JPH0135514B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a circuit board, and its purpose is to have a conductive part and an insulating part on the same plane, a smooth mirror-like surface, and further have good heat resistance, moisture resistance, impact resistance, etc. Our goal is to provide superior circuit boards. Conventionally, many proposals have been made regarding methods of forming conductive patterns on circuit boards. For example, as shown in FIG. 1a, an organic adhesive 2 is applied onto an electrically insulating substrate 3 made of paper-phenolic resin or glass fiber-epoxy resin, and a metal foil 1 made of copper or the like is bonded. Alternatively, as shown in FIG. 1b, a metal foil 1 made of copper or the like is hot-press molded onto an electrically insulating substrate 3 made of a glass fiber-diallyl phthalate resin prepreg, and the prepreg is cured and the metal foil is bonded. etc., and in any case,
After manufacturing a so-called copper-clad laminate, there is a method of removing unnecessary portions of the metal foil by etching or the like. On the other hand, there is also a method in which, instead of removing unnecessary parts of the metal foil, a metal such as copper is deposited only on the necessary parts by plating or the like to form a conductive pattern. However, as shown in FIG. 2, the circuit boards obtained by these methods all have a conductive pattern 4 protruding from an electrically insulating substrate 3, and the conductive part and the insulating part are on the same plane. It is impossible to do as above. In order to make this possible, various proposals have been made, such as forming a conductive pattern on a release plate using a printing method and then inverting and pasting it onto an electrically insulating substrate. Due to the limitations of conductive materials, it is extremely difficult to build circuits with low resistance, and considering the thickness of the printed film, it is generally impossible to run a large current;
It was also difficult to obtain fine patterns. Moreover, circuit boards using these conventional general-purpose resins as resins for electrically insulating boards have poor toughness, so the resulting circuit boards may crack, chip, or
Or, there is an inconvenience that may cause a crack.
Furthermore, the heat resistance and moisture resistance were also far from satisfactory. Taking the above points into consideration, the present inventors realized that the conductive part and the insulating part are on the same plane, the board has a smooth mirror-like surface, and the board itself has excellent physical properties such as heat resistance, moisture resistance, and impact resistance. As a result of various studies for the purpose of obtaining a circuit board, the present application was able to achieve its purpose by using a new allyl resin developed earlier as a material for an electrically insulating board. That is, the present invention includes a step of masking unnecessary parts on an aluminum base material and depositing copper by electroplating to form a conductive pattern, and placing the conductive pattern on an electrically insulating substrate so that the pattern surface is aligned with the insulating substrate. The process of laminating them so that they are in contact and obtaining a laminate by thermo-pressing, and the process of dissolving and removing the aluminum base material in the laminate by alkali treatment, provide heat resistance and moisture resistance in which the conductive part and the insulating part are on the same plane. , a method for manufacturing a circuit board with excellent impact resistance, etc., characterized in that the following terephthalic acid diallyl ester copolymer resin is used as the electrically insulating resin used for the electrically insulating board. . The terephthalic acid diallyl ester copolymer resin refers to a copolymer resin of terephthalic acid diallyl ester and an aromatic hydrocarbon having at least one hydrogen atom at the benzyl position represented by the following formula (). (However, in the above formula (), R ¹ and R ² each represent a group selected from the group consisting of a hydrogen atom and a lower alkyl group, and n = an integer of 1 to 3. The present invention is described below with reference to the drawings. Figure 3 a.
~ Figures 3c and 4 show one embodiment of the present invention. As shown in Figure 3a, the aluminum plate or aluminum foil (hereinafter referred to as aluminum base material) is 5
If unnecessary parts other than the upper circuit pattern part (hereinafter referred to as conductive pattern) are masked with masking agent 6, copper is deposited on the necessary parts by electroplating and the masking agent is removed, Figure 3b is obtained.
