Semiconductor device

Abstract

Provided is a semiconductor device capable of suppressing heat generation at a junction between a circuit pattern and a terminal when a large current flows. The semiconductor device includes a circuit substrate (1) having a circuit pattern (2) and a terminal (3). The terminal (3) has an electrode junction portion (4) having a rectangular shape in plan view, a main wiring portion (5), and a pair of sub wiring portions (6). A lower surface of the electrode junction portion (4) is joined to the circuit pattern (2) by a joining material (8). The main wiring portion (5) is disposed in a standing disposition from an edge (4a) of the electrode junction portion (4). The pair of sub wiring portions (6) extend from both widthwise ends of the main wiring portion (5) along edges (4b), (4c) of the electrode junction portion (4) adjacent to the edge (4a). Lower end portions (6) of the pair of sub wiring portions project to a position lower than the lower surface of the electrode junction portion (4). The lower end portions of the pair of sub wiring portions are joined to the circuit pattern (2) by the joining material (8) together with the lower surface of the electrode junction portion (4).

Description

Technical Field

[0001] This invention relates to semiconductor devices. Background Technology

[0002] Currently, semiconductor devices are equipped with terminals serving as external electrodes. One end of these terminals is bonded to a circuit pattern, and the other end is connected to an external device. With such semiconductor devices, a problem exists: when the bonding area between the circuit pattern and the terminal is small, the current density flowing through the bonding area becomes high. This causes localized heating at the bonding area when a large current flows, thereby reducing the lifespan of the semiconductor device.

[0003] For example, Patent Document 1 discloses a structure in which, in order to increase the bonding area between the electrode and the wiring pattern (equivalent to a circuit pattern), a pair of triangular bent portions are provided at one end of the electrode, and the pair of bent portions are bent in a manner that is upright relative to the bonding surface.

[0004] Patent Document 1: Japanese Utility Model Application Publication No. 02-077870

[0005] In the technology described in Patent Document 1, the lower ends of a pair of bent portions are joined in contact with the wiring pattern, thus increasing the joint surface area by the amount of the lower ends of the pair of bent portions. However, since the lower ends of the pair of bent portions have narrow areas, the increase in joint surface area is small, and therefore, the effect of suppressing heat generation at the joint between the wiring pattern and the electrode is insufficient. Summary of the Invention

[0006] Therefore, the object of the present invention is to provide a semiconductor device capable of suppressing heat generation at the junction between the circuit pattern and the terminals when a large current is flowing.

[0007] The semiconductor device of the present invention comprises: a circuit board having a circuit pattern on which semiconductor elements are mounted on its upper surface; and a terminal serving as an external electrode, one end of which is engaged with the circuit pattern and the other end of which is connected to an external device, the terminal having: an electrode engagement portion that is rectangular in shape when viewed from above, the lower surface of which is engaged with the circuit pattern by a bonding material; a main wiring portion that is erected from a first side of the electrode engagement portion; and a pair of secondary wiring portions that extend from both ends of the main wiring portion in the width direction along a second and a third side of the electrode engagement portion adjacent to the first side, the lower ends of the pair of secondary wiring portions protruding to a position lower than the lower surface of the electrode engagement portion, the lower ends of the pair of secondary wiring portions being engaged with the circuit pattern together with the lower surface of the electrode engagement portion by the bonding material.

[0008] The effects of the invention

[0009] According to the present invention, in addition to the bonding between the circuit pattern and the electrode junction achieved by the bonding material, the lower ends of a pair of sub-wiring portions are bonded to the circuit pattern by the bonding material while protruding to a position lower than the lower surface of the electrode junction. Therefore, compared with the case where the lower ends of a pair of sub-wiring portions are bonded to the circuit pattern by the bonding material, the bonding area between the circuit pattern and the terminal is increased. As a result, heat generation at the bonding area between the circuit pattern and the terminal when a large current is flowing can be suppressed.

[0010] The objectives, features, solutions, and advantages of the present invention will become clearer from the following detailed description and accompanying drawings. Attached Figure Description

[0011] Figure 1 This is a front view showing the state of the semiconductor device according to Embodiment 1 after the terminals are connected to the circuit pattern.

[0012] Figure 2 yes Figure 1 A sectional view along line AA.

[0013] Figure 3 This is a front view of the terminals of the semiconductor device according to Embodiment 2.

