JP4085488B2 - Circuit member mounting method and circuit member mounting adhesive - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a circuit member mounting method for bonding a semiconductor chip to a substrate with an adhesive by, for example, a flip chip mounting method, and electrically connecting both electrodes, and an adhesive for connecting a circuit member.
[0002]
[Prior art]
In the semiconductor mounting field, flip chip mounting, in which an IC chip is directly mounted on a printed circuit board or a flexible wiring board, has attracted attention as a new mounting form corresponding to cost reduction and high accuracy. As the flip chip mounting method, there are known a method in which solder bumps are provided on the terminals of the chip and solder connection is made, and a method in which electrical connection is made through a conductive adhesive. In these methods, there is a problem that when the stress based on the difference in thermal expansion coefficient between the chip to be connected and the substrate is exposed to various environments, it is generated at the connection interface and connection reliability is lowered. For this reason, a method of injecting an epoxy resin-based underfill material into the gap between the chip and the substrate is generally studied for the purpose of alleviating the stress at the connection interface. However, the underfill injection process complicates the process and is disadvantageous in terms of productivity and cost. Recently, flip-chip mounting using an anisotropic conductive adhesive having anisotropic conductivity and a sealing function has attracted attention from the viewpoint of process simplicity in order to solve such problems.
[0003]
[Problems to be solved by the invention]
Since mounting with anisotropic conductive adhesive requires heat and pressure, it must be performed at the beginning of the mounting process of electronic components on the board because it cannot be mounted on the back side of the board and due to considerations for mounting other electronic components. There was a restriction such as having to do so, and after thermocompression bonding, it took an inefficient mounting process of going through a reflow process with other electronic components.
The present invention provides a circuit member mounting method and a circuit member connecting adhesive that are mounted simultaneously with other electronic components and collectively cured by heat treatment while obtaining electrical conduction between electrodes of the circuit members. Is.
[0004]
[Means for Solving the Problems]
In the circuit member mounting method according to the present invention, the circuit member is bonded to the mounting substrate provided with the terminal (b) corresponding to the terminal (a) of the circuit member, with the terminal (a) and (b) facing each other. A circuit member mounting method for electrically connecting the terminals (a) and (b) by mounting together with other electronic components and heating the adhesive in a batch to thermally cure the adhesive. agents are including anisotropic conductive adhesive metal particles with a matrix resin and easily meltable metal surface, wherein the metal particles wherein the metal particles are melted deformed melted deformed by the heating terminal (a) (b) The matrix resin is a mixture of a UV curing system and a curing agent system that generates free radicals upon heating and / or a thermosetting epoxy resin, and generates free radicals upon heating. Hardener system and It is a mixed system with a curable epoxy resin, a curing agent system that generates free radicals by heating, or a thermosetting epoxy resin, and the electrical connection of the terminals (a) and (b) by the melted and deformed metal particles all SANYO having a viscosity which does not interfere with the heating step, characterized by connecting the only self-weight of the circuit member in said heating step terminals (a) (b) electrically.
[0005]
The mounting method of the present invention realizes the mounting of the circuit member through the adhesive only by the weight of the circuit member without applying special pressure . In implementing the above method Symbol circuit member, the matrix resin is a thermosetting resin, after electrically connecting the terminal (a) (b) by heating, is cured by heating the matrix resin at a temperature at which the molten metal particles Can be.
[0006]
Circuit member mount adhesive of the present invention, opposite the terminal of the circuit member to the mounting board terminals (b) are provided corresponding to the terminal (a) of the circuit member (a) (b), other It is an adhesive for mounting a circuit member for electrically connecting the terminals (a) and (b) by being mounted together with the electronic components , and being collectively heated and thermally cured , and is easily meltable with a matrix resin. Metal particles having a metal surface, wherein the metal particles are melted and deformed by heating, and the terminals (a) and (b) are electrically connected by the melted and deformed metal particles, and the matrix resin is UV-cured System and mixed system of curing agent system that generates free radicals by heating and / or thermosetting epoxy resin, mixed system of curing agent system that generates free radicals by heating and thermosetting epoxy resin, free radicals by heating The curing agent system generates le, or a thermosetting epoxy resin, those having the viscosity that does not interfere with the electrical connection of the by molten deformed metal particles terminals (a) (b) in the heating stage It is characterized by that.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The metal particles having an easily meltable metal surface used in the present invention include one metal selected from the group consisting of Sn, Bi, In, Ag, Sb, Cu, Zn, Ni, Au, Mg, Ga, and Al. Or it is an alloy material formed by combining two or more metals, and the melting point of the conductive fine particles is preferably 250 ° C. or lower, more preferably 100 ° C. or higher and 190 ° C. or lower. The metal particle surface layer may be an easily meltable metal.
