Jim:

My suspicion is that it may well be impossible for you to get PTFE to pass water break, certainly no cleaning/treatment after etch is going to help.
The water break test is all about wetting, and PTFE is not going to wet by water.  
That said, what is supposed to be happening with the sodium based etch, is it is supposed to remove the Fluorine and thus convert the surface into something else other than PTFE, presumeably more wettable.

I suggest that you take a test panel, and over-etch excessively.  It could easily be that you are not etching enough.

Are you agitating during etching?   I suspect this would help.

Rudy Sedlak
RD Chemical Company

"Marsico, James" <[log in to unmask]> wrote: Hello Technet:

 

We have an application where we have to etch a PTFE PWB in preparation
for bonding.   The etch is a commercially available sodium-containing
solution.  We're also expected to meet a water-break test prior to
bonding.  We're having trouble meeting the water-break test and was
wondering if the two (etched PWB and water-break) are compatible.  If
so, what cleaning/rinsing could be performed after the etching to ensure
a water-break free surface?

 

Thanks in advance,

 

Jim Marsico

EDO Corporation

Amityville:  631-630-5079

Bohemia:  631-218-7057

[log in to unmask]

 


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