RF Sensitivity of Multi Chip Package Development by Using Embedded Resistor in Package Substrate

摘要

Recently, mobile age is blooming and makes change of 21st century. Especially multi chip package –MCP- is located center position of this flash era. Moreover, radio frequency –RF- sensitivity determinesthe product quality and life, therefore we try to develop the RF sensitivity of MCP in wirelesscircumstance. In this study, MCP comprised NAND Flash memory, Mobile DRAM, and a substrate, wefocused on the substrate, changed substrate design and performance by using resistor embedded into 1layer of substrate. The purpose of adaption of embedded resistor is in order to control the slew rate ofsignal channel of DRAM. NiCr thin film was used for the resistor in substrate. NiCr material presentssuperior temperature coefficient of resistance –TCR- to thick film material. NiCr coated on Cu foil andthis foil laminated by conventional substrate manufacturing method. Embedded resistor applied onsignal line as 3 kinds; 1. Signal and signal strobe line by 50 Ohm, 2.Signal strobe line by 50 Ohm, and 3.Signal and signal strobe line by 20 Ohm. In case of 3, result showed 0.5 dBm increment of RF sensitivityin full strength mode, also we got the same performance at half strength mode. Embedded resistorformed substrate did not affect the reliability of MCP, from the results of reliability test; preconditioningtest, thermo-cyclic, temperature humidity, HAST, un-Bias HAST, and hot temperaturestorage test. This study showed signal waveform of DRAM is significantly effective in RF sensitivity forMCP. Passive component, resistor, made change of slew rate and revealed increase of sensitivity levelfinally.