JP2010232310A - Resin box body with built-in electronic circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin box body embedded with circuit resin where a printed-wiring board and a box body resin have high adhesive properties, in the resin box body embedded with an electronic circuit in which the printed-wiring board is integrated with the box body resin. <P>SOLUTION: In the resin box body embedded with the electronic circuit, a thermoplastic resin layer is fused and formed on the printed-wiring board with the electronic circuit formed on one surface or both surfaces of a molding of a graft copolymer (A). The graft copolymer (A) is obtained by graft-polymerizing a 15 to 40 pts.mass aromatic polyvinyl monopolymer to a 60 to 85 pts.mass random or block copolymer composed of a component based on an &alpha;-olefin monomer or a conjugated diene monomer. A polyfunctional aromatic polyvinyl monomer in the whole aromatic polyvinyl monomer is set in 5 to 35 mass%. The thermoplastic resin layer is fused on the printed-wiring board by an insert molding method. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a resin casing that incorporates a circuit board and has a large space volume at the same time by using a resin casing containing an electronic circuit.

  In recent years, demands for various types of electronic devices have been accelerating, and various innovative technologies have been proposed and realized in response. In particular, since mobile communication devices such as mobile phones are assumed to be carried by users, they are required to be smaller and lighter if they have the same function, and more sophisticated if they have the same size. As a method to meet such demands for miniaturization, the internal volume of equipment that was previously wasted between the equipment casing and the printed wiring board can be effectively used as a space for various modules and batteries. Technology development to use is progressing.

  As one of them, there is a method of obtaining an electronic circuit built-in resin casing in which a printed wiring board and a casing resin are integrated by insert molding a casing resin on a printed wiring board on which various components are mounted. Known (for example, Patent Document 1). In insert molding, an insert product (in this case, a printed wiring board) is pre-loaded into a mold, and then the molten resin is injected to fix the insert product to the molten resin, so that the insert product and the resin are integrated. This is a method of manufacturing a composite part.

  When obtaining a resin housing with an electronic circuit by this method, if there is a gap between the printed wiring board and the housing resin, the air present inside the resin housing with an electronic circuit is used when the electronic device is used. Moisture inside may enter the voids, adversely affect the electronic circuit, such as corrosion, and adversely affect the reliability of the electronic equipment. In order to eliminate a gap between the printed wiring board and the housing resin, a thermosetting adhesive is used (for example, Patent Document 2). However, the presence of these adhesive components at the interface to be fused at the time of insert molding causes misalignment due to the flow of molten resin flowing in at high pressure and shrinkage deformation when the resin is cooled and solidified, and cohesive failure of the bonded portion And the reliability of the electronic device is adversely affected by the presence of the air gap. In recent years, various designs have been elaborated, and resin casings with curved surfaces and irregular shapes have been frequently used, and the printed wiring board is closely attached to the casing resin along the shape of the resin casing. Things are getting stricter.

  Regardless of the shape of the resin casing, there is a strong demand to obtain a resin casing with a built-in electronic circuit that has high adhesion between the printed wiring board and the casing resin and is highly reliable for electronic devices.

JP-A-63-080597 Japanese Patent Laid-Open No. 06-021594

  Accordingly, an object of the present invention is to provide a resin case with a built-in circuit resin in which a printed wiring board and a housing resin have high adhesion in a resin case with a built-in electronic circuit in which the printed wiring board and the housing resin are integrated. It is to provide.

  As a result of intensive studies in view of the above problems, the present inventors have obtained a circuit obtained by fusing and forming a casing of a thermoplastic resin layer on a printed wiring board using a graft copolymer having a specific composition. The knowledge that the above-described problems can be solved by the resin housing with resin is obtained, and the present invention has been completed.

That is, the present invention includes the following [1] and [2].
[1] Grafting 15 to 40 parts by mass of an aromatic vinyl monomer on 60 to 85 parts by mass of a random or block copolymer composed of an α-olefin monomer or a conjugated diene monomer. A graft copolymer obtained by polymerization, wherein the polyfunctional aromatic vinyl monomer is 5 to 35% by mass of the entire aromatic vinyl monomer. An electronic circuit built-in resin casing having a thermoplastic resin layer formed by fusion bonding on a printed wiring board in which an electronic circuit is formed on one side or both sides of a molded product.
[2] The resin housing with built-in electronic circuit according to [1], wherein the thermoplastic resin layer is fused on the printed wiring board by an insert molding method.

