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Proportional Through-hole Padstacks

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Nick B View Drop Down
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    Posted: 14 Mar 2012 at 3:22am
Here is the latest Through-hole Padstacks file - Updated 8-9-12
 
 
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Chris View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Chris Quote  Post ReplyReply Direct Link To This Post Posted: 14 Mar 2012 at 4:29am
Thanks very much. Smile
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Nightwish Quote  Post ReplyReply Direct Link To This Post Posted: 14 Mar 2012 at 6:56am
Thanks a lot for sharing this with usSmile
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Nick B Quote  Post ReplyReply Direct Link To This Post Posted: 15 Mar 2012 at 3:38am
Updated on March 15, 2012 - see link in original post for latest version.
 
  1. Updated “Mil Unit” pad sizes to be rounded up to the nearest 2 mil increment. This ensures that all measurements are in 1 mil increments. The pad size radius is now in 1 mil increments.
  2. Totally overhauled the Fiducial pages to include the new 3-Tier Local Fiducial and added Global Fiducials and 3-Tier SMT Test Points.
  3. Removed Thermal Relief data from all Mounting Holes. There is no requirement for Thermal Relief’s on Mounting Holes.
  4. Updated the Via Tables to add Inner and Bottom pad sizes and removed the thermal relief requirements. Standalone vias do not require thermal reliefs.

 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote IanOnBass Quote  Post ReplyReply Direct Link To This Post Posted: 15 Mar 2012 at 2:08pm
Excellent resource. Thanks for sharing.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RLS2004 Quote  Post ReplyReply Direct Link To This Post Posted: 15 Mar 2012 at 2:37pm
Thanks for updating TH Padstacks.
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Thanks a ton!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Artwork Master ITALY Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar 2012 at 9:51am
Great work!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Nick B Quote  Post ReplyReply Direct Link To This Post Posted: 20 Mar 2012 at 2:40am

The link above was updated again:

Updated the Thermal Spoke Width calculations for Plated Through Hole padstacks

The new improved formula is: Spoke Width = 75% of Plane Anti-pad divided by 4

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 20 Mar 2012 at 11:15am
Here is the "Proportional Through-hole Padstack" Mathematical Model data:
 
The first column is the Maximum Component Lead Size and it is determined by -
 
 
The second column is the Finished Hole Size and it is determined by adding 8 mil (0.2 mm) to the Maximum Lead Size in the first column. This is the "Nominal" Lead to Hole calculation as seen in the chart from the IPC-2222 standard.
 
 
The next 5 columns are the Pad Sizes for all the layers and they are the same value across all the rows. The Pad Size starts out using the IPC-2221 nominal annular ring requirements of 10 mil (0.25 mm) or the Pad is 20 mil (0.5 mm) larger than the hole size.
 
Then, as the hole size gradually gets larger, the pad annular ring grows "Proportionally" larger in increments of 1 mil (0.025 mm). The primary theory is that the hole size gets larger to accommodate a larger component lead. Larger component leads are created to carry additional current or because the component size is large and needs stronger support (more solder).
 
The Plane Anti-Pad Clearance is derived from the Hole Size and it remains relatively constant because it has nothing to do with supporting large components. It's simply a clearance from the hole to improve the PCB manufacturing yields. The minimum annular ring of the Plane Anti-Pad is 15 mil (0.35 mm) for holes intended for component leads. As the hole size grows in size, the Plane Anti-Pad stays somewhat constant but it does slightly grow as the hole size grows to keep a safe distance from higher voltage currents that larger holes can carry.
 
The Thermal Relief is a simple formula -
The ID is 20 mil (0.5 mm) larger than the Hole Size
The OD is the same value as the Anti-pad
The Spoke Width = Anti-pad X 75% divided by 4 spokes, the calculated spoke width X 4 = Hole Size or slightly larger than the hole
 
 
 


Edited by Tom H - 20 Mar 2012 at 11:19am
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