Circuit board

Abstract

To make it easier to control the height dimensions of circuit boards where electronic components are covered with resin material, as well as the spread dimensions of the resin material. [Solution] A circuit board 1 comprising an FPC (flexible printed circuit board) 2, a thermistor 3 mounted on the FPC 2, a frame component 4 fixed to the surface of the FPC 2 on which the thermistor 3 is mounted and surrounding the thermistor 3, and a resin material 5 filling the space 4C surrounded by the inner circumferential surface 4B of the frame component 4 and covering the thermistor 3. The presence of the frame component 4 prevents the final shape of the resin material 5 from being determined by chance. This makes it easier to control the height dimension of the circuit board 1 and the spread dimension of the resin material 5.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a circuit board.

Background Art

[0002] Conventionally, a circuit board including a printed board, electronic components mounted on the printed board, and a resin material covering the electronic components has been known (see, for example, Patent Document 1). Specifically, the invention described in Patent Document 1 includes a flexible printed board, a current limiting element mounted on the flexible printed board, and an insulating resin overcoating the current limiting element. Patent Document 1 describes that since the current limiting element is overcoated with an insulating resin, the electrodes of the current limiting element are not short-circuited by water droplets or the like formed due to dew condensation.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The invention described in Patent Document 1 had room for improvement in covering electronic components with a resin material. This specification discloses a technique for facilitating the management of the height dimension of a circuit board in which electronic components are covered with a resin material and the spreading dimension of the resin material.

Means for Solving the Problems

[0005] The circuit board according to this disclosure comprises a printed circuit board, electronic components mounted on the printed circuit board, a frame component fixed to the surface of the printed circuit board on which the electronic components are mounted and surrounding the electronic components, and a resin material filling the space surrounded by the inner circumferential surface of the frame component and covering the electronic components. [Effects of the Invention]

[0006] According to this disclosure, it becomes easier to control the height dimension of the circuit board in which electronic components are covered with resin material, as well as the spread dimension of the resin material. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a top view of a circuit board according to Embodiment 1. [Figure 2] Figure 2 is a cross-sectional view of the circuit board along line AA shown in Figure 1. [Figure 3] Figure 3 is a bottom view of the circuit board. [Figure 4] Figure 4 is a schematic cross-sectional view showing a cross-section of a circuit board according to Embodiment 2. [Modes for carrying out the invention]

[0008] [Description of Embodiments in this Disclosure] First, the embodiments of this disclosure will be listed and described.

[0009] (1) The circuit board according to the present disclosure comprises a printed circuit board, electronic components mounted on the printed circuit board, a frame component fixed to the surface of the printed circuit board on which the electronic components are mounted and surrounding the electronic components, and a resin material filling the space surrounded by the inner circumferential surface of the frame component and covering the electronic components.

[0010] The invention described in Patent Document 1, mentioned above, has the problem that the final shape of the insulating resin is determined by chance, making it difficult to control the dimensions. Specifically, as shown in Figure 5 of the same document, the insulating resin described in the document is thicker in the center and becomes thinner towards the edges. For this reason, it is necessary to apply a thick overcoat to prevent the corners of the electronic components from being exposed or to prevent the insulating resin from becoming thin at the corners of the electronic components. However, applying a thick overcoat means that the final thickness of the circuit board becomes unpredictable, making it difficult to control the height of the circuit board when there are strict constraints on its height. Furthermore, applying a thick overcoat also means that the spread of the insulating resin becomes unpredictable, making it difficult to control the spread of the insulating resin. In contrast, the circuit board described in (1) above has a frame component which prevents the final shape of the resin material from being determined by chance. This makes it easier to control the height dimension of the circuit board where the electronic components are covered by the resin material, as well as the spread dimension of the resin material.

[0011] (2) In the circuit board described in (1) above, the resin material may be contained within the space.

[0012] According to the circuit board described in (2) above, since the resin material is contained within the space (in other words, the resin material does not protrude from the space), the height of the circuit board can be controlled by the height of the frame component rather than the resin thickness. Therefore, it becomes easier to control the height dimension when there are strict constraints on the height of the circuit board.

[0013] (3) In the circuit board described in (2) above, the side of the resin material opposite to the printed circuit board may be a concave surface that is recessed toward the printed circuit board.

[0014] According to the circuit board described in (3) above, since the resin material is recessed in a concave shape, it is possible to more reliably suppress the resin material from protruding from the space.

