WO2019151187A1

WO2019151187A1 - Conductive adhesive composition

Info

Publication number: WO2019151187A1
Application number: PCT/JP2019/002762
Authority: WO
Inventors: 章郎高橋
Original assignee: タツタ電線株式会社
Priority date: 2018-01-30
Filing date: 2019-01-28
Publication date: 2019-08-08
Also published as: JP6805190B2; TW201936846A; JP2019131674A

Abstract

Provided is a conductive adhesive composition that is capable of being worked at no more than 120°C and has both isotropic conductivity and excellent adhesion properties. The conductive adhesive composition contains 50–300 parts by mass of a dendrite-shaped conductive filler, relative to 100 parts by mass of a resin component containing at least 60 parts by mass of a crystalline thermoplastic resin (A) having a melting point of at least 100°C.

Description

Conductive adhesive composition

The present invention relates to a conductive adhesive composition.

As a means for electrically connecting the electronic component and the substrate, use of a conductive adhesive composition in which a conductive filler is dispersed can be mentioned. As such a conductive adhesive composition, for example, in Patent Document 1, a thermoplastic resin composition having excellent mechanical strength and heat resistance, and excellent electrical properties such as conductivity and antistatic properties. The specific surface area of amorphous thermoplastic resin (component A), crystalline thermoplastic resin (component B), conductive carbon black (component C), and conductive carbon black of component C A thermoplastic resin composition comprising a large conductive carbon black or hollow carbon fibril is described.

However, there is a need for a conductive adhesive composition capable of obtaining isotropic conductivity depending on the application. However, the conductivity of the thermoplastic resin composition described in Patent Document 1 is anisotropic and isotropic. Therefore, if the conductive filler is highly blended, the adhesiveness may be impaired.

In recent years, conductive adhesive compositions used for connecting heat-sensitive members such as electronic parts, for example, electrodes of piezoelectric films, are required to be capable of processing at low temperatures, particularly at temperatures of 120 ° C. or lower. Has been. In response to such a problem, Patent Document 2 discloses an anisotropic conductive film for anisotropically conductively connecting a terminal of a first electronic component and a terminal of a second electronic component, and a film-forming resin and An anisotropic conductive film containing a curable resin, a curing agent, and conductive particles, wherein the film-forming resin contains a crystalline resin and an amorphous resin is disclosed. Patent Document 3 discloses an anisotropic conductive film for anisotropically connecting a terminal of a first electronic component and a terminal of a second electronic component, which includes a crystalline resin, an amorphous resin, An anisotropic particle containing conductive particles, wherein the crystalline resin contains a crystalline resin having the same bond characterizing the resin as the bond characterizing the resin of the amorphous resin. An electrically conductive film is disclosed. However, both are anisotropic conductive films.

Patent Document 4 discloses an adhesive composition comprising (a) a crystalline polyester resin having a melting point of 40 ° C. to 80 ° C., (b) a radical polymerizable compound, and (c) a radical polymerization initiator. Is disclosed, and in order to impart conductivity or anisotropic conductivity, it is disclosed that (f) conductive particles can be further included.

However, as described above, in order to obtain isotropic conductivity, it is necessary to add a high amount of conductive filler, and there is room for further improvement in compatibility between adhesiveness and isotropic conductivity.

JP 2003-96317 A JP 2014-102943 A JP 2014-60025 A International Publication No. 2009/038190

The present invention has been made in view of the above, and can provide a conductive adhesive composition that can be processed at a low temperature of 120 ° C. or lower and has isotropic conductivity and excellent adhesiveness. Objective.

In order to solve the above-mentioned problems, the conductive adhesive composition of the present invention has (A) dendrites with respect to 100 parts by mass of a resin component containing 60 parts by mass or more of a crystalline thermoplastic resin having a melting point of 100 ° C. or higher. The shaped conductive filler is contained in an amount of 50 to 300 parts by mass.

The resin component may contain (B) an amorphous thermoplastic resin.

The crystalline thermoplastic resin (A) is preferably a crystalline polyester, and the amorphous thermoplastic resin (B) is preferably an amorphous polyester.

