Power supply module

A power supply module includes a circuit board and a heatsink plate. The circuit board includes a first principal surface, a second principal surface, and side surfaces. Electronic components are mounted on the first principal surface. The heatsink plate includes a plate-shaped body portion that faces the first principal surface, and a plurality of fixing portions that extend at an angle from the body portion to face the side surfaces. The fixing portions are configured to come into contact with the second principal surface to secure the body portion to the circuit board.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a power supply module, and particularly to a power supply module that includes a circuit board with electronic components mounted thereon.

2. Description of the Related Art

As an invention related to a power supply module of the related art, a housing for electronic components is known, which is described, for example, in Japanese Unexamined Patent Application Publication No. 2002-271064.FIG. 4is a cross-sectional view illustrating a structure of a housing500for electronic components, described in Japanese Unexamined Patent Application Publication No. 2002-271064.

The housing500includes an upper case504and a lower case506and contains a printed circuit board502. The upper case504is disposed on the upper side of the printed circuit board502. The lower case506is disposed on the lower side of the printed circuit board502. The printed circuit board502and the lower case506are sandwiched from above and below by the upper case504. The printed circuit board502, the upper case504, and the lower case506are thus formed into a single unit.

The housing500described in Japanese Unexamined Patent Application Publication No. 2002-271064 requires two components, the upper case504and the lower case506, and has a problem in terms of the number of components required.

SUMMARY OF THE INVENTION

Accordingly, preferred embodiments of the present invention provide a power supply module that includes fewer components than conventional devices.

A power supply module according to a preferred embodiment of the present invention includes a circuit board including a first principal surface, a second principal surface, and side surfaces, the circuit board including electronic components mounted on the first principal surface; and a heatsink plate including a plate-shaped body portion that faces the first principal surface and a plurality of fixing portions that extend at an angle from the body portion to face the side surfaces, the fixing portions being configured to come into contact with the second principal surface to secure the body portion to the circuit board.

Various preferred embodiments of the present invention provide a power supply module that includes fewer components than conventional devices.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A power supply module according to preferred embodiments of the present invention will now be described.

A configuration of a power supply module according to a preferred embodiment of the present invention will be described with reference to the drawings.

FIG. 1is an outside perspective view of a power supply module10according to a preferred embodiment of the present invention.FIG. 2is a five-side view of the power supply module illustrated inFIG. 1.FIG. 3is an exploded view of the power supply module10illustrated inFIG. 1. In the following description, the up-and-down direction inFIG. 1is simply referred to as an up-and-down direction. In plan view as viewed from above inFIG. 1, the direction in which shorter sides of the power supply module10extend is defined as a front-and-back direction, and the direction in which longer sides of the power supply module10extend is defined as a right-and-left direction.

The power supply module10is a direct-current (DC) or alternating-current (AC) power supply circuit. As illustrated inFIG. 1toFIG. 3, the power supply module10includes a heatsink plate12, a circuit board14, and a heatsink sheet member16.

The circuit board14preferably is a multilayered circuit board which is made of resin material and is substantially rectangular in plan view as viewed from above. The circuit board14includes principal surfaces S1and S2and side surfaces S3to S6. The principal surface S1is a surface located on the upper side. The principal surface S2is a surface located on the lower side. The side surface S3is a surface located on the front side. The side surface S4is a surface located on the right side. The side surface S5is a surface located on the back side. The side surface S6is a surface located on the left side. A circuit including copper conductors or the like is disposed on the principal surfaces S1and S2and inside the circuit board14.

As illustrated inFIG. 1toFIG. 3, electronic components50a,50b,52a, and52bare mounted on the principal surface S1of the circuit board14. As illustrated inFIG. 2andFIG. 3, a height h2of the electronic components52aand52bfrom the principal surface S1in the up-and-down direction is smaller than a height h1of the electronic components50aand50bfrom the principal surface S1in the up-and-down direction.

As illustrated inFIG. 1toFIG. 3, electronic components54a,54b, and56ato56care mounted on the principal surface S2of the circuit board14. As illustrated inFIG. 2andFIG. 3, a height h4of the electronic components56ato56cfrom the principal surface S2in the up-and-down direction is smaller than a height h3of the electronic component54aand54bfrom the principal surface S2in the up-and-down direction.

The electronic components50aand54aface each other in the up-and-down direction, with the circuit board14interposed therebetween, to define, for example, a ferrite core. Similarly, the electronic components50band54bface each other in the up-and-down direction, with the circuit board14interposed therebetween, to define, for example, a ferrite core. A choke coil or transformer is formed when such a ferrite core is configured to pass through a coil pattern in the circuit board14. The electronic component52aand52bpreferably are semiconductor devices. For example, the electronic component52aand52bpreferably are switching devices, such as field-effect transistors (FETs). The electronic components52aand52bare devices that generate heat more easily than the electronic components50a,50b,54a, and54b. The electronic components50a,50b,52a,52b,54a,54b, and56ato56cand the circuit in the circuit board14define a power supply circuit.

