JPH0931684A - Electrically conductive paste for electrolytic plating and electrolytic plating method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the variation in plated film thickness from occurring, to enable shortening of the plating time and also, to prevent any reduction in mechanical strength and deterioration of electric characteristics of an element of the electronic parts from occurring at the time of plating electronic parts. SOLUTION: This conductive paste 12 is obtained by mixing a metal powder and a vehicle consisting of a resist together and has 55 to 90wt.% of the metal powder content based on the total weight of the paste 12. Then, an area between every adjacent two of electrodes 2 and a connection part of one of the electrodes 2 to the cathode (-) of a DC power source, on an object to be plated 10 are coated with the conductive paste 12 to form electrical continuity among the electrodes 2 and between the cathode (-) of the DC power source and the electrodes 2. Thereafter, the object to be plated 10 and a metallic plate that is used for plating and connected to the anode (+) of the DC power source are immersed in a plating solution 7 and by passing current through the solution 7 between the cathode (-) and the anode (+) of the DC power source, a plated film is formed on the surface of each of the electrodes 2 on the object 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for electrolytic plating in which an object to be plated such as an electronic component is immersed in a plating solution and a plating film is deposited on a predetermined portion of the object to be plated while energized. The present invention relates to a conductive paste for electrolytic plating and an electrolytic plating method using the same.

[0002]

2. Description of the Related Art Barrel plating is one of the plating methods used for plating an object to be plated such as electronic parts.

In this barrel plating method, at least a part is made of a material that allows a plating solution to pass therethrough, and after placing a large number of objects to be plated in a barrel having a cathode electrode inserted therein, the barrel is placed in a plating tank. Is a method of performing plating by immersing in the plating solution and rotating the barrel while supplying electricity between the cathode electrode and the anode electrode.

In the above barrel plating method, the object to be plated is usually small, and it is difficult to efficiently contact the portion to be plated of the object to be plated with the cathode electrode as it is. A current-carrying medium (for example, a steel ball) for efficiently conducting the cathode electrode is placed in the barrel so that the object to be plated and the cathode electrode are surely conducted through the current-carrying medium.

[0005]

However, in the above-described conventional plating method, since there is a difference in shape and specific gravity between the current-carrying medium and the object to be plated, the object to be plated and the current-carrying medium are uniformly distributed in the barrel. Mixing is difficult, the amount of electricity applied to the object to be plated becomes uneven, and the thickness of the plated film varies. Further, if it is attempted to secure a plating film thickness required as a product in consideration of the variation in the thickness of the plating film, the plating time becomes long and the production efficiency is lowered. When the plating time is long, when the object to be plated is a ceramic electronic component, the ceramic body is eroded or melted in the plating solution, resulting in a decrease in mechanical strength and a deterioration in electrical characteristics.

Therefore, the main object of the present invention is to make the thickness of the plating film uniform and to shorten the plating time. Even when the ceramic electronic component is plated,
A conductive paste for electroplating and a conductive paste for electrolytic plating, which can prevent the ceramic body from being corroded or melted by a plating solution to prevent the mechanical strength of the ceramic body from being deteriorated or the electrical characteristics from being deteriorated, An object is to provide an electrolytic plating method.

[0007]

In order to solve the above-mentioned problems, the present invention provides a conductive paste for electroplating in which metal powder and a vehicle made of a plating resist are mixed, and the electroplating of the metal powder is carried out. The content of the conductive paste for use is 55 to 90 wt. It is characterized by being%.

Further, the object to be plated, which is electrically connected to the cathode, and the plated metal body, which is electrically connected to the anode, are immersed in a plating solution, and a current is applied between the cathode and the anode, whereby the object to be plated is predetermined. In an electroplating method for depositing a plating film, between electrodes in the object to be plated, a metal powder, and a conductive paste for electroplating in which a vehicle made of a plating resist is mixed, The proportion of the conductive paste for electrolytic plating is 55 to 90 wt. %, The conductive paste for electrolytic plating is applied to bring it into conduction, the electrode surface is plated, and the conductive paste for electrolytic plating is separated from the object to be plated.

