JPH0839617A - Molded product and mold - Google Patents

Abstract

PURPOSE:To make gate residual length constant by holding a flat resin gate between a package main body and a resin gate to form a resin sump and concentrating stress to the boundary of the flat resin gate and the resin sump when the resin gate and the resin sump are removed to cut the flat resin gate. CONSTITUTION:A cavity 24 forming the package main body of a miniature molded product is formed to the mating surface of an upper mold 21 and a lower mold 22 and a mold gate 25 becoming an introducing port pouring a molten resin in the cavity 24 is formed to the mating surface 23 of the lower mold. The cross-sectional shape of the mold gate 25 becomes fine as approaches the cavity 24 to be continued to a resin sump forming recessed part 27 and one end of the mold gate 25 is connected to the other end of the flat mold gate 26 with a thickness of 0.2mm, a width of 0.3mm and a length of 0.1mm connected to the side surface of the cavity 24. The length of the flat mold gate 26 is set to a resin gate residue standard, for example, 0.1mm or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded product and a mold, and more particularly to a small molded product and a mold.

[0002]

2. Description of the Related Art For example, molded products are applied to electronic devices such as semiconductor devices and capacitors. Recently, as demands for downsizing have increased in electronic products and the like on which electronic parts are mounted, a small size of 1.3 mm x 0.8 mm x 0.7 mm is also used as an example of surface mount type electronic parts. It is made into a semi-finished product and is called a mini-molded product. The case where the mini-molded product is applied to a semiconductor device (for example, a diode) will be described below. The mini-molded product is resin-molded by a molding die as shown in FIG. As shown in FIG. 1, this molding die has a cavity 4 formed on the abutting surface 3 of an upper die 1 and a lower die 2 for forming a package main body of a mini-molded article. A mold gate 5 serving as an inlet for pouring the molten resin is formed on the abutting surface 3 of the lower mold. The cross-sectional shape of the mold gate 5 becomes narrower as it approaches the cavity 4, and the interface with the cavity 4 has a thickness of 0.2 mm and a width of 0.3 mm, for example. For resin molding with the above-mentioned mold, a lead frame (not shown) is inserted between the abutting surfaces 3. In the cavity 4, although not shown, a main portion of a lead frame having an island on which a semiconductor pellet is mounted and a lead electrically connected to the semiconductor pellet by a fine metal wire is arranged. Next, with the mold die closed and the lead frame clamped, a molten resin is injected and filled into the cavity 4 from the mold gate 5 to obtain the above-mentioned mini-molded product (see FIG. 4).
To form. Next, after opening the mold die, the mini-molded product is taken out to remove undesired resin other than the package body, and individual products are obtained from the lead frame.

[0003]

2. Description of the Related Art Next, another example of a conventional mini-mold molded article will be described.
Resin molding is performed with a molding die as shown in FIG. This mold is made up of the upper mold 1 as shown in FIG.
A cavity 14 is formed on the abutting surface 13 of the lower die 12 and the die 1 to form a package body of a mini-molded article, and a die gate 15 serving as an inlet for pouring the molten resin into the cavity 14 is provided. It is formed on the abutting surface 13 of the lower die. The shape of the mold gate 15 becomes narrower as it approaches the cavity 14, and is connected to the cavity 14 via a flat mold gate 16 having a thickness of 0.2 mm, a width of 0.3 mm and a length of 0.1 mm, for example. are doing. For resin molding with the above-mentioned mold, a lead frame (not shown) is inserted between the abutting surfaces 13. In the cavity 14, although not shown, a main portion of a lead frame having an island on which a semiconductor pellet is mounted and a lead electrically connected to the semiconductor pellet by a fine metal wire is arranged. Next,
With the mold die closed and the lead frame clamped, a molten resin is injected and filled from the mold gate 15 into the cavity 14 to form the mini-molded product (see FIG. 6). . Next, after opening the mold die, the mini-molded product is taken out to remove undesired resin other than the package body, and individual products are obtained from the lead frame.

[0004]

However, the mini-molded article (see FIG. 4) formed by the molding die of the conventional technique 1 (see FIG. 4) is most suitable for the resin gate 33 when the resin gate 33 is removed. Although it is easy to cut at the boundary 34 surface with the thin package body 31, there is a problem that a force is applied to the package body 31 and a resin chip 35 is generated. Further, the mini-molded product (see FIG. 6) molded by the molding die of the conventional technique 2 is cut by the flat resin gate 44 having the smallest cross-sectional area when the resin gate 43 is removed. However, the cutting position is not fixed, and variations occur in the remaining length of the undesired resin remaining after cutting (gate remaining length m). The remaining gate length varies from 0.0 mm to 0.1 mm, and the length including the package body 41 is 0.8 to 0.9 m.
The variation becomes larger with m. When the variation becomes large,
This causes variations in the position of the package body 41 when manufacturing a board on which electronic components are mounted.

