JP2007291396A - Wiring-connecting material and process for producing circuit board with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring-connecting material for electric/electronic uses, which is excellent in low temperature quick curability than those of conventional epoxy resin-based connecting materials, and has a good pot life, and to provide a method for producing a circuit board with the same. <P>SOLUTION: A wiring-connecting material (15) comprises 2 to 75 parts by weight of a polyurethane resin, 30 to 60 parts by weight of a radical-polymerizable substance, and 0.1 to 30 parts by weight of a hardener which upon heating generates free radicals. The material (15) preferably further contains a film-forming material and/or conductive particles (14). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wiring connecting material and a method for manufacturing a wiring board using an adhesive composition and conductive particles.

  Epoxy resin adhesives are widely used in various applications such as electrical, electronic, architectural, automobile, and aircraft because they have high adhesive strength and are excellent in water resistance and heat resistance. Among them, the one-pack type epoxy resin adhesives are easy to use because they do not require mixing of the main agent and the curing agent, and are widely used in the form of films, pastes, and powders. In the one-pack type epoxy resin adhesive, since the epoxy resin, the curing agent and the modifier can be combined in various ways, for example, as described in Patent Document 1, by appropriately selecting the combination, Desired performance can be obtained.

  However, the film-like adhesive disclosed in Patent Document 1 is not suitable at room temperature for the purpose of obtaining good stability by coexistence of short-time curability (fast curability) and storage stability (storability). Since an active catalyst-type curing agent is used, a sufficient reaction cannot be obtained at the time of curing, and although it is excellent in workability, it is heated at about 140 to 180 ° C. with a connection time of about 20 seconds, and 180 at 10 seconds. Heating of about ~ 210 ° C was necessary.

However, in recent years, in the field of precision electronic equipment, the density of circuits has been increased, and the connection terminal width and the connection terminal interval have become extremely narrow. For this reason, when the connection is performed under the connection conditions using this conventional epoxy resin-based wiring connection material, the wiring may drop off, peel off, or be displaced. In addition, in order to improve production efficiency, it has been required to shorten the connection time that can be connected in 10 seconds or less. In order to satisfy these requirements, a low-temperature fast-curing wiring connection material that cures at a low temperature in a short time is required.
JP-A-62-141083

  The present invention provides an electrical / electronic wiring connection material that is superior in low-temperature fast-curing properties and has a pot life as compared with conventional epoxy resin-based connection materials, and a method of manufacturing a wiring board using the same. For the purpose.

  In the present invention, there is provided a wiring connecting material comprising 2 to 75 parts by weight of a polyurethane resin, 30 to 60 parts by weight of a radical polymerizable substance, and 0.1 to 30 parts by weight of a curing agent that generates free radicals upon heating. . The wiring connecting material of the present invention is particularly suitable as a connecting material for interposing between connecting terminals facing each other and pressurizing the connecting terminals facing each other to electrically connect the connecting terminals in the pressurizing direction. .

  The wiring connection material of the present invention preferably further contains a film forming material and / or conductive particles. The film forming material preferably has a blending amount of 0 to 40 parts by weight, and is preferably a polyimide resin.

  Further, as the polyurethane resin, it is preferable to use a resin having a pour point measured by a flow tester method of 40 ° C. to 140 ° C., and as a curing agent, a weight retention rate at 25 ° C. for 24 hours (that is, room temperature (25 It is desirable to use a curing agent in which the ratio of the mass difference before and after being left open for 24 hours at normal pressure is 20% by weight or more. As the radically polymerizable substance, urethane acrylate is preferable.

  Moreover, in this invention, the manufacturing method of a wiring board including the process of connecting between the terminals of wiring using the wiring connection material of this invention is provided. That is, in the present invention, there is provided a wiring board manufacturing method including a connecting step of connecting between wiring members each having a connecting terminal so that the connecting terminals can be electrically connected, and the connecting step includes a surface having the connecting terminal. There is provided a method of manufacturing a wiring board including a step of heating a wiring connecting material of the present invention sandwiched between two or more wiring members arranged so as to face each other while pressing the wiring connecting material through the wiring member. . This manufacturing method of the present invention is particularly suitable when at least one surface of the connection terminal is made of at least one selected from gold, silver and platinum group metals.

  According to the present invention, it is possible to provide an electrical / electronic wiring connecting material that has excellent low-temperature rapid curing properties and has a long working life as compared with conventional epoxy resin systems, and has little circuit corrosivity.

A. Curing Agent The curing agent used in the present invention decomposes by heating a peroxide compound, an azo compound or the like to generate free radicals. The curing agent can be appropriately selected depending on the intended connection temperature, connection time, pot life, etc. In order to achieve high reactivity and a long pot life, the temperature of a half-life of 10 hours is 40 ° C. or more. Organic peroxides having a half-life temperature of 180 ° C. or lower are preferred, and organic peroxides having a half-life temperature of 10 hours or higher and a half-life time of 1 minute of 170 ° C. or lower are more preferred.

