Circuit board for high frequency induction heating device

Abstract

To appropriately perform soldering to a through hole in soldering using a high-frequency induction heating device for performing heating while a terminal of an electronic component is sandwiched with a magnetic gap.SOLUTION: With a circuit board for a high-frequency induction heating device, in a surface side pad of a circuit board 60, at a portion orthogonal to a magnetic gap 27 direction of the high-frequency induction heating device, an area where current density is high is formed, generation of heat of the surface side pad portion is transmitted to a back surface side pad via a via hole 66, and temperature of the back surface side pad near a through-hole 62 and in the through-hole is raised. Thereby, it becomes possible to prevent deterioration in solder quality and increase in soldering time. By transmitting heat of a via-hole 62 portion of the surface side pad portion to the back surface side pad via the via hole 66, abnormally high temperature of a via-hole area 66 portion of the surface side pad can be avoided and damage to the circuit board 60 can also be prevented.SELECTED DRAWING: Figure 30

Description

[Technical Field]

[0001] The present invention relates to a circuit board for a high-frequency induction heating device. [Background technology]

[0002] For example, as shown in Patent Document 1, a high-frequency induction heating device is used to solder electronic components to pads on a circuit board. That is, this type of high-frequency induction heating device is configured to include a high-frequency induction heating head that solders the terminals of electronic components to the pad portions of the circuit board, and a solder supply means that supplies solder to the pad portions. The high frequency induction heating head has a core body having a magnetic gap, a coil for supplying magnetic flux to the core body, and control means for controlling the supply of current to the coil. When using this high-frequency induction heating device to solder the terminals of an electronic component to the pads of a circuit board, first the magnetic gap of the high-frequency induction heating head is moved to the pads, and the pads and the terminals of the electronic components are heated to a temperature above the melting point of the solder. Next, solder is supplied to the magnetic gap from a solder supply means to semi-melt the solder, and the semi-melted solder is then pressed against the pads and terminals. In this state, the pads, terminals and solder are heated to melt the solder and complete the soldering. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-120649 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above prior art, terminals of electronic components are soldered to pads on a circuit board, but no consideration is given to soldering the terminals of electronic components that pass through through holes in the circuit board to the inside of the through holes, to the pads on the solder side of the through holes, and to the pads on the component side. Therefore, an object of the present invention is to provide a circuit board for a high-frequency induction heating device to which terminals of electronic components can be properly soldered by a high-frequency induction heating device equipped with a core body having a magnetic gap. [Means for solving the problem]

[0005] To achieve this object, the circuit board for a high-frequency induction heating device of the present invention is a circuit board for a high-frequency induction heating device comprising a circuit board on which terminals of electronic components are heated and soldered across the magnetic gap of a core body by a high-frequency induction heating device having a core body with a magnetic gap, the circuit board having through holes that pass through between the solder surface and component surface, solder surface side pads on the solder surface side of the circuit board that are electrically connected to the through holes, and component surface side pads on the component surface side of the circuit board that are electrically connected to the through holes, and via hole areas are provided in the solder surface side pads and component surface pads in parts that are perpendicular to the magnetic gap direction of the core body of the high-frequency induction heating device, and the via hole areas have via holes that pass through between the component surface and solder surface of the circuit board and are thermally connected to the solder surface side pads and component surface pads. In addition, the circuit board for a high-frequency induction heating device of the present invention has the solder side pads and component side pads, which have non-via hole areas outside the through holes and on the extension line in the magnetic gap direction. [Effects of the Invention]