The conductive filler is one or more selected from the group consisting of copper particles, silver particles, gold particles, nickel particles, silver-coated copper particles, silver-coated copper alloy particles, and silver-coated nickel particles. It can be.

The glass transition point of the amorphous thermoplastic resin (B) may be 50 to 120 ° C.

The content ratio ((A) / (B)) of the crystalline thermoplastic resin (A) and the amorphous thermoplastic resin (B) is 60/40 to 100/0 by mass ratio. be able to.

The conductive adhesive composition according to the present invention can be processed at a low temperature of 120 ° C. or lower, and isotropic conductivity and excellent adhesiveness can be obtained.

It is a schematic cross section which shows the sample used for the measurement of 70 degreeC creep strength and tensile shear adhesive strength. Method of measuring the surface resistivity R ₁ is a schematic sectional view for explaining the. It is a schematic cross-sectional view for explaining a method of measuring the connection resistance ratio R _2.

Hereinafter, embodiments of the present invention will be described more specifically.

The conductive adhesive composition according to this embodiment comprises (A) a dendritic conductive filler with respect to 100 parts by mass of a resin component containing 60 parts by mass or more of a crystalline thermoplastic resin having a melting point of 100 ° C. or higher. The content is 50 to 300 parts by mass. The resin component may further contain (B) an amorphous thermoplastic resin from the viewpoint of processability. Here, the crystalline resin is a polymer substance having a crystal part when solidified, and such a crystalline resin is usually heated by differential scanning calorimetry (hereinafter also referred to as “DSC”). The differential scanning calorimetry curve obtained in the process shows a clear endothermic peak, not a stepwise endothermic change. The melting point (Tm) of the crystalline resin means the peak top temperature in the endothermic peak. An amorphous resin is a polymer substance that does not have a crystalline portion when solidified, and such an amorphous resin usually has a differential scanning calorimetry curve obtained during the DSC temperature rising process. It does not show a clear endothermic peak. In the present specification, the differential scanning calorimeter is measured using a differential scanning calorimeter (for example, trade name “DSC220 type” manufactured by Seiko Denshi Kogyo Co., Ltd.). After flowing in at 10 mL / min and holding at 25 ° C., the temperature is raised to 200 ° C. at 10 ° C./min.

Although it does not specifically limit as crystalline thermoplastic resin (A), For example, polyester (PEs), polyethylene (PE), polypropylene (PP), polyamide (PA), polyimide (PI), polycarbonate (PC), polyacetal ( POM), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), and the like. These may be used singly or as a mixture of two or more. Among these, polyester is preferable from the viewpoint of workability at a low temperature of 120 ° C. or lower.

The number average molecular weight of the crystalline thermoplastic resin (A) is not particularly limited, but is preferably 8000 to 30000, and more preferably 10,000 to 25000. When it is 8000 or more and 30000 or less, it becomes an appropriate viscosity and it is easy to form a film such as an electrode of a piezoelectric film. In this specification, the number average molecular weight is determined using gel permeation chromatography (for example, measuring device: “llance HPLC system” manufactured by Waters Corporation, column: “KF-806L” manufactured by shodex), and the solvent is tetrahydrofuran. The value measured by standard polystyrene conversion is used.

The melting point of the crystalline thermoplastic resin (A) is not particularly limited as long as it is 100 ° C. or higher, but is preferably 100 to 140 ° C., more preferably 110 to 140 ° C., and more preferably 110 to 130 ° C. More preferably. It is desirable that the adhesiveness be maintained at 70 ° C. or lower from the usage state of the electronic component and the substrate connected using the conductive adhesive composition according to the present embodiment, and the melting point of the crystalline thermoplastic resin (A) is By being 100 ° C. or higher, creep deformation at 70 ° C. hardly occurs, and excellent adhesiveness is easily obtained. Moreover, by being 140 degrees C or less, even if it melt | dissolves in the organic solvent at room temperature, it is hard to gelatinize and it is easy to obtain the outstanding workability.

Although it does not specifically limit as an amorphous thermoplastic resin (B), For example, polyester (PEs), polyvinyl chloride (PVC), polystyrene (PS), polymethyl methacrylate (PMMA), acrylonitrile butadiene styrene (ABS) , Polycarbonate (PC), polyethersulfone (PES), polyetherimide (PEI), polyamideimide (PAI) and the like. These may be used alone or in combination of two or more. Also good. Among these, polyester is preferable from the viewpoint of workability at a low temperature of 120 ° C. or lower.

