RusTec has developed a process of manufacturing of thermoelectric material dices on the basis of bismuth telluride; the method does not include the step when slices are cut into dices which previously resulted in a significant loss of thermoelectric material due to the cut width and additional manhours spent on waxing/dewaxing of slices. The so-called Rod Technology is based on the following: first, rods of the required diameter are produced through melting or extrusion; then the lateral surface of a rod is coated with the specifically designed epoxy-based chemical compound which permits to coat dice ends with metal diffusion barriers after the coated rods are sliced into dices of the required height.

The advantages of the technology:

-  Easiness of placement of dices with round shape;

-  Feasibility of using circular-section dices in cases where the use of rectangular-section dices would have made it difficult to properly position cube-shaped dices;

-  Protection (by coating) of dice lateral surface which precludes the adverse events such as electrical bridges, penetration of solder in semiconductor due to lateral surface solder acceptance during module soldering.

Technology Specification

-  Dice diameter: 1.4 – 10 mm.

-  Dice height: 0.2 – 10 mm.

-  Lateral surface protection: galvanic deposited epoxy composition, 10-30 micron, operating temperature: -50...+280 °C.

-  Diffusion barrier: chemical deposition of nickel-based alloys; 7±2  micron thick; adhesion of not less than 1 kg/mm².

-  Solderable layer: 5 micron Sn (+1 % Bi) or 0.1-0.2 micron gold flashing.