Method for manufacturing semiconductor module

Abstract

According to the present invention, a screw is securely fastened to a case.　A molding space (61a) is composed of: a molding inner surface (60d2) which defines an outer frame and a housing region; a molding outer surface (60d1) which is provided on the outer side of the molding inner surface (60d2), and in which an injection port (60da) that is in communication with the molding space (61a) is formed so as to be inwardly separated from each end in a plan view; and a molding bottom surface (60d3) which connects the molding inner surface (60d2) and the molding outer surface (60d1) to each other, and is in contact with the lower surface of the outer frame. A mold pin part (62) is disposed at a corner part of the molding space (61a) in a plan view so as to be perpendicular to the molding bottom surface (60d3). During an injection step, a rod-shaped second mold component (64) is disposed in parallel to the mold pin part (62) at a position between the mold pin part (62) and the injection port (60da) in the molding space (61a) in a plan view, the position being closer to the molding inner surface (60d2) than to the molding outer surface (60d1).

Description

Semiconductor module manufacturing method

[0001] The present invention relates to a method for manufacturing a semiconductor module.

[0002] The semiconductor module includes a case that houses a semiconductor element and a printed circuit board that is attached to the top surface of the case with self-tapping screws. The case is made of resin and has mounting holes for the self-tapping screws that pass through the printed circuit board. The mounting holes are cylindrical in shape with semi-spherical tips. This prevents cracks and voids from occurring during resin molding of the case (see, for example, Patent Document 1).

[0003] The semiconductor device also includes an insulating substrate on which a semiconductor chip is disposed, a heat sink on which the insulating substrate is disposed, and a resin case including screw holes to be engaged with tapping screws inserted into through holes in the heat sink. A high-voltage resin is filled into the gaps in the screw holes of the resin case into which the tapping screws are engaged, thereby improving the discharge voltage resistance and dielectric breakdown resistance (see, for example, Patent Document 2).

[0004] International Publication No. 2021 / 024636 Japanese Patent Application Laid-Open No. 2006-032392

[0005] The present invention has been made in view of the above points, and has as its object to provide a method for manufacturing a semiconductor module including a case in which screws are securely fastened.

[0006] According to one aspect of the present invention, a molding die having a rectangular shape in a plan view, an outer frame surrounding all four sides of a storage area extending from a lid portion to a bottom surface, a cavity corresponding to the shape of a case having cylindrical fastening portions formed at corners of an upper surface of the outer frame to be fastened with screws, an injection port formed to communicate with the cavity from the outside, and a first mold part including a rod-shaped mold pin portion corresponding to the fastening portion; and a molding material; and an injection step of providing the mold pin portion in the cavity of the first mold part and injecting the molding material from the injection port into the cavity, wherein the cavity of the first mold part includes a molding space in which the outer frame is molded, and a molding die that is configured by a molding inner surface that defines the outer frame and the storage area, a molding outer surface that is provided outside the molding inner surface and has injection ports that lead to the molding space formed at a distance inward from each end in a planar view, and a molding bottom surface that connects the molding inner surface and the molding outer surface and is in contact with the underside of the outer frame, wherein the mold pin portion is arranged at a corner of the molding space in a planar view perpendicular to the molding bottom surface, and the molding die further includes, during the injection step, a rod-shaped second mold part that is arranged in the molding space between the mold pin portion and the injection port in a planar view and parallel to the mold pin portion at a location that is closer to the molding inner surface than the molding outer surface.

[0007] According to one aspect of the present invention, a molding die having a rectangular shape in a plan view, an outer frame surrounding all four sides of a storage area extending from a lid portion to a bottom surface, a cavity corresponding to the shape of a case having cylindrical fastening portions formed at corners of an upper surface of the outer frame to be fastened with screws, an injection port formed to communicate with the cavity from the outside, and a first mold part including a rod-shaped mold pin portion corresponding to the fastening portion; and a molding material; and an injection step of providing the mold pin portion in the cavity of the first mold part and injecting the molding material from the injection port toward the cavity, wherein the cavity of the first mold part is a molding outer surface provided outside the molding inner surface, the injection ports leading to the molding space being formed spaced apart inward from each end in a plan view; and a molding bottom surface connecting the molding inner surface and the molding outer surface and in contact with the lower surface of the outer frame; wherein the mold pin portions are arranged at corners of the molding space perpendicular to the molding bottom surface in a plan view; and wherein the injection ports are formed on the molding outer surface at a position not greater than 30% from the upper surface of the outer frame with respect to the height from the upper surface to the lower surface.

[0008] According to the disclosed technology, it is possible to provide a method for manufacturing a semiconductor module that can reliably fasten screws to a case, prevent the screws from coming loose during operation, and improve reliability.

[0009] The above and other objects, features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings illustrating preferred embodiments of the present invention.

[0010] 1 is a perspective view of a semiconductor module according to a first embodiment; a cross-sectional view of the semiconductor module according to the first embodiment; a back view of the semiconductor module according to the first embodiment; a plan view of a semiconductor unit included in the semiconductor module according to the first embodiment; a first cross-sectional view of a semiconductor module to which a printed circuit board according to the first embodiment is attached; a second cross-sectional view of a semiconductor module to which a printed circuit board according to the first embodiment is attached; an enlarged cross-sectional view of a semiconductor module to which a printed circuit board according to the first embodiment is attached; a flowchart showing a method for manufacturing a case included in the semiconductor module according to the first embodiment; a plan view of a molding apparatus according to the first embodiment; a first cross-sectional view of a molding die included in the molding apparatus according to the first embodiment; a second cross-sectional view of a molding die included in the molding apparatus according to the first embodiment; a third cross-sectional view of a molding die included in the molding apparatus according to the first embodiment; a first cross-sectional view showing an injection step included in a method for manufacturing a case according to a comparative example; an enlarged cross-sectional view of a case according to the comparative example; a perspective view of a semiconductor module according to a second embodiment; a second cross-sectional view of a semiconductor module to which a printed circuit board according to the second embodiment is attached; an enlarged cross-sectional view of a semiconductor module to which a printed circuit board according to the second embodiment is attached; a plan view of a molding apparatus according to the second embodiment. 10A and 10B are second and third cross-sectional views of the molding die included in the molding apparatus of the second embodiment, respectively;

[0011] Hereinafter, embodiments will be described with reference to the drawings. In the following description, the terms "front surface" and "top surface" refer to the X-Y plane facing upward (+Z direction) in the semiconductor module shown in the drawings. Similarly, "top" refers to the upward (+Z direction) direction in the semiconductor module shown in the drawings. The terms "back surface" and "bottom surface" refer to the X-Y plane facing downward (-Z direction) in the semiconductor module shown in the drawings. Similarly, "bottom" refers to the downward (-Z direction) direction in the semiconductor module shown in the drawings. Similar orientations will be used in other drawings as necessary. The terms "front surface," "top surface," "top," "back surface," "bottom surface," "bottom," 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, "top" and "bottom" do not necessarily refer to the vertical direction relative to the ground. In other words, the "top" and "bottom" 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. Furthermore, "substantially the same" may be within a range of ±10%. Furthermore, "perpendicular" and "parallel" may be within a range of ±10°. "Up" and "down" do not necessarily mean the vertical direction relative to the ground. In other words, the directions of "up" and "down" are not limited to the direction of gravity. Furthermore, in the following description, "main component" refers to a component containing 80 vol% or more.

