As per IPC-RB-276 section 3.2.2: Pink Ring: A zone around a through hole/internal layer interface from which the oxide coating on the copper has been discolored or chemically removed. As per IPC-RB-276 section 3.6.2.3: Pink Ring: No evidence exists that pink ring affects functionality. The presence of excessive pink ring may be considered an indicator of process or design variation but is not a cause for rejection. The focus of concern should be the quality of the lamination bond. I have not read in any discussions evidence that a mismatch in the thermal expansion will cause pink ring. Does anyone have any QUANTIFIED data (other than the empirical data of those who have switched) on the problems and benefits of direct connection vias to plane layers? So far, I have heard two types of response -- "We switched and have had no problems", and "We haven't tried it, but you might want to watch out for <insert potential problem here>..." Has anyone done any mixed designs (ie: thermals on the Vcc layer and direct connections on the GND layer) with the intention of creating an impedence "slope" to funnel noise to the ground plane? [log in to unmask] Don Walker **************************************************************************** * The mail list is provided as a service by IPC using SmartList v3.05 * **************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ****************************************************************************