JP2018014464A - Positioning jig and semiconductor device manufacturing method - Google Patents

Abstract

An object of the present invention is to provide a positioning jig and a method of manufacturing a semiconductor device, which can prevent the solder from diffusing and adhering to an unintended place on a base plate by reducing the pressure around the solder. A positioning jig according to the present invention has a plate-like shape having a through hole in the center, a plate-like portion having a groove on the lower surface, and the plate-like portion surrounding the plate-like portion. By providing the projecting portion projecting below the portion, the diffused solder can be accommodated in the groove, and the solder is prevented from adhering to an unintended place of the base plate. [Selection diagram] Fig. 3

Description

  The present invention relates to a positioning jig used for manufacturing a semiconductor device and a method for manufacturing a semiconductor device using the positioning jig.

  Patent Document 1 discloses that a metal cooler and an insulating substrate are fixed by an ultra-high temperature bonding layer. The cooler is formed with a groove frame and has a shape that suppresses wetting and spreading during formation of the ultra-high temperature bonding layer.

Japanese Patent Laying-Open No. 2015-072957

  In order to install the insulating substrate at a predetermined location on the base plate, the insulating substrate may be installed on the base plate exposed from the through hole by placing a positioning jig on which the through hole is formed on the base plate. is there. After the insulating substrate is placed on the base plate, the solder provided between the insulating substrate and the base plate is melted to fix the insulating substrate to the base plate. The pressure around the solder is reduced for the purpose of removing voids in the solder during melting. At that time, the solder that has come off together with the void flows between the base plate and the positioning jig, and reaches the portion of the base plate where the resist coat is not formed, and may adhere to the base plate. Solder adhering to the base plate causes poor appearance.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a positioning jig and a semiconductor device manufacturing method that can prevent solder from adhering to a base plate.

  The positioning jig according to the invention of the present application has a plate-like shape having a through-hole in the center, a plate-like portion having a groove on the lower surface, and surrounds the plate-like portion, and is below the plate-like portion. And a projecting portion that projects into the surface.

  In the method of manufacturing a semiconductor device according to the invention of the present application, a first mounting step of placing a positioning jig having a through hole in the center on a base plate, and a semiconductor element on the upper surface of the base plate exposed by the through hole A second mounting step of placing the attached insulating substrate, and melting the solder provided between the base plate and the insulating substrate to fix the insulating substrate to the base plate, and the solder is molten A fixing step of decompressing the periphery of the solder and a lower surface of the positioning jig trapping the solder that diffuses between the base plate and the positioning jig by depressurizing the periphery of the solder in the fixing step A groove is provided.

  According to the present invention, since the positioning jig is provided with a groove and the solder is accommodated in the groove, the solder can be prevented from adhering to the base plate.

It is a top view of a semiconductor device. 3 is a cross-sectional view of a base plate and a positioning jig according to Embodiment 1. FIG. It is sectional drawing, such as an insulated substrate. It is a top view of the positioning jig etc. after a 2nd mounting process. It is sectional drawing, such as a positioning jig after a fixing process. It is sectional drawing of the positioning jig etc. which concern on a 1st comparative example. FIG. 6 is a cross-sectional view of a positioning jig and the like according to a second embodiment. It is a top view, such as a positioning jig. FIG. 8 is an enlarged view of the second lower surface of FIG. 7 and its surroundings. It is sectional drawing of the positioning jig etc. which concern on a 2nd comparative example. It is an enlarged view of the plate-shaped part of FIG. 10, and its periphery.

  A positioning jig and a method for manufacturing a semiconductor device according to an embodiment of the present invention will be described with reference to the drawings. The same or corresponding components are denoted by the same reference numerals, and repeated description may be omitted.

Embodiment 1 FIG.
1 is a plan view of a semiconductor device manufactured by the method of manufacturing a semiconductor device according to the first embodiment. This semiconductor device includes a base plate 1. An insulating substrate 2 is soldered to the upper surface of the base plate 1. An IGBT (Insulated Gate Bipolar Transistor) chip 3 and an FwDi (Free-wheeling Diode) chip 4 are soldered to the upper surface of the insulating substrate 2. The IGBT chip 3 and the FwDi chip 4 may be collectively referred to as a semiconductor element. A resist coat 5 is formed on the base plate 1. The resist coat 5 surrounds the insulating substrate 2. The resist coat 5 is a solder resist formed on a portion not to be soldered. No solder adheres to the upper surface of the resist coat 5 and the side surface of the base plate 1 and the vicinity thereof. Wire bonding is appropriately performed on the semiconductor device of FIG. 1 to obtain a power module.

