Control device

Abstract

To provide a control device including a printed wiring board in consideration of heat radiation of a power supply IC.SOLUTION: In the control device 60, the transformer 41 is mounted on the first surface 51a of the printed wiring board 51 with the heat dissipation space 450 formed between the transformer 41 and the first surface 51a. Further, the power source IC43 is mounted on the second surface 51b of the printed wiring board 51 so as to face at least a part of the transformer 41. The printed wiring board 51 has a plurality of vent holes 511 communicating with the heat dissipation space 450 at a position facing the transformer 41 and a position facing the power source side IC43.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] This relates to a control device equipped with a switching power supply circuit. [Background technology]

[0002] Conventionally, efforts have been made to reduce the mounting area of ​​switching power supply circuits in order to make printed wiring boards smaller and more dense. For example, in the power conversion device described in Patent Document 1 (WO2015-053142), a transformer and a power supply IC for power supply control are mounted facing each other across a printed wiring board, thereby reducing the mounting area. Summary of the Invention [Problem to be solved by the invention]

[0003] However, while Patent Document 1 provides ample space around the power supply IC, allowing the power supply IC to dissipate heat even when it heats up, some devices may have a mounting plate for mounting a printed wiring board near the power supply IC, which may prevent the power supply IC from dissipating heat. Therefore, there is a demand for a control device equipped with a printed wiring board that takes into account the heat dissipation of the power supply IC. [Means for solving the problem]

[0004] A control device according to a first aspect includes a printed wiring board, a mounting plate, a switching transformer, and a switching power supply IC. The printed wiring board has a first surface and a second surface opposite the first surface. The mounting plate has the printed wiring board attached thereto and faces the second surface of the printed wiring board. The switching transformer is mounted on the first surface, forming a predetermined space between the mounting plate and the first surface. The switching power supply IC is mounted on the second surface so as to face at least a portion of the switching transformer, and controls the current input to the switching transformer. The printed wiring board has a plurality of holes that lead to the predetermined space at locations facing the switching transformer and the switching power supply IC.

[0005] In this control device, the switching transformer and switching power supply IC are placed opposite each other with the printed circuit board in between, which allows for a smaller and more densely packed printed circuit board. When this is done, the heat generated by the switching power supply IC causes the ambient temperature to rise, but the heated air flows through multiple holes into a designated space on the switching transformer side. As a result, excessive temperature rises around the switching power supply IC are suppressed, and the temperature rise of the switching power supply IC is also suppressed.

[0006] A control device according to a second aspect is the control device according to the first aspect, wherein the plurality of holes include through holes that electrically connect a predetermined first conductive pattern on the first surface and a predetermined second conductive pattern on the second surface.

[0007] In this control device, the through holes are not only used as holes for air circulation, but also to conduct heat from the second surface side to the first surface side via the through holes, thereby suppressing the temperature rise of the switching power supply IC.

[0008] A control device according to a third aspect is the control device according to the first or second aspect, further comprising a base, the base being disposed between the core of the switching transformer and the first surface of the printed wiring board to form a predetermined space.

[0009] In this control device, the height dimension of the base from the first surface of the printed wiring board is adjusted to adjust the specified space to a size suitable for the diffusion of air passing through the holes from the second surface side.

[0010] A control device according to a fourth aspect is the control device according to the third aspect, wherein the height of the base is set so that the shortest distance from the first surface of the printed wiring board to the lowest point of the switching transformer is 5 mm or more and 10 mm or less.

[0011] A control device according to a fifth aspect is the control device according to any one of the first aspect to the fourth aspect, in which the number of holes is 4 to 14.

[0012] A control device according to a sixth aspect is the control device according to any one of the first to fifth aspects, wherein the switching power supply IC is a rectangular package incorporating a switching element and a control IC, and lead terminals of the switching power supply IC are arranged along the short sides of the package.

