Circuit board and method for manufacturing the same

Abstract

A circuit board and a manufacturing method thereof. The manufacturing method includes: providing a circuit substrate including a first surface and a second surface opposite in a first direction, the circuit substrate being provided with a through slot, the through slot forming a first opening and a second opening on the first surface and the second surface respectively; providing a first heat sink and a second heat sink, the first heat sink including a first extension and a first body part, the second heat sink including a second extension and a second body part, the width of the first extension being greater than the width of the first body part in a second direction, and the width of the second extension being greater than the width of the second body part; covering the first surface and the second surface with a first adhesive layer and a second adhesive layer respectively; inserting the first heat sink into the through slot from the first opening, inserting the second heat sink into the through slot from the second opening, and then performing compression. The application can prevent the first heat sink and the second heat sink from being separated from the side wall of the through slot.

Description

Technical Field

[0001] This application relates to the field of printed circuit boards, and more particularly to a printed circuit board and a method for its fabrication. Background Technology

[0002] With the increasing demand for computers, consumer electronics, and communication products, and the diversification of their functions, electronic components are becoming increasingly centralized. As the support and carrier for the electrical connections of these electronic components, heat dissipation has become a major problem for the circuit board industry.

[0003] Therefore, copper blocks are usually placed in the circuit board as heat sinks. However, when subjected to external forces (such as during subsequent processing or transportation of the circuit board), the copper blocks are prone to detaching from the sidewalls of the slot, leading to circuit board failure. Summary of the Invention

[0004] Therefore, it is necessary to provide a circuit board with heat dissipation function.

[0005] In addition, this application also provides a method for preparing the above-mentioned circuit board.

[0006] This application provides a method for manufacturing a circuit board, comprising: providing a circuit substrate, the circuit substrate including a first surface and a second surface disposed opposite to each other in a first direction, the circuit substrate having a through groove, the through groove forming a first opening and a second opening on the first surface and the second surface respectively; providing a first heat sink and a second heat sink, the first heat sink including a first extension and a first body portion connected together, the second heat sink including a second extension and a second body portion connected together, wherein in a second direction perpendicular to the first direction, the width of the first extension is greater than the width of the first body portion, and the width of the second extension is greater than the width of the second body portion; and providing a first heat sink and a second heat sink, the first heat sink including a first extension and a first body portion connected together in a first direction, the second heat sink including a first extension and a second body portion in a second direction perpendicular to the first direction, the first extension having a width greater than the width of the first body portion, and the second heat sink including a first extension and a second body portion in a second direction perpendicular to the first direction; and providing a method for manufacturing a circuit board, comprising providing a first heat sink and a second heat sink including a first extension and a first ..., the first extension having a width greater than the width of the first body portion, and the second heat sink including a first extension and a second body portion in a second direction perpendicular to the first direction, the first extension having a width greater than the width of the first body portion, and the second heat sink including a first extension and a second body portion in a second direction perpendicular to the first direction, the first extension having a width greater than the width of the first body portion, and the second A first adhesive layer and a second adhesive layer are respectively covered on the surface. The first adhesive layer and the second adhesive layer are respectively provided with a first window and a second window. When viewed from the first direction, the first window overlaps with the first opening, and the second window overlaps with the second opening. The first heat sink is inserted into the through groove from the overlap between the first window and the first opening, and the second heat sink is inserted into the through groove from the overlap between the second window and the second opening to obtain an intermediate body. The intermediate body is pressed together so that the first extension is bonded to the first surface through the first adhesive layer, and the second extension is bonded to the second surface through the second adhesive layer, thereby obtaining the circuit board.

[0007] In some possible implementations, when forming the through groove, the through groove includes a main groove body and at least one positioning groove recessed in the side wall of the main groove body. When providing the first heat sink and the second heat sink, the first heat sink further includes at least one first positioning protrusion protruding from the side wall of the first body portion, and the second heat sink further includes at least one second positioning protrusion protruding from the side wall of the second body portion. When inserting the first heat sink and the second heat sink, the first positioning protrusion and the second positioning protrusion are respectively inserted into the positioning groove from both sides.

