Breaking out traces from a 113 Microstar BGA package.

DAN ROSS1

Hello, We're working on a project that uses the MSP4305659 processor with the Microstar 113 BGA package. Looking at breaking out the inner ball signals, means 3 mil spacing and 2 mil traces - which is to small. Does T.I. recommend any other method (Blind Via's, etc) to break out these signals.

Thanks

Dan Ross

AST

over 11 years ago

0 Brian Boorman over 11 years ago

Guru 25210 points

Typically you use micro-via-in-pad to bring inner ball fields to an inner layer and route out of there.

This document is a little old, but has some additional recommendations as well: http://www.ti.com/general/docs/lit/getliterature.tsp?baseLiteratureNumber=ssyz015

Here is an example (not all pins used) of 5438A in same package. Red=Top, Teal=Layer2, Tan=Layer3.

0 Jens-Michael Gross over 11 years ago

Guru 227245 points

When using BGA packages, you usually use micro vias. BGA is indeed much too tight to route the inner signals through the outer ball rows. Since the 113 BGA package has no ‘middle rows’, you should be able to succeed with normal vias and without in-pad vias (which most layout programs consider an error)

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Breaking out traces from a 113 Microstar BGA package.