Question About Soldering Technique

[SeanB]

I avoid fish from my local harbour, especially since they decommissioned the TE lead tank there, and had a small announcement about finding a crack in the tank, and that around 25 tons of the TE lead concentrate went into the ground, and from there around 50m directly into the harbour, right near the best fishing spot ( and about the only one you do not need a harbour permit to get to, so very popular) in the harbour.

http://www.oilwatch.org/doc/paises/sudafrica/sudafrica2003ing.pdf

[hizzy]

Hi,

I was wondering what popular opinion is on this technique for soldering dsub connectors:

http://www.aeroelectric.com/articles/dsubs/d_solder.html

Does this look like a method I should emulate?

Thanks!

[nanofrog]

Yes, that's a good method. 

IF you want to meet NASA/Mil-Spec standards however, the gold plating inside the solder cups has to be removed first. So you'd fill the cup with solder, then wick it out. And finally complete it with the steps as described. No need to do this at a hobbyist level IMHO however.

[hizzy]

Thankfully, I don't think I have plating in my solder cups. They just look like plain silver!

[Ian.M]

Hopefully that's tin plate, which takes solder readily if its not old and badly oxidised.

While the techniques that pre-load the cup with solder are good for individual wires, I always found them to be a PITA if working with a cable and a short back-shell as manipulating a short wire constrained at the other end to insert it while the solder is molten has a high risk of insulation damage.   *IF* the cups take solder readily, I would recommend fluxing them lightly with liquid Rosin based flux, shaking or blotting off excess and allowing them to dry to leave a trace film of flux inside the cup, then inserting the pre-tinned and trimmed wire cold then soldering, feeding solder as required to correctly fill the cup.   If they *DON'T* take solder well you'll need to pre-tin and wick NASA style.  It does require a slightly longer dwell time as its essential that any pockets of flux or air bubbles have enough time to come to the surface.

Unless you are 100% certain the insulator is themoset, not thermoplastic, always protect the insulator against distortion by mating the connector with its opposite gender one to support the contacts while soldering.   The only thing worse than breaking a pin on the centre row of a DE-15 plug because it skewed out of alignment due to the insulator softening, is a skew pin distorting the contacts of a PCB mounted socket so that a correctly assembled un-distorted plug no longer makes reliable contact  . . . . 

[hizzy]

How does this look? I think he could have tinned the wire first. Should there be less solder on the tip of his iron?





Thanks!

[Ian.M]

In addition to failure to tin and trim the wire, you can see it move as he finishes the joint - so that's a possible dry joint right there.   Then he shrinks heatshrink by direct contact with the bit. If you are going to use a soldering iron to shrink heatshrink, hold it just above but NOT in contact with the barrel near the tip and let the hot air convection do the job.

As we don't get to see a closeup, we cant tell if he's transferred excessive solder to the side of the pin or how good the joint is .

[mariush]

What you do in the video is just ... acceptable.

One observation ... you don't clean the tip on the sponge.   Add a bit of solder on the tip if there's not much, get a paper towel or "chemwipe" (lint free handkerchief sort of) , clean the tip with this paper towel/ whatever (run the tip over the paper and rotate it a bit).  Now that it's clean of solder, rub it a bit on the wet sponge to break whatever oxides are still there, and put a tiny amount of solder to minimize oxidation.  You're ready to solder. When you're done, add some solder to the tip to protect it until next use (you'll remove this solder with your paper towels next time)

The technique is not that great because you have little control over how deep the solder actually goes in.

Pace Worldwide (they make soldering stations and lots of soldering related tools) has on their channel very good videos. Among them there's a series called "Basic Soldering Lessons" which may seem dated, but the information in the videos is still quite valid.  You should definitely watch parts 1, 6 and 7 as a refresher, and below you can see Lesson 3 which is about cup terminals (similar to what you have on those D connectors)



The basics : TIN the wires first... it's important.  Fill the cups with solder (bend solder wire in 2 or 3 or as many times as needed to get thick enough solder to get right amount in cups).  Heat until flux boils at the top then insert tinned wire, remove tip and hold in place until everything solidifies.

This guy does it the paranoid nasa avionics grade ultra ridiculous whatever way - seriously you'd probably roll your eyes half way into the video :

[CraigHB]

In my many years of soldering electronics I've come to like brass wool for tip cleaning the best.  I use the Hakko replacement pads.  It cleans any stubborn oxidation easily.  A wet sponge works well, but in some cases it doesn't get all the gunk off.  The down side with the wool is there may be some abrasion that occurs, but I haven't noticed it reducing the life of the tip at all.  The down side with a wet sponge is the temperature shock suffered by the tip, but again have not noticed any tip degradation due to that.

[hizzy]

I ordered a brass cleaner this morning, along with a few different tips!

[helius]

If you use a sponge to clean your iron with solder on it, it quickly gets covered in solder blobs. With the brass wool there's no problem, the solder just pools and hardens in the bottom of the container. :thumbsup:

[hizzy]

When soldering a d sub connector, is there a preferred tip I should be using? Should I go for the smallest one possible? Thanks!!

