Crimp *and* solder a crimp connector? Good? Bad? Why?

[george graves]

For connectors that are designed from the get-go to be crimped, what's the harm to soldering them as well? I've heard the rule, and usually stick to it.  But I don't know the reason behind it, or the exceptions to the rule(if any).

I assume there is going to be a small about of solder to creep up into the strands and reduce flexibility. What's the failure mode for that?  If the flexibility isn't needed?  But actually, I ask assuming a automotive or vibration environment.  (Surely a static environment it would be fine?)

And does that answer change on the gauge of the wiring?  Say something like 22 gauge vs 0 gauge where there is almost no flexibility in a 0 gauge wire anyways?

[coppice]

There isn't going to be a little solder wicking up the strands. There is going to be a lot. You can attach a heat sink to the stranded wire as you solder, to reduce the wicking effect, but you can't really stop it. The result is a wire that breaks after a few flexes. If you have crimped properly, forming cold welds between a clean wire and a clean terminal, the joint will be more reliable that solder by some orders of magnitude. If you crimp poorly, and just squeeze everything together, don't expect good results.

[TopLoser]

I've never done it because the soldering operation melts the insulation that you have just clamped as part of the crimping operation, compromising the mechanical strength. Plus it may change the state of the insulation, making it brittle or soft. Plus the obvious wicking of the solder up the strands making the wire less flexible.

Lots of bads in my opinion.

[tautech]

There isn't going to be a little solder wicking up the strands. There is going to be a lot. You can attach a heat sink to the stranded wire as you solder, to reduce the wicking effect, but you can't really stop it. The result is a wire that breaks after a few flexes. If you have crimped properly, forming cold welds between a clean wire and a clean terminal, the joint will be more reliable that solder by some orders of magnitude. If you crimp poorly, and just squeeze everything together, don't expect good results.

+1
You nailed it perfectly coppice, a properly done compression weld can't be beat.

[penfold]

Hi,

For short term or regularly maintained equipment then its really not so much of a bother, additional soldering would guarantee a better INITIAL joint.

However, the idea behind crimping is that it should be done so that there is sufficient pressure between all of the metallic surfaces that it slowly 'cold welds'. This is not an instantaneous process and takes a little time for the processes to happen.

If you add solder to the voids (we'll assume that the actual metal-metal contact region is so tight that no solder will leach in to it), then as the assembly heats and cools (and thus expands and contracts) the solder will provide a region which expands for tends to separate the nice clean metal-metal region or disturbs the natural movement of the metals.

Crimping contacts eliminates the use of solder which will wick up wire strands and provide an excessive rigid patch which degrades the flexibility and strain tolerance of the wire. The crimp contacts are of course higher maintenance and require more cleanliness whereas the solder is just more forgiving but requires more strain relief, the world seems to have done in the direction of crimping because they are better suited in batch production scenarios and so connectors are optimised for crimped terminals and so might not provide as much strain relief where necessary

[German_EE]

Look at it this way, the wire connections in a spacecraft (which is probably the highest vibration environment you will find) are crimped and not soldered. Crimping works if you use the right tools and is ultra reliable, soldering will decrease this reliability.

[Circlotron]

Maybe the worst thing you can do is tin stranded wire with solder and then crimp it. (or clamp it in a screw terminal for that matter). It will definitely loosen.

[calzap]

For building wiring in the US and (I think) Canada, connections must be mechanically strong without soldering.  Then solder can be applied, but there is a risk an inspector won't pass it because once solder is applied, it may be impossible to know whether the connection would be strong without it.  In most jurisdictions, it is OK to use exothermic welding to join wires to ground rods or Ufer grounds; however, I've seen pictures of exothermic welds that cracked long after the work was done and inspected.

I'm not sure what rules UL or other certifying organizations apply to connections of free-standing, mains-voltage (or higher) wires inside electrical devices.   I've seen only crimp connectors or wire nuts without solder.

Mike in California

[Fraser]

In the automotive industry, crimp is king. BUT you do have to to watch out for moisture ingress causing corrosion and intermittent connections. I have also noted that the heavy load cable terminations in buildings are crimped so there must be confidence in the crimp method when subjected to very high currents. No solder to be seen on those connections.

Fraser

[CatalinaWOW]

I think Penfold nailed the fundamental reliability issue.  Flexibility and insulation effects are real, but not critical in all environments. 

[C]

Wire_wrap is a type of compression connection
https://en.wikipedia.org/wiki/Wire_wrap

Wire wrap construction can produce assemblies which are more reliable than printed circuits: connections are less prone to fail due to vibration or physical stresses on the base board, and the lack of solder precludes soldering faults such as corrosion, cold joints and dry joints. The connections themselves are firmer and have lower electrical resistance due to cold welding of the wire to the terminal post at the corners.

Note that a proper wire_wrap connection has many compression points, and maintains pressure on the  compression points.

Insulation-displacement connector
[urlhttps://en.wikipedia.org/wiki/Insulation-displacement_connector][/url]

When properly made, the connector blade cold-welds to the conductor, making a theoretically reliable gas-tight connection

Notice that a lot of automotive connectors add some sealing on connector assembly.

A gas tight compression is best, followed by compression & sealing, then compression. 
Solder is way down the list. And as others have stated will increase the failure rate of a compression connection.


C

[nctnico]

Soldering after crimping is not done. Actually a solder joint is several magnitudes worse than a crimped connection! A solder joint will fall apart under vibration/mechanical stress.

[DanielS]

A solder joint will fall apart under vibration/mechanical stress.

An unsupported crimp will fail on fairly short notice too.

[CatalinaWOW]

In the military equipment industry both solder and crimp joints are used.  I don't actually know which is more reliable, but when properly implemented both can meet standards for life in extreme shock and vibration environments.  The difference in reliability may be moot.  Kind of like designing a heart pacemaker for a 200 year lifetime, such a device's life will never be exercised.   

[nctnico]

Run a high current through a solder joint and a 6.3mm spade connection and notice the difference. There is a good reason why they use anything but solder joints for wiring in equipment which needs to have a long service life.

[CatalinaWOW]

Run a high current through a solder joint and a 6.3mm spade connection and notice the difference. There is a good reason why they use anything but solder joints for wiring in equipment which needs to have a long service life.

Makes sense to me that solder joints are less satisfactory for high current applications.  Don't know if I would generalize to say that solder is not satisfactory for long service life in applications where resistive heating of the joint is unlikely to be significant.

As an example, in radios manufactured in the 1920s and 1930s, failing solder joints are way down the list of what is found wrong.  The list runs through bad tubes (valves), failed or drifted capacitors, failed or drifted resistors, bad sockets, failed insulation on wires and somewhere well after that solder joints.  90-100 year service life seems adequate for most applications.

[coppice]

In the military equipment industry both solder and crimp joints are used.  I don't actually know which is more reliable, but when properly implemented both can meet standards for life in extreme shock and vibration environments.  The difference in reliability may be moot.  Kind of like designing a heart pacemaker for a 200 year lifetime, such a device's life will never be exercised.

The military does indeed use a lot of soldering and a lot of crimping. They are, however, very particular about where each is used. You would, for example, never be allowed to solder to a multi-strand wire.

[donmr]

I agree that a good crimped connection is the best, but that assumes it was done with the proper equipment, a trained operator and that everything is calibrated and periodically tested.  For home hobby applications I don't usually have all of that and I tend to solder a lot of connections after crudely crimping them.

[nctnico]

In the military equipment industry both solder and crimp joints are used.  I don't actually know which is more reliable, but when properly implemented both can meet standards for life in extreme shock and vibration environments.  The difference in reliability may be moot.  Kind of like designing a heart pacemaker for a 200 year lifetime, such a device's life will never be exercised.

The military does indeed use a lot of soldering and a lot of crimping. They are, however, very particular about where each is used. You would, for example, never be allowed to solder to a multi-strand wire.

And appearantly for a good reason. Over the years I have restored several HP power supplies from the 80's and in many cases I could pull the multi-stranded  wires (including those carrying mains!) from the boards without much force. Part of the restoration is to fixate the wires with hot-melt as a strain relief after resoldering them.

[DanielS]

Run a high current through a solder joint and a 6.3mm spade connection and notice the difference.

What do you use to secure your spade-to-PCB connectors to the PCB side of the connection? Most likely solder.

If soldering was a no-go for high-vibration environments, there wouldn't be a ~300 pages long NASA standard about how to tin wires and soldering in general for aerospace applications.

[mos6502]

If properly done, reliability of crimp and solder joints is equal.

E.g., check this out:

"Solder-style splices produce a smaller, more compact splice
termination, with significant weight reductions over crimp-style splices."

http://www.hq.nasa.gov/office/codeq/doctree/87394.pdf

Would they do that if it was unreliable?

[eneuro]

http://www.hq.nasa.gov/office/codeq/doctree/87394.pdf
Would they do that if it was unreliable?

