JPS6296692A - Nickel-boron alloy plating method - Google Patents

Abstract

PURPOSE:To prolong the life of an electroplating soln. and to obtain superior efficiency of Ni-B alloy plating for a long period by adding a specified amount of metaboric acid or a metaborate to the plating soln. contg. Ni ions and trimethylaminoborane as essential components. CONSTITUTION:Electroplating is carried out with a plating soln. prepd. by adding 1-60g/l metaboric acid or metaborate to an aqueous soln. contg. Ni ions and trimethylaminoborane as essential components. By this method, the plating soln. is prepd. and replenished or regenerated in a time- and labor-having manner and the productivity of plating is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for electrolytic plating of nickel-boron alloy.
In particular, it relates to technology that significantly extends the life of a plating solution and increases operational efficiency including plating efficiency by improving the component composition of the plating solution.

[Prior Art] Nickel-boron alloy plating has the property of providing a coating layer with high heat resistance, and is currently being applied in many fields.

By the way, the nickel-boron alloy plating methods currently in practical use can be roughly divided into electroless plating methods and electrolytic plating methods. In other words, the former electroless plating method involves adding dimethylamine borane or a boron hydride compound as an agent that functions as both a reducing agent and a boron donor to an aqueous solution containing a low concentration of nickel ions, and then plating at about 60°C. This is a method of forming a nickel-boron alloy film by processing at a temperature above, but since the plating film forming reaction proceeds by the reduction reaction of the reducing agent, the deposition rate is slow, and the self-decomposition of the reducing agent is significant. The problem is that the bath life is very short.

On the other hand, the latter electrolytic plating method was proposed as a method that could solve the problems mentioned above with the electroless plating method, and it uses trimethylamine borane, which has self-stability that can withstand oxidation and reduction reactions caused by electrolysis. By using it as a reducing agent and a boron donor, it is possible to increase the plating speed, improve the stability of the plating bath 9, and extend the life of the plating bath.

However, although trimethylamine borane in the above electrolytic plating solution can exhibit excellent stability in the electrolytic plating process, its performance as a boron donor is not necessarily satisfactory, and the amount of plating processed is relatively small. There is a problem in that the production rate of nickel-boron alloy plating rapidly decreases even after sharpening, and this is a major cause of hindering the practical application of electrolytic plating in terms of plating efficiency.

[Problems to be Solved by the Invention] The present invention has been made to overcome this situation, and its purpose is to effectively exhibit the excellent reducing properties of trimethylamine borane when electrolytic plating is applied. The object of the present invention is to provide a method that not only allows plating of nickel-boron alloys but also effectively functions as a boron donor and provides excellent nickel-boron alloy plating efficiency over a long period of time.

[Means for solving the problems] The structure of the nickel-boron alloy plating method according to the present invention is as follows:
The gist is that electrolytic plating is carried out using a plating solution prepared by adding 1 to 60 g/Il of metaboric acid or its salt to an aqueous solution containing nickel ions and trimethylamine borane as main components.

[Function] In order to improve the above-mentioned problems that occur in the case of electrolytic plating using an aqueous solution containing nickel ions and trimethylamine borane as main components, the present inventors have specifically developed a boron-donating method using trimethylamine borane. We have carried out improvement research aimed at maximizing the effectiveness of the body's functions. In this research, the present inventors thought that the above objective could be achieved by adding a third component to the plating solution, and investigated the effects of many additive chemicals on the function of trimethylamine borane as a boron donor. I looked into it. the result,
Previously, no effect was observed on boric acid or its salts, which have been widely used as a nickel plating agent, but when a small amount of metaboric acid or its salts is added, trimethylamine borane acts as a boron donor. It was confirmed that the functionality was significantly improved and the life of the electrolytic plating solution could be significantly extended.

The present invention is based on the above findings, and
In short, by adding an appropriate amount of metaboric acid or its salt to the plating solution containing nickel ions and trimethylamine borane, the plating efficiency (especially its sustainability) was increased by increasing the function of trimethylamine borane as a boron donor. However, despite subsequent research, the reason why a very small amount of metaboric acid or its salt exerts such an outstanding effect remains unclear, but in any case, metaboric acid The coexistence of boric acid or a salt thereof moderately suppresses the decomposition of trimethylamine borane in an electrolytic atmosphere and maintains its function as a boron donor for a long period of time, making it possible to significantly extend the life of the plating bath.

Additives that exhibit these effects include metaboric acid or water-soluble metaborate salts such as sodium metaborate and potassium metaborate.In order to effectively exhibit these effects, it is necessary to add Must be added at least 1 g/IL. As the amount added increases, the above-mentioned effect increases to a certain degree, but at 60g/j
The effect becomes saturated at around 1 liter, and adding more than that will not only increase the cost, but also cause some of it to be unable to completely dissolve in the plating solution, resulting in precipitation and deterioration of its performance as a plating solution. In the invention, the upper limit of the amount added is set at 60 g/42. However, considering the stability of the plating bath and the plating efficiency, the more preferable amount of metaboric acid or its salt is 10
~50 g/u.

