Semiconductor Module

Abstract

To enable an attachment of a semiconductor module to a cooling substrate without generating damages.SOLUTION: In a semiconductor module 2, a back surface support part 12 projected from a back surface at a neighbor to the side opposite to a heat radiation plate 35 against a pair of attachment holes 11 in a back surface from the back surface is formed. When attaching the semiconductor module 2 to a cooling substrate 3 with a screw 4, the semiconductor module 2 is prevented from being floated on the other attachment hole 11 side by the back surface support part 12 so that the heat radiation plate 35 becomes a support point. The semiconductor module 2 is horizontally maintained to the cooling substrate 3, and is fastened to a fastening hole 3a of the cooling substrate 3 while inserting the screw 4 into one attachment hole 11. Then, the semiconductor module 2 is fastened to the fastening hole 3a of the cooling substrate 3 with the screw 4 to the other attachment hole 11 without receiving damages.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] The semiconductor device includes a semiconductor module including a semiconductor chip and a heat sink attached to the semiconductor module. The semiconductor chip includes a switching element and a diode element of a power device. The switching element is, for example, an insulated gate bipolar transistor (IGBT) or a power metal oxide semiconductor field effect transistor (MOSFET). The diode element is, for example, a Schottky barrier diode (SBD) or a free wheeling diode (FWD) of a P-intrinsic-N (PiN) diode. A control IC controls the driving of the switching element. Such a semiconductor module is attached to the heat sink using screws (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 239997 Summary of the Invention [Problem to be solved by the invention]

[0004] In the semiconductor device described above, the semiconductor module may be damaged when it is attached to the heat sink with screws. For example, if the semiconductor module has screw holes on both sides of its length in a plan view, one end is screwed to the heat sink (cooling substrate) and the other end is screwed. In this case, screwing one end may cause the other end of the semiconductor module to float. If the other end is screwed in this state, a large stress will be applied to the center of the semiconductor module. This could, for example, cause the case of the semiconductor module to break and cracks to form in the substrate inside the semiconductor module.

[0005] The present invention has been made in view of the above points, and has as its object to provide a semiconductor module that can be attached to a cooling substrate without being damaged. [Means for solving the problem]

[0006] According to one aspect of the present invention, a semiconductor device includes: a semiconductor chip; and a sealing body portion having a rectangular parallelepiped shape in which the semiconductor chip is sealed with a sealing member, a main surface of a heat sink protruding from a back surface, and a pair of mounting holes penetrating a front surface and the back surface formed on both sides of the heat sink in a plan view; wherein a back surface support portion protruding from the back surface is formed near the opposite side of the heat sink relative to the pair of mounting holes on the back surface; or a front surface support portion protruding from the front surface is formed near the sides of the front surface where the pair of mounting holes face each other. a width of the back surface support portion in an extension direction of the long sides of the sealing main body portion corresponds to a length from the pair of mounting holes to the opposing short sides of the sealing main body portion, and the front surface support portion has an inclined surface whose height relative to the front surface increases with increasing distance from the opposing short sides; A semiconductor module is provided. [Effects of the Invention]

[0007] According to the disclosed technology, the semiconductor module is attached to the cooling substrate without being damaged, and a decrease in reliability is suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a plan view of a semiconductor device according to a first embodiment; [Figure 2] 1 is a side cross-sectional view of a semiconductor device according to a first embodiment. [Figure 3] FIG. 1 is a plan view of a semiconductor module according to a first embodiment. [Figure 4] FIG. 2 is a bottom view of the semiconductor module according to the first embodiment. [Figure 5] FIG. 1 is a side view of a semiconductor module according to a first embodiment. [Figure 6] 1 is a cross-sectional plan view of a semiconductor module according to a first embodiment. [Figure 7] 1 is a side cross-sectional view of a semiconductor module according to a first embodiment. [Figure 8] 2A and 2B are diagrams illustrating how the semiconductor module of the first embodiment is attached to a cooling substrate. [Figure 9] 10A and 10B are diagrams illustrating mounting of a semiconductor module of a reference example to a cooling substrate. [Figure 10] FIG. 10 is a cross-sectional side view of a main part of a semiconductor device according to a modified example 1-1 of the first embodiment. [Figure 11] FIG. 10 is a bottom view of a semiconductor module according to a modified example 1-2 of the first embodiment. [Figure 12] FIG. 10 is a bottom view of a semiconductor module according to a modified example 1-3 of the first embodiment. [Figure 13] FIG. 10 is a plan view of a semiconductor module according to a second embodiment. [Figure 14] FIG. 10 is a bottom view of the semiconductor module according to the second embodiment. [Figure 15] FIG. 10 is a side view of a semiconductor module according to a second embodiment. [Figure 16] 10 is a diagram (part 1) showing how the semiconductor module of the second embodiment is attached to a cooling substrate; FIG. [Figure 17] FIG. 10 is a diagram (part 2) showing how the semiconductor module of the second embodiment is attached to the cooling substrate; DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described with reference to the drawings. In the following description, the terms "front surface" and "upper surface" refer to the surface facing upward in the semiconductor device 1 shown in the drawings. Similarly, "up" refers to the upward direction in the semiconductor device 1 shown in the drawings. The terms "back surface" and "lower surface" refer to the surface facing downward in the semiconductor device 1 shown in the drawings. Similarly, "lower" refers to the downward direction in the semiconductor device 1 shown in the drawings. Similar directions will be used in other drawings as necessary. The terms "front surface," "upper surface," "upper," "back surface," "lower surface," "lower," and "side surface" are merely convenient expressions for specifying relative positional relationships and do not limit the technical concept of the present invention. For example, "upper" and "lower" do not necessarily refer to the vertical direction relative to the ground. In other words, the "upper" and "lower" directions are not limited to the direction of gravity. In the following description, the term "main component" refers to a component containing 80 vol% or more of a component.

[0010] [First embodiment] The semiconductor device 1 will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a plan view of the semiconductor device of the first embodiment, and Fig. 2 is a side cross-sectional view of the semiconductor device of the first embodiment. Fig. 2 is a cross-sectional view taken along the dashed dotted line X1-X1 in Fig. 1.

