JPH05230276A - Composition applied to article to be plated and method for plating therewith - Google Patents

Abstract

PURPOSE:To form a strong plating layer on an article made of a heat-resistant plastic and to thereby widen the application area of the plastic. CONSTITUTION:After the title compsn. 2 is applied to an article 1 made of a heat-resistant plastic and cured by polymn. (see fig. 1 (A)), filler particles 3 contained in the surface layer of the cured compsn. are exposed to the outside (see fig. 1 (B)) and removed by dissolution (see fig. 1 (C)). The surface is then electrolessly plated, causing a plating metal 5 to penetrate into a great many minute holes 4 formed on the surface and simultaneously forming a plating layer. The formed plating layer is bonded to the compsn. by the anchor effect. Since the holes 4 are appropriate in size and in density per unit area, the plating layer is bonded to the article 1 very firmly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition to be plated and a plating method using the composition.

[0002]

2. Description of the Related Art Conventionally, electroless plating for plastics has been studied for various plastics such as thermoplastics. However, although the adhesive strength of the plating is weak and it has not been put into practical use, only the one for ABS resin has been put into practical use. The reason is that the double bond of the butadiene moiety of the ABS resin is attacked by acid treatment to form micropores, the plating metal adheres to the micropores, and the metal and resin are firmly bonded by the anchoring effect. It is presumed that it is possible to sufficiently withstand a heat cycle and the like.

[0003]

However, the ABS resin has a limit in heat resistance and has a problem that it cannot be used when heat of 100 ° C. to 120 ° C. or more is applied.

In order to solve this problem, therefore, electroless plating has been attempted on heat resistant plastics such as epoxy, phenol and polyester. However, there is a problem in that the metal film after plating has a weak adhesion to heat-resistant plastics and cannot be put to practical use.

[0005]

In order to solve this problem, the inventors of the present invention have conducted extensive studies and, as a result, have formed a plating film having high strength and durability on a heat-resistant plastic. The composition to be plated was found as follows.

That is, the first composition to be plated according to the present invention comprises 50 to 200 parts by weight of calcium carbonate having a particle size of 5 μm or less as a filler in a resin having a reactive group.

The second composition to be plated has a resin having a reactive group and 50 parts to 200 parts of barium sulfate having a particle size of 5 μm or less as a filler.

Further, a plating method has been invented as follows, which is capable of forming a plating film having high strength and durability on a heat resistant plastic by using the above composition to be plated.

That is, the first plating method of the present invention is
A coating treatment step of applying the above-mentioned first or second plated coating composition to an object to be plated, a curing treatment step of polymerizing and curing the applied plated coating composition, and the cured plated coating composition A surface treatment step of exposing the filler in the material, an elution treatment step of eluting the exposed filler,
The plating treatment step of subjecting the surface of the composition to be plated after the elution treatment to electroless plating.

Further, the second plating method is a method in which a heat treatment step of further heating the object to be plated at a predetermined temperature for a predetermined time is added after the steps of all the treatments of the first plating method.

[0011]

In the invention of the composition to be plated, calcium carbonate or barium sulfate is used as the filler. As a result, when a plating layer is formed by electroless plating, a uniform and relatively thick plating layer without pinholes can be formed in a short time, which can contribute to the economical efficiency and efficiency of plating formation.

Further, since the particle diameter of the filler is 5 μm or less, when the filler exposed on the surface is eluted with the treatment liquid, the filler can be eluted in a short time. Since the elution is easy as described above, a special elution step is not required and the filler can be sufficiently eluted even in the usual pretreatment step (soft etching etc.) in the conventional well-known electroless plating. In addition, in the present invention, it is presumed that the size of the micropores formed after the elution of the filler can contribute to the improvement of the anchoring effect after plating, which can contribute to the improvement of the peel strength of the plated film.

Further, 50 parts by weight to 20 parts of a filler is added to the polymer.
Since it was filled at a rate of 0 part, it is estimated that the density per unit area of the micropores formed after the elution of the filler is appropriate. Therefore, by optimizing the density of the micropores, the anchoring effect after plating is improved, which can contribute to the prevention of blistering and poor adhesion of the plating layer under heating.

In addition, the thermal expansion and contraction of the plating layer is suppressed by the improvement of the anchoring effect after the plating described above, so that it is possible to endure the heat cycle of 150 ° C to -40 ° C.

Next, in the invention of the first plating method, the above-mentioned composition to be plated 2 is applied to the object to be plated 1 in the coating treatment step (see FIG. 1 (A)). In the subsequent curing treatment step, when the applied coating composition 2 is polymerized and cured, the plating object 1 and the plating composition 2 are firmly bonded. Further, in the surface treatment step, the filler 3 in the cured coating composition 2 is exposed by a physical or chemical method (see FIG. 1 (B)).

