Wire bond failures, encapsulated device

Epoxy molding compounds, used to encapsulate microelectronic devices, contain bromine to provide flame retardancy to the package. This bromine, typically added as tetrabromo bisphenol-A or its epoxy derivative, has been found to contain many hydrolyzable bromides. These bromides, along with the presence of chloride impurities, are detrimental to the life of the electronic component. Bromine especially has been suspected (proven) to cause wire bond failure when subjected to moisture and/or high temperatures. With the addition of a more thermally and hydrolytic stable bromine compound, flame retardancy does not have to be compromised to increase the device reliability. Stable brominated cresol epoxy novolac, when formulated into a microelectronic encapsulant, increases the reliability of the device without sacrificing any of the beneficial properties of present-day molding compounds. 

One of the most frequent failures encountered in the encapsulated micro devices is the so-called open circuit, which results from a break of the bonding wire between circuitry. The breakage is primarily due to corrosion. This is initiated by the impurities in epoxy resins, such as halogen, which upon exposure to heat and moisture generate a corrosive acid. 

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