Semiconductor Devices

Abstract

The present invention relax stress concentration in a ceramic circuit board, thereby preventing the ceramic circuit board from the occurrence of a crack.　A semiconductor device (10) according to the present invention comprises: a ceramic circuit board (11); and terminals (12, 12-1) and a semiconductor chip (18), which are bonded to the front surface of the ceramic circuit board (11). The ceramic circuit board (11) comprises an insulating plate (11a), conductive plates (11b, 11b-1) and a metal plate (11c). The insulating plate (11a) is mounted on a surface of a base plate (15). The conductive plates (11b, 11b-1) are mounted on the insulating plate (11a); and the terminal (12), which is provided on a case (17), is bonded onto the conductive plate (11b) by the intermediary of a bonding material (13). A bonding material leaking / spreading inhibition structure (1) for inhibiting leaking and spreading of a melted bonding material (13) is provided in the vicinity of an edge (eg1) of the conductive plate (11b).

Description

[Technical Field]

[0001] The present invention relates to a semiconductor device in which terminals are bonded to a substrate with a bonding material. [Background technology]

[0002] Semiconductor devices include power devices, which are used, for example, as power converters. Power devices are semiconductor chips that include an IGBT (Insulated Gate Bipolar Transistor) or a power MOSFET (Metal Oxide Semiconductor Field Effect Transistor).

[0003] Electronic components, such as semiconductor chips, are mounted on a ceramic circuit substrate via solder. The ceramic circuit substrate also includes an insulating plate and multiple conductive plates formed on the insulating plate. In such semiconductor devices, terminals of electronic components or lead frames are fixed to the conductive plates by melting and solidifying the solder. However, since the molten solder may flow out of the terminal bonding area, it is important to take measures to prevent the solder from flowing out.

[0004] Related technologies include, for example, a technique proposed in which a plating film on a circuit board is irradiated with a laser to generate a resist portion, which is an oxide film, to repel solder (Patent Document 1). Another technique has been proposed in which a solder dam is formed on the surface of a copper circuit pattern to prevent the outflow of molten solder (Patent Document 2). Another technique has been proposed in which a protrusion is formed between the soldering area and the wire bonding area on the surface of the copper plate to prevent the outflow of solder (Patent Document 3).

[0005] Another proposed technique involves forming a thin portion by molding the periphery of a heat diffusion plate to balance the stress on the solder layer (Patent Document 4). Another proposed technique involves improving heat cycle resistance by making the bonding layer extend beyond the edge of the metal member by 0.1 to 1.0 times the thickness of the metal member (Patent Document 5). Another proposed technique involves joining a metal plate to the main surface of a ceramic substrate via a brazing filler metal layer, with the brazing filler metal layer extending outward beyond the side of the metal circuit pattern formed on the metal plate (Patent Document 6). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-118350 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-363216 [Patent Document 3] Japanese Patent Application Laid-Open No. 2000-286289 [Patent Document 4] Japanese Patent Application Publication No. 7-221265 [Patent Document 5] Japanese Patent Application Publication No. 10-190176 [Patent Document 6] Japanese Patent Application Publication No. 11-340598 Summary of the Invention [Problem to be solved by the invention]

[0007] If the molten solder flows out of the joint area of ​​the terminal and spreads to the edge of the conductive plate, it may cause cracks in the ceramic circuit board, for example, when a heat cycle test is performed. This occurs when the ceramic circuit board is affected by the expansion and contraction of the solder under the terminal, causing stress to concentrate on the ceramic circuit board around the solder, resulting in cracks.

[0008] Conventionally, cracks in ceramic circuit boards have been prevented by providing an R-shape at the edge of the conductive plate around the solder where cracks can occur, thereby alleviating the stress caused by the expansion and contraction of the solder. However, if there is not enough space in the layout for mounting the semiconductor chip in the peripheral area where cracks may occur in the ceramic circuit board, it is difficult to take measures such as providing an R-shape at the end of the conductive plate.

