JPH02175894A - Method and device for tin or tin alloy electroplating - Google Patents

Abstract

PURPOSE:To stably electroplate a material to be plated with Sn or an Sn alloy by jointly using metallic Sn and an insoluble anode as the anode at the time of plating the material in a diaphragm-type plating bath. CONSTITUTION:An Sn or Sn alloy electroplating bath is separated by the diaphragms 3 of a cation-exchange membrane, a porous sheet, a 'Vinylon(R)' nonwoven fabric, etc., into anode chambers 1 and 1 and a cathode chamber 2. An article 5 to be plated is placed in the cathode chamber 2, and an insoluble anode 6 of carbon, etc., and a consumable anode 4 made of metallic Sn or an Sn alloy are dipped in the anode chambers 1 and 1. A plating soln. contg. Sn ion and Sn alloy ion is charged into the plating bath, and a DC voltage is impressed from a rectifier 7 to apply a current. The stannous ion eluted from the anode 4 is oxidized to stannic ion by the O2 generated from the anode 6, the stannic ion enters the cathode chamber 2 through the diaphragm 3, and the surface of the material 5 is stably plated with Sn or an Sn alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for electroplating tin or a tin alloy easily and with high efficiency, and a plating apparatus for carrying out the method.

<Prior Art> Conventionally, in electroplating methods for tin and its alloys, the tin ions in the plating bath were stannous ions. Stannous ions are easily oxidized to stannic ions.

This changes the bath composition and causes phenomena such as mixing of stannous and stannous ions, which adversely affects plating and sometimes makes plating impossible.

Also, Frederic Knee, Lohenheim (Freder
ick A, Modern Electroblating by Lowenheiml.

plating) 3rd edition 394 pages (1974) John Wiley and Sams Inc., 1JohnWi
Published by Ley & Soms Inc., the alkaline stannate bath [KaSn fOH-1
A method is described in which tin electroplating is carried out using NatSn (O old, ) as an electric bath and tin as an anode. In this method, it is strictly required to maintain an appropriate current density. At current density, oxygen is generated from the anode and a yellow-green film is formed, which dissolves as tetravalent tin.However, at low current density, a white film (Sn*21) is formed on the surface of the tin anode, which is eluted. If the current density is too high, excess oxygen will be generated, forming a black oxide film on the surface of the tin anode.
The tin anode will not melt at all. Therefore, when implementing this method, several tin anodes are taken out from the plating tank in advance to increase the anode current density, and then the tin anodes that were taken out in advance are returned to the plating tank one by one to maintain the appropriate density. That is necessary. Such means are inefficient and difficult to put into practical use.

The present invention first discloses the use of tin salts, cobalt salts, nickel, etc. as alloy film forming agents for producing binary alloy plating films of tin-cobalt, tin-nickel, and tin-lead which have a particularly bright and decorative effect. Patent application 1982 concerning a plating bath composition obtained by mixing any one of salts and lead salts; 1-hydroxyecune l,l diphosphonic acid or its salt; mechunsulfonic acid or its alkali salt and conductive salt.
-No. 30681 was filed. The same specification states that a bath using a stannic salt as the tin salt allows for a more stable plating operation and that the use of a cation exchange membrane makes it possible to control the bath composition extremely easily. Suggests.

(Problems to be Solved by the Invention) The present invention solves the problems of the method described in modern electroblating, and is
As a result of research, we have developed the present invention for the purpose of further embodying the method suggested in No. 1 and developing an electroplating method that can easily and efficiently perform tin or tin alloy plating, and an apparatus for implementing the method. completed.

Means for Solving the Problems> The present invention to achieve the above object divides the electroplating bath TL into an anode chamber and a cathode chamber by a diaphragm, and the anode chamber contains a metal tin anode and an oxidizing gas. An insoluble anode is placed in the cathode chamber, and the object to be electroplated with tin or tin alloy is placed in the cathode chamber.
By placing a tin or tin alloy electroplating bath in the electroplating bath and applying a voltage between the electrodes, the stannous ions eluted from the metal tin anode are oxidized by the oxidizing gas generated from the insoluble anode. becomes ditin ion,
A tin or tin alloy electroplating method characterized by passing through a diaphragm into a cathode chamber and forming a tin or tin alloy electroplating coating on an object to be electroplated in the cathode chamber, and a diaphragm for carrying out the method. A tin electroplating bath characterized in that the electroplating bath is divided into an anode chamber and a cathode chamber, a metal tin anode and an insoluble anode are placed in the anode chamber, and an object to be plated with tin or tin alloy is placed in the cathode chamber. ,
This invention relates to tin alloy electroplating equipment.

