JPH11185526A - Anisotropic conductive adhesive, electronic circuit parts, and piezoelectric parts, and bonding method for electric parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce vibration inhibiting of a piezoelectric element, perform reliable bonding, and reduce the cost by compounding conductive particles and a flexibility imparting agent in a matrix resin. SOLUTION: A flexibility imparting agent is compounded in a matrix resin of an anisotropic conductive adhesive, the flexibility imparting agent is compounded by 10 to 35 wt.% with a total of components of the anisotropic conductive adhesive being 100 wt.%, and the flexibility imparting agent is preferably made of a rubber or a rubber mixed resin. The matrix resin is a thermosetting resin, and specifically, it is desirably an epoxy resin, an urethane resin or the like. The conductive particles include metal powders, carbon powders, metal plating plastic ball or the like. As summary of samples, an anisotropic conductive adhesive 1 is applied onto a substrate 5 having electrode 5a and 5b by screen printing, a piezoelectric element 3 having electrodes 3a and 3b at its lower part is placed on the anisotropic conductive adhesive 1, and is cured while in pressurization.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an anisotropic conductive adhesive, an electronic circuit component, a piezoelectric component, and a method for bonding electronic components.

[0002]

2. Description of the Related Art Conventionally, when a chip-shaped electronic component, in particular, an electronic component having a vibration region such as a piezoelectric element is mounted on a substrate, the electronic component is controlled so that the vibration is not hindered by the binding force of an adhesive. A component is adhered to a substrate at an electrode portion of the electronic component, and an isotropic conductive adhesive that does not extend to a vibration area is used.

As shown in FIG. 3, a general conventional isotropic conductive adhesive 20 includes an insulating matrix resin having an adhesive force and a state in which the matrix resin is in contact with and electrically connected to each other. And conductive particles (not shown) dispersed so as to keep them.

Electronic component 2 using isotropic conductive adhesive 20
3 is applied to the substrate 28 so that the isotropic conductive adhesive 20 does not protrude between the electrodes 26a and 26b of the electronic component 26 and the electrodes 28a and 28b of the substrate. As described above, the electrode 26a of the electronic component and the electrode 28a of the substrate are connected to the electrode 26b of the electronic component and the electrode 2 of the substrate.
8b are electrically connected to each other via conductive particles in the isotropic conductive adhesive 20.

On the other hand, as shown in FIG. 4, when a chip-shaped electronic component 27 that does not vibrate is mounted on a substrate, the anisotropic conductive adhesive 21 is used to increase the bonding area and strengthen the bonding force. Is used.

A general conventional anisotropic conductive adhesive 21 is:
It is composed of an insulating matrix resin 23 having an adhesive force, and conductive particles 25 dispersed in the matrix resin 23.

To bond the electronic component 27 to the substrate 28 with the anisotropic conductive adhesive 21, the anisotropic conductive adhesive 21 is applied almost entirely between the electronic component 27 and the substrate 28, and
7 electrode 27a and the electrode 28a of the substrate 28 opposed thereto.
This is performed by interposing conductive particles 25 between them and pressing them. At this time, the electrodes 27a, 27b of the electronic component
The electrodes 28a and 28b of the substrate are in contact with the conductive particles 25 and pressed to form the conductive particles 25a which are flattened and electrically connected. In addition, since the conductive particles 25 in the anisotropic conductive adhesive 21 are substantially uniformly dispersed, they do not usually come into contact with each other, and the electrodes 27a and 27b of the electronic component and the electrodes of the substrate that face each other are not normally in contact with each other. There is no electrical connection except for the combination with 28a and 28b. As the conductive particles 25, metal-plated plastic spheres having good dispersibility and dispersion stability with respect to the matrix resin 23 are used.

[0008]

However, the conventional isotropic conductive adhesive 20 and the conventional anisotropic conductive adhesive 21 have the following problems. 1. When the isotropic conductive adhesive 20 is used for mounting the electronic component 26 and the substrate 28, since the bonding area is small,
Poor adhesion. In addition, there is a danger that the isotropic conductive adhesive 20 applied to different portions may protrude and abut, causing a short circuit.

[0009] 2. When the anisotropic conductive adhesive 21 is used for mounting the electronic component 27 composed of the piezoelectric element and the substrate 28, the elastic modulus of the cured matrix resin 23 is high, that is, the matrix resin 23 is hardened. Is restrained, which is a factor that hinders the vibration of the electronic component 27.

