Circuit board and method of manufacturing the same

Abstract

A circuit board includes a main substrate and an extension substrate. The main substrate includes a first outer structure, a second outer structure, and an inner structure. The first outer structure includes a first metal piece having a first protrusion. The second outer structure includes a second metal piece having a second protrusion. The inner structure is disposed between the first outer structure and the second outer structure, wherein the first outer structure and the second outer structure protrude from a boundary of the inner structure in a first direction. A side opening is located in the inner structure, the first outer structure, and the second outer structure. The extension substrate is detachably inserted into the main substrate from the side opening, which can reduce the thickness of the circuit board, facilitate the development of thin circuit boards, and facilitate the reuse of the original main substrate and extension substrate.

Description

Technical Field

[0001] The present invention relates to a circuit board and a manufacturing method thereof, and more particularly to a circuit board in which an extension substrate is arranged on a side of a main substrate and a manufacturing method thereof. Background Art

[0002] Circuit boards are widely used in applications such as Bluetooth modules, wireless fidelity (WiFi) modules, and narrowband Internet of Things (NB-IoT). Circuit boards are formed by stacking daughter boards on a main board (also called a motherboard), and the daughter boards are soldered to the motherboard.

[0003] However, stacking a daughterboard and a motherboard to form a circuit board reduces the overall thickness of the circuit board, hindering the trend toward thinner designs. Furthermore, soldering a daughterboard and a motherboard together can be difficult to reuse. For example, if a daughterboard is mistakenly soldered to a motherboard that doesn't meet specifications, the original daughterboard and motherboard are difficult to detach and rework, rendering them unusable and potentially forcing them to be scrapped. In light of the foregoing, there is an urgent need to develop a thinner circuit board and a circuit board that can reuse daughterboards and motherboards to overcome these shortcomings. Summary of the Invention

[0004] At least one embodiment of the present invention provides a circuit board comprising a main substrate and an extension substrate, and a method for manufacturing the same. The extension substrate can be positioned on the side of the main substrate, thereby reducing the thickness of the circuit board and promoting the development of thinner circuit boards. Furthermore, the main substrate includes two opposing metal members, each having a corresponding protrusion. The extension substrate can be removably inserted into the main substrate through a side opening of the main substrate, facilitating the reuse of the original main substrate and extension substrate.

[0005] At least one embodiment of the present invention provides a circuit board comprising a main substrate and an extension substrate. The main substrate comprises a first external structure, a second external structure, an internal structure, a first adhesive layer, and a second adhesive layer. The first external structure comprises a first metal member having a first protrusion. The second external structure comprises a second metal member having a second protrusion. The internal structure is disposed between the first and second external structures, wherein the first and second external structures protrude beyond the boundary of the internal structure in a first direction. The internal structure, the first and second external structures are stacked in a second direction perpendicular to the first direction, and side openings are located within the internal structure, the first and second external structures, with the boundary exposed by the side openings. The first protrusion has a first curved surface protruding toward the second external structure, and the second protrusion has a second curved surface protruding toward the first external structure, the first and second curved surfaces being disposed opposite each other, and both the first and second protrusions are located within the side openings. The first adhesive layer is disposed between the internal structure and the first external structure, connecting the internal structure and the first external structure. The first metal member further comprises a first extension disposed between the first adhesive layer and the first external structure, wherein the first extension connects to the first protrusion. The second adhesive layer is disposed between the inner structure and the second outer structure, connecting the inner structure and the second outer structure. The second metal member further includes a second extension portion disposed between the second adhesive layer and the first outer structure, wherein the second extension portion is connected to the second protrusion. The extension substrate is detachably inserted into the main substrate through the side opening.

[0006] In at least one embodiment of the present invention, the internal structure includes a first internal insulating layer, and the extended substrate includes a first circuit layer, a second circuit layer, and a second internal insulating layer. The second internal insulating layer is disposed between the first and second circuit layers, wherein the first, second, and second internal insulating layers are stacked along a second direction. When the extended substrate is inserted into the main substrate through the side opening, the extended substrate is sandwiched between the first and second metal members, wherein the first protrusion of the first metal member compresses the first circuit layer, and the second protrusion of the second metal member compresses the second circuit layer.

[0007] In at least one embodiment of the present invention, the first inner insulating layer is aligned with the second inner insulating layer in the first direction.

[0008] In at least one embodiment of the present invention, the first external structure further includes a first groove, the first metal member further includes a first support portion connected to the first protrusion, wherein the first support portion is disposed in the first groove. The second external structure further includes a second groove, the second metal member further includes a second support portion connected to the second protrusion, wherein the second support portion is disposed in the second groove, and the first support portion and the second support portion are located between a first bottom portion of the first groove and a second bottom portion of the second groove.

[0009] In at least one embodiment of the present invention, the extended substrate includes a first circuit layer, a second circuit layer, and a second internal insulating layer. The second internal insulating layer is disposed between the first circuit layer and the second circuit layer, wherein the first circuit layer, the second circuit layer, and the second internal insulating layer are stacked along a second direction. When the extended substrate is separated from the main substrate, the first supporting portion of the first metal member does not contact the first bottom surface of the first groove, and the second supporting portion of the second metal member does not contact the second bottom surface of the second groove.

[0010] In at least one embodiment of the present invention, the minimum distance between the first curved surface of the first protrusion and the second curved surface of the second protrusion is less than or equal to the distance between the surface of the first circuit layer and the surface of the second circuit layer.

[0011] In at least one embodiment of the present invention, the overall thickness of the extension substrate is less than or equal to the height of the side opening of the main substrate.

