JP2012069722A - Electrical equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide electrical equipment in which occurrence of migration is effectively suppressed by preventing a part in which migration may occur from being exposed to a high-humidity atmosphere (and high-temperature) as far as possible even if the part in which migration may occur cannot be completely sealed due to device configuration.SOLUTION: In an operation input device of an in-vehicle air conditioner, a rib 30 is extended from a rear cover 3 and the whole periphery of an electric element is surrounded by the rib 30 in consideration of the possibility of migration occurrence in an electric element on a circuit board 4 equipped inside. Consequently, exposing the electric element to a high-humidity atmosphere and high-temperature is suppressed by the rib 30 and the migration occurrence is effectively suppressed through a simple structure.

Description

  The present invention relates to an electrical device.

  Various electric devices have a problem called migration that causes malfunction. Migration is a phenomenon in which a metal or a compound is deposited on an electrode part in a printed circuit board placed in a high humidity (and high temperature) state. When this phenomenon progresses, a short circuit occurs between the electrodes. For example, Patent Document 1 below discloses a bread maker that prevents malfunction caused by migration.

Japanese Patent Laid-Open No. 10-137133

  For example, in an in-vehicle air conditioner and the like, the circuit board cannot be completely sealed in the housing due to the device configuration. Therefore, in order to prevent migration of the electric element on the circuit board, In addition, it is necessary to devise a method that prevents exposure to as much atmosphere as possible.

  In the prior art, for example, there is a technique of applying a drip-proofing agent to a place where migration is likely to occur, for example, between ports of a microcomputer on a printed circuit board to prevent exposure to a high humidity and high temperature atmosphere. However, this method has a problem that the number of work steps increases and the cost increases.

  Moreover, in the said patent document 1, the control part (printed circuit board) is completely covered with the cover member, and the outer periphery of the cover member is completely overlapped with the rib. However, this method requires that no gap be formed between the rib and the cover member, but it may not be possible depending on the form of the device or product, such as an opening for an external connector.

  Therefore, in view of the above problems, the problem to be solved by the present invention is to prevent migration-prone portions from being exposed to high humidity (and high It is an object of the present invention to provide an electric device in which occurrence of migration is effectively suppressed by avoiding exposure to an atmosphere of (temperature) as much as possible.

Means for Solving the Problems and Effects of the Invention

  In order to achieve the above object, an electrical device according to the present invention is housed in an electrical device and executes a control process in the electrical device, and at least a partial region of the circuit board surface of the circuit substrate. A cover portion having a cover surface that covers the circuit board with a space therebetween, and surrounds the entire circumference of the predetermined electrical element disposed in the partial area of the circuit board. An imaginary line on the surface is used as a substrate imaginary line, and the cover portion is formed on the substrate imaginary line so as to surround the entire circumference of the predetermined electric element from a position facing the substrate imaginary line on the inner surface of the cover portion. It has the projection part formed in the cylinder shape which protrudes toward, It is characterized by the above-mentioned.

  Thus, in the electrical device according to the present invention, in the structure in which the circuit board is covered with the cover portion, the protruding portion is formed from the cover portion so as to protrude toward the virtual line surrounding the predetermined element on the substrate. Such a structure can effectively suppress exposure of a predetermined element to an undesired atmosphere. Therefore, for example, the occurrence of migration caused by exposing the circuit board to an atmosphere of high humidity and high temperature can be effectively suppressed.

  The cylindrical shape of the protruding portion includes a tip portion parallel to the substrate surface, and the protruding portion is formed by extending from the inner surface of the cover portion so that the tip portion is at a predetermined distance from the substrate surface. It may be done.

  As a result, the protruding portion is arranged so that the tip of the protruding portion is a predetermined distance from the substrate surface, so that a predetermined element on the substrate is provided with a gap by a predetermined distance and the entire circumference is surrounded by the protruding portion. Can do. Therefore, it is possible to effectively prevent the predetermined element from being exposed to an undesirable atmosphere by appropriately surrounding the element on the circuit board.

  The electrical device is installed in a high-humidity atmosphere capable of causing migration, and the predetermined electrical element is an electrical element that may cause migration among electrical elements disposed on the circuit board. There may be.

