Dennis and others, Your comments are much appreciated on this, the copper was etched before laser drilling, and permanganate desmear. This is Paladium metalization and Revese Pulse plated, so the hole geometry is what needs addressing, it seems. Time to back down on the laser power \.../ Larry Russell -----Original Message----- From: Dennis Fritz [mailto:[log in to unmask]] Sent: Monday, September 12, 2005 10:16 PM To: [log in to unmask] Subject: Re: [TN] Microvia Puzzle The microvia you have sectioned will be an enormous problem to electroplate - as you have found out. It appears that very significant etchback of the resin/glass under the copper foil has occured. The "shelf" left by the copper surface foil is requiring the copper to plate back under itself. This type of "desmear" was common when plasma was used to remove resin only dielectric some years ago. The way the overhang problem was solved was to agressively microetch the surface foil to remove all the overhang. I suggest the same thing here. How was the original copper foil removed for this microvia? You say CO2, but it appears to me that too much copper is present for the CO2 to cut through it. Either, this was a combined UV/CO2 microvia drill where the UV cut the initial foil and the CO2 removed the epoxy and glass fibers, or the original hole in the foil was chemically etched. Notice how the microvia drill stopped nicely at the level two copper foil - the way CO2 drills do. I think your microvia will be easier to plate with more of a "V" shape, and certainly no copper foil overhang. Denny Fritz MacDermid, Inc. --------------------------------------------------- Technet Mail List provided as a 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------