The circuit board14is provided with external connection terminals30ato30jprotruding downward from the principal surface S2. As illustrated inFIG. 2, the external connection terminals30ato30eare aligned in this order from the front to the back, along the right (shorter) side of the principal surface S2. Also as illustrated inFIG. 2, the external connection terminals30fto30jare aligned in this order from the front to the back, along the left (shorter) side of the principal surface S2.

A height H2indicates the height of the external connection terminals30ato30jfrom the principal surface S2in the up-and-down direction. The external connection terminals30ato30jpreferably are stepped pins. As illustrated inFIG. 2, the external connection terminals30ato30jhave each a base portion60and an end portion62. For simplicity of the drawing, these reference numerals are given only to the base portion60and the end portion62of the external connection terminal30ainFIG. 2. The base portion60is the upper portion of each of the external connection terminals30ato30j, and has a diameter greater than that of the end portion62. A height H3indicates the height of the base portion60from the principal surface S2in the up-and-down direction. The end portion62is the lower portion of each of the external connection terminals30ato30j, and has a diameter smaller than that of the base portion60. When the power supply module10is mounted on another circuit board or apparatus, the end portions62are inserted into the circuit board or apparatus. However, the base portions60are not inserted into the circuit board or apparatus in this case. Thus, when the power supply module10is mounted on another circuit board or apparatus, the circuit board14is held at the height H3from the circuit board or apparatus.

The height H3of the base portions60from the principal surface S2in the up-and-down direction is greater than the height h3of the electronic components54aand54bfrom the principal surface S2in the up-and-down direction. Therefore, when the power supply module10is mounted on another circuit board or apparatus, the electronic components54aand54bcan be prevented from coming into contact with the circuit board or apparatus.

The heatsink plate12preferably includes a single metal plate (aluminum plate). The heatsink plate12preferably includes a body portion20, fixing portions22ato22d, and bent portions26ato26d.

The body portion20preferably is a plate-shaped member located above the circuit board14to face the principal surface S1. In plan view as viewed from above, the body portion20is a substantially rectangular member having the same or substantially the same size as the circuit board14. As illustrated inFIG. 1andFIG. 3, the body portion20is provided with recessed portions G1and G2extending downward (or toward the circuit board14). In plan view as viewed from above (in the direction of the normal to the principal surface S1), the recessed portions G1and G2overlap with the electronic components52aand52b, respectively. It is preferable that the depth of the recessed portions G1and G2be substantially the same as the difference between the height h1and the height h2.

The fixing portions22ato22dextend at an angle from the body portion20to face the corresponding side surfaces S3and S5. The fixing portions22ato22dthen come into contact with the principal surface S2to secure the body portion20to the circuit board14. Specifically, the fixing portion22apreferably is a belt-shaped member extending in the up-and-down direction. The fixing portion22aextends downward at an angle from the body portion20at the left end of the front (longer) side of the body portion20. The fixing portion22afaces the circuit board14near the left end of the side surface S3and extends to a position below the circuit board14. The fixing portion22ais provided with a protrusion24aat an end portion thereof extending below the circuit board14. The protrusion24aprotrudes backward from the fixing portion22a. The protrusion24ais in contact with the principal surface S2near the left end of the front (longer) side of the principal surface S2.

The fixing portion22bpreferably is a belt-shaped member extending in the up-and-down direction. The fixing portion22bextends downward at an angle from the body portion20at the right end of the front (longer) side of the body portion20. The fixing portion22bfaces the circuit board14near the right end of the side surface S3and extends to a position below the circuit board14. The fixing portion22bis provided with a protrusion24bat an end portion thereof extending below the circuit board14. The protrusion24bprotrudes backward from the fixing portion22b. The protrusion24bis in contact with the principal surface S2near the right end of the front (longer) side of the principal surface S2.

The fixing portion22cpreferably is a belt-shaped member extending in the up-and-down direction. The fixing portion22cextends downward at an angle from the body portion20at the left end of the back (longer) side of the body portion20. The fixing portion22cfaces the circuit board14near the left end of the side surface S5and extends to a position below the circuit board14. Thus, the fixing portions22aand22cface each other in the front-and-back direction, with the circuit board14interposed therebetween. The fixing portion22cis provided with a protrusion24cat an end portion thereof extending below the circuit board14. The protrusion24cprotrudes forward from the fixing portion22c. The protrusion24cis in contact with the principal surface S2near the left end of the back (longer) side of the principal surface S2.

