JPH07214598A - Die device for resin sealing - Google Patents

Abstract

PURPOSE:To seal airtightly with an uncured resin which melts and cures satisfactorily without wasting a resin. CONSTITUTION:A die device for resin sealing is equipped with a plunger 34 provided at a specified interval from a cavity area 33 formed by a top force 31 and a bottom force 32 of a die and so constructed as to plunge a resin material 4 in a vertical direction, against the contact surfaces of the top and the bottom force. Further, the tip of the plunger is introduced into a notched part in such a state that a lead frame with the notched part formed toward an outer area from a package line so that a semiconductor chip is positioned in the cavity area 33. A sealing resin pressurized by the tip of the plunger is injected into the cavity area from a direction in parallel with the main surface of the lead frame, through the notched part, and the resin sealing is achieved.

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 device, and more particularly to a structure of a sealing resin filling portion.

[0002]

2. Description of the Related Art A resin-sealed semiconductor device is mainly obtained by a transfer molding method. In this method, uncured resin such as epoxy molding material mainly composed of epoxy resin and filler is heated and melted, poured into a mold using a transfer molding machine, and molded in a high temperature and high pressure state, It is a method of encapsulating a semiconductor chip mounted on a lead frame by curing. The resin-encapsulated semiconductor device manufactured by this method is excellent in reliability because the semiconductor chip is completely covered with the epoxy resin composition, and the package appearance is good because it is densely molded with a mold. Therefore, most resin-encapsulated semiconductor devices are currently manufactured by this method.

Further, as the size of semiconductor chips has increased in recent years due to the higher integration of semiconductor devices, the package of resin-encapsulated semiconductor devices has also increased in size, while the package has become thinner with the miniaturization of the mounting space. The tendency is becoming stronger, and this tendency is expected to become stronger in the future.
However, in the transfer molding method, there is a problem in that the die device used for transfer molding becomes even larger. Usually, in transfer molding, the lead frame 1 as shown in FIG. 11 is sandwiched so that the chip 2 is located in the cavity formed by the cavity block C, and provided on the sub-runner SR, as shown in FIG. A method of injecting a sealing resin into the cavity through the gate G and performing pressure molding is adopted. However, according to this method, the gate G is located on one surface of the lead frame 1, and a shadow of the lead frame 1 is formed in the inflowing resin, and bubbles may be generated at this position. These bubbles become voids (cavities) and cause the intrusion of water.

In order to solve this problem, there has been proposed a method of forming a runner groove through which a sealing resin flows, and making the cavity communicate with each other so as to inject the sealing resin from the side surface of the lead frame. There is
No. 66).

[0005]

However, in this method, the resin material for sealing is supplied to the mold through the plunger, but the mold is called curl and smoothes the running of the resin. A resin pressurizing section, a runner that is a resin running groove, and a sub-runner that is connected to this as a guide groove that is connected to the gate, and a gate is formed at this end. Since the resin is injected, the resin also remains in the curls, runners, sub-runners, and gates, and there is a problem that the resin is wasted. Furthermore, the formation of such a gate has extremely high precision in forming a shape such as setting an injection angle, and when it is provided on the upper mold side, the upper part is filled first and a cavity is easily formed, so that the mold is uniformly formed. It is extremely difficult to fill the resin with. Moreover, it is not easy to determine the shape and position of the gate in order to uniformly fill the resin. Further, depending on the composition of the resin, the viscosity of the sealing resin material at the time of melting may be high, and the cavity may not be smoothly filled and may remain. In addition, when a plurality of plungers are molded at the same time, the time required for the resin to reach the cavity is different due to the difference in distance from the plunger, which causes a problem that the curing time varies. Further, there is a problem that warpage is likely to occur if the curing time varies as the package becomes thinner. In addition, the resin material also contains a hard substance that wears the mold, and there is also the problem that maintenance is required such as replacing the mold because the gate wears and the injection amount of the resin material fluctuates. It was

The present invention has been made in view of the above-mentioned circumstances, and has a simple device configuration, does not waste resin material, and allows a sealing resin to be melted and cured in a good state for precise resin sealing. It is to provide a mold for resin encapsulation that can be performed.

[0007]

Therefore, the resin sealing mold of the present invention is provided so as to be separated from the cavity region formed by the upper mold and the lower mold by a predetermined distance. And a plunger configured to push out the material resin in a direction perpendicular to the contact surface of the semiconductor chip, and the semiconductor chip is placed in the cavity area when the lead frame with the cutout portion formed outward from the package line is formed. The tip of the plunger is inserted into the cutout portion while being sandwiched between the contact surfaces of the upper die and the lower die so as to be positioned, and is parallel to the main surface of the lead frame through the cutout portion. In this direction, the cavity region is filled with a sealing resin that is pressed by the tip of the plunger to perform resin sealing.