[0010] 3. When the electronic component 26 composed of a piezoelectric element and the other electronic component 27 are mounted together on the substrate 28, it is necessary to change the adhesive used. Therefore, the number of steps of bonding the electronic component 27 increases, and the cost increases.

[0011] An object of the present invention is to provide a bonding method that can reduce vibration inhibition of a piezoelectric element and perform bonding with high bonding reliability, even if a piezoelectric element is included in an electronic component to be bonded. An object of the present invention is to provide an anisotropic conductive adhesive that can be downed, and an electronic circuit component, a piezoelectric component, and an electronic component bonding method using the anisotropic conductive adhesive.

[0012]

According to a first aspect of the present invention, there is provided an anisotropic conductive adhesive comprising a matrix resin, conductive particles, and a flexibility-imparting agent.

Further, the anisotropic conductive adhesive of the second invention comprises:
An anisotropic conductive adhesive obtained by dispersing conductive particles in a matrix resin, characterized in that a flexibility imparting agent is blended in the matrix resin.

With such a configuration, the bonding area between the electronic component and the substrate can be increased, and the adhesive strength of the electronic component to the substrate can be increased. In addition, by reducing the elastic modulus of the adhesive itself and giving the adhesive flexibility, the binding force to the electronic component to be bonded can be reduced to some extent. Even if an element is included, the vibration inhibition can be reduced to some extent, and the piezoelectric element and other electronic components can be bonded at one time, so that the cost can be reduced.

[0015] In the anisotropic conductive adhesive according to the third invention, the total of the components of the anisotropic conductive adhesive is 100% by weight.
It is preferable that 10 to 35% by weight of the flexibility-imparting agent is blended.

By using such an amount of the flexibility-imparting agent, the elasticity can be further reduced to give flexibility,
In addition, an anisotropic conductive adhesive having a strong adhesive force can be obtained.

Further, in the anisotropic conductive adhesive according to the fourth invention, the flexibility-imparting agent is made of rubber or a rubber-mixed resin.

By using such a flexibility-imparting agent, the elastic modulus of the anisotropic conductive adhesive can be reduced more effectively.

Further, in the anisotropic conductive adhesive according to the fifth invention, the matrix resin is a thermosetting resin.

By using such a matrix resin, an anisotropic conductive adhesive having higher adhesive strength and more excellent heat resistance can be obtained.

According to a sixth aspect of the present invention, there is provided an electronic circuit component comprising: a substrate having a wiring circuit; an electronic component body having electrodes; and an anisotropic conductive adhesive interposed between the substrate and the electronic component body. Wherein the anisotropically conductive adhesive is the anisotropically conductive adhesive according to any one of claims 1 to 5.

By using such an electronic circuit component, the bonding area between the electronic component body and the substrate can be increased to increase the adhesive strength. In particular, the piezoelectric electronic component main body can be bonded to the substrate together with the other electronic component main bodies using an anisotropic conductive adhesive while minimizing the inhibition of vibration by the adhesive.

The piezoelectric component according to a seventh aspect of the present invention is a piezoelectric component according to the first aspect.
And an anisotropic conductive adhesive according to any one of claims 1 to 5, wherein the adhesive is adhered on the substrate.

With this configuration, it is possible to obtain a piezoelectric component capable of minimizing the inhibition of vibration even when the adhesive strength to the substrate is increased by using an anisotropic conductive adhesive.

According to an eighth aspect of the present invention, there is provided the electronic component bonding method, wherein an anisotropic conductive adhesive comprising a matrix resin, conductive particles, and a flexibility-imparting agent is applied on a substrate. Is pressed against and adhered to the substrate coated with the anisotropic conductive adhesive.

By adopting such an electronic component bonding method, the bonding area between the electronic component and the substrate can be increased, and the adhesive strength of the electronic component to the substrate can be increased. Also, by reducing the elastic modulus of the anisotropic conductive adhesive itself and giving the adhesive flexibility, the binding force to the bonded electronic components can be reduced to some extent. Even if a piezoelectric element is included, the vibration inhibition can be reduced to some extent, and the piezoelectric element and other electronic components can be simultaneously bonded, so that the cost can be reduced.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The anisotropic conductive adhesive of the present invention comprises a matrix resin, conductive particles, and a flexibility-imparting agent.