[0014] Figure 4 yes Figure 3 BB line section view.

[0015] Figure 5 This is a front view showing the state of the semiconductor device according to Embodiment 2 after the terminals are connected to the circuit pattern.

[0016] Figure 6 yes Figure 5 CC-line sectional view.

[0017] Figure 7 This is a front view showing the state of the semiconductor device according to Embodiment 3 after the terminals are joined with the circuit pattern.

[0018] Figure 8 yes Figure 7 DD-line sectional view.

[0019] Figure 9 This is a front view showing the state of the semiconductor device according to Embodiment 4 after the terminals are connected to the circuit pattern. Detailed Implementation

[0020] <Implementation Method 1>

[0021] <Structure of Semiconductor Devices>

[0022] Hereinafter, Embodiment 1 will be described using the accompanying drawings. Figure 1 This is a front view showing the state of the semiconductor device according to Embodiment 1 after the terminal 3 is connected to the circuit pattern 2. Figure 2 yes Figure 1 A sectional view along line AA.

[0023] like Figure 1 and Figure 2 As shown, the semiconductor device includes a circuit board 1, a semiconductor element (not shown), and terminals 3. The semiconductor device also includes an encapsulating resin (not shown) that encapsulates the circuit board 1 and the semiconductor element, and a housing (not shown) that fills the encapsulating resin, but these are the same as existing structures, so their description is omitted.

[0024] The circuit board 1 is formed, for example, using a ceramic with excellent thermal conductivity such as aluminum nitride or silicon nitride, or a resin with excellent thermal conductivity. A circuit pattern 2 is provided on the upper surface of the circuit board 1. The circuit pattern 2 is formed using a copper or aluminum alloy, and a semiconductor element (not shown) is mounted on the upper surface of the circuit pattern 2.

[0025] Terminal 3 is an external electrode, having one end that engages with circuit pattern 2 and another end that connects to an external device (not shown). Specifically, terminal 3 has an electrode engagement portion 4, a main wiring portion 5, a device connection portion 7, and a pair of auxiliary wiring portions 6.

[0026] The electrode junction 4, the main wiring section 5, the pair of auxiliary wiring sections 6 and the equipment connection section 7 are manufactured, for example, by processing a metal plate (hereinafter referred to as "the metal plate before processing") of a certain thickness formed using copper or copper alloy.

[0027] like Figure 2 As shown, the electrode junction 4 has opposing sides 4a and 4d and adjacent sides 4b and 4c, forming a rectangular shape when viewed from above. The lower surface of the electrode junction 4 is bonded to the circuit pattern 2 by a bonding material 8 such as solder.

[0028] like Figure 1 and Figure 2 As shown, the main wiring portion 5 is provided vertically on the first side 4a of the electrode bonding portion 4. Specifically, the main wiring portion 5 is formed by bending the portion that will become the main wiring portion 5 upward along the side 4a relative to the portion that will become the electrode bonding portion 4 in the metal plate before processing. Although not shown, the lower end of the main wiring portion 5 is located at the same height as the lower surface of the electrode bonding portion 4, and is bonded to the circuit pattern 2 together with the lower surface of the electrode bonding portion 4 by the bonding material 8.

[0029] like Figure 1 and Figure 2As shown, a pair of secondary wiring portions 6 extend from both ends of the main wiring portion 5 along the electrode joint portion 4, adjacent to edge 4a, which serves as the second edge and edge 4c, which serves as the third edge. Specifically, the pair of secondary wiring portions 6 are formed by bending the portion that will become the pair of secondary wiring portions 6 relative to the portion that will become the main wiring portion 5 in the metal plate before processing, in the direction of edges 4b and 4c. The pair of secondary wiring portions 6 are arranged upright along the outer periphery of edges 4b and 4c of the electrode joint portion 4. The upper ends of the pair of secondary wiring portions 6 are located higher than the upper ends of the main wiring portion 5.

[0030] On the other hand, the lower ends of the pair of secondary wiring portions 6 protrude to a position lower than the lower surface of the electrode junction portion 4. Therefore, with the lower ends of the pair of secondary wiring portions 6 protruding to a position lower than the lower surface of the electrode junction portion 4, they are joined to the circuit pattern 2 together with the lower surface of the electrode junction portion 4 and the lower end of the main wiring portion 5 by the bonding material 8.