The fixing portion22dpreferably is a belt-shaped member extending in the up-and-down direction. The fixing portion22dextends downward at an angle from the body portion20at the right end of the back (longer) side of the body portion20. The fixing portion22dfaces the circuit board14near the right end of the side surface S5and extends to a position below the circuit board14. Thus, the fixing portions22band22dface each other in the front-and-back direction, with the circuit board14interposed therebetween. The fixing portion22dis provided with a protrusion24dat an end portion thereof extending below the circuit board14. The protrusion24dprotrudes forward from the fixing portion22d. The protrusion24dis in contact with the principal surface S2near the right end of the back (longer) side of the principal surface S2. Thus, the fixing portions22ato22dsecure the heatsink plate12in place at the four corners of the circuit board14.

As illustrated inFIG. 2, a height H1indicates the height of the fixing portions22ato22dfrom the principal surface S2in the up-and-down direction. The height H1is smaller than the height H2. Thus, since the lower ends of the end portions62of the external connection terminals30ato30jare located below the lower ends of the fixing portions22ato22d, the end portions62can be inserted into another circuit board or apparatus. The height H1is preferably smaller than the height H3. Thus, when the entire end portions62are inserted into another circuit board or apparatus, the fixing portions22ato22dcan be prevented from coming into contact with the circuit board or apparatus.

The bent portions26ato26dextend at an angle from the body portion20in the same direction as the fixing portions22ato22d(i.e., the bent portions26ato26dextend downward). The bent portions26ato26dhave a height smaller than that of the fixing portions22ato22dfrom the body portion20in the up-and-down direction. Specifically, the bent portion26aextends along the front (longer) side of the body portion20. The bent portion26ais connected, at both ends thereof in the right-and-left direction, to the fixing portions22aand22b. The bent portion26adoes not face the side surface S3of the circuit board14. Thus, the bent portion26ais separated by a gap from the circuit board14.

The bent portion26bextends along the right (shorter) side of the body portion20. The bent portion26bdoes not face the side surface S4of the circuit board14. Thus, the bent portion26bis separated by a gap from the circuit board14.

The bent portion26cextends along the back (longer) side of the body portion20. The bent portion26cis connected, at both ends thereof in the right-and-left direction, to the fixing portions22cand22d. The bent portion26cdoes not face the side surface S5of the circuit board14. Thus, the bent portion26cis separated by a gap from the circuit board14.

The bent portion26dextends along the left (shorter) side of the body portion20. The bent portion26ddoes not face the side surface S6of the circuit board14. Thus, the bent portion26dis separated by a gap from the circuit board14.

The heatsink plate12is formed preferably by die-cutting, bending, and press working a single metal plate, for example. Specifically, the fixing portions22ato22dand the bent portions26ato26dare formed preferably by bending, and the protrusions24ato24dand the recessed portions G1and G2are formed preferably by press working, for example.

As illustrated inFIG. 3, the heatsink sheet member16is interposed between the principal surface S1and the body portion20. The heatsink sheet member16is in contact with the electronic components50a,50b,52a, and52band the body portion20. The heatsink sheet member16is made of material having good heat dissipation properties. For example, the heatsink sheet member16is preferably made of a silicone compound. The heatsink sheet member16preferably has elasticity.

The power supply module10configured as described above includes fewer components than conventional devices. Specifically, the heatsink plate12extends downward at an angle from the body portion20to face the side surfaces S3and S5and come into contact with the principal surface S2. Thus, the heatsink plate12is secured to the circuit board14. The heatsink plate12of the power supply module10is composed of a single component. This means that the power supply module10includes fewer components than the housing500described in Japanese Unexamined Patent Application Publication No. 2002-271064.

In the power supply module10, the heatsink plate12is secured to the circuit board14by the fixing portions22ato22dthat form and define a portion of the heatsink plate12. Therefore, the power supply module10does not require any screws or fittings for securing the heatsink plate12to the circuit board14. This means again that the power supply module10includes fewer components than conventional devices.

In the power supply module10, the heatsink plate12is formed preferably by bending and press working a single metal plate. A mold used for bending and press working is less costly than that for casting. Therefore, the cost of producing the heatsink plate12is lower than that of producing a heatsink plate by casting.

The power supply module10can achieve a high heat dissipation effect. Specifically, the body portion20is provided with the recessed portions G1and G2extending toward the circuit board14. In plan view as viewed from above, the recessed portions G1and G2overlap with the electronic components52aand52b, respectively, having the height h2that is smaller than the height h1of the electronic components50aand50b. This reduces the distance between the body portion20and the electronic components52aand52b. Thus, heat generated by the electronic components52aand52bis efficiently transferred via the heatsink sheet member16to the body portion20. With the recessed portions G1and G2of the body portion20, the distance between the body portion20and the electronic components52aand52bis close to that between the body portion20and the electronic components50aand50b. This means that the magnitude of force applied from the electronic components52aand52bto the body portion20is close to that applied from the electronic components50aand50bto the body portion20. It is thus possible to reduce concentration of stress on portions of the body portion20.

