JPS5882000A - Plating apparatus for plating copper-tin alloy - Google Patents

Abstract

PURPOSE:To enable the control of Ni concn. always, by mounting a mechanism for measuring absorbancy of a plating bath. CONSTITUTION:A liquid recirculating pipe 3 is provided to the plating tank 1 of a plating apparatus for plating a Cu-Sn alloy and a plating bath is recirculated through a pump 2. A bypass passage 4 is provided to said liquid recirculating pipe 3 and an apparatus for measuring absorbancy of the plating bath on the way thereof. In the apparatus 5, a light source 6 is formed to one side of an absorbancy measuring cell 8 connected to the bypass passage 4 and a light receiving part 7 to the other side thereof. Therefore, the variation of Ni concn. in the plating bath can be always measured and the control of Ni concn. is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plating apparatus for copper-tin alloy plating, and in particular, a new plating device for using a copper-tin alloy plating bath based on copper cyanide-alkaline stannate containing nickel salt. Copper cyanide-alkali stannate baths have been known for a long time as baths for obtaining copper-tin alloy metals, which are used in coating equipment. The bath consists of a bath whose basic components are alkali and alkali hydroxide, and bright plating is performed by adding these brighteners. It has been found that when a thiosifunate, a polyethyleneimine compound, and a nickel salt are combined as agents, an extremely excellent brightness can be obtained. However, in a copper cyanide-alkaline stannate plating bath, nickel salts have unique properties (depending on their concentration).
The alloy Ij7L composition of the deposited copper-tin alloy plating has a property of changing. For example, in a bath with the following basic composition, when the nickel concentration is 0 to 150 vpdl/L, the tin content is 40 to 45% and 300ssJ /4, the tin content is 35 T, and 750 td/L, the tin content is 25.
s and alloy composition change.

Sodium stannate 100Jj/A Copper cyanide 121/ Sodium cyanide
3011/L sodium hydroxide
Therefore, in the case of this plating, it is necessary to control the nickel concentration in order to always obtain the same quality plating, but with conventional plating equipment, it is not possible to adequately control the concentration, so it is necessary to always maintain stable quality. It was difficult to obtain.

This 'art was created from the situation of expanding the invention,
To provide a plating apparatus that is capable of constantly controlling nickel concentration (KToJ), and is characterized in that the plating apparatus is equipped with a device for measuring the absorbance of a plating bath.

The present inventors conducted detailed research on the above-mentioned copper-tin alloy plating bath containing nickel salts, and found that when nickel salts were added to this plating bath, the color of the bath changed to pale yellow. I looked at the layers and thought of taking advantage of this point. In order to do this, the wavelength 3 is measured using a spectrophotometer.
When the relationship between nickel concentration and absorbance was investigated at 70% sK, it was found that there was a correlation φ, and the apparatus of the present invention was devised.

Hereinafter, the present invention will be explained in detail by way of examples with reference to FIGS. 1 and 2.

As shown in FIG. 1, a plating tank 1 is provided with a liquid circulation pipe 3 as in the past, a bypass path 4 is provided in the pump 2t, and a device 5 for measuring absorbance is provided along the way.
It is intended to provide

Inside the apparatus for measuring absorbance, as shown in FIG. 2, an absorbance measuring cell 80 connected to a bypass path 4 is provided with a light source 6 on one side and a light receiving section 7 on the other side.

When plating is performed using this device, the liquid in the cell is constantly circulated through the liquid circulation, which makes it possible to constantly measure changes in the nickel concentration in the i1 bath using the absorbance measurement device. , it becomes easier to manage the nickel concentration.

As described above, according to the apparatus of the present invention, since the nickel concentration can be constantly controlled, copper-tin alloy plating of stable quality is always possible.

Note that the method for attaching the absorbance measuring device is not limited to that described in the embodiments, and similar effects can be achieved by other methods.

[Brief explanation of drawings]

FIG. 81 is a schematic diagram of an apparatus showing an example of an embodiment of the present invention, and FIG. 2 is a diagram showing an example of the inside of the absorbance measuring apparatus. 101. Plating tank 200. Pump 306. Circulation pump 40. . Bypass path 506. Absorbance measuring device 6...light source 710. Light receiving section 800. Absorbance measurement cell and above Applicant: Daini Seikokin Co., Ltd. Agent Mr. Mogami 1st grade Figure 1

Claims (1)

[Claims] A plating apparatus for copper-tin alloy plating, characterized in that it is equipped with a mechanism for measuring the absorption straight tube of a plating bath.
Tin alloy plating equipment.