----------
>JB
>
> 1. What is the advantage of vacuum pressing FR4?
>
>       There are several advantages with vacuum pressing.

                1.  Less Pressure is required due to the vacuum which aids in
                        removing air and solvents from the package.
                2.  The vacuum also aids in pregpreg flow reducing starvation at the
                        edges of the panels.
                3.  The result of using less pressure is an improved registration and
                        reduced distortion.
                4.   The impact of vacuum pressing is seen more destinct the higher
                        the layer count is in the panel.
                5.   If you are pressing blind and burried vias and/or using sequential
                        lamination the vacuum will be of great help.
                6.  One of the most important issues of vacuum pressing if you are
incharge
                        of the actual press cycle is the flexibility in heat rise adjustment
                        the vacuum allows  due mostly to #1 and #2 above.

John Haman Jr
Process / Product Engineer
American Board Companies, Inc

>
>

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