JPS595226B2 - How to install parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for attaching components such as electronic components, and more particularly to a method for attaching components to a printed circuit board using an adhesive.

Conventionally, the method of fixing electronic components such as chip resistors and chip capacitors on insulating substrates made of phenol, epoxy, polyimide, etc. has been to apply a small amount of adhesive to the adhesive surface of the electronic components or between the solder bonding patterns of the insulating substrate. The adhesive is applied to the substrate and attached to the board via an adhesive, and the adhesive is then cured in a heating drying oven to obtain various properties for bonding and fixing electronic components, such as bonding strength during soldering and heat resistance. After that, solder it through the molten solder bath1.
The most common method was

The adhesive used here is solder heat resistant, fast curing, and has good adhesion.
Excellent properties such as strength, flexibility, etc. are required.

However, no conventional adhesive has been found that satisfies these properties. There are various resins such as 20 epoxy resins, unsaturated polyester resins, phenol resins, epoxy (meth)acrylate resins, ester (meth)acrylate resins, and urethane (meth)acrylate resins.

However, various properties such as heat resistance, fast curing properties, and adhesion 25 are not well balanced. Particularly flexible ones are rarely found. For example, epoxy resins generally have excellent heat resistance and adhesive properties, but poor flexibility. Acrylate resins and methacrylate resins generally have inferior heat resistance. Further, ultraviolet curable resin compositions usually have excellent curing performance, but those containing inorganic fillers or coloring substances have the disadvantage of poor curability. Therefore, when these adhesives are used, there is a problem that after the components have been bonded to the printed circuit board and hardened, the components may fall off during transportation or during soldering. Therefore, the present invention aims to solve these problems.

How to attach the parts of the present invention is 1 to 35% by weight of epoxy (meth)acrylate resin and 0.3 to 30% by weight of urethane (meth)acrylate resin. and 0.05 to 5 weight of either or both of a photopolymerization initiator and a thermal polymerization initiator. and 0.05 to 50% by weight of either or both of an inorganic filler and a pigment, and a mixture of one or more of acrylic esters and methacrylic esters constituting the remainder. The component is applied to the printed circuit board, and after the component is placed and cured, the component is attached to the printed circuit board to prevent the component from falling off in later steps.

Next, each component constituting the curable resin composition of the present invention will be explained in detail.

Compounds with acryloyl or methacryloyl groups include acrylic acid, methacrylic acid and alkyl, cycloalkyl, glycidyltetrahydrofurfuryl, allyl, hydroxyalkyl acrylate or methacrylate, alkylene glycol, polyoxyalkylene glycol, trimethylolpropane. , mono- or polyacrylic esters or methacrylic esters such as pentaerythritol.

In addition, epoxy (meth)acrylate resin, urethane (
Also included are meth)acrylate resins, oligoester (meth)acrylates, and the like. Here, (meth)acrylate represents either acrylate or methacrylate, or both. The present invention is characterized in that it contains the above-mentioned acryloyl group- or methacryloyl group-containing resin, as well as a polymerization initiator, an inorganic filler, or a coloring pigment as essential components.

More specifically, in order to improve the heat resistance and enclosure of the resin composition, it is characterized in that it is contained as an acryloyl group- or methacryloyl group-containing resin.

Further, to explain in more detail, in order to improve the heat resistance of the resin composition, an epoxy (meth)acrylate resin is contained as an acryloyl group- or methacryloyl group-containing resin.

Examples of the epoxy (meth)acrylate resin include phenol novolak epoxy (meth)acrylate resin, cresol novolak epoxy (meth)acrylate resin, and bisphenol A epoxy (meth)acrylate resin. In addition, a urethane (meth)acrylate resin is blended together with the epoxy (meth)acrylate resin. In addition, since the epoxy acrylate resin is a starch syrup-like or solid substance and produces a hard cured product, the blending amount is preferably 35% by weight or less, and 35% by weight or less.
If the amount exceeds % by weight, the resin composition will become highly viscous, making it difficult to apply with a dispenser or screen printing, the cured product will not have enough flexibility, and the adhesive will easily come off when using a flexible printed circuit board. If this is not included, the heat resistance will decrease, and the urethane acrylate resin will weigh 30%? The following is desirable; if the amount is more than that, the heat resistance and adhesive strength will decrease, and there is a problem that the bonded parts will fall off in the later process.If it is not included, the flexibility will decrease and the flexible substrate This makes it unsuitable for attaching parts to. From this, 1 to 35% by weight of epoxy (meth)acrylate resin and 0.5 to 30% by weight of urethane (meth)acrylate resin to the resin composition.
It is necessary to contain it.

