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Wrong Pad Stack Name?

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dlveazie View Drop Down
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    Posted: 01 Dec 2017 at 8:34am
When I use inch dimensions in pad stack calculator, the pad stack name looks like it's getting truncated instead of rounded. 

Creating pad stack for 0.025" x 0.025" lead says hole size should be 0.041" with 0.061" pad but pad stack name is c61h40.



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Jeff.M View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jeff.M Quote  Post ReplyReply Direct Link To This Post Posted: 01 Dec 2017 at 9:13pm
Pad stack name sizes (and certain footprint sizes) are created in what we call 'centrons'.
Without going into a whole lot of detail, a conversion factor is added to a dimension and decimal places are dropped.
The hole size in this case is actually 0.409.
After conversion and dropping the decimal place it equals 40 not 41 as you would expect if it were simply rounded thus h40.
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