Semiconductor device

Abstract

To provide a semiconductor device which can suppress formation of flash burrs on a lower surface of a die pad, in such a configuration that the lower surface of the die pad is exposed from a sealing resin.SOLUTION: A semiconductor device has a lead frame composed of a flat plate-like die pad and lead which has a mounting region having a semiconductor chip mounted on one main surface, projects to the side in an eaves shape along the one main surface and has a frame-like projection on the side parts in top view, a semiconductor chip mounted on the mounting region, and a sealing body which coats the side face of the die pad while exposing the other main surface of the die pad, and seals the semiconductor chip on the one main surface of the die pad and holds the die pad, and holds the lead, wherein a through hole penetrating through the projection in a direction crossing the one main surface is formed in the die pad.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a semiconductor device. [Background technology]

[0002] A semiconductor device is disclosed that includes a lead frame including a die pad and leads, a semiconductor chip mounted on the die pad, and a sealing resin that seals the lead frame and the semiconductor chip. For example, Patent Document 1 discloses a semiconductor device in which the lower surface of the die pad is exposed from the sealing resin and has a groove portion in which a plurality of grooves are formed on the lower surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-082446 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the semiconductor device described in Patent Document 1, for example, when a die pad with a semiconductor chip mounted thereon and leads are placed in a mold during manufacturing of the semiconductor device and sealing resin is injected into the mold, the sealing resin is guided along a groove formed on the underside of the die pad.

[0005] However, depending on the pressure applied when the sealing resin is injected, the sealing resin may flow into areas other than the groove between the mold and the lower surface of the die pad, i.e., areas that should be exposed from the sealing resin.

[0006] If this occurs, the resin adhering to the underside of the die pad other than the grooves will harden and remain as flash burrs, which will reduce the heat dissipation ability when, for example, heat generated in the semiconductor chip when the semiconductor chip is operating is tried to escape from the underside of the die pad.

[0007] The present invention has been made in consideration of the above points, and aims to provide a semiconductor device that is capable of suppressing the formation of flash burrs on the underside of a die pad in a configuration in which the underside of the die pad is exposed from the sealing resin. [Means for solving the problem]

[0008] The semiconductor device of the present invention comprises a lead frame consisting of a flat die pad and leads, the die pad having a mounting area on one of its main surfaces for mounting a semiconductor chip, the die pad protruding laterally along the one main surface like an eave and having a frame-shaped convex portion on the side when viewed from above, a semiconductor chip mounted in the mounting area, and a sealing body that covers the side surfaces of the die pad while exposing the other main surface of the die pad, seals the semiconductor chip on one of the main surfaces of the die pad, holds the die pad, and holds the leads, and the die pad is characterized in that a through hole is formed in the die pad, penetrating the convex portion in a direction intersecting the one main surface. [Brief description of the drawings]

[0009] [Figure 1] 1 is a top view of a semiconductor device according to a first embodiment. [Diagram 2] 1 is a cross-sectional view of a semiconductor device according to a first embodiment. [Diagram 3] 4 is a cross-sectional view showing a state in which a resin is injected during the manufacture of the semiconductor device according to the first embodiment. FIG. [Figure 4] FIG. 2 is a top view of a semiconductor device according to a first modified example of the first embodiment. [Diagram 5] FIG. 11 is a top view of a semiconductor device according to a second modified example of the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of the embodiments and the accompanying drawings, substantially the same or equivalent parts are designated by the same reference numerals. EXAMPLES

[0011] The configuration of a semiconductor device 100 according to a first embodiment will be described with reference to Figures 1 and 2. Figure 1 is a top view of the semiconductor device 100. Figure 2 is a cross-sectional view of the semiconductor device 100 taken along line 2-2 shown in Figure 1. In Figure 2, the up-down direction is the height direction of the semiconductor device 100. In Figure 1, for ease of viewing, the outer edge of a sealing body 17, which will be described later, is shown by a two-dot chain line, and other components sealed by the sealing body 17 are shown by a solid line.

[0012] The lead frame 11 is composed of a die pad 12 that holds a semiconductor chip 15, which will be described later, and leads 13 that are used as wiring when mounting the semiconductor device 100. The lead frame 11 is made of a metal material such as copper (Cu), iron (Fe), or an alloy based on these metals.

[0013] The die pad 12 is a plate-like body having a rectangular upper surface. The die pad 12 has a protrusion 12C on one side that protrudes laterally in an eave-like shape along the upper surface 12U and has a frame-shaped protrusion 12C in a top view. In other words, the die pad 12 has an eave portion that protrudes laterally from a side of the die pad 12 along the upper surface 12U. The protrusion 12C is formed in a frame shape in a top view.

