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Ultrasonic cleaning of old boards

Posted by: Bryant on 2023-03-13 18:54:26

This is not strictly a compact Mac question but there may be some fine points particular to them and similar age electronics.

Up 'til now I've been cleaning boards with IPA and a toothbrush, but I finally purchased an ultrasonic cleaner. I'm tested using diluted Stens 770-100 Ultrasonic Cleaning Solution on a couple of Mac Plus boards. I washed for about 4 minutes at 125 F. Then rinsed with distilled water followed by blow dryer on warm alternating with compressed air to blow the water from under the chips, then dry overnight. I haven't tested them yet, but they look great 🙂

However, some of my older boards have paper labels and stickers (e.g. on EPROMS). Should I remove these and re-attach after cleaning? It seems like they might clean right off otherwise.

Any other tips for cleaning 30-50-ish year old boards particularly?

Posted by: Phipli on 2023-03-14 00:50:38

The ultrasonic tends to remove pen and some printed ink. I'm not precious about it (I'd rather have a functional board than preserve the signature of the person at station 4 on the production line).

You could try applying an adhesive mask or tape over the labels?

Posted by: Byrd on 2023-03-14 01:13:00

Prior to cleaning Mac PCBs I tend to remove larger chips from sockets (ROMs, CPUs etc), old paper stickers and labels will become waterlogged and macerated but the plastic labels are fine.

Don’t forget you need to “degas” with detergent for 5-10 mins before immersing something, and I find agitating suspect areas with a soft toothbrush can help things along, same with spraying areas with IPA prior. Keep checking every 5-10 mins as sometimes very aged boards can suddenly tarnish quickly (or in the case of my wife’s cheaper jewellery recently, remove all trace of shine leaving a crusty white layer underneath!)

Posted by: Phipli on 2023-03-14 01:25:19

Keep checking every 5-10 mins

Check every 5 to 10 minutes? Yikes, how long are you running them for?! My machine would eat a hole in a board in 20 minutes!

Posted by: Byrd on 2023-03-14 01:47:50

I’m using a medical grade 10L unit; it honestly takes a good 20mins to heat up and act; are you using a cleaner for a boat? 😃

Posted by: Phipli on 2023-03-14 02:16:08

I’m using a medical grade 10L unit; it honestly takes a good 20mins to heat up and act; are you using a cleaner for a boat? 😃

I warm it up before I use it. I have a 10l and a 22l.

What cleaner are you using? I use this PCB and flux cleaner. I put boards in for 3 minutes at a time, one side at a time, and a maximum of 4 sessions with care. After that it starts discolouring the solder mask.

Ultrasonic PCB Cleaner and Flux Remover 5 LTR Fluid, for use in ultrasonic Cleaning Tanks and Baths, removes Debris, Dirt and Grease, 5 Litre : Amazon.co.uk: DIY & Tools

amzn.eu

Posted by: mg.man on 2023-03-14 03:20:27

put boards in for 3 minutes at a time, one side at a time

Semi-related Q... do you just lay the boards in the s/steel basket? If so, no worries / issues with direct contact (ultrasonic) vibrations? FWIW, I devised some "hangers" to suspend the boards I do - but not all boards have holes (for the hangers) in the corners. 🤔

Posted by: Phipli on 2023-03-14 03:59:10

Semi-related Q... do you just lay the boards in the s/steel basket? If so, no worries / issues with direct contact (ultrasonic) vibrations? FWIW, I devised some "hangers" to suspend the boards I do - but not all boards have holes (for the hangers) in the corners. 🤔

I lay them in the basket, usually angled. Only one board has stopped working after being cleaned and that was a many bodge monstrosity that I anticipate stopped working because of another trace failing. The fault is intermittent in the nubus circuit and I haven't gone searching yet.

Truth is I'd probably rather suspend them, but even with a 22l ultrasonic tank, I'd struggle to suspend a IIx board or similar.

Posted by: mg.man on 2023-03-14 04:10:37

Only one board has stopped working

I've only killed one SE/30 board - but that was probably down to over-sonicing it when I was getting started - I think I did 4 or so times of 5 mins @ 50C -- the more the better, right?? Nope. 😞

I'd probably rather suspend them, but ... I'd struggle to suspend a IIx board

😀 I mostly do smaller. I'll carry on with suspension-sonicing. 😀

Posted by: Phipli on 2023-03-14 04:14:56

I mostly do smaller.

I rarely do smaller than all the IIci sized boards. They just fit if you take the basket out, but need to be angled to go in the basket.

I considered making some standoffs with rubber feet, but haven't.

think I did 4 or so times of 5 mins @ 50C

That doesn't sound terrible - is something is marginal the ultrasonic will make it fail, but it might have failed next week anyway 🙂

Posted by: Daniël on 2023-03-14 05:12:11

I don't know if my cleaner is too aggressive (don't know off the top of my head what it is, but it was sold for PCB cleaning), I went for too long or went too warm, but I've had one or two boards with serious cap goop leakage shed their solder mask in tiny flakes during the cleaning process. That becomes a real pain in the butt real fast when doing further work on those.

Posted by: mg.man on 2023-03-14 05:29:05

if something is marginal the ultrasonic will make it fail

I believe it ended up being the '030 that died! I'd need to check - @max1zzz managed to resuscitate it! 😀

Posted by: max1zzz on 2023-03-14 05:56:43

I believe it ended up being the '030 that died! I'd need to check - @max1zzz managed to resuscitate it! 😀

Yep that board had a bad '030
I also killed your other board in the US after fixing it, in tHat case it was one of the VRAM ic's that filed

Chip damage in the ultrasonic is rare, but I have seen it twice, both with your SE/30 boards.....

Posted by: cheesestraws on 2023-03-14 06:04:31

so what you're saying is that @mg.man has a baleful influence? ;-)

Posted by: mg.man on 2023-03-14 06:14:27

@mg.man has a baleful influence?

I'm not the one with possessed stuff... 😛

Posted by: mg.man on 2023-03-14 06:17:01

that board had a bad '030

and... it was working OK until I decided to tidy it up in my shiny new US cleaner. 😞

Posted by: Phipli on 2023-03-14 06:23:17

and... it was working OK until I decided to tidy it up in my shiny new US cleaner. 😞

Did the new cleaner look like this?

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Posted by: cheesestraws on 2023-03-14 06:27:21

I'm not the one with possessed stuff... 😛

Fair point!

Posted by: mg.man on 2023-03-14 06:37:03

Did the new cleaner look like this?

No, but that looks PERFECT for my batt-bombed IIsi 'board!

Posted by: Phipli on 2023-03-14 07:11:17

No, but that looks PERFECT for my batt-bombed IIsi 'board!
View attachment 53628

Where is the damage, I can't see because of the toffee you dropped next to the battery, and tried to remove with a blow torch?

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