[0012] [First Embodiment] A semiconductor module according to a first embodiment will be described with reference to FIGS. 1 to 4. FIG. 1 is a perspective view of the semiconductor module according to the first embodiment, and FIG. 2 is a cross-sectional view of the semiconductor module according to the first embodiment. FIG. 3 is a rear view of the semiconductor module according to the first embodiment. FIG. 4 is a plan view of a semiconductor unit included in the semiconductor module according to the first embodiment. Note that FIG. 2 is a cross-sectional view taken along the dashed dotted line Y1-Y1 in FIG. 1. In addition, in this embodiment, the plurality of conductive patterns 22, the plurality of semiconductor chips 30a, 30b, the plurality of contact components 31, the plurality of external connection terminals 32, and the plurality of wires 33 will be described without distinction and will be assigned the same reference numerals.

[0013] The semiconductor module 1 includes a case 10 and a semiconductor unit 2 housed in the case 10. A plurality of external connection terminals 32 included in the semiconductor unit 2 extend to the outside from the front surface of the case 10. The inside of the case 10 is sealed with a sealing member 35.

[0014] The case 10 has an outer frame 11 that surrounds the components of the semiconductor module 1 described later, an attachment portion 14 that is integrally attached to the outer frame 11, and a lid portion 12 that covers the top of the outer frame 11 and is integrally attached to the outer frame 11.

[0015] The outer frame 11 has a generally rectangular box shape in plan view and includes continuous annular upper and lower surfaces 11e and 11f. The upper and lower surfaces 11e and 11f are generally parallel and generally smooth. The outer frame 11 includes side walls 11a to 11d that surround the storage area 15 (see FIG. 2) on all four sides. The side walls 11a to 11d are integrally connected to form a continuous annular shape in plan view. The upper and lower surfaces 11e and 11f are formed by the integrally connected side walls 11a to 11d. The side walls 11a and 11c correspond to the short sides of the outer frame 11 and are parallel to the short-side direction (±Y direction) of the outer frame 11. The side walls 11b and 11d correspond to the long sides of the outer frame 11 and are parallel to the longitudinal direction (±X direction) of the outer frame 11.

[0016] The side wall 11b further includes outermost surfaces 11b1 and 11b5, an outer surface 11b3, and inclined surfaces 11b2 and 11b4. The outermost surfaces 11b1 and 11b5 are located further outward (in the +Y direction) than the outer surface 11b3. That is, the outermost surfaces 11b1 and 11b5 of the side wall 11b are thicker than the outer surface 11b3. This thicker portion (fastening portion) includes a fastening portion 13, which will be described later. The outermost surfaces 11b1 and 11b5 also include a gate mark S, not shown. The gate mark S will be described later.

[0017] The inclined surfaces 11b2 and 11b4 are provided along the longitudinal direction (±X direction) in regions that protrude from the outer surface 11b3 of the outermost surfaces 11b1 and 11b5. In a side view, the inclined surfaces 11b2 and 11b4 are inclined downward from the upper surface 11e on the side walls 11c and 11a of the outer frame 11, which will be described later, toward the center of the side wall 11b. The fastening portion is the portion surrounded by the outermost surfaces 11b1 and 11b5, the inclined surfaces 11b2 and 11b4, the upper surface 11e, and the lower surface 11f.

[0018] The side wall 11d also includes outermost surfaces 11d1 and 11d5, an outer surface 11d3, and inclined surfaces 11d2 and 11d4. The outermost surfaces 11d1 and 11d5 are located further outward (in the -Y direction) than the outer surface 11d3. That is, the outermost surfaces 11d1 and 11d5 of the side wall 11d are thicker than the outer surface 11d3. This thicker portion (fastening portion) includes the fastening portion 13, which will be described later. The outermost surfaces 11d1 and 11d5 also include a gate mark S, which will be described later.

[0019] The thicknesses of the side walls 11a and 11c are equal to or thinner than the thicknesses of the outer surfaces 11b3 and 11d3 of the side walls 11b and 11d. That is, the thicknesses of the side walls 11a and 11c are thinner than the thicknesses of the outermost surfaces 11b1 and 11b5 and the outermost surfaces 11d1 and 11d5 of the side walls 11b and 11d.

[0020] The inclined surfaces 11d2 and 11d4 are provided along the longitudinal direction (±X direction) in a region protruding from the outer surface 11d3 of the outermost surfaces 11d1 and 11d5. In a side view, the inclined surfaces 11d2 and 11d4 are inclined downward from the upper surface 11e on the side walls 11c and 11a of the outer frame 11 (described later) toward the center of the side wall 11d. The fastening portion is the portion surrounded by the outermost surfaces 11d1 and 11d5, the inclined surfaces 11d2 and 11d4, the upper surface 11e, and the lower surface 11f.

[0021] Furthermore, in plan view, the upper surfaces 11e of the side walls 11b and 11d are formed on the side walls 11a and 11c sides together with the fastening portions 13. The fastening portions 13 and the columnar marks 16 will be described in detail later.

[0022] The mounting portions 14 are integrally formed in the central portions of the side walls 11b and 11d. The mounting portions 14 are generally flat and are formed to be flush with the lower surface 11f of the outer frame 11 (side walls 11b and 11d). Mounting holes 14a may be formed in the mounting portions 14. Such mounting portions 14 may be made of, for example, metal. The semiconductor module 1 is installed in a predetermined installation area, and screws are inserted through the mounting holes 14a of the mounting portions 14 to fasten them to the installation position. This allows the semiconductor module 1 to be fixed to the installation area.

[0023] The lid portion 12 covers the upper portion of the storage area 15 and is integrally connected to each of the side walls 11a to 11d. The lid portion 12 may not be flush with the upper surface 11e of the side walls 11a to 11d, but may be connected below the upper surface 11e. The lid portion 12 may have terminal holes 12a formed in a grid pattern. The multiple external connection terminals 32 are inserted through the terminal holes 12a of the lid portion 12 and extend vertically upward (in the +Z direction) from the outer frame 11 relative to the lid portion 12. The lid portion 12 may also have an opening separate from the terminal holes 12a. This opening may have a larger diameter than the terminal holes 12a. A sealing member 35 may be filled into the case 10 through this opening.

[0024] The case 10 (excluding the mounting portion 14) may be made of a thermoplastic resin. Examples of such resins include polyphenylene sulfide resin, polybutylene terephthalate resin, polybutylene succinate resin, polyamide resin, and acrylonitrile butadiene styrene resin. The case 10, including the mounting portion 14, is formed by injection molding using a thermoplastic resin.