[0015] (4) In the circuit board according to any one of (1) to (3) above, the inner peripheral surface of the frame component may be tapered such that the inner diameter decreases from one side to the other side in a direction orthogonal to the board surface of the printed board.

[0016] According to the circuit board described in (4) above, when one side is the printed board side with respect to the frame component and the other side is the side opposite to the printed board, the inner diameter decreases in the direction away from the printed board. By doing so, since the resin material is suppressed by the inner peripheral surface of the frame component, it becomes difficult for the resin material to come off. Conversely, when one side is the side opposite to the printed board with respect to the frame component and the other side is the printed board side, the inner diameter decreases toward the printed board. By doing so, since the inner peripheral surface of the frame component is suppressed by the resin material, it becomes difficult for the frame component to come off. <统一编号:

[0017] (5) In the circuit board according to any one of (1) to (N) above, the printed board is a flexible printed board, and on the surface of the flexible printed board opposite to the surface on which the electronic components are mounted, a plate-like component may be attached in a range including the area where the electronic components are projected onto the opposite surface.

[0018] According to the circuit board described in (5) above, due to the presence of the plate-like component, physical protection of the flexible printed board and improvement of strength can be achieved.

[0019] [Details of Embodiments of the Present Disclosure] Details of embodiments of the present disclosure will be described below. The present disclosure is not limited to these examples, but is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0020] <Embodiment 1> Embodiment will be described with reference to FIGS. 1 to 3. In the following description, the front-rear direction and the left-right direction are based on the front-rear direction and the left-right direction shown in FIG. 1, and the up-down direction is based on the up-down direction shown in FIG. 2. Note: The "统一编号:0000084" in the original Chinese text seems to be an incorrect or unclear expression. I have translated it as "<统一编号:0...>". You may need to check and correct it if there is a specific correct format or content for this part. Also, the "(1) to (N)" is a placeholder in the original text, and you may need to replace it according to the actual content.

[0021] [1] Circuit board Referring to Figure 1, the circuit board 1 according to Embodiment 1 will be described. The circuit board 1 is a temperature detection circuit board that is disposed on the upper or lower surface of a predetermined device to detect the temperature of the device. The circuit board 1 comprises a flexible printed circuit board 2 (FPC) as a printed circuit board, a thermistor 3 as an electronic component, a frame component 4, a resin material 5 (see Figure 2), and a metal plate 6 (see Figure 2) as a plate-shaped component. In the following description, the flexible printed circuit board 2 will be referred to as FPC2.

[0022] [1-1] FPC As shown in Figure 2, the FPC2 comprises a base layer 2A made of a thin insulating material such as a plastic film, a temperature detection line 2B formed by patterning copper foil formed on the base layer 2A, and a coverlay layer 2C made of a thin insulating material. An opening 2D is formed in the coverlay layer 2C where the thermistor 3 is mounted, and the temperature detection line 2B is exposed.

[0023] [1-2] Thermistor Thermistor 3 is an electronic component that detects temperature. A PTC (Positive Temperature Coefficient) thermistor or an NTC (Negative Temperature Coefficient) thermistor can be used. The electrode 3A of thermistor 3 is soldered to the temperature detection line 2B with solder 7. If there are strict height constraints on the circuit board 1, a thin thermistor 3 is preferable.

[0024] [1-3] Frame parts As shown in Figure 1, the frame component 4 is fixed to the surface on which the thermistor 3 is mounted in the FPC 2, and surrounds the thermistor 3. The frame component 4 is rectangular in top view, and has a roughly circular through-hole 4A that penetrates it in the vertical direction (perpendicular to the plane of the paper in Figure 1). The shape of the frame component 4 is not limited to a rectangle, and any suitable shape can be adopted. The shape of the through-hole 4A is also not limited to a roughly circular shape, and any suitable shape can be adopted.

[0025] The frame component 4 is made of an insulating resin material. The frame component 4 is fixed to the FPC2 using double-sided tape or adhesive after the thermistor 3, which is mounted on the FPC2 during the mounting process, is heated and soldered during the reflow process. The reason the frame component 4 is fixed after the reflow process is that, since the frame component 4 is made of resin, there is a risk that it will melt due to the heat of the reflow process if it is fixed before the reflow process.

