JPH06200227A - Epoxy resin adhesive - Google Patents

Abstract

PURPOSE:To obtain an epoxy resin adhesive which is capable of short-time curing and has good storage stability. CONSTITUTION:This adhesive comprises an epoxy resin, a reactional product of an epoxy resin with a prim. amine and/or a sec. amine, and zeolite.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin adhesive which can be cured at a relatively low temperature for a short time and has good storage stability, and particularly to fix a chip component such as a resistor or a capacitor to a printed circuit board. The present invention relates to an epoxy resin adhesive suitable for.

[0002]

2. Description of the Related Art Conventionally, an ultraviolet curable acrylic adhesive has been used as an adhesive for fixing chip components such as chip resistors and chip capacitors or surface mounting LSIs and ICs such as QFP and SOP on a printed circuit board. Has been used. The UV-curable adhesive was an excellent adhesive suitable for line production because it can be cured in a short time of a few seconds to a few tens of seconds by irradiation with ultraviolet rays. As a result, the UV lamp does not reach the adhesive when it enters the shade of the IC, and the adhesive may not be sufficiently cured.

[0003]

As one of the methods for solving this problem, a heat-curing type epoxy adhesive has come to be used. In this case, in line production, since the adhesive also needs to be heat-cured at the same speed as the ultraviolet-curing adhesive, the addition reaction product of the epoxy compound and the primary or secondary amine can be cured at a speed higher than that of the ultraviolet-curing adhesive. It is used as a curing agent for large epoxy resins. However, the heat-curing type epoxy adhesive compounded with this curing agent has a drawback that storage stability is extremely poor.

The present invention solves the above-mentioned conventional problems and provides an epoxy resin adhesive satisfying both fast curing property and storage stability.

[0005]

The present inventors have completed the present invention as a result of intensive studies to solve the above problems. That is, the present invention includes (A) epoxy resin, (B) 1
A reaction product of an epoxy compound having one or more epoxy groups in the molecule with a primary amine and / or a secondary amine (hereinafter referred to as "epoxy amine adduct");
And (C) an epoxy resin adhesive composed of zeolite.

The epoxy resin adhesive of the present invention will be described in detail below.

The component (A) used in the present invention is preferably an epoxy resin having two or more epoxy groups in one molecule, and conventionally known ones can be used. Examples of this are bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin and bromide thereof, and further hydrogenated bisphenol A type epoxy resin, alicyclic epoxy resin, urethane. Examples thereof include a modified epoxy resin, a glycidyl ester type epoxy resin of fatty acid, or a glycidyl ether type epoxy resin of polyethylene glycol or polypropylene glycol. These epoxy resins can be used alone or in combination of two or more. Among these epoxy resins, those which are liquid at room temperature are preferable, and among them, bisphenol A type epoxy resins or bisphenol F type epoxy resins which are liquid at room temperature are most preferable because they have excellent adhesive strength.

On the other hand, it is desired that the adhesive for fixing the chip component has a low spinnability so that it can be applied at a high speed. For that purpose, the viscosity of the resin can be reduced. The preferred viscosity range for this is the B-type viscometer (rotor No.
800 cp when measured at 2, 12 rpm, 25 ° C)
s or less. Since it is difficult to realize this viscosity range by the compound having two or more epoxy groups in one molecule alone, it is relatively low molecular weight compound having one epoxy group in one molecule in addition to the compound ( Hereinafter, this viscosity range can be easily achieved by using "reactive diluent" together. That is, the component (A) epoxy resin used in the present invention is preferably a combination of a compound having two or more epoxy groups in one molecule and a reactive diluent.

Examples of reactive diluents are aromatic glycidyl ethers such as phenyl glycidyl ether or cresyl glycidyl ether; alkyls such as ethyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether or higher alcohol glycidyl ether. Glycidyl ether; butylphenyl glycidyl ether, allyl glycidyl ether, glycidyl ester of versatic acid and the like can be mentioned. Among these reactive diluents, those having good compatibility with the component (B) described later are not preferable because they reduce the storage stability of the adhesive, and the reactive diluent dissolves most of the component (B). Preferred is an alkyl glycidyl ether having 3 or more carbon atoms, an alkylphenyl glycidyl ether having 3 or more carbon atoms, or a glycidyl ester of versatic acid.

