JPH08288321A - Liquid resin molding method - Google Patents

Abstract

PURPOSE: To obtain a liquid resin molding method for an electronic device in which a void-free molding having good appearance can be obtained in a short time. CONSTITUTION: An electronic device 2 positioned in a lower die 1 is applied with an upper case to form a vacuum container which is then evacuated. Liquid insulating resin 5 is then injected into the container through an injection nozzle penetrating the upper case 4 and dripped onto the electronic device 2. Before the injected insulating resin 5 cures thoroughly, the upper case is replaced by an upper die 7 subjected to temperature control. Subsequently, the same liquid insulating resin 5 is injected into the cavity between the upper and lower dies 7, 1 through an injection nozzle 6 of the upper die 7 and thermally cured at an appropriate temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sealing and molding a liquid resin, and more particularly to a method for molding a liquid insulating resin on the outside of electronic and electric parts and sealing with the resin.

[0002]

2. Description of the Related Art In recent years, the miniaturization of parts used has been further accelerated along with the miniaturization of electronic and electric devices.
Surface mounting is the main method for mounting such electronic and electrical components, and for the purpose of insulation protection,
It is widely practiced to wrap and seal the outside of these parts with an insulating resin.

Conventionally, in the encapsulation of such electronic and electric parts, on the parts held in a vacuum container,
A casting method is used in which a liquid thermosetting resin such as an epoxy resin or a silicone resin is dropped and potted to be cured.

In recent years, the mold temperature has been kept at a relatively low temperature (50 to 150 ° C.), and a liquid thermosetting resin has been injected and filled into the cavity of the mold at a relatively low pressure (0.1 to 10 Kg / cm ² ). A so-called liquid resin injection molding method has also been developed.

[0005]

However, among the methods for sealing and molding electronic parts and the like using such liquid resin,
In the former casting method, there is a problem that one surface of the molded body corresponding to the liquid resin dropping surface is not covered with the container, so that the appearance is poor and the molding takes time and labor.

Further, in the latter liquid resin injection molding method, there is a problem that the degree of vacuum around the electronic parts and the like deteriorates as the liquid resin is filled, and unfilled portions and voids are generated.

The present invention has been made in order to solve these problems, and an electronic component or the like made of a liquid resin which can be molded in a short time, has a good appearance and is capable of obtaining a sealed molded body free from voids and the like. It is an object of the present invention to provide a method for sealing and molding.

[0008]

The liquid resin encapsulation molding method of the present invention is applied to electronic and electric parts held in a lower mold.
A step of dropping a liquid insulating resin under reduced pressure, and after placing an upper mold on the lower mold, the liquid insulating resin is dropped and impregnated around the electronic and electric parts, the liquid And a step of injection-filling and molding the insulating resin.

In the present invention, the same kind of liquid thermosetting resin is usually used as the insulating resin to be dropped and impregnated on the electronic component etc. and the insulating resin to be injected and filled in the mold cavity. . However, different types of synthetic resins may be used as the dropping impregnating resin and the injection molding resin,
Alternatively, it is possible to further increase the resin impregnation rate for electronic parts and the like by changing the compounding ratio of the curing agent and the like.

[0010]

In the liquid resin sealing molding method of the present invention,
The surroundings of electronic and electrical parts such as semiconductor elements mounted and held in the lower mold are vacuum-sucked and kept at a certain degree of vacuum. An appropriate amount, that is, a part of the final sealing molding resin amount is dropped. Next, after the atmospheric pressure around the electronic parts etc. in which the liquid resin has been dropped and impregnated is returned to normal pressure, the upper mold is covered on the lower mold, and then the liquid insulation in the cavity between them. Resin is injected and filled, and this resin is sealed and molded around electronic parts and the like.

In this way, since impregnation and sealing with a liquid insulating resin for electronic parts and the like are continuously and efficiently performed, molding does not take time, the appearance is good, and there is no void or unfilled portion. A molded body is obtained.

