JP2000133917A - Packaging of circuit member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of packaging a electronic component, which uses an anisotropic conductive adhesive only by the self weight of the electronic component without particularly pressuring the adhesive. SOLUTION: Ni grains with the surfaces covered with an Sn-In alloy (a melting point of 117 deg.C) are dispersed in a phenolic curing system thermosetting adhesive having a melting viscosity of 1000 cps at a temperature of 117 deg.C to obtain an anisotropic conductive bonding agent. The anisotropic conductive adhesive is applied on electrodes on a glass epoxy mounting substrate. Electrodes of a QFP package (124 pins) and a BGA package (225 pins) are aligned with the substrate electrodes and the QEP and BGA packages are mounted on the substrate. Subsequently, ultrasonic vibrations of a frequency of 65 Hz are applied to the substrate for 20 msec and after an adhesive 6 between all the electrodes of the packages and conductive grains 5 and between the conductive grains 5 and the substrate electrodes 2 is eliminated, the substrate is put in a heating furnace of a temperature of 130 deg.C for one minute. After the substrate is taken out from the heating furnace, the substrate is heated and cured in a heating furnace of a temperature of 200 deg.C for two hours.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting a circuit member for bonding a semiconductor chip to a substrate with an adhesive and electrically connecting both electrodes by, for example, a flip chip mounting method.

[0002]

2. Description of the Related Art In the field of semiconductor mounting, flip chip mounting, in which an IC chip is directly mounted on a printed circuit board or a flexible wiring board, has been attracting attention as a new mounting mode corresponding to cost reduction and high precision. As a flip-chip mounting method, a method of providing a solder bump on a terminal of a chip and performing solder connection or a method of performing electrical connection via a conductive adhesive is known. In these methods, there is a problem in that when exposed to various environments, stress based on the difference in thermal expansion coefficient between the chip to be connected and the substrate is generated at the connection interface and connection reliability is reduced. For this reason, a method of injecting an epoxy resin-based underfill material into a gap between a chip and a substrate is generally studied for the purpose of reducing stress at a connection interface. However, there is a problem that the underfill injection step complicates the process and is disadvantageous in terms of productivity and cost. In order to solve such a problem, flip-chip mounting using an anisotropic conductive adhesive having anisotropic conductivity and a sealing function has recently attracted attention from the viewpoint of process simplicity.

[0003]

Since mounting with an anisotropic conductive adhesive requires heat and pressure, it cannot be mounted on the back side of the substrate and other electronic components must be mounted. There are restrictions such as the fact that it must be performed at the beginning of the component mounting process, and an inefficient mounting process has been adopted in which, after thermocompression bonding, a reflow process is performed together with other electronic components.
The present invention provides a method for mounting a circuit member, which is mounted simultaneously with another electronic component, is collectively thermally cured by a heat treatment, and obtains electrical conduction between electrodes of the circuit member.

[0004]

According to the method of mounting a circuit member of the present invention, the circuit member is mounted on a mounting board provided with a terminal (b) corresponding to the terminal (a) of the circuit member.
(B) is a method of mounting a circuit member which is opposed to and mounted with an adhesive containing a matrix resin and metal particles, and which electrically connects the terminals (a) and (b) by heating. A step of applying sonic vibration to expose metal particles on both surfaces of the matrix resin.
Preferably, the metal particles are metal particles having a readily fusible metal surface. Ultrasonic vibration, frequency 25 ~ 100KH
z, a condition of a vibration time of 10 to 50 seconds is preferable.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION As metal particles, Au, Ag,
Metal particles such as Ni, Cu, and solder, and carbon can be used. In the case where the above-mentioned conductive layer is formed on a plastic by coating or the like and the outermost layer is made of a noble metal plastic as a nucleus or in the case of hot-melt metal particles, the contact area with the electrode increases at the time of connection because it has deformability by heating and pressing. This is preferable because the reliability is improved. In addition, Sn, Bi, In, Ag, Sb, Cu, Z, which are metal particles having a fusible metal surface.
n, Ni, Au, Mg, Ga and an alloy material made of a combination of two or more metals selected from the group consisting of Ga and Al, and the melting point of the conductive fine particles is preferably 250 ° C. or less, more preferably Is 100 ° C. or more and 190 ° C. or less. The metal particle surface layer may be a fusible metal.

