BGA Pad Size Calculation
Printed From: PCB Libraries Forum
Category: PCB Footprint Expert
Forum Name: Questions & Answers
Forum Description: issues and technical support
URL: https://www.PCBLibraries.com/forum/forum_posts.asp?TID=594
Printed Date: 19 Nov 2024 at 6:36am
Topic: BGA Pad Size Calculation
Posted By: lalexman
Subject: BGA Pad Size Calculation
Date Posted: 03 Oct 2012 at 8:57am
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Hi, How is the size of the BGA pad calculated? |
Replies:
Posted By: Tom H
Date Posted: 03 Oct 2012 at 9:20am
Most BGA's are Collapsing Balls. In the "PCB Footprint Expert" in "Setup > User Preferences > Terminals > BGA Collapsing Ball" you will see Ball Sizes in the first column and the "Pad Size Reduction" in the second column. The Adj% = the Pad Size Reduction from the Ball Size.  Example: the first Ball Size in the table is 0.60 mm and the Pad Size Reduction calculation is 25%. So 25% of 0.60 mm = 0.45 mm nominal. However, IPC-7351 specifies a tolerance range of +/-0.05 mm so the tolerance range is
The IPC-7351 standard always uses the "Maximum" material condition, so the 0.60 mm Ball Size would require a 0.50 mm Pad Size. The "PCB Footprint Expert" automatically performs all these calculations for the user. |
Posted By: lalexman
Date Posted: 03 Oct 2012 at 9:26am
| Thanks Tom. |
Posted By: DaveCowl
Date Posted: 18 Oct 2012 at 1:44pm
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I was wondering about that. In fact I got to this page because I was trying to find out why the LP Wizard threw out .35 mm pads for my 0.8mm .4mm ball BGA where everyone else says Nominal would be 0.3mm. In any case I am excited to see this product listed and will give it a try for sure! Cheers!
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Posted By: DaveCowl
Date Posted: 18 Oct 2012 at 2:16pm
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Ok I have been playing with the software and I have a couple of questions: My BGA is 18x18 0.8mm pitch with 0.4mm balls 1) It seems to output 0.35mm pads for all of L, N and M - does that make sense? 2) Looking at the table above there is no entry for 0.4 - I tried to add one but to no avail - does it just use the same settings for all sizes 0.35 - 0.45? 3) Did you know that text based HKP files are no longer supported by Mentor Library software? Do you have any fixes for that? Thanks!
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Posted By: Tom H
Date Posted: 29 Dec 2012 at 12:33pm
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The BGA "Pad Size" calculation is 1-Tier, but the Silkscreen Line Width, Ref Des Height and Local Fiducial Size are 3-Tier environment per the upcoming IPC-7351C standard. |