[0009] 15 and 16 are diagrams showing an example of a configuration in which an R-shaped edge is provided on the end of a conductive plate. In a ceramic circuit board 100, an insulating plate 110 is formed on a metal plate (not shown), and a conductive plate 120 is formed on the insulating plate 110. Terminals (not shown) are joined to the conductive plate 120 by solders 130a to 130d. Furthermore, the solders 130b and 130d are surrounded by a separation groove m0. Component regions 121 to 124 on the conductive plate 120 are regions on which semiconductor chips are mounted.

[0010] Here, when the solder 130a under the terminal is in a molten state, there is a possibility that the solder 130a will wet and spread to the end eg0 of the conductive plate 120. For this reason, it is conceivable to take measures to provide an R-shape to the end eg0 of the conductive plate 120, which is likely to cause a crack in the ceramic circuit board 100.

[0011] However, if an R-shape sp1 is provided on the entire side of the conductive plate 120, including the edge eg0, as shown in Fig. 15, while maintaining the distance (frame dimension) from the edge of the insulating plate to the edge of the conductive plate and satisfying the insulation standard, the area of ​​the edge eg0 will be scraped away. Furthermore, the component areas 121 and 122 on the conductive plate 120 will also be scraped away, making it difficult to mount semiconductor chips on the component areas 121 and 122.

[0012] Also, as shown in Fig. 16, a countermeasure can be considered in which an R-shape sp2 is provided locally at the end eg0 of the conductive plate 120. Fig. 17(a) shows an example of a configuration in which an R-shape is provided at the end of the conductive plate before the countermeasure, and Fig. 17(b) shows an example of a configuration in which an R-shape is provided at the end of the conductive plate after the countermeasure. In the structure before the countermeasure in Fig. 17(a), the solder 130a reaches the end eg0 of the conductive plate 120. If an R-shape sp2 is provided locally at the end eg0 of the conductive plate 120 in such a structure, the R-shape sp2 provided on the conductive plate 120 will protrude outward, as shown in the structure after the countermeasure in Fig. 17(b). In this case, the end of the R-shape sp2 of the conductive plate 120 and the insulating Edge plate It becomes impossible to ensure the frame dimension sz, which is the distance from the end of 110, and it becomes difficult to satisfy the insulation standard.

[0013] As mentioned above, the conventional measure of reducing stress concentration in ceramic circuit boards by forming an R-shape on the edges of conductive plates can be difficult to implement depending on the semiconductor chip mounting layout. For this reason, there is a demand for technology that can effectively reduce stress concentration in ceramic circuit boards caused by the wetting and spreading of solder, and prevent the occurrence of cracks in ceramic circuit boards, without relying on the semiconductor chip mounting layout.

[0014] In one aspect, the present invention aims to provide a semiconductor device that prevents cracks from occurring in a ceramic circuit board by suppressing the range of solder wetting and spreading and thereby alleviating stress concentration in the ceramic circuit board. [Means for solving the problem]

[0015] In order to solve the above problems, a semiconductor device is provided. , absoluteThe device comprises an edge plate, a conductive plate provided on an insulating plate, and a terminal joined to the conductive plate with a bonding material, and the edge of the conductive plate is provided with a structure that prevents the bonding material from spreading to the edge. This structure also includes a thin portion of the conductive plate at the edge, with the bonding material adhering to the boundary of the thin portion of the conductive plate and the thin portion of the conductive plate being free of the bonding material. Furthermore, the thin portion of the conductive plate is provided in a predetermined region near the edge where the bonding material should not be attached, and is a gradient provided on the surface of the conductive plate to which the terminal is joined with the bonding material. [Effects of the Invention]

