JPH07137082A - Mold for resin molding - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the releasability of molded packages and cured resins, and to improve the slidability of ejector pins and plungers. [Structure] The entire surface of the upper mold (1/20) and the lower mold (2:30), or the cavities (3, 4) and pots (5) of the respective constituent members
・ 21), plunger (6 ・ 22), resin passage (10 ・ 11 ・ 19), cull (1
2.28) and recesses (9) and other contact surfaces with the molten resin material, by forming an amorphous chrome plating layer A, a substantially perfect smooth surface without many fine cracks on both mold surfaces. Make up.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to electronic parts such as, for example,
The present invention relates to an improvement of a resin molding die for sealing and molding a semiconductor or the like with a resin material.

[0002]

2. Description of the Related Art Conventionally, semiconductors and the like have been resin-sealed by a transfer molding method.
This method is usually performed as follows using a resin molding die.

First, the upper mold and the lower mold of the resin molding die are heated in advance to the resin molding temperature by a heating means such as a heater. Next, a lead frame on which a semiconductor or the like is mounted is fitted and set at a predetermined position of a recess provided on the mold surface of the lower mold, and a resin material is supplied into the pot. Next, the lower mold is moved upward and the upper and lower molds are clamped. At this time, the semiconductor and the lead frame around the semiconductor are fitted and set in both upper and lower cavities opposite to the upper and lower mold parting line (PL) surfaces. Next, the resin material in the pot is pressed by the plunger, and the molten resin material heated and melted by the heating means is passed through a resin passage provided between the pot and the upper and lower cavities to form the upper and lower cavities. Fill inside. At this time, the semiconductor and the like and the lead frame in the periphery thereof are sealed in a package molded corresponding to the shapes of the upper and lower cavities. Next, after the resin is cured, the lower mold is moved downward to open the upper and lower molds, and substantially simultaneously with the mold opening of the upper and lower molds, a mold release mechanism such as an ejector pin is used to move the inside of the both molds. The cured resin in the package, the lead frame, and the resin passage is projected between the upper and lower molds and separated from each other.

For the purpose of improving hardness and wear resistance, for example, hard chrome plating has been performed on the mold surfaces of both molds and the surfaces of ejector pins.

[0005]

As described above, conventionally, a hard chrome plating layer is formed on the surface of each mold member of a resin molding mold to improve the hardness and wear resistance of the mold. Is being carried out. However, a large number of fine cracks are formed in the above-mentioned hard chrome plating layer, and in recent years, it has been attempted to reduce the viscosity of the resin material that has been heated and melted due to the demand for improved semiconductor quality. Therefore, when the resin encapsulation molding is performed using such a resin material, the molten resin material easily enters the cracks of the hard chromium plating layer described above, which causes various problems. .

That is, with the decrease in viscosity of the molten resin material,
When the molten resin material enters into the cracks of the hard chrome plating layer formed on the inner surface of the cavity described above, the releasability of the package (resin molding) molded in a so-called undercut state is improved. There are problems such as deterioration. In addition, with the decrease in viscosity of the molten resin material,
It has been pointed out that the cured resin easily forms a burr on the surface of each mold member of the mold and adheres to the mold member, which adversely affects the durability and the like of the mold. Further, in order to remove this burr, cleaning means using a rotating brush or the like is provided, but there is a problem that the cleaning means cannot obtain a sufficient removing effect. Further, since the burr cannot be sufficiently removed by the above-mentioned cleaning means, the burr overlaps and adheres to the surface of the mold when the number of moldings is repeated, which causes an adverse effect such as indentation on the parting line surface of the mold.

Further, with the decrease in viscosity of the molten resin material,
In particular, a problem has arisen in each mold member that reciprocates in the mold, for example, an ejector pin. For example, as shown in FIG. 6, there is a problem that a molten resin material adheres to the surface of the ejector pin 25 in the ejector portion 24 and is hardened to easily generate a resin dregs 27. Mating hole
There is an adverse effect that it gets into the gap between the inner surface of 26 and the ejector pin 25 to reduce the slidability of the ejector pin 25, and finally the ejector pin 25 becomes unable to slide. In addition, such a problem of poor sliding between the ejector pin 25 and the fitting hole 26 also occurs between the mold pot and the plunger under the same conditions.

In addition, the resin material that has been heated and melted has a reduced viscosity due to the demands for lowering the stress and improving the moisture resistance of the molded package, and the adhesiveness to the mold surface that is in contact with the molten resin material. Tends to be stronger, especially
The adhesion to the cavity surface of the mold is strong. Further, in the case of the ejector pin, the molten resin material penetrates into the sliding clearance (gap), and the clamping force of the ejector pin increases due to the high adhesion of the molten resin material,
Since the hard chrome plating that has been surface-treated conventionally is crystalline, even fine cracks (microcracks) that have occurred have come to affect the slidability of the ejector pin. Then, this invention pays attention to the surface treatment of the amorphous chromium plating which a fine crack does not generate | occur | produce, and it aims at providing the metal mold | die which can improve the mold release property of the molded package and hardening resin. Another object of the present invention is to provide a mold capable of improving the slidability of the sliding member in the mold. Another object of the present invention is to provide a sliding member having good slidability.