Subsequently, in the elution processing step, the exposed filler 3 is eluted. After the filler 3 is eluted and removed, a large number of micropores 4 corresponding to the shape of the fine particles of the filler 3 are obtained as cavities (see FIG. 1C).

In the next plating step, electroless plating is applied to the surface of the composition 2 to be plated in the above state. In this treatment step, the plating metal 5 penetrates into the many micropores 4 of the composition to be plated 2, and a plating layer is formed on the surface of the composition to be plated 2 with a uniform thickness. .. When the electroless plating is completed, the plating film is integrally joined to the object to be plated 1 by the anchoring effect (Fig. 1 (D)).
reference).

In the plated product thus obtained, the large number of micropores 4 obtained after the elution of the filler 3 in the composition 2 to be plated has an appropriate size capable of contributing to the anchoring effect after plating. It is presumed that the peel strength of the plated film can be improved.

Further, the filler 3 is added to the polymer which is polymerized and cured.
It is presumed that the density per unit area of the micropores 4 formed after the elution of the filler 3 is appropriate since the filler is filled in a ratio of 50 to 200 parts. Therefore, this micropore 4
The anchoring effect after plating is improved by optimizing the density of
It is possible to prevent swelling and poor adhesion of the plating layer under heating.

In addition, since the anchoring effect after the plating is improved, the thermal expansion and the thermal contraction of the plated layer are suppressed, so that the thermal cycle of 150 ° C. to −40 ° C. can be endured.

Next, in the invention of the second plating method, after the steps of all the treatments of the invention of the first plating method, a heat treatment step of further heating the object to be plated at a predetermined temperature for a predetermined time is added. It is a thing. By adding this heat treatment step, the intermolecular distance between the object to be plated and the plating layer is shortened,
The secondary bonding force increases, and the bonding between the two becomes stronger.

[0022]

EXAMPLES Examples of the plating method of the present invention will be described in detail below.

The plating adhered composition used in this plating method contains a colorant, a filler, a dispersant, and a solvent for adjusting the viscosity, in addition to the resin base having a reactive group.

The base material is preferably the same as that of the material to be plated, as will be described later, and is, for example, epoxy, phenol, polyester, urethane or the like having high heat resistance. As the filler, it has been found that calcium carbonate or barium sulfate is suitable as described later. The colorant is, for example, cyanine green, the dispersant is, for example, polyethylene glycol noniphenyl ether, and the viscosity adjusting solvent is, for example, cyclohexanone.

[0025]

[Table 1] Next, the base, colorant, filler, dispersant, and viscosity adjusting solvent as shown in Table 1 were weighed in the weight ratio shown in Table 1, put in a stirring container and stirred by a stirrer to be plated. Create a composition. The rotation speed of the stirrer is 1200 rpm
The stirring time is 3 hours to 6 hours.

Further, a predetermined curing agent (for example, modified amine) is added in a weight ratio of 12 to 100 of the coating composition thus prepared, and the mixture is sufficiently stirred to obtain a coating composition containing the curing agent. To create. Then, as an object to be plated, a printed circuit board 10 having a copper foil circuit 11 on the surface thereof is prepared from a plastic having high heat resistance, for example, an epoxy resin.

Then, by screen-printing the surface of the prepared printed circuit board 10 in the X-axis direction, clay was first prepared as the undercoating agent 12 to prepare a composition of the same series as the composition to be plated 2 and to a uniform thickness. Apply to After application, the primer 12 is dried and cured at a temperature of 150 ° C. for 30 minutes. After that, the above-mentioned plating adhered composition 2 containing a curing agent is applied to the surface of the printed circuit board 10 in the Y-axis direction by screen printing to a uniform and predetermined thickness. After the application, the composition to be plated 2 is applied 150
Dry and cure for 30 minutes at a temperature of ° C. As a result, as shown in FIG. 2 (A), the printed board 10 and the composition to be plated 2 are firmly bonded. At this time, the thickness of the undercoating agent 12 is preferably about 20 to 30 μ, and the thickness of the composition to be plated 2 is preferably about 20 to 30 μ.

As described above, when the undercoating agent 12 is undercoated, the adhesiveness with the copper foil circuit 11 is improved and the insulation of the circuit can be secured. Furthermore, since the undercoating agent 12 is applied by screen printing in the X-axis direction of the printed circuit board 10, the composition 2 to be plated is applied by screen printing in the Y-axis direction of the printed circuit board 10. Can be prevented, and the coated surface can be smoothed.

When the curing of the composition to be plated 2 is completed in this way, the filler 3 in the cured composition 2 to be plated is subsequently exposed, as shown in FIG. 2B. .. The filler 3 is generally exposed by buffing the surface of the composition 2 to be plated, but the surface treatment may be other physical or chemical polishing.

