JP2009242508A - Adhesive and bonded body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive which can be hardened thermally at a low temperature of 150°C or below and has high connection reliability and high adhesive strength. <P>SOLUTION: The adhesive contains an epoxy-modified silicone oil, an epoxy resin other than the epoxy-modified silicone oil, and a hardening agent. When an electrically conductive particle of ≥0.1 vol.% and <30 vol.% is contained in the adhesive based on 100 vol.% of the sum of the resin component and the hardening agent component of the adhesive, the obtained adhesive can be used as an anisotropically conductive adhesive. When the electrically conductive particle of 30-80 vol.% is contained in the adhesive, the obtained adhesive can be used as an electrically conductive adhesive. It is preferable that the electrically conductive particle has 1-20 μm average particle diameter. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an adhesive, and more particularly to an adhesive suitable for adhering a semiconductor element or semiconductor module such as an IC or LSI to a support substrate such as a lead frame or a wiring board.

Conventionally, as an adhesive containing conductive particles, an adhesive capable of exhibiting anisotropic conductivity (hereinafter also referred to as “anisotropic conductive adhesive”) and an adhesive exhibiting conductivity (hereinafter referred to as “conductive adhesive”). Also known). Among these, anisotropic conductive adhesives are adhesives that connect the electrodes (connection electrodes and connected electrodes) by deforming the conductive particles to some extent by heating and pressurizing the intended connection electrodes and connected electrodes. A bonded body can be obtained by curing.
As an adhesive used for the anisotropic conductive adhesive, an adhesive using an epoxy resin, a phenoxy resin, or a latent curing agent is known. (For example, Patent Documents 1 and 2).

A method for connecting the connection electrode and the electrode to be connected in the case where the anisotropic conductive adhesive is used will be described.
First, a base material (for example, a polyimide flexible printed circuit board) having an electrode to be connected or an electronic component (for example, an IC chip) is placed on a base material having a connection electrode to obtain a structure. Next, a heating head is pressed against the structure and heated and pressed to cure the adhesive contained in the anisotropic conductive adhesive. This makes it possible to maintain insulation between adjacent electrodes while electrically connecting between different substrates or between the substrate and the electronic component by the conductive particles.

  As a problem of the prior art, in the case where the connection electrode on the flexible base material and the electrode to be connected are joined, there is a current situation that the flexible base material has poor heat resistance and resistance to deformation against a load. That is, a specific flexible substrate cannot be connected at a high temperature exceeding 150 ° C. or a high pressure of 3 MPa or more. Therefore, the connection object of anisotropic conductive adhesive was limited to base materials, such as glass, and a heat-resistant film, for example, a polyimide film.

  Patent Document 1 discloses a conductive adhesive containing an epoxy-modified silicone compound obtained by a reaction between an organopolysiloxane having phenol groups at both ends and an epoxy resin, a curing agent, and conductive particles. Patent Document 2 discloses a conductive adhesive containing an epoxy-modified silicone compound obtained by a reaction between a dimethylsiloxane having a carboxyl group at both ends and an epoxy resin, a curing agent, and a conductive filler. is there. All the adhesives had problems in connection reliability.

Japanese Patent Publication No. 6-37613 JP-A-11-236545

  An object of the present invention is to provide an adhesive that can overcome the above problems and can be cured by heating at a low temperature of 150 ° C. or less, and has high connection reliability and high adhesive strength.

As a result of intensive studies to solve the above problems, the present inventor has come to the following invention.
That is, the present invention is as follows.
(1) An adhesive comprising an epoxy-modified silicone oil, an epoxy resin other than the epoxy-modified silicone oil, and a curing agent.
(2) The adhesive according to (1), further comprising conductive particles.
(3) The adhesive according to (2), wherein the conductive particles are conductive particles having an average particle diameter of 1 μm to 20 μm.
(4) The adhesive according to any one of (1) to (3), wherein the curing agent is a latent curing agent.
(5) The conductive particles may be contained in an amount of 0.1% by volume to less than 30% by volume with respect to a total of 100% by volume of the resin component and the curing agent component of the adhesive, and may exhibit anisotropic conductivity ( The adhesive agent as described in any one of 2)-(4).
(6) The conductive particles are contained in an amount of 30% by volume to 80% by volume with respect to a total of 100% by volume of the resin component and the curing agent component of the adhesive, and any one of (2) to (4) The adhesive according to item.
(7) A method for producing a joined body, comprising placing the adhesive according to (5) or (6) on a substrate having a conductive electrode or a conductive electrode, and thermocompression bonding the electronic component.
(8) A joined body made of a base material or a conductive electrode having a conductive electrode and an electronic component manufactured by the manufacturing method according to (7).