  When the connection time is 10 seconds or less, in order to obtain a sufficient reaction rate, the amount of the curing agent is preferably 0.1 to 30 parts by weight, and more preferably 1 to 20 parts by weight. When the blending amount of the curing agent is less than 0.1 parts by weight, a sufficient reaction rate cannot be obtained, and good adhesive strength and small connection resistance tend to be difficult to obtain. When the blending amount exceeds 30 parts by weight, the fluidity of the wiring connection material is lowered, the connection resistance is increased, or the pot life of the wiring connection material tends to be shortened.

  Examples of the organic peroxide suitable as the curing agent of the present invention include diacyl peroxide, peroxydicarbonate, peroxyester, peroxyketal, dialkyl peroxide, hydroperoxide, silyl peroxide, and the like.

  Examples of diacyl peroxides include isobutyl peroxide, 2,4-dichlorobenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, succinic peroxide, Examples include benzoyl peroxytoluene and benzoyl peroxide.

Peroxydicarbonates include di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, bis (4-tert-butylcyclohexyl) peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, di- (2-Ethylhexylperoxy) dicarbonate, dimethoxybutylperoxydicarbonate, di (3-methyl-3-methoxybutylperoxy) dicarbonate and the like.
Peroxyesters include cumylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneodecanoate, t- Hexyl peroxyneodecanoate, t-butyl peroxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanate, 2,5-dimethyl-2,5-di (2 -Ethylhexanoylperoxy) hexane, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexa Nonate, t-butylperoxyisobutyrate, 1,1-bis (t-butylperoxy) cyclohexane t-hexylperoxyisopropyl monocarbonate, t-butylperoxy-3,5,5-trimethylhexanate, t-butylperoxylaurate, 2,5-dimethyl-2,5-di (m-toluoyl) Peroxy) hexane, t-butyl peroxyisopropyl monocarbonate, t-butyl peroxy-2-ethylhexyl monocarbonate, t-hexyl peroxybenzoate, t-butyl peroxyacetate and the like.

  In peroxyketals, 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane, 1,1-bis (t- Butyl peroxy) -3,3,5-trimethylcyclohexane, 1,1- (t-butylperoxy) cyclododecane, 2,2-bis (t-butylperoxy) decane and the like.

  Dialkyl peroxides include α, α′-bis (t-butylperoxy) diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, and t-butyl. Cumyl peroxide and the like.

  Examples of hydroperoxides include diisopropylbenzene hydroperoxide and cumene hydroperoxide.

  Examples of silyl peroxides include t-butyltrimethylsilyl peroxide, bis (t-butyl) dimethylsilyl peroxide, t-butyltrivinylsilyl peroxide, bis (t-butyl) divinylsilyl peroxide, and tris (t-butyl). ) Vinylsilyl peroxide, t-butyltriallylsilyl peroxide, bis (t-butyl) diallylsilyl peroxide, tris (t-butyl) allylsilyl peroxide, and the like.

  In the present invention, one of these compounds may be used as the curing agent, or two or more compounds may be used in combination. Moreover, you may use these hardening | curing agents (free radical generator) together with a decomposition accelerator, an inhibitor, etc.

  In addition, in order to suppress the corrosion of the connection terminal of a wiring member, it is preferable that the chlorine ion and organic acid which are contained in a hardening | curing agent are 5000 ppm or less, Furthermore, a thing with little organic acid generated after thermal decomposition is preferable. Moreover, since the stability of the produced wiring connection material improves, it is preferable that the weight retention after leaving open for 24 hours at room temperature (25 ° C.) and normal pressure is 20% by weight or more.

  In addition, those encapsulating these curing agents with polyurethane-based or polyester-based polymeric substances and the like and microencapsulated are preferable because the pot life is extended.

B. Polyurethane resin As a polyurethane resin, a resin obtained by the reaction of a diol having two hydroxyl groups in the molecule and a diisocyanate having two isocyanate groups is excellent in stress relaxation at the time of curing and has adhesiveness. This is suitable for the present invention.

  As the diol, any linear compound having a hydroxyl group at the terminal can be used. Specifically, polyethylene adipate, polydiethylene adipate, polypropylene adipate, polybutylene adipate, polyhexamethylene adipate, polyneo Examples include pentyl adipate, polycaprolactone polyol, polyhexamethylene carbonate, silicone polyol, acrylic polyol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Any one of these compounds may be used alone, or two or more thereof may be used in combination.

  Examples of the diisocyanate include isophorone diisocyanate, tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, naphthalene-1,5-diisocyanate, p-phenylene diisocyanate, 4,4′-methylenebiscyclohexyl diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate and the like. Can be mentioned. Any one of these compounds may be used alone, or two or more thereof may be used in combination.

  The weight average molecular weight of the polyurethane resin used in the present invention is preferably 10,000 to 1,000,000. If the weight average molecular weight is less than 10,000, the cohesive force of the wiring connecting material tends to be reduced, and sufficient adhesive strength tends to be difficult to obtain, and if it exceeds 1000000, the mixing property and fluidity tend to deteriorate.

  In addition, when synthesizing a polyurethane resin, in addition to these diols and diisocyanates, polyhydric alcohols, amines, acid anhydrides and the like may be added and reacted as appropriate, for example, obtained by reacting with an acid anhydride. An imide group-containing polyurethane is preferable because adhesion and heat resistance are improved.

  The polyurethane resin used in the present invention may be modified. In particular, those modified with radically polymerizable functional groups are preferred because the heat resistance is improved.

