Semiconductor device

Abstract

This semiconductor device comprises: a substrate having a circuit pattern; a semiconductor chip disposed on the circuit pattern; a sealing resin for sealing the semiconductor chip; and a strip-shaped terminal electrically connected to the semiconductor chip. The terminal includes a first portion positioned on the top side of the sealing resin, and a second portion connected to the first portion via a first bent part. A protrusion that protrudes upward and is disposed in a region between the tip of the first portion and the first bent part or in a region having the first bent part positioned therein is provided on the top surface of the sealing resin.

Description

Semiconductor Devices

[0001] This disclosure relates to a semiconductor device. This application claims priority to Japanese Application No. 2024-6728, filed January 19, 2024, and incorporates by reference all of the contents of said Japanese application.

[0002] A technology related to a power module has been disclosed (see, for example, Patent Document 1). The power module disclosed in Patent Document 1 includes a resin mold and a lead frame sealed inside the resin mold. The lead frame included in the power module disclosed in Patent Document 1 has a first region extending from a first surface of the resin mold, and a second region extending from the first region in a direction perpendicular to the first surface and sealed inside the resin mold. The first surface has a shape such that a bending angle, which is an angle formed by two adjacent regions of the lead frame sandwiching a bent portion where the first region is bent, is greater than 90 degrees.

[0003] WO2022 / 244080

[0004] A semiconductor device according to the present disclosure includes a substrate having a circuit pattern, a semiconductor chip disposed on the circuit pattern, a sealing resin for sealing the semiconductor chip, and a strip-shaped terminal electrically connected to the semiconductor chip. The terminal includes a first portion located above the sealing resin and a second portion connected to the first portion via a first bent portion. A protrusion protruding upward is provided on the upper surface of the sealing resin, and is located in a region between the tip of the first portion and the first bent portion or in a region where the first bent portion is located.

[0005] FIG. 1 is a schematic perspective view of a semiconductor device in a first embodiment. FIG. 2 is a schematic side view of the semiconductor device shown in FIG. 1. FIG. 3 is a schematic front view of the semiconductor device shown in FIG. 1. FIG. 4 is a schematic perspective view showing the semiconductor device shown in FIG. 1 in a state where a sealing resin and a nut, which will be described later, have been removed. FIG. 5 is a schematic side view of the semiconductor device shown in FIG. 4. FIG. 6 is a schematic front view of the semiconductor device shown in FIG. 4. FIG. 7 is a schematic cross-sectional view showing one of the steps when bending a terminal at a first bending portion to form a first portion. FIG. 8 is a schematic perspective view showing a state after bending the terminal and a state before bending the terminal.

[0006] [Problem to be solved by the present disclosure] In the lead frame disclosed in Patent Document 1, the region where the bolt is fastened can only be bent up to 90 degrees during the bending process when fastening to the bolt. This makes it extremely difficult to perform bending that takes springback into consideration, resulting in a low levelness of the region where the bolt is fastened. This results in a large variation in contact resistance when fastening to the bolt. In such a situation, the differences in characteristics between devices become significant. If an attempt is made to increase the levelness by forcibly bending the region beyond 90 degrees by increasing the bending load during bending, there is a risk of cracks occurring in the resin mold at the base of the bent portion. If a crack occurs in the resin mold, it becomes difficult to use the semiconductor device stably for a long period of time, and the reliability of the semiconductor device is impaired.

[0007] Therefore, one object is to provide a semiconductor device that can improve reliability while reducing differences in characteristics between devices.

[0008] Effect of the Present Disclosure According to such a semiconductor device, it is possible to improve reliability while reducing differences in characteristics between devices.

[0009] [Description of Embodiments of the Present Disclosure] (1) A semiconductor device according to the present disclosure includes a substrate having a circuit pattern, a semiconductor chip disposed on the circuit pattern, a sealing resin for sealing the semiconductor chip, and a strip-shaped terminal electrically connected to the semiconductor chip. The terminal includes a first portion located above the sealing resin and a second portion connected to the first portion via a first bent portion. A protrusion protruding upward is provided on the upper surface of the sealing resin, and is located in a region between a tip of the first portion and the first bent portion or in a region where the first bent portion is located.

