Koichiro Nakase

Signal Integrity and Power Integrity Properties of FCBGA Based on Ultra-Thin, High-Density Packaging Substrate

We developed an ultra-thin high-density packaging substrate, called an MLTS (multi-layer thin substrate), that consists only of build-up layers without a core laminate. We evaluated the signal integrity and power integrity properties of a flip-chip ball grid array (FCBGA) based on the MLTS, along with those of an identically functioning FCBGA based on conventional build-up printed wiring board (PWB). Our signal-integrity simulation clearly showed that the return loss (S11) of the MLTS was 6 dB smaller than that of the PWB in the frequency range from 1 to 10 GHz. In our power-integrity simulation, the noise transmitted inside the MLTS was 13 dB smaller than that inside the PWB at 10 GHz. These results indicate that the MLTS has considerable advantages over a conventional build-up PWB, especially for operation in the GHz range.

Narrow sheet design with shielding metal walls of two-dimensional communication

In a sheet design of the two-dimensional communication (2DC) system, it is desirable to add shielding metal walls to the edges of the sheet in order to suppress electromagnetic (EM) radiation. Then, the sheet medium has the cutoff frequency similar to a rectangular waveguide, which can be determined from the width of the sheet. If the carrier frequency is less than the cutoff frequency, the power cannot be transmitted through the sheet. This paper proposes a new narrow 2DC sheet with the cutoff frequency lower than a conventional 2DC sheet with metal walls. Actually, the lower cutoff frequency can be obtained by forming a special metal pattern near the shielded walls. This can make the sheet width wider equivalently (electrical length longer). Then EM wave can propagate through a narrower sheet. Measurements using fabricated prototypes clearly show the advantage of the proposed structure.