SOT-223 tab pad

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   I'm normalizing my SOT-223/TO-261 FPs across multiple manufacturers.  The dimensions I'm using are identical across 4, 5, and 6 pin except for the pitch and pin widths.  I've noticed that with LEP 2019.07 the tab pad size changes along with its corner radii when the smaller pins on the other side change.  For example, the Y size on a 4-pin is 1.8mm but on a 5 or 6-pin it is 1.65mm.  Is this intentional?  What is the rationale?

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jhansonxi Members Profile Send Private Message Find Members Posts Add to Buddy List New User Joined: 13 Dec 2012 Location: Michigan, USA Status: Offline Points: 8	Post Options Post Reply Quote jhansonxi Report Post Thanks(0) Quote Reply Topic: SOT-223 tab pad Posted: 06 Sep 2020 at 4:02pm
	I'm normalizing my SOT-223/TO-261 FPs across multiple manufacturers. The dimensions I'm using are identical across 4, 5, and 6 pin except for the pitch and pin widths. I've noticed that with LEP 2019.07 the tab pad size changes along with its corner radii when the smaller pins on the other side change. For example, the Y size on a 4-pin is 1.8mm but on a 5 or 6-pin it is 1.65mm. Is this intentional? What is the rationale?



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: 5716	Post Options Post Reply Quote Tom H Report Post Thanks(0) Quote Reply Posted: 06 Sep 2020 at 4:42pm
	You are in 100% control of the Preference Options. If you are using Library Expert Pro, you can select the "Rules" tab and change the "Corner Radius Size" values to anything you want. There is: Corner Radius Size (% of Pad Width) Corner Radius Size Limit Corner Radius Round-off Change the "Corner Radius Size Limit" to 0.10 and you'll tighten up your corner radius values. If you get the Free Library Expert Enterprise on a Cloud License you just pay for the yearly maintenance to get all the updates and technical support. Then you can have access to the Global Preferences so that you set the values once and it applies to every footprint. The Enterprise edition allows you access to over 1,000 preference settings to globally apply to every footprint.
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jhansonxi Members Profile Send Private Message Find Members Posts Add to Buddy List New User Joined: 13 Dec 2012 Location: Michigan, USA Status: Offline Points: 8	Post Options Post Reply Quote jhansonxi Report Post Thanks(0) Quote Reply Posted: 07 Sep 2020 at 9:06pm
	I know I can change it in the preferences. I can also change it in Altium. But that doesn't answer my question: Why does the small pin dimensions affect the Tab Pad?