JPH0864623A - Resin sealing method for semiconductor device and resin sealing device used for said resin sealing method - Google Patents

Abstract

PURPOSE: To form a semiconductor device of high reliability by preventing voids from forming outside and inside a package and, further, preventing the generation of peeling and bulging through improvement of adhesion of lead frames and the like to a resin. CONSTITUTION: After a resin tablet 6c softens due to heat of a lower die 16c, a plunger 12c for pressurizing the tablet rises. After the tablet 6c is completely compressed and deformed and a resin is filled, evacuation is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin encapsulation method for a semiconductor device and a resin encapsulation device used for the method, and more particularly,
The present invention relates to a resin encapsulation method for a semiconductor device for degassing a mold and a resin encapsulation device used for the method.

[0002]

2. Description of the Related Art FIG. 8 is a cross-sectional view showing an example of a conventional semiconductor device mold, FIG. 9 is a plan view showing an example of a conventional semiconductor device mold, and FIG. 10 is a conventional semiconductor device manufacturing process. FIG. 11 is a diagram for explaining an example, and FIG. 11 is a pressure reduction timing chart in the manufacturing process shown in FIG.

Conventionally, as shown in FIG. 8, a resin sealing device for a semiconductor device generally has a structure in which the upper and lower molds 16a and 17a mounted on a transfer molding press are clamped and then a plunger 12a is used to move the inside of the transfer pot 7a. It is known that molding is performed by pressure-feeding the resin tablet 6a of the above into the cavity 9a.

Specifically, as shown in FIGS. 8 and 9, a fixed mold 17a having a transfer pot 7a in which a plunger 12a for pressing a resin tablet advances and retracts and a cavity 9a for molding one package. When,
A movable mold 16 that is provided below the mold and can move back and forth, and has a cavity 9a for molding the other package.
a, and a protrusion mechanism having ejector pins 13a housed in the mold 16a and the stationary mold 17a, respectively, and advanced and retracted inside each cavity 9a.

A resin sealing method using this resin sealing device will be described with reference to FIGS. 10 and 11.

The semiconductor element 3a is fixed to the island 5a using a silver paste 4a, and an electrode provided on the semiconductor element 3a and a lead frame 1a to which an inner lead is bonded are bonded via a bonding wire 2a to a lower mold 16a. Set on top (A) and transfer pot 7a
After the resin tablet 6a is put therein, the movable lower mold 16a is lifted to perform mold clamping (B).

After the resin tablet 6a is softened by the heat of the mold, the plunger 12a for pressing the tablet rises, and the resin passes through the runner 8a and the gate 11a,
The cavity 9a is filled (C) and molded.

Next, this state is maintained until the curing of the resin is completed (D), and after the curing of the resin, the lower mold 16 on the movable side.
a is opened, the ejector pin 13a is projected, the sealed package is pushed out from the mold (E), and the semiconductor device is sealed with resin.

FIG. 12 is a view for explaining another example (pressure reduction method) of the conventional semiconductor device manufacturing process, and FIG. 13 is FIG.
14 is a plan view showing another example of a conventional semiconductor device die (pressure reducing method) in the manufacturing process shown in FIG. 14, and FIG. 15 is another example of a conventional semiconductor device die (pressure reducing method). FIG.

In the resin sealing device for a semiconductor device shown in FIGS. 12 and 13, the pressure reducing device is driven at the time of resin sealing so that the inside of the cavity 9b and the transfer pot 7b is depressurized through the air vent 10b. In this way, air is prevented from entering the package.

As shown in FIGS. 14 and 15, a resin sealing device for a semiconductor device of this type has a fixed upper mold 17b having a cavity 9b for forming one package.
And a lower mold 16b on the movable side which is provided below the mold and is movable back and forth and has a cavity 9b for molding the other package.

