Interconnection of germanium photovoltaic cells using vapor phase soldering technology

The solar panels (SP) are the main energy source especially for the new generation of nanosatelit. Having an area of around 100mm2, SP are obtained by soldering photovoltaic (PV) cells on the surface of a dedicated printed circuit board (PCB). The power and voltage values generated have been obtained by the interconnection structures of PV cells used to realize SP. The soldering process could be manually or reflow type, when are used surface mounted technologies (SMT). The process constrains are generated by the PV cells’ structure and materials. In this paper the authors proposed vapor phase soldering (VPS) technology for assembling PV cells based on germanium, having maximum 0.5mm thickness, in order to avoid the mechanical damages which appear in the manual soldering process and to provide uniform heating with the peak temperature less than 150ºC. The novelty of the proposal consists in realizing the control of VPS process in order to obtain a precise and repeatable thermal profile (TP) below VPS liquid boiling point. Based on the experiments already done, theoretical studies and experiments regarding the heat transfer in VPS process there will be developed, in order to define a technology for assembling SP module with PV cells soldered into one step.