  In order to solve the above-mentioned problems, the thermoplastic resin has a melting point comparable to that of the housing resin at the time of insert molding, and can maintain the shape without showing rapid fluidity even when the melting point is exceeded. Resin was the main component of the printed wiring board. When the printed wiring board is made of a thermoplastic resin, it partially melts with the housing resin, and adhesion between different resins is obtained. In addition, since the printed wiring board is made of thermoplastic resin, it can be deformed to the same shape as the resin housing shape before insert molding, and can follow the housing shape that is bent or bent. Since it is possible to reduce the shape change before and after insert molding for wiring boards, distortion to the printed wiring board after insert molding is reduced, and high adhesion is exhibited between the printed wiring board and the housing resin. .

  According to the present invention, it is possible to provide a resin casing firmly integrated with a printed wiring board on which an electronic circuit is formed.

(A) is sectional drawing which shows the male type | mold and female type | mold which comprise the circuit board deformation | transformation metal mold | die for curving the copper clad board for printed wiring boards in an Example, (b) shows a circuit board deformation | transformation metal mold | die. Plan view. (A) is a sectional view showing an insert molding die, (b) is a sectional view showing a male die of the insert molding die, (c) is a sectional view showing a female die of the insert molding die, (d) ) Is a plan view showing a mold for insert molding. The perspective view which shows the resin housing | casing with a built-in electronic circuit.

Hereinafter, embodiments of the present invention will be described in detail.
The resin case with built-in electronic circuit of the present invention is a resin case having a function as an electronic circuit and a function as an electronic device case at the same time. This resin casing is composed of a printed wiring board on which an electronic circuit is formed and a resin casing made of a thermoplastic resin layer, and bonding between them is made of a thermoplastic resin that becomes a casing for the printed wiring board. This is achieved by insert molding. Further, the printed wiring board on which the electronic circuit is formed has a characteristic that it can be deformed into a shape along a housing shape having various shapes. Therefore, a special design such as a bent shape or a hemispherical curved surface can be obtained by insert-molding a thermoplastic resin (housing resin) on a printed wiring board that has been deformed into a shape after bonding in advance and an electronic circuit is formed. It is possible to obtain a resin casing to which a printed wiring board having an electronic circuit is bonded in a shape along the resin casing. The electronic device casing having such a configuration has a special design, increases the internal space volume of the apparatus, and is an effective casing for high functionality or light and thin.

In order to obtain the resin casing of the present invention, it is necessary to obtain a printed wiring board that satisfies the above functions and characteristics. Therefore, the main component is a graft copolymer (A) which is a thermoplastic resin, can be surface-modified after circuit formation, and exhibits a slow increase in fluidity even above the melting point. The printed wiring board which has is obtained. However, the graft copolymer (A) is a resin material that is hardly soluble in an organic solvent or the like. Therefore, it is not possible to adopt a general printed wiring board manufacturing method by an impregnation method. Therefore, the graft copolymer (A) is formed into a sheet, and a metal film is formed on a prepreg obtained by hot pressing a single or two sheets with an inorganic reinforcing material sandwiched between them. A substrate can be obtained. Here, the prepreg is generally a non-adhesive semi-adhesive material in which a reinforced plastic resin is mixed with a curing agent and other components in an appropriate ratio and impregnated in advance in a fabric-like reinforcing material such as glass cloth. This refers to the molding material in a cured state [Taisho Publishing Co., Ltd., Polymer Dictionary 5th Edition]. In the present embodiment, a non-adhesive molding material is obtained by a blending method similar to this definition, so that it is referred to as a prepreg even if it is not semi-cured using a curing agent.
<Graft copolymer (A)>
The graft copolymer (A) is an aromatic vinyl monomer in 60 to 85 parts by mass of a random or block copolymer composed of a monomer unit of an α-olefin monomer or a conjugated diene monomer. It is obtained by graft polymerization of 15 to 40 parts by mass.

  Fragrance that causes a π-electron interaction in a random or block copolymer comprising a monomer unit of an α-olefin monomer or a conjugated diene monomer, which is a constituent unit of the graft copolymer (A) In order to take the molecular form of a graft copolymer grafted with an aromatic vinyl monomer, it is considered that the aromatic vinyl monomer unit forms a domain with respect to the main chain structure. For this reason, only the partial solubility with respect to a solvent is shown, and it has the characteristic that it liquefies even if it is the temperature more than melting | fusing point, and it flows and does not leak.

  Examples of the α-olefin monomer include ethylene, propylene, butene, octene, 4-methylpentene-1, 2,4,4-methylpentene-1, and the like. Examples of the conjugated diene monomer include 1,3-butadiene and 2-methyl-1,3-butadiene.

