JP2018010884A - Circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board which has a wiring board less likely to cause size increase and achieves good radiation properties of an electric component associated with heat generation.SOLUTION: A circuit board 20 comprises: a first surface mounting electric component 26 associated with heat generation; a second surface mounting electric component 27 not associated with heat generation; and a wiring board 21 which has a first surface where the first electric component 26 and the second electric component 27 are mounted and a second surface opposite to the first surface. The circuit board 20 further comprises: a first wiring pattern 21g to which the second electric component 27 is fastened by solder S3 and the first electric component 26 is electrically connected; a third surface mounting electric component 28 which is associated with heat generation and electrically connected with the second surface of the wiring board 21; and second wiring patterns 21j, 21k to which the third electric component 28 is electrically connected and which are partially opposed to at least part of the first wiring patterns 21g, 21h to which the second electric component 27 is fastened.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a circuit board in which electrical components are mounted on a wiring board.

  Conventionally, various surface mount type electric components mounted on a wiring board have been proposed, and for example, disclosed in Patent Document 1 and Patent Document 2. The surface mount type electrical component is electrically connected to a wiring pattern made of a copper foil formed on a substrate of the wiring board by solder. The circuit board disclosed in Patent Document 2 is provided with a heat radiating portion in the wiring pattern, and the heat generated by the electrical components mounted on the wiring board is dissipated by the heat radiating portion.

JP 2006-127974 A JP 2014-17402 A

The circuit board disclosed in Patent Document 2 provides good heat dissipation by providing a heat dissipation portion in the wiring pattern, but the heat dissipation portion occupies a mounting area for mounting electrical components. There has been a problem that the number of electrical components that can be mounted on the wiring board is reduced, or the size of the wiring board is increased.
The present invention has been made in view of this problem, and provides a circuit board in which there is little risk of an increase in the size of a wiring board and heat dissipation of electrical components that generate heat is good.

  The present invention includes a surface mount type first electrical component 26 that generates heat, a surface mount type second electrical component 27 that does not generate heat, the first electrical component 26, and the second electrical component 27. A circuit board 20 having a first surface on which the second electrical component 27 is mounted and a second surface opposite to the first surface, wherein the second electrical component 27 is solder S3. The first electrical component 26 is electrically connected to the first wiring pattern 21g fixed in (1).

  Further, according to the present invention, a surface mount type third electrical component 28 with heat generation is electrically connected to the second surface of the wiring board 21.

  Further, according to the present invention, the second wiring in which the third electrical component 28 is electrically connected to at least a part of the first wiring patterns 21g and 21h to which the second electrical component 27 is fixed. At least some of the patterns 21j and 21k are opposed to each other.

  In the present invention, the second electrical component 27 is a surface mount type connector.

  Since the heat generated by the first electrical component is dissipated in the first wiring pattern to which the second electrical component is fixed, the wiring board is less likely to be large and the electrical component that generates heat Good heat dissipation.

Sectional drawing which shows embodiment of this invention. The front view which shows embodiment same as the above. Sectional drawing which shows the principal part which shows embodiment same as the above.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The vehicle display device includes a pointer 10, a circuit board 20, a case body 30, a display plate 40, a liquid crystal display 50, and a rear cover 60.

  The pointer 10 includes an instruction portion 11 made of a translucent resin, a pointer cap 12 made of an opaque resin, a boss portion 13 into which the rotating shaft 22a is press-fitted, and a pointer seat 14 on which the indication portion 11 is placed. The indicator unit 41 is instructed by the instruction unit 11. The boss portion 13 and the pointer seat 14 of the pointer 10 are integrally formed of white resin. The illumination light emitted from the light emitting element 25 and having passed through the through hole 20 c is reflected by the boss portion 13 and the pointer seat 14 in the vicinity of the through hole 40 c of the display panel 40.

