Planar transformer

Abstract

The circuit board of the planar transformer includes a first post hole, a second post hole, and a plurality of winding layers. At least one winding layer includes a first winding wire and a second winding wire connected in series. The first winding wire surrounds the first post hole and has a first opening direction, and the second winding wire surrounds the second post hole and has a second opening direction. The first opening direction is different from the second opening direction. In this way, the holes can be properly connected in series between the multiple layers to increase the number of winding turns.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a transformer, in particular, a planar transformer. BACKGROUND

[0002] Many electrical appliances use transformers to adjust input voltage to a desired voltage. A general transformer includes a high-voltage side coil and a low-voltage side coil. The high-voltage side coil receives alternating current to generate a magnetic field. The low-voltage side coil generates an induced potential difference in response to the magnetic field. The transformer obtains voltage conversion corresponding to the turns ratio of the high-voltage side coil and the low-voltage side coil.

[0003] Currently, more and more electrical appliances require small size, so the size of the transformer also needs to be reduced. Compared with traditional transformers, planar transformers have the characteristic of small size. Therefore, the proportion of planar transformers used in applications with smaller space is increasing. SUMMARY

[0004] Therefore, according to some embodiments, a planar transformer includes a circuit board including a plurality of winding layers, a first post hole, and a second post hole. Each winding layer includes a first winding post region and a second winding post region. The first post hole passes through the first winding post regions, and the second post hole passes through the second winding post regions. The winding layers include a first layer and a second layer. The first layer includes a first winding wire and a second winding wire. The first winding wire of the first layer is located in the first winding post region of the first layer and surrounds the first post hole to have a first opening direction, and the second winding wire of the first layer is located in the second winding post region of the first layer and surrounds the second post hole to have a second opening direction. The first winding wire of the first layer is electrically connected to the second winding wire of the first layer, and the first opening direction of the first layer is different from the second opening direction of the first layer. The second layer includes a first winding wire and a second winding wire. The first winding wire of the second layer is located in the first winding post region of the second layer and surrounds the first post hole to have a first opening direction on a second side, and the second winding wire of the second layer is located in the second winding post region of the second layer and surrounds the second post hole to have a second opening direction. The first winding wire of the second layer is electrically connected to the second winding wire of the second layer, and the first opening direction of the second layer is different from the second opening direction of the second layer.

[0005] According to some embodiments, the first winding wire of the first layer is located on a first side of the first post hole, and the second winding wire of the first layer is located on a second side of the second post hole. The first winding wire of the second layer is located on a second side of the first post hole, and the second winding wire of the second layer is located on a first side of the second post hole. The first side of the first post hole is opposite to the second side of the first post hole. The first side of the second post hole is opposite to the second side of the second post hole.

[0006] According to some embodiments, each of the winding layers includes a first extending region and a second extending region. The circuit board includes a second via hole passing through the second extending regions. The first winding of the first layer extends to the first extending region of the first layer. The second winding of the first layer and the second winding of the second layer are electrically connected through the second via hole. The first winding of the second layer extends to the first extending region of the second layer.

[0007] According to some embodiments, the winding layers further include a third layer. The third layer includes a first winding and a second winding. The first winding of the third layer is located in the first post region of the third layer and surrounds the first post hole with a first opening direction. The second winding of the third layer is located in the second post region of the third layer and surrounds the second post hole with a second opening direction. The first winding of the third layer is electrically connected to the second winding of the third layer. The first opening direction of the third layer is different from the second opening direction of the third layer.

[0008] According to some embodiments, the circuit board includes a first via hole and a second via hole. The first via hole passes through the first extending regions, and the second via hole passes through the second extending regions. The first winding of the first layer extends to the first extending region of the first layer. The second winding of the first layer and the second winding of the second layer are electrically connected through the second via hole. The first winding of the second layer and the first winding of the third layer are electrically connected through the first via hole. The second winding of the third layer extends to the second extending region of the third layer.

[0009] In summary, according to some embodiments, the winding layers of the flat transformer include first and second windings in series. The opening directions of the first and second windings are different. The winding direction of the first winding around the first post hole is opposite to the winding direction of the second winding around the second post hole. Therefore, the designer can adjust the opening direction of the winding to match the high-voltage side circuit, the low-voltage side circuit, and the circuit layout requirements, increasing the flexibility of the design. In some embodiments, the via holes pass through the extending regions, and the windings of the multi-layer winding layers are electrically connected through the via holes. Therefore, the via holes do not need to be arranged in the post regions, making the circuit layout more flexible. In some embodiments, the via holes are through holes, so that the circuit board of the flat transformer has no buried via holes or blind via holes, and the manufacturing cost of the circuit board is lower, the yield is higher, and the reliability is higher. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 A perspective exploded view of a flat transformer according to some embodiments is shown;

[0011] Figure 2A A top view of two winding layers according to some embodiments is shown;

[0012] Figure 2B A top view of a winding layer is illustrated according to some embodiments;

[0013] Figure 2C The illustrations are based on some embodiments. Figure 2A and Figure 2B The winding layer is applied to Figure 1 A cross-sectional view of the magnetic core and magnetic pillars at position 2C-2C;

[0014] Figure 2D The illustration contains Figure 2A and Figure 2B Experimental waveform diagram of the circuit board with winding layer;

[0015] Figure 3A The illustration shows a top view of three winding layers, based on some embodiments.

[0016] Figure 3B The illustration contains Figure 3A and Figure 2B Experimental waveform diagram of the circuit board with winding layer;

[0017] Figure 4A The illustration shows a top view of three winding layers, based on some embodiments.

[0018] Figure 4B The illustration contains Figure 4A and Figure 2B Experimental waveform diagram of the circuit board with winding layer;

[0019] Figure 5A A top view of a winding layer is illustrated according to some embodiments;

[0020] Figure 5B The illustration contains Figure 5A and Figure 2B Experimental waveform diagram of the circuit board with winding layer;

[0021] Figure 6 The illustration shows a top view of two winding layers, based on some embodiments;

[0022] Figure 7 An exploded perspective view of a planar transformer is shown based on some embodiments;

[0023] Figure 8 Draw Figure 7 A top view of each winding layer of the circuit board in an embodiment;

[0024] Figure 9 Draw Figure 7 A circuit functional block diagram of a planar transformer in an embodiment;

[0025] Figure 10 An exploded perspective view of a planar transformer is shown based on some embodiments;

[0026] Figure 11 FIG. 1 illustrates a perspective exploded view of a planar transformer according to some embodiments; and Figure 10 FIG. 2 illustrates a circuit functional block diagram of a planar transformer according to some embodiments.

[0027] Figure 12 FIG. 3 illustrates a perspective exploded view of a planar transformer according to some embodiments; and

[0028] Figure 13 FIG. 4 illustrates a circuit functional block diagram of a planar transformer according to some embodiments. Figure 12

[0029]

Symbol Description

[0030] 100: circuit board

[0031] 101, 102, 201, 202, 301, 302: first post hole, second post hole

[0032] 101a, 102a: first side

[0033] 101b, 102b: second side

[0034] 106, 106m, 107, 107m: guide hole

[0035] 110, 120, 130, 150, 160: winding layer, first layer, second layer, third layer

[0036] 110m, 120m, 130m, 110r, 120r: first layer, second layer, third layer

[0037] 111, 121, 131, 161: first winding post area

[0038] 112, 122, 132, 162: second winding post area

[0039] 113, 123, 133, 113m, 123m, 133m, 163: first extension area

[0040] 114, 124, 134, 114m, 124m, 134m, 164: second extension area

[0041] 116, 126, 136, 116m, 126m, 136m, 166, 116r, 126r: first wire winding

[0042] 116a, 126a, 136a, 166a: first opening direction

[0043] 116b, 116c: end point

[0044] ​117, 127, 137, 117m, 127m, 137m, 167, 117r, 127r: second winding

[0045] 117a, 127a, 137a, 167a: second opening direction

[0046] 190: Nth layer

[0047] 191, 192: first insulating layer, second insulating layer

[0048] 197: second winding

[0049] 200: circuit board

[0050] 201, 202: first hole, second hole

[0051] 206a, 206b, 207: through hole

[0052] 210, 220, 230, 240: first layer, second layer, third layer, fourth layer

[0053] 216, 226, 236, 246: first winding

[0054] 217, 227, 237, 247: second winding

[0055] 291, 292, 293: first insulating layer, second insulating layer, third insulating layer

[0056] 300: circuit board

[0057] 301, 302: first hole, second hole

[0058] 306a, 306b, 306c, 307a, 307b: through hole

[0059] 308c, 308d, 308e, 308f: through hole

[0060] 310, 320, 330, 340, 350, 360, 370, 380: first layer, second layer, third layer, fourth layer, fifth layer, sixth layer, seventh layer, eighth layer

[0061] 316, 326, 336, 346, 356, 366, 376, 386: first winding

[0062] 317, 327, 337, 347, 357, 367, 377, 387: second winding

[0063] 391, 392, 393, 394, 395, 396, 397: first, second, third, fourth, fifth, sixth, seventh insulating layers