  A copolymer used as a grafted body of the graft copolymer (A) (hereinafter referred to as a matrix polymer) is a random comprising monomer units of the above α-olefin monomer or conjugated diene monomer. Or it is a block copolymer and the monomer unit of the α-olefin monomer or the conjugated diene monomer may be used by mixing a plurality of different types. Moreover, the conjugated diene monomer unit in the matrix polymer may be partially hydrogenated.

  Examples of the aromatic vinyl monomer to be grafted onto the matrix polymer include monofunctional monomers such as styrene monomers such as styrene, p-methylstyrene, and p-ethylstyrene. Examples of the polyfunctional one include divinylbenzene. These monomers can be used alone or in combination of two or more.

  The ratio of the aromatic vinyl monomer in the graft copolymer (A) is 15 to 40% by mass, preferably 25 to 35% by mass. When this proportion is less than 15% by mass, the graft copolymer (A) strongly exhibits the characteristics of an α-olefin polymer and a conjugated diene polymer, and exhibits extremely high fluidity above the melting point. It becomes difficult to maintain the shape of the prepreg and control the thickness. On the other hand, when it is more than 40% by mass, it becomes very brittle when it is made from a prepreg into a molded product, and it becomes difficult to form a sheet.

  Furthermore, the polyfunctional aromatic vinyl monomer ratio in the aromatic vinyl monomer is 5 to 35 mass%, preferably 15 to 25 mass%. When the ratio of the polyfunctional aromatic vinyl monomer in the aromatic vinyl monomer is less than 5% by mass, the fluidity of the graft copolymer increases, and the heat cycle resistance of the resin casing with built-in electronic circuit is increased. Gets worse. On the other hand, if it is more than 35% by mass, it may become very brittle and difficult to form into a sheet when a prepreg is formed into a molded product.

  The molecular size of the graft copolymer (A) is appropriately determined based on fluidity because it does not form a linear polymer chain. The method for measuring fluidity is defined by the method described in the examples. The value of the melt mass flow rate (MFR) of the graft copolymer (A) is preferably 2 to 50 g / (10 min), more preferably 5 to 15 g / (10 min). When this MFR value is less than 2 g / (10 min), it is very brittle when used as a sheet or prepreg, and sufficient mechanical properties cannot be obtained. There is a problem that it is difficult to maintain the shape of the printed wiring board during deformation before molding, or a circuit shift occurs during insert molding.

  As the grafting method for producing the graft copolymer (A), any generally well-known chain transfer method, ionizing radiation irradiation method or the like may be employed. Among these methods, since the graft efficiency is high and secondary aggregation due to heat does not occur, the development of performance is more effective, and the production method is simple, so the impregnation graft polymerization method shown below is preferable. .

  When the impregnation graft polymerization method is employed, the graft copolymer (A) is usually produced as follows. First, 100 parts by mass of a matrix polymer formed from at least one monomer selected from α-olefin monomers and conjugated diene monomers is suspended in water. Separately, 5 to 400 parts by mass of the aromatic vinyl monomer are mixed with one or more kinds of radical copolymerizable organic peroxides described later with respect to 100 parts by mass of the aromatic vinyl monomer. 0.1 to 10 parts by mass and a radical polymerization initiator having a decomposition temperature of 40 to 90 ° C. for obtaining a half-life of 10 hours is the sum of aromatic vinyl monomer and radical copolymerizable organic peroxide A solution in which 0.01 to 5 parts by mass is dissolved with respect to 100 parts by mass is added.

  Next, the matrix copolymer is impregnated with the radical copolymerizable organic peroxide. Thereafter, the temperature of the aqueous suspension is increased under the condition that decomposition of the radical polymerization initiator does not substantially occur, and the aromatic vinyl monomer and the radical copolymerizable organic peroxide are co-polymerized in the matrix polymer. Polymerize to obtain the grafted precursor. Finally, the target graft copolymer can be obtained by kneading the grafted precursor under melting at 100 to 300 ° C.

  In this case, a polymer formed from at least one monomer selected from an α-olefin monomer and a conjugated diene monomer different from the matrix polymer separately from the graft polymer, or A graft copolymer can be obtained by mixing a copolymer or a polymer comprising an aromatic vinyl monomer and kneading the mixture at 100 to 300 ° C. under melting.