  The circuit board 20 includes a wiring board 21, a pointer driving unit 22, light emitting elements 24 and 25, a linear regulator 26, a connector 27, and a power transistor 28, and is disposed on the rear side of the display board 40. ing. The light emitting elements 24 and 25 and the power transistor 28 are mounted on the front surface of the wiring board 21. The pointer drive unit 22, the linear regulator 26, and the connector 27 are mounted on the rear surface of the wiring board 21. The light-emitting elements 24 and 25, the linear regulator 26, the connector 27, and the power transistor 28 are surface mount type electric components. A wiring cord 90 is connected to the connector 27 of the circuit board 20.

  The pointer driving unit 22 includes a movable magnet type driving device, a stepping motor, and the like. The rotation shaft 22 a of the pointer driving unit 22 is inserted into a through hole 21 p formed in the wiring board 21, and the pointer 10 is attached to the rotation shaft 22 a of the pointer driving unit 22. The boss portion 13 of the pointer 10 is inserted into a through hole 40 c formed in the display board 40. The through hole 40c of the display board 40 is formed at a location corresponding to the rotating shaft 22a of the pointer driving unit 22 and has a circular shape when viewed from the front.

  Each of the light emitting elements 24 and 25 includes one or more light emitting diodes. The light emitting element 24 illuminates and transmits the display panel 40. The light emitting element 25 shines the instruction unit 11 of the pointer 10. The light emitting elements 24 and 25 are turned on / off according to an illumination switch or the like operated by a vehicle driver.

  The case body 30 is made of a white synthetic resin (for example, polypropylene), and the circuit board 20 is fixed to the case body 30. The case body 30 has a vertical part 31, an inclined part 32, a parallel part 33, an inclined part 34, and a vertical part 35. The vertical portion 31 of the case body 30 has a cylindrical shape, the front end is in contact with the rear surface of the display panel 40, and the rear end is in contact with the front surface of the circuit board 20. The vertical portion 31 of the case body 30 is a light shielding wall that prevents the illumination light emitted from the light emitting element 24 and the illumination light emitted from the light emitting element 25 from being mixed.

  The inclined portion 32 of the case body 30 has a shape that spreads in an inverted conical shape from the outer peripheral surface of the vertical portion 31. The inclined portion 32 of the case body 30 reflects the illumination light emitted from the light emitting element 24 toward the parallel portion 33 and the inclined portion 34. The parallel part 33 of the case body 30 has a flat plate shape parallel to the display panel 40. The inclined portion 34 of the case body 30 has an inverted conical shape and is continuous with the outer peripheral end of the parallel portion 33. The inclined portion 34 of the case body 30 reflects the illumination light emitted from the light emitting element 24 toward the display plate 40. The vertical portion 35 of the case body 30 has a cylindrical shape, and the rear end is in contact with the front surface of the circuit board 20. The vertical portion 35 of the case body 30 is continuous with the outer peripheral end of the inclined portion 34. The vertical portion 35 of the case body 30 has a front end in contact with the rear surface of the display board 40 and a rear end in contact with the front surface of the circuit board 20.

  The display board 40 is obtained by forming various printing layers on a base material made of a light-transmitting resin such as polycarbonate, and has an indicator portion 41 arranged in an arc shape with a through hole 40c as a center. The indicator portion 41 of the display panel 40 is transmitted and illuminated by the illumination light emitted from the light emitting element 24.

  The liquid crystal display 50 is disposed between two pointer-type meters (speedometer and tachometer). The liquid crystal display 50 includes a liquid crystal display panel 51, a connection member 52, an optical sheet 53, and a case body 54. The liquid crystal display panel 51 has polarizing plates attached to both front and rear surfaces of a liquid crystal cell in which liquid crystal is sealed in a pair of glass substrates on which transparent electrodes are formed. The liquid crystal display panel 51 displays vehicle information such as the accumulated travel distance.

  The connection member 52 is made of a metal pin, and one end is electrically connected to the liquid crystal display panel 51 and the other end is electrically connected to the circuit board 20 by solder. The optical sheet 53 is formed by appropriately combining a light diffusion film, a brightness enhancement film, and the like, and is disposed on the rear surface of the liquid crystal display panel 51. The case body 54 is made of a white resin. The liquid crystal display panel 51 is transmitted and illuminated by a light emitting element (not shown) mounted on the front surface of the circuit board 20.