[0008]
The adhesive used in the present invention is a UV curing system, a curing agent system that generates free radicals upon heating, a thermosetting epoxy resin, or a mixed system thereof. As a UV curing photoinitiator, benzoin ethyl ether is used. Benzoin ethers such as isopropyl benzoin ether, benzyl ketals such as benzyl and hydroxycyclohexyl phenyl ketone, ketones such as benzophenone and acetophenone and derivatives thereof, thioxanthones, bisimidazoles, etc. Sensitizers such as amines, sulfur compounds, and phosphorus compounds may be added in any ratio.
[0009]
Curing agents that generate free radicals upon heating are those that decompose upon heating of peroxide compounds, azo compounds, etc. to generate free radicals, and are appropriately selected according to the desired connection temperature, connection time, pot life, etc. Is done. A compounding quantity is about 0.05 to 10 weight%, and 0.1 to 5 weight% is more preferable. Specifically, it can be selected from diacyl peroxide, peroxydicarbonate, peroxyester, peroxyketal, dialkyl peroxide, hydroperoxide, silyl peroxide, and the like. Further, in order to suppress corrosion of the connection terminals of the circuit member, the chlorine ions and organic acids contained in the curing agent are preferably 5000 ppm or less, and more preferably less organic acids generated after the thermal decomposition. . Specifically, it is more preferably selected from peroxyesters, dialkyl peroxides, hydroperoxides, silyl peroxides, and peroxyesters that provide high reactivity. These can be mixed and used as appropriate.
In addition, it is preferable to use these curing agents coated with a polyurethane-based or polyester-based polymer substance to form a microcapsule because the pot life is extended.
[0010]
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. The radical polymerizable substance can be used in either a monomer or oligomer state, and the monomer and oligomer can be used in combination.
[0011]
The epoxy resin used in the present invention has a skeleton containing a bisphenol type epoxy resin derived from epichlorohydrin and bisphenol A, F, AD, etc., an epoxy novolac resin derived from epichlorohydrin and phenol novolac or cresol novolac, and a naphthalene ring. It is possible to use various epoxy compounds having two or more glycidyl groups in one molecule such as naphthalene epoxy resin, glycidylamine, glycidyl ether, biphenyl, alicyclic, etc. alone or in combination of two or more. It is. For these epoxy resins, it is preferable to use a high-purity product in which impurity ions (Na +, Cl-, etc.), hydrolyzable chlorine, etc. are reduced to 300 ppm or less to prevent electron migration.
The epoxy resin is preferably a trifunctional or higher polyfunctional epoxy resin and / or a naphthalene-based epoxy resin in order to lower the thermal expansion coefficient and improve the glass transition temperature. Examples of the trifunctional or higher polyfunctional epoxy resin include phenol novolac type epoxy resin, cresol novolac type epoxy resin, trishydroxyphenylmethane type epoxy resin, tetraphenylolethane type epoxy resin, dicyclopentadiene phenol type epoxy resin and the like. Naphthalene-based epoxy resins have a skeleton containing at least one naphthalene ring in one molecule, and include naphthol-based and naphthalenediol-based resins.
[0012]
A necessary amount of a rubber component such as acrylic rubber may be added to the adhesive. As the acrylic rubber, a polymer or copolymer containing at least one of acrylic acid, acrylic ester, methacrylic ester or acrylonitrile as a monomer component is used. Among them, a copolymer type acrylic rubber containing glycidyl acrylate or glycidyl methacrylate containing a glycidyl ether group is preferably used.
In addition, a thermoplastic resin such as a phenoxy resin can be blended in the adhesive in order to make film forming easier. In particular, the phenoxy resin is preferable because it has a similar structure to the epoxy resin and has characteristics such as excellent compatibility with the epoxy resin and excellent adhesion.