  The radical copolymerizable peroxide is a compound that has both the characteristics as a monomer capable of radical copolymerization in the molecule and the characteristics as an organic peroxide, preferably t-butylperoxyacryloyloxy. Examples include ethyl carbonate, t-butyl peroxymethacryloyloxyethyl carbonate, t-butyl peroxyallyl carbonate, t-butyl peroxymethallyl carbonate, and the like. Of these, t-butylperoxymethacryloyloxyethyl carbonate is preferred.

  As a method of forming the graft copolymer (A) to obtain a sheet-like graft copolymer (A), generally known methods such as a T-die method, an inflation molding method, a calender roll molding method, and a press molding method are used. Any method may be used, but a calendar roll forming method is more preferable. In particular, the sheet-like graft copolymer (A) having a uniform thickness can be obtained by calender roll molding at a temperature 20-30 ° C. higher than the melting point of the graft copolymer.

  The method for obtaining the prepreg from the sheet-like graft copolymer (A) may be any of the generally well-known methods such as the vacuum press method and the belt press method, but the vacuum press method is particularly preferable. . An inorganic reinforcing material is sandwiched between two sheet-like graft copolymers (A), and thermocompression bonding is performed at a temperature and pressure at which the sheet-like graft copolymer (A) and the inorganic reinforcing material are sufficiently heat-sealed. Do. The temperature of thermocompression bonding is usually in the range of 160 to 300 ° C. The pressure is usually in the range of 2 to 10 MPa.

  The prepreg used in the present invention can be used by adding ordinary additives such as a lubricant, a plasticizer, a crystal nucleating agent, an ultraviolet light inhibitor, a colorant, and a flame retardant, as long as the effects of the present invention are not impaired. . The method of adding these additives can be easily performed by kneading into the graft copolymer (A) from the viewpoint of miscibility with the entire prepreg. The method for kneading the additive is not particularly limited, but the additive can be mixed using a Banbury mixer, a pressure kneader, a roll, a single or twin screw extruder having a heating function and a kneading function. Above all, using a twin screw extruder, supply the graft copolymer, antioxidant, and flame retardant from the main hopper, melt knead, pass the rod-shaped product discharged from the die through the pelletizer, and granulate A method obtained as a product (pellet) is preferable because it is simple and inexpensive. The temperature at that time may be a temperature at which the graft copolymer (A) is sufficiently softened, and is usually in the range of 150 to 300 ° C.

  As the inorganic reinforcing material, an insulating coating treatment or a silane compound (chlorosilane, alkoxysilane, organofunctional silane, silazane), titanate-based, aluminum-based coupling agent, or the like may be used.

  The compounding amount of the inorganic reinforcing material in the metal-clad substrate for a printed wiring board is preferably 0 to 85% by mass, and more preferably 55 to 65% by mass. When the blending amount exceeds 85% by mass, the volume fraction of the inorganic reinforcing material in the prepreg is increased, and the metal film is poorly formed and the adhesion with the housing resin at the time of insert molding is impaired.

  As a method for obtaining a metal-clad substrate for a printed wiring board from the sheet-like graft copolymer (A) or prepreg, a method of forming a plating on the surface of the sheet-like graft copolymer (A) or prepreg or a metal film Any method such as a vacuum pressing method and a belt pressing method may be used, but a metal-clad substrate for a printed wiring board can be easily obtained by selecting the vacuum pressing method. From the metal-clad substrate for a printed wiring board obtained by this method, a printed wiring board in which an electronic circuit is formed by a generally known manufacturing method such as a subtractive method, an additive method, or a semi-additive method can be obtained.

  The metal film used for the metal-clad board for printed wiring boards is a film of a single substance or an alloy such as copper, aluminum, iron, nickel, zinc, etc., and chromium, molybdenum, etc. for rust prevention as necessary. The metal may be subjected to surface treatment. About these metal films, what was manufactured by conventionally well-known techniques, such as an electrolysis method and a rolling method, can be used, and those thickness is about 0.003-1.5 mm normally. Further, the metal film may be formed on the outer layer of the prepreg by a vacuum deposition method or a plating method.

  The printed wiring board obtained from the metal-clad substrate for printed wiring board is not a simple shape like a box shape configured by combining planes, but a device casing (resin casing) having a shape formed by a curved surface or the like. In order to integrate the body without occupying the space inside the housing, it is advantageous that the shape of the device housing and the shape of the printed wiring board are the same. This is because the space generated between the resin casing and the printed wiring board during insert molding is reduced, so that peeling due to resin shrinkage after molding is less likely to occur, and the volume that the printed wiring board occupies the internal space of the casing This is because there is an advantage that the housing volume is increased because of a smaller value.