A conductive pattern 4 can be formed on an aluminum base material 5 as shown in FIG. FIG. 3c shows a laminate obtained by laminating and hot-pressing an electrically insulating substrate 3 made of an electrically insulating terephthalic acid diallyl ester copolymer resin and the conductive pattern shown in FIG. 3b, on an aluminum substrate 5. The conductive pattern 4 formed in is embedded in an electrically insulating substrate. Third
By removing the aluminum base material 5 in Figure c with an alkaline aluminum etching solution,
It is possible to obtain a circuit board in which a conductive pattern 4 as shown in FIG. 4 is embedded in an electrically insulating substrate 3, the conductive portion and the insulating portion are on the same plane, and the surface is smooth and mirror-like. Further, according to the present invention, not only a simple conductive path using a copper layer but also a resistor element 7 is provided in a necessary portion of a conductive pattern 4 formed on an aluminum base material 5, as shown in FIG. After it is assembled by printing or other methods, it is laminated with the electrically insulating substrate 3 as described above, and after hot press molding, the aluminum base material is removed, and as shown in FIG. 6, elements such as conductive parts and resistors are formed. It is thus possible to produce circuit boards in which the sections and the insulating sections are all coplanar. The thickness of the aluminum base material may be selected in consideration of ease of handling and removal of the base material after forming the conductive pattern, but a thickness of about 30 to 100 microns is most convenient for use in the present invention. In order to form a conductive pattern on an aluminum base material, it is preferable to electrodeposit copper on necessary portions by electroplating. Be sure to mask unnecessary parts with a solvent-removable plating resist, immerse it in a plating bath such as a copper sulfate bath or a copper pyrophosphate bath, and apply electricity to electrodeposit a thin copper film using the masked aluminum substrate as a cathode. The electroplating method is advantageous because it can be carried out under acidic conditions, the deposition rate is fast, and the aluminum base material is not easily attacked. In order to improve adhesion to the electrically insulating substrate, the surface may be subjected to an appropriate chemical treatment such as applying copper oxide, or may be mechanically roughened. Further, a suitable adhesive may be applied to the electrically insulating substrate. As the electrically insulating substrate of the present invention, in order to embed the conductive pattern obtained above, it is preferable to use a terephthalic acid diallyl ester copolymer resin newly developed by the applicant as an electrically insulating resin, and the resin itself is It is advantageous because it has excellent electrical properties, heat resistance, high temperature and humidity resistance, bending strength, etc., as well as excellent impact resistance. The above-mentioned terephthalic acid diallyl ester copolymer resin refers to a copolymer obtained by polymerizing terephthalic acid diallyl ester and an aromatic hydrocarbon in the presence of an organic peroxide and an azo compound. A terephthalic acid diallyl ester copolymer resin as described in 1 is preferable as a resin used for the electrically insulating substrate. That is, the following formula () However, in the above formula (), R ¹ and R ² each represent a group selected from the group consisting of a hydrogen atom and a lower alkyl group, and n = an integer of 1 to 3. An aromatic hydrocarbon having at least one hydrogen atom at the benzylic position represented by the following formula () A copolymer resin with terephthalic acid diallyl ester represented by (a) one monomer unit of formula () at the end of the monomer unit of formula (), and an allyl group of the monomer unit of formula () placed at the benzyl position. *C and/
Or * Has a structure in which C and carbon-carbon bonds are formed. Furthermore, (b) the number of monomer units of the formula () in the carbon-carbon bond molecular chain portion formed by the allyl group of the monomer unit of the formula () of the copolymer resin is 3 to 11, preferably 3 to 10; It is a copolymer resin with certain structural characteristics. Furthermore, copolymer resins having the following properties are desirable. (c) Iodine value measured by Wijs method: 40~
85. (d) True specific gravity at 25°C is 1.20-1.25. (e) Softening range: approximately 50 to approximately 120°C. (f) 50% by weight methyl ethyl ketone solution viscosity 80~
