Semiconductor device and method for manufacturing semiconductor device

Abstract

A semiconductor device and a manufacturing method of a semiconductor device are provided, which maintain a solder thickness capable of maintaining a certain heat dissipation. A metal base plate (30) having a disposition region provided separately from a center line (CL) on a front surface and a ceramic circuit substrate (21) disposed in the disposition region by a solder (25a, 25b) are provided. At this time, the thickness of an end portion of the solder (25a, 25b) away from the center line (CL) is thicker than that of an end portion close to the center line (CL). In a region outside the solder (25a, 25b), the generation of shrinkage holes is suppressed. By such a manufacturing method, the increase in the amount of the solder (25a, 25b) is suppressed, and the increase in the thermal resistance of the solder (25a, 25b) is also suppressed, and the reduction in the heat dissipation of the semiconductor device (10) can be prevented.

Description

Technical Field

[0001] This invention relates to a semiconductor device and a method for manufacturing a semiconductor device. Background Technology

[0002] A semiconductor device includes multiple substrates, semiconductor elements disposed on the multiple substrates, and a metal substrate frontally bonded to the multiple substrates. The substrates include a ceramic substrate, a metal plate disposed on the back side of the ceramic substrate, and a circuit pattern disposed on the front side of the ceramic substrate. The semiconductor elements are disposed on the circuit pattern of such substrates. The semiconductor elements are power devices. Power devices include, for example, IGBTs (Insulated Gate Bipolar Transistors) and power MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). The multiple substrates, each disposed of such semiconductor elements, are bonded to the metal substrate by solder. In the semiconductor device, heat from the heating semiconductor elements is conducted from the substrates to the metal substrate for heat dissipation. To improve the heat dissipation of the semiconductor device, it is desirable to reduce the thickness of the solder between the substrates and the metal substrate.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2015-170826 Summary of the Invention

[0006] Technical issues

[0007] However, in semiconductor devices, if the solder is made too thin, cavities (shrinkage holes) will form inside the solder. If shrinkage holes form in the solder, its thermal conductivity will decrease. As a result, the heat dissipation of the semiconductor device will decrease, leading to a degraded performance. On the other hand, if the solder is thickened to prevent shrinkage holes, heat dissipation cannot be improved.

[0008] The present invention was made in view of the following circumstances, and its object is to provide a semiconductor device and a method for manufacturing a semiconductor device that can maintain a certain solder thickness that can maintain a certain heat dissipation.

[0009] Technical solution

[0010] According to one aspect of the present invention, a semiconductor device is provided, comprising: a metal substrate having a configuration area disposed on its front side and a central portion above ground; and a substrate disposed on the configuration area by solder, wherein the thickness of the solder at the end furthest from the central portion is greater than the thickness of the end closer to the central portion.

[0011] In addition, according to one aspect of the present invention, a semiconductor device is provided, comprising: a metal substrate having a configuration area disposed on the front side and a central portion above ground; and a substrate disposed on the configuration area by solder, wherein the fillet weld of the solder at the end away from the central portion is larger than the fillet weld at the end closer to the central portion.

[0012] In addition, according to one aspect of the present invention, a method for manufacturing the above-described semiconductor device is provided.

[0013] Technical effect

[0014] According to the publicly available technology, it is possible to maintain a solder thickness that allows for adequate heat dissipation to ensure stable operation. Attached Figure Description

[0015] Figure 1 This is a top view of the semiconductor device according to the first embodiment.

[0016] Figure 2 This is a cross-sectional view of the semiconductor device according to the first embodiment.

[0017] Figure 3 This is a flowchart of a method for manufacturing a first semiconductor device.

[0018] Figure 4 This is a diagram illustrating the setup of a solder joint apparatus for explaining a method of manufacturing a first semiconductor device.

[0019] Figure 5 This is a diagram illustrating the heating process using a solder bonding device to explain the manufacturing method of a first semiconductor device.

[0020] Figure 6 This is a diagram illustrating a method for manufacturing a first semiconductor device, showing cooling using a solder joint device.

[0021] Figure 7 This is a cross-sectional view of the semiconductor device according to the second embodiment.

[0022] Figure 8 This is a flowchart of a method for manufacturing a second semiconductor device.

[0023] Figure 9 This is a diagram illustrating the setup of a solder joint apparatus for explaining a method of manufacturing a second semiconductor device.

[0024] Figure 10 This is a top view of the semiconductor device according to the third embodiment.

[0025] Figure 11 This is a cross-sectional view of the semiconductor device according to the third embodiment.

[0026] Figure 12 This is a top view of the semiconductor device according to the fourth embodiment.

[0027] Figure 13 This is a cross-sectional view of the semiconductor device according to the fourth embodiment.

[0028] Symbol Explanation

[0029] 10, 10a, 10b, 10c semiconductor devices

[0030] Semiconductor units 20, 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j, 20k, 20l

[0031] 21 Ceramic Circuit Board

[0032] 22 Insulation Board

[0033] 23 Metal Plates

[0034] Circuit diagrams 24a, 24b, 24c, and 24d

[0035] 25a, 25b, 25c, 25g, 25l solder

[0036] Gap between 26a, 26b, 26g, and 26l

[0037] 27a, 27b solder boards

[0038] 27a1, 27b1 molten solder

[0039] 28a and 28b semiconductor chips

[0040] 30 Metal base plate

[0041] 31 Heat sink

[0042] 32a~35a, 32b~35b, 32c~35c, 32d~35d, 32e~35e, 32f~35f, 32g, 33g, 32l, 33l protrusions

[0043] Configuration areas for 36a, 36b, 36c, 36d, 36e, 36f, 36g, 36h, 36i, 36j, 36k, and 36l

[0044] 41a, 41b Compression hammers

[0045] 50 Solder bonding device Detailed Implementation

[0046] The embodiments will now be described with reference to the accompanying drawings. It should be noted that in the following description, "front" and "top surface" are used interchangeably. Figure 2 In the semiconductor device 10, the surface facing upwards is indicated. Similarly, "upper" is used in... Figure 2 In semiconductor device 10, the upper side is indicated. "Back side" and "lower surface" are... Figure 2 In the semiconductor device 10, the downward-facing surface is indicated. Similarly, "down" is used in... Figure 2 The direction shown in the semiconductor device 10 is the lower side. The same directionality may be shown in other figures as needed. The terms "front," "upper surface," "upper," "back side," "lower surface," "lower," and "side" are used only for ease of defining relative positional relationships and do not limit the technical concept of the invention. For example, "upper" and "lower" do not necessarily indicate the direction of gravity relative to the ground. That is, the directions of "upper" and "lower" are not limited to the direction of gravity.

[0047] [First Implementation Method]

[0048] use Figure 1 and Figure 2 The semiconductor device of the first embodiment will be described. Figure 1 This is a top view of the semiconductor device according to the first embodiment. Figure 2 This is a cross-sectional view of the semiconductor device according to the first embodiment. It should be noted that, in Figure 1 In the diagram, dashed lines indicate the formation positions of protrusions 32a-35a and protrusions 32b-35b. Figure 2 express Figure 1 A cross-sectional view at the point marked by a single-dotted line XX.

[0049] The semiconductor device 10 includes two semiconductor units 20a and 20b and a metal substrate 30 on which the semiconductor units 20a and 20b are disposed via solder 25a and 25b. It should be noted that, in the following description, without specifically distinguishing between semiconductor units 20a and 20b, semiconductor unit 20 will be referred to as semiconductor unit 20.

