Does this relate to the new classifications of FR-4?  Have heard there may be a pretty frisky IPC 4101 meeting coming in Rosemont. 
 
Denny Fritz
 
 
-----Original Message-----
From: Ron Feyereisen <[log in to unmask]>
To: TechNet <[log in to unmask]>
Sent: Thu, Sep 18, 2014 5:01 pm
Subject: [TN] Allowable % of Filler in FR-4


Hi Technetters!

Does anyone know if there's an allowable percentage maximum of silica filler 
used in FR-4 PCB material?

"Fillers such as silica and aluminum hydroxide are added to the epoxy resin 
primarily to lower the coefficient of thermal expansion (CTE) of
the laminate while enhancing the flame retardant ability and reducing material 
cost."

From "Controlling Moisture in Printed Circuit Boards" published in the IPC 
Printed Circuit Expo, APEX & Designer Summit Proceedings

Thanks,

Ron



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