Semiconductor device and method for manufacturing the same

Abstract

To obtain a semiconductor device and a method for manufacturing the same that suppress deterioration of insulation properties. [Solution] The device comprises a semiconductor element, a heat spreader to which the other side of the semiconductor element is connected to one side, a lead frame to which one side of the semiconductor element is connected to a connection portion which is the side of one end, and a molded resin that seals the semiconductor element, the heat spreader, and the lead frame. The intermediate portion of the lead frame between the connection portion and the exposed portion which is the side of the other end is spaced apart from the bonding surface of the heat spreader and extends along the bonding surface. A thin-walled portion of the molded resin is formed between the portion of the intermediate portion opposite to the side of the heat spreader and the outside, and a thick-walled portion of the molded resin is formed on the portion of the intermediate portion opposite to the side where the thin-walled portion is formed. The thickness of the thin-walled portion is smaller than the thickness of the thick-walled portion, and the lead frame has a through hole in the intermediate portion that connects the thin-walled portion and the thick-walled portion.

Description

Technical Field

[0001] The present disclosure relates to a semiconductor device and a method for manufacturing the same.

Background Art

[0002] Semiconductor devices are used to control and rectify relatively large amounts of electric power in vehicles such as railway vehicles, hybrid cars, and electric vehicles, and industrial machines. Therefore, since a high voltage of several hundred volts or more is applied to the semiconductor device, insulation between the semiconductor device and the outside is required. Thus, a configuration in which a semiconductor element such as a diode or a transistor included in the semiconductor device and a lead frame are resin-sealed by transfer molding to ensure insulation is used for the semiconductor device.

[0003] When the semiconductor device is resin-sealed by transfer molding, the thickness of the mold resin will be different between one side and the other side of the lead frame in the direction perpendicular to the surface of the lead frame. For example, a thin portion with a small thickness of the mold resin is formed on one side of the lead frame, and a thick portion with a large thickness of the mold resin is formed on the other side of the lead frame.

[0004] When the thin portion and the thick portion are formed, when resin injection starts in the transfer molding process, the mold resin preferentially flows from the thick portion, and then the mold resin wraps around the end face of the lead frame and flows into the thin portion. Therefore, the portion of the thin portion becomes the final filling position. Since it is difficult for the mold resin to flow into the thin portion where the thickness of the mold resin is small, molding defects such as the mold resin remaining unfilled in the thin portion may occur. There has been a problem that the insulation performance of the semiconductor device deteriorates due to the occurrence of molding defects where the mold resin remains unfilled.

[0005] A semiconductor device configuration has been disclosed that aims to avoid molding defects resulting in incomplete filling of the mold resin (see, for example, Patent Document 1). In the configuration disclosed in Patent Document 1, by adjusting the tip shape of the lead frame so that the resin thickness of the thin-walled portion is increased, the mold resin flowing to the thick-walled and thin-walled portions reaches the surface facing the gate opening almost simultaneously, thereby suppressing incomplete filling of the mold resin. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2010-103411 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] In the above-mentioned Patent Document 1, the shape of the lead frame tip facing the gate opening is adjusted so that the thickness of the mold resin in the thin-walled portion is increased. This allows the mold resin flowing into the thin-walled and thick-walled portions to reach the surface facing the gate opening almost simultaneously, thereby suppressing the occurrence of voids and weld lines that result in unfilled areas of mold resin. However, with this configuration, the distance between the internal structural components of the semiconductor device and the lead frame becomes small, and the insulating distance between the structural components and the lead frame is not ensured, resulting in a deterioration of the insulating properties of the semiconductor device.

[0008] Therefore, the purpose of this disclosure is to obtain a semiconductor device that suppresses deterioration of insulating properties. [Means for solving the problem]

[0009] The semiconductor device of this disclosure comprises one or more semiconductor elements, a heat spreader to which the other surface of the semiconductor element is connected to one surface via a bonding member, a lead frame to which one surface of the semiconductor element is connected to one end via a bonding member, and a molded resin that seals the semiconductor element, the heat spreader, and the lead frame with the other end of the lead frame, opposite to the connection portion which is one end of the lead frame, exposed. The intermediate portion of the lead frame between the connection portion and the exposed portion which is the other end is spaced apart from the bonding surface which is one surface of the heat spreader, and extends along the bonding surface. A thin-walled portion of the molded resin is formed between the portion of the intermediate portion opposite to the heat spreader side and the outside, and a thick-walled portion of the molded resin is formed on the portion of the intermediate portion opposite to the side where the thin-walled portion is formed. The thickness of the thin-walled portion in the direction in which the thin-walled portion, the intermediate portion, and the thick-walled portion overlap is smaller than the thickness of the thick-walled portion, and the lead frame has a through hole in the intermediate portion that connects the thin-walled portion and the thick-walled portion.

[0010] The present disclosure's method for manufacturing a semiconductor device comprises: a component preparation step of preparing one or more semiconductor elements, a lead frame, and a heat spreader; a through-hole formation step of forming a through-hole in an intermediate portion sandwiched between one end and the other end of the lead frame; a bonding step of connecting the other surface of the semiconductor element to one surface of the heat spreader via a bonding member, and connecting one surface of the semiconductor element to one end of the lead frame via a bonding member; and placing the other surface of the heat spreader at the bottom inside of a first mold, leaving a gap between it and the bonding surface which is one surface of the heat spreader, extending the intermediate portion along the bonding surface, and placing the other end of the lead frame in the first mold. The process includes a resin inflow step in which the second mold is placed over the first mold with the second mold protruding from the inside toward the outside of the first mold, and mold resin is inflowed around the semiconductor element, heat spreader, and lead frame inside the first and second molds, a thin-walled portion of mold resin is formed in the portion between the intermediate portion and the second mold, a thick-walled portion of mold resin is formed on the side of the intermediate portion opposite to the side where the thin-walled portion is formed, the thickness of the thin-walled portion in the direction in which the thin-walled portion, intermediate portion and thick-walled portion overlap is smaller than the thickness of the thick-walled portion, a through hole connects the thin-walled portion and the thick-walled portion, and when viewed in a direction perpendicular to the joining surface, the second mold has one or more gas vents in the portion of the second mold around the through hole. [Effects of the Invention]

[0011] The semiconductor device of this disclosure comprises one or more semiconductor elements, a heat spreader, a lead frame, and a molded resin that seals the semiconductor elements, the heat spreader, and the lead frame. The intermediate portion of the lead frame between the connection portion and the exposed portion extends along the bonding surface, spaced apart from the bonding surface of the heat spreader. A thin-walled portion of the molded resin is formed between the portion of the intermediate portion opposite to the heat spreader side and the outside. A thick-walled portion of the molded resin is formed on the portion of the intermediate portion opposite to the side where the thin-walled portion is formed. The thickness of the thin-walled portion in the direction in which the thin-walled portion, the intermediate portion, and the thick-walled portion overlap is smaller than the thickness of the thick-walled portion. The lead frame has through holes in the intermediate portion that connect the thin-walled portion and the thick-walled portion. Therefore, the molded resin that flows through the thick-walled portion wraps around the end face of the lead frame and flows into the thin-walled portion side, as well as flowing into the thin-walled portion side from the through holes. This prevents the molded resin from remaining unfilled in the thin-walled portion where it is difficult to flow. Since it is possible to avoid incomplete filling of the mold resin, the occurrence of molding defects is suppressed, and thus a semiconductor device with suppressed deterioration of insulation can be obtained.