[0050] The semiconductor unit 20 includes a ceramic circuit board 21 and semiconductor chips 28a and 28b disposed on the ceramic circuit board 21 by solder. The ceramic circuit board 21 is rectangular when viewed from above. The ceramic circuit board 21 includes an insulating plate 22, a metal plate 23 disposed on the back side of the insulating plate 22, and circuit patterns 24a to 24d disposed on the front side of the insulating plate 22. The insulating plate 22 and the metal plate 23 are rectangular when viewed from above. Furthermore, the corners of the insulating plate 22 and the metal plate 23 can be chamfered into an R-shape or a C-shape. The size of the metal plate 23 is smaller than the size of the insulating plate 22 when viewed from above and is formed inside the insulating plate 22. The insulating plate 22 is made of a ceramic with good thermal conductivity. Such ceramics are, for example, alumina, aluminum nitride, or silicon nitride. The metal plate 23 is made of a metal with excellent thermal conductivity. Such metals are, for example, aluminum, iron, silver, copper, or alloys containing at least one of these metals. Furthermore, the thickness of the metal plate 23 is 0.1 mm or more and 2.0 mm or less. To improve corrosion resistance, the surface of the metal plate 23 can be plated. The plating material used is, for example, nickel, a nickel-phosphorus alloy, or a nickel-boron alloy. The circuit patterns 24a to 24d are made of a metal with excellent conductivity. Such metals are, for example, silver, copper, nickel, or alloys containing at least one of these metals. Furthermore, the thickness of the circuit patterns 24a to 24d is 0.5 mm or more and 1.5 mm or less. To improve corrosion resistance, the surface of the circuit patterns 24a to 24d can be plated. The plating material used is, for example, nickel, a nickel-phosphorus alloy, or a nickel-boron alloy. Such circuit patterns 24a to 24d are obtained by forming a metal layer on the front side of the insulating plate 22 and etching the metal layer. Alternatively, the circuit patterns 24a to 24d, pre-cut from the metal layer, can be pressed onto the front side of the insulating plate 22. It should be noted that... Figure 1 The circuit patterns 24a to 24d shown are examples. The number, shape, size, etc. of the circuit patterns can be appropriately selected as needed. For the ceramic circuit board 21 composed of such components, for example, a DCB (Direct Copper Bonding) substrate or an AMB (Active Metal Brazed) substrate can be used.

[0051] Semiconductor chip 28a includes switching elements. These switching elements may be, for example, IGBTs or power MOSFETs. When semiconductor chip 28a is an IGBT, it has a collector as the main electrode on its back side and a gate electrode and an emitter electrode as the main electrode on its front side. When semiconductor chip 28a is a power MOSFET, it has a drain electrode as the main electrode on its back side and a gate electrode and a source electrode as the main electrode on its front side. The back side of the semiconductor chip 28a is bonded to circuit patterns 24b and 24c by solder (not shown). Wiring components are appropriately electrically and mechanically connected to the main electrode and gate electrode on the front side of the semiconductor chip 28a. These wiring components may be, for example, bonding wires, lead frames, pin-shaped or strip-shaped components.

[0052] Additionally, semiconductor chip 28b includes a diode. The diode may be, for example, an SBD (Schottky Barrier Diode), a PiN (P-intrinsic-N) diode, or a FWD (Free Wheeling Diode). This semiconductor chip 28b has an output electrode (cathode) as the main electrode on its back side and an input electrode (anode) as the main electrode on its front side. The back side of the semiconductor chip 28b is bonded to circuit patterns 24b and 24c by solder (not shown). Wiring components are also appropriately electrically and mechanically connected to the main electrode on the front side of the semiconductor chip 28b. Wiring components may be, for example, bonding wires, lead frames, pin-shaped or strip-shaped components. It should be noted that RC (Reverse-Conducting)-IGBTs, which combine the functions of IGBTs and FWD, may also be used instead of semiconductor chips 28a and 28b. Furthermore, Figure 1 The diagram only shows the case where two sets of semiconductor chips 28a and 28b are provided. It is not limited to two sets; the number of sets can be set according to the specifications of the semiconductor device 10. Additionally, if necessary, electronic components can be arranged in circuit patterns 24b and 24c according to the specifications of the semiconductor device 10. The required number of electronic components are soldered to the circuit patterns 24b and 24c respectively. Appropriate selection of electronic components enables the semiconductor device 10 to achieve the desired function. Such electronic components include, for example, control ICs (Integrated Circuits), thermistors, capacitors, and resistors.

[0053] The solder used to bond semiconductor chips 28a, 28b to circuit patterns 24b, 24c is lead-free solder. The lead-free solder has at least one alloy as its main component, for example, an alloy comprising tin-silver-copper, an alloy comprising tin-zinc-bismuth, an alloy comprising tin-copper, or an alloy comprising tin-silver-indium-bismuth. Furthermore, the solder may contain additives. Additives may include, for example, nickel, germanium, cobalt, or silicon. By containing additives, the solder can improve wettability, gloss, and bond strength, thereby enhancing reliability.

[0054] The metal substrate 30 is made of a metal with excellent thermal conductivity. Such metals include, for example, aluminum, iron, silver, copper, or alloys containing at least one of these metals. Furthermore, to improve corrosion resistance, the surface of the metal substrate 30 can be plated. The plating material used in this case is, for example, nickel, a nickel-phosphorus alloy, or a nickel-boron alloy. Additionally, the coefficient of thermal expansion of the metal substrate 30 is greater than that of the ceramic circuit board 21. The metal substrate 30 can be rectangular when viewed from above. Furthermore, the corners of the metal substrate 30 can be chamfered into R-shapes or C-shapes. This metal substrate 30 includes a heat sink 31 and protrusions 32a-35a and 32b-35b formed on the front side of the heat sink 31. The heat sink 31 is a flat portion of the metal substrate 30. Figure 2 As shown, the heat sink 31 is warped downwards into a convex shape. That is, the heat sink 31 is warped such that the short and long sides of the heat sink 31 are above the center, so that the center is below. This is caused by heating during the manufacturing process of the semiconductor device 10, as described later. The overall average thickness of the heat sink 31 is more than 1 mm and less than 10 mm. In addition, on the heat sink 31, there are symmetrically arranged arrangement areas 36a and 36b with the center as the center. As described later, semiconductor units 20a and 20b are arranged in arrangement areas 36a and 36b. The metal substrate 30 (heat sink 31) is warped so that the center convexes downwards. Therefore, the arrangement areas 36a and 36b are not set at the center of the heat sink 31, but are set symmetrically across the centerline CL of the heat sink 31. Specifically, in Figure 1 In this case, the configuration areas 36a and 36b are respectively positioned on the left and right sides, separated by a centerline CL that passes through the center of the heat sink 31 and is parallel to the short side direction. It should be noted that the heat sink 31 has mounting holes formed at the corners, etc., as needed. The metal base plate 30 is mounted in a predetermined position by fixing it with screws through the mounting holes, and the cooler, described later, is also installed.

