JPH0239368B2 - JUSHIFUSHIGATAHANDOTAISOCHISEIKEIYOMOORUDOKANAGATA - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold die (hereinafter abbreviated as "mold") used when molding a resin-sealed semiconductor device.

Hereinafter, a mold for molding a resin-sealed semiconductor integrated circuit device (hereinafter abbreviated as "resin-sealed IC") will be explained as an example.

FIGS. 1A and 1B are a perspective view and a side view, respectively, showing the outer shape of an example of a resin-sealed IC.

Generally, the surface of the resin-sealed part of a resin-sealed IC is marked with an indication mark (a in the figure), as shown in Figure 1.
is printed. However, if the printing surface on which this display mark is printed is a smooth surface, the display mark is likely to disappear, so it is required that this printing surface be a satin surface. In order to make this printing surface a satin surface, the molding surface of the mold for molding resin-sealed IC must be a matte surface, but since the material of the mold is very hard, the molding surface must be made into a matte surface. It is not easy to create a pear-like surface using methods such as Yotsutoblasting. Therefore, conventionally, a mold consisting of a single plate-shaped body whose molding surface is made into a satin finish by cutting by electrical discharge machining has been widely used.

Fig. 2A is a plan view showing a conventional lower mold for molding resin-sealed ICs, and Fig. 2B is B- of Fig. 2A.
It is a sectional view taken along the B line.

In the figure, 1 is a lower mold, 2a has the same shape as the lower half of the resin-sealed part of the resin-sealed IC shown in FIG.
cavities that are cut by electric discharge machining so that they are aligned at intervals along the center line on one side of the body, and the IC elements are resin-sealed;
2b is a cavity formed on the surface of the lower mold 1 by electrical discharge machining in line symmetry with the cavity 2a with respect to the center line. 3 is a cavity formed on the surface of the lower mold 1 from the reference plane 1a to the cavities 2a and 2b. 3a is an air vent groove provided at the end of the runner 3 opposite to the reference surface 1a;
a and 4b are gates connecting the runner 3 and the cavities 2a and 2b, respectively;
a is a positioning pin for positioning and placing a lead frame (L _a indicated by a two-dot chain line) on which an IC element to be resin-sealed in the cavity 2a is mounted on the surface of the lower mold 1; Similarly, 5b is sealed with resin on the surface of the lower mold 1 within the cavity 2b.
This is a positioning pin for positioning and mounting the lead frame (L _b indicated by the two-dot chain line) on which the IC element is mounted. The upper mold has the same shape as the upper half of the resin-sealed part of the resin-sealed IC shown in FIG. 1 on the surface portion facing the cavities 2a and 2b of the lower mold 1. The cavity with which the locating pins 5a and 5b can be inserted is formed by electric discharge machining, and there are no locating pin insertion holes in the surface facing the locating pins 5a and 5b. Since it is the same as the mold 1, the explanation of the upper mold will be omitted and only the lower mold 1 will be described below.

The display mark printed surface of the resin-sealed IC molded using such a lower mold 1 is similar to the cavity 2a.
Since the molded surface of 2b and 2b is a satin surface obtained by electric discharge machining, it becomes a satin surface.

By the way, in this lower mold 1, the cavities 2a and 2 are aligned with respect to the reference plane 1a and the center line.
It is necessary to improve the positional accuracy of b, and it is necessary to make the dimensions, surface roughness, etc. of cavities 2a and 2b uniform. However, the positional accuracy of the cavities 2a and 2b is determined by the accuracy with which the electrical discharge machining electrode is attached to the lower mold 1 during electrical discharge machining, and even a slight deviation in the attachment of the electrical discharge machining electrode can be fatal. This is a very nerve-wracking and difficult task as it can result in defects. In addition, the electrical discharge machining for forming the cavities 2a and 2b is a bottoming process in which the periphery of the electrical discharge machining part of the electrical discharge machining electrode is surrounded. It is not easy to make the surface roughness uniform by the subsequent discharge. Furthermore, since the electric discharge machining time is long, the dimensions of the cavities 2a and 2b tend to become uneven due to wear of the electric discharge machining part of the electric discharge machining electrode.In order to eliminate this irregularity, a large number of electric discharge machining electrodes must be prepared. and need to be replaced frequently. Moreover, the shape of the electrical discharge machining part of the electrical discharge machining electrode is changed to cavities 2a and 2.
It is necessary to match the shape of b, which increases the manufacturing cost of the electrode for electrical discharge machining.

