Semiconductor device and method for manufacturing a semiconductor device

Abstract

It is an object to provide a technology that can prevent misalignment when an electrode terminal is mounted on a circuit pattern of an insulating substrate. A semiconductor device comprises: an insulating substrate (1) on the upper surface of which a circuit pattern (3) is formed; a semiconductor element (5) mounted on the circuit pattern (3); and an electrode terminal (6) having a connection point (6a) connected to an upper surface of the circuit pattern (3) and electrically connected to the semiconductor element (5), wherein the circuit pattern (3) has a fitting part, and wherein the connection point (6a) of the electrode terminal (6) has a fitted part to be fitted into the fitting part.

Description

Technical FieldThe present disclosure relates to a semiconductor device and a method of manufacturing the semiconductor device.Prior ArtConventionally, forming pads each having a step on an insulating substrate and mounting a wiring (corresponding to an electrode terminal) to correspond to the step of each of the pads prevents misalignment of wirings (see, for example, Patent Document 1).Prior Art DocumentsPatent DocumentPatent Document 1: Japanese Patent Application Laid-Open No. H5-67871SummaryProblem to be Solved by the InventionThe steps for forming the pads described in Patent Document 1 are provided to prevent a flow of solder in a reflow process. Each of the steps is designed to be larger than a connection of the line by the solder which is applied to the step. Therefore, misalignment occurs when the leads are mechanically or manually mounted on the steps of the pads. When misalignment occurs, inferior quality of a semiconductor device has been a problem.The present disclosure has an object of providing a technology that can suppress misalignment when an electrode terminal is mounted on a circuit structure of an insulating substrate.Means for Solving the ProblemA semiconductor device according to the present disclosure includes: an insulating substrate on the upper surface of which a circuit pattern is formed; and an electrode terminal having a connection site connected to an upper surface of the circuit pattern, the circuit pattern having a fitting part, and the connection site of the electrode terminal having a fitted part to be fitted into the fitting part.Effects of the InventionThe present disclosure can suppress misalignment when an electrode terminal is mounted on a circuit structure of an insulating substrate by fitting a fitted part of the electrode terminal into a fitting part of the circuit structure.The objects, features, aspects, and advantages of this disclosure will become more apparent from the following detailed description and the accompanying drawings.Brief Description of the FiguresFIG. 1 is a schematic cross-sectional view illustrating a connection location of an electrode terminal included in a semiconductor device according to Embodiment 1 and the vicinity thereof. FIG. 2 is a schematic cross-sectional view illustrating a connection location of an electrode terminal included in a semiconductor device according to Embodiment 2 and the vicinity thereof. FIG. 3 is a schematic cross-sectional view of a joint of an electrode terminal included in a semiconductor device according to Embodiment 3 and its vicinity before crimping. FIG. 4 is a schematic cross-sectional view of the connection location of the electrode terminal included in the semiconductor device according to Embodiment 3 and the vicinity thereof after crimping.DESCRIPTION OF THE EMBODIMENTS[Embodiment 1]Embodiment 1 will be described below with reference to the figures. FIG. 1 is a schematic cross-sectional view illustrating a connection location 6 aof an electrode terminal 6 included in a semiconductor device according to Embodiment 1 and the vicinity thereof.As illustrated in FIG. 1, the semiconductor device includes an insulating substrate 1, a semiconductor element 5, and the electrode terminal 6. The insulating substrate 1 includes an insulating layer 2, circuit patterns 3, and a base plate 4. The insulating layer 2 is formed of, for example, ceramic. The plurality of conductive circuit patterns 3 are disposed on the upper surface of the insulating layer 2. The circuit patterns 3 are formed of Cu, for example. The base plate 4 is disposed on the lower surface of the insulating layer 2.The electrode terminal 6 is connected to the upper surface of the circuit pattern 3 by a bonding material 7. Moreover, a plurality of the semiconductor elements 5 such as an insulated gate bipolar transistor (IGBT) and a free wheeling diode (FWDI) are connected by solder (not illustrated) to the upper surfaces of the circuit patterns 3 adjacent to the circuit pattern 3 to which the electrode terminal 6 is connected. Each of the adjacent circuit patterns 3 is connected to the circuit pattern 3 by an aluminum wire (not illustrated). Further, the insulating substrate 1, the semiconductor elements 5, and the electrode terminal 6 are protected by a case (not illustrated) and a sealant such as a gel (not illustrated). A metal oxide semiconductor field effect transistor (MOSFET) may be mounted as the semiconductor element 5 instead of the IGBT. Further, a Schottky diode (SBD) may be mounted instead of the FWDI.The electrode terminal 6 is electrically connected to the semiconductor elements 5 by aluminum wires (not illustrated). The electrode terminal 6 is formed of Al, for example. The electrode terminal 6 has a joint 6 aformed at one end of the electrode