JP6922968B2 - Manufacturing method of printed wiring board with metal reinforcing plate, laminate, and printed wiring board with metal reinforcing plate - Google Patents

Description

The present invention relates to a method for manufacturing a printed wiring board with a metal reinforcing plate, a laminate used in the manufacturing method, and a printed wiring board with a metal reinforcing plate.

With the further improvement and miniaturization of electronic devices such as OA devices and communication devices, flexible printed wiring boards (hereinafter referred to as "FPC") utilize the bendable characteristics of electronic devices. It is used to incorporate electronic circuits in narrow and complicated internal boards and the like. It is common to use an FPC provided with an electromagnetic wave shield layer that shields the generated electromagnetic waves for this electronic circuit, but this is due to the recent increase in the amount of information in the electronic circuit and the increase in frequency and the miniaturization of the electronic circuit. Therefore, electromagnetic wave countermeasures are becoming more important.

As an FPC having an electromagnetic wave shield layer, Patent Document 1 discloses an FPC in which a conductive metal reinforcing plate and a ground circuit are connected by a conductive adhesive. Specifically, the metal reinforcing plate is electrically connected to the ground circuit by attaching a metal reinforcing plate such as stainless steel to the FPC using a conductive adhesive sheet. With such a configuration, an FPC having a good electromagnetic wave shielding property can be obtained, and a circuit signal can be stably transmitted. Patent Document 2 discloses a technique relating to a conductive adhesive containing a thermosetting resin and a conductive filler.

International Publication No. 2014/010524 International Publication No. 2019/031394

When a metal reinforcing plate is attached to an FPC using a conductive adhesive, the conductive adhesive is required to have embedding property in the opening of the insulating protective film. Specifically, when the laminate in which the metal reinforcing plate / conductive adhesive / FPC is laminated is hot-pressed at a predetermined press temperature (for example, 170 ° C.), the softening of the conductive adhesive is insufficient at the press temperature. If there is, there is a problem that the filling property of the conductive adhesive in the opening is deteriorated. In particular, when the opening is small, the filling property is remarkably deteriorated and conduction is poor. Therefore, it is necessary to soften the conductive adhesive at the press temperature (for example, 170 ° C.).
On the other hand, if the conductive adhesive seeps out from between the metal reinforcing plate and the FPC due to the pressing pressure in the pressing process, it causes a poor appearance and a short circuit, which has been a problem.

On the other hand, if the conductive adhesive is softened, the conductive adhesive oozes excessively from between the metal reinforcing plate and the FPC, causing a poor appearance and a short circuit.

In view of the above problems, an object of the present invention is a method for manufacturing a printed wiring board with a metal reinforcing plate, which has good filling property of a conductive adhesive in an opening and does not have a poor appearance and a short circuit, and a method for manufacturing the printed wiring board. It is an object of the present invention to provide a laminate used in a manufacturing method and a printed wiring board with a metal reinforcing plate.

As a result of diligent studies by the present inventors, they have found that the problems of the present invention can be solved in the following aspects, and have completed the present invention.
In the method for manufacturing a printed wiring board with a metal reinforcing plate according to one aspect of the present invention, the circuit pattern including the ground circuit and the circuit pattern are insulated and protected, and above the printed wiring board on which an insulating protective film having an opening is formed. In addition, a conductive adhesive containing a binder resin and a conductive filler that is softened by heat, a metal reinforcing plate, and a laminate having a cushioning material in this order are provided so that the wiring plate and the conductive adhesive face each other. Placement step [1],
The laminate is hot-pressed, and the gland circuit and the metal reinforcing plate are adhered to each other by a conductive adhesive through an opening provided in the insulating protective film, and the gland circuit and the metal reinforcing plate are electrically connected. Step of connecting [2],
Further, the step [3] of peeling off the cushion material of the laminated body is provided.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a printed wiring board with a metal reinforcing plate which has good filling property of a conductive adhesive into an opening and does not have a poor appearance and a short circuit.

It is a figure for demonstrating the preparation process of the laminated body which concerns on embodiment. It is a figure for demonstrating the manufacturing method of the printed wiring board with a metal reinforcing plate which concerns on embodiment. It is sectional drawing of the printed wiring board with a metal reinforcing plate which concerns on embodiment. It is sectional drawing of the laminated body which concerns on embodiment. It is sectional drawing of the printed wiring board with a metal reinforcing plate. It is a top view of the printed wiring board. It is a top view which shows the state which attached the metal reinforcing plate to the printed wiring board.

The sheet in the present specification includes not only a sheet defined in JIS but also a film. The following description and drawings have been simplified as appropriate to clarify the description. Unless otherwise specified, the various components mentioned in the present specification may be used independently or in combination of two or more.
In this specification, the "printed wiring board" may be abbreviated as "wiring board".
Hereinafter, examples of embodiments of the present invention will be described.

<< Manufacturing method of printed wiring board with metal reinforcing plate >>
A method of manufacturing a printed wiring board with a metal reinforcing plate will be described with reference to FIGS. 1 and 2. FIG. 2 shows a manufacturing process when a metal reinforcing plate is attached to a printed wiring board using a conductive adhesive. The details of the materials constituting each member will be described later. Further, in the present specification, the "conductive adhesive" indicates a conductive adhesive before thermosetting, and the "conductive adhesive layer" is a layer obtained by thermosetting the conductive adhesive (that is, that is). , Conductive adhesive after thermosetting).

<Laminate body preparation process>
First, as shown in the preparation step [1] of FIG. 1, a conductive adhesive sheet 13 in which a conductive adhesive 12 is laminated on a peelable film 11 and a metal reinforcing plate 14 are prepared. Then, as shown in the preparation step [2], the conductive adhesive 12 side of the conductive adhesive sheet 13 is attached to the metal reinforcing plate 14, and the conductive adhesive sheet 13 is temporarily attached to the metal reinforcing plate 14. The temperature at which the conductive adhesive sheet 13 is temporarily attached to the metal reinforcing plate 14 (temporary application temperature) can be, for example, 110 ° C. to 150 ° C., preferably 130 ° C. After the temporary attachment, the conductive adhesive 12 is in a semi-cured state.

Next, as shown in the preparation step [3], the peelable film 11 is peeled off to expose the surface of the conductive adhesive 12 on the opposite side to the metal reinforcing plate 14. After that, the preliminary laminate 15 of the conductive adhesive 12 and the metal reinforcing plate 14 is cut to a predetermined size (the cutting line is indicated by reference numeral 18). Cutting of the pre-laminated body 15 can be carried out by using, for example, punching. The peelable film 11 may be peeled off after the cutting step.

<Step [1]>
In step [1], a binder resin and a conductive filler that are softened by heat are placed above the printed wiring board on which the circuit pattern including the ground circuit and the circuit pattern are insulated and protected and the insulating protective film having an opening is formed. This is a step of arranging a laminate having a conductive adhesive, a metal reinforcing plate, and a cushioning material in this order so that the wiring plate and the conductive adhesive face each other.

In the present invention , the conductive adhesive, the metal reinforcing plate, and the cushioning material are arranged and used in order above the printed wiring plate, or the cushioning material is further arranged on the laminate of the conductive adhesive and the metal reinforcing plate. In the case of using the conductive adhesive by arranging a laminate of the metal reinforcing plate and the cushioning material, the conductive adhesive, the metal reinforcing plate, and the cushioning material are arranged in this order at the time of hot pressing. I just need to be able to.