[0005]

[Means for Solving the Problems] Means for solving the above problems are as follows.
In a mold for forming a cavity between the abutting surfaces of the upper die and the lower die, and forming a die gate on the abutment surface of the lower die to inject resin, the die is located near the cavity. The mold is a mold having a resin mold forming concave portion sandwiching a flat mold gate, and a molded product resin-molded by the mold.

[0006]

With the above mold, the molten resin flows from the resin pool forming recess to the flat resin gate on the cavity side. However, since the cross-sectional area between the two rapidly changes, the strain is concentrated at the boundary between the two. To do. Therefore, the resin gate is cut at the boundary between the resin reservoir and the flat resin gate. For this,
The remaining gate length is uniform, which facilitates subsequent positioning when mounting on a printed circuit board or the like.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A mini-molded product and its mold applied to a semiconductor device (for example, a diode) will be described as an embodiment of the molded product and its mold according to the present invention with reference to FIGS. The molded product of the present invention is resin-molded by a molding die as shown in FIG. As shown in the figure, this molding die includes an upper die 21 and a lower die 2
A cavity 24 forming a package body of a mini-molded product is formed on the abutting surface 23 of the second mold, and a mold gate 25 serving as an inlet for injecting the molten resin into the cavity 24 is formed on the lower mold. It is formed on the mating surface 23. The cross-sectional shape of the mold gate 25 becomes narrower toward the cavity 24 and is connected to the resin pool forming recess 27, and one end is connected to the side surface of the cavity 24. The thickness is 0.2 mm and the width is 0.3 m.
It is connected to the other end of a flat mold gate 26 having a length of m and a length of 0.1 mm. The length of the flat mold gate 26 is set to the resin gate remaining length standard, for example, 0.1 mm or less. At this time, the cross-sectional shape of the flat mold gate 26 may be made thinner as it goes away from the cavity 24. In order to mold the resin with the molding die described above, a lead frame (not shown) is inserted between the abutting surfaces 23. In the cavity 24,
Although not shown, the island on which the semiconductor pellets are mounted and the leads electrically connected to the semiconductor pellets by a fine metal wire
A main portion of the lead frame having a cord is arranged. Next, with the mold die closed and the lead frame clamped, the molten resin is transferred from the mold gate 25 into the cavity 24 via the resin pool forming recess 27 and the flat mold gate 26. Is injected and filled to form the mini-molded product shown in FIG. Next, after opening the mold, the mini mold molded product is taken out, and the resin gate 53 and the resin pool 55 are removed. The mini-molded product molded by the mold of the present invention is cut at this portion because the strain is concentrated on the interface between the resin pool 55 and the flat resin gate 52. At this time, if the flat mold gate 26 between the cavity 24 and the resin reservoir 27 is made thinner as it goes away from the cavity 24, it becomes easier to cut at the interface between the resin reservoir 55 and the flat resin gate 52. From this interface, the package body 51
Even if a cutting punch (not shown) is applied to a portion away from, it is cut at this interface. Therefore, the flat resin gate
By setting the length of the flat mold gate 26 to be equal to or less than the gate remaining length standard so that the length of the gate 52 is equal to or less than the gate remaining length standard, the gate remaining length is less than the standard. Next, the lead frame is cut to obtain individual products.

[0008]

The mini-molded product (FIG. 2) formed by the molding die of the present invention has the flat resin gate 52 and the resin pool 55 when the resin gate 53 and the resin pool 55 are removed. The stress concentrates on the boundary and is cut, and the remaining gate length is aligned.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of a mold of the present invention.

FIG. 2 is a cross-sectional view showing an embodiment of a molded molded product of the present invention.

FIG. 3 is a sectional view of an essential part showing a conventional example 1 of a mold for a mold.

FIG. 4 is a sectional view showing Conventional Example 1 of a molded product.

FIG. 5 is a sectional view of an essential part showing a second conventional example of a mold die.

FIG. 6 is a sectional view showing a second conventional example of a molded molded product.

[Explanation of symbols]

 22 Upper mold 22 Lower mold 23 Abutting surface 24 Cavity 25 Mold gate 26 Flat mold gate 27 Recess for forming resin pool

Claims (5)

[Claims] 1. A molded product, which is resin-molded in a cavity having upper and lower mold abutting surfaces, wherein a flat resin gate is sandwiched between the package body and the resin gate to form a resin pool. Molded product characterized by 2. The molded product according to claim 1, wherein the cross-sectional shape of the flat resin gate is made smaller as the distance from the cavity is increased. 3. A mold for forming a cavity between the abutting surfaces of an upper die and a lower die, forming a die gate on the abutting surface of the lower die, and injecting resin, in the vicinity of the cavity. A mold for molding, wherein the mold gate is provided with a recess for forming a resin pool with a flat mold gate interposed therebetween. 4. A mold according to claim 3, wherein the cross section of the flat mold gate is made smaller as the distance from the cavity is increased. 5. A mold according to claim 3 or 4, wherein the length of the flat mold gate is shorter than a predetermined value.