A low-cost high-density substrate technology for wireless-related applications

We have developed a thin-film on modified ceramic (TFoMC) technology in this work to achieve high-density, high-accuracy and high-uniformity substrate technology for RF-related applications. Integrated passive devices (IPDs), including capacitors, inductors, band-pass filters and baluns, were realized based on the proposed TFoMC technology. The IPD characterization results were similar to the HFSS simulation results, and demonstrated good in-substrate uniformity. A WLAN front-end module (FEM) was designed and realized by integrating IPDs, power amplifier die and switch die on the modified ceramic substrate. The FEM exhibited a 31-dB signal gain in the pass band, and passed the spectrum mask specifications and error vector magnitude requirements under 802.11b/g modulations. The characterization results demonstrated the excellent RF performance of TFoMC substrate. Following JEDEC standards, thermal shock, high-temperature storage, unbiased damp heat and unbiased autoclave measurements were carried out to evaluate the reliability of the TFoMC substrate. The IPDs exhibited no performance degradation after the moisture and thermal stress tests indicating the excellent substrate reliability. IPDs fabricated on different types of silicon substrates using the same thin-film process were also characterized. The performance and cost of different substrate technologies for RF-related applications were evaluated.