JP2016027131A - Adhesive composition, coverlay for printed wiring board, bonding film for printed wiring board, and printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition, a coverlay, and a bonding film which is hard to leave any foam on a surface of an adherend even when adhered to the adherend in a short time by one-time hot press.SOLUTION: An adhesive composition in one embodiment of the present invention has an elastic modulus of 900 MPa or less at 30°C in a B-stage state and a glass transition temperature of 70°C or higher. It is preferable that the adhesive composition contains a polyphenylene ether and a styrene elastomer. It is further preferable that the adhesive composition contains an acryl polymer. A coverlay for a printed circuit board in one embodiment of the present invention, includes: a resin film; and an adhesive layer formed from the above adhesive composition and deposited on one surface side of the resin film. A bonding film for a printed wiring board in one embodiment of the present invention is formed from the above adhesive composition.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an adhesive composition, a printed wiring board coverlay, a printed wiring board bonding film, and a printed wiring board.

  In the production of a printed wiring board, a thermosetting adhesive composition is used for laminating layers such as a base film (base material layer), a conductor layer, and a coverlay.

  Such a thermosetting adhesive composition is often provided in a B-stage state. Specifically, for example, it is provided as a part of a cover lay in which an adhesive composition in a B-stage state is laminated on a resin film, or as a bonding film in which the adhesive composition is formed into a sheet shape in a B-stage state. These adhesive compositions are typically used to form printed wiring boards.

  Such a thermosetting adhesive composition is required to have adhesiveness in the B-stage state, adhesiveness in the C-stage state, heat resistance, and flame retardancy. In order to satisfy these requirements, various adhesive compositions using an epoxy-based or polyimide-based thermosetting resin have been proposed (see, for example, JP-A-2014-19787).

JP 2014-19787 A

  The conventional adhesive composition as described above is cured by hot pressing for several tens of minutes to several hours. When applied to a roll-to-roll manufacturing method with high production efficiency, the conventional adhesive composition adheres to concave portions on the surface of the adherend, for example, between conductive pattern wiring, etc. The adhesive composition cannot be sufficiently filled, the embedding property is insufficient, and there is a risk that small bubbles may be left in the recesses on the surface of the adherend, and the air release property is insufficient. There is a possibility that an air dome-like bubble is formed by pressing the surrounding adhesive layer while leaving an air layer in a part of the area. Applying a vacuum press that evacuates air prior to hot pressing can improve the above-mentioned embedding and air release properties, but the roll-to-roll manufacturing method, which is a continuous production method, can be applied to short-time hot pressing processes. Is difficult in terms of cost and production efficiency.

  The present invention has been made based on the above-described circumstances, and an adhesive composition and print in which air bubbles hardly remain on the surface of the adherend even if it is bonded to the adherend in a short time and with a single hot press. It is an object of the present invention to provide a wiring board cover lay, a printed wiring board bonding film, and a printed wiring board that can be provided at high quality and at low cost.

  The adhesive composition according to one embodiment of the present invention made to solve the above problems has an elastic modulus at 30 ° C. in a B-stage state of 900 MPa or less and a glass transition temperature of 70 ° C. or more.

  In the adhesive composition according to one embodiment of the present invention, bubbles hardly remain on the surface of the adherend even if the adhesive composition adheres to the adherend in a short time and with a single hot press.

FIG. 1 is a schematic partial cross-sectional view showing a printed wiring board according to an embodiment of the present invention. FIG. 2 is a diagram showing the physical properties of the adhesive composition and the evaluation results of the adhesion test.

[Description of Embodiment of the Present Invention]
The adhesive composition according to one embodiment of the present invention has an elastic modulus at 30 ° C. in a B-stage state of 900 MPa or less and a glass transition temperature of 70 ° C. or more.

  Since the elastic modulus at 30 ° C. in the B-stage state is 900 MPa or less, the adhesive composition can be easily filled in the recesses on the surface of the adherend layer in the initial stage of hot pressing, and has excellent embedding properties. . In addition, the adhesive composition has a glass transition temperature of 70 ° C. or higher, so that it softens in the initial stage of hot pressing and does not easily form air dome-shaped bubbles, and has excellent air release properties. For this reason, even if the said adhesive composition adhere | attaches to a to-be-adhered body for a short time and one hot press, a bubble does not remain easily on the surface of a to-be-adhered body.

  The adhesive composition may include polyphenylene ether and a styrenic elastomer. Thus, the said elastic modulus and glass transition temperature are easily realizable by including a polyphenylene ether and a styrene-type elastomer. Moreover, since the dielectric constant of the said adhesive composition can be reduced by using polyphenylene ether, the transmission characteristic of a printed wiring board can be improved.