The adhesive of the present invention can be heat-cured at a low temperature of 150 ° C. or less, and has high connection reliability and high adhesive strength.
Therefore, a film base material that has not been connected in the past and has high transparency but no heat resistance, such as a polyethylene terephthalate film (hereinafter also referred to as “PET film”) or a polycarbonate film (hereinafter also referred to as “PC film”). In addition, it has become possible to conduct a conductive connection while having a high adhesive force with an electronic component typified by an IC chip or a substrate having a conductive electrode.

The adhesive of the present invention includes at least an epoxy-modified silicone oil, an epoxy resin other than the epoxy-modified silicone oil (hereinafter also simply referred to as “epoxy resin”), and a curing agent.
As the epoxy-modified silicone oil, for example, a silicone oil in which epoxy groups are introduced at both ends or side chains of a dimethyl or diethyl silicone skeleton can be used.
The epoxy group is preferably an epoxy group contained in a glycidyl group or an epoxy group contained in an alicyclic epoxy group.
Specific examples of the epoxy-modified silicone oil include BY16-855, SF8411, SF8413, FZ-3720, BY16-839, and SF8421 manufactured by Toray DOW CORNING.

  The content of the epoxy-modified silicone oil in the resin component of the adhesive is preferably 0.1% by volume or more and 50% by volume or less. More preferably, they are 1 volume% or more and 40 volume% or less. From the viewpoint of adhesion, it is preferably 0.1% by volume or more and from the viewpoint of connection reliability, 50% by volume or less is preferable.

The epoxy resin other than the epoxy-modified silicone oil referred to here is a resin containing an epoxy group, and a resin other than the above-described silicone epoxy-modified silicone oil is used. Examples of such an epoxy resin include bisphenol A resin, bisphenol F resin, naphthalene resin, bisphenol S resin, phenol novolac resin, cresol novolac resin, alicyclic resin, biphenyl resin, dicyclo Bifunctional to tetrafunctional epoxy resins such as pentadiene type resin, glycidylamine type resin, and glycidyl ester type resin can be used. As the epoxy resin, a single resin or a plurality of resins may be used.
By simultaneously using the epoxy-modified silicone oil and the epoxy resin, it is possible to provide an adhesive having uniformly high adhesion strength.

  The content of the epoxy resin in the resin component of the adhesive is preferably 5% by volume or more and 90% by volume or less. More preferably, they are 10 volume% or more and 80 volume% or less. More preferably, it is 20% by volume or more from the viewpoint of adhesion to a substrate and curing shrinkage, and 70% by volume or less from the viewpoint of forming a film-like adhesive.

Any curing agent may be used as long as it can cure the epoxy resin and the epoxy-modified silicone oil. When the adhesive of the present invention is used by heating, a certain degree of preservation is required after mixing until the start of use. For this reason, it is preferable that a hardening agent is a latent hardening agent, for example, an acid anhydride, a polyamine, an amine compound, phenols, imidazoles etc. can be used. In order to ensure storage stability at room temperature, it is more preferable to encapsulate the latent curing agent. In particular, a latent curing agent obtained by microencapsulating an imidazole curing agent is preferable.
The amount of the curing agent used is preferably 5 to 300% by volume with respect to 100% by volume in total of the epoxy resin and the epoxy-modified silicone oil.

The adhesive can contain conductive particles. The conductive particles are preferably those having an average particle diameter of 1 to 20 μm. From the viewpoint of being able to absorb the range of height variation between the connection electrodes during heat-curing connection, it is preferably 1 μm or more, and preferably 20 μm or less from the viewpoint of handleability when the adhesive is formed into a film. The average particle diameter of the conductive particles is more preferably 2 μm to 10 μm.
The average particle size of the conductive particles can be defined as a 50% volume cumulative particle size value measured by a laser diffraction method using an airflow particle size distribution analyzer (ROODS SR).