This invention was made in view of the above-mentioned problems, and by providing an assembly structure in which the cavity component parts can be separated, it is possible to correct the position of the cavity with respect to the reference plane of the mold, Another object of the present invention is to provide a mold for molding a resin-sealed semiconductor device that improves the machinability of the cavity by electrical discharge machining and is inexpensive to manufacture.

A mold according to an embodiment of the present invention used for molding the resin-sealed IC shown in FIG. 1 will be described below with reference to FIGS. 3 to 6. In this embodiment as well, the second
Similar to the conventional example shown in the figure, the upper mold is substantially the same as the lower mold, so a description of the upper mold will be omitted and only the lower mold will be described.

FIGS. 3A and 3B are a plan view and a side view, respectively, showing a base plate forming a part of the lower mold of this embodiment.

In the figure, 11 is the base plate of this embodiment made of a metal plate, 11a is a reference surface corresponding to the reference surface 1a of the lower mold 1 of the conventional example shown in FIG. 2, and 13 is the runner of the above conventional example. 3, 14a and 14b are gates corresponding to the gates 4a and 4b of the conventional example, and 15a and 15b are positioning pins corresponding to the positioning pins 5a and 5b of the conventional example.
16a has a groove width W equal to the length of the cavity 2a in the direction along the reference surface 1a of the conventional example, and a predetermined depth D.
Similarly, a cavity insert insertion groove is ground through a portion corresponding to the cavity 2a of the conventional example and extends to the end surface opposite to the reference surface 11a, and into which the cavity insert shown in FIG. 4 is inserted. Reference numeral 16b denotes a cavity insert insertion groove which has a groove width W and a depth D and is ground so as to pass through a portion corresponding to the cavity 2b of the conventional example.

FIGS. 4A, B, and C are a plan view, a side view, and a front view, respectively, showing a cavity insert forming a part of the lower mold of this embodiment.

In the figure, reference numeral 17 indicates the width W of the cavity insert fitting grooves 16a, 16b shown in FIG.
A rectangular main surface whose length is the length along the center line - of the cavity insert insertion groove 16
The cavity insert fitting groove 16a and the cavity insert fitting groove 16b are made of a metal quadrangular columnar body having a thickness D equal to the depth D of the cavities a and 16b.
Cavity inserts 18 are fitted into the respective holes and fixed to the base plate 11 shown in FIG. 3 by tightening screws.
is the end surface 1 of the exit surface of the cavity int 17.
7a is a reference plane, and is a lateral groove formed by electrical discharge machining in a portion corresponding to the cavities 2a and 2b from the reference plane 1a of the conventional example shown in FIG. The groove width of the lateral groove 18 is the same as the length in the direction along the center line of the cavities 2a and 2b, and its depth is the same as that of the cavity 2a, 2b.
The depth is the same as that of a and 2b.

FIGS. 5A and 5B are a front view and a side view, respectively, showing an end plate constituting a part of the lower mold of this embodiment.

In the figure, reference numeral 19 is fixed with a screw to the end surface of the base plate 11 shown in FIG. This is an end plate having side end surfaces and an air vent groove 19a formed in the center of the surface to communicate with the runner 13 of the base plate 11.

Next, FIG. 6 shows the state of the lower mold of this embodiment assembled with the base plate 11 shown in FIG. 3, the cavity insert 17 shown in FIG. 4, and the end plate 19 shown in FIG. A is a plan view of FIG. 6A, and FIG. 6B is a sectional view taken along the line BB of FIG. 6A.

When assembling the lower mold of this example, the third
Cavity insert fitting groove 16a and cavity insert fitting groove 16 of base plate 11 shown in the figure
4b, the cavity insert 17 is inserted and fixed to the base plate 11 by screwing so that the reference surface 11a of the base plate 11 and the end surface 17a of the cavity insert 17 shown in FIG. 4 are aligned. Thereafter, the end plate 19 shown in FIG. 5 is fixed to the end surface of the base plate 11 on the opposite side from the reference surface 11a with screws, thereby obtaining the lower mold of this embodiment shown in FIG. 6.

