JP2003236843A - Resin molding die and resin molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin molding die which is used for the manufacture of the molded product by injecting a molten resin into a cavity and inhibits the generation of voids in a molded product, and a resin molding method. <P>SOLUTION: This resin molding die comprises a top force 1 and a bottom force 2 opposed to each other, a cavity 6 formed in the top force 1, a porous ceramic member 9 which constitutes at least part of the face of the cavity 6, a fixing block 10 fixed on the upper face of the ceramic member 9, a recessed part 11 formed on a face in contact with the ceramic member 9 of the fixing block 9 and a suction aperture 12, a suction pipe 13 and a vacuum pump 14 which are sequentially connected with the recessed part 11. The top force 1 and the bottom force 2 are clamped and a molten resin 19 is injected into the cavity 6 while the interior of the cavity 6 is sucked using the vacuum pump 14. Consequently, the molten resin 19 including air bubbles 20 is defoamed and the air bubbles 20 are discharged to the outside of the cavity 6 together with gas entrapped in the cavity 6. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molding die used when a molten resin is injected into a cavity of at least one of opposing molds to produce a molded product, and more particularly to a lead frame. The present invention relates to a resin molding die and a resin molding method for sealing a chip-shaped electronic component mounted on a printed circuit board or the like (hereinafter referred to as a board).

[0002]

2. Description of the Related Art Conventionally, in resin molding in which molten resin is pressed and injected into a cavity, that is, so-called transfer molding, a resin molding die in which a cavity is provided in at least one side is used. ing. The mold is made of a steel material such as tool steel.

However, the conventional resin molding die has a problem that the gas contained in the molten resin is difficult to escape from the cavity after the die is clamped. As a result, bubbles contained in the molten resin may remain and voids may occur in the cured resin obtained by curing the molten resin. The voids generated in the cured resin may reduce the yield and reliability of a molded product, particularly a package which is a final product in which electronic components are sealed.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a resin molding die and a resin molding method for suppressing the generation of voids in a molded product.

[0005]

In order to solve the above-mentioned technical problems, a resin molding die according to the present invention is a molded product obtained by injecting a molten resin into a cavity of at least one of opposing molds. A resin mold used for manufacturing, comprising: an inorganic sintered member having at least a part of a cavity surface of a cavity and having porosity; and a suction means connected to the inorganic sintered member. In addition, the gas is permeable to the inorganic sintered member and the molten resin is impermeable to the inorganic sintered member.

According to this, the inside of the cavity is sucked by the suction means through the porous inorganic sintered member. Therefore, the bubbles contained in the molten resin in the cavity are effectively degassed, and the gas in the cavity containing the degassed bubbles is discharged to the outside of the cavity.

Further, the resin mold according to the present invention is the above-mentioned resin mold, wherein the inorganic sintered member has inorganic particles each having a hollow structure, and the inorganic particles while covering the surfaces of the inorganic particles. A connecting part for connecting the bodies in a mesh shape is provided, and the inorganic sintered member is porous at the connecting part.

[0008] According to this, the air bubbles contained in the molten resin in the cavities are degassed by sucking the inside of the cavities through the mesh-shaped connecting portions existing between the inorganic particles. In addition, the inorganic granules having a hollow structure and the mesh-shaped connecting portions existing between the inorganic granules can reduce the weight of the inorganic sintered member, and thus the weight of the resin molding die.

Further, the resin mold according to the present invention is the resin mold described above, which is provided with a coating portion for covering the inorganic sintered member on the cavity surface, and the coating portion is formed by curing the molten resin. It is characterized by having low adhesion to resin.

According to this, in the portion of the cavity surface, which is made of the inorganic sintered member, the portion that comes into contact with the molten resin is covered with the coating portion having low adhesion to the cured resin. Therefore, the releasability between the cured resin and the resin mold is improved.

Further, the resin mold according to the present invention is different from the above-mentioned resin mold in that it has a porous film stretched between the molds facing each other and the gas is permeable to the film. And the molten resin is impermeable, and the suction means sucks the inorganic resin through the inorganic sintered member to bring the film into close contact with the cavity surface.