An air vent 1 is attached to the lower mold 16b on the movable side.
0b is formed, and the pressure reducing groove 14b is formed.
An O-ring 15b for sealing the mold is installed around 4b. Further, the lower mold 16b has a cavity 9b.
The ejection mechanism has an ejector pin 13b that moves forward and backward.

An air vent 1 is attached to the fixed upper mold 17b.
0b, and a pressure reducing groove connecting portion 18b for contacting the pressure reducing groove 14b and the pipe 26b. The upper mold 17b is the movable lower mold 16b.
Similar to b, a protrusion mechanism having an ejector pin 13b that moves forward and backward inside the cavity 9b is provided. FIG. 16 is an overall view of a resin encapsulation device for a semiconductor device capable of reducing pressure.

As shown in FIG. 16, the semiconductor encapsulation device main body 29b normally includes a lower platen 19b for fixing the lower mold 16b, an upper platen 20b for fixing the upper mold 17b, and various parts. It is composed of a control unit 21b for controlling the operation.

The pressure reducing device 30b is a vacuum pump 28.
Reserve tank 27, b connected to b, solenoid valve 25
b, a pressure adjusting valve 24b for keeping the degree of vacuum constant, a filter 23 for removing gas discharged from the resin
b, a vacuum gauge 22b for confirming the degree of vacuum, and connected to the main body 29b by a pipe 26b. Here, a resin sealing method using the resin sealing device according to the above depressurization method will be described with reference to FIGS. 12 and 13.

The semiconductor element 3b is fixed to the island 5b using the silver paste 4b, and the electrode provided on the semiconductor element 3b and the lead frame 1b to which the inner lead is bonded are mounted on the mold 16b via the bonding wire 2b. (A), put the resin tablet 6b in the transfer pot 7b, and then move the lower mold 1 on the movable side.
6b is raised to perform mold clamping, and the depressurizing device 30b is operated (B).

After the resin tablet 6b is softened by the heat of the mold, the plunger 12b for pressing the tablet rises, and the resin is filled into the cavity 9b through the runner 8b and the gate 11b (C) and molded. It

After the resin filling is completed, the decompression device is stopped (D).

Next, this state is maintained until the curing of the resin is completed, and the mold 16b on the operating side is opened after the curing of the resin, the injector pin 13b is projected, and the sealed package is extruded from the mold (E ), The semiconductor device is sealed with resin.

[0020]

However, in the resin encapsulation device for a semiconductor device configured as in the above-mentioned conventional technique, air contained in the resin tablet,
Since the transfer pot is a mechanism that opens to the outside,
The air existing in the transfer pot and the cavity when the resin is pressure-fed is mixed into the molten resin by the pressure of the plunger, and voids (spaces) are formed outside the package or inside the package. there were.

Further, at the timing when the pressure reducing device is stopped after the resin is filled, the pressure is reduced even during the resin filling, so that the resin foams in the transfer pot and the cavity, and the cavities are instantaneously generated. Since the filling into the tee is completed, the resin flow pattern is disturbed, the air vent is blocked, and the air inside the package cannot be removed.

Further, since the resin flow pattern is disturbed, the island shift is increased, and there is a problem in that wire exposure and island exposure may cause problems.

On the other hand, the operation timing of the pressure reducing device as disclosed in Japanese Patent Laid-Open No. 63-95636 (see FIG. 1).
7 and FIG. 18), the pressure reducing device is stopped at the same time as the plunger is started, so that the resin flow pattern can be prevented from being disturbed. However, when the resin tablet is compressed, the air contained inside the resin tablet is removed into the transfer pot and cavity, but because the decompression device stops at the same time as the plunger starts, it is removed into the transfer pot and cavity. There is a problem that the air is not degassed and the degassing effect cannot be sufficiently obtained.

In view of the above-mentioned problems of the prior art, the present invention prevents voids (spaces) from being formed outside or inside the package during resin encapsulation of a semiconductor device, and also leads to a lead frame or the like. An object of the present invention is to provide a resin encapsulation method and a resin encapsulation device for a semiconductor device, in which adhesion with a resin is improved to prevent chipping or blistering and form a highly reliable semiconductor device.