[0008] In some possible implementations, there are two positioning grooves, each recessed into two adjacent sidewalls of the main groove. There are two first positioning protrusions, each protruding from two adjacent sidewalls of the first body portion. There are two second positioning protrusions, each protruding from two adjacent sidewalls of the second body portion.

[0009] In some possible implementations, the two positioning grooves are semicircular with different radii in a cross-section perpendicular to the first direction.

[0010] In some possible implementations, after the pressing, in the first direction, the sum of the thickness of the first body portion and the thickness of the second body portion is equal to the depth of the through groove.

[0011] A second aspect of this application provides a circuit board, including a circuit substrate, a first adhesive layer, a second adhesive layer, and a heat sink. The circuit substrate includes a first surface and a second surface disposed opposite each other in a first direction. A through-slot is formed in the circuit substrate, and the through-slot forms a first opening and a second opening on the first surface and the second surface, respectively. The first adhesive layer is disposed on the first surface and has a first opening, which overlaps with the first opening when viewed from the first direction. The second adhesive layer is disposed on the second surface and has a second opening, which overlaps with the second opening when viewed from the first direction. The heat sink includes a first heat sink block and a second heat sink block. The first heat sink block includes a first extension and a first body portion connected together. In a second direction perpendicular to the first direction, the width of the first extension is greater than the width of the first body portion. The first body portion passes through the first opening and the first opening and is disposed within a portion of the through-slot. The first extension is bonded to the first surface through the first adhesive layer. The second heat sink includes a second extension and a second body connected together. In the second direction, the width of the second extension is greater than the width of the second body. The second body passes through the second window and the second opening and is disposed in another part of the through groove. The second extension is bonded to the second surface by the second adhesive layer.

[0012] In some possible implementations, the through slot includes a main slot body and at least one positioning slot recessed in the side wall of the main slot body. The first heat sink further includes at least one first positioning protrusion protruding from the side wall of the first body portion, and the second heat sink further includes at least one second positioning protrusion protruding from the side wall of the second body portion. The first positioning protrusion and the second positioning protrusion are disposed within the positioning slot and are in contact with each other.

[0013] In some possible implementations, there are two positioning grooves, each recessed into two adjacent sidewalls of the main groove. There are two first positioning protrusions, each protruding from two adjacent sidewalls of the first body portion. There are two second positioning protrusions, each protruding from two adjacent sidewalls of the second body portion.

[0014] In some possible implementations, the two positioning grooves are semicircular with different radii in a cross-section perpendicular to the first direction.

[0015] In some possible implementations, in the first direction, the sum of the thickness of the first body portion and the thickness of the second body portion is equal to the depth of the through groove.

[0016] In this application, since the first extension and the second extension are respectively bonded to the circuit board through the first adhesive layer and the second adhesive layer, and the dimensions of the first extension and the second extension in the second direction are large, the bonding area is increased. When the circuit board is subjected to external force, the arrangement of the first extension and the second extension helps to reduce the risk of the heat sink and the circuit board detaching. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a circuit board provided in one embodiment of this application.

[0018] Figure 2 In order to be in Figure 1 The diagram shows the structure of the circuit board after a through slot is opened.

[0019] Figure 3 In order to be in Figure 2 The diagram shows a top view of the circuit board.

[0020] Figure 4 In order to be in Figure 2 The diagram shows the structure of the circuit board after both sides are covered with insulating layers and heat sinks.

[0021] Figure 5 For pressing Figure 4 The schematic diagram of the circuit board obtained after the structure shown is shown.

[0022] Figure 6 for Figure 5 The diagram shows a cross-sectional view of the circuit board along line VI-VI.

[0023] Explanation of main component symbols

[0024] Circuit Board 1

[0025] Circuit board 10

[0026] Line layer 11

[0027] Insulation layer 12

[0028] Through slot 13

[0029] Heat sink 20

[0030] First heat sink 21

[0031] Second heat sink 22

[0032] First adhesive layer 30

[0033] First window opening 31

[0034] Second adhesive layer 40

[0035] Second window 41

[0036] First surface 101

[0037] First opening 101a

[0038] Second surface 102

[0039] Second opening 102a

[0040] Main tank 131

[0041] Positioning groove 132

[0042] First extension 211

[0043] First body part 212

[0044] First positioning protrusion 213

[0045] Second extension 221

[0046] Second Body Section 222

[0047] Second positioning protrusion 223

[0048] First direction X

[0049] Second direction Y

[0050] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0051] To better understand the above-mentioned objectives, features, and advantages of this application, the application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. Many specific details are set forth in the following description to provide a thorough understanding of this application; the described embodiments are merely a part of the embodiments of this application, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The term "and / or" as used herein includes all and any combination of one or more of the associated listed items.