(First mounting process)
A method for manufacturing a semiconductor device according to the first embodiment of the present invention will be described. FIG. 2 is a diagram showing that the positioning jig 6 is placed on the base plate 1. A through hole 6 a is formed in the center of the positioning jig 6. The upper surface of the base plate 1 is exposed to the outside by the through hole 6a. The positioning jig 6 has a plate shape having a through hole 6a in the center.

  The positioning jig 6 has a plate-like portion 6A and a protruding portion 6B connected to the plate-like portion 6A. A groove 6b is provided on the lower surface of the plate-like portion 6A. The groove 6b is preferably provided in an annular shape so as to surround the through hole 6a. The protruding part 6B is a part protruding downward from the plate-like part 6A. The protruding portion 6B surrounds the plate-like portion 6A in plan view. In the first mounting step, the position of the positioning jig 6 with respect to the base plate 1 can be determined by the protrusion 6B. Thus, the process of placing the positioning jig 6 on the base plate 1 is referred to as a first mounting process.

(Second mounting process)
Next, the process proceeds to the second mounting process. In the second mounting step, the insulating substrate 2 is placed on the base plate 1. FIG. 3 is a diagram showing that the insulating substrate 2 is placed on the base plate 1. The insulating substrate 2 has a ceramic substrate 2a, a metal pattern 2b formed on the upper surface of the ceramic substrate 2a, and a metal pattern 2c formed on the lower surface of the ceramic substrate 2a. The IGBT chip 3 and the FwDi chip 4 are provided on the metal pattern 2b via the solder S1. Below the metal pattern 2c is the base plate 1 via the solder S2. In the second mounting step, the insulating substrate 2 to which the IGBT chip 3 and the FwDi chip 4 are attached is placed on the upper surface of the base plate 1 exposed by the through hole 6a of the positioning jig 6.

  FIG. 4 is a plan view of the positioning jig 6 and the like after the second mounting step. Only the outline of the positioning jig 6 is drawn, and the configuration below the positioning jig 6 is drawn with a broken line. The groove 6b of the positioning jig is formed in an annular shape in plan view.

(Fixing process)
Next, the process proceeds to the fixing step. FIG. 5 is a cross-sectional view of the positioning jig 6 and the like after the fixing process. In the fixing step, the solder S2 provided between the base plate 1 and the insulating substrate 2 and the solder S1 provided between the semiconductor element and the insulating substrate 2 are melted. Thereby, the insulating substrate 2 is fixed to the base plate 1 and the semiconductor element is fixed to the insulating substrate 2. This process is called a fixing process.

  In the fixing step, when the solders S1 and S2 are melted, the pressure around the solders S1 and S2 is reduced. Specifically, the processing space that houses the positioning jig 6 is evacuated to lower the pressure around the solders S1 and S2 below atmospheric pressure. The decompression is preferably continued until the solders S1 and S2 are melted and then solidified. The voids in the solders S1 and S2 can be reduced by removing bubbles inside the solders S1 and S2 by reducing the pressure.

  By reducing the pressure around the solders S <b> 1 and S <b> 2 in the fixing process, the solder may diffuse between the base plate 1 and the positioning jig 6. The diffused solder is trapped by a groove 6 b formed on the lower surface of the positioning jig 6. FIG. 5 shows the solder 7 accommodated in the groove 6b.

  FIG. 6 is a view showing a positioning jig and the like according to the first comparative example. No groove is formed in the positioning jig of the first comparative example. Therefore, the lower surface of the positioning jig is flat. In this case, the solder flows between the base plate 1 and the positioning jig 6, and the solder 7 adheres to a portion where the resist coating near the side surface of the base plate 1 is not present. This solder 7 is detected as an appearance defect.

  On the other hand, in the positioning jig according to Embodiment 1 of the present invention, as shown in FIG. 5, the groove 6b is formed on the lower surface of the plate-like portion 6A. Therefore, the solder that diffuses between the base plate 1 and the positioning jig 6 in the fixing step can be stored in the groove 6b. By forming the groove 6b in an annular shape so as to surround the insulating substrate 2 in plan view, it is possible to prevent the solder from diffusing to the side surface of the base plate 1 or the vicinity thereof. The groove 6b is not necessarily provided in an annular shape, and can have an arbitrary shape.

  The positioning jig 6 and the semiconductor device manufacturing method according to the first embodiment of the present invention can be modified in various ways within a range not losing its characteristics. For example, the IGBT chip 3 and the FwDi chip 4 may be replaced with other semiconductor elements. Further, the shape of the groove 6b can be changed to an arbitrary shape. These modifications can be appropriately applied to a positioning jig and a semiconductor device manufacturing method according to the following embodiments. Since the positioning jig and the semiconductor device manufacturing method according to the following embodiment have much in common with the first embodiment, differences from the first embodiment will be mainly described.

