IPC-7351 Collapsing and Non-Collapsing BGA Balls
Printed From: PCB Libraries Forum
Category: Libraries
Forum Name: PCB Library Construction Guidelines
Forum Description:
URL: https://www.PCBLibraries.com/forum/forum_posts.asp?TID=3370
Printed Date: 12 Oct 2024 at 7:28pm
Topic: IPC-7351 Collapsing and Non-Collapsing BGA Balls
Posted By: Tom H
Subject: IPC-7351 Collapsing and Non-Collapsing BGA Balls
Date Posted: 07 Apr 2024 at 1:31pm
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IPC has a rule for BGA pad size tolerances. They take a Nominal Ball and reduce or increase the pad size by a percentage, then add a pad size tolerance (variation). IPC-7351 recommends using the Maximum Material Condition of the Variation. All BGA balls collapse. Non-collapsing BGA balls are created by the PCB librarian by solder mask defined pads or making the pad size larger than the Ball. Collapsing Ball.  Non-Collapsing Ball defined by Solder Mask.  IPC-7351 BGA tables for pad size reduction for collapsing balls and pad size increase for non-collapsing balls. The pad size increase is normally used for fine pitch BGA's that require via-in-pad technology for fanout. There are 3 Density Levels A, B and C that indicate the percentage amount for pad size calculation.  ------------- Stay connected - follow us! https://twitter.com/PCBLibraries" rel="nofollow - X - http://www.linkedin.com/company/pcb-libraries-inc-/" rel="nofollow - LinkedIn |
Replies:
Posted By: Tom H
Date Posted: 07 Apr 2024 at 1:39pm
The Solder Mask Defined BGA pad helps secure the pad to the prepreg. This helps during drop tests.  ------------- Stay connected - follow us! https://twitter.com/PCBLibraries" rel="nofollow - X - http://www.linkedin.com/company/pcb-libraries-inc-/" rel="nofollow - LinkedIn |