[0053] In the various embodiments of this application, for ease of description and not limitation, the term "connection" used in the patent application specification and claims is not limited to physical or mechanical connections, whether direct or indirect. Terms such as "upper," "lower," "above," "below," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship also changes accordingly.

[0054] One embodiment of this application provides a method for manufacturing a circuit board 1, comprising the following steps:

[0055] Step S1: Please refer to Figure 1 A circuit board 10 is provided, which includes a first surface 101 and a second surface 102 disposed opposite to each other in a first direction X.

[0056] In some embodiments, the circuit board 10 includes a plurality of circuit layers 11 stacked along a first direction X and an insulating layer 12 disposed between two adjacent circuit layers 11. The outermost circuit layer 11 forms a first surface 101, and the other outermost circuit layer 11 forms a second surface 102.

[0057] In one embodiment, the insulating layer 12 is made of insulating resin. For example, the insulating layer 12 can be made of one of the following resins: epoxy resin, prepreg (PP), BT resin, polyphenylene ether (PPO), polyimide (PI), polyethylene terephthalate (PET), and polyethylene naphthalate (PEN).

[0058] In some embodiments, the circuit board 10 can be a high-density interconnect board or a flexible circuit board. The circuit layer 11 of the circuit board 10 can be made of copper.

[0059] Step S2: Please refer to Figure 2 and Figure 3 A through groove 13 is formed in the circuit board 10, and the through groove 13 penetrates the entire circuit board 10 along the first direction X. That is, the through groove 13 penetrates the first surface 101 and the second surface 102, thereby forming a first opening 101a and a second opening 102a on the first surface 101 and the second surface 102, respectively.

[0060] In some embodiments, the through groove 13 includes a main groove 131 and at least one positioning groove 132 recessed in the side wall of the main groove 131. Figure 2 and Figure 3As shown in some embodiments, there may be two positioning grooves 132, which are respectively recessed into two adjacent sidewalls of the main groove 131. Each of the main groove 131 and the positioning groove 132 extends through the first surface 101 and the second surface 102 along the first direction X. In some specific embodiments, in a cross-section perpendicular to the first direction X, the main groove 131 is square, and each positioning groove 132 is semi-circular with different radii, for example, one positioning groove 132 has a radius of approximately 1 mm, and the other positioning groove 132 has a radius of approximately 2 mm.

[0061] In some embodiments, the through-slot 13 can be formed by mechanical drilling. The location of the through-slot 13 can avoid the location of conductive lines in the wiring layer 11.

[0062] Step S3, please refer to Figure 4 It provides a first heat sink 21 and a second heat sink 22.

[0063] Both the first heat sink 21 and the second heat sink 22 have a T-shaped structure. The first heat sink 21 includes a first extension 211 and a first body 212 connected to each other, and the first body 212 can be formed by protruding outward from the center of the first extension 211. In the second direction Y, which is perpendicular to the first direction X, the width of the first extension 211 is greater than the width of the first body 212.

[0064] The second heat sink 22 may have a structure similar to that of the first heat sink 21. The second heat sink 22 includes a second extension 221 and a second body portion 222 connected to each other, and the second body portion 222 may be formed by protruding outward from the center position of the second extension 221. In the second direction Y, the width of the second extension 221 is greater than the width of the second body portion 222.

[0065] Furthermore, when the through slot 13 is designed to include a main slot 131 and a positioning slot 132, the first heat sink 21 also includes at least one first positioning protrusion 213 protruding from the side wall of the first body portion 212. Similarly, the first heat sink 21 also includes at least one second positioning protrusion 223 protruding from the side wall of the second body portion 222. In a cross-section perpendicular to the first direction X, the size of the first positioning protrusion 213 matches the size of the positioning slot 132, and the size of the second positioning protrusion 223 also matches the size of the positioning slot 132. In some specific embodiments, there may be two first positioning protrusions 213, which protrude from two adjacent side walls of the first body portion 212 respectively; there may also be two second positioning protrusions 223, which protrude from two adjacent side walls of the second body portion 222 respectively.