[0016] According to one aspect, it is possible to reduce stress concentration in the ceramic circuit board and prevent cracks from occurring in the ceramic circuit board. 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. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a diagram showing an example of the configuration of a semiconductor device of the present invention; [Figure 2] FIG. 10 is a diagram showing the distance from the edge of the conductive plate to the solder adhesion area. [Figure 3] FIG. 10 is a diagram showing the distance from the edge of the conductive plate to the solder adhesion area. [Figure 4] 10 is a diagram showing the relationship between the distance from the end of the conductive plate to the solder adhesion area and stress. FIG. [Figure 5] FIG. 10 is a diagram illustrating an example of an analysis result. [Figure 6] 6(a) shows an example of a solder leakage / spread suppression structure, in which the solder under the terminals is attached to the conductive plate, as viewed from the front side of the ceramic circuit board, and FIG. 6(b) shows a side view of the ceramic circuit board as viewed from direction A. [Figure 7]7(a) shows an example of a solder leakage / spread suppression structure, in which the solder under the terminals is attached to the conductive plate, as viewed from the front side of the ceramic circuit board, and FIG. 7(b) shows a side view of the ceramic circuit board as viewed from the direction A. [Figure 8] 8(a) shows an example of a solder leakage / spread suppression structure, in which the solder under the terminals is attached to the conductive plate, as viewed from the front side of the ceramic circuit board, and FIG. 8(b) shows a side view of the ceramic circuit board as viewed from direction A. [Figure 9] 9(a) shows a plan view of a ceramic circuit board in which solder under the terminals is attached to a conductive plate, as viewed from the front side, and FIG. 9(b) shows a cross-sectional view of the ceramic circuit board as viewed from direction B. [Figure 10] FIG. 10 is a diagram illustrating an example of an analysis result. [Figure 11] 11(a) shows a plan view of a ceramic circuit board in which solder under the terminals is attached to a conductive plate, as viewed from the front surface, and FIG. 11(b) shows a cross-sectional view of the ceramic circuit board as viewed from direction B. [Figure 12] FIG. 10 is a diagram illustrating an example of an analysis result. [Figure 13] 13(a) shows a plan view of a ceramic circuit board in which solder under a terminal is attached to a conductive plate, as viewed from the front surface, and FIG. 13(b) shows a cross-sectional view of the ceramic circuit board as viewed from direction B. [Figure 14] FIG. 10 is a diagram illustrating an example of an analysis result. [Figure 15] 10A and 10B are diagrams showing an example of a configuration in which an R-shape is provided at the end of a conductive plate. [Figure 16] 10A and 10B are diagrams showing an example of a configuration in which an R-shape is provided at the end of a conductive plate. [Figure 17] 17A and 17B are diagrams illustrating an example of a structure in which an R-shape is provided at the end of a conductive plate, before and after the countermeasure is taken. Fig. 17A shows the structure before the countermeasure is taken, and Fig. 17B shows the structure after the countermeasure is taken. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, the present embodiment will be described with reference to the drawings. In this specification and the drawings, elements having substantially the same configuration may be denoted by the same reference numerals to avoid redundant description. In the following description, "upper surface" refers to a surface facing upward as viewed from the paper. Similarly, "upper" and "upper part" refer to a direction facing upward as viewed from the paper. "Downward" refers to a direction facing downward as viewed from the paper. These directions are used in all drawings. "Upper surface," "upper," "upper part," and "downward" are merely convenient expressions for specifying relative positional relationships and do not limit the technical idea of ​​the present invention.

[0019] <Configuration of semiconductor device> 1 is a diagram showing an example of the configuration of a semiconductor device of the present invention. It shows a cross-sectional view of a semiconductor device 10. The semiconductor device 10 has a ceramic circuit substrate 11, terminals 12 and 12-1 connected to the front surface of the ceramic circuit substrate 11, and a semiconductor chip 18.

[0020] The ceramic circuit board 11 has an insulating plate 11a, conductive plates 11b and 11b-1, and a metal plate 11c. If the conductive plates 11b and 11b-1 and the metal plate 11c are, for example, copper foil patterns, a DCB (Direct Copper Bonding) board can be used in which the conductive plates 11b and 11b-1 and the metal plate 11c are directly bonded to both sides of the insulating plate 11a.

[0021] The ceramic circuit board 11 is mounted on the surface of the base plate 15, and the terminal 12 provided on the case 17 is bonded onto the conductive plate 11b of the ceramic circuit board 11 via the bonding material 13.

[0022] A bonding material leakage / spread suppression structure 1 (described in detail below) is provided near the end eg1 of the conductive plate 11b to suppress leakage / spread of the molten solder 13. Although solder or brazing material is used as the bonding material 13, the following description will be given assuming that the bonding material is solder.