[0010] According to the semiconductor device, a protrusion is provided on the upper surface of the sealing resin. The protrusion is located in the region between the tip of the first portion and the first bent portion or in the region where the first bent portion is located. This allows the protrusion to be used as a fulcrum when bending the tip of the terminal to form the first portion. Because the protrusion protrudes from the upper surface of the sealing resin, a bending load can be applied taking springback into account, allowing the terminal to be bent at an angle of 90 degrees or more. This bending increases the horizontality of the first portion. Therefore, the variation in contact resistance when fastened with a bolt can be reduced. Furthermore, the risk of cracks occurring in the sealing resin at the base of the bent portion due to bending can be significantly reduced. As described above, this semiconductor device can improve reliability while reducing differences in characteristics between devices.

[0011] (2) In the above (1), the protrusion may extend in the width direction of the terminal. In this way, the protrusion can be used as a fulcrum for bending the strip-shaped terminal across the width direction. Therefore, bending can be performed with even higher precision.

[0012] (3) In the above (1) or (2), the terminal may further include a third portion connected to the second portion via a second bent portion. This makes it easy to bend the terminal along the side surface of the sealing resin after forming the sealing resin to form a desired terminal shape. Therefore, productivity can be improved.

[0013] (4) In the above (3), the terminal may further include a fourth portion connected to the third portion via a third bent portion. This prevents the angles of the first bent portion, the second bent portion, and the third bent portion from becoming acute, making it easier to bend the terminal to obtain a desired shape. This further improves productivity.

[0014] [Details of the Embodiments of the Present Disclosure] Next, embodiments of the semiconductor device of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference characters, and description thereof will not be repeated.

[0015] First Embodiment A semiconductor device according to a first embodiment of the present disclosure will be described. FIG. 1 is a schematic perspective view of the semiconductor device according to the first embodiment. FIG. 2 is a schematic side view of the semiconductor device shown in FIG. 1. FIG. 3 is a schematic front view of the semiconductor device shown in FIG. 1. FIG. 4 is a schematic perspective view of the semiconductor device shown in FIG. 1 with a sealing resin and a nut, which will be described later, removed. FIG. 5 is a schematic side view of the semiconductor device shown in FIG. 4. FIG. 6 is a schematic front view of the semiconductor device shown in FIG. 4. In FIG. 1 and subsequent drawings, the direction indicated by arrow Z indicates the thickness direction of a semiconductor chip (the height direction of the semiconductor device), which will be described later, the direction indicated by arrow X indicates the vertical direction of the semiconductor device, and the direction indicated by arrow Y indicates the horizontal direction of the semiconductor device. The directions indicated by arrow X, arrow Y, and arrow Z are all orthogonal to each other. FIG. 2 is a view seen from the direction indicated by arrow II (the direction indicated by arrow X) in FIG. 1. FIG. 3 is a view seen from the direction indicated by arrow III (the direction indicated by arrow Y) in FIG. 1. FIG. 5 is a view seen from the direction indicated by arrow V (the direction indicated by arrow X) in FIG. 4. FIG. 6 is a view seen from the direction indicated by the arrow VI in FIG. 4 (the direction indicated by the arrow Y).

[0016] 1, 2, 3, 4, 5, and 6, a semiconductor device 10a according to a first embodiment includes a substrate 11a, semiconductor chips 12a, 12b, 12c, 12d, 12e, and 12f, a sealing resin 13a, and terminals 14a, 14b, 14c, and 14d. In this embodiment, semiconductor device 10a includes six semiconductor chips: 12a, 12b, 12c, 12d, 12e, and 12f, and four terminals: 14a, 14b, 14c, and 14d. Semiconductor device 10a further includes two wiring boards 15a and 15b, and a heat sink 16a. Terminals 14a, 14b, 14c, and 14d are also referred to as lead frames. In this embodiment, for example, the terminals 14a and 14d can be applied as O terminals, the terminal 14b as a P terminal, and the terminal 14c as an N terminal.