Specifically, for example, as shown in step [1] of FIG. 2, the preliminary laminate 15 cut to a predetermined size is arranged on the wiring board 20. Further, the laminated body 17 is formed by laminating the cushion material 16 on the upper surface of the metal reinforcing plate. Here, the wiring board 20 has a structure in which the lower insulating film 21 and the upper insulating film 22 are bonded with an insulating adhesive 23. A signal circuit 24 and a ground circuit 25 are formed on the insulating film 21, and an opening (through hole) 27 is formed above the ground circuit 25. That is, the ground circuit 25 is arranged on the insulating film 21, and a part of the ground circuit 25 is exposed through the opening 27. The laminated body 17 is arranged above the opening 27 of the wiring board 20.

<Step [2]>
In the step [2], the laminate is hot-pressed, and the gland circuit and the metal reinforcing plate are adhered to each other by a conductive adhesive through an opening provided in the insulating protective film of the printed wiring board, and the gland is attached. This is the process of electrically connecting the circuit and the metal reinforcing plate.

Specifically, for example, as shown in step [2] of FIG. 2, following step [1], the laminate of the laminate 17 / wiring board 20 is brought to a predetermined temperature (for example, 150 to 190 ° C., preferably 170 ° C.). ) To heat press (heat / pressurize). As a result, the conductive adhesive 12 is softened and embedded in the opening 27 of the insulating protective film. When the softened conductive adhesive 12 is filled in the opening 27, the conductive adhesive 12 comes into contact with the ground circuit 25 exposed by the opening 27. After the hot pressing, the conductive adhesive 12 is cured to bond the metal reinforcing plate 14 and the wiring plate 20, and the ground circuit and the metal reinforcing plate are electrically connected. On the other hand, the cushion material 16 flows by heat and pressure and flows into the side surface side of the metal reinforcing plate 14 and the conductive adhesive 12 to suppress the exudation of the conductive adhesive 12. Therefore, the cushion material 16 flows to the side surface of the conductive adhesive 12 before the conductive adhesive 12 seeps out from the metal reinforcing plate during hot pressing, and dams up the seepage. In this state, the cushion material needs to have a hardness (viscoelasticity) that suppresses the exudation of the conductive adhesive 12.

The pressure at the time of hot pressing is preferably about 3 to ^{30 kg / cm 2.} As the apparatus used for the hot press, a flat plate crimping machine or a roll crimping machine can be used. The heat pressing time is not particularly limited as long as the laminated body of the cushion material 16 / metal reinforcing plate 14 / conductive adhesive 12 / wiring plate 20 is sufficiently adhered, but is usually from 1 minute to 1 minute. It takes about 1 hour. When the heat pressing time is short, it is preferable to heat the conductive adhesive 12 in an oven at 150 to 190 ° C. for 30 minutes to 3 hours after the heat pressing to finally cure the conductive adhesive 12.

<Step [3]>
The step [3] is a step of peeling off the cushioning material of the laminated body.
After the hot pressing, as shown in step [3] of FIG. 2, the cushion material whose temperature has dropped and whose fluidity has disappeared is peeled off by a suction peeling device or manually.
As a result, as shown in FIG. 3, a printed wiring board with a metal reinforcing plate having an electromagnetic wave shielding property in which the metal reinforcing plate 14 and the ground circuit 25 of the wiring plate 20 are electrically connected via a conductive adhesive 12. 30 can be manufactured.

Subsequently, the details of the materials constituting each member will be described.
<Laminated body>
The laminate according to the present embodiment is used in the above-mentioned method for manufacturing a printed wiring board with a metal reinforcing plate, and the cushion material, the metal reinforcing plate, and the conductive adhesive are laminated in this order. As shown in FIG. 4A, each member may have the same size, but as shown in FIG. 4B, a mode in which the cushioning material is made larger than the metal reinforcing plate and the conductive adhesive improves the exudability. It is preferable from the viewpoint of improvement.
Further, in the laminate of the present invention, the storage elastic modulus of the cushion material is 10 MPa or more and 100 MPa or less at 170 ° C., and the storage elastic modulus of the conductive adhesive is 2 MPa or more and 50 MPa or less at 170 ° C. It is preferable that the storage elastic modulus of the material is higher than the storage elastic modulus of the conductive adhesive in terms of exudability.

As described above, the laminate may be a lamination step of laminating the cushion material after forming the preliminary laminate 15 composed of the metal reinforcing plate 14 and the conductive adhesive 12, and the laminate is formed in advance before being placed on the wiring board. You may. The details of each layer will be described below.

(Cushion material)
The cushion material has a role of uniformly transmitting the press pressure of the heat press machine to the metal reinforcing plate and the conductive adhesive, flowing during the heat press, and suppressing the seepage of the conductive adhesive.

The storage elastic modulus of the cushion material is preferably 10 MPa or more and 100 MPa or less, more preferably 12 MPa or more and 90 MPa or less, and further preferably 15 MPa or more and 70 MPa or less at 170 ° C. Within the above range, the exudation of the conductive adhesive of the heat press is suppressed. Specifically, as shown in FIG. 4B, when the storage elastic modulus of the cushion material exceeds 100 MPa, the conductive adhesive 12 softens and easily exudes before the cushion material flows. On the other hand, if the storage elastic modulus is less than 10 MPa, the hardness of the cushion material is insufficient, and it becomes difficult to suppress exudation due to softening of the conductive adhesive.

The storage elastic modulus of the cushioning material according to the present embodiment can be measured as follows. That is, a dynamic viscoelasticity measuring device is used to measure changes in the storage elastic modulus (E'), loss elastic modulus (E "), and loss tangent (tan δ) of the cushioning material in the temperature range of 25 to 200 ° C., and the temperature. It can be obtained by extracting the storage elastic modulus (E') in.

The cushion material can be formed of a thermoplastic resin composition containing a thermoplastic resin. Further, the thermoplastic resin composition may contain a plasticizer, a thermosetting agent, an inorganic filler and the like in addition to the thermoplastic resin.

Examples of the thermoplastic resin include polyolefin resins, acid-modified polyolefin resins grafted with acids, copolymer resins of polyolefins and unsaturated esters, vinyl resins, styrene / acrylic resins, diene resins, cellulose resins, and the like. Examples thereof include polyamide resin, polyurethane resin, polyester resin, polycarbonate resin, polyimide resin, and fluororesin.
Among these, polyolefin-based resins, acid-modified polyolefin-based resins grafted with acids, copolymer resins of polyolefins and unsaturated esters, and vinyl-based resins are preferable.
As the thermoplastic resin, one type can be used alone, or two or more types can be mixed at an arbitrary ratio as required.

The polyolefin-based resin is preferably a homopolymer or copolymer such as ethylene, propylene, or α-olefin compound. Specific examples thereof include low-density polyethylene, ultra-low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene homopolymer, polypropylene copolymer and the like.
Among these, polyethylene resin and polypropylene resin are preferable, and polyethylene resin is more preferable.

The acid-modified polyolefin resin is preferably a polyolefin resin grafted with maleic acid, acrylic acid, methacrylic acid, itaconic acid and the like.
Among these, maleic acid-modified polyolefin resin is preferable.

Examples of the unsaturated ester in the copolymer resin of the polyolefin and the unsaturated ester include methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, isooctyl acrylate, methyl methacrylate, isobutyl methacrylate, and dimethyl maleate. Examples thereof include diethyl maleate and glycidyl methacrylate.
Among these, an ethylene-glycidyl methacrylate copolymer resin composed of ethylene as the polyolefin and glycidyl methacrylate as the unsaturated ester is preferable.