  The adhesive composition may further include an acrylic polymer. Thus, when the adhesive composition further contains an acrylic polymer, the adhesion after after-curing can be relatively increased even when the after-curing is performed at a relatively low temperature.

  The content ratio of the polyphenylene ether to the styrene elastomer is preferably 1/5 or more and 1/2 or less. Thus, the elastic modulus and glass transition temperature can be more easily realized when the mass ratio of polyphenylene ether to styrene elastomer is within the above range.

  The adhesive composition may include polyphenylene ether and an acrylic polymer. Thus, the said elastic modulus and glass transition temperature are easily realizable because the said adhesive composition contains a polyphenylene ether and an acrylic polymer. Moreover, since the dielectric constant of the said adhesive composition can be reduced by using polyphenylene ether, the transmission characteristic of a printed wiring board can be improved.

  A printed wiring board cover lay according to another aspect of the present invention includes a resin film and an adhesive layer laminated on one surface side of the resin film and formed from the adhesive composition.

  The printed wiring board cover lay is formed by laminating an adhesive layer formed from the above adhesive composition on a resin film, so that the printed wiring can be printed even if it is bonded to the printed wiring board by a single hot press in a short time. Air bubbles hardly remain on the surface of the plate.

  The bonding film for printed wiring boards according to still another aspect of the present invention is formed from the above adhesive composition.

  In the bonding film for a printed wiring board, even if the layers constituting the printed wiring board are bonded by a single hot press for a short time, bubbles hardly remain between the layers.

  The printed wiring board which concerns on another aspect of this invention is equipped with the said cover lay or the said bonding film in the adhesive state in the adhesive composition.

  Since the printed circuit board is adhered by curing the cover layer adhesive layer or the bonding film, even if it is formed in a short time and once in a hot press, air bubbles hardly remain, so the production efficiency is good. High quality and low cost.

  Here, “elastic modulus” and “glass transition temperature” are values measured by, for example, a dynamic viscoelasticity measuring apparatus manufactured by Hitachi High-Tech Science Corporation. Specifically, the storage elastic modulus when a B-stage adhesive composition cut to a width of 4 mm and a length of 20 mm is mounted between chucks of a measuring apparatus and measured in a tensile mode at a heating rate of 10 ° C./min. Is the “elastic modulus” of the adhesive composition, and the temperature at which the tan δ peaked is the “glass transition temperature” of the adhesive composition.

[Details of the embodiment of the present invention]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Adhesive composition]
First, an adhesive composition according to an embodiment of the present invention will be described.

  The upper limit of the elastic modulus at 30 ° C. in the B-stage state of the adhesive composition is 900 MPa, preferably 600 MPa, and more preferably 400 MPa. On the other hand, the lower limit of the elastic modulus at 30 ° C. in the B-stage state of the adhesive composition is preferably 10 MPa, more preferably 100 MPa, and even more preferably 200 MPa. When the elastic modulus at 30 ° C. in the B-stage state of the adhesive composition exceeds the above upper limit, a concave portion (for example, a gap in a wiring pattern of a printed wiring board, etc.) is formed on the bonding surface of the bonded body during thermocompression bonding to the bonded body. ), The concave portion of the adhesive surface cannot be sufficiently filled with the adhesive composition, and bubbles may be left behind, that is, the embedding property may be insufficient. Further, when the elastic modulus at 30 ° C. in the B-stage state of the adhesive composition is less than the lower limit, the fluidity of the adhesive composition before curing is too large, and it is difficult to manufacture a printed wiring board and the like. There is a risk of disappearing.

  The lower limit of the glass transition temperature of the adhesive composition is 70 ° C, preferably 100 ° C, and more preferably 110 ° C. On the other hand, as an upper limit of the glass transition temperature of the adhesive composition, 150 ° C. is preferable, and 120 ° C. is more preferable. When the glass transition temperature of the adhesive composition is less than the lower limit, the adhesive composition softens at an early stage during hot pressing and traps air between the surface of the adherend and creates air dome-like bubbles. There is a risk of forming the air, i.e., air bleedability may be insufficient. Moreover, when the glass transition temperature of the said adhesive composition exceeds the said upper limit, in order to fully express adhesive force, high temperature is required and there exists a possibility that adhesion | attachment to a to-be-adhered body may become easy.

  The adhesive composition includes an adhesive resin component and a solvent. Moreover, it is preferable that the said adhesive composition contains a polymerization initiator, a hardening accelerator, etc.

<Adhesive resin component>
The adhesive resin component preferably contains polyphenylene ether and styrene elastomer, or preferably contains polyphenylene ether and acrylic polymer, and more preferably contains polyphenylene ether, styrene elastomer and acrylic polymer. Moreover, the said adhesive resin component may contain other resin components, such as an epoxy resin and a phenol resin, for example.