According to this, the inside of the cavity is sucked by the suction means through the porous inorganic sintered member and the film. Therefore, the bubbles contained in the molten resin in the cavity are effectively degassed, and the gas in the cavity containing the degassed bubbles is discharged to the outside of the cavity. In addition, since the porous film uniformly adheres to the cavity surface, wrinkles in the film are prevented. As a result, the molten resin is injected into the cavity without wrinkles in the film that is in close contact with the cavity surface. Therefore, the generation of wrinkles is prevented on the surface of the cured resin formed by curing the molten resin. Also,
Since the surface state of the cavity surface is transferred to the cured resin via the film, the surface roughness of the cured resin can be easily set / changed according to the surface roughness of the cavity surface.

The resin molding method according to the present invention is a resin molding method of injecting a molten resin into a cavity of at least one of the molds facing each other to manufacture a molded article, wherein A step of tensioning a film having porosity to the cavity, a step of bringing the film into close contact with the cavity surface by sucking the film at the cavity surface of the cavity, a step of clamping the molds facing each other, and a film at the cavity surface. And a step of injecting a molten resin into the cavity while sucking the inside of the cavity via the.

According to this, the inside of the cavity is sucked by the suction means through the porous inorganic sintered member and the film. Therefore, the bubbles contained in the molten resin in the cavity can be effectively degassed, and the gas in the cavity containing the degassed bubbles can be discharged to the outside of the cavity. Further, since the porous film is evenly adhered to the cavity surface, wrinkles in the film can be prevented. As a result, the molten resin is injected into the cavity without wrinkles in the film that is in close contact with the cavity surface. Therefore, it is possible to prevent wrinkles from being generated on the surface of the cured resin formed by curing the molten resin. Also, since the surface condition of the cavity surface can be transferred to the cured resin via the film, the surface roughness of the cured resin can be easily set according to the surface roughness of the cavity surface.
Can be changed.

[0015]

(First Embodiment) First Embodiment of the Present Invention
The resin mold according to the embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 (1) is a sectional view showing a state where the resin molding die according to the present embodiment is opened, and FIG.
FIG. 2 is an enlarged cross-sectional view showing the vicinity of part A of FIG. 2 (1) and 2 (2) are cross-sectional views showing a state where molten resin is injected into the cavity after the resin molding die of FIG. 1 is clamped and a state where molten resin is filled into the cavity. It is a figure.

In FIG. 1A, an upper mold 1 and a lower mold 2 are provided so as to face each other, and these together form a resin molding mold. A substrate 3 such as a lead frame or a printed circuit board is placed on the lower mold 2. A chip 4 made of an electronic component such as a semiconductor chip is mounted on the substrate 3,
The electrodes of the chip 4 and the chip 4 are electrically connected to each other by the wire 5. In the upper mold 1, a space that covers the chip 4 and the wire 5, that is, a cavity 6, and a cavity 6
And a gate 7, which is a space communicating with the. As will be described later, the molten resin is injected into the cavity 6 via the gate 7 and hardened, whereby a hardened resin is formed.

Further, the upper die 1 is provided with a through hole 8 on the upper surface of the surface of the cavity 6. In the through hole 8,
Porous ceramic member 9 as inorganic sintered member
And the lower surface of the ceramic member 9 constitutes a part of the upper surface of the cavity 6. The fixing block 10 is fixed to the upper surface of the ceramic member 9. The fixing block 10 is provided with a concave portion 11 on a surface in contact with the upper surface of the ceramic member 9, and the concave portion 11 has a suction port 12,
It is connected to the vacuum pump 14 through the suction pipe 13 in order.

Below, the structure of the ceramic member 9 is shown in FIG.
This will be described with reference to (2). In FIG. 1 (2),
The hollow ceramic particles 15 include, for example, silica and alumina as main components, and have a high melting point (for example, 1500 ° C. to 160 ° C.).
It is a minute hollow spherical body having a temperature of about 0 ° C. The connecting portion 16 is an inorganic member formed in a film shape on the surface of the hollow ceramic particles 15 and connecting the hollow ceramic particles 15 in a mesh shape. The connecting portion 16 is made of, for example, a silicic acid compound such as sodium silicate and has a material having a melting point lower than that of the hollow ceramic particles 15 as a main component. The gap 17 is the connecting portion 1
6 is a space formed and the gap 17 exists in the connecting portion 16, so that the ceramic member 9 has porosity and air permeability.