Polymerization initiators include photopolymerization initiators and thermal polymerization initiators.

As a photopolymerization initiator, one or a mixture of two or more of benzoin, benzoin alkyl ether, a-substituted benzoin, anthraquinone, alkyl-substituted anthraquinone, benzyl, benzophenone, etc.; as a thermal polymerization initiator, benzoin peroxide, methyl ethyl ketone peroxide, etc. oxide, t-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, t-butyl peroxybenzoate, etc., or one or more azo compounds such as azobisisobutyronitrile. Mixtures and the like can be mentioned. Furthermore, when the thermal polymerization initiator is used in combination with a photopolymerization initiator, it can also act as a curing accelerator for the photopolymerization initiator. The amount of these used is 0.0 based on the resin composition.
5-5 weight? is desirable. Examples of inorganic fillers include those commonly used as fillers for resins, such as calcium carbonate, talc, and barium sulfate.

The amount of these added depends on the viscosity of the resin component, the viscosity when the composition is used, the properties of the cured product, etc., but it is preferably 10 to 50% by weight based on the resin composition. In addition, in order to impart particularly thixotropic properties, this purpose can be achieved by generally known methods, for example by adding a small amount of Paraerosil. As the coloring substance, commonly known dyes or pigments can be used. If the amount of the coloring substance added is large, the ultraviolet curability will be significantly reduced, so in order to improve the curability, it can be used in combination with a thermal polymerization initiator. The amount of color pigment added is 0.0
5 to 5% by weight is desirable. As described above, the resin composition of the present invention contains an inorganic filler and/or a coloring pigment of 0.00%.
It contains 05 to 50% by weight, is opaque and cannot be cured by ordinary ultraviolet irradiation, but is a resin with high chain polymerization properties.Furthermore, it is a photopolymerization initiator or a photopolymerization initiator that can be used to initiate thermal polymerization. This is a composition that can be sufficiently cured by containing an agent. In addition, in order to improve storage stability, P-benzoquinone, hydroquinone,
Catechol, P-methoxyphenol, etc. can be used.

These can be used alone or as a mixture of two or more in an amount of 0.0001 to 5% by weight based on the resin. Furthermore, in the present invention, cobalt naphthenate, manganese naphthenate, amines, P-toluenesulfonic acid amide, etc. are blended as a curing accelerator, if necessary. Also, add antifoaming agents, thickeners, etc. as necessary*.
I can do it. In addition, the resin composition of the present invention can be cured by a conventional ultraviolet ray curable composition or by an ultraviolet generating source used in curing a heat-curable composition, such as a conventional ultra-high-pressure mercury lamp, high-pressure mercury lamp, or low-pressure mercury lamp. , metal halide lamps, xenon lamps, chemical lamps, etc.

Further, examples of the heating source include hot air, nichrome heater wire, infrared lamp, and far infrared heater. Next, the present invention will be specifically explained with reference to Examples.

[Example 1] 1 Phenol novolac type epoxy acrylate 18% by weight 2 Urethane acrylate 14% by weight 3 Tetraethylene glycol dimethacrylate 34% by weight 4 Multifunctional polyester acrylate 2% by weight 5 Benzoin isobutyl ether 1% by weight 6 t-Butylper Oxybenzoate 1% by weight7 Talc 27% by weight8 Pigment (white) 0.5% by weight9 Antifoaming agent, thickener, inhibitor 2.5% by weightThe above urethane acrylate is 2,6-tolylene diisocyanate and ethylene glycol It is an acrylate of the addition reaction product, and is represented by the following chemical formula.

