I’m making a board with TI’s AFE4490 chip and I’m currently working out how to make the appropriate footprint for it, which is QFN-40 with 0.5mm pitch.
One option that I found was to use the existing “QFN-40-1EP_6x6mm_Pitch0.5mm” footprint in the “Housings_DFN_QFN” library. The library footprint was similar to the recommended footprint in the datasheet, but the dimensions were not as close as I’d like them to be. Has anyone tried using this footprint before? How did it work out?
Instead, I modified the existing footprint to follow the recommended footprint and solder paste patterns more closely. This is what I’ve come up with so far: (can’t upload the .kicad_mod file yet because i’m a new user)
Following the datasheet recommendations, I made the pin pads slightly longer and wider and made the exposed pad out of a 3x3 pad array with about 69% solder paste coverage. I also tried to implement the rounded inner parts of the pad by adding circular pads of the same net. Will these changes work? Do you think it will make much of a difference in assembly quality?
I noticed that the footprint provided by the library did not have soldermask between the pins in the 3D viewer, but mine does. I’m a bit new to making footprints. Are there any things to watch out for when putting soldermask between the small pitch pins, such as design rules?
I haven’t yet implemented thermal vias as suggested in the datasheet. I don’t expect to need them, but will likely put them in just in case. Any suggestions for a newbie on where to start for this task? Any suggestions for improving the footprint that I have so far?
Thanks for reading,