  The housing resin that is insert-molded on the printed wiring board may be any thermoplastic resin that is generally insert-moldable. However, considering the adhesion with the printed wiring board during insert molding, it is the main component of the printed wiring board. A resin that is insert-molded at a temperature higher than the melting point of a certain graft copolymer (A) is selected. Since the melting point of the graft copolymer (A) is about 140 to 175 ° C, the molding temperature of the resin to be insert-molded is preferably about 150 to 300 ° C. When the molding temperature of the resin to be insert-molded is lower than 150 ° C., the adhesive force with the resin surface of the printed wiring board becomes small, and normal bonding cannot be performed. In addition, when the molding temperature of the resin to be insert-molded is higher than 300 ° C., the electronic circuit formed on the printed wiring board may be displaced due to the resin temperature at the time of the insert molding, or the mounting part may be thermally damaged.

  Examples of the thermoplastic resin suitable for such insert molding include poly (acrylonitrile-butadiene-styrene) (ABS resin), polycarbonate, cyclic polyolefin, polyoxymethylene, polybutylene terephthalate, polyphenylene sulfide, and the like.

As a pretreatment for insert molding of the housing resin on the printed wiring board, a surface treatment such as UV-O ₃ (ultraviolet-ozone) treatment may be performed on the surface of the printed wiring board that contacts the housing resin. The UV-O ₃ treatment is usually performed at an illuminance of 1000 to 4000 mJ / cm ² of ultraviolet light (wavelength 254 nm). If the illuminance of ultraviolet light is too low, the effect of the surface treatment cannot be obtained. is there.

  As a method of insert-molding the housing resin on the printed wiring board, a method is usually selected in which the printed wiring board is placed in a mold and the housing resin is injection-molded in the mold. In this case, the injection temperature of the housing resin is suitably a temperature that does not cause the printed wiring board to be excessively melted, and specifically, with respect to the melting point of the graft copolymer (A) constituting the printed wiring board. An injection temperature of about +50 to + 150 ° C. is appropriate.

  By satisfying the above-described steps and conditions, a resin casing containing a printed wiring board on which an electronic circuit is formed can be obtained.

Hereinafter, the embodiment will be described more specifically with reference examples, examples, and comparative examples.
First, the test method of the resin housing with a built-in electronic circuit used in Examples and Comparative Examples is shown.
[Measurement of fluidity of resin]
Measured using a melt indexer (manufactured by Toyo Seiki Seisakusho Co., Ltd.) based on JIS K 7210: 1999 “Plastics—Test methods for melt mass flow rate (MFR) and melt volume flow rate (MVR) of thermoplastics”. MFR (g / 10 min) was measured under a load of 98.1 N (10 kg · f). Unless otherwise specified, the measurement was performed at a resin temperature of 230 ° C.
[appearance]
After the housing resin is insert-molded on the printed wiring board (circuit board), if the adhesion strength between the two materials is insufficient, the interface resin will be peeled off due to the cooling and shrinkage of the housing resin after the insert molding. Since a gap is formed, a white peeling portion is observed. Further, since the high-temperature casing resin is in contact with the printed wiring board instantaneously at the time of insert molding, there is a possibility that the resin portion of the printed wiring board flows and circuit displacement or circuit cutting occurs. Furthermore, circuit displacement and cutting due to cooling and shrinkage of the resin casing after insert molding can be considered. The appearance of the resin casing with built-in electronic circuit was evaluated according to the following evaluation criteria.
(Evaluation criteria)
○: No peeling, circuit deviation, cutting, etc. ×: Peeling, circuit deviation, cutting, etc. [heat cycle resistance]
After the housing resin is insert-molded on the printed wiring board, even if the adhesion strength is high enough to cause delamination between the two materials, if the adhesion strength is potentially low, interfacial delamination is formed due to further thermal load . In the present invention, by performing a thermal shock test (heat cycle resistance test) as a thermal load, a thermal load is applied to the resin casing with built-in electronic circuit, and the adhesion strength between the printed wiring board and the casing resin is evaluated. The following evaluation criteria were used. As conditions for the heat cycle resistance test, conditions were selected in which the environment of the sample was repeated at −30 ° C. and + 85 ° C. every 30 min.
(Evaluation criteria)
○: No peeling for 100 cycles or more ×: Peeling occurred up to 100 cycles Next, a method for producing the graft copolymer (A) used in Examples and Comparative Examples is shown as a reference example.
<Reference Example 1, Production of Graft Copolymer (A), and Production of Sheet Molded Product of Graft Copolymer (A)>
In a stainless steel autoclave having an internal volume of 5 liters, 2500 g of pure water was added, and 2.5 g of polyvinyl alcohol was dissolved as a suspending agent. Into this, 700 g of polypropylene was put and stirred and dispersed. Separately, 2.0 g of benzoyl peroxide as a radical polymerization initiator, 7.5 g of t-butylperoxymethacryloyloxyethyl carbonate as a radical copolymerizable organic peroxide, 100 g of divinylbenzene as an aromatic vinyl monomer and styrene This was dissolved in 200 g, and this solution was charged into the autoclave and stirred. Next, the temperature of the autoclave was raised to 85 to 95 ° C., and stirred for 2 hours to impregnate polypropylene with an aromatic vinyl monomer containing a radical copolymerization initiator and a radical polymerizable organic peroxide. Next, the temperature was lowered to 75 to 85 ° C., and maintained at that temperature for 5 hours to complete the polymerization. After filtration, washed with water and dried, a grafted precursor was obtained.