The object to be plated, which is electrically connected to the cathode, and the plated metal body, which is electrically connected to the anode, are immersed in a plating solution, and a current is applied between the cathode and the anode, whereby the object to be plated is predetermined. In an electrolytic plating method for depositing a plating film, an extraction electrode is provided on an electrode in the object to be plated, and a metal powder and a vehicle made of a plating resist are mixed between the extraction electrodes. In the conductive paste for use in electroplating, the ratio of the metal powder in the conductive paste for electrolytic plating is 55 to 9
0 wt. % Of the conductive paste for electroplating to bring it into conduction and perform plating on the electrode surface,
It is characterized in that the conductive paste for electrolytic plating is peeled off from the object to be plated.

Thus, when the conductive paste for electroplating of the present invention is used, the step of connecting the electrodes on the object to be plated is only the application of the conductive paste, and the step of removing the conductive paste is also immersed in the plating resist stripping solution. Since it is only performed, the work is simple, the desired plating film is formed only on the electrode surface, and an electrically excellent plated object can be obtained.

According to the electrolytic plating method of the present invention,
Since the electrodes to be plated are stably energized, the thickness of the plated film on each electrode can be made uniform. Therefore, unlike the conventional plating method, it is not necessary to take a margin into the plating time in consideration of the variation in the thickness of the plating film, and as a result, the plating time can be shortened.

Further, in the case where the lead electrode is provided by plating from the electrode of the object to be plated, the conductive paste is plated without being applied to the electrode, so that the electrode strength is improved.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The conductive paste for electrolytic plating of the present invention and the electrolytic plating method using the same are described below.
The embodiment will be described with reference to the drawings and tables.

First, the steps of producing a conductive paste for electrolytic plating will be described below. In this embodiment, Ag is used as the metal powder.
Powder was used. A plating resist made of an ultraviolet curable resin was used as a vehicle. The Ag powder and the plating resist were mixed and dispersed with a three-roll mill to obtain a conductive paste for electrolytic plating having the composition shown in Sample No. 1 in Table 1.

Similarly, conductive pastes for electrolytic plating having the compositions shown in Sample Nos. 2 to 8 in Table 1 were prepared. In Table 1, those marked with * are outside the range of the composition ratio of the conductive paste for electrolytic plating of the present invention, and the others are within the range of the present invention.

[0016]

[Table 1]

Next, the steps of one embodiment of the electrolytic plating method of the present invention will be described. In FIG. 1, reference numeral 10 denotes an object to be plated, which includes a substrate 1 and a plurality of electrodes 2 formed on the substrate 1. Then, the above-prepared conductive paste 12 for electrolytic plating is applied by a method such as screen printing between the electrodes 2 and to the connection between the cathode (−) of the DC power supply and the electrode 2, and the object to be plated 10 is irradiated with ultraviolet rays to be electrolyzed. Conductive paste for plating 12
Is cured, and the object to be plated 10 and the cathode electrode 5 are electrically connected.

Subsequently, a plating solution containing Ni as a plating metal is used as the plating solution 7, and the cathode (-) of the DC power source is used.
The object 10 to be plated, which is conducted to, is immersed in the plating solution 7, the Ni plate 8 which is a plating metal is connected to the anode (+) of the DC power source, and the Ni plate 8 is immersed in the plating solution 7. In this state, a Ni plating film is formed on the surface of the electrode 2 portion by energizing between the cathode (−) and the anode (+) of the DC power supply.

After the Ni plating is completed, the object to be plated 10
The conductive paste 12 for electrolytic plating above is peeled off by immersing the object 10 to be plated in a plating resist peeling solution. In this example, N-methyl-2- was used as the plating resist stripping solution.
Pyrrolidone is used, but when the electrolytic plating conductive paste 12 is not completely removed by immersion, ultrasonic waves are applied in the immersion liquid to remove it. Through the above steps, the object 10 to be plated having the plating film formed on the surface of the electrode 2 is obtained.

