JPS60116151A - Sealing method of electronic parts - Google Patents

Abstract

PURPOSE:To effectively seal electronic parts by forming a film bonded to the part with powder of photocurable resin, emitting ultraviolet ray to cure it. CONSTITUTION:Resin powder is bonded to a hybrid IC2 which places a miniature molded transistor. When now using a fluid dipping method, an electronic part is preheated to the softening temperature or higher of the resin powder, this part is led to a fluid tank, and the resin is bonded to the surface of the part in the tank. After forming a resin film 2 of uniform thickness, ultraviolet ray is emitted to cure the resin. As a light source of the ultraviolet ray a high pressure mercury lamp, or xenon arc lamp is used. Thus, the resin 3 is not mixed with the gap 4 which is not emitted with the light, and uncured portion is not retained. Since powder is used, the resin after coating is not dropped to irregularly form the thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for sealing a moisture-proof insulated container for various electronic components or hybrid ICs to be subjected to moisture-proof insulation.

[Background technology]

Hybrid ICs and the like mounted with capacitors, resistor arrays, and various electronic components are protected by resin coating for moisture-proof insulation.

Moisture-proof insulation method-C has conventionally applied a thermosetting, photocurable, or photo- and thermocurable liquid resin face to the surface of electronic components using a method such as dipping. There is a method of curing the resin by heating or ultraviolet irradiation, or a combination of both heating and ultraviolet rays, or a method of attaching thermosetting epoxy resin powder to electronic parts, heating it to form a film, and curing it. Among these methods, when thermosetting resin is used in the method using liquid resin, it takes 30 minutes to 3 hours at a temperature of room temperature to 180°C to completely cure the resin. As a result, productivity was extremely low. On the other hand, when using a photocurable resin, the resin can be cured by irradiating it with ultraviolet light for only a few seconds to a few minutes, which significantly improves productivity. However, on the other hand, as shown in Figure 1, Another disadvantage is that the resin 3 gets into the gap between the mounted component l such as a transistor and the substrate 2, that is, the shadow area 4 where light does not reach, and the resin does not harden even after being irradiated with ultraviolet rays. Furthermore, liquid thermosetting and photocurable resins have the following drawbacks in common. In other words, ■Liquid monomers have a strange odor and many have a negative impact on the human body, making them a poor working environment.■Pheno has the risk of ignition and explosion and must be handled with care. In addition to the above problems, (1) The thickness of the paint film becomes uneven due to dripping of the phenol, making it impossible to achieve uniform coating.

On the other hand, when thermosetting resin powder is used, the above problems are solved, but it takes a long time to cure the resin at 130° to 180°C, from 30 minutes to 3 hours, and it requires a high-performance heating furnace. is needed.

[Purpose of the invention]

It is an object of the present invention to provide a temporary sealing method which eliminates the drawbacks of the above-mentioned conventional methods, has a fast curing speed, and provides a uniform coating film.

[Disclosure of the Invention J In order to achieve the above object, the method for encapsulating electronic components according to the present invention involves attaching photocurable resin powder to electronic components to form a film, and curing it by irradiation with ultraviolet rays. This feature aims to significantly shorten the time required for moisture-proof insulation treatment and provide highly reliable moisture-proof insulation with a uniform coating.

The photocurable resin powder used in this invention may be a resin that polymerizes and hardens by irradiation with ultraviolet rays, as long as it has a melting point or softening temperature of 50°C to 150°C. It is used after being ground to a particle size of ~350 mesh. Generally, it is a composition containing a photopolymerization initiator such as benzoin alkyl ether, penzyl dimethyl ketal, benzophenone, etc. in epoxy acrylate, urethane acrylate, or unsaturated polyester resin. A linear polymer compound having compatibility with the above resin, such as methacrylic resin, may be used in this photocurable resin composition.

Methacryl-nunalene copolymer, polystyrene.

May contain ethyl cellulose, polycarbonate, hydrocarbon resin, etc. In addition, polymerizable monomers,
It may also contain fillers, pigments, coupling agents, etc.

Next, a method for sealing an electronic component according to the present invention will be explained.

The resin powder can be attached to the surface of the electronic component by a method similar to a known powder coating method.

Namely, there are the fluidized immersion method, the bath spray method, the spray method, and the electrostatic dry spray method. Therefore, to explain the fluidized dipping method as an example, first, an electronic component is preheated to a temperature higher than the softening temperature of the resin powder, the component is introduced into a fluidized bath, and the resin is adhered to the surface of the electronic component within the bath.

