JP4310461B2 - Switching power supply module - Google Patents

Description

  The present invention relates to a switching power supply module provided with a switching power supply circuit having a transformer.

  FIG. 5 shows a configuration example of the switching power supply circuit. In this example, the switching power supply circuit 10 has a transformer 11, and on the primary coil N1 side of the transformer 11, input terminals + Vin, -Vin, an input filter circuit 12, a snubber circuit 13, a main switch (MOSFET) 14, and the relevant switch A control circuit 17 for controlling the main switch 14 is provided to form a primary side circuit. Further, a rectifier circuit 15, an output filter circuit 16, and output terminals + Vout and -Vout are provided on the secondary coil N2 side to form a secondary circuit. Further, the switching power supply circuit 10 is provided with a noise countermeasure capacitor 23.

  The input filter circuit 12 includes capacitors 18, 19, 20, a common mode inductor 21, and an inductor 22. The snubber circuit 13 is a circuit for protecting the main switch 14 from a surge voltage generated during a voltage fluctuation transient period, and includes a capacitor 24, a resistor 25, and a diode 26.

  The rectifier circuit 15 includes a synchronous rectifier (for example, MOSFETs) 28 and 29 and a synchronous rectifier drive circuit 30 for driving the synchronous rectifiers 28 and 29. The output filter circuit 16 includes a choke coil 32 and a capacitor 33.

  In this switching power supply circuit 10, when a DC voltage is input from the outside through input terminals + Vin and −Vin, this DC voltage is applied to the series circuit of the input filter circuit 12, the primary coil N <b> 1 of the transformer 11, and the main switch 14. To do. This DC voltage is converted to AC by the switch ON / OFF operation of the main switch 14 by the control operation of the control circuit 17, and is transmitted to the secondary circuit via the transformer 11. As a result, the AC voltage output from the transformer 11 (secondary coil N2) is rectified by the rectifier circuit 15, converted into a DC voltage by the smoothing operation of the output filter circuit 16, and output to the outside from the output terminals + Vout and -Vout. Is done.

  The value of the voltage output to the outside is detected by an output voltage detection circuit (not shown), and this detection voltage is applied to the control circuit 17 through a feedback circuit (not shown). Based on the detected voltage, the control circuit 17 performs a switching control operation of the main switch 14 by, for example, a PWM control method in order to stabilize the voltage output to the outside. This stabilizes the output voltage to the outside.

  In addition, although the prior art document was investigated, there was no appropriate prior art document.

  There is a switching power supply module in which the switching power supply circuit 10 as described above is formed in a single component form. FIG. 3 is a schematic perspective view showing an example of the appearance of the switching power supply module proposed by the present applicant.

  The switching power supply module 1 includes a substrate 2 on which a switching power supply circuit 10 is formed and a terminal 3 attached to the substrate 2. The switching power supply module 1 can be mounted on the motherboard 4 by connecting the tip of the terminal 3 to the motherboard 4, for example.

  In this switching power supply module 1, the substrate 2 is constituted by a multilayer substrate in which a plurality of conductor layers are laminated with an insulating layer interposed therebetween. Components 5 such as a capacitor component and an IC component constituting the switching power supply circuit 10 are mounted on both the front and back surfaces of the substrate 2. Further, the substrate 2 is formed with a through hole 6 penetratingly formed from the front surface side to the back surface side, an inner via hole penetratingly formed between the surface conductor layer and the inner conductor layer, or between a plurality of inner conductor layers. ing.

  Furthermore, a conductor pattern such as a wiring pattern is formed on each conductor layer of the substrate 2. FIG. 4 shows a simplified pattern configuration example of each of the conductor layers Z1 to Z4 when the substrate 2 has four conductor layers. In this example, the coil patterns 35 (35a, 35b, 35c, 35d) are arranged at the same formation position in each of the conductor layers Z1 to Z4. That is, a plurality of coil patterns 35 are stacked on the substrate 2. The laminated portions of the coil patterns 35 are sandwiched from both the upper and lower sides of the substrate 2 by a core member (for example, ferrite core) 36 that partially or wholly forms a pair (see FIG. 3). 3, only the E-shaped core member 36 disposed on the upper side of the substrate 2 among the paired core members 36 is illustrated, and the core member disposed on the lower side of the substrate 2 is the substrate 2. It is not shown in the figure because it is arranged in a shaded position. The shape of the core member disposed on the lower side of the substrate 2 may be, for example, an E shape similar to that of the core member 36 disposed on the upper side of the substrate 2 or a plate shape (I shape). There can be. Further, the substrate 2 is provided with a through hole 37 through which the core foot of the core member 36 is inserted. The core legs of the core member 36 are inserted into the through holes 37 so that the upper core member of the substrate 2 and the lower core member of the substrate 2 are in contact with each other, and the core member 36 forming a pair has a closed magnetic path. It is composed.

