JPH0825420A - Molds for thermosetting resin - Google Patents

Abstract

PURPOSE:To provide molds for thermosetting resin in which molding quality can be improved by preventing its pinhole. CONSTITUTION:A cold slug well 7 is disposed between a unit cavity 6a of an end position and a gas vent 8 through the both. Accordingly, even if the air is introduced to the inner wall of the cavity 6a in the charging step, the air can be fed to the cold slug well 7, i.e., a part having no relation to the product via the flow of the resin thereby to prevent a pinhole, thereby improving its molding quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold useful when transfer molding, injection molding, sealing molding or the like is performed using a thermosetting resin as a molding material.

[0002]

2. Description of the Related Art FIG. 8 is a schematic view of a transfer molding machine used for molding a thermosetting resin. In the figure, 11 is an upper mold, 12 is a lower mold, 13 is a pot, 14 is a runner, 15 is a gate, 16 is a cavity, 17 is a gas vent, 18 is a plunger, and T is a tablet.

A plurality of runners 14 are branched from the pot 13, and the number of cavities 16 is equal to the product size.
Is provided at the branch end of the runner via the gate 15. The tablet T is formed by pressing a thermosetting resin powder into a cylindrical shape, and has a diameter slightly smaller than the pot diameter.

The upper mold 11 and the lower mold 12 are kept at a temperature suitable for plasticizing and hardening the thermosetting resin by a heater or the like, and the tablets T put in the pot 13 are plasticized by receiving heat. . The plasticizing resin is pressurized by the plunger 18, passes through the runner 14 and the gate 15, and is filled in each cavity 16, and further receives heat in the cavity 16 to be hardened.

After molding, the resin (product) hardened in each cavity 16 is taken out from the mold together with the cull part and the runner part, each product is separated at the gate position, and the runner part and the cull part are discarded.

[0006]

In the above filling process,
The plasticized resin Pm is used for the gas vent 1 as shown in FIG. 9 (a).
The inside air is discharged from 7 and flows in each cavity 16. However, since the gas vent 17 is dimensionally controlled so that the plasticized resin Pm does not flow out, the filling is completed with the air A being sandwiched between the inner wall surfaces near the gas vent as shown in FIG. If this happens, there is a problem that these remain as pinholes on the product surface.

The present invention has been made in view of the above problems, and an object thereof is to provide a molding die for a thermosetting resin capable of preventing pinholes and improving molding quality. .

[0008]

To achieve the above object, the invention of claim 1 comprises a cavity filled with a plasticized thermosetting resin, and a gas vent for discharging air in the cavity at the time of filling. In the molding die of the thermosetting resin described above, a pool for receiving a predetermined amount of the plasticized resin is arranged between the cavity and the gas vent so as to communicate with both.

According to a second aspect of the present invention, in the molding die according to the first aspect, a plurality of cavities are continuous through a resin flow path, and a hot water pool is provided between the cavity at the end position and the gas vent. Is characterized by.

The invention of claim 3 is characterized in that, in the molding die according to claim 2, a plurality of cavities are linearly continuous in the same direction.

[0011]

According to the first aspect of the present invention, the molten metal pool for receiving a predetermined amount of the plasticizing resin is arranged between the cavity and the gas vent so as to communicate with both, and the plasticizing resin is finally fed to the molten metal pool during filling. Therefore, even if air is trapped in the inner wall surface of the cavity during the filling process, the air can be sent to the inside of the basin by the flow of the resin, that is, to a portion unrelated to the product.

According to the second aspect of the present invention, since the plurality of cavities are continuous through the flow path, it is not necessary to increase the number of runners even when increasing the number of take-outs. The yield of the resin can be improved by increasing the ratio of the resin. Other functions are similar to those of the invention of claim 1.

According to the third aspect of the present invention, since the plurality of cavities are linearly continuous in the same direction, the plasticizing resin can be smoothly and surely filled in each continuous cavity. Other functions are similar to those of the invention of claim 2.