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 mixture thereof. Benzoin ethyl ether, benzoin ether such as isopropyl benzoin ether, benzyl, benzyl ketal such as hydroxycyclohexyl phenyl ketone, benzophenone,
There are ketones such as acetophenone and derivatives thereof, thioxanthones, bisimidazoles, and the like.If necessary, sensitizers such as amines, sulfur compounds, and phosphorus compounds may be added to these photoinitiators at any ratio. Is also good.

The curing agent which generates free radicals upon heating is one which decomposes upon heating of a peroxide compound, an azo compound or the like to generate free radicals, and has a desired connection temperature, connection time, pot life and the like. Is selected as appropriate. The compounding amount is about 0.05 to 10% by weight, and more preferably 0.1 to 5% by weight. Specifically, it can be selected from diacyl peroxide, peroxydicarbonate, peroxyester, peroxyketal, dialkyl peroxide, hydroperoxide, silyl peroxide and the like. Further, in order to suppress the corrosion of the connection terminal of the circuit member, the chlorine ion and the organic acid contained in the curing agent are preferably 5000 ppm or less,
Further, those having less organic acid generated after thermal decomposition are more preferable. Specifically, it is selected from peroxyesters, dialkyl peroxides, hydroperoxides, and silyl peroxides, and is more preferably selected from peroxyesters having high reactivity. These can be used by mixing as appropriate. A microcapsule obtained by coating these curing agents with a polyurethane-based or polyester-based polymer substance or the like is preferable because the pot life is extended.

The radically polymerizable substance used in the present invention is a substance having a functional group which is polymerized by a radical, such as acrylate, methacrylate, and maleimide compound. The radical 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.

The epoxy resin used in the present invention includes a bisphenol type epoxy resin derived from epichlorohydrin and bisphenol A, F, AD, etc., an epoxy novolak resin derived from epichlorohydrin and phenol novolak or cresol novolak, and a naphthalene ring. Naphthalene epoxy resin having a skeleton, glycidylamine, glycidyl ether, biphenyl, various epoxy compounds having two or more glycidyl groups in one molecule such as alicyclic, etc. are used alone or as a mixture of two or more. It is possible. It is preferable to use a high-purity epoxy resin in which impurity ions (Na +, Cl −, etc.), hydrolyzable chlorine and the like are reduced to 300 ppm or less for preventing electron migration. The epoxy resin is preferably a trifunctional or higher-functional polyfunctional epoxy resin and / or a naphthalene-based epoxy resin in order to reduce the coefficient of thermal expansion and improve the glass transition temperature. Examples of the trifunctional or higher polyfunctional epoxy resin include a phenol novolak type epoxy resin, a cresol novolak type epoxy resin, a trishydroxyphenylmethane type epoxy resin, a tetraphenylolethane type epoxy resin, and a dicyclopentadiene phenol type epoxy resin. Further, the naphthalene epoxy resin has a skeleton containing at least one naphthalene ring in one molecule,
There are naphthol type, naphthalene diol type and the like.

A necessary amount of a rubber component such as acrylic rubber may be added to the adhesive. As the acrylic rubber, a polymer containing at least one of acrylic acid, acrylic ester, methacrylic ester or acrylonitrile as a monomer component is used. Copolymers or copolymers can be mentioned, and among them, copolymer 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 with the adhesive in order to make the film formability 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 adhesiveness.

