JPH0629340A - Die for forming resin-sealed semiconductor device and resin-seal of semiconductor chip used therefor - Google Patents

Abstract

PURPOSE:To provide a forming die which prevents the occurrence of voids or non-fillings in a package sealed in resin, and a forming method which employs the die. CONSTITUTION:A forming die M is made up of an upper die 5 and a lower die 6, and the ends of a number of movable pins 9 are flatly formed so as to be flush with inner surfaces 5a and 6a of cavities 5A and 6A of the upper and lower dies. These pins are respectively disposed on the upper and lower dies in such a way as to be vertically movable relative to the inner surface. While an IC chip 1 mounted on a leadframe is fastened at a predetermined location within the cavities 5A and 6A by means of the die M, the movement of the IC chip 1 is regulated by drawing each movable pin 9. In this state, the cavity of the die is filled with molten sealing resin. By the end of the filling, the movable pins 9 are retracted to the position where the flat ends of the pins become flush with the inner surfaces 5a and 6a of the cavities 5A and 6A, and sealing resin is then made set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die for a resin-sealed semiconductor device (hereinafter simply referred to as "IC") for sealing a semiconductor chip with a resin by a transfer molding method (hereinafter simply referred to as "molding die"). ]) And a resin encapsulation method for encapsulating a semiconductor chip with a resin using this molding die.

[0002]

2. Description of the Related Art A conventional molding die will be described with reference to FIGS. A conventional molding die is usually composed of an upper die 5 and a lower die 6, as shown in the longitudinal sectional view of FIG. This molding die is a cavity 5 which is a hollow portion for sealing the IC chip 1 sandwiched between two upper and lower dies 5 and 6 as a resin-molded IC having a predetermined shape.
A and 6A, and a gate portion 8 serving as an injection port from the runner portion 7 serving as a resin passage to each cavity 5A, 6A.

In such a molding die, since the molten sealing resin is injected from one side of the cavities 5A and 6A during resin molding, the pressure of the injected resin is applied to the IC chip and the die pad 2 on which the IC chip is mounted. It may move up and down or tilt from its designed position.

Particularly in recent years, the degree of integration of the IC chip 1 has increased and the area of the IC chip 1 has also increased, so that the die pad 2 has become larger than before. On the other hand, the number of pins in the package is increasing, the pitch between the external leads is narrowing, and along with this, the width of the support bar that suspends the internal leads and the die pad 2 is becoming narrower and longer. With such a structure, the IC chip 1 and the die pad 2 move up and down or tilt as described above even with a small resin pressure.

Furthermore, in an IC having a floating chip structure, which is being developed for the purpose of thinning in recent years, since the die pad 2 does not exist in the lead frame, the vertical movement or inclination of this chip has the die pad 2. It happens more often than anything.

When the IC chip 1 and its die pad 2 are vertically moved and tilted significantly, 1. Since the space in which the sealing resin is filled is narrowed above the IC chip 1 or below the die pad 2 (below the IC chip 1 in the case of a floating chip structure), the fluidity of the molten resin deteriorates. 1. Unfilled or voids are generated on the surface of the injected molten resin. The longitudinal sectional structure of the IC is unbalanced, and the IC package is warped due to the difference in the coefficient of thermal expansion between the internal constituent materials.

Furthermore, especially when the semiconductor chip 1 is raised upward, 3. The wire 3 bonding between the IC chip 1 and the lead frame is exposed on the surface of the sealing resin. 4. When the position of the bonding point on the IC chip 1 rises, the wire 3 falls down and touches the edge portion of the IC chip 1, causing a short circuit defect. This may cause trouble such as the wire 3 being pulled and breaking.

[0008]

In order to suppress the vertical movement of the IC chip 1 which causes such a fatal defect, in the case disclosed in JP-A-4-7848, resin encapsulation for an IC of a floating chip structure is adopted. In the mold, protrusions are provided for sandwiching and fixing the IC chip between the upper mold and the lower mold. In this sealing method, as shown in FIG. 7, the protrusion is formed on the surface of the IC package 10. The traces of the object 11 remain, and depending on the case, the thickness of the resin to the surface of the IC chip becomes thin, or the surface of the IC chip is exposed.