[0025]

In order to achieve the above object, the present invention provides a resin sealing method for a semiconductor device, in which a semiconductor device is sealed with resin by evacuating the inside of the mold by a pressure reducing device in a mold clamping state. In (1), the vacuum evacuation is performed simultaneously with the start of the mold clamping, and the vacuum evacuation is stopped when the resin tablet is completely compressed and deformed and the resin starts to be filled.

In the resin sealing method for a semiconductor device, the vacuum evacuation is performed from the start of mold clamping until the resin starts entering the cavity, and the vacuum evacuation is performed from the mold clamping start to the resin gate. To the time when the resin reaches the cavity, the method of performing the vacuum exhaust until the time when the resin moves on the runner part from the start of the mold clamping, and the method of performing the vacuum exhaust when the resin starts to enter the cavity from the start of the mold clamping. There may be a method in which the inside of the cavity is set to a vacuum degree such that the resin does not foam, and the cavity is stopped when the filling is completed.

Further, as a resin sealing device used in such a resin sealing method for a semiconductor device, when controlling the timing of stopping the vacuum exhaust, it depends on the time from when the plunger for pressing the tablet starts to operate. , A controller equipped with a controller for controlling the drive / stop of the pressure reducing device, and a controller for controlling the drive / stop of the pressure reducing device depending on the stroke amount of the plunger for pressurizing the resin tablet when controlling the timing of stopping the vacuum exhaust It may be possible to provide a controller equipped with a controller that controls the driving or stopping of the decompression device by a sensor such as a pressure sensor or optical sensor embedded in the mold when controlling the timing of stopping the vacuum exhaust. .

[0028]

According to the present invention constructed as described above, in the resin sealing method in which the inside of the mold is vacuum-exhausted by the pressure reducing device in the mold-clamping state and the semiconductor device is sealed by the resin, the vacuum-exhaustion is performed simultaneously with the start of the mold clamping. Then, when the resin tablet is completely compressed and deformed and the resin starts to be filled, the vacuum evacuation is stopped to prevent the resin from foaming in the cavity.

The injection time and the stroke amount of the plunger are used to detect the timing at which the vacuum exhaust is stopped.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. Further, in the description of the resin sealing device for a semiconductor device according to the present invention, except for the controller that controls the resin press-in timing and the decompression device stop timing in this device, the prior art shown in FIGS. The configuration other than the controller is omitted because it is the same as the configuration of FIG.

(First Embodiment) FIG. 1 is a manufacturing process diagram for explaining a first embodiment of a resin sealing method for a semiconductor device according to the present invention, and FIG. 2 is a reduced pressure in the first embodiment. It is an apparatus operation timing chart.

As shown in FIGS. 1 and 2, the semiconductor element 3c is fixed to the island 5c by using at least the silver paste 4c on the lower die 16c of the upper and lower dies which have been heated to a desired temperature in advance. Then, a lead frame 1c is set in which an electrode (not shown in the figure) provided on the semiconductor element 3c and an inner lead are electrically connected via a bonding wire 2c (A). Then, the resin tablet 6c is put into the transfer pot 7c, and the lower die 16c
Is raised to perform mold clamping, and a decompression device (not shown in the figure) is operated to decompress the inside of the cavity 9c (B). At this time,
The pressure inside the cavity is about 0.1 atm.

Next, after the resin tablet 6c is softened by the heat of the lower mold 16c, the plunger 12c for pressing the tablet rises, the tablet 6c is completely compressed and deformed, and when the resin is filled, a vacuum is generated. Stop the exhaust (C).

After that, the resin is runner 8c and gate 1
Flowing through 1c, the cavity 9c is filled and molded (D).

Finally, the mold clamped state is maintained until the curing of the resin is completed, the lower mold 16c on the movable side is opened after the curing of the resin, and the injector pin 13c is projected.
The sealed package is released from the mold. In this way, resin sealing of the semiconductor device is realized.