As the curing agent for the epoxy resin, a latent curing agent such as an imidazole-based compound, a hydrazide-based compound, a boron trifluoride-amine complex, an aromatic sulfonium salt, an amine imide, a polyamine salt, or dicyandiamide is used. From the viewpoint, it is effective, and an acid anhydride-based curing agent is also effective because it has less ionic impurities. The reflow treatment according to the present invention is performed by the whole heating method such as infrared ray, air, vapor phase (VPS), nitrogen, etc.
It is a partial heating method such as laser, semiconductor laser, xenon lamp, halogen lamp, pulse heater, hot air and the like.

The technique for arranging metal particles of the present invention includes, for example, JP-A-6-163550 and JP-A-6-310.
No. 515, for example, are disclosed in
In the technique described in Japanese Patent No. 163550, a closed space is formed on a glass jig having a large number of through-holes having different diameters on both sides, and a solder ball can be mounted on a surface having a large-diameter hole. Is sent to the closed space by compressed air, and is sucked from the small-diameter hole of the glass jig, so that the solder balls are sucked and arranged in the large-diameter through-hole of the glass jig. Also, Japanese Patent Application Laid-Open No. Hei 6-31051
In the technique described in Japanese Patent Application Laid-Open No. 5 (1999) -1995, solder balls are supplied by a screw feeder or the like on a plate on which solder balls can be mounted in a fixed number, and are vibrated and arranged by a vacuum pump and a vibrator. Also, a method in which suction holes are provided at desired intervals in the mounting head, and the mounting head is moved up and down to vacuum-adsorb the conductive balls and move the mounting head onto a sheet to be arranged, and then release and arrange the suction. And a method using a mesh. These techniques may be used. Further, the adhesive film may have a multilayer structure of a support layer and an adhesive layer, in which case, the steps of adhesive layer coating → drying → support layer coating → curing → adhesive layer coating → drying may be performed. . Regarding the spraying of the conductive fine particles, if the electrostatic force is used, surplus particles can be collected, and efficient spraying can be performed.

In the present invention, when formed into a film, the surface of the conductive fine particles is desirably exposed from the front and back surfaces of the film, and it is desirable that the surface of the film has an adhesive force. In addition, since the conductive fine particles need to have a particle size smaller than the minimum distance between the electrodes of the substrate, the conductive fine particles may be deformed into a predetermined shape as needed. The amount of the conductive particles dispersed in the adhesive is 0.1 to 3 with respect to 100 parts by volume of the adhesive resin composition.
0 parts by volume, preferably 0.2 to 15 parts by volume.

The adhesive for connecting circuit members used in the present invention may be a screen-printed liquid adhesive instead of a film-like adhesive on the electrodes of the circuit board. As a circuit member, a semiconductor package (QFP, BGA, C
SP, SOP, TCP, etc.), chip components such as capacitors, resistors, and 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 large number of terminals corresponding to the terminals via an adhesive with the terminals facing each other, and the terminals are electrically connected. 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.

As the organic insulating substrate, a synthetic resin film such as a polyimide resin or a polyester resin, or a glass substrate such as a glass cloth or a glass nonwoven fabric is impregnated with a resin such as a polyimide resin, an epoxy resin, or a phenol resin, and cured. Laminated boards are used. An electrode connected to a 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 arranged via the respective insulating layers, and a predetermined number of the electrode / wiring layers. A multilayer wiring board having electrically conductive holes for electrical connection can be used. As such a multilayer wiring board, a build-up multilayer in which insulating layers and conductive circuit layers are alternately formed on a substrate composed of insulating layers using glass cloth or a wiring board having one or more conductive circuits. Substrates are preferred.

As the surface insulating layer, a resin film can be used. This resin film is made of an epoxy resin, a polyimide resin, a polyamideimide resin, a modified polyphenylene ether resin, a phenoxy resin, an amide epoxy resin, a phenol resin or a mixture thereof. Films of polymers and the like, and films of heat-resistant thermoplastic engineering plastics such as polysulfone, polyethersulfone, polyetheretherketone, wholly aromatic liquid crystal polyester, and fluororesin 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 base material, a prepreg obtained by impregnating a glass base material such as a glass cloth or a nonwoven fabric with a resin such as an epoxy resin or a phenol resin and curing the resin can be used.