[0055] Furthermore, in the metal substrate 30, protrusions 32a-35a and 32b-35b are integrally formed at the corners of the placement areas 36a and 36b of the heat sink 31, respectively. The placement areas 36a and 36b of the heat sink 31 can be located opposite to the semiconductor units 20a and 20b. That is, the placement areas 36a and 36b of the heat sink 31 can be located opposite to the back surface of the metal plate 23 of the ceramic circuit board 21. Therefore, protrusions 32a-35a and 32b-35b can be located opposite to the corners of the semiconductor units 20a and 20b. Further, protrusions 32a-35a and 32b-35b can be located opposite to the corners of the back surface of the metal plate 23 of the ceramic circuit board 21. It should be noted that in the first embodiment, the protrusions 32a-35a and 32b-35b have the same height. The height is, for example, 0.05 mm or more and 0.5 mm or less. Furthermore, the diameter of the protrusions 32a-35a and 32b-35b is, for example, 50 μm or more and 500 μm or less. Additionally, the protrusions 32a-35a and 32b-35b are not limited to... Figure 2 The protrusions 32a-35a and 32b-35b can also be, for example, hemispherical, semi-ellipsoidal, or cubic. Alternatively, they can be convex shapes formed by connecting protrusions 32a and 34a along the edge of the ceramic circuit board 21. Similarly, protrusions 33b, 35b, 33a, 35a, 32b, and 34b can also be convex shapes formed by connecting them along the edge of the ceramic circuit board 21.

[0056] It should be noted that the cooler (not shown) can be mounted to the back of such a metal base plate 30 using solder or silver solder. In this case, the mounting holes of the metal base plate 30 and the cooler are fixed with screws. This improves the heat dissipation of the metal base plate 30. The cooler in this case is, for example, made of a metal with excellent thermal conductivity. Such metals are, for example, aluminum, iron, silver, copper, or alloys containing at least one of these metals. Alternatively, a heat sink or a heat sink composed of multiple heat sinks, or a water-cooled cooling device can be used as the cooler. Furthermore, the metal base plate 30 can be integrated with such a cooler. In this case, the metal base plate 30 is also made of a metal with excellent thermal conductivity. Such metals are, for example, aluminum, iron, silver, copper, or alloys containing at least one of these metals. In addition, to improve corrosion resistance, the surface of the cooler integrated with the metal base plate 30 can be plated. The plating material used in this case is, for example, nickel, nickel-phosphorus alloy, or nickel-boron alloy.

[0057] Semiconductor units 20a and 20b are disposed on the configuration areas 36a and 36b of the metal substrate 30 via solder 25a and 25b. At this time, as... Figure 2As shown, solder 25a and 25b are formed between the front side of the metal substrate 30 and the back side of the metal plate 23 of the ceramic circuit board 21. This allows the front side of the metal substrate 30 to be bonded to the back side of the metal plate 23 of the ceramic circuit board 21. Furthermore, fillets are formed in the solder 25a and 25b, extending smoothly outward from the ends of the metal plates 23.

[0058] In addition, such as Figure 2 As shown, the thickness of the ends of solder 25a and 25b furthest from the center line CL (center portion) of the metal substrate 30 is greater than the thickness of the ends of solder 25a and 25b closest to the center line CL. Preferably, the thickness of the ends of solder 25a and 25b furthest from the center line CL (center portion) is 10% to 400% greater than the thickness of the ends of solder 25a and 25b closest to the center line CL. For example, the thickness of the ends of solder 25a and 25b furthest from the center line CL (center portion) is 0.40 mm, and the thickness of the ends of solder 25a and 25b closest to the center line CL is 0.25 mm. Here, the thickness of the ends of solder 25a and 25b can be the thickness of the solder 25a and 25b formed between the back side of the end of the metal plate 23 formed on the ceramic circuit board 21 and the front side of the heat sink 31 of the metal substrate 30, excluding the protrusions 32a-35a and 32b-35b. It should be noted that the solder 25a and 25b can become thicker as they move away from the center line CL of the metal substrate 30. Alternatively, the solder 25a and 25b can have a thinner portion from the end near the center line CL to the end away from the center line CL, corresponding to the warping of the metal substrate 30, than the end away from the center line CL.

[0059] Furthermore, the front ends of the protrusions 32a, 34a and 33b, 35b located on the side near the center line CL of the metal substrate 30 abut against the back surface of the semiconductor cells 20a, 20b. On the other hand, the protrusions 33a, 35a and 32b, 34b located away from the center line CL are separated from the back surface of the semiconductor cells 20a, 20b by gaps 26a, 26b at all locations, including their front ends. It should be noted that in Figure 2Only the sides of protrusions 32a, 33a, 32b, 33b are shown. The same applies to the sides of protrusions 34a, 35a, 34b, 35b. That is, the semiconductor cells 20a and 20b are joined at an angle by solder 25a and 25b, with the ends near the center line CL of the metal substrate 30 lower than the ends far from the center line CL. Therefore, the thickness of the solder 25a and 25b at the ends far from the center line CL (center portion) of the metal substrate 30 is greater than the thickness at the ends near the center line CL. Furthermore, the amount of solder 25a and 25b overflowing from the ends of the metal plate 23 on the front side of the metal substrate 30 is greater at the ends far from the center line CL (center portion) than at the ends near the center line CL. Therefore, the fillet welds at the ends of solders 25a and 25b that are away from the center line CL of the metal substrate 30 are larger than the fillet welds at the ends of solders 25a and 25b that are close to the center line CL.

[0060] It should be noted that, in the first embodiment, although not illustrated, the semiconductor device 10 can be encapsulated with an encapsulating resin. In this case, the encapsulation component includes thermosetting resins such as epoxy resin, phenolic resin, and maleimide resin, and fillers contained within the thermosetting resin. As an example of an encapsulation component, there is epoxy resin containing a filler. The filler may be an inorganic filler. Examples of inorganic fillers include silicon oxide, aluminum oxide, boron nitride, or aluminum nitride.

[0061] Next, use Figures 3-6 The manufacturing method of such a semiconductor device 10 will be described. Figure 3 This is a flowchart of a method for manufacturing a first semiconductor device. Figure 4 This is a diagram illustrating the arrangement of the solder bonding apparatus in a method for manufacturing a first semiconductor device. Figure 5 This is a diagram illustrating the heating process using a solder bonding device to explain the manufacturing method of a first semiconductor device. Figure 6 This diagram illustrates a method for manufacturing a first semiconductor device, showing cooling using a solder joint apparatus. It should be noted that... Figures 4-6 Is with Figure 1 A sectional view of the location corresponding to the single-dotted line XX.

[0062] First, prepare the semiconductor chip 28a, 28b, ceramic circuit board 21, metal substrate 30, solder plate and other components of the semiconductor device 10 (step S1). It should be noted that the metal substrate 30 has protrusions 32a to 35a and protrusions 32b to 35b formed in the designated placement areas 36a and 36b respectively.

[0063] Next, the metal substrate 30 is placed in a predetermined area of ​​the solder bonding device 50. It should be noted that the metal substrate 30 may be slightly warped into a convex shape with its center facing upwards. That is, the metal substrate 30 may be warped such that its center protrudes upwards relative to both the short and long sides. Solder plates 27a and 27b are respectively positioned to be supported by protrusions 32a-35a and 32b-35b formed in the placement areas 36a and 36b of the metal substrate 30. The solder plates 27a and 27b are plate-shaped and composed of the same material as the solder 25a and 25b described above. Furthermore, the dimensions of the solder plates 27a and 27b are such that, when viewed from above, their corners are supported by the protrusions 32a-35a and 32b-35b, respectively. Furthermore, the thickness of solder plates 27a and 27b is set to be approximately the same as or a few percent higher than the heights of protrusions 32a-35a and 32b-35b. A ceramic circuit board 21 is placed on these solder plates 27a and 27b, and semiconductor chips 28a and 28b are placed on circuit patterns 24b and 24c of the ceramic circuit board 21 via solder plates (not shown) (step S2). It should be noted that these solder plates are also the same type as solder plates 27a and 27b. In step S2, a jig capable of aligning with the placement areas 36a and 36b of the metal substrate 30 is used. This jig is flat, with dimensions the same as the metal plate 30 when viewed from above, and has an opening wider than the dimensions of the placement areas 36a and 36b in the area corresponding to them. Furthermore, the fixture is made of a material with excellent heat resistance. Such materials include, for example, composite ceramic materials and carbon. Solder plates 27a and 27b, ceramic circuit board 21, solder plates, and semiconductor chips 28a and 28b are disposed at the opening of the fixture that has been disposed on the metal substrate 30.

