Patent ID: 7435625
Filing Date: 2008-10-14
Classification: H01L

Abstract:
1. A method of encapsulating a semiconductor die, comprising: mounting the die on a lead-frame; adding particles of a filler to a resin, wherein the particles of the filler have a mix of filler sizes, and the particles of the filler are tightly packed within the resin; covering a portion of the die with a buffer region of a first dielectric constant and first loss tangent, wherein the buffer region includes the resin and the filler packed within the resin; placing the lead-frame with the die and buffer region in a mold suitable for plastic encapsulation, wherein the die and buffer region are located in a cavity in the mold; and placing a plastic encapsulant in the cavity of the mold to substantially fill the cavity of the mold around the lead frame, die and buffer region with a plastic material of a second dielectric constant and a second loss tangent, wherein at least the second dielectric constant is larger than the first dielectric constant or the second loss tangent is larger than the first loss tangent.