  The polyurethane resin used in the present invention preferably has a pour point in a flow tester method in the range of 40 ° C to 140 ° C, more preferably 50 ° C to 100 ° C. The pour point in the flow tester method is the temperature at which the cylinder begins to move when a die of 1 mm in diameter is used and a pressure of 3 MPa is applied and the temperature is raised at a rate of temperature rise of 2 ° C./min. Measure using a tester. If the pour point in the flow tester method is less than 40 ° C., the film formability and adhesiveness may be inferior, and if it exceeds 140 ° C., the fluidity may deteriorate and the electrical connection may be adversely affected.

C. Film forming material Examples of the film forming material used in the present invention include polyimide resin, polyvinyl formal resin, polystyrene resin, polyvinyl butyral resin, polyester resin, acrylic resin, polyamide resin, xylene resin, and phenoxy resin. Any of these may be used alone or in combination of two or more.

  The film-forming material means that when the liquid is solidified and the constituent composition is made into a film shape having self-supporting properties, the film is easy to handle and does not easily tear, crack, or stick. Such mechanical properties that can be handled as a film in a normal state.

  As the film forming material, a polyimide resin is particularly suitable for the present invention from the viewpoint of heat resistance. As the polyimide resin, for example, a polyamic acid synthesized by an addition reaction of tetracarboxylic dianhydride and diamine and subjected to imidation by heat condensation can be used. The weight average molecular weight of the polyimide resin is preferably about 10,000 to 150,000 from the viewpoint of film formability.

  The acid dianhydride and diamine used when synthesizing the polyimide resin can be appropriately selected from the viewpoints of solubility in a solvent and compatibility with a radical polymerizable material. Moreover, each may use a single compound and may use 2 or more types of compounds together. In addition, since adhesiveness and a softness | flexibility improve, it is preferable that at least 1 type of compound of an acid dianhydride and diamine has a siloxane skeleton.

  The film forming material used in the present invention may be modified with a radical polymerizable functional group.

D. Radical polymerizable substance The radical polymerizable substance used in the present invention is a substance having a functional group that is polymerized by radicals, and examples thereof include acrylates, methacrylates, maleimide compounds, and the like. Any of these may be used alone or in combination of two or more.

  In addition, the radically polymerizable substance can be used in any state of a monomer and an oligomer, and the monomer and the oligomer can be used in combination.

  Specific examples of acrylates suitable for the present invention include methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, trimethylol propane triacrylate, tetramethylol methane tetraacrylate, 2-hydroxy-1 , 3-Diacryloxypropane, 2,2-bis [4- (acryloxymethoxy) phenyl] propane, 2,2-bis [4- (acryloxypolyethoxy) phenyl] propane, dicyclopentenyl acrylate, tricyclo Examples include decanyl acrylate, tris (acryloyloxyethyl) isocyanurate, isocyanuric acid ethylene oxide-modified diacrylate, and urethane acrylate. Also, methacrylates corresponding to these acrylates are suitable for the present invention.

  A radical polymerizable substance having at least one of a dicyclopentanyl group, a tricyclodecanyl group and a triazine ring is preferable because the heat resistance of the obtained wiring connection material is improved.

  As the radically polymerizable substance used in the present invention, urethane acrylate is particularly preferable because of excellent adhesiveness. The urethane acrylate has at least one urethane group in the molecule, and examples thereof include a reaction product of a polyol such as polytetramethylene glycol, polyisocyanate and a hydroxyl group-containing acrylic compound.

  Moreover, since the adhesive strength on the surface of an inorganic substance such as a metal is improved, it is preferable to use a radical polymerizable substance having a phosphate structure in addition to these radical polymerizable substances.

  As a radically polymerizable substance having a phosphate ester structure suitable for the present invention, there can be mentioned a reaction product of phosphoric anhydride and 2-hydroxyethyl methacrylate which is 2-hydroxyethyl acrylate or a corresponding methacrylate. Specifically, mono (2-methacryloyloxyethyl) acid phosphate, di (2-methacryloyloxyethyl) acid phosphate, or the like can be used. These may use one type of compound or two or more types in combination.

  As the maleimide compound, those containing at least two maleimide groups in the molecule are suitable for the present invention. Examples of such maleimide compounds include 1-methyl-2,4-bismaleimide benzene, N, N′-m-phenylene bismaleimide, N, N′-p-phenylene bismaleimide, N, N′-m. -Toluylene bismaleimide, N, N'-4,4-biphenylene bismaleimide, N, N'-4,4- (3,3'-dimethylbiphenylene) bismaleimide, N, N'-4,4- ( 3,3′-dimethyldiphenylmethane) bismaleimide, N, N′-4,4- (3,3′-diethyldiphenylmethane) bismaleimide, N, N′-4,4-diphenylmethane bismaleimide, N, N′- 4,4-diphenylpropane bismaleimide, N, N′-4,4-diphenyl ether bismaleimide, N, N′-3,3′-diphenylsulfone bismale 2,2-bis (4- (4-maleimidophenoxy) phenyl) propane, 2,2-bis (3-s-butyl-3,4- (4-maleimidophenoxy) phenyl) propane, 1,1- Bis (4- (4-maleimidophenoxy) phenyl) decane, 4,4′-cyclohexylidene-bis (1- (4-maleimidophenoxy) -2-cyclohexylbenzene, 2,2-bis (4- (4- And maleimidophenoxy) phenyl) hexafluoropropane.

