Dave, If you have Puligandla Viswanadham's book Failure Modes and Mechanisms in Electronic Packages, you may find an explanation. On page 164 he shows something that reminds of your wavy PTH. He speaks about a combination of rough drilling, delamination, copper barrel spiral cracking and finally, the solder's inability to wet this messy barrel properly. The result can be a wavy PTH. Ericsson Microwave Systems -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Dave Simonik Sent: den 3 september 2004 17:40 To: [log in to unmask] Subject: [TN] Wavy Holes. Technetters; One of those Friday questions: Has anyone seen, experienced, or dealt with 'wavy' through holes in thick backplane type pcb constructions? I have searched the Technet archives, but came up empty handed. We have begun to see this phenomenon on some of our tougher thick constructions, and we are scratching our heads in trying to define the root cause of this issue. The holes appear somewhat like this after drill: | | \ \ / / | | / / \ \ | | We have seen this on hole sizes .020" - .032". We have begun to set up some DOE's. Even our tool supplier is lost for words, trying to imagine how such a large tool can 'wave' like that during the drill cycle. If anyone wants further details, please contact me offline. I have many digital photo's of this issue if anyone wants to offer their services in posting a picture on a web site. Thank you. David R. Simonik ------------------------------------------ Laser Engineering Technician Sanmina - SCI Corporation Owego NY Division 1200 Taylor Rd. Owego NY 13827 Office: 607-689-5609 Fax: 607-689-5909 <mailto:[log in to unmask] <mailto:[log in to unmask]> > --------------------------------------------------- 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 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- 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 847-509-9700 ext.5315 -----------------------------------------------------