JPH10217275A - Resin sealing method for semiconductor apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin sealing method of a semiconductor apparatus constituted so as to suppress the generation of void inferiority when a molten resin is extruded into a cavity in a reduced pressure atmosphere to enhance the reliability of a resin sealing type semiconductor apparatus. SOLUTION: In a semiconductor apparatus, cavities 131, 132 are mutually formed to lower and upper molds 11, 12 and a semiconductor element 14 is arranged in the cavity 131. A pot 15 is formed to the lower mold 11 and resin pellets 16 are charged in the pot 15 to be extruded to flow passages 181, 182 by a plunger 17. An air vent 19 is formed to the upper mold 12 so as to communicate with the cavities 131, 132 and a groove 20 reducing exhaust resistance at the time of pressure reduction is formed to the air vent 19. By the reduction of exhaust resistance at a time when a resin is extruded into the cavity in a reduced pressure atmosphere, the generation of void inferiority is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a resin-encapsulated semiconductor device, for example, a semiconductor device in which a semiconductor element portion having a semiconductor chip mounted on a lead frame is sealed with a protective resin. A resin sealing method.

[0002]

2. Description of the Related Art Generally, a semiconductor device is sealed with a resin.
A cylindrical resin tablet is put into a pot communicating with the molding surface in the upper and lower molds, and after the upper and lower molds are clamped, the resin is pushed out of the pot by a plunger. in this case,
The resin tablet is melted by the heat of the mold, and the melted resin is transferred to a cavity in which a lead frame on which a semiconductor chip is mounted is arranged in advance. Thereafter, the state is maintained and cured for a predetermined time, and then the resin-molded semiconductor device is completed by taking it out of the mold.

In such a resin-sealing-type resin-sealing process, during the flow from the pot to the cavity, the air in the flow passage is transferred into the cavity while being entrained, thereby causing void defects. Form.

For example, in a resin sealing method under reduced pressure disclosed in Japanese Patent Application Laid-Open No. 5-41396, after a resin tablet is put into a pot, a molding surface of the mold is formed just before the mold is completely closed. Is sealed and evacuated. In this case, the mold surface can be efficiently exhausted with a small resistance.

More specifically, after the resin tablet is put into the pot, the upper and lower molds are not completely clamped, but the mold is stopped at a distance of 0.3 to 20 mm immediately before the mold or the mold is closed at a very low speed. At this stage, at least the space including the pot and the mold forming surface is sealed with a sealing material or the like, and the space is exhausted using a vacuum pump or the like.

In such an exhaust state, since the upper and lower dies are maintained at a distance of 0.3 to 20 mm, the exhaust resistance is kept sufficiently small, and the pressure is reduced in a very short time. It can be. After being set in such a reduced pressure state, the mold is opened after a predetermined curing time, and a molded product, which is a semiconductor device sealed with resin, is taken out. By performing resin molding under a reduced pressure state in this way, it is possible not only to prevent the entrainment of air into the resin during the flow of the melted resin, but also to discharge volatile components in the flowable resin and to reduce void defects. Occurrence can be reduced.

However, in such a resin sealing method,
Without completely clamping the upper and lower molds, the mold clamping is stopped or the mold is clamped at a very low speed before the mold is completely clamped. At this stage, the exhaust can be efficiently performed. However, after the mold is closed, the gap between the upper and lower molds becomes extremely small, so that the exhaust efficiency is necessarily reduced. Therefore, the exhaustion of volatile components generated by the curing reaction of the resin generated after the mold clamping is impaired, which is a major cause of void defects.

FIGS. 3 and 4 illustrate an example of a conventional resin sealing method for a semiconductor device. First, as shown in FIG. Mold 51
And a second mold 52 set thereabove to be an upper mold.
Is set. The first mold 51 includes a first cavity 53.
1 is set, and the second mold 52 has the first cavity
A second cavity 532 opposed to 531 is formed as a recess. In the first cavity 531, a semiconductor chip mounted on a lead frame and bonded to predetermined lead-out leads by wire bonding is provided. Is installed.

Here, a pot 55 having a cylindrical opening, for example, is formed in the first mold 51, and a pellet 56 of a sealing resin is set in the pot 55 and pushed out by a plunger 57. In this case, the extruded resin flows into a resin flow passage 58 formed between the molds 51 and 52.
1 and 582 to the cavity 53 composed of the first and second cavities 531 and 532. Numeral 59 denotes an air vent for exhaust, which communicates with the cavity 53.

[0010] The first mold 51 and the second mold 52 are provided in the first mold 51.
In a state where the semiconductor element 55 is set in the cavity 53, the two are brought close to each other as shown in FIG. In this case, the first and second molds 51 and 52 are not completely clamped, but are stopped at 0.5 to 20 mm before the clamping or performed at a very low speed.