The number average molecular weight of the amorphous thermoplastic resin (B) is not particularly limited, but is preferably 10,000 to 30,000, and more preferably 12,000 to 25,000.

The glass transition point (Tg) of the amorphous thermoplastic resin (B) is not particularly limited, but is preferably 50 to 120 ° C, and more preferably 60 to 100 ° C. By being 50 degreeC or more, the outstanding adhesiveness is easy to be obtained, and by being 120 degreeC or less, it is excellent in a softness | flexibility and is easy to apply to uses, such as a film.

Here, in this specification, the glass transition point means the temperature at the inflection point of the differential scanning calorimetry curve obtained by differential scanning calorimetry.

The resin component of the conductive adhesive composition of the present embodiment includes resins other than the crystalline thermoplastic resin (A) and the amorphous thermoplastic resin (B) as long as the object of the present invention is not impaired. It may be included.

The content ratio ((A) / (B)) of the crystalline thermoplastic resin (A) and the amorphous thermoplastic resin (B) is not particularly limited, but is 60/40 to 100/0 by mass ratio. It is preferably 70/30 to 100/0, more preferably 70/30 to 90/10. When the content ratio is within the above range, excellent results are easily obtained in a creep test at 70 ° C. for evaluating adhesiveness.

The content of the conductive filler is 50 to 300 parts by mass, preferably 50 to 250 parts by mass, and more preferably 50 to 200 parts by mass with respect to 100 parts by mass of the resin component. When it is 50 parts by mass or more, isotropic conductivity is easily obtained, and when it is 300 parts by mass or less, both conductivity and adhesiveness are easily achieved.

The conductive filler is not particularly limited as long as it has a dendrite shape, and examples thereof include copper particles, silver particles, gold particles, nickel particles, silver-coated copper particles, silver-coated copper alloy particles, and silver-coated nickel particles. From the viewpoint of conductivity, silver-coated copper particles, silver-coated copper alloy particles, and silver-coated nickel particles are preferable. Here, the dendrite shape means a shape having one or more dendritic protrusions protruding from the particle surface, and the dendritic protrusion may be only a main branch without branching, and a branch portion branches from the main branch. It may be a planar shape or a three-dimensionally grown shape.

The silver-coated copper particles may have copper particles and a silver-containing layer that covers the copper particles, and the silver-coated copper alloy particles include copper alloy particles and a silver-containing layer that covers the copper alloy particles. The silver-coated nickel particles may have nickel particles and a silver-containing layer that covers the nickel particles. Further, the copper alloy particles may have a nickel content of 0.5 to 20% by mass and a zinc content of 1 to 20% by mass. Nickel and zinc are included within the above-described range, and the balance is made of copper, and the balance of copper may contain unavoidable impurities.

The silver coating amount is preferably 1 to 30% by mass and more preferably 3 to 20% by mass in the ratio of silver-coated copper particles, silver-coated copper alloy particles, or silver-coated nickel particles. When the silver coating amount is 1% by mass or more, excellent conductivity is easily obtained, and when the silver coating layer is 30% by mass or less, the cost is lower than that of silver particles while maintaining excellent conductivity. Can be reduced.

The average particle diameter of the conductive filler is not particularly limited, but is preferably 1 to 20 μm, and more preferably 3 to 15 μm. When it is 1 μm or more, excellent dispersibility is easily obtained, and when it is 20 μm or less, excellent conductivity is easily obtained. Here, in this specification, the average particle diameter means a particle diameter (primary particle diameter) at an integrated value of 50% in a particle size distribution obtained by a laser diffraction scattering method.

In the conductive adhesive composition of the present embodiment, silica, urethane beads or the like can be appropriately blended according to the required physical properties to adjust the hardness of the composition. By blending silica, the conductive adhesive composition can be hardened, and by blending urethane beads, the conductive adhesive composition can be softened.

