QFP pattern help

Making your own components and patterns, organizing and using libraries.
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rick.curl
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Posts: 162
Joined: 14 Jun 2010, 16:46

QFP pattern help

#1 Post by rick.curl » 29 Jun 2020, 15:58

I am defining a new component: dSPIC33EP256MU806 in a 64-pin TQFP package. Even after reading the "Pattern Names Help" PDF, I am still unsure which pattern to choose. The patterns in the QFP pitch 0.50mm library have many more characters in their name than what is covered in the document. Just looking at 64 pin variants only, there are over 100 choices available. Looking at similar pre-defined chips, it appears that the correct answer is QFP64P50_1200X1200X120L60X22N_AD3.

The spec sheet for the chip is here: http://ww1.microchip.com/downloads/en/D ... 70616g.pdf and the TQFP footprint is on page 583.

If I had a physical chip here, I'd print the footprint and see how it fits, but the chips won't arrive until next week.

Can anyone help demystify this for me?

Thank you!

-Rick

Tomg
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Posts: 1541
Joined: 20 Jun 2015, 14:39

Re: QFP pattern help

#2 Post by Tomg » 29 Jun 2020, 22:00

Well, trying out the Pattern Editor's IPC-7351 pattern generator and plugging in the MicroChip-recommended dimensions (including pad size) produces the name "QFP64P50_1200X1200X120L60X22"...
MC_QFP.png
If you search the standard DipTrace pattern libraries for similar names, the Nominal density "QFP64P50_1200X1200X120L60X22N_AD1" seems to come closest while maintaining a pad width of 0.3mm...
DT_QFP.png
Comparing the two patterns reveals a difference in pad length (MicroChip = 1.5mm, DipTrace = 1.3mm), which may or may not make a difference in your application.
c1.png
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Tom

rick.curl
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Posts: 162
Joined: 14 Jun 2010, 16:46

Re: QFP pattern help

#3 Post by rick.curl » 30 Jun 2020, 08:21

WOW!
Thanks, Tom. Your detailed response is very helpful. It answers a ton of questions.

I really appreciate the time you took to respond.

-Rick

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