[0014] The die pad 12 is formed with through holes 12H penetrating the base 12J of the protrusion 12C in the height direction. In the semiconductor device 100 of this embodiment, the through holes 12H have a rectangular shape in the upper surface thereof with the longitudinal direction being along each side of the die pad 12, and a plurality of through holes 12H are formed along each side of the die pad 12. In this embodiment, five through holes 12H are provided along each side of the die pad 12.

[0015] The through hole 12H has a notch 12N that terminates in the height direction from a portion on the inner side of the base 12J of the protrusion 12C on the upper surface 12U of the die pad 12 without reaching the lower surface 12L of the die pad 12. In the through hole 12H, the portion cut out by the notch 12N is exposed in a top view (see FIG. 1).

[0016] In other words, as shown in FIG. 2, the through hole 12H has a cross-sectional shape that penetrates through the base 12J of the protrusion 12C of the die pad 12 and has a stepped portion in a portion inside the base 12J of the through hole 12H.

[0017] The through hole 12H having such a cross-sectional shape can be formed, for example, by performing an etching process from the upper surface 12U side to the lower surface 12L on the portion of the base 12J of the protrusion 12C in the die pad 12. Note that the through hole 12H may be formed by a method other than the etching process, for example, a mechanical process such as drilling.

[0018] 1, the die pad 12 is provided with support bars SB, each having a rectangular top shape, which extend outward from the four corners of the frame-shaped protrusion 12C along the diagonal lines of the die pad 12. The support bars SB are used as guides when injecting a molding resin 17M, which will be described later, during the manufacture of the semiconductor device 100.

[0019] The leads 13 are elongated thin plates arranged at a distance from each other in a direction along each side of the upper surface 12U of the die pad 12 in a top view. In other words, the leads 13 are arranged along each side of the die pad 12 so as to surround the die pad 12 in a top view. In Fig. 1, seven leads 13 are provided on each side.

[0020] As shown in FIG. 2, the lead 13 has a first parallel portion 13A extending in a direction parallel to the upper surface 12U arranged on one end side, i.e., the proximal side of the die pad 12, a second parallel portion 13B extending in a direction parallel to the upper surface 12U on the other end side, i.e., the distal side of the die pad 12, and arranged lower than the first parallel portion 13A, and an inclined portion 13C inclined to connect the first parallel portion 13A and the second parallel portion 13B.

[0021] The second parallel portion 13B of the lead 13 is a portion that is joined to a printed wiring board using a joining material such as solder when, for example, the semiconductor device 100 is mounted on a printed wiring board.

[0022] The semiconductor chip 15 is a semiconductor element such as an IC chip having a rectangular upper surface shape and made of a semiconductor material such as silicon (Si). The semiconductor chip 15 is mounted on a mounting area (not shown) on the upper surface 12U of the die pad 12 using a bonding material (not shown) such as solder.

[0023] Electrode pads (not shown) are formed on the upper surface of the semiconductor chip 15 in the number corresponding to the leads 13, and each of the electrode pads of the semiconductor chip 15 and each of the leads 13 are electrically connected via wires (not shown) made of a metal such as gold (Au) or aluminum (Al).

[0024] The encapsulant 17 is a encapsulating member made of a resin such as an epoxy resin that partially covers the die pad 12 and the leads 13 to hold the die pad 12 and the leads 13 while encapsulating the semiconductor chip 15 mounted on the die pad 12.

[0025] Specifically, the sealing body 17 covers the side of the die pad 12 while exposing the lower surface 12L of the die pad 12, seals the semiconductor chip 15 on the upper surface 12U of the die pad 12 to hold the die pad 12, and holds the lead 13 by covering a portion of the first parallel portion 13A of the lead 13.

[0026] That is, in semiconductor device 100, lower surface 12L of die pad 12 and portions of first parallel portions 13A of leads 13 are exposed from sealing body 17, and the rest are sealed by sealing body 17.

[0027] As described above, the semiconductor device 100 receives electrical power from an external power source connected to a printed wiring board, for example, by electrically connecting the second parallel portions 13B of the leads 13 to the printed wiring board.

[0028] In the semiconductor device 100 mounted on the printed wiring board, the lower surface 12L of the die pad 12 is exposed from the sealing body 17, so that heat generated when the semiconductor chip 15 receives a supply of electricity and operates can be released to the outside via the lower surface 12L of the die pad 12. In other words, the semiconductor device 100 has a structure intended to release heat generated when the semiconductor chip 15 operates via the die pad 12.

