KR102190760B1 - Connector and flexible wiring board - Google Patents

Abstract

An insertion-side connector inserted into a mating connector and used to connect wiring is disclosed.
The connector is disposed on the end of the flexible substrate on the side opposite to the flexible substrate, the wiring terminal disposed on one side of the flexible substrate, and the wiring terminal of the flexible substrate, and facing the flexible substrate A resin layer containing a resin and having a surface is provided.
The end of the connector on the tip side of the resin layer has a surface forming a convex curved surface that curves from the opposite surface toward the flexible substrate.

Description

Connector and flexible wiring board{CONNECTOR AND FLEXIBLE WIRING BOARD}

The present invention relates to a connector and a flexible wiring board.

Conventionally, single-sided, double-sided, or multi-layered various printed wiring boards are widely used in the field of industrial equipment or consumer equipment. In electronic devices, only one printed wiring board is rarely used, and for example, a plurality of printed wiring boards divided by function is used. Usually, a plurality of wiring boards are connected by various connectors.

Flexible wiring boards are composed of base materials such as polyimide, conductor materials, adhesives, and coverlays as basic materials, and are recently assembled in mobile phones, video cameras, and notebook computers due to the lightness, thinness, and reduction of electronic devices. Has been. Since the flexible wiring board has low rigidity, it is generally mounted with a reinforcing member (reinforcing plate) attached to a mounting portion of an electronic component and a connector portion (for example, Patent Document 1).

As the reinforcing plate of the flexible wiring board, a polyester film, a metal plate such as a stainless steel plate and an aluminum plate, a ceramic, and a glass cloth-based epoxy resin laminated plate are used. However, a thick polyimide film excellent in punching processability, heat resistance and processability has become the mainstream of reinforcing plates for connectors. The reinforcing plate is pasted on the substrate on the side opposite to the wiring terminal arranged on one side of the substrate through an adhesive (see, for example, Non-Patent Document 1).

Patent Document 1: Unexamined Patent Publication No. 2005-51177

Non-Patent Document 1: Electronic Materials, October 2004

However, in the connector described in Patent Literature 1 and Non-Patent Literature 1, which has a polyethylene terephthalate film or a polyimide film as a reinforcing plate, there are cases where the insertion into the mating connector is not smoothly performed.

Therefore, an object of the present invention is to provide a connector having smooth insertability and a flexible wiring board provided with the same.

The present invention relates to an insertion-side connector inserted into a mating connector and used for connecting wiring. The connector according to the present invention includes a flexible substrate, a wiring terminal disposed on one side of the flexible substrate, and on the end of the flexible substrate on the side opposite to the wiring terminal of the flexible substrate. It is disposed and has a resin layer containing a resin and having a surface facing the flexible substrate. The front end of the connector of the resin layer may have a surface forming a convex curved surface that curves from the opposite surface toward the flexible substrate.

When inserting the connector into the mating connector, the resin layer has a surface that forms a convex curved surface that curves toward the flexible substrate from the opposite surface facing the flexible substrate. The sense of resistance is reduced, and a sufficiently smooth insertability is obtained.

The resin layer may further contain an inorganic filler. The inorganic filler may be, for example, silica particles. The content of the inorganic filler in the resin layer may be 30 to 70% by volume relative to the volume of the resin layer.

The flexible substrate may be a polyester substrate or a polyimide substrate. The thickness of the flexible substrate may be 75 μm or less.

The initial tensile modulus of the resin layer at 25° C. may be 0.3 to 3.0 GPa. The thickness of the resin layer may be 50 to 500 µm.

The present invention further relates to a flexible wiring board including the connector, a flexible substrate for circuits, and a circuit provided on the flexible substrate for circuits and connected to wiring terminals of the connector. The flexible substrate of the connector and the flexible substrate for circuits may be the same single substrate, or the flexible substrate of the connector and another flexible substrate for circuits may be connected.

According to the present invention, a connector having smooth insertability and a flexible wiring board having the same can be provided.

1 is a schematic diagram showing an embodiment of a connector.
[Fig. 2] It is a cross-sectional view taken along the line II-II' of the connector shown in Fig. 1.
3 is a cross-sectional view showing a modified example of the shape of a resin layer.
[Fig. 4] It is a cross-sectional view showing another embodiment of a connector.
[Fig. 5] It is a cross-sectional view showing another embodiment of a connector.
[Fig. 6] It is a cross-sectional view showing another embodiment of a connector.
Fig. 7 is a process chart showing an embodiment of a method for manufacturing a connector.
Fig. 8 is a schematic explanatory diagram showing a method of testing the durability of a connector.
Fig. 9 is an optical micrograph of a cross section of a connector.
Fig. 10 is a scanning electron micrograph of a cross section of a resin layer.

Hereinafter, preferred embodiments of the present invention will be described in detail. However, this invention is not limited to the following embodiment. All configurations described in this specification can be arbitrarily combined within a range not departing from the spirit of the present invention. For example, numerical ranges related to various characteristics can be defined by using as the upper or lower limit values arbitrarily selected from the upper and lower limits of the numerical range described in the present specification, and the numerical values described in Examples.