  Known conductive particles can be used as the conductive particles. For example, nickel, gold plated particles, copper particles, silver particles, silver-copper alloy particles, solder particles, non-lead solder particles, nickel particles, and gold plated particles thereof can be used on plastic particles. Among them, metal particles, particularly copper, silver, gold, tin, or alloys thereof are preferable because they are soft and non-destructive. Therefore, connection at a low pressure of 0.5 MPa or less is possible. For example, there is an advantage that a transparent ITO electrode or the like is not destroyed.

  The adhesive can be used as an anisotropic conductive adhesive by containing 0.1% by volume or more and less than 30% by volume of conductive particles with respect to a total of 100% by volume of the resin component and the curing agent of the adhesive. The volume% of the conductive particles is calculated from the specific gravity by measuring the mass. The content of the conductive particles is more preferably 0.5 to 15% by volume.

As the adhesive, in addition to the epoxy-modified silicone oil and the epoxy resin, a phenoxy resin, an acrylic resin, a methacrylic resin, a silane coupling agent, a titanium coupling agent, a silicone pressure-sensitive adhesive, and the like can be mixed and used.
Examples of the phenoxy resin include bisphenol A type, F type phenoxy resin, polyol-modified phenoxy resin, and the like. When it contains a phenoxy resin, it can be contained in an amount of 30% by volume to 80% by volume in the resin component of the adhesive.

The anisotropic conductive adhesive may be used in either a paste form or a film form.
When used in the form of a film, the thickness of the film is preferably 10 μm or more and 50 μm or less.
When used in the form of a paste, it is preferably used after adjusting to an appropriate viscosity using an appropriate solvent or reactive diluent.

  A base material having a first conductive electrode, such as an FPC (flexible printed circuit board), or an electronic component, for example, an electronic component represented by an IC chip, is formed on the base material having a second conductive electrode. When connecting using a dispenser or syringe, apply an appropriate amount of anisotropic conductive adhesive on the substrate having the second conductive electrode, and the substrate or electron having the first conductive electrode. A method in which the component and the counter electrode of the substrate having the second conductive electrode are aligned and then heated and cured from the substrate or electronic component side having the first conductive electrode is preferable. Similarly, when the anisotropic conductive adhesive is used in the form of a film, the film is attached on the base material having the second conductive electrode, and the adhesive is heated at an actual temperature of 110 to 150 ° C .; A method of curing by pressing at 2 to 3 MPa is preferred.

  The electrode provided on the substrate having the first conductive electrode, the electronic component, and the substrate having the second conductive electrode are ITO, copper, gold, silver, IZO, aluminum, tantalum, tin, titanium, nickel, An electrode containing at least one selected from chromium is preferable.

Furthermore, the anisotropic conductive adhesive can be used even on a flexible base material in which at least one of the base material having the first conductive electrode and the base material having the second conductive electrode has poor heat resistance.
A flexible base material having poor heat resistance is a base material that cannot withstand heating at 160 ° C. or higher, and is, for example, a PET film or a PC (polycarbonate) film.

  In addition, the adhesive contains 30% by volume to 80% by volume of conductive particles with respect to a total of 100% by volume of the resin component and the curing agent component of the adhesive, and exhibits conductivity (hereinafter referred to as conductive). It can be used as an adhesive). The content of the conductive particles is more preferably 40% by volume to 60% by volume in the adhesive.

  When a base material having a first conductive electrode, for example, an FPC or an electronic component, for example, an electronic component represented by an IC chip, is connected to a base material having a second conductive electrode using a conductive adhesive, A method in which a conductive adhesive is applied or printed on a base material having a first conductive electrode, or an electronic component or a base material having a second conductive electrode, and is cured by heating at 110 ° C. to 150 ° C. Can be used. At this time, it can also pressurize at 0.2-3 MPa as needed.

