Hello, Eltek

Use an anti-tarnish in the electroless plating line after the plating 
tank but before you take the boards off the machine and stack 'em up.  
You may find a propritary one that work (quick, more $), or develop a 
simple one yourself.  (cirtic acid, or, if my memory is good, I think 
MEA - Mono Ethanol Amine is another anti tarnish.)

If you do not provide some oxide protection, the oxide will progress 
deep into the porous e'less copper where it will not be removed by your 
pre-laminination cleaner, causing possible photoresist/oxide lock-in 
issues.

Finally, an out of control too-thick electroless process is one root 
cause of post seperation, or innerconnect defects.  Don't let this one 
sneak up on you!  I tried to keep the electroless to 15-30 millionths of 
an inch going into the copper plater (by weight gain) to stay well away 
from this problem with the Chemistry I used in a past life.


Tabasco goes well with leftover Turkey
George Franck

PS.  Due the international nature of this forum, an explanation: Turkey 
is the traditional meal for the upcoming US Thanksgiving Holiday.  
Tabasco is a Hot Pepper sauce of Cajun origin.



On Nov 26,  8:10am, Eltek Ltd. - Process Engineering wrote:
> Subject: Thick Electroless
> Hello Technet !
> We intend to switch our PTH process from thin copper electroless plus
> electrolytic strike to thick ( hot ) electroless , 2 microns thick . 
The
> line will be loaded with baskets , so we do expect the PCBs will be
> oxidized.We are considering some kind of chemical treatment prior to 
dry
> film lamination instead of pumice scrub.Wjhat kind of treatment is 
recommended ?


-- 


George Franck Jr
Raytheon E-Systems
Product Assurance Engineer
Falls Church Va

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