Thanks, for this nice NASA document 

Anyway, for 230VAC mains on welder transformer primary I will have a chance to debunk this solder "disaster" myths, since one of connectors (5mm wide ~2.5mm2 strand wire) is only crimped and protected with thermal heatshrink, while another one like this below was the same of course strand wire, crimped, added thermal heatshrink, then from front a little bit of 1mm solder applied, but in a very controlled way-I mean lets say 5mm-10mm, so while it was heated from connector side, copper wire conducted heat and solder penetrated inside strand wires througth crimped connector, but of course we have full controll how much solder will go inside and while solder like heat it will fill connector side better than opposite side, i guess:



We'll see what happends at currents between 15A-20A (below home mains grid circuit breaker 25A), but I do not expect any harmfull flex and huge vibrations and I do not know, it looks like, while solder filled empty space between strand wire, shouldn't it create even lower resistance, assuming there wer eno extreme solder temperatures and whol eprocess was only a few seconds long? 
Visual inspection of this connector seams to better protect inside wire from external erosion, than when no solder joint is created from connector side... 

Maybe, to debunk this theory, will be better put such terminated wires on welder transformer secondary, than slowly increase welding current and see which fail sfirst at which current level, but I exepct that strand wire itself fails first rather than this connector with added small amount of solder 

Update: Probably not best example of controled solder filling, while seams to me that mayb ea little bit too much solder was added, but idea remains the same... other connectors made thi sway doesn't have this bulb where connector crimp ends-there were too much solder , I guess...

[KD0CAC John]

There are multiple reasons for doing or not doing something but when it comes to electrical connections , I ask the question is any chance of regular movement / flexing .
If so , then crimp , if not - soldering is OK .
This is from 50 + yrs. of automotive , truck , motorcycle etc.
What I have seen happen is there is movement , vibration or flexing , a soldered connection has a high failure rate from metal fatigue at the point of the solder .
I did a lot of mobile work and learned to try to reuse some crimp connectors battery and others , many times the dimple crimp for the most common type of crimp connector , would cut some of the strands when you get just enough pinch in the dimple to keep from pulling apart .
Then when computers enter cars I saw for the 1st time what I call a double row crimp , this is a true die where one half of the die is a half round and the other side of the die is made of 2 half rounds that are closer than half round and have a sharp point  between that does not reach all the way through that half of the die , this sharp point is meant to meet the seam of a crimp connector and each grabs and raps around half the strands .
After the lack of a picture and not quite 1,000 words
I have not seen one of these fail - if done correctly .
I ended up buy off the Snap On truck a 3 foot long crimper like this for battery connection , and welder cable .
I uncrimped a few of these by putting the crimp fitting in a vice and used a small punch to spread the 2 rap around parts open and with none of the strands captured by any of the crimp , I found that the some of the strands were acutely fused to the surface of the open crimp fitting .
So my reasoning for having enough crimpers of this style to do almost all sizes of wire and cable .   

[AF6LJ]

If properly done, reliability of crimp and solder joints is equal.

E.g., check this out:

"Solder-style splices produce a smaller, more compact splice
termination, with significant weight reductions over crimp-style splices."

http://www.hq.nasa.gov/office/codeq/doctree/87394.pdf

Would they do that if it was unreliable?

I use to have a hard copy of that document, thanks for posting that...
Back into the library it goes.

The largest single problems with crimping are;
The wrong terminal is used.
The wrong tool is used.
The technician / assembler is not properly trained in the use of the tools or preparation of the wires to be crimped.

As someone who has crimped a few miles of connections, it is in many cases as hard or harder to master than soldering.

[DanielS]

From what I remember of the NASA document I have skimmed, the main problems with solder connections are copper embrittlement from using the wrong type of solder or flux for the connections being made and contaminated solder.

[coppice]

Run a high current through a solder joint and a 6.3mm spade connection and notice the difference.

What do you use to secure your spade-to-PCB connectors to the PCB side of the connection? Most likely solder.

If soldering was a no-go for high-vibration environments, there wouldn't be a ~300 pages long NASA standard about how to tin wires and soldering in general for aerospace applications.

Soldering is not a no-go for high vibration environments. It is used all the time. It is used in specific ways, though. If the solder is requirement to provide no mechanical strength, and simply provides a conductive infill, it works fine. As soon as you expect any mechanical strength from it you are in trouble. Even the minor mechanical strength required to hold a DIP pin in a plated through hole can be problematic. The holes are made as small as possible, so there is the minimum possible space between the pin and the hole.

[coppice]

If properly done, reliability of crimp and solder joints is equal.

E.g., check this out:

"Solder-style splices produce a smaller, more compact splice
termination, with significant weight reductions over crimp-style splices."

http://www.hq.nasa.gov/office/codeq/doctree/87394.pdf

Would they do that if it was unreliable?

The technique is neither reliable nor unreliable. Context is everything. If the splice is in a position where is will not be flexed frequently or be subject to vibration (e.g. inside a lot of NASA ground equipment) a well executed soldered splice will work fine, even on stranded wire.

[CatalinaWOW]

A refrain that needs to be played over and over again, in every context there is. 

Something that is employed properly and executed well works.  Anything short of that can turn out poorly, though even here you can get lucky.  Sometimes more often than not.

The comments in this thread have been helpful in the proper employment part of the equation.

[eneuro]

Run a high current through a solder joint and a 6.3mm spade connection and notice the difference. There is a good reason why they use anything but solder joints for wiring in equipment which needs to have a long service life.

Makes sense to me that solder joints are less satisfactory for high current applications. 

Myth buster time comes 
I want to compare today two connection types: crimped and filled with solder to glue everything VS crimped only-both of them covered with thermal heatshrink 
Those connectors will be in series on huge welder transformer secondary  and slowly current will be raised until.... we'll  see strand wire insulation disapear and then lets see which connector fails first or pobably wire itself, I bet   

[george graves]

Thanks for all the info!

Regarding wire to wire joints,  I will add, that I think the military (and maybe some aviation?) they might be keen to use crimps as with the right tool, they are more-or-less monkey proof.  Where soldering requires a lot more training/experience.

Second question:  Is there any solder that it's flux is so corrosive that when it wicks into stranded wire it will actually eat up the copper over the course of a few years?  I know someone that says he see it on a regular basis.  He installs car stereos for a living(so take that with a grain of salt) - and I'm assuming he's seeing people use copper pipe solder for electrical work.  Anyone else run into this?

[wraper]

Second question:  Is there any solder that it's flux is so corrosive that when it wicks into stranded wire it will actually eat up the copper over the course of a few years?  I know someone that says he see it on a regular basis.  He installs car stereos for a living(so take that with a grain of salt) - and I'm assuming he's seeing people use copper pipe solder for electrical work.  Anyone else run into this?

Yes it's quiet common to happen.

[DanielS]

Myth buster time comes 
I want to compare today two connection types: crimped and filled with solder to glue everything VS crimped only-both of them covered with thermal heatshrink 
Those connectors will be in series on huge welder transformer secondary  and slowly current will be raised until.... we'll  see strand wire insulation disapear and then lets see which connector fails first or pobably wire itself, I bet   

The solder will melt before the wire fails. Some interesting things might happen once solder starts dripping out of the joint. For high-temperature connections, you want to use spot/fusion welds, crimps or appropriate screw hardware until you get out of the hot zone.

Second question:  Is there any solder that it's flux is so corrosive that when it wicks into stranded wire it will actually eat up the copper over the course of a few years?

Plumbing acid flux. That stuff is intended to clean off most of the junk of the surface of solid copper pipes. It does not really harm the pipes since they are 1/16" thick (over 1mm) but on fine multi-strand wires, the wires might be gone in less than a year.

[nctnico]

Plumbing acid flux. That stuff is intended to clean off most of the junk of the surface of solid copper pipes. It does not really harm the pipes since they are 1/16" thick (over 1mm) but on fine multi-strand wires, the wires might be gone in less than a year.

Actually you are supposed to whipe the pipes clean after soldering!

[eneuro]

Myth buster time comes 
I want to compare today two connection types: crimped and filled with solder to glue everything VS crimped only-both of them covered with thermal heatshrink 
Those connectors will be in series on huge welder transformer secondary  and slowly current will be raised until.... we'll  see strand wire insulation disapear and then lets see which connector fails first or pobably wire itself, I bet   

The solder will melt before the wire fails.

I can't wait to test this, while I do not believe in that 

What about connect this 2.5mm2 strand wire to... 2.5kW spot welder secondary with hundreds of amps of short circuit current? 

Yep, I like this idea-I will start from 1 mains period pulses (20ms) util wire insulation disapears and series connection fails 

[calzap]

I think the main reason solder is not allowed to be the mechanical connector for building wiring is because it may melt in a high or over current situation, especially in a warm environment (junction box on a roof-top or in an attic, for example).  In an over-current situation, this might occur before an inverse time breaker (the usual kind) trips.  Think of a solder joint as a fusible link.  In addition to the circuit going dead,  dripping solder and wires springing apart can cause all sorts of mischief.

