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Ag/Pd termination reflow soldering issues

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Ag/Pd termination reflow soldering issues | 18 April, 2007

I facing dewetting problem on Ag/Pd termination(chip component)during reflow process. The solder wetting is pull to terminal side and exhibits dewetting. Any one ever face the same problem and any solutions for the problem?

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Ag/Pd termination reflow soldering issues | 18 April, 2007

Good afternoon,

Huh. My sympathy. We have the same issue. Check this:

BR, Pavel

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Ag/Pd termination reflow soldering issues | 18 April, 2007

We have no experience with this termination, but in our notes => Silver palladium termination * AgPd-terminated capacitors are designed for conductive adhesion. Reflow or wave soldering is not recommended. [EPCOS Multilayer ceramic capacitors, Soldering directions, October 2006] * CONDUCTIVE EPOXY BONDING. Epoxy connection is a technically demanding technique. It requires the user to be familiar with the material requirements and reliability considerations of the conductor system chosen. ATC typically recommends either its gold over nickel barrier termination (termination style "CA") or its Ag/Pd alloy termination for compatibility with these applications.[Recommended Attachment Techniques for ATC Multilayer Chip Capacitors, Bulletin No. 201]. * To keep to external terminations of the resistors from separating from the body, compatible termination materials should be used. For example, if silver palladium [Ag-Pd] is used for the external terminations, Ag [2-2.5%] eutectic solder should be used. Please also carefully select the amount of solder used. [Precautions on the use of fixed resistors, Taiyo Yuden] * Silver palladium terminations are used for the large sizes 1812 and 2220 and for chips intended for conductive adhesion. This metallization improves the resistance of large chips to thermal shock. In case of conductive adhesion, the silver palladium metallization reduces susceptibility to corrosion. [Mounting Instructions for Chip Capacitors , Siemens Matsushita Components] * For application of the conductive paste bonding process, gold or silver-palladium is suitable as the electrode material. Accordingly, components using gold or silver-palladium electrodes are now in demand. Therefore, to meet the requirements for the conductive paste bonding process, Murata's newly developed components for automotive equipment use gold-plated electrodes. [Technical Trends > Eliminating and reducing Lead (Pb), Murata Electronics] * Hybrid assembly using conductive epoxy or wire bonding requires the use of silver palladium or gold terminations. Nickel barrier termination is not practical in these applications, as intermetallics will form between the dissimilar metals. The ESR will increase over time and may eventually break contact when exposed to temperature cycling. [Multilayer capacitors (MLC) Application Notes, Novacap]

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Ag/Pd termination reflow soldering issues | 19 April, 2007

I don't suggest using Pd/Ag or Ag/Pd terminated components unless you are forced to use them. You often see a line of demarcation that suggests a poorly wetted solder joint. I have had bad experiences with Pd/Ag terminated capacitors. Even when soldered using nitrogen and OA solder paste, you can still have trouble. Had perfectly looking joints with OA paste and nitrogen at 20ppm ROL. In shock and vibe testing, the Pd/Ag components failed due to cracking solder joints.

Dave is correct. Pd/Ag for silver epoxy. Sn/Pb or Sn for solder. The converse of Sn/Pb in silver epoxy and Pd/Ag in solder could give you a bad experience.


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Ag/Pd termination reflow soldering issues | 29 August, 2007

I am being asked to perform the same evaluation now with a Au/Pd termination varistor. We currently use a Pb/Sn process with an RMA flux. The manufacturer of the device recommends going to a 2% silver paste. What is the intended advantage with 2% silver, is it still to prevent the breakdown of the terminations, or is there another reason? Can we use this part with a tin/lead solder process? What are the long-term reliability concerns (we build long life high rel products)? If we change to the 2% silver paste for the rest of the assembly, and still use tin-lead terminations, what are the reliability concerns there? Are there any concerns? From past experience, what is the best way to proceed?

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