Next, with respect to the electroconductive pastes for electrolytic plating shown in Table 1, the ultraviolet curing property, the sheet resistance value, and the plating property were confirmed. The results are shown in Table 1.

As shown in Table 1, when a plating film is formed using the conductive pastes for electrolytic plating of sample No. 2 to sample No. 7 obtained in this example, the ultraviolet curability and the plating property are good. .

However, when the content of the Ag powder is less than 55% of the total paste amount, as shown in Sample No. 1, the area resistance value of the electroplating conductive paste rapidly increases and no current flows. Plateability deteriorates. On the other hand, when the content of the Ag powder exceeds 90% of the total paste amount, as shown in Sample No. 8, the plating resist which is a vehicle is too small, so that the fluidity peculiar to the paste is further lowered and the printability is deteriorated. Therefore, the ultraviolet curability deteriorates.

Next, the steps of the electrolytic plating method according to another embodiment of the present invention will be described. As shown in FIG. 2, the object to be plated 1
Reference numeral 0 includes a substrate 1 and a plurality of electrodes 2 formed on the substrate 1. A lead electrode 13 is formed on the electrode 2. The extraction electrode 13 is formed simultaneously with the electrode 2 or the electrode 12
Any of them may be formed. Then, among the prepared electroconductive pastes for electrolytic plating, the electroconductive plating pastes for sample Nos. 2 to 5 are screen-printed between the extraction electrodes 13 and at the connection portion between the cathode (−) of the DC power source and the extraction electrode 13. Apply by the method such as
0 is irradiated with ultraviolet rays to cure the conductive paste 12 for electrolytic plating, and the object 10 to be plated and the cathode (−) of the DC power supply are electrically connected.

Then, a plating solution containing Ni as a plating metal is used as the plating solution 7, and the cathode (-) of the DC power source is used.
The object 11 to be plated, which is electrically connected to, is immersed in the plating solution 7, the Ni plate 8 which is a plating metal is connected to the anode (+) of the DC power supply, and the Ni plate 8 is immersed in the plating solution 7. In this state, the Ni plating film is formed on the surface of the electrode 2 by energizing between the cathode (−) and the anode (+) of the DC power supply.

After the Ni plating is completed, the object to be plated 10
The above electroconductive paste for electrolytic plating is peeled off by immersing the object 10 to be plated in a plating resist peeling solution. Also in this embodiment, N-methyl-2 was used as the plating resist stripping solution.
-Pyrrolidone is used, but when the conductive paste for electrolytic plating is not completely removed by immersion, ultrasonic waves are applied in the immersion liquid to remove it. Then, an overcoat is applied on the lead-out electrode 13 which is not necessary as a product by a method such as screen printing, and the object 10 to be plated with the plated film on the electrode 12 is obtained through the above steps.

Next, for the obtained object 10 to be plated, the thickness of the Ni plated film of each electrode 2 was confirmed. The results are shown in Table 2. In addition, this result is the result when using the conductive paste type 6 (Ag powder: plating resist = 80: 20 wt.%) Of the conductive paste for electrolytic plating in Table 1. Further, for comparison, Table 2 also shows the results of the thickness of the Ni plated film obtained by the barrel plating method of the conventional example. In addition,
The thickness of the formed Ni plating film was measured by the fluorescent X-ray method. (Number of samples n = 15)

[0027]

[Table 2]

Variation in thickness of Ni plating film (maximum value-
As shown in Table 2, the minimum value is 1.85 μm when plating is performed by the method of the conventional example, whereas it is 0.25 when plating is performed by the method of the embodiment of the present invention.
38 μm, when plated by the method of the other embodiment of the present invention, it is 0.37 μm, and it can be seen that the thickness variation of the plated film is 1/4 or less. This is because in the plating method of the present invention, the amount of electricity applied to the object to be plated becomes uniform.