[0011] The semiconductor device 1 includes a semiconductor module 2 and a cooling substrate 3. The semiconductor module 2 is fastened to the cooling substrate 3 with screws 4. The semiconductor module 2 has a substantially rectangular shape in a plan view. The corners of the semiconductor module 2 may be chamfered. The chamfering may be R-chamfering or C-chamfering. A heat sink 35 protrudes from the back surface of the semiconductor module 2. Its thickness (distance in the -Z direction) is Tc. The semiconductor module 2 is formed with mounting holes 11. The pair of mounting holes 11 are formed at both ends of the semiconductor module 2 in the longitudinal direction (±Y directions) and in the center in the lateral direction (±X directions) in a plan view. The pair of mounting holes 11 are formed closer to the short side of the semiconductor module 2 than the heat sink 35 in a plan view. The mounting holes 11 penetrate the front and back surfaces of the semiconductor module 2.

[0012] A back surface support portion 12 is formed on the back surface of the semiconductor module 2. The back surface support portion 12 is formed outside the longitudinal direction of the mounting hole 11 on the back surface of the semiconductor module 2. The back surface support portion 12 may be formed along the short side of the back surface of the semiconductor module 2. The height (length in the -Z direction) of the back surface support portion 12 is Ta. The height Ta of the back surface support portion 12 may be smaller than the thickness Tc of the heat sink 35, but is preferably approximately the same as the thickness Tc. The thickness Tc is 0.1 mm or more and 0.3 mm or less, for example, 0.2 mm. The distance Lb between the back surface support portion 12 and the end of the heat sink 35 is approximately 1 mm larger than the diameter of the screw 4 (shank 4a). The semiconductor module 2 will be described in detail later.

[0013] The cooling substrate 3 has a substantially smooth main surface. The semiconductor module 2 is mounted on this main surface. The semiconductor module 2 may also be mounted on this main surface via thermal grease. The cooling substrate 3 includes this main surface and is, for example, flat. The cooling substrate 3 is not limited to being flat as long as it includes this main surface. The cooling substrate 3 may have a plurality of fins formed on its rear surface. Fastening holes 3a are formed in the cooling substrate 3. The fastening holes 3a are formed at positions corresponding to the mounting holes 11 of the semiconductor modules 2 mounted on the main surface. Screws 4 are threaded into the fastening holes 3a and fastened to the screws 4. The fastening holes 3a do not necessarily have to pass through the cooling substrate 3. It is sufficient for the fastening holes 3a to be able to fasten the screws 4.

[0014] Such a cooling substrate 3 is mainly composed of a metal with excellent thermal conductivity. The metal is, for example, copper, aluminum, or an alloy containing at least one of these. The thickness of the cooling substrate 3 is 0.5 mm or more and 2.0 mm or less. The entire cooling substrate 3 may be plated. The plating improves the corrosion resistance of the cooling substrate 3. In this case, the plating material used is, for example, nickel, a nickel-phosphorus alloy, or a nickel-boron alloy.

[0015] A cooling device may be attached to the backside of the cooling substrate 3. The cooling device is attached via solder, brazing material, or thermal interface material. This also makes it possible to improve the heat dissipation of the cooling substrate 3. The cooling device dissipates heat by circulating a refrigerant inside. The brazing material is mainly composed of at least one of aluminum alloy, titanium alloy, magnesium alloy, zirconium alloy, and silicon alloy, for example. When brazing material is used, the cooling substrate 3 Front The semiconductor module 2 can be joined to the mounting area of ​​the semiconductor module 2 on the surface by brazing. Thermal interface material is a general term for various materials such as thermally conductive grease, elastomer sheet, RTV (Room Temperature Vulcanization) rubber, gel, and phase change material. Grease is, for example, silicone mixed with metal oxide filler.

[0016] The screw 4 includes a shank 4a and a head 4b. The shank 4a is cylindrical. A groove that can be threaded into the fastening hole 3a is formed at least at the tip of the shank 4a. The diameter of the shank 4a corresponds to the diameters of the mounting hole 11 and the fastening hole 3a. The diameters of the mounting hole 11 and the fastening hole 3a are, for example, approximately 1 mm larger than the diameter of the shank 4a.

[0017] The head 4b is integrally joined to the other end of the shank 4a. The other end of the shank 4a is the end opposite the tip of the cylindrical shank 4a. The surface of the head 4b joined to the other end of the shank 4a may be a substantially smooth main surface. The head 4b may be rectangular, semispherical, or trapezoidal in side view. The diameter of the head 4b is longer than the diameter of the shank 4a, for example, two or more times and four or less times the diameter of the shank 4a. Such a screw 4 is made of a material expected to have high strength. Examples of such materials include steel, stainless steel, brass, aluminum, magnesium, plastic, and titanium.

[0018] The screws 4 are inserted through the mounting holes 11 of the semiconductor module 2 and fastened to the fastening holes 3a of the cooling substrate 3. The heads 4b of the fastened screws 4 press the periphery of the mounting holes 11 on the front surface of the semiconductor module 2 toward the cooling substrate 3. In addition, the rear surface support portion 12 and the heat sink 35 of the semiconductor module 2 are pressed against the front surface of the cooling substrate 3.

[0019] Next, details of the semiconductor module 2 will be described with reference to FIGS. 3 to 7. FIG. 3 is a plan view of the semiconductor module of the first embodiment, and FIG. 4 is a bottom view of the semiconductor module of the first embodiment. FIG. 5 is a side view of the semiconductor module of the first embodiment, FIG. 6 is a plan sectional view of the semiconductor module of the first embodiment, and FIG. 7 is a side sectional view of the semiconductor module of the first embodiment. Note that FIG. 5(A) shows a side view of the semiconductor module 2 of FIG. 3 as seen in the -Y direction, and FIG. 5(B) shows a side view of the semiconductor module of FIG. 3 as seen in the +X direction. FIG. 7 is a sectional view taken along the dashed dotted line Y1-Y1 of FIG. 6.

