Solder Pad lifted

[Almighty1]

I have a question, I was desoldering a capacitor and the entire copper piece which is the only thing in that solder mask lifted off the board, how do I fix this? I don't have a current picture but basically the copper piece came off the board, can one just glue it back with super glue like when I googled the subject or does it need to be conductive on the other side as well. It seems like this one is not part of the copper trace except it's a isolated piece that is the same size as the solder pad.

[tw2005]

Re: Solder Pad lifted

I have a question, I was desoldering a capacitor and the entire copper piece which is the only thing in that solder mask lifted off the board, how do I fix this? I don't have a current picture but basically the copper piece came off the board, can one just glue it back with super glue like when I googled the subject or does it need to be conductive on the other side as well. It seems like this one is not part of the copper trace except it's a isolated piece that is the same size as the solder pad.

undoubtedly a double sided pcb so the connection that counts is the top. That's what you need to make sure the solder flows to . I've done this, does not take much heat to lift those. I have used 5 min epoxy just to get the pad back which helps to secure the cap when it's soldered there, probably protect the top pad being torn if one was to apply pressure to the cap by mistake, otherwise won't matter

[Almighty1]

Re: Solder Pad lifted

You're right it's a double sided PCB but how does one know solder actually made it to the side where the capacitor is since the capacitor is sitting tight to the board, always wondered if one can use a Digital Multi-Meter to test for continuity but there is no trace for this pad so need to check the other side. I actually got these lifted when I was using solder only and didn't have the problem after I started to use the DeOxit/Radio Shack Rosin Flux. I thought about using super glue or epoxy but I thought the pad was supposed to be conductive since it's it supposed to connect to something. The pad really only lifted like 25%, should I actually pry the pad out and apply super glue or 5 minute epoxy or even Radio Shack's conductive wire glue before soldering? Thanks!

[tw2005]

Re: Solder Pad lifted

If it's only a little lifted , maybe try gluing that side down, but I'd just try soldeing as is. I'm sure there'd be a more profession way, as for checking. simple. Follow the track topside to a point you can probe, on bottom side just touch the leg of the cap. If you have room and it's a new cap , mount the cap high enough so if you have to solder the topside you can get the tip in. I had to do that on a Ymain from a sammy to be sure it soldered as it did not seem to flow from the bottom.

If you're not in a rush maybe wait for some other opinions from some of the pros

[Almighty1]

Re: Solder Pad lifted

It seems like if the cap is tight, then that leg must be soldered tight except not sure if solder made it to the other side. The top side is hard as there are cap and other things next to it so I can't even figure out where there trace is. I originally was thinking about mounting the cap with the leads extended so it sits above the board but it seems like reading the forums, people seem to recommend the base of the cap to sit against the top of the board. I noticed there are some things where there is a base pad without a trace on the bottom and then the top has has a metal circle but there is no trace either, maybe it's just used for support and not actually transferring any form of current. My other thought is I did manage to get a pad to completely lift off and and looks like burnt black flux but I couldn't see what's on the other side of the burnt flux.

[rhomanski]

Re: Solder Pad lifted

There is usually a metal sleeve or ferrule lining the hole connecting the top run to the bottom copper run. This allows for capillary action to spread the solder throughout the hole top and bottom. The rule for soldering is 5 seconds of heat. If it doesn't solder properly in 5 seconds you haven't prepped it good enough and need to regroup and try another way.

Leaving the pencil on too long melts the glue holding the copper run and then any physical movement pulls it up from the board. To fix it make sure the metal ferrule is still in the hole and is still good where it connects to the run under the cap. Some boards have runs between two layers of board. They actually have three ways for copper to run. You have to ensure conductivity with that run as well when your done on those.

Cut the lifted run back to where it's still solid with the board. Scrape it clean of any coating. Put your cap in the hole and put some flux on it, liquid is best, and heat it, apply solder. If it's sucked in the hole, you know it's making it to the upper contact pad.

