JP2011040507A - Circuit device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit device with a new heat dissipation structure, capable of effectively dissipating heat generated in an electric component mounted on a printed circuit board. <P>SOLUTION: A through-hole 28 is formed in a mounting area 26 for a heating component 14 in the printed circuit board 12, and a heat dissipation rod 36 formed by cutting a metal wire rod is inserted through and fixed to the through-hole 28, with one end 38 of the rod 36 being in contact with the heating component 14 and the other end 42 being protruded out of the printed circuit board 12. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a circuit device mounted on an electrical junction box for automobiles, and more particularly to a circuit device in which a heat generating component is mounted on a printed circuit board.

  Conventionally, a circuit device using a printed circuit board has been used as a component of various electric circuits. A specific circuit pattern is formed on the printed circuit board, and electrical components such as a relay, a capacitor, a resistor, a transistor, and an LSI are mounted on the circuit pattern to form an electric circuit.

  By the way, electrical components mounted on a printed circuit board include heat generating components such as relays, power transistors, and LSIs, and the heat generation may damage the electrical components and the printed circuit board itself. Therefore, as described in Japanese Patent Application Laid-Open No. 2005-183559 (Patent Document 1), a through hole for heat dissipation in which a mounting region of a heat generating electrical component on a printed board is filled with a heat conductive paste or the like It has been proposed to form via holes.

  However, there are cases where it is difficult to obtain a sufficient heat dissipation effect by simply forming through holes or via holes for heat dissipation.

  In order to improve the heat dissipation effect, Japanese Patent Application Laid-Open No. 2006-1000048 (Patent Document 2) proposes to spread a heat dissipation conductor between the core layers and the back surface of the printed circuit board. It has been proposed to form a heat dissipation pattern that spreads out of the mounting area of the electrical components on both the front and back sides of the printed circuit board. However, because other circuit patterns are formed on the core layer and front and back surfaces of the printed circuit board and electrical components are mounted, it may be difficult to form a heat dissipation conductor or heat dissipation pattern with a sufficient area, It was not always effective.

JP 2005-183559 A JP 2006-1000048 A

  The present invention has been made in the background of the above-mentioned circumstances, and its solution is to provide a novel heat dissipation structure that can effectively dissipate heat generated in electrical components mounted on a printed circuit board. An object of the present invention is to provide a circuit device provided.

  According to a first aspect of the present invention, in a circuit device in which a heat generating component is mounted on a printed circuit board, a through hole is formed in the mounting region of the heat generating component on the printed circuit board, and the metal wire is cut. The heat dissipating rod is inserted and fixed in the through hole, and one end of the heat dissipating rod is in contact with the heat generating component, while the other end of the heat dissipating rod is outward from the printed circuit board. It is characterized by protruding.

  According to the present invention, the heat of the heat generating component can be dissipated from the back side opposite to the heat generating component on the printed board through the heat dissipation rod. In particular, by setting the other end portion of the heat dissipating rod to protrude from the back surface of the printed circuit board, the heat dissipating area was secured three-dimensionally in the thickness direction instead of the surface direction of the printed circuit board. As a result, a heat dissipation structure in which the heat dissipation area stays in the printed circuit board, such as forming a through hole filled with conductive paste, or a heat dissipation area that increases the area of the heat dissipation pattern remains on the surface of the printed circuit board. Compared to the heat dissipation structure, a more excellent heat dissipation effect can be obtained. In addition, the heat of the heat generating member can be efficiently transmitted to the back side of the printed circuit board by utilizing the excellent heat transfer performance of the metal heat dissipation rod.

  In particular, it is often difficult for a printed circuit board to secure a space on a mounting surface due to a wiring pattern, a mounting component, or the like. However, according to the present invention, the heat dissipating rod is projected in the thickness direction of the printed circuit board in the mounting region of the mounting component to secure the heat dissipating area, with almost no loss of the routing area and the member disposing space. Heat dissipation efficiency can be improved.

  The printed board in the present invention may be a single-sided printed wiring board or a double-sided printed wiring board using one printed board, or a multilayer printed wiring board in which a plurality of printed boards are stacked. In addition, one end of the heat dissipation rod may be in direct contact with the heat generating component, for example, a connecting member or an adhesive for connecting the heat generating component and the heat dissipation rod, or formed on the surface of the printed circuit board. It may be indirectly in contact with the heat generating member through a heat conduction part such as a land or a heat dissipation circuit.