300cps (30℃). (g) The polystyrene equivalent number average molecular weight (n) measured by GPC (gel permeation chromatography) method is 4,000 to 10,000, the weight average molecular weight (w) is 70,000 to 200,000, and the relationship between n and Mw is The molecular weight distribution expressed as the ratio w/n is
10-40. (h) Brabender melt viscosity measured with a Brabender plastograph is 250 to 2600 m·g, and processing time is 5 to 65 minutes. The details of the manufacturing method of the terephthalic acid diallyl ester copolymer resin are described in Japanese Patent Application No. 189981/1989 (Japanese Unexamined Patent Publication No. 80409/1989) filed by the present applicant. In the present invention, the above terephthalic acid diallyl ester copolymer resin is combined with paper, glass cloth, glass mat, glass nonwoven fabric, synthetic fiber cloth, synthetic fiber nonwoven fabric, etc. to produce an electrically insulating substrate with excellent impact resistance and other properties. Can be used. Of course, the copolymer resin can also be used after being modified with other resins, such as diallyl phthalate resin or unsaturated polyester resin. If a particularly flexible circuit board is required, a plastic sheet or film such as the above-mentioned terephthalic acid diallyl ester copolymer resin-glass fiber or synthetic fiber laminate may be used. Alternatively, in addition to the laminate, it is also possible to use the above-mentioned terephthalic acid diallyl ester copolymer resin molding material to form an electrically insulating substrate. The resin content in these electrically insulating substrates is 40 to 70
A range of weight percent is suitable. If the patterned surface of the conductive pattern formed on the aluminum base material and the material selected from the above-mentioned various electrically insulating substrates are laminated so as to be in contact with each other and then hot-press molded, an aluminum base material as shown in Figure 3c can be obtained. A sticky circuit board is obtained. Molding conditions are usually temperature
The temperature ranges from 100 to 190°C and the pressure from 5 to 1000 Kg/cm ² . In order to remove the aluminum base material, etching may be performed using an alkaline solution, for example, an etching solution containing 50 g of sodium hydroxide or 1 g of sodium gluconate. After removing the aluminum layer, it is washed with water and dipped in a weak copper etching agent such as 20% ammonium persulfate to remove surface stains, yielding a circuit board as shown in FIG. 4 or FIG. 6. In order to protect the surface of the circuit and maintain solderability, the conductive pattern may be coated with gold, tin/nickel, tin/lead, tin plating, or the like. By effectively utilizing the method of the present invention, it is possible to manufacture multilayer boards as well as circuit boards having conductive patterns on one and both sides. According to the method of the present invention, each process such as applying a masking agent, electroplating, and cleaning can be performed on the aluminum base material in advance, so that the electrically insulating substrate containing organic matter as a component can be treated in a plating bath or other chemical treatment. Less exposed to chemicals, moisture, heat, etc.
Another important feature is that it has the advantage of being less susceptible to damage, and that a high-precision circuit board with excellent dimensional stability can be obtained. The circuit board thus obtained has a conductive part and an insulating part on the same plane, a smooth mirror-like surface, and the circuit board itself has heat resistance, moisture resistance, impact resistance, etc. Therefore, it is particularly suitable for applications such as sliding on circuit boards. It is further advantageous to improve the wear resistance by adding an anti-wear agent or the like to the electrically insulating substrate. The circuit board obtained by the method of the present invention can be used not only as an excellent high-performance printed wiring board, but also for incorporating multi-polar connectors, resistors, etc. For example, if a small motor commutator or carbon electrode is incorporated into various composite elements, potentiometers, encoders, sensors, etc., it can be used as a power supply circuit, and many other fields that take advantage of the sliding properties due to the smoothness of the surface can be used. be. Production of terephthalic acid diallyl ester copolymer resin.Inner diameter 600mm equipped with turbine blade type variable stirrer, double pipe type supply nozzle for monomer and catalyst supply, nitrogen purger, leak valve, sampling port, thermometer and pressure gauge. Comes with a jacket with an internal volume of 120