[0006] As described above, the circuit board for a high-frequency induction heating device of the present invention comprises through holes that penetrate between the solder side and component side of the circuit board, solder side pads on the solder side of the circuit board that are electrically connected to the through holes, and component side pads on the component side of the circuit board that are electrically connected to the through holes, and further comprises via hole areas in parts of the solder side pads and component side pads that are perpendicular to the magnetic gap direction of the core body of the high-frequency induction heating device, and these via hole areas have via holes that penetrate between the component side and solder side of the circuit board and are thermally conductively connected to the solder side pads and component side pads. That is, in the circuit board for a high-frequency induction heating device of the present invention, an area of ​​high current density is formed in the solder-side pad of the circuit board in a portion that is perpendicular to the magnetic gap direction of the high-frequency induction heating device, so that the heat generated in the solder-side pad portion is transmitted to the component-side pad via the via hole, thereby increasing the temperature of the component-side pad near the through-hole and within the through-hole, thereby preventing a deterioration in solder quality and a prolonged soldering time. In addition, by transferring the heat from the via hole area of ​​the solder side pad to the component side pad through the via hole, the via hole area of ​​the solder side pad can be prevented from becoming abnormally hot, and damage to the circuit board can also be prevented. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a perspective view of a high-frequency induction heater according to an embodiment of the present invention. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. 2 is a perspective view of the high-frequency induction heating device with a part removed. [Figure 6] FIG. [Figure 7]FIG. [Figure 8] FIG. 2 is an enlarged perspective view of a high-frequency induction heating head portion of the high-frequency induction heating device according to the first embodiment. [Figure 9] FIG. 2 is an enlarged exploded perspective view of a high-frequency induction heating head portion of the high-frequency induction heating device according to the first embodiment. [Figure 10] FIG. 2 is an enlarged exploded perspective view of a high-frequency induction heating head portion of the high-frequency induction heating device according to the first embodiment. [Figure 11] FIG. [Figure 12] FIG. [Figure 13] FIG. [Figure 14] FIG. [Figure 15] FIG. [Figure 16] FIG. [Figure 17] FIG. [Figure 18] FIG. [Figure 19] FIG. [Figure 20] FIG. 2 is a control block diagram of the high-frequency induction heating device according to the first embodiment. [Figure 21] 4A to 4C are diagrams illustrating the operation of the high-frequency induction heating device according to the first embodiment. [Figure 22] 4A to 4C are diagrams illustrating the operation of the high-frequency induction heating device according to the first embodiment. [Figure 23] 4A to 4C are diagrams illustrating the operation of the high-frequency induction heating device according to the first embodiment. [Figure 24] 4A to 4C are diagrams illustrating the operation of the high-frequency induction heating device according to the first embodiment. [Figure 25] 4A to 4C are diagrams illustrating the operation of the high-frequency induction heating device according to the first embodiment. [Figure 26] 4A to 4C are diagrams illustrating the operation of the high-frequency induction heating device according to the first embodiment. [Figure 27]4A to 4C are diagrams illustrating the operation of the high-frequency induction heating device of the first embodiment. [Figure 28] 4A to 4C are diagrams illustrating the operation of the high-frequency induction heating device of the first embodiment. [Figure 29] 4 is a flowchart illustrating the operation of the high-frequency induction heating device. [Figure 30] 10 is a partial plan view showing another embodiment of a circuit board to be soldered by the high-frequency induction heating device of the first embodiment; FIG. [Figure 31] 31 is a cross-sectional view taken along line A-A in FIG. 30. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. (Embodiment 1) In this embodiment, first, the configuration of the high-frequency induction heating head 1 will be described using FIGS. 1 to 10, and the configuration of other parts will be described using FIGS. 1 to 4, a high-frequency induction heating head 1 of this embodiment includes a box-shaped main body case 2. As shown in FIG. The main body case 2 has an upper surface 2a, a lower surface 2b, and four outer peripheral surfaces 2c, all six of which are formed from resin, and an IH output connection connector 2A and two cooling water connection connectors 3 are provided on the upper surface 2a of the main body case 2. Further, below the main body case 2, a core body 4 and a coil 5 that supplies magnetic flux to the core body 4 are arranged. As shown in Figs. 5 to 7, a capacitor 6 is disposed inside the main body case 2, and electric waterway connectors 7 and 8 are provided on both sides of the capacitor 6, facing outward from the capacitor 6 side. These electrical waterway connectors 7 and 8 are both made of copper material and are configured to provide electrical conduction with the articles they come into contact with. First, the electrical waterway connector 8 has an overall building-like shape, and inside it is formed a waterway (not shown) that extends vertically, and a cooling water connection connector 3 is connected to the upper end of this waterway on the upper surface of the electrical waterway connector 8. 7, the lower end of the water channel in the electrical water channel connector 8 forms a water channel joint 9 at the lower part of the electrical water channel connector 8 on the condenser 6 side. Next, the electrical waterway connector 7 has an overall plate-like shape, but inside the lower base portion 10, a waterway (not shown) is formed that extends laterally toward the electrical waterway connector 8 and then downward. The end of the water channel of the electrical water channel connector 7 on the side of the electrical water channel connector 8 is a water channel joint portion 11 as shown in FIG. 7, the water channel of the electrical water channel connector 7 has a water channel joining portion 12 at the end toward the lower end. With the above configuration, when the left and right electrical waterway connectors 7 and 8 are screwed to the fixing parts of the capacitor 6 using the metal screws 13 and 14 shown in Figures 6 and 7, the electrical waterway connectors 7 and 8 are integrated on both sides of the capacitor 6, as shown in Figure 5. Furthermore, through this integration process, continuous water channels are formed in both the left and right electrical water channel connectors 7 and 8, respectively, from the cooling water connection connector 3, the water channel within the electrical water channel connector 8, its water channel joint 9, the water channel joint 11 of the electrical water channel connector 7, the water channel of the electrical water channel connector 7, and the water channel joint 12. The integrated capacitor 6 and electrical waterway connectors 7 and 8 are held on the bottom surface 2b inside the main body case 2 as shown in Figure 5, and the cooling water connection connector 3 is pulled out onto the through hole A on the top surface 2a of the main body case 2. In addition, the undersides of the base portions 10 of the two electrical waterway connectors 7 are located in the through-hole B portion of the underside 2b of the main body case 2, so that the waterway coupling portion 12 on the underside of the base portions 10 faces outside the main body case 2 through the through-hole B. The core body 4 and the coil 5 are connected to the underside of the two base portions 10 with the screws 16 shown in FIGS. 6 and 7, as shown in FIG.

[0009] Specifically, the coil 5 is formed in a U-shape using a copper pipe with a water channel formed inside, and one end and the other end are connected to front and rear coil bases 17 and 18 made of copper, respectively. The front and rear coil bases 17, 18 have horizontal flanges 17a, 18a formed on their upper edges, each with a through hole for passing a screw 16 through. The front and rear coil bases 17, 18 are joined to the base part 10 of the electrical-waterway connector 7 by passing the screw 16 through the through hole of the flanges 17a, 18a from below and threading the screw 16 into the threaded hole on the underside of the base part 10 of the electrical-waterway connector 7. In addition, each of the coil bases 17 and 18 has a water passage (not shown) formed in the vertical direction, and the lower end of the water passage in the coil base 17 is connected to a water passage joint (not shown) on one end side of the coil 5, and the lower end of the water passage in the coil base 18 is connected to a water passage joint (not shown) on the other end side of the coil 5. In addition, a water channel joint 19 is formed on flange 17a at the upper end of the water channel of coil base 17 as shown in Figure 6, and a water channel joint 20 is formed on flange 18a at the upper end of the water channel of coil base 18 as shown in Figure 6. Therefore, when the coil bases 17 and 18 are fixed to the underside of the two base portions 10 with the metal screws 16 shown in Figures 6 and 7, the water channel coupling portions 19 and 20 of the coil bases 17 and 18 are each separately connected to the water channel coupling portions 12 on the underside of the two base portions 10 via rubber gaskets 15. In addition, a rubber packing 15 as shown in FIG. 7 is also interposed between the water channel joints 9 and 11 to prevent water leakage. With the above configuration, when cooling water of, for example, 25°C is poured into one of the cooling water connection connectors 3, the cooling water flows through the water channel in one of the electrical water channel connectors 8, the water channel joint 9, the water channel joint 11 of one of the electrical water channel connectors 7, the water channel in one of the electrical water channel connectors 7, the water channel joint 12, the water channel joint 19 of the coil base 17, the water channel in the coil base 17, the water channel joint on one end of the coil 5, the water channel in the coil 5, the water channel joint on the other end of the coil 5, the water channel in the coil base 18, the water channel joint 20 of the coil base 18, the water channel joint 12 of the other electrical water channel connector 7, the water channel in the other electrical water channel connector 8, and the other cooling water connection connector 3, and then is cooled in the cooling section outside the main body case 2 and circulated again to the one of the cooling water connection connectors 3. The coil bases 17 and 18 are overlapped with a resin insulating plate 21 in between, and the screws 22 that join them are made of resin and are insulating, so that no short-circuiting electrical conduction occurs between the coil bases 17 and 18. Also, as shown in Figure 5, one terminal of the IH output connection connector 2A and the terminal portion 23 of one of the electrical waterway connectors 8 are connected by wiring (not shown in the figure to avoid cluttering the drawing), and the other terminal of the IH output connection connector 2A and the terminal portion 24 of the other electrical waterway connector 8 are connected by wiring (not shown in the figure to avoid cluttering the drawing). The capacitor 6 and the electrical waterway connectors 7 and 8 are also integrated with the metal screws 13 and 14 and are electrically connected. Furthermore, the capacitor 6, the electrical waterway connectors 7 and 8, the coil bases 17 and 18, and the coil 5 are also electrically connected. That is, when power is supplied from the IH output connector 2A, resonance occurs between the capacitor 6 and the coil 5, and this resonance current is supplied to the coil 5, generating a magnetic flux.