[0064] Next, as Figure 4 As shown, pressure hammers 41a and 41b are respectively disposed on the centerline CL side of the metal substrate 30 of the ceramic circuit board 21 (step S3). Pressure hammers 41a and 41b are rectangular, for example, when viewed from above. Such pressure hammers 41a and 41b are disposed along opposite edges of the ceramic circuit board 21 at its outer edge. Preferably, pressure hammers 41a and 41b are located above protrusions 32a and 34a and protrusions 33b and 35b, for example, when viewed from the side. It should be noted that such pressure hammers 41a and 41b are also made of a material with excellent heat resistance. Such materials are, for example, composite ceramic materials or carbon.

[0065] Next, the soldering device 50 is driven to heat the solder plates 27a and 27b via the metal substrate 30 (step S4). Heat generated from the soldering device 50 is conducted to the back surface of the metal substrate 30. When heated, the metal substrate 30 warps downwards from its center. That is, the metal substrate 30 warps with its short and long sides positioned above its center. Therefore, the heat is generated from the center of the back surface of the metal substrate 30 via the soldering device 50. The heat travels along... Figure 5 The dashed arrows are conducted from the center of the back side of the metal substrate 30 (center line CL) to the outer edge of the metal substrate 30 (heat sink 31). Heat is conducted through the heat sink 31 to the protrusions 32a-35a and 32b-35b. Then, the solder plates 27a and 27b supported by the protrusions 32a-35a and 32b-35b are heated and melted. The molten solder 27a1 and 27b1 obtained from the melting of the solder plates 27a and 27b are pressed by the ceramic circuit board 21 toward the placement areas 36a and 36b. At this time, the ceramic circuit board 21 is in a state where the end of the ceramic circuit board 21 away from the center line CL is lifted relative to the side pressed by the hammers 41a and 41b toward the placement areas 36a and 36b. In this state, the thickness of the ends of the molten solder 27a1 and 27b1 obtained by the complete melting of solder plates 27a and 27b, away from the center line CL of the metal substrate 30, is as follows: Figure 6 The thickness shown is greater than that at the end near the center line CL. It should be noted that protrusions 32a-35a and protrusions 32b-35b are rod-shaped. Therefore, the molten solder 27a1 and 27b1 obtained from the melting of solder plates 27a and 27b easily descends along the protrusions 32a-35a and 32b-35b towards the arrangement areas 36a and 36b. Furthermore, the protrusions 32a-35a and 32b-35b are rod-shaped and located at the corners of the arrangement areas 36a and 36b. Therefore, it is less likely to hinder the extension of the molten solder 27a1 and 27b1 towards the arrangement areas 36a and 36b. Additionally, the protrusions 32a, 34a and 33b, 35b located on the side near the center line CL of the metal substrate 30 abut against the back surface of the semiconductor cells 20a and 20b at least at their front ends. On the other hand, the protrusions 33a, 35a and 32b, 34b, which are far from the center line CL, are separated from the back surfaces of the semiconductor units 20a, 20b by gaps 26a, 26b at all locations, including their front ends. Furthermore, in order to press the ceramic circuit board 21 with a hammer to make the molten solder 27a1, 27b1... Figure 6The shape shown allows for the application of a resist component parallel to the center line CL on the outer side of, for example, the side of the configuration areas 36a and 36b furthest from the center line CL. This resist component prevents molten solder 27a1 and 27b1 from flowing outwards from the center line CL. Consequently, the thickness of the molten solder 27a1 and 27b1 at the ends furthest from the center line CL of the metal substrate 30 is indeed greater than the thickness at the ends closer to the center line CL.

[0066] Next, the operation of the solder joint device 50 is stopped, and the molten solder 27a1 and 27b1 are cooled (step S5). If the heating of the solder joint device 50 is stopped, the metal substrate 30 (heat sink 31) moves along... Figure 6 The dashed arrows shown indicate that cooling occurs from the center (centerline CL) towards the outer edge of the metal substrate 30 (heat sink 31). The molten solder 27a1 and 27b1 are also cooled from the centerline CL side outwards. In the molten solder 27a1 and 27b1 being cooled in this way, the outermost region, which is the last to be cooled, solidifies and shrinks in volume. At this time, if the outer region of the molten solder 27a1 and 27b1 needs to compensate for the volume shrinkage, the volume around it further solidifies. If the volume used for compensation is insufficient, a cavity will form and a shrinkage cavity will occur. However, in the first embodiment, as... Figure 6 As shown, the thickness of the ends of the molten solder 27a1 and 27b1 furthest from the center line CL of the metal substrate 30 is greater than the thickness of the ends closer to the center line CL. Therefore, the outer regions of the molten solder 27a1 and 27b1 can compensate for the volume of the shrinkage portion as the solder contracts, thus suppressing the formation of shrinkage cavities. In this way, the molten solder 27a1 and 27b1 are cooled and solidified to become solder 25a and 25b. Thus, semiconductor units 20a and 20b are bonded to the metal substrate 30 via solder 25a and 25b to manufacture a semiconductor device 10. Such a semiconductor device 10 is removed from the solder bonding device 50, thereby obtaining... Figure 2 The semiconductor device 10 shown. It should be noted that, in Figure 3 In the flowchart, hammers 41a and 41b are used to tilt the ceramic circuit board 21. However, it is not limited to this case; components or fixtures that can press the center line CL side of the ceramic circuit board 21 when the solder plates 27a and 27b are molten can also be used.

[0067] Thus, in the semiconductor device 10, a ceramic circuit board 21 is disposed on the metal substrate 30 in the placement areas 36a and 36b via solder plates 27a and 27b. While pressing the front side of the ceramic circuit board 21 towards the metal substrate 30 from the side closest to the center line CL, the solder plates 27a and 27b are melted, thereby bonding the ceramic circuit board 21 to the bonding areas 36a and 36b. By melting the solder plates 27a and 27b while pressing the front side of the ceramic circuit board 21 towards the metal substrate 30 from the side closest to the center line CL, the thickness of the ends of the molten solder 27a1 and 27b1 away from the center line CL is greater than the thickness of the ends closest to the center line CL. Therefore, the outer region of the molten solder 27a1 and 27b1 can compensate for the volume of the shrinkage portion as it shrinks, suppressing the formation of shrinkage cavities.