In some cases, it may be necessary to repeat preheating and dipping several times until a uniform coating is obtained. Once a uniform resin film with the required thickness is formed, the resin is cured by irradiation with ultraviolet rays. In this case, it is convenient to irradiate the electronic component with ultraviolet light while the temperature of the electronic component is high to complete the curing reaction.

Ultra-high-pressure mercury lamps, high-pressure mercury lamps, low-pressure mercury lamps, carbon arc lamps, xenon arc lamps,
A metal halide lamp or the like can be used. The intensity of the ultraviolet rays is not particularly limited, but for curing work 30
-160 W/cmO is preferred. 1] If one resin is irradiated with ultraviolet rays from a distance of 10 to 20 cm, curing is usually completed within a few seconds. Therefore, faster curing can be achieved compared to conventional methods using thermosetting resins.

In the present invention, post-heating may be performed after powder adhesion, if necessary, or preheating may be omitted and only post-heating may be performed.

Since a powdered resin is used in the resin sealing, the resin 3 will not enter the gap 4 where light does not shine, and there is no risk of leaving uncured parts as shown in Figure 2. . Moreover, the resin after application does not drip and the thickness of the coating film becomes uneven.

By the way, when sealing semiconductor elements such as ICs, transistors, or diodes, partially sealing hybrid ICs, or sealing the ends of capacitors, it is necessary to adjust the powder resin to the shape of the sealing area in advance so that the desired shape is achieved. It is convenient to have it on a tablet. The sealing method according to the present invention can also be applied to such uses. Conventionally, tablets for pressing thermosetting epoxy resin powder have been used for this purpose;
It took a long time, 20 hours.

In this respect, the sealing method according to this release +J1 achieves a remarkable shortening of the curing time.

(Example 1) Epoxy acrylate (manufactured by Showa-tei Bunsoku Co., Ltd., Lipoxy VR)
-60) 100 g (S (parts by weight, hereinafter F).

Heat and mix 2 parts of benzyl dimethyl ketal in a dark place.
After uniformly dissolving benzyl dimethyl ketal, it is ground at a low temperature to a particle size of about 20 mesh.
A powder coating with a melting point of 80"C was obtained.

Using the above powdered resin, a 1fi4 resin film was formed on the entire surface of a hybrid IC by the usual fluidized dipping method as described above, and then 80W/c! n high pressure mercury lamp, 10
Ultraviolet rays were irradiated for 5 seconds from a distance of cm to obtain a hard resin coating.

After curing, when we removed the parts mounted on the hybrid IC, we found that no resin had entered the approximately 0.255 m gap between the parts and the board, and unlike in the case of liquid resin, the uncured parts of the resin It didn't exist.

(Example 2) A resin tablet was prepared in a conventional manner from the same resin as the resin powder used in Example 1, and used for sealing the end of a Mylar capacitor.

First, place the tablet at the end of the capacitor and
After heating to 0°C to melt the powder and form a uniform coating, it was heated to 0°C using a high-pressure mercury lamp of BOW/am for 10 min.
The resin was cured by irradiating ultraviolet light for 10 seconds from a distance of σ.

When the finished product was disassembled, it was found that the liquid resin had penetrated between the films (Mylar film), and that part remained uncured even after irradiation with light.
No resin penetration was observed.

〔Effect of the invention〕

As seen above, in the sealing method of this invention, the resin may get into gaps where light does not shine, or it may drip after application and cause damage to the coating.
Since there is no possibility of uneven thickness of the insulation, it is possible to provide highly reliable moisture-proof insulation with uniform thickness. Furthermore, since the curing time of the resin is very short, productivity can be significantly increased.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a hybrid IC sealed by the conventional method.
FIG. 2 shows an embodiment of this invention, and is a sectional view of a hybrid IC which is moisture-proof and insulated by this sealing method. 1...Mini-mold transistor 2...Hybrid IC base & 3...1 Liquor coating 1 return 4...1 Suzuma agent Patent attorney Takehiko Matsumoto Figure 1 Figure 2

Claims (2)

[Claims] (1) A method for sealing electronic components, which comprises attaching photocurable resin powder to electronic components to form a film, and curing the film by irradiating it with ultraviolet rays. (2) The method for sealing an electronic component according to claim 1, wherein the photocurable resin powder is in the form of a doublet.