Acid flux (plumbing flux) can indeed corrode stranded wire rapidly; I've seen examples.  The main reason copper or brass pipes survive acid flux is their mass.  Wiping the joint after soldering is mostly for cosmetic reasons and to allow the inspector to see the joint better.  Many plumbing fluxes are in a petroleum jelly matrix, and wiping just spreads the residual flux further down the pipe and onto the outer surface of the fitting.  Besides you can't wipe the inside of the pipe or fitting in most situations.  Water flow  may wash away some of the acid  inside, but many pipes have little or no water moving through them (vents, compressed air distribution, etc.).  The  only disastrous corrosion I've seen in copper pipes is when they are used as drain pipes and subjected to all sorts of chemicals over the years or at sharp bends (causes turbulence) in systems that run continuously, like hot water re-circulation systems.

Mike in California

[penfold]

The only problem with solder in those environments is because of the safety factors and already the conductors are already designed to get pretty warm at peak current so a lot of thermal cycling will not be doing it any favors.

In high reliability environments the use of solder in multi-strand wires is discouraged because it limits the natural flex of the cable strands which requires bit more strain relief in the cable. It is not necessarily true that it will always do this, but it is practically impossible to prove that the solder has not wicked up the center of the wire whereas a crimp is pretty easy to test. The additional strain relief in soldered junctions means additional weight which for the aerospace industry is a big deal and it just so happens that they are some of the key players who influence the design of high reliability interconnects.

The big deal is with inspectability, some solder joints can be very misleading and the solder itself hides a multitude of sins whereas with a crimp you can quite quickly determine that the wire was of the correct gauge, the correct crimp die has been used and that the correct depth of the wire in the junction has been reached.

[MK]

In a crimped joint done properly, the uncrimped portion of the ferrule in conjunction with the insulation provides a region of steadily decreasing stiffness from the crimp proper all the way out to the unsupported wire, this region where the stiffness steadily decreases is what will make that connection more resistant to vibration than a soldered joint where the solder backfills the wire out to the unsupported region thus concentrating all the vibration to that single mm of wire, thus it will fail quicker unless there is never any vibration at all.

[tooki]

Look at it this way, the wire connections in a spacecraft (which is probably the highest vibration environment you will find) are crimped and not soldered. Crimping works if you use the right tools and is ultra reliable, soldering will decrease this reliability.

The military does indeed use a lot of soldering and a lot of crimping. They are, however, very particular about where each is used. You would, for example, never be allowed to solder to a multi-strand wire.

Umm, maybe I'm not understanding your comment, because they certainly do allow soldering of stranded wire. Here's a video series of soldering training to NASA standards, and it begins with soldering stranded wire.

[IanJ]

In my experience, tinned strands which are then crimped can have a tendency to work loose.......not just because of the rigidity factor of the wire leaving the crimp but due to the compressibility of the solder and flux residue.
Over time this can deteriorate and the crimp ends up loose.

Soldering after crimping is a different thing and has it own set of issues/benefits depending on where you solder.

Nothing beats or improves on a properly crimped connection......IMHO.

Ian.

[John Coloccia]

I don't see how solder could improve a crimped joint. A properly crimped joint is already gas tight, and often there are even cold welds that develop, like wire wrap.

[VK5RC]

I read on this forum a comment that resonated with me, a good crimp is often better than a good solder joint BUT a really good crimp joint needs a specific wire,  a specific crimp, a specific tool and a trained crimper operator, you can get pretty close to  that quality solder joint with far less bother. I.E much easier to make a bad crimp than a bad solder joint, but both are possible!

[DanielS]

BUT a really good crimp joint needs a specific wire,  a specific crimp, a specific tool and a trained crimper operator

How much training does a "crimper operator" need to operate a $600 ratcheting or powered crimper and die set? The main reason connector manufacturers produce manual crimpers and die sets tailored to specific connectors and wire gauges is to take as much of the human factor out of the equation as possible so field technicians and engineers can achieve connections comparable to factory crimps with minimal training.

(That and vendor lock-in: the connector manufacturer won't guarantee performance of their parts unless you use their specific dies and the specific crimp tools they were designed for even when you have functionally identical tools or die models in every way which should physically matter.)

[mikerj]

Run a high current through a solder joint and a 6.3mm spade connection and notice the difference.

What do you use to secure your spade-to-PCB connectors to the PCB side of the connection? Most likely solder.

If soldering was a no-go for high-vibration environments, there wouldn't be a ~300 pages long NASA standard about how to tin wires and soldering in general for aerospace applications.

Does that NASA document permit stranded cables to be tinned and soldered when used in high vibration environments?  I suspect not.

[eneuro]

I don't see how solder could improve a crimped joint.

I've some theory behind it-higher conductivity area ~ lower connection resistance 

Preparing welder transformer secondary connector on 6mm in diameter copper strand wire and for testing purposes I've used classic (old) vice , and patent pending  screw cut into two pieces, so when copper pipe was pressed by screw forming  copper connector into circular shape and prewenting flat pressing, I've got decent results:



However (it is not cleary visible) I've made also ~1.5mm hole in front of connector, to be able fill empty space from connector hole side by solder inserted throuught this small hole, while connector is heated from hole side.

I expect, strand small wires soldered to connector from front and not too much penetration to wire after connector since there will be lower temperature, so solder will rather be kept in front of connector.
Additional connection area made with solder this way, I hope, it  will lower down total connector resistance even more and while this wire will not work in high vibration environment I do not expect any flexibility issues-of course thermal heatshrink will improove rigidiity w few centimeters around connector.

I will have a chance test this connection during test welding tomorow and meantime I will make this experiment with 2.5mm2 connectors in crimped vs crimped and soldered version 

[CatalinaWOW]

If any of you have a late 90s Chevy or GMC 4WD vehicle you have probably experienced a failure of the drive selection system.  The problem in every case that I have found is failure of the press fit connections between two circuit boards in the switch.  Presumably these had all of the benefits at assembly, new materials, proper sizes of both sides of the joint, carefully designed pressures and proper tools.  While this is not a crimp joint, it is one form of the same joining concept.  They are touted to be gas tight and occasionally forming cold welds.  They can and do fail if everything is not perfect.

While my solution is not perfect, it has lasted longer than the original connection.  I soldered them.

[TopLoser]

"Presumably"

At that point your argument becomes very much less convincing...

[DanielS]

While my solution is not perfect, it has lasted longer than the original connection.  I soldered them.

When you do not know what the proper connector, die and other specs are, do not have the necessary tools and parts, cannot be bothered to look them up and order, or did but the price is out of the acceptable range for the small quantity you need, soldering is usually better than improvising crimps with whatever you have on-hands.

And every now and then you have cases where mechanical connections fail, like one microwave oven I repaired last year which had a burnt switch. After breaking off the melted and charred connector plastic from the intermittent switch because the connector wouldn't come off, I found that the contacts had also spot-welded themselves to the switch, indicating that they were once loose enough to start an arc.

[ConKbot]

Run a high current through a solder joint and a 6.3mm spade connection and notice the difference.

What do you use to secure your spade-to-PCB connectors to the PCB side of the connection? Most likely solder.

If soldering was a no-go for high-vibration environments, there wouldn't be a ~300 pages long NASA standard about how to tin wires and soldering in general for aerospace applications.

Does that NASA document permit stranded cables to be tinned and soldered when used in high vibration environments?  I suspect not.

Your joint shouldn't be providing mechanical support for the wire that's what the lacing on the harness, back shell clamps and padded p clips are for. And for larger gauge stuff, stranded would hold up better than solid everywhere else anyway.

[Psi]

I don't see how solder could improve a crimped joint. A properly crimped joint is already gas tight, and often there are even cold welds that develop, like wire wrap.

It improves your confidence that it's not going to pull out.

Personally, if your quick about soldering and use a high temp I don't think the solder will wick up the wire fast enough to get past the insulation retention crimp.  Might be a good experiment to try. Tin some wire and time how quickly the solder wicks up the wire. Then crimp the same wire and see how fast you can solder it.

[John Coloccia]

I don't see how solder could improve a crimped joint. A properly crimped joint is already gas tight, and often there are even cold welds that develop, like wire wrap.

It improves your confidence that it's not going to pull out.

If you're worried about the wire pulling out, your crimps are no good. If you don't have complete confidence in your crimps, there's no point crimping. You should switch to some sort of solder cup style connector instead because that will be designed for soldering. The whole point of crimping is to make a gas tight, solid connection. If you only manage to make a crappy connection that "pulls out", or whatever, and you feel it needs to be soldered, isn't it better to use a connector that's designed to be soldered?

But that said, it's absolutely trivial to make a proper crimp with a crimper and the correct dies. None of this is particularly expensive, and you would have to be completely brain dead to mess it up. Just make a couple of test crimps and then yank on them to see what it really takes to compromise it. That should give you a bit of confidence in the technique.

[Psi]

I don't see how solder could improve a crimped joint. A properly crimped joint is already gas tight, and often there are even cold welds that develop, like wire wrap.