[0013] In this control device, the switching power supply IC is placed across the insulating area between the primary and secondary circuits of the switching power supply circuit equipped with a switching transformer, with one lead terminal of the switching power supply IC connected to the primary circuit and the other lead terminal of the switching power supply IC connected to the secondary circuit. Therefore, it is advantageous to place the terminals of the switching power supply IC along the short side of the package. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2 is a circuit diagram of a switching power supply circuit of a control device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a perspective view of the periphery of a transformer mounted on a printed wiring board of a control device. [Figure 3] 1 is a plan view of a portion of a second surface of a printed wiring board, on which a power supply IC is mounted, the second surface being opposite to the first surface on which a transformer is mounted. [Figure 4] FIG. 2 is a partial cross-sectional side view of a printed wiring board on which a transformer and a power supply IC are mounted. DETAILED DESCRIPTION OF THE INVENTION

[0015] (1) Overview of the switching power supply circuit 30 of the control device 60 1 is a circuit diagram of a switching power supply circuit 30 of a control device 60 according to an embodiment of the present disclosure. In FIG. 1, the control device 60 is used in, for example, an outdoor unit or an indoor unit of an air conditioner. The switching power supply circuit 30 generates a control voltage for the control device 60.

[0016] The transformer 41 is a switching transformer and has a primary winding 41f and a secondary winding 41s. Here, a circuit connected to the primary winding 41f is referred to as a primary-side circuit 31, and a circuit connected to the secondary winding 41s is referred to as a secondary-side circuit 32.

[0017] (1-1) Primary side circuit 31 A DC voltage Vdc is supplied to a primary winding 41f of the transformer 41. The DC voltage Vdc is obtained by full-wave rectifying a commercial AC voltage and smoothing it with an electrolytic capacitor 2. A switching element 4 is connected in series to the primary winding 41f. A resonance capacitor 3 is connected in parallel between the output terminals (collector-emitter) of the switching element 4.

[0018] A control IC 5 is connected to the base of the switching element 4, and further connected to the output circuit of a photocoupler 6. The control IC 5 controls the switching element 4 so that the period during which the switching element 4 is on becomes shorter as the output current of the photocoupler 6 increases, and the period during which the switching element 4 is on becomes longer as the output current of the photocoupler 6 decreases. The switching element 4 and the control IC 5 form a packaged switching power supply IC, hereinafter referred to as a power supply IC 43.

[0019] (1-2) Secondary circuit 32 The voltage generated in the secondary winding 41s of the transformer 41 is supplied to the electrolytic capacitor 9 via the diode 8 and smoothed by the electrolytic capacitor 9. The smoothed output voltage is provided to an electronic device such as a microcomputer 13 as a DC voltage Vcc for control.

[0020] The output voltage is also applied to the series circuit of the input circuit of the photocoupler 6 and resistor 10, causing a current to flow through the input circuit (light-emitting diode) of the photocoupler 6. At this time, the current flowing through the photocoupler 6 increases or decreases in accordance with the increase or decrease in the output voltage.

[0021] Specifically, when the output voltage becomes higher than a predetermined reference value of Vcc, the current flowing through the input circuit and output circuit of the photocoupler 6 increases relatively, and the control IC 5 of the power supply IC 43 operates to shorten the period during which the switching element 4 is turned on.

[0022] As a result, the output voltage drops. Conversely, when the output voltage drops below the reference value, the current flowing through the input and output circuits of the photocoupler 6 decreases relatively, causing the control IC 5 of the power supply IC 43 to extend the period during which the switching element 4 is on. As a result, the output voltage rises. This feedback action keeps the output voltage constant.

[0023] Furthermore, an abnormal voltage absorbing capacitor 11 and a resistor 12 are connected in parallel to the input circuit of the photocoupler 6. Resistor 12, together with resistor 10, divides the output voltage and regulates the voltage applied to the input circuit of the photocoupler 6 so that it does not exceed the allowable range.

[0024] Abnormal voltage absorption capacitor 11 absorbs surge noise caused by switching and external noise. For this reason, a ceramic capacitor is used for abnormal voltage absorption capacitor 11, as it has excellent response to high-frequency components of surge noise caused by switching and external noise. The external noise comes from, for example, an inverter circuit (not shown) controlled by microcomputer 13.

[0025] Here, the switching power supply circuit 30 including the photocoupler 6 is described as an example, but the present invention is not limited to this and may be a switching power supply circuit equipped with a power supply IC that employs technology that eliminates the need for a photocoupler.

