[SI-LIST] Re: Decoupling capacitors for BGA
- From: Balaji S <Balaji.S@xxxxxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Sat, 13 May 2006 13:52:11 +0530
Hi All,
Adding to Subramanian's query, if the caps are placed around the BGA, then
can we use capacitor networks for decoupling to save real estate??
Regards
Balaji S
"Dagmara Avanindra" <dagmara.avanindra@xxxxxxxxx>
Sent by: si-list-bounce@xxxxxxxxxxxxx
05/13/2006 09:13 AM
Please respond to
dagmara.avanindra@xxxxxxxxx
To
subramanian1683@xxxxxxxxx
cc
si-list@xxxxxxxxxxxxx
Subject
[SI-LIST] Re: Decoupling capacitors for BGA
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
On 5/12/06, Subramanian R <subramanian1683@xxxxxxxxx> wrote:
>
> Hello All,
> We are using a 0.5mm Pitch 457-Pin BGA Processor. It is running at a
> maximum
> of 532MHz.
> It has 60 Power pins (Core & I/O)
>
> How do i place the Decoupling capacitors?
>
> Now we have placed all decaps (0402 pack) around the BGA (like an
island)
> and connected it to the VCC plane. Should i need to route it to the
> individual pins itself?
>
> The BGA does not have much space between the Balls. So not more than 4-5
> caps can be placed right over the BGA on the other side.
>
> The other thing i can go for is Inter-plane capacitance. But for that
> VCC-GND dielectric should be around 2-3mils, i understand. That doesn't
> look
> possible with our PCB thickness requirements. It is a 6-layer PCB
>
> Thanks for any suggestions.
>
> Regards
> Subbu
>
> ------------------------------------------------------------------
> 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
>
>
>
------------------------------------------------------------------
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
------------------------------------------------------------------
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:
