Oxide on chip legs

[fujidude]

Fine grit sand paper.

One of the appropriate products from Caig Labs, or similar product by other brand. A little goes a long way. I have a small bottle of Deoxit and Pro Gold G4 I have had for years.

[atari-dna]

Best thing to use is simply a scratch brush which is a fiberglass pen. It's cheap, and refills are available. I usually put a blade from a Swiss army knife behind the pins and gently scrub them (in the direction of the pin).

 

They will shine brilliantly. And this takes minutes. Bonus: no fumes!

 

 

[Osgeld]

I use fiberglass pens quite a bit, they do the job well, couple things to keep in mind

 

1) its still an abrasive and like all abrasives you can go too deep and get into the copper, which is bad as it oxidizes and looses contact pretty quick

2) those pens leave a fine fiberglass dust all over the area you were working, which instantly gets into my skin ... and im sure some small amount is airborne as well, degree of protection is up to the user

Edited November 20, 2015 by Osgeld

[Keatah]

I prefer to stay away from chemical baths and fluid soaking if possible, I don't like how they can wick up into the plastic IC body on some older less-well-made parts. A few minutes is okay. But not hours or days.

 

I prefer a gentle mechanical means, brushes, erasers, light abrasives for tougher jobs. After cleaning, you can polish up with some deoxit or contact cleaner. Just a little. Finally you can use a bit of dielectric grease, to prevent corrosion years into the future.

 

In some cases I just purposely break off the pin if it's pitted too badly, or it breaks off on its own. Then it gets a replacement pin.

 

If this is real classic electronics with important date codes, like my 4004, 6502, and aerospace stuff, I'll work under a microscope and go pin by pin. Observing the surface of each as I work. Not saying those things ever got into bad condition in the first place.

Edited December 3, 2015 by Keatah

[serpret]

This thread is pretty old, but I just wanted to add what our company does.

We sometimes have batches of CPLD's with oxide on the pins that don't solder very well. My boss puts them into a small polishing tumbler overnight ( i think sometimes two nights) and the next day they solder much better. It's the same tumbler that people use to polish rocks or bullet casings. You buy some abrasive media for it like walnut shell peices or they make these little abrasive pyramids and you load it in with the ic chips and then turn on the tumbler and it gently vibrates the whole mess together until you turn it off again.

[Keatah]

Doesn't that abrade the IC body itself?

Edited December 2, 2016 by Keatah

[CC Clarke]

Try a pencil eraser; this is a tried-and-true method that cleans without being too abrasive. It's especially good on PCB edge connectors. As you already know, solder only sticks to clean, hot, metal.

 

CC

[serpret]

Doesn't that abrade the IC body itself?

Yes, but it doesn't affect the body too much. And it's very nice if you have a batch of IC's that you don't want to individually deal with and you don't feel like messing with various liquid solutions.

[Trinity]

How about this stuff? DeoxIT

 

http://store.caig.com/s.nl/sc.2/category.188/.f

[Keatah]

Deoxit + mild abrasive like an eraser = the best you can get.

 

I've fixed noisy video and RF with this alone.

Edited December 8, 2016 by Keatah

[DavidMil]

Steel wool will remove just about anything from the 'legs' of the chips. You have to be careful not to bend the pins. As soon a you shine them up,

hit 'em with a light coat of solder to keep them clean. Remember that this will only work on the exposed surfaces. You may have a bunch of chips

that were originally coated in some sort of weatherproofing or buried in an epoxy. I have used a lot of liquid flux to remove crap from IC's in the past.

I used to drop the chips in just enough flux to cover the pins and then rub the pins with VERY hot soldering iron. Just don't leave the iron in contact

with the chips too long and watch out for fumes!

 

DavidMil

[KLund1]

Bring this thread back to life.

I have several hundred IC's that have back or dull gray corrosion on the legs. I do not want to shine the legs one at a time. Most of them have bits of the decayed anti-staic pad stuck to the legs as well.

I have a jewelry ultrasonic cleaner I can use.

[Keatah]

That allows the working fluid to enter into the plastic/epoxy IC case at the pin-case interface. There's no real seal. And most all consumer ICs are not hermetically sealed. And I also don't like exposing vintage ICs to ultrasonics, who knows what it'd do to the bonding inside the chip. Remember they're not mil-spec either. So..

 

You may want to set up a rotary pink eraser, not unlike a grindstone configuration, but very low-RPM. And use that to do the chips one-by-one, but 8 or 32 or 40 pins at a shot. A bulk buffer so to speak.

Edited June 28, 2018 by Keatah

[Zitruskeks]

Arcade Jason had a nice video about it, he used TarnX, which cleaned the chips perfectly with no overexessive abrasion, no bend legs in seconds.

 

https://www.youtube.com/watch?v=g_EaHKlwtZc

[Keatah]

Causes pitting in the tin coating.

[KLund1]

All good points.

I think I'll just clean and test as I need one. And not do them all in batches.

I did a small batch of 10 74LS00's in a jewelry cleaner with 1/2 ISA, and 1/2 nail polish remover (asatone) for 3 minutes. After I dried them, they all looked a lot better but still had some corrosion on the pins. 2 tested good. 6 tested better, but still were only at about 75% functional. 2 were still bad. I scraped off the all the pins on a bad one and it tested 100%, I did the same for a 75%, and it then tested 100%.

So it looks like bath is only partly ok, but runs the risk of possible wicking, or internal damage, but still have to scrape the pins. So probably best just to scrap the pins for a IC when I need one.

Thanks everyone.

[Keatah]

Additionally, you may want to brush on some Deoxit, of bulb grease/dielectric compound. This prevents moisture and oxygen from getting at the contact-contact interface (socket & pin). It's a time-honored method of increasing longevity and making future maintenance easier.

 

Ideally, you wipe with a razor, like a brushing action, not scraping, then eraser, then Deoxit or dielectric grease. Do it gently and you won't damage the tin plating on the chip at all. Same applies to switches and pots and really any kind of moving contact. Except with those, you don't use the razor edge, a rough cloth works best.

 

And if you have damaged the tin coating, the grease will stop electrolysis and corrosion from happening with the 2 or more dissimilar metals. Eliminates electrical hot-spots on the microscopic scale. While those aren't a problem initially, they cause higher resistance some years later. Then you gotta clean again. So lube-up!

 

I did this back in the 70's on those project kits and some SBCs, and the ICs slid right out of their sockets 40 years later with zero corrosion. And no black stuff either. An Apple ][+ and // I did this to back in 84/85'ish have had zero problems since and are likely good for another 40 years.

 

People bitch and moan about intermittent connections and switches and likewise, but the don't take a few extra seconds to preserve/prepare their equipment for the long haul.