Next, a method of forming the lateral groove 18 of the cavity insert 17 of the lower mold of this embodiment shown in FIG. 4 will be explained with reference to FIGS. 7 and 8.

FIGS. 7A and 7B are front and side views showing enlarged main parts of the cavity insert 17 of the lower mold of this example, and FIGS. 8A and B are respectively of the lower mold of this example. FIG. 2 is a front view and a side view showing enlarged main parts of an electrode for electrical discharge machining used to form a lateral groove 18 of a cavity insert 17. FIG.

In FIG. 8, 20 is an electric discharge machining electrode used when forming the horizontal groove 18 of the cavity insert 17 of this embodiment by electric discharge machining, and 20a is the electric discharge machining electrode 20 used for forming the lateral groove 18 of the cavity insert 17.
This is an electric discharge machining section that is provided so as to correspond to the horizontal groove 18, has the same cross-sectional shape as the cross-sectional shape of the horizontal groove 18, and performs electric discharge machining.

When forming the lateral grooves 18 of the cavity insert 17 of this embodiment by electric discharge machining, first, as shown by the dashed line in FIG.
A lateral groove 18a having a cross-sectional shape slightly smaller than that of the lateral groove 18 is formed by grinding. Next, electrical discharge machining is performed by bringing the electrical discharge machining section 20a of the electrical discharge machining electrode 20 into contact with the horizontal groove 18a, and when the cross-sectional shape of the horizontal groove 18a is made into the cross-sectional shape of the electrical discharge machining section 20a, the horizontal groove 1 of the cavity insert 17
8 is formed.

In the lower mold of the embodiment configured as described above, the cavity corresponding to the cavity 2a of the conventional example shown in FIG. Insertion groove 1
It is composed of a recess formed at the intersection with the lateral groove 18 of the pear-finished surface formed by electric discharge machining of the cavity insert 17 fitted into the cavity insert 6a, and similarly, the cavity corresponding to the cavity 2b of the conventional example described above is smooth. It is composed of a recess formed at the intersection of the cavity insert fitting groove 16b on the surface and the structure groove 18 on the matted surface of the cavity insert 17 fitted in this fitting groove 16b. The display mark printed surface of the resin-sealed IC molded using a mold has a matte surface, and the end surface on the short side thereof is a smooth surface. Therefore, the resin-sealed IC molded using the lower mold of this embodiment whose short side end face is a smooth surface is different from the resin-sealed IC molded using the lower mold of the above conventional example whose entire surface has a satin surface. Better releasability than molded resin-sealed ICs. Also, the cavity insert 17 is inserted into the cavity insert insertion grooves 16a, 1 of the base plate 11.
By moving it within 6b, the position of the cavity in this embodiment, which is formed by the intersection of the fitting grooves 16a, 16b and the lateral groove 18 of the cavity insert 17, with respect to the reference surface 11a of the base plate 11 is corrected. Furthermore, even if the cavity insert 17 is damaged, it can be easily replaced with a new cavity insert. In addition, the horizontal groove 18 of the cavity insert 17
When forming the lateral grooves 18 in advance, the lateral grooves 18 are formed in the portions of the cavity insert 17 where the lateral grooves 18 are to be formed.
By cutting the horizontal groove 18a having a cross-sectional shape slightly smaller than the cross-sectional shape by grinding, it becomes possible to extremely reduce the electrical discharge cutting portion by the electrical discharge machining part 20a of the electrical discharge machining electrode 20, The electric discharge machining time is shortened, and the electric discharge machining section 2
0a consumption is reduced. Moreover, the electrical discharge machining section 2
The shape of 0a is the width W of cavity insert 17
There is no need to match the electrode 2 for electrical discharge machining.
0 manufacturing cost can be reduced. Furthermore, the electrical discharge machining by the electrical discharge machining section 20a is performed by the electrical discharge machining section 20a.
Since the side surface of a is open, cutting dust can be easily discharged to the outside, making it possible to prevent secondary discharge due to this cutting dust, and making the surface roughness uniform.