[0020] First, as shown in FIG. 3 , the semiconductor module 2 is molded into a three-dimensional shape by sealing the entire component with a sealing body 10. The sealing body 10 of the semiconductor module 2 is cubic. The corners of the sealing body 10 may be rounded. The sealing body 10 has a front surface 10e and a back surface 10f that are rectangular in plan view. The sealing body 10 is surrounded on all four sides by a pair of opposing long side surfaces 10a and 10c and a pair of opposing short side surfaces 10b and 10d. In other words, the sealing body 10 is surrounded on all four sides by one long side surface 10a, one short side surface 10b, the other long side surface 10c, and the other short side surface 10d, in that order. Note that one long side surface 10a, one short side surface 10b, the other long side surface 10c, and the other short side surface 10d may also be referred to as one long side, one short side, the other long side, and the other short side, respectively.

[0021] Semiconductor Module 2 The front of teeth , sealed Stopper body 10 Compatible with front side 10eThat is, the back surface of the insulating plate 44 is exposed from the back surface 10f of the sealing body 10. The back surfaces of the insulating plate 44 and the back surface 10f of the sealing body 10 are flush with each other. Furthermore, as shown in FIG. 4, a heat sink 35 is provided on the back surface of the insulating plate 44 and the back surface 10f of the sealing body 10.

[0022] The semiconductor module 2 has a pair of mounting holes 11 formed on the short side surfaces 10b, 10d of the heat sink 35 in a plan view (of the back surface 10f) on a center line passing through the centers of the short side surfaces 10b, 10d. The diameter of the mounting holes 11 is such that the shanks 4a of the screws 4 can be inserted therethrough. Rear surface support portions 12 are formed further outward from the mounting holes 11 on the rear surface 10f of the semiconductor module 2. The rear surface support portions 12 have a length corresponding to at least the width of the pair of mounting holes 11 parallel to the opposing short side surfaces 10b, 10d, and are formed to face the pair of mounting holes 11. The rear surface support portions 12 are rectangular in a plan view (of the back surface 10f). The rear surface support portions 12 are formed along the short side surfaces 10b, 10d in a plan view (of the back surface 10f). The width of the back surface support portion 12 (length in the ±Y directions, length in the direction in which the long sides of the semiconductor module 2 extend) corresponds to the length from the pair of mounting holes 11 to the opposing short side surfaces 10b, 10d. The length (in the ±X directions) of the back surface support portion 12 is formed continuously along the opposing short side surfaces 10b, 10d from one long side surface 10a to the other long side surface 10c. In other words, the length of the back surface support portion 12 in the ±X directions extends from just in front of the long side surface 10a to just in front of the long side surface 10c.

[0023] In the semiconductor module 2, a plurality of control lead frames 20 and a plurality of main current lead frames 30 extend vertically from both long side surfaces 10a, 10c of the encapsulation body 10. In this case, the main current lead frames 30 are provided on the long side surface 10c of the encapsulation body 10 at predetermined intervals.

[0024] In this semiconductor module 2, components such as those shown in FIGS. 6 and 7 are sealed in a sealing body 10. The sealing body 10 is integrally formed with the back support 12. The semiconductor module 2 includes three semiconductor chips 41a and 41b to 41d, a control lead frame 20, a main current lead frame 30, control ICs 42a and 42b, electronic components 43, and an insulating plate 44. Specifically, the three semiconductor chips 41a and 41b to 41d, the control lead frame 20, the main current lead frame 30, the control ICs 42a and 42b, the electronic components 43, and the insulating plate 44 are set in a predetermined mold. This mold includes a portion corresponding to the back support 12. Then, the mold is filled with a sealing material for the sealing body 10. After the sealing material solidifies, the mold is removed to obtain the semiconductor module 2 with the back support 12. Therefore, the sealing body 10 and the back support 12 may be made of the same material.

[0025] The control IC 42a and the three semiconductor chips 41a are electrically and mechanically connected by control wires 45a. and It is electrically and mechanically connected to the control lead frame 20 by a control wire 45a.

[0026] Furthermore, the three semiconductor chips 41a are electrically and mechanically connected to the main current lead frame 30 by main current wires 45b. The semiconductor chips 41b to 41d are electrically and mechanically connected to the main current lead frame 30 by main current wires 45b.

[0027] The control wire 45a and the main current wire 45b are made of a material with excellent conductivity, such as gold, silver, copper, aluminum, or an alloy containing at least one of these. The diameter of the control wire 45a is, for example, 10 μm or more and 250 μm or less. The diameter of the main current wire 45b is, for example, 300 μm or more and 500 μm or less.

[0028] The semiconductor chips 41a to 41d are mainly composed of silicon, silicon carbide, or gallium nitride. These semiconductor chips 41a to 41d include RC (Reverse Conducting)-IGBT switching elements, in which an IGBT and an FWD are configured within one chip. The RC-IGBT chip configures a circuit in which the IGBT and the FWD are connected in anti-parallel. These semiconductor chips 41a to 41d have input electrodes (collector electrodes) as main electrodes on their back surfaces. Furthermore, the semiconductor chips 41a to 41d have control electrodes (gate electrodes) and output electrodes (emitter electrodes) on their front surfaces. The semiconductor chips 41a to 41d shown in FIG. 6 are arranged with the gate electrodes facing the long side surface 10c. The thickness of the semiconductor chips 41a to 41d is, for example, 50 μm or more and 220 μm or less. Instead of these semiconductor chips 41a to 41d, six pairs of semiconductor chips, each pair consisting of a semiconductor chip including a switching element and a semiconductor chip including a diode element, may be arranged. In this case, the semiconductor chips 41a to 41d of the switching elements are, for example, power MOSFETs and IGBTs. Each of these semiconductor chips 41a to 41d has, for example, a drain electrode (positive electrode, collector electrode in an IGBT) as a main electrode on the back surface, and a gate electrode (control electrode) as a control electrode and a source electrode (negative electrode, emitter electrode in an IGBT) as a main electrode on the front surface. The semiconductor chips of the diode elements are FWDs such as SBDs and PiN diodes. Each of these semiconductor chips has a cathode electrode as a main electrode on the back surface and an anode electrode as a main electrode on the front surface. This embodiment merely illustrates the case where six semiconductor chips 41a to 41d are provided. The number of sets is not limited to six, and can be any number depending on the specifications of the semiconductor module 2.