  In the present invention, in addition to these radically polymerizable substances, a polymerization inhibitor such as hydroquinones and methyl ether hydroquinones may be used as necessary.

E. Blending ratio The blending amount of each of the above components in the wiring connection material of the present invention is 2 to 75 parts by weight of the polyurethane resin, 30 to 60 parts by weight of the radical polymerizable substance, and 0 hardener that generates free radicals upon heating. 0.1 to 30 parts by weight, and when the film forming material is included, the content is 0 to 40 parts by weight. The compounding quantity of these components can be suitably determined within the above-mentioned range.

  When the blending amount of the polyurethane resin is less than 2 parts by weight, the effect of relaxing the stress at the time of curing the wiring connection material or at the time of heat load is poor and the adhesive strength is lowered. Moreover, when it exceeds 75 weight part, there exists a possibility that connection reliability may fall.

  If the blending amount of the radical polymerizable substance is less than 30 parts by weight, the mechanical strength of the wiring connection material after curing tends to decrease, and if it exceeds 60 parts by weight, the tackiness of the wiring connection material before curing increases, The handling becomes inferior.

  Also, if the blending amount of the curing agent that generates free radicals by heating is less than 0.1 parts by weight, it is difficult to obtain a sufficient reaction rate as described above, and it is difficult to obtain good adhesive strength and small connection resistance. Tend to be. Furthermore, when the blending amount of the curing agent exceeds 30 parts by weight, the fluidity of the wiring connection material is lowered, the connection resistance is increased, or the pot life of the wiring connection material tends to be shortened.

  When the blending amount of the film forming material exceeds 40 parts by weight, the fluidity of the wiring connecting material tends to decrease or the connection resistance tends to increase. The film forming material may not be blended as long as a sufficient film can be formed by other components such as a polyurethane resin, a radical polymerizable substance, and a curing agent that generates free radicals upon heating.

F. Conductive Particles The wiring connection material of the present invention does not need to contain conductive particles since it can be connected by direct contact between the connection terminals even if it does not contain conductive particles. However, it is desirable to include conductive particles because a more stable connection can be obtained.

  As the conductive particles, metal particles such as Au, Ag, Ni, Cu, and solder, carbon particles, and the like can be used. In order to obtain a sufficient pot life, the surface layer of the particles is preferably not a transition metal such as Ni or Cu but Au, Ag, or a platinum group noble metal, and Au is particularly preferable.

  The surface of transition metals such as Ni is coated with noble metals such as Au, and the surface of particles such as non-conductive glass, ceramics, and plastics is covered with the above-mentioned conductive layer. Further, particles having a part of particles having conductivity, such as composite particles whose surfaces are covered with an outermost layer made of a noble metal, can also be used in the present invention as conductive particles.

  The thickness of the noble metal coating layer in such composite particles is not particularly limited, but is preferably 100 mm or more in order to obtain good resistance. However, when a noble metal layer is provided on the surface of a transition metal such as Ni, a redox action occurs due to a loss of the noble metal layer that occurs when the conductive particles are mixed and dispersed, generating free radicals, and reducing pot life. May cause. For this reason, the thickness of the noble metal layer is preferably 300 mm or more. Further, if the thickness of the noble metal layer is greater than 1 μm, the effect may be saturated, so that a film thickness of 1 μm or less is effective from the viewpoint of cost and the like.

  In addition, since composite particles having plastic as a core and hot-melt metal particles are highly deformable by heating and pressurization, they are easily deformed by heating and pressurization performed at the time of connection, and the contact area with the connection terminal is large. It is preferable because it increases and reliability is improved.

  When mix | blending electroconductive particle with the wiring connection material of this invention, it is desirable that the compounding quantity shall be 0.1-30 volume% with respect to an adhesive agent component, and can be suitably determined according to a use. In order to prevent a short circuit between adjacent circuits due to excessive conductive particles, the content is preferably 0.1 to 10% by volume.

G. Additives In addition to the components A to F described above, the wiring connection material of the present invention further includes a filler, a softener, an accelerator, an anti-aging agent, a colorant, a flame retardant, a thixotropic agent, and a coupling. An agent or the like may be included.

  If a filler is blended, the connection reliability of the obtained wiring connection material can be improved, which is preferable. The maximum diameter of the filler is preferably less than the particle diameter of the conductive particles, and the blending amount is preferably 5 to 60% by volume. If it exceeds 60% by volume, the effect of improving the reliability is saturated.

  As a coupling agent, a vinyl group, an acryl group, an amino group, an epoxy group, and an isocyanate group-containing material are preferable from the viewpoint of improving adhesiveness.

H. Film structure The wiring connection material of this structure does not need to have all the components in a single layer, and it is good also as a laminated film of two or more layers. For example, in addition to the effect that high definition can be achieved by separating these components into a two-layer structure of a layer containing a curing agent that generates free radicals and a layer containing conductive particles, The effect of improving pot life is obtained.

