Solder differences and desoldering tools/technique

[jayjr1105]

I've been using some cheap Amazon stuff thats 63/37 with 1.8% flux. It does well just practicing soldering on a piece of perf board but would a good roll of 63/37 Kester make a significant difference when replacing motherboard caps? I have found motherboards to be extremely difficult to desolder and resolder new caps. I am slowly getting better with the solder sucker to clear out the hole. But If I go through all the labor to properly remove a cap and have a clean hole, I want to make sure the solder I'm using will flow nicely with the new cap.

Also, what do you guys use to hold motherboards nice and still? I feel like this is an underestimated part of this process.

Another side question. Are there affordable de-solder vacuum tools out there or should I just get good with the sucker?

[mariushm]

Re: Solder differences and desoldering tools/technique

Yes, quality solder should help.
You have plenty of high quality solder on Digikey, Newark, Mouser ... you shouldn't mess with solder from Amazon unless it's sold by authorized resellers or the actual company. There are quite a few fakes sold through Amazon by third party sellers.

A good solder 63/37 3% no-clean flux, 0.38mm, 1/2lbs (227g) for 20.5$ : https://www.digikey.com/product-deta...131-ND/2498929

Ideally, you'll want something a bit thicker but the good ones are only available in 450g (1lb) for around 29$, like this one (0.56mm, C502 flux) : https://www.digikey.com/product-deta...129-ND/2498927 or this one ( 0.61mm , C400 flux) : https://www.digikey.com/product-deta...121-ND/2498919
C400 is a bit more acid but without halides, C502 has halides and less acid both are good solders but I think the C502 is a tiny bit better.

Newark has Kester Solder 63/37 ~0.63mm ~ 2.8% RMA flux 450g (1lb) for around 25$ : http://www.newark.com/kester-solder/...3-c/dp/34C5667


You should invest some money on some good LIQUID FLUX, it helps a lot when it comes to motherboards.

Also, solder isn't the main problem when it comes to motherboards.

Motherboards are a special case because they're made of multiple (often 6 or more) layers of circuit board with large planes of copper which simply suck the heat from your soldering iron tip before it gets a chance to properly bring the leads and pads to melting temperature.

63/37 solder will actually be a bit worse for you in this case compared to regular 60/40 solder because it's euctetic, it transitions from solid to liquid and back at a very narrow temperature range, around the 183 degrees Celsius point. It practically snaps between states at 183c. Great in general and especially where you have to deal with vibrations, but not so great when you want to desolder things.
60/40 solder is a bit more lenient, it will become liquid at 180c and stay liquid over a wider range, you'll have around 10 degrees Celsius range to play it... so with motherboards with big planes of copper, staying semi-liquid for a few seconds can be helpful.

So the proper technique would actually be to:

* OPTIONALLY find some paint drying gun or hair dryer or hot air gun to blow on the motherboard in the area where you want to desolder or solder, to raise the overall motherboard temperature to around 50-60c ... warm but not hot enough to melt plastics (from inductors for example),

* be generous with liquid flux because the surfaces are pretty much oxidized and won't take solder, and if you heated the board in previous step the heat will activate the flux a bit and do some work before you even put the soldering iron on the board

* pick the right size of iron tip and the right solder thickness, add some solder to the joint to reduce the melting point from ~ 217c (lead free) down to around 183c (63/37) or 180c (60/40) , then as you heat the pad and lead, use the solder sucker on the joint or just pull the component from the other side.

If the hole is covered in solder, don't bother with solder wick, find some very thin stainless steel needle, add some flux over the pad filled with solder, add some solder and cover the hole with more solder and while you keep the solder liquid, gently push the stainless steel needle from the other side, or push the needle through the solder.

Solder won't stick to a stainless steel needle, so you can easily make you hole this way.
But you have to be careful not to lift pads this way or not to break the walls of the through hole by pushing a too thick stainless steel needle.

[jayjr1105]

Re: Solder differences and desoldering tools/technique

I have some paste flux which I apply with a tiny little brush before hand. Is that sufficient or should I still try to get some liquid.

My Iron is a Hakko FX888D with the smaller chisel tip. I try to desolder and solder on motherboards @ 375c. I also have the bevel tip C2 I think it is.

I guess I'll try and grab some 60/40 solder as well. Everywhere you read everyone is tooting the 63/37 horn but If you say so.

Can you recommend something to keep a motherboard stable? Just a basic bench vise?

[mariushm]

Re: Solder differences and desoldering tools/technique

I like 63/37 more than 60/40, and I have the above Multicore C502 0.56mm spool and works great for me.
I'm just saying that where the component sucks all the heat from your tip, it may help you a bit to use 60/40, but with that soldering station you should be fine with 63/37.

