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Reply To: | TechNet E-Mail Forum. |
Date: | Mon, 3 Mar 2003 14:16:20 +0200 |
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Hi, folks,
I have two questions of a layman, regarding PCB 0f 22 layers, 3.4 mm thick
(controlled impedances in all the signal layers, what else?):
1. Until recently I succeeded to protect the fortress and avoid using
BGA with pitch of less than 1 mm. Lately I missed a battle, and a 0.8 mm BGA
was implemented. Does it necessarily mean that I have to leave my old and
favor HASL finish and migrate to the immersion field?
2. Will FR4 (of course - Tg=180 deg C) withstand the thermal stresses
of this stack up, or should I migrate to more stable material (lower Cte-z
axis)?
Regards
Ofer Cohen
Quality Assurance Manager
Seabridge Ltd.
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