Substrate unit

Abstract

To provide a substrate unit capable of improving heat dissipation.SOLUTION: A substrate unit includes a first substrate and a second substrate. A control electronic component is mounted on the first substrate. The second substrate has a power supply electronic component mounted thereon and is disposed such that a surface on which the power supply electronic component is mounted faces the first substrate. The first substrate includes an exposed portion that is not covered with the surface layer on a surface facing the second substrate. The electronic component for power supply is disposed to abut on the exposed portion.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The disclosed embodiments relate to a substrate unit. [Background technology]

[0002] In recent years, as products have become smaller, there has been a demand for miniaturization of the electronic boards included in the products, and various techniques for miniaturizing such electronic boards have been proposed (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-053698 Summary of the Invention [Problem to be solved by the invention]

[0004] Electronic boards include, for example, boards on which electronic control components are mounted and boards on which electronic power supply components are mounted, and these boards are sometimes combined into units to achieve miniaturization. However, in board units that include such boards, further miniaturization can be achieved by, for example, narrowing the spacing between the mounted components, which can result in a decrease in heat dissipation.

[0005] An object of one aspect of the embodiment is to provide a board unit that can improve heat dissipation. [Means for solving the problem]

[0006] A substrate unit according to one aspect of the embodiment includes a first substrate on which a control electronic component is mounted, and a second substrate on which a power supply electronic component is mounted and disposed so that the surface on which the power supply electronic component is mounted faces the first substrate. The first substrate has an exposed portion on the surface facing the second substrate that is not covered by a surface layer. The power supply electronic component is disposed so as to abut against the exposed portion.

[0007] In this way, by abutting the power supply electronic components of the second substrate against the exposed portion of the first substrate that is not covered by the surface layer, the exposed portion can function as a heat sink to cool the power supply electronic components, thereby improving the heat dissipation properties of the substrate unit.

[0008] Furthermore, because the exposed portion functions as a heat sink, an additional cooling mechanism such as a heat sink is not required, allowing the board unit to be made smaller. Furthermore, because the power supply electronic components of the second board are arranged to abut against the exposed portion of the first board, space for the power supply electronic components can be secured between the opposing first and second boards. Therefore, spacers or the like for securing such space are not required, and as a result, the height of the board unit can be reduced. Furthermore, eliminating the need for the heat sink and spacers mentioned above is advantageous in terms of manufacturing costs for the board unit.

[0009] The surface area of ​​the first substrate is configured to be larger than the surface area of ​​the second substrate.

[0010] This allows a relatively large exposed area to be secured on the first board, thereby ensuring sufficient cooling performance through the exposed area, in other words, reliably improving the heat dissipation performance of the board unit. Also, because the surface area of ​​the first board is larger than that of the second board, the power electronic components of the second board and the control electronic components of the first board can be arranged relatively far apart, thereby preventing heat generated by the power electronic components from affecting the control electronic components.

[0011] The control electronic components are disposed at a position other than the exposed portion of the first substrate.

[0012] This allows the control electronic components to be positioned relatively far away from the exposed portion, thereby preventing the heat generated by the power electronic components mounted on the second board from affecting the control electronic components.

[0013] The control electronic components are arranged on the surface of the first substrate facing the second substrate.

[0014] This allows the height of the board unit to be reduced compared to when the control electronic components are arranged on the surface of the first board opposite the second board side. That is, when the control electronic components are arranged on the surface of the first board opposite the second board side, the height of the control electronic components does not overlap with the height (thickness) of the second board, so the height of the board unit is a value that includes the height of the control electronic components and the height of the second board. In contrast, when the control electronic components are arranged on the surface of the first board facing the second board, the height of the control electronic components and the height (thickness) of the second board partially overlap, so the height of the board unit can be reduced. Furthermore, by configuring the control electronic components to be arranged in a position other than the exposed portion of the first board, the height of the board unit can be reduced from depending on the height of the control electronic components. [Effects of the Invention]

[0015] According to one aspect of the embodiment, it is possible to improve heat dissipation in the board unit. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a plan view of a substrate unit according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a block diagram showing an example of the configuration of a power supply module. [Figure 4] FIG. 4 is a plan view of the second substrate as viewed from the front surface. [Figure 5] FIG. 5 is a side view of the second substrate. [Figure 6] FIG. 6 is a bottom view of the second substrate as viewed from the rear surface. [Figure 7] FIG. 7 is a plan view of the first substrate as viewed from the front surface. [Figure 8] FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the substrate unit disclosed in the present application will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments.