terminal 6, and a bent part 6 bwhich is bent upward from the joint 6 a. The joint 6 ais a part extending parallel to the upper surface of the circuit pattern 3, and is a part connected to the upper surface of the circuit pattern 3. The lower surface of the joint 6a is flat, and is in contact with the circuit pattern 3 over the entire surface. The joint 6a has a depending surface 6c which projects downward from the outer circumferential surface. The depending surface 6 cis formed over a part of the entirety of the outer circumferential surface of the connection portion 6 aof the electrode terminal 6. When the depending surface 6 cis formed only on a part of the outer circumferential surface of the joint 6 a, the depending surface 6 cis preferably formed on the end side of the joint 6 a. The end side of the joint 6a is at the left in FIG. 1, that is, opposite to the bent part 6b.A recess 3a into which the depending surface 6c can be fitted is formed in a part of the upper surface of the circuit pattern 3 to which the electrode terminal 6 is connected. Specifically, the end portion of the depending surface 6 cis fitted into the recess 3 a. The recess 3 ais located at a position facing the depending surface 6 con the upper surface of the circuit pattern 3, and is sized such that the end part of the depending surface 6 cmay be fitted. Fitting the depending surface 6 cin the recess 3 apositions the electrode terminal 6 by the circuit pattern 3.The bonding material 7 is placed so as to cover the connection site 6 aof the electrode terminal 6 and a part of the bent part 6 b. The bonding material 7 is, for example, a solder.Next, a method of forming the depending surface 6 cincluded in the method of manufacturing the semiconductor device will be described simply without figures. First, a metal plate to be the electrode terminal 6 is placed in a die. Next, a metal plate is punched with a clearance between the die and an upper die facing the die to plastic-deform the metal plate. This completes the electrode terminal 6 with the depending surface 6c. In typical semiconductor devices, the electrode terminal 6 is manufactured by minimizing the distance between the lower die and the upper die to prevent the depending surface 6 cfrom being formed. In Embodiment 1, the electrode terminal 6 having the depending surface 6 cis manufactured by expanding the distance between the lower die and the upper die more than that of the typical semiconductor devices.The semiconductor device according to Embodiment 1 includes: the insulating substrate 1 on the upper surface of which the circuit pattern 3 is formed; and the electrode terminal 6 including the joint 6 athat is connected to an upper surface of the circuit pattern 3, the circuit pattern 3 including a fitting part, and the joint 6 aof the electrode terminal 6 including a fitted part to be fitted into the depending surface 6 c. Specifically, the fitting part is the recess 3 aformed in the circuit pattern 3, and the fitted part is the depending surface 6 cthat protrudes downward from the outer circumferential surface of the joint 6 aof the electrode terminal 6, and the fitting of the depending surface 6 cin the recess 3 apositions the electrode terminal 6 through the circuit pattern 3.Therefore, fitting the depending surface 6 cas a fitted part of the electrode terminal 6 into the recess 3 aas a fitting part of the circuit pattern 3 can suppress misalignment when the electrode terminal 6 is mounted on the circuit pattern 3 of the insulating substrate 1. This can also suppress misalignment when the electrode terminal 6 is connected to the circuit pattern 3.Forming the depending surface 6 con the electrode terminal 6 facilitates forming a first solder fillet. This improves not only the yield of the semiconductor devices but also the durability.A method of manufacturing the semiconductor device according to Embodiment 1 includes disposing a metal plate to be the electrode terminal 6 in a die, and punching the metal plate with a clearance between the die and an upper die facing the die to plastic-deform the metal plate and form the depending surface 6 c. Since the depending surface 6 cmay be formed in a punching process for manufacturing the electrode terminal 6, an increase in manufacturing processes may be suppressed.[Embodiment 2]Next, a semiconductor device according to Embodiment 2 will be described. FIG. 2 is a schematic cross-sectional view illustrating the connection location 6 aof the electrode terminal 6 included in the semiconductor device according to Embodiment 2 and the vicinity thereof. In Embodiment 2, the same reference numerals are assigned to the same constituent elements described in Embodiment 1, and the description thereof is omitted.As illustrated in FIG. 2, the joint 6 aof the electrode terminal 6 does not include the depending surface 6 c(see FIG. 1 ), and the entire lower end part of the joint 6 afunctions as a fitted part.The recess 3 aformed in the circuit pattern 3 has a size such that the entire lower end part of the joint 6 acan be fitted. The maximum depth of the recess 3 ais less than or equal to half the thickness of the circuit pattern 3.Preferably, the maximum depth of the recess 3 ais one quarter or more and half or less of the thickness of the circuit pattern 3.In the semiconductor device according to Embodiment 2, the fitting part is the recess 3 aformed in the circuit pattern 3, the maximum depth of the recess 3 ais less than or equal to a half thickness of the circuit pattern 3, the fitted part is the lower end part of the connection site 6 aof