1 is a schematic diagram showing an embodiment of a connector. FIG. 2 is a cross-sectional view taken along line II-II' of FIG. 1. The connector 10 shown in FIGS. 1 and 2 includes a flexible substrate 2, a wiring terminal 1 disposed on one side of the flexible substrate 2, and a wiring terminal of the flexible substrate 2 ( It is composed of a resin layer 3 disposed on the end of the flexible substrate 2 on the side opposite to 1). The rigidity of the flexible substrate 2 is higher in a portion in contact with the resin layer 3 compared to the case where the resin layer 3 is not formed. The connector 10 is an insertion-side connector inserted into a mating connector and used to connect wiring. By inserting the end of the connector 10 into the mating connector, a state in which transmission is possible by, for example, mechanical or electrical (electronic) connection is obtained. The connector 10 can be safely and easily detached as needed.

In FIG. 2, a flexible substrate 52 for a circuit and a circuit 51 provided on the flexible substrate 52 for a circuit are shown together with the connector 10. The circuit 51 is connected to the wiring terminal 1 of the connector 10. The flexible wiring board 100 is constituted by the connector 10, the flexible substrate 52 for circuits and the circuit 51. The flexible substrate 2 of the connector and the flexible substrate 52 for circuits may be the same one or each of the substrates connected to each other.

The flexible substrate 2 is not particularly limited as long as it shows flexibility that can be bent, but may be a polyester substrate (polyester film) or a polyimide substrate (polyimide film) from the viewpoint of toughness. , In terms of toughness and heat resistance, a polyimide base material (polyimide film) may be used. The thickness of the flexible substrate 2 may be 75 μm or less in terms of bendability. The thickness of the flexible substrate 2 may be 10 μm or more.

The wiring terminal 1 is, for example, a conductor layer formed of a conductor such as metal. The thickness of the wiring terminal 1 may be 5 to 40 µm.

The resin layer 3 usually contains a cured product of a curable resin composition as a resin. Details of the curable resin composition used to form the resin layer 3 will be described later.

The resin layer 3 is a surface positioned on the opposite side of the surface in contact with the flexible substrate 2 and has a counter surface 6 facing the flexible substrate 2. The end 3a of the front end side of the connector 10 of the resin layer 3 (the side that is the part inserted into the counterpart connector) is curved from the opposite surface 6 toward the flexible substrate 2, It has a surface 7 which forms a convex curved surface that is convex toward the outside of the resin layer 3. When the surface 7 of the end portion 3a of the resin layer 3 forms a convex curved surface, the resistance at the time of insertion into the mating connector decreases, and smooth insertability is obtained.

In the connector according to the present embodiment, the end portion of the resin layer 3 on the opposite side to the front end of the connector 10 is also curved from the opposite surface 6 toward the flexible substrate 2 to form a convex curved surface. Has. However, the surface of the end of the connector 10 on the opposite side to the front end does not have to have a convex curved surface. Further, the end of the resin layer 3 on the side of the connector 10 may have a surface in which the opposite surface 6 is curved toward the flexible substrate 2 to form a convex curved surface. .

The surface of the end portion 3a of the resin layer 3 (the surface of the portion not in contact with the flexible substrate 2) should just form a convex curved surface. The end portion 3a of the resin layer 3 may have a surface forming a plane along the line of the main surface of the flexible substrate, as in the embodiment of FIG. 2. 3A and 3B are cross-sectional views illustrating a modified example of the shape of a resin layer. In the case of the embodiment shown in FIG. 3B, the entire side surface of the end portion 3a of the resin layer 3 on the front end side of the connector forms a convex curved surface.

The thickness of the resin layer 3 may be 50 to 500 µm, 70 to 300 µm, or 75 to 200 µm. When the thickness of the resin layer 3 is within these ranges, formation of the resin layer is easy. In addition, since the resin layer 3 is not easily bent, particularly excellent connector shape retention is obtained. The length of the resin layer 3 in the connector insertion direction may be, for example, 3 to 30 mm. The resin layer 3 may be provided over the entire width direction of the flexible substrate, or may be provided only in a partial region in the width direction within a range in which required rigidity is obtained.

The initial tensile modulus of the resin layer 3 at 25° C. may be 0.3 to 3.0 GPa, 0.5 to 2.5 GPa, or 1.0 to 2.2 GPa. When the initial tensile modulus of the resin layer 3 is within these ranges, cracks in the resin layer 3 are less likely to occur, and further superior insertability can be obtained.

The initial tensile modulus of the resin layer 3 at 25°C can be obtained from the maximum value of the slope of the tangent line of the stress-displacement curve obtained when tensile stress is applied to the rectangular resin layer at a tensile speed of 50 mm/min. The rectangular resin layer can be prepared, for example, by cutting out from a plate-shaped resin layer formed by curing a curable resin composition described later. Details of the method of measuring the initial tensile modulus will be described in detail in Examples to be described later.

The initial tensile modulus within the above numerical range can be achieved by, for example, a resin layer further containing an inorganic filler in addition to the resin.

The inorganic filler in the resin layer 3 may be composed of one type of particle or may be composed of a combination of two or more types of particles. The average particle diameter of the inorganic filler may be 1 to 100 µm, 1 to 50 µm, 1 to 20 µm, or 1.5 to 10 µm. The inorganic filler may be a mixture of plural types of fillers having different average particle diameters. Thereby, it is possible to increase the space filling rate by the inorganic filler.

