JPH07290491A - Mold - Google Patents

Abstract

PURPOSE:To form a cull part without applying discharge processing to suppress the cost of a mold low. CONSTITUTION:A resin sump part 11 is provided to a lower center block 1 and a resin supply pot 4 is opened to the bottom part of the resin sump part 11. The ejection cull roll 12 faced to the interior of the resin sump part 11 and constituting the cull part is provided to an upper center block 2 and, by changing the shape of the ejection roll 12, the vol. of the cull part or the flow characteristic of a resin can be altered. Therefore, discharge processing is entirely obviated and the cost reduction is achieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die used in, for example, a molding device for resin molding of a semiconductor device, and more particularly to a structure of a cull portion.

[0002]

2. Description of the Related Art Conventionally, as this type of molding die, there is one having a structure as shown in FIG. FIG. 5 is a cross-sectional view showing a conventional mold die, in which reference numeral 1 is a lower die center block as a lower die, and 2 is vertically movable with respect to the lower die center block 1 by a press mechanism (not shown). It is an upper mold center block as an upper mold configured to be. The lower mold center block 1 and the upper mold center block 2 are arranged adjacent to a chase block in which a cavity (not shown) is formed.

A pot 4 for supplying the resin 3 into the die is mounted on the lower die center block 1, and
A runner 5 is formed to flow the resin from the cull portion of the upper mold center block 2 described later into the cavity. Further, the reference numeral 6 located in the pot 4 is a plunger for pumping the resin 3 into the mold.

In the upper mold center block 2, a cull portion 7 for accumulating resin is formed at a position facing the upper end opening of the pot 4 on the lower surface which constitutes the mold clamping surface together with the upper surface of the lower mold center block 1. ing. The cull portion 7 is formed by partially recessing the lower surface of the upper die center block 2, and the side portion thereof is configured to overlap the upstream end portion of the runner 5 in a plan view.
The inner wall of the cull portion 7 is tapered so that the cured resin 3 can be easily removed. In addition, this cull part 7
Is provided for the purpose of adjusting the flow rate of the resin supplied to the runner 5 by the volume of this portion and stabilizing the flow characteristics of the resin such as the flow velocity and the flow direction of the resin.

When the cull portion 7 is recessed in the upper mold center block 2, the inner wall must be tapered and the side portion must be aligned with the position of the runner 5, resulting in a complicated shape. Due to the relationship, machining cannot be performed using a cutting tool, so electrical discharge machining was used.

By the way, the external dimensions of the cull portion 7 are designed so as to obtain an optimum amount of resin according to the resin (tablet) used. Therefore, when the type of resin is changed or the shape of the cavity is changed, the entire upper die center block 2 must be recreated. If the upper mold center block 2 is not dug in and the flow of the resin 3 is received only by the horizontal surface, the resin 3 will flow to the cavity at the initial flow rate, and thus the resin 3 will be loaded into the cavity. For example, the thin metal wire for wire bonding of a semiconductor device is easily cut.

[0007]

As described above, in the conventional molding die, since the cull portion 7 is formed by electric discharge machining, there is a problem that a large machining time is required and the manufacturing cost is increased. there were. Moreover, if the type of molded product or the type of resin tablet is changed, the upper mold center block 2 must be recreated, which further increases the cost.

From the idea of reducing the cost of rebuilding the center block as much as possible, for example, JP-A-3-
As disclosed in Japanese Unexamined Patent Publication No. 246017 or Japanese Unexamined Patent Publication No. 2-6112, it has been conventionally practiced to change the volume of the portion where the resin is accumulated.

In the molding die disclosed in Japanese Patent Laid-Open No. 3-246017, another resin reservoir portion is communicated with the cull portion,
The wall surface of the resin reservoir portion is variably configured by a screw so that the internal volume can be changed. However, in such a structure, since a mechanism is added in addition to the conventional electric discharge machining, the structure becomes more complicated than the conventional mold, and the initial cost becomes high, which is not practical. Moreover, the complicated structure is likely to cause a failure. In addition, the cured resin is likely to remain in the resin reservoir different from the cull portion, and the flow of the resin flowing into the runner becomes unnatural.

