JP4405843B2 - Switching power supply - Google Patents

Description

The present invention relates to a single substrate type switching power supply device in which a printed circuit board on which a power supply circuit is mounted without being housed in a case is attached to a device to be used.

  Conventionally, as a single substrate type switching power supply device, for example, there is one shown in FIG. In FIG. 4, the single substrate type switching power supply device has a metal plate 102 serving as a radiator and a reinforcing plate fixed in the longitudinal direction of the side edge of the printed circuit board 101.

  That is, in the case of a single substrate type switching power supply device, when vibration is applied, the printed circuit board 101 may bend due to the weight of the component, causing cracks in the soldered part of the mounted component and cracks in the printed circuit board. There is a case. Further, if the printed circuit board 101 bends during soldering dip, it may cause warpage of the printed circuit board 101 thereafter. In order to prevent this, a structure is adopted in which a metal plate 102 that also serves as a radiator is fixed to the printed board 101 to reinforce the printed board 101.

  The metal plate 102 is fixed to the printed circuit board 101 by bending the mounting pieces 104, 105, and 106 having screw holes 103 at three positions on both sides and the center of the metal plate 102 into an L shape. , 106 through holes 107, 108, 109 are formed at positions of the printed circuit board 101 opposite to the screw holes 103, and are fixed by screwing into the screw holes 103 through the screws 110, 111, 112 from below. The metal plate 102 also serves as a heat sink, and a heating element 118 such as an FET or SCR is attached to the metal plate 102.

Further, the printed circuit board 101 is mounted with respective circuit components with the imaginary line 113 as a boundary and the right side serving as the primary circuit portion 114 of the switching power supply circuit and the left side serving as the secondary circuit portion 115. Correspondingly, a frame ground potential pattern (hereinafter referred to as “FG potential pattern”) 116 of the primary side circuit unit 114 is formed at the position of the through hole 107 on the right end of the printed circuit board 101. The FG potential pattern 117 of the secondary side circuit unit 115 is formed at the position, and the FG potential patterns 116 and 117 are connected by fixing the mounting pieces 104 and 106 at both ends of the metal plate 102 with screws 110 and 112, and the primary side. It also has a function of electrically connecting the FG potential of the circuit portion 114 and the FG potential of the secondary side circuit portion 115.
Japanese Patent Laid-Open No. 2002-232170

  However, in such a conventional single substrate type switching power supply device, the screws 110, 111, and 112 for fixing the metal plate 102 to the printed circuit board 101 are at the frame ground potential (hereinafter referred to as "FG potential"). It is necessary to secure a creepage distance that satisfies the safety standard defined in the acquired safety standard of the product between the circuit component having the primary potential mounted on the printed circuit board 101 and the fixing screws 110 and 111. There is.

  Therefore, circuit components having a primary potential can be arranged around the screws 110 and 111 that fix the mounting pieces 104 and 105 of the metal plate 102 provided on the primary circuit portion 114 of the printed circuit board 101. There is a problem that the mountable area of the primary side circuit component is reduced.

An object of this invention is to provide the switching power supply device provided with the attachment structure of the metal plate which can increase the arrangement area of the primary side circuit components on a printed circuit board.

  In order to achieve this object, the present invention is configured as follows. The present invention includes a printed circuit board on which circuit components are mounted and a mounting hole for a device to be used, and a metal plate that is fixed to the side edge of the printed circuit board in an upright state and serves as a printed circuit board reinforcing plate and a radiator. In the switching power supply apparatus, the printed circuit board forms through holes at positions where the FG potential pattern of the primary side circuit unit and the FG potential pattern of the secondary side circuit unit are formed, and is between the through holes. A rectangular fitting notch is formed at the side surface, and the metal plate is bent to form a board mounting piece with a screw hole at the lower end of the position corresponding to the through hole of the printed circuit board, and the position corresponding to the fitting notch The fitting piece of the metal plate is inserted into the fitting notch of the printed circuit board from the lateral direction and the screw hole of the metal plate is aligned with the through hole of the printed circuit board. And characterized in that a fixing structure for fixing screwed Luo screws.

Here, the metal plate fitting piece extends to the lower side of the printed circuit board and has a width exceeding the cutout of the printed circuit board. It has a fitting shape cut into a rectangle. Moreover, you may make it provide the fitting piece of a metal plate, and the notch of a printed circuit board in multiple places.

