Poh Kong Hui said: >Hello Olly and Technetters, > >Could you tell me what is LQFP ?. And I am not too sure the meaning of >"thicker version" of the std QFP.... No. Someone is always making up obscure acronyms, though. >The interesting part is that it only happened on only one part number, >and the board contains other QFPs of other vendors, but no problem. > >Any idea ??? Yes. Remove one of the parts with "lifted" legs, using minimal heating or simply by desoldering the pins. Examine carefully the bottom of the plastic molded surface, with suspicion that the surface is now rounded outward with the dreaded popcorn disease. If this are TQFP's (thin quad flat pack), it is a strong possibility. The effect is that the molded plastic will swell downward, the part will then tilt during reflow toward the edge whose leads wet first, leaving the other edge with no contact to the paste. Some of these TQFP's have literally paper thin plastic underneath the diepad in the belly area of the part. Make sure the parts have been properly drypacked, stored, and that your profile is not giving this area of the board too much heat. The ramp up portion of the profile needs to be as gradual as possible. regards, Jerry Cupples Interphase Corporation Dallas, TX USA http://www.iphase.com *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************