Edwin, Are you talking about plating a heat sink after it is attached? I don't understand the comment about aluminum, but since you said "blind", it must be attached. Ask you supplier what the problem is. That aspect ratio for normal blind vias is not a problem; but plating dead-ended blind vias with nickel over copper on a heat sink might have some problems with current .... I just don't fully understand the application .... the supplier might have a better solution. Valerie --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/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 -----------------------------------------------------