How to clean Oxidised / Rusty ROM's

[TheDaddy]

Hey all , So not sure if anyone interested in this but hopefully may help some. I have many boards that are just for spares and often come across boards with Rusty socketed ROM's and though I would share how I try and save as many as I can. I only do this with boards I think are un repairable or crappy games ( Street fighter 2 is peppered with good TTL and RAM , I have a few of these. A lot of ROMS are socket though and are mask roms so not many of them on there).

In this particular case I had a board with board rot and there was some corrosion on 99% of the chips. Some were worse than others , The bottom board was a bit better but still needed both stages. There are 2 ways I clean the chips depending on how bad. I have fixed many a board with this method.

What you will need :-



1) IPA Alcohol
2) A toothbrush / Or cleaning brush (A smokers toothbrush is always good IMO)
3) A Fibre pen
4) Piece of sandpaper (Not course sandpaper , fine Finishing sandpaper is more than enough)
5) A Stanley knife blade.
6) OPTIONAL :- A pair of gloves !!
7) A little time and Patience !

So this is the top / Bottom board where I removed the chips , There was a few 27c128 But mostly 27c256 (I had none left so this was a bonus), Around 20 256 I think.




So I removed all of the available chips and 50% were really bad, I first removed the sticker on the top using the Stanley knife blade. Remember kids you may want to get an adult to help you out with this (Blue Peter Style !)





So this is Stage 1 , If you are just cleaning a rom skip to Stage 2.

So first, as these are real bad , we need to get rid of the rust without destroying the rom legs. You will not save all of the roms , I had around 4 that the legs broke off , This is unavoidable. I would prefer 16 than none ! So stuck these in the tester and legs failed (Expected obviously !)



Some did test a lot worse than this but this was enough to photo for information purposes.

I took these over to my bench , Popped my gloves on & got the sandpaper out. I sanded both sides slowly , Checking as I went to make sure I am not removing too much. Go steady no rush here and DO NOT press down to hard soft and steady here :-



I use a circular motion as this seems to work best. After several goes an both side (Including the inside) they look a lot better :-



Stage 2 :-

So its time to get rid of any bit we could not get too with the sandpaper and clean with the Fibre pen. This take a bit of practice as you can bend the pins , I tend to put the side you are working on a flat surface. The idea here is to rub pretty much around every pin as best you can.



After this is done , its time to use your toothbrush and IPA to thoroughly clean the chip and get rid of any filings & dirt.

TIP :- we all goto McDonalds , I grab lots of there serviettes when I got and take them home saves me buying kitchen role ! lol

Anyway once done and cleaned pop these into your UV to wipe them & you should have this result in tester :-



Most chips do not require Stage 1 , This is only realy when the rust / oxidation is too bad and that is fairly rare. Stage 2 is an absolute must for anyone experiencing problems as this is the second thing you should be doing (First is check voltages !!!). I have fixed many a board using the above , trust me many !

If pins fail on test they repeat as required , Some chips will be beyond saving but there should not really be that many unless the legs are completely rotten !

I have done this in the hope it will help others to maintain / repair there boards. The above is how I personally do it , I am sure there is many other ways that works for others as well. There is no rights & wrongs just ' Works for me '.

Leave a message if you like, Always nice to know people are reading and what they think.

Dave.

P.S Only aloud 10 images so had to tone it down a bit , Hopefully enough !

 

[ArcadePCB]

I would not recommend sanding IC legs if possible because it destroys the tin coating and makes it more likely to fail in future. I try to use a glass fibre eraser you use in stage 2 first instead of sanding paper, because it takes away much less material. Of course, you have to have much more patience, too and it doesn't work all the time. But if it works, the coating of the legs isn't destroyed completely.
The worst chips to clean are NAMCO customs in my opinion, because the legs consisit of steel and tend to rust inside of the tin coating if they were stored for years in a environment having high humidity. So if this happened they break immediately when pulled out of the socket.
EPROMs often have copper alloy legs so they tend to become green rather than rust away. So there is a good chance to get them saved.

 

[TheDaddy]

Thanks for your input , i know its controversial but As i say stage 1 is worse case when you cant use a fibre pen to get rid rust / oxidised legs. I have been doing it this way for many years and never realy had any issue. Always try stage 2 first as also mentioned. I find this better than chucking them in the bin.

