[SI-LIST] : ?Dumb Question Regarding Multilayer Boards

Mark Randol (ryvw50@email.sps.mot.com)
Thu, 26 Mar 1998 15:55:59 -0700

Hello to the list,

Here's the setup. I'm thinking that it's time to go to more than
2 layers for some of our internal boards, and some that we demo
to customers. The objection I hear from management and co-workers
is regarding the expense.

I've done a little digging on my own, and it seems that going
from a 2 to 4 layer board, in "production" quantities, raises
the cost by about 2X - assuming the same size board. I SWAG
that a size reduction of about 75% will occur due to more direct
trace routing, and elimination of some of the bypass caps,
etc <?>. So that's a board cost increase of about 1.5X (not
counting component cost reductions that might be possible).

Am I about right here, or am I dreaming? Performance, as long
as it's "reasonable", isn't an issue. We can get that on
a 2 layer board (mostly). EMI/EMC isn't an issue either (since
we don't do compliance testing - yet?)

(component reductions I'm assuming are application specific,
and likely too involved for discussion here)

Thanks,

-- 
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Mark Randol, RF Measurements Engineer   | Motorola SPS, Inc.
(602)413-8052 Voice                     | M/S EL379
(602)413-4150 FAX                       | 2100 E. Elliot Road
ryvw50@email.sps.mot.com                | Tempe, AZ 85284
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