  Of the coil patterns 35a to 35d formed in each of the conductor layers Z1 to Z4, the coil pattern 35a of the first layer (lowermost conductor layer) and the coil pattern 35d of the fourth layer (uppermost conductor layer) are through. The primary coil N1 of the transformer 11 is configured by being connected by the hole 38a. Further, the second layer coil pattern 35b and the third layer coil pattern 35c are connected by an inner via hole 39a to constitute the secondary coil N2 of the transformer 11. That is, in this example, the transformer 11 is configured by the coil pattern 35 of each conductor layer Z1 to Z4 and the core member 36 forming a pair.

  By the way, when the transformer having the coil pattern 35 formed on the substrate 2 as described above is used as the transformer 11 constituting the switching power supply circuit 10, the following problems occur. That is, since the plurality of coil patterns 35 are arranged to face each other, a capacity is generated between the coil patterns 35, and the capacity between the coil patterns 35 is synthesized as a distributed capacity, as shown by a dotted line in FIG. It becomes a parasitic capacitance Cp. This parasitic capacitance Cp is charged and discharged according to the switching operation of the main switch 14. The charging / discharging of the parasitic capacitance Cp may cause the following problems. The problem is that the circuit portions A, B, C, and D surrounded by the chain line in the circuit diagram of FIG. 5 are designed such that the potential does not fluctuate in an alternating manner, but the parasitic capacitance Cp of the transformer 11. , The potential between the primary side circuit portion A and the secondary side circuit portion B, the potential between the primary side circuit portion A and the secondary side circuit portion D, and the primary side circuit portion C. And the potential between the circuit portion B on the secondary side and the potential between the circuit portion C on the primary side and the circuit portion D on the secondary side (that is, the potential between the primary-secondary potential stabilizing circuit portion) vary. It is a thing that ends up. Although the parasitic capacitance Cp is also generated in the wound transformer, the parasitic capacitance Cp of the transformer 11 having the coil pattern is larger than that of the wound transformer, and thus the primary due to charging / discharging of the parasitic capacitance Cp of the transformer 11 is performed. -Potential fluctuations between the secondary potential stabilization circuit portions are so large that they cannot be ignored, and may be a major cause of common mode noise. The common mode noise generated thereby propagates to the space around the switching power supply module 1 to become radiation noise, and propagates to the input line to become input feedback noise. In order to satisfy the EMI standard, it is necessary to suppress the occurrence of common mode noise.

  Therefore, in the circuit configuration shown in FIG. 5, the potential stabilization circuit portion C of the primary side circuit and the potential stabilization circuit portion B of the secondary side circuit are connected by the capacitor 23, and the transformer 11 according to the switching operation of the main switch 14. This constitutes a feedback circuit for charging and discharging current of the parasitic capacitance Cp. As a result, the potential between the primary and secondary potential stabilization circuit portions is stabilized, and the occurrence of common mode noise due to potential fluctuations between the primary and secondary potential stabilization circuit portions is suppressed.

  Such a noise countermeasure capacitor 23 connects a primary side circuit and a secondary side circuit, and is required to have a high breakdown voltage capable of withstanding a high voltage such as DC500V to 2500V in order to comply with safety standards. For this reason, the capacitor component that functions as the capacitor 23 is a large component, and the occupied area of the capacitor component on the substrate 2 is wide, and the interval between the surrounding components and the conductor pattern is also wide.

  The switching power supply module 1 is required to be miniaturized, but there is a problem that it is difficult to miniaturize such a large component. In addition, since large parts are expensive, the cost of the switching power supply module 1 is increased.

  The present invention has been made to achieve the above object, and an object of the present invention is to provide a switching power supply module that can be easily reduced in size and cost.

