IPC-7251

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   Hi all:

I cannot find IPC-7251 in IPC website, it haven't released?
What is the standard for through hole land calculation in Library Expert?

Thanks in advance.

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drj-bbe Members Profile Send Private Message Find Members Posts Add to Buddy List Advanced User Joined: 08 Jul 2015 Status: Offline Points: 71	Post Options Post Reply Quote drj-bbe Report Post Thanks(0) Quote Reply Topic: IPC-7251 Posted: 25 Nov 2015 at 2:33am
	Hi all: I cannot find IPC-7251 in IPC website, it haven't released? What is the standard for through hole land calculation in Library Expert? Thanks in advance.



Tom H Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5718	Post Options Post Reply Quote Tom H Report Post Thanks(0) Quote Reply Posted: 25 Nov 2015 at 5:48am
	The IPC Land Pattern committee decided a year ago to merge IPC-7251 for through-hole into the new IPC-7351C. You can download several documents here - http://www.pcblibraries.com/downloads What's New in IPC-7351C Surface Mount Component Families Through-hole Component Families
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drj-bbe Members Profile Send Private Message Find Members Posts Add to Buddy List Advanced User Joined: 08 Jul 2015 Status: Offline Points: 71	Post Options Post Reply Quote drj-bbe Report Post Thanks(0) Quote Reply Posted: 25 Nov 2015 at 7:45pm
	Thank you very much. I have other questions below: The calculation formula below for pad diameter is different with IPC-2221B 9.1.1, how to set "pad to hole ratio" and "minimum annular ring"? http://www.pcblibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785.html The calculation of pad diameter in IPC-7351C will not consider "Standard fabrication allowance" which in IPC-2221B Table 9.1, right?

Tom H Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5718	Post Options Post Reply Quote Tom H Report Post Thanks(0) Quote Reply Posted: 25 Nov 2015 at 8:55pm
	Set all the Through-hole user preferences - Preferences > Terminals > Through-hole The current default settings are from IPC-2221 but will also be in IPC-7351C.
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drj-bbe Members Profile Send Private Message Find Members Posts Add to Buddy List Advanced User Joined: 08 Jul 2015 Status: Offline Points: 71	Post Options Post Reply Quote drj-bbe Report Post Thanks(0) Quote Reply Posted: 26 Nov 2015 at 12:59am
	Thanks, but I still confused on below two calculation method for a pad: IPC-2221B calculation formula is: Land size, minimum = Hole size + 2Min. annular ring(Min 0.05mm) + fabrication allowance IPC-7351C calculation formula will be: Pad diameter = Hole size + 2Min. annular ring(Min 0.2mm), or = Hole size * pad-to-hole-ratio, whichever is larger. But calculated result will be different between above two calculation method, IPC-7351C defined a proportional annular ring, IPC-2221B defined same size annular ring even though hole size go up, right? This is for minimum pad design, the annular ring seems smaller than normal, is there suggestion for normal pad size?

Tom H Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5718	Post Options Post Reply Quote Tom H Report Post Thanks(0) Quote Reply Posted: 26 Nov 2015 at 10:44am
	Library Expert only uses "Hole Over Lead" from IPC. Everything else uses the PTH Reference Calculator located here - http://www.pcblibraries.com/forum/ipc7351-smd-pth-reference-calculators_topic785.html
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