[0023] Meanwhile, semiconductor chip 18 is soldered onto conductive plate 11b-1. Wire 16-1 joins the electrode of semiconductor chip 18 to conductive plate 11b, which serves as a lead electrode of ceramic circuit board 11. Wire 16-2 joins conductive plate 11b-1 to terminal 12-1 provided on case 17. Wires 16-1 and 16-2 are bonded by ultrasonic wire bonding using a load.

[0024] The wires 16-1 and 16-2 are made of a conductive metal such as copper or aluminum or a conductive alloy such as an iron-aluminum alloy, and are formed to have a diameter of, for example, 300 to 500 μm for a high-voltage device.

[0025] The ceramic circuit board 11 with the semiconductor chip 18 bonded thereto is housed in a case 17, and the area surrounded by the case 17 and the base plate 15 is filled and sealed with a sealing resin 19. The case 17 and the base plate 15 are fixed together with an adhesive or the like.

[0026] Here, the insulating plate 11a of the ceramic circuit board 11 is made of insulating ceramics such as aluminum nitride, silicon nitride, or aluminum oxide, and is a plate-like member having a thickness of, for example, 0.2 to 1 mm.

[0027] On the other hand, the conductive plates 11b and 11b-1 of the ceramic circuit board 11 are provided on the upper surface of the insulating plate 11a and are made of a material with excellent conductivity. Such a material may be, for example, copper, aluminum, or an alloy containing at least one of these. The thickness of the conductive plates 11b and 11b-1 is, for example, 0.2 mm.

[0028] In addition to the semiconductor chip 18, wiring members such as bonding wires, lead frames, and connection terminals, as well as electronic components, can be appropriately arranged on the conductive plates 11b and 11b-1 as needed.

[0029] The number, arrangement positions, and shapes of the conductive plates 11b and 11b-1 can be selected appropriately by design. The metal plate 11c of the ceramic circuit board 11 is made of a conductive metal such as copper or aluminum and has a thickness of, for example, 0.1 to 1 mm and is provided on the lower surface of the insulating plate 11a.

[0030] The base plate 15 may be made of, for example, a copper substrate or an aluminum silicon carbide (Al-SiC) substrate, which have high heat dissipation properties. The semiconductor chip 18 is a power device made of silicon, silicon carbide, or gallium nitride. The semiconductor chip 18 includes a switching element, such as a power MOSFET or IGBT.

[0031] Such a semiconductor chip 18 includes, for example, a drain electrode (positive electrode, collector electrode in an IGBT) and a source electrode (negative electrode, emitter electrode in an IGBT) as main electrodes, and a gate electrode as a control electrode.

[0032] The semiconductor chip 18 also includes a diode element, which is, for example, an FWD (Free Wheeling Diode) in which an SBD (Schottky Barrier Diode), a PiN (P-intrinsic-N) diode, or the like is provided in anti-parallel with a switching element.

[0033] Other electronic components may be disposed on the conductive plates 11b and 11b-1 as needed. Examples of the electronic components include capacitors, resistors, thermistors, current sensors, and control ICs (Integrated Circuits). The solder 13 is void-resistant and resistant to high temperatures. For example, the solder 13 may be an alloy primarily composed of tin and antimony. The sealing resin 19 may be a gel filler.

[0034] <Relationship between the distance from the edge of the conductive plate to the solder adhesion area and the stress> Next, the relationship between the distance from the edge of the conductive plate to the solder adhesion area and the stress will be explained using Figures 2 to 5. Figures 2 and 3 are diagrams showing the distance from the edge of the conductive plate to the solder adhesion area. In states st1 and st2 of Figures 2 and 3, respectively, terminal 12 is shown joined to conductive plate 11b via solder 13.

[0035] [State st1] This is a state in which the distance from the end eg1 of the conductive plate 11b to the adhesion area 12a of the solder 13 is 0 mm. In other words, the solder 13 has leaked and spread to reach the end eg1 of the conductive plate 11b, and the solder 13 is adhered to the end eg1 of the conductive plate 11b.