  In order to achieve the above object, the present invention has the following configuration as means for solving the above problems. That is, the present invention has a multilayer substrate in which four or more conductor layers are laminated with an insulating layer interposed therebetween, and has a coil pattern formed on each of the plurality of conductor layers of the multilayer substrate. A switching power supply circuit having a transformer, a primary circuit connected to a primary coil of the transformer, and a secondary circuit connected to a secondary coil of the transformer is formed on the multilayer substrate, and the switching The primary circuit of the power supply circuit is provided with a main switch for controlling the circuit operation of the entire switching power supply circuit, and the potential stabilization circuit in which the potential does not fluctuate in an alternating manner by the switching operation of the main switch in the primary circuit and the secondary circuit At least a part of the partial wiring pattern is formed on the inner conductor layer provided between the lowermost conductor layer and the uppermost conductor layer of the multilayer substrate. In addition, at least one of the inner conductor layers is formed with an electrode pattern connected to the potential stabilizing circuit portion of the primary circuit, and the potential stabilizing circuit portion of the secondary circuit is formed on another inner conductor layer. The electrode pattern to be connected to the electrode pattern is formed so that at least a part thereof faces the electrode pattern on the primary circuit side, and the electrode pattern on the primary circuit side and the electrode pattern on the secondary circuit side are between the electrode patterns. An equivalent capacitor is formed by functioning an insulating layer as a dielectric for a capacitor.

  According to the present invention, the electrode pattern on the primary circuit side and the electrode pattern on the secondary circuit side that constitute the equivalent capacitor are formed on the internal conductor layer of the multilayer substrate. While the lowermost conductor layer and the uppermost conductor layer of the multilayer substrate have a large area that is effectively used, such as multiple components are mounted or many wiring patterns connected to these components are formed, The inner conductor layer has a smaller effective area and more free space than the lowermost conductor layer and the uppermost conductor layer. In the present invention, an equivalent capacitor electrode pattern can be formed without increasing the size of the switching power supply module by effectively utilizing an empty space that has not been used so far in the inner conductor layer to form an equivalent capacitor electrode pattern. A pattern can be provided.

  In addition, since the electrode pattern of the equivalent capacitor can be produced only by changing the shape of the conductor pattern formed on the internal conductor layer, an increase in manufacturing cost due to an increase in manufacturing steps can be prevented.

  Further, by providing a configuration for causing an equivalent capacitor to function as a noise countermeasure capacitor, the following effects can be obtained. That is, since a noise countermeasure capacitor having an electrode connected to the primary circuit and an electrode connected to the secondary circuit is required to have a high breakdown voltage, the capacitor component becomes large. When this large capacitor component is mounted on the front or back surface of the board, a large mounting area is required on the front or back surface of the capacitor component, and the capacitor component and its peripheral components and A wide space between the conductor pattern is required. On the other hand, in the present invention, instead of a noise countermeasure capacitor component, a noise countermeasure capacitor is constituted by an equivalent capacitor composed of an electrode pattern, and the noise countermeasure capacitor (equivalent capacitor) The electrode pattern is formed in the portion of the inner conductor layer of the multilayer substrate that has been a dead space until now. As a result, the switching power supply module can be reduced in size because it is not necessary to provide a large component with a high withstand voltage on the front surface or the back surface of the substrate. In addition, the number of components of the switching power supply module can be reduced, and the component cost can be reduced.

  By having such a configuration, the primary-secondary potential stabilization circuit portion of the switching power supply circuit is reduced by a noise countermeasure capacitor (equivalent capacitor) while suppressing an increase in the size and cost of the switching power supply module. Thus, an effect that input feedback noise and radiation noise caused by potential fluctuation between the primary and secondary potential stabilizing circuit portions can be suppressed can be obtained.

  In addition, according to the present invention, at least a part of the wiring pattern of the potential stabilization circuit portion in the switching power supply circuit is formed on the inner conductor layer of the multilayer substrate, and the wiring pattern of the potential stabilization circuit portion formed on the inner conductor layer is reduced. By making at least a part of the wide wiring pattern, effectively using the former dead space of the inner conductor layer of the multilayer substrate, and forming the wide wiring pattern to prevent the switching power supply module from becoming large, For example, in a state where the switching power supply module of the present invention is mounted on a mother board, the capacitance between the wiring pattern of the potential stabilization circuit portion of the switching power supply circuit and the ground can be increased. Since the potential stability of the potential stabilization circuit portion increases as the capacitance with the ground increases, the potential stability of the potential stabilization circuit portion is improved by providing this configuration, and the primary-secondary potential stabilization. For example, occurrence of common mode noise caused by potential fluctuation between circuit portions can be suppressed to a small level. As a result, even if the capacitance (capacitance of the capacitor for noise suppression) provided between the primary and secondary potential stabilization circuit portions is small, an effect of enabling noise suppression can be achieved.

