JPH0717156Y2 - Circuit board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a circuit board for electric or electronic circuits,
In particular, the present invention relates to a heat dissipation structure of a circuit board on which heat generating elements that generate heat during operation are arranged.

[Prior Art] A conventional heat dissipation structure for dissipating heat generated from a part of heat-generating components in a circuit board formed by forming a circuit on an alumina substrate, a resin substrate, or the like is, for example, SAIKAI Sho-56- 169
The ones shown in Japanese Patent No. 573 and Japanese Utility Model Laid-Open No. 61-83098 are known.

When connecting a heat-generating electronic component to another electronic component, the former circuit board is connected by a heat-dissipating jumper wire instead of the connection by a wiring pattern formed on the circuit board. That is, the U-shaped or coil-shaped heat dissipation jumper wire is connected to the wiring pattern at the through-hole connection portion provided on the circuit board, so that the heat-dissipating electronic component is connected to another electronic component.

In the latter circuit board, wing-shaped fins having a heat dissipation pattern may be extended from near the heat-generating components of the circuit board,
Separately, fins are mounted on the circuit board to increase the area of the heat dissipation pattern.

[Problems to be solved by the invention] However, in the former circuit board, since it is necessary to intentionally connect the electronic components that can be originally connected by the wiring pattern with the heat radiation jumper wire, it is troublesome to manufacture the circuit board. have. Moreover, since the linear components such as the heat radiation jumper wires must be connected to the circuit by the through-hole connection, the surface mounting method using the chip-shaped electronic components is not generalized. The connection of the heat radiating jumper wire requires a great deal of labor compared to the mounting of other electronic components.

Further, the heat dissipation jumper wire constitutes a part of the circuit, and a current flows through it. Therefore, when the number of turns increases, a magnetic field is generated, which affects surrounding circuits. Not only that, but in a high-frequency circuit or the like, the heat radiation jumper wire is heated at a high frequency, which itself becomes a heat source. Therefore, there is a limit to increase the number of windings, and there is also a limit to the heat dissipation effect.

Even if the number of turns of the heat radiation jumper wire can be increased, the heat inlet is limited to one end side connected to the heat generating component. Therefore, the thermal resistance on the heat inlet side is large,
There is a limit to the amount of heat that can be transferred to the heat dissipation jumper wire per unit time. Then, as the distance from the one end of the heat radiating jumper wire on the heat inlet side increases, the temperature decreases, and the temperature difference with the surroundings decreases, so that the heat radiating effect decreases. Therefore, even if the number of turns of the heat radiation jumper wire is increased, the heat radiation effect cannot be expected to be improved accordingly.

Further, in the latter circuit board, the fins are extended from the circuit board to the outside thereof, which hinders downsizing of the circuit board.
In addition, when connecting the circuit board and a separate fin with solder, the complicated fin shape hinders the mounting, and simultaneous mounting with other electronic components is difficult, and more time is required for mounting. .

In view of the above-mentioned problems in the prior art, the present invention has an inexpensive and easy-to-mount heat dissipation structure for dissipating heat from a heat-generating element disposed on a circuit board, and the surrounding circuit is electrically connected. To provide a circuit board having high heat dissipation efficiency without giving a negative influence.

[Means for Solving the Problem] That is, the object of the present invention is to mount the heat-generating element 2 on the substrate 1.
In the circuit board disposed on the conductor layer formed on the main surface of the heat dissipation element, the heat dissipation conductor layer 5 is formed on the main surface of the substrate 1 in the vicinity of the location where the heat generating element 2 is disposed. This is achieved by a circuit board characterized in that a coil outer peripheral portion of a radiator 6 made of a coil-shaped metal wire having a tubular shape as a whole is fixed on the conductor layer 5.

[Operation] Since the radiator 6 is made of a coiled metal wire and has a tubular appearance as a whole, it can be handled in common with other chip-type electronic components mounted on the substrate 1. That is, at the same time as mounting other chip type electronic components on the surface of the substrate 1 using the automatic mounting apparatus, the radiator 6 is
Mounted on the heat dissipation conductor layer 5 provided on the surface of the substrate 1,
Can be fixed. Further, the radiator 6 made of the coiled metal wire can be manufactured by directly diverting the manufacturing process of the coil component used as the inductor on the circuit from the structure and the shape, and therefore, it is extremely easy. And it can be obtained at low cost.

The radiator 6 is only mounted on the heat dissipation conductor layer 5 and does not constitute an electronic circuit, so that no current flows through it. Therefore, the magnetic field is not generated and the surrounding circuits are not adversely affected. Further, the radiator 6 does not generate heat electrically, and there is no possibility that the radiator 6 itself becomes a heat source.

Further, since the radiator 6 is made of a coil-shaped metal wire, it has a large surface area and a high heat radiation amount per unit projected area can be obtained. Moreover, since the radiator 6 has its coil outer peripheral portion fixed to the heat dissipation conductor layer 5, the coil-shaped metal wire forming the radiator 6 has a number of portions corresponding to the number of turns thereof.
It is fixed to the heat dissipation conductor layer 5 at regular intervals. For this reason,
The heat transferred from the heat-generating element 2 to the heat-dissipating conductor layer 5 is further transferred from the plurality of fixing points of the radiator 6 to the respective portions of the metal wire substantially uniformly, and is radiated to the surroundings. Thereby, a high heat dissipation effect can be obtained. Moreover, since the number of fixing points with the heat dissipation conductor layer 5 can be arbitrarily selected by the number of turns of the heat radiator 6, the heat dissipation amount can be arbitrarily set according to the heat generation amount of the exothermic element 2.