  Subsequently, this grafting precursor was extruded at 210 ° C. with a Laboplast Mill single screw extruder (manufactured by Toyo Seiki Seisakusho Co., Ltd.) and grafted to obtain a graft resin. Furthermore, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, neopentanetetraylbis (2 , 6-di-t-butyl-4-methylphenyl) phosphite was dry blended in an amount of 100 g each, and then a coaxial twin screw extruder [TEX-30α, ( Supplied to Nippon Steel Works, Ltd.] and granulated after extrusion to obtain a graft copolymer (A). The MFR of this graft copolymer (A) was 8 g / (10 min). Furthermore, the graft copolymer (A) was stretched at 170 ° C. with a calender roll device (manufactured by Nippon Roll Manufacturing Co., Ltd.) to obtain a sheet-like molded product of the graft copolymer (A). Table 1 shows the composition of the graft copolymer (A) constituting the sheet-like molded product. The trade name of each component is shown below.

Polypropylene: “Sun Allomer PM671A” [trade name, manufactured by Sun Allomer Co., Ltd.]
Benzoyl peroxide: “Niper BW” [trade name, manufactured by NOF Corporation, 75% pure water-containing product]
t-Butylperoxymethacryloyloxyethyl carbonate [manufactured by NOF Corporation, 40% toluene solution]
1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene: “Irganox 1330” [trade name, manufactured by Ciba Japan Co., Ltd.]
Neopentanetetraylbis (2,6-di-t-butyl-4-methylphenyl) phosphite: “ADK STAB PEP-36” [trade name, manufactured by ADEKA Corporation]
<Reference Examples 2-9>
By the same method as in Reference Example 1, a sheet-like molded product was obtained using the graft copolymer (A). Table 1 shows the composition of these graft copolymers (A).
<Reference Examples 10 and 11>
Although it is a resin different from the graft copolymer (A), it can be formed into a sheet shape by a calender roll. From the sheet, a metal-clad substrate for a printed wiring board, or a prepreg and a printed wiring board using the same A thermoplastic resin capable of obtaining a metal-clad substrate was shown.

表１中の略号を以下に示す。

Abbreviations in Table 1 are shown below.

PP: Polypropylene “Sun Allomer PM671A” [trade name, manufactured by Sun Allomer Co., Ltd.]
St: Styrene DVB: Divinylbenzene TPX: Poly-4-methylpentene-1 “TPX RT18” [trade name, manufactured by Mitsui Chemicals, Inc.]
MeSt: p-methylstyrene SEPS: Styrene-ethylene-propylene-styrene copolymer “Septon 2007” [trade name, Kuraray Co., Ltd.]
Example 1
After performing UV-O ₃ treatment on both surfaces of the sheet-like molded product of Reference Example 1 using a UV irradiation machine PM20014B-3 type (lamp: low-pressure mercury lamp EUV200US-55 type) manufactured by Sen Engineering Co., Ltd. Rolled copper foil with a thickness of 18 μm (Fukuda Metal Foil Powder Co., Ltd.) sandwiched between two sheet-like molded products, thermocompression-bonded using a vacuum press at 200 ° C, and a copper-clad substrate for printed wiring boards Got.

