JP4454270B2 - Power supply heat dissipation structure - Google Patents

Description

  The present invention relates to a heat dissipation structure for a power supply device, and more particularly to a heat dissipation structure provided with a heat dissipation base standing on a substrate.

  Since many power supply devices are provided with a circuit corresponding to a large current or a high voltage, a countermeasure for heat radiation becomes a major issue. For example, the invention described in Patent Document 1 relates to a heat dissipation structure for an inverter power source of a high-frequency heating device. In the present invention, a primary winding of a high-voltage transformer on a substrate is wound around a ferrite core in a cylindrical shape, and the circumferential surface of the cylindrical primary winding is perpendicular to a printed circuit board. The heat dissipating fin with the semiconductor element attached is disposed at a position facing the cylindrical circumferential surface formed by the primary winding. With such a configuration, since a gap is formed between the radiation fin and the high-voltage transformer, the air flow from the cooling fan becomes smooth, and the cooling effect of the semiconductor element and the like can be improved even in a device having a high mounting density.

However, as the demand for miniaturization of power supply devices is increasing, the room for changing the arrangement of components on the board is becoming smaller, and it becomes increasingly difficult to smooth the air flow by this means. Yes. Furthermore, it has become common to provide a bead core for noise suppression at the lead portion of the semiconductor element attached to the heat dissipation base, and this bead core tends to hinder the flow of air. Of course, if air is applied from the position facing the semiconductor element, heat can be dissipated sufficiently, but it is extremely difficult to arbitrarily select the location of the cooling fan in a situation where further downsizing of the power supply device is required. is there.
JP 2001-185339 A (page 2-4, FIG. 1)

  The present invention has been made in view of the above-described circumstances, and in the heat dissipation structure of the power supply device, it is not necessary to change the arrangement of components and cooling fans on the board and does not hinder downsizing of the power supply device. The purpose is to provide.

  In order to solve the above-described problems, the present invention provides a heat dissipation structure for a power supply device including a heat dissipation base provided so as to rise from a substrate, wherein the heat dissipation base is attached to a portion where a semiconductor element on the base end side is attached. A notch for securing a gap between the substrate and the substrate is formed.

  Therefore, since air flowing inside the power supply device passes between the heat dissipation base and the substrate, the air circulation inside the power supply device is improved and the heat dissipation effect is enhanced.

  In the above invention, the height of the notch from the substrate surface may be substantially equal to the height of the upper end of the bead core attached to the lead portion of the semiconductor element.

  Further, the present invention provides a heat dissipation structure of a power supply device including a heat dissipation base provided so as to rise from a substrate, and includes a spacer provided between the heat dissipation base and the substrate, The base side edge is separated from the substrate by the spacer.

  Therefore, since air flowing inside the power supply device passes between the heat dissipation base and the substrate, the air circulation inside the power supply device is improved and the heat dissipation effect is enhanced. In addition, the notch processing on the base end side of the heat radiating base is not necessary.

  Further, in the above invention, the height of the upper end of the spacer from the substrate surface can be substantially equal to the height of the upper end of the bead core attached to the lead portion of the semiconductor element.

In the present invention, since air passes between the heat dissipation base and the substrate, air circulation around the bead core is improved, and the heat dissipation effect of the semiconductor element and the bead core is enhanced. Further, providing a gap between the heat dissipation base and the substrate does not affect the arrangement of components at all, and thus does not hinder downsizing of the power supply device. Furthermore, since the surface area of the heat dissipation base that contributes to heat dissipation increases by exposing the base end side of the heat dissipation base, the volume of the heat dissipation base can be reduced by an amount corresponding to the surface area.

  In the embodiment of the present invention, the greatest feature is that a gap is provided between the heat dissipating base and the substrate, in particular, at a portion where the semiconductor element of the heat dissipating base is attached. FIG. 4 is a table showing the results of a comparative experiment relating to the cooling effect between the heat dissipation structure of the present invention and the heat dissipation structure of the prior art.

  In this experiment, a rectifier having an input voltage of AC 180 V, an output voltage of 48 V, and an output current of 158 A was used, and a plate-like heat radiating base without heat radiating fins was prepared. Ten rectifying diodes and four flywheel diodes were attached to each phase on the front and back of the heat dissipation base. In the heat dissipation structure of the present invention, a spacer as in Example 2 to be described later is provided, thereby providing a gap of about 10 mm between the heat dissipation base and the substrate. This gap corresponds to the height of the upper end of the bead core provided in these diodes. On the other hand, in the heat dissipation structure of the prior art, the heat dissipation structure and the substrate are in contact with each other. The parts other than the spacers have the same configuration in both structures. And the voltage rise was input into the rectifier, and the temperature rise of the measurement site | part of each structure at the time of the ambient atmosphere of a thermal radiation base | substrate becoming 50 degreeC was measured. The temperature-measured portion 1 is a rectifying diode-side bead core located near the support portion of the heat dissipation base, and the portion 2 is a flywheel diode-side bead core located near the center of the heat dissipation base.