[0029] For example, heat dissipation from the semiconductor device 100 may be achieved by connecting the lower surface 12L of the die pad 12 to a heat dissipation structure that dissipates heat to the outside of the device to which the semiconductor device 100 is attached via a thermally conductive material such as metal.

[0030] [Mechanism for suppressing flash burr formation on the underside of the die pad] 1 to 3, a description will be given of suppression of flash burr formation on the lower surface 12L of the die pad 12 during the manufacture of the semiconductor device 100. Fig. 3 is a cross-sectional view of the semiconductor device 100 taken along line 3-3 in Fig. 1, showing a state when molding resin is injected to form the sealing body 17 during the manufacture of the semiconductor device 100.

[0031] As shown in FIG. 3, the die pad 12 on which the semiconductor chip 15 is mounted and the leads 13 are held by a metal mold 21, and a molding resin 17M, which is the sealing body 17 before hardening, is injected into the die pad 12 and the leads 13.

[0032] Specifically, the die pad 12 on which the semiconductor chip 15 is mounted is placed on the lower die 21A of the die 21, and each of the leads 13 is fixed in a manner in which it is sandwiched between the upper die 21B and the lower die 21A of the die 21. Then, a molding resin 17M is injected into a sealing space Sp formed by the lower die 21A and the upper die 21B, and the molding resin 17M is cured to form the sealing body 17 in the semiconductor device 100.

[0033] 3, the molding resin 17M is supplied at a predetermined pressure into the sealing space Sp along the support bar SB through a gate (not shown) provided in the mold 21. The molding resin 17M is injected, for example, from the lower right corner of the die pad 12 close to the gate to the upper left corner diagonally opposite the lower right corner.

[0034] As described above, in the semiconductor device 100 of this embodiment, the through hole 12H is formed in the portion of the base 12J of the protruding portion 12C of the die pad 12. This makes it possible to suppress the formation of flash burrs on the lower surface 12L of the die pad 12, which would otherwise be caused by the molding resin 17M entering the lower surface 12L of the die pad 12, when the molding resin 17M is injected into the sealing space Sp.

[0035] A specific mechanism for suppressing the formation of flash burrs will be described below. When the molding resin 17M is injected into the above-mentioned sealing space Sp, the molding resin 17M, for example, enters the space below the protrusion 12C. For example, if the through-hole 12H is not formed in the protrusion 12C of the die pad 12, the molding resin 17M that has entered the space below the protrusion 12C has almost no escape route to the space above the protrusion 12C, and therefore the force of the molding resin 17M may concentrate on the lower end side of the die pad 12.

[0036] As a result, if the through-hole 12H is not formed in the protruding portion 12C of the die pad 12, the pressure applied to the lower end of the die pad 12 by the molding resin 17M may cause the resin to enter between the lower surface 12L of the die pad 12 and the lower mold 21A from the lower end, causing the die pad 12 to lift up and the lower surface 12L to separate from the lower mold 21A. In addition, the resin that has entered under the protruding portion 12C of the die pad 12 may generate a force that presses the protruding portion 12C upward, causing the die pad 12 to lift up.

[0037] For example, if the injected molding resin 17M gets into the gap between the lower surface 12L of the die pad 12 and the lower mold 21A, the molding resin 17M may harden in this state, causing flash burrs to be formed on the lower surface 12L of the die pad 12.

[0038] For example, if flash burrs are formed on the lower surface 12L of the die pad 12, the heat dissipation properties of the lower surface 12L of the die pad 12 may decrease when the semiconductor chip 15 is driven, which may eventually lead to an increase in temperature of the semiconductor chip 15 and cause a breakdown. Also, for example, if a large number of flash burrs remain on the lower surface 12L of the die pad 12, the effort required to remove the flash burrs in order to ensure heat dissipation may increase.

[0039] According to the semiconductor device 100 of this embodiment, as described above, the through hole 12H is formed in the convex portion 12C of the die pad 12, thereby releasing the pressure applied to the lower end of the die pad 12 when the molding resin 17M is injected, thereby preventing the molding resin 17M from entering between the lower surface 12L of the die pad 12 and the lower mold 21A.

[0040] Specifically, in the semiconductor device 100 of this embodiment, the molding resin 17M can flow around to the underside of the protrusion 12C and from the underside of the protrusion 12C through the through holes 12H to the upper surface 12U side of the die pad 12, as shown by the dashed-dotted arrow A1 in Fig. 3. This allows the pressure applied when the molding resin 17M is injected to be dispersed via the through holes 12H, and prevents the pressure of the molding resin 17M from concentrating on the lower end of the die pad 12.