[0010] Next, the core body 4 that performs heating by this magnetic flux will be described. As shown in Figures 8 to 10, the core body 4 is configured by overlapping one end (upper end) of a C-shaped first sub-core body 25 and one end (upper end) of an inverted C-shaped second sub-core body 26, and forming a magnetic gap 27 between the other end (lower end) of the sub-core bodies 25, 26. In other words, the core body 4 is configured such that, when viewed from the front, it is ring-shaped by overlapping one end (upper end) of the C-shaped sub-core body 25 and the inverted C-shaped sub-core body 26, and a gap that forms the magnetic gap 27 is formed in part of the ring. The coil 5 passes linearly through the internal space of the ring-shaped core body 4, so that the magnetic flux generated by the coil 5 flows through the core body 4 and the magnetic gap 27. Furthermore, a through hole 28 penetrating the sub-core bodies 25, 26 is provided in the overlapping portion at one end side of the sub-core bodies 25, 26, and a screw 29 is inserted into this through hole 28 as a penetrating shaft, and this screw 29 is used as an opening / closing shaft to vary the size of the magnetic gap 27. The core body 4 is formed in a plate shape with a thickness dimension in the front-to-back direction smaller than the outer diameter dimension when viewed from the front, and protective plates 30 and 31 are arranged on the front and back surfaces of this plate-shaped core body 4, respectively. The protective plate 30 is formed by overlapping one end (upper side) of a C-shaped first sub-protective plate 32 and an inverted C-shaped second sub-protective plate 33, and a through hole 34 is provided at the overlapping portion of these sub-protective plates 32, 33, penetrating the sub-protective plates 32, 33, and a screw 29 passes through this through hole 34 as the penetrating axis. In addition, the protective plate 31 is formed by overlapping one end (upper side) of a C-shaped first sub-protective plate 35 and an inverted C-shaped second sub-protective plate 36, and a through hole 37 that penetrates the sub-protective plates 35, 36 is provided at the overlapping portion of these sub-protective plates 35, 36, and a screw 29 passes through this through hole 37 as the through axis. In other words, the screw 29 acts as a through axis and passes through the through hole 34 of the sub-protective plates 32 and 33, then the through hole 28 of the sub-core bodies 25 and 26, and then the through hole 37 of the sub-protective plates 35 and 36, and is screwed into the threaded hole 39 of the U-shaped heat conduction member 38. With this configuration, the core body 4 is covered on both the front and back surfaces with the protection plates 30 and 31 in a state where heat can be conducted. Further, rearward bent portions 40 are formed on the upper portions of the sub-protective plates 32 and 33 so as to cover the upper surfaces of the sub-core bodies 25 and 26, and screw holes 41 are formed in the bent portions. Furthermore, a forward bent portion 42 is formed in the upper portion of the sub-protective plates 35, 36 so as to cover the rearward bent portion of the upper portion of the sub-protective plates 32, 33, and a through hole 43 is formed therein. Further, the sub-protective plates 35 and 36 are provided at their upper portions with outward mounting portions 44, in which through holes 45 are formed. The through-hole 43 is a long hole extending in the front-rear direction, and the through-hole 45 is a long hole extending in the outer circumferential direction. With this configuration, the protective plate 31, core body 4, and protective plate 30 are stacked and held and fixed to the heat conduction member 38. As an example of the method, first, the protective plate 31, core body 4, and protective plate 30 are stacked, and a rod-shaped jig (not shown) is passed through the through holes 34, 28, and 37 to align the axes. Next, the screw 46 is threaded from above the protective plate 31 through the through hole 43 into the screw hole 41 of the protective plate 30, thereby sandwiching the core body 4 between the protective plates 30 and 31 from the front and back. Then, the rod-shaped jig is removed from the core body 4 and protective plates 30, 31 that have been temporarily unitized in this manner, and is then placed in the holding portion 38a of the heat conduction member 38 in Figure 9. Screws 29 are then passed through the through holes 34, 28, and 37 of the protective plate 31, core body 4, and protective plate 30, and these screws 29 are then screwed into the threaded holes 39 of the heat conduction member 38. The screws 47 are passed through the through holes 45 of the protection plate 31 and screwed into the screw holes 48 of the heat conducting member 38 . In this state, the size of the magnetic gap 27 is adjusted, and finally the screws 29 and 47 are tightly tightened, thereby completing the holding and fixing of the protection plate 31, core body 4 and protection plate 30 to the heat conducting member 38. With the above configuration, the surface of the protection plate 31 opposite to the core body 4 is in contact with the heat conducting member 38, facilitating heat conduction between the heat conducting member 38 and the protection plate 31. In other words, when the coil base 18 is cooled by the cooling water that cools the coil 5, the low temperature is also used to cool the core body 4 made of ferrite material via the copper heat conduction member 38 and the copper protective plate 31, and in this embodiment, even when operated continuously for 24 hours, the temperature of the core body 4 can be kept at around 100°C.