According to the present invention, the fixed portion for connecting the FG potential pattern of the primary side circuit portion and the FG potential pattern of the secondary side circuit portion is connected using screws as in the conventional structure, and the primary side circuit portion is connected to the primary side circuit portion. The fixed part of the printed circuit board and the sheet metal provided in the primary circuit part that does not have the function of connecting the FG potential pattern of the secondary circuit part does not use a screw, but the fitting piece of the metal plate and the printed cutout of the printed circuit board The area that the fitting and fixing structure occupies on the printed circuit board can be made smaller than the area that the screw occupies on the printed circuit board. It is possible to increase the arrangement area of the primary side circuit components arranged at a predetermined creepage distance on the printed circuit board, and as a result, downsizing and cost reduction of the device can be achieved.

  FIG. 1 is an explanatory view showing an embodiment of a mounting structure of a printed board and a metal plate. FIG. 1 (A) shows a front view, FIG. 1 (B) shows a bottom view, and FIG. 1 (C) shows a side view. ing.

  In FIG. 1, in the switching power supply device of the present invention, a metal plate 2 is fixed in an upright state at a side end in a longitudinal direction of a printed board 1 on which components constituting a switching power supply circuit are mounted.

  The metal plate 2 also serves as a reinforcing plate and a heat sink for the printed circuit board 1 by being fixed to the printed circuit board 1. Further, the FG potential pattern of the primary circuit section and the secondary circuit section, which will be clarified later, is connected. Also serves as a connecting member.

  As shown in FIG. 1B, the printed circuit board 1 is mounted with components constituting the primary circuit section 14 on the right side with the imaginary line 13 as a boundary, and components constituting the secondary circuit section 15 are mounted on the left side. Implemented. An FG potential pattern 16 connected to the FG potential of the primary side circuit portion 14 is formed on the right end portion of the printed circuit board 1 on the side where the metal plate 2 is attached to the primary side circuit portion 14.

  On the other hand, an FG potential pattern 17 to which the FG potential of the secondary side circuit portion 15 is connected is formed at the upper left end portion on the metal plate 2 side on the secondary side circuit portion 15 side. The formation positions of the FG potential patterns 16 and 17 are the formation positions of the through holes 7 and 9 for attaching the metal plate 2.

  In this embodiment, the metal plate 2 is provided with fixing portions in three places on both sides and the center. On both sides of the metal plate 2, mounting pieces 4 and 6 bent in an L shape in the direction of the printed circuit board 1 are formed. The mounting pieces 4 and 6 correspond to the through holes 7 and 9 of the printed circuit board 1. A screw hole 3 is formed.

  Therefore, the screws 10 and 12 are fitted into the screw holes 3 of the mounting pieces 4 and 6 through the through holes 7 and 9 from the lower side of the printed circuit board 1 in a state where the metal plate 2 is set to the mounting position with respect to the printed circuit board 1. By doing so, both ends are fixed to the printed circuit board 1 with screws.

  A fitting piece 5 is provided at the center of the metal plate 2, and a rectangular fitting notch 8 is formed on the side surface of the printed circuit board 1 facing the fitting piece 5. When the metal plate 2 is attached to the printed board 1, the metal plate 2 is fitted and fixed to the fitting notch 8 of the printed board 1 by being fitted to the fitting piece 5 of the metal plate 2 from the lateral direction.

  A heat generating element 18 such as an FET or SCR is attached to the metal plate 2 fixed to the printed circuit board 1, and the metal plate 2 functions as a heat radiating plate. Moreover, since the screws 10 and 12 are inserted into the through holes 7 and 9 of the FG potential patterns 16 and 17 formed on the printed circuit board 1 and screwed into the screw holes 3 of the mounting pieces 4 and 6 on the metal plate 2 side, The FG potential pattern 16 and the FG potential pattern 17 on the printed circuit board 1 side are connected via the metal plate 2 by screwing and fixing with the screws 10 and 12.

  FIG. 2 is an explanatory view showing the fitting structure of the printed board 1 and the metal plate 2 in FIG. In FIG. 2, on the printed circuit board 1 side, a rectangular fitting notch 8 opened on the side end surface is formed. Here, the fitting notch 8 has a width a1. The thickness of the printed circuit board 1 is b1.

  The fitting piece 5 on the metal plate 2 side has a width W that exceeds the width a1 of the opening in the fitting notch 8 of the printed circuit board 1, and the fitting piece 5 on the front side facing the fitting notch 8 of the printed circuit board 1. The fitting groove 19 is formed by leaving the fitting part 19 at the center and notching both sides.

  Here, the width a2 of the fitting portion 19 in the fitting piece 5 is set to be slightly smaller than the width a1 of the fitting notch 8 in the printed circuit board 1. Further, the height b2 of the fitting groove 20 formed on both sides of the fitting portion 19 is formed to be slightly larger than the thickness b1 of the printed circuit board 1.

