JP2007204696A - Resin composition, resin film, cover-lay film, interlayer adhesive agent, metal-clad laminate, flexible printed circuit board, and multilayered circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition for flexible printed circuit board free from flow out of an adhesive layer in heating/pressing, and to provide a cover-lay film obtained by coating the resin composition on a resin film and then drying, and to provide an interlayer adhesive agent obtained by coating and drying the resin composition onto a release film. <P>SOLUTION: The resin composition for flexible printed circuit board comprising an inorganic filler having 1-500 nm of average particle diameter. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resin composition, a resin film, a coverlay film, an interlayer adhesive, a metal-clad laminate, a flexible printed circuit board, and a multilayer circuit board.

  Because flexible printed circuit boards are thin, light, and have excellent flexibility, they are used mainly in mobile devices such as mobile phones, PDAs, and digital cameras. In recent years, these electronic devices have been improved in performance and size. Along with this, miniaturization of wiring on flexible printed circuit boards, high density mounting, and bending resistance are increasingly required.

  Moreover, mounting using lead-free solder that does not contain lead is increasing due to environmental issues, and it is expected that it will become mainstream in the future. In mounting using lead-free solder, the mounting temperature is 15 to 20 ° C. higher than that of normal solder, and accordingly, the flexible printed circuit board is required to have higher heat resistance and higher dimensional stability than ever before.

  Moreover, it is requested | required that a halogen is not included as a flame retardant. As a conventional flame retardant adhesive, a brominated epoxy resin is generally used (for example, Patent Document 1). However, there is a concern about generation of dioxin during combustion, and a halogen-free material is required.

  On the other hand, in terms of heat resistance, thermoplastic polyimide may be used as a material that overcomes heat resistance (for example, Patent Document 2). However, thermoplastic polyimide is still expensive, and uses that can be used in terms of cost are limited.

  Similarly, a coverlay film used for protecting a circuit portion of a flexible printed circuit board is also required to have high heat resistance and high dimensional stability (for example, Patent Document 3). In addition, as a new requirement, when mounting components on a single-sided flexible printed circuit board with low wiring density and low residual ratio of metal foil that becomes a conductor circuit and low circuit board rigidity, the rigidity is low, There is a problem that the circuit board is warped due to thermal stress and the mounted component is displaced from a predetermined position, and a circuit board that is less warped even by heat during mounting is required.

  On the other hand, in addition to these various requirements, coverlay films, metal-clad laminates for flexible printed circuit boards, multilayering of printed circuit boards, etc. Requires an adhesive layer. Until now, these adhesive layers have used urethane resin, polyester resin, epoxy resin, acrylic resin, and the like. However, in these resin systems, a large amount of adhesive flows from between the layers or between the metal layer and the substrate during heating and pressurization, so that sufficient adhesive strength cannot be secured, and the adhesive layer becomes thin. There was a problem that the heat resistance at the time of moisture absorption after curing was inferior.

Japanese Patent Laid-Open No. 11-054934 JP 05-003395 A JP 05-218616 A

  The present invention provides a resin composition used for a flexible printed circuit board, which does not flow out of an adhesive layer when heated and pressurized.

  The resin composition of the present invention is a resin composition used for a flexible printed circuit board, and contains an inorganic filler having an average particle diameter of 1 nm or more and 500 nm or less.

  According to the present invention, by containing a nano-level inorganic filler, it is possible to control the melt viscosity at the time of heating and pressurization, and the flow of resin can be reduced.

  Moreover, the resin composition of this invention can be used as a resin film.

  The resin film of the present invention may be laminated on a covering film to form a coverlay film for a flexible printed circuit board. By carrying out like this, it can be set as the cover-lay film by which the resin film which does not bleed out the adhesive agent at the time of heat-pressing and does not pollute a conductor pad was laminated | stacked.