[0068] The semiconductor device 10 manufactured in this way has a metal substrate 30 and a ceramic circuit board 21. The metal substrate 30 has arrangement regions 36a and 36b separated from the center line CL on its front side. The ceramic circuit board 21 is disposed on the arrangement regions 36a and 36b by solder 25a and 25b. In this case, the thickness of the ends of the solder 25a and 25b furthest from the center line CL is greater than the thickness of the ends closest to the center line CL. In the region outside the solder 25a and 25b, the formation of shrinkage cavities is suppressed. Through this manufacturing method, the increase in the amount of solder 25a and 25b can be suppressed, as well as the increase in the thermal resistance of the solder 25a and 25b, and the reduction in the heat dissipation of the semiconductor device 10 can be prevented. Therefore, the decrease in the reliability of the semiconductor device 10 is suppressed, thereby ensuring stable operation of the semiconductor device 10.

[0069] [Second Implementation]

[0070] use Figure 7 The semiconductor device 10a of the second embodiment will be described. Figure 7 This is a cross-sectional view of the semiconductor device according to the second embodiment. It should be noted that... Figure 7 Is with Figure 1 A cross-sectional view of the part corresponding to the single-dotted line XX. Additionally, the semiconductor device 10a, when viewed from above, is... Figure 1 Same. In addition, semiconductor device 10a uses the same symbols to refer to the same components as semiconductor device 10 in the first embodiment, in order to simplify or omit detailed descriptions.

[0071] Regarding the protrusions 32a-35a and 32b-35b of the arrangement regions 36a and 36b formed on the metal substrate 30 of the semiconductor device 10a, the protrusions 33a, 35a, 32b, and 34b located outside the centerline CL are formed to be taller than the protrusions 32a, 34a, 33b, and 35b located on the centerline CL side. The height of the protrusions 33a, 35a, 32b, and 34b is 50% to 400% higher than the height of the protrusions 32a, 34a, 33b, and 35b. For example, the height of the protrusions 33a, 35a, 32b, and 34b is 0.35 mm, and the height of the protrusions 32a, 34a, 33b, and 35b is 0.10 mm. The protrusions 32a-35a and 32b-35b, located on the side closer to the center line CL of the metal substrate 30 and on the side farther from the center line CL of the metal substrate 30, respectively abut against the back surfaces of the semiconductor cells 20a and 20b at their front ends. It should be noted that in Figure 7 Only the sides of protrusions 32a, 33a, 32b, 33b are shown. The same applies to the sides of protrusions 34a, 35a, 34b, 35b. The thickness of the ends of solder 25a, 25b away from the center line CL (center portion) of the metal substrate 30 is greater than the thickness of the ends of solder 25a, 25b near the center line CL. Here, the thickness of the ends of solder 25a, 25b can be the thickness of solder 25a, 25b formed between the back side of the end of the metal plate 23 formed on the ceramic circuit board 21 and the front side of the heat sink 31 of the metal substrate 30 excluding the protrusions 32a-35a, 32b-35b. That is, the semiconductor units 20a, 20b are bonded by solder 25a, 25b in a state where the ends near the center line CL of the metal substrate 30 are lower than the ends away from the center line CL. Furthermore, the amount of solder 25a and 25b overflowing from the ends of the metal plate 23 on the front side of the metal substrate 30 is as follows: the overflow amount at the end farther from the center line CL (center portion) is greater than the overflow amount at the end closer to the center line CL. Therefore, in solder 25a and 25b, the fillet weld at the end farther from the center line CL of the metal substrate 30 is greater than the fillet weld at the end closer to the center line CL. Additionally, in the semiconductor device 10a, the protrusions 32a and 34a can also be convex shapes formed by connecting them together along the edge of the ceramic circuit board 21. Similarly, the protrusions 33b, 35b, 33a, 35a, 32b, and 34b can also be convex shapes formed by connecting them together along the edge of the ceramic circuit board 21. Furthermore, the height of the structure formed by connecting the protrusions 33a and 35a is greater than the height of the structure formed by connecting the protrusions 32a and 34a. The protrusions 32b to 35b are also the same height.

[0072] Additionally, using Figure 8 and Figure 9 The manufacturing method of such a semiconductor device 10a will be described. Figure 8 This is a flowchart of a method for manufacturing a second semiconductor device. Figure 9 This is a diagram illustrating the arrangement of the solder joint apparatus in a method for manufacturing a second semiconductor device. It should be noted that... Figure 8 In the flowchart, simplify or omit... Figure 3 The flowchart provides a detailed description of the same process. Additionally, Figure 9 Also with Figure 1 The cross-sectional view at the position corresponding to the single-dotted line XX is equivalent to the first embodiment. Figure 4 .

[0073] First, similar to the first embodiment, components such as semiconductor chips 28a and 28b, ceramic circuit board 21, metal substrate 30, and solder plate of semiconductor device 10a are prepared (step S1). It should be noted that for the metal substrate 30, the following components are prepared... Figure 7 The base plate shown. That is, a metal base plate 30 is prepared as follows: for the configuration areas 36a and 36b, the protrusions 33a, 35a and 32b, 34b located on the outer side relative to the center line CL are formed higher than the protrusions 32a, 34a and 33b, 35b on the side of the center line CL.

[0074] Next, the metal substrate 30 is placed in a predetermined area of ​​the solder bonding device 50. It should be noted that the metal substrate 30 can also be slightly warped into a convex shape with its center portion facing upwards. That is, the metal substrate 30 can be warped so that its center portion protrudes upwards relative to both the short and long sides. Solder plates 27a and 27b are respectively positioned to be supported by protrusions 32a-35a and 32b-35b formed in the placement areas 36a and 36b of the metal substrate 30. The solder plates 27a and 27b are supported by protrusions 32a-35a and 32b-35b of different heights, such that their centerline CL side is lower and inclined than the outer side farther from the centerline CL. Figure 9 As shown, a ceramic circuit board 21 is placed on solder plates 27a and 27b, and semiconductor chips 28a and 28b are placed on circuit patterns 24b and 24c of the ceramic circuit board 21 via solder plates (not shown) (step S2).

[0075] In steps S3 and S4, the following steps are performed: Figure 3The process is the same as steps S4 and S5 in the flowchart. That is, the solder bonding device 50 is driven to heat the solder plates 27a and 27b via the back side of the metal substrate 30 (step S3). As a result, the metal substrate 30 produces a convex warp with its center facing downward. Then, the molten solder 27a1 and 27b1 obtained by melting the solder plates 27a and 27b spreads between the back side of the ceramic circuit board 21 and the placement areas 36a and 36b. It should be noted that, in this case, in order to suppress the excessive spread of the molten solder 27a1 and 27b1, a resist component may also be coated parallel to the center line CL on the outer side of the side of the placement areas 36a and 36b away from the center line CL.

[0076] Furthermore, if the heights of protrusions 33a, 35a, 32b, 34b are 100 μm or more greater than the heights of protrusions 32a, 34a, 33b, 35b, the ends of molten solder 27a1, 27b1 on the side of the ceramic circuit substrate 21 away from the center line CL may be thinner than the ends on the side of the ceramic circuit substrate 21 closer to the center line CL. On the other hand, if the heights of protrusions 33a, 35a, 32b, 34b are much greater than the heights of protrusions 32a, 34a, 33b, 35b, sometimes the molten solder 27a1, 27b1 cannot fill the ends of the ceramic circuit substrate 21 away from the center line CL. In this case, the solder 25a and 25b obtained by solidifying the molten solder 27a1 and 27b1 in subsequent processes will not be able to support the entire end of the ceramic circuit board 21 on the side away from the center line CL through the fillet weld. On the other hand, when the height of the protrusions 33a, 35a and 32b, 34b is about 100 μm higher than the height of the protrusions 32a, 34a and 33b, 35b, the molten solder 27a1 and 27b1 can reliably fill the end of the ceramic circuit board 21 on the side away from the center line CL. As a result, the thickness of the molten solder 27a1 and 27b1 at the end away from the center line CL of the metal substrate 30 is greater than the thickness at the end closer to the center line CL.

