soldering tips for stubborn solder?

drewpayne34

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Hello everyone, I've got a medalist mother board here i'm trying to swap some bad caps on. Normally this is a quick easy task but i cant seem to get the desoldering wire to absorb the solder. My iron is plenty hot and the wire works fine on other boards.. just not these tiny pins. Any tips greatly appreciated.
 

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Hello everyone, I've got a medalist mother board here i'm trying to swap some bad caps on. Normally this is a quick easy task but i cant seem to get the desoldering wire to absorb the solder. My iron is plenty hot and the wire works fine on other boards.. just not these tiny pins. Any tips greatly appreciated.

Put a dab of new solder on your iron and then touch the older solder with it, to try and get it flowing again.
 
Flux the braid! Flux the braid!
 
Thanks for the quick responses all! Ill try adding more solder and flux and see if i can get it flowing. I have been using Alpha fry rosin core.
 
It's probably lead free solder... and being a computer motherboard, it's probably around 8 layers of copper, and it has no thermal relief... so your soldering iron probably just can't get it hot enough to melt the solder. You'll probably need a higher power soldering iron, or to pre-heat the motherboard with hot air so the solder joint doesn't need as much power from the iron to melt the solder.

DogP
 
Hello everyone, I've got a medalist mother board here i'm trying to swap some bad caps on. Normally this is a quick easy task but i cant seem to get the desoldering wire to absorb the solder. My iron is plenty hot and the wire works fine on other boards.. just not these tiny pins. Any tips greatly appreciated.

Break the caps off from the top side first, so you can grab the pins with needlenose to pull them out as you heat it.... then clean out the holes.
 
Break the caps off from the top side first, so you can grab the pins with needlenose to pull them out as you heat it.... then clean out the holes.

That will only work if his iron has the berries for the job. I suspect the problem is exactly what DogP said it was. I've had trouble melting the lead-free solder in certain through-holes of modern multi-layered PCBs with a Metcal, which is one of the strongest irons out there, and I was doing exactly what you described. I had to jam the point of the STTC-126 tip down into the hole, and it took a good 10 seconds or so to melt the solder enough that I could pull out the lead with the needle-nose pliers, at which point the Metcal had heated the entire ground plane of the board up so much that it would burn you if you touched it anywhere.
 
I had to jam the point of the STTC-126 tip down into the hole, and it took a good 10 seconds or so to melt the solder enough that I could pull out the lead with the needle-nose pliers, at which point the Metcal had heated the entire ground plane of the board up so much that it would burn you if you touched it anywhere.

Ah, the STTC-126... my favorite tip until some moron at works tries to bend it back.
I keep one hidden in the lab.
 
Ah, the STTC-126... my favorite tip until some moron at works tries to bend it back.
I keep one hidden in the lab.

LOL

I've used an STTC-126 for nearly everything since the late 1990s. I was introduced to Metcals and that particular tip cartridge when I worked at a PCB factory from 1998 to 2000, doing assembly-line soldering as well as a lot of rework. It was by far the most popular tip there; though a few people preferred the STTC-125 straight chisel tip. Eventually I found a good deal on a used Metcal STSS unit on eBay so I have one at home.
 
I mostly use SP200s at home, so I actually use the SSC-726A the most :)

I picked up a cheap STSS off craigslist, with a good variety of tips, but I keep that for special occasions, and usually just use the MX5000s in the lab at work for detail work.
 
I mostly use SP200s at home, so I actually use the SSC-726A the most :)

I picked up a cheap STSS off craigslist, with a good variety of tips, but I keep that for special occasions, and usually just use the MX5000s in the lab at work for detail work.

If you haven't already read it, you might find the EEVBlog thread from a guy who built his own Metcal-compatible RF generator (13.56 MHz variety: STSS and MX-series; the SP-series is 450 KHz) from scratch interesting:

https://www.eevblog.com/forum/projects/diy-metcal-13-56-mhz-rf-supply/

That guy prefers the STTC-126 too.

He did some runs of the PCBs he designed, so quite a few people ended up building them:

rcrfrXH.jpg


1yLfLNk.jpg


Here in the U.S. old STSS units are easy to find and fairly inexpensive, but in that guy's part of the world I guess Metcals were a lot harder to come by, so building his own made sense.
 
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