In addition to the above components, the conductive adhesive composition of the present embodiment includes antioxidants, pigments, dyes, tackifier resins, plasticizers, ultraviolet absorbers, anti-oxidants, and the like within a range not impairing the object of the present invention. A foaming agent, a leveling regulator, a filler, a flame retardant, etc. can be mix | blended.

The conductive adhesive composition of the present embodiment can be prepared by kneading according to a conventional method using a commonly used Banbury mixer, kneader, roll, or other mixer.

The conductive adhesive composition of one embodiment can be suitably used as an electrode for a piezoelectric film (piezo film) or as an adhesive for electronic components that are vulnerable to heat.

The conductive adhesive composition of the present embodiment may be formed into a film shape by coating with a desired film thickness on a film made of polyethylene terephthalate or the like that has been subjected to a release treatment, and may be used as a conductive adhesive film. In addition, you may provide a release film in the single side | surface or both surfaces in order to protect a conductive adhesive film.

Examples of the present invention are shown below, but the present invention is not limited to the following examples. In the following, the blending ratio and the like are based on mass unless otherwise specified.

In accordance with the formulation shown in Table 1 below, each component was mixed to prepare a conductive adhesive composition. This was coated on a release-treated polyethylene terephthalate (PET) film (release film 18) to produce a conductive adhesive film having a thickness of 60 μm. Details of the compounds described in the table are as follows, Tm represents a melting point, Tg represents a glass transition point, and Mn represents a number average molecular weight.
Crystalline thermoplastic resin 1: crystalline polyester, Tm = 120 ° C., Mn = 22000
Crystalline thermoplastic resin 2: crystalline polyester, Tm = 95 ° C., Mn = 20000
Crystalline thermoplastic resin 3: crystalline polyester, Tm = 130 ° C., Mn = 20000
Amorphous thermoplastic resin 1: Amorphous polyester, Tg = 65 ° C., Mn = 16000
Amorphous thermoplastic resin 2: Amorphous polyester, Tg = 94 ° C., Mn = 16000
Conductive filler 1: dendritic silver-coated copper particles, average particle diameter of 5 μm, silver coating amount of 10% by mass
Conductive filler 2: spherical, silver-coated copper particles, average particle size of 5 μm

The adhesiveness (70 ° C. creep strength and tensile shear adhesive strength), surface resistivity, and connection resistivity of the obtained conductive adhesive composition were measured, and the results are shown in Table 1. The measuring method is as follows.

-70 degreeC creep strength: Sample 1 which laminated copper foil 12 on PET film 10 via double-sided tape 11, and the aluminum vapor deposition surface of aluminum vapor deposition film 13 on PET film 10 via double-sided tape 11 become the surface Sample 2 laminated in this manner was prepared, and each sample size was cut to 50 mm × 20 mm. Then, the conductive adhesive film 14 having a film thickness of 60 μm made of the conductive adhesive composition obtained above is cut so as to have a size of 20 mm × 5 mm, laminated on the copper foil 12 of the sample 1, and the temperature After press-pressing at 100 ° C. and a pressure of 0.5 MPa for 30 seconds, the release film 18 was peeled off. And as shown in FIG. 1, the aluminum vapor deposition surface of the aluminum vapor deposition film 13 of the sample 2 and the electroconductive adhesive film 14 were adhere | attached, and it connected by press-pressing for 30 seconds at the temperature of 100 degreeC and the pressure of 0.5 MPa. The end of the sample 1 that is not bonded is gripped and suspended in an air oven, and the end of the sample 2 that is not bonded is attached with a weight of 500 ± 2 g, and then heated at 70 ° C. The time until 1 and sample 2 were separated at the bonding site was measured. Those having a time until separation of 500 hours or more were considered excellent in adhesiveness.

-Tensile shear adhesive strength (N / 20 mm): Sample 1 and sample 2 are bonded and connected with a conductive adhesive film 14 in the same manner as the 70 ° C creep strength, and is made by Shimadzu Corporation according to JIS K6850. Using the test “AGS-X50S”, a tensile test was performed at a tensile speed of 200 mm / min, and the maximum load at break was measured. The thing of 60 N / 20mm or more shall be excellent in adhesiveness.