[0011] The high frequency induction heating head of this embodiment solders the terminals of electronic components to the pads of the circuit board in the magnetic gap 27 area, and the ability to perform such soldering work continuously for 24 hours a day dramatically increases productivity. In this embodiment, the protection plates 30 and 31 are made of a metal material that has a lower relative magnetic permeability than the core body 4 and a lower electrical resistance than the core body 4 . Specifically, the core body 4 is made of a ferrite material, and the protection plates 30 and 31 are made of a copper material or an aluminum material. The relative permeability of the ferrite material that makes up the core body 4 is 50 to 5000, whereas when the protective plates 30 and 31 are made of copper or aluminum, the relative permeability is approximately 1. Therefore, the magnetic flux that flows through the core body 4 flows solely within the core body 4 and rarely leaks to the protective plates 30 and 31. However, in this embodiment, a large current of about 100 A is passed through the coil 5, so even if the leakage magnetic flux is sufficiently small compared to the amount of magnetic flux flowing through the magnetic gap 27, it may still heat up the components near the core body 4 sufficiently and cause them to reach high temperatures. In contrast, in this embodiment, the magnetic flux leaking from the core body 4 passes through the protective plates 30, 31, which have a lower relative permeability than the core body 4. Furthermore, since these protective plates 30, 31 are made of a metal material with a lower electrical resistance than the core body 4, the passage of the magnetic flux causes eddy currents to flow, and these eddy currents generate magnetic flux in the opposite direction to the magnetic flux passing through the protective plates 30, 31. As a result, the amount of magnetic flux leaking from the core body 4 through the protective plates 30, 31 is reduced, thereby preventing other nearby components from being inadvertently heated. According to the experiment, it was possible to reduce inadvertent heating by 20% at a position 4 mm away from the magnetic gap 27, and by 40% at a position 8 mm away. This prevents an article that is not intended to be heated from being inadvertently heated by the magnetic flux from the core body 4 and from being deteriorated. Furthermore, since items that are not intended to be heated in the vicinity of the magnetic gap 27 are not inadvertently heated by the magnetic flux, the degree of freedom in the heating operation is improved, and productivity is also increased. Furthermore, the reduction in leakage flux also means that the magnetic flux in the magnetic gap 27 increases, which can improve the heating efficiency. When the protection plates 30 and 31 are made of copper, the electrical resistance is 1.68×10 -8 Ωm, and when the protection plates 30 and 31 are made of aluminum, the electrical resistance is 2.83×10 -8 While ferrite material is substantially insulating, it has an extremely low electrical resistance of Ωm. Furthermore, the outer shape of the core body 4 and the outer shapes of the protective plates 30, 31 are made substantially the same, and the front and back surfaces of the core body 4 are covered with the protective plates 30, 31, so that the protective plates 30, 31 can protect the core body 4 from being directly hit by other objects, and as a result, damage to the core body 4 can be suppressed. In other words, since the core body 4 is made of ferrite, it is susceptible to damage when struck by other objects or when the core body 4 itself falls. However, if the outer shape of the core body 4 and the outer shape of the protective plates 30, 31 are made approximately the same and the front and back of the core body 4 are covered with the protective plates 30, 31, the protective plates 30, 31 can protect the core body 4 from being directly struck by other objects, and as a result, damage to the core body 4 can be reduced. Furthermore, when the protective plate 31 is made of copper, the thermal conductivity is 403 W / m K, and when it is made of aluminum, the thermal conductivity is 236 W / m K, both of which have good thermal conductivity. Therefore, when the coil 5 is cooled with cooling water, the core body 4 can be sufficiently cooled via the protective plate 31. However, if a thermally conductive grease such as silicone grease is placed between the core body 4 and the protective plate 31, the cooling effect can be further improved. In the above embodiment, the core body 4 is water-cooled, but the core body 4 may be air-cooled. For example, air may be blown to the heat conducting member 38 and the protection plates 30 and 31 for cooling. For this purpose, the heat conducting member 38 and the protection plates 30 and 31 may be provided with heat dissipation fins.

[0012] The above explanation has focused on the core body 4, coil 5, etc. that make up the high-frequency induction heating head 1, but in addition to the high-frequency induction heating head 1, the high-frequency induction heating device of this embodiment also includes a wire solder supply device 49 as an example of a solder supply device shown in Figures 11 to 29, and radiation thermometers 50, 51 as examples of temperature measuring means. Although Figures 11 to 29 are identical to those shown in Figures 1 to 10, the explanation will focus on the solder wire supply device 49 and the radiation thermometers 50 and 51, and in order to avoid complicating the drawings, some of the symbols explained in Figures 1 to 10 have not been added. First, as shown in Figures 11 to 20, the high-frequency induction heating device of this embodiment is provided with, in addition to the high-frequency induction heating head 1, a wire solder supply device 49 as an example of a solder supply device, and radiation thermometers 50 and 51 as an example of a temperature measuring means. The circuit board 52 shown in FIG. 15 is transported to the high-frequency induction heating head 1 by, for example, an XYΘ table (not shown) used as an example of transport means. As shown in Figures 17, 18, and 21, the circuit board 52 includes a through hole 52a (having a conductive film on the inner surface) penetrating the circuit board 52, a solder surface side pad 53a electrically connected to the through hole 52a on the solder surface side of the circuit board 52 (in this embodiment, the upper surface side in Figures 17, 18, and 21), and a component surface side pad 53b electrically connected to the through hole 52a on the component surface side of the circuit board 52 (in this embodiment, the lower surface side in Figures 17, 18, and 21). In addition, electronic components such as a transformer (not shown) are mounted on the component side of the circuit board 52, and their terminals 54 penetrate the through holes 52a from the component side (lower side) to the solder side (upper side) and protrude onto the solder side (upper side) of the circuit board 52. As shown in FIG. 21, this terminal 54 is moved into the magnetic gap 27 of the high-frequency induction heating head 1, and in this state is soldered to the solder surface side pad 53a, the component side pad 53b, and the through hole 52a. In other words, the terminal 54 portion protruding from the solder surface side (upper surface side) of the circuit board 52 is sandwiched between the sub-core bodies 25 and 26 at a predetermined distance in the magnetic gap 27 portion formed by the sub-core bodies 25 and 26. In this state, the radiation thermometer 50 shown in FIGS. 11 to 20 measures the temperature of the upper end portion of the terminal 54 protruding above the through-hole 52a. The radiation thermometer 50 corresponds to the first temperature detecting means of the present invention. A radiation thermometer 51 measures the temperature of the solder surface side pad 53a and the temperature of the terminal 54 adjacent to the solder surface side pad 53a. This radiation thermometer 51 corresponds to the second temperature detecting means in the present invention. As shown in FIG. 20, these radiation thermometers 50 and 51 are connected to a control unit 55, which is an example of a control means. The control unit 55 is also connected to a timer 56, a memory 57 (containing the program shown in FIG. 29, etc.), and a power supply unit 58, and the power supply unit 58 is connected to the coil 5 and the capacitor 6. As shown in Figure 15, the solder wire supply device 49 is held on the heat conductive member 38 by a holding means 59, and as shown in Figures 21 to 24, the solder wire supply device 49 is configured to appropriately supply solder wire 49a to the terminal 54 portion located in the magnetic gap 27. Here, we will explain the relationship between the supply position of the solder thread 49a from the solder thread supply device 49 to the terminal 54 protruding from the through hole 52a toward the solder surface side and the temperature detection position by the radiation thermometer 50.The solder thread supply device 49 is configured to supply the solder thread 49a to the terminal 54 portion that is closer to the solder surface side pad 53a than the temperature detection portion by the radiation thermometer 50. In other words, the radiation thermometer 50 detects the temperature of the terminal 54 without being affected by the melting wire solder 49a. On the other hand, the radiation thermometer 51 is set to measure the temperature of the solder surface side pad 53a and the terminal 54 close to this solder surface side pad 53a, so that it detects the temperature in a state that is affected by the melting state of the wire solder 49a.

