How To Clean a Vintage Circuit Board Assembly?
I have a vintage computer board that is contaminated with decomposed anti-static foam. The microprocessor and other ICs have a sticky grime on the leads. I want to preserve it and make sure it will be operational. Jim Hall and Phil Zarrow, The Assembly Brothers, offer suggestions. Board Talk
Phil Zarrow, ITM Consulting With over 35 years experience in PCB assembly, Phil is one of the leading experts in SMT process failure analysis. He has vast experience in SMT equipment, materials and processes.
Jim Hall, ITM Consulting A Lean Six-Sigma Master Blackbelt, Jim has a wealth of knowledge in soldering, thermal technology, equipment and process basics. He is a pioneer in the science of reflow.
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And welcome to Board Talk with Phil and Jim, the Assembly Brothers, also known as ITM Consulting. We’re here to help you with your process, assembly, problems, methods, equipment, materials old and new.
Speaking of old Jim, this is a real interesting one we have here from J.W. J.W. writes, I have a vintage computer board that is contaminated with what appears to be decomposed anti-static foam. The board has been in storage for forty years. Hey, who does this remind you of?
The microprocessor and other ICs on this board have a sticky grime on the leads. Due to the rarity and value of the board, I want to preserve it and make sure it will be operational. It has been suggested that 90% isopropyl alcohol soaked on the entire board followed by brushing with a soft toothbrush is recommended. Do you have any other thoughts on how to tackle this problem?
Time stamp, forty years ago is before no-clean. So, this was either assembled with an RMA or a water-soluble and it was probably cleaned one way or another. The degrading static-foam could be anything. Alcohol might clean it. Alcohol is certainly a safe thing for most products.
The one thing with cleaning in general, Phil, is that if this a completed board. There may be things on the final assembly that were put on after cleaning that aren’t compatible with any cleaning. You really need to determine that.
Open switches, open coil devices and things typically if it is not a no-clean process, they are added as secondary ops, after the entire board is clean. You want to make sure of that. My advice would be to try a little alcohol on a rag or a Q-Tip or something on specifically the contamination that you are looking at on these leads and see if it cleans it. If it does, great.
If there is nothing that can’t be cleaned on there, then alcohol is a safe solution. Alcohol doesn’t clean everything. You may find that the alcohol doesn’t clean this residue that you are seeing supposedly from the decomposed anti-static foam.
In that case, you are going to have to look for a stronger or a different cleaning solution, a solvent or an aqueous material until you find one. Then clean the whole board with that. Again, being conscious of what else is on the board.
Right, my brother has once again given us wonderful, sage advice. I would say going back forty years ago, as Jim mentioned before the Montreal protocol, I think there is a good chance if it was a computer board this board was built with RMA fluxes and probably originally solvent cleaned and a vapor degreaser. Remember that?
Good old tri-chlore and other great stuff. Freon, yeah. You have to watch out for that tricore attacking that might have been done, as Jim said secondary operations. I think Jim’s advice and the inclination is trying an isopropyl first.
Beyond that, I keep getting these flyers that vinegar does all of these great things. It might make it smell kind of funny. I actually had a board a while back that I dug up from my archives. This thing was probably from the late 60s, maybe even earlier. It had core memory on it.
I wound up cleaning it using a saponifier. I took it over to one of my friendly saponifier suppliers and we ran it through a clean with saponifier. There wasn’t anything from concern from a water-standpoint and secondary ops. Also, I wasn’t going to attempt to make this board operational. That is really very ambitious of you J.W.
You know Jim, thinking about this forty year old board, you realize that this board is probably older than a lot of people listening to us on Board Talk.
You’re right, Phil.
We hope we gave some good advice here. We both hope our listeners and readers will chime in with some thoughts too. Beyond that, no matter how old your board is, if it is an old fossil like Jim and I, then whatever you do hope it wasn’t soldered by my brother.
And I hope it wasn’t soldered by my brother.
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