John,

Sounds like your customer is just getting into ball grid array design.  The
feature set he choose is way too large for a 560 BGA design.  Suggest your
customer get in touch with the BGA vendor for their design requirements.
They will be more than happy to help with industry standard design data.

Jim Kittel

> -----Original Message-----
> From: John Parsons [SMTP:[log in to unmask]]
> Sent: Friday, December 17, 1999 12:06 PM
> To:   [log in to unmask]
> Subject:      [TN] Need Design Advice for BGA (?) Socket
>
> Seasons Greetings!
>
> We have just received a design from a customer which utilizes a
> 560 pin BGA(?) socket.  Here are the details;
>
> -6 Layer board, 4 routing layers 2 plane layers
> -Socket is 5 rows deep
> -Current configuration - 23mil hole on 30mil pad on 50mil grid
> -Routing out with 8mil traces on primary, secondary and two inner
> layers
>
> We have told him that his hole to pad ratio is too small for us to
> manufacture.  Currently our minimum spec is 6mil annular ring (pad
> dia - finished hole size/2) for outer layers and 7.5mil for inners
> (although we will do 6mil on inners if we have to).
>
> He is telling us that he cannot design within these constraints.
>
> What are others doing for this design?  Are you routing out on
> outer layers?  We cannot seem to put our hands on another
> sample design from our files (although I know they are some in
> there somewhere).
>
> Regards
> John Parsons
> Circuit Graphics Ltd.
>
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