Joking aside... About those vias.



Are they via in (SMT) pad?



What type vias?



Copper filled uVia?

PTH?



If PTH, how filled and plated over?



*VIPPO PTH?

Epoxy filled PTH (non-VIPPO, sometimes just filled prior to surface finish))?



*Via In Pad Plated Over





-----Original Message-----

From: TechNet <[log in to unmask]> On Behalf Of Guy Ramsey

Sent: Friday, August 2, 2019 11:32 AM

To: [log in to unmask]

Subject: [EXT] [TN] Jumping QFNs



We are experiencing a bout of QFNs that jump off the pads, even off the assembly during reflow.

The parts are handled in accordance with J-STD-033.

The boards are complex multilayer sequential lamination with thousands of vias, blind, buried, and through hole. All exposed vias are filled and plated,with ENIG finish.

We bake the boards 10 hrs at 105C.

Solder paste is FCT WS159 . . . I know, I know.  The Peregrine parts don't solder well unless the flux is crazy active.

Any ideas on why about 2-5 percent of the parts jump off the pads or assembly completely?

Can this be just a solderability problem?