The ceramic member 9 is manufactured by mixing and kneading the hollow ceramic particles 15 and the raw material of the connecting portion 16 and then firing the mixture at a temperature of, for example, about 1200 ° C to 1300 ° C. This firing temperature is lower than the melting point of the material of the hollow ceramic particles 15, and
The temperature is higher than the melting point of the material.

The coating portion 18 is made of the ceramic member 9
A film formed on the surface of the ceramic member 9 on the surface constituting the cavity surface. The coating portion 18 is made of a material having low adhesion to a cured resin obtained by curing a molten resin, such as a glaze, a fluorine-polymerized hard film, or diamond-like carbon.

By the way, when manufacturing the ceramic member 9 shown in FIG. 1B, the outer diameter of the hollow ceramic particles 15 and the number of the ceramic members 9 per unit volume and the connecting portion 16 are formed. The amount of the inorganic material can be changed appropriately. As a result, on the cavity surface, the size of the gap 17, that is, the diameter of the opening formed in the cavity surface and the surface roughness can be appropriately determined. Therefore, the surface roughness of the molded product can be easily set / changed by replacing the ceramic member 9.

Here, the first characteristic of the resin molding die according to the present invention is that the ceramic member 9 is manufactured so that the gap 17 satisfies the following conditions. That is, the diameter of the gap 17 is sufficiently small that the particles of the molten resin injected into the cavity 6 cannot pass through. Further, the diameter of the gap 17 is large enough to allow the gas evaporated from the molten resin and the molecules of the gas taken in the molten resin to pass while the molten resin is being pressurized and injected into the cavity 6. . Therefore, the gas taken in the molten resin, that is, the gas in the cavity 6 containing the bubbles is sucked using the vacuum pump 14 and is discharged to the outside of the cavity 6 through the gap 17. . On the other hand, the molten resin remains inside the cavity 6. A second feature is that a film-shaped coating portion 18 having low adhesion to the cured resin is formed on the surface of the ceramic member 9 on the cavity surface. This improves the releasability between the cured resin and the resin mold.

The operation of the resin mold according to this embodiment will be described below with reference to FIG. In FIG. 2 (1), while the upper mold 1 and the lower mold 2 are clamped, the inside of the cavity 6 is sucked by using the vacuum pump 14,
Molten resin 19 is injected into the cavity 6 through the gate 7 shown in (1). Thereby, the bubbles 20 contained in the molten resin 19 are removed. Therefore,
The bubbles 20 form the recess 1 together with the gas inside the cavity 6.
1, the suction port 12, and the suction pipe 13 are sequentially discharged to the outside of the cavity 6.

In FIG. 2B, after the molten resin 19 is filled in the cavity 6, the molten resin 19 is cured to form a cured resin. Then, after the upper mold 1 and the lower mold 2 are opened, the molded product in which the cured resin and the substrate 3 are integrated is taken out from the resin molding mold. Here, as shown in FIG. 1 (2), since the film-shaped coating portion 18 having low adhesion to the cured resin is formed on the surface of the ceramic member 9 on the cavity surface, a molded product is obtained. Are easily retrieved. In addition, it is possible to minimize the adhered matter such as dirt on the cavity surface.

As described above, according to this embodiment, the gas in the cavity 6 containing the bubbles 20 contained in the molten resin 19 is discharged to the outside of the cavity 6. Therefore, the generation of voids is suppressed in the molded product. Also, a film-shaped coating portion 1 is formed on the cavity surface.
Since No. 8 is formed, the molded product can be easily taken out, and the adhesion of deposits on the cavity surface can be suppressed. Further, the hollow ceramic particles 15 and the gap 17 can reduce the weight of the resin molding die.

In the ceramic member 9 shown in FIG. 1 (2), depending on the material and surface condition of the hollow ceramic particles 15 and the connecting portion 16 and the kind of the molten resin 19, a cured resin may be used. In some cases, the adhesion between the ceramic member 9 and the ceramic member 9 may not be so large. In this case, it is not always necessary to form the coating portion 18 on the surface of the ceramic member 9 on the cavity surface.

