JPH0645382A - Resin injection mold - Google Patents

Abstract

PURPOSE:To provide a resin injection mold which has long life and in which its molding yield is more improved. CONSTITUTION:A cavity 4 and a runner 5 in contact with thermosetting synthetic resin of an upper mold 2 and a lower mold 3 are covered with titanium nitride film 8 thereby to enhance a surface hardness of a resin injection mold 1, thereby increasing a strength against an impact at the time of molding. Thus, a life of the mold is prolonged, its releasability is improved, deformation, crack generated at the time of releasing a molded product are reduced, and a molding yield is improved. Further, resin N scarcely adheres to the mold, and a frequency of cleaning the mold is reduced. In addition, an irregularity in thicknesses of the films 8 is reduced, accuracy of a size of the mold is improved, and an additional operation is not required.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molding die used when a semiconductor device package is formed using a thermosetting synthetic resin.

[0002]

2. Description of the Related Art As is well known, there are semiconductor devices in which a semiconductor chip mounted on a lead frame is sealed with an epoxy thermosetting synthetic resin to form a package.

Conventionally, resin molding performed by molding such a thermosetting synthetic resin is performed by transfer molding. The molding die used is such that the surface of the runner through which the synthetic resin flows and the cavity to be molded into a predetermined package shape are smoothed, and the surface of the smoothed surface is coated with hard chrome with a thickness of 2 to 5 μm. It has been subjected.

However, in the above prior art,
Hard chrome plating is applied to the surface of the mold that comes in contact with the synthetic resin, and the plating film enhances the hardness of the surface, as well as improves rust prevention and mold release of molded products. , The surface hardness is increased to extend the mold life so that more molding processes can be continuously performed, and the mold releasability is also improved to eliminate the deformation and cracks that occur during mold release and improve the molding yield. In addition, it is required to reduce the frequency of cleaning the mold by reducing the adhesion of resin residue to the mold.

On the other hand, although the hard chrome plating can make the film thickness relatively thin, the range of film thickness variation may become as large as 5 μm or more in some cases, and the film thickness may be, for example, 150 mm in length and 200 mm in width. When an attempt was made to perform hard chromium plating of 5 μm, the thickness of the plated film was 7 to 10 μm, and although the variation range of the film thickness was about 3 μm, the average value of the film thickness could not be set to a predetermined value of 5 μm. It is difficult to obtain a predetermined film thickness.

For this reason, in a compact package such as a semiconductor device having a high degree of integration and having a large number of outer leads at a narrow pitch, which requires high precision so as not to be unsightly in appearance, a molding die is used after plating. Measure the dimensions of the main part of the mold and the assembled parts to be assembled.
Then, extra work such as adjustment and assembly such as selection of combined parts and selective assembly must be performed so that each part has a predetermined dimension when assembled as a molding die and no gaps are formed, and the accuracy of the die dimension is improved. There is also a demand for improvement.

[0007]

As described above, conventionally, the surface of the mold is hard chrome plated to increase the surface hardness and improve the mold releasability. However, the mold life is longer and the mold release is better. It is required that the molding yield is improved by further improving the moldability and that extra work is not required even when the mold dimension requires high accuracy. The present invention has been made in view of such a situation, and the purpose thereof is to have an extra work even if the die life is long, the molding yield is further improved, and high die dimensional accuracy is required. Not to provide a resin molding die.

[0008]

The resin molding die of the present invention is a resin molding die for molding by introducing a thermosetting synthetic resin into a cavity through a runner, and is in contact with the thermosetting synthetic resin. The titanium compound film is deposited on the surfaces of the cavity and the runner, and the titanium compound film is titanium nitride.

[0009]

In the resin molding die constructed as described above, a titanium compound film such as titanium nitride is deposited on the surfaces of the cavity and the runner which come into contact with the thermosetting synthetic resin, whereby the surface of the die is formed. The hardness becomes high and the strength against abrasion etc. due to resin flow during molding increases and the mold life extends,
In addition, the mold releasability is also improved, and the deformation and cracks that occur during mold release of the molded product are reduced, the molding yield is improved, and the resin residue is less likely to adhere to the mold, so the frequency of cleaning the mold is reduced. Become. Further, the variation in the film thickness of the deposited titanium compound film is small, the precision of the mold dimension is improved, and no extra work is required.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 is a partial cross-sectional view, FIG. 2 is a plan view of a main part of a lower mold, FIG. 3 is a perspective view showing a part of FIG. 2 in an enlarged manner, and FIG. 4 is for explaining a molding state. FIG. 5 is a perspective view of the molded product.

1 to 3, the resin molding die 1 is shown.
Is a split mold which is composed of an upper mold 2 and a lower mold 3 and which is divided in the vertical direction. The molds 2 and 3 each have a plurality of substantially square cavities 4 matched to a predetermined shape of a molded product. It has been cut down. Also, for both molds 2 and 3, a resin molding mold 1
A runner 5 for introducing a thermosetting synthetic resin for molding the cavity 4 from the outside is cut.

The runner 5 includes a main runner portion 6 for introducing a thermosetting synthetic resin into the resin molding die 1 from the outside, and a branch runner portion for feeding the thermosetting synthetic resin from the main runner portion 6 to each cavity 4. 7, the branch runner portion 7 has one end connected to a corner portion of the cavity 4 and opened into the cavity 4. In addition, 4a is an air vent and 7a is a gate. The shape of the runner 5 and the connection position to each cavity 4 are appropriately determined depending on the flow of the thermosetting synthetic resin in the cavity 4, the curing state, and the like.