The molding die disclosed in Japanese Patent Application Laid-Open No. 2-6112 has a structure in which a plurality of types of center blocks having cull portions of different sizes are prepared and are exchanged as needed. It was If a plurality of molds are formed in this way, the initial cost will be high as in the above case.
In particular, in the case where the mold is divided into a center block and a chase block, the center block must be formed with high accuracy, and it is impossible to reduce the cost.

The present invention has been made to solve the above problems, and an object of the present invention is to form a cull portion without performing electrical discharge machining and to keep the cost low.

[0012]

A molding die according to the present invention is provided with a resin reservoir portion having an opening on a mating surface and a resin supply pot provided with this resin on either one of a lower die and an upper die. The opening is made at the bottom of the reservoir, and the other is provided with a protrusion that faces the inside of the resin reservoir and forms a cull portion therewith.

[0013]

The cull portion is composed of a resin reservoir portion formed by machining on one die and a projection provided on the other die. By changing the shape of the protrusion, the volume of the cull portion and the flow characteristics of the resin are changed. The shape of the protrusion can be changed by machining.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. FIG. 1 is an enlarged cross-sectional view showing an essential part of a molding die according to the present invention, and FIG. 2 is a plan view showing a mold clamping surface of a lower mold center block, which is one side with respect to a center line of a pot. Only one is drawn. FIG. 3 is a perspective view of the protruding calcoma. In these figures, the same or equivalent members as those described in FIG. 5 are designated by the same reference numerals, and detailed description thereof will be omitted.

Lower mold center block 1 shown in these figures
The resin reservoir 11 is formed by a recessed portion in which the upper surface serving as the mold clamping surface is partially recessed downward, and the pot 4 is opened at the bottom of the resin reservoir 11. The resin reservoir 11 is formed in a circular shape in plan view as shown in FIG. 2, and the opening diameter is gradually increased from the bottom toward the upper opening edge. Then, the runner 5 is attached to the inclined inner peripheral wall of the resin reservoir 11.
The upstream end of the is open. In addition, the resin reservoir 11
Is formed by subjecting the lower die center block 1 to mechanical processing such as cutting with an end mill.

In the present embodiment, the upper mold center block 2 has a flat lower surface which is a mold clamping surface, and a protruding calcoma 12 as a projection according to the present invention is provided on the lower surface. The protruding calcoma 12 is formed by using a lathe or a milling machine. In this embodiment, the protruding calcoma 12 is formed in a truncated cone shape as shown in FIG. 3, and is fixed to the lower surface of the upper mold center block 2 serving as a mold clamping surface by a fixing bolt 13 as a fastening means. . The outer diameter of the protruding calcoma 12 is
It is set smaller than the inner diameter of the opening of the resin reservoir 11, and the thickness dimension is set smaller than the depth dimension of the resin reservoir 11. The mounting position of the protruding calcoma 12 is a position facing the inside of the resin reservoir portion 11 from above, and the axial center of the protruding calcoma 12 coincides with the axial center of the pot 4. The fixing bolt 13 penetrates the upper mold center block 2 in the vertical direction and has a lower end protruding and screwed to the calcoma 12.

By providing the projecting calcoma 12 on the upper mold center block 2 as described above, the resin pool portion 11 and the projecting calcoma 12 are formed on the wall surface of the molding die having the lower mold center block 1 and the upper mold center block 2. The cull part is defined as That is, the amount of the resin 3 accumulated in the cull portion can be changed by changing the diameter dimension, the thickness dimension, etc. of the protruding calcoma 12 and changing the volume thereof, so that the resin flows into the cavity (not shown) from the runner 5. It is possible to control the flow rate of the resin 3 to be used. In other words, the external dimension of the protruding calcoma 12 is such that the volume of the cull portion in the state where it faces the resin reservoir 11 is sufficient to fill the runner 5 and the cavity from the total amount of the resin supplied to this cull portion. It is set to correspond to the amount minus the minutes. Moreover, the flow direction in the cull portion can be changed so that the resin 3 can easily flow into the runner 5, and the flow velocity when the resin 3 flows into the runner 5 can be made slower than the initial flow velocity. There is.