[0077] Next, the molten solder 27a1 and 27b1 obtained by melting solder plates 27a and 27b are cooled (step S4). Thus, the molten solder 27a1 and 27b1 are cooled and solidified to become solder 25a and 25b, which are then removed from the solder bonding device 50, as follows: Figure 7 As shown, a ceramic circuit board 21 is bonded to a metal substrate 30 to obtain a semiconductor device 10a.

[0078] Thus, in the semiconductor device 10a, a ceramic circuit board 21 is disposed on protrusions 32a, 34a, 33b, 35b and higher-than-normal-height protrusions 33a, 35a, 32b, 34b of the placement areas 36a, 36b formed on the metal substrate 30 via solder plates 27a, 27b, and the ceramic circuit board 21 is bonded to the placement areas 36a, 36b by melting the solder plates 27a, 27b. Consequently, the thickness of the ends of the molten solder 27a1, 27b1 away from the center line CL is greater than the thickness of the ends closer to the center line CL. Therefore, the outer region of the molten solder 27a1, 27b1 can compensate for the volume of the shrinkage portion as it shrinks, suppressing the formation of shrinkage cavities. Therefore, compared to the first embodiment, the pressing process (using hammers 41a, 41b) is eliminated, reducing manufacturing costs. Furthermore, the semiconductor device 10a uses protrusions 32a, 34a, 33b, and 35b, as well as protrusions 33a, 35a, 32b, and 34b with a height greater than these protrusions. Therefore, the thickness of the ends of the solder 25a and 25b furthest from the center line CL is greater than the thickness of the ends closer to the center line CL. Thus, it is possible to reliably form fillet welds where the thickness of the ends furthest from the center line CL is greater than the thickness of the ends closer to the center line CL compared to the first embodiment.

[0079] The semiconductor device 10a manufactured in this way has a metal substrate 30 and a ceramic circuit board 21. The metal substrate 30 has arrangement regions 36a and 36b separated from the center line CL on its front side. The ceramic circuit board 21 is provided in the arrangement regions 36a and 36b by solder 25a and 25b. At this time, the thickness of the ends of the solder 25a and 25b away from the center line CL is greater than the thickness of the ends closer to the center line CL. In the region outside the solder 25a and 25b, the formation of shrinkage cavities is suppressed. With this manufacturing method, the increase in the amount of solder 25a and 25b can be suppressed, as well as the increase in the thermal resistance of the solder 25a and 25b, and the reduction in the heat dissipation of the semiconductor device 10a can also be prevented. In addition, the protrusions 32a to 35a and the protrusions 32b to 35b all support the back side of the semiconductor units 20a and 20b. Therefore, the adhesion between the solder 25a, 25b and the metal substrate 30 is better than in the first embodiment, and the bonding strength between the metal substrate 30 and the semiconductor units 20a, 20b is improved. As a result, the decrease in reliability of the semiconductor device 10a is suppressed, thereby ensuring stable operation of the semiconductor device 10a.

[0080] [Third Implementation Method]

[0081] use Figure 10 and Figure 11 The semiconductor device 10b of the third embodiment will be described. Figure 10 This is a top view of the semiconductor device according to the third embodiment. Figure 11 This is a cross-sectional view of the semiconductor device according to the third embodiment. It should be noted that... Figure 11 yes Figure 10 A cross-sectional view at the point indicated by the single-dotted line XX. Furthermore, in the third embodiment, the same symbols are used to label components identical to those in the first and second embodiments. Descriptions of these components are simplified or omitted.

[0082] Semiconductor device 10b includes four semiconductor units 20c, 20d, 20e, and 20f and a metal substrate 30 on which the semiconductor units 20c, 20d, 20e, and 20f are disposed by solder (solder 25c for semiconductor unit 20c). It should be noted that, hereinafter, without specifically distinguishing between semiconductor units 20c, 20d, 20e, and 20f, they will be described as semiconductor unit 20.

[0083] The metal base plate 30 has a heat dissipation plate 31 and protrusions 32c-35c, 32d-35d, 32e-35e, and 32f-35f formed on the front side of the heat dissipation plate 31. It should be noted that... Figure 10 In the diagram, dashed lines indicate the formation locations of these protrusions 32c~35c, 32d~35d, 32e~35e, and 32f~35f.

[0084] On the heat sink 31, symmetrically arranged rectangular configuration areas 36c, 36d, 36e, and 36f are positioned with the central portion CP as the center. Specifically, configuration areas 36c and 36f are point-symmetric with respect to the central portion CP. Configuration areas 36d and 36e are also point-symmetric with respect to the central portion CP. Furthermore, configuration areas 36c and 36d, as well as configuration areas 36e and 36f, are line-symmetric with respect to a straight line (not shown) passing through the central portion CP and parallel to its shorter side. Further, configuration areas 36c and 36e, as well as configuration areas 36d and 36f, are line-symmetric with respect to a straight line (not shown) passing through the central portion CP and parallel to its longer side.

[0085] Protrusions 32c-35c, 32d-35d, 32e-35e, and 32f are integrally formed at the corners of configuration areas 36c, 36d, 36e, 36e, and 36f, respectively. These protrusions 32c-35c, 32d-35d, 32e-35e, and 32f-35f are configured such that the height of the protrusions farther from the center CP is greater than the height of the protrusions closer to the center CP. For example, the case of configuration area 36c will be explained. Figure 11 As shown, among the protrusions 32c to 35c, the protrusion 32c, which is closest to the center CP, has the lowest height, while the protrusion 35c, which is farthest from the center CP, has the highest height. Protrusions 33c and 34c (in...) Figure 11The height of the protrusion 33c (omitted in the illustration) is the height between the heights of protrusions 32c and 35c. It should be noted that in... Figure 11 In the diagram, the position of protrusion 34c is indicated by a dashed line. Protrusions 32c to 35c are formed in this way, if according to... Figure 8 The flowchart shows that the ceramic circuit board 21 is disposed on the arrangement area 36c by solder 25c, and the thickness of the end of solder 25c away from the center CP is greater than the thickness of the end of solder 25c closer to the center CP. Here, the thickness of the end of solder 25c can be the thickness of the solder 25c formed between the back side of the end of the metal plate 23 formed on the ceramic circuit board 21 and the front side of the heat sink 31 of the metal substrate 30 excluding the protrusions 32c to 35c. In this case, as Figure 10 As shown, the solder 25c thickness of the region Fc surrounded by the dashed line in semiconductor cell 20c is thicker than that of the region Nc, which is closer to the center CP and also surrounded by the dashed line. Similarly, among the other configuration regions 36d, 36e, and 36f, the protrusions 32d-35d, 32e-35e, and 32f-35f, are closest to the center CP in height (32d, 32e, 32f) and furthest from the center CP in height (35d, 35e, 35f). The heights of protrusions 33d, 34d, 33e, 34e, 33f, and 34f are between the heights of these protrusions. If we follow... Figure 8 The flowchart shows that the ceramic circuit board 21 is placed on the arrangement areas 36d, 36e, and 36f using solder (not shown). In this case, the solder thickness at the end furthest from the center CP is greater than the solder thickness at the end closer to the center CP. In this situation, if... Figure 10 As shown, the solder thickness of the regions Fd, Fe, and Ff enclosed by dashed lines in semiconductor cells 20d, 20e, and 20f is thicker than that of the regions Nd, Ne, and Nf enclosed by dashed lines near the center CP. Furthermore, the amount of solder overflow from the ends of the metal plate 23 on the front side of the metal substrate 30 is greater at the ends farther from the center CP than at the ends closer to the center CP. Therefore, the fillet weld at the ends of the solder farther from the center CP of the metal substrate 30 is larger than the fillet weld at the ends closer to the center CP. It should be noted that, hereinafter, the solder that bonds semiconductor cells 20c, 20d, 20e, and 20f to the metal substrate 30 will be simply described as solder.