As the vinyl resin, a polymer obtained by polymerizing a vinyl ester such as vinyl acetate and a copolymer of a vinyl ester and an olefin compound such as ethylene are preferable. Specific examples thereof include ethylene-vinyl acetate copolymer, ethylene-vinyl propionate copolymer, and partially saponified polyvinyl alcohol.
Of these, ethylene-vinyl acetate copolymer is preferable.

The styrene / acrylic resin is preferably a homopolymer or copolymer composed of styrene, (meth) acrylonitrile, acrylamides, maleimides and the like. Specific examples thereof include syndiotactic polystyrene, polyacrylonitrile, and acrylic copolymers.

The diene-based resin is preferably a homopolymer or copolymer of a conjugated diene compound such as butadiene or isoprene, and a hydrogenated additive thereof. Specifically, for example, styrene-butadiene rubber, styrene-isoprene block copolymer, styrene-ethylene / butylene-styrene block copolymer, styrene-ethylene / propylene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-butylene. Examples thereof include a butadiene-styrene block copolymer, a mixture of a styrene-ethylene / butylene-styrene block copolymer and a styrene-ethylene / butylene block copolymer.

The cellulosic resin is preferably a cellulose acetate butyrate resin. The polycarbonate resin is preferably bisphenol A polycarbonate.

The polyimide-based resin is preferably a thermoplastic polyimide, a polyamide-imide resin, or a polyamic acid type polyimide resin.

The cushion material may be in a form including a release layer in addition to the cushioning member in order to facilitate the peeling of the cushion material from the metal reinforcing plate, the wiring plate, and the heat press machine after heat pressing. As the release layer, it is preferable to form a layer made of polypropylene, polymethylpentene, cyclic olefin polymer, silicone, or fluororesin. Of these, polypropylene, polymethylpentene, silicone, and fluororesin are more preferable.
In addition to the above forms, a form coated with a release agent such as alkyd or silicone is also preferable.

The thickness of the release layer is preferably 0.001 to 70 μm, more preferably 0.01 to 50 μm.

As a commercially available cushion material, "CR1012", "CR1012MT4", "CR1031", "CR1033", "CR1040", "CR2031MT4", etc. manufactured by Mitsui Tosero Co., Ltd. can be used. These commercially available cushioning materials have a layer structure in which both sides of the cushioning material are sandwiched between polymethylpentene as release layers, and in the present application, these integrated structures are referred to as cushioning materials.

The thickness of the cushion material is preferably 50 to 300 μm, more preferably 75 to 250 μm, and even more preferably 100 to 200 μm. The exudability can be improved by setting the thickness to 50 to 300 μm. When the mold release layer is provided, the thickness is a value including the release layer.

(Metal reinforcement plate)
Examples of the metal reinforcing plate include conductive metals such as gold, silver, copper, iron and stainless steel. Among these, stainless steel is preferable in terms of strength, cost and chemical stability as a reinforcing plate.

The thickness of the metal reinforcing plate is preferably 50 to 500 μm, more preferably 60 to 400 μm, and even more preferably 75 to 300 μm. By setting the thickness of the metal reinforcing plate to 500 μm or less, it is possible to suppress exudation due to the flow of the cushion material, and to promote weight reduction and miniaturization of the printed circuit board. When the thickness is 50 μm or more, the strength of the metal reinforcing plate is improved and the reliability of the wiring board is improved.

The metal reinforcing plate preferably has a plating layer formed on the surface in order to suppress an increase in resistance value due to the non-conductorization of the surface. The plating layer is preferably gold, silver, nickel, or phosphorus-containing nickel plating. The plating method is preferably an electrolytic plating method or an electroless plating method. The thickness of the plating layer is about 0.1 to 5 μm, more preferably 0.2 to 4 μm. When the metal reinforcing plate has a plating layer, the thickness of the metal reinforcing plate is a value including the plating layer. From the viewpoint of reducing the cost, it is preferable that the plating is not performed.

From the viewpoint of more effectively suppressing exudation, the ratio of the thickness of the metal reinforcing plate to the cushion material (thickness of the metal reinforcing plate [μm] / thickness of the cushion material [μm]) is preferably 2 or less. It is more preferably 1.7 or less, and even more preferably 1.3 or less.

(Conductive adhesive)
The conductive adhesive according to the present embodiment preferably contains at least a binder resin that is softened by heat and a conductive filler, and has the following characteristics.

[Storage modulus]
In the present embodiment, the storage elastic modulus of the conductive adhesive at 170 ° C. may be 2 MPa or more and 50 MPa or less, preferably 4 MPa or more and 25 MPa or less, and more preferably 7 MPa or more and 15 MPa or less. By setting the storage elastic modulus of the conductive adhesive at 170 ° C. within this range, the conductive adhesive 12 can be sufficiently softened during hot pressing (see steps [1] to [3] of FIG. 2). It is possible to improve the filling property of the conductive adhesive 12 into the opening. Therefore, it is possible to suppress the formation of a gap 29b (see FIG. 5 (1)) between the conductive adhesive 12 and the gland circuit 25, and the resistance between the metal reinforcing plate 14 and the gland circuit 25. It is possible to suppress an increase in the value. Further, it is possible to prevent the exudation from being deteriorated due to the excessive softening of the conductive adhesive (see FIG. 5 (2)).

As a method for increasing the storage elasticity at 170 ° C. to 2 MPa or more, for example, increasing the weight molecular weight Mw of the binder resin, using the binder resin as a skeleton having many aromatic rings to increase the rigidity, conductive filler, inorganic filler, etc. Examples include increasing the amount of the filler component added, and increasing the cross-linking density with the curing agent in the B stage when the binder resin is a thermosetting resin.

As a method for reducing the storage elastic modulus at 170 ° C., for example, the weight molecular weight Mw of the binder resin is lowered, the aromatic ring is reduced from the skeleton of the binder resin to reduce the rigidity, and fillers such as conductive fillers and inorganic fillers are used. Examples include reducing the amount of the component added, and when the binder resin is a thermosetting resin, reducing the crosslink density with the curing agent in the semi-cured B stage.

In the present embodiment, the storage elastic modulus of the conductive adhesive at 170 ° C. is within the above range, so that the conductive adhesive has good filling property to the opening when the printed wiring board with the metal reinforcing plate is manufactured. A laminate and a printed wiring board with a metal reinforcing plate can be provided.

The storage elastic modulus of the conductive adhesive according to the present embodiment can be obtained by the same method as that for the cushion material.

Further, the storage elastic modulus of the cushion material is preferably higher than the storage elastic modulus of the conductive adhesive. The difference in storage elastic modulus between the cushion material and the conductive adhesive at 170 ° C. is preferably 4 to 100 MPa, more preferably 10 to 87 MPa. Within the above range, the effect of damming the exuding conductive adhesive with the cushion material is further improved.

[Loss tangent]
In the present embodiment, the loss tangent (tan δ) of the conductive adhesive at 170 ° C. is preferably 0.05 or more and 0.4 or less, more preferably 0.15 or more and 0.35 or less, and 0.20 or more and 0. 3 or less is more preferable. By setting the loss tangent (tan δ) of the conductive adhesive at 170 ° C. within this range, the filling property of the conductive adhesive 12 into the opening can be further improved.

As a method for setting the loss tangent at 170 ° C. to 0.05 or more, for example, the weight molecular weight Mw of the binder resin is lowered, the acid value of the binder resin is lowered, the glass transition temperature (Tg) of the binder resin is lowered, and in addition. Examples include adding a curing agent that is liquid at room temperature.