[0018] A board unit according to an embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a plan view of the board unit according to an embodiment, and Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. Figs. 1, 2, and Fig. 4 onwards are all schematic diagrams.

[0019] 1 and 2, for ease of explanation, a three-dimensional Cartesian coordinate system defined by mutually orthogonal X-axis, Y-axis, and Z-axis directions is illustrated. Such Cartesian coordinate systems may also be shown in other drawings used in the following explanation. In the following explanation, expressions such as "X-axis direction," "Y-axis direction," and "Z-axis direction" are used, but these refer to the "X-axis direction," "Y-axis direction," and "Z-axis direction" when the board unit is in the state shown in the drawings, and do not limit the arrangement direction of the board unit, etc.

[0020] The board unit 1 is mounted on a product (not shown) and controls the product and supplies power to the product. The product may be any product that can mount the board unit 1. Examples of products include, but are not limited to, toilet devices, sanitary washing devices, electrical devices, and electronic devices.

[0021] As shown in FIGS. 1 and 2, the board unit 1 includes a first board 10, a second board 20, and a case 30.

[0022] The first substrate 10 is, for example, flat, and is formed in a rectangular or substantially rectangular shape in a plan view (viewed in the Z-axis direction). Note that the shape of the first substrate 10 shown in Fig. 1 is an example and is not limited thereto.

[0023] The first substrate 10 is mounted with a control electronic component 11, a transformer unit 12, a connector 13, a load driver unit 14, a load 15, and the like. The control electronic component 11 includes a microcomputer that controls the load driver unit 14, and the like. As will be described later, the transformer unit 12 steps down the DC voltage supplied from the second substrate 20, and supplies power to the load 15, the control electronic component 11, an external load (not shown) connected to the connector 13, and the like. A switching regulator IC or the like can be used as the transformer unit 12.

[0024] An external load (not shown) is connected to the connector 13. Examples of the external load include, but are not limited to, a motor, a display device, and a lighting device. The load driving unit 14 is a component (e.g., a switching element (e.g., a transistor)) that drives the load 15 in response to a drive command from the control electronic component 11. An example of the load 15 is, but is not limited to, a buzzer.

[0025] In this way, the first substrate 10 is configured so that components related to control of loads and the like and components related to power supplies such as transformers are mounted on one substrate.

[0026] Furthermore, each component such as the control electronic component 11 is mounted on the front surface 10a of the first substrate 10. In other words, each component such as the control electronic component 11 is disposed on the surface of the first substrate 10 facing the second substrate 20 (front surface 10a).

[0027] In the example shown in Figures 1 and 2, each component such as the control electronic component 11 is mounted on the front surface 10a of the first substrate 10, but this is not limited to this, and some of the components may be mounted on the back surface 10b of the first substrate 10.

[0028] Furthermore, the components mounted on the first substrate 10 described above are merely examples and are not limited thereto, and some of the components may not be mounted on the first substrate 10. Furthermore, the positions on the first substrate 10 at which the components are mounted are also merely examples and are not limited thereto. Furthermore, the mounting of the components on the first substrate 10 may be surface mounting in which the components are connected via pads or the like provided on the surface of the first substrate 10, or insertion mounting in which the components are connected by inserting leads into through holes in the first substrate 10. Furthermore, the control electronic component 11, the transformer unit 12, and the load driver 14 may include electronic components such as resistors and capacitors.

[0029] Furthermore, the first substrate 10 is formed with an insertion hole 16 (see FIG. 2) through which a connection connector 23 of the second substrate 20, which will be described later, can be inserted. The first substrate 10 and the second substrate 20 are electrically connected by inserting the connection connector 23 into the insertion hole 16. The connection connector 23 and the insertion hole 16 can also be said to be a connecting member that connects the first substrate 10 and the second substrate 20 together.

