Liu Yunan,Fu Renli,Lu Ran,Shen Minhao,Hu Yunjia,Bei Guoping
Low Temperature Co-Fired Ceramic (LTCC) substrates used for microwave circuits typically must have low dielectric loss and low permittivity, as well as the ability to co-fire with metals. The dielectric properties of the microcrystalline glass materials used as the LTCC substrates are closely related to the crystallization process during sintering. This study focuses on the crystallization process of CaO-B 2 O 3 -SiO 2 microcrystalline glass. Wollastonite and pseudowollastonite seeds were used to control the degree of crystal precipitation. The phase composition and microstructure of each sample were analyzed in detail to elucidate the changes in the dielectric properties and sintering performance of the material. The addition of crystal seeds as nucleation sites promoted crystallization and led to the formation of quartz crystals. The sintered samples exhibited excellent dielectric properties: ε r < 4 at 18 GHz, tan δ < 0.0015, and Q × f > 12000 GHz. They have great potential as high-performance LTCC substrates.
A novel LTCC substrate manufacturing process based on 3D printing was investigated in this paper. Borosilicate glass-alumina substrates with controlled size and thickness were successfully manufactured using a self-developed dual-nozzle hybrid printing system. The printing parameters were carefully analyzed. The mechanical and dielectric properties of the printed substrate were examined. The results show that the printed substrates obtain smooth surface (Ra=0.92 μm), compact microstructure (relative density 93.7%), proper bending strength (156 mPa), and low dielectric constant and loss (Ɛr=6.2, =0.0055, at 3 GHz). All of those qualify the printed glass–ceramic substrates to be used as potential LTCC substrates in the microwave applications. The proposed method could simplify the traditional LTCC technology.
危险品化学品经营许可证（带存储）