  According to a second aspect of the present invention, in the one described in the first aspect, a land is formed in at least one opening portion of the through hole, and the heat dissipation rod is fixed to the land. Is. If it does in this way, a rod for heat dissipation can be stably fixed to a printed circuit board using a land. As a result, it is possible to stably maintain the contact state of the heat dissipating rod to the heat generating component mounted on the printed circuit board, and to improve the heat transfer efficiency and its reliability.

  According to a third aspect of the present invention, in the first or second aspect, a gap is formed between facing surfaces of the printed circuit board and the heat-generating component, and the heat dissipation rod is the printed board. It protrudes into the gap from the substrate, and the heat-radiating rod is in contact with the heat-generating component at the protruding portion into the gap.

  According to this aspect, since a gap is formed between the heat generating component and the printed board, heat transfer from the heat generating component to the printed circuit board can be further reduced. At the same time, since the heat dissipating rod is disposed in the gap, the heat staying in the gap can be dissipated from the back side of the printed circuit board through the heat dissipating rod.

  According to a fourth aspect of the present invention, there is provided the printed circuit board according to any one of the first to third aspects, wherein the printed circuit board is formed in a space between wiring patterns and is outward from a mounting region of the heat generating component. A heat dissipation circuit extending to the heat dissipation circuit is formed, and the heat dissipation rod is connected to the heat dissipation circuit.

  In this way, the empty space between the wiring patterns can be skillfully used to secure a larger heat dissipation area without causing an increase in the size of the printed board. In addition, the heat dissipation circuit in this aspect can be formed not only on the surface of the printed board on which the heat generating component is mounted, but also on the back surface of the printed board and in the case of a multilayer printed board.

  According to the present invention, in the mounting area of the heat generating component on the printed circuit board, one end portion of the metal heat dissipation rod is brought into contact with the heat generating component, and the other end portion projects to the opposite side of the heat generating component on the printed circuit board. I let you. As a result, it is possible to form a heat dissipation area in three dimensions in the thickness direction of the printed circuit board, and to secure an effective heat dissipation area without almost reducing the wiring pattern and electric component placement area on the printed circuit board. Excellent heat dissipation efficiency can be obtained.

FIG. 3 is a cross-sectional explanatory view of the circuit device as the first embodiment of the present invention, and is a cross-sectional explanatory view corresponding to the II cross section in FIG. 2. Explanatory drawing which shows the surface of the printed circuit board which comprises the circuit apparatus shown in FIG. Sectional explanatory drawing of the circuit apparatus as 2nd embodiment of this invention. Sectional explanatory drawing of the circuit apparatus as 3rd embodiment of this invention. Cross-sectional explanatory drawing of the circuit apparatus of the different aspect of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, FIG. 1 shows a circuit device 10 as a first embodiment of the present invention. The circuit device 10 has a structure in which a relay 14 as a heat generating member is mounted on a printed board 12 made of an insulating plate.

  FIG. 2 shows the surface 16 of the printed circuit board 12. The circuit device 10 is a double-sided printed wiring board, and printed wirings 20a and 20b as wiring patterns made of copper foil or the like are formed on the front surface 16 and the back surface 18 of the printed circuit board 12. The printed wirings 20a and 20b formed on the front surface 16 and the back surface 18 penetrate the printed circuit board 12 in the thickness direction, and have through holes 22 and via holes (illustrated) whose inner peripheral wall is covered with a conductor such as copper foil. Is omitted). In the present specification, the through-hole means that through which the terminal of the electric component is inserted, and the via hole means that through which the terminal of the electric component is not inserted.

  Further, on the front surface 16 and the back surface 18, heat radiation circuits 24a and 24b are formed between the printed wirings 20a and 20b. The heat dissipation circuits 24a and 24b are preferably formed from members having high thermal conductivity, and are preferably formed from copper foil or the like by the same formation method as the printed wirings 20a and 20b. The heat dissipation circuits 24 a and 24 b extend on the front surface 16 and the back surface 18 of the printed circuit board 12 from the mounting region 26 where the relay 14 is overlapped to the outside of the mounting region 26. The sizes of the heat dissipation circuits 24a and 24b are not particularly limited, and are appropriately set in consideration of the heat generation amount of a heat generating component connected through a heat dissipation rod 36 described later, the required heat dissipation capacity, and the like. However, as shown in FIG. 2, it is preferable that the wirings 20a and 20b are provided as widely as possible.