After that, wrap a cut off lead from the other side of the cap around the lead in question. Run it over to the run you cut and solder at both ends, cut the remaining lead and you should be ready to go.

[Almighty1]

Re: Solder Pad lifted

Thanks rhomanski for the pointers. It was actually the desoldering that caused the pad to come off.

[rhomanski]

Re: Solder Pad lifted

Sure, desoldering is almost always where the damage is done. For through hole, I use wick. With practice you can still do a double sided without damaging anything. Soldering is a lot like welding, it takes practice. Knowing the fundamentals is crucial though, saves a lot of time over having to figure it out for yourself. In one of my classes we got a guy from the previous class, he couldn't get a flat pack right. They kept bringing him back for another go with each new class. He still couldn't get it right when I left the class. I imagine he came back for that day in the next class.

[Almighty1]

Re: Solder Pad lifted

What happened originally was I thought capacitors needed to be completely tight meaning when you try to push it, it shouldn't move at all so I was trying to fix that and that was what was causing it but those pads never completely lifted off but only a little so that was okay on the main PCB of the PSU. It was trying to get the mini-board out of the daughterboard that was what was a pain in the you know where as basically it took lots of heat before the thing would even slightly move and then when it did, two of the metal sleeves were stuck to the pins resulting in one of the traces being torn out, ofcourse the three pads also lifted off except one was physically part of the trace and not a separate piece. So what I ended up doing was first take the metal sleeves back out from the pins and then used non-teeth pliers to push the metal sleeves back where they belong and for the one with the broken trace, I basically scraped the solder mask off exposing the copper and then used solder to get them back together and then using a Digital Multi-Meter to check for continuance to make sure the rest of the trace can see it. I tried to use 5 minute epoxy, the one that comes in two separate bottles to put the two lifted pads back and allowed 24 hours for it to dry except when I tried to put the mini-board back, the pads lifted off again as the epoxy doesn't seem to hold it well. The only problem is small square pad in the middle completely melted when I tried to apply a layer of solder to bond it to the pad so basically now, the board is bare naked for that hole, is there anything I can do to fix that one? Wonder what type of material was that pad made out of. The front side with the metal sleeves is secure with the soldering and I've checked all the traces which on both the front and backside where those pins lead to with the digital multi-meter and they all conduct current fine. Pictures are attached to the post. Sure a lot of trouble to change that one capacitor on the mini-board.

As for using wick to desolder, that seems to be hard if I'm trying to clear the hole of the solder since the front side usually has wires or something next to it and it's not easy to do with two hands since I can only hold the soldering iron and one other thing at the same time, I still don't know how people can hold capacitors with their bare hands when it can get fairly hot pretty fast both on the PCB itself and the capacitor. I think with everything, practice always is a good thing but it helps when I actually see it demonstrated in-person since learning online is still not the hands-on experience.

[Agent24]

Re: Solder Pad lifted

That's a tricky one. Because it's plated through-hole, a one-shot desoldering pump or wick won't clear the hole easily (if at all)

You really need a vacuum desoldering tool, but the pins look large so finding a tip that fits could be a challenge.

Another way would be to find a way to heat all the pins at once, either with a hot air rework tool and appropriately shaped nozzle or selective reflow soldering machine (Lots of $$$) - the cheapest solution may be just a really big iron so you can heat all the pins at once and then pull. Clean up with wick or one-shot tool.


I personally would probably have tried to make room to work on the board by removing the coil and capacitor behind the board instead, as they would likely be easier to deal with (Round leads typically desolder easier than square, too, especially if they are quite tight in the hole)

[rhomanski]

Re: Solder Pad lifted

Honestly, wick would probably be best for that job. I just removed three boards like that from the main board of a cassette deck from 1985. I sucked up as much as I could on the bottom of the board , let it cool, sucked up as much as I could get from the top. Wiggle, pull, wiggle. Try to suck up a bit more and eventually it comes out. Then you clean it up with more wick. I use liberal amounts of flux it helps spread the heat. The wick also acts as a heat sink so it gives you a touch more time before damage is done.