The matrix resin in the present invention has adhesive strength and can be cured. Specific examples include thermosetting resins such as epoxy resins, silicone resins, urethane resins, phenol resins, and polyimide resins, and thermoplastic resins such as phenoxy resins, polyamide resins, and polyester resins. It is preferable to use a thermosetting resin in terms of properties and the like. More preferably, it is an epoxy resin in view of adhesive strength and environmental resistance.

The conductive particles are for connecting the electrodes of the electronic component and the electrodes of the substrate. Examples of the material include metal powder, carbon powder, metal-plated plastic spheres, etc., which are excellent in heat shock resistance, such as flattening at the time of bonding, expansion and contraction at the time of heat shock, and preventing poor contact between electrodes. It is preferred to use plated plastic spheres. In addition, since it is necessary to abut both electrodes at the time of bonding without contacting each other in a normal state,
The diameter of the conductive particles is preferably 5 to 15 μm, and the amount added is preferably 1 to 10% by volume.

The flexibility-imparting agent is blended with the matrix resin and has an insulating property comparable to that of the matrix resin. Use one that can reduce the rate. Preferably,
Isoprene rubber, butadiene rubber, styrene butadiene rubber, chloroprene rubber, which is more effective in reducing the elastic modulus,
Acrylonitrile butadiene rubber or the like is used alone or as a mixture with a matrix resin. More preferably, it is an acrylonitrile butadiene rubber which forms an appropriate sea-island structure with the matrix resin, has excellent dispersibility, and has little effect on lowering the peak temperature (Tg) of tan δ when added.

Further, the electronic circuit component of the present invention comprises a substrate having a wiring circuit, an electronic component body having electrodes, and an anisotropic conductive adhesive interposed between the substrate and the electronic component body. . Here, the number and shape of the electronic component body are not particularly limited. As the electronic circuit component of the present invention,
For example, a communication circuit, a video circuit, and the like can be given.

The piezoelectric component of the present invention is not particularly limited as long as it has a piezoelectric body. For example, there are a surface acoustic wave device, a piezoelectric vibrator, a filter device, and the like.

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to only these examples.

[0034]

EXAMPLE A method for producing an anisotropic conductive adhesive according to the present invention will be described. First, a bisphenol A type epoxy resin was prepared as a matrix resin. Next, gold-plated plastic spheres having a diameter of 10 μm as conductive particles were added in an amount of 2.0% by volume with respect to all the adhesive components. Next, as the flexibility-imparting agent, epoxy resin and CTBN rubber (carboxy-terminal-modified acrylonitrile-butadiene rubber) were mixed at 50: 5.
0 (weight), and compounded with the matrix resin as rubber or a rubber mixed resin. Further, a microcapsule-type imidazole was added as a curing agent to the matrix resin in an amount of 28% by weight based on the epoxy resin serving as the matrix resin and the epoxy resin component in the flexibility-imparting agent.

Next, the obtained compound was kneaded with a vacuum planetary mixer for 30 minutes to obtain an anisotropic conductive adhesive.

(Example 1) The anisotropic conductive adhesive obtained by changing the blending amount of the flexibility-imparting agent as described above was cast into a mold having a thickness of 1 mm. The plate-like adhesive obtained by curing for 10 minutes was cut into a strip having a width of 10 mm and a length of 50 mm to obtain a sample, and a bending mode was performed at room temperature (25 ° C.) to measure an elastic modulus (Pa). The elastic modulus (P
The equation for obtaining a) is Pa = | E ^* | cosδ (where E ^* :
Complex elastic modulus, δ: loss angle).

Embodiment 2 FIG. 1 is a schematic perspective view of a sample of the second embodiment, and FIG. 2 is a schematic sectional view of the sample of the second embodiment. In addition, the two-dot chain line in FIG. 1 indicates the electrode bonding position of the piezoelectric element. As shown in FIGS. 1 and 2, a predetermined amount of the anisotropic conductive adhesive 1 prepared by the above method is applied on a substrate 5 having two electrodes 5a and 5b by screen printing, and the two electrodes 3a, A piezoelectric element 3 having a length of 5 mm, a width of 1 mm, and a thickness of 0.5 mm having a 3b is bonded to an anisotropic conductive adhesive 1
After the sample is placed on top and cured at 150 ° C for 30 minutes while applying pressure, Loss, which is the loss of vibration generated in the longitudinal direction of the piezoelectric element, and the piezoelectric element in the direction normal to the bonding surface between the piezoelectric element and the substrate The adhesive strength, which is the tensile breaking strength when the element is separated, the resistance between the electrode 3a (3b) of the piezoelectric element and the electrode 5a (5b) of the substrate, the electrode 5a-5b of the substrate
The insulation resistance between them was measured.