  For electrical equipment installed in a high-humidity atmosphere that can cause migration, the entire circumference of the electrical element that may cause migration is surrounded by a protrusion that extends from the cover. It is possible to effectively suppress the occurrence of migration by effectively suppressing the exposure of the electric element to an atmosphere of high humidity and high temperature with a simple structure.

  The cover portion may not seal the inside of the electric device.

  As a result, in a structure in which the cover portion does not seal the inside of the electric device, there is a possibility that high humidity and high temperature air flows into the inside and migration may occur on the circuit board. In the structure covered with the cover part, since the protruding part is formed from the cover part so as to protrude toward the imaginary line surrounding the predetermined element on the substrate, the predetermined element is exposed to an undesired atmosphere with a simple structure. This can be effectively suppressed. Therefore, for example, the occurrence of migration caused by exposing the circuit board to an atmosphere of high humidity and high temperature can be effectively suppressed.

The perspective view of the vehicle-mounted air-conditioner operation input device in Example 1 of this invention. The front view of a vehicle-mounted air-conditioner operation input device, a rear view, and AA sectional drawing. BB sectional drawing of an in-vehicle air conditioner operation input device. The figure which shows the BB sectional drawing of the vehicle-mounted air-conditioner operation input device in Example 2. FIG. The figure which shows the BB sectional drawing of the vehicle-mounted air-conditioner operation input device in Example 3. FIG. The figure which shows the BB sectional drawing of the vehicle-mounted air-conditioner operation input device in Example 4. FIG. The perspective view of a cover part. The perspective view of a circuit board.

  Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show an example of an operation input device 1 for an in-vehicle air conditioner according to a first embodiment of the present invention. 1 is a perspective view, FIG. 2 (a) is a rear view, FIG. 2 (b) is an AA sectional view, FIG. 2 (c) is a front view, and FIG. 3 is a BB sectional view.

  The operation input device 1 includes an operation panel unit 2, a rear cover 3, and a printed circuit board 4 (circuit board). The operation panel unit 2 includes a liquid crystal display unit 20, an air conditioning on / off button 21, a mode switching button 22, a set value decrease button 23, and a set value increase button 24. The liquid crystal display unit 20 displays various types of information such as air conditioning set temperature and set air volume.

  When the user presses the air-conditioning on / off button 21, the on-off of the vehicle air-conditioning is switched. When the user presses the mode switching button 22, for example, the blowing position (face, foot, defroster, etc.) is switched. When the user presses the set value lowering button 23, the set temperature and the set air volume are reduced. When the user presses the set value increase button 24, the set temperature and the set air volume increase.

  The rear cover 3 (cover portion) is a cover that covers the rear portion of the operation input device 1 (the side opposite to the operation panel portion 2). Details of the rear cover 3 will be described later. An electric circuit (electronic circuit) for controlling the operation panel and the air conditioner is printed on the printed board 4 (circuit board, board), and various electric elements (electronic elements) such as an IC are arranged. The operation input device 1 has the above-described configuration and is disposed, for example, on a part of an instrument panel (instrument panel, dashboard) in a passenger compartment of an automobile.

  Details of the rear cover 3 will be described below. FIG. 7 is a perspective view of the rear cover 3. 2A and 2B are a rear view and a cross-sectional view taken along line AA of the rear cover.

  The rear cover 3 includes an opening 36, and FIG. 7 is a perspective view seen from the opening 36 side. The rear cover 3 in FIG. 7 has a rectangular parallelepiped box shape in which the inside is hollow, and one surface thereof is an opening 36. The box shape has a bottom surface portion 37 (bottom surface, covering surface) and four side surface portions 38. Such a shape of the rear cover 3 is only one embodiment of the present invention, and may be an arbitrary distorted three-dimensional shape instead of a rectangular parallelepiped shape. Furthermore, the rear cover 3 only needs to cover at least a part of the circuit board 4.

  Ribs 30 and 35 are formed on the bottom surface portion 37 of the rear cover 3. The ribs 30 are formed so as to extend from the inner surface side of the bottom surface portion 37 (the inner surface side in a state assembled to the operation input device 1) and project by a cylindrical shape having a rectangular cross section in a direction parallel to the bottom surface portion 37. Has been. The rib 30 is a main part of the present invention, and details will be described later. The rib 35 is formed to increase the strength of the rear cover 3. The rib 35 is extended so that a lattice-shaped (that is, a plurality of intersecting linear) protruding portions protrude from the bottom surface portion 37.