The above polyfunctional polyester acrylate is an acrylate of an ester compound of terephthalic acid and ethylene glycol, and is represented by the chemical formula below.

These components were mixed uniformly to obtain a curable resin composition of the present invention.

Next, apply it to a film-like printed circuit board with a thickness of 200μ using a regular dispenser, and after setting the adhesive parts,
It was cured by irradiating it for 10 seconds (irradiation distance 10 degrees) using a 0W/(V7L high-pressure mercury lamp).The properties of the above adhesive are 1. Soldering heat resistance (JISC-6481) 260±5℃, 10 seconds No abnormality ( No decrease in adhesion)2
Flexibility 90 degree bending No abnormality (no peeling) 3 Adhesive strength 180 degree peeling 10 kg/cd Guaranteed Good adhesion to a wide range of materials such as glass, ceramics, metal epoxy moldings, phenol resin plates, etc.

Moreover, this composition had excellent storage stability and was stable for more than 3 months at room temperature.

In the case of the above compounded composition, curing with only a photopolymerization initiator is not possible, but by using a thermal polymerization initiator in combination, it acts as an accelerator for the photopolymerization initiator, and the curing reaction can be completed in a short time. . [Example 2] 1 Bisphenol A type epoxy acrylate 27 weight? 2 Urethane acrylate 14% by weight3
Trimethylolpropane trimethacrylate
14% by weight4 Polyfunctional polyester acrylate 17% by weight5 Benzoin isobutyl ether
1 weight? 6t-butyl peroxybenzoate
1% by weight 7 pigment (brown) 2% by weight? The above urethane acrylate and polyfunctional polyester acrylate are the same compounds as in Example 1.

These components were mixed uniformly to obtain a curable resin composition of the present invention. Next, using a 250-300 mesh screen, 20
80W/G7 after printing to 0μ thickness and setting adhesive parts
rL high pressure mercury lamp for 20 seconds (irradiation distance 10cTn)
) irradiation, and then placed in a 160° C. heating oven for 1 minute to cure. Even though it is basically opaque, it is a highly chain-reactive composition when exposed to ultraviolet rays, but this heating completely cures it to the shadow areas (the bottom of the adhesive area) where ultraviolet rays do not reach and to the deep parts of thick coatings. can be done. Regarding the various properties of the adhesive, similar results to those of Example 1 were obtained. This blended composition is easily cured by ultraviolet irradiation up to a coating thickness of 200 .mu.m, but when the coating thickness is 200 .mu.m or more, it is easily cured by also using heat curing.

The feature of this composition is that, compared to general heat-curable resin compositions, the surface is first cured by UV irradiation, and then the inside is cured by heat curing, so the coated material does not flow or change its shape when heated. It has the following characteristics. In addition, the above compound has a well-balanced property of heat resistance, adhesiveness, flexibility, and can bond parts made of a wide range of materials such as resin parts and ceramic parts. It can be used in a wide range of ways depending on the purpose.

As explained above with the examples, the method of the present invention:
Since the curing time of the curable resin composition for fixing parts is shorter than that of conventional ones, the time for fixing the parts to the printed circuit board can be shortened.
The use of meth)acrylate resin and urethane(meth)acrylate resin provides a good balance between sufficient heat resistance and flexibility, allowing for adhesion even when heated during soldering, etc., performed during the printed circuit board assembly process. It is possible to achieve the effect that parts can be fixed without a decrease in force and without parts falling off even on a flexible board.

Claims (1)

[Claims] 1 1 to 35% by weight of epoxy (meth)acrylate resin and 0.3 to 3% of urethane (meth)acrylate resin
0% by weight, 0.05 to 5% by weight of one or both of a photopolymerization initiator and a thermal polymerization initiator, and 0.05 to 50% by weight of one or both of an inorganic filler and a pigment. , a curable resin composition consisting of one or a mixture of two or more of acrylic esters and methacrylic esters constituting the remainder is applied to a printed circuit board, and the component is mounted and cured to attach the component to the printed circuit board. How to install.