[0030] The second substrate 20 is, for example, flat, and is formed in a rectangular or substantially rectangular shape in a plan view (viewed in the Z-axis direction). The second substrate 20 is formed so that its surface area is smaller than that of the first substrate 10. Specifically, the second substrate 20 is formed so that its surface area in a plan view (area in a plan view) is smaller than the surface area (area) of the first substrate 10. Conversely, the first substrate 10 is formed so that its surface area is larger than that of the second substrate 20. Specifically, the first substrate 10 is formed so that its surface area in a plan view (area in a plan view) is larger than the surface area (area) of the second substrate 20. The shape of the second substrate 20 shown in FIG. 1 is an example and is not limited thereto.

[0031] Various components that control the power supplied to the product are mounted on the second substrate 20. The second substrate 20 on which these various components are mounted is a so-called power supply module in which power supply components corresponding to the product are modularized.

[0032] The power supply module 120 will now be described with reference to Fig. 3. Fig. 3 is a block diagram showing an example of the configuration of the power supply module 120.

[0033] As shown in FIG. 3, the power supply module 120 includes an input unit 121, a filter unit 122, a smoothing unit 123, a SW unit (switch unit) 124, an output unit 125, a voltage detection unit 126, and a control unit 127.

[0034] The input unit 121 receives an AC current from, for example, an AC power supply A and outputs the input AC current to the filter unit 122. The filter unit 122 removes noise from the input AC current and outputs the result to the smoothing unit 123. The smoothing unit 123 converts the AC current input from the filter unit 122 into a DC current and outputs the result to the SW unit 124. The SW unit 124 reduces the voltage of the DC current input from the smoothing unit 123 and outputs the result to the output unit 125. The output unit 125 outputs the DC current reduced in voltage by the SW unit 124 to the first substrate 10 via the above-mentioned connection connector 23 (see FIG. 2).

[0035] The voltage detection unit 126 detects the voltage of the direct current output from the output unit 125, and outputs a signal indicating the detected voltage value to the control unit 127. The control unit 127 controls the SW unit 124 and the like based on various signals such as the signal indicating the voltage value. Note that the power supply module 120 may be configured without some elements such as the input unit 121.

[0036] The input unit 121, filter unit 122, smoothing unit 123, SW unit 124, output unit 125, voltage detection unit 126, and control unit 127 include electronic components such as FETs (field effect transistors), transistors, capacitors, transformers, varistors, resistors, and switching regulator ICs. These electronic components are related to the power supply supplied to the product, and are therefore referred to as "power supply electronic components 21" in this specification. As described above, such power supply electronic components 21 are mounted on the second substrate 20. An example of the configuration of the power supply module 120 including the second substrate 20 is that described in the Japan Institute of Invention and Innovation's Disclosure Technical Bulletin No. 2023-500268.

[0037] Next, the second substrate 20 on which the power supply electronic components 21 are mounted will be described with reference to Figures 4 to 6. Figure 4 is a plan view of the second substrate 20 as seen from the front surface 20a. Figure 5 is a side view of the second substrate 20, and Figure 6 is a bottom view of the second substrate 20 as seen from the back surface 20b.

[0038] 4 to 6, the power supply electronic components 21 are mounted on the front surface 20a and the back surface 20b of the second substrate 20. In the following, the power supply electronic components 21 mounted on the front surface 20a may be referred to as "power supply electronic components 21a," and the power supply electronic components 21 mounted on the back surface 20b may be referred to as "power supply electronic components 21b." Furthermore, the power supply electronic components 21b may be, for example, components that generate heat more easily than the power supply electronic components 21a and require appropriate cooling (e.g., FETs, transistors, etc.), but are not limited to this.

[0039] 4 to 6, the positions at which the power supply electronic components 21a and 21b are mounted on the second substrate 20 are merely examples and are not limited thereto. The power supply electronic components 21a and 21b may be mounted on the second substrate 20 by surface mounting, in which they are connected via pads or the like provided on the surface of the second substrate 20, or by insertion mounting, in which leads are inserted into through holes in the second substrate 20 for connection.

