FLUXLESS SOLDERING PROCESS

A method of fluxlessly joining members e.g. solder pads, having relatively low melting materials is described. The members to be joined are exposed in a non-oxydising atmosphere to ion beam radiation of sufficient intensify and for a time sufficiently long to cause cleaning of the low melting materials by removal of contaminating surface oxide layers. The members are then placed into juxtaposition with each other and are heated for a time sufficient to cause reflow of the low melting materials which upon cooling joins said members. The members may be heated conventionally or may be exposed again to an ion beam radiation to effect joining. In a second example, contacting members are cleaned and reflowed in a single step by exposure to an ion beam radiation. In the Figure an ion beam 28 impinges on solder pads 32 on a chip 30 and on matching solder pads 38 on a substrate 36. After cleaning the pads the chip 30 is flipped on to the substrate 36, (indicated by the arrow), and further heated, e.g. by further radiation, to effect joining by solder reflow.