0402's Tombstoning

Bryan,

0402's tombstonning isn't that uncommon and usually the 1st reaction is alway's the pad size aint right. If you've followed the IPC guidline's normally you should be fine but I'd double check the component supplier's spec's as well. brian's point about the profile is a good one, your unlikely to be using the same oven type as the sub contractor so your profile wont be exactly the same anyway since not 2 oven's ever are. You also as brian suggest's need to check on the N2 situation and find out what they are using plus what paste. the key's for the tombstonning are normally the ramp rates and the pad sizes which basically comes down to the wetting forces that your setting up, so maybe something else to consider is the end cap terminations and what the plating is vs the paste and the PCB finish, e.g. HASL / Silver palladium / gold etc. An old tric is to turn of the N2 and run it in air to slow down the wetting, you may also what to look at copper loading aorund the chip's and the direction's although with today's oven's this really shouldn't be a problem.

JohnW

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