JP2001077135A - Resin sealing method of semiconductor device and equipment thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rapidly and uniformly heat a lead frame and raise its temperature up to a prescribed value before clamping, when the lead frame is sealed with resin by using a resin sealing metal mold. SOLUTION: A sealing metal mold is opened, and a lead frame 1 on which a semiconductor chip is mounted is put on a drag 3b. A lead frame pressing mechanism 7 is moved above the lead frame 1, a pressing pin 2 is made to descend, and the lead frame 1 is pressed against the drag 3b. As a result, a contact area of the lead frame 1 and the drag 3b is enlarged, the lead frame 1 can be heated uniformly, without depending on heating with radiation heat, and its temperature can be raised in a short time. By the increase in temperature, the lead frame 1 is thermally expanded, and positioning pins 13 are inserted in positioning holes 14 and then the positioned. Clamping is then performed, and resin molding is perfomed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin sealing method for sealing a lead frame on which electronic parts such as ICs are mounted with a thermosetting resin by a transfer molding method using a mold, and the resin sealing. The present invention relates to a sealing device used for:

[0002]

2. Description of the Related Art Conventionally, a lead frame on which electronic components such as semiconductor chips are mounted is resin-sealed (packaged) using a thermosetting resin such as an epoxy resin by a transfer molding method. This method is performed using a resin sealing mold, and the used mold includes, for example, a fixed lower mold and a movable upper mold, and a heater is incorporated in each of the upper and lower molds. It can be heated to the sealing temperature (about 180 ° C.).

In the operation, first, the upper mold is raised to open the mold, and the lead frame on which the semiconductor chip is mounted is transported and set at a predetermined position on the upper surface of the lower mold. At the same time, a tablet of thermosetting resin is supplied into the pot of the lower mold, the upper mold is lowered, the upper and lower molds are closed, and the lead frame is fastened. Here, the thermosetting resin in the pot is heated and melted, further extruded by a plunger, and flows into the cavities of the upper and lower molds through the runner. After a certain period of time, the thermosetting resin is cured, and the resin sealing of the lead frame is completed by the thermosetting resin molded into the cavity shape.

[0004]

In the above-described conventional resin sealing method, a lead frame on which a semiconductor chip is mounted is transported by a lead frame loader, and a predetermined position on the upper surface of a lower mold which has been heated to a predetermined temperature in advance. In this case, the following problem occurs. This will be described with reference to the drawings. FIG. 7 is a perspective view showing a set state of a conventional lead frame.

First, positioning pins 13 are provided at equal pitch intervals in the lower mold 3b. When setting the lead frame 1, positioning holes 14 formed at equal pitch intervals in the lead frame 1 are fitted. It has become. However, the pitch of the positioning holes 14 formed in the lead frame 1 is designed in advance so as to match the pitch of the positioning pins 13 when the temperature of the lead frame 1 rises to the temperature of the lower mold 3b. I have.

Therefore, immediately after the lead frame 1 at room temperature is placed on the heated lower mold 3b, the pitch between the positioning holes 14 and the positioning pins 13 does not match, and the lead frame 1 is partially lifted. It is placed on the lower mold 3b in a state where the lower mold 3b is set. FIG. 7 shows this state.

[0007] The problem when setting the lead frame in the mold will be described more specifically. In FIG. 7, first, the lower mold 3b is heated to a temperature (about 18
(0 ° C.). The lead frame 1 is conveyed onto the lower mold 3b by the lead frame loader, and is placed in an inclined state while being hooked on the positioning pins 13, and absorbs heat from the lower mold 3b while being left in this state for a certain period of time to heat the lead frame 1. Is performed.

[0008] As described above, after the lead frame is sufficiently heated and thermally expanded, the upper and lower enclosing molds are fastened to perform resin sealing of the semiconductor device. There are the following problems.

First, the first problem is that the lead frame is heated by being left on the lower mold,
At this time, since the area of the portion in contact with the lower mold is very small, the place of relying on heating by radiant heat rather than heat conduction by contact is large, and as a result, the rate of temperature rise is small.

The reason why the area of the contacting portion is very small is that the lead frame is warped immediately after the start of heating. This is because the contact area becomes smaller. In addition, a low heating rate means that a long time is required for the lead frame to reach a target temperature, which lowers the production capacity of the sealing device and lowers efficiency.