[0013] This condition is explained in more detail below. The radiation thermometers 50 and 51 are held in the main body case 2 by other holding means, but these holding means are not shown in order to avoid complicating the drawing. In the above configuration, when the circuit board 52 is transported by the XYΘ table (not shown) and its terminal 54 is positioned in the magnetic gap 27 portion as shown in Figures 17 and 21, power supply to the coil 5 is started as preheating (S1 in Figure 29), and temperature measurement by the radiation thermometers 50 and 51 is also started (S2 in Figure 29). In the flow diagram shown in FIG. 29, the radiation thermometer 50 is represented as the radiation thermometer 1, and the radiation thermometer 51 is represented as the radiation thermometer 2. Terminals are also labeled as pins. In this preheating (period A in FIG. 27), heating is performed at 105 A and 130 W, for example. As shown in FIGS. 17 to 19, the radiation thermometer 50 measures the temperature of the upper end portion of the terminal 54 protruding from the through hole 52a toward the solder surface of the circuit board 52. As shown in FIGS. 17 to 19, the radiation thermometer 51 measures the temperature of the solder-side pad 53a and the terminal 54 near the solder-side pad 53a. First, it is determined whether the temperature measured by the radiation thermometer 50 (the temperature at the upper end of the terminal 54) exceeds the solder melting temperature (e.g., 300°C) at which the wire solder 49a can be sufficiently melted (S3 in Figure 29). The melting temperature of the wire solder 49a used here is about 220° C. as shown in FIG. Therefore, at the above solder melting temperature (for example, 300° C.), the wire solder 49a can be sufficiently melted. If the temperature of the upper end portion of the terminal 54 detected by the radiation thermometer 50 does not exceed 300°C, then it is determined whether the temperature detected by the radiation thermometer 51 (the temperature of the solder surface side pad 53a and the terminal 54 portion nearby) exceeds the overheat threshold temperature (e.g., 350°C) (S4 in Figure 29). If the temperature detected by the radiation thermometer 51 (the temperature of the solder surface side pad 53a and the terminal 54 in the vicinity thereof) does not exceed the overheat threshold temperature (for example, 350° C.), the process returns to (S3 in FIG. 29) and preheating continues. (Period A) in Figure 27 shows the temperature (line E) of the upper end portion of terminal 54 detected by radiation thermometer 50 in this preheating state, and the temperature (line F) of solder side pad 53a and the nearby portion of terminal 54 detected by radiation thermometer 51 in this preheating state. As can be seen from these (Line E) and (Line F), during preheating (Period A in Figure 27), the temperature gradually rises over time, but since terminal 54 is heated within magnetic gap 27, the temperature rise speed is faster in solder surface side pad 53a than in the nearby portion of terminal 54. In addition, if the temperature detected by the radiation thermometer 51 (the temperature of the solder surface side pad 53a and the terminal 54 in the vicinity thereof) exceeds the overheat threshold temperature (e.g., 350°C) in (S4 in Figure 29), the power supply to the coil 5 is stopped (S5 in Figure 29). Also, in (S3 in Figure 29), when the temperature of the upper end portion of the terminal 54 exceeds 300°C, which is a temperature that can sufficiently melt the wire solder 49a, a determination is then made as to whether the temperature detected by the radiation thermometer 50 (the temperature of the upper end portion of the terminal 54) exceeds the overheat threshold temperature (e.g., 350°C) (S6 in Figure 29). If the temperature of the upper end portion of the terminal 54 exceeds the overheat threshold temperature (for example, 350° C.) (S6 in FIG. 29), the power supply to the coil 5 is stopped (S7 in FIG. 29). If the temperature of the upper end portion of the terminal 54 does not exceed the overheat threshold temperature (e.g., 350°C) (S6 in FIG. 29), then it is determined whether the temperature detected by the radiation thermometer 51 (the temperature of the solder surface side pad 53a portion and the terminal 54 portion nearby) exceeds the overheat threshold temperature (e.g., 350°C) (S8 in FIG. 29). In (S8 in FIG. 29), if the temperature detected by the radiation thermometer 51 (the temperature of the solder surface side pad 53a and the nearby terminal 54) exceeds the overheat threshold temperature (e.g., 350°C), the power supply to the coil 5 is stopped (S9 in FIG. 29). In (S8 in Figure 29), if the temperature detected by the radiation thermometer 51 (the temperature of the solder side pad 53a and the nearby terminal 54) does not exceed the overheat threshold temperature (e.g., 350°C), as shown in Figures 21 and 22, the supply of thread solder 49a by the thread solder supply device 49 is started (period B in Figure 27), and the output to the coil 5 is changed (output increased) to 150 A and 270 W for main heating (S10 in Figure 29). That is, a preset amount of solder wire 49a is supplied from solder wire supply device 49 to the magnetic gap 27 portion of terminal 54. The wire solder 49a supplied to the terminal 54 melts due to the heat of the terminal 54, and becomes spherical at the solder surface side pad 53a as shown in Figure 23, and then flows and flows into the through hole 52a as shown in Figure 24. 22 shows (point B in period) in FIG. 27, FIG. 23 shows (the state at point 23 in FIG. 23 of main heating period Ca) in FIG. 27, and FIG. 24 shows (the state at point 24 in FIG. 24 of main heating period Cb) in FIG. In other words, Figure 22 shows the point at which the supply of solder wire 49a from solder wire supply device 49 begins, and the temperature detected by radiation thermometer 50 (the temperature of the upper end part of terminal 54) reaches 310°C, but the temperature detected by radiation thermometer 51 (the temperature of the solder surface side pad 53a part and the terminal 54 part nearby) is 200°C. For reference, the detected temperature of component surface side pad 53b (measured using other temperature detection means for reference) is 150°C. The temperature at the upper end of terminal 54 reaches 310°C because terminal 54 is heated intensively within magnetic gap 27. In comparison, the detected temperature at solder surface side pad 53a and the nearby terminal 54 is low at 200°C because the magnetic flux density is lower than that at magnetic gap 27. Furthermore, the magnetic flux density is even lower in component surface side pad 53b than in magnetic gap 27, and the temperature rise occurs mainly due to heat conduction through through hole 52a. Also, in Figure 23, the supply of solder wire 49a from solder wire supply device 49 has started, and the heating state has been reached. The temperature detected by radiation thermometer 50 (the temperature of the upper end part of terminal 54) remains at 310°C, and the temperature detected by radiation thermometer 51 (the temperature of the solder surface side pad 53a part and the terminal 54 part nearby) is 155°C. The detected temperature of the component surface side pad 53b is 160°C. The temperature of the upper end portion of the terminal 54 is maintained at 310°C because it is in the main heating state, while the temperature of the solder surface side pad 53a and the nearby portion of the terminal 54 drops to 155°C. This is because the radiation thermometer 51 is used as a temperature detection means for detecting the temperature of the solder surface side pad 53a and the terminal 54 in the vicinity thereof. In other words, as shown in Figure 23, when the solder becomes molten in the solder surface side pad 53a part and the nearby terminal 54 part, the molten solder reduces the temperature radiation from the temperature detection part, and when the molten solder comes into contact with the solder surface side pad 53a, heat is conducted to the circuit board 52 side. As a result, the temperature detected by the radiation thermometer 51 (the temperature of the solder surface side pad 53a part and the nearby terminal 54 part) gradually decreases as shown by line F in Figure 27. The detected temperature of the component surface side pad 53b is slightly increased to 160° C. because heat conduction through the through hole 52a has progressed. Also, in Figure 24, when the supply of solder wire 49a from the solder wire supply device 49 and the heating state are continued, the temperature detected by the radiation thermometer 50 (the temperature of the upper end part of the terminal 54) is maintained at 310°C, and the temperature detected by the radiation thermometer 51 (the temperature of the solder surface side pad 53a part and the terminal 54 part nearby) is 95°C. The detected temperature of the component surface side pad 53b is 180°C. The temperature of the upper end portion of the terminal 54 is maintained at 310°C because it is in the main heating state, while the temperature of the solder surface side pad 53a and the nearby portion of the terminal 54 drops to 95°C.