Next, the pretreatment of the usual electroless plating treatment,
In other words, cleaner conditioner, hot water wash, water wash,
Each treatment such as soft etching, washing with water, acid activation, and washing with water is sequentially performed, but the exposed large number of fillers 3 are eluted by sodium persulfate used for soft etching and crude sulfuric acid used for acid activation. , As shown in FIG. After the filler 3 is eluted and removed in this way, a large number of cavities of micropores 4 corresponding to the shape of the fine particles of the filler 3 are obtained.

Subsequently, the surface of the plating adhered composition 2 in the above state is electrolessly plated with gold, silver, copper, nickel, zinc or the like. As the electroless plating solution, product number “328A” of Secret Japan Co., Ltd. is used here, and the plating condition is that the plating temperature is 19 ° C. to 22 ° C. and the plating time is 20 minutes.

By this electroless plating process, the plating metal 5 penetrates into the innumerable micropores 4 of the composition 2 to be plated, and a plating layer is uniformly formed on the surface of the composition 2 to be plated. Will be done.

When the electroless plating is completed, (D) of FIG.
As shown by, a plating film having a predetermined thickness is formed. Next, after each step of washing with water, drying, acid activation, and washing with water in this order, electroplating is performed. This electroplating uses a chemical such as copper sulfate pentahydrate as in the conventional case, and the plating condition is that the temperature is 22 ° C. to 28 ° C. and the plating time is 50 to 70 minutes. Then, after the electroplating is finished, each process of rust prevention and drying is performed, and the whole process is finished.

Thus, the composition to be plated 2 is applied, plated, and then the plated layer is etched into a circuit pattern to obtain a multilayer printed circuit board having the composition 2 to be plated as an insulating layer. However, if the plating adhered composition 2 is selectively applied without being applied to the entire surface of the copper foil of the printed circuit board as described above, the uncoated round portion is directly connected to the underlying copper foil to form a through hole. There is no inter-layer conduction.

The plating method of the present invention is carried out by the above treatments.
A comparative test as shown in FIG. That is, in this comparative test, the composition to be plated was subjected to the conditions shown in Table 1, only the filler was changed in its type and average particle diameter, and the plating was performed in the same process as above. The results are shown in Table 2.

[0036]

[Table 2] In Table 2, the thickness of the formed plated layer was measured by peeling off the formed plated layer and measuring the thickness with a micrometer. With respect to the peeling strength, the plated layer after formation is cut into a strip having a width of 25 mm with a cutter knife, and a part thereof is forcibly peeled in the direction of 180 ° by a tensile tester. At this time, the pulling speed is 50 mm / min. For the observation of the surface condition, the gloss of the plated surface was observed with the naked eye, "A" was good and "B" was diffuse reflection.
Further, the presence or absence of pinholes was examined by observing the peeled plating layer with a microscope of 30 times to inspect the presence or absence of pinholes.

From Table 2, comparing the thickness of the formed plating layer, the peeling strength of the plating layer, the surface condition of the plating, and the presence or absence of pinholes, calcium carbonate and barium sulfate are excellent fillers. I found out. That is, when calcium carbonate or barium sulfate is selected as the type of filler, a uniform and relatively thick plating layer without pinholes can be formed in a short time, which is efficient and economical (see Table 2).

It has been found that calcium carbonate preferably has an average particle size of 5.0 μ or less, and barium sulfate has an average particle size of 5.0 μ or less, preferably 1.5 μ or less. The reason is that when the heat-cured filler is exposed on the surface and is eluted with the treatment liquid, the filler can be completely eluted with the treatment liquid in a short time, and in the process of pretreatment of the usual plating process. This is because elution becomes possible. At the same time, it is presumed that the size of the micropores formed after the elution of the filler can contribute to the improvement of the anchoring effect after plating, and the peel strength of the plating film is improved as shown in Table 2 (Table 2).

In the comparative test shown in Table 2, it was found that calcium carbonate or barium sulfate was excellent as the filler for the composition to be plated, and its suitable average particle size could be specified. However, in order to find out the optimum mixing ratio (weight ratio) of calcium carbonate or barium sulfate occupying in the composition to be plated with the filler, a comparative test as shown in Table 3 was performed.

[0040]

[Table 3] In this comparative test, when the sample filler is calcium carbonate, the average particle size is 0.8μ, and when the sample filler is barium sulfate, the average particle size is 1.0μ,
The addition amount is 30 parts, 50 parts, 100 parts, 150 parts, 2
It was carried out by changing it to 00 parts, 230 parts, 250 parts. In addition, the components other than the filler in each sample, that is, each substance of the base, the colorant, the dispersant, and the viscosity adjusting solvent, and the mixing ratio thereof are the same as in Table 1.

Next, from the results of this comparative test, the thickness of the formed plating layer, the peeling strength of the plating film, the surface condition of the plating, and the presence or absence of pinholes were compared for each sample. In both the case and barium sulfate, it can be seen that a weight ratio of 50 parts or more is put to practical use.