  As can be seen from FIG. 4, it has been clarified that the cooling effect of the heat dissipation base can be greatly enhanced by providing a gap between the heat dissipation base and the substrate. In addition, according to research results including other experiments by the inventors, it was found that this gap is effective not only when a cooling fan is provided in the power supply device but also when cooling only by natural air cooling. . An embodiment having this feature will be described below.

  FIG. 1 is an explanatory diagram of a heat dissipation structure for a power supply device according to a first embodiment of the present invention. In FIG. 1, 10 is a heat dissipation base, 11 is a support portion, 12 is a notch, 13a and 13b are flat surfaces for mounting, 14 is a heat dissipation fin, 20 is a substrate, 21a and 21b are semiconductor elements, 22 is a lead portion, 23 Indicates a bead core. The heat dissipation structure shown in FIG. 1 is housed in the casing of the power supply apparatus, and a wiring pattern is formed on the substrate 20 and a large number of electronic components are mounted. Description of the casing, the wiring pattern, and the electronic parts not related to the present invention is omitted.

  FIG. 1A is a perspective view of the heat dissipation structure of the power supply device according to the first embodiment. As shown in FIG. 1A, the heat radiating base 10 is provided in a state of rising on the substrate 20, and mounting flat surfaces 13a and 13b are formed on both the front and back surfaces. The mounting flat surfaces 13a and 13b are formed below the heat dissipation base 10 and absorb heat from the semiconductor elements 21a and 21b. Further, heat radiating fins 14 are formed on the heat radiating base 10. The heat radiating fins 14 serve to dissipate heat transferred from the semiconductor elements 21a and 21b to the upper portion 12 of the heat radiating base 10 into the surrounding atmosphere. Note that if the casing of the power supply device is brought into contact with the upper end portion of the heat dissipation base 10, the casing also becomes a part of the heat dissipation structure, so that the heat dissipation efficiency can be further improved. In addition, when heat dissipation capability is not required for the heat dissipation base 10 or when auxiliary means for heat dissipation is provided, such as bringing the casing of the power supply device into contact with the upper end of the heat dissipation base 10, the heat dissipation fins 14 are provided. It is also possible to omit the heat dissipation base 10 and form the entire shape of the heat dissipation base 10 in a plate shape.

  The lead portions 22 of the semiconductor elements 21a and 21b are provided with a bead core 23 as a noise countermeasure. The bead core 23 is formed in a cylindrical shape, and is provided through the lead portion 23 therein. In addition, in order to hold the bead core 23 at a predetermined portion of the lead portion 22, the bead core 23 may be attached to the lead portion 22 with an adhesive.

  FIG. 1B is a cross-sectional view taken along the line AA in FIG. 1A, and shows an example in which a large number of semiconductor elements are attached to portions other than the left and right end portions of the lower end portion of the heat dissipation base 10. As shown in FIG. 1 (b), a notch 12 is formed at the semiconductor element pasting portion at the lower end of the heat dissipation base 10. The notch 12 is for providing a gap between the heat dissipation base 10 and the substrate 20 and for blowing air sent from the cooling fan. By blowing air, cooling of the semiconductor element and the bead core is promoted.

  By the way, it is desirable that the notch 12 has a height substantially equal to the upper end of the bead core 23. The reason is described below. FIG. 2 is a cross-sectional view showing the height relationship between the notch and the bead core. In FIG. 2, h1 is the height of the notch 12 from the substrate surface, h2 is the height from the substrate surface to the upper end of the bead core 23, and h3 is the height from the substrate surface to the lower end of the mold part of the semiconductor element 21a. Indicates.

  The outer diameter of the bead core 23 is considerably larger than the thickness (width) of the lead portion 22. When the bead cores 23 are passed through the lead portions 22, the bead cores 23, or the interval between the bead cores 23 and the lead portions 22 or the heat dissipation base 10, is the lead portions 22 when the bead cores 23 are not provided, or the lead portions 22 and the heat dissipation substrate 10. It is much narrower than the interval. Therefore, when the bead core 23 is provided, the flow of air sent from the semiconductor element cooling fan is hindered, and the heat dissipation near the lead portion 22 is lowered.

  Therefore, if the notch 12 having a height substantially equal to the upper end of the bead core 23 is formed, that is, if h1 and h2 in FIG. 2 are substantially equal, the air around the bead core 23 is notched as described above. Heat dissipation is improved by passing through the portion 12. If the height of the notch 12 is higher than that of the upper end of the bead core 23, for example, h1 and h3 are equal, the heat dissipation near the lead 22 is further improved. However, if the semiconductor element is manually attached to the heat radiating base 10, if there is no margin, for example, the vicinity of the lower end of the semiconductor element 21a may not protrude from the mounting flat surface 13a and be bonded to the heat radiating base 10. Case occurs. Such a protruding portion is not preferable because it causes troubles in heat dissipation of the semiconductor element. On the contrary, if the height of the notch portion 12 is lower than the height of the upper end portion of the bead core 23, the amount of air passing through the notch portion 12 is reduced, so that the heat dissipation in the vicinity of the lead portion 22 is not improved so much. Therefore, it can be said that it is most desirable to make h1 and h2 in FIG. 2 substantially equal.

