Hi, We use type UR, AR, SR coatings to coat boards. Urethane coatings are hard (stiff) coatings that lead to these defects as they cannot yield to the expansion/contractions during thermal cycles. Is there a specific reason (property) of 1A20 that you use it for?. Another suggestion to this problem would be to use acrylic coatings (1B31, 1B73 etc) Sincerely, Amol Kane M.S (Industrial Eng.) Process Engineer Harvard Custom Manufacturing 941 Route 38 Owego, NY 13827 Phone: (607) 687-7669 x349 [log in to unmask] -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Marsico, James Sent: Monday, May 22, 2006 1:17 PM To: [log in to unmask] Subject: Re: [TN] Cracked ICs Hello, again... All indications are leading to the conformal coating as the culprit for the cracked 8-pin DIPs. The urethane coating (Humiseal 1A20) is dip-applied, and a typical assembly has bridging between the component body and the PWB, as well as between the component body and the leads. Ten ESS thermal cycles of -51 to +85C prior to coating showed no cracks, but samples cycled after coating had some cracks. My suggestion to the supplier was to spray-apply the coating and inspecting for coating bridging. Have you experienced anything like this before? Jim Marsico Senior Engineer Production Engineering EDO Corporation [log in to unmask] <mailto:[log in to unmask]> 631-630-5079 -----Original Message----- From: Russ Winslow [SMTP:[log in to unmask]] Sent: Wednesday, May 10, 2006 5:58 PM To: TechNet E-Mail Forum; Marsico, James Subject: RE: [TN] Cracked ICs Hello James, Here are a few things to look for. The 8-pin cerdip package does not have much surface area for the glass seal especially if the die is large. A lead forming step prior to board assembly could be the cause. If you are forming the leads inward be certain that only the minor leads (the skinny portion) are being bent. If the major leads (the wide portions) are bent simultaneously then you may very well pop the cap from the base or cause these perimeter cracks. Another thing to look for is cracks before board assembly. Cerdips are prone to glass cracking caused by tube to tube handling. I have never heard of cracking due to reflow process unless you are doing vapor phase without preheat. Some automatic lead straighteners will crack 1000 units per hour so do not let them come anywhere near your glass sealed components. Another cause could be a lead tinning (hot solder dip) step. Without proper preheat a supplier could cause serious damage to the glass seal. If you send me a sample I can probably tell you much more. (no charge!) Regards, Russ Winslow Six Sigma 905 Montague Expwy Milpitas, CA 95035 [log in to unmask] www.sixsigmaservices.com Phone (408) 956-0100 x 111 Fax (408) 956-0199 -----Original Message----- From: Marsico, James [mailto:[log in to unmask]] Sent: Wednesday, May 10, 2006 6:11 AM To: [log in to unmask] Subject: [TN] Cracked ICs Hello Technet, We're seeing a recurring problem of a cracked ceramic IC, assembled on a through-hole PWB. The component is an 8-pin DIP, T.I. P/N 5962-9452601QPA . The crack is located below the lead frame and radiates all the way around the device. Has anyone experienced this before? Please respond directly to me, as I cannot receive e-mails from Technet. Thanks in advance, Jim Marsico Senior Engineer Production Engineering EDO Corporation [log in to unmask] <mailto:[log in to unmask]> 631-630-5079 --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------