  Embodiments according to the present invention will be described below with reference to the drawings.

  Similar to the switching power supply module 1 of FIG. 3, the switching power supply module of this embodiment is configured to include a substrate 2 that is a multilayer substrate and a plurality of terminals 3. A switching power supply circuit 10 as shown is formed. Since the configuration of the switching power supply circuit 10 shown in FIG. 5 has been described above, a duplicate description thereof will be omitted.

  In this embodiment, the substrate 2 has a multilayer structure in which four conductor layers Z1 to Z4 are laminated with an insulating layer interposed therebetween. Components 5 are provided on both the front and back surfaces of the substrate 2, and conductor patterns such as wiring patterns are formed on the conductor layers Z1 to Z4.

  In this embodiment, the insulating layers between the conductor layers Z1 to Z4 are each made of the same insulating material (for example, glass epoxy resin). For example, the conductor patterns of the conductor layers Z1 to Z4 can be insulated (for example, the conductor pattern formed on the conductor layer Z2 is insulated from the conductor pattern formed on the conductor layer Z3 (for example, The thickness of the insulating layer between the conductor layers Z1 to Z4, the insulating material constituting the insulating layer, and the like are set so that the high withstand voltage of DC 2500V can be obtained. In addition, all the insulating layers between each conductor layer Z1-Z4 may be comprised with the same insulating material, and each of those insulating layers may be comprised with the mutually different insulating material. Further, an insulating layer functioning as a dielectric of an equivalent capacitor described later (in this embodiment, an insulating layer between the conductor layers Z2 and Z3) is made of an insulating material having a high dielectric constant, and the other insulating layers are low dielectric. It is good also as a structure comprised with an insulating material of a rate.

  FIG. 1 shows a simplified pattern configuration example of each of the conductor layers Z1 to Z4 of the substrate 2 in this embodiment. In this embodiment example, each of the conductor layers Z1 to Z4 is formed with a coil pattern 35 (35a to 35d) constituting the transformer 11 as in the configuration of FIG. 4 described above. The coil pattern 35a of the conductor layer Z1 and the coil pattern 35d of the fourth conductor layer Z4 are connected via a through hole 38a to constitute the primary coil N1. The coil pattern 35b of the second conductor layer Z2 and the coil pattern 35c of the third conductor layer Z3 are connected via an inner via hole 39a to constitute a secondary coil N2. That is, in this embodiment, the secondary coil N2 has a sandwich structure sandwiched between the coil patterns 35a and 35d constituting the primary coil N1. By adopting this structure, the degree of coupling between the primary coil N1 and the secondary coil N2 can be improved.

  In this embodiment, the second conductor layer Z2, which is the inner conductor layer of the substrate 2, has a capacitor conductor pattern (electrode pattern) 7a formed on one side of a pair of electrodes constituting the noise countermeasure capacitor 23. Is formed. The capacitor conductor pattern 7a is connected to one end side of the coil pattern 35b (that is, one end side (secondary side circuit) of the secondary coil N2). In addition, the third conductor layer Z3, which is the internal conductor layer of the substrate 2, has a capacitor conductor pattern (electrode pattern) 7b formed on the other electrode of the noise countermeasure capacitor 23 via the conductor layer Z3. It is formed at a position facing the capacitor conductive pattern 7a. The capacitor conductor pattern 7b is connected to a wiring pattern 42b formed in the conductor layer Z4 by a connection means (not shown), and is connected to one end side of the coil pattern 35d (that is, the primary coil N1) via the wiring pattern 42b. One end side (primary side circuit)).

  In this embodiment, as described above, the capacitor conductor pattern (electrode pattern) 7a, 7b that forms a pair and the insulating layer (dielectric) between the capacitor conductor patterns 7a, 7b are used as the noise countermeasure capacitor 23. A functional equivalent capacitor is constructed. The noise countermeasure capacitor (equivalent capacitor) 23 has high withstand voltage by the insulating layer having high withstand voltage as described above.

