PCB Libraries Forum : IPC-7351 Collapsing and Non-Collapsing BGA Balls https://www.PCBLibraries.com/forum/ Sun, 12 Apr 2026 11:02:12 +0000 Fri, 28 Mar 2025 13:38:11 +0000 http://blogs.law.harvard.edu/tech/rss Web Wiz Forums 12.07 360 https://www.PCBLibraries.com/forum/RSS_post_feed.asp?TID=3370 <![CDATA[PCB Libraries Forum]]> https://www.PCBLibraries.com/forum/forum_images/PCBLForumLogo.gif https://www.PCBLibraries.com/forum/ <![CDATA[IPC-7351 Collapsing and Non-Collapsing BGA Balls : If the Ball diameter is on the...]]> https://www.PCBLibraries.com/forum/ipc7351-collapsing-and-noncollapsing-bga-balls_topic3370_post13843.html#13843 Author: Tom H
Subject: 3370
Posted: 28 Mar 2025 at 1:38pm

If the Ball diameter is on the dividing row between percentages the new ball size will take the lower values. 

Here is a sample BGA terminal option table where the 0.24 mm Ball Diameter was added.


 
]]> Fri, 28 Mar 2025 13:38:11 +0000 https://www.PCBLibraries.com/forum/ipc7351-collapsing-and-noncollapsing-bga-balls_topic3370_post13843.html#13843 <![CDATA[IPC-7351 Collapsing and Non-Collapsing BGA Balls : For the collapsing BGA ball with...]]> https://www.PCBLibraries.com/forum/ipc7351-collapsing-and-noncollapsing-bga-balls_topic3370_post13842.html#13842 Author: mking
Subject: 3370
Posted: 28 Mar 2025 at 11:39am

For the collapsing BGA ball with a diameter between the values listed what is appropriate reduction?

My example is a 0.242 mm diameter. Is the recommended reduction 15%, 20%, or 19.2% (linear interpolation)?
]]> Fri, 28 Mar 2025 11:39:16 +0000 https://www.PCBLibraries.com/forum/ipc7351-collapsing-and-noncollapsing-bga-balls_topic3370_post13842.html#13842 <![CDATA[IPC-7351 Collapsing and Non-Collapsing BGA Balls : The Solder Mask Defined BGA pad...]]> https://www.PCBLibraries.com/forum/ipc7351-collapsing-and-noncollapsing-bga-balls_topic3370_post13485.html#13485 Author: Tom H
Subject: 3370
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. 



]]> Sun, 07 Apr 2024 13:39:29 +0000 https://www.PCBLibraries.com/forum/ipc7351-collapsing-and-noncollapsing-bga-balls_topic3370_post13485.html#13485 <![CDATA[IPC-7351 Collapsing and Non-Collapsing BGA Balls : IPC has a rule for BGA pad size...]]> https://www.PCBLibraries.com/forum/ipc7351-collapsing-and-noncollapsing-bga-balls_topic3370_post13484.html#13484 Author: Tom H
Subject: 3370
Posted: 07 Apr 2024 at 1:31pm

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.



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