[0026] As shown in Figure 2, the frame component 4 has a certain thickness. Specifically, the thickness of the frame component 4 (in other words, its width in the vertical direction) is greater than the thickness of the thermistor 3. Therefore, the thermistor 3 is contained within the space 4C surrounded by the inner circumferential surface 4B of the frame component 4. The inner circumferential surface 4B of the frame component 4 according to Embodiment 1 is tapered, with the inner diameter narrowing from the lower side (one side) to the upper side (the other side) in the vertical direction (an example of a direction perpendicular to the surface of the printed circuit board). Therefore, the inner diameter of the inner circumferential surface 4B narrows in the direction away from the FPC2.

[0027] [1-4] Resin materials The resin material 5 is provided to insulate and waterproof the thermistor 3. The resin material 5 is filled (potted) into the space 4C of the frame component 4 and covers the entire thermistor 3. The resin material 5 is, for example, an epoxy resin mixed with a hardening agent that has been cured with ultraviolet light, and has insulating and waterproof properties. The material of the resin material 5 is not limited to epoxy resin; other materials may be used as long as they can be filled into the space 4C and cured, and have insulating and waterproof properties. The resin material 5 is contained within space 4C and does not protrude above space 4C. More specifically, the upper surface 5A of the resin material 5 (in other words, the surface 5A of the resin material 5 opposite to FPC2) is concave towards FPC2.

[0028] [1-5]Metal plate The metal plate 6 (an example of a plate-shaped component) is attached to the back surface of the FPC2 (in other words, the side of the FPC2 opposite to the side on which the thermistor 3 is mounted). The metal plate 6 is made of, for example, copper or aluminum. Specifically, as shown in Figure 3, the metal plate 6 is attached to the area on the back surface of the FPC 2 that includes the region where the thermistor 3 is projected onto the back surface. In the example shown in Figure 3, the metal plate 6 is attached to an area that includes not only the region where the thermistor 3 is projected onto the back surface, but also the region where the frame component 4 is projected onto the back surface. The reason for attaching the metal plate 6 is to provide physical protection for the FPC 2, improve its strength, and improve the temperature measurement accuracy of the thermistor 3.

[0029] [2] Effects of the embodiment As shown in Figure 2, according to the circuit board 1 of Embodiment 1, the presence of the frame component 4 prevents the final shape of the resin material 5 from being determined by chance. Therefore, it becomes easier to control the height dimension of the circuit board 1 where the thermistor 3 is covered by the resin material 5, and the spread dimension of the resin material 5.

[0030] According to circuit board 1, since the resin material 5 is contained within space 4C (in other words, the resin material 5 does not protrude from space 4C), the height of circuit board 1 can be controlled by the height of the frame component 4 rather than the resin thickness. Therefore, it becomes easier to control the height dimension when there are strict constraints on the height of circuit board 1.

[0031] According to the circuit board 1, the upper surface 5A of the resin material 5 is concave, which more reliably prevents the resin material 5 from protruding from the space 4C.

[0032] According to the circuit board 1, the inner diameter of the inner circumferential surface 4B of the frame component 4 narrows in the direction away from the FPC 2. This arrangement holds the resin material 5 in place by the inner circumferential surface 4B of the frame component 4, making it less likely for the resin material 5 to come loose.

[0033] According to circuit board 1, the presence of the metal plate 6 provides physical protection and improves the strength of the FPC 2. If the electronic component is a thermistor 3, the metal plate 6 can also improve the accuracy of temperature measurement by absorbing heat from the object being measured.

[0034] <Embodiment 2> Referring to Figure 4, the circuit board 201 according to Embodiment 2 will be described. The inner circumferential surface 204B of the frame component 204 of the circuit board 201 is tapered, with the inner diameter narrowing from the upper side (one side) to the lower side (the other side) in the vertical direction (an example of a direction perpendicular to the board surface of the printed circuit board). Therefore, the inner diameter of the inner circumferential surface 204B narrows toward the FPC2. In this way, the inner circumferential surface 204B of the frame component 204 is held in place by the resin material 5, making it difficult for the frame component 204 to come off.

[0035] <Other Embodiments> The technology disclosed herein is not limited to the embodiments described above in the description and drawings, and the following embodiments, for example, are also included in the technical scope disclosed herein.

[0036] (1) In the above embodiment, thermistor 3 was used as an example of an electronic component, but the electronic component is not limited to thermistor 3 and may be other electronic components. For example, the electronic component may be a chip fuse.