The average particle diameter of the inorganic filler is the arithmetic average of the particle diameters (maximum diameters) of the plurality of inorganic fillers observed by observing the resin layer 3 with a scanning electron microscope (Scanning Electron Microscope) at, for example, 1000 times magnification. . The number of inorganic fillers whose particle diameter is measured in order to obtain the average particle diameter is 50 or more.

The content of the inorganic filler in the resin layer 3 is 30 to 70% by volume, 40 to 65% by volume, or 50 to 65% by volume of the resin layer 3 in terms of strength and initial tensile modulus of the resin layer. It may be volume %. In addition, the content of the inorganic filler in the resin layer 3 is 40 to 85% by mass, 45 to 80% by mass, or 50 to the mass of the resin layer 3 in terms of strength and initial tensile modulus of the resin layer. It may be -80 mass%.

The inorganic filler may contain silica particles. The silica particles are not particularly limited, and may be, for example, spherical silica, crushed silica refined by pulverization, dry silica or wet silica.

When spherical silica particles are selected, the surface of the resin layer 3 becomes smooth, and smooth insertability is obtained. In addition, it is also possible to obtain more excellent wear resistance and crack resistance.

Spherical silica particles can be obtained, for example, by a sol-gel method. The average particle diameter of the spherical silica particles may be 0.05 to 50 µm, 0.1 to 50 µm, 0.2 to 30 µm, or 0.5 to 20 µm.

The spherical silica particles need only have a shape that is almost spherical (refer to JIS Z2500:2000), and does not necessarily have a complete spherical shape. The ratio (DL)/(DS) of the long diameter (DL) and the short diameter (DS) of the particles (sometimes referred to as a spherical coefficient or sphericity degree) may be 1.0 to 1.2. .

As the spherical silica particles, MSR-2212, MSR-SC3, MSR-SC4, MSR-3512, MSR-FC208 (above, the brand name manufactured by Tatsumori Co., Ltd.), Exerica (trade name manufactured by Kuyama Corporation), SO-E1 , SO-E2, SO-E3, SO-E5, SO-E6, SO-C1, SO-C2, SO-C3, SO-C5, SO-C6, SO-25R (above, made by Adomatech Co., Ltd. Brand name), FB-5D, FB-12D, FB-20D, FB-105, FB-940, FB-9454, FB-950, FB-105FC, FB-870FC, FB-875FC, FB-9454FC, FB-950FC , FB-105FD, FB-970FD, FB-975FD, FB-950FD, FB-300FD, FB-300FD, FB-400FD, FB-400FE, FB-7SDC, FB-5SDC, FB-3SDC (above, Denki Chemical High School Co., Ltd. brand name), etc. are mentioned.

The silica particles may be surface-treated. Surface treatment agents used to surface-treat silica particles include, for example, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-glycylate. Doxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane , p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltri Ethoxysilane, 3-acryloxypropyltrimethoxysilane, n-2-(aminoethyl)-3-aminopropyl methyldimethoxysilanetriethoxysilane, n-2-(aminoethyl)-3-aminopropyltrime Toxoxysilane, n-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1 ,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, 3- Ureidepropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatepropyltriethoxysilane, dimethyl It is 1 type or 2 or more types selected from the group consisting of polycondensates of silane, polycondensates of diphenylsilane, and cocondensates of dimethylsilane and diphenylsilane. Among these, N-phenyl-3-aminopropyltrimethoxysilane can be selected from the viewpoint of compatibility with an acrylic resin.

The resin layer 3 may contain fumed silica as an inorganic filler. The fumed silica is used in some cases to control the printability of the liquid composition described later used to form the resin layer 3. As commercially available products of fumed silica, hydrophilic silicas such as Aerosil 50, 90G, 130, 200, 300 and 380, and R972, R972CF, R972V, R974, R9765, R140, RX50, NAX50, NX90G, RX200, RX300, R812 , Hydrophobic silicas such as R8200 and R200H (above, Nippon Aerosil Co., Ltd. brand name).

4 is a cross-sectional view showing another embodiment of a connector. The flexible substrate 2 of the connector 10 shown in FIG. 4 is composed of a flexible substrate 40 and a cover film 41 provided on the main surface of the flexible substrate 40 on the resin layer 3 side. The cover film 41 can function as, for example, a film for protecting the wiring terminal 1 or a solder resist. The cover film 41 may be provided on the main surface of the flexible substrate 40 on the side of the wiring terminal 1, or may be provided on both surfaces of the flexible substrate 40. As the flexible substrate 40, the same substrate as the flexible substrate 2 can be used.

The cover film 41 can be formed using various thermosetting or photosensitive resin films. As a commercial item of the resin film used to form the cover film 41, for example, Nikaflex CTSV, CISV, CISA, CKSE, CISG, CKSG (above, Nikkan Kogyo Co., Ltd. brand name), Pyralux PC1000 (Above, DuPont's brand name), Raytech FR-7025, FR-7038, FR-7050, FZ-2520G, FZ-2525G, FZ-2530G, FZ-2535G (above, Hitachi Kasei Corporation's product name) Brand name).