  The rib 35 is formed over the entire bottom surface portion 37, and its side end portion is in contact with and integrated with the side surface portion 38. The material of the rear cover 3 is, for example, resin (polypropylene or the like), and the bottom surface portion 37, the side surface portion 38, and the ribs 30 and 35 may be integrally molded by injection molding.

  FIG. 8 shows a perspective view of the circuit board 4 (FIG. 8 is a simplified diagram, and illustration of wiring patterns formed on the circuit board and various elements disposed thereon is omitted). . As described above, in a circuit board exposed to an atmosphere of high humidity (and high temperature), for example, migration of ions occurs between adjacent terminals having different voltage values, and so-called migration in which metal or the like precipitates to cause corrosion. A reaction called occurs. A short circuit between the wirings occurs at the location where the migration has progressed.

  In particular, in the case of the operation input device 1, a hole portion 39 for a connector portion for exchanging information and power with other devices is formed, and the inside of the device cannot be sealed by the rear cover 3. The operation input device 1 equipped with the circuit board 4 of FIG. 8 is equipped in an instrument panel of an automobile vehicle, and this place is also a place where high humidity and high temperature are likely to occur. Therefore, high-humidity and high-temperature air flows into the operation input device 1. In the circuit board 4 of FIG. 8, it is assumed that the IC 40 (microcomputer element) has adjacent terminals with different voltage values, and that portion of the IC 40 may cause migration.

  A line 41 shown in FIG. 8 indicates a virtual line (substrate virtual line) surrounding the entire circumference of the IC 40. That is, the virtual line 41 is a closed line that surrounds the entire periphery of the IC 40 within the substrate surface. The virtual line 41 is formed so that the element 40 having the possibility of migration is enclosed therein, the element having a low possibility of migration (not present) is placed outside the element, and there is no element on the virtual line 41. do it. The virtual line 41 is only a virtual line and does not need to be actually drawn on the substrate.

  The shape of the imaginary line 41 does not have to be a simple rectangle as shown in FIG. 3 or the like, but is a closed line having an arbitrary shape according to the shape of a part, element, or the like where migration may occur. It may be a closed line that surrounds the entire circumference of the portion where migration may occur. The cross-sectional shape (in the direction parallel to the bottom surface portion 37) of the rib 30 in the rear cover 3 may be made to coincide with the imaginary line 41 in the circuit board 4. The rear cover 3 thus formed is arranged so as to cover the rear side of the operation input device 1 as shown in FIG.

  The operation panel unit 2 and the rear cover 3 may be fixed by, for example, a screw structure or a fitting structure (not shown). Further, the circuit board may be fixed to the operation panel unit 2 by a screw structure or a fitting structure (not shown). The board surface on which various elements on the circuit board are arranged is located on the rear side of the operation input device 1. Thereby, the substrate surface of the circuit board 4 is disposed at a position facing the rear cover 3 (the bottom surface portion 37 thereof).

  The rib 30 of the rear cover 3 is disposed so as to be close to the virtual line 41. As shown in FIG. 7, the rib 30 has a tip surface 30 a (tip portion). The tip surface 30 a may be parallel to the bottom surface portion 37. By assembling the rear cover 3, the front end surface 30 a is arranged in parallel with the substrate surface of the substrate 4. As shown in FIG. 2B, the tip surface 30a of the rib 30 and the circuit board 4 (the imaginary line 41) may be in contact with each other, or may be separated by a predetermined distance.

  When the tip surface 30a and the substrate surface are separated from each other, the tip surface 30a of the rib 30 is also affected by a dimensional error or expansion in consideration of a dimensional error in the rear cover 3 or expansion or contraction of the rear cover 3 due to a temperature change. The minimum necessary distance that does not press the circuit board 4 (and deform the board) is set as the distance between the tip surface 30a and the board surface. As a result, the distance between the rib 30 and the substrate surface is the minimum necessary distance, and the rib 30 surrounds the entire circumference of the element 40 that may migrate.

