Question About Soldering Technique

[hizzy]

Hi Everyone!

Long time lurker, first time poster! I have a question that could use some clarification. I've recently gotten into electronics because I've been building joysticks for my old Atari 2600, Before buying a soldering station, I watched many on-line tutorials. I've noticed that people use different methods when soldering, i.e twisting wires together, pre-tinning and then joining wires, "western union" joints, etc..., but one thing has me confused. In the video below, the person demonstrating says that, when joining two wires, your solder and the tip of your iron should never make contact. That is, you hold the iron below the wire, heat up the wire, and then bring the solder to the wire, making contact only with the wire and not with the tip at all. He says this around the 3:20 point.



In other videos, like the next one, the narrator says to have  your solder touch the tip of your iron, where the tip and the wire meet. He says this at around the 4:50 mark of the video:




Is one of these methods wrong? Are both correct? This has been bugging me. I want to make sure I'm soldering correctly. Thanks so much for your advice and help!

[suicidaleggroll]

The first presenter is probably just trying to keep people from balling up a bunch of solder on their iron without letting any of it flow through the joint.  It's easier to ensure the solder is flowing through the joint if you're applying heat and solder on opposite sides, though it helps to put a bit of solder on the tip at first to help the heat transfer into the joint.  As long as the solder is flowing through the joint completely, it doesn't really matter what method you use.

[MosherIV]

The general principle is to heat up the parts you are trying to solder and then let the part(s) melt the solder. That way the solder flows over the parts and not ball up on the iron tip.

(This usually causes cable sleaving to shrink/melt)

[hizzy]

The general principle is to heat up the parts you are trying to solder and then let the part(s) melt the solder. That way the solder flows over the parts and not ball up on the iron tip.

(This usually causes cable sleaving to shrink/melt)

Sorry if this sounds very silly, but is it a bad thing should your solder wire make brief contact with your iron's tip when heating up a wire?

Thank you!

[rstofer]

The general principle is to heat up the parts you are trying to solder and then let the part(s) melt the solder. That way the solder flows over the parts and not ball up on the iron tip.

(This usually causes cable sleaving to shrink/melt)

Sorry if this sounds very silly, but is it a bad thing should your solder wire make brief contact with your iron's tip when heating up a wire?

Thank you!

Not at all!  I frequently add just a touch of solder to the tip to encourage heat transfer to the wire.  Not a big glob of solder, just a little bit.  Then I apply the solder to the far side of the joint.

[IanB]

In the video below, the person demonstrating says that, when joining two wires, your solder and the tip of your iron should never make contact. That is, you hold the iron below the wire, heat up the wire, and then bring the solder to the wire, making contact only with the wire and not with the tip at all.

I think this is a very idealistic view. It may be true in theory, but I doubt anyone really solders this way.

In order for heat to flow from the iron to the joint there needs to be a "bridge" of solder across the gap to conduct the heat (otherwise the iron will be hot, the joint will be cold, and you will never get the solder to flow). What most people do is to touch the end of the solder wire in the gap between the iron and the joint to start the heat flowing, and then move the wire over the rest of the solder joint until the solder has flowed and the surface is fully wetted.

[GreyWoolfe]

If the wires I am trying to solder are thin, I put the tip under the wires and heat them so the solder flows, adding lots of liquid flux.  If the wires are thick, I will touch the solder to the tip while the tip rests on the wires, still using lots of liquid flux.  I will also use western union splices wherever possible.  When I solder PL-259 connectors, I just use the iron to drop solder in all the holes and use my little butane torch to melt the solder in.

[hizzy]

If the wires I am trying to solder are thin, I put the tip under the wires and heat them so the solder flows, adding lots of liquid flux.  If the wires are thick, I will touch the solder to the tip while the tip rests on the wires, still using lots of liquid flux.  I will also use western union splices wherever possible.  When I solder PL-259 connectors, I just use the iron to drop solder in all the holes and use my little butane torch to melt the solder in.

When you say "adding liquid flux" is this a separate product, other than the flux which is in the rosin core solder?

I have purchased this, but haven't tried it yet:

http://www.ebay.com/itm/252346279419?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Thanks!