What coating is on the legs ?? I thought it was just aluminium ?

Dave.

 

[Mr20to5]

Love your recent posts. Find them really helpful. Thank you.

 

[ArcadePCB]

Thanks for your input , i know its controversial but As i say stage 1 is worse case when you cant use a fibre pen to get rid rust / oxidised legs. I have been doing it this way for many years and never realy had any issue. Always try stage 2 first as also mentioned. I find this better than chucking them in the bin.

What coating is on the legs ?? I thought it was just aluminium ?

Dave.

If it would be aluminum, you wouldn't be able to solder it directly into a PCB. Aluminum is oxidating immediately when cut / filed / scratched. This prevents soldering. I've read about a method using a drop of oil to keep the oxigen of the air away and scratch in the oil. Then you have to solder in the oil drop. There is also a very special solder with a special flux inside you can use to solder aluminium (I've never tried one of both methods), but with an ordinary solder in the common way you will have no chance.
I think the legs are tinned, but if anyone knows better, let me know, please. It must be at least a material that can be soldered very well.

 

[TheDaddy]

Sorry i was totally wrong with the Aluminium I meant steel ! Long day. According to the web its Copper plated with nickel or nickel alloy.

Dave.

 

[ArcadePCB]

Thank you for this information.

Bernd

P.S.: And yes, of course I totally agree - rather sanding than throwing it in the bin.

 

[TheDaddy]

Had a look over the net and seems others do this also and seem ok to do.

Here is one :- https://maker.pro/forums/threads/ic-socket-corrosion-removal.291809/

Or Another :- https://forum.allaboutcircuits.com/...ng abrasive,to protect from further corrosion.

Dave.

 

[Funhouse71]

I tend to use car polishing cones in a cordless battery drill with a bit of liquid car polish of your choice and a splash of water on the cone itself, it brings the legs of the pins back to a gleaming brand new shine without being too abrasive, removes just the oxidation and not the leg coating.

https://www.amazon.co.uk/Paor-Foam-...ocphy=1007091&hvtargid=pla-421299789349&psc=1

For the inside of the legs I use some wet and dry paper soaked in water, again so not to be too abrasive.

If I get a chance I will post before and after pics using this method.

 

[TheDaddy]

I tend to use car polishing cones in a cordless battery drill with a bit of liquid car polish of your choice and a splash of water on the cone itself, it brings the legs of the pins back to a gleaming brand new shine without being too abrasive, removes just the oxidation and not the leg coating.

https://www.amazon.co.uk/Paor-Foam-...ocphy=1007091&hvtargid=pla-421299789349&psc=1

For the inside of the legs I use some wet and dry paper soaked in water, again so not to be too abrasive.

If I get a chance I will post before and after pics using this method.

Yeh be great to see how you do it as well. I never though of wet and dry, may be less harsh ?

Dave.

 

[Phils Arcade]

As above, sandpaper, even wet and dry, will remove the tin coating that was protecting them. This means they will corrode faster. It is possible to get a tin electroplating kit, to reapply the tin coating back onto the pins.

Steel corrosion is the worst. If this happens, there's very little you can do. The corrosion tends to travel along the steel and into the chip itself. If a custom chip and the leg has disintegrated it may be possible to remove some of the plastic around where the leg goes into the chip with a Dremel, and if still clean, solder a new one on. Not the prettiest, but I've had some success before.

 

[Funhouse71]

I polished a tarnished chip tonight using the cone...here are the results

 

[karlcdoe]

I've often considered using the left over bottle of Farcela cutting/finishing compound I have on the shelf from painting my car a few years back. I've used it, brasso or t-cut with good effect of things like copper based motor commutators and cleaning the contacts on distributor rotor arms that are too hard/expensive to replace (or the replacements are crud).
Mind you P2000 and above wet and dry paper is pretty mild and I have used it or a pencil eraser on Ics in the past with some success (as long as you get rid of all the bits of rubber in the latter case) None of it is ideal. I used to have a quite a lot of isopropyl alcahol for washing things down but that supply has long dried out (pun intended).

 

[Alpha1]

I lightly sand with fine grade sand paper