Although the explanation has been given using a resin-sealed IC molding mold as an example, the present invention is not limited to this.
It can also be applied to other molds for molding resin-sealed semiconductor devices.

As described above, in the mold for molding a resin-sealed semiconductor device of the present invention, the cavity insert insertion groove is formed by grinding on the base plate, and the cavity insert has at least the inner bottom surface and the inner wall surface. By forming a lateral groove cut by electrical discharge machining, and inserting the cavity insert into the cavity insert insertion groove, the intersection of the cavity insert insertion groove and the lateral groove is formed. The concave area formed by
It has the following effects.

That is, (a), the position of the cavity can be corrected by moving the cavity insert within the cavity insert insertion groove. (b) Even if the cavity insert is damaged, it can be easily replaced with a new one. (c) When forming the lateral groove in the cavity insert, a lateral groove with a cross-sectional shape slightly smaller than that of the lateral groove is formed in advance in the region of the cavity insert where the lateral groove is to be formed by grinding. By forming it in advance, it becomes possible to extremely reduce the portion to be cut and removed by electric discharge machining, thereby shortening the electric discharge machining time and reducing wear of the electric discharge machining electrode. (iv) In electrical discharge machining, the sides of the electrical discharge machining electrode are open, and cutting powder can be easily discharged to the outside.
It becomes possible to prevent secondary discharge due to this cutting powder, and the surface roughness can be made uniform.
(E) Since it is not necessary to match the shape of the electric discharge machining electrode to the width of the cavity insert, the manufacturing cost is reduced. (f) The cavity is composed of a recess formed at the intersection of the lateral groove on the matte surface formed by electrical discharge machining and the cavity insert insertion groove on the smooth surface formed by grinding, so it can be formed using this mold. The display mark printed surface of the molded product corresponding to the lateral groove is a satin surface, and the end surface corresponding to the cavity insert fitting groove is a smooth surface. Therefore, a molded product using this mold has better mold releasability than a molded product using a conventional mold whose entire surface has a satin finish.

[Brief explanation of drawings]

Figures 1A and B are a perspective view and a side view showing an example of the outer shape of a resin-sealed IC, respectively, and Figure 2A is
2 is a plan view showing a conventional lower mold for molding resin-sealed ICs, FIG. 2B is a sectional view taken along the line B-B of FIG. 2A, and FIGS. A plan view and a side view showing a base plate constituting a part of the lower mold of the example, and FIGS. 4A, B, and C each show a cavity insert constituting a part of the lower mold of the above example. A plan view, a side view, and a front view; FIGS. 5A and 5B are a front view and a side view, respectively, showing an end plate constituting a part of the lower mold of the above embodiment; FIG. 6A is a bottom view of the lower mold of the above embodiment. A plan view showing the assembled state of the mold, FIG. 6B is a sectional view taken along the line B-B of FIG. 6A, and FIGS. 7A and B are cavity inserts of the lower mold of the above example. 8A and 8B are enlarged front and side views showing the main parts of the cavity insert to explain the method for forming the lateral grooves in the lower mold of the above example. It is a front view and a side view which expand and show the principal part of the electrode for electrical discharge machining used for formation. In the figure, 11 is a base plate, 11a is a reference plane, 1
6a and 16b are cavity insert fitting grooves, 17 is a cavity insert, and 18 is a lateral groove. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1 Consisting of a metal plate-shaped body, a cavity insert insertion groove having a predetermined groove width and a predetermined depth is formed on the surface portion from one end face to the other end face on the opposite side by grinding. a rectangular main surface whose width is the groove width of the cavity insert insertion groove and the length between the two end faces of the base plate, and the depth of the cavity insert insertion groove. It consists of a metal rectangular prism-like body having a thickness not exceeding At least a portion of the inner bottom surface and inner wall surface of the lateral groove that opens on both end surfaces thereof is provided with a cavity insert formed by electrical discharge machining, and the cavity insert is fitted into the cavity insert insertion groove of the base plate. A resin-sealed type characterized in that a recess formed at the intersection of the cavity insert insertion groove and the lateral groove by inserting the lead frame into the lead frame is used as a cavity in which a semiconductor element mounted on the lead frame is resin-sealed. Mold for molding semiconductor devices.