[0064] 400: circuit board

[0065] 401, 402: first, second column holes

[0066] 406a, 406b, 407a, 407b: guide holes, sub-guide holes

[0067] 408c, 408d, 408e, 408f: guide holes

[0068] 410, 420, 430, 440, 450, 460, 470, 480: first, second, third, fourth, fifth, sixth, seventh, eighth layers

[0069] 416, 426, 436, 446, 456, 466, 476, 486: first windings

[0070] 417, 427, 437, 447, 457, 467, 477, 487: second windings

[0071] 491, 492, 493, 494, 495, 496, 497: first, second, third, fourth, fifth, sixth, seventh insulating layers

[0072] 80, 82: first, second magnetic cores

[0073] 84, 84a, 84b, 86, 86a, 86b: first magnetic column, first sub-magnetic column, second magnetic column, second sub-magnetic column

[0074] 88: closed magnetic circuit

[0075] 90: high-voltage side circuit

[0076] 92: low-voltage side circuit

[0077] 94: input power supply

[0078] 96: load

[0079] 98a, 98b, 98c, 98d, 98e, 98f, 98g, 98h: synchronous rectification circuits

[0080] T H ,T H 1,T H 2,T LHigh-voltage side coil, first coil, second coil, low-voltage side coil 1 DETAILED DESCRIPTION

[0081] Please refer to Figure 1 and Figure 2A , Figure 1 A perspective exploded view of a planar transformer is shown in accordance with some embodiments, Figure 2A A top view of two winding layers is shown in accordance with some embodiments, Figure 2A The two winding layers stacked on top of each other are shown in a side-by-side manner. The planar transformer includes a circuit board 100. The circuit board 100 includes a plurality of winding layers 110, 120, 150, a first post hole 101, and a second post hole 102. Each of the winding layers 110, 120 includes a first winding post region 111, 121 and a second winding post region 112, 122. The first post hole 101 passes through the first winding post regions 111, 121, and the second post hole 102 passes through the second winding post regions 112, 122.

[0082] Figure 2A In the illustrated embodiment, the circuit board 100 includes two winding layers 110, 120. The winding layers 110, 120 include a first layer 110 and a second layer 120 (also referred to as a first winding layer and a second winding layer, respectively, hereinafter, without further elaboration). The first layer 110 includes a first winding 116 and a second winding 117. The first winding 116 of the first layer 110 is located in the first winding post region 111 of the first layer 110 and surrounds the first post hole 101 with a first opening direction 116a. The second winding 117 of the first layer 110 is located in the second winding post region 112 of the first layer 110 and surrounds the second post hole 102 with a second opening direction 117a. The first winding 116 of the first layer 110 is electrically connected to the second winding 117 of the first layer 110. The first opening direction 116a of the first layer 110 is different from the second opening direction 117a of the first layer 110. The second layer 120 includes a first winding 126 and a second winding 127. The first winding 126 of the second layer 120 is located in the first winding post region 121 of the second layer 120 and surrounds the first post hole 101 with a first opening direction 126a. The second winding 127 of the second layer 120 is located in the second winding post region 122 of the second layer 120 and surrounds the second post hole 102 with a second opening direction 127a. The first winding 126 of the second layer 120 is electrically connected to the second winding 127 of the second layer 120, and the first opening direction 126a of the second layer 120 is different from the second opening direction 127a of the second layer 120.

[0083] The aforementioned winding column regions 111, 112, 121, 122 refer to regions for the winding wires 116, 117, 126, 127 to loop around, and the winding column regions 111, 112, 121, 122 are located around the column holes 101, 102. Figure 2A In the embodiment, the winding column regions 111, 112, 121, 122 are rectangular, but the shape of the winding column regions 111, 112, 121, 122 is not limited thereto, and the winding column regions 111, 112, 121, 122 can also be circular, elliptical, or irregular shapes that loop around the column holes 101, 102. The winding wires 116, 117, 126, 127 loop around the column holes 101, 102 in the winding column regions 111, 112, 121, 122 and have an opening, and thus the angle of each winding wire 116, 117, 126, 127 looping around the column holes 101, 102 can be from 10 degrees to close to 360 degrees (to be described later), depending on the needs of the wiring plan, such as but not limited to the wiring plan needs of electrical connection between the two winding layers, or the wiring plan needs of the winding wires electrically connected to the high-voltage side circuit or the low-voltage side circuit (to be described later in detail).

[0084] The aforementioned first opening direction 116a of the first winding wire 116 of the first layer 110 refers to the opening direction of the arc formed by the first winding wire 116. The arc is the arc (also referred to as the looped arc) formed by the first winding wire 116 looping around the first column hole 101. The looped arc has two endpoints 116b, 116c, which can be the intersection of the first winding wire 116 and the first winding column region 111, or the actual opening endpoints of the first winding wire 116 (to be described later). The line connecting the two endpoints 116b, 116c is the chord of the first winding wire 116, and the first opening direction 116a of the first winding wire 116 is the direction perpendicular to the chord of the first winding wire 116, passing through the midpoint of the chord and facing outward. The meaning of the second opening direction 117a of the first layer 110, the first opening direction 126a of the second layer 120, and the second opening direction 127a of the second layer 120 is the same, and thus will not be described again.

[0085] Secondly, for each layer 110, 120, the winding direction of its first winding 116, 126 is opposite to the winding direction of its second winding 117, 127. That is, the first winding 116 of the first layer 110 is electrically connected to the second winding 117 of the first layer 110, and the first winding 126 of the second layer 120 is electrically connected to the second winding 127 of the second layer 120. Therefore, the first winding 116, 126 and the second winding 117, 127 of each layer 110, 120 are in series. If current is input to one end of the series connection and current flows out of the other end, then for each layer 110, 120, the winding direction of its first winding 116, 126 is opposite to the winding direction of its second winding 117, 127. For example, if current is input to the first winding 116 of the first layer 110 and output to the second winding 117 of the first layer 110, then the winding direction of the first winding 116 of the first layer 110 is clockwise (based on...). Figure 2A (viewpoint), while the second winding 117 of the first layer 110 is wound counterclockwise (based on...) Figure 2A (View angle), the two winding directions are opposite. Similarly, the winding direction of the first winding 126 of the second layer 120 is opposite to the winding direction of the second winding 127 of the second layer 120.

[0086] exist Figure 2A In the embodiment, the first opening direction 116a of the first layer 110 is generally oriented towards Figure 2A From the right side of the viewpoint, the second opening 117a of the first layer 110 roughly faces... Figure 2A From the upper left of the viewpoint, the two are different. The first opening 126a of the second layer 120 is roughly oriented towards... Figure 2A From the left side of the viewpoint, the second opening 127a of the second layer 120 generally faces... Figure 2A From the right side of the viewpoint, the two are different. In addition, the surrounding arcs formed by the first winding 116 of the first layer 110, the second winding 117 of the first layer 110, the first winding 126 of the second layer 120, and the second winding 127 of the second layer 120 can be designed as needed, and the lengths of these surrounding arcs can be the same or different (details to follow).

[0087] According to some embodiments, the first winding 116 of the first layer 110 is located on a first side 101a of the first post hole 101. The second winding 117 of the first layer 110 is located on a second side 102b of the second post hole 102. The first winding 126 of the second layer 120 is located on a second side 101b of the first post hole 101. The second winding 127 of the second layer 120 is located on a first side 102a of the second post hole 102. The first side 101a of the first post hole 101 is opposite to the second side 101b of the first post hole 101. The first side 102a of the second post hole 102 is opposite to the second side 102b of the second post hole 102.

[0088] In some embodiments, each winding layer 110, 120 is located on a surface of an insulating layer 191, 192 of the circuit board 100. Figure 2A In this embodiment, the first layer 110 is located on one surface of the first insulating layer 191, and the second layer 120 is located on the surface of the second insulating layer 192. However, this is not a limitation; the first layer 110 and the second layer 120 may be located on the upper and lower surfaces of the same insulating layer, respectively, for example... Figure 7 In this embodiment, the third layer 230 and the fourth layer 240 are located on the upper and lower surfaces of the third insulating layer 293, respectively (details to follow). Each winding region 111, 112, 121, 122 corresponds to the surface where the windings 116, 117, 126, 127 are located (or, the region of each winding region 111, 112, 121, 122 located on the surface where the windings 116, 117, 126, 127 are located). For example, the windings 116, 117 of the first layer 110 are located on the surface of the first insulating layer 191, and the winding regions 111, 112 of the first layer 110 correspond to this surface of the first insulating layer 191; the windings 126, 127 of the second layer 120 are located on the surface of the second insulating layer 192, and the winding regions 121, 122 of the second layer 120 correspond to this surface of the second insulating layer 192.

