| abstract |
Disclosed is a resin encapsulated semiconductor memory device comprising a semiconductor memory element, a package encapsulating the memory element and an alpha -rays shielding layer made from a water-resistant aromatic polyimide polymer, interposed between the memory element and the package, the aromatic polyimide polymer having a saturated water absorption rate of 1% or less. The polyimide polymer is exemplified as the polymer having the following recurring units: <IMAGE> wherein R is an aliphatic or aromatic group; R1 and R2 are independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or CF3; and R3 to R6 are independently a hydrogen atom, a halogen atom or an alkyl group having 1 to 4 carbon atoms. The disclosure is also concerned with resin encapsulated semiconductor devices in which the aromatic polyimide polymer of low water absorption is used as an insulating layer or passivation film. |