[SI-LIST] Re: 4 Layer card with blind & buried via's
- From: "Prasad Mangipudi" <Prasad.Mangipudi@xxxxxxxx>
- To: <sunil_bharadwaz@xxxxxxxxx>, "SI LIST" <si-list@xxxxxxxxxxxxx>
- Date: Mon, 3 Dec 2012 12:55:44 -0800
Sunil,
Low cost manufacturing and Micro BGA do not go together. With 0.4mm pitch, and
0.25mm ball dia, you do not have sufficient place for conventional vias. Cost
of manufacturing will increase due to blind/buried vias and via-in-pad
manufacturing and smaller trace geometries. If cost is main issue, choose a
package that suits conventional manufacturing and not HDI.
Prasad
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of sunil bharadwaz
Sent: Monday, December 03, 2012 6:22 AM
To: SI LIST
Subject: [SI-LIST] 4 Layer card with blind & buried via's
Hi All ,
I'am trying to do a board for a micro BGA with 0.4 mm pitch & 0.25 mm ball dia.
To cut down the cost , i want to use a 4-layer card instead of a 6-Layer card.
Layer -1 to Layer -2 & Layer -4 to Layer-3 would be blind Via's .
Can i also use a blind via directly from Layer -1 to Layer-3 or do i have to use
a blind Via from Layer-1 to Layer -2 & then have a buried Via from
Layer-2 to Layer-3 ?
Layer 1 & 4 - Signal.
Layer-2 - complete gnd plane.
Layer -3 Vcc & gnd plane.
I'am looking forward to hear the rules followed in designing such boards.
Thanks for all the help in advance !!
Regards
Sunil.B
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