In the present invention, the basic components of the electrolytic cleaning solution are nickel ions and trimethylamine borane, and the preferred content of both is 1 to 100 g/l in terms of nickel ions.
, trimethylamine borane is 0.5 g/It or more. That is, nickel ions include nickel sulfate, nickel chloride, nickel sulfamate, nickel acetate, nickel citrate, nickel phosphate, nickel ammonium sulfate,
It is supplied as a water-soluble nickel compound such as nickel hydroxide, and in order to ensure a satisfactory target performance as a nickel-boron alloy plating layer, its concentration should be 1 g/I1 or more in terms of nickel ions. It is better. However, the effect is saturated at around 100 g/u, and increasing the concentration further will not produce a commensurate effect and will only impair economic efficiency, so the concentration as nickel ions should be kept below 100 g/u. It is better.

Next, as mentioned above, trimethylamine borane is indispensable as a boron donor to the plating layer, and if its concentration is less than 0.5 g711, the absolute amount as a boron donor is insufficient, so an appropriate amount of metaboric acid is added. (or a salt thereof), it becomes difficult to obtain an appropriate nickel-boron alloy plating layer.

On the other hand, there is no particular upper limit to the trimethylamine borane content, but considering practicality, it seems appropriate to consider zog/J2 as the upper limit. Therefore, the solubility of trimethylamine borane in an aqueous solution containing nickel ions is 13
g/u, and the required characteristics for a nickel-boron alloy plating layer are fully satisfied not only within this dissolution range but even when added to supersaturation. In particular, even when trimethylamine borane is added to supersaturation, trimethylamine borane can be dissolved by electrolysis. As the supersaturated trimethylamine borane is consumed, the supersaturated trimethylamine borane dissolves, so there is no adverse effect on the plating properties. However, unnecessarily adding a large amount exceeding the saturation amount increases losses due to natural decomposition and scattering of trimethylamine borane, which is uneconomical.
It is best to keep it below about g/, Q.

In addition to the above-mentioned essential components, it is also effective to use an N buffer agent and a complexing agent in the electrolytic plating solution used in the present invention for the following reasons. In other words, the buffering agent has the effect of keeping the p)I of the plating solution constant and increasing the stability of the plating characteristics. For example, these can be added alone or in combination of two or more types if necessary. The preferred amount of buffer added is in the range of 10 to 100 g/jQ. Complexing agents have the effect of keeping the nickel ion concentration constant and suppressing the formation of precipitates due to changes in the pH of the plating solution, such as citric acid, acetic acid, lactic acid, oxalic acid, tartaric acid, and their sodium salts or ammonium salts. Salts, etc. can be mentioned, and the preferable amount thereof is in the range of 1 to 100 g/l.

[Example] After applying a normal plating pretreatment to a copper alloy plate,
Continuous plating treatment was performed under the following conditions, and the amount of current applied until the plating film lost its oxidation resistance (discoloration resistance when heated in the atmosphere at 450° C. for 5 minutes) was measured. The results are summarized in Table 1.

Kumetsuki conditions〉 Bath temperature: 40℃ Current density: 2A/di2 Plating solution composition: Table 1 From Table 1, it can be considered as follows.

(1) Conventional method shown as a comparative example (No. 23°24)
So, regardless of the presence or absence of boric acid, any plating solution is 26-2
The liquid deteriorated with a current flow of 6.5 kilocoulombs/l, making it impossible to obtain the desired electroplating effect.

(2) In contrast, in Examples (Nos. 1 to 19) in which an appropriate amount of metaboric acid or its salt was blended, the plating solution did not deteriorate until it deteriorated. Kffi is 56-66 kg/℃
This value is more than twice that of the conventional example, indicating that the life of the plating solution has been dramatically increased.

(3) On the other hand, if the amount of metaboric acid or its salt added is insufficient compared to the amount specified in the present invention, a considerable life extension effect is observed compared to the comparative example, but the effect is not the same as the example of the present invention. considerably inferior in comparison.

[Effects of the Invention] The present invention is configured as described above, and by incorporating a small amount of metaboric acid or in situ into an electrolytic plating solution containing nickel ions and trimethylamine borane as its main components, its lifespan is significantly extended. It is possible to maintain high plating efficiency over a long period of time. As a result, not only the cost required for preparing the plating solution is reduced, but also
It is possible to enjoy many benefits such as the labor burden required for replacing and replenishing the plating solution is reduced, and the frequency of work interruptions required for these tasks is also reduced, increasing productivity.

Claims (1)

[Claims] A nickel-boron alloy plating method characterized by performing electrolytic plating using a plating solution prepared by adding 1 to 60 g/l of metaboric acid or its salt to an aqueous solution containing nickel ions and trimethylamine borane as main components. .