[SI-LIST] Re: Decoupling capacitors for BGA
- From: craig mathew <craig.mathew@xxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Fri, 12 May 2006 22:07:30 -0700 (PDT)
Hi Avanindra,
I have a similar question. We are using 0201 decaps at the bottom of our BGA
device for decoupling. We are using 9 mil drill size for via.
Unfortunately we are up against two odds, our PCB is close to 125mil thick
and we have small via drill, This increases the via inductance. Is there a way
I can calculate to what frequency will my decap work effectively?
I may be really dumb here but more I think more it seems logical to place
decaps around the periphery of the device than at the bottom.
Thanks
Craig M
----text deleted-----
Subbu,
if your board is not thick, you may want to consider using 0201 caps
directly underneeth the BGA aray, especially if GND and VDD are located
directly diagonally across from each other.
If you connect caps via individual traces to the pins, you will get alot of
resistivity.
Which can be a plus if your goal is to dampen high-frequency noise. However,
if you make traces very thin and long, you may slow your response time too.
So calculate your resisitivity per square to figure out what is the optimal
cap connection for you.
Dagmara
---------------------------------
Love cheap thrills? Enjoy PC-to-Phone calls to 30+ countries for just 2¢/min
with Yahoo! Messenger with Voice.
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