[hizzy]

The general principle is to heat up the parts you are trying to solder and then let the part(s) melt the solder. That way the solder flows over the parts and not ball up on the iron tip.

(This usually causes cable sleaving to shrink/melt)

Hi!

Another silly question, perhaps: When soldering something like a DB9 connector, would you rest your tip against the bottom of the cup and let the solder fill the cup? Is go to the back or bottom a good soldering technique?

Thank you in advance!

[MosherIV]

Another silly question, perhaps: When soldering something like a DB9 connector, would you rest your tip against the bottom of the cup and let the solder fill the cup? Is go to the back or bottom a good soldering technique?

No silly questions if it leads to better soldering technique.

So with any connector with 'bucket' which accept wires - as I said the general goal is to heat up the parts you want to solder and let the heat from the parts melt the solder.
That said, for the bucket with a wire in it, it is very hard to heat both up at the same time.
personally, I find it easiest to put the soldering iron tip somewhere where it toouches both the wire and the solder bucket, a little solder on the iron will help make good contact.
Simple answer bottom of the open bucket and touch the wire at the same time.

[Ian.M]

There is no such thing as a DB9 connector.  In the D-subminiature connector series the second letter codes the shell size, and B is the size for the 25 pin connector.
See https://en.wikipedia.org/wiki/D-subminiature

However the D series connectors are invariably somewhat of a PITA to solder, and if you have the choice, use a shell that takes crimp contacts, with the correct contacts and specific crimp tool for it.   If you do have to solder them, its essential to pre-tin and trim the wire ends then you should pre-apply Hellerine expanding sleeving that you can ease over the joint after soldering.  Heatshrink is useless as you wont be able to get it far enough away from the joint to avoid it shrinking prematurely without cutting back the jacket and shield further than most backshells can accommodate.  You can only get away without sleeving if the wire has high temperature low shrinkage insulation.

Most D-sub contact cups will have a low side facing out, so your only real choice is to heat the side of the cup on the side you haven't wired the next pin on yet. If you attempt to heat the wire as well as the cup, you'll get excessive insulation burn-back and the bit will block the access you need to feed solder.  Because the wire has been pre-tinned, as soon as you feed a tiny bit of solder into the cup, the cup will effectively transfer heat to the wire.  Feed solder till the cup is fractionally short of full - nearly flat but slightly concave is far easier to inspect for suspect joints than an overfilled cup.  There should be minimal excess solder on the outside of the pin.

Exception: if you ever have to solder large diameter solid wire into D-sub cups, you will need to tin and flux the wire then heat both it and the cup due to the solid wire's much higher thermal conductivity.

Also many shells have thermoplastic insulators, so you need to support the contacts by plugging it into a mating connector while soldering it and not dwell excessively on each joint.  A three clip 'helping hands' tool is a big help here - two clips to hold the shell and one to position the cable so there is no sideways strain on the wire.

[tggzzz]

Here's a set of nine expert, succinct, and accurate videos on soldering, showing you what you need to acheive and why, how to achieve it, recognising mistakes and avoiding mistakes - including variants. https://www.youtube.com/playlist?list=PL926EC0F1F93C1837 But please, no sniggering at the pronounciation of "solder and "soldering"

One of the problems nowadays is that anyone can make a video blog. While some are very good and useful, most aren't; in the worst the Dunning-Krueger effect is strong One often overlooked advantage of the good old days (cough) was that because it was hard and expensive to make videos, people only made videos when they were required to pass on information, and they planned exactly the minimum that needed to be said.

[hizzy]

There is no such thing as a DB9 connector.  In the D-subminiature connector series the second letter codes the shell size, and B is the size for the 25 pin connector.
See https://en.wikipedia.org/wiki/D-subminiature

However the D series connectors are invariably somewhat of a PITA to solder, and if you have the choice, use a shell that takes crimp contacts, with the correct contacts and specific crimp tool for it.   If you do have to solder them, its essential to pre-tin and trim the wire ends then you should pre-apply Hellerine expanding sleeving that you can ease over the joint after soldering.  Heatshrink is useless as you wont be able to get it far enough away from the joint to avoid it shrinking prematurely without cutting back the jacket and shield further than most backshells can accommodate.  You can only get away without sleeving if the wire has high temperature low shrinkage insulation.

