Re: [SI-LIST] : BGA Ni-Au platting pattern.

Gregory P. Fitzgerald (gpf@cadence.com)
Wed, 07 Oct 1998 08:08:29 -0400

I assume you re talking about the plating bar (stub) that goes out to the
edge of the package. Most tools that I know of do not consider this in
their electrical extraction however Advanced Packaging Ensemble from
Cadence does.
When the solver/extractor in SPECCTRAQuest sees the 'T-point' created, it
builds the plating bar stub as a transmission line that is open ended.

Based on the package correlation (measurement) work I did when supporting
the Alpha processsor and its core logic ASICs at Digital, the effect of the
stub (the additional capacitive loading, the reflection caused by the open
ended T-line,etc.) seemed to be negligble above ~1 nS edge rates, but
noticeable at 0.75 nS and below.

With a good extractor that 'does the right thing' you can easily verify
when you need to consider: a) the effects of the stub and take them into
account and/or b)the effect of 'pin-swapping' a short trace/long stub net
for a long trace/no stub trace.

/Greg

At 03:49 PM 10/7/98 +0900, komerix wrote:
>Hello All,
>
>I am simulating BGA platting patterns.
>
>In my thought, there aren't any tools that could condsider plating patterns.
>I also modeled this patterns with one material, copper.
>But, I can't affirm that this would have litttle error.
>Could anyone tell me how much deviations exist between measurement and
>simulation result?
>I will appreciate any information about this.
>
>Sunhue HUH
>
>## Komerix Engineering. ##
><huh>komerix@soback.kornet.nm.kr
>
>
>
>**** To unsubscribe from si-list: send e-mail to
majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE
si-list, for more help, put HELP. si-list archives are accessible at
http://www.qsl.net/wb6tpu/si-list ****
>
>
>
Greg Fitzgerald
Cadence Design Systems
Performance Engineering Business Unit
270 Chelmsford, MA 01824
Phone: 978-446-6638
FAX: 978-446-6798
e-mail:gpf@cadence.com

**** To unsubscribe from si-list: send e-mail to majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE si-list, for more help, put HELP. si-list archives are accessible at http://www.qsl.net/wb6tpu/si-list ****