Embedded capacitor technology can increase silicon packing efficiency, improve electrical performance, and reduce assembly cost compared with traditional discrete capacitor technology. Developing a suitable material that satisfies electrical, reliability, and processing requirements is one of the major challenges of incorporating capacitors into a printed wiring board (PWB). Polymer-ceramic composites have been of great interest as embedded capacitor material because they combine the processability of polymers with the high dielectric constant of ceramics. A novel nanostructure polymer-ceramic composite with a very high dielectric constant ( r ϳ110, a new record for the highest reported r value of a nanocomposite) was developed in this work. A high dielectric constant is obtained by increasing the dielectric constant of the epoxy matrix ( r Ͼ6) and using the combination of lead magnesium niobate-lead titanate (PMN-PT)/BaTiO 3 as the ceramic filler. This nanocomposite has a low curing temperature (Ͻ200°C); thus, it is multichip-module laminate (MCM-L) process-compatible. An embedded capacitor prototype with a capacitance density of 50 nF/cm 2 was manufactured using this nanocomposite and spin-coating technology. The effect of the composite microstructure on the effective dielectric constant was studied. This novel nanocomposite can be used for integral capacitors in PWBs.
For an ester‐type photosensitive polyimide precursor of low thermal expansion coefficient, the oxygen concentration in the curing process and the molecular weight of the polyimide precursor were found to control the properties of the polyimide. The effects of these factors on the thermal expansion coefficient, tensile strength, and modulus of polyimide film were investigated. Based on these results, a photosensitive polyimide with low thermal expansion coefficient, called the PIMEL TL‐series, was developed. Crack and delamination free multilayers were successfully achieved using this newly developed product.
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