the electrode terminal 6, and the fitting of the lower end part of the connection site 6 aof the electrode terminal 6 into the recess 3 apositions the electrode terminal 6 through the circuit pattern 3.Thus, fitting the lower end part of the joint 6 aas a fitted part of the electrode terminal 6 into the recess 3 aas a fitting part of the circuit pattern 3 can suppress misalignment when the electrode terminal 6 is mounted on the circuit pattern 3 of the insulating substrate 1. This can also suppress misalignment when the electrode terminal 6 is connected to the circuit pattern 3.Further, a reduction in thickness of a part of the circuit pattern 3 to which the electrode terminal 6 is connected reduces the heat resistance from the electrode terminal 6 to radiation fins (not illustrated) to be connected to the lower surface of the base plate 4. This facilitates dissipation of the heat generated in the electrode terminal 6 through the radiation fins.[Embodiment 3]Next, a semiconductor device according to Embodiment 3 will be described. FIG. 3 is a schematic cross-sectional view of the joint 6 aof the electrode terminal 6 included in the semiconductor device according to Embodiment 3 and the vicinity thereof before crimping. FIG. 4 is a schematic cross-sectional view of the joint 6 aof the electrode terminal 6 included in the semiconductor device according to Embodiment 3 and the vicinity thereof after crimping. In Embodiment 3, the same reference numerals are assigned to the same constituent elements described in Embodiments 1 and 2, and the description thereof is omitted.As illustrated in FIG. 3, a protrusion 8 protruding upward is formed on the upper surface of the circuit pattern 3 in Embodiment 3. The protrusion 8 is formed as a cylindrical column or a cylinder, and is formed integrally with the circuit pattern 3. The vertical length of the protrusion 8 is greater than the thickness of the connection portion 6 aof the electrode terminal 6.The connection portion 6 aof the electrode terminal 6 has a through hole 6 a, into which the protrusion 8 can be fitted. The diameter of the through hole 6d is formed slightly larger than that of the projection 8 to allow deformation of the projection 8 when the end portion of the projection 8 is crimped. The fitting of the protrusion 8 into the through hole 6 dpositions the electrode terminal 6 through the circuit pattern 3. This connects the electrode terminal 6 to the circuit pattern 3 without using the bonding material 7 (see FIG. 1 ). Here, the protrusion 8 corresponds to a fitting part, and the through hole 6 dcorresponds to a fitted part.Next, a method of crimping the end part of the protrusion 8 included in the method of manufacturing the semiconductor device will be described simply. First, the electrode terminal 6 is disposed on the circuit pattern 3 such that the through hole 6 dof the joint 6 ais fitted into the protrusion 8 on the circuit pattern 3 as illustrated in FIG. 3. Next, a force is applied to the end part of the protrusion 8 using an ultrasonic joining tool (not illustrated). As a result, the end portion of the projection 8 is crimped as illustrated in FIG. 4.As described above, in the semiconductor device according to Embodiment 3, the fitting part is the protrusion 8 formed on the circuit pattern 3, the fitted part is the through hole 6 dformed in the connection site 6 aof the electrode terminal 6, and the fitting of the through hole 6 din the protrusion 8 positions the electrode terminal 6 through the circuit pattern 3.Thus, fitting the through hole 6 dof the joint 6 aas a fitted part of the electrode terminal 6 into the protrusion 8 as a fitting part of the circuit pattern 3 can suppress misalignment when the electrode terminal 6 is mounted on the circuit pattern 3 of the insulating substrate 1. This can also suppress misalignment when the electrode terminal 6 is connected to the circuit pattern 3.Since the end part of the protrusion 8 is crimped while the end part of the protrusion 8 is fitted into the through hole 6 d, the electrode terminal 6 can be connected to the circuit pattern 3 without using the connecting material 7.Even when the electrode terminal 6 formed of Al is connected to the circuit pattern 3 formed of Cu, which has been conventionally difficult without raising the temperature, electrical connection of the electrode terminal 6 to the circuit pattern 3 is facilitated. Moreover, crimping the end part of the protrusion 8 while the end part of the protrusion 8 is fitted into the through hole 6 dincreases the connection reliability between the electrode terminal 6 and the circuit pattern 3.Since the protrusion 8 is integrated with the circuit pattern 3, connecting the protrusion 8 to the circuit pattern 3 is unnecessary. This further improves the connection reliability between the electrode terminal 6 and the circuit pattern 3.Since the protrusion 8 is formed as a cylindrical column or a cylinder, the protrusion 8 can be brought into close contact with the through hole 6 dby uniform deformation of the protrusion 8. This further reinforces the connection of the electrode terminal 6 to the circuit structure 3.While the disclosure has been described in detail, the foregoing description is illustrative in all aspects and does not limit the present disclosure. Therefore, various modifications that have already been illustrated are devised.Embodiments may be freely combined, and appropriately modified or omitted.List of reference characters1 Insulating substrate 3 Circuit pattern 3 a 6 Electrode terminal 6 a 6 c Surface 6 dThrough hole 8

