Aluminum Alloy Package for Microwave Amplifier

A study of hermetic sealing methods for a general-use Al alloy package for a microwave amplifier with increased output power and lighter weight is described. To solder the glass insulated terminals to the Al alloy case hermetically, using commercial Pb-Sn solder, we propose a unique "local plating method"--Ni plating inside the terminal holes of the case. In this method, Ni plating 2-4/um thick is necessary to solder the terminal well. Laser welding of Al alloy was accomplished by adding Si in the weld zone by laser welding Al-Si alloy foil together with the Al alloy to strengthen the weld metal at the high temperature. Good hermetic sealing between the case and the cover by laser welding is obtained using foil with thickness from 300 to 500 um, and Si content from 7.0 to 13.0 wt%. The Al alloy package hermetically sealed in this way has high reliability. Leakage is unchanged after various reliability tests in accordance with MIL-STD-202 and leak rates remained constant at 10^-9atm * cm³/s.