Thanks to you and Brian Ellis for your suggestions. We do business with a lab that can do SIR and IC testing. The only change we are making to our process is a change from one no clean flux (which seemed to cause adhesion problems with our polyurethane coating) to Indium #9942. We have completed 100 cycles of thermal shock per the IPC test noted below and the conformal coating adhesion appears to not be a problem with the Indium flux. We are considering cycling the test samples in a chamber from -40 C to +70 C in 95% humidity and then rechecking (IC lab testing probable to verify no unacceptable ionic contamination levels on the boards. Anyone have any views on the utility of this? SIR testing only? -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Joe Russeau Sent: Wednesday, November 12, 2008 2:58 PM To: [log in to unmask] Subject: Re: [TN] Flux Qualification Hi Ken, If you are trying to look for electrochemical (ECM) failures as a result of the flux, then you may wish to consider doing SIR testing per IPC-TM-650, method 2.6.3.7. The conditions used in this method (40 C / 93% RH with a 10 VDC bias and test for 7 days using continuous monitoring) have been shown to be more stringent than using higher temperatures with high humidity (i.e. 70 C / 95% RH), especially for low solids fluxes (i.e. no cleans). Part of the drawback of using higher temperature / humidity test environments, is that you often cook off the very residues you are trying to observe. Work done by Dr. Chris Hunt of NPL showed that lower temperatures with high humidity and lower biases was better for evaluating the potential for ECM events due to flux residues. All that said, I would suggest evaluating the flux residues using the above method with a test board that is designed for SIR and has components to mimic modern assemblies. The IPC-B-52 board comes to mind. I would highly recommend that you obtain the Gerbers for the board you choose and have them made by your preferred supplier with your preferred materials and surface finish. This may cost you a bit more, but it gives you an apples to apples comparison. Secondly, it would be a good idea to compare the residues from your current materials against the Indium material using ion chromatography. This will give you some important additional data and provide a baseline to compare to the SIR data and to the performance of your current paste / flux material. Anyway, I hope this helps. Best Regards, Joe Russeau ----- Original Message ----- From: "Chafin, Ken G." <[log in to unmask]> To: <[log in to unmask]> Sent: Wednesday, November 12, 2008 1:13 PM Subject: [TN] Flux Qualification We are trying to qualify a no-clean flux to be used in our wave solder process. The flux in question is Indium #9942. After wave soldering our boards are conformal coated with polyurethane coating Conathane CE-1164. We have done some baking of a test sample at 70 degrees C and and have tested per IPC-TM-650 2.6.7.1--thermal shock test. This testing was done primarily to evaluate the adequacy of the adhesion of the conformal coating. We are interested in further evaluating this flux to determine if it contributes to corrosion development or other undesirable effects. We are considering "soaking" a sample in a chamber at 70 degrees C at 95% relative humidity for four or five days. I am interested in any recommendations for further testing--standards-related tests, nonstandards-related tests that may reveal undesirable properties in the flux, etc. Thanks Kenneth Chafin Quality Compliance Leader <file:///c:/signature/Email%20signature_files/image001.jpg> 1000 Technology Drive Pittsburgh, PA 15219-3120 USA Telephone: +1-412-688.2400 Ext [Ext] Telefax: +1-412-688.2399 www.ansaldo-sts.com <http://www.ansaldo-sts.com/> CONFIDENTIALITY This message is strictly confidential. Its content and use is restricted to the designated recipients. The use, copy, reproduction or transmittal by any process or means without prior written notice of the Author or Ansaldo STS / Union Switch & Signal Inc. office of the Legal Counsel is strictly prohibited. If you have received this message in a transmission error, please inform the sender immediately and destroy any copy, saved files or print you have erroneously made. 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