A polymerization tank made of SUS304 was used. The double-tube supply nozzle for monomer and catalyst supply is installed below the liquid level in the body of the polymerization layer, and the inner diameter of the outer tube is set to 1.5 mm before entering the polymerization tank to minimize the residence time in the supply piping. I made it shorter. Three such nozzles were installed in preparation for nozzle blockage. A sampling port was also installed in the body of the polymerization tank, making it possible to take samples of the liquid phase using the internal pressure during the polymerization reaction. An oil rotary vacuum pump and a nitrogen cylinder were connected to the nitrogen purger so that it could be switched as needed. 60 kg of xylene is charged into the above polymerization layer as shown in Table 1 below, and at room temperature, the pressure is reduced with a vacuum pump and the pressure is returned to normal pressure with nitrogen gas.The operation is repeated three times to replace the air in the tank with nitrogen. After that, the pressure was reduced again and the polymerization tank was sealed. start the stirrer
While stirring at 240 RPM, steam was passed through the jacket to raise the temperature to 140°C. The stirring speed was increased to 720 RPM, and terephthalic acid diallyl ester was added from the outer pipe of the double pipe nozzle at the specified speed, and at the same time, di-tert-butyl peroxide (DTBPO) and xylene were added at a molar ratio of 0.5:1. were mixed in advance and supplied to the polymerization tank at a predetermined speed using a pump with a discharge pressure of 70 kg/cm ² . During this time, the steam was adjusted so that the temperature of the polymerization tank was maintained at 140°C. The terephthalic acid diallyl ester (DAT) to be supplied is heated to 15°C and di-tert peroxide.
- The mixtures of butyl and xylene were each cooled to 5° C., and the piping leading to the polymerization tank was kept cold. The polymerization tank pressure was 0.3 to 2 Kg/cm ² G. Once the specified amounts of diallyl terephthalate, xylene, and di-tert-butyl peroxide have been supplied, the steam is turned off and the stirring speed is reduced to 240 RPM.
Then, cooling water was passed through the jacket to cool it. After cooling to around room temperature, the leak valve was opened to return to normal pressure, and the polymerization reaction was completed. During the polymerization reaction, samples were appropriately taken from the sampling port, and the reaction was monitored using refractive index and GPC. The feed rates and amounts of diallyl terephthalate, xylene, and di-tert-butyl peroxide are shown in Table 1 below. The volatile components of the polymerization reaction solution obtained above were distilled off using a thin film evaporator, and the ratio of unreacted xylene in the evaporation residue to the total of copolymer resin and unreacted diallyl terephthalate was determined. , 0.3 in weight:
1, and then the evaporation residue was added dropwise to a stirring tank containing methanol in an amount 5 times the weight of the supplied diallyl terephthalate and stirred to precipitate a copolymer resin. The precipitated copolymer resin was thoroughly washed with the same amount of methanol, filtered, dried, and pulverized to obtain a powdered copolymer resin. Table 1 shows the yield and physical properties of the copolymer resin.

[Table] In Table 1 above, (1) is the polystyrene equivalent value measured by the gel permeation chromatography method using a "150CGPC" device manufactured by Waters. For (2), a light transmission type automatic melting point measuring device "PF61" manufactured by Mettler was used. (3) is the value measured by Brabender Plastograph manufactured by Brabender (Germany). Kneading chamber capacity 50c.c., rotor model W50H, sample 50
g+zinc stearate 0.5g, kneading chamber temperature 130
℃, the kneading resistance at rotor rotation speed 22 RPM
The processing was continued until reaching 5000 m·g, and from the torque curve of the recording paper, the lowest torque value was taken as the Brabender solution viscosity, and the time from the end of sample introduction to 5000 m·g was taken as the processing time. Example <Formation of a conductive pattern on an aluminum base material> On an aluminum foil with a thickness of 40μ, unnecessary parts were masked with a plating resist agent by screen printing so that only the conductive pattern part was exposed, and copper sulfate was applied. The solution was used as a plating bath to deposit copper on the exposed parts of the aluminum, and after drawing a conductive pattern consisting of a 35 μm thick copper layer, the resist agent was peeled off. <Preparation of electrically insulating substrate> The molding material shown below was prepared using the terephthalic acid diallyl ester copolymer resin produced above. Terephthalic acid diallyl ester copolymer resin
