Bryan I am not sure if already posted a reply to your question - (withdrawal symptoms from a week-end absence from the TechNet?) but I do have a suggestion to validate your process: Circuit Reliability Testing Concoat are able to assist in providing Process Characterisation/Validation tests using new Auto-SIR(tm) Surface Insulation Resistance (SIR) test methods with Frequent Monitoring, Trend Analysis (FMTA) techniques. (Sorry for the advert but this is a unique capability.) SIR testing measures the actual effects of both Ionic and Non-Ionic contamination, on the surface insulation resistance of your representative assembly under conditions of accelerated ageing, to better predict the reliability of your product. The testing should be conducted according to: Either: J-STD-001B Class 2 (7 day test) Or: J-STD-001B Class 3 (7 day test cycling) Both require special SIR test coupons incorporating inter-digitated comb patterns that should be processed simultaneously with the existing production processes. These coupons, such as IPC-B36 should permit component overmounting to the test patterns. The test should offer a complete SIR overview of the total process. The coupons must be prepared by production means and entered into the test at subsequent stages of the production process. For example, and based upon an original enquiry on the TechNet by Jim Mathis: Stage 1 Bare FR4 as from supplier 4 coupons Stage 2 Solder resist applied and cured 4 coupons Stage 3 Application of SMT adhesive side 1 4 coupons Stage 4 Application of Paste, reflow 4 coupons Stage 5 Application of flux and wave soldered 4 coupons Stage 6 Application of Paste, components mounted, reflow 4 coupons Stage 7 Application of flux and components mountd, wave soldered 4 coupons If applicable, then: Stage 8 Boards are cleaned 4 coupons Stage 9 Conformal Coating applied and cured 4 coupons Obviously, the manufacturing process and therefore the number of test coupons involved, will vary from customer to customer. If only a fully assembled final sample is tested, then any process problems cannot be so easily identified. The testing that can now be provided: * Very low test leakage current detection ( <10-12 A) providing far more sensitive testing. * Each test site is able to be monitored at 10 minute intervals. This gives far greater opportunity to detect Electro-Migration in the form of Dendrites. * It permits CAF influences to be detected. * Dendrites may be preserved to facilitate subsequent and separate failure analysis. * Varying test voltages may be used We consider that, because of the low current test capability, reverse bias is unnecessary as it does not properly reflect actual assembly operating conditions. From this testing, the synergistic effect of each process step can be seen in the final evaluation. For example low SIR might come from a problem in the bulk FR4 in Stage 1, or may be introduced by a contaminated cleaning tank in Stage 8. Or low SIR could indicate an adverse and unpredictable reaction between the solder resist and solder flux. I am sure that test specialists such as: CSL, Trace, Robisan, in the USA; NPL in the UK; IVF in Sweden etc., will be willing and able to conduct this work. Graham Naisbitt Concoat Ltd Email: [log in to unmask] Alasan House, Albany Park Tel: +44 (0)1276 691100 Camberley, Surrey GU15 2PL UK Fax: +44 (0)1276 691227 -----Original Message----- From: TechNet On Behalf Of Bryan Woods Sent: Thursday, October 23, 1997 5:41 PM To: [log in to unmask] Subject: [TN] Wave soldering SMD actives Because of top side board space constraints, we are considering wave soldering some active SMD components (SOICs, etc.) on the bottom side of our boards for the first time. They would potentially be glued onto the board via an epoxy dispenser with screened solder paste and then run through our wave solder. I am very interested to hear what problems/solutions were encountered by others trying to go down this path. Issues of specific interest to me are: Nitrogen environment or free air? Thieving pads? Fluxes being used (no clean/water wash)? What kind of pitches/sizes of components? Thermal degradation of components? Any else? Thanks in advance. Bryan Woods Manufacturing Engineer Parker Hannifin | Phone: (707)584-2542 Compumotor Division | Toll free: (800) 358-9068, ext 2542 5500 Business Park Drive | FAX: (707)584-8015 Rohnert Park,CA 94928 | Email: [log in to unmask] | Web site: http:\\www.compumotor.com ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ############################################################## ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ##############################################################