Needing ultrasonic cleaning solution for old dielectric grease.

[Rat_Patrol]

Sorry, not sure if its the correct forum, but this is repair orientated.

I will be salvaging to reuse a metric ton of old PCB to harness connectors. Easy enough to remove and toss in the ultrasonic cleaner, but so far I can't seem to get the old white dielectric grease off the pins. So far, I've used branson EC, Flux-Off aqueous, IPA (does an OK job, but not good enough, plus I won't run it in my big UCs).

The connector is some kind of polymer that doesn't seem to really be a thermal plastic. It tends to burn and not melt. Its very hard, vintage late 80's to early 90's. The pins are standard gold-plated pins, but not very accessible.

Right now, I have to dip a Q tip in IPA and scrub them manually. Its easy enough after soaking long enough in IPA, but that is time and time is money.

Anybody have a good experience of a particular ultrasonic cleaning solution to try? I don't want anything toxic, as the UCs are in my lab with me. The Flux-Off is bad enough.

[TheMG]

Most dielectric grease is silicone based, so alcohols and water based solutions won't do much.

You'll need an organic solvent. I would first try mineral spirits, as it would be the least harmful of the various options, and commonly available.

[DaJMasta]

I haven't tried it, but I've heard common industrial cleaners/degreasers can be a good option for ultrasonic cleaners.  It may depend on what other parts are on the board, I'm sure there are some components that could be damaged by it, but just water and something like simple green could do a good job with it and would be a fairly inexpensive option.

[m3vuv]

have you tried parafin,ie kerrosine,or even diesel if you can stand the smell.

[Rat_Patrol]

These are removed connectors, so there are no PCB components to worry about.

I'll try to soak in some mineral spirits today, see what happens.

I have not tried kerosene, but I'll investigate if mineral spirits does not work.

I'll have to order some simple green or something to try.

[KaneTW]

Silicone oils are pretty annoying. Set your ultrasonic to the hottest it'll go and clean with 3% Alconox, then clean with similarly hot water and then with room temperature water.

[jogri]

If it is in fact a silicon grease ethyl acetate will be a rather good solvent. I use it to degrease my glas labware, works great even at room temperature. Hexane (kerosene/lighter fuel) also works, but it is not that good. My SOP is to remove as much grease as possible with ethanol/hexane before applying the acetate (the acetate is not that good at removig large quantities, but great for traces).

Another method to dissolve it would be a KOH washing as that stuff will get rid of almost anything (it generally doesn't attack plastic, but you should definitely check if it dissolves your connectors before using it). If you want to try it just take a big plastic box, make a concentrated KOH/NaOH solution and let your parts soak for a few days.

[duak]

If you can't get or if none of the above solvents work, you might try a silicone wax remover that autobody shops use before painting.  I have a spray can of Kleen-flo Tumbler Silicone wax remover that I found in the half price bin at the local auto parts shop.  This stuff took old silicone thermal paste off like nothing I've ever seen.

[jogri]

If you can't get or if none of the above solvents work, you might try a silicone wax remover that autobody shops use before painting.  I have a spray can of Kleen-flo Tumbler Silicone wax remover that I found in the half price bin at the local auto parts shop.  This stuff took old silicone thermal paste off like nothing I've ever seen.

Good idea, the SDS of such a wax remover mentions iPA and amines, so it could be worth trying aniline if nothing else works. That stuff has a boiling point of 180°C, so it should be safe-ish to use it in ultrasonic cleaner.