(Second Embodiment) FIG. 3 is a manufacturing process diagram for explaining a second embodiment of a resin sealing method for a semiconductor device according to the present invention.

Similar to the first embodiment, as shown in FIG. 3, the resin tablet 6c is placed in the transfer pot 7c.
Is charged, the lower mold 16c is raised to perform mold clamping, and a decompression device (not shown in the figure) is operated to decompress the inside of the cavity 9c.

Next, after the resin tablet 6c is softened by the heat of the lower mold 16c, the plunger 12c for pressing the tablet rises, the tablet 6c is completely compressed and deformed, and the filling of the resin is started, so that the resin is Although it flows through the runner 8c and the gate 11c and is filled in the cavity 9c, the vacuum exhaust is stopped when the resin begins to enter the cavity 9c as shown in FIG. 3 (C).

As a result, it is possible to prevent the foaming of the resin in the cavity 9c, and since the vacuum evacuation time is long, the air in the transfer pot 7c and the cavity 9c should be sufficiently removed. Can be done.

(Third Embodiment) FIG. 4 is a manufacturing process diagram for explaining a third embodiment of the resin sealing method for a semiconductor device according to the present invention.

Similar to the first embodiment, as shown in FIG. 4, the resin tablet 6c is placed in the transfer pot 7c.
Is charged, the lower mold 16c is raised to perform mold clamping, and a decompression device (not shown in the figure) is operated.

After the resin tablet 6c is softened by the heat of the lower die 16c, the plunger 12c for pressing the tablet rises and the tablet 6c is completely compressed and deformed.
Filling of resin begins, and resin is runner 8c and gate 11
c, and is filled in the cavity 9c.
As shown in (C), the vacuum evacuation is stopped when the resin reaches the gate. This makes it possible to prevent the resin from foaming in the cavity 9c.

The lower die 16c is designed so that the gate portion (not shown) can be replaced because the gate portion (not shown) is subject to wear.

Therefore, when the sensor 14c such as a pressure sensor is used to detect the timing at which the vacuum exhaust is stopped, it is easy to attach the pressure sensor 14c to the gate portion (not shown in the figure). By setting the timing of stopping the exhaust to the time when the resin reaches the gate, highly accurate control becomes possible.

(Fourth Embodiment) FIG. 5 is a manufacturing process diagram for explaining a fourth embodiment of a resin sealing method for a semiconductor device according to the present invention.

Similar to the first embodiment, as shown in FIG. 5, the resin tablet 6c is placed in the transfer pot 7c.
Is charged, the lower mold 16c is raised to perform mold clamping, and a decompression device (not shown in the figure) is operated.

After the resin tablet 6c is softened by the heat of the lower mold 16c, the tablet pressing plunger 12c rises and the tablet 6c is completely compressed and deformed.
Filling of resin begins, and resin is runner 8c and gate 11
c, and is filled in the cavity 9c.
As shown in (C), when the resin is flowing through the runner 8c and the vacuum evacuation is stopped, even if the timing at which the vacuum evacuation is stopped varies a little, the resin remains in the cavity 9c.
Since it has not reached the inside, the resin does not foam.

Further, since the vacuum evacuation time is longer than that of the first embodiment of the present invention, the air in the transfer pot 7c and the cavity 9c can be sufficiently removed.

(Fifth Embodiment) FIG. 6 is a manufacturing process diagram for explaining a fifth embodiment of a resin sealing method for a semiconductor device according to the present invention. FIG. 7 is a timing chart of the pressure reducing device operation according to the fifth embodiment.

Similar to the first embodiment, as shown in FIGS. 6 and 7, the resin tablet 6c is put into the transfer pot 7c, the lower die 16c is raised and the die is clamped, and the pressure reducing device ( (Omitted in the figure).

