Electronic apparatus

Abstract

To provide an electronic apparatus capable of accurately detecting the presence or absence of misalignment of a heat transfer sheet though image inspection.SOLUTION: An electronic apparatus according to the present invention includes: a housing; a plurality of bus bars; and heat transfer sheets disposed on a bottom surface of an accommodation portion the housing, and sandwiched between the housing and the bus bars. Therein each of the heat transfer sheets has a detection point, and is disposed such that two sides constituting outline of the heat transfer sheet are aligned with two intersecting reference lines of the housing, and the detection point is located in a position that does not overlap with the bus bars in a top view, so as to eliminate a need to accurately detect positions of edges of the heat transfer sheet, and misalignment of the heat transfer sheet can be accurately detected through image inspection.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electronic device, and more particularly to an electronic device including a heat transfer sheet between a housing and a bus bar. [Background technology]

[0002] Inverters installed in electric vehicles (EVs) are designed to be high-output, compact, and lightweight in order to extend driving range and improve fuel and electricity costs. However, if the inverter becomes too hot, it will not be able to perform to its full potential and there is a risk of it being damaged, so it must be cooled.

[0003] The bus bar connecting the inverter and the motor is prone to heat generation due to the large current that flows through it, and is also required to have insulation properties. Therefore, heat is dissipated through an insulating heat transfer sheet.

[0004] Patent Document 1 describes an electronic device in which a heat transfer sheet having through holes is interposed between a heat generating element and a heat sink. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-82887 Summary of the Invention [Problem to be solved by the invention]

[0006] In the inverter assembly process, image inspection is generally performed to detect the edge of the heat transfer sheet using an image taken from above the inverter and to detect whether the heat transfer sheet is misaligned or has been assembled incorrectly.

[0007] However, it is difficult to accurately detect the position of the edge of the heat transfer sheet due to curling at the cut points of the heat transfer sheet (warping of the heat transfer sheet) and reflections that occur on the casting surface of the housing outside the heat transfer sheet, resulting in frequent false alarms.

[0008] The present invention was made in consideration of the problems associated with the conventional technology, and its purpose is to provide an electronic device that can accurately detect whether or not a heat transfer sheet is misaligned through image inspection. [Means for solving the problem]

[0009] As a result of extensive research into achieving the above-mentioned object, the inventors discovered that by providing a detection point at a location on the heat transfer sheet that does not overlap with the bus bar when the heat transfer sheet is placed in a predetermined position, it becomes possible to detect whether or not the heat transfer sheet is misaligned by combining the position of the edge of the heat transfer sheet with the position of the detection point, thereby eliminating the need to accurately detect the position of the edge of the heat transfer sheet, and thus completed the present invention.

[0010] That is, the electronic device of the present invention includes a housing, a plurality of bus bars, and a heat transfer sheet that is disposed on the bottom surface of the housing and sandwiched between the housing and the bus bars. The heat transfer sheet has a detection point, and the heat transfer sheet is arranged so that two sides constituting its outer shape are aligned along two reference lines where the housing intersects, and the detection point is located at a position that does not overlap with the bus bar when viewed from above. [Effects of the Invention]

[0011] According to the present invention, when the heat transfer sheet is placed in a predetermined position, a detection point is provided at a location that does not overlap with the bus bar of the heat transfer sheet. This eliminates the need to accurately detect the position of the edge of the heat transfer sheet, and makes it possible to provide an electronic device that can accurately detect whether the heat transfer sheet is misaligned by image inspection. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram illustrating an example of an electronic device of the present invention. [Figure 2] FIG. 10 is a cross-sectional view of a main part showing a state in which the burr side of the heat transfer sheet is in contact with the housing. DETAILED DESCRIPTION OF THE INVENTION

[0013] The electronic device of the present invention will now be described in detail. The electronic device of the present invention comprises electronic components housed within a housing 1 and a bus bar 2 for supplying power to an external device such as a motor, and further comprises a heat transfer sheet 3 sandwiched between the housing 1 and the bus bar 2 with its main surface in contact with the bottom surface of the housing's storage section.

