Direct glassing of silicon space solar cells: approach and manufacturing experiences

An investigation of direct glassing, using electrostatic forces to fix CMZ coverglasses to silicon solar cells is described. The aim is to establish direct glassing as an economic production alternative to the conventional glassing techniques. The milestones of the investigations are: fit of CMZ glass to direct glassing demands; evaluation of boundary conditions concerning cell and cover; optimization of the bonding parameters-temperature, pressure, time, and voltage-for different cell sizes, especially for 2×4 cm² solar cells; design and manufacture of a prototype bonding machine; execution of direct glassing trials of 2×4 cm² solar cells with constant parameter set to evaluate yield; definition of quality criteria to weight the process; performance of environmental tests (irradiation, thermal cycling,) as space qualification; and economic and technical assessment of the direct glassing against more conventional methods