KR100228776B1 - Apparatus for molding semiconductor chip package - Google Patents

Abstract

According to the present invention, a cavity is formed to form a predetermined package shape with a molding resin through a lead frame having a plurality of leads in which the semiconductor chip is mounted and electrically connected to the semiconductor chip, and the molding resin is injected into the cavity. In the semiconductor chip package molding apparatus comprising a runner and a upper mold and a lower mold having protrusions formed at portions where the runners and cavities are connected, the protrusions have a fan shape in which the portions in contact with the leads are cut out. The semiconductor chip package molding apparatus is provided with a groove in which a molding resin is injected into the cavity from a runner at a central portion thereof, thereby preventing wear of the protrusion of the gate portion caused by the flow of the resin encapsulant in the molding die. And at the same time the protrusion height on the difference between the thermal expansion coefficient of the protrusion and the mold Even if this is changed, the lead can be prevented from being crushed and the occurrence of flash can be reduced, thereby increasing the reliability of the molding process and improving the process reliability of a subsequent cutting / bending process.

Description

Apparatus for molding semiconductor chip package

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a semiconductor chip package molding apparatus, and more particularly, to a transfer molding which prevents lead crushing or leaking of a resin encapsulant and at the same time prevents abrasion of a mold to extend the life of the mold. A semiconductor chip package molding apparatus is used.

Recently, electronic devices have become increasingly functional, multifunctional, and miniaturized. Accordingly, semiconductor devices have been highly integrated, increased memory capacity, increased power consumption and signal processing speed, and high density mounting. In particular, with the miniaturization of electronic devices using semiconductor devices, development of thin semiconductor chip packages having improved mounting density and greatly reduced in size has been accelerated. In this trend, the importance of the molding process for protecting the function of the semiconductor chip from the external environment during the semiconductor assembly process is increasing.

The molding process is a process of forming a package body with a resin encapsulant such as an epoxy molding compound in order to protect a lead frame in which a semiconductor chip is mounted and wire bonding is completed, from an external environment. The external lead serving as the external connection terminal is exposed to encapsulate the semiconductor chip and the electrical connection parts connected thereto. Due to the recent high integration of semiconductor devices and an increase in memory capacity, the number of input / output terminals has increased, leading to a complicated structure of leads and a thin package body. Therefore, the molding process requires more advanced technology. In addition, the resin encapsulant used in the molding process requires properties such as heat resistance, high mechanical strength, moderate hardness that does not wear a mold during the molding process, good thermal conductivity, and small thermal expansion coefficient difference with a semiconductor chip.

At present, the molding process has been widely used a transfer molding method using an epoxy molding resin excellent in economics, mass production, and excellent water absorption. Here, the epoxy molding resin used as the resin encapsulation material is about 17-19% epoxy resin, about 8-10% curing agent, about 70-75% filler (SiO ₂ ), and about several% other additives. It is generally made of. Epoxy molding resins have a solid state because of their ease of transport and storage before being used in the molding process. Since the epoxy molding resin, which is in a solid state, cannot be directly injected into the cavity of the molding die, it is injected after being heated in a molding apparatus to have a constant viscosity (gel) state.

1 is a schematic configuration diagram of a general semiconductor chip package molding apparatus;

2 is a state diagram showing before the epoxy molding resin is filled in the cavity;

3 is a perspective view showing an upper portion of a piece of a semiconductor chip package molding apparatus according to the prior art;

4 is a plan view illustrating a gate portion of a lower mold of the semiconductor chip package molding apparatus.

1 and 2, the molding apparatus 100 to which the transfer molding method is applied uses an upper mold 110 and a lower mold 150. A pot 130 is formed at the center of the upper mold 110 to apply pressure to a plunger 120 that is a pressing means. The upper cavity 140 and the lower cavity 160 are formed in the upper mold 110 and the lower mold 150, respectively, so that the upper mold 110 and the lower mold 150 are matched with each other to have a shape of a semiconductor chip package. It is. The lower mold 150 has a runner 170 having one side connected to the port 130 and the other side connected to the lower cavity 160. In the connection portion between the runner 170 and the lower cavity 160, a protrusion 180 protruding upward from the bottom of the runner 170 is formed at the lower mold 150. When the upper mold 110 and the lower mold 150 are mated, the upper mold 110 at the connection portion of the cavity 190 and the runner 170 formed by the upper cavity 140 and the lower cavity 160. ) And the passage formed by the protrusion 180 is called a gate.

The operation of the semiconductor chip package molding apparatus will now be described. In the pot 130, the solid epoxy molding resin 200 having a cylindrical shape is heated to a high temperature (about 175 to 185 ° C.) to change into a gel having a constant viscosity, and a pressure is applied to the plunger 120. In addition, the epoxy molding resin 202 is injected into the cavity 190 having the lead frame 300 on which the semiconductor chip 320 is mounted while maintaining a gel state. When the epoxy molding resin 202 is completely filled in the cavity 190, the epoxy molding resin 200 is cured to form a package body, thereby protecting the embedded semiconductor chip 320 and its electrical connection from the surrounding environment. do.