[0040] The second substrate 20 also includes the above-mentioned connection connectors 23. A plurality of connection connectors 23 (for example, two) are provided at each of diagonally opposite corners of the second substrate 20 in a plan view. The connection connectors 23 are pin-shaped and are formed to protrude from the rear surface 20b of the second substrate 20.

[0041] 1 and 2, the case 30 is a rectangular parallelepiped housing with an open upper surface (positive Z-axis direction). The first substrate 10 and the second substrate 20 are arranged in the internal space B of the case 30, and the case 30 accommodates the first substrate 10 and the second substrate 20. Specifically, the second substrate 20 is arranged above the first substrate 10 (positive Z-axis direction), and the first substrate 10 and the second substrate 20 are accommodated in the case 30 in an overlapping state. In other words, the first substrate 10 and the second substrate 20 are arranged to face each other. More specifically, the first substrate 10 and the second substrate 20 are arranged so that the front surface 10a of the first substrate 10 and the back surface 20b of the second substrate 20 face each other, and are accommodated in the case 30 in this state.

[0042] In this way, in the board unit 1 according to this embodiment, the first board 10 on which the control electronic components 11 and the like are mounted and the second board 20 on which the power supply electronic components 21 are mounted are combined into a unit. This allows the board unit 1 to be made smaller.

[0043] Note that first substrate 10, second substrate 20, and some or all of the components mounted on each substrate may be coated with resin or the like within case 30.

[0044] Here, the second substrate 20 overlapping the first substrate 10 has power supply electronic components 21 mounted on the back surface 20b side. More specifically, the second substrate 20 has power supply electronic components 21b mounted on the back surface 20b side, which is the surface facing the first substrate 10. As described above, such power supply electronic components 21b are components that generate heat relatively easily.

[0045] Therefore, the board unit 1 according to this embodiment is configured to be able to appropriately cool the power supply electronic components 21b and improve heat dissipation.

[0046] This configuration will be described below with reference to Figures 7 and 8. Figure 7 is a plan view of the first substrate 10 as seen from the front surface 10a. Figure 8 is a cross-sectional view taken along line VIII-VIII in Figure 7.

[0047] 7, the first substrate 10 has an exposed portion 18. The exposed portion 18 is formed in a rectangular or substantially rectangular shape in a plan view (when viewed in the Z-axis direction). Note that the shape of the exposed portion 18 shown in FIG. 7 and other figures is merely an example and is not intended to be limiting.

[0048] The exposed portion 18 is a portion that is not covered with a surface layer on the surface (front surface 10a) facing the second substrate 20. The first substrate 10 having the exposed portion 18 will be described with reference to FIG.

[0049] 8, the first substrate 10 includes a base 101, a copper foil portion 102, and surface layers 103 and 104. The base 101 is a flat plate-shaped member made of, for example, resin. Although not shown, conductive patterns such as electrodes and wiring are provided on the base 101 at positions where electronic components such as the control electronic component 11 are to be mounted.

[0050] The copper foil portion 102 is a flat (thin) copper member, and is provided on the front surface 101a side of the base 101. In other words, the copper foil portion 102 is provided on the surface (front surface 10a) facing the second substrate 20 (see FIG. 2). The copper foil portion 102 is exposed without being covered by the surface layer 103, and therefore functions as the exposed portion 18. Note that, although the present embodiment shows an example in which the copper foil portion 102 is used as the exposed portion 18, this is not limiting. In other words, the exposed portion 18 may be a member made of a material with a relatively high thermal conductivity (for example, iron, aluminum, or other metals).

[0051] The surface layer 103 is a resist provided on the front surface 101a side of the base 101 and covering the front surface 101a side. The surface layer 104 is a resist provided on the back surface 101b side of the base 101 and covering the back surface 101b side.

