JP2018056310A - Resin encapsulation mold, and method of manufacturing semiconductor device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin encapsulation mold capable of suppressing generation of flash burrs on a rear face of a die pad.SOLUTION: On a rear face of a die pad 3, a projection 4 is provided at its outer peripheral part. On an upper surface of a resin encapsulation lower mold 1, that is, on a bottom face of an encapsulation region 11, a convex part 2 whose area is smaller than a part surrounded by the projection 4 on the rear face of the die pad, and whose height is the same as a height of the projection 4 is provided. Although a push-down stress is applied to a semiconductor chip mounting surface of the die pad and the mounted semiconductor chip by a molding pressure at resin encapsulation, the convex part provided on the resin encapsulation lower mold 1 supports the die pad, and thus, deformation of the die pad, intrusion of a resin caused by the deformation to between the rear face of the die pad and the mold, and a stress to the semiconductor chip mounted on the die pad, can be prevented.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a semiconductor device in which a back surface of a die pad on which a semiconductor chip is mounted is exposed from a mold resin, and a resin-sealed mold as a manufacturing facility thereof.

  In general, a semiconductor device has a semiconductor chip mounted on a die pad portion of a lead frame including a die pad on which the semiconductor chip is mounted and a lead serving as a signal path, and the electrode pad and the lead on the semiconductor chip are made of gold, copper, aluminum, or the like. After connecting with a wire, the semiconductor chip, die pad, wire, and lead are made by a resin sealing process using a transfer mold. In recent years, power consumption has increased due to higher integration and higher functionality of semiconductor chips, and the amount of heat generated from the semiconductor chips has been increasing accordingly. Therefore, higher heat dissipation of semiconductor devices is required. One technique for increasing heat dissipation is to expose the back surface of the die pad to the outside of the resin sealing body.

  When forming this type of semiconductor device, the back surface of the die pad that is sealed during transfer molding is placed in contact with the top surface of the mold for sealing, and then sealed in the mold. The mold resin is injected under predetermined conditions.

  During resin sealing, the resin may enter through the gap between the back surface of the die pad and the mold for sealing, and may adhere to the back surface of the die pad to be exposed as a thin flash burr. May drop out in subsequent processes and cause problems. Further, the exposed area on the back surface of the die pad serves as a path for electrical connection between the semiconductor device and the substrate when the semiconductor device is mounted on the substrate, and heat generated from the semiconductor chip is transmitted through the substrate. Often used as a heat dissipation path. In this case, since the electrical and thermal connection between the semiconductor device and the substrate is hindered by the burr, it is desired to prevent the burr and to remove it when the burr occurs.

  In order to solve this problem, a protruding wall is provided on the outer periphery of the exposed part of the die pad, thereby increasing the surface pressure of the back surface of the die pad and the contact surface of the resin sealing mold during resin sealing to prevent the resin from entering. Is disclosed (for example, see Patent Document 1).

JP 2008-270661 A

  However, even in the above prior art, a gap is generated between the back surface of the die pad and the contact surface of the resin sealing mold during resin sealing. For this reason, distortion of the die pad occurs due to the injection pressure of the resin at the time of sealing, and the adhesion between the back surface of the die pad and the resin sealing mold is impaired. In addition, stress is applied to the semiconductor chip mounted due to the distortion of the die pad, which can cause fluctuations or breakage of electrical characteristics of the semiconductor chip.

  It is an object of the present invention to provide a resin-sealed mold for solving these problems and a method for manufacturing a semiconductor device using the same.

In order to solve the above problems, the following means are used in the present invention.
First, a protrusion is provided on the outer peripheral portion of the back surface of a die pad on which a semiconductor chip is mounted, and the protrusion of the die pad contacts in a resin-sealed mold for molding a semiconductor device in which the back surface of the die pad is exposed from the sealing resin. A first mold having a first die pad installation area, a periphery of which is surrounded by the first die pad installation area and having a convex portion whose upper surface is in contact with the die pad, and a pair of the first mold and a sealing area And a second mold that forms a resin-sealed mold.