[0029] The backsides of the semiconductor chips 41a to 41d are joined to a predetermined main current lead frame 30 by solder (not shown). The solder is made of lead-free solder containing a predetermined alloy as a main component. The predetermined alloy is, for example, at least one of a tin-silver alloy, a tin-zinc alloy, and a tin-antimony alloy. The solder may contain additives such as copper, bismuth, indium, nickel, germanium, cobalt, or silicon. Instead of solder, joining may be performed by sintering using a sintering material. In this case, the sintering material is, for example, powder of silver, gold, or copper.

[0030] The main electrodes on the front surfaces of the semiconductor chips 41a to 41d are electrically and mechanically connected to the main current lead frame 30 via main current wires 45b. The gate electrodes on the front surfaces of the semiconductor chip 41a are electrically and mechanically connected to the control IC 42a via control wires 45a. The gate electrodes on the front surfaces of the semiconductor chips 41b to 41d are electrically and mechanically connected to the control IC 42b via control wires 45a.

[0031] The multiple main current lead frames 30 are provided on the long side surface 10c of the encapsulation body 10, and the other ends of the multiple main current lead frames 30 extend downward in FIG. 6 from the long side surface 10c of the encapsulation body 10. The main current lead frame 30, on which the semiconductor chips 41a-41d are arranged, has a main die pad portion, a linking portion, and a main current terminal portion integrally connected. The semiconductor chips 41a-41d are arranged on the main die pad portion. The main current terminal portion extends outward from the long side surface 10c. The linking portion connects the main die pad portion and the main current terminal portion. The main current terminal portion is located above the main die pad portion (in the +Z direction). In other words, there is a step between the main current terminal and the main die pad portion. An insulating plate 44 is attached to the back surface of the main die pad portion.

[0032] The multiple control lead frames 20 are provided on the long side surface 10a of the encapsulating body 10, which is opposite to the long side surface 10c from which the main current lead frame 30 extends. The multiple control lead frames 20 may extend parallel to the front and back surfaces of the encapsulating body 10 without having any steps within the encapsulating body 10. The multiple control lead frames 20 are located at the same height as the main current terminal portions of the main current lead frame 30.

[0033] Of the multiple control lead frames 20, the control lead frame 20 provided on the semiconductor chip 41a-41d side includes a control die pad on which the control ICs 42a, 42b are arranged. One end of the control lead frame 20 extends into the interior from the long side surface 10a and extends along the side of the semiconductor chips 41a-41d, and the other end extends outward from the long side surface 10a. Of the multiple control lead frames 20, the control lead frame 20 on which the electronic components 43 are respectively arranged includes a control die pad on which the electronic components 43 are respectively arranged.

[0034] The main current lead frames 30 and the control lead frames 20 are made of a material with excellent conductivity. Examples of such materials include copper, aluminum, or an alloy containing at least one of these. The thickness of the main current lead frames 30 and the control lead frames 20 is preferably 0.10 mm or more and 1.00 mm or less, and more preferably 0.20 mm or more and 0.50 mm or less. The main current lead frames 30 and the control lead frames 20 can also be plated with a material with excellent corrosion resistance. Examples of such materials include nickel, gold, or an alloy containing at least one of these.

[0035] The encapsulation main body 10 includes a thermosetting resin and an inorganic filler contained in the thermosetting resin. The thermosetting resin is primarily composed of at least one selected from the group including, for example, epoxy resin, phenolic resin, and melamine resin. Preferably, the thermosetting resin is primarily composed of epoxy resin. The inorganic filler is a highly insulating and highly thermally conductive inorganic material. The inorganic material is primarily composed of, for example, at least one selected from the group including aluminum oxide, aluminum nitride, silicon nitride, and boron nitride. Preferably, the inorganic filler is primarily composed of silicon oxide. The use of silicon oxide also functions as a mold release agent. High flame retardancy can be maintained without the addition of halogen-based, antimony-based, or metal hydroxide-based flame retardants. The inorganic filler accounts for 70 vol% to 90 vol% of the entire encapsulation raw material.

[0036] The insulating plate 44 is made of ceramics or insulating resin. Ceramics include aluminum oxide, aluminum nitride, silicon nitride, etc. Insulating resins include, for example, a paper phenol substrate, a paper epoxy substrate, a glass composite substrate, and a glass epoxy substrate.

[0037] Alternatively, the insulating plate 44 may be a sheet-like resin. In this case, the insulating plate 44 contains a thermosetting resin and an inorganic filler contained in the resin. The thermosetting resin is primarily composed of at least one selected from the group including, for example, epoxy resin, phenolic resin, melamine resin, and polyimide resin. Preferably, the thermosetting resin is primarily composed of epoxy resin. The filler is an inorganic material primarily composed of at least one selected from the group including aluminum oxide, aluminum nitride, silicon nitride, and boron nitride, which have high insulation and thermal conductivity. In this case, the insulating plate 44 is preferably primarily composed of the same thermosetting resin as the encapsulant main body 10. More preferably, the thermosetting resins of both the encapsulant main body 10 and the insulating plate 44 are primarily composed of epoxy resin.

[0038] The insulating plate 44 has, for example, a rectangular shape in a plan view. The thickness of the insulating plate 44 is 50 μm or more and 1.2 mm or less. The main die pad portions of the multiple main current lead frames 30 are arranged in a row along the longitudinal direction of the insulating plate 44 on the front surface of the insulating plate 44. The insulating plate 44 must be large enough to accommodate at least the multiple main die pad portions. Therefore, the insulating plate 44 may be wider than the case shown in FIG. 6. By covering the periphery of the main die pad portions, insulation can be more reliably ensured even if the semiconductor module 2 is deformed. The insulating plate 44 conducts heat generated by the semiconductor chips 41a to 41d from the main die pad portions to the heat sink 35, which will be described later.

[0039] The heat sink 35 has a rectangular shape in a plan view. The area of ​​the heat sink 35 is sufficiently larger than the area of ​​the insulating plate 44. The heat sink 35 is attached to the back surface of the semiconductor module 2 so as to cover the exposed insulating plate 44. The heat sink 35 dissipates heat from the insulating plate 44 to the outside of the semiconductor module 2, thereby contributing to heat dissipation of the semiconductor module 2. The thickness Tc of the heat sink 35 is approximately equal to the height Ta of the back surface support portion 12. For example, the thickness Tc and the height Ta are equal to or greater than 95 μm and equal to or less than 110 μm, e.g., 100 μm.