It improves your confidence that it's not going to pull out.

If you're worried about the wire pulling out, your crimps are no good. If you don't have complete confidence in your crimps, there's no point crimping. You should switch to some sort of solder cup style connector instead because that will be designed for soldering. The whole point of crimping is to make a gas tight, solid connection. If you only manage to make a crappy connection that "pulls out", or whatever, and you feel it needs to be soldered, isn't it better to use a connector that's designed to be soldered?

But that said, it's absolutely trivial to make a proper crimp with a crimper and the correct dies. None of this is particularly expensive, and you would have to be completely brain dead to mess it up. Just make a couple of test crimps and then yank on them to see what it really takes to compromise it. That should give you a bit of confidence in the technique.

You can be pretty sure the crimp is good if you use the manufacturers tool which usually cost in the $500-$1000 range. The cheap tools "seem" to work fine but are often not the locking ratchet type.

But the only way to be 100.000% sure the crimp was good is to pull it out and see how much force it takes which kind of ruins the joint.

[eneuro]

But the only way to be 100.000% sure the crimp was good is to pull it out and see how much force it takes

I think, you concentrate too much on mechanical strength of such connection, since in many cases, good electrical contact is the main purpose of making those connections 
I see no reasons for brute force mechanical tests of electrical copper wires which are not designed for mechanical loads.

So, to some degree those connections have to be not too loose, but I see no reason stress copper to its limits to see what wins wire or connection-at least all those forces have to be calculated and mechanical forse choosen corectly, not as much force as possible.

In high current welder application for me more important is to do not have power loses higher than in wire itself, so by increasing conductors contact area inside such connector, I see benefit of adding some solder to make perfect fits and remove any air from strand wire.

Watching those few NASA videos, conclusion might be, that we have to always try to clean connection from flux to avoid corrosion, so we want to have clean metals connected (soldered) .
Using additional thermal heatshrinks and antyvibration insulation we can easy limit any solder stres around connected wire.

[mzzj]

I don't see how solder could improve a crimped joint. A properly crimped joint is already gas tight, and often there are even cold welds that develop, like wire wrap.

It improves your confidence that it's not going to pull out.

If you're worried about the wire pulling out, your crimps are no good. If you don't have complete confidence in your crimps, there's no point crimping. You should switch to some sort of solder cup style connector instead because that will be designed for soldering. The whole point of crimping is to make a gas tight, solid connection. If you only manage to make a crappy connection that "pulls out", or whatever, and you feel it needs to be soldered, isn't it better to use a connector that's designed to be soldered?

But that said, it's absolutely trivial to make a proper crimp with a crimper and the correct dies. None of this is particularly expensive, and you would have to be completely brain dead to mess it up. Just make a couple of test crimps and then yank on them to see what it really takes to compromise it. That should give you a bit of confidence in the technique.

You can be pretty sure the crimp is good if you use the manufacturers tool which usually cost in the $500-$1000 range. The cheap tools "seem" to work fine but are often not the locking ratchet type.

But the only way to be 100.000% sure the crimp was good is to pull it out and see how much force it takes which kind of ruins the joint.

And pretty often I found that I have to join slightly different cable sizes. IE 0,75mm2 to 1mm2, 18AWG or 16 AWG. Car electronics seem like worst, gazillion of different wire gauges.

No-name crimp connectors and  assortement boxes are usually not any good, copper is too thin to provide sufficient strenght in the crimp. No-name 60/40 solder works just fine 

Proper crimp should hold more than 50% of the wire breaking strenght, ideally 100% so that the wire should break before cable slips out of the crimp.

[eneuro]

Proper crimp should hold more than 50% of the wire breaking strenght, ideally 100% so that the wire should break before cable slips out of the crimp.

No plans to stress too much my soldered 6mm in diameter strand wire into copper pipe of 8mm in OD and 1.5mm thickness, but when compare this "art" work with what I saw in local market with welding tools and saw ground welder wire crimped with connector in a way, that more than half of strand wire were broken and no chance to weld anything, I'm preaty confident this my connection made in protected with double thermal heatshribk in connector area will be much better. Strand wire insulation was cooled with wet (water) thermal mass close to connector during soldering (only a few seconds enougth to put inside decent amount of solder wire througth 1.5mm hole, than I've put connector from horizontal to vertical position to let solder go down to from connector during cool down).



After soldering cleared this connector with grain alcohol (95%) and after applying thermal heatshrinks it might be not so bad and a way better that this "commercial" investigated during quick teardown in local market with welding tools  It wasn't the cheapiest welder machine, so i was really  what I saw inside this ground connection wire.



BTW: I cost me less than $0.30 to make this connector, since I've used 1.5mm thick 8mm copper pipe and drilled hole for M10 (10mm) screw after smashing half of this pipe in vise and with a little help of hammer   

We'll see during welding how it performs, but I've made connectors for spot welder in similar way and there were no problem what so ever so far 

[mikerj]

But the only way to be 100.000% sure the crimp was good is to pull it out and see how much force it takes which kind of ruins the joint.

Which is the entire purpose of a test crimp.  I used to work for a company that designed and manufactured railway signalling equipment, and a test crimp would be performed every day (per tool) and the result logged.  I don't recall a test ever failing whilst I was there.  Anyone soldering a crimped connection would have had their backsides well and truly kicked.

[eneuro]

Myth buster time comes 
I want to compare today two connection types: crimped and filled with solder to glue everything VS crimped only-both of them covered with thermal heatshrink 
Those connectors will be in series on huge welder transformer secondary  and slowly current will be raised until.... we'll  see strand wire insulation disapear and then lets see which connector fails first or pobably wire itself, I bet   

The solder will melt before the wire fails.

I can't wait to test this, while I do not believe in that 

Crimped vs crimped and soldered 


Batte field: spot welder high current output -no survivors? 


How this happened - raw footage from weak crimped soldered connector wires Myth Buster's scene 


As expected, connectors are fine - failed one of the wires... 


Update: Moment of wire explosion from step by step frames analysis 


Shortly before explosion-it looks like parts of copper flown around at high speed 

[Psi]

I think its more of a perception problem than a physical one.

It's hard to accept that crushing something together is a good way to join it. So we like to fall back to good old soldering.

[DanielS]

It's hard to accept that crushing something together is a good way to join it.

The really big difficulty with crimps is that you need to apply enough pressure to make a solid electrical and mechanical connection but not enough to compromise the cable's mechanical and electrical integrity. Depending on the type of wire and crimp connection, that sweet spot can be very narrow, hence the need for tools specifically designed for them to achieve consistent results.

[CatalinaWOW]

"Presumably"

At that point your argument becomes very much less convincing...

I am not arguing.  It is just an observation.  These are components in new products from a major manufacturer, which while not at the top of quality rankings, is not at the bottom either (and the range from top to bottom in that industry is actually not that broad).  While a presumption is not evidence of any kind, it is usually safe to assume that significant effort was taken to make sure that these things were done properly.   If nothing else the accountants drive it to keep the costs of warranty returns down.

Reading through this thread is almost like watching people discuss religion.  Both crimps and solder have their place.  Both have their strengths and weaknesses.  Both provide excellent service when applied properly.  Both can be botched.

My comment on soldering as a repair for the assembly in question is not an assertion of general superiority of solder.  But I will assert that soldering was the only practical rework process in this case, and suspect that if I did a teardown thread on the subject most would agree.  Fortunately for me, the rework process has proved at least as reliable as the original joint.  Which then leads to what is probably the real issue for the OP and others.  The vendor of many types of equipment will make many of the joints in question.  A proper crimping tool for the application costing $500 to $1000 will be amortized over these joints and is well worth it.  An individual or small shop doing repairs on such a device doesn't have the same economic base, and will look for an alternative that is either already capitalized or which requires no real investment.  Soldering is such an option.  The question then becomes:  Can it be done in such a way as to provide useful service?  Useful may not mean as good as original.  Merely safe, and lasting long enough not to be a bother may be enough.

Useful input from this thread would include care to limit how far up the stranded wire solder is wicked, providing mechanical support for the cable so that flex of the wire near the joint is prevented, and not attempting this type of repair when the application will lead to significant heating of the joint.

[Balaur]

As expected, connectors are fine - failed one of the wires... 

You've just proved that improperly made crimps (i.e. the clamp & wire contraction) failed before the other elements.

[eneuro]

You've just proved that improperly made crimps (i.e. the clamp & wire contraction) failed before the other elements.

Crimped connectors are in the middle, one of the copper wire failed, because of while there were series connection, some part of this circuit had slightly higher resistance than other, and maybe a few single wires lost from whole strand wire was enougth-it failed first, but crimped (and soldered) connectors has no chance to fail first, since inside connector wir eis supported by connector copper and in th ecase of soldered one, we have even lower resistance, so nope, wire must fail first, not connector

In spare time I will make slow motion version of this video, while things go so fast that it looks like nothing happends in the time of wire explosion, but one single frames I've found copper crap flying around 

Wire have no chance to survive with connector in series-because of proper connector (cross section area) with wire inside will always have smaller resistance and wire must fail first-if connector failed it could mean you choosen bad connector 

[Balaur]

You've just proved that improperly made crimps (i.e. the clamp & wire contraction) failed before the other elements.