  In addition, since the notch 12 is formed corresponding to the part to which the semiconductor element is applied, for example, when the semiconductor element is not attached to the vicinity of the center in addition to the left and right ends of the mounting flat surface 13a, It is not necessary to form the notch portion 12.

  Further, both left and right end portions of the lower end portion where the notch portion 12 is not formed serve as a support portion 11 that supports the heat dissipating base body 10 in a state of rising on the substrate 20. In the case where the semiconductor element is not attached near the center of the mounting flat surface 13a, a support portion can be formed in the vicinity. Of course, a support portion can be formed in a portion other than the vicinity of the center where the semiconductor element is not attached.

  As described above, according to the above-described heat dissipation structure, air circulation near the lead portions 22 of the semiconductor elements 21a and 21b attached to the mounting flat surfaces 13a and 13b is improved. Can be improved. Of course, it is not necessary to change the installation position of the cooling fan. Further, since the lower end portion of the heat radiating base 10 is exposed, this vicinity is also cooled by the air passing through the notch 12, and the heat radiating property of the heat radiating base 10 is improved.

  FIG. 3 is an explanatory diagram of the heat dissipation structure of the power supply device according to the second embodiment of the present invention. In FIG. 3, 15 is a spacer, and other reference numerals are the same as those in FIG.

  As shown in FIG. 3, the heat dissipation structure of the power supply device according to the second embodiment of the present invention is a structure in which a gap is provided by a spacer 15 instead of the structure in which a gap is provided by the notch 12 shown in FIG. is there. That is, the spacer 15 is interposed between the heat dissipation base 10 and the substrate 20 so that the heat dissipation base 10 floats from the surface of the substrate 20. In addition, the spacer 15 is provided in the site | part which does not affix the semiconductor element of the mounting flat surface 13a similarly to the support part 11. FIG. The structure of other parts is the same as that shown in FIG. The spacer 15 is preferably made of resin in terms of ensuring insulation, but other materials such as rubber and ceramic can also be used. The fixing means for the substrate 20, the spacer 15 and the heat dissipation base 10 is preferably a screw, but can be fixed with an adhesive.

  According to the above heat dissipation structure, the same effect as that of the heat dissipation structure shown in FIG. 1 can be obtained. Further, although a new part called the spacer 15 is required, since it is not necessary to form the notch 12 in the heat dissipation base 10, the cost required for processing the heat dissipation base 10 can be reduced.

  1 may be combined with the spacer 15 of FIG. 3 to provide a gap between the heat dissipation base 10 and the substrate 20. In the case of this structure, for example, a bushing for ensuring insulation between the heat dissipation base 10 and the substrate 20 can be used as the spacer 15, so that it is easy to secure a gap. In each of the above embodiments, the heat dissipation structure for the semiconductor element such as a rectifying diode or MOSFET has been described. However, the present invention can be applied to the case where the heat dissipation target is another device such as a resistor or a transformer. In addition, the heat radiating base has been described as having a plate-like lower portion. However, if a gap can be formed between the substrate and the substrate, the lower portion may have other shapes such as an L shape or a yo-shape. It is also good. Needless to say, this structure also has an effect even when the semiconductor element is attached to only one surface.

It is explanatory drawing of the thermal radiation structure of the power supply device which concerns on the 1st Example of this invention. It is sectional drawing which shows the relationship of the height of a notch part and a bead core. It is explanatory drawing of the thermal radiation structure of the power supply device which concerns on 2nd Example of this invention. It is a table | surface which shows the comparative experiment result regarding the cooling effect of the thermal radiation structure of this invention, and the thermal radiation structure of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Radiation base 11: Support part 12: Notch part 13a: Mounting flat surface 13b: Mounting flat surface 14: Radiation fin 15: Spacer 20: Substrate 21a: Semiconductor element 21b: Semiconductor element 22: Lead part 23: Bead core

Claims (2)

In the heat dissipation structure of the power supply device provided with the heat dissipation base provided to stand up from the substrate,
Provide a semiconductor element with a bead core attached to the lead,
The heat dissipation base has the semiconductor element attached to the base end side, and a notch for securing a gap between the substrate and the substrate is formed at this part .
A heat dissipation structure for a power supply device , wherein a height of the notch from the substrate surface is substantially equal to a height of an upper end of a bead core attached to a lead portion of the semiconductor element . In the heat dissipation structure of the power supply device provided with the heat dissipation base provided to stand up from the substrate,
Provide a semiconductor element with a bead core attached to the lead,
A spacer provided between the heat dissipation base and the substrate;
The base of the heat dissipating base is separated from the substrate by the spacer ,
A heat dissipation structure for a power supply device , wherein a height of an upper end of the spacer from the substrate surface is substantially equal to a height of an upper end of a bead core attached to a lead portion of the semiconductor element .

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