However, if the weight ratio of the filler exceeds 200 parts, the peeling strength of the plating is reduced and the composition to be plated is subject to cohesive failure and, at the same time, it becomes brittle and the coating suitability is deteriorated. Moreover, if the weight ratio exceeds 200 parts, there is a problem in that it is difficult to mix the composition to be plated when it is prepared, and the production thereof becomes difficult.

Therefore, the filler of the composition to be plated to be used in the plating method of the present invention, both calcium carbonate and barium sulfate, is added in an amount of 50 parts by weight or more.
A range of 200 parts was found to be optimal. In other words, the optimum addition amount is in the range of 50 parts to 200 parts, and it is presumed that the density per unit area of the micropores that are cavities after elution of the filler is appropriate. Therefore, the proper density of the micropores improves the anchoring effect after plating, and can prevent swelling and poor adhesion of the plated layer under heating, thus greatly improving the thermal shock strength.

Further, since the anchoring effect after the plating is improved, the thermal expansion and the thermal contraction of the plating layer are suppressed, so that the thermal cycle of 150 ° C. to -40 ° C. can be endured.

Next, another embodiment of the plating method of the present invention will be described.

In this embodiment, the printed circuit board 10 is further heated to a predetermined temperature (for example, 15) after each processing of the above embodiments.
At 0 ° C., a heat treatment of heating for a predetermined time (for example, 30 minutes) is added.

As shown in Tables 2 and 3, it can be seen that the peel strength of the plating layer is improved when the heat treatment is added as compared with the case where the heat treatment is not added.
It is presumed that the reason is that when heat treatment is applied, the intermolecular distance between the printed board 10 and the plating layer is shortened, the secondary bonding force is increased, and the bonding between the two becomes stronger.

The above is the case where the plating method of the present invention is applied to a printed circuit board. However, as an object to be plated that can be applied to this plating method, in addition to the above-mentioned printed circuit board, it can be widely applied to a field requiring heat resistance such as a material for an electromagnetic shield and a product for decoration.

[0049]

As described above, in the invention of the composition to be plated, since calcium carbonate or barium sulfate is used as the filler, uniform plating can be performed in a short time when the plating layer is formed. It can contribute to efficiency and economy in forming.

Further, since the particle diameter of the filler is set to 5 μm or less, when the heat-cured filler is exposed on the surface and eluted with the treatment liquid, the filler is completely eluted with the treatment liquid in a short time. Yes, it is efficient. At the same time, it is presumed that the size of the micropores formed after the elution of the filler can contribute to the improvement of the anchoring effect after plating, which can contribute to the improvement of the peel strength of the plated film.

Furthermore, it is presumed that the density of the fine pores formed per unit area of the composition filled with the filler in the ratio of 50 to 200 parts will be appropriate.
Therefore, by optimizing the density of the micropores, the anchoring effect after plating is improved, which can contribute to the prevention of blistering and poor adhesion of the plating layer under heating.

In addition, since the thermal expansion and the thermal contraction of the plating layer are suppressed by improving the density of the anchoring effect after the plating described above, the thermal cycle of 150 to -40 ° C can be endured.

Next, according to the invention of the first plating method,
For heat-resistant plastic, a uniform and relatively thick plating layer without pinholes can be formed in a short time,
It is economical.

In addition, the formed plating layer improves the peeling strength of the plating film due to the improved anchoring effect, and
By improving the anchoring effect, it is possible to prevent swelling and poor adhesion of the plating layer under heating. Further, since the anchoring effect is improved, the thermal expansion and the thermal contraction of the plating layer are suppressed, so that the plating layer can withstand the heat cycle of 150 ° C to -40 ° C.
Therefore, it is possible to form a plating layer that can be practically used for heat-resistant plastic.

Next, in the invention of the second plating method, after each treatment of the invention of the first plating method, a heating treatment for further heating the object to be plated at a predetermined temperature for a predetermined time is added. The intermolecular distance between the object to be plated and the plating layer is shortened, the secondary bonding force is increased, the bond between the two becomes stronger, and the bond strength of the plating is further improved.

[Brief description of drawings]

FIG. 1 is a process diagram illustrating a plating method of the present invention.

FIG. 2 is a process diagram when the plating method of the present invention is applied to a printed circuit board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plated object 2 Plated composition 3 Filler 4 Micropores 5 Plated metal 10 Printed circuit board 11 Copper foil 12 Undercoat agent

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[Procedure amendment]

[Submission date] April 19, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title: Composition to be plated and plating method using the same

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition to be plated and a plating method using the composition.