Crimped connectors are in the middle, one of the copper wire failed, because of while there were series connection, some part of this circuit had slightly higher resistance than other, and maybe a few single wires lost from whole strand wire was enougth-it failed first, but crimped (and soldered) connectors has no chance to fail first, since inside connector wir eis supported by connector copper and in th ecase of soldered one, we have even lower resistance, so nope, wire must fail first, not connector

In spare time I will make slow motion version of this video, while things go so fast that it looks like nothing happends in the time of wire explosion, but one single frames I've found copper crap flying around 

Wire have no chance to survive with connector in series-because of proper connector (cross section area) with wire inside will always have smaller resistance and wire must fail first-if connector failed it could mean you choosen bad connector 

I was half joking:

The wire failed close to the clamp, and I mean by that the ring clamp you used to connect the wire to the spot welder electrodes.
Technically it's a crimp, as it relies on mechanical pressure to create a (cold-weld?) connection.
Since this contraction caused the wire to fail very close to it, creating a particular mode of failure, it's less than ideal.

[Tandy]

What I do when crimping stranded wire is to remove more insulation than needed and tin the end of the wire. Then trim it down so that the solder just acts like a little end cap on the end of the wire. It will help stop moisture getting in between the strands from the ends and also makes pushing the wire into the connector easier as the strands are held together. It can be fiddly if you push the wire in and don't line it up perfect and a couple of strands end up outside the the crimp area.

You don't want solder on the conductor where the crimp goes as the solder would actually act as a sort of lubricant making it easier for the wire to pull out of the crimp joint.

You will find this method used a lot in UK mains plug screw terminals.

[eneuro]

Since this contraction caused the wire to fail very close to it, creating a particular mode of failure, it's less than ideal.

When we analyse where this wire could fail, so it is clear than due to huge thermal capacity of spot welder 15mm in diameter copper pipe, where I've connected those tested wires (pressed from both sides by good conductors, but better from pipe copper side), when this lowest resistance part of circuit started to heat up at high current it was cooled from spot welder connection itself and by rest of the wire to connectors side, so somewhere in the middle (depending on thermal capacity at the edges of the wire) it will fail not at the edge but somewhere between since huge heat gradient concentrates in the middle, not at the ends)

Update: Yep, highest temperature as expected in the middle in one of 30fps frames 



At slower fps speed, even if this is not the greates video quality (old Pentax digital camera) before wire melted its cleary visible hot air around wire.
When we tried pure wire without any connectors in the middle probably it will fail somewhere in the middle due to mentioned higher thermal capacity at the edges connected to spot welder copper pipes.
I will try tomorow brake the same wire without connectors just to see where it fails and make slow motion video instead to see more details when it breaks 

[eneuro]

I've today another experiment using (spot) welder 11Voc and this wire insulation quickly gone into flames and copper wire broken 



I've used my spot welder which has programmed 2 seconds delay to start welding after pressing start/stop button, to be able press hard spot welded pieces or like in this experiment I had 2 seconds to run awa as quickly as possible_i've programmed weld duration for 10 seconds 

Anyway, no special effect this time-it was mounted to welder wires using those crimped and soldered connectors, which as we can see are best surrivors in this disaster-wire insulation quickly changed into fire ball and smoke after broken at high temperature (copper melting point temperature is around 1000*C).

So, another experiment which debunks theory of bad quality of crimped and soldered connectors 

What can I say-NASA rules 

[smile]

I think this would be good addition.

https://hackaday.com/2016/11/03/specifications-you-should-read-the-nasa-workmanship-standards/#comment-4190294

See the guide http://workmanship.nasa.gov/lib/insp/2%20books/frameset.html

The interesting part is they show themselves crimped solder tinned wires.

Here is shot from this manual:



yet state that: "Crimping of ...stranded wire that has been solder-tinned, is prohibited.NASA-STD-8739.4 [4.3.4]"



https://workmanship.nasa.gov/lib/insp/2%20books/links/sections/207%20Butt%20Splices.html

So it means all that marine cable is prohibited from crimping? When infact it's the only right cable type to use for crimping since oxidation is less for such crimps. All cable in washing machines is "solder plated cable", boats too use it. So was NASA really in space with such rules?

[Siwastaja]

By "solder tinned", they must mean wire manually tinned using solder, either in a solder pot or using an iron and solder wire.

This joins the strands together and forms a very brittle structure. Try to crimp that and you'll agree that it's not reliable.

Chemically separately tin coated copper strands is completely different and I don't think that NASA spec refers to that.

[smile]

@Siwastaja "they must mean wire manually tinned using solder, either in a solder pot or using an iron and solder wire."

I wonder what stopped them from saying "manually solder tinned" then?

[smile]

@Siwastaja "This joins the strands together and forms a very brittle structure."

Using 60/40 solder and wrapping a thin copper wire strand around then the wire is solder tinned it, makes a very reliable connection.


It can be used in screw terminal. This is exactly what was done in all electrical outlets in lamps in Europe and in Russia in 80's-90's and it worked OK. AFAIK there were no ferrules back then.

Only now days everyone likes to use these spring action crimper like


But there will be no joint that is "gas free" like everyone point's out with spring loaded tool.

[Siwastaja]

"Solder tinned" is very well understandable IMO. It already contains the "solder" word for extra unambiguity.

Wire you buy with separately chemically tinned strands is not tinned by solder: https://en.wikipedia.org/wiki/Solder

But misunderstanding is always possible and happens no matter how careful you are.

[smile]

"Solder tinned" is very well understandable IMO. It already contains the "solder" word for extra unambiguity.

Wire you buy with separately chemically tinned strands is not tinned by solder: https://en.wikipedia.org/wiki/Solder

But misunderstanding is always possible and happens no matter how careful you are.

Nice info about solder types, so what is used in "chemically tinned strands" if it ain't solder then?
What is used for ferules is it same thing as "chemically tinned strands"?

[Siwastaja]

Using 60/40 solder and wrapping a thin copper wire strand around then the wire is solder tinned it, makes a very reliable connection.

A reliable connection, until you compress it under the screw or crimp; even if the connection between the two resistors remains ok, the connection to the terminal block or the crimped connection will be severely compromised.

It can be used in screw terminal.

No. Never. Ever. Except temporarily, at your own risk .

This is exactly what was done in all electrical outlets in lamps in Europe and in Russia in 80's-90's and it worked OK. AFAIK there were no ferrules back then.

Was done to some limited extend in 1980's yes, and by some DIYers still in the late 1990's, whether it worked "OK" or not depends on what's your definition on "OK". It was outlawed for a very good reason. Does cause fires.

(If you don't have ferrules or crimps available and must put a stranded wire under a screw, then you just do it as-is, trying to be careful to get as many strands under the screw as possible. You do not tin the wire.)

Of course, most likely OK, like most electrical mishaps. If all you do is 10 connections in your entire life, they'll most likely be all ok, and even if one goes bad, it's very unlikely it causes a fire. Just some sparking and a bit of smoke.

It's all about risk management, and the modern electrical code is based on minimizing the risk to very low levels, so that while millions of people die on cancer, and hundreds of thousands in traffic, it's "too much" if one dies in electric shock or electrical fire.

And NASA cares about reliability for obvious reasons.

Solder connection shown in the image is very reliable. When crimped or compressed under a screw, the reliability is orders of magnitude worse.

[Siwastaja]

Meaning of "solder", from Wikipedia:

Solder (/?so?ld?r/,[1] /?s?ld?r/[1] or in North America /?s?d?r/[2]) is a fusible metal alloy used to create a permanent bond between metal workpieces. The word solder comes from the Middle English word soudur, via Old French solduree and soulder, from the Latin solidare, meaning "to make solid".[3] In fact, solder must be melted in order to adhere to and connect the pieces together


So no, factory tinning on strands is not "solder", and has nothing to do with "solder".

But you can always misunderstand. Please just go on.

[smile]

Well but crimping with spring loaded tool like the expensive over 100Eur KNIPEX

does not make gas tight ferrule crimps. Nobody measures wires and crimped result with micrometers against a standard like they should, yet everyone pretends crimp is better then soldered, or crimped then soldered is even worse. Where is only logical that to insert the connector pin into the block you must crimp it first and then solder, not the other way around.

The multitool 97 43 200 A KNIPEX is 130Eur for handle and anywhere between 40Eur and 300Eur for a die set.

Luckily I found that a company in Taiwan makes this similar tool:

KY8161-0010 10pcs Professional Smartcrimper tool kit

http://www.kyptool.com/front/bin/ptdetail.phtml?Part=KY8161-0010&Rcg=5

I wonder who copied who, and if KNIPEX dies would fit it, but at least for most popular set you pay like 90Eur and get 6 dies total where with KNIPEX same set would cost about 500Eur.