[0036] [State st2] This is a state in which the distance from the end eg1 of the conductive plate 11b to the adhesion area 12a of the solder 13 is 0.3 mm. In other words, the solder 13 does not leak and spread to the end eg1 of the conductive plate 11b, and there is a non-adhesion area 12b where the solder 13 is not attached in the 0.3 mm section from the end eg1 to the adhesion area 12a of the solder 13.

[0037] 4 is a diagram showing the relationship between the distance from the edge of the conductive plate to the solder adhesion area and stress. The vertical axis represents the stress applied to the ceramic circuit board 11, and the horizontal axis represents the distance (mm) from the edge eg1 of the conductive plate 11b to the solder adhesion area 12a.

[0038] The line g1 shows the analysis results. As the distance from the end eg1 of the conductive plate 11b to the adhesion area 12a of the solder 13 increases, the stress decreases, and the possibility of cracks occurring in the ceramic circuit board 11 decreases.

[0039] Fig. 5 shows an example of the analysis results, which are presented in a table, and the items shown are the distance (mm) from the end eg1 of the conductive plate 11b to the adhesion area 12a of the solder 13, and the relative value (%) of the stress generated in the ceramic circuit board 11, with a distance of zero as the reference.

[0040] 5, [distance (mm), stress (%)] = [0, 100], [0.1, 88], [0.3, 74]. The stress acting on ceramic circuit board 11 tends to decrease as the distance from end eg1 of conductive plate 11b to adhesion area 12a of solder 13 increases. Therefore, for example, by ensuring a distance of about 0.3 mm as shown in FIG. 3, the stress decreases by approximately 26% compared to when the distance from end eg1 of conductive plate 11b to adhesion area 12a of solder 13 is 0 mm, and the crack resistance of ceramic circuit board 11 increases.

[0041] <Solder leakage and spread prevention structure #1> Next, a structure for preventing solder 13 from spreading to the end eg1 of conductive plate 11b will be described with reference to Fig. 6 to Fig. 8. Fig. 6 shows an example of a structure for preventing solder leakage and spreading. Fig. 6(a) shows a plan view of the front surface of a ceramic circuit board in which solder under the terminals is attached to the conductive plate, and Fig. 6(b) shows a side view of the ceramic circuit board as seen from direction A.

[0042] A convex portion 1a is provided in a predetermined region r0 near the end eg1 of the conductive plate 11b where the solder 13 should not adhere, forming a convex structure. The convex portion 1a is made of a highly heat-resistant resin that does not peel or deteriorate at the heating temperature of the solder joint, and a thermosetting resin can be used for the convex portion 1a. Examples of thermosetting resins include epoxy resin, phenolic resin, maleimide resin, polyester resin, polyimide resin, silicone resin, and polyamide resin.

[0043] Alternatively, the protrusion 1a may be a metal wire. A dumb wire may be formed by joining the metal wire to a predetermined region r0 near the end eg1 of the conductive plate 11b. The material of the metal wire may be, for example, gold, silver, copper, aluminum, or an alloy containing at least one of these. The joining to the conductive plate 11b may be performed by, for example, ultrasonic bonding.

[0044] In this way, by providing a convex portion 1a in a specified region r0 near the end eg1 of the conductive plate 11b where the solder 13 should not adhere, it is possible to suppress the solder 13 from leaking and spreading to the end eg1 of the conductive plate 11b, thereby preventing cracks from occurring in the ceramic circuit board.

[0045] Figure 7 shows an example of a solder leakage and spread suppression structure. Figure 7(a) shows a plan view of a ceramic circuit board from the front side, with the solder under the terminals adhering to the conductive plate, and Figure 7(b) shows a side view of the ceramic circuit board from direction A.

[0046] A liquid-repellent portion (resist) 1b is provided in a predetermined region r0 near an end eg1 of the conductive plate 11b where the solder 13 should not adhere. The liquid-repellent portion 1b is an oxide film formed by oxidizing the conductive plate 11b.

[0047] The oxide film is, for example, a nickel oxide film. Such an oxide film is formed by irradiating the plating film on the conductive plate 11b with a laser, thereby oxidizing the plating film. The laser irradiation may be either a CW laser that continuously emits laser light or a pulsed laser that intermittently emits laser light.