5 is a cross-sectional view showing another embodiment of a connector. The flexible substrate 2 of the connector shown in FIG. 5 includes a flexible substrate 40, a non-wiring metal layer 42 and a cover film 41 which are sequentially provided on the main surface of the flexible substrate 40 on the resin layer 3 side. ). As shown in FIG. 6, the flexible substrate 2 is composed of a flexible substrate 40 and a non-wiring metal layer 42 provided on the main surface of the flexible substrate 40 on the resin layer 3 side, and a cover film You don't have to have (41).

The connector 10 includes, for example, a step of providing a wiring terminal 1 on one side of the flexible substrate 2 and a resin layer on the side opposite to the wiring terminal 1 of the flexible substrate 2 It can be manufactured by a method including a step of forming (3). The wiring terminal 1 may be provided before the resin layer 3 is formed, or may be provided after the resin layer 3 is formed.

The resin layer 3 can be formed, for example, by a method including a step of applying a curable resin composition and a liquid composition (liquid ink) containing an inorganic filler to a flexible substrate, if necessary. . According to a method using such a liquid composition, a rigid resin layer can be formed in a simple process. The thickness of the resin layer can be easily and precisely controlled according to a method such as printing. Therefore, it is possible to efficiently manufacture products with different thickness specifications. Further, according to a method such as printing, it is possible to form a resin layer very efficiently at an arbitrary position on the flexible substrate, without manual intervention. Furthermore, a resin layer excellent also in reflow resistance can be formed.

7 is a process diagram showing an embodiment of a method of forming the resin layer 3 using the liquid composition 5. First, a liquid composition 5 containing a curable resin composition and a metal mask 4 having an opening 4a are prepared (see Fig. 7(a)). The liquid composition 5 may contain a solvent in which the curable resin composition is dissolved or dispersed.

Next, the liquid composition 5 is filled in the opening 4a of the metal mask 4 and printed on the flexible substrate 2 (see Fig. 7(b)). The method of applying the liquid composition can be appropriately selected by screen printing, bar coater, etc. in addition to printing using a metal mask.

From the applied liquid composition 5, the solvent is removed by a method such as heating as necessary, and an uncured resin layer 3 is formed (see Fig. 7(c)). By curing the curable resin composition in the uncured resin layer 3, the resin layer 3 containing a cured product of the curable resin composition as a resin is formed. Curing of the curable resin composition can be performed, for example, by heating or irradiation with light. The metal mask 4 can be removed after application of the curable resin composition, for example. According to the method of applying and curing the liquid composition, it is possible to easily form a resin layer having an end portion on which a convex curved surface is formed.

The solvent removal (drying) and curing temperature may be 50 to 250°C, 80 to 200°C, or 100 to 190°C.

For example, by punching the flexible substrate 2, the resin layer 3 can be disposed on the end of the flexible substrate 2 (see Fig. 7(d)).

The liquid composition 5 may contain, for example, a curable resin composition, the above-described inorganic filler, and a solvent. The curable resin composition is composed of components other than a solvent and an inorganic filler in the liquid composition 5, and contains, for example, a curable resin cured by heat and/or light, and a thermoplastic resin. The curable resin contains, for example, one or two or more epoxy resins. The thermoplastic resin contains, for example, one or two or more types of acrylic resins (polymers of acrylic monomers).

Epoxy resins are polyglycis obtained by reacting polyhydric phenols such as bisphenol A, novolac-type phenol resin and orthocresol novolac-type phenol resin, or polyhydric alcohols such as 1,4-butanediol with epichlorohydrin. Polyglycidyl ester obtained by reacting polybasic acids such as diether, phthalic acid and hexahydrophthalic acid with epichlorohydrin, N-glycidyl derivatives of compounds having an amino group, amide group, or heterocyclic nitrogen base, and alicyclic It is selected from formula epoxy resin. From what has high compatibility with an acrylic resin, a biphenylaralkyl type epoxy resin can be selected.

The curable resin may contain an epoxy resin curing agent. The curing agent is, for example, selected from dicyandiamide, diaminodiphenylmethane, diaminodiphenylsulfone, phthalic anhydride, pyromellitic anhydride, and polyfunctional phenols (phenolic resins) such as phenol novolac and cresol novolac. I can.

The phenol resin may contain a phenol type, a bisphenol A type, a cresol novolak type, or an aminotriazine novolak type phenol resin. One or both of a cresol novolak type and an aminotriazine novolak type phenolic resin can be selected from the viewpoint of compatibility with an acrylic resin. The aminotriazine novolac-type phenol resin has a structural unit represented by the following structural formula (I).

[In formula (I), R represents a hydrogen atom or a methyl group, and n represents an integer of 1 to 30.]

The curable resin may contain a high molecular weight component for the purpose of improving the heat resistance of the resin layer. However, the molecular weight of the component constituting the curable resin is usually 3000 or less.

The curable resin may contain an accelerator for the purpose of accelerating the curing reaction. The type and amount of the accelerator are not particularly limited. For example, one or two or more selected from imidazole-based compounds, organophosphorus compounds, tertiary amines, quaternary ammonium salts, and the like are used.