[0025] The semiconductor unit 2 includes an insulating circuit board 20, semiconductor chips 30a and 30b, and a plurality of external connection terminals 32. The insulating circuit board 20 includes an insulating plate 21, a plurality of conductive patterns 22, and a metal plate 23. The insulating plate 21 and the metal plate 23 are rectangular in plan view. The corners of the insulating plate 21 and the metal plate 23 may be round-chamfered or C-chamfered. The size of the metal plate 23 is smaller than the size of the insulating plate 21 in plan view, and is formed inside the insulating plate 21.

[0026] The insulating plate 21 is made of a material that has insulating properties and excellent thermal conductivity. Such an insulating plate 21 may be made of ceramics. Examples of ceramics include aluminum oxide, aluminum nitride, and silicon nitride.

[0027] The plurality of conductive patterns 22 are formed on the front surface of the insulating plate 21. The plurality of conductive patterns 22 are made of a metal with excellent conductivity. Such a metal is, for example, copper, aluminum, or an alloy containing at least one of these as a main component. The surfaces of the plurality of conductive patterns 22 may be plated. In this case, the plating material used is, for example, nickel, a nickel-phosphorus alloy, or a nickel-boron alloy. The plated plurality of conductive patterns 22 has improved corrosion resistance.

[0028] The plurality of conductive patterns 22 are formed on the front surface of the insulating plate 21 as follows. A metal plate is formed on the front surface of the insulating plate 21, and then a process such as etching is performed on this metal plate to obtain the plurality of conductive patterns 22 of a predetermined shape. Alternatively, the plurality of conductive patterns 22 may be cut out in advance from a metal plate and pressure-bonded to the front surface of the insulating plate 21. Note that the plurality of conductive patterns 22 is one example. The number, shape, size, and position of the conductive patterns may be selected appropriately as needed.

[0029] The metal plate 23 is formed on the back surface of the insulating plate 21. The metal plate 23 has a rectangular shape. The area of ​​the metal plate 23 in a plan view is smaller than that of the insulating plate 21 and larger than the area of ​​the region in which the multiple conductive patterns 22 are formed. The corners of the metal plate 23 may be round-chamfered or C-chamfered. The metal plate 23 is smaller than the size of the insulating plate 21 and is formed on the entire surface of the insulating plate 21 except for the edges. The metal plate 23 is primarily composed of a metal with excellent thermal conductivity. The metal may be, for example, copper, aluminum, or an alloy containing at least one of these. The surface of the metal plate 23 may be plated. Examples of plating materials used in this case include nickel, a nickel-phosphorus alloy, and a nickel-boron alloy. The plated metal plate 23 has improved corrosion resistance.

[0030] Examples of the insulating circuit board 20 having such a configuration include a DCB (Direct Copper Bonding) board and an AMB (Active Metal Brazed) board. A cooler (not shown) may be attached to the back surface of the insulating circuit board 20 (semiconductor module 1) via a bonding material. This improves the heat dissipation performance of the semiconductor module 1. The cooler may be made of, for example, aluminum, iron, silver, copper, or an alloy containing at least one of these materials, which have excellent thermal conductivity. Examples of the cooler include a heat sink and a water-cooled cooling device. The heat sink may have multiple fins. Examples of the bonding material include a brazing material and a thermal interface material (TIM). The brazing material may be primarily composed of at least one of an aluminum alloy, a titanium alloy, a magnesium alloy, a zirconium alloy, and a silicon alloy. TIM includes a variety of generic names, such as thermally conductive grease, elastomer sheet, RTV (Room Temperature Vulcanization) rubber, gel, and phase change material.

[0031] The semiconductor chips 30a and 30b may be made primarily of silicon, for example. The semiconductor chip 30a is a switching element. Examples of switching elements include an integrated gate bipolar transistor (IGBT) and a metal oxide semiconductor field effect transistor (power MOSFET). If the semiconductor chip 30a is an IGBT, it has a collector electrode as a main electrode on its back surface, and a gate electrode as a control electrode and an emitter electrode as main electrodes on its front surface. If the semiconductor chip 30a is a power MOSFET, it has a drain electrode as a main electrode on its back surface, and a gate electrode as a control electrode and a source electrode as main electrodes on its front surface.

[0032] The semiconductor chip 30b is a diode element. The diode element may be, for example, a Schottky Barrier Diode (SBD) or a P-intrinsic-N (PiN) diode as a Free Wheeling Diode (FWD). The semiconductor chip 30b has a cathode electrode as a main electrode on its back surface and an anode electrode as a main electrode on its front surface. The back surfaces of the semiconductor chips 30a and 30b are bonded to a predetermined conductive pattern 22 by a bonding member (not shown).

[0033] Alternatively, the semiconductor chips 30a and 30b may be replaced by a semiconductor chip including a silicon RC (Reverse-Conducting)-IGBT. The RC-IGBT combines the functions of an IGBT, which is a switching element, and an FWD, which is a diode element. Such a semiconductor chip has a collector electrode as a main electrode on the back surface, and a gate electrode, which is a control electrode, and an emitter electrode, which are also main electrodes, on the front surface.

[0034] Alternatively, instead of the RC-IGBT, a semiconductor chip including a power MOSFET made of silicon carbide may be used. The body diode of the power MOSFET may perform the same function as the FWD of the RC-IGBT. Such a semiconductor chip has a collector electrode as a main electrode on the back surface, and a gate electrode as a control electrode and an emitter electrode as a main electrode on the front surface.

[0035] The bonding material for the conductive patterns 22 of the semiconductor chips 30a, 30b may be, for example, solder or a metal sintered body. Lead-free solder is used as the solder. Lead-free solder mainly contains at least one of the following alloys: a tin-silver-copper alloy, a tin-zinc-bismuth alloy, a tin-copper alloy, and a tin-silver-indium-bismuth alloy. Furthermore, the solder may contain additives. Examples of additives include nickel, germanium, cobalt, or silicon. The addition of additives to the solder improves its wettability, gloss, and bonding strength, thereby improving reliability. The metal sintered body mainly contains, for example, silver or a silver alloy.

[0036] In order for the semiconductor module 1 to achieve a desired function, an electronic component 30c may be disposed on the conductive pattern 22. The electronic component 30c may be, for example, a thermistor or a current sensor, depending on the function. The electronic component 30c may also be bonded to the conductive pattern 22 using the above-described bonding material.

[0037] The external connection terminals 32 are electrically connected to the conductive patterns 22 via contact elements 31. The contact elements 31 include a main body with a cylindrical through-hole formed therein and flanges provided at the open ends of the main body. One open end of the contact element 31 is joined via a joining member to predetermined positions of the plurality of conductive patterns 22 provided on the front surface of the insulating circuit board 20. The external connection terminals 32 are press-fitted into the other open end of the contact element 31. The contact element 31 is made of a metal with excellent conductivity. Examples of such metals include copper, aluminum, silver, nickel, or an alloy containing at least one of these as a main component. The surface of the contact element 31 may be plated to improve corrosion resistance. Examples of plating materials used in this case include nickel, a nickel-phosphorus alloy, and a nickel-boron alloy.