As a method for reducing the loss tangent at 170 ° C. to 0.40 or less, for example, the weight molecular weight Mw of the binder resin is increased, the acid value of the binder resin is increased, the Tg of the binder resin is increased, and the solid is cured at room temperature. Addition of an agent and the like can be mentioned.

The loss tangent (tan δ) of the conductive adhesive according to the present embodiment is the storage elastic modulus (E') of the conductive adhesive in the temperature range of 25 to 200 ° C. using the dynamic viscoelasticity measuring device as described above. ), The loss elastic modulus (E ″), and the loss tangent (tan δ) change are measured, and the loss tangent (tan δ) at each temperature can be extracted.

[Glass-transition temperature]
Further, in the conductive adhesive of the present embodiment, in the temperature-loss tangent (tan δ) curve obtained by viscoelasticity measurement, the glass transition temperature on the low temperature side is 10 ° C. or higher and 45 ° C. or lower, and the glass transition temperature on the high temperature side is high. It is preferably 70 ° C. or higher and 140 ° C. or lower. It is more preferable that the glass transition temperature on the low temperature side is 25 ° C. or higher and 40 ° C. or lower, and the glass transition temperature on the high temperature side is 75 ° C. or higher and 110 ° C. or lower. It is more preferable that the glass transition temperature on the low temperature side is 27 ° C. or higher and 36 ° C. or lower, and the glass transition temperature on the high temperature side is 78 ° C. or higher and 95 ° C. or lower. By setting the glass transition temperature of the conductive adhesive in such a range, the adhesion of the conductive adhesive and the filling property to the opening can be further improved.

As a method for setting the glass transition temperature on the low temperature side to 10 ° C. or higher and 45 ° C. or lower, for example, a method for controlling the Tg of the binder resin, and when the binder resin is a thermosetting resin, the crosslink density with the curing agent is used. There is a method of controlling.
In order to make the glass transition temperature on the high temperature side 70 ° C. or higher and 140 ° C. or lower, it can be adjusted by the same method as described above.

In the present embodiment, the glass transition temperature can be determined by using the temperature of the peak in the temperature-loss tangent (tan δ) curve obtained by measuring the viscoelasticity of the conductive adhesive.

[Film thickness]
The thickness of the conductive adhesive is preferably 15 to 70 μm, more preferably 20 to 65 μm. By setting the thickness to 15 μm or more, the embedding property in the small opening via can be improved. Exudability can be suppressed by setting the thickness to 70 μm or less. The thickness of the conductive adhesive can be measured by a contact-type film thickness meter, measurement by cross-sectional observation, or the like.

[Manufacturing method of conductive adhesive]
The conductive adhesive constituting the laminate can be produced, for example, by using a conductive resin composition and forming a conductive adhesive on a peelable film.

"Conductive resin composition"
The conductive adhesive according to the present embodiment is preferably formed of a binder resin that is softened by heat and a conductive resin composition containing conductive fine particles.

The binder resin that is softened by heat is not particularly limited as long as it does not deviate from the gist of the present invention, but a thermosetting resin is preferable. Further, in applications where there is no heating step such as a reflow step in the post-step, the thermoplastic resin is preferable. As the thermosetting resin, a self-crosslinking type and a curing agent reaction type can be used. As the curing agent reaction type binder resin, a thermosetting resin in which a reactive functional group capable of reacting with the curing agent is bonded is suitable.

<Thermosetting resin>
The thermosetting resin is a resin having a plurality of functional groups that can be used for a cross-linking reaction by heating.
Examples of the functional group include a hydroxyl group, a phenolic hydroxyl group, a carboxyl group, an amino group, an epoxy group, an oxetanyl group, an oxazoline group, an oxazine group, an aziridine group, a thiol group, an isocyanate group, a blocked isocyanate group and a silanol group. ..
The thermosetting resin having the above functional groups includes, for example, acrylic resin, maleic acid resin, polybutadiene resin, polyester resin, condensed polyester resin, additive polyester resin, melamine resin, polyurethane resin, polyurethane urea resin, and epoxy resin. , Oxetane resin, phenoxy resin, polyimide resin, polyamide resin, polyamideimide resin, phenolic resin, alkyd resin, amino resin, polylactic acid resin, oxazoline resin, benzoxazine resin, silicone resin, fluororesin and the like. Among these, polyurethane resin, polyurethane urea resin, epoxy resin, additive polyester resin, polyimide resin, polyamide resin, and polyamideimide resin are preferable.

The weight average molecular weight (Mw) of the thermosetting resin is preferably 50,000 to 200,000, more preferably 70,000 to 130,000. By setting the weight average molecular weight (Mw) in the above range, the storage elastic modulus and loss tangent of the conductive adhesive at 170 ° C. can be made suitable.

The glass transition temperature (Tg) of the thermosetting resin is preferably −20 ° C. to 20 ° C., more preferably −7 ° C. to 150 ° C. By setting the glass transition temperature in the above range, the storage elastic modulus of the conductive adhesive at 25 ° C. can be made suitable.

The acid value of the thermosetting resin is preferably 1 to 40 mg /, more preferably 4 to 15, and even more preferably 6 to 13. By setting the acid value of the thermosetting resin in the above range, the crosslink density with the curing agent described later can be optimized, and the storage elastic modulus and loss tangent at 170 ° C. can be made suitable.

<Hardener>
The curing agent functions to make a semi-curing state when a conductive adhesive is formed by a cross-linking reaction, does not react when forming a sheet, but reacts when heat-pressing a wiring plate or a metal reinforcing plate. Such a curing agent can be appropriately selected. Examples of the curing agent include epoxy-based compounds, isocyanate-based curing agents, amine-based curing agents, aziridine-based curing agents, and imidazole-based curing agents.

As the epoxy compound, for example, a glycisyl ether type epoxy compound, a glycisyl amine type epoxy compound, a glycidyl ester type epoxy compound, a cyclic aliphatic (alicyclic) epoxy compound and the like are preferable.

Examples of the glycidyl ether type epoxy compound include bisphenol A type epoxy compound, bisphenol F type epoxy compound, bisphenol S type epoxy compound, bisphenol AD type epoxy compound, cresol novolac type epoxy compound, phenol novolac type epoxy compound, and α-naphthol. Novolak type epoxy compound, bisphenol A type novolak type epoxy compound, dicyclopentadiene type epoxy compound, tetrabrom bisphenol A type epoxy compound, brominated phenol novolac type epoxy compound, tris (glycidyloxyphenyl) methane, tetrakis (glycidyloxyphenyl) Epoxy and the like can be mentioned.

Examples of the glycidylamine type epoxy compound include tetraglycidyldiaminodiphenylmethane, triglycidylparaaminophenol, triglycidylmethaminophenol, tetraglycidylmethoxylylenediamine and the like.

Examples of the glycidyl ester type epoxy compound include diglycidyl phthalate, diglycidyl hexahydrophthalate, and diglycidyl tetrahydrophthalate.

Examples of the cyclic aliphatic (alicyclic) epoxy compound include epoxycyclohexylmethyl-epoxycyclohexanecarboxylate and bis (epoxycyclohexyl) adipate.

Examples of the isocyanate-based curing agent include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, dicyclohexylmethane diisocyanate, 1,5-naphthalenediocyanate, tetramethylxylylene diisocyanate, and trimethylhexamethylene diisocyanate. Can be mentioned.

Examples of the amine-based curing agent include diethylenetriamine, triethylenetetramine, methylenebis (2-chloroaniline), methylenebis (2-methyl-6-methylaniline), 1,5-naphthalenediisocyanate, n-butylbenzylphthalic acid and the like. ..