[0014] This is because, as described above, the radiation thermometer 51 is used as a temperature detection means for detecting the temperature of the solder surface side pad 53a and the terminal 54 in the vicinity thereof. In other words, as shown in Figure 24, when the solder melts in the solder surface side pad 53a and the nearby terminal 54 and flows into the through hole 52a, the molten solder reduces the temperature radiation from the temperature detection part, and the molten solder comes into contact with the solder surface side pad 53a, flows into the through hole 52a, and heat conducts toward the circuit board 52. As a result, the temperature detected by the radiation thermometer 51 (the temperature of the solder surface side pad 53a and the nearby terminal 54) gradually decreases as shown by line F in Figure 27. The detected temperature of the component surface side pad 53b is slightly increased to 180° C. because heat conduction through the through hole 52a has progressed. Even in this main heating state, a determination is continuously made as to whether the temperature detected by the radiation thermometer 50 (the temperature at the upper end portion of the terminal 54) exceeds the overheat threshold temperature (e.g., 350°C) (S11 in Figure 29). If the temperature detected by the radiation thermometer 50 (the temperature at the upper end of the terminal 54) exceeds the overheat threshold temperature (for example, 350°C) (S11 in FIG. 29), the power supply to the coil 5 is stopped (S12 in FIG. 29). In (S11 in Figure 29), if the temperature measured by the radiation thermometer 50 (the temperature of the upper end part of the terminal 54) does not exceed the overheat threshold temperature (e.g., 350°C), the heating continues, and the solder wire supply device 49 continues to supply only a predetermined amount of solder wire 49a. As a result, the molten solder wire 49a reaches the component-side pad 53b as shown in FIG. In addition, in the state shown in FIG. 25, the supply of wire solder 49a has also been completed. The state of FIG. 25 shows the state of FIG. 27 and FIG. 28 (the state at the point in FIG. 25 during period D). In Figure 25, the supply of solder wire 49a from solder wire supply device 49 has ended, but the heating state continues, and the temperature detected by radiation thermometer 50 (the temperature of the upper end part of terminal 54) is 320°C, and the temperature detected by radiation thermometer 51 (the temperature of solder surface side pad 53a and the nearby terminal 54 part) is 90°C. The detected temperature of the component surface side pad 53b is 220°C. The detected temperatures at each point in FIG. 25 will be described in detail below. What is noteworthy in Figure 27 is that from the start of the supply of wire solder 49a (period B in Figure 27) through (main heating periods Ca and Cb), the temperature detected by radiation thermometer 50 (the temperature of the upper end portion of terminal 54) is 300°C or higher, while the temperature detected by radiation thermometer 51 (the temperature of the solder surface side pad 53a portion and the nearby terminal 54 portion) gradually decreases from around 200°C. The temperature detected by radiation thermometer 50 (the temperature at the upper end of terminal 54) is 300° C. or higher because high-frequency induction heating by sub-core bodies 25 and 26 is being performed continuously. If high-frequency induction heating by the sub-core bodies 25, 26 is performed continuously, it is thought that the temperature detected by the radiation thermometer 51 (the temperature of the solder surface side pad 53a portion and the nearby terminal 54 portion) will also gradually increase, but in reality, the temperature detected by the radiation thermometer 51 gradually decreases as shown by line F in Figure 27. This is because the radiation thermometer 51 is used as a temperature detection means for detecting the temperature of the solder surface side pad 53a and the terminal 54 in the vicinity thereof. In other words, as shown in Figures 23 and 24, when the solder surface side pad 53a and the nearby terminal 54 become molten, the molten solder reduces the temperature radiation from the temperature detection part, and the molten solder comes into contact with the solder surface side pad 53a and flows into the through hole 52a, causing heat conduction to the circuit board 52 side.In conclusion, even if this heating state continues, the temperature detected by the radiation thermometer 51 (the temperature of the solder surface side pad 53a and the nearby terminal 54) will gradually decrease as shown by line F in Figure 27. However, in (period D) in FIGS. 27 and 28, the temperature detected by the radiation thermometer 51, which had been decreasing, begins to increase. This state will be explained using FIG. 25, which shows the portion indicated by the point in FIG. 25 during (period D) in FIGS. In FIG. 25, the supply of the wire solder 49a has also finished, and the solder supplied to the terminal 54 has passed from the solder-side pad 53a through the through-hole 52a and reached the component-side pad 53b. The temperature of component surface side pad 53b continues to rise due to heat conduction through terminal 54, through hole 52a, and solder, and in the state shown in FIG. 25, it has reached 220° C., which is higher than the melting point of wire solder 49a. In other words, in the states of Figures 23 and 24, the temperature detected by radiation thermometer 51 gradually decreases due to heat absorption by solder surface side pad 53a, through hole 52a, and component surface side pad 53b, but in the state of Figure 25, even component surface side pad 53b is at 220°C, so the heat absorption state does not occur, and as a result, the temperature detected by radiation thermometer 51 begins to rise. In this embodiment, the temperature detected by the radiation thermometer 51 starts to rise, and after 0.3 seconds (set by the timer 56), it is determined that "the solder has also reached the component surface side pad 53b, and fillets have been formed on the solder surface side pad 53a and the component surface side pad 53b" (S13 in Figure 29). In addition, in the state where an increase in the temperature detected by the radiation thermometer 51 is not detected in (S13 in FIG. 29), the process returns to (S11 in FIG. 29) again, and the main heating is continued. Next, when an increase in the temperature detected by the radiation thermometer 51 is detected (S13 in FIG. 29), it is then determined whether the temperature detected by the radiation thermometer 50 (the temperature at the upper end of the terminal 54) exceeds the overheat threshold temperature (e.g., 350°C) (S14 in FIG. 29). If the temperature of the upper end portion of the terminal 54 exceeds the overheat threshold temperature (for example, 350° C.) (S14 in FIG. 29), the power supply to the coil 5 is stopped (S15 in FIG. 29). Also, in (S14 in Figure 29), if the temperature of the upper end portion of the terminal 54 does not exceed the overheat threshold temperature (e.g., 350°C), power supply to the coil 5 continues for the finishing time set by the timer 56, and when the finishing time has elapsed, output to the coil 5 is stopped (S16, S17 in Figure 29). FIG. 26 shows the state at point 26 in period D of FIGS. 27 and 28. In other words, when soldering is completed and output to coil 5 is stopped, the temperature detected by radiation thermometer 50 (temperature of the upper end part of terminal 54) is 330°C, the temperature detected by radiation thermometer 51 (temperature of solder surface side pad 53a and the nearby terminal 54 part) is 100°C, and the temperature detected by component surface side pad 53b is 230°C. By carrying out such control, appropriate fillets are formed on both the solder surface side pads 53a and the component surface side pads 53b, as shown in FIG. That is, the terminals 54 of the electronic components can be properly soldered to the circuit board 52 having the through holes 52a. In the above embodiment, the soldering was performed by arranging the circuit board 52 in a flat state with the solder side pads 53a on the upper surface and the component side pads 53b on the lower surface, but soldering can also be performed by arranging the circuit board 52 in a flat state with the solder side pads 53a on the lower surface and the component side pads 53b on the upper surface. In other words, the solder melted at the terminal 54 advances to the solder surface pad 53a, the through hole 52a, and the component surface pad 53b due to its wet state and capillary action in the through hole 52a, so soldering can also be performed with the solder surface pad 53a on the bottom surface and the component surface pad 53b on the top surface. Furthermore, even when the circuit board 52 is in an upright position, the molten solder advances to the solder surface pads 53a, the horizontal through holes 52a, and the component surface pads 53b, so that proper soldering can be performed even in this case. In the above embodiment, when the temperature detected by the radiation thermometer 51 (the temperature of the solder surface side pad 53a and the terminal 54 in the vicinity thereof) shows a downward trend and then starts to rise, the control unit 55 stops the supply of electricity to the coil 5. However, in this case, the amount of power supplied to the coil 5 may be reduced.