(Polyphenylene ether)
Polyphenylene ether can increase the glass transition temperature of the adhesive composition and improve heat resistance. Further, by using polyphenylene ether, the adhesive composition can have a relative dielectric constant of 3 or less, preferably 2.5 or less, and transmission characteristics of a printed wiring board using the adhesive composition can be improved. It can be improved. The “relative dielectric constant” is a value measured according to JIS-C-2138 (2007).

(Styrene elastomer)
Styrenic elastomer (TPS) reduces the elastic modulus at 30 ° C. in the B-stage state of the adhesive composition, improves embedding properties, and imparts adhesion after curing.

  Examples of the styrenic elastomer include polystyrene-polybutadiene block copolymer (SBC), polystyrene-poly (ethylene / propylene) block copolymer (SEP), polystyrene-poly (ethylene / propylene) -polystyrene block copolymer (SEPS), polystyrene-poly ( Ethylene / butylene) -polystyrene block copolymer (SEBS), polystyrene-poly (ethylene-ethylene / propylene) block-polystyrene block copolymer (SEEPS), polystyrene-polyisoprene-polystyrene block copolymer (SIS), polystyrene-hydrogenated polyisoprene- Polystyrene block copolymer (SEPS), polystyrene-hydrogenated poly (isoprene / butadiene) -polystyrene block Kukoporima (SEEPS) and the like may be used singly or in combination of two or more.

  The lower limit of the mass ratio of polyphenylene ether to styrene elastomer is preferably 1/5, more preferably 1/4. The upper limit of the content mass ratio is preferably 1/2, and more preferably 2/5. When the content ratio by mass of polyphenylene ether to styrene-based elastomer is less than the lower limit, the glass transition temperature of the adhesive composition may be low, and air bleeding may be insufficient. Moreover, when the mass ratio of polyphenylene ether to styrene-based elastomer exceeds the above upper limit, the elastic modulus of the adhesive composition is increased, and the embedding property may be insufficient.

(Acrylic polymer)
The acrylic polymer reduces the elastic modulus at 30 ° C. in the B-stage state of the adhesive composition and improves the embedding property. In addition, since the adhesive resin component includes an acrylic polymer, the adhesive composition can be after-cured at a relatively low temperature. Therefore, other configurations of products such as printed wiring boards using the adhesive composition It is possible to prevent damage to the elements and reduce the energy cost required for manufacturing the product.

  As the acrylic polymer, an acrylate copolymer is preferable, and one having at least one of a hydroxyl group, a carboxyl group, an epoxy group, and an amide group is more preferable. By using such an acrylate copolymer as an acrylic polymer, it has preferable reactivity, and a preferable elastic modulus after B-stage state and heat curing can be obtained, so that the embedding property of the adhesive composition can be obtained. Can be improved more reliably.

The average molecular weight of the acrylic polymer is preferably 10 ⁴ or more and 10 ⁵ or less. By using an acrylic polymer having such an average molecular weight, the elastic modulus in the B-stage state of the adhesive composition can be reduced, and the embedding property can be improved more reliably. In addition, “average molecular weight” means gel permeation in accordance with JIS-K7252-1 (2008) “Plastics—How to determine average molecular weight and molecular weight distribution of polymer by size exclusion chromatography—Part 1: General rules”. Refers to a value measured using chromatography (GPC).

  The lower limit of the mass ratio of the acrylic polymer to the polyphenylene ether is preferably 1, and more preferably 1.5. The upper limit of the mass ratio of the acrylic polymer to the polyphenylene ether is preferably 10, and more preferably 7. When the content ratio by mass of the acrylic polymer to the polyphenylene ether is less than the lower limit, the elastic modulus of the adhesive composition is increased and the embedding property may be insufficient. Moreover, when the content mass ratio with respect to the polyphenylene ether of an acrylic polymer exceeds the said upper limit, there exists a possibility that the glass transition temperature of the said adhesive composition may become low and air bleeding property may become inadequate.

  The lower limit of the total content of polyphenylene ether, styrene elastomer and acrylic polymer in the adhesive resin component of the adhesive composition is preferably 50% by mass, more preferably 70% by mass, and even more preferably 90% by mass. When the total content of polyphenylene ether, styrene elastomer and acrylic polymer in the adhesive resin component of the adhesive composition is less than the lower limit, it may be difficult to achieve the above elastic modulus and glass transition temperature. is there.

(Epoxy resin)
The heat resistance of the adhesive composition can be improved by adding an epoxy resin to the adhesive composition. The lower limit of the content of the epoxy resin in the adhesive resin component of the adhesive composition is preferably 1% by mass. On the other hand, the upper limit of the content of the epoxy resin in the adhesive resin component of the adhesive composition is preferably 5% by mass. When the addition amount of the epoxy resin is less than the lower limit, the heat resistance improving effect may be insufficient. Moreover, when the addition amount of the said epoxy resin exceeds the said upper limit, there exists a possibility that the adhesive force with respect to a board | substrate may become inadequate.

