Buried via will be different from PTH because it is typically filled with resin from the prepreg or some via fill material. Our finite element results suggest that there might be some increase in the strain in copper for buried via when filled with resin. This is because resin has a low elastic modulus (does not help to bear stress) and a high CTE (help stretch the copper barrel even more). We have observed failures in buried via, which prompted us to do this FEA study. Type II, HDI design has buried via from L2 to Ln-1. The reliability of these vias should be looked into further. Regards, Mason --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------