How to Fix Broken IC Pin

[bostonman]

Has anyone had experience soldering a jumper to the broken pin of an IC or shaving some of the body away?

I'm thinking I can solder a jumper wire into the hole of a socket (I planned to socket this IC regardless), but not certain how to solder to this broken pin.

Enough metal may be exposed that I can get a tiny bit of solder, but thinking it will not hold and heat/cold will cause it to break off over time.

I'm reluctant to try shaving the body, but think it's the only option.

Any ideas?

[IanB]

That looks like enough exposed metal to solder to. Get a blob of solder to stick to it, then reflow a very thin tinned length of wire onto it. Use a very thin, flexible wire, because the joint will not have much mechanical strength. Attach the other end of the thin wire to a short stub of much thicker wire to go into the IC socket.

[bostonman]

The thin flexible wire is good advice, I would have went with a standard piece of bus wire and it would have been too stiff.

I agree on having enough metal to solder to since I'll probably use very thin wire. It looks close, but I fear trying to shave the plastic is too dangerous; although if successful would provide more metal.

[NiHaoMike]

The actual chip is at the center of the package so scraping away the plastic on a corner pin is low risk. Start using a hacksaw at an angle with light pressure and switch to a scalpel when you get near the pin.

Once you have a wire soldered on and verified a good connection, secure it in place with super glue.

[WattsThat]

Yep, I’ve done it. A liquid spill on a HP chip led to electrolysis which ate the pin away.

A Dremel tool with an abrasive cutoff blade works well on an epoxy package. You only need a millimeter of copper lead frame to attach to. A single strand of wire from a piece of stranded 22-24 gauge works well.

Safety glasses are mandatory.

[EPAIII]

I've done it too. But a full mm may be a bit risky. Just expose enough to get a small blob of solder on it.


And order a new chip ASAP.

[m3vuv]

ive done this a few times,just be carefull and use a magnifier,i normaly put some araldite over the solder joint after wards for a bit of mechanical strenth.

[Ian.M]

I've done it too. But a full mm may be a bit risky. Just expose enough to get a small blob of solder on it.


And order a new chip ASAP.

There's no risk carefully grinding back the resin to expose more of the leadframe for a corner pin as its a long way from the die.   A small inverted cone burr in a dremel or similar at low to moderate speed should let you expose a mm or so fairly easily.  You can probably get enough joint area to let you solder on a replacement pin rigidly enough to survive use in a socket if you support the joint with a little epoxy.

[bostonman]

And order a new chip ASAP.

Thanks for all the advice. Unfortunately this is an obsolete chip - although I can buy new variation designed by someone - but I'd like to try keeping the original.

[m3vuv]

stop beeing paranoid and try it,you cant make it any worse can you !

[bostonman]

Hahah I planned to give it whirl.

I was simply stating that this is an obsolete chip,

[Peabody]

I think success is more likely if you never move it again.  So if you solder all the other pins, and solder a wire or the replacement pin into the hole, then bring that up to the stub and solder it, it will probably work fine.  Physically it will have very little strength, but there will be no strain on it that would break the connection.   If you'll be needing to move this chip into and out of a socket, then mount it permanently into an intermediate socket.

[bostonman]

If I have enough headroom, I planned to place this chip into a socket, solder a wire to the stub and into the socket pin, and then plug that socket into the socket soldered onto the board.

I do like the idea of trying to expose more metal though and inquired based on wondering if a specific method exists. Seems a few methods exist based on various approaches, but nothing that secures a safe approach.

Obviously removing too much plastic will expose the find wire soldered to the leg, so it's important to only remove a hair should I take this approach.

[DrG]

I had success regenerating salvaging use from broken (corroded all to hell) pins on an IC using a socket. At least one pin was down to the nub as in your case.



Not terribly neat, but the chip functioned ok.

I also remember (many, many years ago, modifying a TRS-80 for lower case and soldered wire wrap onto  a pin in circuit).

I think you can probably do this, but then again, it's your chip.

[andy3055]

What is the part number? Someone might have one in their old parts stocks, including me!

[bostonman]

This is a PLA for a C64.

Alternate 3rd party replacements exist, and I have a few, but no sense discarding this over a broken pin.

[andy3055]

I do not have one of those unfortunately.

You can use one of those "needle files" to carefully remove some of the casing on either side of the pin. You will have more control than using a motorized tool. Also, the vibrations introduced by a tool like that might do some internal damage.

[DavidAlfa]

Sure, with steady hands, just scratch the epoxy to expose the  metal.
I did this some months ago on a tqfp package with water damage, the pins and pads were completely gone!

[bostonman]

I took the advice of manually filing the case.

Thankfully I have very small files, and, under a microscope, was able to file away the case much quicker than I had expected.

Once I got deep enough, I began filing downwards towards the pin and then took a small blade and scrapped away the remaining thing layer - I didn't want to continue filing and file away the metal pin.

I have a set of resistors with very flexible leads, so I soldered the lead into a socket (although now I'm thinking maybe I didn't need to), cut to length, bent the lead 90 degrees so it laid across the exposed pin, and placed a blob of solder.

It came out much better than I expected and quite strong. My only concern is in the future I may forget about it, attempt to remove the IC,and rip off the pin. I considered soldering a pin at the opposite end, but these sockets have flimsy pins and I fear they may break, so using epoxy or soldering additional pins may result in an issue should I ever need to replace the socket.

The sockets I've come across at old jobs were much more durable, the sockets I've bought at a local electronics store made by Philmore look like the pins are made from much thinner metal.

[andy3055]

Please post a closeup of what you did.

[Alex Eisenhut]

Brings back memories. I had a KERNAL chip that lost a pin and I did pretty much the same thing. I soldered it into a socket. Those were the days of trying different fast loader ROMS.

[bostonman]

I'll post a picture later today.

The broken pin was my fault, I should have devoted more time to properly unsoldering it from the board, however, I also thought it was causing the failure since it's the main chip failure and didn't give much effort into saving the chip.

[Ian.M]

My only concern is in the future I may forget about it, attempt to remove the IC,and rip off the pin. I considered soldering a pin at the opposite end, but these sockets have flimsy pins and I fear they may break, so using epoxy or soldering additional pins may result in an issue should I ever need to replace the socket.

Use Kapton tape to strap the ends of the IC to the extra socket.

[bostonman]

Here are the close up pictures.

The Kapton tape is a great idea, but it may impede heat dissipation.

[andy3055]

Great. I was just thinking if it would be possible to clip off a pin from another un-usable IC and solder it there. Dig deep in and cut it off so that it will have more length. That way, you don't need to solder the pin to the socket.

BTW, if you are concerned that you might forget and try to pull it out at a later date, just past a note with a warning sign on the surface. Anything that will draw your attention.