Claims

A semiconductor device comprising: • an insulating substrate on the upper surface of which a circuit pattern is formed; and • an electrode terminal having a connection site connected to an upper surface of the circuit pattern, wherein • the circuit pattern has a fitting part, and • the connection site of the electrode terminal has a fitted part to be fitted into the fitting part.The semiconductor device according to claim 1, wherein • the fitting part is a recess formed in the circuit structure, • the fitted part is a depending surface that protrudes downward from an outer circumferential surface of the connection site of the electrode terminal, and • the fitting of the depending surface into the recess positions the electrode terminal through the circuit structure.The semiconductor device according to claim 1, wherein • the fitting part is a recess formed in the circuit pattern, • a maximum depth of the recess is less than or equal to half a thickness of the circuit pattern, • the fitted part is a lower end part of the connection site of the electrode terminal, and • the fitting of the lower end part of the connection site of the electrode terminal into the recess positions the electrode terminal through the circuit pattern.The semiconductor device according to claim 1, wherein • the fitting part is a protrusion formed on the circuit pattern, • the fitted part is a through hole formed in the connection location of the electrode terminal, and • the fitting of the through hole into the protrusion positions the electrode terminal through the circuit pattern.The semiconductor device according to claim 4, wherein an end part of the protrusion is crimped while the end part of the protrusion is fitted into the through hole.The semiconductor device according to claim 4 or 5, wherein the protrusion is integrated with the circuit structure.The semiconductor device according to any one of claims 4 to 6, wherein the protrusion is formed as a cylindrical column or a cylinder.A method for manufacturing the semiconductor device according to claim 2, the method comprising: • disposing a metal plate, which becomes the electrode terminal, in a die, and • punching the metal plate with a clearance between the die and an upper die facing the die to plastic deform the metal plate and form the depending surface.A method for manufacturing the semiconductor device according to claim 5, the method comprising: • disposing the electrode terminal on the circuit pattern such that the through hole of the joint is fitted into the protrusion of the circuit pattern, and • applying a force to the end part of the protrusion using an ultrasonic bonding tool to crimp the end part of the protrusion.

Images