C.uyemura Co., Ltd.

Toyota Jidosha Kabushiki Kaisha

Hiroki Uchida

Masayuki Kiso

Tohru Kamitamari

Teruyuki Hotta

Motonobu Kubo

Toshiaki Shibata

Kazuki Yoshikawa

Shinji Kato

Yoshio Takagi

Takayuki Nakamura

Hitoshi Ozawa

Rumiko Susuki

Koichiro Shimizu

Tsuyoshi Uotani

Yosiomi Aoyagi

A solution for removing an aluminum oxide film from an aluminum or aluminum alloy surface, which includes a salt or oxide of a metal capable of substituting aluminum, a solubilizing agent for ions of the metal, and an alkali, and which has a pH of 10 to 13.5. The removing solution makes it possible to form a film of the metal derived from the metal salt or oxide contained in the removing solution by dissolving away the oxide film from the aluminum or aluminum alloy surface at a low temperature and a high speed while restraining, as securely as possible, erosion of the aluminum or aluminum alloy surface. The removing solution ensures that even in the case where the thickness of the aluminum or aluminum alloy basis material is very small, the aluminum or aluminum alloy surface can be activated while assuredly leaving the aluminum or aluminum alloy basis material.

Solution for removing aluminum oxide film and method for surface treatment of aluminum or aluminum alloy

A workpiece including aluminum or an aluminum alloy on a surface thereof is subjected to surface treatment including the steps of immersing in an acidic or alkaline aluminum oxide film-removing solution containing a salt or oxide of a metal capable of substitution with aluminum and forming a substituted metal layer and contained in the removing solution on a surface of the aluminum or aluminum alloy while removing an aluminum oxide film on aluminum or aluminum alloy surface, forming a substituted zinc film by zinc substitution treatment without removing the substituted metal layer, removing the substituted metal layer and substituted zinc film with an oxidizing liquid, and subjecting again to zinc substitution treatment, forming a substituted zinc film.

Method of surface treatment for aluminum or aluminum alloy

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.

Electroless nickel plating solution and method

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.

Analysis of tin, lead or tin-lead alloy plating solution

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.

Bath and method for the electroless plating of tin and tin-lead alloy

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.

Process for electroless plating tin, lead or tin-lead alloy

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.

Metal ion replenishment to plating bath

An Fe-P alloy film is electrodeposited on a workpiece in a bath comprising 20-80 g/l ferrous ion, 0.01-15 g/l hypophosphorous acid and/or a hypophosphite, and 0.05-5 g/l aluminum ion or a bath comprising 20-80 g/l ferrous ion and 0.01-20 g/l phosphorous acid and/or a phosphite, and optionally aluminum ion at 10.degree.-80.degree. C. and 0.5-30 A/dm.sup.2. There is obtained a crack-free alloy film having a P content of 0.1 to 9.9 wt %.

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Hirakata, Japan

Hiroki Uchida