Thermal Conductive Bonding, Inc.
Given the setbacks in bonding with indium, TCB invented, engineered, and introduced a bonding system for sputtering targets that overcomes much of the disadvantages of indium bonding. Primarily, we can bond at a low temperature and lock in the zero-stress point at 50C; thereby limiting the amount of growth and stress on the materials when cooled to ambient temperatures. Due to the nature of the elastomer, its elasticity is such that the bond can absorb the expansion differential when the assembly is heated in operation, keeping the assembly flat and reducing the pass through of stresses into the target material.
There are some concessions that need to be made to achieve all of this, and that is the elastomer is less thermally/electrically conductive and requires a more rigid backing plate. We have found in our experiments that the advantages outweigh the disadvantages of weaker conductivity. Although the bond may run slightly hotter, there is no effect on the sputtered films when compared to an indium bond. In addition, the elastomer has a higher operating temperature, 250C, however an elastomer bond will only outperform an indium bond by approximately 25% with regards to a power increase.
All TCB elastomers are in-house formulated, independently lab tested, and meet NASA criteria for TML for suitability in hi-vacuum applications. Each process step is meticulously followed and inspected to assure compliance with our internal specifications and test procedures.