[0031] The device connection portion 7 is formed by bending the portion that will become the device connection portion 7 relative to the portion that will become the main wiring portion 5 in the metal plate before processing toward the side 4d opposite to the side 4a of the electrode joint portion 4. The device connection portion 7 is connected to an external device (not shown). When viewed from above, the device connection portion 7 is rectangular in shape and extends from the upper end of the main wiring portion 5 toward the side 4d of the electrode joint portion 4.

[0032] Here, the electrode junction 4, the main wiring portion 5, and the pair of auxiliary wiring portions 6 correspond to one end of the terminal 3 that is connected to the circuit pattern 2, and the device connection portion 7 corresponds to the other end of the terminal 3 that is connected to an external device (not shown).

[0033] Additionally, a groove 9 is formed in the electrode junction 4, extending from the upper surface to the lower surface. For example... Figure 2 As shown, groove 9 is formed from the center of edge 4d of electrode junction 4 along a direction parallel to edges 4b and 4c to the center of edges 4b and 4c. Furthermore, groove 9 branches off at this location and extends to the center of edges 4b and 4c in a direction parallel to edges 4a and 4d. Groove 9 also extends from this location along edges 4b and 4c to edge 4a. Additionally, the width of groove 9 on its upper surface and the width on its lower surface are constant.

[0034] When joining the terminal 3 to the circuit pattern 2, after the bonding material 8 is placed on the upper surface of the circuit pattern 2, the terminal 3 is joined to the circuit pattern 2 by heating to a temperature exceeding the melting point of the bonding material 8 during the joining process. The bonding material 8, which is molten by heating, penetrates into the groove 9 and expands within the groove 9, thereby increasing the bonding strength between the electrode joint 4 and the circuit pattern 2.

[0035] <Effect>

[0036] As described above, in Embodiment 1, the semiconductor device includes: a circuit board 1 having a circuit pattern 2 on which semiconductor elements are mounted on the upper surface; and a terminal 3 serving as an external electrode, one end of which is joined to the circuit pattern 2 and the other end of which is connected to an external device. The terminal 3 has: an electrode junction portion 4 that is rectangular in shape when viewed from above, the lower surface of which is joined to the circuit pattern 2 by a bonding material 8; a main wiring portion 5 that is provided vertically from the side 4a of the electrode junction portion 4; and a pair of secondary wiring portions 6 that extend from both ends of the main wiring portion 5 in the width direction along the sides 4b and 4c of the electrode junction portion 4 adjacent to the side 4a. The lower ends of the pair of secondary wiring portions 6 protrude to a position lower than the lower surface of the electrode junction portion 4, and the lower ends of the pair of secondary wiring portions 6 are joined to the circuit pattern 2 together with the lower surface of the electrode junction portion 4 by the bonding material 8.

[0037] Therefore, in addition to the bonding between the circuit pattern 2 and the electrode junction 4 achieved by the bonding material 8, the lower ends of the pair of sub-wiring portions 6 are bonded to the circuit pattern 2 by the bonding material 8 while protruding further below the lower surface of the electrode junction 4. Thus, compared to the case where the lower ends of the pair of sub-wiring portions 6 are bonded to the circuit pattern 2 by the bonding material 8, the bonding area between the circuit pattern 2 and the terminal 3 is increased. This suppresses heat generation at the bonding area between the circuit pattern 2 and the terminal 3 when a large current is flowing. Therefore, long-term use of the semiconductor device is possible.

[0038] Furthermore, a groove 9 extending from the upper surface to the lower surface is formed in the electrode junction 4. Therefore, the bonding material 8, which is molten by heating, expands within the groove 9, thereby increasing the bonding strength between the electrode junction 4 and the circuit pattern 2. As a result, the reliability of the semiconductor device is improved.

[0039] <Implementation Method 2>

[0040] <Structure of Semiconductor Devices>

[0041] Next, the semiconductor device according to Embodiment 2 will be described. Figure 3 This is a front view of terminal 3A of the semiconductor device according to Embodiment 2. Figure 4 yes Figure 3 BB line section view. Figure 5 This is a front view showing the state of the semiconductor device according to Embodiment 2 after the terminal 3A is joined with the circuit pattern 2. Figure 6 yes Figure 5 A CC-line sectional view. Furthermore, in Embodiment 2, structural elements identical to those described in Embodiment 1 are labeled with the same reference numerals and their descriptions are omitted.