[0002]

2. Description of the Related Art Conventionally, electroless plating for plastics has been studied for various plastics such as thermoplastics. However, although the adhesive strength of the plating is weak and it has not been put into practical use, only the one for ABS resin has been put into practical use. The reason is that the double bonds of butadiene et emission portion of the ABS resin is in micropores attacked by the acid treatment is formed, its the micropores plating of metal deposition, firmly bonded by the anchor effect and the metal and resin It is presumed that this will occur, and it is possible to sufficiently withstand a heat cycle and the like.

[0003]

However, the ABS resin has a limit in heat resistance and has a problem that it cannot be used when heat of 100 ° C. to 120 ° C. or more is applied.

Therefore, in order to solve this problem, electroless plating has been attempted on heat-resistant plastics such as epoxy resin , phenol resin and polyester resin . However, there is a problem in that the metal film after plating has a weak adhesion to heat-resistant plastics and cannot be put to practical use.

[0005]

In order to solve this problem, the inventors of the present invention have conducted extensive studies and, as a result, have formed a plating film having high strength and durability on a heat-resistant plastic. The composition to be plated was found as follows.

Namely, main Tsu key object sealing composition of the present invention, the calcium carbonate particle size less 5μ as fillers in 100 parts by weight of the resin having a reactive group and / or sulfuric acid
Barium is made by filling 50 parts by weight to 200 parts by weight.

[0007] Also, using the above plating the sealing composition, a plating method capable of forming a plating film rich in strength and durability against the plastic having heat resistance, and invention as described below.

That is, the first plating method of the present invention is
The above main Tsu key object sealing composition, a coating process for coating the object to be plated, a curing treatment step of polymerizing and curing the coating to be worn composition thereof coated, the filling of the cured coating to be worn composition A surface treatment step for exposing the agent, an elution treatment step for eluting the exposed filler, and a plating treatment step for subjecting the surface of the composition to be plated after the elution treatment to electroless plating. ..

Further, the second plating method is a method in which a heat treatment step of further heating the object to be plated at a predetermined temperature for a predetermined time is added after the steps of all the treatments of the first plating method.

Next, the plating method of the present invention will be described below.
Will be described in detail.

Plated wear assembly used in this plating method
In addition to the resin base that has a reactive group,
It includes a filler, a dispersant, and a solvent for adjusting the viscosity.

The base material is the same as the material to be plated as described later.
The same thing is preferable, for example, epoxy resin with high heat resistance
Fat, phenol resin, polyester resin, polyurethane
For example, resin. As the filler, calcium carbonate,
It has also been found that barium sulfate is suitable. Colorant
For example, cyanine green, for example as a dispersant
For example polyethylene glycol noniphenyl ether, viscosity
The solvent for adjustment is, for example, cyclohexanone.

[0013]

In the invention of the composition to be plated, calcium carbonate or barium sulfate is used as the filler. As a result, when a plating layer is formed by electroless plating, a uniform and relatively thick plating layer without pinholes can be formed in a short time, which can contribute to the economical efficiency and efficiency of plating formation.

Further, since the particle size of the filler is 5 μm or less, when the filler exposed on the surface is eluted with the treatment liquid, the filler can be eluted in a short time. Since the elution is easy as described above, a special elution step is not required and the filler can be sufficiently eluted even in the usual pretreatment step (soft etching etc.) in the conventional well-known electroless plating. In addition, in the present invention, it is presumed that the size of the micropores formed after the elution of the filler can contribute to the improvement of the anchoring effect after plating, which can contribute to the improvement of the peel strength of the plated film.

Furthermore, since the filler is filled in the cured composition to be plated on the basis of 50 parts by weight to 200 parts by weight , the density per unit area of the micropores formed after the elution of the filler becomes appropriate. Inferred. Therefore, by optimizing the density of the micro holes, the anchoring effect after plating is improved,
It can contribute to the prevention of blistering and poor adhesion of the plating layer under heating.

In addition, since the anchoring effect after the plating is improved, the thermal expansion and the thermal contraction of the plating layer are suppressed, so that it is possible to endure the heat cycle of 150 ° C to -40 ° C.

Next, in the invention of the first plating method, the above-mentioned composition to be plated 2 is applied to the object to be plated 1 in the coating treatment step (see FIG. 1 (A)). In the subsequent curing treatment step, when the applied coating composition 2 is polymerized and cured, the plating object 1 and the plating composition 2 are firmly bonded. Further, in the surface treatment step, the filler 3 in the cured coating composition 2 is exposed by a physical or chemical method (see FIG. 1 (B)).

Subsequently, in the elution processing step, the exposed filler 3 is eluted. After the filler 3 is eluted and removed, a large number of micropores 4 corresponding to the shape of the fine particles of the filler 3 are obtained as cavities (see FIG. 1C).

In the next plating step, electroless plating is applied to the surface of the composition 2 to be plated in the above state. In this treatment step, the plating metal 5 penetrates into the many micropores 4 of the composition to be plated 2, and a plating layer is formed on the surface of the composition to be plated 2 with a uniform thickness. .. When the electroless plating is completed, the plating film is integrally joined to the object to be plated 1 by the anchoring effect (Fig. 1 (D)).
reference).