After the resin tablet 6c is softened by the heat of the lower die 16c, the plunger 12c for pressing the tablet rises, the resin tablet 6c is completely compressed and deformed, the filling of the resin begins, and the resin is runner 8c. , Flows through the gate 11c and fills the cavity 9c, but when the resin begins to enter the cavity, a pressure adjusting valve (not shown in the figure) is used to prevent the resin from foaming the pressure in the cavity 9c. By adjusting the pressure (0.5 to 0.8 atm) to prevent the foaming of the resin in the cavity 9c, the cavity 9c can be prevented.
It is possible to eliminate gas and air generated from the resin during the filling in c.

(Sixth Embodiment) Usually, in a resin sealing device for a semiconductor device, the resin press-in time is an important parameter that affects wire deformation and the like, and the resin press-in time is accurately controlled. ing.

In this embodiment, since the controller for controlling the stop timing of the decompression device by the resin press-in time is provided, it is possible to perform highly accurate control without newly installing a special sensor. Become.

(Seventh Embodiment) Usually, in a resin sealing device for a semiconductor device, the stroke amount of a plunger for pressing a resin tablet is an important parameter that affects unfilling, tie bar deformation, etc. The stroke of the jar is precisely controlled. Further, the amount of resin press-fitted is determined by the stroke amount of the plunger. Therefore, in this embodiment, by providing the controller for controlling the stop timing of the decompression device with the stroke amount of the plunger for pressurizing the resin tablet, highly accurate control can be performed without installing a special sensor. It becomes possible to do.

(Eighth Embodiment) Usually, a mold for a resin sealing device of a semiconductor device is designed so that it can be replaced like a gate part and a runner part as a countermeasure against wear. Has been done.

Therefore, by burying a sensor such as a pressure sensor or an optical sensor in the gate portion or the runner portion in order to obtain the stop timing of the decompression device, it is possible to detect the precise position of the resin in the flow. Therefore, it is possible to perform control with higher precision than in the sixth and seventh embodiments.

In the above-described first to eighth embodiments, the pressure is reduced from the start of mold clamping to the beginning of the resin filling into the cavity, and the depressurization is stopped at the beginning of the resin filling. In addition, it is possible to prevent the air existing in the cavity from being mixed into the molten resin by the pressure of the plunger and forming a void (space portion) outside the package or inside the package.
It is also possible to prevent the resin from foaming inside the cavity.
In addition, since the sealing is performed under reduced pressure, impurities such as air and moisture existing at the interface between the lead frame and the resin are removed, the adhesion between the lead frame and the resin is improved, and peeling or blistering occurs. Lost.

Here, in each of the technique of the present invention shown in FIGS. 1 to 7, the conventional technique shown in FIGS. 8 to 11 (without reduced pressure), and the conventional technique shown in FIGS. 12 to 16 (with reduced pressure). Table 1 shows the void occurrence rate and the peeling occurrence rate.

[0059]

[Table 1] As shown in this table, it is understood that the present invention can provide a highly reliable semiconductor device as compared with the prior art.

[0060]

As described above, according to the present invention, by using the resin sealing device for the semiconductor device, the air inside the transfer pot and the cavity is depressurized from the mold clamping start to the resin filling initial stage. Prevents the air existing in the transfer pot and cavity from being mixed into the molten resin due to the pressure of the plunger when the resin is pressed in, forming voids (spaces) outside the package or inside the package. At the same time, since the pressure reduction is stopped at the initial stage of resin filling, it is possible to prevent the resin from foaming inside the cavity.

Further, since the sealing is performed under reduced pressure, impurities such as air and moisture existing at the interface between the lead frame and the resin are removed, the adhesion between the lead frame and the resin is improved, and peeling and Since blister is eliminated, a highly reliable semiconductor device can be provided.

[Brief description of drawings]

FIG. 1 is a manufacturing process diagram for explaining a first embodiment of a resin sealing method for a semiconductor device of the present invention.

FIG. 2 is a timing chart of a pressure reducing device operation according to the first embodiment.