That is, the present invention is characterized in that the electroplating bath is divided by a diaphragm into an anode chamber and a cathode chamber in which the material to be plated serves as the cathode, and a soluble anode, that is, a metal tin anode, and an insoluble anode are both disposed in the anode chamber. There is.

When specifically carrying out the tin and tin alloy electroplating method of the present invention, first, an electroplating bath having a desired composition is poured into a plating bath, an object to be plated is attached to the cathode chamber so as to act as a cathode, and a voltage is applied. do. As electroplating progresses, the plating source in the plating bath decreases, but at the anode, the tin metal anode is gradually eluted into the plating solution as stannous ions. Alternatively, an oxidizing gas, specifically oxygen or chlorine, is generated from the insoluble anode, and the stannous ions become extremely stable stannous ions, which pass through the diaphragm and migrate to the cathode chamber.

The reaction in the anode chamber is expressed by the following equation.

(a) Dissolution of tin anode Sn"-4Sn"+2e- (b) Anodic reaction HJ "2H" +l/20i + 2e- or 2
C1-= C1g + 2e-(c) Stannous oxide Sn" + 1/20*-' in the anode chamber
Sn"10-" or Sn" + C1a-I S
n”+ 2CI- In the method of the present invention, the plating film formed on the catholyte plating material may include various tin alloy films such as tin-cobalt, tin-nickel, tin-lead, tin-zinc, etc., depending on the composition of the electroplating bath, in addition to the tin film. When the concentration of these cobalt, nickel, lead, zinc, etc. in the bath decreases, they can be replenished into the bath by known means.

In the present invention, well-known means can be suitably employed for adjusting the plating bath.

Here is an example.

Salts of the respective metals are used as alloy film forming agents. These are generally plated with 5 g of tin/9. ~5 [1g/flood, cobalt 3g/2
~12g/12, nickel 3g/12~13g/f
i, a range of 3 g/12 to 25 g/I2 of lead is used.

1-Hydroxyethane 1.1 diphosphonic acid (where X represents hydrogen, sodium, potassium, calcium, magnesium, or ammonia)
)IEDPA), the amount of salt added is 80g/I~140
g/l. This contributes to increasing the gloss of the plating film.

Furthermore, the decorative appearance effect is further increased by adding methanesulfonic acid or an alkali salt thereof in an amount of 1 to 4 moles per mole of 1-hydroxyethane-1.1 diphosphonic acid or its salt. And the above two components total 40~
180g/! It is desirable to do so.

As tin salts that are alloy film forming agents, tetravalent compounds such as sodium stannate, potassium stannate, and chloride are preferable, and as cobalt and nickel salts, chloride, sulfate, and perchloric acid are preferable. As the salts and lead salts, water-soluble acetates, perchlorates, etc. are preferable.

As mentioned above, the plating bath according to the present invention uses stannic (tetravalent tin) as the tin salt to change the tin concentration in the liquid by oxidation (and when forming a binary alloy film, it is possible to change the tin concentration in the plating bath). In the bath, all of the target alloy metals for plating, namely tin-cobalt, tin-nickel, and tin-lead, are chelated at the same time, so that the metal concentration ratio in the plating layer matches the alloy composition of the target plating film. It has the characteristic of

Therefore, by keeping the ratio of metal concentrations in the metal within a desired range, the composition of the electrodeposited alloy can be easily controlled.

Furthermore, the bath of the present invention naturally contains known conductive salts necessary for electrodeposition operations, such as sodium chloride, potassium chloride, potassium sulfate, sodium sulfate, ammonium sulfate, and the like. The amount added is within the usual range of about 15 to 80 g/l; if it is too large, it will cause poor plating such as streaks on the coating, and if it is too small, the resistance of the bath will increase.

If necessary, other components may be added to the electroplating bath used in the method of the present invention as long as they do not adversely affect the bath composition.

The conditions for carrying out the electroplating method of the present invention are a bath temperature of 50°C.
~65℃, cathode current density 0.5A/dm"~5A/dm
The anode current density is preferably in the range of 0.5 A/dm to IOA/dm, and the pH range is also extremely wide, 1.0 to 13.5.

As the insoluble anode for generating oxidizing gas, known ones such as carbon and ferrite are used.

Also, as a diaphragm to separate the cathode chamber and anode chamber,
Cation exchange membranes made of styrene and divinylbenzene copolymers introduced with sulfonic acid and reinforced with a synthetic fiber core material, unglazed boards, woven fabrics such as vinylon and nylon, and nonwoven fabrics are used.

Next, the electroplating apparatus of the present invention will be explained. Figure 0 is a side view schematically showing the configuration of an example of the electroplating apparatus of the present invention. In the figure, 1 is an anode chamber, and 2 is a cathode chamber.
In the drawing, the anode chamber is placed on both sides of the cathode chamber.

3 is a diaphragm provided at the boundary between the cathode chamber and the anode chamber.