[0048] In this way, by providing a liquid-repellent portion 1b in a specified area r0 near the end eg1 of the conductive plate 11b where the solder 13 should not adhere, it is possible to suppress the leakage and spread of the solder 13 to the end eg1 of the conductive plate 11b, thereby preventing the occurrence of cracks in the ceramic circuit board.

[0049] Figure 8 shows an example of a solder leakage and spread suppression structure. Figure 8(a) shows a plan view of a ceramic circuit board from the front side, with the solder under the terminals adhering to the conductive plate, and Figure 8(b) shows a side view of the ceramic circuit board from direction A.

[0050] A recess 1c is provided in a predetermined region r0 near the end eg1 of the conductive plate 11b where the solder 13 should not be attached, forming a concave structure. The recess 1c is provided at a position a predetermined distance da away from the end eg1 of the conductive plate 11b. The recess 1c is, for example, a long hole provided along the side L1 of the end eg1 of the conductive plate 11b.

[0051] In this way, by providing a recess 1c in a specified region r0 near the end eg1 of the conductive plate 11b where the solder 13 should not adhere, the leakage and spread of the solder 13 to the end eg1 of the conductive plate 11b can be suppressed, thereby preventing cracks from occurring in the ceramic circuit board.

[0052] <Solder leakage and spread prevention structure #2> Next, a structure for suppressing the solder 13 from spreading to the end eg1 of the conductive plate 11b will be described with reference to Figures 9 to 14. The solder leakage and spread suppression structures shown in Figures 9, 11, and 13 have a structure in which a thin portion of the conductive plate 11b is provided at the end eg1 of the conductive plate 11b.

[0053] Figure 9 shows an example of a solder leakage and spread suppression structure. Figure 9(a) shows a plan view of a ceramic circuit board from the front side, in which the solder under the terminals is attached to a conductive plate, and Figure 9(b) shows a cross-sectional view of the ceramic circuit board from direction B.

[0054] A step 1d is provided in a predetermined region r1 near the end eg1 of the conductive plate 11b where the solder 13 should not be attached, forming a thin portion of the conductive plate 11b. In the example of Fig. 9, the step 1d has a width of 0.15 mm relative to the 5 mm-wide end eg1 of the conductive plate 11b.

[0055] Fig. 10 is a diagram showing an example of the analysis results. Fig. 10 is a table showing the analysis results of the solder leakage and spread suppression structure of Fig. 9, and the items shown are the distance (mm) from the end eg1 of the conductive plate 11b to the adhesion area of ​​the solder 13, and the relative value (%) of the stress generated in the ceramic circuit board 11 with respect to a distance of zero.

[0056] 10, [distance (mm), stress (%)] = [0, 100], [0.15, 74]. In this way, a step 1d is provided in a predetermined region r1 near the end eg1 of the conductive plate 11b where the solder 13 should not be attached, ensuring a distance of approximately 0.15 mm to the region where the solder 13 is attached.

[0057] This reduces stress by approximately 26% compared to when the distance from the end eg1 of the conductive plate 11b to the solder 13 adhesion area is 0 mm, increasing the crack resistance of the ceramic circuit board 11. Note that this structure not only prevents solder from adhering to the end of the conductive plate, but also reduces stress by thinning the conductive plate, resulting in lower stress compared to the structure shown in Figure 4 in which the distance from the end of the conductive plate to the solder adhesion area is increased.

[0058] Figure 11 shows an example of a solder leakage and spread suppression structure. Figure 11(a) shows a plan view of a ceramic circuit board from the front side, in which the solder under the terminals is attached to a conductive plate, and Figure 11(b) shows a cross-sectional view of the ceramic circuit board from direction B.

[0059] A sloped portion 1e is provided in a predetermined region r1 near the end eg1 of the conductive plate 11b where the solder 13 should not be attached, forming a thin portion of the conductive plate 11b. In the example of Fig. 11, the sloped portion 1e is formed at an angle of 45° with respect to the 5 mm wide end eg1 of the conductive plate 11b.