In the plated product thus obtained, the large number of micropores 4 obtained after the elution of the filler 3 in the composition 2 to be plated has an appropriate size capable of contributing to the anchoring effect after plating. It is presumed that the peel strength of the plated film can be improved.

Further, the filler 3 is added to the polymer which is polymerized and cured.
It is presumed that the density per unit area of the micropores 4 formed after the elution of the filler 3 is appropriate, since it is filled at a ratio of 50 parts by weight to 200 parts by weight . Therefore, by optimizing the density of the fine holes 4, the anchoring effect after plating is improved, and it is possible to prevent swelling and poor adhesion of the plated layer under heating.

In addition, the thermal expansion and contraction of the plated layer is suppressed by the improvement of the anchoring effect after the plating described above, so that it becomes possible to endure the heat cycle of 150 ° C to -40 ° C.

Next, in the invention of the second plating method, after the steps of all the treatments of the invention of the first plating method, a heat treatment step of further heating the object to be plated at a predetermined temperature for a predetermined time is added. It is a thing. By adding this heat treatment step, the intermolecular distance between the object to be plated and the plating layer is shortened,
The secondary bonding force increases, and the bonding between the two becomes stronger .

[0024]

【Example】

[Table 1] Next, the base, colorant, filler, dispersant, and viscosity adjusting solvent as shown in Table 1 were weighed in the weight ratio shown in Table 1, put in a stirring container and stirred by a stirrer to be plated. Create a composition. The rotation speed of the stirrer is 1200 rpm
The stirring time is 3 hours to 6 hours.

Further, a predetermined curing agent (for example, modified amine) is added in a weight ratio of 12 to 100 of the coating composition thus prepared and sufficiently stirred, and the coating composition containing the curing agent is added. To create. Then, as an object to be plated, a printed circuit board 10 having a copper foil circuit 11 on the surface thereof is prepared from a plastic having high heat resistance, for example, an epoxy resin.

[0026] Then, in the X-axis direction in the screen printing of the surface of the printed circuit board 10 which is prepared, a predetermined curing agent is first adjusted viscosity to the compositions of the same series and plating the sealing composition 2 as a primer 12 In addition , it is applied to a uniform and predetermined thickness. After application, the primer 12 is dried and cured at a temperature of 150 ° C. for 30 minutes. After that, the above-mentioned plating adhered composition 2 containing a curing agent is applied to the surface of the printed circuit board 10 in the Y-axis direction by screen printing to a uniform and predetermined thickness. After the application, the composition 2 to be plated is dried and cured at a temperature of 150 ° C. for 30 minutes. As a result, as shown in FIG. 2 (A), the printed board 10 and the composition to be plated 2 are firmly bonded. At this time, the thickness of the undercoating agent 12 is 20
˜30 μm is preferable, and the thickness of the composition to be plated 2 is preferably 20 to 30 μm.

As described above, when the undercoating agent 12 is undercoated, the adhesion with the copper foil circuit 11 is improved, and the insulation of the circuit can be secured. Furthermore, since the undercoating agent 12 is applied by screen printing in the X-axis direction of the printed circuit board 10, the composition 2 to be plated is applied by screen printing in the Y-axis direction of the printed circuit board 10. Can be prevented, and the coated surface can be smoothed.

When the curing of the composition 2 to be plated is completed in this way and the filler 3 in the cured composition 2 to be plated is subsequently exposed, it becomes as shown in FIG. 2 (B). .. The filler 3 is generally exposed by buffing the surface of the composition 2 to be plated, but the surface treatment may be other physical or chemical polishing.

Next, the pretreatment of the usual electroless plating treatment,
In other words, cleaner conditioner, hot water wash, water wash,
Each treatment such as soft etching, washing with water, acid activation, and washing with water is sequentially performed, but the exposed large number of fillers 3 are eluted by sodium persulfate used for soft etching and crude sulfuric acid used for acid activation. , As shown in FIG. After the filler 3 is eluted and removed in this way, a large number of cavities of micropores 4 corresponding to the shape of the fine particles of the filler 3 are obtained.

Subsequently, electroless plating of gold, silver, copper, nickel, zinc or the like is applied to the surface of the composition 2 to be plated in the above state. As the electroless plating solution, product number “328A” of Secret Japan Co., Ltd. is used here, and the plating condition is that the plating temperature is 19 ° C. to 22 ° C. and the plating time is 20 minutes.

By this electroless plating treatment step, the plating metal 5 penetrates into the innumerable micropores 4 of the composition 2 to be plated, and a plating layer is uniformly formed on the surface of the composition 2 to be plated. Will be done.

