hi everybody, We've been doing some studies on assembly of CSPs , namely ones like the tessera 46 I/O, FCT ultra CSP to name a few. We assembled these packages on micrivia-in-pad patterns. These are 15/13.5/11 mil pads with 6 mil design microvia, using photo/laser/plasma tech. We are seeing voids, as big as the microvia, and they sit exactly at the via opening. The process we use is pretty robust, using nitrogen for reflow and the problem is seen for both solder and flux. The reliability data is still not out,but we expect the voids to make a diffrence. Would appreciate some inputs on why/how? and what to do/what not to do? THanks in anticipation Parvez M.S. Patel Graduate Research Associate, Universal Instruments Corporation, SUNY - Binghamton, New York. Ph: 607 779 7215(O) Fax: 607 779 4646 *************Equilibrium is death. Seek persistent non-equilibrium*************** ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################