[0037] (2) In the above embodiment, the case in which the resin material 5 is contained within space 4C was illustrated. In contrast, if, for example, there are no strict constraints on the height dimension of the circuit board 1 and only the spread dimension of the resin material 5 needs to be controlled, the resin material 5 may protrude above space 4C.

[0038] (3) In the above embodiment, the upper surface 5A of the resin material 5 was shown to be concave, but the upper surface 5A does not have to be concave as long as the resin material 5 does not protrude above the space 4C. For example, the upper surface 5A may be a flat surface that is flush with the upper surface of the frame component 4.

[0039] (4) In the above embodiment, the resin material 5 was shown as having insulating and waterproof properties, but the resin material 5 may have only one of these properties. For example, if the circuit board 1 is located in a place where the possibility of short circuits is low, the resin material 5 does not need to have insulating properties. Alternatively, if the circuit board 1 is located in a place that is completely sealed and where condensation is unlikely to occur, the resin material 5 does not need to have waterproof properties.

[0040] (5) In the above embodiment, the case in which the inner circumferential surface 4B of the frame component 4 is tapered was illustrated, but the inner circumferential surface 4B does not have to be tapered. That is, the inner diameter of the inner circumferential surface 4B of the frame component 4 may be constant from top to bottom.

[0041] (6) In the above embodiment, the frame component 4 is shown as being made of resin, but even if the frame component 4 is made of metal, if the possibility of the circuit board 1 short-circuiting is low, the frame component 4 may be made of metal. However, in order to reliably protect the circuit board 1 from short-circuiting, it is preferable that the frame component 4 be made of resin.

[0042] (7) In the above embodiment, the case in which a metal plate 6 is attached to the back surface of the FPC2 was illustrated, but the metal plate 6 does not have to be attached.

[0043] (8) In the above embodiment, a metal plate 6 was used as an example of a plate-shaped part, but the material of the plate-shaped part is not limited to metal, and may be resin.

[0044] (9) In the above embodiment, FPC2 was used as an example of a printed circuit board, but the printed circuit board may be a rigid printed circuit board (a so-called rigid board). An example of a rigid board is a so-called glass epoxy board, which is made by impregnating glass fibers with epoxy resin.

[0045] (10) As mentioned above, the shape of the through hole 4A of the frame component 4 is not limited to a roughly circular shape, and any suitable shape can be adopted. For example, the through hole 4A may be square, rectangular, elliptical, or a so-called racetrack shape consisting of two parallel lines and two semicircles. The shape of the through-hole 4A may be one that closely matches the shape of the electronic component. For example, if the electronic component is rectangular, making the through-hole 4A rectangular will allow the distance between the electronic component and the inner surface of the through-hole 4A to be roughly constant around the entire circumference of the electronic component. In this way, the creepage distance from any point a certain distance away from the electronic component to the electronic component can be made roughly constant. [Explanation of Symbols]

[0046] 1: Circuit board 2: FPC (Flexible Printed Circuit Board) 2A: Base layer 2B: Temperature detection line 2C: Coverlay layer 2D: Opening 3: Thermistor 3A: Electrode 4: Frame parts 4A: Through hole 4B: Inner surface 4C: Space 5: Resin material 5A: Top 6: Metal plate 7: Handa 201: Circuit board 204: Frame parts 204B: Inner surface

Claims

1. Printed circuit board and The electronic components mounted on the aforementioned printed circuit board, A frame component is fixed to the surface of the printed circuit board on which the electronic components are mounted, and surrounds the electronic components. A resin material that fills the space surrounded by the inner circumferential surface of the frame component and covers the electronic component, A circuit board equipped with the following features.

2. A circuit board according to claim 1, A circuit board in which the aforementioned resin material is housed within the aforementioned space.

3. The circuit board according to claim 2, A circuit board in which the side of the resin material opposite to the printed circuit board is concave, recessed toward the printed circuit board.

4. A circuit board according to any one of claims 1 to 3, A circuit board in which the inner circumferential surface of the frame component is tapered, with the inner diameter narrowing from one side to the other in a direction perpendicular to the surface of the printed circuit board.

5. A circuit board according to any one of claims 1 to 3, The aforementioned printed circuit board is a flexible printed circuit board, A circuit board in which a plate-shaped component is attached to the side of the flexible printed circuit board opposite to the side on which the electronic components are mounted, in a region that includes the area obtained by projecting the electronic components onto the opposite side.

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