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H2S Susceptibility of Au plated Micro Circuit Frames Using Static Intercept Packaging

Micro circuit technology parts are susceptible to degradation by atmospheric contamination. This contamination causes high contact resistance and unsolderable surfaces. In advanced stages the surfaces will show visual discoloration and corrosion products.

Intercept plastics (developed by Lucent Technologies to prevent static and corrosion damage to products) was tested with standard low density polyethylene to assess the protective performance of both polymers to compare the effectiveness of these plastics as a primary packaging material for DIP and SMT packages. In order to evaluate the relative protection capability of the Intercept plastic product to standard polyethylene plastic bags the following tests were performed.

Eight SMT packages were obtained. The lead frames were constructed from 42 alloy which is predominantly copper, with small amounts of zinc and  tin. The frames were plated with a nickel strike and finished with a gold plate. A standard IC package was than manufactured on the frames. The frames were kept in the as manufactured axial position so as not to produce any stresses in the plating which could unduly enhance corrosion.

Two IC=s were heat sealed in two Static Intercept 0.002" thick and two Low Density Poly bags 0.003" thick. The heat sealed bags containing the samples were placed in a pyrex corrosive gas chamber. The chamber contained 5 PPM of H2S. Temperature was maintained between 20 and 22 degrees C. Humidity was maintained at 100% by heating a water source of deionized water to 30 degrees C. and allowing condensate to form.

Samples were pulled out of the chamber at 1 month and 2 months.

EDXA analysis confirms Cu2S formation on the discolored areas shown on figure 1.

In depth analysis was not performed on the samples since this is considered a qualitative, not quantitative test of the Intercept technology performance relative to standard packaging.

Conclusion:

The Intercept Technology provided superior protection from severe exposures to humid atmospheres containing high levels of gaseous sulfur. Environments such as used in this testing can be expected on shipments of equipment via oceanic transport to areas such as Pac Rim, China and South America. The use of Intercept technology for the protection of equipment destined to these areas should be considered.

 H2S Susceptibility Test – Gold Plate

1 Month Exposure	2 Month Exposure
2 mil Intercept Bag	2 mil Intercept Bag

1 Month Exposure	2 Month Exposure
3 mil Polyethylene Bag	3 mil Polyethylene Bag