Barry-----
Originally, the natural coloration of the epoxy resin and glass was a 
greenish color ----
different shades for different laminators but essentially the green 
family with a translucent
quality.  When installed in some of the equipment in the earlier 
computers, the array of
cards looked different and in cases of problems, the customer ofter 
alluded to the normal
difference in coloration as a reflection of production/ process 
controls variations which
ultimately led to laminators introducing a small amount of compatible 
dye into the resin
system to yield a uniform color ----- still in the greenish family.

In some special instances,
this lead to the development of colored epoxy glass laminates ------ 
tan, black, blue and
white being the predominant colors.  The opacity hid a multitude of 
sins but was also
used for product identification---------- the original Ampex Blue, 
Formica's White FR-45,
the Magnavox Tan originally produced by CDF --- later Budd Company 
---- for the Signal
Corps and Indiana General Black used primarily to inhibit light 
transmission ---- how I
really don't know.

Enjoy the holiday
Bernie Kessler



At 11:39 AM 7/3/2008, Barry Gallegos wrote:
>Good day Tech netters.
>
>I have a Question. I had an engineer broch a question to me. I could not
>answer his question, So I bring this to you as well .
>
>
>
>Q. Why are PCB's predominantly Green in color?
>
>
>
>Barry.
>
>
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