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Solder pad replacement

T

the3dfxdude

Experienced Member
Joined
Jan 11, 2019
Messages
263
Location
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Hi all,

I have a VLB video card here that had a surface mount tantalum cap torn off along with the pads. The tear does not appear to have gone into the underlayer, so the only real damage is the missing pads. The cap is missing of course, and the card still works. It was a ripple supply cap for the main IC. Since I would like to try to put it back into use, and for it to have survived this long, I figured it's worth trying putting a new one on. The thing is, how do I attach it?

There are thin slivers of copper that my probe can touch that connects to the 5V and ground sides. What can I do to ensure the solder flows and makes a good connection?
 
Should be fixable, can you please upload a photo of the whole card and a close up of the capacitor's footprint?

You can buy board repair kits, but it might not be necessary for this.
 
The thin silvers (traces) may or may not be covered with solder mask. If they have solder mask, you won't be able to solder to them. You might be able to scrape enough of the mask off to make them solderable. Generally you would run a wire from the part to another place, so if there are other parts that also have the 5V/GND connections, you may be able to add the main cap to them directly or via some jumper wires.
 
IMG_2793b.JPG

The vias are next to the pads, and they are still there. On one, you can see the solder mask is gone, and the other, might have lifted the mask a little. On the one that's still partly covered, you can probe it on top of the via still, and on the side where the pad was.

It would be nice if I could attach some metal to bridge from the via onto the pad to give it a good foundation to solder to rather than trying to solder directly to the vias.
 
Thanks for the photo. It looks like the top via has lost the plating around the hole? Does it share a connection (5V, GND) with any of those resistors nearby?

If you want the card to look good cosmetically you would need to cut new pads from very thin copper, or use a board repair kit.

But what I'd do is carefully scrape all the solder mask off the via at the bottom of the photo, then solder one pad of the capacitor directly to that. Then for the other pad you could use a wire to join it to another pad on the board (like those smd resistors nearby if they happen to have the correct 5V/GND connection). You could also run a very thin wire through the hole in the via and attach it on the other side (although wire this thin isn't great for power, so it would need to be really short).

Oh, and use heaps of flux when soldering. ;)
 
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