Cleanly removing solder and epoxy resin without damaging parts

[szzuk]

I glued some expensive parts (piezos) together with a steel laden epoxy resin, I've separated the parts ok but how do I get rid of the epoxy resin? I think I need some kind of chemical or 'wet' solution. If all else fails I will try sanding the epoxy off but I'd prefer to avoid that if you can think of a better solution.

I also need to remove excess solder very cleanly from the same parts. I have got most of it off but the rest is in a very thin layer. What would you suggest?

 

[cobra1]

what are the parts? depending on what they are will determine what method of removal you can use.

 

[szzuk]

The parts are pzt rings. So they are a delicate ceramic.

Regards,

Szzuk.

 

[Sceadwian]

Steel laden epoxy? Man did you dig yourself a grave, might as well try time travel...
Many epoxies can be dissolved via heated nitric acid vapor, that's usually relegated to high end companies that need to reverse engineer complex IC's. The expoxy type itself is more important than the part.

The cost for retrieval might very well be more than the cost of the component, how much are they worth?

 

[jpanhalt]

What chemical solvents do you have access to? Some paint removers for aircraft and other durable finishes have methylene chloride and other aggressive solvents in them that will denature the epoxy enough to get it off. If you have chloroform, soaking in that may help. Nitric acid is also a good reagent to try and should not affect a ceramic.

How hot can you get the parts? At about 150° to 175°C, the epoxy should start to soften and may be peeled off.

As stated previously, you need to balance the cost/risk of getting rid of the epoxy vs. just buying new parts.

John

 

[Sceadwian]

There are many different kinds of epoxies, true epoxies are not thermally sensitive, those with plastic components are.
Steel filled epoxy makes me think that perhaps there's not a large plastisizer element...

 

[jpanhalt]

... true epoxies are not thermally sensitive, those with plastic components are.

What do you mean by that? I was talking specifically about exceeding the Tg for the epoxy, at which point it becomes flexible and can be often be "peeled" from whatever it is applied to.

Obviously, we seem to differ in how to define a "true" epoxy. How do you define it? FR4 in my book is a true epoxy with a Tg of about 135°C in its common form (https://en.wikipedia.org/wiki/FR-4).

John

 

[szzuk]

Steel laden epoxy? Man did you dig yourself a grave, might as well try time travel...
Many epoxies can be dissolved via heated nitric acid vapor, that's usually relegated to high end companies that need to reverse engineer complex IC's. The expoxy type itself is more important than the part.

The cost for retrieval might very well be more than the cost of the component, how much are they worth?

They cost £400 ($600) each. I guess I will need to send them somewhere to be repaired? I was hoping there was something I could do here.

 

[szzuk]

What chemical solvents do you have access to? Some paint removers for aircraft and other durable finishes have methylene chloride and other aggressive solvents in them that will denature the epoxy enough to get it off. If you have chloroform, soaking in that may help. Nitric acid is also a good reagent to try and should not affect a ceramic.

How hot can you get the parts? At about 150° to 175°C, the epoxy should start to soften and may be peeled off.

As stated previously, you need to balance the cost/risk of getting rid of the epoxy vs. just buying new parts.

John

The pzt will depolarise if it gets too hot, but I'm not sure what temperature too hot is. I will find out. I'll also see if I can get hold of some of those solvents, I can practise with some broken or cheaper parts to see what works.

 

[Sceadwian]

I wouldn't play with anything, if you're sure it's worth the time spend the time on the phone, contact the maker of the epoxy. Don't try to contact customer service that'll lead you to a dead end, try contacting someone within the manufacturing plant and see if you can get a hold of a shift manager for production, if you're polite and explain things simply and clearly there's a good chance they'll put you through to someone that actually knows what they're talking about. Anyone that actually knows the details of how their product is made should be able to provide either the right substance to use, or at least be able to tell you what the basic makeup of their epoxy is so you can research for yourself something that will work. Ceramics and piezo materials are pretty chemical resistance so if you can just find the right chemical you should be all set. Keep in mind, pretty much anything that will disolve that kind of epoxy will be extremely dangerous and the waste materials should be disposed of properly.

 

[szzuk]

That's good advice. I'll get on the phone. Regards. Szzuk.