Abstract: Soldering flux and solder paste compositions which are non-acidic, low-residue, and non-corrosive, leaving no substantial residue after soldering without a subsequent cleaning process and yet exhibiting excellent solderability are disclosed. The compositions comprise (A) at least one compound which generates a peroxide by decomposition or oxidation when subjected to heating, and (B) at least one ester from an inorganic or organic acid which generates an acid by decomposition in the presence of compound (A). They are particularly advantageous for eliminating the cleaning process with a solvent such as Flon to solve the ozone layer destruction problem and for improving the performance of the in-circuit test for printed-circuit boards after soldering.

Abstract: A soldering flux includes at least one acid component and at least one ester component. The acid component is selected from among dibasic carboxylic acid, hydroxycarboxylic acid and keto carboxylic acid. The ester component is selected from among phosphoric ester, phosphorous ester and hypophosphite ester.