[0014] In the electronic device, the heat transfer sheet is in contact with the housing and the bus bar, so that heat from the bus bar can be transferred to the housing and dissipated via the heat transfer sheet.

[0015] However, electronic devices such as inverters for drive motors of electric vehicles generally have housings made of cast metal containing aluminum or other metals. Because the bus bars are high-voltage parts, misalignment of the heat transfer sheet not only prevents heat transfer but also prevents insulation, so the heat transfer sheet must be accurately positioned in a predetermined position.

[0016] As described above, the presence or absence of misalignment of the heat transfer sheet is detected by image inspection. This image inspection detects the edge of the heat transfer sheet from the difference in brightness and hue between the heat transfer sheet and the housing, and detects the presence or absence of misalignment based on the position of the edge relative to a reference point set on the housing, etc.

[0017] In such image inspections, if the light in the inspection environment causes the edges of the heat transfer sheet to appear bright and whitish due to reflections from the edges of the heat transfer sheet or the housing, the difference in brightness and hue at the boundary between the heat transfer sheet and the housing becomes small, making it impossible to accurately detect the position of the edge of the heat transfer sheet, resulting in a false alarm.

[0018] The reflections near the edges of the heat transfer sheet are often caused by the curl that occurs when the sheet is rolled up, and curls do not form in two perpendicular directions at the same time. Therefore, although detecting the edges of the heat transfer sheet in both the X and Y directions reduces the occurrence of false alarms, it is difficult to accurately detect misalignment in either the X or Y direction.

[0019] In the electronic device of the present invention, when the heat transfer sheet is placed in a predetermined position on the housing, a detection point 31 is provided at a location on the heat transfer sheet that does not overlap with the bus bar when viewed from above, and the heat transfer sheet is placed so that two sides of the edge that constitutes the outer shape of the heat transfer sheet 3 are aligned with two intersecting reference lines 11 that indicate the location where the heat transfer sheet provided on the housing 1 should be placed.

[0020] If the shape of the heat transfer sheet is point symmetric or line symmetric, the detection points 31 are provided at locations other than the point or line of symmetry.

[0021] Therefore, during image inspection, the electronic device of the present invention can detect the position of the detection point 31 in addition to the positions of the two intersecting sides of the heat transfer sheet to detect whether or not there is a positional misalignment, so even if the heat transfer sheet has a tendency to curl and reflections occur near the edges, the occurrence of false alarms can be reduced.

[0022] In other words, when it is possible to detect that the detection point of the heat transfer sheet is at a predetermined position, the positional deviation that occurs is limited to the positional deviation that occurs when the heat transfer sheet rotates around the detection point.Therefore, if it is possible to detect the position of either of the two intersecting sides that make up the outer shape of the heat transfer sheet and to detect that this side has not deviated from the predetermined position, there will be no problematic positional deviation, and the occurrence of false alarms will be reduced.

[0023] As the heat transfer sheet, for example, a highly heat conductive insulating resin sheet made of silicone, epoxy or the like filled with ceramic filler can be used.

[0024] Furthermore, the reference line of the housing on which the heat transfer sheet is placed may be a mark formed on the housing, but if it is a vertical wall of the housing, it becomes easy to place the heat transfer sheet in the specified position by abutting two sides of the heat transfer sheet, i.e., the side faces, against the vertical wall when viewed from above.

[0025] The detection point only needs to be able to be detected by image inspection, and can be formed by a mark in a color that has a large difference in brightness or hue from the surrounding area, i.e., the background color of the heat transfer sheet, or by a hole that penetrates the heat transfer sheet.

[0026] If the detection points are through holes, the detection points can be formed when the heat transfer sheet is cut, thereby reducing the number of manufacturing steps.

[0027] When the detection point is formed by a through hole, the detection point will have the color of the housing, so if the color of the heat transfer sheet is lower in brightness than the color of the housing, reflection on the heat transfer sheet is suppressed, making it easier to detect the position of the detection point.