[0038] The external connection terminal 32 is a press-fit terminal having a rod-shaped main body, tapered tips formed at both ends of the main body, and a thickened portion formed above the main body. The lower tip of the external connection terminal 32 is press-fitted into the contact component 31. The upper tip is later press-fitted into the printed circuit board 40 (see FIG. 5). The main body is, for example, prismatic. The external connection terminal 32 is also made of a metal with excellent conductivity. Such metals include, for example, copper, aluminum, nickel, or an alloy containing at least one of these as a main component. The surface of the external connection terminal 32 may be plated to improve corrosion resistance. Examples of plating materials used in this case include nickel, a nickel-phosphorus alloy, and a nickel-boron alloy. Note that the external connection terminal 32 is not limited to a press-fit terminal, and may also be a terminal with a substantially straight main body without a thickened portion.

[0039] Furthermore, the external connection terminals 32 may be joined to the insulating circuit board 20 without using the contact parts 31. For example, the external connection terminals 32 may be joined directly to the conductive patterns 22 of the insulating circuit board 20 by ultrasonic bonding or the like. Furthermore, the external connection terminals 32 may be joined to the conductive patterns 22 of the insulating circuit board 20 by using solder or brazing material, for example.

[0040] In the semiconductor unit 2, a power conversion circuit is formed by connecting the semiconductor chips 30 a and 30 b, connecting the semiconductor chips 30 a and 30 b and the conductive patterns 22, and connecting the plurality of conductive patterns 22 together with wires 33. The wires 33 are mainly composed of, for example, gold, silver, copper, aluminum, or an alloy containing at least one of these metals.

[0041] The sealing member 35 includes a thermosetting resin and a filler contained in the thermosetting resin. The thermosetting resin is, for example, an epoxy resin, a phenolic resin, or a maleimide resin. The filler is, for example, silicon oxide, aluminum oxide, boron nitride, or aluminum nitride.

[0042] In the semiconductor module 1, the case 10 covers the components arranged on the insulating circuit board 20 and is fixed to the insulating circuit board 20 (insulating plate 21) with adhesive 34 applied along the outer periphery of the insulating circuit board 20. A step 11g is formed along the opening 11h on the inside of the lower surface 11f of the outer frame 11 of the case 10. The cross section of the step 11g is L-shaped. The outer periphery of the insulating plate 21 of the insulating circuit board 20 is fitted into this step 11g, and the insulating circuit board 20 covers the opening 11h of the storage area 15 of the case 10 (outer frame 11).

[0043] The sealing member 35 is filled in the storage area 15 of the case 10 and seals the front surface of the insulating circuit board 20. That is, the sealing member 35 seals the plurality of conductive patterns 22, the semiconductor chips 30a and 30b, the contact components 31, the lower parts of the external connection terminals 32, and the wires 33. A gap may be provided between the front surface of the sealing member 35 and the lid portion 12.

[0044] Next, the semiconductor module 1 to which the printed circuit board is attached will be described with reference to Figures 5 to 7. Figure 5 is a first cross-sectional view of the semiconductor module to which the printed circuit board of the first embodiment is attached, and Figure 6 is a second cross-sectional view of the semiconductor module to which the printed circuit board of the first embodiment is attached. Figure 7 is an enlarged cross-sectional view of the semiconductor module to which the printed circuit board of the first embodiment is attached.

[0045] The semiconductor device 5 is formed by attaching a printed circuit board 40 to the semiconductor module 1 shown in Fig. 1. Figures 5 and 6 are cross-sectional views of the semiconductor device 5 taken along dashed lines Y1-Y1 and Y2-Y2 of the semiconductor module 1 shown in Fig. 1. Fig. 7 is an enlarged view of the area surrounded by the dashed line in Fig. 6.

[0046] The semiconductor device 5 includes a semiconductor module 1 and a printed circuit board 40. The printed circuit board 40 includes an insulating plate and a plurality of upper circuit patterns formed on the front surface of the insulating plate (not shown). The printed circuit board 40 also includes a plurality of lower circuit patterns on the back surface of the insulating plate, as needed. Furthermore, the printed circuit board 40 has a plurality of through-holes 41 that penetrate from the front surface to the back surface, formed at positions corresponding to the external connection terminals 32 of the semiconductor module 1. The printed circuit board 40 also has alignment holes 42 (see FIG. 6 ) formed at the four corners of the area where the plurality of through-holes 41 are formed.

[0047] The insulating plate is flat and made of an insulating material. Such a material is used by soaking a base in resin. For example, paper, glass cloth, or glass nonwoven cloth is used as the base. For example, phenolic resin, epoxy resin, or polyimide resin is used as the resin. Specific examples of insulating plates include a paper phenolic substrate, a paper epoxy substrate, a glass epoxy substrate, a glass polyimide substrate, and a glass composite substrate. Such insulating plates are also rectangular in plan view. The corners of the insulating plate may be rounded or chamfered.

[0048] The upper circuit pattern and the lower circuit pattern have a plurality of pattern shapes to form a predetermined circuit. The upper circuit pattern and the lower circuit pattern are made of a material with excellent conductivity. Examples of such materials include silver, copper, nickel, or an alloy containing at least one of these. The surfaces of the upper circuit pattern and the lower circuit pattern may be plated to improve corrosion resistance. Materials used in this plating process include nickel, nickel-phosphorus alloy, nickel-boron alloy, etc. Furthermore, the through-holes 41 are electrically connected to at least one of the upper circuit pattern and the lower circuit pattern as appropriate.

[0049] The external connection terminals 32 of the semiconductor module 1 are press-fitted into the through holes 41 of the printed circuit board 40. Furthermore, the printed circuit board 40 is fixed to the semiconductor module 1 with tapping screws 50 inserted through the alignment holes 42. This electrically connects the printed circuit board 40 and the semiconductor module 1. Note that if the external connection terminals 32 are straight rather than press-fit terminals, the external connection terminals 32 may be inserted into the through holes 41 and fixed to the through holes 41 with solder.

[0050] When the external connection terminals 32 are press-fitted into the printed circuit board 40, the back surface of the printed circuit board 40 abuts against the upper surface 11e of the case 10 (outer frame 11). Then, the alignment holes 42 of the printed circuit board 40 are positioned in the fastening portions 13 of the case 10 (outer frame 11). Tapping screws 50 are inserted through the alignment holes 42 of the printed circuit board 40 to attach it to the case 10 (outer frame 11).