  Next, this copper-clad board for printed wiring boards is cut into a size of 30 mm in length and 50 mm in width, and unnecessary portions of the copper foil on the surface are removed using a 45 ° Be ferric chloride solution to remove the short axis. A circuit board having a conductor as an electronic circuit imitating a microstrip line having a line width of 0.05 mm and a line length of 45 mm starting from a position in the center of the direction and 2.5 mm in the long axis direction was obtained. Further, as shown in FIGS. 1 (a) and 1 (b), a circuit board 11 as a printed wiring board is modified from a circuit board in which a surface of an electronic circuit 12 having conductive wires is composed of a male mold 13 and a female mold 14. The evaluation circuit board 16 is arranged so as to be on the female mold 14 side of the metal mold 15 (see the one-dot chain line in FIG. 1A) and is curved by pressing under conditions of 140 ° C., 10 min, 2.0 MPa. [Refer to the two-dot chain line in FIG. 1 (a)].

Next, the curved evaluation circuit board 16 obtained in the above process was subjected to surface modification using a UV-O ₃ treatment apparatus on the side on which the housing resin was insert-molded, and then FIG. ) To (d), insert molding was performed using an insert molding die 19 composed of a convex mold 17 and a concave mold 18. That is, the evaluation circuit board 16 curved toward the convex mold 17 side of the cavity 20 formed by the convex mold 17 and the concave mold 18 is disposed so that the surface of the electronic circuit 12 faces the concave mold 18, and then melted from the gate 21. Insert molding was performed by injecting a thermoplastic resin (insert resin) to mold the thermoplastic resin layer (resin casing) 23. Then, an electronic circuit built-in resin casing 22 in which the evaluation circuit board 16 having the electronic circuit 12 was in close contact with the inner side surface of the thermoplastic resin layer 23 having a concave groove shape as shown in FIG. 3 was obtained. At this time, the insert resin was ABS shown below, and the injection temperature was 250 ° C. In the electronic circuit built-in resin housing 22, the electronic circuit 12 is formed between the thermoplastic resin layer 23 and the evaluation circuit board 16.

ABS: Poly (acrylonitrile-butadiene-styrene) resin “Toyolac 100” (trade name, manufactured by Toray Industries, Inc.), injection temperature 250 ° C.
About the obtained resin case 22 with a built-in electronic circuit, the external appearance and heat cycle resistance were evaluated by the test method described above, and the results are shown in Table 2.
(Example 2)
After performing UV-O ₃ treatment on one side of the sheet-like molded product of Reference Example 1 in the same manner as in Example 1, two sheets of the molded product were made of glass cloth [“Type 1067”, trade name And Asahi Kasei Electronics Co., Ltd.] were sandwiched and thermocompression bonded using a vacuum press at 200 ° C. to obtain a prepreg. Further, a copper-clad board for a printed wiring board was obtained by using the same method as in Example 1 for this prepreg, and further a circuit board 11, its curved deformation, and an electronic circuit built-in resin casing 22 by insert molding were obtained. About the obtained resin case 22 with a built-in electronic circuit, the external appearance and heat cycle resistance were evaluated by the test method described above, and the results are shown in Table 2. Abbreviations in Table 2 are shown below.

# 1067: Glass cloth ["Type 1067", trade name, manufactured by Asahi Kasei Microdevices Corporation]
PC: Polycarbonate resin “Panlite K-1300Y” [trade name, manufactured by Teijin Chemicals Ltd.], injection temperature 290 ° C.
ZEONOR: Hydrogenated polynorbornene resin “ZEONOR 1020R” (trade name, manufactured by Nippon Zeon Co., Ltd.), number average molecular weight of about 1000, injection temperature of 200 ° C.
(Examples 3 to 8)
Using the predetermined graft copolymer (A) shown in Table 1, an electronic circuit built-in resin casing 22 was obtained in the same manner as in Example 1 or 2. About the obtained resin case 22 with a built-in electronic circuit, the external appearance and heat cycle resistance were evaluated by the test method described above, and the results are shown in Table 2. Abbreviations in Table 2 are shown below.