I. Characteristics of the wiring connection material The wiring connection material of the present invention is one in which the adhesive melts and flows at the time of connection and contacts the connection terminals facing each other, and then hardens to retain the connection. Is an important factor. The wiring connection material of the present invention is a glass having a thickness of 0.7 mm and 15 mm × 15 mm. A wiring connection material having a thickness of 35 μm and 5 mm × 5 mm is sandwiched between the glasses, and heated and pressed at 160 ° C., 2 MPa for 10 seconds. In this case, the value of fluidity (B) / (A) represented by using the initial area (A) and the area after heating and pressing (B) is preferably 1.3 to 3.0. More preferably, it is 5-2.5. If it is 1.3 or more, there is sufficient fluidity and a good connection can be obtained. Moreover, if it is 3.0 or less, a bubble will be hard to generate | occur | produce and it is excellent in reliability.

  Furthermore, when the wiring connection material of the present invention is measured using a differential scanning calorimeter (DSC) at a heating rate of 10 ° C./min, the rising temperature (Ta) of the exothermic reaction is in the range of 70 to 110 ° C. The peak temperature (Tp) is preferably Ta + 5 to 30 ° C. and the end temperature (Te) is preferably 160 ° C. or lower. By providing such characteristics, both low temperature connectivity and storage stability at room temperature can be achieved.

  In addition, the wiring connection material of the present invention is advantageous in reducing the internal stress of the resin after connection, improving the adhesive force, and obtaining good conduction characteristics, so that it is stored at 25 ° C. after curing. The elastic modulus is preferably 100 to 2000 MPa, and more preferably 300 to 1500 MPa.

J. et al. Manufacturing Method of Wiring Board The wiring connecting material of the present invention is also useful as a film-like adhesive for bonding an IC chip and a chip mounting substrate or bonding electric circuits to each other.

  That is, by using the wiring connection material of the present invention, the first wiring member having the first connection terminal and the second wiring member having the second connection terminal are connected to the first connection terminal and the second connection member. The connection terminals are arranged opposite to each other, the wiring connection material (film adhesive) of the present invention is interposed between the first wiring member and the second wiring member, and heated and pressurized, The wiring board can be manufactured by electrically connecting the one connection terminal and the second connection terminal.

  As wiring members, chip parts such as semiconductor chips, resistor chips, capacitor chips, printed boards on which chips are mounted and / or subjected to resist processing, TAB (Tape Automated Bonding) tapes are used. Mounted, resist-treated TCP (tape carrier package), liquid crystal panel, etc., silicon, gallium / arsenic, glass, ceramics, glass / thermosetting resin composites (glass / epoxy composites, etc.), A conductive metal foil formed on an insulating substrate made of plastic such as polyimide (plastic film, plastic sheet, etc.) via an adhesive to form wiring including connection terminals. Conductive wiring is applied, and a material such as a plating catalyst is applied to make the conductive Well as those forming the line it can be exemplified. Suitable wiring members for connection using the manufacturing method of the present invention include TAB tape, FPC (flexible printed circuit board), PWB (printed wiring board), ITO (indium tin oxide), and a semiconductor having connection pads. A typical example is a chip.

  The material of the wiring member is not particularly limited. Silicon, gallium, arsenic, etc. of semiconductor chips, glass, ceramics, polyimide, glass / thermosetting resin composite material (glass / epoxy composite, etc.), plastic Any of these may be used.

  When the surface of the conductive connection terminal in contact with the wiring connection material is made of a transition metal such as copper or nickel, free radicals are generated by the oxidation-reduction action. For this reason, if the wiring connection material is temporarily bonded to the first connection terminal and left for a certain period of time, radical polymerization proceeds, making the connection material difficult to flow, and the main connection with the aligned second connection terminal. Sometimes there is a risk of not being able to make a sufficient electrical connection. Therefore, it is preferable that the surface of at least one of the connection terminals is composed of at least one selected from gold, silver, a platinum group metal, or tin. A plurality of metals such as copper / nickel / gold may be combined to form a multilayer structure.

  Furthermore, in the wiring board manufacturing method of the present invention, it is preferable that at least one of the connection terminals is directly disposed on the surface of the plastic substrate. Here, examples of the plastic substrate include polyethylene terephthalate resin, polyethylene naphthalate resin, polyether sulfone resin, polycarbonate resin, and a polyimide resin film or sheet, which are preferably made of polyimide resin.

  By using this plastic substrate, the thickness of the wiring board can be further reduced and the weight can be reduced. In the manufacturing method of the present invention, since the connection at a low temperature is possible by using the wiring connection material of the present invention, a plastic having a relatively low glass transition temperature or melting point can be used, which is economically excellent. A wiring board can be obtained.

  In order to reduce the thickness and weight of the wiring member, it is a wiring member configured such that a connecting terminal that does not use an adhesive is directly present on the plastic rather than bonding the connecting terminal made of a plastic and a conductive material with an adhesive. Is preferred. A polyimide resin with a metal foil obtained by the direct coating method that directly forms a resin solution with a certain thickness on a metal foil such as a copper foil without using an adhesive is commercially available, and is formed by patterning this metal foil. The wiring member thus obtained is suitable for the present invention. Further, a film obtained by thermocompression bonding of a film and a metal foil directly extruded into a film shape from an extruder or the like, and a pattern obtained by patterning this metal foil can also be used in the present invention.