From your pictures Your board is only connected electrically to one side of the board anyway. The top one is connected to the bottom of the board only. The other two are only electrically connected to the component side of the board. The missing pads are only for assuring the physical connection of the two boards.

I'd say just solder what you can and let it go. Those lifted pads aren't really necessary anyway. They take the place of glue on large capacitors.

Yeah, that burnt up square pad was electrically not connected so not really important. Just solder what's left and make sure it's physically secure and let it go. I mean make sure it's not very wobbly.

[Almighty1]

Re: Solder Pad lifted

@Agent24,

I wonder what kind of material did they use for the middle plate because it seems like that material melts pretty easily compared to the other pads. It wasn't hard clearing the hole since it was a large size, it's the smaller holes for capacitors that seems harder to clear as those, the only way to get the solder inside the hole to melt is to actually have the tip inside the hole.

How do you heat all the pins at once with a big iron since the tip will only be able to touch one pin at a time as you can't lay the iron flat without doing major damage to the board. I know that a hot air rework tool would work but I can only work with the equipment I already have since I only solder once in a blue moon and getting a hot air rework tool just for this fix of my own PSU is not going to be cost effective. The way I even successfully desoldered the thing was using a wide chisel tip.

I was thinking about removing the coil except it seems that one has 4 legs which are all far apart from each other, not to mention there is also the yellow glue holding it down and getting to the glue seems to be even more work than taking out 3 pins. The metal sleeves slide off the square pins on it's own when I heat the pins above the metal sleeves, same thing with soldering the mini-board back, it seems like the metal sleeves would slide off onto the pins from the board until I had the sleeves on the bottom and heated the pins above the metal sleeves. I was using lots of rosin flux but it didn't really help, maybe because the solder is old or something.

@rhomanski,

I'm actually worried about trying to use a wick on the top side as it seems like I can melt something else like the plastic connector by accident quite easily.

As for the way the three pins are connected, it goes like this after I looked at it carefully to do the continuance test using the Digital Multi-Meter:
Top pin is connected to a trace on the back of the board that goes to the 1st pin of the J7 connector and then on the other side of the trace, it goes to the coil, the blue rectangle capacitor and also the last 3 pins of J11.

Middle Pin is connected to the coil on one end, then the other end of the trace goes to the white rectangle capacitor at C102 before going to pins 3 and 4 of connector J7.

The last Pin is not connected at all on the back side and the trace is on the other side with one end going under the coil and under blue rectangle capacitor C107 and connects to pins 4 and 5 of connector J11 while the other end goes under the white rectangle capacitor C102 before ending up at pin 2 on connector J7.

Speaking about capacitors, if one lead of a capacitor is sharing the trace with a pin of a IC, would there be a problem if I accidentally created a solder bridge between the two since they are next to each other. I'll attach a picture to show what I mean. Even on the other side of the board, there is a trace that runs between that IC pin and the metal sleeve of the capacitor lead. From what I understand, as long as something is part of the same solder mask, soldering them together would not create problems.

As for the burnt up square pad, are those supposed to be made out of copper since I thought it wouldn't have melt that easily but I basically did another fix by melting some 60/40 solder at 218C so that it is larger than the hole just to make the pin physically secure and made sure it passed continuity.

[Agent24]

Re: Solder Pad lifted

How do you heat all the pins at once with a big iron since the tip will only be able to touch one pin at a time as you can't lay the iron flat without doing major damage to the board.

Was thinking something like this: http://www.somersetsolders.com/produ...ng_iron_ab3178

Probably need to run it through a light dimmer or something though to control it a bit...

[rhomanski]

Re: Solder Pad lifted

That middle one is smaller than the bottom one, it's not connected to anything so will heat faster. It's made of the same material as the others.