Aziridine-based curing agents include, for example, trimethylolpropane-tri-β-aziridinyl propionate, tetramethylolmethane-tri-β-aziridinyl propionate, N, N'-diphenylmethane-4,4'-bis. (1-Aziridinecarboxamide), N, N'-hexamethylene-1,6-bis (1-aziridinecarboxamide) and the like can be mentioned.

Examples of the imidazole-based curing agent include 2-methylimidazole, 2-heptadecylimidazole, 2-phenyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazolium trimerite and the like.

The curing agent is preferably blended with 0.3 to 80 parts by weight, more preferably 1 to 50 parts by weight, based on 100 parts by weight of the thermosetting resin. By setting the addition amount of the curing agent to 0.3 to 80 parts by weight, the crosslink density of the conductive adhesive can be optimized, and the storage elastic modulus at 170 ° C. can be in the range of 2 MPa or more and 50 MPa or less. Further, by setting the addition amount of the curing agent to 0.3 to 80 parts by weight, the conductive adhesive sheet can be made difficult to flow after semi-curing, so that blocking can be easily suppressed.

<Thermoplastic resin>
In this embodiment, a thermoplastic resin may be used in combination.
Examples of the thermoplastic resin include polyolefin resins, vinyl resins, styrene / acrylic resins, diene resins, terpene resins, petroleum resins, cellulose resins, polyamide resins, polyurethane resins, and polyester resins that do not have the curable functional group. , Polycarbonate resin, polyimide resin, fluororesin and the like.

The polyolefin-based resin is preferably a homopolymer or copolymer such as ethylene, propylene, or α-olefin compound. Specific examples thereof include polyethylene propylene rubber, olefin-based thermoplastic elastomers, and α-olefin polymers.

As the vinyl resin, a polymer obtained by polymerizing a vinyl ester such as vinyl acetate and a copolymer of a vinyl ester and an olefin compound such as ethylene are preferable. Specific examples thereof include ethylene-vinyl acetate copolymers and partially saponified polyvinyl alcohols.

The styrene / acrylic resin is preferably a homopolymer or copolymer composed of styrene, (meth) acrylonitrile, acrylamides, (meth) acrylic acid esters, maleimides and the like. Specific examples thereof include syndiotactic polystyrene, polyacrylonitrile, acrylic copolymers, ethylene-methyl methacrylate copolymers and the like.
The diene-based resin is preferably a homopolymer or copolymer of a conjugated diene compound such as butadiene or isoprene, and a hydrogenated additive thereof. Specific examples thereof include styrene-butadiene rubber and styrene-isoprene block copolymers. The terpene resin is preferably a polymer composed of terpenes or a hydrogenated product thereof. Specific examples thereof include aromatic-modified terpene resin, terpene phenol resin, and hydrogenated terpene resin.

The petroleum-based resin is preferably a dicyclopentadiene type petroleum resin or a hydrogenated petroleum resin. The cellulosic resin is preferably a cellulose acetate butyrate resin. The polycarbonate resin is preferably bisphenol A polycarbonate. The polyimide-based resin is preferably a thermoplastic polyimide, a polyamide-imide resin, or a polyamic acid type polyimide resin.

<Conductive fine particles>
As the conductive fine particles, conductive metals such as gold, platinum, silver, copper and nickel, alloys thereof, and fine particles of a conductive polymer are preferable. Further, a composite fine particle in which a metal or resin is used as a nucleolus instead of a fine particle having a single composition and a coating layer covering the surface of the nucleolus is formed of a material having higher conductivity than the nucleolus is preferable from the viewpoint of cost reduction.
The nucleolus is preferably selected from cheap nickel, silica, copper and alloys thereof, and resins as appropriate.
The coating layer may be any material having conductivity, and a conductive metal or a conductive polymer is preferable. Examples of the conductive metal include gold, platinum, silver, tin, manganese, indium and the like, and alloys thereof. Examples of the conductive polymer include polyaniline and polyacetylene. Among these, silver is preferable from the viewpoint of conductivity.
The conductive fine particles may be used alone or in combination of two or more.

The composite fine particles preferably have a coating layer at a ratio of 1 to 40 parts by weight, more preferably 5 to 30 parts by weight, based on 100 parts by weight of the nucleus. When coated with 1 to 40 parts by weight, the cost can be further reduced while maintaining the conductivity. In the composite fine particles, it is preferable that the coating layer completely covers the nucleolus. However, in reality, a part of the nucleolus may be exposed. Even in such a case, if the conductive fine particles cover 70% or more of the surface area of the nucleus, the conductivity can be easily maintained.

The shape of the conductive fine particles is not limited as long as the desired conductivity can be obtained. Specifically, for example, spherical, flake-shaped, leaf-shaped, dendritic-shaped, plate-shaped, needle-shaped, rod-shaped, and grape-shaped are preferable. Spherical and dendritic shapes are more preferable in order to efficiently form a longitudinal conduction path between the metal reinforcing plate and the wiring plate.

The average particle diameter of the conductive fine _{particles, D 50} average particle diameter is preferably 1～120Myuemu, 5 to 60 m is more preferable. D ₅₀ average particle size can be prevented that the blocking takes place by in this range. Incidentally, D ₅₀ average particle size can be determined by laser diffraction scattering method particle size distribution measuring apparatus. For example, a conductive adhesive sheet having a conductive adhesive on a peelable film is transported in a rolled state. Blocking is a phenomenon in which the conductive adhesive sheet adheres to the back surface of the peelable film when the conductive adhesive sheet is unwound from the roll-shaped conductive adhesive sheet.

The amount of the conductive fine particles added is preferably 30 to 90% by weight, more preferably 40 to 80% by weight in the conductive adhesive. By setting the addition amount as described above, each storage elastic modulus at 170 ° C. can be set in a suitable range.

The conductive resin composition according to the present embodiment has a solvent, a heat-resistant stabilizer, an inorganic filler, a pigment, a dye, a tackifier resin, a plasticizer, a silane coupling agent, an ultraviolet absorber, an antifoaming agent, and other optional components. A leveling adjuster or the like can be blended.

Examples of the inorganic filler include silica, alumina, aluminum hydroxide, magnesium hydroxide, barium sulfate, calcium carbonate, titanium oxide, zinc oxide, antimony trioxide, magnesium oxide, talc, montmorolinite, kaolin, bentonite and the like. Be done. Since the conductive adhesive layer contains an inorganic filler, the storage elastic modulus before curing can be controlled to control the optimum flow amount.

The conductive resin composition can be obtained by mixing and stirring each of the above components. For stirring, a dispermat that can use a known stirring device is generally used, but a homogenizer is also preferable.

The conductive resin composition is applied to the peeling surface of the peelable film, for example, knife coat, die coat, lip coat, roll coat, curtain coat, bar coat, gravure coat, flexo coat, dip coat, spray coat, spin coat and the like. By coating by a method and heating to a temperature of usually 40 to 20 ° C., volatile components such as a solvent can be removed to form a conductive adhesive sheet having a conductive adhesive layer.

"Removable film"
The peelable film can be used without limitation as long as it is a film that has been mold-released on one side or both sides.
As an example of the base material of the peelable film, polyethylene terephthalate, polyethylene naphthalate, polyvinyl fluoride, polyvinylidene fluoride, rigid polyvinylidene chloride, polyvinylidene chloride, nylon, polyimide, polystyrene, polyvinyl alcohol, ethylene / vinyl alcohol co-weight. Combined, polycarbonate, polyacrylonitrile, polybutene, soft polyvinyl chloride, polyvinylidene fluoride, polyethylene, polypropylene, polyurethane, ethylene vinyl acetate copolymer, plastic sheets such as polyvinyl acetate, glassin paper, fine paper, kraft paper, coat Examples thereof include papers such as paper, various non-woven fabrics, synthetic papers, metal foils, and composite films combining these.