As described above, when the lead frame is placed on the mold, the mold is surrounded by the die pad back surface protruding portion and the height is not more than the protruding portion. The upper convex portion supports the back surface of the die pad and suppresses deformation of the die pad that receives resin pressure. As a result, the die pad is stably placed on the sealing mold at the time of resin sealing, so that it is possible to prevent stress on the semiconductor chip due to resin intrusion into the back surface of the die pad and deformation of the die pad.
By using the means, it is possible to provide a semiconductor device in which the occurrence of flash burrs on the back surface of the heat sink is suppressed.

It is sectional drawing which shows the 1st Example of the resin sealing metal mold | die of this invention. It is a perspective view of the IC mounting surface side of the lead frame. It is a perspective view of the die pad back surface side of a lead frame. It is a convex-part enlarged perspective view of the resin-sealed lower mold of the present invention. It is sectional drawing which shows the 2nd Example of the metal mold | die under resin sealing of this invention. It is sectional drawing which shows the 3rd Example of the metal mold | die under resin sealing of this invention.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a first embodiment of a resin-sealed mold according to the present invention.
FIG. 1 shows a state in which a lead frame is clamped between a pair of upper and lower resin-sealing molds 1 and 9. The semiconductor chip 6 is die-bonded on the die pad 3 which is a part of the lead frame, one end of the wire 7 is connected to the electrode pad on the semiconductor chip 6, and the other end of the wire 7 is connected to the lead 5. The lead 5 is sandwiched and fixed between a resin-encapsulated upper mold 9 and a resin-encapsulated lower mold 1. The shape of the resin constituting the semiconductor device is determined by the resin sealing region 10 determined by the resin sealing upper mold 9 and the resin sealing lower mold 1. In general, the resin-sealed lower mold 1 determines the lower half of the resin-sealed area 10, and the resin-sealed upper mold 9 determines the upper half of the resin-sealed area 10.

  On the back surface of the die pad 3, a protrusion 4 is provided on the outer periphery thereof. On the other hand, the area provided on the upper surface of the resin-encapsulated lower mold 1 that determines the bottom surface of the resin sealing area 10 has a smaller area than the area surrounded by the protrusion 4 on the back surface of the die pad. Protrusions 2 having the same height are provided. Therefore, the convex part 2 of the resin-encapsulated lower mold 1 fits inside the protruding part 4 on the back surface of the die pad 3 and supports the die pad 3 from the back surface inside the outer peripheral part.

  When the lead frame and the mold are resin-sealed as described above, the resin injected into the resin-sealed region 10 enters between the die pad 3 and the resin-sealed lower mold 1. The process stops when a small gap created by the absence of the convex portion 2 of the resin-sealed lower mold 1 inside the protruding portion 4 on the back surface of the die pad 3 is filled. At this time, the resin molding pressure causes stress in the direction of pressing down the IC mounting surface of the die pad and the mounted IC, but the convex portion provided in the resin-sealed lower mold 1 supports the die pad. It becomes possible to prevent the deformation of the die pad and the invasion of the resin between the back surface of the die pad and the die and the stress on the semiconductor chip mounted on the die pad. Therefore, it is possible to prevent the formation of a flash burr which is a thin burr on the surface of the back surface of the die pad while suppressing the stress applied to the semiconductor chip.

  FIG. 2 is a perspective view of the lead frame. Two opposing sides of the die pad 3 are supported by the suspension leads 8, and the die pad is set down. Further, the lead 5 adjacent to the die pad is kept at the same height as the suspension lead 8. A semiconductor chip 6 is placed on the die pad 3, and the semiconductor chip 6 and the leads 5 are electrically connected via wires 7. When the lead frame having such a shape is inserted between the upper and lower molds 1 and 9 as shown in FIG. 1, the lead 5 is sandwiched between the molds, and the suspension lead 8 lowers the die pad 3 from the lower mold. It plays the role of pressing onto the mold 1.

FIG. 3 is a perspective view from the back side of the die pad of the lead frame of the present invention. A protrusion 4 is provided along the outer periphery of the back surface of the die pad 3 of the lead frame.
FIG. 4 is an enlarged perspective view of a convex portion of the resin-sealed lower mold according to the present invention. (A) is an example which shows a circular convex part in planar view, (b) is a rectangular convex part.