[0040] Next, the attachment of the semiconductor module 2 to the cooling substrate 3 in the semiconductor device 1 using the screws 4 will be described with reference to FIG. 8. FIG. 8 is a diagram showing the attachment of the semiconductor module to the cooling substrate in the first embodiment. Note that FIG. 8 shows a side view of the semiconductor device 1 shown in FIG. 1 as seen in the +X direction. Also, FIGS. 8(A) and 8(B) show the attachment of the semiconductor module 2 to the cooling substrate 3 in chronological order. Before the following attachment is performed, the semiconductor module 2, cooling substrate 3, and screws 4 described above are prepared in advance.

[0041] First, the semiconductor module 2 is placed on the front surface of the cooling substrate 3. At this time, the mounting holes 11 of the semiconductor module 2 are aligned with the fastening holes 3a of the cooling substrate 3. The rear surface support portion 12 of the semiconductor module 2 and the heat sink 35 are each substantially the same height (thickness). The rear surface support portion 12 and the heat sink 35 of the semiconductor module 2 are placed on the front surface of the cooling substrate 3, as shown in FIG. 8(A). At this time, the front surface 10e of the semiconductor module 2 is substantially horizontal to the front surface of the cooling substrate 3. In particular, since the rear surface support portions 12 are provided on both sides of the heat sink 35 in the ±Y directions, the semiconductor module 2 is stably placed on the cooling substrate 3.

[0042] Next, the semiconductor module 2 is attached to the cooling substrate 3 with the screw 4. The screw 4 is inserted into one of the mounting holes 11 of the semiconductor module 2 (the left mounting hole 11 in FIG. 8(B)) toward the cooling substrate 3. The screw 4 inserted into the mounting hole 11 of the semiconductor module 2 is pressed against the cooling substrate 3 while being rotated clockwise. The screw 4 (its tip) is fastened into the fastening hole 3a of the cooling substrate 3. In particular, the back surface of the head 4b of the screw 4 presses the periphery of the mounting hole 11 on the front surface 10e of the semiconductor module 2 toward the cooling substrate 3 (in the -Z direction). A heat sink 35 and a back surface support 12 are provided on the back surface 10f of the semiconductor module 2, sandwiching the mounting hole 11. Even when the semiconductor module 2 is pressed toward the cooling substrate 3 by the head 4b of the screw 4, the back surface support 12 prevents the other mounting hole 11 side of the semiconductor module 2 from floating. Furthermore, the rear surface support portion 12 and the heat sink 35 make it difficult for the semiconductor module 2 to shift position in the XY plane of the cooling substrate 3. This allows the semiconductor module 2 to be stably and reliably fastened to the cooling substrate 3 with the screws 4. Once fastening to one of the mounting holes 11 is complete, the other mounting hole 11 can be fastened to the fastening hole 3a of the cooling substrate 3 with the screws 4 in the same manner. In this way, the semiconductor device 1 shown in FIGS. 1 and 2 is obtained.

[0043] Here, a reference example of the semiconductor device 1 in FIGS. 1 and 2 will be described. In this reference example, the attachment of a semiconductor module 2 not provided with a back surface support portion 12 to a cooling substrate 3 using screws 4 will be described with reference to FIG. 9. FIG. 9 is a diagram showing the attachment of a semiconductor module of the reference example to a cooling substrate. Note that FIG. 9 also shows a side view of the semiconductor device 1 shown in FIG. 1 as seen from the +X direction. FIGS. 9(A) to 9(C) show the attachment of a semiconductor module 2a to a cooling substrate 3 in chronological order. The semiconductor module 2a is the semiconductor module 2 without the back surface support portion 12. The other components of the semiconductor module 2a are the same as those of the semiconductor module 2.

[0044] First, the semiconductor module 2a is placed on the front surface of the cooling substrate 3. At this time, the mounting holes 11 of the semiconductor module 2 are aligned with the fastening holes 3a of the cooling substrate 3. The back surface 10f of the semiconductor module 2a is supported by the heat sink 35, and the front surface 10e of the semiconductor module 2a and the front surface of the cooling substrate 3 are substantially parallel to each other.

[0045] Next, the semiconductor module 2a is attached to the cooling substrate 3 with a screw 4. The screw 4 is inserted into one of the attachment holes 11 of the semiconductor module 2 (the attachment hole 11 on the left side in FIG. 9) toward the cooling substrate 3 (FIG. 9(A)).

[0046] The screw 4 inserted through the mounting hole 11 of the semiconductor module 2a is rotated clockwise and pressed against the cooling substrate 3. That is, one mounting hole 11 of the semiconductor module 2a is pressed against the cooling substrate 3. As a result, the end (corner) of the heat sink 35 of the semiconductor module 2a serves as a fulcrum for the cooling substrate 3, and the other mounting hole 11 side of the semiconductor module 2a is lifted off the cooling substrate 3 (FIG. 9(B)).

[0047] The other mounting hole 11 of the semiconductor module 2a, which is in a raised state, is attached to the cooling substrate 3 with a screw 4. One mounting hole 11 of the semiconductor module 2a is fixed to the cooling substrate 3. In this state, if an attempt is made to attach the other mounting hole 11 to the cooling substrate 3 with a screw 4, the semiconductor module 2a will warp upward, as shown in FIG. 9(C). Stress is applied to the middle part of the semiconductor module 2, causing cracks in the sealing body 10 of the semiconductor module 2. Depending on the magnitude and direction of the stress, the semiconductor chips 41a to 41d and the insulating plate 44 in the semiconductor module 2a may be damaged, and the control wire 45a and the main current wire 45b may peel off.