[0012] The semiconductor device manufacturing method of this disclosure comprises a component preparation step, a through-hole formation step, a joining step, and a resin inflow step, wherein a thin-walled portion of molded resin is formed in the portion between the intermediate portion and the second mold, and a thick-walled portion of molded resin is formed on the portion of the intermediate portion opposite to the side where the thin-walled portion is formed, the thickness of the thin-walled portion in the direction in which the thin-walled portion, the intermediate portion, and the thick-walled portion overlap is smaller than the thickness of the thick-walled portion, the through-hole connects the thin-walled portion and the thick-walled portion, and the second mold has one or more gas vents in the portion of the second mold around the through-hole when viewed in a direction perpendicular to the joining surface, so that compressed air and gases caused by the molded resin that tend to be generated in the weld line portion of the thin-walled portion which is the final filling position can be efficiently discharged to the outside. Because compressed air and gases caused by the molded resin are efficiently discharged to the outside, it is possible to avoid the molded resin remaining unfilled in the weld line portion of the thin-walled portion which is the final filling position due to compressed air and gases caused by the molded resin. Since it is possible to avoid incomplete filling of the mold resin, the occurrence of molding defects is suppressed, and thus a semiconductor device with suppressed deterioration of insulation can be obtained. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic plan view of the semiconductor device according to Embodiment 1. [Figure 2] This is a cross-sectional view of the semiconductor device cut at the AA cross-sectional position in Figure 1. [Figure 3] This is a cross-sectional view of the semiconductor device cut at the BB cross-sectional position in Figure 1. [Figure 4] This is a cross-sectional view of another semiconductor device cut at the BB cross-sectional position in Figure 1. [Figure 5] This is a cross-sectional view of another semiconductor device cut at the BB cross-sectional position in Figure 1. [Figure 6] This is a plan view showing the external appearance of the semiconductor device according to Embodiment 1. [Figure 7] This figure shows the manufacturing process of a semiconductor device according to Embodiment 1. [Figure 8] This is a plan view showing a schematic of a semiconductor device in the comparative example. [Figure 9] Figure 8 is a cross-sectional view of the semiconductor device cut at the CC cross-sectional position. [Figure 10] Figure 8 is a cross-sectional view of the semiconductor device cut at the DD cross-sectional position. [Figure 11] This is a cross-sectional view of another semiconductor device cut at the DD cross-sectional position shown in Figure 8. [Modes for carrying out the invention]

[0014] The semiconductor device and its manufacturing method according to the embodiments of this disclosure will be described below with reference to the drawings. In each drawing, the same or equivalent components and parts will be denoted by the same reference numerals. Also, each drawing is schematic and does not represent the actual dimensional relationships of the parts of the semiconductor device.

[0015] Embodiment 1. FIG. 1 is a plan view showing an outline of a semiconductor device 100 according to Embodiment 1, a view showing the inside of the semiconductor device 100 through a mold resin 7, FIG. 2 is a cross-sectional view of the semiconductor device 100 cut at the A-A cross-sectional position in FIG. 1, FIG. 3 is a cross-sectional view of the semiconductor device 100 cut at the B-B cross-sectional position in FIG. 1, FIG. 4 is a cross-sectional view of another semiconductor device 100 cut at the B-B cross-sectional position in FIG. 1, FIG. 5 is a cross-sectional view of yet another semiconductor device 100 cut at the B-B cross-sectional position in FIG. 1, FIG. 6 is a plan view showing the appearance of the semiconductor device 100, and FIG. 7 is a view showing a manufacturing process of the semiconductor device 100. FIGS. 3 to 5 show a first mold 10 and a second mold 11 used in the resin inflow process, and in the part of the mold resin 7, the flow of the mold resin 7 when the mold resin 7 is injected in the X direction in the resin inflow process is indicated by an arrow. For convenience of explanation, directions are indicated based on the XYZ axes shown in the figures. In the figures, the direction in which the heat spreader 3a and the additional heat spreader 3b are arranged side by side is the Y direction, the direction perpendicular to the Y direction and parallel to the joint surface 3a1 of the heat spreader 3a is the X direction. The thickness direction of the semiconductor device 100 is synonymous with the Z direction perpendicular to the X direction and the Y direction. The semiconductor device 100 is a resin-sealed semiconductor device 100 in which semiconductor elements 1a to 1d are sealed with a mold resin 7. The semiconductor device 100 is used, for example, for power control. The semiconductor device 100 used for power control is, for example, a device that converts an input current from DC to AC, from AC to DC, or an input voltage to a different voltage.

[0016] <Semiconductor device 100> The semiconductor device 100 includes one or more semiconductor elements, a heat spreader 3a, a lead frame 4a, and a mold resin 7 that seals the semiconductor elements, the heat spreader 3a, and the lead frame 4a. In the present embodiment, as shown in FIG. 1, the semiconductor device 100 includes a plurality of semiconductor elements 1a and 1b, and the semiconductor elements 1a and 1b are formed in a plate shape. The semiconductor device 100 is not limited to a configuration including a plurality of semiconductor elements, and the semiconductor device 100 may have a configuration including a single semiconductor element. The heat spreader 3a is formed in a plate shape. The shape of the heat spreader 3a is not limited to a plate shape and may be a block shape.

[0017] On the heat spreader 3a, the other surfaces of the semiconductor elements 1a and 1b are connected to one surface via the bonding member 2b. On the lead frame 4a, one surface of the semiconductor elements 1a and 1b is connected to one end side via the bonding member 2c. As shown in FIG. 2, the semiconductor elements 1a and 1b, the heat spreader 3a, and the lead frame 4a are encapsulated by the mold resin 7 with the other end side of the lead frame 4a, which is opposite to the connection portion 4a1 on one end side, exposed. The intermediate portion 4a3 between the connection portion 4a1 and the exposed portion 4a2, which is the other end side, of the lead frame 4a extends along the bonding surface 3a1 of the heat spreader 3a with a gap from the bonding surface 3a1, which is one surface of the heat spreader 3a. The lead frame 4a has a through hole 9 in the intermediate portion 4a3. Details of the through hole 9 will be described later.