Here, first and second molds 51 and 52 are provided.
A seal member 60 is interposed between the first and second molds 51 and 52, for example, until the seal member 60 is sandwiched between the first and second molds 51 and 52. That is, in this state, the space including the molding surface of the mold is
The space hermetically sealed by a vacuum pump or the like is exhausted in this state. At this stage, a sufficient degree of vacuum can be obtained because the exhaust resistance is small.

When the mold clamping at the first stage is performed as described above, the mold clamping is performed until the first mold 51 and the second mold 52 come into contact with each other as shown in FIG. After the mold is closed in this way, the sealing resin pellets 56 are extruded by the plunger 57. In this case, the pellets 56 are in a solidified state at the beginning of the injection, but are in a heated state, so that the lower
And the extruded resin is guided into the passage 58 formed by the resin flow passages 581 and 582, and the first and second cavities 531 and 532.
To the cavity 53 formed by

When the flow of the resin starts in this manner, volatile components are generated by a curing reaction of the resin. At this time, since the atmosphere in the resin flowing portion is in a decompressed state, the amount of vaporized volatile components increases due to a decrease in the boiling point. Further, since the gap between the first and second molds 51 and 52 after the mold is closed becomes extremely small, the exhaust resistance inevitably increases, and the volatile matter is discharged from the air vent 59 communicating with the cavity 53. Is impaired, and air bubbles in the resin remain to cause void defects as shown in FIG.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has been made in consideration of the above circumstances. When a melted resin is extruded in a reduced-pressure atmosphere, a curing reaction of the melted resin is performed. Even if volatile components are generated by the semiconductor, the volatile components are effectively discharged, and a void defect in the cured resin is not generated, so that a highly reliable resin-encapsulated semiconductor device can be configured. An object of the present invention is to provide a method of sealing a device with a resin.

[0015]

According to the present invention, there is provided a resin sealing method for a semiconductor device, wherein a resin tablet is put into a pot in a mold of a preheated mold, and upper and lower molds of the mold are set. At least, the space including the molding surface of the pot and the mold is decompressed in the approached state, and then the upper and lower molds are clamped and the molten resin is extruded, and the molten resin is communicated with the pot. In the method for manufacturing a semiconductor device in which the cavity is filled and cured, a groove is formed on the resin molding surface of the mold to communicate with the outside, and the groove is connected to an air vent provided in the cavity, When the molten resin is filled into the cavity, it is sucked in the air pent direction.

According to such a resin sealing method for a semiconductor device, the cavity in which the semiconductor element is set is communicated with the outside under reduced pressure through a groove having a cross section of, for example, 5 mm or more. The extruded sealing resin is filled into the cavity while being sucked. In this case, since the exhaust resistance is made sufficiently small due to the presence of the groove, even bubbles contained in the melted resin are forcibly discharged, and the occurrence of void defects in the cured resin is prevented. Is done.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. First, as shown in FIG. 1A, the lower mold 11 and the upper mold 12 are set to face each other. Here, the lower mold 11 has the first
Is formed, and a second cavity 132 is also formed in the upper mold 12 in a state of being opposed to the first cavity 131. In the first cavity 131, the semiconductor element 14 having a semiconductor chip mounted on a lead frame is installed.

The lower mold 11 has a pot with a cylindrical opening.
A pellet 16 made of a sealing resin is put into the pot 15 and the pellet 16 is placed in a plunger.
17 pushes in the direction of the upper mold 12. Here, a first flow passage 181 is formed in the lower mold 11, and a second flow passage 182 is formed in the upper mold 12. The resin flow passage 18 is formed in a state where the resin flow passage 18 is opposed to the resin flow passage 12.

In a state where the upper mold 12 is opposed to the molding surface of the lower mold 11, the first and second cavities 131 and
The cavity 13 is formed by 132.
An air vent 19 which forms an exhaust port in a state where the air vent communicates with the cavity 13 is formed in the cavity 12. Then, a groove is formed in the upper mold 12 so as to continue to the air vent 19.
20 is formed so that the exhaust resistance from the air vent 19 is reduced. Reference numeral 21 denotes a seal member for keeping the molding surface airtight when the upper mold 12 is opposed to the lower mold 11.

With the lower mold 11 and the upper mold 12 set in this way, they are brought close to each other as shown in FIG. In this case, the lower and upper dies 11 and 12 are not completely clamped, but are stopped at a position 0.5 to 20 mm before the mold clamping, or the mold is clamped at a very low speed. The mold is clamped between the first and second molds 51 and 52 with the seal member 21 interposed therebetween. The space including the molding surface of the mold is made airtight by the seal member 21 and the vacuum The space made airtight by a pump or the like is exhausted.