[0051] As described above, the fastening portions 13 are formed on the upper surfaces 11e of the side walls 11b and 11d on the side walls 11a and 11c sides in a plan view of the upper surfaces 11e. The fastening portions 13 include boss portions 13a, fastening holes 13b, fastening surfaces 13c, and fastening bottom surfaces 13d.

[0052] The boss portion 13a is formed in a continuous ring shape surrounding the fastening hole 13b in the upper surface 11e. The fastening hole 13b is cylindrical. For example, the fastening hole 13b has a cylindrical shape that is circular in a plan view. The fastening hole 13b is formed longer (deeper) than the tapping screw 50 without extending from the upper surface 11e to the lower surface 11f of the outer frame 11. The fastening hole 13b is an area surrounded by the fastening surface 13c and the fastening bottom surface 13d. The fastening surface 13c is curved and extends from the upper surface 11e to the lower surface 11f of the outer frame 11. The fastening surface 13c is substantially smooth before the tapping screw 50 is threaded. When the tapping screw 50 is threaded, a spiral groove is formed in the fastening surface 13c by the threads of the tapping screw 50. The fastening bottom surface 13d is connected to the bottom end of the fastening surface 13c. The fastening bottom surface 13d is generally circular in plan view. Voids V are present below the fastening surface 13c (in the -Z direction) and near the inside of the fastening bottom surface 13d. Voids V are almost absent near the inside of the fastening surface 13c above (in the +Z direction).

[0053] The tapping screw 50 includes a head 51 and a threaded portion 52. The head 51 is integrally joined to the other end of the threaded portion 52. The other end of the threaded portion 52 is the end opposite to the tip of the cylindrical threaded portion 52. It is sufficient that the surface of the head 51 that is joined to the other end of the threaded portion 52 forms a substantially smooth main surface. The head 51 may be rectangular, semispherical, or trapezoidal in side view. The diameter of the head 51 is longer than the diameter of the threaded portion 52, and is, for example, at least two times and at most four times the diameter of the threaded portion 52.

[0054] The threaded portion 52 is cylindrical and has a reduced diameter at its tip (the −Z direction side in FIG. 7). A helical thread is formed on the side (main body) of the threaded portion 52 excluding the tip. The diameter of the threaded portion 52 corresponds to the diameter of the fastening hole 13b.

[0055] Such a tapping screw 50 is made of a material expected to have high strength. Examples of such materials include steel, stainless steel, brass, aluminum, magnesium, plastic, and titanium. When the tapping screw 50 is inserted through the alignment hole 42 of the printed circuit board 40 and enters the fastening hole 13b of the case 10 (outer frame 11) while rotating, the threads of the tapping screw 50 advance in the -Z direction while forming a groove in the fastening surface 13c. In this way, the tapping screw 50 is threaded into the fastening hole 13b.

[0056] Furthermore, the columnar mark 16 is formed parallel to the fastening hole 13b on the side of the fastening hole 13b facing the storage area 15. The columnar mark 16 is a hole extending from the upper surface 11e to the lower surface 11f of the outer frame 11. The columnar mark 16 is columnar and longer (deeper) than the tapping screw 50 threaded into the fastening hole 13b. The columnar mark 16 has, for example, a rectangular columnar shape. The length (depth) of the columnar mark 16 from the upper surface 11e to the lower end may be shorter (shallower) than the length (depth) of the fastening hole 13b from the upper surface 11e to the lower end. The length (depth) of the columnar mark 16 from the upper surface 11e to the lower end may be at least 40% to 50% of the length (depth) of the fastening hole 13b from the upper surface 11e to the lower end.

[0057] Next, a method for manufacturing the case 10 included in the method for manufacturing such a semiconductor module 1 will be described with reference to FIGS. 8 to 12. FIG. 8 is a flowchart illustrating a method for manufacturing a case included in a semiconductor module according to the first embodiment. FIG. 9 is a plan view of a molding apparatus according to the first embodiment. FIG. 10 is a first cross-sectional view of a molding die included in the molding apparatus according to the first embodiment, FIG. 11 is a second cross-sectional view of a molding die included in the molding apparatus according to the first embodiment, and FIG. 12 is a third cross-sectional view of a molding die included in the molding apparatus according to the first embodiment. Note that, although the following description focuses on area A in FIG. 9, the same applies to the other three corner areas of the outer frame 11 in FIG. 9. FIG. 10 shows a cross-sectional view parallel to the X-Y plane of area A of the corner area of ​​the outer frame 11 surrounded by the dashed line in FIG. 9. FIG. 11 shows a cross-sectional view taken along dashed line X-X in FIG. 9. FIG. 12 shows a cross-sectional view taken along dashed line Y-Y in FIG. 9.

[0058] First, a preparation step is performed (step S10) to prepare items necessary for manufacturing the case 10. Items prepared here include, for example, a molding material for the outer frame 11, metal fittings that will become the mounting portion 14, and a molding device (described later). Items other than those listed here may also be prepared as needed.

[0059] Next, a molding device setting step is performed to set up the molding device (step S11). The molding device 3 to be set includes at least the molding die 4, sprues 62a and 62b, runners 62c and 62d, and gates 63a to 63d, as shown in FIG.

[0060] The molding die 4 includes a first mold part 60 and a second mold part 64. The first mold part 60 is box-shaped and has a cavity 61 defined therein. The first mold part 60 includes side faces 60a to 60d that surround the first mold part 60 in order on all four sides in a plan view. The side faces 60b and 60d correspond to the side walls 11b and 11d of the outer frame 11 molded in the cavity 61. The side faces 60a and 60c correspond to the side walls 11a and 11c of the outer frame 11 molded in the cavity 61. In addition, injection ports 60bd and 60bc and injection ports 60db and 60da that lead to the cavity 61 are formed in the side faces 60b and 60d, respectively.

[0061] In a plan view, the injection ports 60bd, 60bc and the injection ports 60db, 60da are located a predetermined distance inward (in the ±X direction) from the side surfaces 60a, 60c of the side surfaces 60b, 60d, respectively. Furthermore, the injection ports 60bd, 60bc and the injection ports 60db, 60da are located near the bottom surfaces of the side surfaces 60b, 60d, in a side view. That is, the injection ports 60bd, 60bc and the injection ports 60db, 60da are provided at positions on the side surfaces 60b, 60d, in a plan view, corresponding to the outermost surfaces 11b1, 11b5 and the outermost surfaces 11d1, 11d5 of the fastening portion of the outer frame 11, and also to the top surface 11e to which the inclined surfaces 11d2, 11d4 and the inclined surfaces 11b2, 11b4 are connected.

