Organic compounds -- part of the class 532-570 series – Organic compounds – Heavy metal containing
Reexamination Certificate
2000-05-11
2001-06-05
Nazario-Gonzalez, Porfirio (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heavy metal containing
Reexamination Certificate
active
06242624
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to methods for making akanol- or alkane-sulfone plumbates used for lead plating and solder plating applications, and relates in particular to a method for making alkanol- or alkane-sulfone plumbates using lead oxide compounds as feed material, which have been regarded as difficult to dissolve in alkanol-sulfonic acid or alkane-sulfonic acid.
2. Description of the Related Art
For work involving lead plating and solder plating containing lead, acidic plating solutions based on alkanol-sulfonic acid or alkane-sulfonic acid are used. The alkanol-sulfonic or alkane-sulfonic plumbates are usually used as source of lead in such cases.
Conventionally, alkanol-sulfonic or alkane-sulfonic plumbates, in particular low &agr;-rays radiation alkanol-sulfonic or alkane-sulfonic plumbates are generally made by reacting alkanol-sulfonic acid or alkane-sulfonic acid on metallic lead. However, it is desirable to make such materials by using naturally existing lead oxides.
Particularly, it is known in recent years that a-rays radiation emitted from lead contained in soldered products causes malfunction of electronic devices. Since then, alkanol-sulfonic or alkane-sulfonic plumbates have been made by using materials of low &agr;-rays radiation lead oxide compounds. However, the volume of production of low radiation lead compounds is relatively small, and the production is tight for supplying thereto to satisfy the demand.
On the other hand, lead oxide such as Pb
3
O
4
and PbO
2
are difficult to dissolve in alkanol-sulfonic acid and alkane-sulfonic acid, and they have not been considered as feed materials for making alkanol-sulfonic or alkane-sulfonic plumbates. However, as the availability of low-radiation lead compounds becomes more difficult, there has been required for a method of making low-radiation alkanol-sulfonic or alkane-sulfonic plumbates by using such lead oxide compounds.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method for make alkanol-sulfonic or alkane-sulfonic plumbates efficiently by improving the solubility of lead oxides such as Pb
3
O
4
and PbO
2
that are difficult to dissolve in alkanol-sulfonic acid or alkane-sulfonic acid.
The present method has been derived from inventors, intense examination of methods of dissolving lead oxide compounds that have been considered to be difficult to dissolve in alkanol-sulfonic or alkane-sulfonic acid. The present invention is based on a discovery by the inventors that the presence of phenol compounds plays a large role in dissolving the difficult-to-dissolve lead oxide compounds.
The present method is based on making alkanol-sulfonic or alkane-sulfonic plumbates by reacting difficult-to-dissolve lead oxide compound with a solution of alkanol-sulfonic or alkane-sulfonic acid, wherein a phenol compound is contained in the solution.
According to the present invention, it is easily possible to obtain alkanol-sulfonic or alkane-sulfonic plumbates efficiently from the difficult-to-dissolve lead oxide compounds at good yield.
In particular, by using the present method, it is possible to provide alkanol-sulfonic or alkane-sulfonic plumbates using the difficult-to-dissolve lead oxide compounds that have low &agr;-rays radiation property as feed material for solder plating. Thus the solder plating does not cause mulfunction of electron devices being soldered thereby.
The above and other objects, features, and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings which illustrate preferred embodiments of the present invention by way of example.
REFERENCES:
patent: 4116873 (1978-09-01), De Vries
patent: 4138351 (1979-02-01), Gilliams et al.
patent: 5162555 (1992-11-01), Remmers et al.
patent: 5618404 (1997-04-01), Okuhama et al.
Inoue Hiroaki
Ohno Kanji
Sekiguchi Akiji
Yoshioka Junichiro
Ebara Corporation
Nazario-Gonzalez Porfirio
Wenderoth , Lind & Ponack, L.L.P.
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