  The resin film of the present invention may be laminated on a release film to form an interlayer adhesive. By doing so, when used for interlayer adhesion between the rigid board and the flexible circuit board, it is possible to suppress the bleeding of the adhesive from the periphery.

Moreover, it is good also as a metal-clad laminated board for flexible printed circuit boards by laminating | stacking the resin film of this invention on a base material or metal foil, and laminating | bonding with a metal foil or a base material. Moreover, it is good also as a flexible printed circuit board and a multilayer circuit board using a cover-lay film and an interlayer adhesive agent.
The metal-clad laminate may be etched to form a flexible printed circuit board.

  ADVANTAGE OF THE INVENTION According to this invention, it is a resin composition used for a flexible printed circuit board, Comprising: The resin composition which does not flow out of an adhesive bond layer at the time of a heating and pressurization can be provided.

  Hereinafter, the resin composition, resin film, coverlay film, interlayer adhesive, metal-clad laminate, flexible printed circuit board, and multilayer circuit board of the present invention will be described in detail.

The resin composition of the present invention is a resin composition used for a flexible printed circuit board,
An inorganic filler having an average particle diameter of 1 nm or more and 500 nm or less is contained. Therefore, an adhesive having a high melt viscosity at the time of heat lamination is obtained. The melt viscosity at 150 to 200 ° C. is preferably 0.1 or more and 10,000 Pa · s or less, more preferably 1 or more and 5000 Pa · s, and more preferably 2 or more and 1000 Pa · s. preferable. When the thickness is within this range, a circuit board can be obtained with less bleeding of the adhesive during lamination bonding during heating and pressing.
Further, by combining with an epoxy resin or the like, it becomes a resin composition having more excellent adhesion. Furthermore, by containing a reducing agent, the solder bump is melted to reduce the oxide film on the solder surface and the oxide film on the copper foil surface, which is the connected surface, at the time of electrical bonding between the layers, thereby achieving good bonding with high strength. The resin composition is made possible.

  The average particle size of the inorganic filler is preferably 1 nm or more and 500 nm or less, more preferably 1 nm or more and 200 nm or less, and further preferably 1 nm or more and 50 nm or less. Since the specific surface area increases as the particle size decreases, the melt viscosity can be easily controlled even when added in a small amount.

Examples of the inorganic filler used in the present invention include alumina, mica, silica, talc, calcium carbonate, clay, and titanium oxide. Silica is particularly preferable. The dielectric constant of the resin composition obtained by this can be made low. Examples of the silica include a silica filler synthesized by a sol-gel method, a silica filler synthesized by a gas phase method, a fused silica filler, and a crystalline silica filler. In particular, a silica filler synthesized by a gas phase method and a silica filler synthesized by a sol-gel method are preferable.
By containing these inorganic fillers, exudation during heating and pressurization can be suppressed, and moisture absorption heat resistance can be improved.

In addition, in order to improve the dispersibility of the inorganic filler in the resin, it is appropriate to perform a hydrophobic treatment. A silane coupling agent such as alkylethoxysilane, a chlorosilane such as dimethyldichlorosilane, or a silicone oil is a treatment agent. Used as
The inorganic filler is preferably contained in an amount of 1 to 200 parts by weight with respect to 100 parts by weight of the resin composition. If the inorganic filler is within this range, a cured product having excellent rigidity can be obtained.

  The epoxy resin used in the present invention is not particularly limited. For example, bisphenol A, bisphenol F, phenol novolac, cresol novolac, alkylphenol having a biphenyl skeleton, naphthalene skeleton, and dicyclopentadiene skeleton. , Etc. are used by 1 type (s) or 2 or more types.

  As the curing agent used in the present invention, those usually used as curing agents for epoxy resins can be used. For example, an acid anhydride, an amine, an ester resin, a compound containing two or more phenolic hydroxyl groups in one molecule, and the like can be given. Moreover, imidazole etc. can be used for the hardening accelerator used for this invention.