(Phenolic resin)
By adding a phenol resin together with an epoxy resin to the adhesive composition, the heat resistance can be improved more effectively. The lower limit of the phenol resin content in the adhesive resin component of the adhesive composition is preferably 1% by mass. On the other hand, the upper limit of the content of the phenol resin in the adhesive resin component of the adhesive composition is preferably 5% by mass. When the addition amount of the phenol resin is less than the lower limit, the heat resistance improvement effect may be insufficient. Moreover, when the addition amount of the said phenol resin exceeds the said upper limit, the adhesive force with respect to a board | substrate etc. falls.

<Curing accelerator>
In order to accelerate the curing of the epoxy resin and the phenol resin, for example, a curing accelerator such as an imidazole curing accelerator or a triazine curing accelerator can be added.

  Examples of the imidazole curing accelerator include 2-methylimidazole (2MZ-H), 2-undecylimidazole (C11Z), 2-heptadecylimidazole (C17Z), 1,2-dimethylimidazole (1.2DMZ), 2 -Ethyl-4-methylimidazole (2E4MZ), 2-phenylimidazole (2PZ), 2-phenylimidazole (2PZ-PW), 2-phenyl-4-methylimidazole (2P4MZ), 1-benzyl-2-methylimidazole ( 1B2MZ), 1-benzyl-2-phenylimidazole (1B2PZ), 1-cyanoethyl-2-methylimidazole (2MZ-CN), 1-cyanoethyl-2-undecylimidazole (C11Z-CN), 1-cyanoethyl-2- Ethyl-4-methylimidazole 2E4MZ-CN), 1-cyanoethyl-2-phenylimidazole (2PZ-CN), 1-cyanoethyl-2-undecylimidazolium trimellitate (C11Z-CNS), 1-cyanoethyl-2-phenylimidazolium trimellitate (2PZCNS-PW) and the like.

  Examples of the triazine curing accelerator include 2,4-diamino-6- [2′-methylimidazolyl- (1 ′)]-ethyl-s-triazine (2MZ-A), 2,4-diamino-6- [ 2'-methylimidazolyl- (1 ')]-ethyl-s-triazine (2MZA-PW), 2,4-diamino-6- [2'-undecylimidazolyl- (1')]-ethyl-s-triazine (C11Z-A), 2,4-diamino-6- [2′-ethyl-4′-methylimidazolyl- (1 ′)]-ethyl-s-triazine (2E4MZ-A), and the like.

  As content of a hardening accelerator, it is set as 0.01 to 0.2 mass% with respect to the said adhesive resin component, for example.

<Polymerization initiator>
As the polymerization initiator, for example, a radical polymerization initiator can be used. As the radical polymerization initiator, for example, “Perhexa 25B”, “Perhexa V”, “Perhexine 25B” manufactured by NOF Corporation can be used.

  As content of a radical polymerization initiator, it is 0.5 mass% or more and 3 mass% or less with respect to the said adhesive resin component, for example.

<Solvent>
The solvent is used to obtain a desired viscosity by adjusting the solid content concentration of the adhesive composition.

  For example, toluene can be used as the solvent.

  As a minimum of solid content concentration of the adhesive constituent adjusted with a solvent, 10 mass% is preferred, 13% is more preferred, and 15 mass% is still more preferred. On the other hand, the upper limit of the solid content concentration of the adhesive composition is preferably 40% by mass, and more preferably 25% by mass.

  Moreover, the said adhesive composition may contain suitably additives, such as a flame retardant, a reflow heat resistance improver, an adhesion | attachment improvement agent, for example.

(Flame retardants)
As the flame retardant, for example, a phosphorus-based flame retardant can be used. As content of a flame retardant, it is 2 mass% or more and 8 mass% or less with respect to the said adhesive resin component, for example.

(Reflow heat improver)
For the purpose of improving the heat resistance during reflow, for example, a silica filler may be added to the adhesive composition.

(Adhesion improver)
As the adhesion improver, for example, triallyl isocyanurate (TAIC) can be used.

<Advantages>
The adhesive composition has an elastic modulus at 30 ° C. in a B-stage state of 900 MPa or less and a glass transition temperature of 70 ° C. or more, so that it can be filled in the recesses on the surface of the layer to be bonded in the initial stage of hot pressing. It is easy and has excellent embeddability. In addition, the adhesive composition has a glass transition temperature of 70 ° C. or higher, so that the adhesive composition is less likely to soften and form air dome-like bubbles in the initial stage of hot pressing, and has excellent air release properties. For this reason, even if the said adhesive composition adhere | attaches to a to-be-adhered body for a short time and one hot press, a bubble does not remain easily on the surface of a to-be-adhered body.