[0009]

A resin molding die according to the present invention for solving the above-mentioned technical problem is obtained by heating and melting a resin material supplied into a pot and pressurizing it with a plunger. A resin molding die for injecting the molten resin material into the cavity through a resin passage by forming an amorphous chrome plating layer on at least the surface of the die member in contact with the molten resin material. Characterize.

Further, a resin molding die according to the present invention for solving the above technical problem is characterized in that an amorphous chromium plating layer is formed on the surface of an ejector pin in a die member. .

Further, the resin molding die according to the present invention for solving the above technical problem is characterized in that an amorphous chromium plating layer is formed on the surface of the plunger of the die member.

[0012]

Since the amorphous chromium plating layer is formed on the surface of each mold member in the resin molding mold according to the present invention, the mold releasability of the package is improved and the resin burr is easily separated from the mold. can do.

Further, since the amorphous chrome plating layer is formed on the surface of the ejector pin, resin residue does not adhere to the surface of the ejector pin, and the slidability of the ejector pin can be maintained.

Further, since the amorphous chrome plating layer is formed on the surface of the plunger, resin residue does not adhere to the surface of the plunger, and the slidability of the plunger can be maintained.

[0015]

The present invention will be described in detail below with reference to the drawings of the embodiments. FIG. 1 is a vertical cross-sectional view of a mold according to the present invention, showing a state in which both upper and lower molds are clamped. FIG. 2 is a plan view of a mold corresponding to FIG. 1 and shows a mold surface of a lower mold. FIG. 3 is a vertical cross-sectional view of the ejector portion in FIGS. 1 and 2, showing a state in which an ejector pin that slides back and forth protrudes into the cavity. Figure 4
[Fig. 6] is a vertical cross-sectional view of another embodiment according to the present invention, showing a state in which both upper and lower molds are clamped. FIG. 5 is a plan view of the mold corresponding to FIG. 4, showing the mold surface of the lower mold.
In the drawings, the same reference numerals are given to the same mold members. Also, the shaded portion in the figure indicates the amorphous chromium plating layer (A).

The resin molding die shown in FIG. 1 comprises an upper die 1 and a lower die 2. The upper and lower molds (1 and 2) are respectively provided with cavities (3 and 4) for resin molding so as to face each other. Further, the lower mold 2 shown in FIGS. 1 and 2 is provided with a pot 5 for supplying the resin material R, and the pot 5 is fitted with a plunger 6 for pressurizing the resin material R in the pot. Has been done. Further, the lower mold 2 is provided with a recess 9 for fitting and setting the lead frame 8 having the semiconductor 7 mounted therein at a predetermined position. In addition, a resin passage (gate) 10 is formed in communication with the cavity 4 of the lower mold 2, and the upper mold 1 is provided with a plunger 6 to form a pot 5.
A cull 12 is provided for receiving a molten resin material transferred under pressure from a mold and distributing it to a resin passage 11. The pot 5 and the lower mold cavity 4 are the molds of both molds (1, 2) shown in FIG. It is provided so as to communicate with each other via the cull 12 and both resin passages (10, 11) when tightened. In addition, both upper and lower types (1/2),
Package molded in cavity (3, 4) (not shown)
And ejector pin (1) for ejecting resin (not shown) cured by resin passage (10/11) or cull 12
3 ・ 14) are provided. In addition, both upper and lower types (1/2),
Fitting holes (15, 16) for ejector pins (13, 14) are provided. Further, an amorphous chromium plating layer A is formed on the entire surface of the above-mentioned molds (1, 2), or on at least the contact surface of the constituent members of each mold with the molten resin material. Therefore, the mold surface on which the plating layer A is formed is
It will be configured as a substantially perfect smooth surface without many fine cracks such as a hard chrome plating layer.
For this reason, when resin molding is performed using both molds (1 and 2), the releasability from the above-mentioned package and cured resin is extremely good, and burr adhesion to the surface of both molds can be reliably prevented. . Therefore, the durability of the mold itself is improved, and labor saving or omission of the cleaning work can be achieved to achieve high efficiency production.

Next, the present invention will be described in more detail by taking the ejector portion 23 of the lower mold 2 shown in FIG. 3 as an example. An ejector pin 13 is fitted in a fitting hole 15 in an ejector portion 23 shown in FIG. 3, and the ejector pin 13 is provided so as to slide up and down by a vertically moving mechanism (not shown). Further, as described above, the amorphous chromium plating layer A is formed on the surface of the ejector pin 13 and the surface of the cavity 4, respectively. The amorphous chromium plating layer A may be formed on the inner surface of the fitting hole 15 of the ejector pin. The above-mentioned amorphous chromium plating layer is amorphous, its surface is smooth and no cracks are observed. The amorphous chromium plating layer has high hardness, excellent wear resistance, corrosion resistance, heat resistance, oxidation resistance, and the like, and has a small dynamic friction coefficient.
Therefore, the ejection of the package by the ejector pin 13 can be favorably performed. Further, it is possible to reliably prevent the resin residue from adhering to the ejector pin. Furthermore, since the sliding resistance of amorphous chrome plating is small, the slidability of the ejector pin becomes good,
The durability can be improved.