[0066] In some embodiments, the first heat sink 21 and the second heat sink 22 may be made of a metal or alloy with a high thermal conductivity. The materials of the first heat sink 21 and the second heat sink 22 may be the same or different. In some specific embodiments, the materials of the first heat sink 21 and the second heat sink 22 may both be copper, silver, aluminum or steel.

[0067] For step S4, please refer to [link / reference]. Figure 4 A first adhesive layer 30 and a second adhesive layer 40 are respectively covered on the first surface 101 and the second surface 102.

[0068] The first adhesive layer 30 and the second adhesive layer 40 are respectively provided with a first window 31 and a second window 41. When viewed from the first direction X, the first window 31 of the first adhesive layer 30 overlaps with the first opening 101a, and the second window 41 of the second adhesive layer 40 overlaps with the second opening 102a.

[0069] In some embodiments, when viewed from the first direction X, the first window 31 of the first adhesive layer 30 completely overlaps with the first opening 101a, and the second window 41 of the second adhesive layer 40 completely overlaps with the second opening 102a.

[0070] In one embodiment, the first adhesive layer 30 and the second adhesive layer 40 are made of insulating resin. For example, the material of each of the first adhesive layer 30 and the second adhesive layer 40 can be selected from resins such as epoxy resin, prepreg (PP), BT resin, polyphenylene ether (PPO), polyimide (PI), polyethylene terephthalate (PET), and polyethylene naphthalate (PEN). The materials of the first adhesive layer 30 and the second adhesive layer 40 can be the same or different.

[0071] For step S5, please refer to [link / reference]. Figure 4 and Figure 5 The first heat sink 21 is inserted into the through groove 13 from the overlap between the first window 31 and the first opening 101a, and the second heat sink 22 is inserted into the through groove 13 from the overlap between the second window 41 and the second opening 102a, to obtain an intermediate body (not shown).

[0072] It is understood that when the through slot 13 includes a main slot body 131 and a positioning slot body 132, and the first heat sink 21 and the second heat sink 22 respectively include a first positioning protrusion 213 and a second positioning protrusion 223, during the insertion of the first heat sink 21, the first positioning protrusion 213 is inserted into the positioning slot body 132 from one side, and during the insertion of the second heat sink 22, the second positioning protrusion 223 is inserted into the positioning slot body 132 from the other side. The cooperation between the positioning protrusions and the positioning slots can play a role in directional positioning and guidance during the insertion of the heat sink.

[0073] Step S6, please refer to Figure 5 and Figure 6 The intermediate bodies are pressed together so that the first heat sink 21 and the second heat sink 22 come into contact within the through groove 13. Simultaneously, the first extension 211 of the first heat sink 21 is bonded to the first surface 101 via the first adhesive layer 30, and the second extension 221 of the second heat sink 22 is bonded to the second surface 102 via the second adhesive layer 40. At this point, circuit board 1 is obtained.

[0074] In this design, the first body portion 212 of the first heat sink 21 is disposed within a partial through groove 13, and the first extension portion 211 of the first heat sink 21 protrudes from the first surface 101. The second body portion 222 of the second heat sink 22 is disposed within another partial through groove 13, and the second extension portion 221 of the second heat sink 22 protrudes from the second surface 102. The first body portion 212 and the second body portion 222 contact each other within the through groove 13 to form a heat conduction channel (see reference). Figure 4 When the first positioning protrusion 213 and the second positioning protrusion 223 are provided, the first positioning protrusion 213 and the second positioning protrusion 223 also contact each other in the through groove 13 after pressing. In the first direction X, the sum of the thickness of the first body portion 212 and the thickness of the second body portion 222 can be approximately equal to the depth of the through groove 13. The first heat sink 21 and the second heat sink 22 together form the heat sink 20.