[0089] Please continue to refer to this. Figure 1 In some embodiments, the planar transformer includes a first magnetic core 80, a second magnetic core 82, a first magnetic post 84, and a second magnetic post 86. The first magnetic post 84 and the second magnetic post 86 are respectively connected to the first magnetic core 80. The first magnetic post 84, the first magnetic core 80, and the second magnetic post 86 are three independent elements connected in sequence, or a single element integrally formed. In some embodiments, the first magnetic post 84 and the second magnetic post 86 are respectively connected to the second magnetic core 82. The first magnetic post 84, the second magnetic core 82, and the second magnetic post 86 are three independent elements connected in sequence, or a single element integrally formed. In some embodiments, the first magnetic post 84 and the second magnetic post 86 are not connected to the first magnetic core 80 or the second magnetic core 82 (e.g., there is a small gap between the elements), but are both located between the first magnetic core 80 and the second magnetic core 82. In some embodiments (see reference...),Figure 7 ), the flat transformer comprises two first sub-magnetic columns 84a, 84b and two second sub-magnetic columns 86a, 86b, the two first sub-magnetic columns 84a, 84b are substantially coaxially arranged, and the two second sub-magnetic columns 86a, 86b are substantially coaxially arranged. The first sub-magnetic column 84a, the first magnetic core 80, and the second sub-magnetic column 86a are three independent elements connected in sequence or a single element integrally formed. The first sub-magnetic column 84b, the second magnetic core 82, and the second sub-magnetic column 86b are three independent elements connected in sequence or a single element integrally formed.

[0090] In some embodiments, each of the winding layers 110, 120, 150 comprises a first extension region 113, 123 and a second extension region 114, 124. The first wire 116 of the first layer 110 extends to the first extension region 113 of the first layer 110, and the first wire 126 of the second layer 120 extends to the first extension region 123 of the second layer 120. In this way, the flat transformer can be electrically connected to the outside of the circuit board 100 or to an electronic element through the first wire 116, 126 located in the first extension region 113, 123. Similarly, the second wire 117 of the first layer 110 extends to the second extension region 114 of the first layer 110, and the second wire 127 of the second layer 120 extends to the second extension region 124 of the second layer 120, and the use thereof will not be described again.

[0091] In some embodiments, the line connecting the center of the first column hole 101 and the center of the second column hole 102 passes through the first extension region 113 and the second extension region 114, and the first extension region 113, the first winding column region 111, the second winding column region 112, and the second extension region 114 are sequentially arranged.

[0092] In some embodiments, the circuit board 100 comprises a second through hole 107 passing through (or located in) the second extension regions 114, 124, and the second wire 117 of the first layer 110 and the second wire 127 of the second layer 120 are electrically connected through the second through hole 107. In some embodiments, the second wire 117 of the first layer 110 extends to the second extension region 114 of the first layer 110 to be electrically connected to the second through hole 107, and the second wire 127 of the second layer 120 extends to the second extension region 124 of the second layer 120 to be electrically connected to the second through hole 107 (as shown in Figure 2A In some embodiments, the second through hole 107 is located adjacent to the second winding column region 112, 122 of the second extension region 114, 124, or is located at the boundary of the second extension region 114, 124 adjacent to the circuit board 100 (as shown in Figure 2A(See the top side of the view), and the second winding 117 of the first layer 110 and the second winding 127 of the second layer 120 extend to the corresponding second extension areas 114, 124 depending on the position of the second guide hole 107. In this embodiment, the second guide hole 107 is only located in the second extension areas 114, 124, and there are no guide holes in the winding areas 111, 112, 121, 122.

[0093] Please refer to some embodiments. Figure 2A The first winding 116 of the first layer 110, the second winding 117 of the first layer 110, the second winding 127 of the second layer 120, and the first winding 126 of the second layer 120 are connected in series. The first winding 116 of the first layer 110 extends to the portion of the first extension area 113 of the first layer 110, and the first winding 126 of the second layer 120 extends to the portion of the first extension area 123 of the second layer 120 (e.g., Figure 2A The two arrows shown below (the arrow direction indicates the possible direction of current flow) can be used to electrically connect to the outside of the circuit board 100 or to electronic components.

[0094] In this embodiment, the second winding 117 of the first layer 110 and the second winding 127 of the second layer 120 are electrically connected through the second guide hole 107. The first windings 116 and 126 corresponding to the first post hole 101 have the same winding direction, and the second windings 117 and 127 corresponding to the second post hole 102 have the same winding direction, but the winding directions of the first windings 116 and 126 are opposite to those of the second windings 117 and 127. For example, current is input through the first winding 116 of the first layer 110 (…). Figure 2A (The large upward arrow) indicates that the current sequentially passes through the second winding 117 of the first layer 110, the second guide hole 107, the second winding 127 of the second layer 120, and the first winding 126 of the second layer 120 (current flows from...). Figure 2A Output at the large downward arrow). From Figure 2A It can be seen (based on) Figure 2A From a certain perspective, the winding direction (clockwise) of the first winding 116 of the first layer 110 is the same as the winding direction (clockwise) of the first winding 126 of the second layer 120; the winding direction (counterclockwise) of the second winding 117 of the first layer 110 is the same as the winding direction (counterclockwise) of the second winding 127 of the second layer 120. Thus, please refer to... Figure 2C , Figure 2C The illustrations are based on some embodiments. Figure 2A and Figure 2B The winding layer is applied to Figure 1Figure 2C is a cross-sectional view of the magnetic core and magnetic columns at the 2C-2C position. The current enters the paper on the left side of the first magnetic column 84, exits the paper between the first magnetic column 84 and the second magnetic column 86, and enters the paper on the right side of the second magnetic column 86. By virtue of the design that the winding direction of the same magnetic column 84, 86 is the same and the winding direction of the different magnetic columns 84, 86 is different, the two ends of the series-connected windings 116, 117, 126, 127 form a closed magnetic circuit 88 after the input of the current.

[0095] In addition, from Figure 2A It can be seen that the first winding 116 and the second winding 117 of the first layer 110 form a first line shape, which is substantially S-shaped (or reverse S-shaped). The first winding 126 and the second winding 127 of the second layer 120 form a second line shape. The second line shape is substantially complementary to the first line shape. Here, the line shape complementation does not require that the windings of the two layers connected in series form a circle after being stacked, but the windings of the two layers stacked can also be an arc with a predetermined angle having an opening. For example, in the embodiment of Figure 2A For example, in the embodiment of the circuit board 100, if the first layer 110 and the second layer 120 are stacked (the first column hole 101 and the second column hole 102 are through holes), the first windings 116, 126 of the stacked first layer 110 and the second layer 120 are substantially a circle around the first column hole 101, and the second windings 117, 127 of the stacked first layer 110 and the second layer 120 are substantially a circle around the second column hole 102.

[0096] Please refer to Figure 2A , Figure 2B , Figure 2C and Figure 2D , Figure 2B Figure 1A shows a top view of a winding layer according to some embodiments. Figure 2D Figure 2A shows a top view of a winding layer according to some embodiments. Figure 2A and Figure 2B Figure 3 shows an experimental waveform diagram of a circuit board including winding layers. According to some embodiments, the flat transformer includes a first magnetic core 80, a second magnetic core 82, a first magnetic column 84, a second magnetic column 86, and a circuit board 100. The winding layers of the circuit board 100 include a first layer 110, a second layer 120, and an Nth layer 190. From Figure 2B It can be seen that the Nth layer 190 includes a second winding 197, and the Nth layer 190 second winding 197 surrounds the second column hole 102. The second winding 117 of the first layer 110 is electrically connected to the second winding 127 of the second layer 120 through the second guide hole 107. The two ends of the windings 116, 117, 126, 127 of the first layer 110 and the second layer 120 are used as input terminals of the high-voltage side, and a high-voltage current is input at the input terminals. Figure 2DAC voltage represented by a dotted line. The second winding 197 of the Nth layer 190 is on the low voltage side and measures the output signal of the second winding 197 of the Nth layer 190. According to experimental tests, the output signal is Figure 2D AC voltage represented by a dotted line. Figure 2D The horizontal axis is time in seconds (s) and the vertical axis is voltage in volts (V). From Figure 2D It can be seen that the peak to peak voltage of the input signal is about 18.96 V and the peak to peak voltage of the output signal is about 9.7 V. From Figure 2D It can be known that the turns ratio of the high voltage side to the low voltage side is about 2:1.

[0097] Please refer to Figure 3A , Figure 3A a top view of three winding layers according to some embodiments, Figure 3A The three sequentially stacked winding layers are shown in a side-by-side manner. The winding layers of the circuit board 100 include a first layer 110, a second layer 120, and a third layer 130 (also referred to as a third winding layer). The third layer 130 includes a first winding 136 and a second winding 137. The first winding 136 of the third layer 130 is located in the first winding column region 131 of the third layer 130 and surrounds the first column hole 101 with a first opening direction 136a. The second winding 137 of the third layer 130 is located in the second winding column region 132 of the third layer 130 and surrounds the second column hole 102 with a second opening direction 137a. The first winding 136 of the third layer 130 is electrically connected to the second winding 137 of the third layer 130. The first opening direction 136a of the third layer 130 is different from the second opening direction 137a of the third layer 130.