  By using the adhesive of the present invention, the ITO or IZO electrode connection on the flexible substrate using a film with poor heat resistance can be connected at a low temperature of 130 ° C., and the adhesive strength is reduced at a low temperature. It has the great advantage of maintaining high adhesive strength over the prior art. In particular, by containing an epoxy-modified silicone oil, the effect of improving the adhesive strength without lowering the compatibility with the epoxy resin can be obtained.

  Moreover, the adhesive excellent in storage stability can be provided by using a latent hardener. By using the adhesive of the present invention, it can be applied to uses such as a flexible display (for example, electronic paper), high-definition organic EL, LED element connection, liquid crystal panel, and COF (chip on film).

The present invention will be described below based on examples.
The raw material components of the adhesive used in the examples and comparative examples are as follows.
(Epoxy resin)
A: Bisphenol A type epoxy resin (AER2600 manufactured by Asahi Kasei Chemicals)
B: Bisphenol F-type epoxy resin (RE-303S manufactured by Nippon Kayaku Co., Ltd.)
C: Naphthalene type epoxy resin (HP-4032D manufactured by Dainippon Ink Co., Ltd.)
D: Biphenyl type epoxy resin (Japan Epoxy Resin YX4000)
(Phenoxy resin)
F: Phenoxy resin (PKHC manufactured by Inchem)
(Epoxy-modified silicone oil)
G: Epoxy modified silicone oil (SF8413 manufactured by Dow Corning)
H: Epoxy-modified silicone oil (BY16-855, manufactured by Dow Corning)
I: Epoxy-modified silicone oil (BY16-839 manufactured by Dow Corning)
(Curing agent)
J: Latent curing agent (HX3941HP manufactured by Asahi Kasei Chemicals Corporation)
(Other)
K: Silane coupling agent (Shin-Etsu Chemical KBM403)

<Examples 1 and 2>
Compositions 1 and 2 were prepared in the proportions shown in Table 1, applied onto a 50 μm film made of PET using a bar coater, and dried in air at 60 ° C. for 10 minutes to form a 25 μm film. An anisotropic conductive adhesive was obtained. In order to judge the compatibility between the adhesive and PET at this time, the presence or absence of repelling of 0.2 mmφ or more was examined. The state without repelling was defined as “good”, and the state with repelling was defined as “bad”.

Moreover, the following base material was used as a test base material.
(Base material having first conductive electrode)
Polyimide flexible substrate with copper foil (Ni-plated gold with 200μm pitch on copper foil)
(Base material having second conductive electrode)
Base material (300Ω / sheet resistance) on which an ITO electrode is formed on a PET film / Example 1
Base material on which ITO electrode is formed on PC film (300Ω / sheet resistance) / Example 2

The base material having the first conductive electrode and the base material having the second conductive electrode were joined using the film-like anisotropic conductive adhesive obtained as described above.
Bonding is performed by attaching a film-like anisotropic conductive adhesive to the base material having the second conductive electrode, and 130 ° C., 30 seconds, 0 from the flexible base material side having the first conductive electrode. It was carried out by applying pressure and heating with a 1.5 mm head at 5 MPa.

With respect to the joined body thus obtained, the initial connection resistance value, connection reliability (resistance value after leaving at 85 ° C. and 85% humidity for 200 hours), and initial adhesive strength (at a speed of 100 mm / min in the direction of 90 degrees with respect to the substrate). The strength at the time of peeling) and the adhesive strength after the connection reliability test were measured.
The initial connection resistance value was measured by a 4-terminal method using a Hioki 9455 type multimeter. In the measurement, the resistance of a pair of copper foils on the polyimide side was measured by a four-terminal method. The results are shown in Table 2.
In the evaluation of the initial connection resistance value, 50Ω or less was evaluated as “good”, and the value exceeding it was determined as “bad”.
The connection reliability was evaluated as “good” when 100Ω or less, and “bad” when exceeding it.
In addition, in the evaluation of the adhesion strength after the initial stage and the connection reliability test, the initial 700 gf / cm or more was regarded as “good”, and the less than 700 gf / cm was regarded as “bad”.