Are you using a soldering pencil or a gun. You should be using a 30 to 35 watt pencil with a small tip. If your careful, you could get a small tip in there and not damage the plastic. I've had to work in tighter spaces before. It takes practice.

From what I'm seeing that spot the arrow is pointing at looks okay. Not very elegant but functional.

To clean the old flux, I use acetone. Use it only in a well ventilated area, don't get it on your skin unnecessarily. A little won't hurt, just don't wash your hands in it. Women use it to remove their finger nail polish so it's not instantly lethal.

Years ago we used to have a tip for a pencil that was basically a stick with a bar welded at the tip. You put it up against the large IC's and it would heat up all the pins at once. You could then pry up that side of the IC a tad. Heat the other, pry it up. Repeat until you got it loose. Some even had grooves cut in the bar at the same spacing as the chip leads. You could install with that too, by cleaning it good and then cutting off small pieces of solder and placing them down on the table. Then bringing the tip to touch on each piece of solder all at once. It would melt and suck up into each groove and then you touched it to the pins. The solder would stick to each pin individually at the same time. Quick in and out. Then you inspected each leg for proper solder adhesion. Time was the key. Too much heat would kill the new chip.

That's the only tool we had for melting several pins at once. As the components became smaller, new techniques were developed like hot air guns and such. I'm afraid I haven't kept up with them. These guy's here talk about throwing boards in the oven. I've never done that.

I recapped one of my power supplies recently and a monitor but mostly I work on old stereos now.

[Almighty1]

Re: Solder Pad lifted

Agent24, I guess when you meant big, you meant both physically big and high in wattage big too. LOL.

rhomanski:

This is what I am using:
http://www.gotronik.pl/stacja-lutown...cmc-p-549.html

For the back side where the joints are, I used the 3.0mm wide tip as the 0.3mm tip didn't work at all. For the other side, I used the 0.3mm tip. You're right it takes practice and being extremely careful.

As for acetone, wouldn't that melt the PCB as well? I've used 100% acetone fingernail polish remover before to clean the top of the CPU for new thermal interface material so its pretty safe except I know it can strip off paint and melt plastic even a little.

The pencil with the bar welded at the tip sounds like it would work which is similar to hot those hot air stations work except I do wonder with the hot air stations, wouldn't it cause a bad joint in the components you're not repairing?

As for the PSU, it's a PC Power & Cooling Turbo-Cool 450ATX from 2000/2001 and after replacing all the caps, it is working fine. Not sure if it's the -5VDC or not, but somehow at the same 100% load which is probably due to the caps on the motherboard, the PCP&C PSU seems to allow the mouse to move while with the replacement Corsair CX750m I was using for the past month, that one was like really lagging as the mouse was non-responsive, maybe the PCP&C just delivered better current to the motherboard or something. The motherboard is being recapped now.

[Agent24]

Re: Solder Pad lifted

Agent24, I guess when you meant big, you meant both physically big and high in wattage big too. LOL.

I meant physically big mostly, that iron I linked to would surely destroy boards if used as-is. Why I suggested running something like that through a dimmer or such to keep the temperature in check to the standard 350 degrees C or thereabouts.

[rhomanski]

Re: Solder Pad lifted

That's a nice pencil, I like it. I guess it's just the user needs more practice, Lol.

Glad it's working.

[retiredcaps]

Re: Solder Pad lifted

I have a question, I was desoldering a capacitor and the entire copper piece which is the only thing in that solder mask lifted off the board, how do I fix this?

I have seen several questions from you regarding fixing soldering problems.

While old, these videos from Pace are excellent.

Start with part 1 and continue.

http://www.youtube.com/playlist?list=PL926EC0F1F93C1837

http://www.youtube.com/playlist?list=PL958FF32927823D12

[delaware74b]

Re: Solder Pad lifted

^X2 on using acetone for removing flux.
I actually use acetone-based brake cleaner (CRC green-label) and not had any issues using it.