Further, regarding the electrode strength (average value) of the obtained object 10 to be plated, the method of one embodiment of the present invention and the method of other embodiments were confirmed. The electrode strength was measured by the tensile test method. When plating is performed by the method of one embodiment of the present invention, the electrode strength is 1.2 kg /
2 mm □, when plating is performed by the method of the other embodiment of the present invention, the electrode strength is 2.1 kg / 2 mm □, and the electrode strength is further increased in the method of the other embodiment of the present invention. Was confirmed.

In the above embodiments, the case where the electrode surface formed on the substrate is plated has been described as an example, but the objects to which the present invention can be applied are various electronic parts, Furthermore, it can be applied when plating various components other than electronic components, products, and the like.

The present invention is not limited to the above-mentioned embodiments in other points as well, and the kind of metal powder used in the electroconductive paste for electrolytic plating, the kind of plating resist as a vehicle, and the kind of metal to be plated. Etc. are not particularly limited.

[0032]

As described above, in the conductive paste for electrolytic plating of the present invention and the electrolytic plating method using the same, the step of electrically connecting the electrodes on the object to be plated is only to apply the conductive paste. Since the conductive paste stripping step is simply immersed in the plating resist stripping solution, the work is simple and the desired plating film is formed only on the electrode surface, and an electrically excellent plated object is obtained. .

Further, by applying the electroconductive plating conductive paste between the electrodes on the object to be plated, the electrodes on the object to be plated are stably energized, so that the thickness of the plated film on each electrode is made uniform. Will be able to. Therefore,
Unlike the conventional plating method, it is not necessary to take a margin in the plating time in consideration of the variation in the thickness of the plating film, so that the plating time can be shortened.

Further, in the case where the lead electrode is provided by plating from the electrode of the object to be plated, the conductive paste is plated without being applied to the electrode, so the electrode strength is improved.

[Brief description of drawings]

1A and 1B show an electrolytic plating method according to an embodiment of the present invention, FIG. 1A is a plan view of an object to be plated, and FIG.

2A and 2B show an electrolytic plating method according to another embodiment of the present invention, FIG. 2A is a plan view of an object to be plated, and FIG.

[Explanation of symbols]

 2 Electrode 7 Plating solution 10 Plated object 12 Electroconductive plating conductive paste 13 Extraction electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koei Sugo 226-10 Tenjin Tenjin, Nagaokakyo City, Kyoto Murata Manufacturing Co., Ltd.

Claims (3)

[Claims] 1. In a conductive paste for electroplating, which comprises a mixture of metal powder and a vehicle made of a plating resist, the proportion of the metal powder in the electroconductive paste for electroplating is 55 to 90 wt. %, A conductive paste for electrolytic plating. 2. The object to be plated, which is electrically connected to the cathode, and the plated metal body, which is electrically connected to the anode, are immersed in a plating solution and a current is applied between the cathode and the anode, whereby the object to be plated is predetermined. An electrolytic plating method in which a plating film is deposited, between electrodes in the object to be plated.
Conductive by applying the conductive paste for electrolytic plating described,
An electrolytic plating method, characterized in that the electrode surface is plated and the conductive paste for electrolytic plating is peeled off from the object to be plated. 3. The object to be plated, which is electrically connected to the cathode, and the plated metal body, which is electrically connected to the anode, are immersed in a plating solution, and a current is applied between the cathode and the anode, whereby the object to be plated is predetermined. In an electrolytic plating method in which a plating film is deposited, lead electrodes are provided on the electrodes in the object to be plated, and the conductive paste for electroplating according to claim 1 is applied between the lead electrodes to make them conductive, An electrolytic plating method characterized in that the surface is plated and the conductive paste for electrolytic plating is peeled off from the object to be plated.