Surface resistivity (Ω / □): As shown in FIG. 2, on the conductive adhesive film 14 produced above, cubic electrodes A and B (electrode area: 1 cm ² (each side = 1 cm), electrodes Surface: gold plating treatment) was placed. The distance between the electrodes A and B at this time was 10 mm. A load of 4.9 N was applied to each electrode in the vertical direction, the resistance value between the AB electrodes was measured by the two-terminal method, and the value 1 minute after the start of measurement was defined as the surface resistivity R ₁ .

-Connection resistivity: The connection resistivity with the aluminum vapor deposition surface and the connection resistivity with the copper foil surface were measured. Specifically, as shown in FIG. 3, an aluminum deposited film 17 in which an aluminum deposited layer 16 is formed on a PET film 10 is prepared, and a conductive film having a film thickness of 60 μm made of the conductive adhesive composition obtained above. The adhesive film 14 was pressed and transferred to the aluminum vapor deposition film 17 at a temperature of 100 ° C. and a pressure of 0.5 MPa for 30 seconds, and the release film 18 was peeled off. And among the cube-shaped electrodes C and D (electrode area: 1 cm ² (each side = 1 cm), electrode surface: gold plating treatment), the electrode C is placed on the conductive adhesive film 14, and the electrode D is deposited on the aluminum vapor deposition film. 17 was mounted. Otherwise, in the same manner as the surface resistivity was measured connection resistance value R ₂ between C-D electrode. Further, the connection resistivity with the copper foil surface was measured in the same manner as described above except that the copper foil was used instead of the aluminum vapor deposited film 17 and the electrode D was placed on the copper foil.

In all cases, Table 1 shows the average values when the measurement atmosphere temperature is room temperature (18 to 28 ° C.) and the number of tests is n = 5. Those having a resistance value of 10Ω / □ or less can be judged to be excellent in conductivity. At this time, it was also evaluated whether the electrical connection was anisotropic or isotropic. For the anisotropic connection, the evaluation of the surface resistivity R ₁ was blank (−).

As shown in Table 1, Examples 1 to 6 were excellent in adhesiveness (70 ° C. creep strength and tensile shear adhesive strength), surface resistivity, and connection resistivity.

In Comparative Example 1, the melting point of the crystalline thermoplastic resin (A) was outside the predetermined range, and the 70 ° C. creep strength was inferior.

In Comparative Examples 2 and 3, the content of the crystalline thermoplastic resin (A) was outside the predetermined range, and both of them were inferior in 70 ° C creep strength.

Comparative Example 4 is an example using a spherical conductive filler, and isotropic conductivity was not obtained. Moreover, the connection resistivity with an aluminum vapor deposition surface and a copper foil surface was inferior.

DESCRIPTION OF SYMBOLS 1 ... Sample 2 ... Sample 10 ... PET film 11 ... Double-sided tape 12 ... Copper foil 13 ... Aluminum vapor deposition film 14 ... Conductive adhesive film 16 ... Aluminum Vapor deposition layer 17 ... Aluminum vapor deposition film 18 ... Releasing films A, B, C, D ... electrodes

Claims

(A) A conductive adhesive composition containing 50 to 300 parts by weight of a dendritic conductive filler with respect to 100 parts by weight of a resin component containing 60 parts by weight or more of a crystalline thermoplastic resin having a melting point of 100 ° C. or higher. object.
The conductive adhesive composition according to claim 1, wherein the resin component contains an amorphous thermoplastic resin (B).
The conductive adhesive composition according to claim 2, wherein the crystalline thermoplastic resin (A) is a crystalline polyester and the amorphous thermoplastic resin (B) is an amorphous polyester.
The conductive filler is one or more selected from the group consisting of copper particles, silver particles, gold particles, nickel particles, silver-coated copper particles, silver-coated copper alloy particles, and silver-coated nickel particles, Item 4. The conductive adhesive composition according to any one of Items 1 to 3.
The conductive adhesive composition according to any one of claims 2 to 4, wherein the amorphous thermoplastic resin (B) has a glass transition point of 50 to 120 ° C.
The content ratio ((A) / (B)) of the crystalline thermoplastic resin (A) and the amorphous thermoplastic resin (B) is 60/40 to 100/0 by mass ratio. 6. The conductive adhesive composition according to any one of 2 to 5.