[0028] It is preferable that the sagging surface of the heat transfer sheet contacts the bus bar and the burr surface contacts the housing.

[0029] The sagging surface refers to the surface that the blade contacts when punching the heat transfer sheet, and the burred surface refers to the surface that the blade comes off.

[0030] As shown in Figure 2, the punching process makes the area of ​​the heat transfer sheet on the burr surface 32 side larger than the area on the sagging surface 33 side. Therefore, by making the area on the sagging surface side larger than the area of ​​the bus bar, there are no areas where the heat transfer path becomes narrow when heat is transferred from the bus bar to the housing, and the heat from the bus bar can be transferred over a wide area, improving heat transfer efficiency.

[0031] When the detection points are marks, the sagging and burring surfaces (front and back) of the heat transfer sheet can be detected by forming a mark only on the sagging surface side of the heat transfer sheet.When the detection points are formed by through holes, the detection is possible by the through holes having an asymmetric shape that does not have point symmetry or line symmetry.

[0032] Furthermore, if the outer shape of the heat transfer sheet is asymmetrical, the sides of the heat transfer sheet will not be aligned with the reference lines of the housing, so that it is possible to prevent the heat transfer sheet from being placed upside down.

[0033] The detection points may be provided at any position that does not overlap with the bus bars and that can be seen from above.

[0034] For example, when multiple bus bars are arranged side by side so that their main surfaces are parallel to the bottom surface of the housing, as shown on the lower side in the top view of Figure 1, the wiring may be located outside of adjacent bus bars or between parallel bus bars.

[0035] Busbars are typically high-voltage components, and because a certain creepage distance must be maintained, gaps are often provided between the busbars. By providing a detection point between adjacent busbars, this space can be effectively utilized, enabling electronic devices to be made smaller.

[0036] Furthermore, as shown on the left side of the top view of Figure 1, when multiple bus bars are bent and rise from a substrate that is arranged parallel to the bottom surface of the housing, and are insulated with an insulating sheet or resin mold, etc., and the multiple bus bars are overlapped to save space, in other words, when the thickness direction of the bus bars and the thickness direction of the heat transfer sheet are perpendicular to each other and there are no gaps between the bus bars, a detection point can be provided outside the overlapping bus bars. [Explanation of symbols]

[0037] 1 chassis 11 Reference line (vertical wall) 2 busbars 21 Insulation sheet 3 Heat transfer sheet 31 detection points 32 Burr surface 33 Droopy Face 4 boards

Claims

1. An electronic device comprising: a housing; a plurality of bus bars; and a heat transfer sheet disposed on a bottom surface of an accommodation portion of the housing and sandwiched between the housing and the bus bars, the heat transfer sheet has a detection point, the heat transfer sheet is arranged so that two sides constituting its outer shape are aligned along two reference lines where the housing intersects; The electronic device is characterized in that the detection point is located at a position that does not overlap with the bus bar when viewed from above.

2. 2. The electronic device according to claim 1, wherein the detection point is a hole that penetrates the heat transfer sheet.

3. 3. The electronic device according to claim 2, wherein the color of the heat transfer sheet is lower in brightness than the color of the housing.

4. 2. The electronic device according to claim 1, wherein the heat transfer sheet has a burr side that contacts the housing.

5. 3. The electronic device according to claim 2, wherein the detection point has an asymmetric shape.

6. the plurality of bus bars are arranged side by side in an in-plane direction of the heat transfer sheet, 2. The electronic device according to claim 1, wherein the detection point is located between the plurality of bus bars.

7. the plurality of bus bars are arranged side by side in an in-plane direction of the heat transfer sheet, 2. The electronic device according to claim 1, wherein the detection point is located outside the space between the bus bars.

8. a thickness direction of the bus bar and a thickness direction of the heat transfer sheet are perpendicular to each other, 2. The electronic device according to claim 1, wherein the plurality of bus bars are insulated from each other.

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