Hi all,

We recently ran across a whitish spotty/hazy laminate condition first spotted 
after a couple of boards had gone thru assembly (see attached PWB.jpg 
picture showing condition on laminate between connector fingers on 
assembly).  The condition was brought into question and after some 
investigation, we learned that such condition is a pre-existing one at the bare 
laminate level that normally occurs with Arlon's 33N polyimide laminates due to 
a micro-disperse second phase of the flame retardant brominated sytem.

And apparently, this condition is seen to varying degrees within the 33N (see 
attached pictures: 113_1335a.jpg - more so, 113_1352a.jpg - less so).  Also 
attached is Arlon's letter that explains this laminate appearance, concluding 
that it's not a laminate defect.

How have other end-users of this 33N laminates dealt with this laminate 
appearance at the assembly level?  Has it caused any grief and how had the 
assemblies been dispositioned?

Of course this condition, when it exists, can only be seen under magnification, 
but even then, the whitish spotty/hazy appearance can be confused with 
other possible laminate imperfections/defects when seen by the inexperienced, 
like we were.  I'm not even sure if we're able to automatically say this is the 
condition we have when similar appearances are seen on future finished 
assemblies.

Any feedback you have is greatly appreciated.

Thank you,

Dung Q. Tiet
Lockheed Martin Space Systems Co.
Sunnyvale, CA
Tel: 408-756-2365
Email: [log in to unmask]