[0026] (2) Mounting state of transformer 41 and power supply IC Fig. 2 is a perspective view of the vicinity of transformer 41 mounted on printed wiring board 51 of control device 60. Fig. 3 is a plan view of a portion of second surface 51b of printed wiring board 51, opposite first surface 51a on which transformer 41 is mounted, on which power supply IC 43 is mounted. Fig. 4 is a partial cross-sectional side view of printed wiring board 51 on which transformer 41 and power supply IC 43 are mounted.

[0027] (2-1) Printed wiring board 51 2 to 4, the printed wiring board 51 has an insulating base material 50 and a conductor layer formed on one first surface 51a of the base material 50. The conductor layer forms a conductive pattern including a 1-A conductive pattern 51aa and a 1-B conductive pattern 51ab. The conductor layer is covered with an insulating film (not shown). The transformer 41 is mounted on the first surface 51a of the printed wiring board 51.

[0028] The printed wiring board 51 further includes a conductor layer formed on the other second surface 51b of the base material 50. The conductor layer forms a conductive pattern including a 2-A conductive pattern 51ba and a 2-B conductive pattern 51bb. The conductor layer is covered with an insulating film (not shown). The power supply IC 43 is mounted on the second surface 51b of the printed wiring board 51.

[0029] 1 are formed on a first surface 51a and a second surface 51b of the printed wiring board 51. An insulating region 33 is provided between the primary circuit 31 and the secondary circuit 32.

[0030] The 1-A conductive pattern 51aa on the first surface 51a is connected to the 2-A conductive pattern 51ba on the second surface 51b by a through-hole. Similarly, the 1-B conductive pattern 51ab on the first surface 51a is connected to the 2-B conductive pattern 51bb on the second surface 51b by a through-hole. A through-hole is a conductive hole-shaped wiring that penetrates the printed wiring board 51.

[0031] (2-2) Mounting state of transformer 41 On the first surface 51a, the transformer 41 is arranged so as to straddle the insulating region 33, with the primary side terminal 411 connected to the 1-A conductive pattern 51aa and the 2-A conductive pattern 51ba of the primary side circuit 31, and the secondary side terminal 412 connected to the 1-B conductive pattern 51ab and the 2-B conductive pattern 51bb of the secondary side circuit 32.

[0032] The transformer 41 is mounted on the first surface 51a with the base 45 sandwiched between the transformer 41 and the first surface 51a. Therefore, a space is formed between the transformer 41 and the first surface 51a by the base 45.

[0033] (2-3) Power supply IC mounting status On the second surface 51b, the power supply IC 43 is arranged so as to straddle the insulating region 33, with the primary side terminal 43a connected to the 2-A conductive pattern 51ba of the primary side circuit 31 and the secondary side terminal 43b connected to the 2-B conductive pattern 51bb of the secondary side circuit 32.

[0034] 3 indicates the size of the projected area of ​​the transformer 41 mounted on the first surface 51a. The power supply IC 43 is contained within the thick rectangular frame, contributing to the miniaturization and high density of the printed wiring board 51. However, the power supply IC 43 does not need to be contained entirely within the thick rectangular frame; it may be that it only partially overlaps it.

[0035] (3) Heat dissipation measures for power supply IC43 4, the printed wiring board 51 is attached so that the second surface 51b on which the power supply IC 43 is mounted faces the attachment plate 57. Therefore, heat generated from the power supply IC 43 tends to be trapped between the second surface 51b and the attachment plate 57. The attachment plate 57 is, for example, a plate-like member that forms the outer casing of an electrical component box of an air conditioner.

[0036] Generally, measures are taken to improve thermal conductivity and heat dissipation by increasing the area of ​​the 2-A conductive pattern 51ba connected to the primary terminal 43a of the power supply IC 43 and the 2-B conductive pattern 51bb connected to the secondary terminal 43b.

[0037] In the control device 60 of this embodiment, in addition to the above measures, a heat dissipation space 450 is formed between the first surface 51a of the printed wiring board 51 and the transformer 41, and a plurality of ventilation holes 511 are provided that extend from the second surface 51b facing the power supply IC 43 through the printed wiring board 51 and communicate with the heat dissipation space 450. Some or all of the plurality of ventilation holes 511 may be through-holes.

[0038] (3-1) Heat radiation space 450 The heat dissipation space 450 is formed by two pedestals 45. As shown in Fig. 4, the pedestal 45 has a support portion 45a that receives the end of the core 41a and a leg portion 45b that holds the support portion 45a.

