JPH0625611A - Pressure-sensitive adhesive for forming electronic circuit and method for forming electronic circuit - Google Patents

Abstract

PURPOSE:To obtain the subject adhesive which has a controlled stickiness during mounting electronic parts and can be completely cured after the mounting by compounding a methacrylic ester, an anaerobic curative, a nonanaerobic curative, a plasticizer, an inorg. filler, and an org. pigment as the main components. CONSTITUTION:This adhesive is prepd. by compounding as the main components a methacrylic ester, an anaerobic curative, a nonanaerobic curative, a plasticizer, an inorg. filler, and an org. pigment. The adhesive is used for forming an electronic circuit by printing a substrate with a cream solder, coating the substrate with the adhesive, making the compsn. applied on the substrate sticky in an atmosphere of low-concn. oxygen, mounting electronic parts on the substrate, and melting the solder printed on the substrate at a high temp. to form a solder bonding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive and an electronic circuit forming method for temporarily fixing an electronic component to a substrate when the electronic component is mounted on the substrate to form an electronic circuit.

[0002]

2. Description of the Related Art In recent years, as a method for forming an electronic circuit, Japanese Patent Laid-Open Publication No.
As disclosed in Japanese Unexamined Patent Publication No. 8-18090, a method is generally used in which a chip-type electronic component such as a chip resistor or a chip capacitor is first temporarily fixed to a substrate and then soldered. In this method, a photo-curable adhesive is applied to the electronic component mounting position on the substrate, the photo-curable adhesive is thickened by light irradiation, and the electronic component is pressed against the thickened adhesive and temporarily fixed. I am trying to do it. That is, when the photocurable adhesive is applied to the substrate, the viscosity of the adhesive is kept low in order to facilitate the application work using a dispenser or the like. When mounting the electronic component, the viscosity of the adhesive is increased to reduce the fluidity, and the pressure-sensitive adhesive property is exerted so that the electronic component is adhesively fixed to prevent displacement. The photocurable adhesive is preferably
It also has a thermosetting property, and after being irradiated with light, it is heat-treated to be completely hardened to give heat resistance, and the adhesive property is eliminated to prevent dust and the like from adhering.

[0003]

However, in the above-mentioned conventional method, it is difficult to delicately control the photo-curing reaction when the adhesive is thickened by irradiation with light, so that the reaction sometimes progresses at the stage of irradiation with light. There is a problem that the adhesive strength may decrease or disappear due to excess.

The present invention solves the above-mentioned conventional problems by using a tacky adhesive of excellent quality which has adhesiveness when mounted on an electronic component and whose curing can be controlled so as to completely cure after mounting. An object of the present invention is to provide a circuit forming method for producing a circuit board with high mounting accuracy.

[0005]

In order to achieve this object, the present invention is to blend a methacrylic acid compound with an anaerobic curing agent and a non-anaerobic curing agent, cure the mixture in a low oxygen concentration atmosphere, and increase it. It is made to be viscous or completely hardened.

[0006]

According to this adhesive / adhesive and electronic circuit forming method, the polymerization reaction at the time of thickening the adhesive can be controlled easily and accurately, so that the polymerization reaction does not proceed excessively at the time of thickening. Since the electronic component can be fixed at a predetermined position without the adhesive force being reduced or disappearing, it is possible to form an electronic circuit having high accuracy and excellent reliability.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

(Example 1) 1.5 g of butyl methacrylate
And tert-butyl peroxybenzoate 0.01
~ 0.3 g and dicumyl peroxide 0.01-0.5
g and Carmine 6B (trade name, manufactured by Dainippon Ink and Chemicals) 0.
After adding 01 to 0.2 g and stirring at room temperature for 1 to 2 hours, 628 g of butyl methacrylate, 10 to 100 g of Empara (trade name, manufactured by Ajinomoto Co., Inc.), and 100 to 400 of calcium carbonate.
g was added, the mixture was stirred at room temperature for 1 to 3 hours, and then defoamed by centrifugation to obtain a pressure-sensitive adhesive for forming an electronic circuit.

In this embodiment, an example in which butyl methacrylate is used has been described, but the number of carbon atoms of the alkyl group is 1 to 1.
A methacrylic acid ester formed of 10 alkyl groups may be used.

Example 2 The steps of an electronic circuit forming method using the adhesive for forming an electronic circuit prepared in Example 1 are shown in FIG.
2 (a) to (e) show a flow chart of the method for forming the electronic circuit in FIG. In the figure, 1 is a substrate on which electronic components are mounted, 2 is a substrate electrode on which components are mounted on the substrate 1, 3 is cream solder printed and applied, 4 is a tacky adhesive for forming an electronic circuit manufactured in Example 1, Reference numeral 5 is a thickened product of the adhesive / adhesive agent 4, 6 is an electronic component to be mounted on the substrate 1, 7 is a completely cured product of the thickened adhesive / adhesive material 5, and 8 is a solder alloy.