  Next, the circuit board 20 will be described in detail with reference to FIG. The wiring board 21 is obtained by forming wiring patterns 21f, 21g, 21h, 21j, 21k and a resist 21b made of copper foil on a flat substrate 21a made of glass epoxy resin. The wiring patterns 21f, 21g, and 21h of the wiring board 21 are formed on the rear surface of the base material 21a, and the wiring patterns 21j and 21k are formed on the front surface of the base material 21a.

  The linear regulator 26 is connected to the wiring patterns 21f and 21g by solders S1 and S2. The connector 27 is fixed to the wiring patterns 21g and 21h by solders S3 and S4. The solders S1 and S2 are for electrically connecting the terminals of the linear regulator 26 to the wiring patterns 21f and 21g, whereas the solders S3 and S4 are for fixing the connector 27 to the wiring board 21. The 27 terminals are not electrically connected.

  Since the linear regulator 26 is connected to the wiring pattern 21g by the solder S2 and the connector 27 is fixed by the solder S3, the heat generated by the linear regulator 26 is dissipated by the wiring pattern 21g and the solder S3. Is done.

  The power transistor 28 is electrically connected to the wiring patterns 21j and 21k by solders S5 and S6. The wiring pattern 21j formed on the front surface of the substrate 21a of the wiring board 21 is opposed to the wiring pattern 21h formed on the rear surface of the substrate 21a. Solders S5 and S6 are for electrically connecting the terminals of the power transistor 28 to the wiring patterns 21j and 21k.

  Since the wiring pattern 21j to which the power transistor 28 is connected is opposed to the wiring pattern 21h, the heat generated by the power transistor 28 is easily transferred to the wiring pattern 21h and the solder S4 via the base material 21a. And dissipated by the solder S4.

  In the present embodiment, a surface-mount linear regulator (first electrical component) 26 that generates heat, a surface-mount connector (second electrical component) 27 that does not generate heat, and the linear regulator (first electrical component) Wiring having a rear surface (first surface) on which the electrical component) 26 and the connector (second electrical component) 27 are mounted and a front surface (second surface) opposite to the rear surface (first surface). A circuit board 20 having a board 21 and a wiring pattern (first wiring pattern) 21g to which the connector (second electrical component) 27 is fixed by solder S3. The electrical component) 26 is electrically connected, and the heat generated by the linear regulator (first electrical component) 26 is the wiring pattern (first electrical component) 27 to which the connector (second electrical component) 27 is fixed. Wiring pattern) 2 Since dissipated by g, the linear regulator heat dissipation of the (first electrical part) 26 is good. In addition, since the wiring pattern (first wiring pattern) 21g is a part for fixing the connector (second electrical component) 27, the wiring pattern dedicated to heat radiation does not occupy the wiring board 21. There is little possibility that 21 will become large.

  In addition, this invention is not limited to this embodiment, A various deformation | transformation is possible. For example, the electrical component that generates heat is not limited to a linear regulator or a power transistor, and may be a microcomputer.

20 Circuit board 21 Wiring board 21g Wiring pattern (first wiring pattern)
21h Wiring pattern (first wiring pattern)
21j wiring pattern (second wiring pattern)
21k wiring pattern (second wiring pattern)
26 Linear regulator (first electrical component)
27 Connector (second electrical component)
28 Power transistor (third electrical component)
S1 solder S2 solder S3 solder S4 solder S5 solder S6 solder

Claims (4)

A first electric component of a surface mount type that generates heat; a second electric component of a surface mount type that does not generate heat; a first surface on which the first electric component and the second electric component are mounted; A circuit board having a second surface that is opposite to the first surface;
A circuit board, wherein the first electrical component is electrically connected to a first wiring pattern to which the second electrical component is fixed by solder.   The circuit board according to claim 1, wherein a third electric component of a surface mount type that generates heat is electrically connected to the second surface of the wiring board.   At least a portion of the second wiring pattern to which the third electrical component is electrically connected is opposed to at least a portion of the first wiring pattern to which the second electrical component is fixed. The circuit board according to claim 2.   The circuit board according to claim 1, wherein the second electrical component is a surface mount type connector.

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