The acrylic resin is generally a copolymer containing as a monomer unit a polymerizable monomer containing two or more types of acrylic monomers having an acrylic group or a methacrylic group. The acrylic resin can be manufactured inexpensively by selecting various combinations from commercially available acrylic monomers according to desired properties. The acrylic resin is excellent in that it has good solubility in a low boiling point ketone-based solvent, so that the printed liquid composition can be easily dried.

The acrylic monomer used for producing the acrylic resin is not particularly limited. Acrylic resins are, for example, acrylonitrile, methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, pentyl acrylate, n-hexyl acrylate , 2-ethylhexyl acrylate, n-octyl acrylate, dodecyl acrylate, octadecyl acrylate, butoxyethyl acrylate, phenyl acrylate, benzyl acrylate, naphthyl acrylate, cyclohexyl acrylate, isobornyl acrylate, methyl acrylate, norbornyl methyl acrylate, acrylic acid Tricyclo[5.2.1.O ^2,6 ]deca-8-yl(dicyclopentanylacrylate), acrylic acid tricyclo[5.2.1.O ^2,6 ]deca-4-methyl, adamantyl acrylate, acrylic acid Isobornyl, norbonyl acrylate, tricyclohexyl acrylate[5.2.1.O ^2,6 ]deca-8-yl, tricyclohexyl acrylate[5.2.1.O ^2,6 ]deca-4-methyl acrylate, and acrylic acid Acrylic acid esters such as adamantyl, and ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, Pentyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, butoxyethyl methacrylate, phenyl methacrylate, meth Naphthyl acrylate, cyclopentyl methacrylate, cyclohexyl methacrylate, methyl cyclohexyl methacrylate, tricyclohexyl methacrylate, norbornyl methacrylate, methyl norbonyl methacrylate, isobornyl methacrylate, Bornyl methacrylate, menthyl methacrylate, adamantyl methacrylate, tricyclo methacrylate[5.2.1.O ^2,6 ]deca-8-yl (dicyclopentanyl methacrylate), and trimethacrylic acid One or two or more types of acrylic monomers selected from methacrylic acid esters such as cyclo[5.2.1.O ^2,6 ]deca-4-methyl are included as a monomer unit.

From the point of heat resistance and adhesiveness of the resin layer according to the present embodiment, the acrylic monomer constituting the acrylic resin may contain a monomer having a functional group. The monomer having a functional group may have at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group, an acid anhydride group, an amino group, an amide group, and an epoxy group, and at least one polymerizable carbon-carbon double bond. . Specific examples of the monomer having a functional group include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, and itaconic acid, acrylic acid-2-hydroxyethyl, methacrylic acid-2-hydroxyethyl, acrylic acid-2-hydroxypropyl, and meta. Acrylic acid-2-hydroxypropyl, and N-methylol methacrylamide, hydroxyl group-containing monomers such as (o-, m-, p-)hydroxystyrene, acid anhydride group-containing monomers such as maleic anhydride, acrylic Amino group-containing monomers such as diethylaminoethyl acid and diethylaminoethyl methacrylate, and glycidyl acrylate, glycidyl α-ethyl acrylate, glycidyl α-n-propyl acrylate, and 3,4-epoxybutyl acrylate , Methacrylic acid-3,4-epoxybutyl, acrylic acid-4,5-epoxypentyl, acrylic acid-6,7-epoxyheptyl, methacrylic acid-6,7-epoxyheptyl, acrylic acid-3-methyl-4-epoxy Butyl, methacrylate-3-methyl-3,4-epoxybutyl, acrylate-4-methyl-4,5-epoxypentyl, methacrylate-4-methyl-4,5-epoxypentyl, -5-methyl acrylate -5,6-epoxyhexyl, acrylic acid-β-methylglycidyl, methacrylic acid-β-methylglycidyl, α-ethylacrylic acid-β-methylglycidyl, acrylic acid-3-methyl-3,4- Epoxybutyl, methacrylate-3-methyl-3,4-epoxybutyl, acrylate-4-methyl-4,5-epoxypentyl, methacrylate-4-methyl-4,5-epoxypentyl, acrylic acid-5- Epoxy group-containing monomers, such as methyl, 6-epoxyhexyl, and methacrylate-5-methyl-5,6-epoxyhexyl, are mentioned. These can be used alone or in combination of two or more.

When the acrylic resin has a glycidyl group, the heat resistance of the resin layer becomes higher. Therefore, the acrylic resin may contain glycidyl methacrylate or glycidyl acrylate as a monomer unit. Based on the amount of all polymerizable monomers constituting the acrylic resin, the content ratio of glycidyl methacrylate or glycidyl acrylate is 0.5 to 10 mass%, 1 to 8 mass%, or 2 to 5 mass %.

The acrylic resin may contain an alkyl acrylate as a monomer from the point of adhesiveness between a flexible base material and a resin layer. The number of carbon atoms in the alkyl group of the alkyl acrylate may be 1 to 12 or 2 to 10. Based on the amount of all polymerizable monomers constituting the acrylic resin, the content ratio of the alkyl acrylate may be 50 to 99% by mass, 60 to 98% by mass, or 70 to 96% by mass. The alkyl acrylate is selected from, for example, ethyl acrylate and butyl acrylate.

The acrylic resin may contain acrylonitrile or methacrylonitrile as a monomer unit from the viewpoint of toughness and adhesiveness. Based on the amount of all polymerizable monomers constituting the acrylic resin, the content ratio of acrylonitrile or methacrylonitrile may be 0.5 to 10 mass%, 1 to 8 mass%, or 2 to 5 mass%.