The height H1of the fixing portions22ato22dfrom the principal surface S2in the up-and-down direction is smaller than the height H2. Thus, since the lower ends of the end portions62of the external connection terminals30ato30jare located below the lower ends of the fixing portions22ato22d, the end portions62can be inserted into another circuit board or apparatus. The height H1is smaller than the height H3of the base portions60of the external connection terminals30ato30jfrom the principal surface S2in the up-and-down direction. Thus, when the entire end portions62are inserted into another circuit board or apparatus, the fixing portions22ato22dcan be prevented from coming into contact with the circuit board or apparatus.

The heatsink plate12has the bent portions26ato26dextending at an angle from the body portion20in the same direction as the fixing portions22ato22d. Since this increases the moment of inertia of area of the body portion20, the strength of the body portion20is improved. As described above, the bent portions26aand26care connected, at their both ends in the right-and-left direction, to the corresponding fixing portions22ato22d. This reduces the possibility of damage to the fixing portions22ato22d.

As illustrated inFIG. 3, the heatsink sheet member16is interposed between the principal surface S1and the body portion20and is in contact with the electronic components50a,50b,52a, and52band the body portion20. Thus, heat generated by the electronic components50a,50b,52a, and52bis transferred via the heatsink sheet member16to the body portion20. This improves the heat dissipation properties of the power supply module10.

The heatsink sheet member16has elasticity. Thus, the heatsink sheet member16presses the body portion20and the circuit board14upward and downward, respectively. Since this causes the protrusions24ato24dto be firmly pressed against the circuit board14, it is possible to reduce looseness of the circuit board14in the up-and-down direction with respect to the heatsink plate12. With the heatsink sheet member16having elasticity, the electronic components50a,50b,52a, and52bare prevented from directly coming into contact with the body portion20. Thus, since a force applied from the electronic components50a,50b,52a, and52bto the body portion20is distributed by the heatsink sheet member16over the entire body portion20, it is possible to reduce concentration of stress on portions of the body portion20.

The heatsink plate12is formed preferably by bending and press working a single metal plate. For better workability, a thin metal plate is used to make the heatsink plate12. Therefore, the power supply module10is lighter in weight and lower in profile than a power supply module that includes a heatsink plate produced by casting.

Other Preferred Embodiments

The power supply module according to the present invention is not limited to the power supply module10of the preferred embodiment described above, and may be changed within the scope of the present invention.

In the power supply module10, the fixing portions22ato22dpreferably have the protrusions24ato24dformed by press working, for example. The protrusions24ato24dpreferably are in contact with the principal surface S2of the circuit board14to secure the heatsink plate12to the circuit board14. However, the heatsink plate12may be secured to the circuit board14in other ways. For example, the fixing portions22aand22bmay be bent backward at the lower ends thereof to come into contact with the principal surface S2, and the fixing portions22cand22dmay be bent forward at the lower ends thereof to come into contact with the principal surface S2. In this case, the fixing portions22ato22dcannot be bent if lower end portions thereof are not long enough to allow bending. It is thus necessary to ensure that the lower end portions of the fixing portions22ato22dare long enough to be bent. Bending the fixing portions22ato22dincreases the contact area where the fixing portions22ato22dare in contact with the principal surface S2. This means that the heatsink plate12is more firmly secured to the circuit board14.

Note that although bending the fixing portions22ato22dincreases the contact area where the fixing portions22ato22dare in contact with the principal surface S2, this results in a decrease in area for mounting electronic components on the principal surface S2. To allow mounting of more electronic components, it is preferable to use the protrusions24ato24ddescribed above.

Although the circuit board14and the body portion20preferably are substantially rectangular in plan view as viewed from above, for example, their shape is not limited to this.

The positions where the fixing portions22ato22dare in contact with the principal surface S2of the circuit board14are not limited to the four corners of the principal surface S2. The fixing portions22ato22dmay be in contact with the principal surface S2at any positions, as long as the fixing portions22ato22dcan secure the heatsink plate12to the circuit board14. For the fixing portions22ato22dto secure the heatsink plate12to the circuit board14, it is only necessary that two of the fixing portions22ato22dbe disposed to face one side surface of the circuit board14and that the other two of the fixing portions22ato22dbe disposed to face the opposite side surface of the circuit board14. Thus, the circuit board14is sandwiched between the fixing portions22ato22d.

Various preferred embodiments of the present invention are useful when applied to power supply modules, and particularly advantageous in reducing the number of components of such power supply modules.