As the inorganic sintered member having a large number of continuous pores, the porous ceramic member 9 composed of the hollow ceramic particles 15 and the connecting portion 16 was used. Not limited to this, it is also possible to use a porous member including an inorganic hollow particle other than ceramics and the connecting portion 16.

(Second Embodiment) A resin mold according to a second embodiment of the present invention will be described with reference to FIG. Figure 3
(1) and (2) are cross-sectional views showing a state where the molten resin is injected into the cavity after the resin molding die according to the present embodiment is clamped, and a state where the molten resin is filled into the cavity. is there.

In FIG. 3A, a film 21 is stretched between the upper mold 1 and the lower mold 2. The film 21 is, for example, a breathable porous film made of a fluororesin such as PTFE having an excellent releasing property and having minute continuous pores formed therein. The diameter of these continuous holes is sufficiently small that particles of the molten resin 19 injected into the cavity 6 cannot pass through. Further, the diameter of the continuous hole is such that, in a state where the molten resin 19 is pressurized and injected into the cavity 6, a gas molecule composed of the gas evaporated from the molten resin 19 or the bubbles 20 taken into the molten resin 19 or the like. Large enough to pass through.

Here, the first feature of this embodiment is that by being sucked through the porous ceramic member 9,
That is, the film 21 is uniformly adhered to the entire surface of the ceramic member 9 on the cavity surface without wrinkles. This prevents the film 21 from being wrinkled due to the pressure of the molten resin 19. Therefore, it is possible to prevent the deterioration of the appearance quality due to the wrinkles of the film 21 being transferred to the surface of the molded product.
This effect is particularly remarkable when the molded product is large. Further, in the past, the film had to have a certain thickness in order to prevent wrinkles, but according to the present embodiment, the thin film 2
1 can be used, so that the material cost can be reduced and the device can be simplified. The second feature is that the bubbles 20 in the molten resin 19 are defoamed by being sucked through the ceramic member 9 and the film 21 each having porosity. As a result, the gas in the cavity 6 including the bubbles 20 is discharged to the outside of the cavity 6 via the film 21, the ceramic member 9, the recess 11, the suction port 12, and the suction pipe 13 in order. The third feature is that the film 21 is made of a fluororesin such as PTFE having excellent releasability. Thereby, when the molded product is taken out, the releasability between the cured resin and the film 21 becomes good. Therefore, the molded product is easily taken out, and the presence of the film 21 prevents the adhered matter from adhering to the cavity surface.

As described above, according to the present embodiment, the wrinkles of the film 21 are prevented, so that the deterioration of the appearance quality of the molded product is prevented. In addition, a thinner film can be used as compared with the conventional one. Further, generation of voids in the molded product is suppressed, removal of the molded product is facilitated, and adhesion of deposits on the cavity surface is suppressed. In addition, the weight of the resin molding die can be reduced as in the first embodiment.

By the way, according to this embodiment, the surface roughness of the molded product can be easily set and changed as follows. That is, as described with reference to FIG. 1 (2), the outer diameter of the hollow ceramic granules 15 and the quantity of the ceramic member 9 per unit volume, and the quantity of the inorganic material forming the connecting portion 16 are Change appropriately. Thereby, the surface roughness of the ceramic member 9 can be changed. On the other hand, since the film 21 is sucked by the vacuum pump 14 through the porous ceramic member 9, the film 21 is evenly adhered to the surface of the ceramic member 9 on the cavity surface. Also, a thinner film than before can be used. By these things, the ceramic member 9
The surface roughness of is accurately transferred to the surface of the molded article through the film 21. Therefore, since the molded product has a surface roughness corresponding to the surface roughness of the ceramic member 9, the surface roughness of the molded product can be easily set / changed by replacing the ceramic member 9.

In the above description of each embodiment, the ceramic member 9 having porosity is used as the inorganic sintered member in which a large number of continuous holes are formed. Not limited to this, other inorganic sintered member having a large number of continuous holes formed, for example,
A member made of sintered metal may be used.

The lower surface of the ceramic member 9 constitutes a part of the upper surface of the cavity 6. Not limited to this, the lower surface of the ceramic member 9 may constitute the entire upper surface of the cavity 6. Furthermore, all the cavity surfaces of the cavity 6 may be formed by the surface of the ceramic member 9. With these, the weight of the resin mold can be further reduced.

