PCB Libraries Forum : Round vs Rectangular PTH Calculations https://www.PCBLibraries.com/forum/ Mon, 06 Apr 2026 20:33:15 +0000 Mon, 25 Feb 2013 09:35:38 +0000 http://blogs.law.harvard.edu/tech/rss Web Wiz Forums 12.07 360 https://www.PCBLibraries.com/forum/RSS_post_feed.asp?TID=672 <![CDATA[PCB Libraries Forum]]> https://www.PCBLibraries.com/forum/forum_images/PCBLForumLogo.gif https://www.PCBLibraries.com/forum/ <![CDATA[Round vs Rectangular PTH Calculations : It&#039;s because the elements...]]> https://www.PCBLibraries.com/forum/round-vs-rectangular-pth-calculations_topic672_post3113.html#3113 Author: Jeff.M
Subject: 672
Posted: 25 Feb 2013 at 9:35am

It's because the elements that contribute to the Proportional calculation (Fabrication Allowance, Hole- over-Lead, etc.) are based solely on the lead 'b' dimension not the hole size.  You'll notice that the Fabrication allowance for the two pads in your example are different.  This is to prevent a slotted hole from having a disproportional fabrication allowance from an un-slotted hole with the same drill size.]]> Mon, 25 Feb 2013 09:35:38 +0000 https://www.PCBLibraries.com/forum/round-vs-rectangular-pth-calculations_topic672_post3113.html#3113 <![CDATA[Round vs Rectangular PTH Calculations : To keep things simple. I used...]]> https://www.PCBLibraries.com/forum/round-vs-rectangular-pth-calculations_topic672_post2311.html#2311 Author: rickdehart
Subject: 672
Posted: 09 Nov 2012 at 1:47pm

To keep things simple.  I used the Radial (LED) and set b= 0.80, L=1.2 tolerance to +/-0, the round off to 0.01 and the placement to 0.01.
]]> Fri, 09 Nov 2012 13:47:51 +0000 https://www.PCBLibraries.com/forum/round-vs-rectangular-pth-calculations_topic672_post2311.html#2311 <![CDATA[Round vs Rectangular PTH Calculations : Since there is currently...]]> https://www.PCBLibraries.com/forum/round-vs-rectangular-pth-calculations_topic672_post2310.html#2310 Author: Jeff.M
Subject: 672
Posted: 09 Nov 2012 at 1:35pm

Since there is currently no component in FPX that allows both round and rectangular leads (just round and square) I checked this out using the Axial calculator for the round lead and a DIP for the rectangular lead with a proportional environment in both cases.
The results were as follows:
1.44mm round lead produces as 1.6mm hole and a 2.4mm pad;
0.8 X 1.2mm lead produces a 2.2mm hole (size based on the diagonal of the lead) and a 2.7mm pad.
These results are pretty much as expected but not the results you report.
Can you explain the method you used to arrive at the values you provided?
]]> Fri, 09 Nov 2012 13:35:52 +0000 https://www.PCBLibraries.com/forum/round-vs-rectangular-pth-calculations_topic672_post2310.html#2310 <![CDATA[Round vs Rectangular PTH Calculations : Can anyone tell me why there is...]]> https://www.PCBLibraries.com/forum/round-vs-rectangular-pth-calculations_topic672_post2309.html#2309 Author: rickdehart
Subject: 672
Posted: 09 Nov 2012 at 12:14pm

Can anyone tell me why there is a difference in the land size between a 1.44mm round and a 0.8x1.2mm rectanular pin?  I am using the proportional enviorment.  The Finished hole calculates out the same 1.64mm, but the land is 2.49mm for round and 2.14mm for rectanular.

I put this on the LP Wizard Forum, but I see Footprint Expert is using the same calculations.  ]]> Fri, 09 Nov 2012 12:14:12 +0000 https://www.PCBLibraries.com/forum/round-vs-rectangular-pth-calculations_topic672_post2309.html#2309