[0018] In the present embodiment, as shown in FIG. 1, the semiconductor device 100 further includes semiconductor elements 1c and 1d, an additional heat spreader 3b, lead frames 4b, 4c, and 4d, an insulating sheet 5, and a metal plate 6. The heat spreader 3a and the additional heat spreader 3b are arranged side by side with a gap on the same plane. On the additional heat spreader 3b, the other surfaces of the semiconductor elements 1c and 1d are connected to the bonding surface 3b1, which is one surface, via the bonding member 2b. On the lead frame 4b, one surface of the semiconductor elements 1c and 1d is connected to the other end side via the bonding member 2c. One end side of the lead frame 4b is connected to the bonding surface 3a1 of the heat spreader 3a via the bonding member 2a. In the present embodiment, one end side of the lead frame 4b is provided with two extensions in the Y direction from the other end side of the lead frame 4b and is connected to the bonding surface 3a1 on each of the one side and the other side in the X direction, but the configuration of the lead frame 4b is not limited to this. The portion extending in the Y direction from the other end side of the lead frame 4b may be provided at one location.

[0019] One end of lead frame 4c is connected to the bonding surface 3b1 of the additional heat spreader 3b via bonding member 2a. One end of lead frame 4c is exposed from the mold resin 7. The other end of lead frame 4d is connected to the bonding surface 3a1 of the heat spreader 3a via bonding member 2a. The other end of lead frame 4d is exposed from the mold resin 7. The semiconductor elements 1a, 1b, 1c, and 1d are connected to the outside of the semiconductor device 100 via the externally exposed lead frames 4a, 4c, and 4d.

[0020] One side of the insulating sheet 5 is thermally connected to the other side of the heat spreader 3a and the other side of the additional heat spreader 3b, as shown in Figure 2. One side of the metal plate 6 is thermally connected to the other side of the insulating sheet 5. The other side of the metal plate 6 is exposed from the mold resin 7. The heat generated when the semiconductor elements 1a, 1b, 1c, and 1d operate is transferred in the following order: bonding member 2b, heat spreader 3a and additional heat spreader 3b, insulating sheet 5, and metal plate 6, and is dissipated to the outside from the other side of the metal plate 6 exposed from the mold resin 7.

[0021] In this embodiment, the semiconductor device 100 has a configuration called a 2-in-1 module. As shown in Figure 1, semiconductor elements 1a and 1c as switching elements and semiconductor elements 1b and 1d as rectifying elements are connected in antiparallel, and there are two sets of element pairs. The configuration of the semiconductor device 100 is not limited to this, and it is possible to mount the required number of semiconductor elements depending on the application in which the semiconductor device 100 is used.

[0022] Details of each component of the semiconductor device 100 will now be described. Semiconductor elements 1a and 1c are power semiconductor elements, such as IGBTs (Insulated Gate Bipolar Transistors) or MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), which are used for power control. Power semiconductor elements drive a load by supplying a large current to it. In this embodiment, a switching element without parasitic diodes, such as an IGBT, is used, and a rectifier element, such as a freewheeling diode, is connected in parallel. However, this is not the only configuration; an RC-IGBT (Reverse Conducting IGBT), in which the switching element and freewheeling diode are integrated, may also be used. Alternatively, a MOSFET may be used, with the parasitic diode of the MOSFET used as the freewheeling diode. When using an RC-IGBT, each of the semiconductor elements 1a, 1b, and 1c, 1d is composed of a single semiconductor element.

[0023] The material of semiconductor elements 1a to 1d is, for example, silicon (Si). The material of semiconductor elements 1a to 1d is not limited to silicon; for example, it may be a material selected from the group consisting of silicon carbide (SiC), gallium nitride (GaN) and other gallium nitride-based materials, and diamond. These are so-called wide-bandgap semiconductor materials, which have a wider bandgap than silicon. When semiconductor elements 1a to 1d are formed using wide-bandgap semiconductor materials, the semiconductor elements can be operated at higher temperatures than silicon semiconductor elements, making wide-bandgap semiconductor materials suitable for carrying large currents. In addition, the time change amount di / dt of the current generated during switching can be made larger than in elements made of silicon. Furthermore, wide-bandgap semiconductor elements have low on-resistance, high allowable current density, low power loss, and low heat generation, so the chip area can be reduced. As the chip area is reduced, the semiconductor device 100 can be miniaturized.

[0024] The heat spreader 3a, additional heat spreader 3b, lead frames 4a, 4b, 4c, 4d, and metal plate 6 are manufactured from a metal material with excellent electrical and thermal conductivity, for example, by cutting or pressing. Among metals with excellent electrical conductivity, copper is a particularly desirable material for these components from the viewpoint of electrical resistance, processability, and cost. Here, copper refers to pure copper or copper alloys with copper as the main component.

[0025] A thermosetting resin material is used for the molding resin 7. The thermosetting resin material is, for example, an epoxy resin filled with hard inorganic powder such as fused silica, which has a low coefficient of thermal expansion. The molding resin 7 does not need to have high thermal conductivity. Therefore, fused silica, among silicon dioxide (silica), is optimal as the inorganic filler contained in the thermosetting resin material because it has good fluidity when incorporated into the thermosetting resin material and its coefficient of linear expansion can be easily adjusted. Depending on the heat dissipation of the semiconductor device 100, the amount of heat generated during operation, and the operating temperature, a general bisphenol type or phenol novolac type epoxy resin can be used. However, the molding resin 7 is not limited to these materials as long as it can encapsulate and protect the semiconductor elements 1a to 1d. As the operating temperature of the semiconductor elements 1a to 1d increases, a highly heat-resistant resin using, for example, a naphthalene type or a polyfunctional type may be used as the molding resin 7.

[0026] To prevent excessive thermal deformation forces from being generated on semiconductor elements 1a-1d due to differences in the coefficients of thermal expansion between the mold resin 7 and the heat spreader 3a, additional heat spreader 3b, and lead frames 4a-4d, it is preferable to use a resin for the mold resin 7 that has a coefficient of thermal expansion close to that of the heat spreader 3a, additional heat spreader 3b, and lead frames 4a-4d. When the heat spreader 3a, additional heat spreader 3b, and lead frames 4a-4d are formed from pure copper, the coefficient of thermal expansion of pure copper is 16 [ppm / K] to 17 [ppm / K], so it is desirable that the coefficient of thermal expansion of the mold resin 7 be in the range of 15 [ppm / K] to 18 [ppm / K], which approximates the coefficient of thermal expansion of pure copper. The coefficient of thermal expansion of the mold resin 7 can be changed by adjusting the amount of inorganic filler. By adjusting the coefficient of thermal expansion of the molding resin 7 to approximate that of pure copper, the thermal deformation force inside the semiconductor device 100 can be reduced, thereby improving the reliability of the semiconductor device 100 against temperature cycles.

[0027] The joining member 2a uses a joining material, for example, one containing solder material, to ensure electrical conductivity between the heat spreader 3a and the additional heat spreader 3b and the lead frames 4b, 4c, and 4d. The joining member 2b is preferably a joining material selected from the group consisting of a joining material containing solder material, a sinterable filler mainly composed of silver, a brazing material mainly composed of silver, a material in which copper is dispersed in tin, gold tin mainly composed of gold, and gold-based alloys such as gold germanium. Since these joining materials have high thermal conductivity and electrical conductivity, they can thermally and electrically connect the heat spreader 3a and the additional heat spreader 3b to the semiconductor elements 1a to 1d. The joining member 2c uses a joining material, for example, one containing solder material, to ensure electrical conductivity between the semiconductor elements 1a to 1d and the lead frames 4a and 4b. If the strength of the joining member 2c is low, cracks will occur in the joining member 2c. Therefore, when using a joining material containing solder material for the joining member 2c, a joining material that is a high-strength material with a tensile strength of approximately 40 MPa or more is optimal as the joining member 2c.