The surface of the peelable film can be matted if necessary. Examples of the mat treatment include sand mats, etching mats, coating mats, chemical mats, and kneading mats.

The peelable film can be obtained by applying a release agent to the base material. Release agents include hydrocarbon resins such as polyethylene and polypropylene, higher fatty acids and their metal salts, higher fatty acid soaps, waxes, animal and vegetable fats and oils, mica, talc, silicone-based surfactants, silicone oils, silicone resins, and fluororesins. Surface active agents, fluororesins, fluorosilicone resins, melamine resins, acrylic resins and the like are used. Conventionally known methods for applying the release agent include, for example, a gravure coating method, a kiss coating method, a die coating method, a lip coating method, a comma coating method, a blade coating method, a roll coating method, a knife coating method, and a spray coating method. It can be performed by a bar coat method, a spin coat method, a dip coat method, or the like.

<Printed circuit board>
The printed wiring board includes a circuit pattern including a ground circuit and an insulating protective film that insulates and protects the circuit pattern and has an opening on the base material. The circuit pattern including the ground circuit is generally formed by etching copper. The insulating protective film is preferably formed of a polyimide coverlay made of a polyimide film and an insulating adhesive, a resist film, or a solder resist. Drilling, etching, and laser machining are preferred as methods for forming openings on the ground circuit. The area and shape of the opening will be described later.

《Printed wiring board with metal reinforcing plate》
In the printed wiring board 30 with a metal reinforcing plate (see FIG. 3) according to the present embodiment, a ground circuit 25 is arranged on the substrate 21, and a part of the ground circuit 25 is insulated to insulate and protect the circuit pattern. It is arranged on the exposed ground circuit 25 and the wiring board 20 through the opening 27 provided in the protective film (insulating film 22 and insulating adhesive 23), and the above-mentioned conductive adhesive is used. It is provided with a conductive adhesive layer 12 composed of the above, and a metal reinforcing plate 14 arranged on the conductive adhesive layer 12 and adhered to the wiring board 20 via the conductive adhesive layer 12. In the printed wiring board 30 with a metal reinforcing plate according to the present embodiment, the ground circuit 25 and the metal reinforcing plate 14 are made of a conductive adhesive by filling the opening 27 with a part of the conductive adhesive layer 12. It is electrically connected via the layer 12. The wiring board 20 may be further provided with a signal wiring 24.

Area of the opening 27 of the metal reinforcing plate with printed wiring board 20 (see FIG. 3) is not particularly limited, may be 0.16 mm ² or more 0.81 mm ² or less. By setting the area of the opening 27 to 0.16 mm ² or more, the filling property of the conductive adhesive 12 into the opening 27 can be improved. Further, by setting the area of the opening 27 to 0.81 mm ² or less, the area of the opening 27 occupying the printed wiring board 20 with the metal reinforcing plate can be reduced. Area of the opening 27 is preferably 0.25 mm ² or more 0.64 mm ² or less, more preferably it may be 0.36 mm ² or more 0.49 mm ² or less. When the area of the opening 27 is within this range, the filling property of the conductive adhesive 12 in the opening 27 can be improved, and the contact resistance between the conductive adhesive 12 and the ground circuit 25 can be lowered. Can be done.
According to the method for manufacturing a printed wiring board with a metal reinforcing plate of the present invention, even when the area of the opening is small, the conductive adhesive can be sufficiently filled and the printed wiring board with a metal reinforcing plate has good embedding property. Can be.

The shape of the opening 27 when viewed in a plan view may be rectangular (see opening 27b in FIG. 6A) or circular (see opening 27a in FIG. 6A). When the shape of the opening 27 is rectangular, it is particularly difficult to fill the four corners of the rectangular opening with the conductive adhesive, and gaps 29b as shown in FIG. 5 are likely to be formed at the four corners. However, by using the conductive adhesive according to the present embodiment having the above-mentioned characteristics, the conductive adhesive can be satisfactorily filled in the opening even if the opening is rectangular.

Further, when the opening 27c is formed in a part of the outer periphery of the wiring board 20 as in the opening 27c shown in FIG. 6A (in the example shown in FIG. 6A, the opening 27c is formed at the corner of the wiring board 20. The formed) is in a state in which a wall for blocking the flow of the conductive adhesive is not provided on the outside of the opening 27c. In this case, as shown in FIG. 6B, when the metal reinforcing plate 14 is adhered to the wiring plate 20 using the conductive adhesive 12, the conductive adhesive 12a seeps out toward the outside of the opening 27c. There was a problem that it would end up.

On the other hand, in the present embodiment, since a laminate made of a cushioning material / metal reinforcing plate / conductive adhesive having the above-mentioned characteristics can be used at the time of hot pressing, the wiring plate 20 and the metal reinforcing plate 14 are used. It is possible to prevent the conductive adhesive from seeping out from the opening 27c at the end (or to reduce the amount of seepage) when the adhesive is adhered.

Such a printed wiring board with a metal reinforcing plate can be mounted on an electronic device such as a mobile phone, a smartphone, a notebook PC, a digital camera, or a liquid crystal display. Further, it can be suitably mounted on transportation equipment such as automobiles, trains, ships, and aircraft.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. Further, in the examples, "part" means a part by weight, and "%" means% by weight.
The blending amount in the table is a part by weight, and is a non-volatile content conversion value except for the solvent. The blanks in the table indicate that they are not mixed.

[Weight average molecular weight (Mw)]
The weight average molecular weight (Mw) is a polystyrene-equivalent value obtained by GPC (gel permeation chromatography) measurement. The measurement conditions are as follows.
Equipment: Shodex GPC System-21 (manufactured by Showa Denko)
Column: A connecting column in which one Shodex KF-802 (manufactured by Showa Denko), one Shodex KF-803L (manufactured by Showa Denko), and one Shodex KF-805L (manufactured by Showa Denko) are connected in series. Solvent: tetrahydrofuran Flow rate: 1.0 mL / min
Temperature: 40 ° C
Sample concentration: 0.2%
Sample injection volume: 100 μL
[Acid value]
It was determined by converting the measured acid value (mgKOH / g) into solid content in accordance with the potentiometric titration method of JIS K 0070.
[Glass transition temperature (Tg)]
The glass transition temperature was measured using a differential scanning calorimeter (model number: DSC-1, manufactured by METTLER TOLEDO).
[Storage modulus] and [Loss tangent tan δ]
Using a dynamic elastic modulus measuring device (model number: DVA-200, manufactured by IT Measurement Control), the deformation mode "tension" for the conductive adhesive, frequency 10 Hz, temperature rise rate 10 ° C / min, measurement temperature range- Under the conditions of 50 to 300 ° C., the storage elastic modulus E'at 170 ° C., the first peak temperature and the second peak temperature of the loss tangent tan δ, and the loss tangent tan δ at 170 ° C. were measured.

<Conductive resin composition, cushioning material, and metal reinforcing plate>
The materials, cushioning materials, and metal reinforcing plates of the conductive resin composition used for producing the laminated body and the printed wiring board with the metal reinforcing plate used in Examples and Comparative Examples are shown below. Table 1 shows the Mw, acid value and Tg of the binder resin.