When the electroless plating is completed, FIG.
As shown by, a plating film having a predetermined thickness is formed. Next, after each step of washing with water, drying, acid activation, and washing with water in this order, electroplating is performed. This electroplating uses a chemical such as copper sulfate pentahydrate as in the conventional case, and the plating condition is that the temperature is 22 ° C. to 28 ° C. and the plating time is 50 to 70 minutes. Then, after the electroplating is finished, each process of rust prevention and drying is performed, and the whole process is finished.

Thus, the composition to be plated 2 is applied, and after the plating treatment, the plated layer is etched into a circuit pattern to obtain a multilayer printed board having the composition 2 to be plated as an insulating layer. However, if the plating adhered composition 2 is selectively applied without being applied to the entire surface of the copper foil of the printed circuit board as described above, the uncoated round portion is directly connected to the underlying copper foil to form a through hole. There is no inter-layer conduction.

[0034] By the above processing, although the practice of the present invention a plating method, in order to compare the plating state, Table 2
A comparative test as shown in FIG. That is, this comparative study, for plating the sealing composition and exactly the composition of Table 1, the only filler, changing the average particle size and its kind, others were plated in the same process as described above. The results are shown in Table 2.

[0035]

[Table 2] In Table 2, the thickness of the formed plated layer was measured by peeling off the formed plated layer and measuring the thickness with a micrometer. With respect to the peeling strength, the plated layer after formation is cut into a strip having a width of 25 mm with a cutter knife, and a part thereof is forcibly peeled in the direction of 180 ° by a tensile tester. At this time, the pulling speed is 50 mm / min. For the observation of the surface condition, the gloss of the plated surface was observed with the naked eye, "A" was good and "B" was diffuse reflection.
Further, the presence or absence of pinholes was examined by observing the peeled plating layer with a microscope of 30 times and inspecting the presence or absence of pinholes.

From Table 2, comparing the thickness of the formed plating layer, the peeling strength of the plating layer, the surface condition of the plating, and the presence or absence of pinholes, calcium carbonate and barium sulfate are excellent as the fillers. I found out. That is, when calcium carbonate or barium sulfate is selected as the type of filler, a uniform and relatively thick plating layer without pinholes can be formed in a short time, which is efficient and economical (see Table 2).

It was also found that calcium carbonate and / or barium sulfate has an average particle size of 5.0 μm or less, preferably 1.5 μm or less. The reason for this is that when the filler in the heat-cured composition to be plated is exposed on the surface and eluted by the treatment liquid, the filler can be completely eluted by the treatment liquid in a short time, and the ordinary plating can be performed. This is because elution becomes possible during the pretreatment process. At the same time, the size of the micropores formed after the elution of the filler is
It is presumed that it can contribute to the improvement of the anchoring effect after plating, and the peeling strength of the plating film is improved as shown in Table 2 (see Table 2).

In the comparative test shown in Table 2, it was found that calcium carbonate or barium sulfate was excellent as the filler for the composition to be plated, and its suitable average particle size could be specified. However, in order to find out the optimum mixing ratio (weight ratio) of calcium carbonate or barium sulfate occupying in the composition to be plated with the filler, a comparative test as shown in Table 3 was performed.

[0039]

[Table 3] In this comparative test, when the sample filler is calcium carbonate, the average particle size is 0.8μ, and when the sample filler is barium sulfate, the average particle size is 1.0μ,
30 parts by weight of the addition amount, 50 parts by weight, 100 parts by weight,
150 parts by weight , 200 parts by weight , 230 parts by weight , 250 parts by weight
It was carried out by changing like the quantity part. The components other than the filler in each sample, that is, the base, the colorant, the dispersant, and the substances for the viscosity adjusting solvent, and their mixing ratios,
The same as in Table 1.

Next, from the results of this comparative test, the thickness of the formed plating layer, the peeling strength of the plating film, the surface condition of the plating, and the presence or absence of pinholes were compared for each sample. In both the case and barium sulfate, it can be seen that a weight ratio of 50 parts or more is put to practical use.

However, if the weight ratio of the filler exceeds 200 parts, the peeling strength of the plating is reduced and the composition to be plated is cohesively destroyed, and at the same time, it becomes brittle and the suitability of the coating is deteriorated. Moreover, if the weight ratio exceeds 200 parts, there is a problem in that it is difficult to mix the composition to be plated when it is prepared, and the production thereof becomes difficult.

Therefore, the filler of the composition to be plated to be used in the plating method of the present invention is 50 parts by weight to 200 parts by weight in both calcium carbonate and barium sulfate. The range of parts was found to be optimal.
It is presumed that the reason is that the density per unit area of the micropores, which are cavities after elution of the filler, is appropriate. Therefore, the proper density of the micropores improves the anchoring effect after plating, and can prevent swelling and poor adhesion of the plated layer under heating, thus greatly improving the thermal shock strength.