[0028] The insulating sheet 5 is required to ensure electrical insulation between the semiconductor elements 1a to 1d and the metal plate 6, while also providing heat dissipation properties to transfer the heat generated when the semiconductor elements 1a to 1d operate to one side of the metal plate 6 and dissipate it from the other side. The insulating sheet 5 is made of, for example, a thermosetting resin filled with an inorganic filler that has high thermal conductivity and insulating properties, and the heat spreader 3a and additional heat spreader 3b are bonded to the metal plate 6 by the thermosetting reaction of the resin. Here, the insulating sheet 5 is made of a material that combines heat dissipation, insulation, and adhesion, and has a structure in which an inorganic powder filler such as highly thermally conductive ceramic particles is contained in a thermosetting resin such as epoxy resin. Suitable inorganic fillers with high thermal conductivity include ceramic particles such as aluminum nitride, silicon nitride, boron nitride, aluminum oxide (alumina), silicon oxide (silica), magnesium oxide, zinc oxide, and titanium oxide. Furthermore, any of these inorganic fillers may be used individually, or a mixture of several types may be used.

[0029] <Comparative Example> Prior to describing the through-hole 9 and its surrounding structure, which are the essential parts of this disclosure, the configuration of the comparative example will be described using Figures 8 to 11. Figure 8 is a schematic plan view of the semiconductor device 101 of the comparative example, showing the inside of the semiconductor device 101 through the mold resin 7. Figure 9 is a cross-sectional view of the semiconductor device 101 cut at the CC cross-sectional position in Figure 8. Figure 10 is a cross-sectional view of the semiconductor device 101 cut at the DD cross-sectional position in Figure 8. Figure 11 is a cross-sectional view of another semiconductor device 101 cut at the DD cross-sectional position in Figure 8. Figures 10 and 11 also show the first mold 10 and the second mold 11 used in the resin inflow process. In the configuration of the comparative example, as shown in Figure 8, the lead frame 4a does not have a through-hole 9 in the intermediate portion 4a3. The other configurations are the same as those shown in Figure 1, so a description of the similar configurations will be omitted.

[0030] When the semiconductor device 101 is resin-encapsulated by transfer molding, the thickness of the molded resin 7 will differ on one side and the other side of the lead frame 4a in a direction perpendicular to the surface of the lead frame 4a. As shown in Figure 9, a thin-walled portion 14 of the molded resin 7 is formed between the portion of the intermediate part 4a3 opposite to the heat spreader 3a and the outside, and a thick-walled portion 15 of the molded resin 7 is formed on the portion of the intermediate part 4a3 opposite to the side where the thin-walled portion 14 is formed. In Figures 10 and 11, the flow of the molded resin 7 when it is injected in the X direction during the transfer molding process is indicated by arrows. The difference between Figure 10 and Figure 11 is the variation in the assembly of the lead frame 4a in the Z direction when the lead frame 4a is assembled. The lead frame 4a shown in Figure 10 is closer to the insulating sheet 5 than the lead frame 4a shown in Figure 11. Therefore, the thickness of the thin-walled portion 14 shown in Figure 10 is greater than the thickness of the thin-walled portion 14 shown in Figure 11.

[0031] When a thin-walled section 14 and a thick-walled section 15 are formed, when resin injection begins in the transfer molding process, the mold resin 7 preferentially flows from the thick-walled section 15, then the mold resin 7 wraps around the end face 4a4 of the lead frame 4a, and flows into the thin-walled section 14. Therefore, the thin-walled section 14 becomes the final filling location. In this way, the mold resin 7 does not easily flow into the thin-walled section 14, where the thickness of the mold resin 7 is small, resulting in molding defects where the mold resin 7 is not filled in the thin-walled section 14. At the location where the weld line 13a is formed in Figures 10 and 11, the mold resin 7 is not filled, resulting in molding defects at the location of the weld line 13a. In Figures 10 and 11, the thickness of the thin-walled section 14 is different, so the position of the weld line 13a is different, but molding defects occur in both thicknesses. When molding defects occur where the mold resin 7 is not filled, the insulation performance of the semiconductor device 101 deteriorates.

[0032] <Through hole 9> The through-hole 9 and the surrounding structure, which are the essential parts of this disclosure, will now be described. As shown in Figure 2, a thin-walled portion 14 of the molded resin 7 is formed between the portion of the intermediate portion 4a3 opposite to the heat spreader 3a and the outside, and a thick-walled portion 15 of the molded resin 7 is formed on the portion of the intermediate portion 4a3 opposite to the side where the thin-walled portion 14 is formed. The thickness of the thin-walled portion 14 in the direction in which the thin-walled portion 14, the intermediate portion 4a3, and the thick-walled portion 15 overlap is smaller than the thickness of the thick-walled portion 15. In the figure, the direction in which the thin-walled portion 14, the intermediate portion 4a3, and the thick-walled portion 15 overlap is the Z direction. The lead frame 4a has a through-hole 9 in the intermediate portion 4a3 that connects the thin-walled portion 14 and the thick-walled portion 15.

[0033] With this configuration, as shown in Figure 3, the mold resin 7 that flows through the thick section 15 wraps around the end face 4a4 of the lead frame 4a and flows into the thin section 14, as well as from the through hole 9. The thin section 14 is the final filling position, as in the comparative example, but because the mold resin 7 flows into the thin section 14 from both the end face 4a4 of the lead frame 4a and the through hole 9, it is possible to avoid the mold resin 7 remaining unfilled in the thin section 14 where it is difficult to flow. Since it is possible to avoid the mold resin 7 remaining unfilled, the occurrence of molding defects is suppressed, and a semiconductor device 100 with suppressed deterioration of insulation can be obtained. Furthermore, as in Patent Document 1, the shape of the tip of the lead frame is not adjusted, so the deterioration of the insulation of the semiconductor device caused by adjustment of the shape of the tip of the lead frame can be suppressed.

[0034] As the mold resin 7 flows into the thin-walled portion 14 from both the end face 4a4 of the lead frame 4a and the through hole 9, a weld line 13 is formed in the portion of the thin-walled portion 14 surrounding the through hole 9 when viewed perpendicular to the joint surface 3a1, as shown in Figure 6. In Figure 6, the through hole 9 and the internal portion of the semiconductor device 100 of the lead frame 4a are shown with dashed lines. In Figure 6, the weld line 13 is schematically shown as a circle, but the weld line 13 is not limited to a circle and may also have an ellipse or other shape with a major axis in the direction in which the mold resin 7 flows. In Figures 3 to 5, the weld line on one side in the X direction is referred to as weld line 13a, and the weld line on the other side in the X direction is referred to as weld line 13b.