  The elastomer used for this invention should just have rubber-like elasticity. Examples thereof include synthetic rubbers such as polymer epoxy resins, phenoxy resins, acrylic rubbers, acrylonitrile butadiene rubbers, and carboxyl group-containing acrylonitrile butadiene rubbers, modified polyimides, and modified polyamideimides. These can be used individually or in mixture of 2 or more types.

  The compound having a carboxyl group and a phenolic hydroxyl group used in the present invention has at least one carboxyl group and at least one phenolic hydroxyl group in the molecule and may be liquid or solid. Although it does not limit, the following are mentioned as a compound which can be used by this invention. For example, one or more of salicylic acid, shikimic acid, vanillic acid, phenolphthalin, sender-chromium AL, 1,2-dicarboxy-cis-4,5-dihydroxycyclohexa-2,6-diene, etc. Can be used in combination. Among them, an epoxy resin whose base resin is one having two or more phenolic hydroxyl groups, such as shikimic acid, phenolphthalene, 1,2-dicarboxy-cis-4,5-dihydroxycyclohexa-2,6-diene, and the like This is preferable because it is incorporated three-dimensionally into the reaction. Further, the content is preferably 5 to 25% by weight of the resin solid content among the contained components. If it is within this range, the resin composition that melts the bumps and reduces the oxide film on the solder surface and the oxide film on the copper foil surface, which is the connected surface, at the time of electrical bonding between the layers and enables good bonding with high strength Since it becomes a thing, it is preferable.

  Next, the coverlay film will be described.

  The cover lay film of the present invention is preferably produced by applying a varnish obtained by dissolving the above resin composition in a predetermined solvent and a predetermined concentration on the resin film, and then drying at 80 ° C. or higher and 150 ° C. or lower. . About the thickness of the resin composition after drying, it coats so that it may become the range of 10 micrometers or more and 100 micrometers or less by a use. In the case of a coverlay film, a film such as polyethylene terephthalate, polyethylene, or polypropylene may be used as a release film on the surface of the resin composition after drying for the purpose of preventing foreign matter from entering.

  As a solvent used for the varnish, a solvent having good solubility in the resin composition must be selected. For example, one or two of acetone, methyl ethyl ketone, toluene, xylene, n-hexane, methanol, ethanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methoxypropanol, cyclohexanone, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, etc. It is possible to use the above mixed system.

  Examples of the resin film include polyimide resin films such as polyimide resin films, polyetherimide resin films and polyamideimide resin films, polyamide resin films such as polyamide resin films, and polyester resin films such as polyester resin films. Among these, a polyimide resin film is particularly preferably used from the viewpoint of improving the elastic modulus and heat resistance.

  The thickness of the resin film is not particularly limited, but is preferably 1 μm or more and 100 μm or less, and particularly preferably 5 μm or more and 50 μm or less. When the thickness is within this range, the flexibility is particularly excellent.

  Next, the interlayer adhesive will be described.

  The interlayer adhesive of the present invention may be used as an interlayer adhesive by applying the resin composition to a releasable substrate. Examples of the releasable base material include metal foil made of copper or copper alloy, aluminum or aluminum alloy, fluorine resin, polyimide resin, polyester resin such as polybutylene terephthalate, polyethylene terephthalate, etc. Resin film and the like.

When the above resin composition is applied to the releasable substrate, it is usually performed in the form of a varnish. Thereby, coating property can be improved.
The solvent used for preparing the varnish desirably exhibits good solubility in the resin composition, but a poor solvent may be used as long as it does not adversely affect the varnish. For example, acetone, methyl ethyl ketone, toluene, xylene, n-hexane, methanol, ethanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methoxypropanol, cyclohexanone, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, etc. It is possible to use a mixed system of
Moreover, when preparing a varnish, although solid content of a resin composition is not specifically limited, 10 to 90 weight% is preferable, and 30 to 70 weight% is especially preferable.