FIGS. 5 (a) to 5 (d) are perspective views showing the warpage occurrence state in more detail.
First, FIG. 8A shows a state immediately after mounting the lead frame 1 on the heated lower mold 3b, and this state is the same as that described with reference to FIG. Next, FIG.
(B) shows a state where the lead frame 1 is placed on the lower mold 3b and then left for 5 seconds.
Are not uniformly heated, so that warpage occurs.

Next, FIG. 8C shows that after a lapse of 2 seconds,
That is, the state in which the lead frame 1 is left standing for 7 seconds after mounting is shown, and the warped state is the same as 2 seconds ago. Next, FIG. 8D shows a state where 13 seconds have passed, that is, the lead frame 1 has been left for 20 seconds after being placed. That is, it is shown that the heating temperature of the lead frame becomes uniform only after elapse of 20 seconds from the placement, the warp is corrected, and the positioning pins 13 of the lower mold 3b and the positioning holes 14 of the lead frame 1 coincide. .

As a second problem, similarly to the first problem, the lead frame is heated by being left on the lower mold, so that the area in contact with the lower mold and the area of the portion are heated. Is so small that the heating is not uniform. In such a state where the heating is not performed uniformly, the lead frame is warped particularly in the early stage of the heating, so that an undesirable stress is generated.

Further, if the mold clamping operation is performed in a state where heating is not performed uniformly as described above, Japanese Patent Laid-Open No. 6-190858 is disclosed.
As described above, since the pins are inserted into the holes in a state where the pitch between the positioning pins of the lower die and the positioning holes of the lead frame are different, the positioning holes of the lead frame are destroyed. Further, if the mold clamping is performed before the lead frame reaches the target heating temperature, that is, when the thermal expansion is insufficient, a package displacement occurs.

An object of the present invention is to uniformly and sufficiently heat a lead frame in a process of sealing a semiconductor device with a resin, thereby preventing damage to positioning holes of the lead frame and preventing a position of a package from being damaged. To prevent slippage,
An object of the present invention is to provide an efficient resin sealing method and apparatus having a high production capacity.

[0016]

According to the resin sealing method of a semiconductor device of the present invention, a lead frame on which a semiconductor chip is mounted is fastened by using an encapsulating mold composed of an upper mold and a lower mold, and a sealing resin is formed. In a resin sealing method for a semiconductor device in which a lead frame is melted to perform encapsulation molding, a lead frame is placed on a lower mold, and then a lead frame pressing mechanism is moved onto the lead frame, and provided in the lead frame pressing mechanism. Lowering the pressing pin to press the lead frame against the lower mold, and forcibly bringing the lead frame into contact with the lower mold before heating the lead frame with the upper and lower molds, and heating. I do.

Further, according to the resin sealing method of a semiconductor device of the present invention, a lead frame on which a semiconductor chip is mounted is fastened by using an encapsulating mold composed of an upper mold and a lower mold to melt the sealing resin. In a resin sealing method of a semiconductor device performing encapsulation molding, a lead frame is supplied to an encapsulation mold by a lead frame loader, and then the lead frame supplied to the encapsulation mold is pressed against a lower mold by a lead frame pressing mechanism. Supplying a sealing resin tablet to the encapsulating mold by a tablet hand.

Further, according to the resin sealing method for a semiconductor device of the present invention, a lead frame on which a semiconductor chip is mounted is fastened by using an encapsulating mold composed of an upper mold and a lower mold to melt the sealing resin. In a resin sealing method of a semiconductor device performing encapsulation molding, a lead frame is supplied to an encapsulation mold by a lead frame loader, and at the same time, a lead frame supplied to the encapsulation mold by a lead frame pressing mechanism is pressed against a lower mold. Supplying a sealing resin tablet to the encapsulating mold by a tablet hand.

The resin sealing device for a semiconductor device according to the present invention is characterized in that the lead frame pressing mechanism is provided independently of the lead frame loader and the tablet hand.

Further, the resin sealing device for a semiconductor device according to the present invention is characterized in that the lead frame pressing mechanism is integrated into a lead frame loader.

Further, according to the resin sealing device for a semiconductor device of the present invention, the tip of the pressing pin provided in the lead frame pressing mechanism, which comes into contact with the lead frame, is formed of a wear-resistant metal, Is formed of a heat insulating material for suppressing heat conduction to the pressing pin driving section.