[0039] In addition, the base 45 holds the primary terminal 411 and the secondary terminal 412 of the transformer 41, and the primary terminal 411 and the secondary terminal 412 are soldered to the printed wiring board 51, thereby fixing the transformer 41 and the base 45 to the printed wiring board 51.

[0040] The heat dissipation space 450 is the gap between the first surface 51a and the lower end of the winding 41b of the transformer 41, but by adjusting the height from the first surface 51a to the top of the base 45 (height H of the base 45), it can be adjusted to a space of a size suitable for air diffusion.

[0041] (3-2) Setting the height of the base 45 The height H of the base 45 is the sum of a first distance D1, which is the shortest distance between the core 41a and the lead wire 41w extending outward from the insulating tape 41c of the winding 41b, and a second distance D2, which is the height required to form the primary side terminal 411 and the secondary side terminal 412.

[0042] The first distance D1 is set to satisfy the creepage distance of 4 mm or more and the spatial distance of 3 mm or more so as to ensure an insulation distance between the lead wire 41w and the core 41a.

[0043] Furthermore, third distance D3, which is the shortest distance from first surface 51a of printed wiring board 51 to the lowest point of winding 41b, can be increased or decreased by adjusting second distance D2. Taking into account the distance between control device 60 and surrounding structures, third distance D3 is preferably 5 mm or more and 10 mm or less.

[0044] (3-3) Ventilation hole 511 As shown in Figures 2 and 4, the multiple ventilation holes 511 not only penetrate the printed wiring board 51 but also lead to the heat dissipation space 450, thereby allowing the heat generated by the power supply IC 43 to be guided to the heat dissipation space 450.

[0045] In this embodiment, the vent holes 511 also penetrate the 1-A conductive pattern 51aa on the first surface 51a and the 2-A conductive pattern 51ba on the second surface, and all the vent holes 511 may be through holes.

[0046] In this case, the through holes not only function as ventilation holes 511 but also function as thermal conductors that transfer heat from the second surface 51b to the first surface 51a, thereby suppressing the temperature rise of the power supply IC 43.

[0047] The effect of suppressing the temperature rise of the power supply IC 43 appears from four vent holes 511 and saturates with 14 or more vent holes 511. Therefore, it is preferable to set the number of vent holes 511 to 4 or more and 14 or less.

[0048] (4) Insulation distance of insulation area 33 In the switching power supply circuit 30, the insulation distances between the primary circuit 31 and the secondary circuit 32, ie, the "creepage insulation distance D4" and the "air insulation distance D5" shown in FIG. 4, must satisfy standard values.

[0049] The creepage insulation distance D4 is the horizontal distance of the insulation region 33 that separates the primary circuit 31 and the secondary circuit 32. The spatial insulation distance D5 is the shortest distance between the 1-A conductive pattern 51aa of the primary circuit 31 and the lead wire 41w.

[0050] In this embodiment, the creepage insulation distance D4 is set to be equal to or greater than the value (unit: mm) obtained by multiplying the peak value of the operating voltage by 0.0027 and adding 0.3412 to the result.

[0051] The insulation distance D5 of the space may be 2.5 mm or more.

[0052] (5) Features (5-1) In the control device 60, the transformer 41 is mounted on the first surface 51a of the printed wiring board 51, forming a heat dissipation space 450 between the transformer 41 and the first surface 51a of the printed wiring board 51. The power supply IC 43 is mounted on the second surface 51b of the printed wiring board 51 so as to face at least a part of the transformer 41. The printed wiring board 51 has a plurality of vent holes 511 that communicate with the heat dissipation space 450 at a location facing the transformer 41 and a location facing the power supply IC 43.

[0053] As described above, in control device 60, transformer 41 and power supply IC 43 are arranged opposite each other with printed wiring board 51 in between, thereby realizing a compact and high-density printed wiring board 51. At this time, heat generated by power supply IC 43 causes the ambient temperature to rise, but air flows through vent hole 511 into heat dissipation space 450 on the transformer 41 side, thereby suppressing an excessive rise in temperature around power supply IC 43.

[0054] (5-2) The plurality of ventilation holes 511 include through holes that electrically connect the 1-A conductive pattern 51aa on the first surface 51a and the 2-A conductive pattern 51ba on the second surface 51b.

