What are the causes of the internal crack on only on layer 5? Most of the
cracks found were on via holes extending into the laminate (no
delamination!). Prepreg used at layer 5 is 3 sheets of 1080 of FR406 (these
3 will give a total of .008" thickness to overall thickness of .093").

Loaded boards failed at ICT that prompted us to do some investigation. What
should I do as an OEM customer on my own as my fab house and assembly house
won't take responsibility easily. Following information may help you
understand my board structure.

# of layers: 12
SIG/GND/SIG/GND/SIG/3.3V/VCC/SIG/GND/SIG/GND/SIG

1oz copper used on all layers except first and last which plated to 1oz final.

re,
ken patel
______________________________________________________
Ken Patel                       Phone:  (408) 490-6804
1708 McCarthy Blvd.             Fax:    (408) 490-6859
Milpitas, CA 95035

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