Dear Matthew, Thank you for your advice about the conductive epoxy. Why do we want transfer from Ag/Pd capacitor or solder/pure Tin capacitor? Because (1) our supplier from Japan will stop supplying the Ag/Pd capacitor and it is very difficult to get Ag/Pd capacitor at different value. It is even more difficult to get Ag/Pd resistor; (2) Ag/Pd terminal is expensive. Our product is optoelectronic component, it is quite cheap about a few dollar. We have very long history to attach Ag/Pd capacitor using conductive epoxy. it is without any problem. The solder/Tin termination capacitor/resistor attached with some conductive experience resistance increase when exposure to 85/85 test. But we do find one epoxy can pass 1000 hrs 85/85 test with very small resistance change with encapsulant and without encapsulant. Your advice is very correct about stencil printing and dispensing. The printing quality is better than that using dispensing. The 4 mil stencil was used. When I am doing the process evaluation about the dispensing, I face a lot of problem such as tailing, insufficient coverage of epoxy and no fillet. After the unit was encapsulated, it go trough 3 times IR reflow, then the resistance increase has been found. Best Regards Eden Chen ______________________________ Reply Separator _________________________________ Subject: Re: [TN] Conductive Epoxy for Solder termination Author: Non-HP-MPARK ([log in to unmask]) at HP-Singapore,mimegw51 Date: 6/16/98 6:03 AM Dear Dr. EC, A successful implementation of electrically conductive epoxies for SMT application is more than understanding those issues you stated. And it is NOT definitely a replacement for tin/lead solderpaste as some mfg of conductive epoxies claim. It is not very difficult to form fillet with the epoxy. Simply epoxies DO NOT form fillets and wet. I performed a few sample tests one/two years ago when one conductive epoxy mfg claimed it prints like any other solderpaste and it is a replacement for solderpaste. I concluded that some fundamental issues have to be addressed to make electrically conductive epoxies useful in a SMT manufacturing environment, - impractical storage/shipping temp, -70'c to-40'c - too suceptable to moisure and dry out too quickly - do not adhere good to tin/lead surface. A test revealed it adhered well to bare copper and solder mask surfaces. It is proper to have a different metallic finish for SMT component soldering terminals and board surface than tin/lead. - redesigning board layout for epoxy application such as pad sizes, conductor space req's etc... - redesigning component soldering terminals for epoxy application. - poor performance of printability of epoxy - reworkability To answer your questions, it is vital to provide only an exact amount of epoxy for component terminal area. A typical printed thickness of epoxy should be at 0.1mm. That is why I believe a dispensing option is not suitable. It won't provide a controlled coverage of epoxy for soldering terminals. There are too many parameter variations to control such as epoxy consistency, dot size, dot height, placement pressure etc... regards Matthew NII-Norsat International Inc. >>> "by Dr. Eden Chen XianSong" <[log in to unmask]> June 14, 1998 8:35 pm >>> Dear Sir, Some silver-filled conductive epoxies in the market claim to be solder replacement, but successful use of these material require a very good understanding of the epoxies properties, the process and CTE mismatch. The epoxy can be deposited to the pad by stencil printing or dispensing, Dispensing process has the tailing problem which can cause short for 0402 chip resistor/capacitor. It is very difficult to form the fillet for epoxy, because the epoxy may have a gap between the side of chip resistor/capacitor and dot peak of epoxy. How much should the placement force be applied and how big should the dot size for 0402 resistor/capacitor? I like to discuss the above-mentioned issue in the TECHNET Eden ################################################################ TechNet E-Mail Forum 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://jefry.ipc.org/forum.htm) for additional information. 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For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################ ################################################################ TechNet E-Mail Forum 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://jefry.ipc.org/forum.htm) for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################