An interlayer adhesive can be obtained by applying the varnish to the releasable substrate and drying at 80 ° C. or more and 200 ° C. or less.
The resin thickness after coating and drying is preferably adjusted to within ± 20% of the height of the solder bump. If it is not in this range, good bonding is possible, which is preferable.

  Next, the metal-clad laminate will be described.

The metal-clad laminate of the present invention is preferably produced by coating a varnish on one or both sides of a substrate, drying it, and then laminating a metal foil on the resin composition surface with a thermocompression roll or the like.
Examples of the metal constituting the metal foil include copper and a copper-based alloy, aluminum and an aluminum-based alloy, iron and an iron-based alloy, and copper is more preferable.
Examples of the base material include resin films, such as polyimide resin films, polyetherimide resin films, polyamide resin films such as polyamide imide resin films, polyamide resin films such as polyamide resin films, and polyester resin films. A polyester resin film is mentioned. Among these, a polyimide resin film is particularly preferably used from the viewpoint of improving the elastic modulus and heat resistance.

  As a solvent used for the varnish, a solvent having good solubility in the resin composition must be selected. For example, acetone, methyl ethyl ketone, toluene, xylene, n-hexane, methanol, ethanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methoxypropanol, cyclohexanone, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, etc. It is possible to use a mixed system of

  Next, the flexible printed circuit board will be described.

The flexible printed circuit board has a conductive layer on at least one surface of a base material via a first resin composition, and a base material with a second resin composition is laminated on the conductive layer.
The flexible printed circuit board of the present invention is processed by chemically etching the metal foil of the metal-clad laminate obtained as described above. A coverlay film in which unnecessary portions are punched in advance on necessary portions on the circuit is laminated by a general method such as a vacuum heat press or a heat roll.

  Next, a multilayer printed circuit board will be described.

In the multilayer printed circuit board of the present invention, the adhesive layer is superposed on one or both surfaces of the inner circuit board with solder bumps, and the solder bumps are melted to form an oxide film on the solder surface and a connected surface at the time of electrical bonding between the layers. This is a multilayer printed circuit board comprising a good bond with a reduced strength by reducing an oxide film on the surface of a certain copper foil. Furthermore, the resin composition of the present invention is a multilayer printed circuit board that does not need to be removed by washing or the like after soldering, and is heated as it is to become a three-dimensionally crosslinked resin and has excellent adhesion.
Although the temperature to heat is not specifically limited, 100-160 degreeC is preferable as 1st temperature at which an adhesive agent softens, and 200-280 degreeC is preferable as 2nd temperature after which a solder is fuse | melted after that. The three-dimensional crosslinking of the adhesive is performed at the same time as melting the solder, and if necessary, the adhesion can be further improved by after-baking. Although the temperature in that case is not specifically limited, 150-200 degreeC is preferable.
Although the pressure to pressurize is not particularly limited, 0.01 to 5 MPa is preferable and 0.1 to 3 MPa is more preferable at the first temperature. The second temperature is preferably 0.01 to 10 MPa.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

In order to confirm the effectiveness of the resin composition, interlayer adhesive, and multilayer printed circuit board of the present invention, the following multilayer circuit board was prepared and evaluated as follows. The results are shown in Table 1.
-Melt viscosity was measured with a viscoelasticity measuring device (manufactured by Jusco International Co., Ltd.). The conditions were a heating rate of 30 ° C./min and a frequency of 1.0 Hz.
-The amount of seepage after bonding was measured, and 1 mm or less was accepted.
-The appearance after coating on the base material was evaluated, and the product without aggregate was regarded as acceptable.
Moisture-absorbing solder reflow test: After treatment at 30 ° C./60%/168 hours, a solder reflow with a maximum temperature of 260 ° C. was passed three times, and a test without peeling or delamination was regarded as acceptable.
-Temperature cycle test: -65 ° C / 30 minutes to 125 ° C / 30 minutes, conduction resistance before and after 1000 cycle treatment was confirmed, and the change rate was 10% or less.
Insulation resistance after moisture absorption: 30 ° C./85%/DC50V/240 hours, the case where the insulation resistance after moisture absorption after treatment was 10 ⁸ Ω or more was regarded as acceptable.