On an electrode pad of a semiconductor chip or a substrate,
The tip of the bump or gold wire formed by plating is melted with a torch or the like to form a gold ball, and after this ball is pressed on an electrode pad, a protruding electrode such as a wire bump obtained by cutting the wire is provided. It can be used as a connection terminal.

FIG. 1 shows a QFP using the mounting method of the present invention.
FIG. 2 is a cross-sectional view in which the package is mounted on a mounting board, and FIG. 2 is a cross-sectional view in which the CSP package is mounted on the mounting board using the mounting method of the present invention. 1 is a mounting board, 2 is an electrode on the board, 3 is a QFP package, 4 is a lead terminal, 5 is N
i particles, 6 an Sn—Bi alloy, 7 an adhesive, 8 a semiconductor element, 9 a sealant, 10 an interposer, and 11 solder balls.

[0019]

EXAMPLE 11 Ni particles (particle diameter 10 μmφ, 8 vol%) coated on the surface with a Sn—In alloy (melting point 117 ° C.)
It was dispersed in a phenol-cured thermosetting adhesive having a melt viscosity at 7 ° C. of 1000 cps to obtain an anisotropic conductive adhesive. An anisotropic conductive adhesive was applied on the electrodes of the glass-epoxy mounting substrate. Next, the QFP package (124
Pins) and the electrodes of the BGA package (225 pins) and the substrate electrodes were aligned and mounted. Subsequently, ultrasonic vibration at a frequency of 65 Hz was applied to the substrate for 20 msec to remove all the electrodes and conductive particles of each package, and the adhesive between the conductive particles and the substrate electrodes, and then placed in a 130 ° C. heating furnace.
Put for minutes. After being taken out of the heating furnace, a continuity test was performed. For the NG product, it was decided to mount it again after repairing, and for the OK product, it was heated and cured in a heating furnace at 200 ° C. for 2 hours. The mounted sample after heat curing is subjected to a heat cycle test (-55 ° C to 125 ° C) and a high temperature and high humidity test (85 ° C /
85% RH).

[0020]

According to the mounting method of the present invention, mounting of an electronic component using an anisotropic conductive adhesive can be realized only by the weight of the electronic component without applying special pressure, and other electronic components can be realized. In addition, heat curing can be performed at the same time as the mounting, and electrical conduction between the electrodes of the circuit members can be obtained, so that the mounting process can be simplified and the cost can be significantly reduced. In addition, it is possible to provide an inspection step and a repair step between the electrical connection step and the mechanical connection step as needed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view in which a QFP package is mounted on a mounting board using an anisotropic conductive adhesive, and then mounted by applying ultrasonic vibration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Circuit board 2 Electrode on board 3 QFP package 4 Lead terminal 5 Conductive particle 6 Adhesive

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kenzo Takemura 48 Wadai, Tsukuba, Ibaraki Prefecture F-term in Tsukuba Development Laboratory, Hitachi Chemical Co., Ltd. 5E319 AA03 AB01 BB04 BB07 BB08 BB09 BB10 BB16 BB20 CC61 GG15 5F044 KK01 LL09 QQ01

Claims (3)

[Claims] 1. A bonding method comprising bonding a circuit member to a mounting substrate provided with terminals (b) corresponding to the terminals (a) of the circuit member, the terminals (a) and (b) being opposed to each other and including a matrix resin and metal particles. And the terminal (a)
A method for mounting a circuit member for electrically connecting (b), comprising a step of applying ultrasonic vibration to the mounting substrate to expose metal particles on both surfaces of the matrix resin. Method. 2. The method for mounting a circuit member according to claim 1, wherein the metal particles are metal particles having an easily fusible metal surface. 3. The ultrasonic vibration has a frequency of 25 to 100 KH.
3. The method for mounting a circuit member according to claim 1, wherein z is a vibration time of 10 to 50 seconds.