[0017] The substrate 11a includes an insulating substrate 21a and a pair of metal plates 22a and 22b arranged on both sides of the insulating substrate 21a in the thickness direction. That is, the substrate 11a has a laminated structure in which the insulating substrate 21a is sandwiched between the pair of metal plates 22a and 22b. A circuit pattern 23a is formed on one of the metal plates 22a. That is, the substrate 11a has the circuit pattern 23a. A heat sink 16a is attached to the other metal plate 22b in the thickness direction.

[0018] The circuit pattern 23a is composed of five circuit boards 24a, 24b, 24c, 24d, and 24e, which are spaced apart from one another on the insulating substrate 21a.

[0019] The semiconductor chip 12a may be, for example, a transistor, specifically a vertical transistor such as a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) or an Insulated Gate Bipolar Transistor (IGBT). In this embodiment, the semiconductor chip 12a is a MOSFET. Note that a diode, specifically, for example, an SBD (Schottky Barrier Diode), may also be used as the semiconductor chip 12a. In this embodiment, the semiconductor chip 12a is rectangular when viewed in the thickness direction (Z direction). Note that the configurations of the other semiconductor chips 12b, 12c, 12d, 12e, and 12f are similar to that of the semiconductor chip 12a, and therefore description thereof will be omitted.

[0020] The semiconductor chips 12a, 12b, and 12c are mounted on the circuit board 24a at intervals in the Y direction. The semiconductor chips 12a, 12b, and 12c are bonded to the circuit board 24a with bonding materials. This electrically connects the drain electrodes of the semiconductor chips 12a, 12b, and 12c to the circuit board 24a. The semiconductor chips 12d, 12e, and 12f are mounted on the circuit board 24d at intervals in the Y direction. The semiconductor chips 12d, 12e, and 12f are bonded to the circuit board 24d with bonding materials. This electrically connects the drain electrodes of the semiconductor chips 12d, 12e, and 12f to the circuit board 24d. A conductive bonding material such as solder is used as the bonding material. The same applies to the bonding materials described below.

[0021] The source electrodes of the semiconductor chips 12a, 12b, and 12c are each bonded to the wiring board 15a with a bonding material. This electrically connects the source electrodes of the semiconductor chips 12a, 12b, and 12c to the wiring board 15a. The source electrodes of the semiconductor chips 12d, 12e, and 12f are each bonded to the wiring board 15b with a bonding material. This electrically connects the source electrodes of the semiconductor chips 12d, 12e, and 12f to the wiring board 15b. The wiring board 15a and the circuit board 24b are also bonded with a bonding material. This electrically connects the source electrodes of the semiconductor chips 12a, 12b, and 12c to the circuit board 24b via the wiring board 15a. The wiring board 15b and the circuit board 24a are also bonded with a bonding material. As a result, the source electrodes of the semiconductor chips 12d, 12e, and 12f are electrically connected to the circuit board 24a via the wiring board 15b.

[0022] The gate electrodes of the semiconductor chips 12a, 12b, and 12c are bonded to the circuit board 24c by wires 25a, 25b, and 25c, respectively. This electrically connects the gate electrodes of the semiconductor chips 12a, 12b, and 12c to the circuit board 24c. The gate electrodes of the semiconductor chips 12d, 12e, and 12f are bonded to the circuit board 24e by wires 25d, 25e, and 25f, respectively. This electrically connects the gate electrodes of the semiconductor chips 12d, 12e, and 12f to the circuit board 24e. Details of other wiring and electrical connections in the semiconductor device 10a will not be described here.

[0023] The sealing resin 13a is disposed on the substrate 11a. In this embodiment, the sealing resin 13a is disposed on the heat sink 16a so as to expose one surface 17a in the thickness direction of the heat sink 16a and a pair of side surfaces 18a located in the X direction. The sealing resin 13a seals components disposed on the circuit pattern 23a, including the semiconductor chips 12a, 12b, 12c, 12d, 12e, and 12f. The sealing resin 13a may be, for example, a thermosetting resin, specifically, an epoxy resin.