Embodiment 2. FIG.
FIG. 7 is a diagram illustrating a positioning jig and the like according to the second embodiment. The lower surface of the plate-like portion 6A has a first lower surface 6C in which a groove 6b is formed, and a second lower surface 6D located higher than the first lower surface 6C. The second lower surface 6D is formed, for example, by applying a counterbore process to the lower surface of the plate-like portion 6A. FIG. 8 is a plan view of the positioning jig 6 and the like. The second lower surface 6D surrounds the first lower surface 6C in plan view. FIG. 7 is a sectional view taken along line VII-VII in FIG.

  Returning to the description of FIG. The base plate 1 is warped. Therefore, the base plate 1 is convex downward and has the highest height at the end. As a result, the lower surface of the base plate 1 can be brought into close contact with the heat sink to ensure heat dissipation of the power module.

  FIG. 9 is an enlarged view of the second lower surface 6D of FIG. 7 and its surroundings. When the first mounting step is finished, as shown in FIG. 9, the end portion of the base plate 1 is located immediately below the second lower surface 6D. There is a space 9 between the end of the base plate 1 and the second lower surface 6D. By securing this space 9, contact between the end of the base plate 1 and the positioning jig 6 is prevented. By securing the space 9, the first lower surface 6C and the base plate 1 can be brought into contact or very close to each other. Therefore, the solder 7 can be trapped in the groove 6b.

  FIG. 10 is a view showing a positioning jig and the like according to the second comparative example. In the second comparative example, the lower surface of the plate-like portion 6A is flat, and there is no second lower surface described above. Therefore, the end of the warped base plate 1 comes into contact with the positioning jig 6, and the positioning jig 6 floats with respect to the base plate 1. As a result, a large gap is generated between the positioning jig 6 and a portion of the base plate 1 that is closer to the center than the end portion, and the solder cannot be trapped in the groove 6b.

  FIG. 11 is an enlarged view of the plate-like portion 6A of FIG. 10 and its periphery. FIG. 11 shows that the solder could not be trapped in the groove 6b due to a large gap between the positioning jig 6 and the portion of the base plate 1 closer to the center than the end. . In the case of the second comparative example, the solder 7 may flow to the side surface of the base plate 1.

  The positioning jig according to the second embodiment of the present invention has a second lower surface 6D formed higher than the first lower surface 6C, so that the solder is grooved when the warped base plate 1 and the insulating substrate 2 are joined. It can be captured in 6b. The positioning jig and the semiconductor device manufacturing method according to the second embodiment of the present invention can be variously modified without losing this characteristic.

  DESCRIPTION OF SYMBOLS 1 Base board, 2 Insulation board | substrate, 6 Positioning jig, 6A Plate-shaped part, 6B Protrusion part, 6a Through-hole, 6b Groove, 6C 1st lower surface, 6D 2nd lower surface

Claims (6)

A plate-like portion having a plate-like shape having a through hole in the center, and a groove provided on the lower surface;
A positioning jig comprising: a protruding portion surrounding the plate-like portion and protruding downward from the plate-like portion. The lower surface of the plate-like part is
A first lower surface on which the groove is formed;
A second lower surface that surrounds the first lower surface in a plan view and is higher than the first lower surface;
The positioning jig according to claim 1, wherein the groove is formed in the first lower surface.   The positioning jig according to claim 1, wherein the groove is provided in an annular shape in plan view. A first mounting step of placing a positioning jig having a through hole in the center on the base plate;
A second mounting step of placing an insulating substrate on which a semiconductor element is mounted on the upper surface of the base plate exposed by the through hole;
A fixing step of melting the solder provided between the base plate and the insulating substrate to fix the insulating substrate to the base plate, and depressurizing the periphery of the solder when the solder is melted;
The lower surface of the positioning jig is provided with a groove for trapping solder that diffuses between the base plate and the positioning jig by reducing the pressure around the solder in the fixing step. A method for manufacturing a semiconductor device. The base plate is warped downward and has the highest height at the end,
The lower surface of the positioning jig has a first lower surface in which the groove is formed, and a second lower surface that surrounds the first lower surface and is higher than the first lower surface in plan view,
5. The end of the base plate is located immediately below the second lower surface after the first mounting step, and a space is provided between the end of the base plate and the second lower surface. The manufacturing method of the semiconductor device as described in 2. above.   6. The method of manufacturing a semiconductor device according to claim 4, wherein the groove is provided in an annular shape in plan view.

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