[0086] Such a semiconductor device 10b has a metal substrate 30 and a ceramic circuit board 21. The metal substrate 30 has arrangement regions 36c, 36d, 36e, and 36f separated from the center portion CP on its front side. The ceramic circuit board 21 is disposed in the arrangement regions 36c, 36d, 36e, and 36f by solder. In this case, the thickness of the solder at the end furthest from the center portion CP is greater than the thickness of the solder at the end closest to the center portion CP. In the region outside the solder, the formation of shrinkage cavities is suppressed. This manufacturing method suppresses the increase in the amount of solder, also suppresses the increase in the thermal resistance of the solder, and prevents a decrease in the heat dissipation of the semiconductor device 10b. Therefore, the decrease in the reliability of the semiconductor device 10b is suppressed, thereby ensuring stable operation of the semiconductor device 10b.

[0087] It should be noted that, in the semiconductor device 10b, when the heights of the protrusions 32c-35c, 32d-35d, 32e-35e, and 32f-35f are all flush, according to Figure 3 The flowchart is used to manufacture it. In this case, in step S3, the pressure hammers are respectively set at... Figure 10 The regions shown are Nc, Nd, Ne, and Nf. Alternatively, they may also include... Figure 10 A pressure hammer is disposed within the regions Nc, Nd, Ne, and Nf shown. As a result, the back surface of the ceramic circuit board 21 is supported by protrusions 32c, 33d, 34e, and 35f closest to the center portion CP. Furthermore, the back surface of the ceramic circuit board 21 is spaced apart from the front portions of the protrusions 35c, 34d, 33e, and 32f furthest from the center portion CP.

[0088] [Fourth Implementation Method]

[0089] In the fourth embodiment, using Figure 12 and Figure 13 The case in which multiple semiconductor units are arranged in a straight line on a metal substrate will be explained. Figure 12 This is a top view of the semiconductor device according to the fourth embodiment. Figure 13 This is a cross-sectional view of the semiconductor device according to the fourth embodiment. It should be noted that... Figure 13 yes Figure 12 A cross-sectional view at the point indicated by the single-dotted line XX. It should be noted that in the fourth embodiment, the same symbols are used to label the same components as in the first to third embodiments. Descriptions of these components are simplified or omitted. Furthermore, semiconductor units 20g, 20h, 20i, 20j, 20k, and 20l have the same configuration as semiconductor unit 20. Therefore, in Figure 12 and Figure 13 The symbols for the various components of semiconductor units 20g, 20h, 20i, 20j, 20k, and 20l have been omitted. Furthermore, in... Figure 12In the diagram, rectangles represent the configuration of semiconductor cells 20g, 20h, 20i, 20j, 20k, and 20l. Additionally, in... Figure 12 In the diagram, the position of the protrusion is indicated by a dashed line, and the symbol is omitted.

[0090] Semiconductor device 10c includes a plurality of semiconductor units 20g, 20h, 20i, 20j, 20k, 20l and a metal substrate 30 on which the semiconductor units 20g, 20h, 20i, 20j, 20k, 20l are disposed. The semiconductor units 20g, 20h, 20i, 20j, 20k, 20l are suitably electrically connected to each other via bonding wires. Electronic components are disposed on the metal substrate 30. The electronic components are suitably electrically connected to the semiconductor units 20g, 20h, 20i, 20j, 20k, 20l via bonding wires. Configuration regions 36g, 36h, 36i and configuration regions 36j, 36k, 36l are linearly disposed on the metal substrate 30 across a center line CL. Semiconductor units 20g, 20h, 20i, 20j, 20k, and 20l are respectively disposed in the configuration areas 36g, 36h, 36i, 36j, 36k, and 36l by solder. Furthermore, similar to the first embodiment, protrusions of the same height are integrally formed at the corners of the configuration areas 36g, 36h, 36i, 36j, 36k, and 36l.

[0091] like Figure 13 As shown, in the semiconductor units 20g and 20l (ceramic circuit board 21) furthest from the center line CL (center portion) of the metal substrate 30, the thickness of the ends of the solder 25g and 25l furthest from the center line CL (center portion) of the metal substrate 30 is greater than the thickness of the ends of the solder 25g and 25l closer to the center line CL. Here, the thickness of the ends of the solder 25g and 25l can be the thickness of the solder 25g and 25l formed between the back side of the end of the metal plate 23 formed on the ceramic circuit board 21 and the front side of the heat sink 31 of the metal substrate 30, excluding the protrusions 32g, 33g, 32l, and 33l. Furthermore, the amount of solder 25g and 25l overflowing from the end of the metal plate 23 on the front side of the metal substrate 30 is greater at the ends furthest from the center line CL (center portion) than at the ends closer to the center line CL. Therefore, the fillet welds at the ends of solder 25g and 25l furthest from the center line CL of the metal substrate 30 are larger than those at the ends closest to the center line CL. Furthermore, the front ends of the protrusions 32g and 33l located on the side closest to the center line CL of the metal substrate 30 abut against the back surface of the semiconductor units 20g and 20l (ceramic circuit board 21). On the other hand, the back surface of the semiconductor units 20g and 20l (ceramic circuit board 21) is separated from the protrusions 33g and 32l furthest from the center line CL by gaps 26g and 26l.

[0092] Furthermore, such as Figure 13 As shown, for the inner semiconductor units 20h to 20k, excluding the semiconductor units 20g and 20l furthest from the center line CL (center portion) of the metal substrate 30, the thickness of the solder ends can be such that the solder ends furthest from the center line CL (center portion) of the metal substrate 30 are thinner than the solder ends closest to the center line CL. Furthermore, the amount of solder overflow from the ends of the metal plate 23 on the front side of the metal substrate 30 can be less at the ends furthest from the center line CL (center portion) than at the ends closest to the center line CL. Therefore, the fillet welds at the ends of these solders furthest from the center line CL of the metal substrate 30 can be smaller than the fillet welds at the ends closest to the center line CL. Additionally, the front end of the protrusion located on the side closest to the center line CL of the metal substrate 30 can be separated from the back side of the semiconductor units 20h to 20k by a gap. On the other hand, the back side of the semiconductor units 20h to 20k can abut against the protrusion furthest from the center line CL.

[0093] according to Figure 3 The flowchart shown illustrates the manufacture of such a semiconductor device 10c. In step S3 of this case, a pressure hammer is positioned at the end of the semiconductor unit 20g, 20l (ceramic circuit board 21) furthest from the centerline CL on the metal substrate 30 (outermost) side. The pressure hammer can then be of the same shape and material as in the first embodiment.