[0062] 10 to 12, the cavity 61 of the first mold part 60 includes a molding space 61a in which the outer frame 11 is molded. This molding space 61a includes molding inner surfaces 60d2, 60c2 that define the outer frame 11 and the storage area 15 for the outer frame 11, molding outer surfaces 60d1, 60c1 that are provided outside the molding inner surfaces 60d2, 60c2 and contact the side walls 11d, 11c of the outer frame 11, and molding bottom surfaces 60d3, 60c3 that connect the molding inner surfaces 60d2, 60c2 and the molding outer surfaces 60d1, 60c1 and contact the bottom surface 11f of the outer frame 11. The width of the molding bottom surfaces 60d3, 60c3 corresponds to the thickness of the side walls 11d, 11c of the outer frame 11. Furthermore, an injection port 60da communicating with the molding space 61a is formed on the molding outer surface 60d1 at a distance inward (in the -X direction) from the end (on the +X direction side) of the molding outer surface 60d1 in plan view.

[0063] Furthermore, the first mold part 60 includes a mold pin portion 62. The mold pin portion 62 is rod-shaped and corresponds to the fastening hole 13b included in the outer frame 11. The mold pin portion 62 is arranged perpendicular to the molding bottom surface 60d3 at a corner of the molding space 61a in a plan view. The mold pin portion 62 may be formed integrally with the first mold part 60.

[0064] The second mold part 64 is rod-shaped and corresponds to the columnar marks 16 included in the outer frame 11. Here, as an example, the second mold part 64 has a rectangular columnar shape in a plan view. The second mold part 64 is positioned parallel to the mold pin part 62 in the molding space 61a, between the mold pin part 62 and the injection port 60da in a plan view, closer to the molding inner surface 60d2 than the molding outer surface 60d1. That is, the second mold part 64 is positioned so as to block the injection port 60da side of the gap between the molding inner surface 60d2 and the mold pin part 62, but does not completely block it. The second mold part 64 is preferably spaced 1 mm or more from the mold pin part 62 toward the injection port 60da (-X direction) in a plan view. Since the second mold part 64 corresponds to the columnar marks 16 included in the outer frame 11, it has the same length as the columnar marks 16. In other words, the length to the lower end of the second mold part 64 in the molding space 61a should be at least 40% to 50% of the length to the lower end of the mold pin portion 62 in the molding space 61a. Note that in this example, the second mold part 64 and the mold pin portion 62 have the same length.

[0065] The filled molding material passes through the sprues 62a and 62b and flows into runners 62c and 62d. The runners 62c and 62d allow the molding material flowing from the sprues 62a and 62b to flow into gates 63a and 63b and gates 63c and 63d. The gates 63a and 63b and gates 63c and 63d are connected to injection ports 60da and 60db and injection ports 60bc and 60bd, respectively. The gates 63a and 63b and gates 63c and 63d allow the molding material flowing from the runners 62c and 62d to be filled into the cavity 61 of the first mold part 60 through the injection ports 60da and 60db and injection ports 60bc and 60bd. A metal fitting that becomes the mounting portion 14 is set in a predetermined location within the cavity 61 of this molding die 4.

[0066] Next, an injection step is carried out (step S12) in which the molding material is injected into the cavity 61 of the molding die 4. With the molding die 4 maintained at a predetermined temperature, the molten molding material is poured from the sprues 62a, 62b of the molding device 3, and the molding material is injected into the cavity 61 (molding space 61a) of the molding die 4. The flow of the molding material within the cavity 61 of the molding die 4 at this time will be described later.

[0067] Next, a hardening step is carried out (step S13) to harden the molding material injected into the cavity 61 of the molding die 4. The molding die 4, whose cavity 61 has been filled with the molding material, is cooled to a predetermined temperature and maintained at that temperature for a certain period of time.

[0068] Next, a molded product removal step is performed (step S14), in which the molded product is removed from the molding die 4. The molding die 4 is opened, and the molded product inside the molding die 4 is ejected using the ejector pin to remove it. When the molding die 4 is released, the mold pin portion 62 and the second mold part 64 are pulled out of the molded product, and the fastening hole 13b and the columnar mark 16 are formed.

[0069] Next, a gate removal step is performed (step S15), in which the portions corresponding to the gates 63a to 63d are removed from the molded product removed in step S14. The portions corresponding to the gates 63a to 63d remain connected to the molded product removed in step S14. By removing these portions, the case 10 is obtained. The gate marks S on the side walls 11b and 11d of the case 10 are the locations where the portions corresponding to the gates 63a to 63d were connected. The portions corresponding to the gates 63a to 63d may be removed, for example, by breaking them off. Alternatively, if the portions corresponding to the gates 63a to 63d are too thick to bend, they may be cut off, for example, with a cutter.

[0070] On the other hand, semiconductor chips 30a, 30b and contact components 31 are bonded to predetermined conductive patterns 22 on the insulating circuit board 20 using a bonding material. Wiring is performed using wires 33. External connection terminals 32 are press-fit into the contact components 31. The semiconductor unit 2 formed in this manner is attached to the case 10 through the opening 11h on the bottom surface 11f. At this time, the external connection terminals 32 are inserted into the terminal holes 12a in the lid portion 12 of the case 10. At this time, the outer edge of the insulating circuit board 20 is fixed to the step 11g of the case 10 via the adhesive 34 applied to the outer edge. A sealing material 35 is filled into the storage area 15 inside the case 10, sealing the components on the front surface of the insulating circuit board 20. In this manner, the semiconductor module 1 is obtained.

[0071] Here, a comparative example of a manufacturing method for the case 10 (outer frame 11) of the first embodiment will be described. In the comparative example, the case 10 is manufactured using the molding die 4 of the first embodiment without using the second mold component 64. That is, the case 10 of the comparative example is manufactured using only the first mold component 60. The case 10 of the comparative example is also manufactured according to the flowchart of FIG. 8. The flow of molding material when only the first mold component 60 is used in the injection process of step S12 will be described using FIG. 13. FIG. 13 is a first cross-sectional view showing the injection process included in the manufacturing method for the case of the comparative example. Note that the solid arrows in FIG. 13 represent the flow of molding material. Also, FIG. 13 corresponds to FIG. 10, with the second mold component 64 removed from FIG. 10.

[0072] The molding material poured into the sprue 62a passes through the runner 62c and gate 63a and is injected into the molding space 61a through an injection port 60da on the side surface 60d of the first mold part 60. The molding material injected into the molding space 61a spreads within the molding space 61a. The molding material flows from the area surrounded by the molding inner surface 60d2, the molding outer surface 60d1, and the molding bottom surface 60d3 into the area surrounded by the molding inner surface 60c2, the molding outer surface 60c1, and the molding bottom surface 60c3. At this time, the molding material flows through the gap B (broken line area) between the mold pin portion 62 and the molding inner surface 60d2.

[0073] When the molding material flows into gap B, which is narrower than the other gaps, the flow rate in gap B decreases. As a result, the molding material flows less around mold pins 62 and tends to stagnate there more than in other places. Therefore, the molding material around mold pins 62 is more likely to shrink.

[0074] In this state, when the molding material begins to harden in the hardening process of step S13, the molding material in gap B hardens last, causing voids to form and remain there. Then, steps S14 and S15 are carried out to obtain case 10.