Most D-sub contact cups will have a low side facing out, so your only real choice is to heat the side of the cup on the side you haven't wired the next pin on yet. If you attempt to heat the wire as well as the cup, you'll get excessive insulation burn-back and the bit will block the access you need to feed solder.  Because the wire has been pre-tinned, as soon as you feed a tiny bit of solder into the cup, the cup will effectively transfer heat to the wire.  Feed solder till the cup is fractionally short of full - nearly flat but slightly concave is far easier to inspect for suspect joints than an overfilled cup.  There should be minimal excess solder on the outside of the pin.

Exception: if you ever have to solder large diameter solid wire into D-sub cups, you will need to tin and flux the wire then heat both it and the cup due to the solid wire's much higher thermal conductivity.

Also many shells have thermoplastic insulators, so you need to support the contacts by plugging it into a mating connector while soldering it and not dwell excessively on each joint.  A three clip 'helping hands' tool is a big help here - two clips to hold the shell and one to position the cable so there is no sideways strain on the wire.

I watched this video, and thought it was called DB9.




Thank you for your clarification! Also, I have never heard of Hellerine expanding sleeving. Do you have a link to it? Thanks again!

[helius]

Here's a set of nine expert, succinct, and accurate videos on soldering, showing you what you need to acheive and why, how to achieve it, recognising mistakes and avoiding mistakes - including variants. https://www.youtube.com/playlist?list=PL926EC0F1F93C1837

Yes, that series really is excellent, although also rather old (early '80s?)! The segment on "cup terminals" is appropriate for D-sub and circular connectors, and its recommendation to use solder preforms and resistance tweezers is quite useful.

[hizzy]

Here's a set of nine expert, succinct, and accurate videos on soldering, showing you what you need to acheive and why, how to achieve it, recognising mistakes and avoiding mistakes - including variants. https://www.youtube.com/playlist?list=PL926EC0F1F93C1837 But please, no sniggering at the pronounciation of "solder and "soldering"

One of the problems nowadays is that anyone can make a video blog. While some are very good and useful, most aren't; in the worst the Dunning-Krueger effect is strong One often overlooked advantage of the good old days (cough) was that because it was hard and expensive to make videos, people only made videos when they were required to pass on information, and they planned exactly the minimum that needed to be said.

I like that series a bit, but do they have a video showing how to join two wires together? That is what I find myself doing most often.

For the cup connector, does anyone use the technique show in the pace video? I don't know how it would work in small cups.

Thanks!

[T3sl4co1l]

Heat transfers entirely because the joint is "wet" and "sticky".  You reach this state by using flux and solder as liberally as you can!

"Can" means, don't leave it globby, shake or wick off excess if you went nuts.  But there's nothing wrong with that, soldering doesn't have to be an additive-only process.

Likewise, desoldering doesn't have to be a subtractive-only process, in fact it can't possibly be only that!  I've gotten weird looks from naive people before, when using solder to tin the tip of a desoldering (hollow tip) iron.  Well, how else do you expect the joint to heat up?!  (Also, flowing in leaded solder is a great help with desoldering lead-free joints.  Lower melting point, easier flow.)

Don't crank the iron temperature up.  Be patient and use lots of flux or solder.  Time at temp is what burns out the tip.  For leaded solder, 650F is fine.  Only turn it up as needed for big and stubborn joints.  (If you don't have a temp controlled iron, you should get one.  It's much easier to use, lasts longer, and only costs a hundred bucks -- it will easily repay itself in months to years, depending on how much you need it.)

Tim

[helius]

Desoldering tips certainly should be kept tinned (and should be covered in solder after use to protect the plating from oxidation). But if you want to really transfer heat in a hurry when desoldering, especially on old, dull joints, a thin coat of liquid flux works well. (The problem is that that flux gets sucked into the desoldering gun and gums up the filter faster). If you mess up and leave some solder down inside the hole, adding more solder is the only way you'll get it desoldered correctly.