The tool is made by few companies

http://www.mactools.com/en-us/Pliers/Wiring-Repair-Pliers/TCT747-KIT/Master-Terminal-Crimper-Tool-Kit-

[wraper]

Cheap ratcheting tools tend to suck. They look OK but crimps they make usually are crap.

I wonder who copied who, and if KNIPEX dies would fit it, but at least for most popular set you pay like 90Eur and get 6 dies total where with KNIPEX same set would cost about 500Eur.

These tools are very different. Except the general shape, I barely see anything common in them.
Crimp made in the end of the video looks like crap. Crimps the same connector I make with knipex multicrimp look much neater. And connector got bent along, it's no longer straight.

The tool is made by few companies

No, it is a cheap tool made by one company and rebadged with different brands.

[wraper]

Well but crimping with spring loaded tool like the expensive over 100Eur KNIPEX
does not make gas tight ferrule crimps.

Where this assumption comes from?

Nobody measures wires and crimped result with micrometers against a standard like they should, yet everyone pretends crimp is better then soldered, or crimped then soldered is even worse. Where is only logical that to insert the connector pin into the block you must crimp it first and then solder, not the other way around.

Solder penetrates into the wire and makes it fragile. If vibration is present, wire may just break near to connector. Flux, which penetrates between the strands as well, may cause corrosion, especially in high humidity conditions.

[nctnico]

It can be used in screw terminal. This is exactly what was done in all electrical outlets in lamps in Europe and in Russia in 80's-90's and it worked OK. AFAIK there were no ferrules back then.

NOOO! Never ever use tinned strands in a srew terminal. The solder will be pushed out and the connection will become bad.
Besides that the solder joint will get bad after 20 to 30 years. You can pull it apart very easely. Crimping OTOH is a cold welding process which doesn't degrade so quickly over time.

[smile]

Crimp made in the end of the video looks like crap.

The KNIPEX crimp also looks like crap in their own demo video, how do you explain this?

[Mr. Scram]

Look at it this way, the wire connections in a spacecraft (which is probably the highest vibration environment you will find) are crimped and not soldered. Crimping works if you use the right tools and is ultra reliable, soldering will decrease this reliability.

It's high vibration, but only for a short while. An aerospace engineer once told me they basically design everything to withstand the first 90 seconds of vibrations or so from a mechanical point of view. After that, everything is smooth sailing. Obviously, that's going to impact the kinds of failures you are and aren't going to see.

[smile]

@wraper
"Where this assumption comes from?"

From the fact that the tool is spring loaded, you can even adjust the crimp force by turning the adjuster.
Only Hydraulic crimpers that have few tons of force will make air tight crimps, and ferules they use are way different, they are very thick.

[wraper]

The KNIPEX crimp also looks like crap in their own demo video, how do you explain this?

Connector was too small small for the wire used. Video is not clear enough to see how strands were crimped, but it's obvious this connector cannot fully enclose insulation of this wire regardless of the tool used.

[smile]

Look at it this way, the wire connections in a spacecraft (which is probably the highest vibration environment you will find) are crimped and not soldered. Crimping works if you use the right tools and is ultra reliable, soldering will decrease this reliability.

It's high vibration, but only for a short while. An aerospace engineer once told me they basically design everything to withstand the first 90 seconds of vibrations or so from a mechanical point of view. After that, everything is smooth sailing. Obviously, that's going to impact the kinds of failures you are and aren't going to see.

Well obviously said that if you solder a crimped connection you should make a shrink tube type stress relief on every wire.

[wraper]

Look at it this way, the wire connections in a spacecraft (which is probably the highest vibration environment you will find) are crimped and not soldered. Crimping works if you use the right tools and is ultra reliable, soldering will decrease this reliability.

It's high vibration, but only for a short while. An aerospace engineer once told me they basically design everything to withstand the first 90 seconds of vibrations or so from a mechanical point of view. After that, everything is smooth sailing. Obviously, that's going to impact the kinds of failures you are and aren't going to see.

Well obviously said that if you solder a crimped connection you should make a shrink tube type stress relief on every wire.

And from my experience I can say that heatshrink somewhat mitigates the issue but it still remains.

[Mr. Scram]

Well obviously said that if you solder a crimped connection you should make a shrink tube type stress relief on every wire.

I'm not sure what you're trying to say, but neither he, nor I, did state anything of that nature.

[smile]

I can say that Engineer PA-09/PA-21 or PAD series crimps better than KNIPEX own video.
http://tech.mattmillman.com/info/crimpconnectors/

But you must agree that Engineer crimps are not airtight. As such if Japan crimp tool can't replace OEM and the OEM costs 300-500Eur for single piece of die, then crimping its crazy nonsense if you are not a factory.

[wraper]

@wraper
"Where this assumption comes from?"

From the fact that the tool is spring loaded, you can even adjust the crimp force by turning the adjuster.
Only Hydraulic crimpers that have few tons of force will make air tight crimps, and ferules they use are way different, they are very thick.

Few tons you say? Tons do not mean anything without knowing area they are applied to. Such crimpers are used for very large crimp connectors, pressure applied to the unit of area might be even smaller than in ratcheting hand crimper. If you will apply tons of pressure onto small connector, metal will just squeeze out from both ends.

[wraper]

I can say that Engineer PA-09/PA-21 or PAD series crimps better than KNIPEX own video.
http://tech.mattmillman.com/info/crimpconnectors/

But you must agree that Engineer crimps are not airtight. As such if Japan crimp tool can't replace OEM and the OEM costs 300-500Eur for single piece of die, then crimping its crazy nonsense if you are not a factory.

I own PA-09 and can say it's a piece of crap. Very unreliable tool. I even filed it a bit, so it could close tighter. Crimps it made were very loose and wire often could be pulled out of connector easily, with applying minimum force.

[smile]

my hats off to anybody showing a ratcheting KNIPEX crimper cut cross section like in photo you show for typical connectors. I'm very interested in this tool

because it's somewhat universal and that makes it cheaper. Just remember for photo to be like in the image above you AFAIK should waterjet cut it. Cutting with hacksaw will make false sense of wires welded together.

[vk6zgo]

Just adding my 2 cents worth.

Over many years, I have seen plenty of crimped connections breaking off just behind the crimped part.
These were supposedly "properly crimped with the correct tool", as they were factory jobs.

Automotive ones seem to be the worst, as they don't seem to provide enough support for the wire.
It seems that the clamp which is supposed to crimp around the insulated part of the wire during the process doesn't close tightly enough.

The repair has been to solder the connector, with  in every case, a longer resultant life time than the original.

I have also seen crimp connector failure in Broadcast Transmitters & other such equipment.
Again, in many cases, the answer has been replacement with a soldered lug, due to not having the correct tool or lugs, & needing the equipment restored to service ASAP.
 
Even with the correct tool & crimp connectors, it is sometimes difficult to find enough length of cable to re crimp, as the conductors & insulation have often been "cooked" due to the fault.

Trying to crimp stranded cables which have been  over heated is a recipe for disaster, so in some cases, it is necessary to splice a new section of wire in place.
At this point, if it is at all viable, it is best to make up a new cable entirely, with properly crimping & stress  relief at both ends.

A good crimp connection is very good indeed, but a bad one is an invitation to trouble.
The  thing is, if manufacturers can't get it right, what chance has someone with an "El Cheapo" crimper off the Internet?

[smile]

Just adding my 2 cents worth.

A good crimp connection is very good indeed, but a bad one is an invitation to trouble.
The  thing is, if manufacturers can't get it right, what chance has someone with an "El Cheapo" crimper off the Internet?

None i suppose, except solder crimped connection and make proper stress relief.

[smile]

I too have seen very many failed factory crimped connection in automotive stuff. They do not use proper factory tin plated wire, and they do not use any sort of grease to protect the crimped wires from oxidation relying on the imaginary gas tight myth to work in their favor. Well somehow this makes bad results after connection oxidizes.

[smile]

But still even if you agree on soldering after crimping that still has one problem, what multi crimper to use. Nobody want's crap tools, and since Engineering brand was said to have terrible quality then what's left? Are you sure this was not quality issue with your item, did you contact manufacturer what did they say?

[mikerj]

I too have seen very many failed factory crimped connection in automotive stuff. They do not use proper factory tin plated wire, and they do not use any sort of grease to protect the crimped wires from oxidation relying on the imaginary gas tight myth to work in their favor. Well somehow this makes bad results after connection oxidizes.

You are making many false assumptions.  A correctly formed crimp, whether performed by a hand tool or a hydraulic tool forms a gas tight, cold welded connection.  Not only does this avoid vibration problems, it also forms a lower resistance than a soldered connection.  If you doubt this, then you'll have to explain why the vast majority of safety critical applications use crimps rather then solder. 