  In order to suppress (avoid) migration, it is important not to expose the element 40 to an atmosphere of high humidity (high temperature). However, as described above, the entire circumference of the element 40 that may be migrated by the rib 30 Since it is surrounded, the element 40 is not exposed to an atmosphere of high humidity (high temperature) (it is difficult to be exposed). As a result of experiments, the inventor has found that the rib 30 configured as described above may cause migration (even if the above-described minimum gap is provided between the tip surface 30a of the rib 30 and the substrate surface of the circuit board 4). It is verified by experiment that it decreases.

  The present invention is not limited to the structure of the first embodiment, and various modifications can be made. Example 2 will be described below. In the second embodiment (and third and fourth embodiments), only the structure and shape of the rib 30 are changed from the first embodiment. Hereinafter, parts different from the first embodiment will be described. The rib structure in Example 2 is shown in FIG. FIG. 4 (and FIGS. 5 and 6) is a cross-sectional view taken along the line BB in the same manner as FIG. In the example of FIG. 4, there are a plurality of elements 40 that may be migrated.

  Ribs 30 and 31 are formed on the rear cover 3 so as to surround each of the plurality of elements 40. The inventor has verified that such a structure can effectively suppress the occurrence of migration in the individual elements 40 by surrounding the individual elements 40. Note that the structure of FIG. 4 is not limited to a structure having two ribs, and the number of ribs 30 may be increased in accordance with the number of elements that may be migrated.

  Next, Example 3 will be described. The rib structure in Example 3 is shown in FIG. In the example of FIG. 5, there are two elements 40 having a possibility of migration, and one rib 32 surrounding them is formed. Thus, even if the single rib 32 is formed so as to surround the entire circumference of the region to which the plurality of elements 40 belong, high humidity (high temperature) air does not flow in each element 40, and migration is effective. The inventor has verified through experiments that it can be suppressed to a low level.

  Next, Example 4 will be described. The rib structure in Example 4 is shown in FIG. In the example of FIG. 6, the double ribs 33 and 34 surround the entire circumference of the element 40 that may be migrated. When multiple (not necessarily double) ribs are formed so as to surround the entire circumference of one element 40 in this way, it is possible to further suppress the flow of high humidity (high temperature) air to the element 40. The inventors have verified through experiments that migration can be more effectively suppressed than in the case of a single rib. Any combination of the above embodiments may be used. That is, for example, a structure in which a plurality of elements are surrounded by multiple ribs may be used.

  The above-described embodiments are some embodiments of the present invention, and may be appropriately changed without departing from the spirit described in the claims. For example, the present invention is not limited to an in-vehicle air conditioner and may be applied to other in-vehicle devices. Furthermore, the present invention is not limited to the in-vehicle device, and can be applied to any electric device having a circuit board exposed to an atmosphere of high humidity (high temperature) and its cover.

1 Onboard air conditioner operation input device (electric equipment)
2 Operation input panel 3 Rear cover 4 Circuit board 30, 31, 32, 33, 34 Rib (projection)

Claims (4)

A circuit board that is housed in an electrical device and executes control processing in the electrical device;
A cover portion including a cover surface that covers at least a part of the substrate surface of the circuit board with a space between the circuit board and the circuit board;
With
A virtual line on the substrate surface surrounding the entire circumference of the predetermined electrical element arranged in the partial area of the circuit board is a substrate virtual line,
The cover portion is a protrusion formed in a cylindrical shape that protrudes toward the substrate imaginary line so as to surround the entire circumference of the predetermined electric element from a position facing the substrate imaginary line on the inner surface of the cover portion. Electrical equipment characterized by comprising a section. The cylindrical shape of the protruding portion includes a tip portion parallel to the substrate surface,
The electric device according to claim 1, wherein the protruding portion is formed to extend from an inner surface of the cover portion so that the tip portion is a predetermined distance from the substrate surface. The electrical equipment is installed in a high humidity atmosphere that can cause migration,
The electric device according to claim 1, wherein the predetermined electric element is an electric element that may cause migration among electric elements arranged on the circuit board.   The electric device according to claim 1, wherein the cover portion does not seal the inside of the electric device.

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