Next, the epoxy amine adduct of component (B) acts as a curing agent for the epoxy resin. As the primary amine and / or the secondary amine,
2-ethyl-4-methylimidazole, 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2
-Imidazoles such as isopropylimidazole; N-
Piperazine compounds such as methylpiperazine; amine compounds such as 2-dimethylaminoethylamine and 3-dimethylamino-N-propylamine; amine compound such as organic acid hydrazides such as adipic acid dihydrazide and isophthalic acid dihydrazide. First having amine in the molecule
An amine or / and a secondary amine compound is preferable because the adhesive has a fast curing property. An epoxy compound having a relatively large molecular weight and solid at room temperature, such as a novolac type epoxy resin, a bisphenol A type epoxy resin or a bisphenol F type epoxy resin, and an epoxy compound having one or more epoxy groups in one molecule, and the amine compound. The curing agent of the component (B) of the present invention can be obtained by reacting at a melting point of not less than. A preferable ratio of both is 0.5% for an epoxy compound having one or more epoxy groups in one molecule with respect to 100% by weight of a primary amine and / or a secondary amine.
To about 10.0% by weight.

Examples of commercially available epoxy amine adducts include Novacure under the trade name of Asahi Kasei Kogyo Co., Ltd. and Amicure under the trade name of Ajinomoto Co., Inc.

According to the present invention, the above epoxy resin (A) and curing agent (B) are mixed with zeolite as the component (C). Zeolites are minerals with unique adsorption properties, and their components are hydrous metal salts of alumina and silicate. It is known that a part of crystal water is removed by drying or heating the metal salt, and molecules to be adsorbed into the cavities to exert an adsorbing property of water, a polar solvent and the like. Synthetic zeolite is commercially available under the name of molecular sieve and widely used as an adsorbent that utilizes this property.

The zeolite that can be used in the present invention may be either a natural product or a synthetic product, and the average particle size thereof is 40 so that it is uniformly dispersed in the resin and the nozzles are not clogged.
It is preferably at most μm, more preferably at most 10 μm.

The adhesive according to the present invention basically comprises the above-mentioned components (A), (B) and (C), but in addition to this, an inorganic filler other than zeolite, a thixotropy imparting agent, Additives such as foaming agents, dyes and pigments can be added.

The inorganic filler is the viscosity of the adhesive or paint,
Titanium oxide, zinc white, talc, clay, silica, etc., which are commonly used to improve thixotropy, heat resistance, etc., can be used. The average particle size is preferably 10 μm or less so as not to be clogged.

A high thixotropy is required for the adhesive for fixing the chip parts of the printed wiring board. In that case, it is preferable to add a thixotropy imparting agent. As the thixotropy-imparting agent, colloidal silica, alumina, or silica, whiskers of potassium titanate, scaly mica, powdered asbestos and the like are common, but the spinnability of the adhesive so that liquid does not drip from the nozzle. The organically modified bentonite is most preferable for eliminating the above.

The preferred blending ratio of each component is as follows. (A) component and (B) in the adhesive of the present invention
The proportion of the components is preferably 5 to 25% by weight, more preferably 15 to 20% by weight, based on the total amount thereof. If it is less than 5 parts by weight, the curing will be slow, and if it exceeds 25 parts by weight, the storage stability tends to be poor, both of which are not preferable. The zeolite as the component (C) preferably accounts for 1 to 20% by volume in the epoxy resin adhesive of the present invention, and more preferably 2 to 20% by volume. If it is less than 1% by volume, the storage stability becomes poor, which is not preferable. When zeolite is used in combination with other inorganic fillers, it is preferable that the zeolite accounts for 10% by volume or more. The total amount of zeolite and other inorganic filler is 10 to 2 based on the total amount of the epoxy resin adhesive of the present invention.
0% by volume is preferable, and 12 to 18% by volume is more preferable.
Is. If it is less than 10% by volume, the shape when the adhesive is applied in dots will have a small height / diameter ratio, and if it exceeds 20% by volume, the height / diameter ratio will be too large.
None of them is preferable for fixing chip parts.
The amount of the thixotropy-imparting agent added is 0.2 to 100 parts by weight based on the total amount of the components (A) and (B).
3.0 parts by weight is preferred.