Further, since the anchoring effect after plating is improved, the thermal expansion and the thermal contraction of the plated layer are suppressed, so that it becomes possible to endure the heat cycle of 150 ° C to -40 ° C.

Next, another embodiment of the plating method of the present invention will be described.

In this embodiment, the printed circuit board 10 is further heated to a predetermined temperature (for example, 15) after each processing of the above embodiments.
The heating treatment is performed by heating at 0 ° C. for a predetermined time (for example, 30 minutes).

As shown in Tables 2 and 3, it can be seen that the peel strength of the plated layer is improved when the heat treatment is applied as compared with the case where the heat treatment is not applied.
It is presumed that the reason is that when heat treatment is applied, the intermolecular distance between the printed board 10 and the plating layer is shortened, the secondary bonding force is increased, and the bonding between the two becomes stronger.

The above is the case where the plating method of the present invention is applied to a printed circuit board. However, as an object to be plated that can be applied to this plating method, in addition to the above-mentioned printed circuit board, it can be widely applied to a field requiring heat resistance such as a material for an electromagnetic shield and a product for decoration.

[0048]

As described above, in the invention of the composition to be coated with plating, since calcium carbonate or / and barium sulfate is used as the filler, uniform plating can be performed in a short time when the plating layer is formed, Therefore, it can contribute to the efficiency and economy of plating formation.

Further, since the particle size of the filler is set to 5 μm or less, when the heat-cured filler is exposed on the surface and eluted with the treatment liquid, the filler is completely eluted with the treatment liquid in a short time. Yes, it is efficient. At the same time, it is presumed that the size of the micropores formed after the elution of the filler can contribute to the improvement of the anchoring effect after plating, which can contribute to the improvement of the peel strength of the plated film.

Further, it is assumed that the composition filled with the filler at a ratio of 50 parts by weight to 200 parts by weight has an appropriate density per unit area of the micropores formed after elution of the filler. .. Therefore, by optimizing the density of the micropores, the anchoring effect after plating is improved, which can contribute to the prevention of blistering and poor adhesion of the plating layer under heating.

In addition, since the thermal expansion and the thermal contraction of the plating layer are suppressed by the improvement of the density of the anchoring effect after the plating, the thermal cycle of 150 ° C. to −40 ° C. can be endured.

Next, according to the invention of the first plating method,
For heat-resistant plastic, a uniform and relatively thick plating layer without pinholes can be formed in a short time,
It is economical.

Moreover, the formed plating layer improves the peeling strength of the plating film due to the improved anchoring effect.
By improving the anchoring effect, it is possible to prevent swelling and poor adhesion of the plating layer under heating. Further, since the anchoring effect is improved, the thermal expansion and the thermal contraction of the plating layer are suppressed, so that the plating layer can withstand the heat cycle of 150 ° C to -40 ° C.
Therefore, it is possible to form a plating layer that can be practically used for heat-resistant plastic.

Next, in the second plating method invention, after each treatment of the first plating method invention, a heating treatment for further heating the object to be plated at a predetermined temperature for a predetermined time is added. The intermolecular distance between the object to be plated and the plating layer is shortened, the secondary bonding force is increased, the bond between the two becomes stronger, and the bond strength of the plating is further improved.

[Brief description of drawings]

FIG. 1 is a process diagram illustrating a plating method of the present invention.

FIG. 2 is a process diagram when the plating method of the present invention is applied to a printed circuit board.

[Explanation of symbols] 1 plated object 2 plated coated composition 3 filler 4 micropores 5 plated metal 10 printed circuit board 11 copper foil 12 undercoating agent

Claims (4)

[Claims] 1. A composition to be plated, which comprises 50 to 200 parts of calcium carbonate having a particle size of 5 μm or less as a filler in a resin having a reactive group. 2. A plating adhered composition obtained by filling 50 to 200 parts of barium sulfate having a particle size of 5 μm or less as a filler in a resin having a reactive group. 3. A coating treatment step of applying the composition to be plated according to claim 1 or 2 to an article to be plated, and a curing treatment step of polymerizing and curing the composition to be plated. A surface treatment step of exposing the filler in the cured plating adhered composition, an elution treatment step of eluting the exposed filler, and electroless plating on the surface of the plated adhered composition after the elution treatment. And a plating method using a composition to be plated, which comprises: 4. A coating treatment step of applying the plating adhered composition according to claim 1 or 2 to an object to be plated, and a curing treatment step of polymerizing and curing the applied plated adherence composition. A surface treatment step of exposing the filler in the cured plating adhered composition, an elution treatment step of eluting the exposed filler, and electroless plating on the surface of the plated adhered composition after the elution treatment. A plating method using a composition to be plated, comprising: a plating treatment step to be performed; and a heating treatment step to heat the plating subject to the plating treatment at a predetermined temperature for a predetermined time.