In some cases, thinner is better. For example, when you look at solder joint reliability, the thinner the board, the more reliable the joint is. Why? Because thinner board can flex and not constraining the solder joint as much as the thicker board. However, the laminate is stretching the copper barrel in the case of PTH symmtrically - no flexing. The more copper on the barrel means more material bearing the load. You are right about not relying solely on intuition. That's why we also run experiments, e.g. thermal cycling, to verify these theories. 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 ---------------------------------------------------------------------------------