The acrylic resin may further contain another monomer copolymerized with an acrylic monomer. Other monomers are, for example, 4-vinylpyridine, 2-vinylpyridine, α-methylstyrene, α-ethylstyrene, α-fluorostyrene, α-chlorstyrene, α-bromostyrene, fluorostyrene, chloro Aromatic vinyl compounds such as styrene, bromostyrene, methylstyrene, methoxystyrene, and styrene, and N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, Ni-propylmaleimide, N-butylmaleimide Selected from N-substituted maleimides such as mid, Ni-butylmaleimide, Nt-butylmaleimide, N-laurylmaleimide, N-cyclohexylmaleimide, N-benzylmaleimide, and N-phenylmaleimide It is at least one kind of compound.

The weight average molecular weight of the acrylic resin may be 150,000 to 1.8 million, 400,000 to 1.5 million, or 500,000 to 1.4 million. When the weight average molecular weight of the acrylic resin is 150,000 or more, the viscosity of the liquid composition is high, and the liquid composition can exhibit thixotropy. When the weight average molecular weight of the acrylic resin is 1.8 million or less, the solubility in the solvent is improved, and it becomes easy to increase the concentration of the solid content in the liquid composition. When the concentration of the solid content of the liquid composition is high, the need to consider the control of the film thickness of the applied liquid composition and the reduction of the film pressure due to drying shrinkage decreases.

The glass transition temperature (Tg) of the acrylic resin may be -50 to 100°C, -45 to 20°C, or -40°C to 5°C. The Tg of an acrylic resin composed of n types of monomers can be calculated by the following calculation formula (FOX formula).

Tg(℃)={1/(W ₁ /Tg ₁ +W ₂ /Tg ₂ +…+W _i /Tg _i +…+W _n /Tg _n )}-273

In the FOX formula, Tg _i (K) represents the glass transition temperature of the homopolymer of each monomer, W _i represents the mass fraction of each monomer, and W ₁ +W ₂ +... +W _i +...W _n =1.

For example, the glass transition of an acrylic resin obtained by copolymerizing glycidyl methacrylate at a ratio of 5% by mass, acrylonitrile at 5% by mass, ethyl acrylate at 85% by mass, and butyl acrylate at 5% by mass The temperature Tg is calculated as follows.

Tg={1/(0.05/319+0.05/498+0.85/251+0.05/219)}-273=-14.7℃

Based on the total mass of a thermoplastic resin (for example, acrylic resin), a curable resin (for example, an epoxy resin) and a curing agent (for example, a phenol resin), the content of the thermoplastic resin is 40 to 90% by weight, 50 It may be -85% by weight, or 60-80% by weight. At this time, the sum of the glycidyl group of the acrylic resin and the epoxy group of the epoxy resin and the amount of hydroxyl groups of the phenol resin may be substantially equivalent.

The liquid composition 5 can be prepared, for example, by a method of mixing and stirring each component constituting the curable resin composition and a solvent as necessary. When the liquid composition 5 contains an inorganic filler, a liquid composition may be prepared using a slurry obtained by dispersing the inorganic filler in an organic solvent containing a surface treatment agent in advance. Further, a mixture of curable resin composition components containing a curable resin may be prepared in advance, and a liquid composition may be obtained by mixing the mixture and the slurry of an inorganic filler.

The solvent used to dissolve or disperse the curable resin composition and the inorganic filler is selected from ketone solvents such as methyl ethyl ketone and cyclohexanone, for example. From the viewpoint of printability, cyclohexanone can be selected.

Example

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these.

Manufacturing Example 1

After dissolving 3.0 g of N-phenyl-3-aminopropyltrimethoxysilane (KBM573, a brand name manufactured by Shin-Etsu Silicone Co., Ltd.) in 129 g of cyclohexanone, adomapine SO-25R (Adomatech Co., Ltd.) as spherical silica particles The company's brand name) 300g was added while stirring, and after adding the whole amount, it stirred at room temperature for 1 hour more. 27.6 g of cyclohexanone solution (solid content 50% by mass) of NC-3000H (trade name manufactured by Nippon Kayaku Co., Ltd.) as an epoxy resin, propylene glycol mono of LA-3018 (trade name manufactured by Dai Nippon Ink Co., Ltd.) as a phenol resin 18.7 g of methyl ether solution (solid content 60% by mass), 0.42 g of 2-ethyl-4-methylimidazole (2E4MZ, product name manufactured by Shikoku Chemicals Co., Ltd.) was added, and after stirring for another 30 minutes, as an acrylic resin 301 g of a cyclohexanone solution (solid content 24.9% by mass) of glycidyl methacrylate, acrylonitrile, ethyl acrylate, and butyl acrylate copolymer (weight average molecular weight 610,000, epoxy equivalent 2869) was added, and 12 hours with a ball mill It stirred and mixed, and the liquid composition was obtained.

Production Examples 2 to 7

A liquid composition was obtained in the same manner as in Production Example 1, except that each material shown in Tables 1 and 2 was used at the mixing ratio shown in the table. The amount of the acrylic resin, the amount of the epoxy resin, and the amount of the phenol resin shown in Tables 1 and 2 are ratios based on the total amount of the acrylic resin, the epoxy resin and the phenol resin.