[Printed wiring board]
Subsequently, a printed wiring board according to an embodiment of the present invention will be described.

  The printed wiring board of FIG. 1 includes a printed circuit board 1, a coverlay 2 stacked on the surface side of the printed circuit board 1, and an electronic component (not shown) mounted on the printed circuit board 1.

<Printed circuit board>
The printed circuit board 1 includes a base film 3, a conductive pattern 4 laminated on the surface side of the base film 3, and an adhesive layer 5 that bonds the base film 3 and the conductive pattern 4.

(Base film)
The base film 3 is composed of a sheet-like member having insulation and flexibility. Specifically, a resin film can be employed as the sheet-like member constituting the base film 3. As a material for this resin film, for example, polyimide, polyethylene terephthalate or the like is preferably used. The base film 3 may contain a filler, an additive, and the like.

  As a minimum of average thickness of base film 3, 5 micrometers is preferred and 12 micrometers is more preferred. On the other hand, the upper limit of the average thickness of the base film 3 is preferably 50 μm, and more preferably 25 μm. When the average thickness of the base film 3 is less than the above lower limit, the strength of the base film 3 may be insufficient. Moreover, when the average thickness of the base film 3 exceeds the said upper limit, there exists a possibility that the flexibility of the printed circuit board 1 may become inadequate, or there exists a possibility that the printed circuit board 1 may become thick unnecessarily. The “average thickness” means an average value of thicknesses measured at arbitrary ten points. The same applies to the case where the “average thickness” is referred to below for other members.

(Conductive pattern)
The conductive pattern 4 can be formed of a conductive material. Examples of the conductive material include metals such as copper, aluminum, and nickel. Generally, for example, copper is used. The conductive pattern 4 may be plated on the surface. As this plating treatment, tin plating or gold plating is preferable.

  The lower limit of the average thickness of the conductive pattern 4 is preferably 5 μm and more preferably 10 μm. On the other hand, the upper limit of the average thickness of the conductive pattern 4 is preferably 50 μm, and more preferably 35 μm. When the average thickness of the conductive pattern 4 is less than the above lower limit, the conductivity may be insufficient. Moreover, when the average thickness of the conductive pattern 4 exceeds the upper limit, the flexibility of the printed circuit board 1 may be insufficient, or the printed circuit board 1 may be unnecessarily thick.

(Adhesive layer)
The adhesive layer 5 is formed of the above-described adhesive composition, and is composed of a bonding film for a printed wiring board according to an embodiment of the present invention. The adhesive composition is in a cured state (C stage state). ).

  The lower limit of the average thickness of the adhesive layer 5 is preferably 10 μm, and more preferably 20 μm. On the other hand, the upper limit of the average thickness of the adhesive layer 5 is preferably 60 μm, and more preferably 50 μm. When the average thickness of the adhesive layer 5 is less than the above lower limit, the adhesion between the base film 3 and the conductive pattern 4 may be insufficient. Moreover, when the average thickness of the adhesive layer 5 exceeds the upper limit, the thickness of the printed wiring board may be unnecessarily increased.

<Coverlay>
The coverlay 2 in FIG. 1 is itself an embodiment of the present invention. The cover lay 2 includes a resin film 6 and an adhesive layer 7 laminated on the back surface of the resin film 6.

(Resin film)
As the resin film 6 of the cover lay 2, an insulating film is used. As the insulating film constituting the resin film 6, the same film as the resin film constituting the base film 3 can be used.

(Adhesive layer)
The adhesive layer 7 of the coverlay 2 is formed from the adhesive composition according to one embodiment of the present invention, and is in a cured state (C stage state) in the printed wiring board.

  As the adhesive composition for forming the adhesive layer 7 of the coverlay 2, the same adhesive composition as that for forming the adhesive layer 5 of the printed circuit board 1 can be used. The average thickness of the adhesive layer 7 of the cover lay 2 is the same as that of the adhesive layer 5 of the printed circuit board 1.

[Method of manufacturing printed wiring board]
The printed wiring board includes a step of manufacturing the printed circuit board 1, a step of manufacturing the cover lay 2, a step of stacking the printed circuit board 1 and the cover lay 2, and a step of mounting electronic components on the printed circuit board 1. Prepare.

<Printed circuit board manufacturing process>
The printed circuit board manufacturing process includes a process of forming a printed wiring board bonding film according to an embodiment of the present invention, and a lamination process of laminating the base film 3 and a conductive material layer (for example, metal foil) via the bonding film. And a step of forming the adhesive layer 5 by curing the bonding film by hot pressing the laminate, and a step of forming the conductive pattern 4 by patterning the conductive material layer.