Liquid flux (or paste-ish flux) helps a lot, get used to applying flux where you work, even though the solder wire itself has 2-3% flux.
I'm buying some liquid flux made by a Polish company , in 100ml and 250ml bottles, in US you may only have flux pens which kinda suck, are a bit expensive.
I buy mine for 5-10$ a bottle, while your pen things are 10$ each ... here's what i buy : https://www.tme.eu/en/katalog/fluxes...5915%3B&page=1

[diif]

Re: Solder differences and desoldering tools/technique

I use genuine Amtech 559 flux for SMD work but no flux on through hole stuff.
I use 60/40 that is 2.2% flux.
I have a Panavise like this https://www.panavise.com/index.html?...eqskudatarq=25 that I have used held in a vice, but I much prefer it lose on the bench. A high temperature silicone mat stops it sliding about. Like this https://www.ebay.com/itm/Station-Pad...L/292187660690

I'd avoid a vice, due to the high possibility of squashing the many layers, unless you can hold it at the sides like the Panavise.

[jasko_jacker]

Re: Solder differences and desoldering tools/technique

In my opinion, the welding or desoldering techniques change according to the type of motherboard you are working on.
If we work on a board with trough hole and surface mount components, it may be difficult to clean the holes well, you have to use a lot of flux, add an alloy with a lower melting point, use a a flat tip welder with a good power (80w) and a good quality desoldering braid .
for boards with surface-mount components, to avoid heating a large area every time, it's useful to have tweezer soldering iron but not cheap type.

[jayjr1105]

Re: Solder differences and desoldering tools/technique

Thanks all for good advice. I'm currently eyeing up this https://www.aliexpress.com/item/Elec...6b69aaab8j3ClT

Thoughts?

[stj]

Re: Solder differences and desoldering tools/technique

i wouldnt, it looks like a mains element.
so for a start your gonna take a wattage loss at 110v because it's probably a universal input.

go look for a ZD unit with seperate iron and control-base.

another problem is no display - just a nob to set the temp - that does not inspire confidence on how well it regulates.

[llonen]

Re: Solder differences and desoldering tools/technique

A solder extractor is definitely the way to go, and if you are going to be carrying out a lot of work then consider it an investment, I have several Pace SX-80's and a SX-90. These are expensive systems but can be had cheaper on the second hand market worth keeping a watch on.

[budm]

Re: Solder differences and desoldering tools/technique

"If the hole is covered in solder, don't bother with solder wick, find some very thin stainless steel needle, add some flux over the pad filled with solder, add some solder and cover the hole with more solder and while you keep the solder liquid, gently push the stainless steel needle from the other side, or push the needle through the solder.

Solder won't stick to a stainless steel needle, so you can easily make you hole this way.
But you have to be careful not to lift pads this way or not to break the walls of the through hole by pushing a too thick stainless steel needle."
You use the method as I do.
I use these SS probes:
https://www.harborfreight.com/5-piec...-set-1816.html
https://www.harborfreight.com/6-piec...set-93514.html

[jayjr1105]

Re: Solder differences and desoldering tools/technique

So I'm using a solder sucker from the top side of the board while I heat up the hole on the other side. It's actually working well. My problem is keeping the board steady between my legs while keeping the iron tip in the hole and then aiming the sucker properly. Holy crap I need 2 more arms!

[megaraider]

Re: Solder differences and desoldering tools/technique

So I'm using a solder sucker from the top side of the board while I heat up the hole on the other side. It's actually working well. My problem is keeping the board steady between my legs while keeping the iron tip in the hole and then aiming the sucker properly. Holy crap I need 2 more arms!

What an excellent option to barbecue your balls... Mine are priceless (as everything else in my body)!
Use the stainless steel needle method, it's far safe and efficient!
(If you don't have a fancy one, make one using a cloth needle and a bottle cork )

[stj]

Re: Solder differences and desoldering tools/technique

sowing needles are chrome-plated steel, solder will stick to them!

[sam_sam_sam]

Re: Solder differences and desoldering tools/technique

sowing needles are chrome-plated steel, solder will stick to them!

Where do you get stainless steel pins
Could you please provide a link where to buy some good quality ones
thanks

[diif]

Re: Solder differences and desoldering tools/technique

So I'm using a solder sucker from the top side of the board while I heat up the hole on the other side. It's actually working well. My problem is keeping the board steady between my legs while keeping the iron tip in the hole and then aiming the sucker properly. Holy crap I need 2 more arms!

Build yourself a large pair of "helping hands" ?

[megaraider]

Re: Solder differences and desoldering tools/technique

sowing needles are chrome-plated steel, solder will stick to them!

Lower quality sewing needles yes. Highest quality ones are platinum and/or titanium plated.
Another home made solution: use a hypodermic needle taken from a syringe.

[diif]

Re: Solder differences and desoldering tools/technique

I've just had these arrive. https://www.aliexpress.com/item/Holl...785718126.html
Awesome for removing stubborn solder stuck in holes.

[tvtimmy]

Re: Solder differences and desoldering tools/technique

My solder sucker of choice is the Vellman. Strong and cheap, like me.lol

[tvtimmy]

Re: Solder differences and desoldering tools/technique

The Vellman

[stj]

Re: Solder differences and desoldering tools/technique

put some hellermann sleeve on that and it will be 10x better