[0048] The semiconductor device 1 includes a semiconductor module 2, screws 4, and a cooling substrate 3. The semiconductor module 2 includes semiconductor chips 41a-41d and a sealing member sealing the semiconductor chips 41a-41d to form a rectangular parallelepiped shape. The main surface of a heat sink 35 protrudes from the back surface 10f. The sealing body 10 includes a pair of mounting holes 11 that penetrate the front surface 10e and the back surface 10f, sandwiching the heat sink 35 in a plan view. The cooling substrate 3 is flat, and the heat sink 35 of the semiconductor module 2 is disposed on the cooling substrate 3. The semiconductor module 2 is attached to the cooling substrate 3 by screws 4 that are inserted into the pair of mounting holes 11 and are threadedly engaged with each other. The semiconductor module 2 includes a back surface support 12 that protrudes from the back surface 10f near the opposite side of the heat sink 35 from the pair of mounting holes 11 on the back surface 10f. When attaching the semiconductor module 2 to the cooling substrate 3 with the screws 4, the rear support portion 12 prevents the semiconductor module 2 from lifting up on the other side of the mounting hole 11, with the heat sink 35 serving as a fulcrum. The semiconductor module 2 is maintained horizontally relative to the cooling substrate 3, and the screws 4 are inserted through one of the mounting holes 11 and fastened to the fastening holes 3a of the cooling substrate 3. The fastening holes 3a of the cooling substrate 3 are then fastened by the screws 4 through the other mounting holes 11 without damaging the semiconductor module 2. This prevents a decrease in the reliability of the semiconductor module 2 and the semiconductor device 1 including the semiconductor module 2. Note that it is sufficient for the rear support portion 12 to prevent the semiconductor module 2 from lifting up significantly when attaching the semiconductor module 2 to the cooling substrate 3 with the screws 4. Therefore, the height Ta of the rear support portion 12 does not have to be the same as the thickness Tc of the heat sink 35. The height Ta may be, for example, 60% or more of the thickness Tc.

[0049] (Variation 1-1) The semiconductor device 1 of Modification 1-1 will be described with reference to FIG. 10. FIG. 10 is a side cross-sectional view of a main part of the semiconductor device of Modification 1-1 of the first embodiment. Note that FIG. 10 shows an enlarged view of the mounting hole 11 on the left side of the semiconductor device 1 of FIG. 2. The semiconductor device 1 of Modification 1-1 differs from the semiconductor module 2 of FIGS. 1 and 2 only in the shape of the back support portion 12 of the semiconductor module 2. The other configurations of the semiconductor device 1 of Modification 1-1 are the same as those of FIGS. 1 and 2.

[0050] The corners of the back surface support portion 12 of the semiconductor module 2 of modification 1-1 on the outer side (the short side surfaces 10b and 10d side; in FIG. 10, the short side surface 10d side) are rounded. When attaching such a semiconductor module 2 to the cooling substrate 3 with screws 4, the rounded back surface support portion 12 is more likely to come into contact with the front surface of the cooling substrate 3. This allows the semiconductor module 2 to be attached to the cooling substrate 3 more stably with the screws 4. Furthermore, the corners of the back surface support portion 12 may be rounded not only on the short side surfaces 10b and 10d side, but also on the long side surfaces 10a and 10c side.

[0051] (Variation 1-2) The semiconductor module 2 of Modification 1-2 will be described with reference to FIG. 11. FIG. 11 is a bottom view of the semiconductor module of Modification 1-2 of the first embodiment. The semiconductor module 2 of Modification 1-2 differs from the semiconductor module 2 of FIGS. 1 and 2 only in the shape of the back surface support portion 12 of the semiconductor module 2. Other configurations of the semiconductor device 1 of Modification 1-2 are the same as those of FIGS. 1 and 2.

[0052] A plurality of back surface supports 12, 12b, and 12c are formed on the back surface 10f of the semiconductor module 2 of Modification 1-2 along the opposing short side surfaces 10b and 10d. The back surface supports 12 are formed in regions adjacent to the short side surfaces 10b and 10d of the mounting hole 11 on the back surface 10f of the semiconductor module 2. The back surface supports 12b and 12c are formed in regions adjacent to the short side surfaces 10b and 10d of the mounting hole 11 on the back surface 10f of the semiconductor module 2, respectively. That is, the back surface supports 12b and 12c are formed next to the back surface supports 12 along the short side surfaces 10b and 10d.

[0053] 1 and 2, the back surface support portions 12, 12b, and 12c are discontinuous, yet provide the same effect as in the case of FIGS. 1 and 2. The back surface support portions 12 in Modification 1-2 must be formed at least in the region adjacent to the mounting hole 11 on the short side surfaces 10b and 10d side. That is, the back surface support portions 12 are formed so as to be aligned with the mounting hole 11. The length (in the ±X directions) of the back surface support portions 12 is preferably equal to or longer than the length (in the ±X directions) of the mounting hole 11. Furthermore, it is sufficient that the back surface support portions 12 are formed at least in the portion adjacent to the mounting hole 11 on the short side surfaces 10b and 10d side. Therefore, the back surface support portions 12 may include, for example, a portion surrounding the mounting hole 11. The number of back surface support portions 12b and 12c is not limited to one each, and may be two or more.

[0054] (Variation 1-3) The semiconductor module 2 of Modification 1-3 will be described with reference to FIG. 12. FIG. 12 is a bottom view of the semiconductor module of Modification 1-3 of the first embodiment. The semiconductor module 2 of Modification 1-3 further includes a back surface support portion 12 formed on the long side surfaces 10a, 10c of the back surface 10f of the semiconductor module 2, as compared to the semiconductor module 2 of FIGS. 1 and 2. The other configurations of the semiconductor module 2 of Modification 1-3 are the same as those of FIGS. 1 and 2.

[0055] In the semiconductor module 2 of the modified example 1-3, the back surface support portions 12 are formed on the back surface 10f not only on the short side surfaces 10b and 10d but also on the long side surfaces 10a and 10c. Therefore, the semiconductor module 2 of the modified example 1-3 can be fastened with the screws 4 more stably than in the case of FIGS. 1 and 2.

[0056] The rear surface support portion 12 formed along the long side surfaces 10a, 10c and the short side surfaces 10b, 10d of the rear surface 10f of the semiconductor module 2 in Modification 1-3 may be discontinuous, as in Modification 1-2.

[0057] [Second embodiment] A semiconductor module included in a semiconductor device according to a second embodiment will be described with reference to FIGS. 13 to 15. FIG. 13 is a plan view of the semiconductor module according to the second embodiment, and FIG. 14 is a bottom view of the semiconductor module according to the second embodiment. FIG. 15 is a side view of the semiconductor module according to the second embodiment. FIG. 15 corresponds to FIG. 5. That is, FIG. 15(A) shows a side view of the semiconductor module 2 of FIG. 13 as seen from the -Y direction, and FIG. 15(B) shows a side view of the semiconductor module of FIG. 13 as seen from the +X direction. The semiconductor module 2 of the second embodiment in FIGS. 1 and 2 is applied to the semiconductor device according to the second embodiment. The cooling substrate 3 is the same as that of the first embodiment.