According to the molding die thus constructed, for example, when resin-sealing a semiconductor device, first, a lead frame or the like is placed in a cavity (not shown) with the upper and lower center blocks separated from each other in the vertical direction. Load it. Then, the upper mold center block 2 is lowered and the mold is clamped.
At this time, the protruding calcoma 12 faces the inside of the resin reservoir 11.

After the mold is clamped in this way, a resin tablet (not shown) is pushed into the cull portion by the plunger 6. By doing so, the resin is pressed against the protruding calcoma 12 from below and is heated and melted while being kneaded in the cull portion, and flows into the cavity through the runner 5 from the inside of the cull portion. At this time, since the surplus amount of the resin 3 remains in the cull portion, the resin 3 flows into the cavity without excess or deficiency. Further, the flow direction of the resin 3 hitting the protruding calcoma 12 is changed so as to face the runner 5, and the resin 3 flows into the runner 5 in a state where the flow velocity is reduced.

After the resin 3 is hardened, the upper mold center block 2 is raised to take out the resin portion from the molding die, thereby completing the molding step. Also, if the type of resin tablet is changed or the package size of the semiconductor device is changed,
The protruding calcoma 12 is replaced with one that gives the optimum amount of resin. This replacement work is performed by loosening and removing the fixing bolt 13.

Therefore, according to the molding die constructed as described above, the cull portion is provided in the lower mold center block 1 by resin machining and the resin reservoir 11 formed in the upper mold center block 2. Sticking out Calcoma 1
It is composed of 2 and 2, so this protruding Calcoma 1
By changing the shape of 2, the volume of the cull portion and the flow characteristics of the resin can be changed. Protruding calcoma 12
Since the shape can be changed by machining using a lathe, a milling machine, etc., it is extremely easy to change the volume of the cull portion and the flow characteristics of the resin.

That is, since the cull portion can be formed without performing any electric discharge machining, the lower mold center block 1
The upper center block 2 can be manufactured at low cost. In addition, when changing the volume of the cull portion or the flow characteristics of the resin, it is only necessary to change the shape of the protruding calcoma 12 by machining, and it is possible to carry out very easily, and from this point also the cost can be kept low. .

Further, as shown in this embodiment, the protruding calcoma 12 is fixed to the upper die center block 2 by a fixing bolt 13.
By adopting a configuration in which it is detachably attached, the volume of the cull portion and the flow characteristics of the resin can be changed by replacing the protruding calcoma 12 with another one. Therefore, the changing work can be performed very easily and at low cost. Since the protruding calcoma 12 is attached by the fixing bolt 13, the attaching work can be easily performed.

In the above embodiment, the protruding calcoma is formed in the shape of a truncated cone. However, the protruding calcoma determines the amount of resin and at the same time controls the flow characteristics of the resin. The characteristics can be changed as shown in FIG. 4 so that various characteristics can be easily obtained.

FIG. 4 is a perspective view showing another example of the protruding calcoma, FIG. 4 (a) shows an example in which a large number of spiral recesses are provided, and FIG. 4 (b) shows an example in which the cross section is formed in a cross shape. The figure (c) shows an example formed in a substantially semicircular shape in side view.

The protruding calcoma 12 shown in FIG.
The lower surface 21 is formed to have a smaller area than that of the above-mentioned embodiment, and a large number of concave portions 22 are spirally arranged side by side on the outer peripheral portion of the truncated cone. The concave portion 22 constitutes an uneven portion that controls the flow of resin. According to this structure, the resin in the cull portion flows in a substantially spiral shape along the concave portion 21, so that the resin can be easily kneaded, and the resin can be smoothly flowed so that air is trapped in the resin. You can prevent getting stuck. In addition, the resin flows toward the outer peripheral side of the cull portion and easily enters the runner, so that it is possible to prevent the cavity from being unfilled. The same effect can be obtained by providing a spiral projection instead of the spiral recess 22.