[0012]

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

In the encapsulation molding method of the embodiment, first, as shown in FIG. 1, an electronic component 2 such as a semiconductor element is placed in a recess of a lower mold 1 having a recess of a predetermined shape and having a temperature controlled. Is positioned and arranged, on which the injection nozzle 3 for the liquid resin is placed.
Is covered with an upper container 4 to hermetically seal the joint with the lower mold 1, and the inside of the vacuum container formed by the lower mold 1 and the upper container 4 is vacuum pumped (not shown). Aspirate under reduced pressure. The liquid resin injection nozzle 3 is provided so as to penetrate through the upper container 4, and the plunger 3b concentrically arranged in the nozzle main pipe 3a is moved up and down so that the inner peripheral surface of the upper container 4 is closed. The tip portion 3c opened directly above the electronic component 2 is opened and closed.

When the inside of the vacuum container is maintained at a certain degree of vacuum, the tip portion 3c of the injection nozzle 3 is opened and the liquid insulating resin 5 is injected into the vacuum container. The injected liquid insulating resin 5 is dropped on the electronic component 2.

Next, before the liquid insulating resin 5 dropped and impregnated on the electronic component 2 is completely cured, the upper container 4 is removed, and then the upper mold 1 is placed on the lower mold 1, as shown in FIG. To
The upper mold 7 to which the temperature is controlled and the liquid resin injection nozzle 6 is connected is put on. Here, the injection nozzle 6 has a tip portion 6c connected to a sprue 7a provided on the upper mold 7, and the entire nozzle is configured to be vertically movable. Further, the nozzle tip portion 6c can be opened and closed by raising and lowering the plunger 6b concentrically arranged in the nozzle main pipe 6a.

Next, the same liquid insulating resin 5 as the resin impregnated by dropping is injected into the cavity between the lower mold 1 and the upper mold 7 from such an injection nozzle 6 and then filled.
The lower die 1 and the upper die 7 are heated to an appropriate temperature to be cured.

In the method of the embodiment thus constituted, the electronic component 2 can be efficiently impregnated with the insulating resin and the encapsulation molding can be carried out efficiently, and the resin impregnation rate to the component is high. As a result, it is possible to obtain a compact molded encapsulation product which has no unfilled parts and voids and has a good appearance.

In the above embodiment, the resin of the same type and composition as the liquid insulating resin 5 to be dipped and impregnated on the electronic component 2 is injection-molded in the mold cavity.
The present invention is not limited to this. That is, by using different kinds of resins as the dropping impregnating resin and the injection molding resin, or by changing the compounding ratio of the curing agent or the like, the resin impregnation rate to the electronic component 2 can be further increased. Further, it is also possible to obtain a sealed molded body having less burrs and no internal cracks.

Further, by dividing the steps using the index table (dropping impregnation step, injection molding step, etc.), more efficient sealing molding can be performed. Furthermore, while arranging a plurality of lower molds in series in a circulating manner,
By dividing the process, continuous and efficient sealing molding can be performed, and in the case of such a configuration, it is possible to easily cope with a change in process.

[0020]

As is apparent from the above description, in the liquid resin encapsulation molding method of the present invention, an appropriate amount is applied to the electronic and electric parts held in the lower mold under a reduced pressure of a certain vacuum degree. After the liquid insulating resin of (1) is dropped and impregnated, the upper part is replaced with an upper mold having an injection mechanism and the liquid resin is injected and filled to impregnate the electronic and electric parts with the resin and seal molding. It can be performed continuously and efficiently. Further, it is possible to obtain a compact molded encapsulation having a high resin impregnation rate, no unfilled portion and no void, and a good appearance.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing a dropping and impregnating step in an embodiment of a liquid resin sealing molding method of the present invention.

FIG. 2 is a cross-sectional view schematically showing an injection molding process in the example.

[Explanation of symbols]

 1 ………… Lower mold 2 ………… Electronic parts 3 ………… Liquid resin injection nozzle 4 ………… Upper container 5 ………… Liquid insulating resin 6 ………… Liquid resin injection nozzle 7 ………… Upper metal Type

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Claims (1)

[Claims] 1. A step of dropping a liquid insulating resin under reduced pressure onto electronic and electric parts held in a lower mold, and arranging the upper mold on the lower mold, and then applying the liquid And a step of injection-filling and molding a liquid insulating resin around the electronic and electric parts in which the insulating resin has been dropped and impregnated.