[0098] In Figure 3A some embodiments, the first winding 136 of the third layer 130 is located on the first side 101a of the first column hole 101, and the second winding 137 of the third layer 130 is located on the second side 102b of the second column hole 102.

[0099] In some embodiments, the circuit board 100 includes a first via 106 and a second via 107, the first via 106 passing through the first extension regions 113, 123, 133, the second via 107 passing through the second extension regions 114, 124, 134, the first winding 116 of the first layer 110 extending to the first extension region 113 of the first layer 110, the second winding 117 of the first layer 110 and the second winding 127 of the second layer 120 electrically connected through the second via 107, the first winding 126 of the second layer 120 and the first winding 136 of the third layer 130 electrically connected through the first via 106, and the second winding 137 of the third layer 130 extending to the second extension region 134 of the third layer 130. Thus, the first winding 116 of the first layer 110, the second winding 117 of the first layer 110, the second winding 127 of the second layer 120, the first winding 126 of the second layer 120, the first winding 136 of the third layer 130, and the second winding 137 of the third layer 130 of the circuit board 100 are connected in series.

[0100] In some embodiments, referring to Figure 3A , the first winding 126 of the second layer 120 extends to the first extension region 123 of the second layer 120 to electrically connect the first via 106, and the first winding 136 of the third layer 130 extends to the first extension region 133 of the third layer 130 to electrically connect the first via 106. The second winding 137 of the third layer 130 extends to the second extension region 134 of the third layer 130 to electrically connect the electronic component. In this embodiment, the vias 106, 107 are plated through holes and are only located in the extension regions 113, 114, 123, 124, 133, 134, and there are no vias in the winding regions 111, 112, 121, 122, 131, 132.

[0101] Referring to Figure 3B , Figure 3B , the circuit board includes Figure 3A and Figure 2B winding layers. The winding layers of the circuit board 100 include the first layer 110, the second layer 120, the third layer 130, and the Nth layer 190. The two ends of the windings 116, 117, 126, 127, 136, 137 of the first layer 110, the second layer 120, and the third layer 130 connected in series are used as the input end of the high-voltage side, and an alternating current represented by a solid line in Figure 3B is input to the input end. The second winding 197 of the Nth layer 190 is used as the low-voltage side, and the output signal of the second winding 197 of the Nth layer 190 is measured. Through experimental testing, the output signal is an alternating current represented by a dotted chain line in Figure 3B . From Figure 3BIt can be seen that the peak voltage of the input signal is about 21.22V, and the peak voltage of the output signal is about 7.2V. From Figure 3B It can be seen that the turns ratio of the high-voltage side to the low-voltage side is about 3:1. In some embodiments, the circuit board 100 includes four or more winding layers, such as Figure 7 or Figure 10 embodiments.

[0102] Each via hole 106, 107 is used to electrically connect the windings located in different layers and connected with each other. Each via hole 106, 107 can be a plated through hole, a blind via hole, or a buried via hole. For example, Figure 2A and Figure 3A The second via hole 107 shown is a plated through hole; in implementation, the second via hole 107 can be a blind via hole. When the via hole 106, 107 is a plated through hole, the process is easier, the yield is higher, and the cost is lower. The via hole 106, 107 is located in the extension area 113, 114, 123, 124, 133, 134, and the winding area 111, 112, 121, 122, 131, 132 of the circuit board 100 is only configured with windings 116, 117, 126, 127, 136, 137, without any plated through hole, blind via hole, or buried via hole, so that the winding design is more convenient, and the yield is improved.

[0103] Please refer to Figure 4A , Figure 4A Fig. 3 shows a top view of three winding layers according to some embodiments, Figure 4A The three sequentially stacked winding layers are shown in a side-by-side manner. Figure 4A The winding layers include a first layer 110m, a second layer 120m, and a third layer 130m. The first winding 116m of the first layer 110m is electrically connected to the second winding 117m of the first layer 110m. The first opening direction 116a of the first winding 116m of the first layer 110m is Figure 4A the upper right of the perspective view, and the second opening direction 117a of the second winding 117m of the first layer 110m is Figure 4A the lower left of the perspective view, which are different.

[0104] The first winding 126m of the second layer 120m is electrically connected to the second winding 127m of the second layer 120m. The first opening direction 126a of the first winding 126m of the second layer 120m is Figure 4A the lower left of the perspective view, and the second opening direction 127a of the second winding 127m of the second layer 120m is Figure 4A the upper right of the perspective view, which are different.

[0105] The first winding 136m of the third layer 130m is electrically connected to the second winding 137m of the third layer 130m. The first opening direction 136a of the first winding 136m of the third layer 130m is Figure 4A The second opening direction 137a of the second winding 137m of the third layer 130m is Figure 4A from the perspective of the upper right, the lower left from the perspective of the left, and both are different.

[0106] Please refer to Figure 4A In some embodiments, the first extension area 113m, 123m, 133m and the second extension area 114m, 124m, 134m are respectively located on the opposite sides of the line connecting the center of the first column hole 101 and the center of the second column hole 102 Figure 4A from the perspective of the left and right sides of the column hole center line). The first extension area 113m, 123m, 133m corresponds to the first column hole 101, and the second extension area 114m, 124m, 134m corresponds to the second column hole 102. The first guide hole 106m passes through the first extension area 113m, 123m, 133m, the second guide hole 107m passes through the second extension area 114m, 124m, 134m, the first winding 116m of the first layer 110m extends to the first extension area 113m of the first layer 110m, the second winding 117m of the first layer 110m and the second winding 127m of the second layer 120m are electrically connected through the second guide hole 107m, the first winding 126m of the second layer 120m and the first winding 136m of the third layer 130m are electrically connected through the first guide hole 106m, and the second winding 137m of the third layer 130m extends to the second extension area 134m of the third layer 130m. Therefore, the first winding 116m of the first layer 110m, the second winding 117m of the first layer 110m, the second winding 127m of the second layer 120m, the first winding 126m of the second layer 120m, the first winding 136m of the third layer 130m and the second winding 137m of the third layer 130m are sequentially connected in series. In this embodiment, the first guide hole 106m is a blind hole and is located only in the first extension area 123m of the second layer 120m and the first extension area 133m of the third layer 130m, and the second guide hole 107m is a blind hole and is located only in the second extension area 114m of the first layer 110m and the second extension area 124m of the second layer 120m.

[0107] Please refer to Figure 4B , Figure 4B The drawing includes Figure 4A and Figure 2BExperimental waveform diagram of the circuit board of the winding layer. The winding layer of the circuit board 100 comprises a first layer 110m, a second layer 120m, a third layer 130m and an Nth layer 190. The two ends of the windings 116, 117, 126, 127, 136, 137 of the first layer 110m, the second layer 120m and the third layer 130m in series are taken as the input end of the high-voltage side, and an alternating current in solid line is input to the input end Figure 4B . The second winding 197 of the Nth layer 190 is taken as the low-voltage side, and the output signal of the second winding 197 of the Nth layer 190 is measured. Through experimental testing, the output signal is an alternating current in dotted chain line Figure 4B . It can be seen from Figure 4B that the peak voltage of the input signal is about 19.97V, and the peak voltage of the output signal is about 6.82V. It can be known from Figure 4B that the turns ratio of the high-voltage side to the low-voltage side is about 3:1.

[0108] Comparing the total arc length (or total arc angle) of the winding in series Figure 3A and Figure 4A , Figure 4A the total arc length (or total arc angle) of the winding in series is greater than Figure 3A the total arc length (or total arc angle) of the winding in series. However, the windings in series of Figure 3A and Figure 4A are taken as the high-voltage side winding respectively, and the second winding 197 of Figure 2B is taken as the corresponding low-voltage side winding. Through experiments, the turns ratio of the high-voltage side to the low-voltage side of the three is about 3:1. It is obvious that the turns ratio has a greater correlation with the winding passing through the aforementioned closed magnetic path 88 (see Figure 2C ), and has little correlation with the total arc length (or total arc angle) of the winding not passing through the closed magnetic path 88. Through the experiments, the user can flexibly design the location of the extension area to match the flat transformer electronic components and the electrical connection mode. For example, the first extension area 113 is selectively designed at the left side, the lower side (as shown in Figure 2A ), or the right side (as shown in Figure 4A ) of the first winding column area 111, and the second extension area 114 is selectively designed at the left side (as shown in Figure 4A ), the upper side (as shown in Figure 2A ), or the right side of the second winding column area 112. In some embodiments, the extension area is provided with a guide hole or a wire for electrical connection with the high-voltage side circuit, the low-voltage side circuit and the circuit layout, and therefore, the flexibility of the extension area configuration position makes the circuit design more convenient.