  Furthermore, in this embodiment, one end side (one end side of the secondary coil N2) of the coil pattern 35b to which the capacitor conductor pattern 7a is connected in the second conductor layer Z2 is connected to the capacitor conductor pattern 7a. In addition to being connected, it is also connected to the wiring pattern 42a. A part of the wiring pattern 42a is formed as a wide wiring pattern W. The wiring pattern 42a is connected to the conductor pattern functioning as the output terminal + Vout through the through hole 38b. That is, the wiring pattern 42 a is the wiring pattern of the potential stabilization circuit portion B in the secondary circuit of the switching power supply circuit 10.

  The wiring pattern 42b formed in the fourth conductor layer Z4 constitutes the wiring pattern of the potential stabilization circuit portion C of the primary side circuit. In this embodiment, this wiring pattern 42b is also a wiring pattern. Similar to the pattern 42 a, a part of the pattern 42 a is a wide wiring pattern W.

  Furthermore, a wiring pattern 42c is formed on the third conductor layer Z3. The wiring pattern 42c is connected to a conductor pattern functioning as the output terminal -Vout through the through hole 38c, and the wiring pattern 42c is a wiring pattern of the potential stabilization circuit portion D of the secondary side circuit. A part of the wiring pattern 42c is formed as a wide wiring pattern W.

  In this embodiment, a part of each of the wiring pattern 42b of the potential stabilization circuit portion A of the primary side circuit and the wiring patterns 42a and 42c of the potential stabilization circuit portions B and D of the secondary side circuit is the wide wiring pattern W. Therefore, the stability of the potential between the potential stabilization circuit portion and the capacitor can be improved. Thereby, the capacity | capacitance of the capacitor | condenser 23 for noise countermeasures can be made small.

  In this embodiment, the wide wiring pattern W of each of the wiring patterns 42a and 42c is formed on the inner conductor layers Z2 and Z3 of the multilayer substrate 2, respectively. Furthermore, capacitor conductor patterns 7a and 7b constituting the electrodes of the noise countermeasure capacitor 23 are also formed on the inner conductor layers Z2 and Z3, respectively. As a result, the portions of the inner conductor layers Z2 and Z3 that have been dead spaces can be used effectively, and waste can be reduced. Further, by adopting a configuration in which the noise countermeasure capacitor 23 is formed inside the substrate 2, it is possible to reduce the number of components because the noise countermeasure capacitor component can be omitted. Furthermore, since it is not necessary to provide a large component with a high breakdown voltage, it is easy to reduce the size of the switching power supply module 1.

  In addition, this invention is not limited to the form of this embodiment, Various embodiment can be taken. For example, in this embodiment, an example in which the noise countermeasure capacitor 23 is formed inside the substrate 2 is shown. However, in addition to the configuration, for example, the capacitor 24 for the snubber circuit 13 also has a noise countermeasure capacitor. Similarly to 23, it may be formed inside the substrate 2. In other words, a pair of capacitor conductor patterns may be disposed on each of the inner conductor layers Z2 and Z3 of the substrate 2 so as to face each other, and the capacitor 24 may be configured by the capacitor conductor patterns forming the pair. Since the capacitor 24 of the snubber circuit 13 requires a withstand voltage of, for example, DC 200V to 250V, the component of the capacitor 24 is large. Therefore, instead of the large component, the capacitor 24 is placed inside the substrate 2. Thus, the switching power supply module 1 can be more easily downsized.

  As described above, capacitors and inductors other than the noise countermeasure capacitor 23 may also be configured by the conductor pattern of the inner conductor layer.

  Furthermore, instead of the configuration of FIG. 1, a configuration as shown in FIG. 2 may be adopted. In the example of FIG. 2, in the second conductor layer Z2, the electrode pattern constituting the capacitor conductor pattern 7a extends from the area facing the capacitor conductor pattern 7b to the outside of the area. The electrode pattern portion extending outward is configured to function as a wide wiring pattern 42a. Also in the third conductor layer Z3, the electrode pattern constituting the capacitor conductor pattern 7b extends from the region facing the capacitor conductor pattern 7a to the outside of the region. Consists of composition. The electrode pattern portion 44 extending to the outside serves as a portion (capacitance-providing portion between the grounds) for applying the capacitance between the ground to the potential stabilizing circuit portion B of the primary circuit, and the potential stabilizing circuit portion B The potential stability of can be improved.

  Furthermore, in this embodiment, only one part of the wiring pattern of the potential stabilization circuit portion is a wide wiring pattern. For example, wide parts are arranged at intervals in a plurality of places in the same wiring pattern. It is good also as composition which has.