[0075] During operation, the heat generated in the circuit layer 11 is first conducted to the first body portion 212 of the first heat sink 21 and the second body portion 222 of the second heat sink 22, then to the first extension portion 211 and the second extension portion 221, and finally to the outside via the first extension portion 211 and the second extension portion 221, thereby achieving heat dissipation. Since the first extension portion 211 and the second extension portion 221 have relatively large dimensions in the second direction Y, their arrangement helps to increase the heat dissipation area of ​​the heat sink 20, thereby improving heat dissipation efficiency. Specifically, if the temperature of a portion of the circuit substrate 10 near the first surface 101 is higher, the heat can be dissipated sequentially via the first body portion 212, the second body portion 222, and the second extension portion 221; conversely, if the temperature of a portion of the circuit substrate 10 near the second surface 102 is higher, the heat can be dissipated sequentially via the second body portion 222, the first body portion 212, and the first extension portion 211. Thus, the heat dissipation effect on both sides can be balanced, thereby improving the overall heat dissipation capacity of the circuit board 1.

[0076] Furthermore, in this application, since the first extension 211 and the second extension 221 are respectively bonded to the circuit board 10 through the first adhesive layer 30 and the second adhesive layer 40, and the dimensions of the first extension 211 and the second extension 221 in the second direction Y are relatively large, the bonding area is increased. When the circuit board 1 is subjected to external force, the provision of the first extension 211 and the second extension 221 helps to reduce the risk of the heat sink 20 detaching from the circuit board 10. In addition, the provision of the first positioning protrusion 213 and the second positioning protrusion 223 to cooperate with the positioning groove 132 of the through groove 13 also helps to increase the contact area between the heat sink 20 and the side wall of the through groove 13, thereby further reducing the risk of the heat sink 20 detaching from the circuit board 10 under external force.

[0077] Please see Figure 5 and Figure 6 An embodiment of this application also provides a circuit board 1 prepared by the above-described method, comprising a circuit substrate 10, a first adhesive layer 30, a second adhesive layer 40, and a heat sink 20. The circuit substrate 10 includes a first surface 101 and a second surface 102 disposed opposite to each other in a first direction X. A through groove 13 is formed in the circuit substrate 10, and the through groove 13 penetrates the entire circuit substrate 10 along the first direction X, thereby forming a first opening 101a and a second opening 102a on the first surface 101 and the second surface 102, respectively.

[0078] The first adhesive layer 30 and the second adhesive layer 40 are respectively disposed on the first surface 101 and the second surface 102. When viewed from the first direction X, the first window 31 of the first adhesive layer 30 overlaps with the first opening 101a, and the second window 41 of the second adhesive layer 40 overlaps with the second opening 102a.

[0079] The heat sink 20 includes a first heat sink 21 and a second heat sink 22. The first heat sink 21 includes a first extension 211 and a first body 212 connected together. In a second direction Y perpendicular to the first direction X, the width of the first extension 211 is greater than the width of the first body 212. The second heat sink 22 includes a second extension 221 and a second body 222 connected together. In the second direction Y, the width of the second extension 221 is greater than the width of the second body 222. The first body 212 of the first heat sink 21 passes through the first opening 31 and the first opening 101a and is disposed within a partial through groove 13. The first extension 211 of the first heat sink 21 is bonded to the first surface 101 by a first adhesive layer 30. The second body 222 of the second heat sink 22 passes through the second opening 41 and the second opening 102a and is disposed within another partial through groove 13. The second extension 221 of the second heat sink 22 is bonded to the second surface 102 by a second adhesive layer 40. The first body part 212 and the second body part 222 come into contact within the through groove 13 to form a heat conduction channel.

[0080] Combined with reference Figure 4 In some embodiments, the through groove 13 includes a main groove 131 and at least one positioning groove 132 recessed in the sidewall of the main groove 131. Each of the main groove 131 and the positioning groove 132 extends through the first surface 101 and the second surface 102 along a first direction X. The first heat sink 21 also includes at least one first positioning protrusion 213 protruding from the sidewall of the first body portion 212, and the first heat sink 21 also includes at least one second positioning protrusion 223 protruding from the sidewall of the second body portion 222. The first positioning protrusion 213 and the second positioning protrusion 223 are in contact within the through groove 13, and the contacting first positioning protrusion 213 and the contacting second positioning protrusion 223 are located within the positioning groove 132.

[0081] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application should not depart from the spirit and scope of the technical solutions of this application.