FIG. 3 is a manufacturing process diagram for explaining the second embodiment of the resin sealing method for a semiconductor device of the present invention.

FIG. 4 is a manufacturing process drawing for explaining the third embodiment of the resin sealing method for the semiconductor device of the present invention.

FIG. 5 is a manufacturing process diagram for explaining the fourth embodiment of the resin sealing method for the semiconductor device of the present invention.

FIG. 6 is a manufacturing process drawing for explaining the fifth embodiment of the resin sealing method for the semiconductor device of the present invention.

FIG. 7 is an operation timing chart of a pressure reducing device according to a fifth embodiment.

FIG. 8 is a cross-sectional view showing an example of a conventional semiconductor device mold.

FIG. 9 is a plan view showing an example of a conventional semiconductor device mold.

FIG. 10 is a diagram for explaining an example of a conventional semiconductor device manufacturing process.

11 is a pressure reduction timing chart in the manufacturing process shown in FIG.

FIG. 12 is a diagram for explaining another example (pressure reduction method) of a conventional manufacturing process of a semiconductor device.

13 is a pressure reduction timing chart in the manufacturing process shown in FIG.

FIG. 14 is a plan view showing another example (pressure reduction method) of a conventional semiconductor device mold.

FIG. 15 is a cross-sectional view showing another example (pressure reduction method) of a conventional semiconductor device mold.

FIG. 16 is an overall view of a resin encapsulation device for a semiconductor device capable of reducing pressure.

FIG. 17 is a manufacturing process diagram of a semiconductor device according to Japanese Patent Laid-Open No. 63-95635.

FIG. 18 is a decompression timing chart according to Japanese Patent Laid-Open No. 63-95635.

[Explanation of symbols]

 1c Lead frame 2c Bonding wire 3c Semiconductor element 4c Silver paste 5c Island 6c Resin tablet 7c Transfer pot 8c Runner 9c Cavity 10c Air vent 11c Gate 12c Plunger 13c Ejector pin 14c Sensor 16c Lower mold 17c Upper mold

Claims (8)

[Claims] 1. A resin sealing method for a semiconductor device, wherein a pressure reducing device evacuates the inside of a mold in a mold clamping state to seal the semiconductor device with a resin. When the resin is compressed and deformed and begins to be filled with this resin,
A method for resin encapsulation of a semiconductor device, which comprises stopping vacuum exhaust. 2. The resin encapsulation method for a semiconductor device according to claim 1, wherein the vacuum evacuation is performed from the start of mold clamping to the time when resin begins to enter the cavity. 3. The vacuum evacuation is performed from the start of mold clamping until the time when the resin reaches the gate.
7. A method for sealing a semiconductor device with a resin according to. 4. The resin encapsulation method for a semiconductor device according to claim 1, wherein the vacuum evacuation is performed from the start of mold clamping until the time when the resin is moving in the runner portion. 5. The vacuum evacuation is performed to a degree of vacuum such that the resin does not foam inside the cavity when the resin begins to enter the cavity after the mold clamping is started, and is stopped at the same time as the completion of filling. Item 2. A method for resin sealing a semiconductor device according to Item 1. 6. A controller for controlling the driving and stopping of the decompression device according to the time from when the plunger for pressurizing the tablet begins to operate, when controlling the timing of stopping the vacuum exhaust. Item 6. A resin encapsulation device used in the resin encapsulation method for a semiconductor device according to any one of items 1 to 5. 7. A controller for controlling driving and stopping of the pressure reducing device according to a stroke amount of a plunger for pressurizing a resin tablet in controlling the timing of stopping the vacuum exhaust. 5. A resin encapsulation device used in the resin encapsulation method for a semiconductor device according to claim 5. 8. The controller according to claim 1, further comprising a controller for controlling driving and stopping of the pressure reducing device by a sensor embedded in a mold for controlling the timing of stopping the vacuum exhaust. 2. A resin encapsulation device used in the resin encapsulation method for a semiconductor device according to item 1.