[0013]
As epoxy resin curing agents, latent curing agents such as imidazole, hydrazide, boron trifluoride-amine complexes, aromatic sulfonium salts, amine imides, polyamine salts and dicyandiamide are effective from the viewpoint of fast curing. In addition, an acid anhydride curing agent is also effective because it contains few ionic impurities.
The reflow treatment referred to in the present invention is a whole heating method such as infrared ray, air, vapor phase (VPS), nitrogen, and a partial heating method such as YAG laser, semiconductor laser, xenon lamp, halogen lamp, pulse heater, hot air. It is.
[0014]
Examples of the metal particle arrangement technique of the present invention include those described in JP-A-6-163550 and JP-A-6-310515, and the technique described in JP-A-6-163550 includes both sides. A closed space is formed on a glass jig on which a solder ball can be mounted on the surface side having a large diameter hole having a large number of through holes having different diameters, and the solder ball is sent into the closed space by compressed air. By sucking from the small holes of the glass jig, the solder balls are sucked into the large through holes of the glass jig and arranged. Further, in the technique described in Japanese Patent Laid-Open No. 6-310515, solder balls are supplied by a screw feeder or the like onto a plate on which a certain number of solder balls can be mounted in an alignment, and are arranged by being oscillated by a vacuum pump and a vibrator. ing. Also, a method is provided in which suction holes are provided at desired intervals in the mounting head, the mounting head is moved up and down, and the conductive balls are vacuum-sucked to move the mounting head onto the sheet to be disposed, and then the suction is released and arranged. And a method using a mesh. These techniques may be used.
In addition, the adhesive film may have a multilayer structure of a support layer and an adhesive layer. In that case, an adhesive layer coating → drying → support layer coating → curing → adhesive layer coating → drying step may be taken. . Regarding the dispersion of the conductive fine particles, if electrostatic force is used, excess particles can be recovered, and efficient dispersion can be achieved.
[0015]
Moreover, when shape | molded in the shape of a film in this invention, it is desirable that the surface of electroconductive fine particles is exposed from the surface of the front and back of a film, and it is desirable that the adhesive force is provided to the surface of the film. The conductive fine particles need to have a particle size smaller than the minimum distance between the electrodes of the substrate, and may be deformed into a predetermined shape as necessary. The amount of conductive particles dispersed in the adhesive is 0.1 to 30 parts by volume, preferably 0.2 to 15 parts by volume with respect to 100 parts by volume of the adhesive resin composition.
[0016]
The adhesive for connecting circuit members used in the present invention may be used by screen-printing a liquid adhesive on the electrodes of the circuit board instead of the film adhesive.
As the circuit member, semiconductor packages (QFP, BGA, CSP, SOP, TCP, etc.), chip parts such as capacitors, resistors, coils, connectors, and the like are used.
The circuit member is provided with a large number of terminals, and the circuit member is mounted on a mounting board provided with a number of terminals corresponding to the terminals with the terminals facing each other via an adhesive, and the terminals are electrically connected. And implemented.
As a substrate on which chip components are mounted, an organic insulating substrate on which electrodes (connection terminals) corresponding to semiconductor chip terminals are formed is used.
[0017]
As an organic insulating substrate, a laminated board obtained by impregnating and curing a resin material such as a polyimide resin, an epoxy resin or a phenol resin on a glass substrate such as a polyimide resin or a polyester resin, or a glass cloth or a glass nonwoven fabric. Is used.
An electrode connected to the circuit member terminal, a surface insulating layer on which the electrode is formed, a predetermined number of insulating layers, a predetermined number of wiring layers disposed via the insulating layers, and a predetermined number of the electrodes / wiring layers A multilayer wiring board having conductive holes for electrical connection can be used.
As such a multilayer wiring board, a build-up multilayer in which insulating layers and conductor circuit layers are alternately formed on a substrate composed of an insulating layer using glass cloth or a wiring substrate having one or more conductor circuits A substrate is preferred.
[0018]
A resin film can be used for the surface insulating layer, and this resin film is an epoxy resin, a polyimide resin, a polyamide-imide resin, a modified polyphenylene ether resin, a phenoxy resin, an amide epoxy resin, a phenol resin, a mixture thereof, a copolymer, or the like. A film of heat-resistant thermoplastic engineering plastic such as polysulfone, polyethersulfone, polyetheretherketone, wholly aromatic liquid crystal polyester, and fluorine resin can be used. A resin film containing an organic or inorganic filler can be used. As the insulating layer made of a resin reinforced with a glass substrate, a prepreg obtained by impregnating and curing a resin such as an epoxy resin or a phenol resin on a glass substrate such as glass cloth or glass nonwoven fabric can be used.