[Binder resin]
Binder resin (a-1 to 6): Polyurethane resin (manufactured by Toyochem)

[Conductive fine particles (conductive filler)]
b-1: silver-coated copper _{particles, D 50} average particle size = 12 [mu] m, karyoplast: dendritic (manufactured by Fukuda Metal)
[Curing agent]
c-1: Bisphenol A type epoxy resin: Epoxy equivalent 189 g / eq (jER1001, manufactured by Mitsubishi Chemical Corporation)
[Curing accelerator]
d-1: Aziridine compound (trimethylolpropane tris [β- (N-aziridinyl) propionate], manufactured by Nippon Shokubai)
[Other ingredients]
e-1: Silica (AEROSIL R974, manufactured by Aerosil Japan)
[solvent]
f-1: Toluene: Isopropyl alcohol (mass ratio = 2: 1) mixed solvent [cushion material]
g-1: Polyethylene terephthalate (thickness 25 μm, storage elastic modulus at 170 ° C. 470 MPa)
g-2: Polybutylene terephthalate (thickness 50 μm, 170 ° C storage elastic modulus 89 MPa)
g-3: Polymethylpentene (thickness 50 μm, 170 ° C storage elastic modulus 62 MPa)
g-4: Styrene-ethylene-butylene-styrene block copolymer (thickness 120 μm, 170 ° C storage elastic modulus 32 MPa)
g-5: Styrene-butadiene-styrene block copolymer (thickness 120 μm, 170 ° C storage elastic modulus 51 MPa)
g-6: Ethylene-glycidyl methacrylate copolymer (thickness 150 μm, 170 ° C storage elastic modulus 23 MPa)
g-7: Soft vinyl chloride (thickness 75 μm, storage elastic modulus at 170 ° C. 1 MPa)
[Metal reinforcement plate]
h-1: SUS304 with a total thickness of 200 μm in which nickel layers with a thickness of 2 μm are formed on both surfaces.
h-2: SUS304 with a total thickness of 150 μm in which nickel layers with a thickness of 2 μm are formed on both surfaces.
h-3: SUS304 having a total thickness of 100 μm in which nickel layers having a thickness of 2 μm are formed on both surfaces.
h-4: SUS304 with a total thickness of 75 μm in which nickel layers with a thickness of 2 μm are formed on both surfaces.
[Printed circuit board]
Printed wiring board 1: In the printed wiring board 1, a copper foil circuit having a thickness of 32 μm is formed on both sides of a polyimide film having a thickness of 75 μm, and the copper foil circuit has a square shape with a side of 0.7 mm and an opening area. An insulating cover film with an adhesive having a thickness of 37.5 μm and having a through hole (opening) of 0.49 mm ^{2 is laminated.} Further, an insulating cover film having a thickness of 37.5 μm with an adhesive having no through hole is laminated on the other copper foil circuit (polyimide so that the printed wiring board does not warp). The copper foil circuit and cover film were arranged symmetrically with respect to the film).
Printed wiring board 2: A printed wiring board having the same configuration as the printed wiring board 1 except that it is a square having a side of 0.4 mm and the opening area of the through hole (opening) is 0.16 mm ^2.
Printed wiring board 3: A printed wiring board having the same configuration as the printed wiring board 1 except that it is a square having a side of 0.2 mm and the opening area of the through hole (opening) is 0.04 mm ^2.

[ Reference example 1 ]
100 parts by weight of the binder resin (a-1) and 250 parts by weight of the conductive fine particles (b-1) were placed in a container, and a solvent (f-1) was added and mixed so that the non-volatile content concentration was 40% by weight. .. Next, 40 parts by weight of the curing agent (c-1) and 0.05 parts by weight of the curing accelerator (d-1) were added, and the mixture was stirred with a stirrer for 10 minutes to prepare a conductive resin composition.
Next, the conductive resin composition prepared above is released using a doctor blade so that the thickness after drying becomes 60 μm (base material: foamed polyethylene terephthalate, base material thickness 50 μm, release). A conductive adhesive sheet on which a conductive adhesive was formed was obtained by coating on one surface of the release-treated surface of the mold agent (alkid-based mold release agent) and drying in an electric oven at 100 ° C. for 2 minutes. ..

Next, the conductive adhesive sheet is cut into a width of 20 mm and a length of 20 mm, and the conductive adhesive is exposed so that the exposed surface is in contact with the metal reinforcing plate (h-1) having a width of 20 mm and a length of 20 mm. The sex adhesive sheet was laminated on the metal reinforcing plate. Next, using a roll laminator, the ^{conductive adhesive sheet and the metal reinforcing plate were roll-laminated under the conditions of 90 ° C., 3 kgf / cm 2} , and 1 m / min to obtain a SUS plate with a conductive adhesive sheet.

Next, the peelable film of the conductive adhesive sheet in the metal reinforcing plate with the conductive adhesive sheet is peeled off and removed, and then punched into a square having a side of 10 mm with a punching machine to form a metal reinforcing plate with a conductive adhesive (a metal reinforcing plate with a conductive adhesive). Hereinafter, it is referred to as "metal reinforcing plate with conductive adhesive"). Next, using the separately produced printed wiring plates 1 to 3, the surface of the metal reinforcing plate with the conductive adhesive on which the conductive adhesive is exposed (the surface opposite to the metal reinforcing plate of the conductive adhesive) is used as the printed wiring plate. The metal reinforcing plate with the conductive adhesive and the printed wiring plate were attached to each other under the conditions of 130 ° C., 3 kgf / cm2, and 1 m / min using a roll laminator. After that, a cushion material (g-1) cut into a square having a side of 20 mm was laminated on the metal reinforcing plate to form a laminated body. Next, these are heat-pressed under the conditions of 170 ° C., 2 MPa, and 5 minutes, the cushioning material is removed, and the printed wiring boards with metal reinforcing plates 1 to 1 are heated at 160 ° C. for 60 minutes using an electric oven. I got 3.

[ Reference Example 2 , Examples 3 to 5, Reference Examples 6 to 8, Examples 9 to 19, Reference Examples 20 to 21, Examples 22 to 23, Comparative Example 1]
As shown in Tables 2 to 4 , the operation was carried out in the same manner as in Reference Example 1 except that the types and blending amounts of the components constituting the conductive resin composition and the types of the cushion material and the metal reinforcing plate were changed. Obtained laminates of Reference Examples 2, Examples 3 to 5, Reference Examples 6 to 8, Examples 9 to 19, Reference Examples 20 to 21, Examples 22 to 23 and Comparative Example 1, and a printed wiring board with a metal reinforcing plate. rice field.
Note that implementation in Table 2. Example 1 ～2,6～8, examples 20-21 in Table 4 is the meaning of Reference Example 1 ～2,6～8,20～21.

[Comparative Example 1]
Printed wiring boards 1 to 3 were used in the same manner as in Example 19 except that the cushion material was not used during the hot pressing, and printed wiring boards with metal reinforcing plates were obtained.

<Evaluation>
The embedding property and the exuding appearance of each of the obtained printed wiring boards with metal reinforcing plates were evaluated according to the following methods. The evaluation results are shown in Tables 2 to 4.

[Embedability]

SUS plate of printed wiring board with metal reinforcing plate using resistance value measuring instrument and BSP probe (model number: MCP-TP05P, manufactured by Mitsubishi Chemical Analytech) for printed wiring boards 1 to 3 with metal reinforcing plate having different opening areas. The electrical resistance (connection resistance value) between the and the copper foil circuit was measured, and the embedding property was evaluated according to the following evaluation criteria using this measured value as an index.

