Capacitors in Tombstone position

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Capacitors in Tombstone position

Post by RE07222013 » 14 Nov 2016, 15:43

Capacitors have dimensions in LxWxH. Sherlock accepts those dimensions as LxWxThickness. I enter that information in the parts database. In the circuit board layout, the capacitor may be turned (tombstone) so its dimensions become LxHxW. What is the best way to handle this situation?

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Re: Capacitors in Tombstone position

Post by natalieh » 13 Dec 2016, 10:46

If the capacitor is in a tombstone position, LxWxH=LxHxW and that is perfectly acceptable in Sherlock. The best way to handle this situation would involve adjusting the bond pad properties.

For example, I have a capacitor that is 3x5x2mm. If I changed its orientation such that it is now in a tombstone position, the dimensions would now be: 3x2x5mm. The width is now 2mm, therefore its bond pad width needs to be smaller so that the correct solder joint shape is produced.

With the bond pad dimensions changed to account for the geometry of the capacitor, the solder joint shape produced in Sherlock will be accurate.

Please let me know if you need further clarification!
Natalie Hernandez, PhD
Sr. Project Manager
ANSYS DfR Solutions

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