(Bonding film formation process)
The bonding film forming step includes a step of adjusting the adhesive composition, a step of laminating the adhesive composition on the release sheet, a step of curing the layered adhesive composition to form a B stage, and a B stage. And a step of peeling the bonding film made of the adhesive composition cured to the state from the release sheet.

<Adhesive composition adjustment process>
In the adhesive composition adjusting step, the adhesive composition is adjusted by blending polyphenylene ether, at least one of a styrene-based elastomer and an acrylic polymer, and an additive.

<Adhesive composition lamination process>
In the adhesive composition laminating step, a layer of the adhesive composition is formed on the release sheet. Examples of the method for forming the adhesive composition layer include coating and printing.

<B-stage process>
In the B-stage forming step, for example, the adhesive composition is cured in a B-stage state by heating at 50 to 100 ° C. for 0.5 to 5 minutes.

<Peeling process>
By peeling the B-staged layer of the adhesive composition from the release sheet, the printed wiring board bonding film according to an embodiment of the present invention formed of the adhesive composition is obtained.

(Film lamination process)
In the film lamination process, the base film 3 and the conductive material layer (for example, metal foil) are laminated via the bonding film.

(Adhesive layer forming process)
In the adhesive layer forming step, the adhesive layer 5 is formed by bringing the bonding film into a cured state (C stage state) by hot pressing the laminate.

(Conductive pattern formation process)
In the conductive pattern forming step, the conductive material layer is patterned by a known pattern forming method, for example, a method of forming and etching a resist pattern to form the conductive pattern 4 having a desired planar shape. Thereby, the printed circuit board 1 provided with the base film 3, the conductive pattern 4, and the adhesive bond layer 5 is obtained.

<Coverlay manufacturing process>
The coverlay manufacturing process includes a process of adjusting the adhesive composition, a process of laminating the adhesive composition on the resin film 6, and a process of curing the adhesive composition to form a B stage.

(Adhesive composition adjustment process)
In the adhesive composition adjustment step, in the same manner as the adhesive composition adjustment step in the bonding film formation step, polyphenylene ether, at least one of a styrene-based elastomer and an acrylic polymer, and an additive are blended. The agent composition.

(Adhesive composition lamination process)
In the adhesive composition lamination step, the adhesive composition is laminated on the resin film 6. The method for laminating the adhesive composition can be the same as in the adhesive composition laminating step in the bonding film forming step.

(B-stage process)
In the B-stage forming process, the adhesive composition 7 is cured in the B-stage state under the same conditions as the B-stage forming process in the bonding film forming process, thereby forming the adhesive layer 7. Thereby, the coverlay 2 according to an embodiment of the present invention provided with the resin film 6 and the adhesive layer 7 is obtained.

<Printed circuit board and coverlay lamination process>
In the printed circuit board and cover lay stacking process, the printed circuit board 1 and the cover lay 2 are overlapped with each other so that the adhesive layer 7 is brought into contact with the conductive pattern 4 and hot-pressed so that the printed circuit board 1 and the cover lay 2 are bonded. Integrate.

  The conditions for the hot press are, for example, a pressure of 3 MPa to 9 MPa, a temperature of 150 ° C. to 200 ° C., and a time of 30 seconds to 180 seconds.

<Electronic component mounting process>
In the electronic component mounting step, the printed wiring board according to the embodiment of the present invention is mounted by mounting the electronic component at a predetermined position of the conductive pattern 4 of the printed circuit board 1 integrated with the cover lay 2 by the heat press. can get. At this electronic component mounting position, a land portion is usually formed in the conductive pattern 4 of the printed circuit board 1, and an opening is formed in the cover lay 2.

  As a method for mounting the electronic component, for example, a known mounting method such as die bonding or wire bonding can be applied.

<Advantages>
The adhesive composition having an elastic modulus at 30 ° C. in the B-stage state of 900 MPa or less and a glass transition temperature of 70 ° C. or more can be easily filled in the recesses on the surface of the adherend layer in the initial stage of hot pressing. Excellent embeddability. In addition, the adhesive composition has a glass transition temperature of 70 ° C. or higher, so that it is less likely to soften and form dome-shaped bubbles in the initial stage of hot pressing, and is excellent in air bleedability. For this reason, even if the said adhesive composition adhere | attaches to a to-be-adhered body for a short time and one hot press, a bubble does not remain easily on the surface of a to-be-adhered body.

  Further, the printed wiring board cover lay 2 including the resin film 6 and the adhesive layer 7 laminated on one surface side of the resin film 6 and formed from the adhesive composition, Even if it is bonded to the printed circuit board 1 by a single hot press, bubbles are unlikely to remain on the surface of the printed circuit board 1.

  The printed wiring board bonding film formed from the adhesive composition has a short time between the layers constituting the printed circuit board 1 of the printed wiring board (the base film 3 and the conductive material layer constituting the conductive pattern 4). In addition, even when bonded by a single hot press, bubbles hardly remain between the layers.