As described above, in the conventional molding apparatus 100, when the epoxy molding resin 200 is injected into the cavity 190 through the runner 170 of the lower mold 150 through the gate portion, the lower mold 150 may be used. In order to prevent abrasion of the protrusion 180 coupled with the lower mold 150 generated by passing the gate portion of the metal, as shown in FIG. The case 210 is coupled to the runner 170 and the cavity 190 of the lower mold 150. This piece 210 is usually cylindrical and coupled to the through hole of the lower mold 150. By the way, the protrusion height changes due to the difference in thermal expansion or installation error between the lower die 150 and the piece 210. When the piece 210 protrudes above a predetermined height, the lead 310 is crushed. This is because the contact is generated in the contact portion between the piece 210 and the lead frame 300 as shown in FIG. When protruding below a predetermined height, the epoxy molding resin 200 is formed on the surface of the lid 310 as well as the cavity 190 of the molding die. The epoxy molding resin formed on such unnecessary portions is called flash. Crushing of the lead or flashing may cause defects in the process that proceeds after the molding process, particularly in the cutting / bending process.

Accordingly, an object of the present invention is to provide a semiconductor chip package molding apparatus capable of preventing wear caused by flow of epoxy molding resin in a molding die and at the same time preventing crushing of leads or generation of flash.

1 is a schematic configuration diagram of a general semiconductor chip package molding apparatus.

2 is a state diagram showing before the epoxy molding resin is filled in the cavity.

3 is a perspective view showing a top of a piece of a semiconductor chip package molding apparatus according to the prior art;

4 is a plan view illustrating a gate portion of a lower mold of the semiconductor chip package molding apparatus.

5 is a schematic cross-sectional view of a semiconductor chip package molding apparatus according to the present invention.

6 is a perspective view showing a piece used in the semiconductor chip package molding apparatus according to the present invention.

7 is a plan view showing a part of the lower mold of the semiconductor chip package molding apparatus according to the present invention.

8 is a cross-sectional view showing a cavity portion of the semiconductor chip package molding apparatus according to the present invention.

<Description of the reference numerals for the main parts of the drawings>

10,100: semiconductor chip package molding device 11110: upper mold

12,120: Plunger 13,130: Pot

14,140: upper cavity 15,150: lower mold

16,160: Lower cavity 17,170: Runner

18,180: projection 19,190: cavity

20,200: epoxy molding resin 21,210: piece

22, 212: groove 23: upper portion

24: stop 30,300: lead frame

31,310: Lead 32,320: Semiconductor chip

40: gate

The semiconductor chip package molding apparatus according to the present invention for achieving the above object is to form a predetermined package shape with a molding resin via a lead frame having a plurality of leads in which the semiconductor chip is mounted and electrically connected to the semiconductor chip. A semiconductor chip package molding apparatus including a runner having a vertex formed therein, and a runner into which a molding resin is injected into the cavity, and an upper mold and a lower mold having protrusions formed at a portion where the runner and the cavity are connected. It has a fan-shaped shape in which the part in contact with the cut-out is cut, characterized in that the groove in which the molding resin is injected into the cavity from the runner is formed in the center.

Hereinafter, a semiconductor chip package molding apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

5 is a schematic cross-sectional view of a semiconductor chip package molding apparatus according to the present invention;

6 is a perspective view showing a piece used in the semiconductor chip package molding apparatus according to the present invention.

5 and 6, the semiconductor chip package molding apparatus 10 basically includes an upper mold 11 having an upper cavity 14 and a lower mold 15 having a lower cavity 16 formed therein. ) When the upper mold 11 and the lower mold 15 are matched, the upper cavity 14 and the lower cavity 16 form a cavity 19 that determines the package shape. The port 13 is formed in the center of the upper die 11. On the upper surface of the lower die 15, a runner 17 in the form of a groove connected to the cavity 19 is formed. When the upper mold 11 and the lower mold 15, which maintain a constant temperature, usually 170 to 180 ° C., are matched and the plunger 12, which is a pressing means, moves downward in the port 13, the epoxy molding resin 20 Resin encapsulating material such as the gel is to flow along the runner 17 to flow into the cavity 19. When the epoxy molding resin 20 is cured, the semiconductor chip 32 and its electrical connection portions are sealed.

