Process for improving the solderability of electric circuit boards

Claim 1

A process for improving the solderability of a circuit board with conductor paths composed of copper, or copper alloy comprising the steps of A. first contacting conductor paths on a circuit board at least at areas to be soldered with a first solution for a time of from about 1 to 50 minutes, said first solution comprising on a 100 weight percent total weight basis. from about 2 to 20 weight percent of at least one dissolved non-ionic surfactant, from about 1 to 20 weight percent of at least one dissolved organic acid capable of producing a pH of not larger than 2 in water solution at a concentration of less than 50 grams per lite, and the balance up to 100 weight percent of any given such solution being water, B. first flushing the so first contacted areas with water for a period of time of at least about 12 seconds, C. secondly contacting the so first flushed areas with a second solution for a time of from about 2 to 10 minutes, said second solution comprising on a 100 weight percent total weight bases; from about 0.5 weight percent up to solution saturation of dissolved potassium persulfate sufficient added sulfuric acid to produce therein a pH of from about 1 to 4, from and including 0 up to about 0.5 weight percent dissolved phosphoric acid, and the balance up to 100 weight percent of any given such solution being water, D. secondly flushing the so secondly contacted areas with water for a period of time of at least about 10 seconds, E. thirdly contacting the so secondly flushed areas with a said first solution for a time of from about 1 to 5 minutes, F. thirdly flushing the so thirdly contacted areas with water for a period of time of at least about 10 seconds, and G. drying the so thirdly flushed areas in air.