First, as shown in FIG. 1A, cream solder 3 is printed on a substrate electrode 2 formed on a substrate 1.
Next, as shown in FIG. 1B, the substrate electrode 2 on the substrate 1
Adhesive 4 is applied to the side of the adhesive using an adhesive applicator. Next, as shown in FIG. 1 (c), the tacky-adhesive agent 4 is thickened in an atmosphere having an oxygen concentration of 10 to 10,000 ppm at room temperature to be changed to a tacky-adhesive thickened material 5. Next, as shown in FIG.
The electronic component 6 is mounted on the thickened material 5 by the component mounting machine. Next, as shown in FIG. 1 (e), the cream solder 3 is melted in a high-temperature reflow furnace to perform solder bonding, and at the same time, the viscous adhesive thickened material 5 is changed to a completely hardened material 7 to increase the tackiness. It disappeared and a high quality electronic circuit was obtained.

Example 3 An electronic circuit was produced using the adhesive for forming an electronic circuit produced by the method of Example 1. The electronic circuit forming process is shown in FIG. 3, and the flowchart of the electronic circuit forming method is shown in FIG. In FIG. 3, 11 is a substrate for forming an electronic circuit, 12 is a substrate electrode for joining electronic components formed on the substrate 11, 13 is cream solder, and 14 is a tacky adhesive for electronic circuit formation manufactured according to the first embodiment. Agent, 15
Is a photo-thickened substance of tacky adhesive 14, 16 is an electronic component to be attached, 1
Reference numeral 7 is a completely cured product of the tackiness agent photo-thickened material 15, and 18 is a solder alloy.

First, as shown in FIG. 3A, the substrate 11
The cream solder 13 is printed on the substrate electrode 12 formed above. Next, as shown in FIG. 3B, a viscous adhesive 14 is applied between the two substrate electrodes 12 on the substrate 11 by an adhesive applicator. Next, as shown in FIG. 3C, the adhesive agent 14 is irradiated with ultraviolet rays to act on the non-anaerobic curing agent to increase the viscosity of the adhesive agent 14, and the adhesive agent photosensitizer is added. Change to item 15. Next, as shown in FIG. 3D, the electronic component 16 is mounted on the tacky adhesive agent photo-thickened material 16 by a component mounting machine. Next, as shown in FIG. 3E, the cream solder 13 is melted in a high temperature reflow furnace in which the inside of the furnace is kept in an atmosphere having an oxygen concentration of 10 to 10,000 ppm to perform solder bonding and at the same time perform viscous adhesion. Agent light thickener 15
By causing the anaerobic curing agent to completely cure the tacky-adhesive photo-thickened material 15 to eliminate the tackiness as the tacky-adhesive completely cured material 17, the electronic component 16 is accurately adjusted to a predetermined level. Fixed in position, a high quality electronic circuit was obtained.

[0014]

As is apparent from the above description of the embodiments, according to the present invention, the reaction at the time of thickening the adhesive is easy,
And because anaerobic curing agent and non-anaerobic curing agent are blended so that they can be accurately controlled, the polymerization reaction proceeds too rapidly during thickening, forming an electronic circuit without reducing or eliminating the adhesive force. can do.

[Brief description of drawings]

FIG. 1 is a sectional view showing an electronic circuit forming process according to a second embodiment of the present invention.

FIG. 2 is a flowchart showing an electronic circuit forming method according to the second embodiment.

FIG. 3 is a sectional view showing an electronic circuit forming process according to the third embodiment.

FIG. 4 is a flowchart showing an electronic circuit forming method according to the third embodiment.

[Explanation of symbols]

 1 Substrate 2 Substrate Electrode 3 Cream Solder 4 Adhesive Adhesive 5 Adhesive Adhesive Thickened Product 6 Electronic Component 7 Adhesive Adhesive Completely Cured Product 8 Solder Alloy

Claims (4)

[Claims] 1. A pressure-sensitive adhesive for forming an electronic circuit, which mainly comprises a methacrylic acid ester, an anaerobic curing agent, a non-anaerobic curing agent, a plasticizer, an inorganic filler, and an aerobic pigment. 2. A first method for printing cream solder on a substrate.
And a second step of applying the adhesive / adhesive for forming an electronic circuit onto a substrate according to claim 1, and imparting tackiness to the adhesive / adhesive applied onto the substrate in a low oxygen concentration atmosphere at room temperature. 3rd to do
An electronic circuit forming method comprising: a step, a fourth step of mounting an electronic component, and a fifth step of melting the cream solder printed on the substrate at a high temperature to perform solder joining. 3. A third step of imparting tackiness to the tacky adhesive is carried out by irradiation of ultraviolet rays, and a fifth step of melting the cream solder at a high temperature to join the solder is carried out in a high-temperature low oxygen concentration atmosphere. The method for forming an electronic circuit according to claim 2, wherein 4. The method for forming an electronic circuit according to claim 2, wherein the tackiness of the tacky adhesive given tackiness in the third step is eliminated in the fifth step, and the tackiness adhesive is completely cured. .