Product Briefing Outline: Sony Chemical & Information Device Corporation has commercialized and commenced full-scale mass production of the SP100 Series, Solar Cell Conductive Film for photovoltaic modules. The SP100 Series has been evaluated by the Consortium for Development and Assessment of Highly-reliable Photovoltaic Modules of the Advanced Industrial Science and Technology (AIST) and modules using the SP100 Series have passed high-temperature / high-humidity testing (85°C / 85%RH, 1000 hours) and temperature cycle testing (-40°C – 85°C, 200 cycles) regulated by IEC61215, an international module accreditation standard, and it has been verified that the product provides the long-term conduction reliability required by photovoltaic modules.
Problem: Solar cell strings, which compose photovoltaic modules, are generally bonded by soldering which requires heating to a temperature of 200°C or higher. Differences in the thermal and mechanical characteristics of the silicon used in cells and metal ribbon (generally solder-coated copper wire) can cause residual stress around the bonding area, leading to problems such as cell breakage after bonding.
Solution: The SP100 Series is a film-type conductive bonding material that bonds the solar cell with the metal ribbon that acts as a transmission line for electricity generated by the cell and, compared with conventional soldering (200°C or more), is capable of low-temperature bonding at 180 C, enabling significant reductions in residual stress after bonding on cells, thereby contributing to improved yield during module production. In addition, the SP100 Series is also capable of bonding thin cells (approximately 150 meta-m) that are weaker against thermal stress during soldering than standard thick cells. The SP100 Series is not only features a bonding mechanism that renders the melting of solder unnecessary, but also is a bonding material with minimal impact on the environment thanks to the absence of constituents such as flux and Pb. This bonding material is compatible with Pb-free solder-type ribbons and contributes to the production of modules that are even more environmentally-friendly.
Applications: Bonding and tabbing c-Si solar cells. It is capable of bonding thin cells (approximately 150 meta-m)
Platform: The SP100 Series is a bonding material that uses Anisotropic Conductive Film (ACF) technology utilized for applications such as the mounting of a driver IC on an LCD panel. The SP100 series makes stable contact between the solar cell and metal ribbon by heating and pressurizing conductive particles distributed evenly into the epoxy-type resin, resulting in heat-curing of the resin simultaneously, so the material provides reliable conduction equivalent to that provided by soldering. In addition, because the material is a film type, there is no dispersal of material to the light receiving area, resulting in a module with better aesthetically finished bonded areas. Moreover, the material is suitable for narrow areas, capable of usage at widths as small as approximately 1mm, making it possible to ensure a wide light-receiving area by reducing the busbar width.
Availability: September 2010 onwards.