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Axial Components Pitch Calculation |
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Jeff.M 
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Joined: 16 May 2012 Location: San Diego Status: Offline Points: 482 |
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 Posted: 04 Nov 2020 at 11:13am |
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Ian's solution is correct: e = D + 2 ( L + R + b / 2 )
I write it : e = D + 2 ( L + R ) + b
Where: b : lead diameter D : part length, including weld beads if any L : lead length extension R : bend radius m : bend radius multiplier, according to the table in Ian's
message e : pitch |
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SWB01
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Joined: 24 Mar 2013 Status: Offline Points: 40 |
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Posted: 04 Nov 2020 at 12:15pm |
(Note that the calculation described by Ian S does not match this equation.) If this is the correct formula, then Library Expert is wrong, since this is not the math that the Axial Leadform Calculator is using. Example with b=0.5 and D=10:Pitch according to this formula = 13.1; Pitch according to the Axial Leadform Calculator = 14.0. Example with b=0.85 and D=7.6:Pitch according to this formula = 12.7; Pitch according to the Axial Leadform Calculator = 16.1.
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Ian S
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Joined: 21 Aug 2014 Status: Offline Points: 67 |
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Posted: 04 Nov 2020 at 12:57pm |
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SWB01 - I agree that PCB Libraries tool's axial component calculation for pin pitch is too large and does not match the calculation per IPC-2221A. I also agree that the SWB01 and Jeff's calculations are as expected.
PS. SWB01, in your original post you questioned why the tool came up with a figure of 2.4 mm, as opposed to 0.8 mm, for the 'lead length extension' for a lead diameter of 0.8 mm - I think you misunderstood my reply as I was demonstrating that the calculated 2.4 mm figure was referring to the distance from the component body to the centre of the drill hole and not the straight part of the lead (which the standard clearly defines as "Straight for 1 diameter, but not less than 0.8 mm"). Ian
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SWB01
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Posted: 04 Nov 2020 at 12:59pm |
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Ian S: Got it. Yes, I indeed misunderstood your reply.
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Jeff.M
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Joined: 16 May 2012 Location: San Diego Status: Offline Points: 482 |
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Posted: 05 Nov 2020 at 12:27pm |
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Looks like the formula changed from: Old formula had Lead Length calculated as 1.5 diameters for least (< 0.8mm); 2.5 diameters for nominal (0.8<1.2) and 3.5 for most (1.2<).
Current has just one diameter for each lead length (not less than 0.8) and produces the following sample results. e = D + 2 ( L + r ) + b
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Tom H
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Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5786 |
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Posted: 05 Nov 2020 at 12:30pm |
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Note: this feature update will be in the V2020.03 release this weekend.
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SWB01
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Posted: 05 Nov 2020 at 8:54pm |
Great! Thank you!
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Tom H
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Posted: 16 Nov 2020 at 9:21am |
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V2020.03 is officially released with this Axial Lead Bend formula fixed.
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Jeff.M wrote: