Jiajie Tang

Thermal management and testing of MCM with embedded chip in silicon substrate

In this paper the thermal management and testing of MCM with embedded chip in Si substrate was performed. Regarding the interconnection structure of the module, a benzocyclobutene (BCB) film covers the multichip modules as dielectric layer and Au soldered balls are utilized for multi-layer vertical interconnection. The thermal resistance and junction temperature are simulated and tested respectively. The results show that the thermal resistance is between 0.7degC/W and 1degC/W dependent on the use of a additional heat sink and the optimization of the parameters.

An MCM package process for 24GHz driver amplifier using photosensitive BCB

This paper presents a wafer-level microwave multichip module (MMCM) packaging process for 24GHz driver amplifier using photosensitive-Benzocyclobutene (photo-BCB) of 25µm. It is developed for multilayer interconnection of monolithic microwave integrated chip (MMIC). A 24GHz driver amplifier chip is embedded in a wet-etched trench on 4 inch lossy Si wafer and covered with a layer of BCB as dielectrics. Microstrip lines are fabricated with two layers of metal patterns to connect pads on MMIC with the test pads on MCM package in case of excessive loss. The interlayer connection resistance of this metal/BCB interconnection structure is tested with interconnection chain structures through Kelvin resistance measurement. The electrical characteristics of the package are also illustrated. The gain of the amplifier (S21) after packaging is more than 22dB from 21GHz to 26 GHz, and the S21 changes when packaged is less than 2 dB. The return loss S11 and S22 is less than −14.1dB and −17.3dB from 21GHz to 26GHz.

Fabrication of integrated microwave passive devices using thick BCB as dielectric at wafer level

This paper presents a wafer-level integration technology of micro/millimeter-wave integrated passive devices utilizing thick photo-BCB layer as dielectrics. Maximum three layers of metal and two layers of BCB are included in the specimen. Several kinds of RF integrated passive devices (IPDs) such as microwave resonator, low-pass filter (LPF) as well as bandpass filter, are fabricated on 25um/layer thick dielectrics. The RF transmission performances are measured on wafer. The S11 and S21 of the λ0/4 resonator are −0.774dB and −25.48dB, and the S11 and S21 of the stepped impedance resonator achieve −0.394dB and −27.42dB respectively at 24GHz. The cut-off frequency of the low pass filter is measured to be 13 GHz. The measured pass-band range of the BPF is 13.15GHz–13.75 GHz where the return loss is better than 11 dB. The pole point appears at 13.4GHz, and the return loss is 18.4dB.

Application of WLP with barrier trench structure in precision screen printing technology by glass frit

This paper reports on glass frit wafer bonding, which is a universally usable technology for Micro-Electronics Mechanical System (MEMS) wafer level encapsulation and packaging. The package process demonstrated from DEK-APi screen printing of glass frit, firing to wafer bonding by glass frit. However, the dimensions of glass frit after bonding are nonuniform and some frit widens to reach MEMS device, resulting in package failure. A new improved technology (Barrier trench technology, BTT) is developed. And in process of bonding, glass frit expanding in bonding force is resisted by the BTT. The uniformity of bonded glass frit dimension can be achieved. It allows hermetic sealing and a high process yield. And shear test, water test for the gross leak and fine leak test results fulfilled the corresponding MIL-STD.

A novel wafer-level double side packaging and its high frequency performance

In this paper, a wafer-level System-in-Packaging structure using through silicon via (TSV) for integration on both sides of the silicon wafer is presented. It is composed of BCB/metal multilayers, high-resistivity silicon substrate with TSV. To reduce the transmission loss in microwave frequency, not only the high-resistivity silicon is used, but also a special TSV structure with 6 grounded shielding vias around the core via are adopted. Microstrip line (MSL) is used to transmit high-frequency signal on package plane together with the low permittivity intermediate dielectric polymer, BCB. Descriptions on the interconnection structure and the fabrication process are included. The microwave measurement result of the MSL connected by TSVs is measured up to 35GHz. The results of both the simulation and the measurement are presented.