[0024] The sealing resin 13a includes a top surface 19a, a first side surface 45a, and a second side surface 45b. In this embodiment, the sealing resin 13a is flat except for the locations where the protrusions 36a and 36b (described later) are provided. The first side surface 45a includes a first inclined surface 46a and a second inclined surface 47a extending from the first inclined surface 46a. The first inclined surface 46a and the second inclined surface 47a are each inclined with respect to the top surface 19a. The first inclined surface 46a is inclined so as to widen outward from the end of the top surface 19a to the connection with the second inclined surface 47a. The second inclined surface 47a is inclined so as to narrow inward from the portion connecting to the first inclined surface 46a toward the region where the heat sink 16a is located. Like the first side surface 45a, the second side surface 45b also includes a first inclined surface 46b and a second inclined surface 47b extending from the first inclined surface 46b.

[0025] The terminal 14a is made of a strip-shaped metal plate, which is formed by bending the strip-shaped metal plate. The other terminals 14b, 14c, and 14d have the same structure as the terminal 14a, and therefore their description will be omitted.

[0026] One end 26a of terminal 14a is located above sealing resin 13a, and the other end 27a is bonded to circuit pattern 23a. Specifically, the other end 27a of terminal 14a is bonded to circuit board 24a. That is, terminal 14a is electrically connected to the drain electrodes of each of semiconductor chips 12a, 12b, and 12c. One end 26b of terminal 14b is located above sealing resin 13a, and the other end 27b is bonded to circuit board 24b of circuit pattern 23a. That is, terminal 14b is electrically connected to the source electrodes of each of semiconductor chips 12a, 12b, and 12c. One end 26c of terminal 14c is located above sealing resin 13a, and the other end 27c is bonded to circuit board 24d of circuit pattern 23a. That is, terminal 14c is electrically connected to the drain electrodes of semiconductor chips 12d, 12e, and 12f. One end 26d of terminal 14d is located above sealing resin 13a, and the other end 27d is joined to circuit board 24e of circuit pattern 23a. That is, terminal 14d is electrically connected to the source electrodes of semiconductor chips 12d, 12e, and 12f. Round through-holes 28a, 28b, 28c, and 28d are formed in one end 26a, 26b, 26c, and 26d of terminals 14a, 14b, 14c, and 14d, respectively.

[0027] The terminal 14a includes a first portion 31a located above the sealing resin 13a and a second portion 32a connected to the first portion 31a via a first bent portion 41a. The terminal 14a also includes a third portion 33a connected to the second portion 32a via a second bent portion 42a. The third portion 33a is located on the opposite side of the second portion 32a from the first portion 31a. The terminal 14a also includes a fourth portion 34a connected to the third portion 33a via the third bent portion 43a. The fourth portion 34a is located on the opposite side of the second portion 32a from the third portion 33a. The fourth portion 34a faces the first portion 31a. In this embodiment, the terminal 14a is configured such that the first portion 31a, the second portion 32a, the third portion 33a, and the fourth portion 34a are connected in the longitudinal direction. The first bent portion 41a, the second bent portion 42a, and the third bent portion 43a are disposed in the region where the respective portions are connected. Of the terminal 14a, the second portion 32a, the third portion 33a, and the fourth portion 34a are exposed outside the sealing resin 13a. The second portion 32a is shaped to follow the first inclined surface 46a, and the third portion 33a is shaped to follow the second inclined surface 47a. That is, the angle of inclination of the second portion 32a is the same as the angle of inclination of the first inclined surface 46a, and the angle of inclination of the third portion 33a is the same as the angle of inclination of the second inclined surface 47a. Like the terminal 14a, the terminal 14b includes the first portion 31b, the second portion 32b, the third portion 33b, the fourth portion 34b, the first bent portion 41b, the second bent portion 42b, and the third bent portion 43b. The other terminals 14c and 14d have the same configuration.