[0094] Then, if such a metal substrate 30 is placed on the solder bonding device 50 in step S4, heat propagates outward from the center (centerline CL) of the metal substrate 30. Therefore, the solder at the ends of the semiconductor units 20g and 20l (ceramic circuit board 21) furthest from the centerline CL is the last to be melted. Then, in step S5, the drive of the solder bonding device 50 is stopped, and the molten solder obtained from the melted solder is cooled. At this time, cooling also occurs from the center (centerline CL) toward the outer edge of the metal substrate 30. As the molten solder cools, as described above, the last outer region to be cooled solidifies, and its volume shrinks. Therefore, shrinkage cavities are easily formed at the solder at the ends of the outermost semiconductor units 20g and 20l furthest from the centerline CL. Therefore, when manufacturing the semiconductor device 10c, on the metal substrate 30 having multiple configuration areas 36g, 36h, 36i, 36j, 36k, and 36l, a pressure hammer is positioned near the center line CL on the ceramic circuit board 21 of the outermost configuration areas 36g and 36l. Figure 13As shown, in the semiconductor device 10c manufactured in this way, the thickness of the solder 25g and 25l at the ends of the semiconductor units 20g and 20l furthest from the center line CL (outermost) is greater than the thickness at the ends closer to the center line CL. In the region outside the solder 25g and 25l, the formation of shrinkage cavities is suppressed, thus suppressing an increase in the amount of solder 25g and 25l, and also suppressing an increase in the thermal resistance of the solder 25g and 25l, preventing a decrease in the heat dissipation of the semiconductor device 10c. Therefore, a decrease in the reliability of the semiconductor device 10c is suppressed, thereby ensuring stable operation of the semiconductor device 10c.

[0095] Furthermore, regarding the semiconductor device 10c, the semiconductor units 20g and 20l furthest from the center line CL (center portion) of the metal substrate 30 can also be formed as in the second embodiment and Figure 7 As shown in the diagram, protrusions 32a, 33a, 32b, and 33b. Protrusions 33g and 32l located on the outer side relative to the center line CL are formed higher than those on the center line CL side. The protrusions 32g, 33g, 32l, and 33l located on the side near the center line CL of the metal substrate 30 and the side away from the center line CL of the metal substrate 30 respectively abut against the back surface of the semiconductor units 20g and 20l at their front ends.

[0096] In this case, it is possible to follow Figure 8 The flowchart shown illustrates the fabrication of a semiconductor device 10c. In this case, among the arrangement regions 36g, 36h, 36i, 36j, 36k, and 36l of the metal substrate 30, the protrusions of the outermost arrangement regions 36g and 36l, away from the center line CL (in... Figure 13 The height of the protrusions 33g and 32l is greater than that of the protrusions near the center line CL. Figure 13 The height of the protrusions 32g and 33l is set high. Therefore, as... Figure 13 As shown with solder 25g and 25l, the thickness of the end furthest from the center line CL is greater than the thickness of the end closest to the center line CL. In this case, the formation of shrinkage cavities is also suppressed in the region outside of the solder 25g and 25l, thus suppressing the increase in the amount of solder 25g and 25l, suppressing the increase in the thermal resistance of the solder 25g and 25l, and preventing a decrease in the heat dissipation of the semiconductor device 10c. Therefore, the decrease in the reliability of the semiconductor device 10c is suppressed, thereby ensuring stable operation of the semiconductor device 10c.

[0097] Furthermore, according to the fourth embodiment, when four or more semiconductor cells 20 are arranged linearly on the metal substrate 30, it is preferable that at least for the outermost semiconductor cells 20, the thickness of the solder at the end away from the center line CL of the metal substrate 30 is greater than the thickness of the solder at the end near the center line CL. Additionally, according to the fourth embodiment, in the third embodiment, when three or more semiconductor cells 20 are arranged longitudinally and transversely on the metal substrate 30, it is preferable that at least for each of the outermost semiconductor cells 20 in both the longitudinal and transverse directions, the thickness of the solder at the end away from the center of the metal substrate 30 is greater than the thickness of the solder at the end near the center.

Claims

1. A semiconductor device, characterized by comprising: having: a metal base plate in which disposition regions are provided separately from a center portion on a front surface; and a substrate provided to the disposition regions by solder, a thickness of an end portion of the solder away from the center portion is thicker than a thickness of an end portion of the solder close to the center portion, the disposition regions of the metal base plate are provided a plurality of times along a predetermined direction from the center portion, and the substrates are provided to the disposition regions by the solder respectively, a thickness of an end portion of the solder away from the center portion in the disposition region that is outermost along the predetermined direction from the center portion is thicker than a thickness of an end portion of the solder close to the center portion.

2. The semiconductor device according to claim 1, characterized in that the metal base plate is warped in a convex shape in which the center portion protrudes to an opposite side of the front surface.

3. The semiconductor device according to claim 1 or 2, characterized in that a first protruding portion is formed at a first formation position on one side close to the center portion, and a second protruding portion is formed at a second formation position on one side away from the center portion with respect to the first formation position in the disposition region.

4. The semiconductor device according to claim 3, characterized in that the first protruding portion abuts to a back surface of the substrate, a length of the second protruding portion is equal to a length of the first protruding portion, and the second protruding portion is separated from the back surface of the substrate.

5. The semiconductor device according to claim 3, characterized in that the first protruding portion abuts to a back surface of the substrate, the second protruding portion is longer than the first protruding portion, and abuts to the back surface of the substrate.

6. The semiconductor device according to claim 1, characterized in that the disposition regions of the metal base plate are provided symmetrically with the center portion as a center, the substrates are provided to the disposition regions respectively.

7. A semiconductor device, characterized by comprising: having: a metal base plate in which disposition regions are provided separately from a center portion on a front surface; and a substrate provided to the disposition regions by solder, a fillet of an end portion of the solder away from the center portion is larger than a fillet of an end portion of the solder close to the center portion, the disposition regions of the metal base plate are provided a plurality of times along a predetermined direction from the center portion, and the substrates are provided to the disposition regions by the solder respectively, a thickness of an end portion of the solder away from the center portion in the disposition region that is outermost along the predetermined direction from the center portion is thicker than a thickness of an end portion of the solder close to the center portion.

8. A method for manufacturing a semiconductor device, characterized by including: a preparation step of preparing a metal base plate in which disposition regions are provided separately from a center portion on a front surface, and the metal base plate is in a convex shape in which the center portion protrudes to the front surface side, and a substrate; a disposition step of providing the substrate to the disposition regions by solder; and a joining step of pressing one side of a front surface of the substrate close to the center portion to the metal base plate side while melting the solder to join the substrate to the disposition regions.

9. The method of manufacturing a semiconductor device according to claim 8, characterized in that, A first protruding portion is formed at a first formation position on a side close to the center portion, and a second protruding portion is formed at a second formation position on a side farther from the center portion than the first formation position.

10. The method according to claim 9, wherein the first protruding portion has a length equal to a length of the second protruding portion, after the joining step, the first protruding portion abuts against a back surface of the substrate, and the second protruding portion is separated from the back surface of the substrate.

11. The method according to claim 9, wherein the second protruding portion is longer than the first protruding portion, after the joining step, the first protruding portion abuts against a back surface of the substrate, and the second protruding portion abuts against the back surface of the substrate.

12. The method according to claim 8, wherein in the joining step, a press hammer is disposed on a side close to the center portion on a front surface of the substrate, and the substrate is pressed toward the metal base plate side.

Images