(Production of multilayer flexible circuit board)
1. 2. Production of Outer Single-Sided Circuit Board As shown in FIG. 2, a flexible copper-clad laminate 110 (Ube Industries, Ltd.) having a 12-μm thick copper foil 101 on a support substrate 102 made of a polyimide film having a thickness of 25 μm as a metal-clad laminate. From the surface on the side of the support base 102, the support base opening 103 having a diameter of 100 μm is formed from the surface of the Iupcel N), and desmearing with an aqueous potassium permanganate solution is performed. After this electrolytic copper plating is performed in the supporting base opening 103 to form a copper post 104 having a height of 15 μm from the surface of the insulating base on the opposite side where the copper foil is present, solder is applied as a metal coating layer 105 covering the copper post 104. Plating is performed to a thickness of 15 μm to form a conductor post 1045.
Next, the copper foil 101 of the one-area layer plate 110 is etched to form a wiring pattern 106, and a thermosetting adhesive (in-house developed material) having a thickness of 25 μm is applied to polyimide having a thickness of 12.5 μm (Apical NPI manufactured by Kaneka Chemical Industry). After the surface coating 107 is applied by laminating the cover lay coated with () by a vacuum press, the surface coating opening 108 is formed and the metal layer coating 109 is applied.
Subsequently, it formed by laminating | stacking the interlayer adhesive (DBF) 111 with a sheet-like reduction | restoration function of the thickness 25micrometer of this invention with a vacuum laminator. Finally, the outer shape was processed to the size of the laminated portion to obtain an outer layer single-sided circuit board 120.

2. Production of Inner-layer Flexible Circuit Board As shown in FIG. 3, after drilling a two-layer double-sided plate 210 (Mitsui Chemicals NEX23FE (25T)) having a copper foil 201 of 12 μm and a supporting base material 202 of a polyimide film thickness of 25 μm. Then, direct plating is performed, and through holes 203 are formed by electrolytic copper plating to form front and back electrical continuity, and then a pad 204 that can receive the wiring pattern and the conductor posts 1045 is formed by etching. After that, a surface coating 206 is formed on the wiring pattern 205 corresponding to the flexible portion 330 by using a thermosetting adhesive (in-house developed material) having a thickness of 25 μm on a polyimide having a thickness of 12.5 μm (Apical NPI manufactured by Kaneka Chemical Industry). did. Finally, it cut | judged to the external size and obtained the inner-layer flexible circuit board 220. FIG.

3. Production of Multilayer Flexible Circuit Board As shown in FIG. 4, the outer-layer single-sided circuit board 120 was laid up on the inner-layer flexible circuit board 220 using a jig with a pin guide for alignment. Thereafter, it was temporarily bonded for positioning with a spot heater at 250 ° C. Next, lamination is performed at 150 ° C. and 0.8 MPa for 90 seconds in a vacuum press, and the conductor post 1045 is molded until it contacts the conductor pad 204, and the circuit of the inner layer flexible circuit board 220 with the conductor pad 204 is molded. Embedded. Next, the post was pressed at 260 ° C. and 0.5 MPa for 60 seconds with a hydraulic press, and the conductor post 1045 was flexible on the inner layer via the 25 μm-thick interlayer adhesive with a reducing function (in-house developed product DBF) 111 of the present invention. The pads 204 of the circuit board 220 were solder-fused to form solder joints and solder fillets, and the layers were joined. Subsequently, in order to cure the adhesive, the temperature was heated at 180 ° C. for 60 minutes to obtain a multilayer flexible circuit board 310 having a multilayer part 320 and a flexible part 330 in which the layers were laminated.
A schematic diagram of the interlayer junction is shown in FIG.