[0075] Next, the fastening holes 13b of the case 10 (outer frame 11) manufactured in this manner will be described with reference to Fig. 14. Fig. 14 is an enlarged cross-sectional view of a comparative example case. Note that Fig. 14 corresponds to the state before the tapping screws 50 in Fig. 7 are attached.

[0076] In the case 10 manufactured using the molding die 4 of the comparative example, a large number of voids V are present near the inside of the fastening surface 13c of the fastening hole 13b on the storage area 15 side. In this case, a plurality of voids V are present across the entire fastening surface 13c in the ±Z direction. Similarly, voids V are also present near the inside of the fastening bottom surface 13d of the fastening hole 13b.

[0077] In this manner, the tapping screw 50 is screwed into the fastening hole 13b, which has a void V inside the fastening surface 13c. When the tapping screw 50 is screwed into the fastening surface 13c, a spiral groove is formed by the threads of the tapping screw 50. However, the fastening surface 13c, which includes the void V, is weak, and the groove is not properly formed. Therefore, the tapping screw 50 cannot be securely screwed into the fastening hole 13b. The tapping screw 50 will either spin freely in the fastening hole 13b or will come out of the fastening hole 13b. As a result, the printed circuit board 40 cannot be securely fixed to the semiconductor module 1.

[0078] On the other hand, the molding die 4 of the first embodiment includes a second mold part 64 in addition to the first mold part 60. During the injection process (step S12), the rod-shaped second mold part 64 is positioned parallel to the mold pin part 62 in the molding space 61a between the mold pin part 62 and the injection port 60da in a plan view, closer to the molding inner surface 60d2 than the molding outer surface 60d1. That is, the second mold part 64 is positioned parallel to the mold pin part 62 in the gap between the mold pin part 62 and the molding inner surface 60d2, on the injection port 60da side. The molding material injected into the molding space 61a flows toward the gap B between the mold pin part 62 and the molding inner surface 60d2 (see FIG. 13). At this time, the molding material flows around the second mold part 64 and into the gap B between the mold pin part 62 and the molding inner surface 60d2 in a plan view. That is, the second mold part 64 prevents the molding material from stagnating around the mold pins 62, thereby reducing shrinkage of the molding material around the mold pins 62. Under these conditions, even when the molding material hardens in the hardening process of step S13, the occurrence of voids is reduced. The outer frame 11 manufactured in this manner contains almost no voids V inside the fastening surfaces 13c of the fastening holes 13b. Therefore, when a tapping screw 50 is threaded into the fastening hole 13b, a groove is reliably formed on the fastening surface 13c by the threads of the tapping screw 50, and the tapping screw 50 is reliably fastened to the fastening hole 13b without slipping or coming loose. Therefore, the semiconductor device 5 allows the printed circuit board 40 to be reliably attached to the semiconductor module 1.

[0079] To ensure reliable fastening of the tapping screw 50 into the fastening hole 13b, it is sufficient that the void V is not present above the fastening surface 13c. Specifically, as shown in FIG. 7 , when the tapping screw 50 is threaded into the fastening hole 13b, it is preferable that the void V is not present between the upper surface 11e of the fastening surface 13c and a position approximately halfway along the tapping screw 50. Therefore, the length (depth) of the columnar mark 16 from the upper surface 11e to its lower end should be at least 40% to 50% of the length (depth) of the columnar mark 16 from the upper surface 11e to its lower end. In other words, the length to the lower end of the second mold component 64 within the molding space 61a should also be at least 40% to 50% of the length to the lower end of the mold pin portion 62 within the molding space 61a.

[0080] Second Embodiment In the second embodiment, a case 10 (outer frame 11) including fastening holes 13b with fewer voids is manufactured using the molding die 4 of the first embodiment without using a second mold part. First, a semiconductor module and a semiconductor device of the second embodiment will be described with reference to FIGS. 15 to 17. FIG. 15 is a perspective view of the semiconductor module of the second embodiment. FIG. 16 is a second cross-sectional view of the semiconductor module to which the printed circuit board of the second embodiment is attached. FIG. 17 is an enlarged cross-sectional view of the semiconductor module to which the printed circuit board of the second embodiment is attached.

[0081] Similar to the first embodiment, the semiconductor module 1a includes a case 10 and a semiconductor unit 2 housed in the case 10. A plurality of external connection terminals 32 included in the semiconductor unit 2 extend to the outside from the front surface of the case 10. The inside of the case 10 is sealed with a sealing member 35.

[0082] In the semiconductor device 5a, a printed circuit board 40 is attached to the semiconductor module 1a with tapping screws 50. The tapping screws 50 are inserted through through holes 41 in the printed circuit board 40 and securely screwed into fastening holes 13b in the case 10.

[0083] However, unlike the first embodiment, the case 10 does not include the columnar marks 16. Also, the position of the gate marks S on the side walls 11b and 11d of the case 10 is closer to the top surface 11e than in the first embodiment.

[0084] The case 10 of the second embodiment is also manufactured in accordance with the flowchart of Fig. 8. Here, the molding device 3 used in manufacturing the case 10 of the second embodiment will be described with reference to Figs. 18 to 20.

[0085] Fig. 18 is a plan view of a molding apparatus according to a second embodiment. Fig. 19 is a second cross-sectional view of a molding die included in the molding apparatus according to the second embodiment, and Fig. 20 is a third cross-sectional view of a molding die included in the molding apparatus according to the second embodiment. Note that, although the following description will focus on range A in Fig. 18, the same applies to the same ranges in the other three corners of the outer frame 11 in Fig. 18. Figs. 18 to 20 correspond to Figs. 9, 11, and 12, respectively. Figs. 19 and 20 are cross-sectional views taken along dashed lines X-X and Y-Y in Fig. 18.

[0086] As shown in FIG. 18, the molding apparatus 3 of the second embodiment also includes at least the molding die 4, sprues 62a and 62b, runners 62c and 62d, and gates 63a to 63d.

[0087] The molding die 4 of the second embodiment includes only a first mold part 60. The first mold part 60 has the same configuration as that of the first embodiment. However, the injection port 60da is provided higher (in the +Z direction) than in the first embodiment. For example, as shown in FIG. 19 , the injection port 60da is formed on the molding outer surface 60d1 at a position corresponding to a height H1 from the upper surface 11e of the outer frame 11 to a height H0 that is 30% or less of the height H0 from the upper surface 11e to the lower surface 11f.

[0088] Because the injection port 60da is formed above (in the +Z direction) the molding outer surface 60d1, a decrease in the speed at which the molding material flows above (in the +Z direction) the mold pins 62 is suppressed. This reduces retention of the molding material above (in the +Z direction) the mold pins 62, thereby reducing shrinkage of the molding material. In this state, even if the molding material hardens in the hardening process of step S13, the occurrence of voids V around (above) the mold pins 62 (in the +Z direction) is reduced.