[0052] As described above, the surface layer 103 is formed so as not to cover the copper foil portion 102. In this embodiment, for example, the surface layer 103 is formed on the front surface 101a of the base 101, including the copper foil portion 102, and then the surface layer 103 formed on the copper foil portion 102 is peeled off, so that the surface layer 103 does not cover the copper foil portion 102, but this is not limiting. That is, the surface layer 103 may not cover the copper foil portion 102 by other methods, such as not forming the surface layer 103 on the copper foil portion 102.

[0053] The thermal conductivity of the copper foil portion 102 is set to be higher than the thermal conductivity of the surface layer (resist) 103. In other words, the exposed portion 18 formed by the copper foil portion 102 has higher heat dissipation properties than the surface layer (resist) 103.

[0054] Next, the position where exposed portion 18 is formed on first substrate 10 will be described in detail with reference to Fig. 7. As shown by dashed lines in Fig. 7, front surface 10a, which is the main surface of first substrate 10, is divided into mounting area 19a and substrate overlapping area 19b. Mounting area 19a is an area where control electronic components 11, transformer section 12, connector 13, load driver 14, load 15, etc. are mounted. Substrate overlapping area 19b is an area where second substrate 20 to be combined overlaps.

[0055] The exposed portion 18 is formed in the substrate overlapping region 19b of the first substrate 10. More specifically, the exposed portion 18 is formed so as to be in a position corresponding to the power supply electronic components 21b mounted on the back surface 20b of the second substrate 20 when the second substrate 20 is in an overlapping state of the first substrate 10. In other words, in a plan view of the first substrate 10, the exposed portion 18 is formed so as to be in a position that includes the portions of the power supply electronic components 21b mounted on the back surface 20b of the second substrate 20 when the second substrate 20 is in an overlapping state. Note that in Figures 1 and 6, the exposed portion 18 is shown by imaginary lines to help understand the positional relationship between the exposed portion 18 and the power supply electronic components 21b.

[0056] In this way, the exposed portion 18 is arranged in the substrate overlapping region 19b, while the control electronic components 11 and the like are arranged in the mounting region 19a. That is, the control electronic components 11 and the like are arranged in positions other than the exposed portion 18 of the first substrate 10. In other words, the control electronic components 11 and the like are arranged in positions relatively far from the exposed portion 18 of the first substrate 10.

[0057] 2, in the board unit 1 according to this embodiment, the power supply electronic component 21b is arranged so as to abut against the exposed portion 18. More specifically, the power supply electronic component 21b mounted on the rear surface 20b of the second board 20 is arranged so as to abut (contact) against the exposed portion 18 of the first board 10. As a result, heat generated in the power supply electronic component 21b is dissipated via the exposed portion 18, thereby cooling the power supply electronic component 21b.

[0058] In this way, by abutting the power supply electronic component 21b of the second substrate 20 against the exposed portion 18 of the first substrate 10 that is not covered by the surface layer (resist) 103, the exposed portion 18 can function as a heat sink to cool the power supply electronic component 21b, thereby improving the heat dissipation properties of the substrate unit 1.

[0059] Furthermore, because the exposed portion 18 functions as a heat sink, an additional cooling mechanism such as a heat sink is not required, allowing the board unit 1 to be made smaller. Furthermore, because the power supply electronic component 21b of the second board 20 is disposed so as to abut against the exposed portion 18 of the first board 10, a space for the power supply electronic component 21b can be secured between the opposing first board 10 and second board 20. Therefore, spacers or the like for securing such a space are not required, and the height H1 (see FIG. 2) of the combined first board 10 and second board 20 can be reduced, thereby allowing the height H2 (see FIG. 2) of the board unit 1 to be reduced. Furthermore, eliminating the need for the heat sink and spacers is advantageous in terms of manufacturing costs for the board unit 1.

[0060] Furthermore, the surface area of ​​the first substrate 10 is configured to be larger than the surface area of ​​the second substrate 20. This makes it possible to ensure a relatively large exposed portion 18 on the first substrate 10, thereby ensuring sufficient cooling performance by the exposed portion 18; in other words, it is possible to reliably improve the heat dissipation performance of the substrate unit 1. Furthermore, because the surface area of ​​the first substrate 10 is larger than the surface area of ​​the second substrate 20, it is possible to arrange the power supply electronic components 21b of the second substrate 20 and the control electronic components 11, etc. of the first substrate 10 relatively far apart, thereby preventing heat generated by the power supply electronic components 21b from affecting the control electronic components 11, etc.