[0055] In the control device 60, the through holes are used as air vents 511, thereby suppressing a temperature rise in the power supply IC 43. In addition, heat on the second surface 51b side is conducted to the first surface 51a side via the through holes, thereby further suppressing a temperature rise in the power supply IC 43.

[0056] (5-3) In the control device 60, the pedestal 45 is disposed between the core 41a of the transformer 41 and the first surface 51a of the printed wiring board 51, thereby forming the heat dissipation space 450. By adjusting the dimension of the height H of the pedestal 45 from the first surface 51a of the printed wiring board 51, the heat dissipation space 450 can be adjusted to a space of a size suitable for the diffusion of air passing through the ventilation holes 511 from the second surface 51b side.

[0057] (5-4) In the control device 60, the height H of the base 45 is set so that the shortest distance from the first surface 51a of the printed wiring board 51 to the lowest point of the transformer 41 is 5 mm or more and 10 mm or less.

[0058] (5-5) The number of ventilation holes 511 is 4 or more and 14 or less.

[0059] (6) Other The power supply IC 43 is a rectangular package incorporating the switching element 4 and the control IC 5. The power supply IC 43 of this embodiment is a square package in plan view, but is not limited to this and may be a rectangular package in plan view.

[0060] In the case of a rectangular package, the terminals are arranged along the short sides of the package. In this case, the power supply IC 43 is arranged to straddle the insulating region 33 between the primary circuit 31 and the secondary circuit 32 of the switching power supply circuit 30, with one primary terminal 43a of the power supply IC 43 connected to the primary circuit 31 and the other secondary terminal 43b of the power supply IC 43 connected to the secondary circuit 32.

[0061] Therefore, arranging the terminals of the power supply IC 43 along the short sides of the package is advantageous in terms of being able to straddle a wider insulating area and increasing the insulation distance.

[0062] Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as defined in the claims. [Explanation of symbols]

[0063] 4 Switching elements 5 Control IC 41 Transformer (switching transformer) 41a Core 43 Power Supply IC (Switching Power Supply IC) 43a Primary terminal (lead terminal) 43b Secondary terminal (lead terminal) 45 pedestal 51 Printed wiring board 51a 1st page 51aa 1-A conductive pattern (first conductive pattern) 51b 2nd side 51ba 2-A conductive pattern (2nd conductive pattern) 57 Mounting plate 60 Control device 450 Heat dissipation space (designated space) 511 Ventilation hole (hole) [Prior art documents] [Patent documents]

[0064] [Patent Document 1] WO2015-053142

Claims

1. a printed wiring board (51) having a first surface (51a) and a second surface (51b) opposite to the first surface (51a); a mounting plate (57) to which the printed wiring board (51) is attached and which faces the second surface (51b) of the printed wiring board (51); a switching transformer (41) mounted on the first surface (51a) with a predetermined space (450) formed between the first surface (51a) and the switching transformer (41); a switching power supply IC (43) mounted on the second surface (51b) so as to face at least a part of the switching transformer (41) and controlling a current input to the switching transformer (41); Equipped with The printed wiring board (51) has a plurality of holes (511) that communicate with the predetermined space (450) at a location facing the switching transformer (41) and a location facing the switching power supply IC (43). A control device (60).

2. The plurality of holes (511) include through holes that electrically connect a predetermined first conductive pattern (51aa) on the first surface (51a) and a predetermined second conductive pattern (51ba) on the second surface (51b). The control device (60) of claim 1.

3. The semiconductor device further includes a base (45) that is disposed between the core (41 a) of the switching transformer (41) and the first surface (51 a) of the printed wiring board (51) to form the predetermined space (450). A control device (60) according to claim 1 or claim 2.

4. the shortest distance from the first surface (51a) of the printed wiring board (51) to the lowest point of the switching transformer (41) is 5 mm or more and 10 mm or less; The control device (60) of claim 3.

5. The number of the holes (511) is 4 or more and 14 or less. A control device (60) according to claim 1 or claim 2.

6. The switching power supply IC (43) is a rectangular package incorporating a switching element (4) and a control IC (5), The lead terminals (43a, 43b) of the switching power supply IC (43) are arranged along the short sides of the package. A control device (60) according to claim 1 or claim 2.

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