[0015] (Embodiment 2) 30 and 31 (a cross-sectional view taken along the line AA in FIG. 30) show a circuit board 60 to be soldered by the high-frequency induction heating device described above (Embodiment 1). This circuit board 60 has front surface pads 61a which serve as solder surface pads, and rear surface pads 61b which serve as component side pads. The circuit board 60 also has a through-hole 62 penetrating through it, and the through-hole 62 is electrically connected to the front-side pad 61a and the back-side pad 61b. Furthermore, terminals 64 of electronic components 63 mounted on the back side of this circuit board 60 penetrate through the through holes 62 in the direction from the back side pads 61b to the front side pads 61a. Then, soldering is performed by the core body 4 of the high frequency induction heating device. Specifically, in the magnetic gap 27 between the left and right sub-core bodies 25 and 26 of the core body 4 , the terminal 64 is sandwiched between the left and right sub-core bodies 25 and 26 of the core body 4 . A feature of this circuit board 60 is that, since electronic components 63 and the like that pass a large current are mounted on it, the front surface pads 61a and rear surface pads 61b are larger than the outer diameter of the electronic components 63, for example. When a terminal 64 of an electronic component 63 is soldered to a circuit board 60 having such large front-side pads 61a and back-side pads 61b using a high-frequency induction heating device, the temperature rise in the through-holes 62 and back-side pads 61b becomes slow, resulting in a deterioration in solder quality and a longer soldering time. In other words, even if the terminal 64 of the electronic component 63 is heated by the core body 4 of the high-frequency induction heating device, if the front-side pad 61a and the back-side pad 61b are large, the temperature rise in the through-hole 62 and the back-side pad 61b will be slow. Therefore, in this embodiment, a via hole area 65 is provided in the front side pad portion 61a and the back side pad portion 61b in a portion that is perpendicular to the direction of the magnetic gap 27 of the core body 4 of the high-frequency induction heating device, and this via hole area 65 is provided with a plurality of via holes 66 that penetrate between the front and back sides of the circuit board 60 and are thermally connected to the front side pad portion 61a and the back side pad portion 61b. Furthermore, non-via hole areas 67 are provided on the front surface side pad portion 61 a and the back surface side pad portion 61 b ​​outside the through holes 62 and on the extension line in the direction of the magnetic gap 27 . With the above configuration, it is possible to promote temperature rise in the through-hole 62 and in the front-side pad portion 61a and the back-side pad portion 61b in the vicinity of the through-hole 62, thereby preventing a deterioration in solder quality and a prolonged soldering time.