[0060] Fig. 12 is a diagram showing an example of the analysis results. Fig. 12 is a table showing the analysis results of the solder leakage spread suppression structure of Fig. 11, and the items shown are the angle (°) of the sloped portion 1e and the relative value (%) of the stress generated in the ceramic circuit board 11 with an angle of zero as the reference.

[0061] In Figure 12, [angle (°), stress (%)] = [0, 100], [45, 72]. By providing a gradient portion 1e in a predetermined region r1 near the end eg1 of the conductive plate 11b where solder 13 should not be attached, stress is reduced by approximately 28% compared to when the gradient is 0°, ensuring the crack resistance of the ceramic circuit board 11. Note that, like the structures shown in Figures 9 and 10, this structure not only prevents solder from adhering to the end of the conductive plate, but also reduces stress by thinning the conductive plate, resulting in lower stress compared to the structure shown in Figure 4, in which the distance from the end of the conductive plate to the solder attachment area is increased.

[0062] Fig. 13 shows an example of a solder leakage / spread suppression structure. Fig. 13(a) shows a plan view of a ceramic circuit board from the front side, in which the solder under the terminals is attached to a conductive plate, and Fig. 13(b) shows a cross-sectional view of the ceramic circuit board from direction B.

[0063] A local step 1d1 is provided in a predetermined region r2 near the end eg1 of the conductive plate 11b where the solder 13 should not be attached, forming a thin portion of the conductive plate 11b. In the example of Fig. 13, the step 1d1 has a step width of 0.15 mm relative to the 1 mm wide end eg1 of the conductive plate 11b.

[0064] Fig. 14 shows an example of the analysis results. Fig. 14 is a table showing the analysis results of the solder leakage and spread suppression structure shown in Fig. 13, and the items shown are the distance (mm) from the edge of the conductive plate to the solder adhesion area, and the relative value (%) of the stress generated in the ceramic circuit board with a distance of zero as the reference.

[0065] 14, [distance (mm), stress (%)] = [0, 100], [0.15, 87]. In this way, a step 1d1 is provided in a predetermined region r2 near the end eg1 of the conductive plate 11b where the solder 13 should not be attached, ensuring a distance of approximately 0.15 mm to the region where the solder 13 is attached.

[0066] This reduces the stress by 13% compared to when the distance from the end eg1 of the conductive plate 11b to the adhesion area of ​​the solder 13 is 0 mm. Although the margin is slightly lower than in the case of Fig. 9, the formation of a local step 1d1 as shown in Fig. 13 can also prevent cracks from occurring in the ceramic circuit board 11.

[0067] Although the embodiments have been described above, the configuration of each part shown in the embodiments can be replaced with other parts having similar functions. Any other components or processes may be added. Furthermore, any two or more configurations (features) of the above-described embodiments may be combined. 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. [Explanation of symbols]

[0068] 10 Semiconductor devices 11 Ceramic circuit board 11a Insulating plate 11b, 11b-1 Conductive plate 11c metal plate 12, 12-1 terminal 13. Joining material (solder) 15 base plate 16-1, 16-2 Wire (bonding wire) 17 cases 18 Semiconductor Chips 19 Sealing resin eg1 end 1. Structure to prevent leakage and spread of bonding material 1a Convex part 1b Liquid repellent part 1c Recess 1d, 1d1 Step 1e Gradient section st1, st2 state 12a Attachment area 12b Non-adherent region g1 line r0, r1, r2 predetermined area da specified distance L1 edge Sr stress value

Claims

[Claim 1] An insulating plate; a conductive plate provided on the insulating plate; a terminal joined to the conductive plate by a joining material, a structure for preventing the bonding material from spreading to the end portion of the conductive plate; In the structure, a portion where the thickness of the conductive plate is thin is provided at an end of the conductive plate, the bonding material is attached up to the boundary of the portion where the thickness of the conductive plate is thin, and the bonding material is not attached to the portion where the thickness of the conductive plate is thin, the thin portion of the conductive plate is provided in a predetermined region near the end portion to which the bonding material should not be attached, and is a gradient provided on the surface of the conductive plate to which the terminal is bonded with the bonding material; Semiconductor device.

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