[0042] like Figure 3 and Figure 4 As shown, in Embodiment 2, the shape of the groove 9 is different from that in Embodiment 1. In Embodiment 1, the width of the upper surface side and the width of the lower surface side of the groove 9 are constant, but in Embodiment 2, the width of the upper surface side of the groove 9 is made wider than the width of the lower surface side.

[0043] The groove 9 has a widened portion 9a on the upper surface and a constant-width portion 9b on the lower surface. The widened portion 9a has a constant width on the upper surface of the groove 9 that is wider than the constant-width portion 9b. The constant-width portion 9b is formed on the lower surface of the groove 9 and communicates with the widened portion 9a. Furthermore, the constant-width portion 9b has a constant width that is narrower than the widened portion 9a. The bonding material 8, molten by heating, penetrates into the groove 9 and expands within it, thereby increasing the bonding strength between the electrode bonding portion 4 and the circuit pattern 2. By providing a concave widened portion 9a on the upper surface of the groove 9, the bonding material 8 filled in the groove 9 can achieve an anchoring effect.

[0044] Furthermore, regarding the portion of the groove 9 that extends from the center of edge 4d of the electrode junction 4 in a direction parallel to edges 4b and 4c to the center of edges 4b and 4c, and the portion that branches off in a direction parallel to edges 4a and 4d and extends to the center of edges 4b and 4c, the width of the upper surface side is wider than the width of the lower surface side. On the other hand, regarding the portion extending from the center of edges 4b and 4c to edge 4a, the width of the upper surface side and the width of the lower surface side are constant.

[0045] In addition, to effectively utilize the anchoring effect, it is preferable to use, for example... Figure 5 and Figure 6 As shown, the bonding material 8 filled in the groove 9 extends in such a way that it covers the area around the groove 9 on the upper surface of the electrode joint 4.

[0046] <Effect>

[0047] As described above, in the semiconductor device according to Embodiment 2, the width of the upper surface side of the trench 9 is wider than the width of the lower surface side, thus enabling the bonding material 8 filled in the trench 9 to have an anchoring effect, thereby further improving the bonding strength between the electrode junction 4 and the circuit pattern 2. As a result, the reliability of the semiconductor device is further improved.

[0048] <Implementation Method 3>

[0049] <Structure of Semiconductor Devices>

[0050] Next, the semiconductor device according to Embodiment 3 will be described. Figure 7 This is a front view showing the state of the semiconductor device according to Embodiment 3 after the terminal 3B is engaged with the circuit pattern 2. Figure 8 yes Figure 7The DD-line sectional view. Furthermore, in Embodiment 3, structural elements identical to those described in Embodiments 1 and 2 are labeled with the same reference numerals and their descriptions are omitted.

[0051] like Figure 7 and Figure 8 As shown, in Embodiment 3, the difference from Embodiment 1 is that a metal plate 20 is provided.

[0052] The metal plate 20, made of copper or aluminum alloy, is formed to the same thickness as the electrode junction 4, and has a smaller top-view profile than the electrode junction 4. Furthermore, the metal plate 20 is positioned above the electrode junction 4 in the portion surrounded by the main wiring portion 5 and a pair of sub-wiring portions 6, and is bonded to the main wiring portion 5 and the pair of sub-wiring portions 6 by a bonding material 20a such as solder. Additionally, the lower surface of the metal plate 20 is bonded to the upper surface of the electrode junction 4 by a bonding material 8a such as solder.

[0053] To reduce heat generation at the junction between circuit pattern 2 and terminal 3B when a large current flows, increasing the junction area between circuit pattern 2 and terminal 3B, as well as increasing the current path of terminal 3B, is effective. To increase the current path of terminal 3B, a metal plate 20 is provided above the electrode junction 4. Alternatively, a metal block thicker than the metal plate 20 can be used instead of the metal plate 20.

[0054] <Effect>

[0055] As described above, in the semiconductor device according to Embodiment 3, a metal plate 20 or a metal block is provided above the electrode junction 4, and the metal plate 20 or the metal block is connected to the main wiring section 5 and a pair of sub-wiring sections 6.

[0056] Therefore, compared with the case where no metal plate 20 or metal block is provided, the current path of terminal 3B is increased, and thus the resistance of terminal 3B is reduced, which can further suppress the heating of the joint between circuit pattern 2 and terminal 3B when a large current is flowing.

