Peter, I just use micro vias to get the dogbones on the second layer then use a bottum up blind via to that layer, when the aspect ratio is below 10:1. This provides the test pads on the bottom side. When the aspect ratio gets absurd, I do the double micro via trick with buried vias connecting both sides. You already knew that but I needed to say it for some strange reason. I've been filling, sequentially laminating and plating over the top for many years. Still have some dimples but minor stuff. Works well and have you all noticed how prices have come down significantly? Why do you suppose that is? Earl --------------------------------------------------------------------------------- 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 e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest 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 ---------------------------------------------------------------------------------