A titanium nitride (TiN) film 8 having a thickness of 3 μm is uniformly deposited on the surfaces of the cavity 4 and the runner 5 which are directly contacted with the thermosetting synthetic resin during resin molding. Reference numeral 9 indicated by a chain double-dashed line indicates a lead frame mounted between the upper mold 2 and the lower mold 3 of the resin molding mold 1 during molding.

Then, the resin molding die 1 is manufactured by forming a cavity 4 and a runner 5 of a predetermined shape in each of metal blocks such as high-speed steel which is a base material of the upper die 2 and the lower die 3. After manufacturing the combined parts and the like to be attached to the cavity 4 and the runner 5, the surface of the cavity 4 whose surface is reflected on the surface of the molded product and the surface of the runner 5 are made smooth. Can be finished.

On the surfaces of the cavity 4 and the runner 5 which have been finished to be smooth, the treatment conditions are set so that the titanium nitride film 8 has a predetermined value in the range of 3 μm to 6 μm by a known ion plating method. And then put on.
Incidentally, when the film thickness of the deposited titanium nitride film 8 is 3 μm, the variation in the film thickness is about 0.3 μm and the film thickness is 10 μm.
It is very small, less than or equal to%.

After the titanium nitride film 8 is thus deposited, the upper mold 2 and the lower mold 3 appropriately combine the respective combination parts to complete the resin molding mold 1.
The resin molding die 1 is provided with a guide pin, a knock pin (not shown), a heater or the like for maintaining the die temperature at a predetermined value.

Then, the molding using the resin molding die 1 thus constructed is carried out as follows. That is, the resin molding die 1 is attached to a molding machine (not shown) and transfer molding is performed. First, as shown in FIG. 4, a lead frame 9 in which a synthetic resin package is formed is arranged between the upper mold 2 and the lower mold 3 of the resin molding mold 1.

A semiconductor chip 11 attached by bonding to the tip of the inner lead 10 is attached to the lead frame 9 at a predetermined pitch. When the lead frame 9 is mounted on the resin molding die 1, the semiconductor chip is attached. 11 is located substantially in the center of the cavity 4.

Next, the upper mold 2 and the lower mold 3 are closed, the lead frame 9 is mounted on the resin molding mold 1, and then the epoxy-based thermosetting is performed in the resin molding mold 1 through the main runner portion 6 of the runner 5. Synthetic resin is introduced. The introduced thermosetting synthetic resin flows from the main runner portion 6 through each branch runner portion 7 and is introduced into each cavity 4 through the gate 7a, and the thermosetting synthetic resin is filled in the cavity 4. At this time, the air in the cavity 4 is evacuated through the air bleeder 4a.

Then, the thermosetting synthetic resin in the cavity 4 and the runner 5 is heated and pressed for a predetermined time to be cured and molded. After that, the upper mold 2 and the lower mold 3 are opened, and the lead frame 9 is removed from the resin molding mold 1. The resin cured in the runner 5 is removed from the removed lead frame 9,
The lead frame 9 in which the semiconductor chip 11 is resin-sealed by the package 12 formed following the shape of the cavity 4 as shown in FIG.

In this embodiment having such a structure, the surfaces of the cavity 4 and the runner 5 that are in direct contact with the thermosetting synthetic resin of the resin molding die 1 are relatively thin and have very little variation in film thickness. Since the titanium nitride film 8 is deposited,
Even in molding that requires dimensional accuracy, it is not necessary to perform extra work such as readjustment and reassembly of the mold. Further, it is possible to prevent the appearance defect of the molded package 12 from occurring.

The surfaces of the cavity 4 and the runner 5 are
The hardness is 2000 Vg / mm in Vickers hardness (Hv)
Has ² or more hard titanium nitride films 8 and 800 kg / m in Vickers hardness (Hv) of the conventional hard chromium plating film
Since it is harder than m ^{2 to} 1100 kg / mm ^2, it is possible to increase the number of molded products that can be molded with one mold,
Mold life can be extended.

Further, the releasability of the package 12 molded in the cavity 4 and the unnecessary member hardened by the runner 5 is further improved, the package 12 is not deformed or cracked, and the molding yield is improved. The adhesion of resin residue to the resin molding die 1 is reduced, the frequency of cleaning the die is reduced, and the efficiency of the molding operation is improved.

In the above embodiment, the titanium nitride film 8 is deposited on the surfaces of the cavity 4 and the runner 5 which are in contact with the thermosetting synthetic resin of the resin molding die 1, but a titanium carbide (TiC) film or the like is used. Other titanium compound films may be deposited,
The present invention can be implemented with appropriate changes within the scope not departing from the gist.

[0025]

As is apparent from the above description, according to the present invention, the life of the mold is extended by forming the titanium compound film on the surfaces of the cavity and runner which are in contact with the thermosetting synthetic resin. Further, the molding yield is further improved, and even when high mold dimensional accuracy is required, extra work is not required.

[Brief description of drawings]

FIG. 1 is a partial sectional view showing an embodiment of the present invention.

FIG. 2 is a plan view of an essential part showing a lower mold in the above.

3 is an enlarged perspective view showing a part of FIG. 2. FIG.

FIG. 4 is a perspective view shown for explaining a molding state according to an embodiment of the present invention.

FIG. 5 is a perspective view of a molded product of the above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Resin molding die 2 ... Upper die 3 ... Lower die 4 ... Cavity 5 ... Runner 8 ... Titanium nitride film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B29L 31:34 4F

Claims (2)

[Claims] 1. A resin molding die for molding by introducing a thermosetting synthetic resin into a cavity through a runner,
A resin molding die, wherein a titanium compound film is deposited on the surfaces of the cavity and the runner which are in contact with the thermosetting synthetic resin. 2. The resin molding die according to claim 1, wherein the titanium compound film is titanium nitride.