[GreyWoolfe]

If the wires I am trying to solder are thin, I put the tip under the wires and heat them so the solder flows, adding lots of liquid flux.  If the wires are thick, I will touch the solder to the tip while the tip rests on the wires, still using lots of liquid flux.  I will also use western union splices wherever possible.  When I solder PL-259 connectors, I just use the iron to drop solder in all the holes and use my little butane torch to melt the solder in.

When you say "adding liquid flux" is this a separate product, other than the flux which is in the rosin core solder?

I have purchased this, but haven't tried it yet:

http://www.ebay.com/itm/252346279419?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Thanks!

This is what I buy.
http://www.all-spec.com/Catalog/Soldering-Rework/Soldering-Chemicals/Solder-Flux/835-100ML-33018?utm_source=bing&utm_medium=cpc&utm_campaign=Product%20Listing%20Ads%20-%20Shopping&utm_term=1100404856838&utm_content=PLA

[mariush]

Here's how you tin wires (paranoid nasa grade style) :



The whole series is nice, though really over the top with cleaning the components.

[tggzzz]

Heat transfers entirely because the joint is "wet" and "sticky".  You reach this state by using flux and solder as liberally as you can!

"Can" means, don't leave it globby, shake or wick off excess if you went nuts.  But there's nothing wrong with that, soldering doesn't have to be an additive-only process.

Likewise, desoldering doesn't have to be a subtractive-only process, in fact it can't possibly be only that!  I've gotten weird looks from naive people before, when using solder to tin the tip of a desoldering (hollow tip) iron.  Well, how else do you expect the joint to heat up?!  (Also, flowing in leaded solder is a great help with desoldering lead-free joints.  Lower melting point, easier flow.)

Don't crank the iron temperature up.  Be patient and use lots of flux or solder.  Time at temp is what burns out the tip.  For leaded solder, 650F is fine.  Only turn it up as needed for big and stubborn joints.  (If you don't have a temp controlled iron, you should get one.  It's much easier to use, lasts longer, and only costs a hundred bucks -- it will easily repay itself in months to years, depending on how much you need it.)

The videos in https://www.eevblog.com/forum/beginners/question-about-soldering-technique/msg1062935/#msg1062935 demonstrate all those points, along with how to select the right iron tip and temperature, then verify the selection by seeing good and bad results.

That is an invaluable addition to correct (but less than completely helpful) statements that the right temperature and tip should be used.

[hizzy]

Is there a difference in the quality of flux from paste & liquid?

Thanks!

[hizzy]

Here's how you tin wires (paranoid nasa grade style) :



The whole series is nice, though really over the top with cleaning the components.

Watching this video a couple times, I find myself more confused. The solder makes scant contact with the wire. It looks like the solder is coming more from the bottom, and it looks like he is using the iron's tip to "brush" the solder over the wire. What do other people think?

[helius]

Is there a difference in the quality of flux from paste & liquid?

Liquid flux is easier to overapply, and flows more easily around the board and under components (which can be good or bad). Watch out because many paste fluxes are not intended for electronics and are too corrosive. There's also tacky flux, which can be applied through a syringe but is a bit easier to control than liquid while retaining most of the latter's properties.

[helius]

Watching this video a couple times, I find myself more confused. The solder makes scant contact with the wire. It looks like the solder is coming more from the bottom, and it looks like he is using the iron's tip to "brush" the solder over the wire. What do other people think?

Because the wire is fluxed, it will be wetted by the solder that's on the tip of the iron. The goal is not to cover the wire with solder: it would be too stiff and brittle especially if it travels up under the insulation.
Ultimately molten solder wants to move towards the heat source, but it will spread over and wet fluxed metal surfaces along the way, as long as they get hot enough. The same way that you only need to heat a through-hole on a double sided board from one side, as long as there is enough flux, the same applies to wire tinning.

[T3sl4co1l]

I've got an old tin of Radio Shack flux.  It's transparent and amber in color, a smooth gel.  Best I've ever used, better than anything dissolved in IPA (it doesn't spatter and run away from the heat!), and better than the most common types of name brand fluxes!

Tim