Leadframe material, encapsulated devices

Many devices, particularly high-power devices, require good heat dissipation to prevent the device from overheating and degrading the device performance. This has generally been obtained through the use of the proper leadframe material and/or the use of an encapsulant that has a high thermal conductivity (e.g.,... 

The moldability/1344 indicates the number of samples which, upon visual inspection, show flaws such as surface voids and rounded corners. Wire sweep and internal voids were determined by x-ray screening. These data may reflect a somewhat greater reactivity of the new molten resin. A further increase in resin viscosity may lead to wire sweep and other imperfections such as internal voids. A low resin bleed count supports this idea. (Resin bleed is resin material protruding onto leadframes beyond the rectangular shape of the resin mass). Linear devices were also molded over CuA leadframes at 175 and 150°C. The test yields were 98.0 and 98.8% respectively. These yields, as well as those obtained with A-42 leadframes (Table IV) are identical to the yeilds observed when commercial encapsulants are used. 

Figure 44 Package constructions used to evaluate the thermal transfer properties of the die attachment materials and substrates. TO-3 steel package is composed of steel case la, OFHC copper 2a, nickel film 3, soft solder 4a, and integrated circuit 5. TO-3 aluminium package is formed of aluminium header lb plated with nickel 3 on the top of which a silver-filled epoxy adhesive 4b is employed to bond the semiconductor device 5. The 24-lead CERDIP package is based on nickel-plated alumina substrate Ic with soft solder bonded silicon chips. In 40-lead plastic package, integrated circuits 5 are bonded to leadframes 2b by using silver-filled epoxy adhesive 4b and then encapsulated in moulding...

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