[0014]

1 is a schematic view of a transfer molding machine to which the present invention is applied. In the figure, 1 is an upper die, 2
Is a lower mold, 3 is a pot, 4 is a runner, 5 is a gate, 6 is a continuous cavity, 7 is a pool of hot water, 8 is a gas vent, 9 is a plunger, and T is a tablet.

The continuous cavity 7 is composed of a plurality of unit cavities 6a (4 in the figure) linearly continuous in the same direction through a flat-shaped flow path 6b through which a unit size of a product is matched. .

The pool 8 has the same width as the flow path 6b and a volume smaller than that of the unit cavity 6a, and is provided between the unit cavity 6a at the end position (the right end position in the figure) and the gas vent 8. It is arranged in communication.

The tablet T is formed by press-molding a powder of thermosetting resin such as epoxy, unsaturated polyester, phenol, diallyl phthalate into a cylindrical shape, and has a diameter slightly smaller than the pot diameter. are doing.

The upper mold 1 and the lower mold 2 are kept at a temperature suitable for plasticizing and curing the thermosetting resin by a heater or the like,
The tablet T placed in the pot 3 receives heat to be plasticized (see FIG. 1).

The resin Pm plasticized in the pot 3 is pressurized by the plunger 6, is first sent into the unit cavity 6a near the pot via the runner 4 and the gate 5, and then the flow passage 6b and the unit cavity 6a are sequentially passed. It is sent to the hot water pool 7 via (Fig. 2, Fig. 3 (a),
(B)).

In the above-mentioned filling process, as shown in FIG. 3 (c), the air A may be trapped on the inner wall surface of the unit cavity 6a on the downstream side, but the plasticizing resin Pm is fed to the pool 7. Therefore, the air A is pushed out into the adjacent unit cavity 6a by the flow of the resin Pm, and finally sent into the molten metal pool 7.

The filling of the plasticized resin Pm is completed when the resin Pm is sent to the hot water pool 7, but since the hot water pool 7 is a portion to be discarded later, the air A is sent to the same portion. Does not matter at all.

The plasticized resin Pm thus filled in the continuous cavity 6 is further heated and hardened. FIG.
As shown in the cross-sectional view and the top view, the product portion Ps cured in each unit cavity 6a has the resin Pk, P cured in the pot 3, the runner 4, and the pool 7, respectively.
It is taken out from the mold together with r and Py.

The molded product taken out of the mold is cut into individual products S at the flow path end position and the gate position as shown in FIG. Various methods such as a mechanical method using a dicing machine and a physical method using a laser beam can be used for cutting. The parts other than the product, that is, the cull part Pk, the runner part Pr, the flow path part Pt, and the molten metal pool part Py are discarded after cutting. Of course, when the length of the flow path portion Pt is short, the product S can be obtained by simply bending and breaking the product portion Ps at the flow path portion position without removing the flow path portion Pt.

According to the above-mentioned transfer molding machine, the pool 7 is provided between the unit cavity 6a at the terminal position and the gas vent 8, and the plasticized resin Pm is finally fed to the pool 7. Even when the air A is trapped on the inner wall surface of the unit cavity 6a during the filling process, the air A can be sent to the inside of the basin 7 by the flow of the resin Pm, that is, to a portion unrelated to the product. Generation can be prevented and molding quality can be improved.

The plurality of unit cavities 6a are connected to the flow path 6
Since it is continuous through b, it is not necessary to increase the number of runners even when increasing the number of take-ups, the runner occupying space can be reduced and the mold can be designed compactly. The product can be molded. Moreover, the yield of the resin can be improved by increasing the ratio of the resin used to the product, and the amount of the discarded resin can be reduced, which can greatly contribute to the reduction of the material cost.

Further, since the plurality of unit cavities 6a are linearly continuous in the same direction, all the continuous unit cavities 6a can be filled with the plasticizing resin smoothly and surely, and the continuous cavities 6 are surrounded by the pot. By arranging them radially, it is possible to follow the increase in the number of products.

