Abstract: An electroless gold plating bath includes a water-soluble gold compound, a complexing agent, an aldehyde compound, and an amine compound represented by R1—NH—C2H4—NH—R2 or (CH2—NH—C2H4—NH—CH2)n—R4 (wherein R1 to R4 represent —OH, —CH3, —CH2OH, —C2H4OH, —CH2N(CH3)2, —CH2NH(CH2OH), —CH2NH(C2H4OH), —C2H4NH(CH2OH), —C2H4NH(C2H4OH), —CH2N(CH2OH)2, —CH2N(C2H4OH)2, —C2H4N(CH2OH)2 or —C2H4N(C2H4OH)2, and n is an integer of 1 to 4). The electroless gold plating can be carried out without corrosion of an underlying metal to be plated at a stable deposition rate. Because of the high deposition rate and the immersion and reduction types, thickening of a plated coating is possible in one solution and the color of the coating is not degraded to provide a good appearance while keeping a lemon yellow color inherent to gold.

Abstract: An electroless gold plating bath includes a water-soluble gold compound, a complexing agent, a formaldehyde metabisulfite adduct, and an amine compound represented by R1—NH—C2H4—NH—R2 or (CH2—NH—C2H4—NH—CH2)n—R4 (wherein R1 to R4 represent —OH, —CH3, —CH2OH, —C2H4OH, —CH2N(CH3)2, —CH2NH(CH2OH), —CH2NH(C2H4OH), —C2H4NH(CH2OH), —C2H4NH(C2H4OH), —CH2N(CH2OH)2, —CH2N(C2H4OH)2, —C2H4N(CH2OH)2 or —C2H4N(C2H4OH)2, and n is an integer of 1 to 4). A gold plated coating of a good appearance can be formed without causing a failure in appearance owing to the progress of intergranular corrosion in a nickel surface.

Abstract: Disclosed herein is a method for forming a displacement tin alloy plated film, on a copper or a copper alloy on a substrate, a tin alloy plated film containing at least one additive metal selected from silver, bismuth, palladium, indium, zinc and antimony, the method including the steps of: forming an under layer on the copper or copper alloy in a low temperature displacement tin alloy plating bath at a temperature of 10 to 50° C.; and forming an upper layer on the under layer in a high temperature tin alloy plating bath at a temperature of 40 to 80° C. to form the displacement tin alloy plated film formed of the under layer and the upper layer.

Abstract: An electroless gold plating bath includes a water-soluble gold compound, a completing agent, an aldehyde compound, and an amine compound represented by R1—NH—C2H4—NH—R2 or (CH2—NH—C2H4—NH—CH2)n—R4 (wherein R1 to R4 represent —OH, —CH3, —CH2OH, —C2H4OH, —CH2N(CH3)2, —CH2NH(CH2OH), CH2NH(C2H4OH), —C2H4NH(CH2OH), —C2H4NH(C2H4OH), —CH2N(CH2OH)2, —CH2N(C2H4OH)2, —C2H4N(CH2OH)2 or —C2H4N(C2H4OH)2, and n is an integer of 1 to 4). The electroless gold plating can be carried out without corrosion of an underlying metal to be plated at a stable deposition rate. Because of the high deposition rate and the immersion and reduction types, thickening of a plated coating is possible in one solution and the color of the coating is not degraded to provide a good appearance while keeping a lemon yellow color inherent to gold.

Abstract: An electroless gold plating bath includes a water-soluble gold compound, a complexing agent, a formaldehyde metabisulfite adduct, and an amine compound represented by R1—NH—C2H4—NH—R2 or (CH2—NH—C2H4—NH—CH2)n—R4 (wherein R1 to R4 represent —OH, —CH3, —CH2OH, —C2H4OH, —CH2N(CH3)2, —CH2NH(CH2OH), —CH2NH(C2H4OH), —C2H4NH(CH2OH), —C2H4NH(C2H4OH), —CH2N(CH2OH)2, —CH2N(C2H4OH)2, —C2H4N(CH2OH)2 or —C2H4N(C2H4OH)2, and n is an integer of 1 to 4). A gold plated coating of a good appearance can be formed without causing a failure in appearance owing to the progress of intergranular corrosion in a nickel surface.

Abstract: To an electroless nickel plating solution comprising a water-soluble nickel salt, a reducing agent, and a complexing agent is added a polythionate or dithionite. The invention also provides a high-build electroless gold plating method comprising the steps of immersing a workpiece in the electroless nickel plating bath, thereby chemically depositing a nickel coating on the workpiece, and immersing the nickel-plated workpiece in an electroless gold plating bath, thereby chemically depositing a gold coating on the workpiece.

Abstract: In electroless or electric tin, lead or tin-lead alloy plating solution which may contain copper, the concentration of a metal ion component selected from divalent tin ion, lead ion, and copper ion is quantitatively determined by taking a sample from the solution, adding a chemical agent, for example, an oxidizing agent to the sample, thereby causing the selected metal ion to develop its color, measuring the absorbance of the sample due to the metal ion by colorimetry, and determining the concentration from the absorbance. A choice of chemical agent depends on a particular metal ion on analysis. When the solution contains more than one metal ion, correction is made by repeating the process using another chemical agent.

Abstract: A tin or tin-lead alloy electroless plating bath comprising (A) a stannous salt or a mixture of a stannous salt and a lead salt, (B) an acid, (C) thiourea or a thiourea derivative, and (D) a reducing agent is improved by adding (E) a nonionic surfactant and optionally, (F) a cationic surfactant, a nitrogenous heterocyclic compound or a derivative thereof, or alternatively by adding (G) an ammonium or quaternary ammonium ion. From the bath, uniform films of fine grains will chemically deposit on fine pitch printed wiring boards intended for SMT.

Abstract: The invention provides a process for electroless plating tin, lead or tin-lead alloy on copper or copper alloy using an electroless plating bath containing a water soluble tin and/or lead salt, an acid capable of dissolving the salts, and a complexing agent. The tin and/or lead content in the bath is maintained high enough to chemically deposit thick films by replenishing the tin and/or lead salt in proportion to an increase in concentration of copper ion dissolving out in the bath. Also provided is an electroless tin, lead or tin-lead alloy plating process in which a water soluble copper salt is added to a fresh bath.

Abstract: For replenishing a metal ion to a plating bath, a soluble electrode of the same type of metal as in the bath and a counter electrode of a metal material having a nobler standard electrode potential than the soluble electrode are immersed in the bath. Electricity is conducted between the soluble electrode and the counter electrode, thereby dissolving the soluble electrode to replenish an ion of the metal of the soluble electrode to the bath. The potential of the counter electrode is measured using a reference electrode of the same metal as the soluble electrode. The quantity of electricity is controlled such that the measured potential may not be negative with respect to the reference electrode, thereby preventing deposition of the dissolving metal ion on the counter electrode while ensuring a high rate of metal ion dissolution.