Example 1
5 parts by weight of silica having an average particle diameter of 16 nm (manufactured by Nippon Aerosil Co., Ltd.), 0.5 parts by weight of silane coupling agent octyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.), bisphenol A type epoxy resin (Dainippon) 40 parts by weight of Epiklon 840-S manufactured by Ink Chemical Industry Co., Ltd., 40 parts by weight of Novolak type phenol resin (PR-53647 manufactured by Sumitomo Bakelite Co., Ltd.), YL-6554 manufactured by Japan Epoxy Resin Co., Ltd. 20 parts by weight of number average molecular weight: 14500), 20 parts by weight of salicylic acid (a reagent manufactured by Kanto Chemical Co., Ltd.) and 100 parts by weight of acetone were mixed, stirred and dissolved to obtain a varnish.

  Applying and drying to a 25 μm thick PET film treated with antistatic as the moldable base material with a comma knife coater to a thickness of 25 μm after drying, interlayer adhesion with a sheet-like reducing function An agent (DBF) was prepared. This was used as an adhesive layer as described above to produce a multilayer flexible circuit board. Subsequently, the above-described evaluation was performed.

(Example 2)
An interlayer adhesive was prepared in the same manner except that the silica of Example 1 (manufactured by Nippon Aerosil Co., Ltd.) was replaced with alumina having an average particle diameter of 13 nm (manufactured by Nippon Aerosil Co., Ltd.). Thereafter, a multilayer flexible circuit board was prepared. Next, the evaluation described above was performed.

(Example 3)
An interlayer adhesive was prepared in the same manner except that the silica of Example 1 (manufactured by Nippon Aerosil Co., Ltd.) was changed to 30 parts by weight of silica having an average particle diameter of 500 nm (manufactured by Admatex Co., Ltd.). Thereafter, a multilayer flexible circuit board was prepared. Next, the evaluation described above was performed.

(Comparative Example 1)
An interlayer adhesive was prepared in the same manner as in Example 1 except that it did not contain the silica of Example 1 (manufactured by Nippon Aerosil Co., Ltd.). Thereafter, a multilayer flexible circuit board was prepared. Next, the evaluation described above was performed.
(Comparative Example 2)
An interlayer adhesive was prepared in the same manner as in Example 1 except that the silica of Example 1 (manufactured by Nippon Aerosil Co., Ltd.) was changed to silica having an average particle diameter of 2000 nm (manufactured by Admatex Co., Ltd.). Thereafter, a multilayer flexible circuit board was prepared. Next, the evaluation described above was performed.

・溶融粘度は、粘弾性測定装置（ジャスコインターナショナル(株)製）で測定した。条件は昇温速度３０℃／ｍｉｎ、周波数１．０Ｈｚとした。
・接合後の染み出し量を測定し、１ｍｍ以下を合格とした。
・基材への塗膜後の外観を評価し、凝集物のないものを合格とした。
・吸湿半田リフロー試験：３０℃／６０％／１６８時間処理後、最高温度２６０℃のはんだリフローを３回通し剥離やデラミがないものを合格とした。
・温度サイクル試験：−６５℃／３０分⇔１２５℃／３０分、１０００サイクル処理前後の導通抵抗を確認し、変化率が１０％以下の場合を合格とした。
・吸湿後の絶縁抵抗：３０℃／８５％／ＤＣ５０Ｖ／２４０時間処理後の吸湿後の絶縁抵抗が１０⁸Ω以上の場合を合格とした。