  Hereinafter, the present invention will be specifically described based on examples.

<Example 1>
(1) Synthesis of polyurethane resin 450 parts by weight of polybutylene adipate diol having an average molecular weight of 2000, 450 parts by weight of polyoxytetramethylene glycol having an average molecular weight of 2000, and 100 parts by weight of 1,4-butylene glycol are mixed, and 4000 parts by weight of methyl ethyl ketone is mixed. In addition, after uniformly mixing, 390 parts by weight of diphenylmethane diisocyanate was added and reacted at 70 ° C. to obtain a polyurethane resin A solution having a solid content of 20% by weight and 15 Pa · s (25 ° C.). The weight average molecular weight of this polyurethane resin was 350,000, and the pour point by the flow tester method was 80 ° C.

(2) Preparation of wiring connection material 40 g of polyurethane resin A (as a solid content) synthesized above in a solid weight ratio, 39 g of dimethylol tricyclodecane diacrylate, phosphate ester acrylate (trade name, manufactured by Kyoeisha Chemical Co., Ltd .; P2M) ) 1 g, 20 g of phenoxy resin, 5 g of lauroyl peroxide (25 g as a methyl ethyl ketone solution), 3% by volume of conductive particles are further dispersed, and a PET (polyethylene terephthalate) film having a surface treated on one side having a thickness of 80 μm is applied. Coating was performed using a coating apparatus, and hot-air drying at 70 ° C. for 10 minutes was performed to obtain a wiring connection material having an adhesive layer thickness of 35 μm.

  In addition, dimethylol tricyclodecane diacrylate was used as the radical polymerizable substance. As the film forming material, a phenoxy resin (trade name “PKHC” manufactured by Union Carbide Co., Ltd .: weight average molecular weight 45000) was used. Further, as a curing agent that generates free radicals upon heating, a 20 wt% methyl ethyl ketone solution of lauroyl peroxide (weight retention 97% when left open for 24 hours at room temperature (25 ° C.) and normal pressure) was used. As the conductive particles, a nickel layer having a thickness of 0.2 μm is provided on the surface of particles having polystyrene as a core, and a conductive layer having an average particle diameter of 10 μm is provided by providing a gold layer having a thickness of 0.04 μm on the outside of the nickel layer. Particles were made and used.

(3) Connection of wiring As shown in FIG.1 (c), using the polyimide film with a copper foil of the 3 layer structure which adhered the polyimide film 18 with the copper foil of thickness 18 micrometers through the adhesive agent 17, this copper foil was used. After patterning to a line width of 100 μm and a pitch of 200 μm and applying a resist treatment, Sn plating is applied to the surface of the wiring formed from the copper foil and the connection terminal 16 to mount a chip (not shown), and resin at 200 ° C. A TCP (tape carrier package) 19 was produced by sealing with (not shown).

  Further, as shown in FIG. 1 (a), using a laminated substrate 11 provided with a copper foil having a thickness of 35 μm, the copper foil is patterned to a line width of 100 μm and a pitch of 200 μm to form a circuit 12, and a resist treatment is performed. The copper foil surface was plated with gold to produce a printed circuit board (PWB) 10.

  Next, an adhesive surface of the wiring connection material 15 including the resin composition 13 and the conductive particles 14 is attached in advance to the surface of the PWB 10 that is the first wiring member, and then heated at 70 ° C. and 0.5 MPa for 5 seconds. After pressurizing and temporarily connecting, the PET film is peeled off (FIG. 1 (b)), and the TCP 19 as the second wiring member is aligned and placed thereon (FIG. 1 (c)) and heated. Then, it was connected by applying pressure 20 to obtain a wiring board 21 (FIG. 1D).

<Example 2>
(1) Synthesis of urethane acrylate 400 parts by weight of polycaprolactone diol having an average molecular weight of 800, 131 parts by weight of 2-hydroxypropyl acrylate, 0.5 part by weight of dibutyltin dilaurate as a catalyst, 1.0 part by weight of hydroquinone monomethyl ether as a polymerization inhibitor The part was heated to 50 ° C. with mixing and mixed. Next, 222 parts by weight of isophorone diisocyanate was added dropwise, and the mixture was further heated to 80 ° C. with stirring to conduct a urethanization reaction. After confirming that the NCO reaction rate was 99% or more, the reaction temperature was lowered to obtain urethane acrylate B.

(2) Synthesis of polyimide resin 2,2-bis (4- (3,4-dicarboxyphenoxy) phenyl) propane dianhydride (26.1 g), which is an acid dianhydride, was dissolved in 120 g of cyclohexanone, An anhydrous solution was obtained.

  Also, diamines such as 2,2-bis (4- (4-aminophenoxy) phenyl) propane (14.4 g), 1,3-bis (3-aminopropyl) -1,1,3,3-tetramethyl Disiloxane (3.8 g) was dissolved in 120 g of cyclohexanone to obtain a diamine solution.

  The diamine solution was added dropwise to the acid dianhydride solution flask while adjusting the temperature of the reaction system so as not to exceed 50 ° C., and stirred for another 10 hours after the completion of the addition. Next, a water retention tube was attached, 50 g of toluene was added, the temperature was raised to 120 ° C. and held for 8 hours, and imidization was performed.