I used to work for a company making railway signalling systems, and we had systems with many hundreds of special fail safe signalling relays, all hand wired using crimped connections.  Each crimp tool would be tested every day by forming a crimp which would be inspected and pull tested.

Even a gas tight connection will eventually succumb to corrosion if exposed to moisture, why do you suppose that external connectors on cars tend to be sealed?

[nctnico]

I can say that Engineer PA-09/PA-21 or PAD series crimps better than KNIPEX own video.
http://tech.mattmillman.com/info/crimpconnectors/

But you must agree that Engineer crimps are not airtight. As such if Japan crimp tool can't replace OEM and the OEM costs 300-500Eur for single piece of die, then crimping its crazy nonsense if you are not a factory.

I own PA-09 and can say it's a piece of crap. Very unreliable tool. I even filed it a bit, so it could close tighter. Crimps it made were very loose and wire often could be pulled out of connector easily, with applying minimum force.

I agree. You need a crimper with a ratcheting mechanism. These can apply the correct pressure due to their construction. The cheap ones are in the $50 ballpark though and you'll need the right one for a particular type of contact.

[tooki]

…and you'll need the right one for a particular type of contact.

Indeed. I think one of the big problems with cheap Chinese crimpers (aside from the huge variability in quality) is that the descriptions are so vague, with no specs to speak of, that you don't know whether you've actually got the right tool for the connectors in question.

For example, the various "Dupont" crimpers and terminals you get on eBay vary from totally compatible to totally incompatible. They look OK at first glance, but in fact they may not be designed for each other, and the wrong combination produces terrible crimps.

[smile]

You are making many false assumptions.  A correctly formed crimp, whether performed by a hand tool or a hydraulic tool forms a gas tight, cold welded connection.  Not only does this avoid vibration problems, it also forms a lower resistance than a soldered connection.  If you doubt this, then you'll have to explain why the vast majority of safety critical applications use crimps rather then solder.

1.hand tool...forms a gas tight, cold welded connection.
Well I would like to see such demonstration video, not some advertisement either.

2.If you doubt this, then you'll have to explain why the vast majority of safety
critical applications use crimps rather then solder.

When you consider savings on not having to make OSHA proper soldering work places in a factory for every worker, not having to make trainings, saved money on solder itself, last time I checked it was not cheap.

The crimp method is better in factory, not for DIY or electronics hobby like were here do. I thought thread title reflects this.

"Crimp *and* solder a crimp connector? Good? Bad? Why?"

Good? - better connection (lower resistance) then simply crimped
(I'm not taking into account proper 500Eur crimp tools here)
Bad? - yes can be bad if proper strain relief is not made
Why? - because DIY and hobby electronics still demands for proper low resistance reliable connections. And you can make them either with 500Eur crimp tools, or soldering the connection after crimping with say Engineer PA-09/21.

The resistance for this soldered vs. factory 500Eur crimp tool made connection will be the same.

[smile]

Another thread has some valuable input to the topic.
https://www.ericthecarguy.com/kunena/9-ETCG-Suggestion-Box/52531-solder-vs-crimp

quote:

"I work in the aerospace industry (think launchpads, not runways) and we use crimps and soldered joints fairly interchangeably. Initial assembly and bench-work is typically soldered. Yet while making repairs or modifications on the spacecraft, we use crimp connections almost exclusively. This is because it's easy to reproduce a functional joint in difficult to reach places, or from uncomfortable working positions.

The crimpers I use at work span many brands and are routinely calibrated by our in house metrology lab."

Few posts above I was told that small crimp connectors should be more easily made gas tight because of small area right, metals should fuse together etc.
Now to verify this I took a bunch of factory crimped (with proper tools I suppose) connectors from computers and a scalpel, I dissembled the connectors without much effort, the strands were not fused together or to the connector. It's actually strange that wires pull out so easy once you know how to release them.

[wraper]

I can say that Engineer PA-09/PA-21 or PAD series crimps better than KNIPEX own video.
http://tech.mattmillman.com/info/crimpconnectors/

But you must agree that Engineer crimps are not airtight. As such if Japan crimp tool can't replace OEM and the OEM costs 300-500Eur for single piece of die, then crimping its crazy nonsense if you are not a factory.

I own PA-09 and can say it's a piece of crap. Very unreliable tool. I even filed it a bit, so it could close tighter. Crimps it made were very loose and wire often could be pulled out of connector easily, with applying minimum force.

I agree. You need a crimper with a ratcheting mechanism. These can apply the correct pressure due to their construction. The cheap ones are in the $50 ballpark though and you'll need the right one for a particular type of contact.

The issue was not pressure as such, although it's important. Dies didn't close tight enough, so crimps, especially of smallest sizes, were very loose regardless of pressure applied.

[wraper]

I did not say that wires are fused together. About being airtight, look into compression fittings. They produce sealed connections without any rubber o-rings. Metal is just pressed together, nothing gets fused.

[Psi]

I've been crimping AWG16 into female pins and then soldering them for 4 years in a product and have never had any fail.
The connector is the same kind as computer ATX plugs, just less pins

[coppice]

I've been crimping AWG16 into female pins and then soldering them for 4 years in a product and have never had any fail.
The connector is the same kind as computer ATX plugs, just less pins

If the joints are not flexed or vibrated in service you'll usually get away with doing that, especially if you took some action to minimise wicking during the soldering. That doesn't make it a preferred solution.

[coppice]

Another thread has some valuable input to the topic.
https://www.ericthecarguy.com/kunena/9-ETCG-Suggestion-Box/52531-solder-vs-crimp

quote:

"I work in the aerospace industry (think launchpads, not runways) and we use crimps and soldered joints fairly interchangeably. Initial assembly and bench-work is typically soldered. Yet while making repairs or modifications on the spacecraft, we use crimp connections almost exclusively. This is because it's easy to reproduce a functional joint in difficult to reach places, or from uncomfortable working positions.

The crimpers I use at work span many brands and are routinely calibrated by our in house metrology lab."

Few posts above I was told that small crimp connectors should be more easily made gas tight because of small area right, metals should fuse together etc.
Now to verify this I took a bunch of factory crimped (with proper tools I suppose) connectors from computers and a scalpel, I dissembled the connectors without much effort, the strands were not fused together or to the connector. It's actually strange that wires pull out so easy once you know how to release them.

The guy being quoted implies he either works in missiles or space vehicles. In both those cases the vibration levels are phenomenal. So much so that lots of materials can't be used for insulation because the vibration liquifies them. The first lesson you learn in soldering is you should always avoid using solder for structural purposes. In high vibration environments you have to take this policy to an extreme. Everything has to be pretty tight and solid before any solder is applied. Solder is so soft and low melting point that it can liquify under high vibration if there is any significant thickness of solder between the mating parts. Every electrical joint, and piece of insulation, is considered with great care in missiles. Anything without a proven track record is generally prohibited, and needs to build a track record outside actual missiles. There are no joint types which are freely interchanged.

[tooki]

My understanding is that adding solder to a good crimp basically gives you all the disadvantages of both, and negates their respective advantages, making it a big no-no. I think that often, people are adding solder to a bad crimp and seeing an improvement, which may be the case, but that’s because it’s a bad crimp. If you can’t get good crimps, then you should just forget the crimping altogether and use connectors with solder cups or lugs instead.

[coppice]

My understanding is that adding solder to a good crimp basically gives you all the disadvantages of both, and negates their respective advantages, making it a big no-no. I think that often, people are adding solder to a bad crimp and seeing an improvement, which may be the case, but that’s because it’s a bad crimp. If you can’t get good crimps, then you should just forget the crimping altogether and use connectors with solder cups or lugs instead.

If you have crimped properly, solder can't get into the actual crimped area, so it can't affect the actual crimp. The main problem with soldering after crimping is wicking. Most crimping is of multi-strand wires. Solder is drawn between the strands for a considerable distance, just as wax is drawn up a candle wick. Where that solder ends you have a point where often just a few wiggles of the wire will cause a fracture. So, the solder wrecks the benefits of crimping, but crimping doesn't have any drawbacks compared to solder, unless you have a poor crimping technique which you can't rely on.

[Psi]

I've been crimping AWG16 into female pins and then soldering them for 4 years in a product and have never had any fail.
The connector is the same kind as computer ATX plugs, just less pins

If the joints are not flexed or vibrated in service you'll usually get away with doing that, especially if you took some action to minimise wicking during the soldering. That doesn't make it a preferred solution.

yeah, just a touch of solder, i don't let it wick up past the insulation crimp

[wraper]

I've been crimping AWG16 into female pins and then soldering them for 4 years in a product and have never had any fail.
The connector is the same kind as computer ATX plugs, just less pins

If the joints are not flexed or vibrated in service you'll usually get away with doing that, especially if you took some action to minimise wicking during the soldering. That doesn't make it a preferred solution.

yeah, just a touch of solder, i don't let it wick up past the insulation crimp

Do you value your time at least a little bit? Wasting additional time on modifying connections from standard to substandard does not make much sense.