[0019]
On the electrode pad of the semiconductor chip or substrate, the bump formed by plating or the tip of the gold wire is melted with a torch or the like to form a gold ball, and after the ball is pressed onto the electrode pad, the wire is cut. Protruding electrodes such as wire bumps obtained in this way can be provided and used as connection terminals.
[0020]
FIG. 1 is a cross-sectional view of a QFP package mounted on a mounting substrate using the mounting method of the present invention, and FIG. 2 is a cross-sectional view of a CSP package mounted on a mounting substrate using the mounting method of the present invention. 1 is a mounting substrate, 2 is an electrode on the substrate, 3 is a QFP package, 4 is a lead terminal, 5 is Ni particles, 6 is a Sn-Bi alloy, 7 is an adhesive, 8 is a semiconductor element, 9 is a sealing agent, Reference numeral 10 denotes an interposer, and 11 denotes a solder ball.
[0021]
【Example】
Particles (10 μmφ, 8 vol%) coated with Sn—Bi alloy (melting point: 139 ° C.) on the surface of Ni particles are dispersed in a phenol curing thermosetting adhesive having a gelation temperature of 160 ° C., and a glass-epoxy circuit board After coating on top, BGA package (225 pin) is mounted after alignment, passed through heating furnace (max. 150 ° C) for 1 minute, continuity test is performed, NG sample is repaired and reconnected, OK The sample was cured in an oven at 200 ° C. for 3 hours to obtain a mounted component. Good results were obtained in both the heat cycle test (−55 ° C. to 125 ° C.) and the high temperature and high humidity test (85 ° C./85% RH). The viscosity of the phenol curable thermosetting adhesive was 1000 CP in a heating furnace (max. 150 ° C.).
[0022]
【The invention's effect】
According to the mounting method of the present invention, it is possible to realize mounting of an electronic component using an anisotropic conductive adhesive only by its own weight without applying special pressure, and it can be performed together with mounting of other electronic components. Thus, heat curing can be performed and electrical conduction between the electrodes of the circuit members can be obtained, so that the mounting process can be simplified and a significant cost reduction can be achieved. Further, an inspection process and a repair process can be provided between the electrical connection process and the mechanical connection process as necessary.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a QFP package mounted on a mounting substrate using the mounting method of the present invention.
FIG. 2 is a cross-sectional view of a CSP package mounted on a mounting substrate using the mounting method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Circuit board 2 Electrode on a board | substrate 3 QFP package 4 Lead terminal 5 Ni particle 6 Sn-Bi alloy 7 Adhesive 8 Semiconductor element 9 Sealant 10 Interposer 11 Solder ball

Claims (2)

A circuit member is mounted together with other electronic components via an adhesive, facing the terminals (a) and (b) on a mounting board provided with terminals (b) corresponding to the terminals (a) of the circuit members, A circuit member mounting method for electrically connecting the terminals (a) and (b) by collectively heating and thermally curing the adhesive,
The adhesive is including anisotropic conductive adhesive metal particles with a matrix resin and easily meltable metal surface,
The metal particles are melted and deformed by the heating, and the terminals (a) and (b) are electrically connected to the melted and deformed metal particles,
The matrix resin is composed of a UV curing system and a curing system that generates free radicals upon heating and / or a thermosetting epoxy resin, a curing system that generates free radicals upon heating and a thermosetting epoxy resin. It is a mixed system, a curing agent system that generates free radicals upon heating, or a thermosetting epoxy resin, and has a viscosity that does not hinder the electrical connection of the terminals (a) and (b) by the melted and deformed metal particles. all SANYO has in stage,
The circuit member mounting method , wherein the terminals (a) and (b) are electrically connected only by the weight of the circuit member in the heating step .   2. The circuit member mounting method according to claim 1, wherein the matrix resin is a thermosetting resin, and after the terminals (a) and (b) are electrically connected by heating, the matrix is melted at a temperature at which the metal particles melt. A circuit member mounting method in which resin is heat-cured.

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