[0028] Here, a protrusion 36a that protrudes upward is provided on the upper surface 19a of the sealing resin 13a. The protrusion 36a is disposed in a region between the tip 35a of the first portion 31a of the terminal 14a and the first bent portion 41a. In this embodiment, the protrusion 36a extends in the width direction (X direction) of the terminal 14a. The protrusion 36a is rib-shaped. A rib-shaped protrusion 36b is also provided on the upper surface 19a of the sealing resin 13a in a region between the tip 35b of the first portion 31b of the terminal 14b and the first bent portion 41b. Protrusions 36a with similar configurations are also provided in corresponding regions of the other terminals 14c and 14d.

[0029] Furthermore, a recess 37a is provided on the upper surface 19a of the sealing resin 13a between the protrusion 36a and the tip 35a of the first portion 31a. Similarly, a recess 37b is provided on the upper surface 19a of the sealing resin 13a between the protrusion 36b and the tip 35b of the first portion 31b. Recesses of similar configurations are also provided in the corresponding regions of the other terminals 14c and 14d.

[0030] A manufacturing method for the semiconductor device 10a will now be briefly described. First, a substrate 11a is prepared on which a heat sink 16a is attached and a circuit pattern 23a is formed. Then, the semiconductor chips 12a, 12b, 12c, 12d, 12e, and 12f, as well as the wiring boards 15a and 15b, are arranged, and the components are electrically connected by bonding or the like. The other ends 27a, 27b, 27c, and 27d of the unbent, strip-shaped terminals 14a, 14b, 14c, and 14d are also bonded to the circuit pattern 23a. The heat sink is then enclosed so that one surface and both side surfaces in the thickness direction are exposed, and filled with uncured resin. The resin is then cured by heating or the like to form the encapsulating resin 13a. At this time, the protrusions 36a and 36b are formed on the upper surface 19a of the encapsulating resin 13a. Furthermore, a fitting hole 38a into which the nut 29a is fitted is provided on the upper surface 19a of the sealing resin 13a, and the nut 29a is also fitted into this fitting hole 38a.

[0031] Thereafter, terminals 14a, 14b, 14c, and 14d are each bent to conform to the outer shape of the side surface of sealing resin 13a. First, terminal 14a is bent at third bend 43a, then at second bend 42a, and finally at first bend 41a to form first portion 31a. FIG. 7 is a schematic cross-sectional view showing one of the steps for forming first portion 31a by bending terminal 14a at first bend 41a. FIG. 7 is a cross-sectional view taken along the Y-Z plane including terminal 14a. FIG. 8 is a schematic perspective view showing the state after terminal 14a is bent and before terminal 14d is bent. Referring to FIGS. 7 and 8 together, protrusion 36a is used when bending at first bend 41a. In this case, the tip of protrusion 36a is used as fulcrum 39a to bend toward the top surface 19a of sealing resin 13a, forming first portion 31a. Here, the bending angle θ is 90 degrees or more. The surface of the first portion 31a that faces the upper surface 19a when bending is indicated by a dashed line. This angle θ is an angle that increases horizontality in consideration of the effect of springback. The same applies to the other terminals 14b, 14c, and 14d. Of course, the bending order may start from any terminal.

[0032] In the semiconductor device 10a, a protrusion 36a is provided on the upper surface 19a of the sealing resin 13a. The protrusion 36a is located in the region between the tip 35a of the first portion 31a and the first bent portion 41a. This allows the protrusion 36a to be used as a fulcrum 39a when bending the tip 35a of the terminal 14a to form the first portion 31a. Because the protrusion 36a protrudes from the upper surface 19a of the sealing resin 13a, a bending load can be applied taking springback into account, allowing for bending of 90 degrees or more. This bending increases the horizontality of the first portion 31a. This reduces the variation in contact resistance when fastened with a bolt. Furthermore, the risk of cracks occurring in the sealing resin 13a at the base of the bent portion due to bending can be significantly reduced. As a result, the semiconductor device 10a can improve reliability while reducing differences in characteristics between devices.