[0035] In this way, by providing the through hole 9, weld lines 13a and 13b are intentionally generated in the thin-walled portion 14 around the through hole 9. Weld line 13a is the point where the mold resin 7 that has wrapped around from the end face 4a4 of the lead frame 4a and the mold resin 7 that has flowed from the through hole 9 to the thin-walled portion 14 meet. Weld line 13b is the point where the mold resin 7 that has wrapped around from the through hole 9 and the mold resin 7 that has flowed to the thin-walled portion 14 from the beginning meet.

[0036] Since a weld line 13 is formed in the portion surrounding the through-hole 9 of the thin-walled portion 14, the final filling position of the mold resin 7 in the thin-walled portion 14 can be formed in the portion surrounding the through-hole 9 of the thin-walled portion 14, thus avoiding any unfilled areas of the mold resin 7 in the thin-walled portion 14. Because unfilled areas of the mold resin 7 can be avoided, the occurrence of molding defects can be suppressed, and a semiconductor device 100 with suppressed deterioration of insulation can be obtained.

[0037] In the configuration shown in Figure 3, the outer portion of the thin-walled section 14 is flat. However, the configuration of the outer portion of the thin-walled section 14 is not limited to this. As shown in Figure 4, one or more recesses 14a may be formed in the thin-walled section 14 at the weld lines 13a and 13b and in the portions surrounding the weld lines 13a and 13b. The recesses 14a are formed by gas vents 12a and 12b, which will be described in detail later, protruding toward the thin-walled section 14. In this embodiment, two gas vents 12a and 12b are provided, and since the two gas vents 12a and 12b protrude toward the thin-walled section 14, two recesses 14a are formed in the thin-walled section 14. The number of recesses 14a is not limited to two; there may be one or more. When the gas vents 12a and 12b protrude toward the thin-walled portion 14 to form a recess 14a, no protrusions are formed on the outer part of the thin-walled portion 14. Therefore, the semiconductor device 100 and other externally installed components do not interfere with each other, thereby improving the freedom of installation of the semiconductor device 100.

[0038] Furthermore, as shown in Figure 5, one or more protrusions 14b projecting outward may be formed in the thin-walled portion 14, in the portions of the weld lines 13a and 13b and in the portions surrounding the weld lines 13a and 13b. The protrusions 14b are formed by the gas vents 12a and 12b, which will be described in detail later, being recessed inward from the inner surface of the second mold 11. In this embodiment, two gas vents 12a and 12b are provided, and since the two gas vents 12a and 12b are recessed inward from the inner surface of the second mold 11, two protrusions 14b are formed in the thin-walled portion 14. The number of protrusions 14b is not limited to two; there may be one or more. When the gas vents 12a and 12b are recessed inward from the inner surface of the second mold 11 to form a protrusion 14b, the protrusion 14b forms a thicker thin-walled portion 14, which improves the fluidity of the mold resin 7 in that area, thereby improving the gas discharge efficiency by the gas vents 12a and 12b.

[0039] In this embodiment, as shown in Figure 2, when viewed in a direction perpendicular to the bonding surface 3a1, the through-hole 9 is formed overlapping the portion between the heat spreader 3a and the additional heat spreader 3b. This configuration allows for a larger thickness of the thickened portion 15 in the Z direction in the portion where the through-hole 9 is formed. As the thickness of the thickened portion 15 increases, the fluidity of the mold resin 7 in the thickened portion 15 is improved, thereby improving the fluidity of the mold resin 7 that flows around the end face 4a4 of the lead frame 4a and into the thinned portion 14. Because the fluidity of the mold resin 7 that flows around the end face 4a4 of the lead frame 4a and into the thinned portion 14 is improved, it is possible to further avoid the mold resin 7 remaining unfilled in the thinned portion 14 where it is difficult to flow. As the mold resin 7 remaining unfilled is further avoided, a semiconductor device 100 with further suppressed deterioration of insulation can be obtained.

[0040] <Method for manufacturing semiconductor device 100> The manufacturing method for the semiconductor device 100 will be explained using Figure 7. The manufacturing method for the semiconductor device 100 shown in Figure 1 comprises a component preparation step (S11), a through-hole formation step (S12), a bonding step (S13), and a resin inflow step (S14). The resin inflow step is a transfer molding step.

[0041] The details of each process will be explained. In the component preparation process, one or more semiconductor elements, lead frames, and heat spreaders are prepared. In this embodiment, semiconductor elements 1a to 1d, lead frames 4a to 4d, heat spreader 3a, and an additional heat spreader 3b are prepared. In this embodiment, the semiconductor device 100 further comprises an insulating sheet 5 and a metal plate 6, but the description of the manufacturing methods for these components is omitted.

[0042] In the through-hole formation process, a through-hole 9 is formed in the intermediate portion 4a3 sandwiched between one end and the other end of the lead frame 4a. In the through-hole formation process of this embodiment, the through-hole 9 is formed by die pressing. The method for forming the through-hole 9 is not limited to press working; other methods such as etching may also be used. By forming the through-hole 9 by press working in this way, the burrs and flash generated by die pressing increase the surface area of ​​the lead frame 4a, thereby improving the adhesive strength between the lead frame 4a and the mold resin 7.

[0043] In the bonding process, the other surfaces of semiconductor elements 1a and 1b are connected to one surface of the heat spreader 3a via bonding member 2b, and one surface of semiconductor elements 1a and 1b is connected to one end of the lead frame 4a via bonding member 2c. In this embodiment, the other surfaces of semiconductor elements 1c and 1d are further connected to one surface of an additional heat spreader 3b via bonding member 2b, one surface of semiconductor elements 1c and 1d is connected to the other end of the lead frame 4b via bonding member 2c, and one end of the lead frame 4b is connected to one surface of the heat spreader 3a via bonding member 2a. In this embodiment, one end of the lead frame 4c is further connected to the bonding surface 3b1 of the additional heat spreader 3b via bonding member 2a, and the other end of the lead frame 4d is connected to the bonding surface 3a1 of the heat spreader 3a via bonding member 2a.

[0044] In the resin inflow process, first, the other side of the heat spreader 3a is placed at the bottom inside of the first mold 10. In this embodiment, the other side of an additional heat spreader 3b is further placed at the bottom inside of the first mold 10. The heat spreader 3a and the additional heat spreader 3b are placed on the same plane with a gap between them. Next, the intermediate portion 4a3 is extended along the bonding surface 3a1, leaving a gap between it and the bonding surface 3a1, which is one side of the heat spreader 3a, and the other end of the lead frame 4a is projected from the inside of the first mold 10 toward the outside of the first mold 10. With this, the second mold 11 is placed over the first mold 10 to close the mold. Next, mold resin 7 is inflowed through the gate opening 8 around the semiconductor elements 1a to 1d, the heat spreader 3a, the additional heat spreader 3b, and the lead frames 4a to 4d inside the first mold 10 and the second mold 11. The gate opening 8 will be described later.

