JPH047383A - Adhesive for use in electronic part and mounting of electronic part - Google Patents

Abstract

PURPOSE:To provide an adhesive for use in electronic parts which has rapidly curing characteristics, good adhesiveness and good heat resistance by compounding a polyamide or a polyimide comprising o-phthalic acid and diethylenetriamine with a resin having photo-setting and thermosetting properties. CONSTITUTION:A resin having a photo-setting functional group (e.g. methoxyethyl acrylate prepolymer) and a resin having a thermosetting functional group (e.g. bisphenol A-based epoxy resin) are mixed to prepare a chief material having photo-setting and thermosetting properties. Then, a polyamide or a polyimide comprising o-phthalic acid and diethylenetriamine are compounded as the curing agent with the chief material to prepare an adhesive for use in electronic parts. The adhesive is suitably used as an adhesive for fixing temporarily the electronic parts onto a printed circuit board in soldering the electronic parts onto the printed circuit board.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an adhesive for electronic components used for temporarily fixing electronic components to a printed circuit board, and an electronic component mounting method using the same.

Conventional technology The applicant used an adhesive for electronic components in which the adhesive had not only photocurability but also thermosetting properties in previously filed Japanese Patent Application No. 1-7219. We also proposed a method to keep the degree of photocurability constant regardless of variations in the ability of the light irradiation equipment.

This method involves adding a long-chain saturated fatty acid amide to an adhesive to retard the photocurability of the adhesive, thereby expanding the range of effective adhesive strength that the adhesive exhibits upon irradiation with light.

Problems to be Solved by the Invention In such prior art, since the curing time of the adhesive is slow, when reflow soldering electronic components to both sides of a printed circuit board, cream solder is first printed on one side of the printed circuit board. After that, the adhesive is applied, the adhesive is irradiated with light to thicken it, electronic components are mounted on the adhesive and heated, and the cream solder is melted and soldered. The other side of the printed circuit board had to be soldered in a similar manner, and there was room for improvement in terms of workability and productivity.

Furthermore, when electronic components are mounted on a printed circuit board by jet soldering, there is also the problem that the electronic components come off.

This invention solves the problems in the prior art, and provides a method for electronic components that has high workability and productivity and allows simultaneous reflow soldering and jet soldering of electronic components to both sides of a printed circuit board. The purpose is to provide adhesives and electronic component mounting methods.

Means for Solving the Problems In order to achieve the above object, the present invention includes a photocurable and thermosetting adhesive containing polyamide and imide made of 0-phthalic acid and diethylenetriamine. It is something.

The invention also uses such an adhesive to simultaneously reflow solder electronic components to both sides of a printed circuit board.

The adhesive for electronic components according to the present invention has photocurability and thermocurability. That is, the resin that is the main material has a photocurable functional group and a thermosetting functional group. In this invention, since it is necessary that thermosetting properties remain after the light irradiation is completed, a resin having a photocurable functional group and a resin having a thermosetting functional group are used together.

Examples of the resin having a photocurable functional group (photocurable resin) include, but are not limited to, ultraviolet curable monofunctional and polyfunctional (meth)acrylate monomers and oligomer prepolymers.

As the monofunctional (meth)acrylate, for example, those shown below can be used.

Methoxyethyl (meth)acrylate.

Methoxypropyl (meth)acrylate.

Ethoxypropyl (meth)acrylate.

Ethoxypropyl (meth)acrylate.

Butoxyethyl (meth)acrylate.

Butoxypropyl (meth)acrylate.

Phenoxyethyl (meth)allylate.

Phenoxypropyl (meth)acrylate.

Nonylphenoxyethyl (meth)acrylate.

Nonylphenoxypropyl (meth)acrylate.

Benzoyloxyethyl (meth)acrylate.

Phenoxydiethylene glycol (meth)acrylate −
to .

2-Hydroxy-3-phenoxypropyl (meth)acrylate.