[0008]

According to the above construction, it is not necessary to provide a runner portion, a sub-runner portion, or a curl in the mold device, so that the construction of the sealing device can be simplified. Further, the sealing resin can be filled at a position extremely close to the cavity region where the package is formed, and this filling port is highly accurately defined by the width of the notch formed in the lead frame and the thickness of the lead frame. No advanced technology is required to form the mold device.

Further, by utilizing a gap formed between the plunger and the notch formed in the lead frame and corresponding to the thickness of the lead frame, the plunger is pressed against the side wall to cause the reaction to flow into the cavity region. As described above, the resin is rectified by accelerating, and a uniform resin flow is formed. Therefore, it is possible to perform a dense filling without generating bubbles. Since this injection position is the position (level) of the lead frame, compared to the conventional case where a mold with a gate is used and injection is performed obliquely from the upper and lower molds, the shadowed part of the lead frame It is possible to prevent the formation of cavities, so that uniform and smooth injection can be performed.

Therefore, even if the resin material has a high viscosity when melted, the cavity can be smoothly filled without causing retention.

Further, since one plunger is used to perform one molding and the distance from the plunger is extremely short,
Needless to say, there is no waste of resin, and there is no problem that the time for the resin to reach the cavity is different and the curing time varies. Therefore, even in the case of a thin package, warping does not occur, and it is possible to provide a resin-encapsulated semiconductor device having excellent moisture resistance and extremely high reliability. Further, since the gate is provided as a guide portion on the lead frame instead of the mold, there is no need for maintenance due to wear of the mold, and the cost is reduced.

The lead frame used here is
In a lead frame provided with a plurality of inner leads radially formed so as to surround the semiconductor chip mounting portion and an outer lead connected to each inner lead, a package line A guide portion having a predetermined width and a predetermined length in a predetermined area and the guide portion are continuously provided,
It is characterized in that a through hole formed from an arc portion having an arc-shaped edge having a diameter larger than the width is provided outward. The diameter of the arc of the arc-shaped edge of the through hole is set to be slightly larger than the diameter of the plunger, and the molten resin is formed in the area formed by the arc portion of the through hole and the periphery of the plunger. Press with a plunger. Then, the pressed resin passes through the guide portion by the reaction from the arcuate edge, is rectified there, and is smoothly filled in the cavity region. That is, the guide portion functions as a gate, and the circular arc portion functions as a curl.

Further, in manufacturing a semiconductor device using this device, a plurality of inner leads radially formed so as to surround the semiconductor chip mounting portion, and each inner lead.
An outer lead connected to the lead,
A through hole formed by a guide portion having a predetermined width and a predetermined length in a predetermined region of the package line and an arc portion continuous with the guide portion and having an arc-shaped edge having a diameter larger than the width is formed. A step of preparing the lead frame provided, an upper die, a lower die, and a cavity region formed by the upper die and the lower die, which are provided apart from each other by a predetermined distance, and are provided in a direction perpendicular to the lead frame. Between the upper mold and the lower mold, the step of preparing a sealing mold device that is configured to press the material resin and that includes a plunger having a diameter slightly smaller than the diameter of the arc of the arc. Sandwich the lead frame so that the semiconductor element mounting part is in the cavity region, supply the sealing resin to the plunger, lower the plunger, and press the sealing resin toward the arc portion, The opposite from the arc edge Filling the sealing resin in the cavity region through a guide portion by use, so that allowed to cure.

A single in-line type lead frame, which is a lead frame in which leads are arranged on one side, may be formed on the other side except this one side.

In a dual in-line type lead frame, which is a lead frame in which leads are arranged on two parallel sides, the through holes may be formed on the sides where no leads are formed.

In the case of a lead frame having leads formed in four directions, a through hole may be provided at one of diagonal positions.

The guide portion may be a tapered surface that opens toward the cavity region, or may be a parallel surface.

When the taper surface is used, it is easy to diffuse in the cavity region.

The parallel planes improve the rectifying action and form a uniform flow.

[0020]

Embodiments of the present invention will now be described in detail with reference to the drawings.

