Solder paste composition and welding method comprising the same reduce void fraction of the welding point and remove metal oxide at the welding point center at the same time

The disclosure provides a solder paste composition comprising: 100 parts by weight of metal powder, and 3 parts by weight to 18 parts by weight of organic mixture; wherein the organic mixture comprises a solvent, a thixotropic agent, and an organic acid in which the boiling point is smaller than the melting point of the metal powder. The disclosure additionally provides a welding method comprising steps of providing the solder paste composition between a substrate and an article to be soldered so as to form a composite structure; placing the composite structure in a chamber communicating with an acid gas; and melting the metal powder having the solder paste composition in order to solder the substrate and the article to be soldered. The solder paste composition of the disclosure mainly breaks metal oxide film on the surface of the metal powder through the low boiling point organic acid to avoid the solder point from being continuously corroded by residual acidic material to reduce void fraction of the welding