The protruding calcoma 12 shown in FIG. 4 (b) is formed in a cross shape in cross section, and is formed such that the thickness of each side of the cross becomes gradually thicker as it goes upward. The respective sides of this cross are indicated by reference numerals 23 to 26 in the figure. The protruding calcoma 12 shown in FIG.
7 is formed in a substantially semicircular thick plate shape. The peripheral surface 28 is curved so as to be rounded from the visible main surface 27 toward the back main surface. Even with such a configuration, the resin can be easily kneaded and can be smoothly flowed, so that an effect equivalent to that of the example shown in FIG.

Further, in the above-described embodiment, the upper mold center block 2 is configured to be vertically movable, but the lower mold center block 1 is configured to be vertically movable with respect to the upper mold center block 2. It is also possible that both are moved up and down together. Furthermore, the vertical positional relationship between the resin reservoir and the protruding cull can be configured upside down as compared with the embodiment. In this case, the pot is attached to the upper mold center block.

[0029]

As described above, in the molding die according to the present invention, the resin mold is provided with the resin reservoir portion opening to the mating surface in either the lower mold or the upper mold. Opened at the bottom of the resin reservoir, and on the other hand, since the protrusion that faces the inside of the resin reservoir and constitutes the cull portion is provided, the cull portion is a resin reservoir portion formed by machining in one mold, The protrusion is provided on the other mold, and the volume of the cull portion and the flow characteristics of the resin can be changed by changing the shape of the protrusion.

Therefore, since it is possible to easily change the shape of the protrusion by machining, it is not necessary to perform electric discharge machining. Therefore, it is possible to reduce the processing cost and the delivery time. In addition, even when the amount of resin is changed by changing the shape of the resin or the cavity used, it is possible to quickly and inexpensively respond.

Further, by changing the shape of the protrusion, it is possible to obtain the best resin flow characteristics for the product, so that the quality of the product becomes stable. Furthermore, since the flow characteristics of the resin can be controlled so that the product is not adversely affected even if the injection speed of the press is increased, the index of the press can be improved.

In addition, when the projection is detachably attached to the mold, the projection is easy to manufacture and thus inexpensive, and the replacement can be easily carried out, so that the running cost is also reduced. Can be made.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view showing a main part of a molding die according to the present invention.

FIG. 2 is a plan view showing a mold clamping surface of a lower mold center block, in which only one side is drawn with respect to the center line of the pot.

FIG. 3 is a perspective view of a protruding calcoma.

FIG. 4 is a perspective view showing another example of the protruding calcoma,
The figure (a) shows an example in which a large number of spiral recesses are provided, the figure (b) shows an example in which the cross-section is formed, and the figure (c) shows an example in which it is formed in a semicircular shape in side view. Show.

FIG. 5 is a cross-sectional view showing a conventional molding die.

[Explanation of reference numerals] 1 ... lower center block, 2 ... upper center block, 3 ... resin, 4 ... pot, 5 ... runner, 6 ... plunger, 11 ... resin reservoir, 12 ... protruding calcoma, 1
3 ... Fixing bolt.

Claims (3)

[Claims] 1. A resin reservoir portion comprising a recessed portion that is opened in a mating surface is provided in either one of the lower die and the upper die, and a resin supply pot is provided in the bottom portion of the resin reservoir portion. On the other hand, a molding die characterized in that a protrusion that faces the inside of the resin reservoir and constitutes a cull portion is provided with the resin reservoir. 2. The molding die according to claim 1,
A mold die, characterized in that the projection is formed separately from the die in which it is provided and is detachably attached to this die by fastening means. 3. The molding die according to claim 1, wherein an uneven portion for controlling the flow of the resin is formed on the outer surface of the protrusion.