What is the coating used on Neumann PCB's?

[RuudNL]

At the moment I am trying to repair a Neumann TLM103 microphone.
The (ceramic) PCB is covered with a layer of 'coating', that makes unsoldering of components very difficult.
I already tried to remove the coating with all kinds of solvents, but without success.
Any idea what kind of material they used for this?
The coating also makes it almost impossible to take measurements, because it seems very difficult to scrape it away in order to get a good contact with a certain component. Just curious...

 

[TillM]

I think it's just laquer.

 

[RuudNL]

In that case it must be something special!
It seems resistant against all kinds of solvents I have used, and it is very hard to scrape away...

 

[Khron]

It's "vintage" ;D They don't make'em like they used to...

 

[micaddict]

So glad I sold mine.  ;D

 

[MS Vienna]

I think it's just laquer.

In that case it must be something special!
It seems resistant against all kinds of solvents I have used, and it is very hard to scrape away...

There are many different types of laquer. For this task usually urethane isolation laquer is used to seal the PCB against moisture.

 

[gyraf]

codenamed "conformal coating"

https://en.wikipedia.org/wiki/Conformal_coating

Jakob E.

 

[Matador]

What is the coating used on Neumann PCB's?

Tears?

 

[chefducuisine]

Conformal coating is a huge spectrum of products.

From the properties you describe it is most likely 'Parylene'
https://scscoatings.com/what-is-parylene/parylene-properties/

Alternatively you can use 'humiseal' after the repair. Downside of Humiseal is that is not resistant to acid. Parylene is.
http://www.humiseal.com


Be warned: Parylene isn't cheap and difficult to get. It is also difficult to apply. Normally you need special machinery for this. There are only a hand full of companies in Germany capable of applying this coating in a correct way.

 

[RuudNL]

This makes sense! Thank you!