[Embodiment] An embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, a so-called heat generating element 2 such as a power transistor is fixed by soldering or the like on the main surface of a substrate 1 for electric or electronic circuits such as a printed circuit board or an alumina insulating substrate. 3 of this exothermic element 2
Each of the terminals 3 of the book is electrically connected to a so-called wiring pattern 4 composed of a conductor layer formed on the main surface of the substrate 1, and forms a predetermined circuit.

According to the present invention, the main portion of the substrate 1 near the location where the heat-generating element 2 is disposed, that is, in FIG. The conductor layer 5 for attaching the radiator 6 is formed on the surface. In the embodiment shown in FIG. 1, a conductor layer for disposing the heat-generating element 2, for example, a metal conductor layer such as copper foil or Ag-Pd is provided from below the heat-generating element 2 to the terminals of the heat-generating element 2. 3 is extended to the surface of the substrate 1 on the side opposite to the protruding side, and a part thereof is used as the heat dissipation conductor layer 5.

The surface of the heat dissipation conductor layer 5 is shown in FIG.
As shown in (b) and (b), a radiator 6 formed by forming a metal wire into a coil shape having a tubular shape as a whole is fixed. That is, the radiator 6 is arranged laterally on the surface of the heat dissipation conductor layer 5, and the outer peripheral portion of the coil is fixed by the solder 7 or the like. As a result, the coil-shaped metal wire forming the radiator 6 is fixed to the heat-dissipating conductor layer 5 at a constant number of positions according to the number of turns.

The radiator 6 is formed by using a metal having a high thermal conductivity such as copper, and its surface is plated to enable soldering. Such a radiator 6 is mounted on the substrate 1 together with the chip type electronic component, and further, the substrate 1
Since it can be soldered by means such as reflow, flow, or ironing, it is easy to handle and there is no need to separately provide a step for attaching the radiator.

FIG. 3 and FIG. 4 show the other example of the radiator 6. That is, FIG. 3 shows a metal wire wound in a coil shape so as to have a square tube shape as a whole, and FIG. 4 shows a coil wire wound so as to have a triangular tube shape as a whole. It is shown. In any of these modified examples, the flat surface of the modified example is brought into contact with the substrate 1 to be mounted, and thus the modified example has the advantages of stability and easy soldering.

Next, FIG. 5 shows another embodiment according to the present invention. In this embodiment, the radiator 6 is provided on the side surface of the substrate 1 in an "L" shape. For this purpose, the so-called mounting conductor layer 5 for mounting the radiator 6 by soldering is also arranged in an "L" shape. This embodiment has the advantage that a sufficiently long radiator can be attached even in a relatively small space, and a sufficiently large heat radiation effect can be obtained.

FIG. 6 shows still another embodiment according to the present invention. In this embodiment, the heat-dissipating conductor layer 5'is formed on the surface opposite to the surface on which the heat-generating element 2 is mounted, that is, the back surface thereof, and the radiator 6 similar to the above is soldered on the heat-dissipating conductor layer 5 '. ing. This embodiment has an advantage that the radiator 6 can be attached even if there is not enough space on the surface side of the substrate 1 on which the heat-generating component 2 is mounted. In this case, the conductor layer in which the heat-generating element 2 is arranged and the heat-dissipating conductor layer 5'may be connected by a through hole or the like as a heat conduction path for increasing heat transfer efficiency. It is possible.

[Effects of the Invention] As is clear from the above description, according to the circuit board of the present invention, the radiator itself is inexpensive and no special process is required for mounting the radiator. High economic effect can be obtained. Furthermore, even in the case of a coiled radiator, no current flows through it, so that the magnetic field does not adversely affect the surroundings, and the radiator itself does not generate heat. Moreover, since heat can be evenly transferred from a plurality of fixing points to the heat dissipation conductor to the metal wire forming the radiator to dissipate heat, the heat dissipation efficiency is high. Since the amount of heat radiation can be set arbitrarily by the number of turns of the radiator, it has high practicality.

[Brief description of drawings]

FIG. 1 is a perspective view showing the structure of a circuit board according to the present invention, FIGS. 2 (a) and 2 (b) are side and front views of the radiator shown in FIG. 1, and FIGS. The front view which shows the other example of the radiator shown to FIG. (A) and (b), and FIG. 5 and 6
The figure shows another embodiment of the present invention. 1 ... Substrate, 2 ... Heating element, 3 ... Terminal, 4 ... Wiring pattern, 5 ... Conductor layer, 6 ... Radiator

Claims (1)

[Scope of utility model registration request] 1. A circuit board in which a heat-generating element 2 is disposed on a conductor layer formed on the main surface of the substrate 1, and on a main surface of the substrate 1 in the vicinity of a location where the heat-generating element 2 is disposed. A circuit board, characterized in that a heat-dissipating conductor layer (5) is formed, and a coil outer peripheral portion of a heat-dissipator (6) made of a coil-shaped metal wire having a generally cylindrical shape is fixed on the heat-dissipating conductor layer (5).