  After cooling the obtained solution to room temperature, the precipitate obtained by reprecipitation in methanol was dried to obtain a polyimide resin having a weight average molecular weight of 32,000. This was dissolved in tetrahydrofuran to obtain a 20 wt% polyimide solution C.

(3) Preparation of wiring connection material and manufacture of wiring board 40 g of the polyurethane resin synthesized in Example 1 (as solid content) as the polyurethane resin, 39 g of urethane acrylate B synthesized in (1) and phosphoric acid as the radical polymerizable substance A wiring connection material was prepared in the same manner as in Example 1 except that 1 g of ester type acrylate was used and 20 g of polyimide resin C (as a solid content) synthesized in (2) was used as a film forming material to produce a wiring board. did.

<Example 3>
As shown in FIG. 2, a two-layered polyimide film with a copper foil comprising a polyimide film 22 and a copper foil having a thickness of 18 μm is used, and this copper foil is patterned to a line width of 100 μm and a pitch of 200 μm to form circuits and connection terminals 23. After forming and resist processing, Au plating was applied to the surface of the connection terminal 23 to produce a flexible wiring board (FPC) 24. A wiring board was obtained in the same manner as in Example 2 except that this FPC 24 was used instead of TCP 19.

<Example 4>
A wiring with a thickness of 15 μm is used in the same manner as in Example 3 except that a liquid crystal panel 27 having a connection terminal and wiring 26 provided with ITO on the surface of the glass substrate 25 is used instead of the printed circuit board (PWB) 10. A wiring board was obtained using a connecting material.

<Comparative Example 1>
Phenoxy resin (trade name “PKHC” manufactured by PKHC Union Carbide Co., Ltd .: weight average molecular weight 45,000), bisphenol A type epoxy resin (trade name “YL980” manufactured by Yuka Shell Epoxy Co., Ltd.), and imidazole microcapsule type curing agent (Asahi Kasei Kogyo) Co., Ltd. trade name “3941HP”), the solid weight ratio of phenoxy resin / bisphenol A type epoxy resin / imidazole microcapsule type curing agent was 40/20/40, and the same as in Example 1 was conducted. A wiring board was produced in the same manner as in Example 1 except that the wiring connecting material prepared by blending the particles was used.

<Comparative example 2>
A wiring connection material was obtained in the same manner as in Example 1 except that a phenoxy resin (PKHC) was used instead of the polyurethane resin A, and a wiring board was manufactured.

  Using the wiring connection materials and wiring boards obtained in Examples 1 to 4 and Comparative Examples 1 and 2 above, adhesive strength, connection resistance, storage stability, insulating properties, fluidity of polyurethane resin, flow of wiring connection materials Property, elastic modulus after curing, and DSC were measured and evaluated. The results are shown in Table 1. The measurement and evaluation methods are as follows.

(1) Measurement of adhesive strength The connection body (wiring board) of the obtained wiring member was peeled in the direction of 90 degrees at a peeling speed of 50 mm / min, and the adhesive strength was measured. The adhesive force was measured at the initial stage of production of the wiring board and after being held in a high-temperature and high-humidity tank at 85 ° C. and 85% RH for 500 hours.

(2) Measurement of connection resistance Using the obtained wiring connection material, a flexible circuit board (FPC) in which 100 Sn-plated copper circuits having a line width of 100 μm, a pitch of 200 μm, and a thickness of 18 μm are arranged, and an ITO film is formed on the entire surface. The glass plate thus obtained was heated and pressed at 160 ° C. and 3 MPa for 10 seconds to be connected over a width of 2 mm.

  The resistance value between the adjacent circuits of this connection body was measured with a multimeter after being initially held in a high-temperature and high-humidity bath at 85 ° C. and 85% RH for 500 hours. The resistance value was shown as an average of 50 resistances between adjacent circuits.

(3) Evaluation of storability The obtained wiring connection material was held in a thermostat at 30 ° C for 30 days, and the circuit was connected in the same manner as in the above (2) to evaluate the storability.

(4) Evaluation of insulation Using the obtained wiring connection material, a printed circuit board having a comb circuit in which 250 copper circuits having a line width of 100 μm, a pitch of 200 μm, and a thickness of 35 μm are alternately arranged, a line width of 100 μm, a pitch of 200 μm, and a thickness A flexible circuit board (FPC) having 500 18 μm copper circuits was heated and pressurized at 160 ° C. and 3 MPa for 10 seconds and connected over a width of 2 mm. A voltage of 100 V was applied to the comb circuit of this connection body, and an insulation resistance value after 500 hours of a high temperature and high humidity test at 85 ° C. and 85% RH was measured.

(5) Pour point measurement of polyurethane resin Temperature at which the cylinder starts to move at a rate of 2 ° C./min at a pressure of 3 MPa using a die with a diameter of 1 mm with a flow tester (trade name “CFT-100 type” manufactured by Shimadzu Corporation). Was measured as the pour point.

(6) Flowability evaluation of wiring connecting material A wiring connecting material having a thickness of 35 μm and 5 mm × 5 mm is sandwiched between glasses having a thickness of 0.7 mm and 15 mm × 15 mm, and heated and pressed at 160 ° C., 2 MPa for 10 seconds. went. Using the initial area (A) and the area (B) after heating and pressing, the value of fluidity (B) / (A) was obtained and defined as fluidity.

