RE: Testing for dry joints - :)
Scott asks .. So I give up - just what exactly is a dry joint? Dry joint: Electrical context: - A solder joint in which the electrical connection between two conductors has been poorly formed by the solder material; a consequence of incomplete formation or surfaces not properly wetted by the soldering material. Testing for these - as this group has shown - can be quite difficult. For more information on this type of dry joint, visit http://www.circuitsassembly.com Glastonbury Context: - Crushed weed or herbs of various descriptions usually rolled up in light paper ( tabloid newspapers make excellent wrappers) and used exactly like cigarettes. Testing for a dry joint should be done in secrecy as there are legal connotations associated with their use. In the interest of keeping this forum blameless, the quest for more information on this type of joint will be left to the reader. Rastafarian context: - Sensemelia dat bringz I an' I guud vibes man! Jah be prezd! Tess-teeng nat necessary. U av' some', u gretful, U pass it round, U a good frend, but wen U pass it around, keep it an de left 'and side. Night club context: - A night club that has run out of liquor. Testing for these is visual. They will usually have no revelers. Butcher's context: - Leg of lamb of the Halal variety, dried or well done . Testing for these is essential as 'succulent' might be the preferred end result of the culinary process. Surgeon's context: - Quality and effectiveness of lubrication following hip replacement. Testing inevitable. Homeless context: - Welcome refuge on rainy nights. Best regards - Chris -Original Message- From: Scott Douglas [SMTP:dougl...@naradnetworks.com] Sent: Friday, October 11, 2002 8:34 PM To: Chris Chileshe; emc-p...@majordomo.ieee.org Subject:Re: Testing for dry joints Chris, So I give up - just what exactly is a dry joint? Scott At 09:55 AM 10/9/2002 +0100, Chris Chileshe wrote: Hi Group, Probably not the appropriate forum but here goes anyway. A colleague is finding numerous problems with subtle dry joints (partial) between connectors and PCBs and is wondering if there is a way - short of new procedures in process control - that dry joints can be tested for? The specific problem is that the joints appear to be electrically sound to start with, meaning the units are getting through function test, but once exposed to endurance (lengthy) tests or worse still, actual practical use, the gremlins begin to show. The fault analysis almost invariably leads to a connector dry joint. The connectors are rated for 6A DC continuous. Any ideas how these can be picked up early or what measures you have in production to eradicate these problems? Regards - Chris Chileshe - Ultronics Ltd This e-mail has been scanned for all viruses by Star Internet. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list This e-mail has been scanned for all viruses by Star Internet. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk This e-mail has been scanned for all viruses by Star Internet. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line
RE: Testing for dry joints - Thank you
Thank you everyone for your very informed replies on the subject. 'Endurance' and 'use' does indeed involve vibration. The units are used on off-highway heavy duty vehicles and forklifts. The contacts are not gold-plated and I am glad I didn't make that clear because the info forthcoming (Thank you JW) is quite relevant to a second product I am working on. What is clear is that it is best to sort out the process. Saves one a lot of grief later on. Your replies have provided the much needed leverage to get process control to take responsibility. Best regards - Chris Chileshe - Ultronics Ltd This e-mail has been scanned for all viruses by Star Internet. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: Testing for dry joints
I read in !emc-pstc that Chris Chileshe chris.chile...@ultronics.com wrote (in 01c26f7a.00510c40.chris.chile...@ultronics.com) about 'Testing for dry joints' on Wed, 9 Oct 2002: The specific problem is that the joints appear to be electrically sound to start with, meaning the units are getting through function test, but once exposed to endurance (lengthy) tests or worse still, actual practical use, the gremlins begin to show. The fault analysis almost invariably leads to a connector dry joint. Can you please provide more information: - do these joints involve gold-plated parts? - do the endurance tests and use involve vibration? Gold plated parts can cause bad joints through the development of a non- conducting interface between the solder and the metal that was gold- plated before the plating dissolved in the solder. Such bad joints are extremely difficult to find, because the fault is hidden inside a perfectly formed solder pad. The remedy is usually to increase the soldering temperature, but a change of flux may also be necessary. Failure due to vibration produces a characteristic grey, almost micro- crystalline appearance of the solder pad. The remedy is self-evident, but may be difficult to implement. I know a way of detecting some types of *potential* bad joint, using an audio-frequency non-linearity test. It can be very sensitive, but obviously I don't know whether it would work in your case. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Testing for dry joints
Dear Chris, If I remember correctly from my days in Britain's National Coal Board, thermal imagers and other temperature sensors were used to check cable joints underground. Poor connections had a higher resistance, and were thus hotter, than their neighbours. I don't know whether such a test methodology is feasible in your case. Ian Unwin Servomex Group Limited This email has been scanned for all viruses by the MessageLabs SkyScan service. For more information on a proactive anti-virus service working around the clock, around the globe, visit http://www.messagelabs.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Testing for dry joints
Chris IPC-A-610 Rev C, covers various inspection criteria for a whole host of solder quality related issues. Most are visual inspections of the board, but in some cases you will need to micro section the joint in question to be sure. But generally you can see a bad joint form the visual inspection or at least get an indication of the over all solder quality. HALT testing can very quickly bring out dry solder joints, but this is expensive and destructive. More mundane environmental testing can be time consuming. With neither methods really being suitable for a 100% screen of all the product. I have had some success with Thermal Imaging to as a non destructive screen for poor solder joints, but this requires a very high optical and thermal resolution camera. The best initial step to pick up these problems would be a solder quality inspection to IPC-A-610. Then depending on these results decide if micro sectioning or environmental screening is required. Andrew Carson - Senior Compliance Engineer, Xyratex, UK Phone: +44 (0)23 9249 6855 Fax: +44 (0)23 9249 6014 -Original Message- From: Chris Chileshe [mailto:chris.chile...@ultronics.com] Sent: 09 October 2002 09:55 To: emc-p...@majordomo.ieee.org Subject: Testing for dry joints Hi Group, Probably not the appropriate forum but here goes anyway. A colleague is finding numerous problems with subtle dry joints (partial) between connectors and PCBs and is wondering if there is a way - short of new procedures in process control - that dry joints can be tested for? The specific problem is that the joints appear to be electrically sound to start with, meaning the units are getting through function test, but once exposed to endurance (lengthy) tests or worse still, actual practical use, the gremlins begin to show. The fault analysis almost invariably leads to a connector dry joint. The connectors are rated for 6A DC continuous. Any ideas how these can be picked up early or what measures you have in production to eradicate these problems? Regards - Chris Chileshe - Ultronics Ltd This e-mail has been scanned for all viruses by Star Internet. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Testing for dry joints
Hi Group, Probably not the appropriate forum but here goes anyway. A colleague is finding numerous problems with subtle dry joints (partial) between connectors and PCBs and is wondering if there is a way - short of new procedures in process control - that dry joints can be tested for? The specific problem is that the joints appear to be electrically sound to start with, meaning the units are getting through function test, but once exposed to endurance (lengthy) tests or worse still, actual practical use, the gremlins begin to show. The fault analysis almost invariably leads to a connector dry joint. The connectors are rated for 6A DC continuous. Any ideas how these can be picked up early or what measures you have in production to eradicate these problems? Regards - Chris Chileshe - Ultronics Ltd This e-mail has been scanned for all viruses by Star Internet. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
