Desolder IC chip

Hi,

First post, so naturally a noob problem…!

Started building my Shruthi last night, all going well til I realised that, instead of soldering in my first IC socket, I’d soldered the LT1054 chip itself directly to the PCB.

I started trying to desolder (using braid and a pump but no flux) and, though that removed most of the solder, it’s not removing enough (specifically the solder that’s flowed through to the top of the board.

I also tried applying heat to the legs at the top but to no avail. Then I stopped, concerned I’d do more damage than good.

What’s the best thing to do? I’ve read the other posts here and elsewhere dealing with desoldering, and obvs I can try with flux but am I likely to have damaged the chip by applying all that heat now? Better to bin it and get another?

On a related note: looks like I’ve melted some of the plastic around the holes in the board. Is that likely to mean I’ve damaged the PCB…?

Thanks in advance…

First and foremost, have you soldered the IC the right way? If so, you might want to consider just leaving it there without any socket.

You say you melted some plastic…please clarify, there is no plastic on the pcb.

Consider the chip as lost, cut the pins right at the body and despolder them one by one either with a solder sucker or desoldering braid to your taste. You don’t need additional flux if you bought the good desoldering braid with integrated flux.

If you burned your board you may have to route some wires to replace the destroyed lines and pads. Its just a 8 Pin Chip so this should be no major problem.

If it’s a relatively cheap chip, my advice would be to snip off the chips legs, then remove them one-by one. It’s the only way to do it, really, without specialist tools that heat all the pins simultaneously.

a|x

fcd72 got in there while I was still writing my post. But yeah- what he said… :wink:
Also, a good solder sucker is a good investment. I can’t remember the name of the one I have, but it was recommended by someone on this forum, and it’s a LOT better than my previous cheap plastic job.

a|x

Oh, there was the one from the Ebay UK seller precisehandtools, which is a small Japanese pump with a high-temperature silicone nozzle and then there was the combined solder sucker and iron that wasn’t that expensive.

@Varthdader: no, I think I soldered the chip in the wrong way around. I was following the instructions for the socket (as I now realise), which didn’t specify alignment. And by plastic, I guess I mean whatever fibreglass or polymer coating is on the PCB. Seems to have altered in look around a couple of the (otherwise very neat) soldered joints I’ve done. Hopefully is just cosmetic and fine.

@fcd72: checked spec and the braid does indeed got flux in it already. So might have to get busy with the clippers…

Elsewhere on the forum I read someone suggesting that covering all the legs with a single, massive blob of solder, then re-melting that to remove the chip might work (I guess because it conducts heat to all the legs simultaneously and makes it easier just to pull out. That likely to work, or is it a really silly idea?

Thanks all.

Oh, a snip like everybody said of each leg then!

Make sure you clean the area well after the removal, there might be a lot of flux that could look like plastic, or you lifted some pads.

Post a photo sometimes it helps!

What tends to happen is solder runs through the holes to the other side of the PCB or inside the holes. With a really good desoldering tool you can often get enough solder out, then wiggle the ends of the legs until it comes loose. Levering with a screwdriver can help too.

But don’t try any of the above unless you have a proper desoldering station, mains powered vacuum sucker.

OK, one last go at freeing it then snip it’ll be!

Final question: the two places I’ve found cheap replacement chips seem not to ship single bits (or charge loads for shipping). Is <a href=“http://www.amazon.co.uk/gp/product/B00419JYV2/ref=olp_product_details?ie=UTF8&me=”>this chip on amazon a good replacement for the LT1054 supplied in the Shruthi kit, do you know? Looks to me like it is but don’t want to make another mistake on the same component. My pride wouldn’t take it…

(Whoops. So html doesn’t work like that on here then.)

This chip:

http://www.amazon.co.uk/gp/product/B00419JYV2/ref=olp_product_details?ie=UTF8&me=

This one should work.

Desoldering by applying big blobs only works if you have a high power, temperature controlled soldering station. I have a 80W digital one and would not try……

Couple of quid cheaper on ebay.

My soldering iron’s only about 40W. So probably won’t try that, then.

Thanks again, everyone. What a brilliant forum!

@6581punk cheers - got one on ebay.

Ebay’s my primary source of small quantity stuff, less common stuff that’s hard to find with web searches. It was where I got my knurled nut driver after not finding one elsewhere.

I’ve bought SID, SSM and CEM chips with no issues.

@Jojjelito that was the sucker! I can highly recommend it.

a|x

toneburst: Yep! It wasaltitude who found that fantastic tool to begin with, all cred should go to him! I recommended it to a few local friends too :slight_smile: Great stuff!

Nhirst, I think you should cut the legs of the IC as it will get damage when you apply the heat to desolder and even you if you are successful to remove the IC most probably it will not work. So try to cut the legs of IC and then the desoldering will be easy for removing the legs and save your PCB.