# 106: Glass cloth [“Type 106”, trade name, manufactured by Asahi Kasei Electronics Co., Ltd.]
# 1037: Glass cloth ["Type 1037", trade name, manufactured by Asahi Kasei Microdevices Corporation]

表２に示した結果より、実施例１〜８に示した電子回路内蔵樹脂筐体２２は、インサート成形時の回路損傷が無く正常に使用可能であり、プリント配線板と樹脂筐体間の密着性が十分であることが示された。
（比較例１〜６）
実施例１または２と同様の方法を用い、表３に示す構成にて電子回路内蔵樹脂筐体２２を得た。得られた電子回路内蔵樹脂筐体２２について、前述の試験方法にて外観および耐ヒートサイクルを評価し、それらの結果を表３に示した。

From the results shown in Table 2, the electronic circuit built-in resin case 22 shown in Examples 1 to 8 can be used normally without circuit damage during insert molding, and the printed wiring board and the resin case are in close contact with each other. Sex was shown to be sufficient.
(Comparative Examples 1-6)
Using the same method as in Example 1 or 2, a resin housing 22 with a built-in electronic circuit was obtained with the configuration shown in Table 3. About the obtained resin case 22 with a built-in electronic circuit, the external appearance and heat cycle resistance were evaluated by the test method described above, and the results are shown in Table 3.

表３に示した結果より、比較例１では、グラフト共重合体（Ａ）においてマトリックス重合体にグラフトされる芳香族系ビニル単量体の割合が多く、シート状成形が困難であるため、電子回路内蔵樹脂筐体２２を得ることができなかった。比較例２では、グラフト共重合体（Ａ）においてマトリックス重合体にグラフトされる芳香族系ビニル単量体の割合が少なく、流動性の高いグラフト共重合体（Ａ）となる。このグラフト共重合体（Ａ）から得られた回路基板１１は熱に対して流動性が高くなり、インサート成形時に射出される筐体樹脂の熱によって流動し、湾曲した評価用回路基板１６表面に形成された電子回路１２の位置ズレや断線が発生した。

From the results shown in Table 3, in Comparative Example 1, the ratio of the aromatic vinyl monomer grafted to the matrix polymer in the graft copolymer (A) is large, and sheet-shaped molding is difficult. The resin housing 22 with built-in circuit could not be obtained. In Comparative Example 2, the ratio of the aromatic vinyl monomer grafted to the matrix polymer in the graft copolymer (A) is small, and the graft copolymer (A) has high fluidity. The circuit board 11 obtained from the graft copolymer (A) is highly fluid with respect to heat, and flows due to the heat of the casing resin injected at the time of insert molding. Misalignment and disconnection of the formed electronic circuit 12 occurred.

  In Comparative Example 3, since the polyfunctional vinyl monomer is not used in the aromatic vinyl monomer grafted to the matrix polymer, the circuit board 11 in the obtained resin housing 22 with built-in electronic circuit is used. The fluidity was large, the resin flowed during the heat cycle test, and positional displacement and disconnection of the electronic circuit 12 formed on the surface of the circuit board 11 occurred. In Comparative Example 4, the aromatic vinyl monomer grafted to the matrix polymer has a large proportion of the polyfunctional vinyl monomer, and it is difficult to form a sheet. I couldn't.

  In Comparative Example 5, the copper-clad substrate for printed wiring board was not obtained from the sheet of graft copolymer (A), but instead a copper-clad substrate was produced using a film made of polypropylene. The displacement of the electronic circuit 12 formed on the surface of the evaluation circuit board 16 curved due to the heat of the body resin and disconnection occurred. In Comparative Example 6, a styrene-ethylene-propylene-styrene copolymer made of polypropylene having an aromatic block in the main chain is used instead of obtaining a metal-clad substrate for a printed wiring board from the graft copolymer (A) sheet. A copper-clad substrate was produced using a film made of coalescence. Therefore, the curved evaluation circuit board 16 in the obtained resin case 22 with built-in electronic circuit has a large fluidity, and the resin flows during the heat cycle test, so that the electronic circuit 12 formed on the surface of the evaluation circuit board 16 is formed. A position shift or disconnection occurred.

  DESCRIPTION OF SYMBOLS 11 ... Circuit board as a printed wiring board, 12 ... Electronic circuit, 16 ... Circuit board for evaluation as a printed wiring board, 22 ... Resin housing | casing with an electronic circuit, 23 ... Thermoplastic resin layer.

Claims (2)

15 to 40 parts by mass of an aromatic vinyl monomer is graft-polymerized to 60 to 85 parts by mass of a random or block copolymer composed of a structural unit based on an α-olefin monomer or a conjugated diene monomer. The graft copolymer is a molded product of the graft copolymer (A) in which the polyfunctional aromatic vinyl monomer is 5 to 35% by mass of the entire aromatic vinyl monomer. An electronic circuit built-in resin housing having a thermoplastic resin layer fused and formed on a printed wiring board having an electronic circuit formed on one side or both sides. The resin case with a built-in electronic circuit according to claim 1, wherein the thermoplastic resin layer is fused on the printed wiring board by an insert molding method.

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