  Furthermore, in this embodiment, the substrate 2 has four conductor layers, but the substrate 2 may have five or more conductor layers. In this case, since the number of internal conductor layers is increased, it is possible to form a wider electrode pattern constituting the capacitor, and there is an advantage that it is easy to increase the capacitance of the capacitor.

  Further, in this embodiment, the noise countermeasure capacitor 23 is provided so as to connect the potential stabilizing circuit portion C of the primary side circuit and the potential stabilizing circuit portion B of the secondary side circuit. The countermeasure capacitor 23 may be provided so as to connect the potential stabilizing circuit portion of the primary side circuit and the potential stabilization circuit portion of the secondary side circuit. For example, the capacitor 23 for noise countermeasure is provided in the primary side circuit. The potential stabilization circuit portion A and the potential stabilization circuit portion B of the secondary side circuit may be connected to each other, or the potential stabilization circuit portion C of the primary side circuit and the potential stabilization circuit portion D of the secondary side circuit may be provided. And may be provided so as to be connected to each other. In each of the potential stabilization circuit portion of the primary side circuit and the potential stabilization circuit portion of the secondary side circuit, at which location the capacitor 23 (capacitor conductor patterns 7a and 7b) for noise suppression is connected is, for example, It is designed appropriately in consideration of the arrangement configuration of conductor patterns formed in the conductor layers Z2 and Z3, the formation positions of through holes and inner via holes, and the like. Further, the formation position of the wide wiring pattern W in the circuit stabilizing circuit portion is also designed as appropriate.

  Furthermore, as the switching power supply circuit provided in the switching power supply module 1, the circuit configuration example illustrated in FIG. 5 is shown, but the configuration of the switching power supply circuit provided on the substrate 2 of the switching power supply module 1 is limited to the configuration in FIG. 5. It is not a thing. Furthermore, the shape of the terminal 3 is not limited to the example of FIG. 3, and can take other shapes. The number of terminals 3 attached to the substrate 2 is also set as appropriate and is not particularly limited.

It is a figure for demonstrating the switching power supply module which concerns on this invention. It is a model figure for demonstrating other example embodiments. It is the model figure which showed the example of 1 external appearance of the switching power supply module. It is a model figure which shows typically the example of a pattern structure of each conductor layer of the multilayer substrate which comprises a switching power supply module. It is a circuit diagram which shows simply an example of the switching power supply circuit formed in a switching power supply module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Switching power supply module 2 Board | substrate 7a, 7b Conductor pattern for capacitor | condenser 23 Capacitor for noise measures 42 Wiring pattern W Wide wiring pattern

Claims (3)

  A transformer having a multilayer substrate in which four or more conductor layers are laminated with an insulating layer interposed therebetween, and having coil patterns respectively formed on a plurality of conductor layers of the multilayer substrate; and A switching power supply circuit having a primary circuit connected to the primary coil of the transformer and a secondary circuit connected to the secondary coil of the transformer is formed on the multilayer substrate, and the primary circuit of the switching power supply circuit Is provided with a main switch for controlling the circuit operation of the entire switching power supply circuit, and at least a wiring pattern of a potential stabilization circuit portion in which the potential does not fluctuate in an alternating manner by the switching operation of the main switch in the primary side circuit and the secondary side circuit A part of the multilayer substrate has a structure formed in an inner conductor layer provided between a lowermost conductor layer and an uppermost conductor layer of the multilayer substrate, At least one of the body layers is formed with an electrode pattern connected to the potential stabilization circuit portion of the primary side circuit, and at least a part of the electrode pattern connected to the potential stabilization circuit portion of the secondary side circuit is formed on another internal conductor layer. Are opposed to the primary circuit side electrode pattern, and the primary circuit side electrode pattern and the secondary circuit side electrode pattern include a dielectric for a capacitor as an insulating layer between the electrode patterns. A switching power supply module characterized in that an equivalent capacitor is configured by functioning as   An equivalent capacitor having an electrode pattern on the primary circuit side and an electrode pattern on the secondary circuit side is designed to reduce potential fluctuations between the potential stabilization circuit portion of the primary circuit and the potential stabilization circuit portion of the secondary circuit. The switching power supply module according to claim 1, wherein the switching power supply module functions as a noise countermeasure capacitor for suppressing noise generation caused by the potential fluctuation.   3. The insulating layer between the electrode pattern on the primary side circuit side and the electrode pattern on the secondary side circuit side, the entire layer is made of the same insulating material. The switching power supply module described.

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