In addition to these appearance problems,
The mechanical strength of the IC package 10 may be reduced, and the reliability of the IC may be reduced due to the intrusion of moisture or the like from these portions. Furthermore, the influence of the light from the outside incident from the trace portion or the light transmitted through the thinned resin may adversely affect the electrical characteristics of the IC, such as the data holding voltage in the case of a memory. become.

Also in the embodiment disclosed in Japanese Patent Laid-Open No. 3-9538, a movable conical shape for sandwiching and fixing a die pad for mounting an IC chip in a resin sealing mold as in the above-mentioned example. It is stated that when the pins are provided and the injected resin hardens and is released from the mold, these movable pins can be retracted to below the surface of the main mold, but as shown in FIG.
Traces of these movable pins remain on the surface of the C package 10, causing the problems described in the above-mentioned embodiment,
Even if the timing of retracting the movable pin during resin sealing is adjusted so that the traces of these pins do not remain, the shape of the movable pin is conical, so the movable pin storage part on the main mold surface The resin flows into the surface, leaving burrs 12 on the surface of the IC package 10 as shown.

[0011]

The present invention provides a molding die for a resin-sealed semiconductor device composed of upper and lower dies,
A plurality of movable pins for restricting the movement of the semiconductor chip and / or the die pad are provided on each main mold surface of the cavity formed in these upper and lower molds and having a flat inner surface into which the sealing resin is injected. The front end portion of the semiconductor chip and / or the die pad is formed in a flat surface so as to form the same plane as the inner surface of the cavity when the movable pins are retracted.

Then, using such a molding die, a lead frame on which a semiconductor chip is mounted is arranged at a predetermined position of a cavity of the molding die, the upper and lower dies are fastened, and the upper and lower dies are attached to each other. Each movable pin provided is moved and brought close to the semiconductor chip to regulate the movement of the semiconductor chip, and a molten sealing resin is injected into the molding die, and the sealing resin is injected. When the semiconductor chip is almost completely covered, or when the semiconductor chips are completely covered, the movable pins are moved to a position where the flat surfaces of the tips of the movable pins form the same surface as the inner surface of the upper and lower molds. After pulling back, the sealing resin fills the space where the movable pins were present and is cured, then the upper and lower molds are opened and the resin-sealed semiconductor chip is released to form a resin-sealed mold. Semiconductor device Obtained manner and so as to solve the above problems.

[0013]

Therefore, I existing in the cavity of the molding die is
Even if the C chip has a speed difference in the flow of the molten sealing resin injected into the molding die and the IC chip is to be moved to either the upper or lower direction, Movement will be restricted. Since the movable pin of the above structure is pulled back to the same surface as the inner surfaces of the cavities before the sealing resin is cured, the cured pin has a very slight trace of the movable pin. There will be no burr like the one mentioned above.

[0014]

Embodiments of the resin-molded semiconductor device molding die of the present invention will be described below with reference to FIGS. Figure 1
FIG. 1A is a cross-sectional view showing a molding die for a resin-encapsulated semiconductor device according to an embodiment of the present invention and a state in which a lead frame having an IC chip mounted thereon is sandwiched by the molding die. FIG. FIG. 2B shows a lead frame having the same, FIG. 2B shows a lead frame without a die pad, and FIG. 2 shows the sealing resin melted in the molding die of the present invention in the state shown in FIG. FIG. 4 is a cross-sectional view showing a manufacturing process of the injected IC, FIG. 3 is a cross-sectional view showing a next manufacturing process from the manufacturing process shown in FIG. 2, and FIG. 4 is a manufacturing process shown in FIG. 5 is a cross-sectional view showing the next manufacturing process, and FIG. 5 is a cross-sectional view showing an effective manufacturing process using the manufacturing process shown in FIG. 4 as needed. The same components as those of the conventional technique shown in FIGS. 6 to 8 are designated by the same reference numerals, and detailed description thereof will be omitted.