[0109] Please refer to Figure 5A , Figure 5A a top view of a winding layer according to some embodiments is shown. Figure 5AThe winding layer 160 comprises a first winding 166 and a second winding 167. The first winding 166 surrounds the first post hole 101 and has a first opening direction 166a. The second winding 167 surrounds the second post hole 102 and has a second opening direction 167a, which is different from the first opening direction 166a. The first winding 166 is electrically connected to the second winding 167. In some embodiments, the first extension region 163, the first post winding region 161, the second post winding region 162 and the second extension region 164 are sequentially adjacent. The first extension region 163 is located on a line (e.g., a line connecting the centers of the two post holes) between the first post hole 101 and the second post hole 102, and the second extension region 164 is not located on the line. In this embodiment (from the perspective of the view angle), the first extension region 163 is located on the lower side of the first post hole 101, and the second extension region 164 is located on the left side of the second post hole 102. Figure 5A

[0110] Please refer to Figure 5B , Figure 5B The experimental waveform diagram of the circuit board comprising the winding layer is shown in Figure 5A and Figure 2B . The winding layer of the circuit board 100 comprises the first layer 110 and the Nth layer 190. The two ends of the windings 116, 117 of the first layer 110 in series are used as the input end of the high-voltage side, and the alternating current shown in solid lines in Figure 5B is input. The second winding 197 of the Nth layer 190 is used as the low-voltage side, and the output signal of the second winding 197 of the Nth layer 190 is measured. Through experimental testing, the output signal is the alternating current shown in a dotted chain line in Figure 5B . It can be seen from Figure 5B that the peak voltage of the input signal is about 10.37V, and the peak voltage of the output signal is about 9.9V. It can be known from Figure 5B that the turns ratio of the high-voltage side to the low-voltage side is about 1:1. It can be seen from Figure 5A that Figure 5A the total arc length of the surrounding arcs of the first winding 166 and the second winding 167 is greater than one turn, and the turns ratio of the experimental result is about 1:1. The experimental result verifies that the turns ratio is closely related to the winding passing through the closed magnetic circuit 88 (see Figure 2C ). According to some embodiments, the winding layer of the circuit board further comprises a turning region (not shown in the figure), which is located between the first post winding region and the second post winding region. The winding layer comprises the first winding, a connecting segment (not shown in the figure) and the second winding which are sequentially connected. This embodiment is applicable to the case where the distance between the first post hole 101 and the second post hole 102 is far.

[0111] The winding in the foregoing embodiments is a linear conductor, such as a linear copper foil. However, it is not limited thereto, and the winding can also be a sheet conductor, such as a sheet copper foil. Please refer to Figure 6 ,​Figure 6 Fig. 2 illustrates a top view of two winding layers according to some embodiments, Figure 6 Fig. 3 illustrates a top view of two winding layers according to some embodiments, Figure 6 Fig. 4 illustrates a top view of two winding layers according to some embodiments, Figure 6 The winding layer 100r comprises a first layer 110r and a second layer 120r. The first winding 116r of the first layer 110r encircles the first post hole 101 and has a first opening direction 116a. The second winding 117r of the first layer 110r encircles the second post hole 102 and has a second opening direction 117a. As mentioned above, the encircling arc formed by the first winding 116r has two end points 116b, 116c (i.e. the end points of the opening of the encircling arc). The line connecting the two end points 116b, 116c is the chord of the first winding 116r, and the first opening direction 116a of the first winding 116r is the direction perpendicular to the chord of the first winding 116r, passing the midpoint of the chord and pointing outward. The first opening direction 116a of the first winding 116r is toward the right of the perspective view. Similarly, the second opening direction 117a of the second winding 117r of the first layer 110r is toward the left of the perspective view, which is different from the first opening direction 116a of the first winding 116r of the first layer 110r. Figure 6 The first winding 126r of the second layer 120r encircles the first post hole 101 and has a first opening direction 126a. The second winding 127r of the second layer 120r encircles the second post hole 102 and has a second opening direction 127a. The first opening direction 126a of the first winding 126r of the second layer 120r is toward the left of the perspective view. Similarly, the second opening direction 127a of the second winding 127r of the second layer 120r is toward the right of the perspective view, which is different from the first opening direction 126a of the first winding 126r of the second layer 120r. Figure 6 The first winding 126r of the second layer 120r encircles the first post hole 101 and has a first opening direction 126a. The second winding 127r of the second layer 120r encircles the second post hole 102 and has a second opening direction 127a. The first opening direction 126a of the first winding 126r of the second layer 120r is toward the left of the perspective view. Similarly, the second opening direction 127a of the second winding 127r of the second layer 120r is toward the right of the perspective view, which is different from the first opening direction 126a of the first winding 126r of the second layer 120r.

[0112] The first winding 126r of the second layer 120r encircles the first post hole 101 and has a first opening direction 126a. The second winding 127r of the second layer 120r encircles the second post hole 102 and has a second opening direction 127a. The first opening direction 126a of the first winding 126r of the second layer 120r is toward the left of the perspective view. Similarly, the second opening direction 127a of the second winding 127r of the second layer 120r is toward the right of the perspective view, which is different from the first opening direction 126a of the first winding 126r of the second layer 120r. Figure 6 The first winding 126r of the second layer 120r encircles the first post hole 101 and has a first opening direction 126a. The second winding 127r of the second layer 120r encircles the second post hole 102 and has a second opening direction 127a. The first opening direction 126a of the first winding 126r of the second layer 120r is toward the left of the perspective view. Similarly, the second opening direction 127a of the second winding 127r of the second layer 120r is toward the right of the perspective view, which is different from the first opening direction 126a of the first winding 126r of the second layer 120r. Figure 6 The first winding 126r of the second layer 120r encircles the first post hole 101 and has a first opening direction 126a. The second winding 127r of the second layer 120r encircles the second post hole 102 and has a second opening direction 127a. The first opening direction 126a of the first winding 126r of the second layer 120r is toward the left of the perspective view. Similarly, the second opening direction 127a of the second winding 127r of the second layer 120r is toward the right of the perspective view, which is different from the first opening direction 126a of the first winding 126r of the second layer 120r.

[0113] The second winding 117r of the first layer 110r is electrically connected to the second winding 127r of the second layer 120r through the via hole 107. Therefore, Figure 6 The first winding 116r of the first layer 110r, the second winding 117r of the first layer 110r, the second winding 127r of the second layer 120r, and the first winding 126r of the second layer 120r of the embodiment are sequentially connected in series. In some embodiments, the via hole 107 used to electrically connect the second winding 117r of the first layer 110r and the second winding 127r of the second layer 120r is a single hole (such as the single conductive hole shown in Figure 2A ) or multiple holes (such as the two rows of conductive holes shown in Figure 6 ).

[0114] InFigure 6 In this embodiment, the first windings 116r and 126r corresponding to the first post hole 101 have the same winding direction, and the second windings 117r and 127r corresponding to the second post hole 102 have the same winding direction, but the winding directions of the first windings 116r and 126r are opposite to those of the second windings 117r and 127r. As described above, current is input to the first winding 116r of the first layer 110r, passes through the second guide hole 107, and is output to the first winding 126r of the second layer 120r (please refer to...). Figure 6 (The large arrow below) The winding direction of the first winding 116r of the first layer 110r and the first winding 126r of the second layer 120r is clockwise (based on...) Figure 6 (From a perspective), the second winding 117r of the first layer (110r) and the second winding 127r of the second layer (120r) are wound counterclockwise (based on...). Figure 6 (Perspective).

[0115] Please see Figure 7 , Figure 7 The diagram illustrates an exploded perspective view of a planar transformer according to some embodiments. The planar transformer includes a first magnetic core 80, a second magnetic core 82, two first sub-magnetic pillars 84a and 84b, two second sub-magnetic pillars 86a and 86b, and a circuit board 200. The circuit board 200 is a four-layer board and includes a first post hole 201 and a second post hole 202. The first sub-magnetic pillars 84a and 84b are located in the first post hole 201, while the second sub-magnetic pillars 86a and 86b are located in the second post hole 202. The circuit board 200, the first sub-magnetic pillars 84a and 84b, and the second sub-magnetic pillars 86a and 86b are located between the first magnetic core 80 and the second magnetic core 82. The circuit board 200 includes multiple winding layers 210, 220, 230, and 240. In this embodiment, the aforementioned four-layer board includes three insulating layers: a first insulating layer 291, a second insulating layer 292, and a third insulating layer 293. The circuit board 200 includes four winding layers: a first layer 210, a second layer 220, a third layer 230, and a fourth layer 240. A first insulating layer 291 is located between the first layer 210 and the second layer 220, a second insulating layer 292 is located between the second layer 220 and the third layer 230, and a third insulating layer 293 is located between the third layer 230 and the fourth layer 240. Therefore, the first layer 210 and the second layer 220 are located on the upper and lower surfaces of the first insulating layer 291, respectively, and the third layer 230 and the fourth layer 240 are located on the upper and lower surfaces of the third insulating layer 293, respectively.