  A plurality of via holes 28 as through holes penetrating the printed circuit board 12 in the thickness direction are formed in regions where the heat dissipation circuits 24 a and 24 b are formed. The via holes 28 are formed in the front surface 16 and the back surface 18. The heat dissipation circuits 24a and 24b are thermally connected. In the present specification, being thermally connected means that the heat of one member can be transmitted to the other member. The via hole 28 is formed on at least the mounting region 26 on the heat radiation circuits 24a and 24b, and more preferably includes a region outside the mounting region 26 and covers the entire heat radiation circuits 24a and 24b as much as possible. Many are formed. Note that the cross-sectional shape of the via hole 28 can be appropriately set in consideration of the cross-sectional shape in the axial direction of the heat dissipating rod 36, which will be described later, and in this embodiment, a circular cross section corresponding to the heat dissipating rod 36. It is made into a shape.

  In the printed circuit board 12 having such a structure, the terminal 30 of the relay 14 is inserted into the through hole 22 from the surface 16. Lands 32 are formed in the opening portions of the front surface 16 and the back surface 18 of the through hole 22, and the terminals 30 protruding from the back surface 18 are fixed to the lands 32 formed on the back surface 18 side with solder 34. Is done. Accordingly, the relay 14 is electrically connected to the printed wirings 20a and 20b and mounted on the printed board 12. Note that the relay 14 of this embodiment is attached to the surface 16 of the printed circuit board 12 with almost no gap. Further, in the mounted state of the relay 14, the heat radiation circuits 24 a and 24 b extend outward from the relay 14 on the front surface 16 and the back surface 18.

  Further, a heat radiating rod 36 is inserted and fixed in a via hole 28 formed in the heat radiating circuits 24 a and 24 b in the mounting region 26. The heat dissipation rod 36 is formed by cutting a metal wire such as copper or iron into a predetermined length. Further, the cross-sectional shape in the direction perpendicular to the axis of the heat dissipating rod 36 is not limited in any way. For example, in the present embodiment, the cross-sectional shape is a constant circular cross-sectional shape over the entire length. Then, one end portion 38 of the heat dissipation rod 36 protrudes from the surface 16 of the printed circuit board 12 and contacts the bottom surface 40 facing the surface 16 in the relay 14. At the same time, the other end 42 of the heat dissipating rod 36 protrudes from the back surface 18 of the printed circuit board 12, and the protruding portion from the back surface 18 is fixed to the heat dissipating circuit 24 b formed on the back surface 18 with solder 34. ing. Thereby, the heat dissipating rod 36 is inserted and fixed to the via hole 28 with one end 38 contacting the relay 14 and the other end 42 protruding from the back surface 18 of the printed circuit board 12. The heat dissipating rod 36 is thermally connected to the heat dissipating circuits 24 a and 24 b through the via hole 28.

  The heat radiation rod 36 is inserted into and fixed to the via hole 28, for example, after the terminal 30 of the relay 14 is inserted into the through hole 22 and protrudes from the rear surface 18, the heat radiation rod 36 is inserted into the via hole from the rear surface 18 side. The terminal 30 and the heat-dissipating rod 36 are fixed by soldering from the back surface 18 side in a state where the one end 38 is inserted into the terminal 28 and in contact with the bottom surface 40 of the relay 14. Alternatively, for example, one end portion 38 of the heat dissipating rod 36 is fixed in contact with the bottom surface 40 of the relay 14 in advance by bonding or the like, and the via hole is inserted into the through hole 22 of the terminal 30 from the surface 16 side. It may be inserted into 28 and fixed by soldering from the back surface 18 side. Further, the heat radiation rod 36 may be fixed to the via hole 28 by, for example, adhesion or press fitting.

  According to the circuit device 10 having such a structure, heat generated in the relay 14 is transmitted to the heat dissipation rod 36 that is in contact with the relay 14. The heat transmitted to the heat radiating rod 36 is dissipated into the atmosphere from the other end 42 protruding to the back surface 18 side of the printed circuit board 12. As a result, overheating of the relay 14 can be suppressed, and the risk of damage to the relay 14 and other electrical components and deformation of the printed circuit board 12 due to this can be reduced. In particular, the heat radiation rod 36 is formed of a metal wire having a relatively high thermal conductivity, so that the heat of the relay 14 can be effectively absorbed. At the same time, the other end 42 side of the heat dissipating rod 36 is projected from the back surface 18 of the printed circuit board 12 and exposed to the atmosphere over the entire circumference, so that an excellent heat dissipating effect can be obtained.

