JPS631725B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of forming electrodes on an element body made of ceramic or the like by a chemical method.

Conventionally, electroless methods mainly composed of base metals such as nickel and copper have been used as a method for forming electrodes or wiring patterns on various electronic components such as oxide ceramic semiconductors or IC boards such as ceramic capacitors, positive temperature coefficient thermistors, and varistors. The Metsuki method is known. The electroless plating method is used to reduce costs as a substitute for expensive silver-baked electrodes, or to effectively bring out the electrical properties of the element, but the adhesion of the electroless plating layer In order to achieve the same effect as above, the element body is subjected to surface roughening, cleaning, degreasing, drying, sensitization, etc. before electroless plating treatment, and then this element body is further treated with PdCl ₂ Alternatively, it was necessary to activate the surface by immersing it in a solution containing SnCl ₂ or the like. For this reason, there are disadvantages in that the number of pretreatment steps is large and complicated, and the manufacturing cost is high.

Furthermore, since the element body activated as described above is immersed in an electroless plating bath mainly composed of nickel or copper, an electroless plating layer is attached to the entire surface of the element body. Partial selective plating limited only to the electrode formation region is impossible, and unnecessary plating layers must be removed by chemical etching, centerless polishing, sandblasting, etc. after electroless plating. For this reason,
Conventional electrode forming methods also have the following drawbacks.

(1) A process for removing unnecessary plating layers is required, which increases the number of processes and increases manufacturing costs.

(2) When removing the plating layer by centerless polishing or sandblasting, etc., interfacial peeling of the plating layer, decrease in adhesive strength, associated deterioration over time, damage or cracking of the element body, or microcracks, etc. may occur. It has been difficult to manufacture highly reliable products with good yields. Particularly in cases where the element body is thin, commercialization has sometimes had to be abandoned due to a lack of mechanical strength.

(3) When unnecessary parts of the plating layer are removed by chemical etching, there are many etching steps, which increases manufacturing costs, and the element body is damaged by the etching solution, which may impair electrical characteristics. deteriorates.

(4) The adhesive strength of the plating layer is weak, and residual ions from the plating liquid are present at the interface between the plating layer and the element, causing peeling of the plating layer, resulting in deterioration of electrical characteristics, and deterioration over time. .

The present invention eliminates the above-mentioned drawbacks of the prior art, and allows electrodes in a predetermined pattern to be formed directly at positions where electrodes are to be formed without requiring an electrode removal process, reducing the number of steps. , economical;
Moreover, it is an object of the present invention to provide an electrode forming method that can form highly reliable electrodes.

In order to achieve the above object, the electrode forming method according to the present invention involves applying a paste containing a reducing agent to a region of an element body where an electrode is to be formed, and then bringing metal ions into contact with the paste to precipitate and generate metal. It is characterized by causing

FIG. 1 shows an embodiment of the invention. First, a paste 2 containing a reducing agent is applied to the area where electrodes are to be formed on the element body 1 made of a suitable material such as dielectric ceramic by means such as screen printing so as to form a predetermined electrode pattern. Then print and apply (Fig. 1b). Suitable examples of the reducing agent include sodium hypophosphite, hydrazines such as hydrazine hydrate and hydrazine sulfate, amines such as isopropylamine, diesoisopropylamine and triethylamine, and formalin. A paste is prepared by mixing this reducing agent in a suitable paste racker, and a suitable mixing ratio is about 1% reducing agent to 99% paste racker.

As mentioned above, if the paste containing the reducing agent is applied onto the element body, the area where the electrodes are to be formed can be easily formed into a highly accurate pattern by means such as screen printing. can be specified.

Next, the element body 1 coated with the reducing agent paste 2 is
Immerse in metal ion solution 3 (Fig. 1c). Then, the metal ion M ²⁺ in solution 3 is reduced by the reducing agent contained in paste 2, and paste 2
A metal film 4 according to the pattern is deposited on the coated area (FIG. 1d).

The metal ion solution 3 mentioned above includes gold, silver,
A saturated aqueous solution of salts or sulfides of various metals such as copper and nickel dissolved in pure water or a hydrophilic organic solvent such as ethylene glycol is suitable.
For example, to explain the case of obtaining copper ion solution 3, copper sulfate pentahydrate (CuSO ₄ , 5H ₂ O)
Dissolve 20g/g in pure water to make a saturated aqueous solution, and add this to ethylene glycol at a ratio of 1:20 ~
Prepare by mixing at a ratio of 30 or more and thoroughly stirring and mixing. In addition, in order to promote the metal precipitation reaction, it is desirable to heat the solution 3 to a temperature of 80 to 90°C. In the case of nickel, a nickel sulfate (NiSO ₄ .7H ₂ O) solution is used.

After that, a finished product is obtained by going through a cleaning, drying process, etc. If the metal film is made of a material with poor solderability such as nickel, electroplating is performed on the metal film using a rotating barrel. According to
Tin, solder plating, etc. may also be applied.

As described above, in the method for forming electrodes of electronic components according to the present invention, a paste containing a reducing agent is applied to a region of an element body where an electrode is to be formed, and then metal ions are brought into contact with the paste to cause a reduction reaction. Since the metal is precipitated and generated by the method, it has the following effects.

(1) Since electrodes can be formed selectively only in the area where electrodes are to be formed, (a) the process of removing unnecessary parts of the electrodes is not required, the number of processes is reduced, and mass productivity is improved. improved and lower manufacturing costs.

(b) Interfacial peeling of electrodes, decrease in adhesive strength, deterioration over time, as seen in centerless polishing, etc.
There is no possibility of various troubles such as breakage or cracking of the element body or generation of microcracks, and highly reliable products can be manufactured at a high yield.

(c) Even if the thickness of the element body becomes thinner, electrodes can be formed without any problems.

(d) There is no possibility of damage to the element body as seen in chemical etching treatments.

(2) Since the area in which the electrode should be formed is specified by applying a paste containing a reducing agent, a highly accurate electrode pattern can be easily formed by means such as screen printing. .

(3) Since the paste is applied, the pretreatment process is much simpler than the conventional electroless plating method, etc., and effects such as a reduction in the number of steps and a reduction in manufacturing costs can be obtained.

(4) By selecting the type of metal ion, it is possible to form an electrode made of a metal suitable for the characteristics and uses of electronic components. For example, if the main purpose is to reduce the cost of the electrode, prevent silver migration, or prevent solder eating, base metal ions such as nickel or copper may be used.

Note that the present invention is not limited to an element body made of ceramic, but can be similarly applied to the case where electrodes are formed on an element body made of synthetic resin, glass, etc., for example.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a method for forming electrodes of an electronic component according to the present invention. DESCRIPTION OF SYMBOLS 1... Elementary body, 2... Paste containing a reducing agent, 3... Metal ion solution, 4... Metal film.

Claims (1)

[Claims] 1. An electronic component characterized in that a paste containing a reducing agent is applied to a region of an element where an electrode is to be formed, and then metal ions are brought into contact with the paste to precipitate and generate a metal film. electrode formation method. 2. The electrode forming method according to claim 1, wherein after applying the paste, the element body is immersed in a metal ion solution to precipitate and generate a metal film. 3. Electrode formation according to claim 1, characterized in that a metal layer with good solderability, such as tin or solder plating, is formed on the precipitated metal film by electroplating. Method.