A 1:1 aspect ratio for blind vias should not be considered the limit. There are some DM processes that can "coat" blind vias to make them conductive rather than rely on the electroless copper process to get into the bottom of the hole. Since the gassing of electroless copper precludes going much higher than a 1:1 aspect ratio, i.e.the gassing limits deposition in the bottom of a blind via, the next limitation becomes that of electrodeposition itself. Providing the entire hole is conductive, I've seen aspect ratios of closer to 2:1 for blind vias. And that's only with conventional electroplating technology. Imagine the possibilities when the industry gets to working more on the electroplating aspects of blind via board construction. Roger Mouton INSULECTRO Lake Forest, CA *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************