The weight average molecular weight of the acrylic resin was converted from a calibration curve using standard polystyrene by gel permeation chromatography (GPC). The calibration curve was approximated by a cubic formula using a set of 5 samples of standard polystyrene (PStQuick MP-H, PStQuick B [trade name manufactured by Tosoh Corporation]) and created. GPC conditions are shown below.

Equipment: (Pump: L-2130 type [manufactured by Hitachi High Technology Co., Ltd.]),

(Detector: L-2490 type RI [manufactured by Hitachi High Technology Co., Ltd.]),

(Column oven: L-2350 [manufactured by Hitachi High Technology Co., Ltd.])

Column: Gelpack GL-A100M (trade name manufactured by Hitachi Chemical Industry Co., Ltd.)

Column size: 10.7mm I.D x 300mm

Eluent: tetrahydrofuran

Sample concentration: 10mg/2ml

Injection volume: 200µl

Flow: 2.05ml/min

Measurement temperature: 25℃

The details of each material shown in Table 1 and Table 2 are as follows.

1. Acrylic resin

GMA/AN/EA/BA: a copolymer of glycidyl methacrylate, acrylonitrile, ethyl acrylate and butyl acrylate

2. Epoxy resin

NC-3000H: Biphenyl aralkyl type epoxy resin (brand name manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 290)

3. Phenolic resin

LA-3018: Aminotriazine novolak-type phenolic resin (trade name manufactured by Dai Nippon Ink Co., Ltd., hydroxyl equivalent weight 151, nitrogen content 18%)

4. Silica particles

F05-12: crushed silica, manufactured by Fukushima Chemical Co., Ltd.

SO-25R: Spherical silica, manufactured by Adomatech Co., Ltd.

5. Surface treatment agent (silane coupling agent)

KBM573: N-phenyl-3-aminopropyltrimethoxysilane, manufactured by Shin-Etsu Silicone Co., Ltd.

(Mechanical properties of the resin layer)

The liquid composition was applied to the mold release treatment PET (polyethylene terephthalate) film using a bar coater so that the thickness after drying became 125 µm. The applied liquid composition was dried by heating at 130° C. for 10 minutes, and then cured by heating at 185° C. for 30 minutes. After peeling off the mold release treatment PET film, the cured product was punched with a width of 10 mm and a length of 100 mm to obtain a test piece. This test piece was tensioned in the longitudinal direction at a tensile speed of 50 mm/min using an EZ tester (autograph EZ-S manufactured by Shimadzu Corporation) to obtain a stress-displacement curve. The maximum value of the slope of the tangent line of the stress-displacement curve at the beginning of the operation after starting the stress load was obtained, and the initial tensile modulus was obtained from the value according to the following equation.

Initial tensile modulus (Pa)=maximum of the slope of the tangent line of the stress-displacement curve (N/m)×[displacement (m)/cross-sectional area of the cured product (㎡)]

Example 1

A copper foil of a polyimide base material (thickness 25 µm)/copper foil (thickness 18 µm) laminate (Spanex, brand name manufactured by Shinnittetsu Chemical Co., Ltd.) was processed by photolithography, and a wiring terminal Formed a pattern of. The liquid composition of Production Example 1 was printed on the surface of the polyimide substrate opposite to the wiring terminal using a metal mask. The printed liquid composition was dried by heating at 130° C. for 10 minutes, and then cured by heating at 185° C. for 60 minutes to form a resin layer having a length of 30 mm and a thickness of 75 μm from the end of the polyimide substrate. A test piece (10 mm in width and 100 mm in length) of a connector having a strata was obtained. The end portion of the resin layer having a substantially rectangular main surface had a surface forming a convex curved surface curved toward the polyimide substrate from an opposing surface facing the polyimide substrate.

Examples 2-12

Using the liquid composition of each production example, except that the thickness of the polyimide substrate or the thickness of the resin layer was changed as shown in Tables 3 and 4, in the same manner as in Example 1, the connector having a resin layer was A test piece was produced. In any of the test pieces, the end portion of the resin layer had a surface forming a convex curved surface curved toward the polyimide substrate from the opposite surface facing the polyimide substrate.

Comparative Example 1

In the same manner as in the examples, a pattern of wiring terminals was formed on a polyimide substrate (50 µm in thickness). A polyimide film (Upyrex 75S, Ube) with a thickness of 75 μm through an adhesive film (Hibon 10-850, a product name manufactured by Hitachi Chemical Co., Ltd.) having a thickness of 30 μm on the side opposite to the wiring terminal of the polyimide substrate Kosan Co., Ltd. product name) was attached, and it cut out into a rectangular shape with a width of 10 mm and a length of 100 mm, and a connector test piece for comparison was obtained. The end of the polyimide film attached to the polyimide substrate had a facing surface facing the polyimide substrate, and a side surface along the line of the polyimide substrate, and the facing surface and the side surface met at a right angle.

(evaluation)

(Bendingability)

A load of 490 mN (50 gf) was applied from the end by pressing the end of the test piece having a width of 10 mm with a balance. When the load was applied, the case where the test piece was not bent was determined as "A", and the case where the test piece was bent or the resin layer was broken was determined as "C".

