New LTCC Package for Microwave Application

摘要

We have developed a new LTCC (Low Temperature Cofired Ceramic) package with copper conductor which is adequate for microwave applications. The dielectric constant of the material is 6.0, and the loss tangent is 0.0029 at 30 GHz. The coefficient of thermal expansion is 7.5 ppm/°C in the range of 40～300°C. The fine leak rate by helium gas is less than 1 x 10~(-9) Pa m~3/s. Sheet resistance of the copper conductor is less than 3m Ω/□. The insertion loss of the LTCC substrate with microstrip line is -0.35dB/cm at 30 GHz which is a half of that of alumina. Multilayered LTCC package plated with nickel and gold were prepared, and reliabilities of the package were evaluated. The copper sealing pattern was formed by cofiring process. The package was sealed with an Alloy 42 lid by gold-tin eutectic alloy. The fine leak rate by helium gas of the package was less than 5 x 10~(-9) Pa m~3/s and showed no change after temperature cycle test (1000 cycles at ― 55～125°C). The new LTCC package has excellent electric characteristics and high reliability, and is adequate for microwave applications at frequencies ranging from 1GHz to 30GHz.