Next, as shown in FIG.
And the upper mold 12 are clamped until they come into contact with each other, and after the mold is closed, a resin pellet for sealing is
Extrude 16. In this case, the pellets 16 are in a solidified state at the beginning of charging, but are melted by the heat of the lower mold 51, and the resin extruded by the plunger 17 passes through the passages formed by the resin flow passages 181 and 182. 18 and the first and second cavities 131
And 132 into a cavity 13 formed by

When the resin starts to flow in this manner, volatile components are generated by the curing reaction of the resin and the like. At this time, since the atmosphere in the resin flowing portion is in a reduced pressure state, the volatile components are vaporized by a decrease in the boiling point. The amount increases. In this case, usually, the gap between the molds 11 and 12 after the mold is closed is extremely small, the exhaust resistance increases, and the discharge of the volatile matter from the air vent 19 communicating with the cavity 13 is impaired. Since the grooves 20 are formed corresponding to the above, the exhaust resistance does not increase even when the molds 11 and 12 are joined.

That is, by forming the groove 20 corresponding to the air vent 19, it is possible to prevent an increase in the exhaust resistance after the mold is clamped, and it is possible to effectively discharge the volatile components vaporized during the flow of the resin. As a result, a resin molded product free from void defects can be obtained.

Here, in order to reliably prevent the occurrence of void defects, it is preferable that the cross-sectional area of the groove 20 is at least 5 mm ² or more, and the molding surfaces of the dies 11 and 12 to be reduced in pressure are formed. It is preferable that the volume change rate of the space including the space is 50% or less before and after the mold clamping. Furthermore, the rate of change of the conductance (exhaust resistance) of the space including the molding surfaces of the molds 11 and 12 which are in a reduced pressure state is 50% before and after the mold clamping.
The following is preferred.

When a resin having a particularly high volatile content is used as the sealing resin, if the reduced pressure is maintained until the filling of the cavity 13 with the resin is completed, the vaporization due to the decrease in the boiling point is so large that the effect of discharging the volatile content cannot be obtained. Has been confirmed to promote In order to prevent such a state, when the transferred resin flows into the cavity 13 from the flow passage 18, the reduced pressure state is released, and by returning to the atmospheric pressure, the vaporization of the volatile components contained in the resin is suppressed. Thus, occurrence of void defects can be suppressed.

In this case, since the continuous groove 10 is provided in the air vent 19, the return from the reduced pressure state to the atmospheric pressure becomes faster even in the mold clamping state, and the occurrence of void defects can be more effectively obtained. Further, since the groove 20 is formed in the upper mold 12, it is effective in preventing accumulation of dust.

[0027]

As described above, according to the resin sealing method for a semiconductor device according to the present invention, even after the upper and lower molds are clamped, the space including the pot for setting the resin and the mold molding surface can be efficiently used. It is possible to efficiently exhaust the volatile components generated in the flowing resin, and it is possible to reliably reduce the occurrence of void defects in the sealing resin.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams for sequentially explaining examples of a resin sealing method according to an embodiment of the present invention.

FIGS. 2A and 2B are diagrams for explaining a resin sealing method following FIG. 1B.

FIGS. 3A and 3B are diagrams for sequentially explaining a conventional resin sealing method.

FIGS. 4A and 4B are diagrams sequentially illustrating a resin sealing method following FIG. 3B.

[Explanation of symbols]

11 ... lower mold, 12 ... upper mold, 13, 131, 132 ... cavity, 14 ... semiconductor element, 15 ... pot, 17 ... resin pellet,
18… plunger, 19… air vent, 20… groove, 21… seal member.

Claims (6)

[Claims] 1. A resin tablet is put into a pot in a mold of a mold that has been set in advance and includes at least a molding surface of the pot and the mold in a state where upper and lower molds of the mold are close to each other. The space is decompressed, then the resin melted by the mold clamping of the upper and lower molds and the heat of the mold is extruded, and the molten resin communicates with the pot, and is filled in a cavity in which a semiconductor element is installed. In a method of manufacturing a semiconductor device in which a resin is cured, a groove is formed on a resin molding surface of the mold so as to communicate with the outside,
The groove is connected to an air vent provided in the cavity so that the molten resin is sucked in the direction of the air vent when filling the cavity with the molten resin. 2. The resin sealing method for a semiconductor device according to claim 1, wherein said reduced pressure state is set until said resin flows into said cavity and filling is completed. 3. The semiconductor according to claim 1, wherein the reduced pressure state is released when the resin flows into the cavity when a resin having a high volatile content is used as the sealing resin. The method of resin sealing of the device. 4. The groove has a sectional area of at least 5 mm.
^2. The resin sealing method for a semiconductor device according to claim 1, wherein the number is set to ^two or more. 5. The method according to claim 1, wherein a volume change rate of the space including the pot and the mold forming surface where the resin is put into the reduced pressure state is 50% or less before and after the mold clamping. Resin sealing method for a semiconductor device. 6. When the space including the molding surface of the mold is decompressed, the rate of change of the exhaust resistance of the space including the molding surface of the mold is 50% or less before and after the mold clamping. 2. The method according to claim 1, wherein the resin is sealed.