  The printed wiring board provided with the cover lay 2 and the bonding film in a cured state of the adhesive film is less likely to remain even if formed by a short-time hot press, so that the production efficiency is high, and the quality is high. Can be provided at low cost.

[Other Embodiments]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is not limited to the configuration of the above-described embodiment, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims. The

  The said bonding film can be used in order to laminate | stack another layer, for example, a reinforcement board etc., on a printed wiring board etc. Moreover, the said bonding film can also be used in order to adhere a some printed wiring board.

  Further, the printed wiring board may not have flexibility.

  The printed wiring board may not have a cover lay. That is, the printed circuit board in the above-described embodiment itself is an embodiment of the printed wiring board of the present invention.

  Moreover, the said printed wiring board may laminate | stack the said coverlay on the printed circuit board formed without using the said adhesive composition.

  EXAMPLES Hereinafter, although this invention is explained in full detail based on an Example, this invention is not interpreted limitedly based on description of this Example.

<Adhesive composition No. 1-20>
In the formulations shown in Tables 1 and 2, adhesive composition No. 1 to 20 were prototyped.

  As polyphenylene ether 1, “SA9000” manufactured by Savic was used, and as polyphenylene ether 2, “SA90” manufactured by Savic was used.

  The styrene elastomer 1 is Kuraray's “SEPTON 4033”, the styrene elastomer 2 is the Kuraray “SEPTON 8007L”, and the styrene elastomer 3 is the Kuraray “SEPTON V9827”. Is Kuraray's "SEPTON V9461", styrene elastomer 5 is Kuraray's "HYBRAR 5125", styrene elastomer 6 is Kuraray's "HYBRAR 7125", and styrene elastomer 7 is Kuraray's HYBRAR 7311 ”, Asahi Kasei Chemicals'“ Tuftec H1041 ”as the styrene elastomer 8, Asahi Kasei Chemicals“ Tuftec M1911 ”as the styrene elastomer 9 The "Tuftec P1500" by Asahi Kasei Chemicals Corporation of the styrene-based elastomer 10, as the styrene elastomer 11 using "Tuftec MP10" of Asahi Kasei Chemicals Corporation.

  As the acrylic polymer 1, “Tathan Resin SG-70L” manufactured by Nagase Chemtech Co., Ltd., as the acrylic polymer 2, “Taisan Resin SG-80H” manufactured by Nagase Chemtech Co., Ltd., and as the acrylic polymer 3, Nagase Chemtech Corp. "Taisan Resin SG-P3" was used.

  As the epoxy resin, “N-695” manufactured by DIC was used.

  As the curing accelerator, 2-ethyl-4-methylimidazole was used.

  As the phenol resin, “KAYAHARD GPH-65” manufactured by Nippon Kayaku Co., Ltd. was used.

  As the polymerization initiator 1, “Perhexa 25B” manufactured by Nippon Oil & Fats Co., Ltd. was used, and “Perhexine 25B” manufactured by Nippon Oil & Fats Co., Ltd. was used as the polymerization initiator 2.

  As a flame retardant, “Exorit OP935” manufactured by Clariant Japan was used.

  In addition, adhesive composition No. 1-20 adjusted the solvent compounding quantity so that solid content might be about 15 thru | or 18 mass%.

  Moreover, “-” in the table means that the raw material is not blended.

<Adhesive composition No. 21>
In addition, adhesive composition No. A polyamide-based adhesive was prepared as 21. This adhesive composition No. No. 21 is obtained by blending 30 parts by mass of polyamide, 25 parts by mass of phosphorus-containing epoxy, 20 parts by mass of phosphorus-containing polyester, 10 parts by mass of benzoxazine, 15 parts by mass of phosphazene, and 5 parts by mass of a curing agent (trimellitic anhydride). It was.

<Adhesive composition No. 22>
In addition, adhesive composition No. No. 22, a commercially available polyamide / epoxy adhesive (“Aron Mighty AST153” manufactured by Toa Gosei Co., Ltd.) was prepared.

<Measurement of physical properties>
The above-mentioned adhesive composition No. About 1-22, the glass transition temperature, the elastic modulus in 30 degreeC in a B stage state, and the elastic modulus in 250 degreeC in a B stage state were measured.

(Elastic modulus)
The elastic modulus was measured according to JIS-K-6868-2 (1999).

(Glass-transition temperature)
The glass transition temperature was measured according to JIS-K-7121 (1987).

<Adhesion test>
Furthermore, the adhesive composition No. 1 to 22 were bonded to a printed wiring board by hot pressing and aftercured, and the air release property and embedding property were evaluated.