[T3sl4co1l]

I'd go with a flat wedge, or whatever they call the tilted-faced-cylinder thing.

Tim

[nanofrog]

When soldering a d sub connector, is there a preferred tip I should be using? Should I go for the smallest one possible? Thanks!!

Personally, I'm fond of bevel/hoof shapes as well as chisels and bent chisels. As per size, you need the tip sized to the joint, so No, don't use the smallest one possible as you won't get sufficient thermal transfer.

Hakko's Tip Selection page should be of interest, as it shows you what the different shapes are used for, and how to size a tip to the joint (lots of illustrations and movies).

[hizzy]

Hi,

Thank you all for the replies! I was wondering: Would it be a good idea to get some magnifying glasses? Is that commonplace among most soldering gurus out there?

Thanks again!

[John Coloccia]

Hi,

I was wondering what popular opinion is on this technique for soldering dsub connectors:

http://www.aeroelectric.com/articles/dsubs/d_solder.html

Does this look like a method I should emulate?

Thanks!

Bob is the man when it comes to aircraft wiring techniques! I've had the pleasure to chat with him a couple of times over the years. Always a gentleman. I'd encourage you to buy his book. It's money well spent and a lot of techniques are directly applicable in your own projects.

[nanofrog]

Hi,

Thank you all for the replies! I was wondering: Would it be a good idea to get some magnifying glasses? Is that commonplace among most soldering gurus out there?

Thanks again!

It's not really necessary for thru-hole, but smaller SMD, it's quite useful. In the latter category, some have even opted for a binocular or trinocular scope (~7x - 45x). Amscope is popular due to the value they offer.

[tggzzz]

HI was wondering: Would it be a good idea to get some magnifying glasses? Is that commonplace among most soldering gurus out there?

That entirely depends on your eyes, so there's no way anyone can give a useful answer.

At my age I use a head-mounted visor, and have a surprisingly good ex-school stereo microscope for close inspection.

[CraigHB]

I'm older and my close vision is not so close anymore.  I use a stereo microscope at 10x most of the time.  It also has a 30x setting, but I only use that for inspection.  I think in my youth I could have done larger components like 0805 (2012 metric) without visual aid, but even then I probably would have needed magnification for 0603 and smaller (back then it was all through hole).  In any case there's lots of options.  The visor style that watchmakers use is popular.  You can use a magnifying glass on a stand or just reading glasses.  I have a set of readers in 3x and I use them a lot for bigger stuff like soldering wires to PCBs.  With better close vision a set of 3x readers would probably do for most stuff.

[GreyWoolfe]

I use a headband magnifier also, even for through hole.  I am far sighted with amblyopia and astigmatisms in both eyes so magnification just works all around for me.  I even use the magnifier for threading needles.  Don't forget good lighting.  I upgraded the lighting on that half of the workbench and it made a big difference.

[CraigHB]

Yes lighting does help a lot when you have limited vision.  I run a couple bright LED floodlights over my work bench.

[steverino]

I use a headband magnifier also (old eyes).  I don't know if I'll ever go the microscope route, uses valuable desk space and just looks like a hassle.  I need a #7 lens on my optivisors and this level of magnification has a focal length that puts my nose about 4 inches from the board (maybe more) which then blocks my lighting.  The best task light I've found so far for close work like this is the Ikea gooseneck lamp, which is only about $22 on ebay.

[CraigHB]

I'm not much further using the microscope, but yeah it is kind of a hassle.  The main problem is the platform isn't always big enough.  I need one that uses a flat mount to allow use of the whole desktop.  What I like about it is the magnification is greater with a lot less distortion than a simple magnifying task light or glasses.  It makes small things look big and easy to work on.  Now having nerves steady enough to do the work without making a mess of it is another thing.

[IanB]

I'm surprised audiophiles haven't cottoned on to this. Shouldn't high end audio equipment be assembled with AuSn solder? 

[John Coloccia]

This guy does it the paranoid nasa avionics grade ultra ridiculous whatever way - seriously you'd probably roll your eyes half way into the video :

That's very normal in avionics and especially astronomical electronics. Gold must be removed before soldering as gold and tin often form a number of different brittle inter-metallic compounds which give you trouble after many times of thermal cycling.
The general rule in avionics is either you have a lot of gold, or none. For some really critical connections that oxidization is not acceptable even in harsh environments, people use gold-tin solder with very high concentration of gold to inhibit the form of IMC as well as to inhibit corrosion. When the cost of AuSn solder can't be justified, people just get rid of gold completely.
Another use of AuSn solder is in high voltage applications where any flux contamination are not accepted. Imaging you are building a power module of 20kV, then any trace amount of baked flux (essentially carbon) will cause long term reliability issue. AuSn solder, thanks to the superior wettability and fast solid phase diffusion speed of gold, doesn't need flux to wet most surfaces, and the bond will grow stronger over time, rather than degrade over time.

Aircraft have massive vibration problems also, especially piston driven aircraft. For example, it's not uncommon to have a wire that was left slightly loose and able to touch part of the airframe, and during annual inspection you find that it's rubbed completely through the insulation.