JPH05337979A - Method for seal-molding of electronic part - Google Patents

Abstract

PURPOSE:To prevent the generation of flash, in the seal molding of an electronic part by a thermosetting insulating resin, by preventing the penertation of a sealing resin into the gap between a mold and the non-sealing part of the part. CONSTITUTION:Beat-resistant resin films 9 each slightly larger than the area of the main surface of the connection terminal 7 of a small-sized transformer 8 are bonded to the upper and rear main surfaces of the connection terminal 7 and the whole is arranged in a mold at a predetermined position and the connection terminal 7 having the films 9 bonded thereto is carefully arranged in the cavity part of the mold. Next, a liquid thermosetting insulating resin is received in the mold to be cured. After curing, the small-sized transformer 8 subjected to seal-molding is taken out of the mold and the resin films 9 are peeled to expose the connection terminal 7.

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 electronic parts, and more particularly, to prevent intrusion of a sealing resin into a non-sealing portion,
The present invention relates to a method for molding a sealed component of good quality.

[0002]

2. Description of the Related Art In recent years, in the field of electronic parts, electronic parts are placed in a mold and filled with a thermosetting insulating resin material at a low pressure of, for example, 50 Kg / cm ² or less, as the lightness, thinness, shortness and miniaturization progress. A method of sealing molding is used in which the molding is performed.

By the way, various types of automatic mounters have been conventionally used as a means for efficiently mounting electronic components on a printed circuit board. In each of the mounters, a required number of lead terminals are provided on the component body. Is configured to mount electronic components of a certain shape attached at appropriate intervals. That is, the chuck of the automatic mounting machine grasps the body of the electronic component accurately positioned, and the lead terminal is inserted into the through-hole previously formed at a predetermined position on the conductor circuit of the printed circuit board. Alternatively, it is mounted on a conductor pad formed at a predetermined position of the conductor circuit and firmly fixed by soldering.

In the mounting process using such an automatic mounting machine, when an insulating film or foreign matter is attached to the lead terminals, the electronic circuit is not completed and the mounting is hindered. It is necessary to completely remove the coating and foreign matter from the lead terminals. Therefore, conventionally, before mounting, an abrasive is mixed with air by a blasting method and sprayed onto a portion where a coating film or a foreign substance is attached to remove them.

[0005]

However, in the method described above, the protective film formed on the lead terminals of the electronic component by plating is scraped off along with the foreign matter, etc., so that if used as it is, an oxide film is formed on the lead terminals. There is a risk that the function of the circuit will be significantly affected.
Further, in order to prevent such a bad influence on the circuit function, if the protective film is formed again on the lead terminal after the blasting, there is a problem that the working efficiency is poor.

[0006] Therefore, in the sealing and molding of electronic parts, it is desired to perform the molding without damaging the surface protective film of the lead terminal. In other words, if non-conductive coatings and foreign substances do not adhere to the surface of the lead terminals during the encapsulation molding, unnecessary man-hours are not required to remove them, and surface protection is required during removal. It is preferable in terms of properties without damaging the film.

In the conventional encapsulation molding method, however, the following minute gaps exist because of the precision of the die and the positioning precision when the lead terminals are pulled out from the strip plate. The resin that leaked out adhered to the lead terminals and became burrs called flash burrs. That is, conventionally, as shown in FIGS. 3 and 4, a state in which a die 1 is provided with a dug portion 4 corresponding to the shape of the lead terminal 3 of the electronic component 2 and the lead terminal 3 is mounted on the dug portion 4 Then, the thermosetting insulating resin 5 was filled in the mold 1, but the dug portion 4 is slightly excavated in consideration of the variation in the dimensions of the lead terminals 3. A gap is created between the lead terminal 4 and the attached lead terminal 3. Therefore, the insulating resin 5 flowing out at the time of filling entered into the above-mentioned gap, and this became a burr and adhered to the lead terminal 3.

The present invention has been made to solve such a problem, and when sealing and molding an electronic component with a thermosetting insulating resin, a gap is formed between a molding die and a non-sealing portion of the component. The purpose is to prevent the encapsulation resin from entering and prevent burr from occurring.

[0009]

According to the method of sealing and molding an electronic component of the present invention, a heat-resistant resin film is formed on the outer peripheral surface of a non-sealing portion when the electronic component is sealed and molded with a thermosetting insulating resin. After sticking, place the electronic component in the mold,
Next, the mold is characterized in that the insulating resin is filled and cured.

[0010]

In the encapsulation molding method of the present invention, a heat resistant resin film is attached to the outer peripheral surface of a non-sealing portion such as a lead terminal of an electronic component, and the non-sealing portion is encapsulated by this film. After being protected, such an electronic component is placed at a predetermined position in the mold, so that the resin film that has been attached almost completely eliminates a minute gap between the mold and the non-sealing portion. Buried. Then, in such a state, since the thermosetting insulating resin is filled in the mold, the insulation of the sealing insulating resin into the gap and the outflow from the gap can be prevented or minimized. .. Further, the attached resin film can be easily peeled and removed without damaging the characteristics of the electronic component.