[Siwastaja]

That makes a lot of sense when you are unsure about the successfullness of your crimps due to a cheap crimp tool or lack of experience using it.

Substandard crimps are a total catastrophe, and soldering makes it much better - although if the crimp is done correctly, then the solder indeed is a downgrade. But for someone experienced with soldering, this gives more consistency if they can accept the robustness of the soldered connection.

"The right way to do it" would of course to get the proper crimp tools and do some quality control on the crimps. But many people who are experienced in electronics - i.e., do all their work soldering - are often unsure about that.

[wraper]

That makes a lot of sense when you are unsure about the successfullness of your crimps due to a cheap crimp tool or lack of experience using it.

Substandard crimps are a total catastrophe, and soldering makes it much better - although if the crimp is done correctly, then the solder indeed is a downgrade. But for someone experienced with soldering, this gives more consistency if they can accept the robustness of the soldered connection.

"The right way to do it" would of course to get the proper crimp tools and do some quality control on the crimps. But many people who are experienced in electronics - i.e., do all their work soldering - are often unsure about that.

He wrote it was a product made for 4 years, so no, it does not make sense. Supposedly it should be commercial product so there is no problem getting proper crimping tool for the task.

I've been crimping AWG16 into female pins and then soldering them for 4 years in a product and have never had any fail.
The connector is the same kind as computer ATX plugs, just less pins

[Psi]

That makes a lot of sense when you are unsure about the successfullness of your crimps due to a cheap crimp tool or lack of experience using it.

Substandard crimps are a total catastrophe, and soldering makes it much better - although if the crimp is done correctly, then the solder indeed is a downgrade. But for someone experienced with soldering, this gives more consistency if they can accept the robustness of the soldered connection.

"The right way to do it" would of course to get the proper crimp tools and do some quality control on the crimps. But many people who are experienced in electronics - i.e., do all their work soldering - are often unsure about that.

He wrote it was a product made for 4 years, so no, it does not make sense. Supposedly it should be commercial product so there is no problem getting proper crimping tool for the task.

I've been crimping AWG16 into female pins and then soldering them for 4 years in a product and have never had any fail.
The connector is the same kind as computer ATX plugs, just less pins

Yes there is, i'm not made of money, the official crimp tool is  US$1200 and i think you still have to buy the crimp insert for the pin you want to crimp.
Instead, I'm using a $60 aftermarket crimp tool designed for the type of pin i'm crimping.
works fine as far as i can tell.

I don't think i will ever trust crimped connections. The only way to know if the crimp is good is to pull on the cable hard and see if it comes out.  But if i do that i definitely wont trust the crimp after that.
So i always drop some solder into the crimp under the microscope for the high current crimps.
The other low current crimps i dont bother.
There's often 10A continuous flowing through the high current connections so i sleep better at night knowing they were also soldered and are not going to develop a high resistance that will cause them to melt the connector.

I'd rather they break off clean from vibration than catch on fire.

[smile]

Now knipex own video shows this crimp quality or the lack of it:



As you can see there is empty space between wires, this is with KNIPEX Hex Self-Adjusting Crimping Pliers for end sleeves (ferrules) with lateral access (97 53 14)

If Hex plier crimp like this then square ones are even worse (because you have to match the wires not only by AWG but make sure manufacturer does not lie about it.), and I don't get why KNIPEX does not have same design Hex crimp pliers as they have way more robust ones

[nctnico]

Ferrules don't need much crimping because they end up under a screw anyway.

[wraper]

Now knipex own video shows this crimp quality or the lack of it:

I rather see your imagination at work, adding what cannot be seen. Sees the gaps between strands  . First of all, picture is not clear enough. Secondly, strands cannot be of exactly of the same length, and there won't be completely tight crimp on the open end because of this. To see if it's tight or not, you would need to cut the crimp and see what's inside. Also it looks like those strands stick a little bit outside of ferrule as it often is done. BTW ferrules usually are not crimped as a one flat piece.

[coppice]

... To see if it's tight or not, you would need to cut the crimp and see what's inside. Also it looks like those strands stick a little bit outside of ferrule as it often is done. BTW ferrules usually are not crimped as a one flat piece.

Isn't it almost universal with crimps that either you can't see the end of the wire (e.g. BNC centre pins) or the wires are neatly trimmed to extend beyond the ferrule, as is the case with the Knipex image shown above?

In pretty much all cases the crimp stops a little short of each end of the ferrule, on purpose. This avoids an abrupt transition from crimped to non-crimped areas on the multi-strand wire, which would increase stresses as the flexible wire is wiggled.

You only get to see the actual crimp quality by a good clean cut through the middle of the ferrule, taking care not to let the cutting tool smear the soft metals together.

[Vernichtung]

I have spent the last 10 years in the Automotive industry and I personally use both, whist crimp is the most common There are situation in which I wouldn't settle for anything less than a soldered connection.
For example I will always crimp AND then solder (to the crimp terminal) a ring terminal. I find this helps to ensure that corrosion is rarely an issue. 

[expinkolator]

Now knipex own video shows this crimp quality or the lack of it:

Bootlace ferrules are not crimp connections, they are crimped to keep them on the wire. The tools are not intended and don't have the strength to deform the wire strands into a single gas tight mass, the thin walls of the ferrule don't have the strength to hold them together anyway.

The are used to make sticking the wire in a hole easier the same as real bootlaces, to provide a bit of mechanical strength, and for cosmetic reasons.

You don't have anything to argue about.

An interesting question is are they good to use with spring (or cage) clamp type terminals. I suspect not.

[Fraser]

If you want to see a scary video filled with bad ideas and practices, take a look here......

https://youtu.be/v2OvuvCuWsk

When working on vessels that navigate water you need to do electrical connections properly and use the correct parts for the job. Flattening a copper pipe to create a crimp lug may work for emergency 'Bush Engineering' but it isn't the best idea for mission critical wiring that can fail at the most inconvenient time.

I like the Dangar Marine video's but this one made me spit my coffee when I saw his ideas about tinning the cable before crimping. Total botch cable by the end of the video. If I had made such at Maritime technical college I would have been laughed out of the room, and rightly so.

Fraser

[smile]

Ferrules don't need much crimping because they end up under a screw anyway.

And you don't use then in wago 221 spring loaded terminals? Inserting stranded wire is a mess. You should be able to save one slot by crimping say two 2.5mm2 wires together into one crimp and using single port on wago 221.

Is that bad practice too, then I don't understand crimping at all.

If the ferules are so thin, they easily deform under pressure then there should be no good contact inside the ferrule.

[smile]

Now knipex own video shows this crimp quality or the lack of it:

BTW ferrules usually are not crimped as a one flat piece.

This make me wonder if they work OK in spring loaded terminals like wago 221? The uneven surface of the ferrule, what about good contact and small resistance, big surface area??

[Fraser]

Regarding the video I referenced showing poor tradecraft in making power crimp terminations.... credit to the video blogger, in response to my comments and direction to NASA guidance on the topic, he has pulled the video.

Dangar Marine is normally a fun channel to watch and he is a responsible chap. He replied in a positive manner to my comments on the video. I wish more video bloggers did the same when they were obviously showing poor tradecraft. In this case the video was based on poor advice he had been given by his audience concerning a previous video on making battery leads.

It just shows how misinformation can spread. Just because it's on the internet or someone tells you something, does not make it true. Research, research, research 

At least this particular misleading video has now been taken down.

For those who did not see it, the presenter showed how to terminate high current battery cables for use in maritime vessels. On advice from his viewing community he applied copious amounts of solder to the copper cable using a blow torch, apparently to prevent corrosion.  The copper conductors spread as the heat burned the insulation and solder filled the gaps between them. He then tried the same task using a 50W Weller type electronics soldering iron with a fine electronics tip fitted. Not surprisingly it created a useless blobby mess on the cable conductors. He was trying to show how hard it is to tin such large cables using a 'normal' soldering iron.

We were then treated to a lesson in how to make your own crimp lugs using lengths of copper tube that had been partially flattened in a vice and drilled to form a lug. The hollow oversize end was then slipped over the solder tinned cable ends and a hydraulic crimping tool used to compress the tube. The result was a DIY crimp that had wings on each side as the crimp die was too small for the tube diameter !

I commented that such a termination may be fine as an emergency bush engineering solution but it had no place on a marine vessel as its failure could strand the vessel. The idea of using a plain unplated copper DIY lug termination on a heavily solder plated multi core cable was abhorrent to me and a disaster waiting to happen. There was so much solder on the cable that The crimp would be compressing down onto a combination of copper and soft electronics solder. The solder would flow over time due to the pressure on it and the termination would fail. The cable was to be used in a 'tinny' Aluminium hulled boat. You can imagine what a 'live' high current sourcing 12V cable could do if it broke loose and started shorting to the Aluminium hull  Even if not so serious, just the heating of a poor termination and its resultant poor conduction under load could disable a vessel.

The author of the video obviously did his reaseach (a bit late) and realised he had been given poor advice.

Fraser