[0061] Furthermore, the control electronic components 11 are disposed at a position other than the exposed portion 18 of the first substrate 10. This allows the control electronic components 11 to be disposed at a position relatively far away from the exposed portion 18, thereby preventing heat generated by the power supply electronic components 21b mounted on the second substrate 20 from affecting the control electronic components.

[0062] Furthermore, the control electronic components 11 are disposed on the surface (front surface 10a) of the first substrate 10 facing the second substrate 20. This allows the height H2 of the substrate unit 1 to be reduced compared to when the control electronic components 11 are disposed on the surface (back surface 10b) of the first substrate 10 opposite the second substrate 20 side. That is, when the control electronic components 11 are disposed on the surface (back surface 10b) of the first substrate 10 opposite the second substrate 20 side, the height of the control electronic components 11 and the height (thickness) of the second substrate 20 do not overlap, so the height of the substrate unit 1 includes the sum of the heights of the control electronic components 11 and the height of the second substrate 20. In contrast, when the control electronic components 11 are disposed on the surface (front surface 10a) of the first substrate 10 facing the second substrate 20, the height of the control electronic components 11 and the height (thickness) of the second substrate 20 partially overlap, so the height H2 of the substrate unit 1 can be reduced. Furthermore, if the control electronic components 11 are configured to be disposed at a position other than the exposed portion 18 of the first substrate 10, the height H2 of the substrate unit 1 can be prevented from depending on the height of the control electronic components 11.

[0063] In the above embodiment, the length L1 (see FIG. 7) of the side (short side) of the first substrate 10 in a plan view and the length L2 (see FIG. 4) of the side (short side) of the second substrate 20 are set to be the same or approximately the same, but this is not limiting, and the length L1 of the side of the first substrate 10 and the length L2 of the side of the second substrate 20 may be set to be different. That is, for example, the length L1 of the side of the first substrate 10 may be set to be longer than the length L2 of the side of the second substrate 20 (L1>L2).

[0064] 4, 7, etc. are merely examples and are not intended to be limiting. That is, the positions of the connector 23 and the insertion holes 16 may be different from those shown in FIGS. 4, 7, etc. (for example, the four corners of the first and second substrates 10, 20).

[0065] <Additional Notes> (1) a first substrate on which electronic control components are mounted; a second substrate on which power supply electronic components are mounted and which is disposed so that the surface on which the power supply electronic components are mounted faces the first substrate; Equipped with the first substrate has an exposed portion that is not covered by a surface layer on a surface facing the second substrate; The power supply electronic component is disposed so as to abut against the exposed portion. Board unit. (2) The surface area of ​​the first substrate is larger than the surface area of ​​the second substrate. The substrate unit described in (1). (3) the control electronic component is disposed at a position other than the exposed portion of the first substrate; A substrate unit according to (1) or (2). (4) The control electronic components are arranged on the surface of the first substrate facing the second substrate. The substrate unit according to any one of (1) to (3).

[0066] Further advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. [Explanation of symbols]

[0067] 1 PCB unit 10 First board 11 Control electronic components 18 Exposed part 20 Second board 21b Power supply electronic components 103 Surface layer

Claims

1. a first substrate on which electronic control components are mounted; a second substrate on which power supply electronic components are mounted and which is disposed so that the surface on which the power supply electronic components are mounted faces the first substrate; Equipped with the first substrate has an exposed portion that is not covered by a surface layer on a surface facing the second substrate; The power supply electronic component is disposed so as to abut against the exposed portion. Board unit.

2. The surface area of ​​the first substrate is larger than the surface area of ​​the second substrate. The substrate unit according to claim 1 .

3. the control electronic component is disposed at a position other than the exposed portion of the first substrate; The substrate unit according to claim 1 or 2.

4. the control electronic components are disposed on the surface of the first substrate facing the second substrate; The substrate unit according to claim 1 or 2.

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