[0022]

Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a view showing a first embodiment of the present invention, and is a front view showing a configuration of a resin sealing device of a semiconductor device.

In FIG. 1, the resin-filled mold is an upper mold 3
a and a lower mold 3b. The press section has a lower base 4b and an upper base 4a that can move up and down along a support 15 erected on the lower base 4b, and a lower mold 3b is fixed to the lower base 4b. Is mounted with an upper mold 3a. A heater is incorporated in each of the upper mold 3a and the lower mold 3b so that the heater can be heated to a resin sealing temperature (about 180 ° C.).

The lead frame loader 5 is a robot mechanism for clamping the lead frame 1 on which the semiconductor chip is mounted by vacuum suction, and transporting and placing the lead frame on the lower mold 3b. The tablet hand 6 picks up and conveys the sealing resin tablet 18 with an opening / closing mechanism,
It is a robot hand that is supplied to and supplied to a pot provided in the lower mold 3b.

Next, the lead frame pressing mechanism which is a feature of the present invention will be described. The lead frame pressing mechanism 7 has a pressing pin 2 and has a function of pressing the lead frame 1 placed on the lower mold 3b against the lower mold 3b. This lead frame pressing mechanism will be described in detail with reference to FIG.

FIG. 2 is a perspective view for explaining the structure and operation of the lead frame pressing mechanism shown in FIG. FIG. 2 shows a state immediately after the lead frame 1 is placed on the heated lower mold 3b. As described above, this state is the same as the state shown in FIGS. 7 and 8A, and is similar to the state shown in FIGS.
And the position of the positioning pin 13 of the lower mold 3b do not match. Then, a state is shown in which the lead frame pressing mechanism 7 is positioned above the lead frame 1 in this state by a moving mechanism (not shown).

The structure of the pressing mechanism 7 will be described. A cylinder 12 is mounted on a base 11 mounted on a moving mechanism (not shown).
The sub-base 9 is attached to the second rod, and the sub-base 9 moves up and down in accordance with the operation of the cylinder 12. A guide shaft 10 is set up on the sub base 9,
The guide shaft 10 is slidably inserted into a guide hole formed in the base 11 so that the sub base 9 can move up and down in the vertical direction.

The pressing pin 2 is attached to the lower surface of the sub base 9. The pressing pin 2 is made of metal in consideration of wear resistance, and a heat insulating material 8 is interposed between the pressing pin 2 and the sub base 9 for the purpose of suppressing heat conduction to the sub base 9.

The lead frame pressing mechanism 7 is
A moving mechanism is provided together with the lead frame loader 5 and the tablet hand 6 to form independent mechanisms.

Next, the lead frame pressing mechanism 7
The operation of will be described. FIG. 4A to FIG.
It is a perspective view explaining the state which presses a lead frame with time.

FIG. 4A shows a state immediately after the lead frame 1 is placed on the lower mold 3b which has been heated (about 180 ° C.). Since the temperature of the lead frame 1 is low and is not thermally expanded, the positioning pins 13 of the lower mold 3b do not completely enter the positioning holes 14 of the lead frame 1.

FIG. 4B shows that the lead frame 1 is moved downward by the pressing pin 2 five seconds after the mounting, and
Shows the state pressed against. At this time, the positioning pins 13 of the lower mold 3b are inserted into the positioning holes 14 of the lead frame 1.
Is not completely contained, but the contact area between the lead frame 1 pressed by the pressing pins 2 and the lower mold 3b is large.

FIG. 4C shows that the lead frame 1 expands due to the rapid and uniform heating to a predetermined temperature two seconds after the pressing, that is, seven seconds after the placing, This shows a state in which the positioning pins 13 of the lower mold 3b are completely inserted into the positioning holes 14 of the lead frame 1.

Next, the operation of the first embodiment of the present invention will be described. FIG. 3A to FIG.
FIG. 7 is a front view of an enclosing mold for describing an operation sequence of the embodiment.

First, FIG. 3A shows an operation 1 in which the enclosing mold is vertically separated into an upper mold 3a and a lower mold 3b, each of which is heated to about 180 ° C. . A lead frame loader 5 for transporting the lead frame 1 and a sealing resin tablet 1 are provided in the vicinity of the sealing mold.
The tablet hand 6 for supplying the lead frame 8 and the lead frame pressing mechanism 7 for pressing the lead frame 1 against the lower mold 3b are on standby.