  As shown in FIG. 4A, the resin-sealed lower mold 1 is provided with a recess for determining the lower half of the sealing area, and a die pad installation area 11 is provided at the center of the bottom surface forming the recess. Is provided, and a circular convex portion 2 that is one step higher is present inside. The convex part 2 has a smaller plane area than the protrusion 4 on the outer periphery of the die pad, and enters the inside of the protrusion. The height is the same as that of the protrusion 4. Since the semiconductor device generally has a rectangular outer shape, the convex portion 2 may be rectangular as shown in FIG.

FIG. 5 is a cross-sectional view showing a second embodiment of the resin-sealed mold of the present invention.
The entire projecting portion on the bottom surface of the resin-sealed lower mold 1 is a protruding pin 12 that can move up and down. The tip of the protruding pin 12 is in a position in contact with the back surface of the die pad installed on the lower mold 1 with resin sealing. The planar shape of the tip of the protrusion pin 12 needs to be large enough to enter the inside of the die pad installation area 11. When the resin sealing of the lead frame is completed and taken out from the mold, it moves upward and functions to protrude the resin body of the semiconductor device from the mold through the die pad. Since the resin body is pressed directly, it is possible to reduce the release stress from the mold compared to the protrusion by pressing the external lead.

FIG. 6 is a cross-sectional view showing a third embodiment of the semiconductor manufacturing method of the present invention.
Inside the convex part 2 on the bottom surface of the resin-sealed lower mold 1, a protruding pin 12 that moves up and down is included. That is, a part of the upper surface of the convex portion is occupied by the tip of the protruding pin 12. When the resin sealing of the semiconductor device is completed and the pin is taken out from the die, the pin moves upward and projects the resin body of the semiconductor device from the die via the die pad as in the second embodiment.

DESCRIPTION OF SYMBOLS 1 Resin sealing lower metal mold 2 Convex part 3 Die pad 4 Die pad protrusion part 5 Lead 6 Semiconductor chip 7 Wire 8 Hanging lead 9 Resin sealing upper metal mold 10 Resin sealing area 11 Die pad installation area 12 Extrusion pin

Claims (6)

A resin-sealed metal for forming a semiconductor device having a protrusion on the outer periphery of the back surface of a die pad on which a semiconductor chip is mounted and the back surface of the die pad being exposed from a sealing resin while the die pad is fixed to a lead frame In the mold,
A recess that determines the lower half of the resin sealing area, a die pad installation area that contacts the protrusion of the die pad provided at the center of the recess, and an upper surface that is surrounded by the die pad installation area and is in contact with the die pad A first mold having a convex portion;
A second mold that pairs with the first mold and determines the upper half of the resin-encapsulated region;
A resin-sealing mold comprising:   2. The resin-sealed mold according to claim 1, wherein the convex part is a movable pin, and is a protruding pin that separates the resin-sealed lead frame from the first mold. 3.   2. The resin-sealed mold according to claim 1, further comprising a movable protruding pin for separating the lead frame resin-sealed in the convex portion from the first mold.   The resin-sealed mold according to any one of claims 1 to 3, wherein a planar shape of the convex portion is circular. The resin-sealed mold according to any one of claims 1 to 3, wherein a planar shape of the convex portion is a rectangle. In a manufacturing method of a semiconductor device having a protrusion on an outer peripheral portion of a back surface of a die pad on which a semiconductor chip is mounted, wherein the back surface of the die pad is exposed from a sealing resin.
A first die having a die pad placement region that contacts the protruding portion of the die pad, surrounded by the die pad placement region, and having an upper surface that is in contact with the die pad; and the first die A step of preparing a second mold for determining a sealing region;
Clamping the lead frame on which the semiconductor chip is mounted on the die pad to the first and second molds and simultaneously bringing the convex portion into contact with the back surface of the die pad;
Injecting the sealing resin into the sealing region determined by the first and second molds;
A step of stopping the intrusion after the sealing resin has intruded between the die pad and the convex portion and filled, and
Removing the resin-sealed lead frame from the first and second molds;
A method for manufacturing a semiconductor device, comprising:

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