[0016] That is, in the magnetic gap 27 portion of the high-frequency induction heating device, in addition to the magnetic flux passing through the terminal 64, magnetic flux flows through the sub-core body 25 of the core body 4, the surface side pad portion 61a, inside the circuit board 60, the sub-core body 26, and the next moment through the sub-core body 26, the surface side pad portion 61a, inside the circuit board 60, and the sub-core body 25. In this way, eddy currents flow in the surface side pad portion 61a portion where the magnetic flux passes on both sides of the through hole 62. At this time, magnetic flux passes from the upper side to the lower side of the surface-side pad portion 61a on one side of the through-hole 62, and conversely, magnetic flux passes from the lower side to the upper side of the surface-side pad portion 61a on the other side, and eddy currents are generated in each magnetic flux passage portion due to the passage of the magnetic flux. As a result, as shown in FIG. 30, in the via hole area 65 portion orthogonal to the direction of the magnetic gap 27, eddy currents 68 flow in the same direction on both sides of the through hole 62. Also, 65a indicates an area in the via hole area 65 where the current density is high, and a via hole 66 is provided in this area 65a. As a result, the via hole area 65 of the front surface side pad portion 61a experiences a higher temperature rise than other locations. Therefore, in this embodiment, a plurality of via holes 66 are provided in this via hole area 65, which penetrate between the front and back surfaces of the circuit board 60 and are thermally connected to the front surface pad portion 61a and the back surface pad portion 61b. As a result, heat generated in the via hole area 65 of the front surface side pad portion 61a is transmitted to the back surface side pad portion 61b through the via hole 66, as shown by the arrow in Figure 31, thereby increasing the temperature of the back surface side pad portion 61b near the through hole 62 and within the through hole 62, thereby accelerating the temperature rise within the through hole 62 and the front surface side pad portion 61a and back surface side pad portion 61b near this through hole 62, preventing a deterioration in soldering quality and a prolonged soldering time. In addition, by transferring heat from the via hole area 65 of the front surface pad portion 61a to the back surface pad portion 61b through the via hole 66, the via hole area 65 of the front surface pad portion 61a is prevented from becoming abnormally hot, and damage to the circuit board 60 is also prevented. Furthermore, non-via hole areas 67 are provided in the front-side pad portion 61a and the back-side pad portion 61b outside the through-hole 62, on the extension line toward the magnetic gap 27. This not only reduces costs but also promotes the temperature rise of the front-side pad portion 61a and the back-side pad portion 61b near the through-hole 62 without unnecessarily increasing the thermal load on the front-side pad portion 61a and the back-side pad portion 61b. In FIG. 31, reference numeral 69 denotes a resist film provided on the front surface pad portion 61a and the back surface pad portion 61b. [Industrial Applicability]

[0017] The circuit board for a high-frequency induction heating device according to the present invention enables appropriate soldering to through holes when soldering is performed using a high-frequency induction heating device that heats terminals of electronic components by sandwiching them in a magnetic gap. [Explanation of symbols]

[0018] 1 High frequency induction heating head 2 Main unit case 2a Top side 2b Bottom side 2c Outer surface 2A IH output connector 3 Cooling water connector 4 Core Body 5 coils 6 capacitors 7 Electrical Waterway Connector 8 Electrical waterway connector 9 Waterway joint 10 Base 11 Waterway joint 12 Waterway joint 13 Screws 14 screws 15 Rubber packing 16 screws 17 Coil base 18 Coil base 19 Waterway joint 20 Waterway joint 21 Insulating plate 22 screws 23 Terminal section 24 Terminal section 25 Sub-core bodies 26 Sub-core body 27 Magnetic Gap 28 Through Hole 29 screws 30 Protection plate 31 Protective plate 32 Sub-protection plate 33 Sub-protection plate 34 Through hole 35 Sub-protection plate 36 Sub-protection plate 37 Through hole 38 Thermal Conduction Materials 39 screw holes 40 Folding section 41 screw holes 42 Folding section 43 Through hole 44 Mounting part 45 through holes 46 screws 47 Screw 48 screw holes 49 Solder wire supply device 50 Radiation thermometer (radiation thermometer 1, first temperature detection means) 51 Radiation thermometer (radiation thermometer 2, second temperature detection means) 52 Circuit Board 52a through hole 53a Solder side pad 53b Component side pad 54 terminals (pins) 55 Control Unit 56 Timer 57 Memory 58 Power supply section 59 Holding means 60 Circuit Board 61a Surface pad (solder side pad) 61b Back side pad (component side pad) 62 through holes 63 Electronic Components 64 terminals 65 Beer Hall Area 65a Area 66 Beer Hall 67 Non-Beer Hall Area 68 Eddy current 69 Resist film

Claims

[Claim 1] A circuit board for a high frequency induction heating device, the circuit board including a core body having a magnetic gap, and a terminal of an electronic component being heated and soldered in the magnetic gap of the core body by a high frequency induction heating device, the circuit board includes a through-hole penetrating between its solder surface and component surface, a solder surface pad on the solder surface side of the circuit board that is electrically conductively connected to the through-hole, and a component surface pad on the component surface side of the circuit board that is electrically conductively connected to the through-hole; via hole areas are provided in the solder surface side pads and component side pads at portions perpendicular to the magnetic gap direction of the core body of the high frequency induction heating device, and via holes are provided in the via hole areas that penetrate between the component surface and solder surface of the circuit board and are thermally conductively connected to the solder surface side pads and component side pads; A circuit board for a high-frequency induction heating device, characterized in that the solder side pads and component side pads have non-via hole areas outside the through holes, on the extension line in the magnetic gap direction.

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