[0058] The semiconductor module 2 of the second embodiment is formed by removing the back surface support portion 12 from the semiconductor module 2 of the first embodiment and forming a front surface support portion 12a. The front surface support portion 12a is formed protruding from the front surface 10e of the semiconductor module 2 near the opposing sides of the pair of mounting holes 11 on the front surface 10e.

[0059] That is, in a plan view, the front surface support portion 12a is formed to surround the periphery of the mounting hole 11, except for the short side faces 10b and 10d of the mounting hole 11. As shown in FIG. 15, the front surface support portion 12a includes an inclined surface in a side view. This inclined surface is inclined so that its height relative to the front surface 10e of the semiconductor module 2 increases with increasing distance from the short side faces 10b and 10d. The highest point of the front surface support portion 12a is point P (see FIG. 17). In this way, the front surface support portion 12a is formed on the front surface 10e of the semiconductor module 2 in an inclined manner (in a bank shape) along the outer periphery of the mounting hole 11 (opposite the short side faces 10b and 10d).

[0060] Furthermore, the semiconductor module 2 of the second embodiment does not have a back surface support portion 12 formed on the back surface 10f. Mounting holes 11 are formed on the short side surfaces 10b and 10d of the back surface 10f of the semiconductor module 2, as shown in Fig. 14. A heat sink 35 is formed between the pair of mounting holes 11 on the back surface 10f of the semiconductor module 2.

[0061] As in the first embodiment, the semiconductor module 2 of the second embodiment is fabricated by setting three semiconductor chips 41a, 41b, 41c, 41d, the control lead frame 20, the main current lead frame 30, the control ICs 42a and 42b, the electronic component 43, and the insulating plate 44 in a predetermined mold. This mold includes a portion corresponding to the front surface support portion 12a. The mold is then filled with the encapsulating material of the encapsulating main body 10. After the encapsulating material solidifies, the mold is removed to obtain the semiconductor module 2 on which the front surface support portion 12a is formed. Therefore, the encapsulating main body 10 and the front surface support portion 12a may be made of the same material.

[0062] Next, the attachment of such a semiconductor module 2 to the cooling substrate 3 using screws 4 will be described with reference to Figs. 16 and 17. Figs. 16 and 17 are diagrams showing the attachment of a semiconductor module to a cooling substrate according to a second embodiment. Figs. 16(A) to 16(C) show the attachment of the semiconductor module 2 to the cooling substrate 3 in chronological order. Fig. 17 is an enlarged view of the area around the screws 4, with Fig. 17(A) showing the moment the screws 4 are attached and Fig. 17(B) showing the moment the screws 4 are fastened. Before the following attachment is performed, the semiconductor module 2, cooling substrate 3, and screws 4 described above are prepared in advance.

[0063] First, the semiconductor module 2 is placed on the front surface of the cooling substrate 3. At this time, the mounting holes 11 of the semiconductor module 2 are aligned with the fastening holes 3a of the cooling substrate 3. The heat sink 35 of the semiconductor module 2 is placed on the front surface of the cooling substrate 3. At this time, the front surface 10e of the semiconductor module 2 is substantially horizontal to the front surface of the cooling substrate 3.

[0064] Next, the semiconductor module 2 is attached to the cooling substrate 3 with the screw 4. The screw 4 is inserted into one of the attachment holes 11 of the semiconductor module 2 (the attachment hole 11 on the left side in FIG. 16(A)) toward the cooling substrate 3. The screw 4 inserted into the attachment hole 11 of the semiconductor module 2 is rotated clockwise and pressed against the cooling substrate 3 until the head 4b of the screw 4 abuts against the front surface support portion 12a (see FIG. 16(A)).

[0065] Here, the screw 4, the front surface support portion 12a, and the heat sink 35 will be described in detail. The diameter of the head 4b of the screw 4 (the length from the shank 4a to the outer periphery) is R. The diameter R is 3.0 mm or more and 3.5 mm or less, for example, approximately 3.25 mm. As shown in FIG. 17(A), the position of a line extending vertically from the end of the heat sink 35 on the mounting hole 11 side to the cooling substrate 3 is designated as E1, the position of a line extending vertically from the inner end of the front surface support portion 12a to the cooling substrate 3 is designated as E2, and the position of a line extending vertically from the outer periphery of the head 4b to the cooling substrate 3 is designated as E3. The position E1 of the end of the heat sink 35 is located closer to the shank 4a than the position E3 of the head 4b.

[0066] The vertex of the front surface support portion 12a is defined as point P. In this case, the distance between position E1 and position E3 is W2 (<radius R). The distance between position E1 and position E2 is W1 (<radius R). As will be described later, point P is preferably located between position E3 and position E1. The distance W1 is 4.0 mm or more and 4.5 mm or less, for example, approximately 4.25 mm. The distance W2 is 2.5 mm or more and 3.0 mm or less, for example, approximately 2.75 mm.

[0067] 16(B), the end (corner) of the heat sink 35 acts as a fulcrum for the front surface of the cooling substrate 3, and the head 4b of the screw 4 presses the mounting hole 11 of the semiconductor module 2 against the cooling substrate 3. The other mounting hole 11 side of the semiconductor module 2 rises up from the cooling substrate 3.

[0068] Furthermore, when the screw 4 is turned and pressed against the cooling substrate 3, the back surface of the head 4b (back surface of the head) presses against point P on the front surface support portion 12a in the direction of the dashed arrow, as shown in FIG. 17(B). When the semiconductor module 2 receives this pressing force, it warps downward, and the back surface of the head 4b of the screw 4 abuts against the slope of the front surface support portion 12a. The other mounting hole 11 of the semiconductor module 2 can also be fastened to the cooling substrate 3 using the screw 4 in a similar manner. As a result, the semiconductor device 1 shown in FIG. 16(C) is obtained. At this time, the semiconductor module 2 warps downward, but the warping is such that it does not cause damage to the semiconductor module 2. In the second embodiment, too, the semiconductor module 2 can be attached to the cooling substrate 3 with the screw 4 without causing damage to the semiconductor module 2.