[0116] Please also refer to Figure 7 and Figure 8 , Figure 8 Draw Figure 7 A top view of each winding layer of the circuit board in the embodiment. Figure 8The four overlapping winding layers are presented in a side-by-side manner (from...) Figure 7 (A bird's-eye view). Figure 8 In this embodiment, the third layer 230 is located on the upper surface of the third insulating layer 293, while the fourth layer 240 is located on the lower surface of the third insulating layer 293. To better present the fourth layer 240, [further details are needed]. Figure 8 Only the third layer 230 is shown on the third insulating layer 293, and the fourth layer is presented separately in a top view and described together. The first winding 226 of the second layer 220 is electrically connected to the second winding 227 of the second layer 220. The first winding 236 of the third layer 230 is electrically connected to the second winding 237 of the third layer 230. The second winding 227 of the second layer 220 and the second winding 237 of the third layer 230 are electrically connected through the second via 207. Therefore, the first winding 226, the second winding 227, the second winding 237, and the first winding 236 of the third layer 230 are connected in series. In some embodiments, the first vias 206a, 206b and the second via 207 are through holes. The first windings 226 and 236 of the second layer 220 and the third layer 230 are electrically connected to the first vias 206a and 206b, respectively, so as to electrically connect the two ends of the first windings 226 and 236 and the second windings 227 and 237 of the second layer 220 and the third layer 230 connected in series to the surface of the circuit board 200.

[0117] The first winding 216 and the second winding 217 of the first layer 210 respectively encircle the first post hole 201 and the second post hole 202. The first winding 216 of the first layer 210 is not electrically connected to the second winding 217 of the first layer 210. Therefore, the number of turns of the first winding 216 and the second winding 217 of the first layer 210 is essentially 1 turn each (with a very small opening). The first winding 246 and the second winding 247 of the fourth layer 240 respectively encircle the first post hole 201 and the second post hole 202. The first winding 246 of the fourth layer 240 is not electrically connected to the second winding 247 of the fourth layer 240. Therefore, the number of turns of the first winding 246 and the second winding 247 of the fourth layer 240 is essentially 1 turn each (with a very small opening). The windings 226, 227, 236, and 237 of the second layer 220 and the third layer 230 are the high-voltage side coil TH (see...). Figure 9 The windings 216, 217, 246, and 247 of the first layer 210 and the fourth layer 240 are low-voltage side coils TL. Therefore, the turns ratio of the high-voltage side coil TH to the low-voltage side coil TL is 2:1:1:1:1.

[0118] Please also refer to Figure 7 and Figure 9 , Figure 9 Draw Figure 7The circuit functional block diagram of the planar transformer in this embodiment is shown. The planar transformer further includes a high-voltage side circuit 90 and a low-voltage side circuit 92. The high-voltage side circuit 90 is adapted to receive an input power supply 94, which can be a DC power supply (such as...). Figure 9 (As shown) or AC power. The high-voltage side circuit 90 is adapted to convert the input power 94 into a predetermined AC power and input it to the high-voltage side coil TH. After receiving the AC power, the high-voltage side coil TH generates an induced current in the low-voltage side coil TL. The low-voltage side circuit 92 rectifies the induced current and outputs it to the load 96. The low-voltage side circuit 92 includes synchronous rectifier circuits 98a, 98b, 98c, 98d (i.e., the aforementioned electronic components), which are electrically connected to the first winding 216, the second winding 217 of the first layer 210, the first winding 246 and the second winding 247 of the fourth layer 240, respectively.

[0119] In some embodiments, please also refer to Figure 7 and Figure 8 The first winding 216 and the second winding 217 of the first layer 210 are located on the upper surface of the first insulating layer 291 and are electrically connected to the corresponding synchronous rectifier circuits 98a and 98b, respectively. The first winding 246 and the second winding 247 of the fourth layer 240 are located on the lower surface of the third insulating layer 293 and are electrically connected to the corresponding synchronous rectifier circuits 98c and 98d, respectively. Through the aforementioned electrical connections, a system is formed. Figure 9 The electrical connection relationship.

[0120] exist Figure 7 In some embodiments, the two synchronous rectifier circuits 98c and 98d corresponding to the fourth layer 240 and the two synchronous rectifier circuits 98a and 98b corresponding to the first layer 210 are located on opposite sides of the circuit board 200, but this is not a limitation. In some embodiments, the two synchronous rectifier circuits 98c and 98d and the other two synchronous rectifier circuits 98a and 98b are located on the same side of the circuit board 200 (i.e., Figure 7 (The left long side of the circuit board 200). In this embodiment, the opening direction of the first winding 246 and the second winding 247 of the fourth layer 240 is the same as the opening direction of the first winding 216 and the second winding 217 of the first layer 210 (towards...). Figure 7 (Top left side).

[0121] Please also refer to the following: Figure 7 and Figure 8When current flows from the first winding 226 of the second layer 220, through the second winding 227 of the second layer 220, the second winding 237 of the third layer 230, and out of the first winding 236 of the third layer 230, magnetic flux is generated in the first magnetic core 80, the first sub magnetic columns 84a, 84b, the second magnetic core 82, and the second sub magnetic columns 86a, 86b (i.e., the aforementioned closed magnetic path 88, see Figure 2C ), so that the first winding 216 of the first layer 210, the second winding 217 of the first layer 210, the first winding 246 of the fourth layer 240, and the second winding 247 of the fourth layer 240 generate induced current, which is rectified by the corresponding synchronous rectification circuits 98a, 98b, 98c, 98d and then output to the load 96.

[0122] Please refer to Figure 10 and Figure 11 , Figure 10 a perspective exploded view of a planar transformer according to some embodiments, Figure 11 a circuit function block diagram of the planar transformer of the embodiment of Figure 10 . The planar transformer includes a first magnetic core 80, a second magnetic core 82, two first sub magnetic columns 84a, 84b, two second sub magnetic columns 86a, 86b, and a circuit board 300. The circuit board 300 is an eight-layer board and includes a first column hole 301 and a second column hole 302. The first sub magnetic columns 84a, 84b and the second sub magnetic columns 86a, 86b are respectively located in the first column hole 301 and the second column hole 302. The circuit board 300 includes seven insulating layers and eight winding layers, which are, from top to bottom, a first layer 310 (first winding layer, referred to as the same below), a first insulating layer 391, a second layer 320, a second insulating layer 392, a third layer 330, a third insulating layer 393, a fourth layer 340, a fourth insulating layer 394, a fifth layer 350, a fifth insulating layer 395, a sixth layer 360, a sixth insulating layer 396, a seventh layer 370, a seventh insulating layer 397, and an eighth layer 380. The circuit board 300 includes three first lead holes 306a, 306b, 306c and two second lead holes 307a, 307b. The first lead holes 306a, 306b, 306c pass through a first extension area (not labeled in the figure), and the second lead holes 307a, 307b pass through a second extension area (not labeled in the figure). The first lead holes are respectively a first sub lead hole 306a, a second sub lead hole 306b, and a third sub lead hole 306c. The second lead holes are respectively a fourth sub lead hole 307a and a fifth sub lead hole 307b.

[0123] In this embodiment, the first winding 326 of the second layer 320 is electrically connected to the first sub via hole 306a, and the second winding 327 of the second layer 320 is electrically connected to the fourth sub via hole 307a. The first winding 336 of the third layer 330 is electrically connected to the second sub via hole 306b, and the second winding 337 of the third layer 330 is electrically connected to the fourth sub via hole 307a. The first winding 366 of the sixth layer 360 is electrically connected to the second sub via hole 306b, and the second winding 367 of the sixth layer 360 is electrically connected to the fifth sub via hole 307b. The first winding 376 of the seventh layer 370 is electrically connected to the third sub via hole 306c, and the second winding 377 of the seventh layer 370 is electrically connected to the fifth sub via hole 307b.

[0124] Therefore, the first winding 326 of the second layer 320, the second winding 327 of the second layer 320, the fourth sub via hole 307a of the second via hole, the second winding 337 of the third layer 330, the first winding 336 of the third layer 330, the second sub via hole 306b, the first winding 366 of the sixth layer 360, the second winding 367 of the sixth layer 360, the fifth sub via hole 307b of the second via hole, the second winding 377 of the seventh layer 370, and the first winding 376 of the seventh layer 370 are sequentially connected in series and form a high-voltage side coil TH, two ends of the high-voltage side coil TH being the first sub via hole 306a and the third sub via hole 306c, respectively. Therefore, according to the aforementioned experimental estimation, the total number of windings of the high-voltage side coil TH is about 4 turns.

