Publications Details
Solder bond applications in a piezoelectric sensor assembly
A procedure was developed to use solder technology in the assembly of a single-crystal quartz accelerometer. 87.5Au-12.5Ge (wt.%) solder films 0.5 {times} 10{sup {minus}6}, 1.0 {times} 10{sup {minus}6}, and 2.0 {times} 10{sup {minus}}6 m thick were formed by the electron beam deposition of individual layers of Au and Ge with thicknesses so that the bulk film composition equals the eutectic composition. Interdiffusion of the Au and Ge formed the solder; thermal-physical measurements showed the multilayer films to behave similarly to bulk 87.5Au-12.5Be solder in process thermal cycles. The 2.0 {times} 10{sup {minus}6}m thick quartz/Au-Ge/quartz bonds had an adhesive tensile strength of 17 {plus minus} 2 MPa. The strength increased to 29 {plus minus} 3 MPa and 27 {plus minus} 12 MPa after thermal shock and thermal cycle exposures respectively. The 1.0 {times} 10{sup {minus}6} m thick bonds exhibited strengths of 16 {plus minus} 3 MPa, 16 MPa and 15 {plus minus} 8 MPa in the as-fabricated, post-thermal shock, and post-thermal cycled samples, respectively. The 0.5 {times} 10{sup {minus}6} m joints produced a large degree of scatter in the strength values. Accelerometers assembled with the 2.0 {times} 10{sup {minus}6} m thick joints demonstrated a significant improvement in temperature performance as opposed to units fabricated with a polyimide adhesive. 8 refs., 12 figs., 8 tabs.