First, a lead frame on which the molding die and the IC chip of the present invention are mounted will be described with reference to FIG. I
The C chip 1 is mounted on the die pad 2 of a normal lead frame composed of the die pad 2, a plurality of inner leads 4 formed on the periphery of the die pad 2, and other components by being bonded and fixed with silver paste or the like. A plurality of electrodes formed on the IC chip 1 are connected to the inner ends of the inner leads 4 by wires 3.

On the other hand, the molding die M shown in FIG. 1 is composed of an upper die 5 and a lower die 6, and cavities 5 whose inner surfaces 5a, 6a are flat on the opposing surfaces of both.
A and 6A are formed. This structure is similar to the molding die of the prior art. According to the present invention, a plurality of movable upper and lower molds 5 and 6 in which the IC chip 1 is present, which are movable toward the IC chip 1 in a state perpendicular to the IC chip 1, in a portion of the main mold surface avoiding the plurality of electrodes. The movable pin 9 was provided on the upper mold 5 and the lower mold 6.

The shapes of these movable pins 9 are described in JP-A-3-
Rather than having the conical shape as in the 9538 embodiment, the main mold surfaces 5a, 6a of the upper and lower molds 5, 6 are drawn when the pins are retracted.
Columnar or prismatic so that it is continuous. The tip portions of the IC chip 1 and the die pad 2 which are close to the back surface of the die pad 2 have inner surfaces 5 of the cavities 5A and 6A when the movable pins 9 are retracted.
It is formed in a flat shape so as to form the same plane as a and 6a (FIGS. 3 and 4).

Next, a method of resin-sealing the IC chip 1 using the upper and lower molds 5 and 6 having such a configuration will be described. First, as shown in FIG. 1, the lead frame is placed on the lower mold 6 so that the IC chip 1 mounted on the die pad 2 is located at the center of the cavity 6A of the lower mold 6, Similarly, the metal mold 5 is overlaid on the lower metal mold 6, and a plurality of inner leads 4 and the like are sandwiched between the edges of the upper and lower metal molds 5, 6 and fixed.

The lower die 6 raises the plurality of movable pins 9 and the upper die 5 raises the plurality of movable pins 9.
The former to the back of the die pad 2 and the latter to the IC.
The IC chip 1 is held almost at a predetermined position on the surface of the chip 1 with a very small gap between them to bring them close to each other.
Adjust to regulate undesired movement.

As shown in FIG. 1B, in the case of a resin-sealed semiconductor device using a die padless lead frame, when the movable pin 9 provided on the lower mold 6 is raised, as described above. These movable pins 9 are also brought close to the back surface of the IC chip 1 directly.

In this way, by projecting the movable pin 9 from the main mold surface of each cavity 5A, 6A, I
The vertical movement of the C chip 1 and / or its die pad 2 is restricted.

Next, as shown in FIG. 3, the molten sealing resin 10 is injected into the cavities 5A and 6A through the runner portion 7 and the gate portion 8. As shown in this figure, each movable pin 9 is kept in a protruding state until the molten sealing resin 10 almost covers the IC chip 1, and when the upper and lower sides are almost covered, the movable pin 9 is pulled back.

Then, the molten sealing resin 10 is molded into a molding die M.
FIG. 4 shows a state in which the cavities 5A and 6A are completely drained. At this point, the surfaces of the tips of all the movable pins 9 have already been formed on the inner surfaces 5a, 6 of the cavities 5A, 6A.
It is returned until it forms the same plane as the main mold surface that is a part of a, and when the sealing resin 10 hardens, it becomes an IC package. Almost traces of the movable pin 9 remain on the surface. I try not to.

Further, it is important to adjust the timing and speed at which each movable pin 9 is pulled back so that no unfilling or voids occur on the surface of the package (cured sealing resin 10). Therefore, each movable pin 9 may be pulled back when the sealing resin 10 is in a fluid state and the sealing resin 10 as shown in FIG. 2 almost completely covers the IC chip 1.

After the sealing resin 10 is injected and the resin is sufficiently hardened, the upper and lower molds 5 and 6 are separated to release the IC from the molding mold M as shown in FIG. At this time, the IC can be charged and separated while the movable pin 9 is in the retracted state. However, when it is difficult to release the IC, some or all of the movable pins 9 can be moved and projected again as shown in FIG. , I
It is also possible to release C.

