Investigations of assembly properties of conductive layers in LTCC circuits

Investigations were aimed at evaluation of assembly properties of conductive layers cofired with LTCC substrates. The usefulness of these layers for low‐temperature soldering, joining with adhesives or for wire bonding was tested. The samples were manufactured from inks and glass‐ceramic sheets from three known LTCC producers. Different material combinations and various temperature‐time profiles of firing were used. The investigations were on: wettability measurements of conductive layers, evaluation of the layer resistance to dissolution, the deep analyses of particular wire bonding processes and the joint quality assessment at the time of welding, and the joint strength measurements. In the case of adhesive connections the resistance measurements of joints were applied. Scanning electron microscopy analyses were applied and metallographic examinations of sample cross‐sections were undertaken. The results of the investigations allowed us to choose films with appropriate bonding properties, and to explain the mechanism of joint failure.