4

I'm using Atmel SAM chips and the data sheets don't have any mention of solder mask clearance for their TQFP packages. What would be a nominal pad/solder mask opening/cream size for a 0.5mm pitch package?

pdel
  • 285
  • 4
  • 14

1 Answers1

5

You should ask your board house what they need to account for registration errors. My board house needs 0.003" on each side of the pad. As for the paste layer, it depends on the pasting process. If it's the classic stencil and squeegee process, you need to be mindful of the thickness of the stencil. I recently did a 0.5mm TQFP, and with 95% coverage and a 0.005" stencil, did just fine. Having leads for excess solder to climb helps a great deal. I'm not aware of any hard, fast rules here.

Matt Young
  • 13,734
  • 5
  • 34
  • 61
  • Is it generally advisable to go with whatever the minimum spacing is? – pdel Oct 06 '14 at 19:17
  • It will never hurt you to have a solder dam in between pads. If they are present, and you're seeing a lot of solder bridges, there is probably too much paste being applied. – Matt Young Oct 06 '14 at 19:21