⊚: Connection resistance value is less than 20 mΩ / □ Very good ○: Connection resistance value is 20 mΩ / □ or more and less than 100 mΩ / □ Good △: Connection resistance value is 100 mΩ / □ or more and less than 300 mΩ / □ Practical use ×: Connection resistance value is More than 300mΩ / □ Practical

[Exudation]
For the printed wiring plate 1 with a metal reinforcing plate, the flow amount of the conductive adhesive protruding from the end of the metal reinforcing plate using a magnifying mirror having a magnification of 200 to 1000 times (maximum movement of the edge of the conductive adhesive layer). The distance (maximum length between the end of the SUS plate and the end of the conductive adhesive layer protruding) was measured, and the appearance was evaluated according to the following evaluation criteria using this measured value as an index.

⊚: Flow amount is 100 μm or less Very good ○: Flow amount is more than 100 μm and 130 μm or less Good Δ: Flow amount is more than 130 μm and 150 μm or less Practical ×: Flow amount is more than 150 μm Practical

Although the present invention has been described above in accordance with the above-described embodiment, the present invention is not limited to the configuration of the above-described embodiment, and those skilled in the art are within the scope of the claims in the claims of the present application. Of course, it includes various modifications, corrections, and combinations that can be made.

11 Removable film 12 Conductive adhesive (conductive adhesive layer)
13 Conductive Adhesive Sheet 14 Metal Reinforcing Plate 15 Preliminary Laminated Body 16 Cushioning Material 17 Laminated Body 18 Cutting Line 20 Wiring Board 21 Base Material 22 Insulating Film 23 Insulating Adhesive 24 Signal Circuit 25 Ground Circuit 27 Opening 29b Gap 30 Metal Printed wiring board with reinforcing plate

Claims (13)

Above the printed wiring board on which the circuit pattern including the ground circuit and the circuit pattern are insulated and protected, and an insulating protective film having an opening is formed.
A conductive adhesive containing a binder resin and a conductive filler that softens by heat and having a storage elastic modulus of 5.5 MPa or more and 50 MPa or less at 170 ° C, a metal reinforcing plate having a thickness of 50 to 500 μm, and storage elasticity at 170 ° C. A step of arranging the cushioning material having a ratio of 10 MPa or more and 100 MPa or less and higher than the storage elastic modulus of the conductive adhesive in this order and so that the printed wiring board and the conductive adhesive face each other [ 1-1],
or,
A conductive adhesive containing a binder resin and a conductive filler that softens by heat and having a storage elastic modulus of 2 MPa or more and 50 MPa or less at 170 ° C., a metal reinforcing plate having a thickness of 50 to 500 μm, and a storage elastic modulus at 170 ° C. A cushioning material having a storage elastic modulus of 10 MPa or more and 100 MPa or less at 170 ° C., which is higher than the storage elastic modulus of the conductive adhesive at 170 ° C. in the range of 21 MPa or more and 50 MPa or less, in this order and Step of arranging the printed wiring board and the conductive adhesive so as to face each other [1-2],
or,
A conductive adhesive containing a binder resin and a conductive filler that softens by heat and having a storage elastic modulus of 2 MPa or more and 50 MPa or less at 170 ° C., a metal reinforcing plate having a thickness of 50 to 500 μm, and a storage elastic modulus at 170 ° C. It is 10 MPa or more and 100 MPa or less, which is higher than the storage elastic modulus of the conductive adhesive, and is the ratio of the thickness of the metal reinforcing plate to the cushioning material (thickness of the metal reinforcing plate [μm] / thickness of the cushioning material [μm]. ) Is 1.5 to 2 in this order, and the printed wiring board and the conductive adhesive are arranged so as to face each other [1-3].
After any one of the steps [1-1] to [1-3], the printed wiring plate, the conductive adhesive, the metal reinforcing plate, and the cushioning material are laminated, and 150 to 190. It is hot-pressed at ° C., the gland circuit and the metal reinforcing plate are bonded to each other by a conductive adhesive through an opening provided in the insulating protective film, and the gland circuit and the metal reinforcing plate are electrically connected. At the same time, the cushioning material flows into the side surface side of the conductive adhesive and the metal reinforcing plate, and prevents the conductive adhesive from seeping out from the metal reinforcing plate [2].
And a step of peeling the front chrysanthemum cushion material [3],
A method of manufacturing a printed wiring board with a metal reinforcing plate. The print with a metal reinforcing plate according to claim 1, wherein in step [1-1] or step [1-3], the difference in storage elastic modulus between the cushioning material and the conductive adhesive at 170 ° C. is 10 to 87 MPa. Manufacturing method of wiring board. In step [1-1] or step [1-2], the ratio of the thickness of the metal reinforcing plate to the cushioning material (thickness of the metal reinforcing plate [μm] / thickness of the cushioning material [μm]) is 2 or less. The method for manufacturing a printed wiring board with a metal reinforcing plate according to claim 1 or 2. In any one of the steps [1-1] to [1-3],
It is characterized by using a conductive adhesive having a loss tangent (tan δ) of 0.05 or more and 0.4 or less at 170 ° C.
The method for manufacturing a printed wiring board with a metal reinforcing plate according to any one of claims 1 to 3. In any one of the steps [1-1] to [1-3],
In the temperature-loss tangent (tan δ) curve obtained by viscoelasticity measurement,
The first glass transition temperature is 10 ° C or higher and 45 ° C or lower.
The second glass transition temperature is 70 ° C. or higher and 140 ° C. or lower.
It is characterized by using a conductive adhesive.
The method for manufacturing a printed wiring board with a metal reinforcing plate according to any one of claims 1 to 4. In any one of the steps [1-1] to [1-3],
It is characterized by using a cushioning material larger than a metal reinforcing plate and a conductive adhesive when viewed in a plan view.
The method for manufacturing a printed wiring board with a metal reinforcing plate according to any one of claims 1 to 5. Step [1-1] - [1-3] Oite as much as any one Tsunoko,
It is characterized by using a conductive adhesive having a thickness of 15 to 70 μm.
The method for manufacturing a printed wiring board with a metal reinforcing plate according to any one of claims 1 to 6. Step [1-1] - [1-3] Oite as much as any one Tsunoko,
Place the conductive adhesive on the printed wiring board,
A metal reinforcing plate is placed on the conductive adhesive,
The method for manufacturing a printed wiring board with a metal reinforcing plate according to any one of claims 1 to 7, wherein a cushion material is arranged on the metal reinforcing plate. Step [1-1] - [1-3] Oite as much as any one Tsunoko,
A preliminary laminate of the conductive adhesive and the metal reinforcing plate is obtained in advance.
Claims 1 to 7, wherein the printed wiring board and the conductive adhesive in the preliminary laminate face each other, and the metal reinforcing plate in the preliminary laminate and the cushion material are arranged so as to face each other. The method for manufacturing a printed wiring board with a metal reinforcing plate according to any one of the following items. Step [1-1] - [1-3] Oite as much as any one Tsunoko,
A laminate obtained by laminating a conductive adhesive, a metal reinforcing plate, and a cushioning material in this order is obtained in advance, and the printed wiring board and the conductive adhesive in the laminate are arranged so as to face each other. The method for manufacturing a printed wiring board with a metal reinforcing plate according to any one of claims 1 to 7, wherein the printed wiring board has a metal reinforcing plate. A printed wiring board with a metal reinforcing plate obtained by the manufacturing method according to any one of claims 1 to 10. The area of the opening when viewed in plan 0.16 mm ² or more and 0.81 mm ² or less, claim 11 metal reinforcing plate with printed wiring board according. The printed wiring board with a metal reinforcing plate according to claim 11 or 12, wherein the opening is formed in a part of the outer periphery of the printed wiring board.

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