<Comparative Examples 1 and 2>
Compositions 3 and 4 were prepared at the ratios shown in Table 1, applied onto a PET film using a bar coater, and dried in air at 60 ° C. for 10 minutes. A film-like anisotropic conductive adhesive having a thickness of 25 μm was obtained.
The following base materials were used as test base materials.
(Base material having first conductive electrode)
Polyimide flexible substrate with copper foil (Ni-plated gold with 200μm pitch on copper foil)
(Base material having second conductive electrode)
Base material on which ITO electrode is formed on PET film (300Ω / sheet resistance) / Comparative Example 1
Base material on which ITO electrode is formed on PC film (300Ω / sheet resistance) / Comparative Example 2
In the same manner as in Example 1, the base material having the first conductive electrode and the base material having the second conductive electrode were joined, and the obtained joined body was evaluated in the same manner as in Example 1. It was.
The results are shown in Table 2.

<Examples 3 and 4>
Compositions 5 and 6 were prepared at a ratio shown in Table 3 to obtain a conductive adhesive.
The following base materials were used as test base materials.
(Base material having first conductive electrode)
Chip Condenser / Example 3
IC (Gold Stud Bump) / Example 4
(Base material having second conductive electrode)
Base material (300Ω / sheet resistance) on which an ITO electrode is formed on a PET film / Example 3
Base material on which ITO electrode is formed on PC film (300Ω / sheet resistance) / Example 4

For joining, a conductive adhesive is applied to a base material having a second conductive electrode, and the above flexible base material side, which is the base material having the first conductive electrode, is operated at 130 ° C., 60 seconds, 0.5 MPa at 1. MPa. It was performed by heating with pressure with a 5 mm width head.
The joined body thus obtained was tested in the same manner as in Example 1 and evaluated according to the evaluation criteria described below. The results are shown in Table 4.

As the conductive adhesive evaluation criteria, a connection resistance value of 1Ω or less is “good”, and if it exceeds 1Ω, it is “bad”, and a resistance value after connection reliability is 10Ω or less is “good” and exceeds 10Ω. The case was determined as “bad”. In addition, the initial adhesive strength of the capacitor and IC was measured by measuring the shear strength from the lateral direction, and “good” when the load was 1 kg or more and “bad” when the load was less than 1 kg. As for the post-reliability adhesive strength, a load of 0.7 kg or more was “good”, and a load less than 0.7 kg was “bad”.
The numerical value about each component of the composition in Table 1 and Table 3 is volume%.
The numerical values (%) for the curing agent (c) in Tables 1 and 3 are based on the total volume of the epoxy-modified silicone oil (a), the epoxy resin (b), and the phenoxy resin (c) being 100%. The volume% of the curing agent (d) is shown.
The numerical values (%) for the conductive particles (e) and others (f) are the total volume of the epoxy-modified silicone oil (a), the epoxy resin (b), the phenoxy resin (c), and the curing agent (d). The volume% of the conductive particles (e) is shown with 100%.

  The adhesive of the present invention can be mounted on a flexible display, electronic paper, wearable display, organic EL, liquid crystal panel, IC flip chip mounting (COF), etc. at low temperature and with high adhesive force.

Claims (8)

  An adhesive comprising an epoxy-modified silicone oil, an epoxy resin other than the epoxy-modified silicone oil, and a curing agent.   The adhesive according to claim 1, further comprising conductive particles.   The adhesive according to claim 2, wherein the conductive particles are conductive particles having an average particle diameter of 1 μm to 20 μm.   The adhesive according to any one of claims 1 to 3, wherein the curing agent is a latent curing agent.   The conductive particles are contained in an amount of 0.1% by volume to less than 30% by volume with respect to a total of 100% by volume of the resin component and the curing agent component of the adhesive, and can exhibit anisotropic conductivity. 5. The adhesive according to any one of 4.   The adhesive according to any one of claims 2 to 4, wherein the conductive particles are contained in an amount of 30% by volume to 80% by volume with respect to a total of 100% by volume of the resin component and the curing agent component of the adhesive. Agent.   A method for producing a joined body, comprising placing the adhesive according to claim 5 or 6 on a substrate having a conductive electrode or a conductive electrode, and thermocompression bonding the electronic component.   The joined body which consists of the base material or conductive electrode which has a conductive electrode manufactured by the manufacturing method of Claim 7, and an electronic component.