[0069] The semiconductor device 1 includes a semiconductor module 2, screws 4, and a cooling substrate 3. The semiconductor module 2 includes semiconductor chips 41a-41d and a sealing body 10 having a rectangular parallelepiped shape with the semiconductor chips 41a-41d sealed with a sealing member, a heat sink 35 with a main surface protruding from a back surface 10f, and a pair of mounting holes 11 penetrating the front surface 10e and the back surface 10f, sandwiching the heat sink 35 in a plan view. The cooling substrate 3 has a flat plate shape, on which the heat sink 35 of the semiconductor module 2 is disposed, and screws 4 are inserted into the pair of mounting holes 11 and threadedly engaged to mount the semiconductor module 2. The semiconductor module 2 includes front surface support portions 12a protruding from the front surface 10e near the opposing sides of the pair of mounting holes 11 on the front surface 10e. When the semiconductor module 2 is attached to the cooling substrate 3 with the screws 4, the front surface support portion 12a causes the semiconductor module 2 to bend slightly downward, preventing it from floating up on the other mounting hole 11 side. The semiconductor module 2 is fastened to the fastening hole 3a of the cooling substrate 3 with the screws 4 at the other mounting hole 11 without being damaged. This makes it possible to suppress a decrease in the reliability of the semiconductor module 2 and the semiconductor device 1 including the semiconductor module 2.

[0070] To mount the semiconductor module 2 on the cooling substrate 3 with the screws 4 in such a manner that it is slightly warped downward and convex, first, as shown in FIG. 17, it is necessary to ensure that the corner (end) (position E1) of the heat sink 35 does not serve as a fulcrum. For this reason, point P of the front surface support portion 12a must be located outside position E1. In other words, it is sufficient that the inclined surface of the front surface support portion 12a abuts against the back surface of the head portion 4b. By positioning the inclined surface of the front surface support portion 12a between positions E1 and E3, it can be pressed in the direction of the dashed arrow in FIG. 17(B). This allows the semiconductor module 2 to be reliably fastened to the cooling substrate 3 with the screws 4 in a manner that is warped downward and convex.

[0071] Furthermore, the front surface support portion 12a may be a simple protrusion without including an inclined surface. In this case, the protruding front surface support portion 12a can press in the same direction as above as long as it is located between positions E1 and E3. In this case, it is preferable that the front surface support portion 12a is located between positions E1 and E3 and as close to position E3 as possible. [Explanation of symbols]

[0072] 1. Semiconductor device 2. Semiconductor Module 3 Cooling substrate 3a Fastening hole 4 screws 4a Shaft 4b head 10. Sealing body 10a,10c long side 10b,10d short side 10e Front 10f back side 11 Mounting holes 12,12b,12c Back support part 12a Front support part 20 Control lead frame 30 Main current lead frame 35 Heat sink 41a, 41b, 41c, 41d Semiconductor chips 42a, 42b Control IC 43 Electronic Components 44 Insulating plate 45a control wire 45b Main current wire

Claims

1. A semiconductor chip; a sealing body portion in which the semiconductor chip is sealed with a sealing member to form a rectangular parallelepiped shape, a main surface of a heat sink protruding from a back surface, and a pair of mounting holes penetrating the front surface and the back surface are formed, sandwiching the heat sink therebetween in a plan view; Including, a rear surface support portion protruding from the rear surface near a side of the rear surface opposite the heat sink with respect to the pair of mounting holes, or a front surface support portion protruding from the front surface near sides of the front surface where the pair of mounting holes face each other, a width of the rear surface support portion in an extension direction of the long sides of the sealing main body portion corresponds to a length from the pair of mounting holes to opposing short sides of the sealing main body portion, The front surface support portions each have an inclined surface whose height relative to the front surface increases with increasing distance from the opposing short sides. Semiconductor module.

2. The pair of mounting holes are formed on center lines passing through the centers of the opposing short sides in a plan view, The semiconductor module according to claim 1 .

3. The rear surface support portions have a length corresponding to at least a width parallel to the opposing short sides of the pair of mounting holes, and are formed to face the pair of mounting holes, respectively. The semiconductor module according to claim 2 .

4. The rear surface support portions are formed along the opposing short sides, The semiconductor module according to claim 3 .

5. The rear surface support portion is formed in plurality along each of the opposing short sides. The semiconductor module according to claim 4 .

6. The rear surface support portion is formed continuously along the opposing short sides from one long side to the other long side. The semiconductor module according to claim 4 .

7. The height of the rear surface support portion is the same as the height from the rear surface to the main surface of the heat sink. The semiconductor module according to claim 1 .

8. The outer corners of the opposing short sides of the back surface support portion are rounded. The semiconductor module according to claim 1 .

9. When the front surface support portion is formed, The sealing main body is warped downward in a convex shape in a side view with the heat sink side facing downward. The semiconductor module according to claim 2 .

10. the sealing body has a flat plate shape and is disposed on the heat sink, and a cooling substrate is attached to the sealing body by threading screws inserted into the pair of mounting holes. The semiconductor module according to claim 9 .

11. the screw includes a cylindrical shank portion that is inserted into the pair of mounting holes and a head portion that has a diameter longer than the shank portion and presses the pair of mounting holes toward the cooling substrate when the shank portion is screwed into the head portion; In a side view, both end portions of the heat sink are located closer to the shaft portion than outer peripheries of the heads of the screws inserted into the pair of mounting holes. The semiconductor module according to claim 10.

12. the front surface support portion supports, in a side view, a portion of the back surface of the head portion inserted into the pair of mounting holes, between a position of a straight line extending perpendicularly to the cooling substrate at an end of the heat sink and the outer periphery. The semiconductor module according to claim 11 .

13. In a side view, the apex of the inclined surface of the front surface support portion is located between the position of a straight line extending perpendicularly to the cooling substrate and the outer periphery on the back surface of the head portion of the head portion inserted into the pair of mounting holes. The semiconductor module according to claim 12.

14. The back surface support portion and the front surface support portion are made of the same material as the sealing member. The semiconductor module according to claim 1 .

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