[0041] Therefore, according to the semiconductor device 100 of this embodiment, the pressure applied when the molding resin 17M is injected is dispersed, thereby preventing the molding resin 17M from entering between the lower surface 12L of the die pad 12 and the lower mold 21A.

[0042] Furthermore, according to the semiconductor device 100 of this embodiment, as described above, the through hole 12H has a notch 12N that terminates in the height direction from a portion inside the base 12J of the protrusion 12C without reaching the lower surface 12L of the die pad 12.

[0043] As a result, in the semiconductor device 100 of this embodiment, for example, when the molding resin 17M flows into the through hole 12H from the upper surface 12U side of the die pad 12, the molding resin 17M hits the step portion formed by the above-mentioned notch 12N as shown by the dotted line arrow A2 in Figure 3, that is, the pressure of the molding resin 17M is applied in the downward direction in the figure, and this can also have the effect of pressing down on the die pad 12 from above.

[0044] Therefore, according to the semiconductor device 100 of this embodiment, the die pad 12 is pressed down from above, making it difficult for the lower surface 12L of the die pad 12 to float above the lower mold 21A, and it is possible to prevent the molding resin 17M from penetrating into the lower surface 12L of the die pad 12.

[0045] Therefore, according to the semiconductor device 100 of this embodiment, the through hole 12H is formed in the die pad 12, which allows the pressure of the molding resin 17M supplied from below the convex portion 12C of the die pad 12 to be released and also provides a pressing effect by the molding resin 17M supplied from above the convex portion 12C.

[0046] Therefore, according to the semiconductor device 100 of this embodiment, in a configuration in which the lower surface 12L of the die pad 12 is exposed from the sealing body 17 serving as sealing resin, it is possible to suppress the formation of flash burrs on the lower surface 12L of the die pad 12.

[0047] In the semiconductor device 100 of this embodiment, the through hole 12H formed in the protruding portion 12C of the die pad 12 has a rectangular shape in the upper surface, but is not limited thereto and may have another shape. For example, the through hole 12H may have a circular or elliptical shape in the upper surface.

[0048] Furthermore, in the semiconductor device 100 of this embodiment, the through hole 12H formed in the protrusion 12C of the die pad 12 is said to penetrate the protrusion 12C in the height direction, but it does not have to be formed in a direction perpendicular to the upper surface 12U of the die pad 12.

[0049] For example, the through hole 12H may be formed obliquely with respect to the upper surface 12U of the die pad 12. Also, for example, the through hole 12H may be formed so that the diameter on the lower surface 12L side of the die pad 12 is larger than the diameter on the upper surface 12U, or vice versa. In other words, the through hole 12H may be formed so as to have a substantially trapezoidal cross-sectional shape.

[0050] That is, it is sufficient that through hole 12H is formed so as to intersect with upper surface 12U of die pad 12. Even when through hole 12H is formed in this manner, it is possible to release the pressure of molding resin 17M supplied from below protruding portion 12C of die pad 12 and obtain the pressing effect of molding resin 17M supplied from above protruding portion 12C.

[0051] Furthermore, in the semiconductor device 100 of this embodiment, the through holes 12H formed in the protruding portion 12C of the die pad 12 are provided in groups of five along each side of the die pad 12, but this is not limited to this and the number may be increased or decreased depending on, for example, the size of the die pad 12.

[0052] In the semiconductor device 100 of this embodiment, the through holes 12H formed in the protruding portion 12C of the die pad 12 are formed along the respective sides of the die pad 12 in the top view, but this is not limited to this. For example, the through holes 12H may be formed only on two sides of the die pad 12 close to the gate into which the molding resin 17M is injected, that is, only on the right side and the bottom side of the die pad 12 in the case of FIG.

[0053] In the semiconductor device 100 of this embodiment, the die pad 12 is provided with a support bar SB at each of the four corners, but it is not necessary to provide the support bar SB. Also, a mode in which the support bar SB is provided only at the corner of the die pad 12 closest to the above-mentioned gate may be adopted.

[0054] In the semiconductor device 100 of this embodiment, the through hole 12H has the notch 12N that terminates in the height direction from a portion on the upper surface 12U of the die pad 12 that is on the inner side of the base 12J of the protrusion 12C without reaching the lower surface 12L of the die pad 12, but the through hole 12H may not have the notch 12N. For example, the through hole 12H may be formed at a position away from the base 12J of the protrusion 12C, that is, so as to penetrate only the protrusion 12C.