Tetrahydrofurfuryl alcohol and ε-caprolactone adduct (meth)acrylate.

Dicyclopentenyloxyethyl (meth)acrylate.

As the (meth)acrylate having bifunctionality or higher (polyfunctionality), for example, those shown below can be used.

Polyethylene glycol di(meth)acrylate.

Polypropylene glycol di(meth)acrylate.

Neopentyl glycol di(meth)acrylate.

1.6-hexadiol di(meth)acrylate.

Trimethylolpropane tri(meth)acrylate.

Pentaerythritol tri(meth)acrylate.

Dipentaerythritol hexa(meth)acrylate −
to .

1.4-butanediol di(meth)acrylate.

Allyl (meth)acrylate.

Hydroxypivalic acid neopentyl glycol di(meth)acrylate.

Acetal glycol di(meth)acrylate.

Trimethylolpropane and propylene oxide adduct tri(meth)acrylate.

A photosensitizer may be added to the photocurable resin, if necessary.

As the resin having a thermosetting functional group (thermosetting resin), a resin having a glycidyl group is used. Specifically, it is an epoxy resin such as bisphenol A type epoxy resin.

In the adhesive for electronic parts according to the present invention, polyamide and imide made of 0-phthalic acid and diethylenetriamine are added as a curing agent for the epoxy resin to such a main material.

The adhesive for electronic parts according to the present invention may contain, in addition to the above, a photopolymerization initiator, a long-chain aliphatic polyamide polymerization inhibitor, a filler, a pigment, a thixotropic agent, as long as the performance is not changed as necessary. Dispersants, anti-aging agents, surfactants, etc. can be added. Here, the filler is calcium carbonate, talc, etc. Although any surfactant may be used as the surfactant, polyether-based surfactants are preferred. Although any pigment may be used, a red pigment is preferable.

The composition of the adhesive for electronic components according to the present invention is not particularly limited, but is, for example, as follows.

1. Total of monofunctional acrylic monomer, oligomer prepolymer, and monofunctional methacrylic monomer oligomer, prepolymer; 10 to 60 parts by weight.

2. Total of the polyfunctional acrylic yarn top, oligomer prepolymer, and polyfunctional methacrylic monomer oligomer and prepolymer: 0.01 to 10 parts by weight.

3. Epoxy resin; 30 to 80 parts by weight.

4. Hardening agent for epoxy resin - 0.1 to 40 parts by weight.

5. Long chain saturated fatty acid amide; 1 to 20 parts by weight.

6. Photopolymerization initiator, photosensitizer, polymerization inhibitor, organic peracid compound, filler, pigment, chicken-like agent, dispersant, anti-aging agent, surfactant, etc. - appropriate amounts.

If the working adhesive has thermosetting properties in addition to photocuring properties, photocuring has occurred at the end of light irradiation, but thermal curing has not occurred. Therefore, since the resin is not completely cured, the adhesive can thicken quickly enough to temporarily fix electronic components.

When polyamide and imide consisting of O-phthalic acid and diethylenetriamine are used as the curing agent for the epoxy resin in this adhesive, the curing speed is fast (as well as
It becomes possible to introduce a benzene ring into the main chain, improving adhesive strength and heat resistance.

Therefore, electronic components can be reflow soldered to both sides of the printed circuit board at the same time, and jet soldering is also possible.

EXAMPLES The present invention will be specifically explained below with reference to Examples and Comparative Examples.

Adhesive strength and curing time were measured for simultaneous reflow soldering on both sides and jet soldering using the following methods.

(1) Adhesive strength In accordance with J I 5K6850, use an aluminum piece, apply adhesive to the casing, and then apply an ultraviolet curing mercury lamp (80w/
An ultraviolet ray was irradiated for 1 second at a position of 10 crn below the lamp, and the sheets were bonded together and cured by heating in an oven at 150° C. for 10 minutes. Using this test piece, the tensile shear adhesive strength was measured.