(7) Elastic modulus after curing The wiring connection material was immersed in 160 ° C. oil for 1 minute to be cured. The storage elastic modulus of the cured film was measured using a dynamic viscoelasticity measuring device (temperature rising rate 5 ° C./min, 10 Hz), and the elastic modulus at 25 ° C. was measured.

(8) Measurement of DSC Using the obtained wiring connection material, rise of exothermic reaction in measurement at 10 ° C./min using a differential scanning calorimeter (DSC, trade name “910 type” manufactured by TA Instruments) Temperature (Ta), peak temperature (Tp), and end temperature (Te) were determined.

  In any of the examples, the initial value of the adhesive strength is about 7.85 to 9.81 N / cm (800 to 1000 gf / cm), and 5.88 to 8.83 N / cm (600 to 900 gf) even after the moisture resistance test. / Cm), and the adhesive strength was excellent without any significant decrease in adhesive strength. In Comparative Example 1, the curing reaction was insufficient. In Comparative Example 2, since no polyurethane resin was used, the adhesive strength was about 1.96 N / cm (200 gf / cm) and the adhesive strength was low.

  The wiring connection material obtained in Example 1 had a low initial connection resistance and a slight increase in resistance after the high-temperature and high-humidity test, indicating good connection reliability. In addition, the wiring connection materials of Examples 2, 3, and 4 and Comparative Example 2 also had good connection reliability. On the other hand, in Comparative Example 1, since the curing reaction was insufficient, the adhesion state was poor, and the initial connection resistance was high.

  In Examples 1-4, the connection result equivalent to the state (initial stage) which does not process for 30 days with a 30 degreeC thermostat was obtained. Moreover, in Examples 1-4, the favorable insulation of 1.0x109 (ohm) or more was obtained, and the fall of insulation was not observed.

  Regarding fluidity, both Example 1 and Example 2 were 1.9. Moreover, it was 800 MPa when the elasticity modulus in 25 degreeC after hardening of the wiring connection material of Example 1 was measured.

  Furthermore, the rising temperature in the curing reaction of the wiring connection material of Example 1 was 89 ° C., the peak temperature was 107 ° C., and the end temperature was 148 ° C. In Example 2, the rising temperature was 92 ° C., the peak temperature was 106 ° C., and the end temperature was 150 ° C. This shows that it cures at a lower temperature, and is more excellent in storage stability than the evaluation result of storage stability.

  In the measurement of connection resistance, a copper circuit with or without Sn plating was prepared, and the wiring connection material produced in Example 1 was used to temporarily connect to the FPC under the same conditions as in Example 1. When the connection resistance was measured after standing, the connection resistance was measured to be 2.3Ω when Sn plated, but 5Ω when the copper surface not plated with Sn was exposed.

  As described above in detail, according to the present invention, it is possible to provide a wiring connection material for electric and electronic that has excellent low-temperature fast-curing property, has a long working life, and has less circuit corrosivity than conventional epoxy resin systems. It becomes.

FIG. 6 is an explanatory view showing the wiring board manufacturing method of Example 1. It is sectional drawing which shows the connection part of the flexible wiring board used in Example 3. FIG. 6 is a cross-sectional view showing a wiring board at a connection portion of a liquid crystal panel used in Example 4;

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Printed circuit board, 11 ... Laminated board, 12 ... Circuit, 13 ... Resin composition, 14 ... Conductive particle, 15 ... Wiring connection material, 16 ... Connection terminal, 17 ... Adhesive, 18 ... Polyimide film, 19 ... Tape Carrier package, 21 ... wiring board, 22 ... polyimide film, 23 ... connecting terminal, 24 ... flexible wiring board, 25 ... glass substrate, 26 ... wiring, 27 ... liquid crystal panel.

Claims (9)

  A wiring connecting material comprising 2 to 75 parts by weight of a polyurethane resin, 30 to 60 parts by weight of a radical polymerizable substance, and 0.1 to 30 parts by weight of a curing agent that generates free radicals upon heating.   Furthermore, the wiring connection material of Claim 1 containing 0-40 weight part of film forming materials.   The wiring connection material according to claim 2, wherein the film forming material is a polyimide resin.   Furthermore, the wiring connection material in any one of Claims 1-3 containing electroconductive particle.   The said polyurethane resin is a wiring connection material in any one of Claims 1-3 whose pour point measured by the flow tester method is 40 to 140 degreeC.   The wiring connecting material according to any one of claims 1 to 5, wherein the curing agent has a weight retention of 20% by weight or more at 25 ° C for 24 hours.   The wiring connection material according to claim 1, wherein the radical polymerizable substance is urethane acrylate.   A wiring board manufacturing method including a connection step of connecting between wiring members each having a connection terminal so that the connection terminals can conduct, wherein the surfaces having the connection terminals face each other. The wiring board manufacturing method including the process of heating the wiring connection material of Claims 1-7 pinched between the two or more said wiring members arrange | positioned in this way, pressing through the said wiring member.   The wiring board manufacturing method according to claim 8, wherein at least one of the connection terminals is made of at least one selected from gold, silver, and platinum group metals.

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