  Further, the heat dissipating rod 36 is disposed in the mounting region 26 where the relay 14 is mounted, and is disposed so as to be inserted and fixed in the via hole 28 and extend in the thickness direction of the printed circuit board 12. A heat dissipation structure can be formed with almost no loss of the wiring space on the printed circuit board 12.

  Further, since the heat dissipating rod 36 is thermally connected to the heat dissipating circuits 24a and 24b, the heat of the heat dissipating rod 36 is more efficiently dissipated using the wide width of the heat dissipating circuits 24a and 24b. I can do it. In addition, since the heat radiation circuits 24a and 24b are formed in a wide range as much as possible, it is possible to equalize the temperature of the entire printed circuit board 12. Since the heat radiation circuits 24a and 24b are formed by using the non-formed portions of the printed wirings 20a and 20b, it is possible to secure a large heat radiation area without causing an increase in the size of the printed circuit board 12. ing.

  Next, FIG. 3 shows a circuit device 50 as a second embodiment of the present invention. In the following description, members and parts that are substantially the same as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment in the drawings, and the description thereof is omitted. To do.

  The relay 14 in the present embodiment is supported on the printed circuit board 12 via a block-like stand 52 for the purpose of reducing the thermal effect in the soldering process. As a result, a gap 54 is formed between the bottom surface 40 of the relay 14 and the surface 16 of the printed circuit board 12. One end portion 38 of the heat dissipation rod 36 protrudes from the surface 16 into the gap 54 and is in contact with the bottom surface 40. Note that the stand 52 may be a protrusion formed integrally with the relay 14.

  Further, the printed circuit board 12 in this embodiment is not formed with the heat dissipation circuits 24a and 24b in the first embodiment, and lands 56 are formed in the openings to the front surface 16 and the rear surface 18 of the via hole 28. Each is formed. The heat dissipating rod 36 is fixed to the land 56 on the back surface 18 side with the solder 34, so that the heat dissipating rod 36 is fixed in a state of being inserted into the via hole 28.

  According to the present embodiment, since the contact area between the relay 14 and the printed circuit board 12 can be reduced, the thermal influence from the relay 14 to the printed circuit board 12 can be further reduced. Since the heat dissipating rod 36 is disposed in the gap 54, the heat in the gap 54 can be dissipated from the back surface 18 side through the heat dissipating rod 36 to prevent or prevent the heat from staying in the gap 54. It can be reduced. As is apparent from the present embodiment, the heat dissipation circuit is not necessarily required in the present invention. For example, one or both of the heat dissipation circuits 24a and 24b in the first embodiment are added to the printed circuit board 12 in the present embodiment. Of course, it is also possible to form.

  Next, FIG. 4 shows a circuit device 60 as a third embodiment of the present invention. The circuit device 60 includes a multilayer printed circuit board 12 configured by stacking a plurality of insulating plates 13a to 13c and conductor patterns. And the printed wiring 20a is formed in the surface 16 of the insulating board 13a which comprises one outer surface of the multilayer printed circuit board 12, while the printed wiring 20b is formed in the back surface 18 of the insulating board 13c which comprises the other outer surface. . Further, printed wirings 20c and 20d are formed between the overlapping surfaces of the insulating plates 13a to 13c, respectively. These printed wirings 20a to 20d are appropriately electrically connected through through holes 22 or via holes (not shown).

  A heat dissipation circuit 24a is formed on the front surface 16 of the insulating plate 13a, while a heat dissipation circuit 24b is formed on the back surface 18 of the insulating plate 13c. Further, heat radiation circuits 24c and 24d are respectively formed between the printed wirings 20c and 20d between the overlapping surfaces of the insulating plates 13a to 13c. And these heat dissipation circuits 24a-24d are thermally connected by the via hole 28 which penetrates the insulating plates 13a-13c on the straight line in the thickness direction.

  The terminal 30 of the relay 14 is inserted into the through hole 22 and fixed with the solder 34, and the heat dissipation rod 36 is inserted into the via hole 28, and one end 38 is brought into contact with the bottom surface 40 of the relay 14. At the same time, the other end portion 42 is fixed from the back surface 18 with the solder 34.

