[SI-LIST] Re: thermal via in BGA's
- From: "John LeVieux" <john.levieux@xxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Mon, 20 Dec 2004 10:45:56 -0800
Chandra,
The via-in-pad and conductive via fill technologies are possible. For =
more information, I refer you to the following website: =
www.datacircuits.com/docs/Conductive%20Via%20Fill.pdf. I recommend you =
discuss the availability of this technology with your PC board =
suppliers.
I am not clear about what your thermal efficiency question is, but I =
offer you the information I have gathered on the subject. According to =
data available at: http://www.wj.com/pdf/techpubs/new%20mounting.pdf, =
the thermal resistance from top to bottom of one 10 mil via filled with =
solder in a PCB that is .062" thick is 99=B0C/W. If the solder is =
excluded, the thermal impedance rises to 117=B0C/W. I will assume you =
can use 30 thermal vias under your BGA device. If you use thermal vias =
filled with solder, the junction temperature of your BGA will rise an =
additional 6.6=B0C due to the thermal vias alone. If the thermal vias =
are not filled with solder, the junction temperature rise due the =
thermal vias will be 7.8=B0C. So filling the vias will make a 1.2=B0C =
difference in your application.
John LeVieux
--------------------------------------------------------------
From: "chandra mohan thimmarayan" <chandramohan@xxxxxxxxxxxxxxxxxx>
Subject: [SI-LIST] thermal via in BGA's
Date: Fri, 17 Dec 2004 17:19:42 +0530
hi,
i'm using a BGA324(1553 ACE) in my design and its power rating is 2W =
and
for thermal consideration the chip mfr. has suggested to put a filled =
via
over GND ball(pad) for better thermal conductivity
and whether this method(placing via over ball pad) is possible in
fabrication and soldering and if it is possible whether i could get the
better thermal efficiency and if it so what percentage of plating will =
be
made for 10mil drill and 24 mil pad.
expecting early reply from all...
thanks and regards,
chandra mohan.T
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