Table 1 shows the measurement results of Examples 1 and 2.
Shown in In the table, the symbol な し indicates that there is no problem in practical use, and the symbol △ indicates that the effect is exhibited although the characteristics are not preferable.

[0039]

[Table 1]

As shown in Table 1, it can be confirmed that the elasticity (Pa) of the anisotropic conductive adhesive of the present invention can be reduced by adding a flexibility-imparting agent to the matrix resin. Although the adhesive strength of the adhesive itself can be reduced to some extent by adding a flexibility-imparting agent to the matrix resin, the total adhesive strength for bonding the piezoelectric element to the substrate is small, for example, because the bonding area is small. Compared with the one-sided conductive adhesive, it is considerably stronger.

In claim 3, the amount of the flexibility-imparting agent is limited to 10 to 35% by weight.
When the blending amount of the flexibility-imparting agent is less than 10% by weight, the effect of blending the flexibility-imparting agent appears, but the elastic modulus of the adhesive does not decrease so much and the adhesive becomes soft. Of the piezoelectric element,
This is because ss becomes larger than 2.5 (dB), which is not preferable. On the other hand, when the blending amount of the flexibility-imparting agent is more than 35% by weight as in Sample No. 8, the adhesive strength becomes smaller than 1.0 × 10 ² (gf),
This is because it is not preferable.

[0042]

Since the anisotropic conductive adhesive of the present invention is composed of a matrix resin, conductive particles and a flexibility-imparting agent, the adhesive has a small elastic modulus and a high flexibility. Even if a piezoelectric element is present in the electronic components to be bonded, the adverse effect of the adhesive on the vibration characteristics can be reduced, and the bonding area between the electronic component and the substrate is large, so that the bonding can be performed more firmly. Further, since the piezoelectric element and other electronic components can be simultaneously mounted in one process, the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a sample according to a second embodiment of the present invention.

FIG. 2 is a schematic sectional view of a sample according to a second embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view illustrating a general bonding state of a conventional isotropic conductive adhesive.

FIG. 4 is a schematic sectional view showing a general bonding state of a conventional anisotropic conductive adhesive.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anisotropic conductive adhesive 3 Piezoelectric element (electronic component) 3a, 3b Electrode of piezoelectric element 5 Substrate 5a, 5b Electrode of substrate

Continuation of front page (72) Inventor Koichi Tanaka 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Murata Manufacturing Co., Ltd.

Claims (8)

[Claims] 1. An anisotropic conductive adhesive comprising a matrix resin, conductive particles, and a flexibility-imparting agent. 2. An anisotropic conductive adhesive obtained by dispersing conductive particles in a matrix resin, wherein a flexibility-imparting agent is compounded in the matrix resin. Adhesive. 3. The total of the components of the anisotropic conductive adhesive is 100
The anisotropic conductive adhesive according to claim 1 or 2, wherein 10 to 35% by weight of the flexibility-imparting agent is blended as% by weight. 4. The anisotropic conductive adhesive according to claim 1, wherein the flexibility-imparting agent is made of rubber or a rubber-mixed resin. 5. The anisotropic conductive adhesive according to claim 1, wherein the matrix resin is a thermosetting resin. 6. An electronic circuit component comprising: a substrate having a wiring circuit; an electronic component main body having electrodes; and an anisotropic conductive adhesive interposed between the substrate and the electronic component main body. The electronic circuit component according to claim 1, wherein the anisotropic conductive adhesive is the anisotropic conductive adhesive according to claim 1. 7. A piezoelectric component bonded to a substrate by the anisotropic conductive adhesive according to claim 1. Description: 8. An anisotropic conductive adhesive comprising a matrix resin, conductive particles, and a flexibility-imparting agent applied on a substrate, and an electronic component is coated with the anisotropic conductive adhesive. A method of bonding an electronic component using an anisotropic conductive adhesive, which is performed by pressing and bonding to a substrate.