Soldering process

Claim 1

A soldering process for connecting the contacts of a plurality of solar cells each having a contact on the underside thereof disposed along a first edge and a contact on the upper side thereof disposed along the edge opposite to such first edge, such cells forming groups of two or more parallel-connected solar cells with the underside contacts of the solar cells in each group being connected together and the upper side contacts of the solar cells in each such group also being connected together, such groups, moreover, being connected in series with each other by connecting the underside contacts of at least a first group with the upper side contacts of a second group, the process comprising, in combination, the steps of: a. applying a relatively soft solder having a layer thickness of approximately 30 micrometers to the surfaces of the contactmaking elements which are to be connected with the underside contacts of the solar cells of a first group and the upper side contacts of the solar cells of a second group, as a consequence of which parallel and series connections can be formed simultaneoUsly for the solar cells; b. applying a fluxing agent solution to the soldering areas of the contact-making elements; c. after evaporation of the solvent of the fluxing agent solution, placing the solar cells and the contact-making elements together so that the soldering areas of the contactmaking elements cover the underside contacts of the solar cells of the first group and the upper side contacts of the solar cells of the second group, respectively, and securing them against displacement in a soldering device; d. thereafter, inserting the soldering device with the solar cells and the contact-making elements thereon into a soldering bath maintained at approximately 240* C. to such a depth that the solder comes into contact with only the underside of the soldering device thereby to transfer to the soldering areas terminal energy required to solder the contacts of the solar cells; and e. placing the soldered solar cells into an ultrasonic bath including a fluxing solvent for removing fluxing agent residues.