At 02:39 13-02-98 -0800, Scott wrote:
>I have noticed that, on occasion, RAM with gold contacts isn't recognized
>by a system that has tin RAM-socket contacts. As I am not aware of any
>basic reactive property between gold and tin (though I do not thoroughly
>recall all of my chemistry instruction), this interaction puzzles me. My
>question is: Why would, or how could, such a problem arise?


Here's a quote from "The Intel Motherboard General FAQ" at
<http://developer.intel.com/design/motherbd/genmbfaq.htm#9A>:

Will gold plated SIMMs work with my Intel motherboard?
Most Intel motherboards use tin-lead SIMM sockets and Intel recommends
NOT mixing dissimilar metals in your memory solution. Studies show that
fretting occurs when tin comes in pressure contact with gold or any
other metal. Tin debris will transfer to the gold surface and oxidize.
Continued transfer will build up an oxide film layer. Tin surfaces
always have a natural oxide. Despite this, electrical contact is easily
made between two tin surfaces. Oxides on both soft surfaces will bend
and break, ensuring contact. The resistance of the oxidation layer
builds up over time when one surface is hard. Increasing the contact
resistance will ultimately result in memory failures.
Source: Edward Bock, AMP P316-90, Mateability of Tin to Gold, Palladium,
and Silver.

Regards,
Bill


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