When the resin mold is used for a long period of time, organic matter such as dirt is gradually deposited on the cavity surface. Further, since the adhered substances are also deposited on the inner wall portion of the gap 17, the air permeability of the ceramic member 9 is lowered. Therefore, the bubbles 20 are less likely to be discharged to the outside of the cavity 6. In this case, the ceramic member 9 may be removed and left in a high temperature atmosphere lower than the firing temperature of the ceramic member 9 for a certain period of time. As a result, the deposit made of organic matter is volatilized and removed from the inner wall of the gap 17, so that the air permeability of the ceramic member 9 is restored.

The present invention can also be applied to other than resin molding for sealing electronic parts.

Further, the present invention is not limited to the above-mentioned embodiments, and can be arbitrarily and appropriately modified and selected as necessary within the scope of the gist of the present invention. Is.

[0038]

According to the present invention, the bubbles contained in the molten resin injected into the cavity are effectively defoamed, and are discharged to the outside of the cavity together with the gas in the cavity. Further, the weight of the resin molding die can be reduced. Further, the releasability between the cured resin and the resin mold is improved. Further, on the surface of the cured resin, the surface state of the cavity surface is accurately transferred, and wrinkles are prevented by the film that is evenly adhered to the cavity surface. This suppresses the occurrence of voids in the molded product, improves the releasability of the cured resin, and allows the surface roughness of the cured resin to be easily set / changed, thus preventing wrinkles on the surface of the cured resin. It is possible to provide a resin molding die and a resin molding method capable of preventing the above-mentioned phenomenon and further reducing the weight of the resin molding die, which is an excellent practical effect.

[Brief description of drawings]

FIG. 1 (1) is a sectional view showing a state where a resin molding die according to a first embodiment of the present invention is opened.
(2) is an enlarged cross-sectional view showing the vicinity of the portion A of FIG. 1 (1).

2 (1) and (2) respectively show a state where molten resin is injected into a cavity after the resin mold of FIG. 1 is clamped and a state where molten resin is filled into the cavity. It is sectional drawing shown.

FIGS. 3 (1) and 3 (2) show a state where molten resin is injected into a cavity after the resin molding die according to the second embodiment of the present invention is clamped, and a molten resin is injected into the cavity. It is sectional drawing which respectively shows the state filled with.

[Explanation of symbols]

1 Upper mold 2 Lower mold 3 substrates 4 chips 5 wires 6 cavities 7 gates 8 through holes 9 Ceramic member (inorganic sintered member) 10 Fixing block 11 recess 12 Suction port 13 Suction tube 14 Vacuum pump 15 Hollow ceramic particles (inorganic particles) 16 Connection 17 Gap 18 Coating department 19 Molten resin 20 bubbles 21 film

Claims (5)

[Claims] 1. A resin molding die used when a molten resin is injected into a cavity of at least one of molds facing each other to manufacture a molded product, wherein at least one of cavity surfaces of the cavity is formed. And an inorganic sintered member having a porosity and a suction means connected to the inorganic sintered member, the gas has permeability to the inorganic sintered member, and the molten resin Is a resin mold which is impermeable. 2. The resin molding die according to claim 1, wherein the inorganic sintered member has inorganic particles each having a hollow structure, and the inorganic particles are meshed while covering the surfaces of the inorganic particles. A resin molding die, comprising: a connecting portion that connects in a circular shape; and the inorganic sintered member has porosity in the connecting portion. 3. The resin molding die according to claim 1, further comprising a coating portion that covers the inorganic sintered member on the cavity surface, and the coating portion is formed by curing the molten resin. A resin molding die having low adhesion to a resin. 4. The resin molding die according to claim 1, further comprising a porous film stretched between the molds facing each other, and gas having permeability to the film. And the molten resin is impermeable, and the film is brought into close contact with the cavity surface by the suction means sucking through the inorganic sintered member. 5. A resin molding method for producing a molded product by injecting a molten resin into a cavity of at least one of opposing molds, wherein a porous film is stretched between the opposing molds. A step of providing, a step of bringing the film into close contact with the cavity surface by sucking the film on the cavity surface of the cavity, a step of clamping the opposite molds, and a step of pressing the film on the cavity surface. And a step of injecting the molten resin into the cavity while sucking the inside of the cavity through the resin molding method.