To provide solder paste which can prevent undesirable accidents, such as the falling-off or positional shift of components in a reflow soldering operation, and further to provide a soldering method using the same solder paste.
The solder paste to be used for joining electronic components to a substrate by soldering is composed by mixing a thermosetting flux and metallic compositions including powder of the solder. The thermosetting flux contains a thermosetting resin and a solid resin, which has such a property that the solid resin is solid at an ordinary temperature, and becomes liquid by being heated, and has a softening temperature higher than the liquidus line of the solder. The thermosetting flux further has an active effect for removing the oxide film of the solder. By this composition, in the reflow soldering operation of the substrate 1 having electronic components joined on its both faces, the solid resin composition can keep the solid state without being liquefied, and as a result, the undesirable accidents, such as the falling-off or positional shift of the joined components, due to the fluidization of a resin reinforcing portion 5b covering the solder joining portion 5 of the already joined electronic components 4 can be prevented.
SAKAI TADAHIKO
YOSHINAGA SEIICHI
Tomoyasu Sakaguchi
Hiroki Naito