Hi Gary, Based upon the information that you have disclosed so far on the TechNet Forum, I would agree with the comment that the pin is structurally OK but the solder joint is fractured due to the shear force applied by the attachment of the heat sink. If you are interested in having a stress analysis of the configuration, and you are willing to provide me with all of the details relative to the design configuration, which includes the material combinations used, the physical dimensions, material properties (specifically modulus of elasticity, and TCE) and etc., I will take a crack at performing a structural stress analysis that determines the shear stress level in the solder joints due to the assembly condition. Regards, faz -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Dehoyos, Ramon Sent: Friday, February 02, 2007 8:42 AM To: [log in to unmask] Subject: Re: [TN] Mechanical Stress on solder joints The pin seems to be intact. The solder joint appears to have caved in and separated from the pin. Something needs to be changed. Either just tack two pins to hold the Converter prior to have the heat sink attached, then reflow both pins at the same time and finish soldering the rest of the pins manually or change the way the heat sink is attached so that it does not pull the converter during attachment. Ramon -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne Thayer Sent: Thursday, February 01, 2007 4:35 PM To: [log in to unmask] Subject: Re: [TN] Mechanical Stress on solder joints Gary- The bottom line is that electrical solder is not a reasonable load bearing material. You can relieve the stress in the joints by reflowing the connections after attaching the heatsink. IF the pins aren't long enough to make that work, then re-think your mounting, because there is no way that it will be reliable with the joints under stress, even if there is no additional environmental stress placed on the system. Wayne Thayer >>> [log in to unmask] 2/1/2007 3:51:03 pm >>> Steve, This is side view of the module with the broken pin. There is a heatsink above approximately 0.100 thick with 4 screws pulling the DC/DC converter upward away from the circuit board. I do not want to place any solder joints under load wither it be clamping or pulling forces. Thanks, Gary Bremer Senior Manufacturing Engineer, CIT Phone: 257-4430 extension 2170 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory Sent: Thursday, February 01, 2007 9:35 AM To: [log in to unmask] Subject: Re: [TN] Mechanical Stress on solder joints Hi Gary! I have your picture posted. It's at: http://stevezeva.homestead.com/files/Broken_Pin.jpg It sure looks like something has pulled or stressed that pin. I'm trying to visualize the heatsink, but I can't form a mental picture of it, so I can't say for sure if it was the heatsink or not. But from your description, it seems pretty probable that the stress that you describe damaged that pin. -Steve Gregory- -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Bremer, Gary Sent: Thursday, February 01, 2007 10:02 AM To: [log in to unmask] Subject: [TN] Mechanical Stress on solder joints Gentlemen, I have a device that failed in the field, the part is a DC/DC converter that is first soldered to the circuit board then a massive heatsink is screwed to the converter pulling the device upward because of an air gap not covered by a thermal conductive pad. Could this be the cause of damage to the component pins as shown in the attached photo? The solder used is Sn63 on the circuit board side and the mass of the board solder joint appears to be twice that of the component. Gary Bremer Senior Manufacturing Engineer, CIT Curtiss-Wright Controls Inc. Embedded Computing -Subsystem 28965 Avenue Penn Santa Clarita, CA 91355-4185 Main: 661.257.4430 extension 2170 Fax: 661.257.4782 e-mail: [log in to unmask] Web: www.cwcembedded.com NOTICE: This e-mail communication is private and confidential and is intended for the addressee only. The email may only be used for conducting business with VISTA Controls Inc., dba Curtiss-Wright Controls Embedded Computing Subsystems. If you are not the intended recipient, please notify us by replying to this email followed by deleting the email and all attachments from your system. Anyone other than the intended recipient or those with a need to know within the recipient's organization is strictly prohibited from using, printing, distributing or disseminating the email or any information or attachment contained therein. --------------------------------------------------- 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 ----------------------------------------------------- ______________________________________________________________________ <<Failed Module.bmp>> <<heatsink.jpg>> --------------------------------------------------- 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 ----------------------------------------------------- ______________________________________________________________________ CAUTION: This message was sent via the Public Internet and its authenticity cannot be guaranteed. ______________________________________________________ ************************************************ The information contained in, or attached to, this e-mail, may contain confidential information and is intended solely for the use of the individual or entity to whom they are addressed and may be subject to legal privilege. 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