[0125] The first layer 310 first and second windings 316, 317, the fourth layer 340 first and second windings 346, 347, the fifth layer 350 first and second windings 356, 357, and the eighth layer 380 first and second windings 386, 387 are low-voltage side coils TL, each of which has about 1 turn (with a very small opening). Therefore, according to the aforementioned experiment, the turns ratio of the high-voltage side coils TH and the low-voltage side coils TL is about 4:1:1:1:1:1:1:1:1. The high-voltage side circuit 90 is electrically connected to the first sub via hole 306a and the third sub via hole 306c. The four synchronous rectifier circuits 98a, 98b, 98c, 98d of the low-voltage side circuit 92 are respectively located on both sides of the upper surface of the first insulating layer 391, and the other four synchronous rectifier circuits 98e, 98f, 98g, 98h of the low-voltage side circuit 92 are respectively located on both sides of the lower surface of the seventh insulating layer 397. The synchronous rectifier circuits 98a, 98b, 98c, 98d, 98e, 98f, 98g, 98h are electrically connected to the windings 316, 317, 346, 347, 356, 357, 386, 387 of the corresponding low-voltage side coils TL. Specifically, the synchronous rectifier circuits 98a, 98b are electrically connected to the first layer 310 first and second windings 316, 317, the synchronous rectifier circuit 98c is electrically connected to the fourth layer 340 first winding 346 through the via hole 308c, the synchronous rectifier circuit 98d is electrically connected to the fourth layer 340 second winding 347 through the via hole 308d, the synchronous rectifier circuit 98e is electrically connected to the fifth layer 350 first winding 356 through the via hole 308e, the synchronous rectifier circuit 98f is electrically connected to the fifth layer 350 second winding 357 through the via hole 308f, and the synchronous rectifier circuits 98g, 98h are respectively electrically connected to the eighth layer 380 first and second windings 386, 387. Among them, the via hole 308c is not electrically connected to the eighth layer 380 first winding 386, the via hole 308d is not electrically connected to the eighth layer 380 second winding 387, the via hole 308e is not electrically connected to the first layer 310 first winding 316, and the via hole 308f is not electrically connected to the first layer 310 second winding 317.

[0126] Please also refer to Figure 12 and Figure 13 , Figure 12 a perspective exploded view of a planar transformer according to some embodiments is shown, Figure 13 a perspective view of a planar transformer according to some embodiments is shown, Figure 12FIG. 4 is a circuit function block diagram of a planar transformer of an embodiment. The planar transformer includes a first magnetic core 80, a second magnetic core 82, two first sub-magnetic columns 84a, 84b, two second sub-magnetic columns 86a, 86b, and a circuit board 400. The circuit board 400 is an eight-layer board and includes a first post hole 401 and a second post hole 402. The first sub-magnetic columns 84a, 84b and the second sub-magnetic columns 86a, 86b are located in the first post hole 401 and the second post hole 402, respectively. The circuit board 400 includes seven insulating layers and eight winding layers, in order from top to bottom, a first layer 410 (first winding layer, hereinafter referred to as the same), a first insulating layer 491, a second layer 420, a second insulating layer 492, a third layer 430, a third insulating layer 493, a fourth layer 440, a fourth insulating layer 494, a fifth layer 450, a fifth insulating layer 495, a sixth layer 460, a sixth insulating layer 496, a seventh layer 470, a seventh insulating layer 497, and an eighth layer 480. The circuit board includes two first lead holes 406a, 406b (which can be referred to as a first sub-lead hole 406a and a second sub-lead hole 406b, respectively) and two second lead holes 407a, 407b (which can be referred to as a fourth sub-lead hole 407a and a fifth sub-lead hole 407b, respectively). The two first lead holes 406a, 406b pass through a first extension area (not shown in the figure), and the two second lead holes 407a, 407b pass through a second extension area (not shown in the figure).

[0127] In this embodiment, the first winding 426 of the second layer 420 is electrically connected to one 406a (first sub-lead hole 406a) of the two first lead holes, and the second winding 427 of the second layer 420 is electrically connected to one 407a (fourth sub-lead hole 407a) of the two second lead holes. The first winding 436 of the third layer 430 is electrically connected to the other 406b (second sub-lead hole 406b) of the two first lead holes, and the second winding 437 of the third layer 430 is electrically connected to one 407a (fourth sub-lead hole 407a) of the two second lead holes. The first winding 466 of the sixth layer 460 is electrically connected to one 406a (first sub-lead hole 406a) of the two first lead holes, and the second winding 467 of the sixth layer 460 is electrically connected to the other 407b (fifth sub-lead hole 407b) of the two second lead holes. The first winding 476 of the seventh layer 470 is electrically connected to the other 406b (second sub-lead hole 406b) of the two first lead holes, and the second winding 477 of the seventh layer 470 is electrically connected to the other 407b (fifth sub-lead hole 407b) of the two second lead holes.

[0128] Therefore, the first winding 426, the second winding 427, and the second guide hole 407a of the second layer 420, the second winding 437, and the first winding 436 of the third layer 430 are sequentially electrically connected to form a first coil TH1. The two ends of the first coil TH1 are electrically connected to the two first guide holes 406a and 406b, respectively. Therefore, based on the aforementioned experiments, the total number of turns of the first coil TH1 is estimated to be approximately 2. Furthermore, the first winding 466, the second winding 467, and the second guide hole 407b of the sixth layer 460, the second winding 477, and the first winding 476 of the seventh layer 470 are sequentially electrically connected to form a second coil TH2. The two ends of the second coil TH2 are electrically connected to the two first guide holes 406a and 406b, respectively. Therefore, based on the aforementioned experiments, the total number of turns of the second coil TH2 is estimated to be approximately 2. The first coil TH1 and the second coil TH2 are connected in parallel through the two first guide holes 406a and 406b to form the high-voltage side coil TH.

[0129] The first layer 410, with first and second windings 416 and 417; the fourth layer 440, with first and second windings 446 and 447; the fifth layer 450, with first and second windings 456 and 457; and the eighth layer 480, with first and second windings 486 and 487, constitute the low-voltage side coil TL. Based on the aforementioned experiments, the number of turns in each layer is estimated to be approximately one turn (with a very small opening). Therefore, the turns ratio of the high-voltage side coil TH to the low-voltage side coil TL is 2:1:1:1:1 and 2:1:1:1:1. The high-voltage side circuit 90 is electrically connected to the two first vias 406a and 406b. The synchronous rectifier circuits 98a, 98b, 98c, and 98d of the low-voltage side circuit 92 are located on both sides of the upper surface of the first insulating layer 491, respectively. The other four synchronous rectifier circuits 98e, 98f, 98g, and 98h of the low-voltage side circuit 92 are located on both sides of the lower surface of the seventh insulating layer 497, respectively. These synchronous rectifier circuits 98a, 98b, 98c, 98d, 98e, 98f, 98g, and 98h are electrically connected to the windings 416, 417, 446, 447, 456, 457, 486, and 487 of the corresponding low-voltage side coil TL. Similar to... Figure 10 Implementation examples, Figure 12 The synchronous rectifier circuits 98c, 98d, 98e, and 98f are electrically connected to the corresponding windings 446, 447, 456, and 457 via 408c, 408d, 408e, and 408f, respectively, which will not be described in detail here.

[0130] Examples of implementations of the aforementioned first or second linear form that substantially exhibit an S-shape (or a reverse S-shape) include, but are not limited to, those described above. Figure 2A The first layer 110, the first and second windings 116, 117, Figure 2A The second layer 120, the first and second windings 126, 127,Figure 3A the first layer 110 first and second windings 116, 117, Figure 3A the second layer 120 first and second windings 126, 127, Figure 3A the third layer 130 first and second windings 136, 137, Figure 4A the first layer 110m first and second windings 116m, 117m, Figure 4A the second layer 120m first and second windings 126m, 127m, Figure 4A the third layer 130m first and second windings 136m, 137m, Figure 5A the first and second windings 166, 167, Figure 6 the first layer 110r first and second windings 116r, 117r, Figure 6 the second layer 120r first and second windings 126r, 127r, Figure 7 the second layer 220 first and second windings 226, 227, Figure 7 the third layer 230 first and second windings 236, 237, Figure 10 the second layer 320 first and second windings 326, 327, Figure 10 the third layer 330 first and second windings 336, 337, Figure 10 the sixth layer 360 first and second windings 366, 367, Figure 10 the seventh layer 370 first and second windings 376, 377, Figure 12 the second layer 420 first and second windings 426, 427, Figure 12 the third layer 430 first and second windings 436, 437, Figure 12 the sixth layer 460 first and second windings 466, 467, and Figure 12 the seventh layer 470 first and second windings 476, 477. Second, the direction of winding of the first winding is opposite the direction of winding of the second winding for the same layer in the foregoing embodiments.

[0131] In summary, in some embodiments, the winding layers of the flat transformer include first and second windings in series. The opening directions of the first and second windings are different. The winding direction of the first winding around the first post hole is opposite to the winding direction of the second winding around the second post hole. Therefore, the designer can adjust the opening direction of the winding to match the high-voltage side circuit, the low-voltage side circuit, and the circuit layout requirement, increasing the flexibility of the design. In some embodiments, the through holes pass through the extension area and the windings of the multi-layer winding layer are electrically connected through the through holes. The through holes do not need to be arranged in the post area, making the circuit layout more flexible. In some embodiments, the through holes are all through holes, so that the circuit board of the flat transformer has no buried via holes or blind via holes, and the circuit board has low manufacturing cost, high yield, and high reliability.