[0026]

Effect of the Invention As described above, according to the molding die and the manufacturing method of the present invention, it is possible to control the position of the IC chip inside the resin package. As a result, 1) unfilling and void formation on the package surface 2) package warpage 3) exposure of bonding wire on the package surface 4) short circuit failure (bonding wire touches edge of chip) 5) bonding wire We were able to reduce problems such as disconnection. Also,

2. The position of the IC chip can be controlled without making holes in the resin portion of the package. As a result, 1) there is no problem in the appearance of the package. 2) It is possible to prevent the mechanical strength of the package from being reduced. 3) By suppressing the ingress of moisture etc., the reliability of the IC can be improved. 4) From the outside The effect of eliminating the incidence of light and eliminating the influence on the electrical characteristics of the IC was obtained.

[0028]

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a molding die for a resin-encapsulated semiconductor device according to an embodiment of the present invention and a state in which a lead frame having an IC chip mounted therein is sandwiched by the molding die. Shows a lead frame having a die pad, and FIG. 6B shows a lead frame having no die pad.

FIG. 2 is a cross-sectional view showing a manufacturing process of an IC in which molten sealing resin is injected into the molding die of the present invention in the state shown in FIG.

3 is a cross-sectional view showing the next manufacturing process from the manufacturing process shown in FIG.

FIG. 4 is a cross-sectional view showing a next manufacturing process from the manufacturing process shown in FIG.

FIG. 5 is a cross-sectional view showing an effective manufacturing process using the manufacturing process shown in FIG. 4 as needed.

FIG. 6 shows a conventional molding die for a resin-sealed semiconductor device,
It is sectional drawing of the state which pinched | interposed the lead frame carrying C chip.

FIG. 7 is a vertical cross-sectional view of a resin-sealed semiconductor device manufactured by a conventional molding die for a resin-sealed semiconductor device.

FIG. 8 is a vertical cross-sectional view of a resin-sealed semiconductor device manufactured by another conventional molding die for a resin-sealed semiconductor device.

[Explanation of symbols]

 M Molding die 1 Semiconductor chip (IC chip) 2 Die pad 4 Inner lead 5 Upper die 5A Cavity of upper die 5a 5a Inner surface of cavity 5A 6 Lower die 6A Cavity of upper die 6a 6a Inner surface of cavity 6A 7 Runner -Part 8 Gate part 9 Movable pin 10 Mold resin 11 Pin mark 12 Burr

Claims (3)

[Claims] 1. A molding die for a resin-encapsulated semiconductor device composed of upper and lower dies, each main die surface of a cavity formed in the upper and lower dies and having a flat inner surface into which a sealing resin is injected. In, a plurality of movable pins for restricting the movement of the semiconductor chip and / or the die pad are provided, and the tip portions of these movable pins in the vicinity of the semiconductor chip and / or the die pad are in a state where these movable pins are retracted,
A molding die for a resin-sealed semiconductor device, which is formed so as to be flush with the inner surface of the cavity. 2. A lead frame on which a semiconductor chip is mounted is arranged at a predetermined position of a cavity of the molding die according to claim 1, the upper and lower dies are fastened, and each movable die provided on the upper and lower dies. The molten sealing resin is injected into the molding die in a state where the pins are moved and brought close to the semiconductor chip to restrict the movement of the semiconductor chip, and the sealing resin is the semiconductor chip. When it is almost completely covered, or when it is completely covered, each movable pin,
After the flat surfaces of the tips are pulled back to a position forming the same plane as the flat surfaces of the inner surfaces of the upper and lower molds, the sealing resin fills the space at the positions where the movable pins exist and is cured. A method of resin-sealing a semiconductor chip, comprising: opening the upper and lower molds and releasing the resin-sealed semiconductor chip to obtain a resin-sealed semiconductor device. 3. The semiconductor chip resin sealing method according to claim 2, wherein after the injected sealing resin is cured, some or all of the movable pins that have been pulled back are moved to the sealing resin side. Then, the resin encapsulation type semiconductor device is released from the mold.