Next, FIG. 3B shows the second operation, in which the lead frame loader 5 is moved and the lead frame 1 is carried into the mold. Next, FIG.
The lead frame loader 5 places the lead frame 1 on the lower mold 3b and returns to the original position.

Next, FIG. 3D shows an operation 4 in which the lead frame pressing mechanism 7 is moved onto the lower mold 3 b on which the lead frame 1 is placed, and the lead frame 1 is moved by the lowering operation of the pressing pin 2. Is pressed against the lower mold 3b for a certain time. Next, FIG. 3E shows an operation No. 5, in which after the pressing operation of the pressing pin 2 is completed, the lead frame pressing mechanism 7 returns to the original position.

Next, FIG. 3F shows an operation 6, in which the tablet hand 6 carries the sealing resin tablet 18 into the encapsulating mold. Next, FIG. 3G shows an operation No. 7,
After putting the sealing resin tablet 18 into the pot of the lower mold 3b, the tablet hand 6 returns to the original position.

Next, FIG. 3H shows the operation No. 8, in which the upper base 4a of the press section is lowered, and the upper die 3a is also lowered, and the lead frame is moved by the upper die 3a and the lower die 3b. Insert 1. Next, resin encapsulation molding is started, and the molten sealing resin flows into the cavity of the encapsulation mold.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a perspective view showing the configuration of the present embodiment. In the first embodiment described above, FIG.
Although the lead frame pressing mechanism is provided independently as shown in (1), the present embodiment has a configuration in which the lead frame pressing mechanism is incorporated in the lead frame loader.

As shown in FIG. 5, the lead frame loader 5 transports the lead frame by vacuum suction in the first embodiment. However, in this embodiment, the opening / closing claw that opens and closes on both sides by an opening / closing mechanism. At 17, the lead frame is hooked and transported. A pressing pin 2 is provided at the center of the opening and closing mechanism. The pressing pin 2 has a stepped structure and has a base (not shown) of the lead frame loader 5.
The lead frame 1 is pressed against the lower mold 3b by the compressive force of the spring 16 via the heat insulating material 8.

As described above, the lead frame pressing mechanism 7 is integrated with the lead frame loader 5 together with the motor or the cylinder as the opening / closing operation mechanism 19, and is used when the lead frame 1 is transferred to the lower mold 3b. At the time of the lowering operation, the opening / closing claw 17 is
And the pressing operation by the pressing pin 2 are performed simultaneously.

Next, the operation sequence of the second embodiment described with reference to FIG. 5 will be described with reference to FIGS. 6 (a) to 6 (f).

FIG. 6 (a) shows the operation 1 in which the upper mold 3a and the lower mold 3b are vertically separated from each other. In the vicinity of the mold, a tablet hand 6 is provided.
A lead frame loader 5 having a lead frame pressing mechanism is provided. The mold is heated to a predetermined temperature.

FIG. 6 (b) shows an operation 2 in which the lead frame loader 5 conveys the lead frame 1 onto the lower mold 3b, places the lead frame 1 by the lowering operation, and simultaneously operates the lead frame pressing mechanism. It acts and stops for a certain period of time, and the lead frame 1 is pressed against the lower mold 3b by the pressing pin 2.

FIG. 6C shows the third operation, in which the lead frame loader 5 has returned to its original position.
FIG. 6D shows an operation 4 in which the tablet hand 6 conveys the sealing resin tablet 18 to the encapsulating mold, and the lower mold 3
The state where it is thrown into the pot b is shown. FIG. 6 (e)
Shows the operation No. 5 and shows a state where the tablet hand 6 has returned to the original position after the sealing resin tablet 18 is inserted.

FIG. 6 (f) shows an operation No. 6, in which the upper base 4a of the press section is lowered and the lead frame 1 is sandwiched between the upper mold 3a and the lower mold 3b. Next, encapsulation molding is started, the sealing resin tablet is melted under pressure, and the molten resin is caused to flow into the cavity of the encapsulation mold.

As described above, according to the second embodiment,
The lead frame pressing mechanism is built into the lead frame loader, and the lead frame pressing mechanism operates simultaneously when the lead frame is lowered when transferring the lead frame to the encapsulating mold. The effect of simplification is obtained. Further, since the lead frame is placed on the lower mold and pressed at the same time, sufficient heating can be performed in a shorter time than in the first embodiment.