Claims

1. A flat-plate transformer, characterized in that, Include: A circuit board comprising multiple winding layers, a first post hole, a second post hole, two first vias, and a second via. Each winding layer comprises a first winding region, a second winding region, a first extension region, and a second extension region. The first post hole passes through the first winding regions, the second post hole passes through the second winding regions, the first vias pass through the first extension regions, and the second vias pass through the second extension regions. The winding layers comprise: A first layer includes a first winding and a second winding, wherein the first winding of the first layer is located in the first winding post area of ​​the first layer and surrounds the first post hole, and the second winding of the first layer is located in the second winding post area of ​​the first layer and surrounds the second post hole; A second layer includes a first winding and a second winding. The first winding of the second layer is located in the first winding post area of ​​the second layer and surrounds the first post hole with a first opening direction. The second winding of the second layer is located in the second winding post area of ​​the second layer and surrounds the second post hole with a second opening direction. The first winding of the second layer is electrically connected to the second winding of the second layer. The first opening direction of the second layer is different from the second opening direction of the second layer. The first winding of the second layer extends to the first extension area of ​​the second layer and is electrically connected to one of the two first guide holes. The second winding of the second layer extends to the second extension area of ​​the second layer and is electrically connected to the second guide hole. A third layer includes a first winding and a second winding. The first winding of the third layer is located in the first winding post area of ​​the first layer and surrounds the first post hole, having a first opening direction. The second winding of the third layer is located in the second winding post area of ​​the third layer and surrounds the second post hole, having a second opening direction. The first winding of the third layer is electrically connected to the second winding of the third layer. The first opening direction of the third layer is different from the second opening direction of the third layer. The first winding of the third layer extends to the first extension area of ​​the third layer and is electrically connected to the other of the two first guide holes. The second winding of the third layer extends to the second extension area of ​​the third layer and is electrically connected to the second guide hole. A fourth layer includes a first winding and a second winding, wherein the first winding of the fourth layer is located in the first winding post area of ​​the fourth layer and surrounds the first post hole, and the second winding of the fourth layer is located in the second winding post area of ​​the fourth layer and surrounds the second post hole; A high-voltage side circuit is electrically connected to the two first vias; and A low-voltage side circuit electrically connects the first winding of the first layer, the second winding of the first layer, the first winding of the fourth layer, and the second winding of the fourth layer.

2. The flat-plate transformer according to claim 1, characterized in that, The low-voltage side circuit includes four sets of output terminals, which correspond to the first winding of the first layer, the second winding of the first layer, the first winding of the fourth layer, and the second winding of the fourth layer, respectively. The four sets of output terminals are connected in parallel.

3. The flat-plate transformer according to claim 1, characterized in that, These winding layers also include: A fifth layer includes a first winding and a second winding, wherein the first winding of the fifth layer is located in the first winding post area of ​​the fifth layer and surrounds the first post hole, and the second winding of the fifth layer is located in the second winding post area of ​​the fifth layer and surrounds the second post hole; A sixth layer includes a first winding and a second winding. The first winding of the sixth layer is located in the first winding post area of ​​the sixth layer and surrounds the first post hole with a first opening direction. The second winding of the sixth layer is located in the second winding post area of ​​the sixth layer and surrounds the second post hole with a second opening direction. The first winding of the sixth layer is electrically connected to the second winding of the sixth layer. The first opening direction of the sixth layer is different from the second opening direction of the sixth layer. The first winding of the sixth layer extends to the first extension area of ​​the sixth layer and is electrically connected to one of the two first guide holes. The second winding of the sixth layer extends to the second extension area of ​​the sixth layer and is electrically connected to the second guide hole. A seventh layer includes a first winding and a second winding. The first winding of the seventh layer is located in the first winding post area of ​​the seventh layer and surrounds the first post hole, having a first opening direction. The second winding of the seventh layer is located in the second winding post area of ​​the seventh layer and surrounds the second post hole, having a second opening direction. The first winding of the seventh layer is electrically connected to the second winding of the seventh layer. The first opening direction of the seventh layer is different from the second opening direction of the seventh layer. The first winding of the seventh layer extends to the first extension area of ​​the seventh layer and is electrically connected to the other of the two first guide holes. The second winding of the seventh layer extends to the second extension area of ​​the seventh layer and is electrically connected to the second guide hole. An eighth layer includes a first winding and a second winding, wherein the first winding of the eighth layer is located in the first winding post area of ​​the eighth layer and surrounds the first post hole, and the second winding of the eighth layer is located in the second winding post area of ​​the eighth layer and surrounds the second post hole; The low-voltage side circuit is electrically connected to the first winding of the fifth layer, the second winding of the fifth layer, the first winding of the eighth layer, and the second winding of the eighth layer.

4. A flat-plate transformer, characterized in that, Include: A circuit board comprising multiple winding layers, a first post hole, a second post hole, three first vias, and two second vias. Each winding layer comprises a first winding region, a second winding region, a first extension region, and a second extension region. The first post hole passes through the first winding regions, the second post hole passes through the second winding regions, the first vias pass through the first extension regions, and the second vias pass through the second extension regions. The first vias are further divided into a first sub-via, a second sub-via, and a third sub-via, and the second vias are further divided into a fourth sub-via and a fifth sub-via. The winding layers include: A first layer includes a first winding and a second winding, wherein the first winding of the first layer is located in the first winding post area of ​​the first layer and surrounds the first post hole, and the second winding of the first layer is located in the second winding post area of ​​the first layer and surrounds the second post hole; A second layer includes a first winding and a second winding. The first winding of the second layer is located in the first winding post area of ​​the second layer and surrounds the first post hole with a first opening direction. The second winding of the second layer is located in the second winding post area of ​​the second layer and surrounds the second post hole with a second opening direction. The first winding of the second layer is electrically connected to the second winding of the second layer. The first opening direction of the second layer is different from the second opening direction of the second layer. The first winding of the second layer extends to the first extension area of ​​the second layer and is electrically connected to the first sub-guide hole. The second winding of the second layer extends to the second extension area of ​​the second layer and is electrically connected to the fourth sub-guide hole. A third layer includes a first winding and a second winding. The first winding of the third layer is located in the first winding post area of ​​the first layer and surrounds the first post hole with a first opening direction. The second winding of the third layer is located in the second winding post area of ​​the third layer and surrounds the second post hole with a second opening direction. The first winding of the third layer is electrically connected to the second winding of the third layer. The first opening direction of the third layer is different from the second opening direction of the third layer. The first winding of the third layer extends to the first extension area of ​​the third layer and is electrically connected to the second sub-guide hole. The second winding of the third layer extends to the second extension area of ​​the third layer and is electrically connected to the fourth sub-guide hole. A fourth layer includes a first winding and a second winding, wherein the first winding of the fourth layer is located in the first winding post area of ​​the fourth layer and surrounds the first post hole, and the second winding of the fourth layer is located in the second winding post area of ​​the fourth layer and surrounds the second post hole; A fifth layer includes a first winding and a second winding, wherein the first winding of the fifth layer is located in the first winding post area of ​​the fifth layer and surrounds the first post hole, and the second winding of the fifth layer is located in the second winding post area of ​​the fifth layer and surrounds the second post hole; A sixth layer includes a first winding and a second winding. The first winding of the sixth layer is located in the first winding post area of ​​the sixth layer and surrounds the first post hole with a first opening direction. The second winding of the sixth layer is located in the second winding post area of ​​the sixth layer and surrounds the second post hole with a second opening direction. The first winding of the sixth layer is electrically connected to the second winding of the sixth layer. The first opening direction of the sixth layer is different from the second opening direction of the sixth layer. The first winding of the sixth layer extends to the first extension area of ​​the sixth layer and is electrically connected to the second sub-guide hole. The second winding of the sixth layer extends to the second extension area of ​​the sixth layer and is electrically connected to the fifth sub-guide hole. A seventh layer includes a first winding and a second winding. The first winding of the seventh layer is located in the first winding post area of ​​the seventh layer and surrounds the first post hole with a first opening direction. The second winding of the seventh layer is located in the second winding post area of ​​the seventh layer and surrounds the second post hole with a second opening direction. The first winding of the seventh layer is electrically connected to the second winding of the seventh layer. The first opening direction of the seventh layer is different from the second opening direction of the seventh layer. The first winding of the seventh layer extends to the first extension area of ​​the seventh layer and is electrically connected to the third sub-guide hole. The second winding of the seventh layer extends to the second extension area of ​​the seventh layer and is electrically connected to the fifth sub-guide hole. and An eighth layer includes a first winding and a second winding, wherein the first winding of the eighth layer is located in the first winding post area of ​​the eighth layer and surrounds the first post hole, and the second winding of the eighth layer is located in the second winding post area of ​​the eighth layer and surrounds the second post hole; A high-voltage side circuit, electrically connected to the first sub-via and the third sub-via; and A low-voltage side circuit electrically connects the first winding of the first layer, the second winding of the first layer, the first winding of the fourth layer, the second winding of the fourth layer, the first winding of the fifth layer, the second winding of the fifth layer, the first winding of the eighth layer, and the second winding of the eighth layer.

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