[0018]

The epoxy resin adhesive according to the present invention has a fast curing rate, excellent adhesiveness and storage stability, and excellent applicability by a dispenser. The reason why the adhesive is excellent in rapid curing property and good in storage stability is presumed as follows. Conventionally, an adhesive using a curing agent based on an epoxy-amine adduct has not been so good in storage stability, and especially when a large amount of a curing agent is added to the epoxy resin in order to obtain fast curing, it is extremely difficult to do. The storage stability was poor, probably due to the water in the adhesive acting as an accelerator. Generally, amine-based curing agents easily absorb moisture, and inorganic fillers such as talc that are often used in adhesives contain about 0.2% by weight of water.
On the other hand, the zeolite added to the adhesive in the present invention,
It is presumed that the quick curing property and the storage stability were compatible because the water content in the adhesive was absorbed.

[0019]

EXAMPLES The present invention will be described below with reference to examples.

Example 1 As an epoxy resin, a bisphenol A type epoxy resin (Epicote 828 manufactured by Yuka Shell Epoxy Co., Ltd.) 5
5.5 parts by weight, butylphenyl glycidyl ether as a reactive diluent (YED- manufactured by Yuka Shell Epoxy Co., Ltd.)
122) 27.8 parts by weight, epoxy amine adduct body as a curing agent (PN-23 manufactured by Ajinomoto Co., Inc.) 16.7
Parts by weight, 1 part by weight of organically modified bentonite as a thixotropy-imparting agent and 0.3 parts by weight of a red pigment, 11.2% by volume of talc as an inorganic filler (total amount of epoxy resin adhesive, the same applies hereinafter) and synthetic zeolite (union. 3.4 volume% of molecular sieve 3A manufactured by Showa KK (particle size 10 μm or less) was mixed, and solid particles were uniformly dispersed in the resin using a triple roll to prepare an epoxy resin adhesive.

Examples 2 to 6 and Comparative Example 1 Under the conditions shown in Table 1, the same steps as in Example 1 were carried out.
An epoxy resin adhesive for fixing chip parts was prepared. These adhesives were evaluated for the following items. The evaluation results are shown in Table 1.

Storage stability The prepared adhesive was placed in a polypropylene container and
Stored in oven at 0 ° C. After 15 days, take out the adhesive and measure the viscosity of the adhesive, and gel the gel or increase the viscosity so that it cannot be measured, x, and increase the viscosity to twice or more immediately after production. Those that were less than twice were rated as ◯.

Spinnability A glass epoxy substrate (FR-4) on which a solder resist is printed and cured on the entire surface is used with a dispenser, and the adhesive is 0.15 mg per point and the coating speed is 50 ms per point.
A continuous 1000-point coating test was conducted with ec, and if there was even one stain on the substrate due to the spinnability, x was marked, and if there was no stain, it was marked with ◯.

Application Shape The shape of the adhesive applied in the above evaluation of the spinnability is a cone, and the diameter D of the bottom of the cone and the height H of the cone are used.
Was observed and measured with a microscope. When the height / diameter ratio H / D was 0.5 or less, the value was x, when the ratio H / D was 0.5 to 1.5, the value was ◯, and when it was 1.5 or more, the value was Δ.

Adhesiveness Similar to the evaluation of spinnability, a solder resist is printed on the surface,
A 2125 resistor chip was adhered to a cured glass epoxy substrate, and the force required to peel off one chip was measured with a push-pull gauge. Adhesive is chip 1
0.3 mg was applied per piece, and the adhesive was cured by heating in an oven at 150 ° C. for 3 minutes.

Gel time A time (second) until 0.3 ± 0.05 g of the adhesive is heated on a hot plate of 150 ° C. and the fluidized state disappears and gelation occurs.
Was measured.

[0027]

[Table 1]

[0028]

Industrial Applicability The epoxy resin adhesive of the present invention is an adhesive that cures quickly and has good storage stability, and is particularly excellent in coatability and adhesiveness for fixing chip parts.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiroshi Nakajima 1-1 Funami-cho, Minato-ku, Nagoya, Aichi Prefecture Toagosei Chemical Industry Co., Ltd. Nagoya Research Institute

Claims (1)

[Claims] 1. An epoxy resin adhesive comprising (A) an epoxy resin, (B) an epoxy compound and a reaction product of a primary amine and / or a secondary amine, and (C) a zeolite.