  As is apparent from this embodiment, the present invention can of course be applied to a multilayer printed wiring board. In particular, in the present embodiment, by forming the heat radiation circuits 24c and 24d also between the overlapping surfaces of the insulating plates 13a to 13c to ensure a wider heat radiation area, a more excellent heat radiation effect is exhibited. ing. However, a heat dissipation circuit may be formed in a part between a plurality of overlapping surfaces of the laminated insulating plates, or only the front and back surfaces of the laminated body (the surface 16 of the insulating plate 13a and the insulating plate 13c in this embodiment). A heat dissipation circuit may be formed on the back surface 18 only).

  As mentioned above, although embodiment of this invention was explained in full detail, this invention is not limited by the specific description. For example, the cross-sectional shape of the heat-dissipating rod is not limited in any way, and can be arbitrarily selected such as a rectangular shape such as a rectangle or a rectangle, a circular shape such as a circle or an ellipse, an arbitrary polygonal shape, or a combination of this and a curved shape. It can be set. Furthermore, the cross-sectional shape of the heat dissipating rod does not need to be constant over the entire length. For example, the tip portion can be tapered to facilitate insertion into the through hole. It is also possible to give the appropriate shape corresponding to the allowable space by appropriately deforming the protruding part from the back side of the printed board of the heat dissipation rod by bending, bending, pressing, etc. It is also possible to adjust the surface area and heat dissipation performance (air fluidity, etc.). For example, like the circuit device 70 as a different aspect of the present invention shown in FIG. 5, the end portion 42 protruding from the back surface 18 in the heat dissipating rod 36 has a flat shape to increase its surface area, thereby improving the heat dissipating efficiency. It is also possible to obtain it.

  Moreover, you may deform | transform the edge part by the side of the heat-emitting component of the heat radiating rod by various processes. For example, the heat-transfer performance is further improved by forming the edge of the heat-dissipating rod side of the heat-dissipating rod into a flange shape that extends in the direction perpendicular to the axis by tapping or the like to increase the contact area with the heat-generating component. You can do that.

  In addition, one end of the heat-dissipating rod is not necessarily in direct contact with the heat-generating component. For example, a connecting member or adhesive for connecting the heat-generating component and the heat-dissipating rod, or the surface of the printed circuit board. It may be indirectly in contact with the heat generating member through the heat conduction part such as the formed land or the heat radiation circuit.

  Further, the heat dissipating rod need not be provided in all of the through holes located in the mounting area. In addition to the heat dissipating rod inserted and fixed in the through hole in the mounting area, the heat dissipating rod is inserted and fixed in the through hole formed on the heat dissipating circuit extending to the outside of the mounting area. The heat may be dissipated from the heat dissipating rod outside the mounting area.

  Also, for example, a conductive member such as solder or an insulating resin material may be filled in the gap between the via hole and the heat dissipating rod, or in the via hole where the heat dissipating rod is not inserted, to further enhance the heat dissipating effect. good. Further, the through hole into which the heat dissipation rod is inserted and fixed may be not only a via hole having through hole plating and used for interlayer connection, but also a simple through hole having no through hole plating or the like.

  Further, in the above embodiment, the circuit device in which the heat generating component in which the terminal is inserted into the through hole is illustrated, but the heat generating component is fixed to the pad formed on the printed circuit board in a mounted state. A surface-mount type or the like may be used.

10, 50, 60, 70: circuit device, 12: printed circuit board, 14: relay (heat-generating component), 20: printed wiring (wiring pattern), 22: through hole, 24a to d: heat dissipation circuit, 26: mounting area, 28: Via hole (through hole), 34: Solder, 36: Rod for heat dissipation, 38: One end, 42: The other end, 54: Gap, 56: Land

Claims (4)

In a circuit device in which a heat generating component is mounted on a printed circuit board,
A through hole is formed in a mounting region of the heat generating component on the printed circuit board, and a heat dissipation rod formed by cutting a metal wire is inserted and fixed in the through hole, and one of the heat dissipation rods A circuit device, wherein an end portion is in contact with the heat-generating component, and a second end portion of the heat dissipating rod projects outward from the printed board.   The circuit device according to claim 1, wherein a land is formed in at least one opening portion of the through hole, and the heat dissipation rod is fixed to the land.   A gap is formed between the opposing surfaces of the printed circuit board and the heat generating component, and the heat dissipation rod protrudes from the printed circuit board into the clearance, and the heat dissipation rod The circuit device according to claim 1, wherein the circuit device is in contact with the heat generating component.   The printed circuit board is formed with a heat dissipation circuit that is formed in a space between wiring patterns and extends outward from the mounting area of the heat generating component, and the heat dissipation rod is connected to the heat dissipation circuit. The circuit device according to claim 1.

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