FIG. 6 (a) shows another example of the shape of the flow path interposed between the unit cavities. The flow path 6b 'has a small height at the boundary with the unit cavity 6a and a central part. The height of is higher than this. If such a flow path 6b 'is adopted, the flow path part Pt can be pressed by pressing the cured flow path part Pt or bending the product part at the flow path end position as shown in FIG. Can be easily removed, and the cutting work described above is unnecessary.

FIG. 7 shows an example in which the above-mentioned transfer molding machine is used for sealing molding of electronic parts. By placing the component bodies such as capacitors whose both ends are supported by the lead frame F in the unit cavities in the mold open state, and then closing the molds and filling the continuous cavities with the plasticizing resin, the component bodies in the unit cavities are It can be sealed with a filling resin. After the molding, the resin Ps cured in each unit cavity is taken out from the mold together with the cull portion Pk, the runner portion Pr and the molten metal pool portion Py, and this is cut at the flow path end position and the gate position to further remove the frame frame.
A resin-packaged electronic component with leads can be obtained.

The continuous number of unit cavities can be appropriately increased or decreased according to the viscosity and curing characteristics of the thermosetting resin used, and the unit cavities may be non-linearly continuous. Further, the present invention can be applied to molding methods other than the transfer exemplified in the examples, and similar effects can be obtained.

[0030]

As described in detail above, according to the first aspect of the invention, even when air is trapped in the inner wall surface of the cavity during the filling process, the air flows in the hot water pool, that is, the product by the resin flow. You can send it to the part that has nothing to do with
This can prevent pinholes from occurring and improve molding quality.

According to the second aspect of the present invention, it is not necessary to increase the number of runners even when increasing the number of pieces to be taken, the space occupied by the runners can be reduced, and the die can be designed compactly. Many products can be molded with. Moreover, the yield of the resin can be improved by increasing the ratio of the resin used to the product, and the amount of the discarded resin can be reduced, which can greatly contribute to the reduction of the material cost.
The other effects are the same as those of the invention of claim 1.

According to the third aspect of the present invention, all the continuous unit cavities can be filled with the plasticizing resin smoothly and reliably, and the continuous cavities are radially arranged around the pot to increase the number to be taken. Can follow. Other effects are similar to those of the invention of claim 2.

[Brief description of drawings]

FIG. 1 is a schematic view of a transfer molding machine to which the present invention is applied.

FIG. 2 is a diagram showing a filling operation.

FIG. 3 is a diagram showing the flow of resin.

FIG. 4 is a view showing a state after molding.

FIG. 5 is a diagram showing a state after cutting.

FIG. 6 is a diagram showing another example of the shape of the flow channel and its action.

FIG. 7 is a diagram showing an example used for a package of electronic parts.

FIG. 8 is a schematic view of a conventional transfer molding machine.

FIG. 9 is a diagram for explaining conventional problems.

[Explanation of symbols]

1 ... Upper mold, 2 ... Lower mold, 3 ... Pot, 4 ... Runner, 5 ...
Gate, 6 ... Continuous cavity, 6a ... Unit cavity,
6b, 6b '... flow path, 7 ... hot water pool, 8 ... gas vent,
T ... tablet, S ... product.

Claims (3)

[Claims] 1. A mold for molding a thermosetting resin, comprising a cavity filled with a plasticized thermosetting resin and a gas vent for discharging air in the cavity at the time of filling, and a predetermined amount of the plasticizing resin. A mold for thermosetting resin, characterized in that a hot water pool for receiving is placed between the cavity and the gas vent so as to communicate with both. 2. The thermosetting resin molding according to claim 1, wherein a plurality of cavities are continuous through a resin flow path, and a hot water pool is provided between the cavity at the terminal position and the gas vent. Mold for. 3. The molding die for thermosetting resin according to claim 2, wherein a plurality of cavities are linearly continuous in the same direction.