Hi Goran, In a message dated 02/03/0 9:12:26, [log in to unmask] writes: >I have a question. People say that plated through hole is the weak link >in the printed circuit board. Not necessarily, it depends on the design, material choices, PCB PTH/PTV interconnect quality, the severity of the soldering operations, and the severity of the use environment. >What is the data, i.e., when does a PTH fail (at what temp cycling, at what no. of cycles)? See IPC-TR-578 (September 1984), IPC-TR-579 (September 1988), and IPC-D-279, Appendix B, (July 1996). If you need to know more details, you should attend my workshop "Design for Reliability and Quality Manufacturing of Plated-Through Holes and Vias" at NEPCON West, Fe. 29, 2000, or at IPC Expo, April 2, 2000 > >For microvias, PTH are often filled and planarized. Is a filled PTH >more reliable? Any data on this? Has anyone looked whether a pure >dielectric vs. filled dielectric vs. a Ag-filled paste make a >difference? Microvias, unlike PTHs/PTVs, are not loaded significantly during assembly and service--so, unless there are quality problems no threat to reliability need to be expected. Filled (solder better than organics) are more reliable than unfilled PTHs/PTVs in terms of innerlayer separation (ILS), but are more prone to barrel cracking if there are voids in the solder-fill (voids are immaterial for organic fills). A fill with a CTE closer to Cu is better as are fills with higher modulus of elasticity--fillers typically tend to change the properties in these directions. Werner Engelmaier Engelmaier Associates, L.C. Electronic Packaging, Interconnection and Reliability Consulting 7 Jasmine Run Ormond Beach, FL 32174 USA Phone: 904-437-8747, Fax: 904-437-8737 E-mail: [log in to unmask], Website: www.engelmaier.com ############################################################## TechNet Mail List 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 web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################