The presence of measling is generally not considered a defect. The laminate fabricators test to IPC-4101, which is basically a thermal cycle on a 12x12 sample of etched laminate - testing for any visual/mechanical changes that could indicate a structure issue. The presence of measles on a PCB should be qualified by the an additional thermal stress (550f/10s) to the effected area and ensure the measles do not propagate. If propagation is evident, then the subsequent thermal excursions in assembly will worsen the condition. Either way, the presence of measles if generally either an issue with the base materials or a management of the thermal cycling process during solder coating/assembly. Heavier copper cladding increase the propensity for measling as the CTE mismatch of the package creates stress to the reinforcement of the laminate. In our process we check for propagation and any reduction in design spacing below 50% or the minimum circuit spacing in tighter areas where the 50% rule is to close. Jeffrey Bush Director, Quality Assurance and Technical Support 76 Technology Drive - POB 1890 Brattleboro, Vermont 05302-1890 Tel. 802.257.4571.21 Fax. 802.257.0011 [log in to unmask] http://www.vtcircuits.com -----Original Message----- From: Richard Kraszewski [mailto:[log in to unmask]] Sent: Wednesday, August 11, 2004 12:41 PM To: [log in to unmask] Subject: [TN] IPC Test methods for measeling of laminate Can any one tell me what the appropriate IPC test methods would be measeling of FR4 laminate? I understand there is a float test of some sort. Rich K / KEDS --------------------------------------------------- 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 -----------------------------------------------------