As described above, since the sealing resin that has entered and flowed out through the gap between the molds does not become a burr and adheres to the non-sealed portion, the number of deburring steps is minimized and the cost can be reduced. In addition, a sealed component of good quality can be obtained.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. In the embodiment, as shown in FIG. 1, when the small transformer 8 in which the box-shaped main body coil portion 6 is attached with the perforated flat plate-shaped connection terminal 7 is sealed and formed, as shown in FIG. 2 heat-resistant resin films 9 larger than the main surface area of the connection terminals 7 by 10% were prepared.
Are attached to the upper and lower main surfaces of the connection terminal 7, respectively. In addition,
When particularly high heat resistance is required, it is desirable to use a polyimide resin film as the heat resistant resin film 9. Further, such a heat resistant resin film 9 is
It is desirable that the end portions be attached straight so that they are along the boundary line between the connection terminal 7 that is the non-sealing portion and the main body coil portion 6 that is the sealing portion.

Next, the main body coil portion 6 of such a small transformer 8 is arranged at a predetermined position in the mold, and the connection terminal 7 to which the heat resistant resin film 9 is attached is attached.
After carefully mounting in the dug portion dug into the die with normal accuracy, a liquid thermosetting insulating resin is filled into the die and cured. The small transformer 8 which is sealed and molded after curing is taken out from the mold, and the resin film 9 is peeled off to expose the connection terminal 7.

In an embodiment constructed in this way,
In the mounting portion of the connection terminal 7, conventionally, the inner peripheral surface of the mold and the metal member of the connection terminal 7 were in contact with each other, but in the embodiment, the heat resistant resin film 9 is interposed therebetween. Since the minute gaps between the metal members are almost completely filled with the film 9, intrusion and outflow of the insulating resin into the gaps can be completely prevented or minimized. Therefore, the insulating resin does not form burrs and adheres to the connection terminals 7, and the number of deburring steps can be reduced. Moreover, the heat-resistant resin film 9 can be easily peeled and removed without damaging the connection terminal 7 in terms of characteristics, and a good quality sealing component can be obtained.

Next, a concrete example in which an epoxy resin is used as a thermosetting insulating resin and a small transformer is sealed and molded at a low pressure of 50 Kg / cm ² or less will be described.

That is, the main body coil portion is 20 mm in length and 1 in width.
Eight pieces of box-like 6 mm x 4 mm thick, with a digging for inserting such a small transformer when molding and molding a small transformer with a perforated flat plate connection terminal with epoxy resin I prepared a mold for taking.

The dimension of the dug portion corresponding to the sealing portion (main body coil portion) formed in the lower die has a length of 20 mm and a width of 1
10% larger for 6mm and 2% for 4mm thickness
It is thin, and the size after sealing is 21.5 mm in height and 1 in width.
It is configured to be 7.2 mm × thickness 5.2 mm.

Then, 0.0125 mm thick polyimide resin films are attached to the upper and lower surfaces of the connection terminals of such a small transformer, respectively. Then, make sure that the connection terminals do not come off from the dug portion. Meanwhile, the mold was mounted at a predetermined position. Next, the upper mold and the lower mold were gently closed, and a pressure of 3 × 10 ⁶ to 4 × 10 ⁶ Pascal was applied and held. Then, when the pressure holding is completed, the air in the mold is sucked and depressurized, and when the internal pressure reaches about 1.3 × 10 ² Pascal, the epoxy resin preliminarily stirred and kept at a temperature of 30 to 40 ° C. Then, the mixture was press-filled at a pressure of 7 × 10 ⁵ Pascal and heated at a temperature of 150 ° C. for 4 minutes to be cured. Next, the molded body was taken out of the mold and the polyimide resin film was peeled off. Observation of the transformer thus molded by encapsulation revealed that the surface of the connection terminal, which is the non-encapsulated portion, was clean, and that no burrs were generated or attached. On the other hand, in the transformer that was sealed and molded in the same manner as in the example except that the polyimide resin films were attached to both upper and lower surfaces of the connection terminal, the thickness of the transformer was 3/100 to 5 inside the connection terminal.
A thin burr of about / 100 mm was generated in a width of about 5 mm, and it could not be mounted on a substrate etc. as it was.

[0019]

As described above, according to the method of the present invention, when the electronic component is sealed and molded with the thermosetting insulating resin, it is sealed in the gap between the molding die and the non-sealed portion of the component. Resin does not enter or flow out. Therefore, burrs are not generated and the generated burrs do not adhere to the non-sealing portion, so that a good quality sealed component can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing an electronic component that is sealingly molded in an embodiment of the present invention.

FIG. 2 is a perspective view for explaining a first step in the embodiment of the present invention.

FIG. 3 is a sectional view for explaining a conventional sealing molding method.

FIG. 4 is a plan view for explaining a conventional sealing molding method.

[Explanation of symbols]

1 ... Mold, 2 ... Electronic component, 3 ... Lead terminal, 4 ...
Dug part, 5 ... Insulating resin, 6 ... Main body coil part,
7 ... Connection terminal, 8 ... Small transformer, 9 ... Heat resistant resin film.

Claims (1)

[Claims] 1. When sealing and molding an electronic component with a thermosetting insulating resin, a heat-resistant resin film is attached to the outer peripheral surface of the non-sealing portion, and then the electronic component is placed in a mold. Then, a method of sealing and molding an electronic component, characterized by filling the mold with the insulating resin and curing the resin.