(Reflow resistance)

By sandwiching the test piece of the connector between two wire meshes and moving at a speed of 1.2 m/min, the maximum temperature of the board surface is 260°C and the temperature is maintained for 10 seconds by a conveyor-type reflow test. , The test piece was treated three times. After the treatment, the appearance was visually observed to confirm the presence or absence of swelling and peeling between the polyimide substrate/resin layer. The case where expansion and peeling did not occur was determined as "A", and the case where expansion and/or peeling occurred was determined as "C".

(Connector durability test)

8 is a schematic explanatory diagram showing a method for testing the durability of the connector. A mirror-finished aluminum plate 31 having a thickness of 1 mm fixed to each of the spindle 21 and the anvil 22, which is a measurement part of the digital micrometer 20 (Mitsutoyo MDC-25SB), 32) was used as a jig for evaluating the pull-out durability. The test was performed by setting the gap between the two opposing aluminum plates 31 and 32 to be the same as the thickness of the test piece, -15 µm, or +15 µm with the digital micrometer 20. After inserting about 10 mm of the test piece 10 into the gap in the direction parallel to the aluminum plate (A), the drawing operation was repeated up to 30 times. The abnormality of the test piece 10 was visually observed, and the number of times until an abnormality such as peeling, cracking, or bending occurred was recorded.

(Adhesion between polyimide substrate and resin layer)

A liquid composition was applied to a polyimide film (Upyrex 50S, product name of Ubego Corporation) using a bar coater so that the thickness after drying was 125 µm. The applied liquid composition was dried by heating at 130°C for 10 minutes and then cured by heating at 185°C for 30 minutes to obtain a sample for evaluation of adhesion. On the resin layer of the sample, 10 2 mm wide and 10 2 mm wide checkerboard marks were put on the resin layer of the sample by a cutter knife. After affixing a cello tape (registered trademark) there, it was removed and checked for peeling of the resin layer. The case where peeling did not occur was determined as "A", and the case where peeling occurred was determined as "C".

(result)

The evaluation results are shown in Tables 3 and 4. In Examples, all the polyimide substrates and resin layers were good, and there was no problem in reflow resistance. Regarding the bendability of the connector, even in all examples, the test piece was not bent under a load of 490 mN (50 gf).

Regarding the durability test of the connector, in the examples, smooth removal and insertion of the test piece was possible, and occurrence of abnormality was not observed even when the removal and insertion was performed 30 times. In the case of the comparative example, the pull-out resistance of the test piece was strong, and when the gap was the same as that of the test piece (173 µm) or -15 µm (158 µm), abnormal occurrence was observed at the time of pulling out and putting in less than 30 times.

9 is a photomicrograph of a cross section of a connector manufactured in Example 1. FIG. Also in microscopic observation, it was confirmed that the end of the resin layer 3 has a surface forming a convex curved surface that curves toward the polyimide substrate 2 from an opposing surface facing the polyimide substrate. 10 is a scanning micrograph (10,000 times) of the resin layer of the connector produced in Example 1. FIG. It was confirmed that spherical silica particles were contained in the resin layer.

1...wiring terminal 2...flexible base
3...resin layer 3a...end of resin layer (3)
4...metal mask 4a...opening
5...liquid composition 6...facing side
7...surface forming a convex surface 10...connector
20...digital micrometer 21...spindle
22...Anvil 31, 32...Aluminum plate
40...Flexible substrate 41...Cover film
42...non-wired metal layer 51...circuit
52...Flexible substrate for circuit 100...Flexible wiring board

Claims (9)

As an insertion-side connector inserted into the mating connector and used to connect wiring,
A flexible substrate (可撓性基材),
A wiring terminal disposed on one side of the flexible substrate,
On the end of the flexible substrate on the side opposite to the wiring terminal of the flexible substrate, a resin layer containing a resin disposed so as to be in contact with the flexible substrate is provided,
The surface of the portion of the resin layer not in contact with the flexible substrate at the distal end of the connector forms a convex curved surface that is curved toward the flexible substrate from a surface located on the opposite side of the surface in contact with the flexible substrate. And a surface along a waterline of a main surface of the flexible substrate, and
The connector, wherein the resin layer contains an inorganic filler, and the content of the inorganic filler in the resin layer is 70 to 80 mass% with respect to the mass of the resin layer. The method according to claim 1,
The inorganic filler is a silica particle connector. The method according to claim 1 or 2,
The flexible substrate is a polyester substrate or a polyimide substrate. The method according to claim 1 or 2,
The flexible substrate has a thickness of 75 μm or less. The method according to claim 1 or 2,
The connector having an initial tensile modulus of the resin layer at 25°C of 0.3 to 3.0 GPa. The method according to claim 1 or 2,
A connector having a thickness of the resin layer of 50 to 500 μm. The connector according to claim 1 or 2, and
A flexible substrate for circuitry,
It is provided on the flexible substrate for the circuit and has a circuit connected to the wiring terminal of the connector,
A flexible wiring board in which the flexible substrate of the connector and the flexible substrate for circuits are the same single substrate, or the flexible substrate of the connector and the flexible substrate for circuits are connected to each other. delete delete

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