The mold device for resin sealing of the embodiment of the present invention comprises an upper mold 31 and a lower mold 32, as shown in FIG.
The resin material 4 is configured to be extruded in a direction perpendicular to the lead frame at a position separated from the cavity region 33 formed by the upper mold 31 and the lower mold 32 by 4 mm, and the diameter of the arc of the arc portion. A semiconductor device is provided between the upper mold and the lower mold by using a sealing mold apparatus equipped with a plunger 34 having a diameter φ2 (φ2 = 4.5 mm) slightly smaller than φ1 (φ1 = 5 mm). With the lead frame 1 sandwiched so that the mounting portion is located in the cavity region, the sealing resin material 4 is supplied to the plunger and the plunger is lowered to press the sealing resin material against the arc portion. Then, by the reaction from the arc-shaped edge, the cavity area is filled with the sealing resin and cured by using the parallel edge as a guide. That is, this mold apparatus is shown in FIGS. 2 (a) and 2 (b) in a top view and a side sectional view of the upper mold,
As shown in FIGS. 3 (a) and 3 (b), which are a top view and a side sectional view of the lower mold, and FIG. 4 is an overall view thereof, an upper mold 31 and a lower mold 32 having a cavity region 33 are provided. The lead frame 1 is sandwiched therebetween, and the plunger 34 is lowered into the space region formed by the arc portion 20b of the through hole 20 and the upper mold 31 and the lower mold 32 to press the resin material 4 to the cavity region 33. It is configured to be filled and heated for a predetermined time to be cured. Here, the sealing resin material contains an epoxy resin as a main component, a curing agent, a curing catalyst, an adhesion aid,
It is composed of a tablet containing a release agent, a coupling agent, and silica (surfactant), and is preheated to about 165 ° C. and supplied. Since the mold is heated to about 170 to 180 ° C., when the cavity is filled with the molten tablet, the mold is cured in 20 to 30 seconds. 3
Reference numeral 5 is a pot serving as a passage for the resin material 4, 36 is a resin material inlet, 37 is a retard pin for mold separation,
Numeral 38 is a relief of the depressed portion that holds the lead frame before resin sealing, 39 is a package escape portion that holds the lead frame after resin sealing, that is, a package, 40 is a cavity holder, 41 is the positioning of the upper die and the lower die. Is a pilot escape hole, 42 is a batting surface for holding the lead frame, 43 is an air vent formed in a half-blanked state for venting air, and 44 is a guide bush.

The lead frame used in this embodiment is
Is made by press-molding 42 alloy.
As shown in FIG. 5, a guide portion 20a having a parallel edge having a width W and a length L from the package line PL and an arc-shaped edge having a diameter φ2 larger than the width W and continuously provided on the guide edge 20a. The through hole 20 formed by the arc portion 20b is formed outward, and the other portions are formed in the same manner as a normal lead frame.
That is, a die pad 11 on which a semiconductor integrated circuit chip (hereinafter, semiconductor chip) is mounted, and a plurality of inner leads 12 arranged so as to surround the die pad 11.
And an inner lead 12 are integrally connected to each other by a tie bar 13
An outer lead 14 connected to each inner lead and extending outside the tie bar, side bars 15 and 16 for supporting the tie bar 13 from both sides, and a support for supporting the die pad 11. It consists of Tober-17.

A semiconductor device mounted using such a lead frame is as shown in FIG. 6, in which the semiconductor chip 2 is mounted on the die pad 11 of the lead frame 1 and the semiconductor chip 2 is mounted on the die pad 11. The bonding pad and the inner frame 12 of the lead frame are connected by a bonding wire 3 of a gold wire or an aluminum wire, which is further sealed with a resin material 4 such as epoxy resin, and then a tie bar or The side bar is cut and the outer lead is bent into a desired shape to complete.

Next, a resin encapsulation method for a semiconductor device using this mold device will be described.

First, a lead frame as shown in FIG. 5 is formed by pressing the strip material. In punching, a progressive die is used to form the through holes 20 and the outer leads, and then the inner leads are formed. The through hole 20 may be formed at the same time as the outer lead,
It may be formed prior to the formation of the outer leads.

Next, the semiconductor chip is placed on the lead frame 1 thus formed and wire bonding is performed.

Thereafter, the lead frame 1 is sandwiched between the upper mold and the lower mold of the sealing die, and the semiconductor chip is placed in the cavity region 33 of the block shown by A in FIG.
Install.

Then, the sealing resin material 4 containing the epoxy resin as a main component is preheated to about 165 ° C.,
The resin material is charged through the charging port 36 and pressed against the circular arc portion 20b while being heated by the plunger 34.