[0055] [Variation 1] The following describes Modification 1 of the semiconductor device 100 according to the first embodiment. Fig. 4 is a top view of a semiconductor device 110 according to Modification 1. The semiconductor device 110 is similar to the first embodiment in other respects, except for the shape of the through hole 12H.

[0056] In the semiconductor device 110 of this modified example, the through hole 12H has a rectangular shape with the longitudinal direction along each side of the semiconductor chip 15 and the length in the longitudinal direction is the same as the side of the semiconductor chip 15.

[0057] That is, in the semiconductor device 110, the through holes 12H are formed along each side of the semiconductor chip 15. Therefore, in the semiconductor device 110 of this modification, the through holes 12H have a larger area than the through holes 12H shown in the first embodiment.

[0058] Even when the through hole 12H is formed in this manner, by forming the through hole 12H in the die pad 12, it is possible to release the pressure of the molding resin 17M supplied from below the protrusion 12C of the die pad 12 and obtain the pressing effect of the molding resin 17M supplied from above the protrusion 12C.

[0059] Therefore, according to the semiconductor device 110 of this modified example, similarly to the first embodiment, in a configuration in which the lower surface 12L of the die pad 12 is exposed from the sealing body 17, it is possible to suppress the formation of flash burrs on the lower surface 12L of the die pad 12.

[0060] In the semiconductor device 110 of this modified example, the through holes 12H may be formed so as to be continuous with each other. That is, the through holes 12H may be formed so as to have a frame shape in a top view.

[0061] [Variation 2] The following describes Modification 2 of the semiconductor device 100 according to the first embodiment. Fig. 5 is a top view of a semiconductor device 120 according to Modification 2. The semiconductor device 120 is similar to the first embodiment in other respects, except for the shape of the through-hole 12H.

[0062] In the semiconductor device 120 of this modification, the through hole 12H has a longitudinal direction and a lateral direction opposite to those of the through hole 12H shown in the embodiment 1. That is, in the semiconductor device 120, the through hole 12H has a longitudinal direction perpendicular to the direction along the side of the die pad 12.

[0063] Even when the through hole 12H is formed in this manner, by forming the through hole 12H in the die pad 12, it is possible to release the pressure of the molding resin 17M supplied from below the protrusion 12C of the die pad 12 and obtain the pressing effect of the molding resin 17M supplied from above the protrusion 12C.

[0064] Therefore, according to the semiconductor device 120 of this modified example, similarly to the first embodiment, in a configuration in which the lower surface 12L of the die pad 12 is exposed from the sealing body 17, it is possible to suppress the formation of flash burrs on the lower surface 12L of the die pad 12. [Explanation of symbols]

[0065] 100, 110, 120 Semiconductor device 11 Lead frame 12 Die pad 13 Lead 15 Semiconductor chips 17 Sealing body 21 Mold

Claims

1. a lead frame including a flat die pad and leads, the flat die pad having a mounting area on one of its main surfaces for mounting a semiconductor chip, the flat die pad protruding laterally along the one of its main surfaces in an eave-like shape and having frame-shaped protrusions on its sides when viewed from above; A semiconductor chip mounted in the mounting area; a sealing body that covers a side surface of the die pad while exposing the other main surface of the die pad, seals the semiconductor chip on the one main surface of the die pad, holds the die pad, and holds the leads, The semiconductor device according to claim 1, wherein the die pad has a through hole penetrating the protrusion in a direction intersecting with the one main surface.

2. 2. The semiconductor device according to claim 1, wherein the through hole is formed so as to penetrate a base portion of the protrusion.

3. 3. The semiconductor device according to claim 2, wherein the through hole includes a notch portion that terminates from a portion inside a base of the protrusion on the one main surface of the die pad without reaching the other main surface of the die pad.

4. 3. The semiconductor device according to claim 1, wherein the through hole penetrates the protrusion in a direction perpendicular to the one main surface.

5. 3. The semiconductor device according to claim 1, wherein the through holes are formed in a plurality of positions along an outer edge of the semiconductor chip in a top view of the one main surface.

6. The semiconductor chip has a rectangular top surface shape, 6. The semiconductor device according to claim 5, wherein the through hole has a rectangular shape with a longitudinal direction along each side of the semiconductor chip.

7. The semiconductor chip has a rectangular top surface shape, 6. The semiconductor device according to claim 5, wherein the through hole has a rectangular shape whose longitudinal direction is perpendicular to the direction along each side of the semiconductor chip.

8. The semiconductor chip has a rectangular top surface shape, 3. The semiconductor device according to claim 1, wherein the through hole has a rectangular shape with a longitudinal direction along each side of the semiconductor chip, and the longitudinal length is the same as the length of the sides of the semiconductor chip.

Images