The connection portion 18 with the lower cavity 16 at the distal end of the runner 17 through which the epoxy molding resin 20 flows is positioned lower than the upper surface of the lower mold 15 and protrudes from the lower surface of the runner 17. ) Is formed. The protrusions 18 are for filling the upper and lower parts about the lead frame 32 in a balanced manner when the epoxy molding resin 20 flows. That is, the protrusion 18 forms a constant inclination angle with the bottom surface of the runner 17 so that the filled epoxy molding resin 20 can be balanced in the upper cavity 14 and the lower cavity 16. . Before the epoxy molding resin 20 flows into the cavity 19, friction is intensively generated at the protrusion 18 at the flow rate of the epoxy molding resin 20. Wear of the protrusions 18 due to such friction affects the progress of the process as already mentioned, such as incomplete molding or poor cutting / bending. In order to prevent wear of the protrusions 18, the semiconductor chip package molding apparatus 10 according to the present invention uses a piece as shown in FIG. 6 as the protrusions 18, and its material is harder than the molding die and has a higher wear resistance. Use this superior material. For example, tungsten carbide can be used. A hole 21 into which the piece 21 may be inserted may be formed in the lower mold 15, and the protrusion 21 may be formed by coupling the piece 21 to the hole. The piece 21 is coupled to the lower mold 11 portion where the epoxy molding resin 20 is intensively rubbed, and thus the friction molding with the epoxy molding resin 20 is not significantly affected.

In the piece 21, as shown in Fig. 6, the upper end 23 has a fan shape. Unlike the related art, both edge portions of the upper end 23 are cut out of the cylindrical piece. A groove 22 is formed obliquely at the center of the upper end portion 21 of the piece 21 so as to have a constant inclination angle, and the groove 22 is a passage connecting the runner 17 and the cavity 19. . The upper end 23 and the stop 24 inserted into the lower mold 15 are cylindrical to facilitate coupling and separation, and the upper end 23 and the stop 24 have a step so that the coupling is easy. The grooves 22 formed in the piece 21 have a wider runner 17 side and a narrower cavity 19 side, so that the epoxy molding resin 20 which has passed through the runner 17 has a higher velocity. It is intended to be injected into the body.

Usually, since the material of the piece 21 and the material of the lower metal mold | die 15 differ, there exists a difference of a thermal expansion coefficient. Since the design and fabrication of the molding die is performed at room temperature and the molding process is performed at about 170 to 180 ° C., it is difficult to have a predetermined protrusion height due to the difference in thermal expansion between the protrusion 18 and the lower mold 15. If the piece 21 is higher than the upper surface of the lower mold 15, lead crushing occurs. If the piece 21 is low, the epoxy molding resin 20 leaks. However, in the present invention, the protrusion 21 has a fan shape in which the portion 21 is exposed to the runner 17 and the cavity 19 to remove the portion where the contact with the lead 31 is expected, and thus the protrusion 18 has a lower mold. Even if it is higher than the upper surface of (14), the lid 31 is not pressed.

7 is a plan view showing a part of the lower mold of the semiconductor chip package molding apparatus according to the present invention,

8 is a cross-sectional view showing a cavity portion of the semiconductor chip package molding apparatus according to the present invention.

7 and 8, the fan-shaped piece 21 which is not in contact with the lead portion of the lead frame mounted on the lower mold 15 is coupled to the corner portion of the lower cavity 16. Since the portion 21 does not come into contact with the lead of the lead frame, when the molding die is warmed to a predetermined temperature, it is larger than the protrusion height determined by the difference in thermal expansion of the portion 21 and the lower mold 15. Even when protruding, the lid 31 is not pressed. In addition, the occurrence of flash can be reduced by preventing the epoxy molding resin from leaking toward the lid 31. Therefore, the molding process of forming the package body with the epoxy molding resin can proceed well.

In the above-described semiconductor chip package molding apparatus according to the present invention, it is introduced that the piece has a fan shape only at the upper end, but may be modified in various forms without departing from the central idea of the present invention. And, while the piece has been described as being coupled to the lower mold, if the protrusion is required in the upper mold may be coupled to the upper mold.

According to the structure of the semiconductor chip package molding apparatus according to the present invention as described above, while preventing the wear of the protrusion of the gate portion caused by the flow of the resin encapsulant in the molding die, the height of the protrusion in the difference between the thermal expansion coefficient of the protrusion and the mold Even if it is changed, it can prevent the lead from being crushed and reduce the occurrence of flash to increase the reliability of the molding process, and can also improve the process reliability such as the subsequent cutting / bending process. Of course, even if wear occurs, it can be easily replaced by a simple replacement operation, there is an advantage that can improve the convenience and economy of the semiconductor chip package molding device.

Claims (5)

A cavity in which a semiconductor chip is mounted and formed into a predetermined package shape with a molding resin through a lead frame having a plurality of leads electrically connected to the semiconductor chip, and a runner into which the molding resin is injected; A semiconductor chip package molding apparatus including an upper mold and a lower mold having protrusions formed at a portion where the runner and the cavity are connected, wherein the protrusions have a fan shape in which the portions in contact with the leads are cut out. The semiconductor chip package molding apparatus characterized by the groove | channel in which molding resin is inject | poured into a cavity from a runner. The apparatus of claim 1, wherein the protrusion is an upper end of a piece coupled to the lower mold. 3. The semiconductor chip package molding apparatus of claim 2, wherein the material of the piece is tungsten carbide. The semiconductor chip package molding apparatus of claim 2, wherein the piece is cylindrical except for a protruding portion. 3. The apparatus of claim 2, wherein the piece has a stepped top and a stop.

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