(2) Curing time: Apply approximately 20μ of adhesive on a hot plate heated to 150℃! Complete curing was confirmed by dripping and stylus, and the time was measured.

(3) Simultaneous reflow soldering on both sides Apply 100% adhesive to the printed circuit board after printing cream solder.
Apply dots (0,5 cm/dot) and use a mercury lamp for UV curing (
Ultraviolet rays were irradiated for 1 second at the 10-point position under an 80 W/AN lamp, and electronic components of 3216 chip resistance were mounted, heated in a reflow oven with the electronic component mounting side facing downward, and soldered.

At that time, we counted the number of electronic components that were soldered without adhering to the board or those that had fallen.

(4) For jet soldering, apply 100 points (0.5 cm/point) of adhesive to the printed circuit board and use a mercury lamp for UV curing (80w/an).
Ultraviolet rays were irradiated for 1 second at a position 10 An below the lamp to perform jet soldering. At that time, the number of electronic components that had fallen was counted.

Adhesives of Examples and Comparative Examples were prepared according to the formulations in Tables 1A and 1B, and the adhesive strength, curing time, double-sided reflow soldering properties, and jet soldering properties were measured using the methods described above. The measurement results are shown in the lower columns of Tables 1A and 1B.

Note that the specific names of each component are as follows.

Monoacrylate A: Phenoxyethyl acrylate Monoacrylate B: Nonylphenoxypropyl acrylate Diacrylate A: 1.6-hexanesiol diacrylate Diacrylate B: Neopentyl glycol diacrylate Epoxy A: Bisphenol A type epoxy resin Epoxy B : Bisphenol F type epoxy resin epoxy curing agent A
polyamide and imide epoxy curing agent B consisting of go-phthalic acid and diethylenetriamine, 2-methylimidazole epoxy curing agent C dicyandiamide photoinitiator: benzyl cimethyl ketal Examples 1 to 3 are used to cure epoxy resins and epoxy resins. This is a case where the amount of the agent added is changed.

Example 4 is a case where the type of epoxy resin was changed from Examples 1 to 1.

In Examples 5 to 7, the types of monoacrylate and diacrylate were changed without changing the blending amounts of the epoxy resin and its curing agent.

In Examples 1 to 7, polyamide and imide made of 0-phthalic acid and diethylenetriamine were used as curing agents, and the adhesive strength, curing time, simultaneous reflow on both sides,
Jet soldering is superior in terms of performance.

In Comparative Example 1.2, the curing agent of the epoxy resin was changed from that of the Example.

In Comparative Example 1, the adhesive strength was weak, and the properties of simultaneous reflow soldering on both sides and jet soldering were poor.

Comparative Example 2 has strong adhesive strength but takes a long time to cure.

When reflow soldering electronic components to both sides of a printed circuit board at the same time using adhesives such as those shown in Table 1A, Table 1B, and Table 2, first print cream solder on both sides of the printed circuit board, and then apply the adhesive on top of it. The adhesive is irradiated with light to thicken it, the electronic components are glued on top of it and temporarily fixed, and the printed circuit board is placed in a reflow oven and heated to melt the cream solder. Solder.

Effects of the Invention As described above, the adhesive for electronic components according to the present invention has fast curing properties and strong adhesive strength and heat resistance, so it can be used to temporarily fix electronic components to printed circuit boards. No parts come off, and workability and productivity are further improved.

Furthermore, since it has strong adhesive strength and heat resistance, electronic components can be reflow soldered to both sides of a printed circuit board at the same time, and jet soldering is also possible.

Claims (2)

[Claims] (1) An adhesive for electronic components that has photocurability and thermosetting properties and contains polyamide and imide made of O-phthalic acid and diethylenetriamine. (2) An electronic component mounting method for simultaneously reflow soldering electronic components on both sides of a printed circuit board using the adhesive according to claim (1).