[0045] After the molding resin 7 has hardened to a certain extent, the molded semiconductor device 100 can be obtained by opening the mold. If the resin has not hardened sufficiently in the mold, an additional step may be taken to fully harden the molding resin 7 by further heating the semiconductor device 100.

[0046] In the above process, a thin-walled portion 14 of the mold resin 7 is formed in the area between the intermediate portion 4a3 and the second mold 11, and a thick-walled portion 15 of the mold resin 7 is formed on the side of the intermediate portion 4a3 opposite to the side where the thin-walled portion 14 is formed. In the direction in which the thin-walled portion 14, the intermediate portion 4a3, and the thick-walled portion 15 overlap, the thickness of the thin-walled portion 14 is smaller than the thickness of the thick-walled portion 15, and the through hole 9 connects the thin-walled portion 14 and the thick-walled portion 15. Viewed in a direction perpendicular to the joining surface 3a1, the second mold 11 has one or more gas vents in the portion of the second mold 11 around the through hole 9.

[0047] In this embodiment, as shown in Figure 3, the second mold 11 has two gas vents 12a and 12b. The number of gas vents is not limited to two; there may be one or more. The gas vents are parts that release air compressed by the mold resin 7 flowing inside the mold. The gas vents are also parts that discharge gas generated from the mold resin 7 flowing inside the mold. Ejector pins or movable pins can be used for the gas vents 12a and 12b. Normally, since ejector pins or movable pins slide, a certain amount of clearance is provided between the second mold 11 and the ejector pins or movable pins. Therefore, the clearance between the second mold 11 and the gas vents 12a and 12b allows compressed air generated in the resin inflow process and gases originating from the mold resin 7 to be discharged to the outside.

[0048] The second mold 11 has gas vents 12a and 12b in the portion of the second mold 11 surrounding the through hole 9, which allows for efficient discharge to the outside of compressed air and gases caused by the mold resin 7 that tend to occur in the weld lines 13a and 13b of the thin-walled portion 14, which is the final filling position. Because the compressed air and gases caused by the mold resin 7 are efficiently discharged to the outside, it is possible to avoid the mold resin 7 remaining unfilled in the weld lines 13a and 13b of the thin-walled portion 14, which is the final filling position, due to the compressed air and gases caused by the mold resin 7. Since it is possible to avoid the mold resin 7 remaining unfilled, the occurrence of molding defects is suppressed, and a semiconductor device 100 with suppressed deterioration of insulation can be obtained.

[0049] The gate opening 8 into which the molding resin 7 flows into the mold will now be described. In Figures 1 and 2, the location where the gate opening 8 is provided is indicated by a dashed line. The gate opening 8 is located on the outside of the semiconductor device 100. Since Figure 2 is a cross-sectional view, the front side of the paper is where the gate opening 8 is provided. In this embodiment, when viewed in a direction perpendicular to the bonding surface 3a1, the gate opening 8 into which the molding resin 7 flows in is formed in the part of the first mold 10 or the second mold 11 surrounding the heat spreader 3a and the additional heat spreader 3b, or in the part between the first mold 10 and the second mold 11. The position of the gate opening 8 in a direction perpendicular to the bonding surface 3a1 is the position where the thickened portion 15 is formed, as shown in Figure 2, and the position of the gate opening 8 when viewed in a direction perpendicular to the bonding surface 3a1 is the position adjacent to the part between the heat spreader 3a and the additional heat spreader 3b, as shown in Figure 1.

[0050] With this configuration, the gate opening 8 is positioned adjacent to the thick-walled portion 15, thereby improving the fluidity of the mold resin 7 in the thick-walled portion 15, as well as the fluidity of the mold resin 7 in the thin-walled portion 14. Because the fluidity of the mold resin 7 in both the thin-walled portion 14 and the thick-walled portion 15 is improved, it is possible to avoid the mold resin 7 around the lead frame 4a remaining unfilled. Since it is possible to avoid the mold resin 7 remaining unfilled, a semiconductor device 100 with further suppressed deterioration of insulation can be obtained.

[0051] In this embodiment, when viewed in a direction perpendicular to the bonding surface 3a1, the through-hole 9 is positioned to overlap the portion between the heat spreader 3a and the additional heat spreader 3b. This configuration allows for a larger thickness of the thickened portion 15 in the Z direction in the portion where the through-hole 9 is formed. As the thickness of the thickened portion 15 increases and the gate opening 8 is positioned adjacent to the thickened portion 15, the fluidity of the mold resin 7 in the thickened portion 15 is further improved, thereby further improving the fluidity of the mold resin 7 that flows around the end face 4a4 of the lead frame 4a and into the thinned portion 14. Because the fluidity of the mold resin 7 that flows around the end face 4a4 of the lead frame 4a and into the thinned portion 14 is further improved, it is possible to further avoid the mold resin 7 remaining unfilled in the thinned portion 14 where it is difficult to flow. Since it is possible to further avoid the mold resin 7 remaining unfilled, a semiconductor device 100 with further suppression of deterioration in insulation can be obtained.

[0052] As shown in Figure 3, the gas vents 12a and 12b are provided in the second mold 11 such that the ends of the gas vents 12a and 12b coincide with the inner surface of the second mold 11. However, the arrangement of the gas vents 12a and 12b may vary in the Z direction, as shown in Figures 4 and 5. In Figure 4, the gas vents 12a and 12b protrude from the inner surface of the second mold 11 in the direction of the internal space enclosed by the first mold 10 and the second mold 11. In Figure 5, the gas vents 12a and 12b are recessed from the inner surface of the second mold 11 in the direction of the interior of the second mold 11. The distance in the Z direction between the inner surface of the second mold 11 and the ends of the gas vents 12a and 12b is 0.1 mm or less. When the gas vents 12a and 12b protrude, a recess 14a with a depth of 0.1 mm or less is formed in the thin-walled portion 14 that is in contact with the gas vents 12a and 12b. When the gas vents 12a and 12b are recessed, a protrusion 14b with a height of 0.1 mm or less is formed in the thin-walled portion 14 that is in contact with the gas vents 12a and 12b.

[0053] In this embodiment shown in Figure 4, two gas vents 12a and 12b are provided, and since the two gas vents 12a and 12b protrude towards the thin-walled portion 14, two recesses 14a are formed in the thin-walled portion 14. When recesses 14a with a depth of 0.1 mm or less are formed in the portion of the thin-walled portion 14 that is in contact with the gas vents 12a and 12b, no protrusions are formed on the outer portion of the thin-walled portion 14, so the semiconductor device 100 and other externally installed components do not interfere with each other, thereby improving the freedom of installation of the semiconductor device 100.

[0054] In this embodiment shown in Figure 5, two gas vents 12a and 12b are provided, and since the two gas vents 12a and 12b are recessed inward from the inner surface of the second mold 11, two protrusions 14b are formed in the thin-walled portion 14. When protrusions 14b with a height of 0.1 mm or less are formed in the thin-walled portion 14 that is in contact with the gas vents 12a and 12b, the protrusions 14b form a thicker portion of the thin-walled portion 14, which improves the fluidity of the mold resin 7 in that area, and thus improves the gas discharge efficiency by the gas vents 12a and 12b.