An amorphous chromium plating layer A is similarly formed on each surface of the plunger 6 which slides reciprocally and the inner surface of the pot 5 which houses the plunger 6 and the resin material R shown in FIG. Therefore, when resin molding is performed similarly to the ejector pin described above, the slidability of the plunger is improved and the durability thereof can be improved.

Next, another embodiment shown in FIGS. 4 to 5 will be described. That is, the resin molding die shown in FIGS. 4 to 5 is composed of the upper die 20 and the lower die 30. Further, as shown in FIG. 5, the lower mold 30 described above is provided with a rectangular pot 21 that is elongated in a plan view, and the rectangular pot 22 has a rectangular plunger corresponding to the pot shape. 22 is fitted. In addition, the rectangular pot 21 in both types (20 and 30) described above
A large number of cavities (3, 4) are arranged facing each other on both sides of the rectangular pot 21, the cull 28 and a short resin passage (gate) 19 respectively. It is connected to each other via. In addition, a molded package (not shown) and a resin passage 19 are provided on both molds (20, 30).
Ejector pins (13, 14) for releasing the cured resin therein and fitting holes (15, 16) for the ejector pins are provided. Further, an amorphous chrome plating layer A is formed on the entire surface of both molds (20, 30) or at least the contact surface of the constituent members of each mold with the molten resin material. Therefore, even when resin molding is performed using both the molds (20 and 30), the mold releasability from the above-mentioned package and the cured resin is extremely good, as in the case of the above-mentioned embodiment. It is possible to reliably prevent burrs from adhering to the surface of the mold and also improve the durability of the mold itself. Further, as in the case of the above-described embodiment, the ejection of the package by the ejector pin can be favorably performed, and the resin residue can be reliably prevented from adhering to the ejector pin. In the rectangular plunger and the rectangular pot as well, similar to the ejector pin, when the molten resin material is pressed into the rectangular pot to form a resin, the slidability of the rectangular plunger becomes good and the like. , Its durability can be improved.

The present invention is not limited to the above-mentioned embodiments, but can be arbitrarily and appropriately modified / selected as needed within the scope of the gist of the present invention. Is. For example, the number of ejector pins and their fitting holes, the arrangement positions, and the like can be changed as appropriate. Further, a multi-plunger mold configuration in which the number of rectangular pots and rectangular plungers shown in FIGS. 4 to 5 is two or more may be adopted.

[0021]

The mold according to the present invention is formed by forming an amorphous chrome plating layer on at least the contact surface with the molten resin material on the surface of each mold member constituting the mold. Also, the excellent releasability of the package and the cured resin is improved.

In particular, since the amorphous chrome plating layer is formed on at least the contact surface of the ejector pin or the plunger with the molten resin material, it is possible to reliably prevent the cured resin from adhering to those surfaces. It has an excellent practical effect that the slidability of the ejector pin and the plunger can be remarkably improved.

Further, according to the present invention, an amorphous chromium plating layer is formed on the surface of a sliding member such as an ejector pin or a plunger by surface treatment, and slidability between the sliding member and its fitting hole is improved. Is improved, so that it is possible to provide a sliding member having good slidability, which is an excellent practical effect.

[Brief description of drawings]

FIG. 1 is a partially cutaway vertical sectional view of a main part of a resin molding die according to the present invention, showing a clamped state of both upper and lower molds.

FIG. 2 is a plan view showing a die surface of a lower die of the die corresponding to FIG.

FIG. 3 is a partially cutaway vertical sectional view of an ejector portion of a lower die of the die corresponding to FIG. 1.

FIG. 4 is a partially cutaway vertical sectional view showing another embodiment of the mold according to the present invention, showing a mold clamping state of both upper and lower molds.

5 is a plan view showing a die surface of a lower die which is a die corresponding to FIG. 4. FIG.

FIG. 6 is a partially cutaway cross-sectional view of an ejector portion in a conventional resin molding die, and is an explanatory diagram of a sliding defect of the ejector pin.

[Explanation of symbols]

 1 Upper mold 2 Lower mold 3 Cavity 4 Cavity 5 Pot 6 Plunger 9 Recess 10 Resin passage 11 Resin passage 12 Cull 13 Ejector pin 14 Ejector pin 15 Fitting hole 16 Fitting hole 19 Resin passage 20 Upper die 21 Rectangular pot 22 Rectangular Plunger 23 Ejector part 28 Cull 30 Lower mold R Resin material A Amorphous chrome plating layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01L 21/56 T 8617-4M // B29L 31:34

Claims (3)

[Claims] 1. A resin molding die for injecting a molten resin material into a cavity through a resin passage by heating and melting the resin material supplied into a pot and pressurizing the molten resin material with a plunger. A resin molding die, comprising an amorphous chrome plating layer formed on the surface of the die member in contact with a molten resin material. 2. A resin molding die, comprising an amorphous chrome plating layer formed on a surface of an ejector pin of a die member. 3. A resin molding die, comprising an amorphous chromium plating layer formed on the surface of a plunger of the die member.