[0089] As described above, for the tapping screw 50 to be securely fastened to the fastening hole 13b, it is sufficient that the void V is not included above the fastening surface 13c. Therefore, by forming the injection port 60da above (in the +Z direction) the molded outer surface 60d1, the occurrence of voids V around the mold pin portion 62 (in the +Z direction) is reduced. In other words, almost no voids V are included around (in the +Z direction) the fastening hole 13b of the case 10. Therefore, when the tapping screw 50 is threaded into the fastening hole 13b, a groove is reliably formed on the fastening surface 13c by the threads of the tapping screw 50, and the tapping screw 50 is securely fastened to the fastening hole 13b without slipping or coming loose. Therefore, in the semiconductor device 5a, the printed circuit board 40 can be securely attached to the semiconductor module 1a.

[0090] The foregoing merely illustrates the principles of the present invention. Further, since numerous modifications and changes will be apparent to those skilled in the art, the present invention is not limited to the exact construction and application shown and described above, and all corresponding modifications and equivalents are deemed to be within the scope of the present invention as defined by the appended claims and their equivalents.

[0091] REFERENCE SIGNS LIST 1, 1a Semiconductor module 2 Semiconductor unit 3 Molding device 4 Molding mold 5, 5a Semiconductor device 10 Case 11 Outer frame 11a to 11d Side wall 11b1, 11b5 Outermost surface 11b2, 11b4 Inclined surface 11b3 Outer surface 11d1, 11d5 Outermost surface 11d2, 11d4 Inclined surface 11d3 Outer surface 11e Top surface 11f Bottom surface 11g Step 11h Opening 12 Lid portion 12a Terminal hole 13 Fastening portion 13a Boss portion 13b Fastening hole 13c Fastening surface 13d Fastening bottom surface 14 Mounting portion 14a Mounting hole 15 Storage area 16 Columnar mark 20 Insulated circuit board 21 Insulating plate 22 Conductive pattern 23 Metal plates 30a, 30b Semiconductor chip 30c Electronic component 31 Contact component 32 External connection terminal 33 Wire 34 Adhesive 35 Sealing member 40 Printed circuit board 41 Through hole 42 Alignment hole 50 Tapping screw 51 Head 52 Threaded portion 60 First mold part 60a to 60d Side surface 60c1, 60d1 Molding outer surface 60c2, 60d2 Molding inner surface 60c3, 60d3 Molding bottom surface 60bc, 60bd, 60da, 60db Inlet 61 Cavity 61a Molding space 62 Mold pin portion 62a, 62b Sprue 62c, 62d Runner 63a, 63b, 63c, 63d Gate 64 Second mold part V Void S Gate mark

Claims

1. A method for manufacturing a mold for molding a case, the mold comprising: a first mold part having a first cavity corresponding to the shape of a case, the first mold part including a rod-shaped mold pin part corresponding to the fastening part, the first mold part having an outer frame surrounding all four sides of a storage area extending from a lid part to a bottom surface of the case, the outer frame having a rectangular shape in a plan view, and a tubular fastening part formed at a corner of the upper surface of the outer frame to be fastened with a screw; an injection step of providing the mold pin part in the cavity of the first mold part and injecting the molding material from the injection part into the cavity; the cavity of the first mold part including a molding space in which the outer frame is molded; a molding outer surface provided outside the molding inner surface and having an injection port communicating with the molding space spaced inward from each end in a plan view; and a molding bottom surface connecting the molding inner surface and the molding outer surface and contacting the lower surface of the outer frame, the mold pin portion being arranged at a corner of the molding space perpendicular to the molding bottom surface in a plan view; and the molding mold further includes a rod-shaped second mold part that is arranged parallel to the mold pin portion in the molding space between the mold pin portion and the injection port in a plan view and closer to the molding inner surface than the molding outer surface during the injection step.

2. The method for manufacturing a semiconductor module described in claim 1, wherein the length to the lower end of the second mold part within the molding space is 40% or more and 50% or less of the length to the lower end of the mold pin portion within the molding space.

3. The method for manufacturing a semiconductor module according to claim 1, wherein the second mold part is spaced from the mold pin portion by 1 mm or more in a plan view.

4. The method for manufacturing a semiconductor module according to claim 1, wherein the second mold part has a rectangular column shape in a plan view.

5. The method for manufacturing a semiconductor module described in claim 1, wherein in the injection process, the molding material injected from the injection port flows around the second mold part within the molding space in a plan view and flows between the mold pin portion and the molding inner surface.

6. A molding die having a first mold part including a rod-shaped mold pin part corresponding to the fastening part, the first mold part having a rectangular shape in a plan view and an outer frame surrounding all four sides of a storage area extending from a lid part to a bottom surface, a cavity corresponding to the shape of a case having a cylindrical fastening part formed at a corner of an upper surface of the outer frame, an injection port formed to communicate with the cavity from the outside, and a molding material; and an injection step of providing the mold pin part in the cavity of the first mold part and injecting the molding material from the injection port toward the cavity, the cavity of the first mold part including a molding space in which the outer frame is molded, A method for manufacturing a semiconductor module, wherein the molding space is composed of a molding inner surface that defines the outer frame and the storage area, a molding outer surface that is provided outside the molding inner surface and has the injection inlets leading to the molding space formed at a distance inward from each end in a planar view, and a molding bottom surface that connects the molding inner surface and the molding outer surface and contacts the lower surface of the outer frame, wherein the mold pin portion is arranged at a corner of the molding space perpendicular to the molding bottom surface in a planar view, and the injection inlet is formed on the molding outer surface corresponding to a position that is 30% or less from the top surface of the outer frame with respect to the height from the top surface to the bottom surface.

7. A method for manufacturing a semiconductor module as described in claim 1 or 6, wherein the outer frame includes a first side wall, a second side wall, a third side wall and a fourth side wall which surround the storage area on all four sides, the first side wall and the third side wall being in the longitudinal direction, and the molding outer surface has the injection ports formed corresponding to the first side wall and the third side wall, respectively.

8. A method for manufacturing a semiconductor module as described in claim 7, wherein in the outer frame, the thicknesses of the first side wall and the third side wall are greater than the thicknesses of the second side wall and the third side wall in a planar view, and the width of the molding space corresponding to the first side wall and the third side wall in a planar view is also greater than the width of the portions corresponding to the second side wall and the third side wall.

9. A method for manufacturing a semiconductor module as described in claim 8, wherein the first side wall and the third side wall of the outer frame are configured so that a fastening portion including the fastening part is thicker than other portions, and the molded outer surface has the injection ports formed so as to correspond to the fastening portions of the first side wall and the third side wall, respectively.

10. A method for manufacturing a semiconductor module as described in claim 9, wherein the fastening portion includes an upper surface on which the fastening section is formed, and an inclined surface integrally connected to the upper surface and inclining toward the lower surface along the first side wall and the third side wall as it moves away from the fastening portion, and the molding outer surface is formed with the injection ports each corresponding to the upper surfaces included in the fastening portions of the first side wall and the third side wall in a planar view.

Images