Laser Metal Bonding (LMB) - Low Impact Joining of Thin Aluminum Foil to PERC and TOPCon Rear Side Surfaces

We present the design, implementation and optimization of laser metal bonding (LMB), a new approach for joining thin aluminum foils and back surfaces of solar cells with a focus on low impact on the semiconductor and good adhesion. We succeeded in establishing an expulsion free laser process to create highly adhesive joints on dielectric layers without penetrating them. Electrically conducting contacts have been successfully created on PERC solar cells via LMB on locally opened nitride layers, achieving efficiencies up to 20.5 %.