80 parts by weight Diaryl phthalate resin 20 Permil D 2 Short glass fiber 60 Calcium carbonate 35 Wollastonite NYAD400 (calcium metasilicate) 5 Silane coupling agent A174 0.6 Hydroquinone 0.01 part by weight Each of the above components is as follows It is as follows. Diaryl phthalate resin: Osaka Soda Co., Ltd. Percmill D: Nippon Oil & Fats Co., Ltd. Short glass fiber: Asahi Fiberglass Co., Ltd. “CSO”
3HB 830A" Calcium carbonate: "NS-100" manufactured by Nippon Funka Kogyo Co., Ltd. Wollastonite: Manufactured by Nagase Sangyo Co., Ltd. Silane Coupling agent: Manufactured by Nippon Konika Co., Ltd. After thoroughly mixing the above ingredients with 100 parts by weight of methyl ethyl ketone, add methyl ethyl ketone. It was removed, dried, and ground to obtain an electrically insulating substrate material. <Molding of circuit board> The patterned surface of the conductive pattern formed on the aluminum base material is laminated so as to be in contact with the electrically insulating board material, and is heated using a mirror surface at a temperature of 165°C and a pressure of 100 kg/cm ² for 30 minutes. It was molded to obtain a laminate. <Removal of aluminum base material> Add an etching solution containing 50 g of sodium hydroxide and 1 g of sodium gluconate at a temperature of 70°C.
immerse the above laminate in water to remove the aluminum layer,
After thorough washing with water, it was immersed in a 20% ammonium persulfate solution for 10 seconds to obtain a circuit board. The resulting circuit board has conductive parts and insulating parts on the same plane.
It had a smooth mirror-like surface. In addition, when this circuit board was subjected to a falling weight impact test according to JISK7211 (after the Dupont type falling ball test, load 500g, support flat impact core 1/2 inch R), the 50% damage height according to the Dickson mode method was It was 570mm. Incidentally, the same procedure as above was carried out except that a resin consisting of 95 parts by weight of diallyl phthalate resin and 5 parts by weight of diallyl phthalate monomer was used instead of the resin containing diallyl terephthalate copolymer resin used for the electrically insulating circuit board. The 50% failure height of the circuit board obtained by the Dickson mode method of the falling weight impact test was 470 mm.

[Brief explanation of drawings]

1a and 1b are sectional views of a conventional metal foil-clad laminate, FIG. 2 is a sectional view of a conventional circuit board, and 3a to 3c and 4 are sectional views of a conventional circuit board. 3a to 3c are sectional views of each process, FIG. 4 is a sectional view of a circuit board, and FIGS.
The figures show other embodiments of the present invention, with FIG. 5 being a sectional view of the process, and FIG. 6 being a sectional view of the circuit board. 1: Metal foil, 2: Adhesive, 3: Electrical insulating substrate,
4: Conductive pattern, 5: Aluminum base material, 6:
Masking agent, 7: Resistor element.

Claims (1)

[Claims] 1. A step of masking unnecessary portions on an aluminum base material and depositing copper by electroplating to form a conductive pattern, placing the conductive pattern on an electrically insulating substrate so that the pattern surface is on the insulating substrate. The process of laminating them so that they are in contact with each other and obtaining a laminate by thermoforming, and the process of dissolving and removing the aluminum base material in the laminate by alkali treatment, make it heat resistant and moisture resistant, with conductive parts and insulating parts being on the same plane. 1. A method for manufacturing a circuit board having excellent properties, impact resistance, etc., characterized in that the following terephthalic acid diallyl ester copolymer resin is used as the electrically insulating resin used in the electrically insulating board. The terephthalic acid diallyl ester copolymer resin refers to a copolymer resin of terephthalic acid diallyl ester and an aromatic hydrocarbon having at least one hydrogen atom at the benzyl position represented by the following formula (). However, in the above formula (), R ¹ and R ² each represent a group selected from the group consisting of a hydrogen atom and a lower alkyl group, and n = an integer of 1 to 3.