Influence of Au finish thickness on air tightness of SiP RF module

Laser sealing welding was conducted on the Kovar frame and plate of SiP RF module with Au finish by LW600AE laser, the influence of Au finish thickness on the air tightness of SiP RF module was analyzed. The results show that the thickness of Au finish has a significant effect on the cracks of welded joint. With the increase of Au finish thickness, welding joint crack tendency increases and cracks increase. The Au element in the electroplating Au finish has lower melting point compared to other elements in Kovar alloy, and it is easy to form a variety of low melting point eutectic, which increases the tendency of cracking. When the thickness of Au finish is 0.1µm~0.3µm, the SiP RF module has the lowest leakage of 3.5×10
^-9
Pa • m
³
/s, and the air tightness is optimal.