[0055] As described above, the semiconductor device 100 according to Embodiment 1 comprises semiconductor elements 1a and 1b, a heat spreader 3a, a lead frame 4a, and a molded resin 7 that encloses the semiconductor elements 1a and 1b, the heat spreader 3a, and the lead frame 4a. The intermediate portion 4a3 of the lead frame 4a, between the connection portion 4a1 and the exposed portion 4a2, extends along the bonding surface 3a1 of the heat spreader 3a, with a gap between it and the bonding surface 3a1. A thin-walled portion 14 of the molded resin 7 is formed between the portion of the intermediate portion 4a3 opposite to the heat spreader 3a and the outside. A thickened portion 15 of the molded resin 7 is formed on the side opposite to the side where the thinned portion 14 is formed. The thickness of the thinned portion 14 in the direction in which the thinned portion 14, the intermediate portion 4a3, and the thickened portion 15 overlap is smaller than the thickness of the thickened portion 15. Since the lead frame 4a has a through hole 9 in the intermediate portion 4a3 that connects the thinned portion 14 and the thickened portion 15, the molded resin 7 that flows through the thickened portion 15 wraps around the end face 4a4 of the lead frame 4a and flows into the thinned portion 14, as well as from the through hole 9 into the thinned portion 14. This prevents the molded resin 7 from remaining unfilled in the thinned portion 14 where it is difficult to flow. Because the molded resin 7 does not remain unfilled, the occurrence of molding defects is suppressed, and a semiconductor device 100 with suppressed deterioration of insulation can be obtained.

[0056] When viewed perpendicular to the bonding surface 3a1, if a weld line 13 is formed in the portion surrounding the through-hole 9 of the thin-walled portion 14, the final filling position of the mold resin 7 in the thin-walled portion 14 can be formed in the portion surrounding the through-hole 9 of the thin-walled portion 14, thus avoiding any unfilled areas of the mold resin 7 in the thin-walled portion 14. Since unfilled areas of the mold resin 7 can be avoided, the occurrence of molding defects can be suppressed, and a semiconductor device 100 with suppressed deterioration of insulation can be obtained.

[0057] If one or more recesses 14a are formed in the thin-walled portion 14, in the portions of the weld lines 13a and 13b and the portions surrounding the weld lines 13a and 13b, no protrusions are formed on the outer portion of the thin-walled portion 14. Therefore, the semiconductor device 100 and other externally installed components will not interfere with each other, thereby improving the freedom of installation of the semiconductor device 100.

[0058] If one or more protrusions 14b are formed in the thin-walled portion 14, both in the weld lines 13a and 13b and in the areas surrounding the weld lines 13a and 13b, the protrusions 14b form a thicker portion of the thin-walled portion 14, thereby improving the fluidity of the mold resin 7 in that area, and thus improving the gas discharge efficiency of the gas vents 12a and 12b.

[0059] When viewed perpendicular to the bonding surface 3a1, if the through-hole 9 is formed overlapping the portion between the heat spreader 3a and the additional heat spreader 3b, the thickness of the thickened portion 15 in the Z direction in the portion where the through-hole 9 is formed increases. This improves the fluidity of the mold resin 7 in the thickened portion 15, thereby improving the fluidity of the mold resin 7 that flows around the end face 4a4 of the lead frame 4a and into the thinned portion 14. Because the fluidity of the mold resin 7 that flows around the end face 4a4 of the lead frame 4a and into the thinned portion 14 is improved, it is possible to further avoid the mold resin 7 remaining unfilled in the thinned portion 14 where it is difficult to flow. Since it is possible to further avoid the mold resin 7 remaining unfilled, a semiconductor device 100 with further suppression of deterioration in insulation can be obtained.

[0060] In the manufacturing method of the semiconductor device 100 according to Embodiment 1, the process includes a component preparation step, a through-hole formation step, a joining step, and a resin inflow step. A thin-walled portion 14 of the mold resin 7 is formed in the portion between the intermediate portion 4a3 and the second mold 11, and a thick-walled portion 15 of the mold resin 7 is formed on the portion of the intermediate portion 4a3 opposite to the side where the thin-walled portion 14 is formed. The thickness of the thin-walled portion 14 in the direction in which the thin-walled portion 14, the intermediate portion 4a3, and the thick-walled portion 15 overlap is smaller than the thickness of the thick-walled portion 15. The through-hole 9 connects the thin-walled portion 14 and the thick-walled portion 15. When viewed in a direction perpendicular to the joining surface 3a1, the second mold 11 has gas vents 12a and 12b in the portion of the second mold 11 around the through-hole 9. Therefore, compressed air that tends to be generated in the weld lines 13a and 13b of the thin-walled portion 14, which is the final filling position, and gases caused by the mold resin 7 can be efficiently discharged to the outside. Since compressed air and gases generated by the mold resin 7 are efficiently discharged to the outside, it is possible to avoid the mold resin 7 remaining unfilled in the weld lines 13a and 13b of the thin-walled section 14, which is the final filling position, due to gases generated by the compressed air and mold resin 7. Because it is possible to avoid the mold resin 7 remaining unfilled, the occurrence of molding defects is suppressed, and a semiconductor device 100 with suppressed deterioration of insulation can be obtained.

[0061] When viewed perpendicular to the bonding surface 3a1, the gate opening 8 into which the mold resin 7 flows is formed in the portion of the first mold 10 or the second mold 11 surrounding the heat spreader 3a and the additional heat spreader 3b, or in the portion between the first mold 10 and the second mold 11, and the position of the gate opening 8 perpendicular to the bonding surface 3a1 is the position where the thick-walled portion 15 is formed, and the position of the gate opening 8 perpendicular to the bonding surface 3a1 is adjacent to the portion between the heat spreader 3a and the additional heat spreader 3b, the gate opening 8 is positioned adjacent to the thick-walled portion 15, thereby improving the fluidity of the mold resin 7 in the thick-walled portion 15, as well as the fluidity of the mold resin 7 in the thin-walled portion 14. Because the fluidity of the mold resin 7 in the thin-walled portion 14 and the thick-walled portion 15 is improved, it is possible to avoid the mold resin 7 around the lead frame 4a remaining unfilled. Because it is possible to avoid the mold resin 7 remaining unfilled, a semiconductor device 100 with further suppression of deterioration in insulation can be obtained.

[0062] When viewed perpendicular to the bonding surface 3a1, if the through-hole 9 is positioned overlapping the portion between the heat spreader 3a and the additional heat spreader 3b, the thickness of the thickened portion 15 in the Z direction in the portion where the through-hole 9 is formed can be increased. As the thickness of the thickened portion 15 increases and the gate opening 8 is positioned adjacent to the thickened portion 15, the fluidity of the mold resin 7 in the thickened portion 15 is further improved, thereby further improving the fluidity of the mold resin 7 that flows around the end face 4a4 of the lead frame 4a and into the thinned portion 14. As the fluidity of the mold resin 7 that flows around the end face 4a4 of the lead frame 4a and into the thinned portion 14 is further improved, it is possible to further avoid the mold resin 7 remaining unfilled in the thinned portion 14 where it is difficult to flow. As it is possible to further avoid the mold resin 7 remaining unfilled, a semiconductor device 100 with further suppression of deterioration in insulation can be obtained.