The resin material 4 extruded into the arc portion 20b is smoothly filled in the cavity region 33 by the reaction and is pressure-hardened. The pressing force at this time is 80k
g / cm ² , melting temperature is 175 ° C., curing time is 20 to 3
0 seconds.

Once cured and the package is formed,
The mold is opened, the pitch is advanced by one pitch, and the package is brought to the position of the package escape portion 39. In block A, the next sealing is performed again.

In this way, it is possible to carry out resin sealing with high precision and reliability very easily. There is no waste of resin and there is almost no flash.

In this way, resin sealing is sequentially performed, and the tie bar is cut by using a tie bar cutting die provided with comb tooth-shaped punches arranged at intervals corresponding to the outer lead intervals. At the same time, resin burrs formed between the package line and the outer leads are removed.

In the above embodiment, the plunger is provided in both the upper mold and the lower mold, and the resin is injected from both the upper mold and the lower mold. However, either the upper mold or the lower mold may be used.

Next, a second embodiment of the present invention is shown in FIG. 7 in which resin is injected from the upper mold, and in FIG. 8 in which resin is injected from the lower mold.

Using such an apparatus, resin sealing can be performed in the same manner as the above method.

Although the lead frame of the dual in-line type has been described in the above embodiment, in the case of the four-direction type, as shown in FIG. 9, if a through hole is provided at one of the corners, the lead frame is formed. Can be formed without affecting. When a wide lead such as a power line or a ground line is arranged at the corner, a similar through hole may be formed in a part of the lead.

The shape of the through hole is not limited to the above embodiment, but the guide portion 20 as shown in FIG. 10, for example.
It can be appropriately modified such that a is tapered.

Further, when the package is formed only on one surface of the lead frame, it can be applied by making one of the molds flat and forming the cavity only on one side.

In addition, although the above-mentioned mold apparatus used for the horizontal type has been described, it goes without saying that it may be used for the vertical type.

[0040]

As described above, according to the present invention, it is possible to provide a resin-encapsulated semiconductor device in which resin is not wasted, is dense, and is highly reliable.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a sealing method using a sealing mold according to an embodiment of the present invention.

FIG. 2 is a view showing a sealing die according to an embodiment of the present invention.

FIG. 3 is a diagram showing a sealing mold according to an embodiment of the present invention.

FIG. 4 is a view showing a sealing die according to an embodiment of the present invention.

FIG. 5 is a diagram showing a lead frame used in the first embodiment of the present invention.

FIG. 6 is a view showing a resin-sealed semiconductor device formed by using the sealing die of the present invention.

FIG. 7 is a view showing a mold for sealing according to another embodiment of the present invention.

FIG. 8 is a view showing a mold for sealing according to another embodiment of the present invention.

FIG. 9 is a diagram showing a lead frame according to another embodiment of the present invention.

FIG. 10 is a diagram showing a modification of the through-hole shape of the lead frame.

FIG. 11 is a diagram showing a conventional lead frame.

FIG. 12 is an explanatory diagram showing a conventional resin sealing method.

[Explanation of symbols]

 1 lead frame 2 semiconductor chip 3 bonding wire 4 resin material 11 die pad 12 inner lead 13 tie bar 14 outer lead 15, 16 side bar 17 support bar 20a guide part 20b circular arc part 20 through hole 31 top Mold 32 Lower mold 33 Cavity area 34 Plunger 35 Pot 36 Resin material input port 37 Retard pin 38 Depress part escape 39 Package escape 40 Cavity holder 41 Pilot escape hole 42 Batting surface 43 Air vent 44 Guide bush

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location H01L 23/50 B // B29L 31:34 (72) Inventor Eiji Hanada 2-10 Komine, Hachiman Nishi-ku, Kitakyushu, Fukuoka No. 1 Mitsui High-Tech Co., Ltd.

Claims (1)

[Claims] 1. A resin-sealing die device for resin-sealing a semiconductor chip mounted on a lead frame, comprising: an upper die, a lower die, and a cavity formed by the upper die and the lower die. A semiconductor chip provided with a predetermined distance from the region and configured to press the sealing resin material in a direction perpendicular to the contact surfaces of the upper mold and the lower mold. With the lead frame having a cutout portion formed outward from the package line so as to be located in the cavity region, sandwiched between the contact surfaces of the upper die and the lower die, the plunger is attached to the cutout portion. Through the notch, and through the cutout portion, from the direction parallel to the main surface of the lead frame, the cavity region is filled with the sealing resin pressurized at the tip of the plunger, and the resin is sealed. Line Resin sealing die apparatus, characterized by being configured to.