-Melt viscosity was measured with a viscoelasticity measuring device (manufactured by Jusco International Co., Ltd.). The conditions were a heating rate of 30 ° C./min and a frequency of 1.0 Hz.
-The amount of seepage after bonding was measured, and 1 mm or less was accepted.
-The appearance after coating on the base material was evaluated, and the product without aggregate was regarded as acceptable.
Moisture-absorbing solder reflow test: After treatment at 30 ° C./60%/168 hours, a solder reflow with a maximum temperature of 260 ° C. was passed three times, and a test without peeling or delamination was regarded as acceptable.
-Temperature cycle test: -65 ° C / 30 minutes to 125 ° C / 30 minutes, conduction resistance before and after 1000 cycle treatment was confirmed, and the change rate was 10% or less.
Insulation resistance after moisture absorption: 30 ° C./85%/DC50V/240 hours, the case where the insulation resistance after moisture absorption after treatment was 10 ⁸ Ω or more was regarded as acceptable.

  Since a pad-on-via structure can be adopted, it is possible to obtain a small and thin multilayer circuit board corresponding to higher density mounting. As a result, it is used in mobile devices that require high functionality and downsizing, such as mobile phones, digital video cameras, digital cameras, and small notebook personal computers.

A joint by solder bumps using the adhesive layer of the present invention. Due to the reducing action of this adhesive, the solder spreads over the adherend.

Sectional drawing for demonstrating the outer-layer single-sided circuit board for multilayer circuit board preparation for confirming the effectiveness of the adhesive bond layer of this invention, and its manufacturing method.

Sectional drawing for demonstrating the inner-layer flexible circuit board for multilayer circuit board preparation for confirming the effectiveness of the adhesive bond layer of this invention, and its manufacturing method.

Sectional drawing for demonstrating the multilayer flexible circuit board of the 4 layer structure for confirming the effectiveness of the adhesive bond layer of this invention, and its manufacturing method.

Explanation of symbols

101, 201: Copper foil 102, 202: Support base material 103: Support base material opening 104: Copper post 1045: Conductor post 105: Metal coating layer 106, 205: Wiring pattern 107, 206: Surface coating 108: Surface coating opening Part 109: Metal layer coating 110: Flexible copper clad laminate 111: Interlayer adhesive 120: Outer layer single-sided circuit board 203: Through hole 204: Pad 210: Two-layer double-sided board 220: Inner-layer flexible circuit board 310: Multilayer flexible circuit board ( 4 layers)
320: Multilayer part 330: Flexible part

Claims (15)

A resin composition used for a flexible printed circuit board,
A resin composition comprising an inorganic filler having an average particle diameter of 1 nm or more and 500 nm or less.   The resin composition according to claim 1, wherein the resin composition has a melt viscosity at 150 ° C. to 200 ° C. of 0.1 Pa · s or more and 10,000 Pa · s or less.   The resin composition according to claim 1 or 2, further comprising a coupling agent in the resin composition.   The resin composition according to claim 3, wherein the coupling agent is aminosilane.   The resin composition according to claim 1, wherein the inorganic filler contains alumina or silica.   6. The resin composition according to claim 1, wherein the content of the inorganic filler is 1 part by weight or more and 200 parts by weight or less with respect to 100 parts by weight of the resin composition.   The resin composition according to any one of claims 1 to 6, wherein the resin composition comprises (A) an epoxy resin, (B) a curing agent for epoxy resin, (C) a curing accelerator, and (D) an elastomer. object.   The resin composition according to any one of claims 1 to 7, further comprising a compound having a carboxyl group and a phenolic hydroxyl group.   A resin film obtained from the resin composition according to claim 1.   The coverlay film which laminated | stacked the resin film of Claim 9 on the coating film.   The interlayer adhesive which laminated | stacked the resin film of Claim 9 on the release film.   A metal-clad laminate for a flexible printed circuit board, wherein the resin film according to claim 9 is laminated on a substrate or a metal foil, and then laminated and adhered to the metal foil or the substrate.   A flexible printed circuit board obtained by laminating the coverlay film according to claim 10 on at least one side.   A multilayer circuit board obtained by laminating and bonding the interlayer adhesive according to claim 11 between the layers. A flexible printed circuit board obtained by etching the metal-clad laminate according to claim 12.

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