In the second embodiment, the case where the lead frame pressing mechanism is incorporated in the lead frame loader has been described. However, the lead frame pressing mechanism may be incorporated in a tablet hand or may be provided in an enclosing mold.

[0050]

As described above, the present invention has the following effects. First, the first effect is that, since the lead frame is pressed against the encapsulating mold and heated, the rate of temperature rise is high, and the heating time is short, so that the production efficiency can be improved. The second effect is that the contact area is increased by pressing the lead frame against the encapsulating mold, and the entire body is uniformly heated, so that undesired warpage does not occur.

The lead frame heating time can be shortened by comparing the present invention and the prior art with reference to FIGS. 4 and 8 in a time series manner. 20 seconds was required, but this example shows that this was reduced to 7 seconds by the present invention.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a lead frame pressing mechanism used in the first embodiment of the present invention.

FIGS. 3A to 3H are diagrams for explaining the operation of the first embodiment of the present invention, and FIG. 3A to FIG.

FIGS. 4A to 4C are views for explaining a heating state of the lead frame according to the present invention, and FIGS.

FIG. 5 is a configuration diagram showing a second embodiment of the present invention.

FIG. 6 is a diagram for explaining the operation of the second embodiment of the present invention, and FIGS. 6 (a) to 6 (f) show the operation order.

FIG. 7 is a perspective view illustrating a heating state of a conventional lead frame.

8 (a) to 8 (d) are views for explaining a heating state of a conventional lead frame, and FIGS. 8 (a) to 8 (d) are process diagrams thereof.

[Explanation of symbols]

 Reference Signs List 1 lead frame 2 pressing pin 3a upper die 3b lower die 4a upper base 4b lower base 5 lead frame loader 6 tablet hand 7 lead frame pressing mechanism 8 heat insulating material 9 sub base 10 guide shaft 11 base 12 cylinder 13 positioning pin 14 positioning Hole 15 Support 16 Spring 17 Opening / closing claw 18 Sealing resin tablet 19 Opening / closing operation mechanism

Claims (6)

[Claims] 1. A resin sealing method for a semiconductor device in which a lead frame on which a semiconductor chip is mounted is fastened by using an encapsulation mold composed of an upper mold and a lower mold, and a sealing resin is melted to perform encapsulation molding. Place the lead frame on the lower mold, move the lead frame pressing mechanism onto the lead frame, lower the pressing pins provided on the lead frame pressing mechanism, press the lead frame against the lower mold, A resin sealing method for a semiconductor device, wherein a lead frame is forcibly brought into contact with a lower mold and heated before the frame is fastened to the upper mold and the lower mold. 2. A resin sealing method for a semiconductor device in which a lead frame on which a semiconductor chip is mounted is fastened by using an encapsulation mold composed of an upper mold and a lower mold, and the encapsulation molding is performed by melting the encapsulation resin. Then, the lead frame is supplied to the sealing mold by the lead frame loader, and then the lead frame supplied to the sealing mold by the lead frame pressing mechanism is pressed against the lower mold, and then the sealing resin tablet is formed into the sealing mold by the tablet hand. Supplying a resin to the semiconductor device. 3. A resin sealing method for a semiconductor device in which a lead frame on which a semiconductor chip is mounted is fastened by using an encapsulation mold including an upper mold and a lower mold, and the encapsulation molding is performed by melting the encapsulation resin. At the same time, the lead frame is supplied to the molding die by the lead frame loader, and at the same time, the lead frame supplied to the molding die is pressed against the lower die by the lead frame pressing mechanism, and then the sealing resin tablet is formed into the molding die by the tablet hand. Supplying a resin to the semiconductor device. 4. The resin sealing device for a semiconductor device according to claim 1, wherein the lead frame pressing mechanism is provided independently of the lead frame loader and the tablet hand. 5. The resin sealing device for a semiconductor device according to claim 1, wherein the lead frame pressing mechanism is integrated into a lead frame loader. 6. A pressing pin provided in the lead frame pressing mechanism has a tip portion made of wear-resistant metal in contact with the lead frame, and an original portion suppresses heat conduction to the pressing pin driving section. 2. The resin sealing device for a semiconductor device according to claim 1, wherein the resin sealing device is formed of a heat insulating material.