  And as shown by the arrow, the fitting part 19 of the fitting piece 5 is printed by fitting the fitting part 19 and the fitting groove 20 of the fitting piece 5 to the fitting notch 8 of the printed circuit board 1 from the lateral direction. The fitting groove 5 of the fitting piece 5 is fitted into the portions of the printed board 1 on both sides of the fitting notch 8 in the printed board 1 and is fixedly fitted.

  According to the fixing structure of the printed circuit board 1 and the metal plate 2 of the present invention, as is apparent from FIG. 1, the portions where the FG potential patterns 16 and 17 are formed are fixed by grooves as in the conventional structure of FIG. The center fixing structure between them is fixed by a fitting structure formed by fitting a fitting piece 5 formed on the metal plate 2 and a fitting notch 8 formed on the printed circuit board 1. Compared to the conventional fixing structure by screwing shown in FIG. 4, there is no screw and metal plate 2 side mounting portion in the mounting area of the primary side circuit portion 14 in the printed circuit board 1 for the central fixing portion. The component mounting portion of the primary circuit section 14 on the printed circuit board 1 can be widened.

  FIG. 3 is an explanatory view of another embodiment of the fitting structure used in the present invention. In this embodiment, the difference with respect to the printed board 1 above the fitting groove 20 in the fitting piece 5 on the metal plate 2 side. A taper portion 21 is formed on the insertion side.

  By forming this tapered portion 21, when the fitting piece 5 of the metal plate 2 is inserted into the fitting notch 8 of the printed board 1 as shown by the arrow, the printed board 1 on both sides of the opening of the fitting notch 8 of the fitting groove 20 is inserted. It is possible to easily fit the side end face.

  In the embodiment described above, the metal plate 2 is attached to the printed board 1 as shown in FIG. Although the fixing structure is provided, when the size of the printed circuit board 1 in the longitudinal direction is large, the fitting fixing portions provided in the middle may be provided in a plurality of places such as two or three places.

  In this case, the fixing position to be the primary circuit part 14 may be a fixing structure by the fitting piece 5 and the fitting notch 8, and the fixing part located in the secondary circuit part 15 may be a fitting structure. However, a screwing structure may be used.

  The switching power supply device of the present invention is a single-unit switching power supply device having a structure in which the printed circuit board is directly mounted on the device to be used without housing the printed circuit board in a case. However, in the above-described embodiment, the mounting holes are omitted at appropriate positions. For example, the mounting holes are provided in, for example, four locations at positions where the FG potential patterns 16 and 17 at both ends in the left-right direction on the printed board 1 are separated.

In addition, the shape of the metal plate 2 is exemplified by a plate shape in which each part is formed at the lower end portion serving as a mounting portion and integrated on the upper side. However, depending on the required strength and requirements as a radiator, It may be bent downward to form a double structure, or may take an appropriate plate shape.

Explanatory drawing which showed embodiment of this invention Explanatory drawing which extracted and showed the fitting structure of FIG. Explanatory drawing of other embodiment of the fitting structure used by this invention Illustration of conventional structure

Explanation of symbols

1: Printed circuit board 2: Metal plate 3: Screw hole 4, 6: Mounting piece 5: Fitting piece 7, 9: Through hole 8: Fitting notch 10, 12: Screw 14: Primary circuit portion 15: Secondary Side circuit portions 16, 17: FG potential pattern 18: heating element 19: fitting portion 20: fitting groove 21: taper portion

Claims (2)

Switching comprising a printed circuit board on which a circuit component is mounted and a mounting hole for a device to be used, and a metal plate fixed to the side edge of the printed circuit board in an upright state and serving as a reinforcing plate and a radiator of the printed circuit board In the power supply,
The printed circuit board has a through hole in each of the formation positions of the frame ground potential pattern of the primary side circuit portion and the frame ground potential pattern of the secondary side circuit portion, and is rectangular at a side surface position between the through holes. Form a mating notch,
The metal plate is formed by bending a board mounting piece having a screw hole at a lower end portion corresponding to the through hole of the printed board, and forming a fitting piece at a position corresponding to the fitting notch,
The fitting piece of the metal plate extends to the lower side of the printed circuit board and has a width exceeding the notch of the printed circuit board, and the width of the notch is left on both sides of the printed circuit board. It has a fitting shape that is cut out into a rectangle,
The fitting piece of the metal plate is fitted into the fitting notch of the printed circuit board from the lateral direction, and the screw hole of the metal plate is screwed from below with the screw hole of the metal plate aligned with the through hole of the printed circuit board. A switching power supply device having a fixed structure for fixing.
  The switching power supply device according to claim 1, wherein the metal plate fitting piece and the printed board cutout are provided at a plurality of locations.

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