An insoluble anode 4 and a metal tin anode 4 are placed in the anode chamber 1, and in the cathode chamber? *[Plating substance 5 is placed. Bus bars 8, 9, and 10 are attached to the cathode and anode, respectively, and are connected to the rectifier 7.

When a material to be electroplated is plated by the method of the present invention, an electroplating bath is first injected into the apparatus and a voltage is applied to the electrodes.

As electroplating progresses, the consumed tin component is gradually replenished by elution from the metal tin electrode. Components other than tin may be replenished by known means.

Incidentally, a plurality of electroplating apparatuses of the present invention can be used in parallel, if necessary.

In this case, an anode chamber and a cathode chamber may be provided alternately.

<Examples and Comparative Examples> Next, Examples and Comparative Examples were carried out using the apparatus shown in the drawings to explain the present invention using Examples and Comparative Examples.

Examples 1 to 10, Comparative Examples 1 to 4 (Formation of tin plating film) Table 1 shows the components to be mixed to form each plating bath, and Table 2 shows the components shown in Table 1 mixed together. The conditions for plating using the plating bath manufactured by the method and the properties of the film produced by plating are shown below.

In addition, in Table 1 (the same applies to Tables 3, 5, 7, and 9) showing the composition of the plating solution, among the types of organic compounds, P is 1-hydroxyethane 1.1 diphosphonic acid, and PN is 1-hydroxyethane 1.1 diphosphonic acid. Sodium salt, PK is its potassium salt, H is methanesulfonic acid, HN is its sodium salt, HK is its potassium salt, C is citric acid, CN is its sodium salt, CK
is its potassium salt, and if two types of organic compounds are present, the numbers attached to each indicate the molar ratio, and N, K
If a number is attached, it indicates the number of substituents.

Examples 1) to 24, Comparative Examples 5 to 9 (Formation of tin-lead binary alloy plating film) Table 3 shows the components to be mixed to form each tin-lead binary alloy plating bath, and Table 4 shows the components to be mixed to form each tin-lead binary alloy plating bath. Table 3 shows the plating conditions and the properties of the films produced by plating using a tempering bath prepared by mixing the components shown in Table 3.

Examples 25 to 28, Comparative Examples 1O to 1) <Formation of tin-cobalt binary alloy plating film> Table 5 lists the components to be mixed to form each tin-cobalt binary alloy plating bath. Table 6 shows the plating conditions performed using a plating bath prepared by mixing the components shown in Table 5, and the properties of the films formed by plating.

Example 29 to 32, Comparative Examples 12 to 13 <Formation of tin-nickel binary alloy plating film> Table 7 shows each tin-nickel binary alloy plating Table 8 shows the plating conditions that were carried out using a plating bath prepared by mixing the components shown in Table 7, and the properties of the film formed by plating.

Ko1-1Ω--1! Example 33 to 38, Comparative Examples 14 to 16 Formation of tin-zinc binary alloy plating wave film) Table 9 shows the respective tin-zinc binary alloy plating baths. Table 1O shows the plating conditions that were carried out using a plating bath prepared by mixing the components shown in Table 9, and the properties of the film produced by plating.

YO1--Dan-jma [-2J--=I gloss ξ (g/ε) <Effects of the invention> Compared to the past, electroplating of tin and tin alloy films can be carried out extremely easily. Therefore, the practical value is extremely large.

[Brief explanation of the drawing]

The drawing shows an electroplating apparatus according to the invention. In the figure, l: anode chamber, 2: cathode chamber, 3: membrane, 4: metal tin anode, 5: electroplated O material,
6... Indicates a non-positive anode. Applicant Kosa Co., Ltd. Rikyu 1-210
? Amendment to Moe Procedures (Voluntary) February 1990 IO date

Claims (2)

[Claims] (1) The electroplating bath is divided into an anode chamber and a cathode chamber by a diaphragm, and the anode chamber is equipped with a metal tin anode and an insoluble anode for generating oxidizing gas, and the cathode chamber is equipped with tin or tin alloy electroplating. By placing a tin or tin electroplating bath in an electroplating bath and applying a voltage between the electrodes, the stannous ions eluted from the metal tin anode are oxidized by the oxidizing gas generated from the insoluble anode. A method for electroplating tin and tin alloys, characterized in that the stannic ions are converted into stannic ions, pass through a diaphragm, enter a cathode chamber, and form a tin or tin alloy electroplating coating on an object to be electroplated in the cathode chamber. (2) The electroplating bath is divided into an anode chamber and a cathode chamber by a diaphragm, the metal tin anode and the insoluble anode are placed in the anode chamber, and the object to be electroplated with tin or tin alloy is placed in the cathode chamber. A tin and tin alloy electroplating device characterized by: