JP2019121747A - Circuit board - Google Patents

Abstract

To provide a circuit board that can prevent a moisture-proof agent from flowing into a screw hole.SOLUTION: A circuit board 10 includes a substrate 11 on which an electronic component is mounted, and screw holes 111 to 116 provided in the substrate 11 for mounting the substrate 11. After the electronic component is mounted on the substrate 11, a moisture-proof agent 12 is applied. Between a region R21 in which the moisture-proof agent 12 is applied and the screw holes 111 to 116, protrusions 131 to 136 are provided to prevent the moisture-proof agent 12 from flowing into the screw holes 111 to 116.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a circuit board on which electronic components are mounted.

  Circuit boards on which electronic components are mounted are mounted on various products. For example, in order to control a passenger car, an on-vehicle circuit board is mounted on the passenger car. In the circuit board of this type, a moisture proofing agent may be applied to the surface of the substrate after the mounting of the electronic component in order to protect the electronic component and circuit from moisture. For example, in a circuit board in which a high density electronic component and an atmospheric pressure sensor are mounted on the same electronic substrate, a moistureproof agent is applied to a region where the high density electronic component is disposed. It is described that the moisture proofing agent is not applied to the area where the pressure sensor is disposed.

JP, 2011-148363, A

  The circuit board is provided with screw holes for screwing the circuit board to the apparatus body. The moisture proofing agent is applied so as not to get caught in the screw hole. However, in the case where the amount of the moisture-proof agent applied is large, even if the moisture-proof agent is applied avoiding the screw holes, an excess of the moisture-proof agent may flow into the screw holes. In this case, when the circuit board is screwed to the apparatus main body, the moisture-proof agent may be attached to the screw and the screw may be defective.

  In view of such a subject, an object of the present invention is to provide a circuit board which can prevent a moisture-proof agent from flowing into a screw hole.

  A circuit board according to a main aspect of the present invention comprises a substrate on which an electronic component is mounted, a screw hole provided in the substrate for mounting the substrate, a region to which a moisture-proof agent is applied, and the screw hole. And a projection provided between the two for preventing the moisture-proof agent from flowing into the screw hole.

  According to the circuit board according to the present aspect, even if the amount of the applied moisture proofing agent is large, the excess moisture proofing agent flows into the screw hole because the protruding moment acts as a barrier and is stopped by the protruding moment There is no. Therefore, the moisture proof agent can be prevented from flowing into the screw hole, and the moisture proof agent can be prevented from adhering to the screw and the screw becoming defective.

  In the aspect, it is preferable that the protrusion is formed to surround the screw hole. This makes it possible to prevent the moisture proofing agent from flowing into the screw well from any direction on the substrate toward the screw well.

  Moreover, it is preferable that the said protrusion is continuously formed continuously. In this case, it is possible to prevent the moisture-proof agent from protruding from the gap between the protrusions and flowing into the screw hole. Therefore, it is possible to more reliably prevent the dampproofing agent from flowing into the screw hole.

  In the case where a ground electrode is provided around the screw hole, the protrusion may be provided between the region to which the moistureproof agent is applied and the electrode. In this case, the moistureproof agent can be prevented from being applied to the electrode, and the circuit board can be reliably connected to the ground via the electrode.

  Further, the protrusion may be formed of ink for printing on the substrate. In this case, since the protrusions can be formed in the printing process, the protrusions need not be integrally formed on the substrate in advance. Therefore, the configuration of the substrate can be simplified, and the cost of the circuit substrate can be reduced.

  As described above, according to the present invention, it is possible to provide a circuit board that can prevent the moisture proof agent from flowing into the screw holes.

  The effects and significances of the present invention will become more apparent from the description of the embodiments shown below. However, the embodiment shown below is merely an example when implementing the present invention, and the present invention is not limited to the one described in the following embodiment.

FIG. 1 is a plan view showing the configuration of a circuit board according to the embodiment. FIGS. 2A and 2B are cross-sectional views showing the configuration near the screw hole of the circuit board according to the comparative example. Drawing 3 (a) and (b) is a sectional view showing the composition near the screw hole of the circuit board concerning each embodiment, respectively. FIG. 4 is a cross-sectional view showing the configuration in the vicinity of the screw hole in a state in which the circuit board is screwed to the support frame on the apparatus body side according to the embodiment. Fig.5 (a) thru | or (d) are top views which show the structure of the protrusion concerning a modification. 6 (a) and 6 (b) are cross-sectional views showing the configuration near the screw hole of the circuit board according to another modification, respectively.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, for example, the present invention is applied to an on-vehicle circuit board. In the drawings, XYZ axes orthogonal to each other are added as appropriate. The Z-axis direction is the thickness direction of the circuit board, and the X-axis direction and the Y-axis direction are the longitudinal direction and the latitudinal direction of the circuit board, respectively.

  FIG. 1 is a plan view showing the configuration of the circuit board 10.

  As shown in FIG. 1, the circuit board 10 includes a substrate 11 on which an electronic component is mounted, and a moistureproof agent 12 applied to the surface of the substrate 11. The substrate 11 has a rectangular corner rounded contour. Electronic components are mounted on the regions R11, R12, R13, and R14 on the substrate 11, respectively. In these regions R11 to R14, wiring patterns for connecting the mounted electronic components are formed.

  After the electronic components are mounted in the regions R11 to R14, the moistureproof agent 12 is applied. The region R21 to which the moisture proofing agent 12 is applied includes the regions R11 to R14 in which the electronic component is mounted, and is set to be slightly larger than the boundaries in the X axis direction and the Y axis direction of these regions R11 to R14. . The moistureproof agent 12 is made of an insulating material having excellent moisture resistance. For example, Humiceal (registered trademark) can be used as the moistureproof agent 12.

  The substrate 11 is provided with screw holes 111 to 116 for installing the substrate 11 in the support frame. In addition, electrodes 121 to 126 for connecting the circuit board 10 to the ground are provided around the screw holes 111 to 116, respectively. The electrodes 121 to 126 are connected to the ground layer of the circuit board 10.

  As described later, conductive screws are fitted in the screw holes 111 to 116, and the circuit board 10 is screwed to the conductive support frame. Thereby, the electrodes 121 to 116 are electrically connected to the support frame via the screws. Thus, the ground layer of the circuit board 10 is connected to the ground, and the circuit of the circuit board 10 is grounded.

  Furthermore, projections 131 to 136 are provided on the substrate 11 between the region R 21 to which the moistureproof agent 12 is applied and the screw holes 111 to 116. The protrusions 131 to 136 are formed to surround the screw holes 111 to 116, respectively. Moreover, the protrusions 131 to 136 are respectively formed continuously without interruption. The protrusions 131 to 136 suppress the flow of the moistureproof agent 12 into the screw holes 111 to 116. The height of the protrusions 131 to 136 is about several tens of μm. In the present embodiment, the protrusions 131 to 136 are integrally formed in advance on the substrate 11 before the electronic component is mounted.

  Next, the operation of the protrusions 131 to 136 will be described. First, as a comparative example, a problem in the circuit board 10 having a configuration in which the protrusions 131 to 136 are not provided will be described.

  FIGS. 2A and 2B are cross-sectional views showing the configuration near the screw hole 115 of the circuit board 10 according to the comparative example. FIGS. 2A and 2B show cross-sectional views in the case where the central position of the screw hole 115 in the Y-axis direction is cut along a plane parallel to the XZ plane.

  FIG. 2A shows a state in which the moistureproof agent 12 is properly applied without protruding from the region R21. In this case, the moistureproof agent 12 stops at a position retracted from the electrode 125, and the moistureproof agent 12 does not flow into the screw hole 115 beyond the electrode 125.

  FIG. 2B shows, for example, a state in which the moistureproof agent 12 protrudes from the region R21 in the coating process because the amount of the moistureproofer 12 applied is large. Here, on the positive side of the screw hole 115 on the X axis, the excess moistureproof agent 12 protrudes from the region R21 and flows into the screw hole 115. In this case, when the circuit board 10 is screwed to the support frame on the apparatus main body side, the moisture-proof agent may be attached to the screw and the screw may be defective.

  In the present embodiment, since the protrusions 131 to 136 are provided as described above, such a problem can be solved.

  FIGS. 3A and 3B are cross-sectional views showing the configuration in the vicinity of the screw hole 115 of the circuit board 10 according to the embodiment. FIGS. 3A and 3B show cross-sectional views in the case where the central position of the screw hole 115 in the Y-axis direction is cut along a plane parallel to the XZ plane.

  FIG. 3A shows a state in which the moistureproof agent 12 is properly applied without protruding from the region R21. In this case, the moistureproof agent 12 stops at a position retracted from the electrode 125 and the protrusion 135, and the moistureproof agent 12 does not flow into the screw hole 115 beyond the electrode 125.

  FIG. 3B shows, for example, a state in which the moistureproof agent 12 protrudes from the region R21 in the coating step because the amount of the moistureproofer 12 applied is large. Here, as in the above-described comparative example, an excess of the moisture proofing agent 12 protrudes from the region R21 on the X axis positive side of the screw hole 115. In the present embodiment, since the protrusion 135 is provided between the region R 21 and the screw hole 115, the moistureproof agent 12 protruding from the region R 21 is stopped by the protrusion 135 with the protrusion 135 serving as a barrier. . For this reason, the moistureproof agent 12 does not reach the electrode 125 and does not flow into the screw hole 115 beyond the electrode 125. Therefore, when the circuit board 10 is screwed to the support frame on the apparatus main body side, the moisture-proof agent can be prevented from adhering to the screw and the screw becoming defective.

  FIG. 4 is a cross-sectional view showing the configuration in the vicinity of the screw hole 115 in a state in which the circuit board 10 is screwed to the support frame 20 on the apparatus body side according to the embodiment. FIG. 4 shows a cross-sectional view in the case where the central position of the screw hole 115 in the Y-axis direction is cut along a plane parallel to the XZ plane.

  As shown in FIG. 4, the circuit board 10 is screwed to the support frame 20 by the screws 30 in a state of being mounted on the support frame 20. The support frame 20 is made of a conductive material, and the screw 30 is also made of a conductive material. With the screw holes 115 fitted in the stop holes 21 of the support frame 20, the screws 30 are fitted into the screw holes 115, and the circuit board 10 is screwed to the support frame 20. At this time, the lower surface of the umbrella portion of the screw 30 contacts the electrode 125. Thus, the electrode 125 is electrically connected to the support frame 20 via the screw 30. Thus, the ground layer of the circuit board 10 is connected to the ground, and the circuit of the circuit board 10 is grounded.

  In the present embodiment, as described above, even if the moisture proofing agent 12 sticks out of the region R21, the moisture proofing agent 12 does not get caught on the electrode 125 because the protruding moisture proofing agent 12 is stopped by the projection 135. Therefore, as shown in FIG. 4, in the state where the screw 30 is stopped, the moisture proofing agent 12 is not sandwiched between the screw 30 and the electrode 125 and the electrical connection between the screw 30 and the electrode 125 is not interrupted. . Thus, the circuit board 10 can be reliably connected to the ground.

  3 (a) and 3 (b) show the configuration in the vicinity of the screw hole 115, but also in the screw holes 111 to 114 and 116, similarly from the region R21 by the projections 131 to 134 and 136. It is suppressed that the overflowing moisture-proof agent 12 reaches the electrodes 121 to 124, 126 and flows into the screw holes 111 to 114, 116 over the electrodes 121 to 124, 126. Also for the screw holes 111 to 114 and 116, the screw 30 is fitted to the screw holes 111 to 114 and 116 in the same manner as in FIG. 4 and the circuit board 10 is screwed to the support frame 20. Also in this case, as in the case of FIG. 4, the moisture proofing agent 12 can be prevented from being sandwiched between the screws 30 and the electrodes 121 to 124 and 126, and the circuit board 10 can be reliably connected to the ground.

<Effect of the embodiment>
According to the above embodiment, the following effects can be achieved.

  Even when the amount of the moisture proofing agent 12 applied is large, the excess moisture proofing agent 12 protruding from the region R21 protrudes because the protrusions 131 to 136 act as a barrier and can be stopped by the protrusions 131 to 136. The moistureproof agent 12 does not flow into the screw holes 111 to 116. Therefore, the moisture proofing agent 12 can be prevented from flowing into the screw holes 111 to 116, and the moisture proofing agent 12 can be prevented from adhering to the screw 30 and the screw 30 becoming defective.

  Further, as shown in FIG. 1, since the protrusions 131 to 136 are formed so as to surround the screw holes 111 to 116, respectively, the moistureproof agent 12 is in the screw holes 111 to 116 from which direction on the substrate 11. Also, the moistureproof agent 12 can be prevented from flowing into the screw holes 111 to 116.

  Further, as shown in FIG. 1, since the protrusions 131 to 136 are continuously formed without interruption, the moisture proofing agent 12 protrudes from the gap between the protrusions 131 to 136 to the screw holes 111 to 116. It can prevent it from flowing in. Therefore, the moisture proofing agent 12 can be more reliably prevented from flowing into the screw holes 111 to 116.

  Furthermore, as shown in FIG. 1, since the protrusions 131 to 136 are provided between the region R 21 to which the moisture proofing agent 12 is applied and the electrodes 121 to 126, the moisture proofing agent 12 is formed on the electrodes 121 to 126. It can prevent that it hangs. Therefore, the circuit board 10 can be reliably connected to the ground via the electrodes 121 to 126.

<Modification example>
As mentioned above, although embodiment of this invention was described, this invention is not restrict | limited at all to the said embodiment.

  For example, in the above embodiment, one protrusion 131 to 136 is provided on the outside of each of the screw holes 111 to 116, but even if a plurality of protrusions 131 to 136 are provided on the outside of the screw holes 111 to 116, respectively. Good. For example, as shown to Fig.5 (a), two protrusion 135a, 135b may be provided in the outer side of the screw hole 115. As shown in FIG. Also in this case, the protrusions 135a and 135b are provided between the screw holes 115 and the region R21 to which the moistureproof agent 12 is applied.

  Moreover, in the said embodiment, although the protrusion 131-136 was the shape bent at about 90 degree in planar view, the shape of the protrusion 131-136 is not restricted to this. For example, as shown in FIG. 5B, the protrusion 135 may have an arc shape.

  Moreover, in the said embodiment, although the protrusion 131-136 was continuously provided without interrupting, the protrusions 131-136 may be discontinuous. For example, as shown in FIG. 5C, three discontinuous projections 135c to 135e may be provided between the screw hole 115 and the region R21 to which the moistureproof agent 12 is applied. However, in this case, since a gap (a region flush with the surface of the substrate 11) is generated between the protrusion 135d and the protrusions 135c and 135e, the moistureproof agent 12 protruding from the region R21 passes through the gap There is a potential for holes 115. Therefore, in order to prevent the moisture-proof agent 12 from flowing into the screw holes 115 more reliably, it is preferable that the protrusions 131 to 136 be continuously provided without interruption as in the above embodiment.

  Moreover, in the said embodiment, although the protrusion 131-136 was provided so that the screw holes 111-116 might be enclosed, a protrusion does not necessarily need to enclose a screw hole. For example, as shown in FIG. 5D, the protrusion may not be formed in the direction in which the region to which the moistureproof agent 12 is applied does not exist.

  Moreover, in the said embodiment, as shown to FIG. 3 (a), (b), although the cross-sectional shape of the protrusion 131-136 was a rectangle, the cross-sectional shape of the protrusion 131-136 is not necessarily a rectangle. It may be another shape such as an inverted U shape or an inverted V shape. In addition, the heights of the protrusions 131 to 136 may not be constant, and the height may be different for each protrusion. Also, the height of the protrusions may be changed within one protrusion. The width of the projection can also be changed variously.

  Moreover, in the said embodiment, although the protrusion 131-136 was integrally formed beforehand to the board | substrate 11, the formation method of the protrusion 131-136 is not restricted to this. For example, as shown in FIGS. 6A and 6B, the protrusions 131 to 136 may be formed by attaching a member to the surface of the substrate 11.

  In this case, the protrusions 131 to 136 may be formed of ink for printing on the substrate 11. Generally, a symbol or the like for identifying a component to be mounted is printed on the surface of the substrate 11. This printing is performed, for example, by silk printing. When the protrusions 131 to 136 are formed by printing together with printing, ink is simultaneously attached to the positions of the protrusions 131 to 136 in the printing process, and the protrusions 131 to 136 are formed by the swelling of the attached ink. Also in this case, the ink is attached to the surface of the substrate 11 by printing so that the height of the protrusions 131 to 136 is about several tens of μm, as in the above embodiment.

  According to this modification, since the protrusions 131 to 136 can be formed in the printing process, the protrusions 131 to 136 may not be integrally formed on the substrate 11 in advance. Therefore, the configuration of the substrate 11 can be simplified, and the cost of the circuit board 10 can be reduced.

  Moreover, in the said embodiment, although the electrodes 121-126 were provided in the circumference | surroundings of the screw holes 111-116, respectively, the electrode does not need to be provided in the circumference | surroundings of a screw hole. Also in this case, as in the above embodiment, by providing a protrusion between the screw hole and the region R21 to which the moisture proofing agent 12 is applied, the flow of the moisture proofing agent 12 into the screw hole can be suppressed, and the occurrence of a screw defect is caused. It can prevent.

  Furthermore, the shape of the circuit board 10, the mounting area of the electronic component, the application area of the moistureproof agent 12, and the position and number of the screw holes are not limited to those described in the above embodiment, and various modifications are possible. is there. Further, the projections need not necessarily be provided for all the screw holes, and for example, the projections may be omitted for the screw holes greatly separated from the area to which the moistureproof agent 12 is applied. Furthermore, the present invention is applicable not only to circuit boards for vehicles but also to other circuit boards to which a moistureproofing agent is applied.

  In addition to the above, the embodiment of the present invention can be variously modified as appropriate within the scope of the technical idea shown in the claims.

DESCRIPTION OF SYMBOLS 10 Circuit board 11 Board | substrate 12 Moisture-proof agent 111-116 Screw hole 121-126 Electrode 131-136, 135a-135e A protrusion

Claims (5)

A substrate on which electronic components are mounted;
A screw hole provided in the substrate to install the substrate;
And a projection provided between the region to which a moisture-proof agent is applied and the screw hole for preventing the moisture-proof agent from flowing into the screw hole.
A circuit board characterized by The protrusion is formed to surround the screw hole.
The circuit board according to claim 1, characterized in that: The projection is continuously formed without interruption.
The circuit board according to claim 1 or 2, characterized in that: An electrode for ground is provided around the screw hole,
The protrusion is provided between an area to which the moisture-proof agent is applied and the electrode.
The circuit board according to any one of claims 1 to 3, characterized in that: The projection is formed of an ink for printing on the substrate.
The circuit board according to any one of claims 1 to 4, characterized in that:

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