[0033] In this embodiment, the protrusion 36a extends in the width direction of the terminal 14a. Therefore, the protrusion 36a can be used as a fulcrum for bending the entire width of the strip-shaped terminal 14a. This allows for even higher accuracy in bending.

[0034] In this embodiment, the terminal 14a includes a third portion 33a that is connected to the second portion 32a via the second bent portion 42a. Therefore, after the sealing resin 13a is formed, the terminal 14a can be easily bent along the side surface of the sealing resin 13a to form a desired terminal shape, thereby improving productivity.

[0035] In this embodiment, the terminal 14a includes a fourth portion 34a that is connected to the third portion 33a via the third bent portion 43a. This prevents the angles of the first bent portion 41a, the second bent portion 42a, and the third bent portion 43a from becoming acute, making it easier to bend the terminal 14a to obtain a desired shape. This further improves productivity.

[0036] In the above embodiment, the protruding portion 36a is arranged in the region between the tip 35a of the first portion 31a and the first bent portion 41a, but this is not limiting, and the protruding portion 36a may be arranged in the region where the first bent portion 41a is located. That is, the protruding portion 36a may be arranged in the region between the tip 35a of the first portion 31a and the first bent portion 41a or in the region where the first bent portion 41a is located.

[0037] (Other Embodiments) In the above embodiment, the protrusion extends in the width direction of the terminal, but this is not limiting, and the protrusion may extend in the longitudinal direction of the terminal. Furthermore, a plurality of protrusions may be provided on each terminal, spaced apart in the width direction or in a direction intersecting the width direction. The tip of the protrusion may be rounded when viewed from the side, or may have an acute or obtuse angle.

[0038] In the above embodiment, the terminal includes the third portion and the fourth portion, but this is not limiting, and the terminal may be configured not to include a portion corresponding to the third portion or the fourth portion. For example, if the side surface is parallel to the X-Z plane, the terminal may be formed by bending in three stages.

[0039] It should be understood that the embodiments disclosed herein are illustrative in all respects and are not limiting in any respect. The scope of the present invention is defined not by the above description but by the claims, and it is intended to include all modifications within the meaning and scope of the claims.

[0040] 10a semiconductor device, 11a substrate, 12a, 12b, 12c, 12d, 12e, 12f semiconductor chip, 13a sealing resin, 14a, 14b, 14c, 14d terminal, 15a, 15b wiring board, 16a heat sink, 17a surface, 18a side, 19a upper surface, 21a insulating substrate, 22a, 22b metal plate, 23a circuit pattern, 24a, 24b, 24c, 24d, 24e circuit board, 25a, 25b, 25c, 25d, 25e, 25f wire, 26a, 26b, 26c, 26d, 27a, 27b, 27c, 27d end, 28a, 28b, 28c, 28d through hole, 29a nut, 31a, 31b First portion, 32a, 32b Second portion, 33a, 33b Third portion, 34a, 34b Fourth portion, 35a, 35b Tip, 36a, 36b Projection, 37a, 37b Recess, 38a Fitting hole, 39a Fulcrum, 41a, 41b First bent portion, 42a, 42b Second bent part, 43a, 43b Third bent part, 45a first side surface, 45b second side surface, 46a, 46b first inclined surface, 47a, 47b second inclined surface, θ angle.

Claims

1. A semiconductor device comprising: a substrate having a circuit pattern; a semiconductor chip disposed on the circuit pattern; a sealing resin for sealing the semiconductor chip; and a strip-shaped terminal electrically connected to the semiconductor chip, wherein the terminal includes a first portion located above the sealing resin and a second portion connected to the first portion via a first bending portion, and a protruding portion protruding upward is provided on an upper surface of the sealing resin in a region between a tip of the first portion and the first bending portion or in a region where the first bending portion is located.

2. The semiconductor device according to claim 1, wherein the protruding portion extends in a width direction of the terminal.

3. The semiconductor device according to claim 1 or 2, wherein the terminal further includes a third portion connected to the second portion via a second bending portion.

4. The semiconductor device according to claim 3, wherein the terminal further includes a fourth portion connected to the third portion via a third bending portion.

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