Screaming Circuits: Funky Footprints


Funky Footprints

Parts with uneven solder pads cause headaches on a fairly regular basis when matched with PCB land patterns that don't also follow the uneven dimensions.

The actual layout, as seen on the left, won't work too well. The surface tension of the molten solder will act on the bigger surface area of the pad on the left and cause the part to shift to the left during reflow. That can lead to reliability issues. In some similar cases, it can also lead to shorts with nearby components or mechanical structures. This part will end up pretty close to the cut-out edge and something structural there could interfere or hit and stress the mechanical bond.

Pad_causes_part_to_shift_in_oven_pr

In the simulated, more betterer landing pad on the right in the red box, both pad sizes on the PCB match in size both of the solder areas on the part. This way, surface tension will act equally on both sides and the part will stay right where it's supposed to.

Duane Benson
Keep off the mask, ya young whippersnapper...

TrackBack

TrackBack URL for this entry:
http://www.typepad.com/services/trackback/6a00d8341c008a53ef00e55364537f8833

Listed below are links to weblogs that reference Funky Footprints:

Comments

Yes. Much morer betterer. :-)

more betterer????

Post a comment

If you have a TypeKey or TypePad account, please Sign In.

« Solder Lug vs. PC Mount | Main | Five Years and Counting »