[0057] In addition, by providing the metal plate 20, the heat capacity of the terminal 3B is increased, thereby suppressing the temperature rise of the terminal 3B.

[0058] Furthermore, in Embodiment 2, terminal 3A can also be a metal plate 20 or a metal block. In this case, the same effect as in Embodiment 3 is obtained.

[0059] <Implementation Method 4>

[0060] <Structure of Semiconductor Devices>

[0061] Next, the semiconductor device according to Embodiment 4 will be described. Figure 9 This is a front view showing the state of the semiconductor device according to Embodiment 4 after the terminal 3C is connected to the circuit pattern 2. Furthermore, in Embodiment 4, structural elements that are identical to those described in Embodiments 1 to 3 are labeled with the same reference numerals and their descriptions are omitted.

[0062] like Figure 9 As shown, in Embodiment 4, the difference from Embodiment 1 is that a slit 21 is formed that extends from the surface of the main wiring section 5 toward the back side.

[0063] The slit 21 is formed by extending vertically along the center of the main wiring section 5 in the width direction.

[0064] As the current path for terminal 3C, there are paths through the main wiring section 5 and through a pair of auxiliary wiring sections 6. However, since the device connection section 7 is directly connected to the main wiring section 5, more current flows through the path through the main wiring section 5 compared to the path through the pair of auxiliary wiring sections 6. As a result, heat is easily generated in the main wiring section 5 when a large current flows. In order to reduce the current density in the main wiring section 5 and to make the current density between the main wiring section 5 and the pair of auxiliary wiring sections 6 uniform, a slit 21 is formed in the main wiring section 5.

[0065] Here, the slit 21 is formed to a size that allows the current density between the main wiring section 5 and a pair of auxiliary wiring sections 6 to be uniform.

[0066] <Effect>

[0067] As described above, in the semiconductor device according to Embodiment 4, a slit 21 extending in the vertical direction is formed in the main wiring section 5. Therefore, the current density of the main wiring section 5 can be reduced, and the current density between the main wiring section 5 and the pair of sub-wiring sections 6 can be made uniform. As a result, the heating of the main wiring section 5 when a large current is flowing can be suppressed.

[0068] Furthermore, the terminal 3A in Embodiment 2 and the terminal 3B in Embodiment 3 can also employ the slit 21. In this case, the same effect as in Embodiment 4 is achieved.

[0069] The invention has been described in detail, but the above description is illustrative in all respects and not limiting. It is to be understood that numerous modifications not illustrated can be conceived.

[0070] Furthermore, it is possible to freely combine the various implementation methods, or to appropriately modify or omit the various implementation methods.

[0071] Explanation of the label

[0072] 1 Circuit board, 2 Circuit pattern, 3, 3A, 3B, 3C terminals, 4 Electrode junction, 5 Main wiring section, 6 Sub-wiring section, 9 Slot, 20 Metal plate, 21 Slit.

Claims

1. A semiconductor device comprising: A circuit board having a circuit pattern on which semiconductor elements are mounted on its upper surface; and As an external electrode, one end of the terminal engages with the circuit pattern, and the other end connects to an external device. The terminal has: an electrode junction portion that is rectangular in shape when viewed from above, the lower surface of which is bonded to the circuit pattern by a bonding material; a main wiring portion that is erected from a first side of the electrode junction portion; and a pair of secondary wiring portions that extend from both ends of the main wiring portion in the width direction along a second and a third side of the electrode junction portion adjacent to the first side. The lower ends of the pair of sub-wiring portions protrude to a position lower than the lower surface of the electrode junction portion. The lower ends of the pair of sub-wiring portions are bonded to the circuit pattern together with the lower surface of the electrode junction portion through the bonding material.

2. The semiconductor device according to claim 1, wherein, A groove is formed at the electrode junction that extends from the upper surface toward the lower surface.

3. The semiconductor device according to claim 2, wherein, The width of the groove on the upper surface side is wider than the width of the groove on the lower surface side.

4. The semiconductor device according to any one of claims 1 to 3, wherein, A metal plate or metal block is disposed above the electrode junction. The metal plate or the metal block is connected to the main wiring section and a pair of the auxiliary wiring sections.

5. The semiconductor device according to any one of claims 1 to 4, wherein, A slit extending in the vertical direction is formed in the main wiring section.

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