Semiconductor encapsulation, epoxy molding compounds

H. Suzuki, T. Moriuchi, and M. Aizawa, Low Mold Stress Epoxy Molding Compounds for Semiconductor Encapsulation, Nitto Electric Industrial Co., Ltd., 1979. 

In this paper we examine moisture sorption in an epoxy molding compound formulation used for semiconductor encapsulation. In particular, we will be concerned with moisture uptake as a function of relative humidity. The effects of temperature, sample thickness, and processing history will be systematically examined for a single commercially important material. 

For epoxy resins used in electronic applications, such as cresol epoxy no-volacs, more powerful polar aprotic solvents such as dioxane or dimethyl for-mamide (DMF) have been used to hydrolyze the difficult-to-hydrolyze HyCls, such as the abnormal chlorohydrins and the organically bound chlorides. The issue here is the inconsistency in results obtained by different methods (78). The presence of ionic hydrolyzable chlorides and total chlorides has been shown to affect electrical properties of epoxy molding compounds used in semiconductor encapsulation (85). For these applications, producers offer high purity grade epoxy resins with low ionic, hydrolyzable and total chloride contents. 

The success of plastic technology in achieving higher rdliability and mass production has led to wider applications in consumer products such as dectronic calculators, radios, televisions, and video recorders and in industrial products such as personal computers, office automation equipment, and computo Today, more tlum 80% of all semiconductor devices are encapsulated by epoxy molding compounds. 

This paper reports the results of a molecular-level investigation of the effects of flame retardant additives on the thermal dedompositlon of thermoset molding compounds used for encapsulation of IC devices, and their implications to the reliability of devices in molded plastic packages. In particular, semiconductor grade novolac epoxy and silicone-epoxy based resins and an electrical grade novolac epoxy formulation are compared. This work is an extension of a previous study of an epoxy encapsulant to flame retarded and non-flame retarded sample pairs of novolac epoxy and silicone-epoxy compounds. The results of this work are correlated with separate studies on device aglng2>3, where appropriate. 

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