Claims

1. A method for manufacturing a circuit board, characterized in that, include: A circuit board is provided, the circuit board including a first surface and a second surface disposed opposite to each other in a first direction, the circuit board having a through groove, the through groove forming a first opening and a second opening on the first surface and the second surface respectively, the through groove including a main groove body and at least one positioning groove body recessed in the sidewall of the main groove body; A first heat sink and a second heat sink are provided. The first heat sink includes a first extension and a first body portion connected together, and at least one first positioning protrusion protruding from the side wall of the first body portion. The second heat sink includes a second extension and a second body portion connected together, and at least one second positioning protrusion protruding from the side wall of the second body portion. In a second direction perpendicular to the first direction, the width of the first extension is greater than the width of the first body portion, and the width of the second extension is greater than the width of the second body portion. A first adhesive layer and a second adhesive layer are respectively covered on the first surface and the second surface. The first adhesive layer and the second adhesive layer are respectively provided with a first window and a second window. When viewed from the first direction, the first window overlaps with the first opening and the second window overlaps with the second opening. The first heat sink is inserted into the through groove from the overlap between the first window and the first opening, and the second heat sink is inserted into the through groove from the overlap between the second window and the second opening. The first positioning protrusion and the second positioning protrusion are respectively inserted into the positioning groove from both sides to obtain the intermediate body. as well as The intermediate body is pressed together such that the first extension is bonded to the first surface through the first adhesive layer, and the second extension is bonded to the second surface through the second adhesive layer, thereby obtaining the circuit board.

2. The method for preparing a circuit board as described in claim 1, characterized in that, The number of positioning grooves is two, which are respectively recessed on two adjacent side walls of the main groove; the number of first positioning protrusions is two, which are respectively protruded on two adjacent side walls of the first body part; the number of second positioning protrusions is two, which are respectively protruded on two adjacent side walls of the second body part.

3. The method for preparing a circuit board as described in claim 2, characterized in that, In a cross-section perpendicular to the first direction, the two positioning grooves are semi-circular and have different radii.

4. The method for preparing a circuit board as described in claim 1, characterized in that, After the pressing, in the first direction, the sum of the thickness of the first body portion and the thickness of the second body portion is equal to the depth of the through groove.

5. A circuit board, characterized in that, include: A circuit board includes a first surface and a second surface disposed opposite to each other in a first direction. A through groove is formed in the circuit board. The through groove forms a first opening and a second opening on the first surface and the second surface, respectively. The through groove includes a main groove body and at least one positioning groove body recessed in the side wall of the main groove body. A first adhesive layer is disposed on the first surface. The first adhesive layer has a first window. When viewed from the first direction, the first window overlaps with the first opening. A second adhesive layer is disposed on the second surface. The second adhesive layer has a second opening. When viewed from the first direction, the second opening overlaps with the second opening. as well as The heat sink includes a first heat sink block and a second heat sink block. The first heat sink block includes a first extension and a first body portion connected together, and at least one first positioning protrusion protruding from the sidewall of the first body portion. In a second direction perpendicular to the first direction, the width of the first extension is greater than the width of the first body portion. The first body portion passes through the first window and the first opening and is disposed in a portion of the through groove. The first extension is bonded to the first surface through the first adhesive layer. The second heat sink block includes a second extension and a second body portion connected together, and at least one second positioning protrusion protruding from the sidewall of the second body portion. The first positioning protrusion and the second positioning protrusion are disposed in the positioning groove and are in contact with each other. In the second direction, the width of the second extension is greater than the width of the second body portion. The second body portion passes through the second window and the second opening and is disposed in another portion of the through groove. The second extension is bonded to the second surface through the second adhesive layer.

6. The circuit board as described in claim 5, characterized in that, The number of positioning grooves is two, which are respectively recessed on two adjacent side walls of the main groove; the number of first positioning protrusions is two, which are respectively protruded on two adjacent side walls of the first body part; the number of second positioning protrusions is two, which are respectively protruded on two adjacent side walls of the second body part.

7. The circuit board as described in claim 6, characterized in that, In a cross-section perpendicular to the first direction, the two positioning grooves are semi-circular and have different radii.

8. The circuit board as described in claim 5, characterized in that, In the first direction, the sum of the thickness of the first body portion and the thickness of the second body portion is equal to the depth of the through groove.

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