[SI-LIST] Re: 4 Layer card with blind & buried via's
- From: sunil bharadwaz <sunil_bharadwaz@xxxxxxxxx>
- To: "b.hargin@xxxxxxxxxx" <b.hargin@xxxxxxxxxx>, "Wolfgang.Maichen@xxxxxxxxxxxx" <Wolfgang.Maichen@xxxxxxxxxxxx>, "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>
- Date: Mon, 3 Dec 2012 22:33:05 -0800 (PST)
Sorry , correction .. I do not think that the conventional technology would
work ...
Regards
________________________________
From: sunil bharadwaz <sunil_bharadwaz@xxxxxxxxx>
To: "b.hargin@xxxxxxxxxx" <b.hargin@xxxxxxxxxx>;
"Wolfgang.Maichen@xxxxxxxxxxxx" <Wolfgang.Maichen@xxxxxxxxxxxx>;
"si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>
Sent: Tuesday, December 4, 2012 11:57 AM
Subject: Re: [SI-LIST] Re: 4 Layer card with blind & buried via's
Thanks to all who have replied to this mail .I cannot get away from using this
particular chip ( 0.4 mm pitch & 0.25 mm bump dia ) . In fact this is a WLCSP
& not a BGA . I guess the package name does not make any difference to
the escape out .
We cannot even use a 6 mil / 10 mil Via for the escape out ( because there is
not enough space with this aggressive ball pitch ) . Definitely struck with
Via on Pad & the HDI technology .
Even with the increase in no of Layers , we may ( rather will ) not be ableÂ
to avoid the blink & buried Vias ( not Via's - thanks for the correction ).
I do not think , conventional technology would not work ..
Regards
Sunil.B
________________________________
From: Bill Hargin (ICD) <b.hargin@xxxxxxxxxx>
To: Wolfgang.Maichen@xxxxxxxxxxxx; sunil_bharadwaz@xxxxxxxxx;
si-list@xxxxxxxxxxxxx
Sent: Monday, December 3, 2012 11:01 PM
Subject: [SI-LIST] Re: 4 Layer card with blind & buried via's
Hi Sunil:
<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 ?>
You can use a blind via from L1-L3 ... Wolfgang is correct, though I'll add
this:Â buried vias would perhaps cost enough more to fabricate than going
with a 6-Layer design -- not to mention other issues that may come up if you
try to sqeeze too much into the two resulting signal layers.
We have a tool that helps with stackup tradeoffs ... There's an eval version
on http://www.icd.com.au/FX.html .
Bill Hargin
In-Circuit Design, USA
Software & SI Simulation for High-Speed PCB Design
(425) 301-4425 ⢠b.hargin@xxxxxxxxxx ⢠Skype: bill.hargin
Online:Â www.icd.com.au
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Wolfgang.Maichen@xxxxxxxxxxxx
Sent: Monday, December 03, 2012 6:37 AM
To: sunil_bharadwaz@xxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: 4 Layer card with blind & buried via's
My guess is that adding blind vias to the design will cost way more than
going from 4 to 6 layers...
Regards, Wolfgang
-----Original
Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of sunil bharadwaz
Sent: Monday, December 03, 2012 3:22 PM
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 -2Â & 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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