[0063] If a recess 14a with a depth of 0.1 mm or less is formed in the thin-walled portion 14 that is in contact with the gas vents 12a and 12b, no protrusions are formed on the outer portion of the thin-walled portion 14. As a result, the semiconductor device 100 and other externally installed components do not interfere with each other, thus improving the freedom of installation of the semiconductor device 100. Furthermore, if a protrusion 14b with a height of 0.1 mm or less is formed in the thin-walled portion 14 that is in contact with the gas vents 12a and 12b, the protrusion 14b forms a thicker portion of the thin-walled portion 14. As a result, the fluidity of the mold resin 7 in that area is improved, thus improving the gas discharge efficiency by the gas vents 12a and 12b.

[0064] Furthermore, while this disclosure describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but can be applied individually or in various combinations to the embodiments. Accordingly, countless variations not illustrated are conceivable within the scope of the art disclosed in this specification. These include, for example, modifying, adding or omitting at least one component, or even extracting at least one component and combining it with components of other embodiments. [Explanation of symbols]

[0065] 1a, 1b, 1c, 1d Semiconductor element, 2a, 2b, 2c Bonding member, 3a Heat spreader, 3a1 Bonding surface, 3b Additional heat spreader, 3b1 Bonding surface, 4a Lead frame, 4a1 Connection part, 4a2 Exposed part, 4a3 Intermediate part, 4a4 End face, 4b, 4c, 4d Lead frame, 5 Insulating sheet, 6 Metal plate, 7 Molding resin, 8 Gate opening, 9 Through hole, 10 First mold, 11 Second mold, 12a, 12b Gas vent, 13, 13a, 13b Weld line, 14 Thin-walled part, 14a Recess, 14b Protruding part, 15 Thick-walled part, 100 Semiconductor device, 101 Semiconductor device

Claims

1. One or more semiconductor elements, The other side of the semiconductor element is connected to a heat spreader on one side via a bonding member, One side of the semiconductor element is connected to a lead frame on one end side via a bonding member, With the other end of the lead frame, opposite to the connecting portion which is one end, exposed, the semiconductor element, the heat spreader, and the molded resin that seals the lead frame are provided. The intermediate portion of the lead frame between the connecting portion and the exposed portion which is the other end is spaced apart from the joining surface which is one of the heat spreaders, and extends along the joining surface. A thin-walled portion of the mold resin is formed between the portion of the intermediate section opposite to the heat spreader side and the outside, and a thick-walled portion of the mold resin is formed on the portion of the intermediate section opposite to the side where the thin-walled portion is formed. In the direction in which the thin-walled portion, the intermediate portion, and the thick-walled portion overlap, the thickness of the thin-walled portion is smaller than the thickness of the thick-walled portion. The lead frame has a through hole in its intermediate portion that connects the thin-walled portion and the thick-walled portion, forming a semiconductor device.

2. The semiconductor device according to claim 1, wherein a weld line is formed in the portion surrounding the through hole of the thin-walled portion when viewed in a direction perpendicular to the bonding surface.

3. The semiconductor device according to claim 2, wherein one or more recesses are formed in the thin-walled portion, in the portion of the weld line and the portion surrounding the portion of the weld line.

4. The semiconductor device according to claim 2, wherein one or more protrusions protruding outward are formed in the thin-walled portion, in the portion of the weld line and the portion surrounding the portion of the weld line.

5. With an additional heat spreader, The heat spreader and the additional heat spreader are arranged on the same plane with a gap between them. The semiconductor device according to any one of claims 1 to 4, as viewed in a direction perpendicular to the bonding surface, wherein the through-hole is formed to overlap the portion between the heat spreader and the additional heat spreader.

6. A component preparation step involves preparing one or more semiconductor elements, lead frames, and heat spreaders. A through-hole forming step is to form a through-hole in the intermediate portion sandwiched between one end and the other end of the lead frame, A bonding step comprising connecting the other side of the semiconductor element to one side of the heat spreader via a bonding member, and connecting one side of the semiconductor element to one end of the lead frame via a bonding member, The second mold is placed over the first mold with the other side of the heat spreader positioned at the bottom of the inside of the first mold, the intermediate portion extending along the joining surface with a gap between it and the joining surface which is one side of the heat spreader, and the other end of the lead frame protruding from the inside of the first mold toward the outside of the first mold, and a resin inflow process is performed to inflow mold resin around the semiconductor element, the heat spreader, and the lead frame inside the first mold and the second mold. A thin-walled portion of the mold resin is formed in the area between the intermediate portion and the second mold, and a thick-walled portion of the mold resin is formed in the area of ​​the intermediate portion opposite to the side where the thin-walled portion is formed. In the direction in which the thin-walled portion, the intermediate portion, and the thick-walled portion overlap, the thickness of the thin-walled portion is smaller than the thickness of the thick-walled portion, and the through hole connects the thin-walled portion and the thick-walled portion. A method for manufacturing a semiconductor device, wherein, viewed in a direction perpendicular to the bonding surface, the second mold has one or more gas vents in the portion of the second mold surrounding the through hole.

7. In the aforementioned component preparation step, additional heat spreaders are further prepared. In the bonding process, the other side of the semiconductor element is connected to one side of the additional heat spreader via a bonding member. In the resin inflow process, the other side of the additional heat spreader is placed at the bottom inside the first mold, and the heat spreader and the additional heat spreader are arranged on the same plane with a gap between them. Viewed in a direction perpendicular to the joining surface, the gate opening for the flow of the mold resin is formed in the portion of the first mold or the second mold surrounding the heat spreader and the additional heat spreader, or in the portion between the first mold and the second mold. The position of the gate opening in the direction perpendicular to the joint surface is the position where the thickened portion is formed. The method for manufacturing a semiconductor device according to claim 6, wherein the position of the gate opening, as viewed in a direction perpendicular to the bonding surface, is adjacent to the portion between the heat spreader and the additional heat spreader.

8. The method for manufacturing a semiconductor device according to claim 7, wherein, when viewed in a direction perpendicular to the bonding surface, the through-hole is arranged to overlap the portion between the heat spreader and the additional heat spreader.

9. The gas vent protrudes from the inner surface of the second mold in the direction of the internal space enclosed by the first mold and the second mold, or is recessed from the inner surface of the second mold in the direction of the interior of the second mold. If the gas vent protrudes, a recess with a depth of 0.1 mm or less is formed in the thin-walled portion in contact with the gas vent. A method for manufacturing a semiconductor device according to any one of claims 6 to 8, wherein, when the gas vent is retracted, a protrusion with a height of 0.1 mm or less is formed on the thin-walled portion in contact with the gas vent.

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