  As the printed wiring board, one having an average thickness of the conductive pattern of 24 μm and an interval (width of the concave portion) of the wiring portion of the conductive pattern of 15 μm was used. The hot press conditions were a pressure of 9 MPa, a temperature of 180 ° C., and a time of 60 seconds. After-curing was performed at a temperature of 190 ° C. for 2 hours or at a temperature of 170 ° C. for 2 hours.

(Air release)
Regarding air bleedability, the printed wiring board with the adhesive composition bonded is checked with an optical microscope, “A” indicates that no air dome-shaped bubbles are present on the conductive pattern, and air dome-shaped bubbles are present on the conductive pattern. The thing to do was designated as “B”.

(Embeddability)
Regarding the embedding property, the printed wiring board to which the adhesive composition is adhered is confirmed with an optical microscope, and “A” indicates that there are no small bubbles between the wiring portions of the conductive pattern, and small between the wiring portions of the conductive pattern. The thing with air bubbles was designated as “B”.

<Peel test>
The peel strength of the adhesive composition was measured for a printed wiring board after-cured at 190 ° C. for 2 hours and a printed wiring board after-cured at 170 ° C. for 2 hours.

(Peel strength)
The peel strength was measured according to JIS-K-6854-2 (1999).

<Plating solution resistance test>
Furthermore, after the printed wiring board after-cured at 190 ° C. for 2 hours was treated in the electroless Ni plating treatment process (Ni concentration 5 mL / L, pH 4.6, temperature 87 ° C., immersion time 20 minutes), the adhesive composition was Observe that "A" indicates that the plating solution does not penetrate between the adhesive and the substrate surface. In some cases, the plating solution penetrates between the adhesive and the substrate surface. “B” indicates that there is no risk of functional problems.

  In Table 2 below, the adhesive composition No. The measured physical property values of 1 to 22, the evaluation results in the adhesion test, the peel strength measurement values, and the evaluation results in the plating solution resistance test are shown. In addition, "-" in a table | surface means that the measurement is not performed.

  Thus, adhesive composition No. In Nos. 1 to 20, the evaluation results of air bleeding and embedding were both “A”. No. 21 has an evaluation result of air bleeding property “B”. No. 22 has an evaluation result of embedding property “B”.

  Adhesive composition No. 1-20 and adhesive composition No. Comparing 21 and 22, it can be seen that there is a difference in glass transition temperature and elastic modulus at 30 ° C.

  Therefore, FIG. For the glass transition temperature of 1 to 22 and the elastic modulus at 30 ° C., the evaluation results of “A” for both the air bleedability and embeddability are plotted with white circles “◯” to evaluate the air bleedability. When the result is “A” and the embeddability evaluation result is “B”, a black square “■” is plotted, the air bleedability evaluation result is “B”, and the embeddability evaluation result is “A”. Are plotted with black triangles “▲”.

  Thus, adhesive composition No. whose elastic modulus in 30 degreeC in a B stage state is 900 Mpa or less. Nos. 1 to 21 have good embedding properties and have an adhesive composition No. 1 having a glass transition temperature of 70 ° C. or higher. Each of 1 to 20 and 22 has a good air escape property. That is, the adhesive composition has a good embedding property and a good air bleeding property because the elastic modulus at 30 ° C. in the B-stage state is 900 MPa or less and the glass transition temperature is 70 ° C. or more. I was able to confirm.

  Moreover, adhesive composition No. containing an acrylic polymer. Nos. 16 to 20 had particularly high peel strength when after-curing at 170 ° C. for 2 hours, and the plating solution resistance was particularly good.

  The adhesive composition, the printed wiring board coverlay and the printed wiring board bonding film of the present invention can be suitably used for the production of a printed wiring board.

1 Printed Wiring Board 2 Cover Lay 3 Base Film 4 Conductive Pattern 5 Adhesive Layer 6 Resin Film 7 Adhesive Layer

Claims (8)

  An adhesive composition having an elastic modulus at 30 ° C. in a B-stage state of 900 MPa or less and a glass transition temperature of 70 ° C. or more.   The adhesive composition according to claim 1, comprising polyphenylene ether and a styrenic elastomer.   The adhesive composition according to claim 2, further comprising an acrylic polymer.   The adhesive composition according to claim 2 or 3, wherein the content ratio of the polyphenylene ether to the styrene elastomer is 1/5 or more and 1/2 or less.   The adhesive composition according to claim 1, comprising polyphenylene ether and an acrylic polymer.   A printed wiring board cover lay comprising a resin film and an adhesive layer laminated on one surface side of the resin film and formed from the adhesive composition according to claim 1.   The bonding film for printed wiring boards formed from the adhesive composition of Claim 1.   A printed wiring board comprising the cover lay according to claim 6 or the bonding film according to claim 7 in a cured state of the adhesive composition.

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