[0012] At least one embodiment of the present invention provides a method for manufacturing a circuit board, comprising the following steps: providing a first initial external structure, wherein the first initial external structure comprises a first insulating layer and a first metal member, the first insulating layer comprises a plurality of first grooves, the first metal member comprises a first protrusion, a first extension, and a first support portion, the first extension portion and the first support portion are respectively located at two ends of the first protrusion, and the first extension portion and the first support portion are respectively disposed in the plurality of first grooves in the first insulating layer. providing a second initial external structure, wherein the second initial external structure comprises a second insulating layer and a second metal member, the second insulating layer comprises a plurality of second grooves, the second metal member comprises a second protrusion, a second extension, and a second support portion, the second extension portion and the second support portion are respectively located at two ends of the second protrusion, and the second extension portion and the second support portion are respectively disposed in the plurality of second grooves in the second insulating layer. providing an internal structure. The first initial external structure, the internal structure, and the second initial external structure are laminated to form an initial circuit substrate. The initial circuit substrate includes a cavity, and the first protrusion, the first support portion, the second protrusion, and the second support portion are located in the cavity. The first protrusion has a first curved surface that bulges toward the second protrusion, and the second protrusion has a second curved surface that bulges toward the first protrusion. A through-hole is formed in the initial circuit substrate, exposing the first support portion and the second support portion in the through-hole. The through-hole is plated. The initial circuit substrate is cut to expose the cavity from the side of the initial circuit substrate to form a circuit board.

[0013] In at least one embodiment of the present invention, a method for manufacturing a first initial external structure includes the following steps: providing a first substrate comprising a first insulating layer and a first circuit layer; etching the first circuit layer to form a first circuit layer; forming a plurality of grooves in the first insulating layer; providing a first metal member; and embedding a first extension portion and a first support portion of the first metal member into the plurality of grooves in the first insulating layer to form the first initial external structure.

[0014] In at least one embodiment of the present invention, after the through-holes are plated, a solder resist layer is formed to fill the plated through-holes and cover the surface of the initial circuit substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The various aspects of the present application are best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be understood that, in accordance with standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of various features may be arbitrarily increased or reduced for clarity.

[0016] Figures 1A to 1D Schematic cross-sectional views of a main substrate in various stages of a process according to at least one embodiment of the present invention.

[0017] Figure 2 for Figure 1D A side view of the main substrate.

[0018] Figure 3 FIG. 4 is a schematic cross-sectional view of an extended substrate according to at least one embodiment of the present invention.

[0019] Figure 4 For connection according to one embodiment Figure 1D The main substrate and Figure 2 A schematic cross-sectional view of a circuit board with an extended substrate.

[0020] Figure 5 For connection according to another embodiment Figure 1D The main substrate and Figure 2 An enlarged cross-sectional schematic diagram of a circuit board with an extended substrate. DETAILED DESCRIPTION

[0021] In the following text, in order to clearly present the technical features of this case, the dimensions (such as length, width, thickness and depth) of the elements (such as substrates, circuit layers and through holes, etc.) in the drawings will be enlarged in a non-uniform manner, and the number of some elements will be reduced. Therefore, the description and explanation of the embodiments below are not limited to the number of elements in the drawings and the dimensions and shapes of the elements, but should cover the dimensions, shapes and deviations thereof caused by actual processes and / or tolerances. For example, the flat surface shown in the drawings may have rough and / or nonlinear features, and the sharp angles shown in the drawings may be rounded. Therefore, the elements shown in the drawings of this case are mainly for illustration and are not intended to accurately depict the actual shape of the elements, nor are they used to limit the claims of this case.

[0022] In addition, spatially relative terms such as "below," "beneath," "below," "above," and similar terms are used to facilitate describing the relationship of one element or feature to another element or feature in the figures. Spatially relative terms encompass not only the orientation depicted in the figures, but also other orientations of the device during use or operation. That is, when the device is oriented differently from the figures (rotated 90 degrees or in other orientations), the spatially relative terms used in this disclosure should be interpreted accordingly.

[0023] It will be understood that although terms such as "first," "second," and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are merely used to distinguish one element from another. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element, without departing from the scope of the embodiments. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0024] As used herein, the terms "approximately," "substantially," or "substantially" may be used to select a more acceptable range of deviations or standard deviations based on the optical, etching, mechanical, measurement, coating, or other properties, and may not apply to all properties in a single standard deviation. It should be noted that the first direction D1 and the second direction D2 are marked in the drawings of this application to illustrate the configuration relationship of the various components in the drawings. The first direction D1 and the second direction D2 are substantially perpendicular to each other.

[0025] Figures 1A to 1D This is a cross-sectional view of the main substrate in various stages of the process of at least one embodiment of the present invention. Figure 1A The main substrate 100 includes a first initial outer structure 110, a second initial outer structure 120, and an inner structure 130. The inner structure 130 is disposed between the first initial outer structure 110 and the second initial outer structure 120. In other words, the first initial outer structure 110 and the second initial outer structure 120 are disposed on opposite sides of the inner structure 130.

[0026] The first initial external structure 110 includes an insulating layer 112, a circuit layer 114, and a first metal member 116. The circuit layer 114 is disposed on one side of the insulating layer 112, and the first metal member 116 is disposed on the other side of the insulating layer 112. Figure 1A In the embodiment, the insulating layer 112 and the circuit layer 114 are arranged parallel to a first direction D1 and stacked along a second direction D2, wherein the first direction D1 may be perpendicular to the second direction D2. The first metal member 116 is also stacked along the second direction D2 with the insulating layer 112 and the circuit layer 114. The first metal member 116 may also be referred to as a 3D metal clip.

[0027] The insulating layer 112 includes a plurality of first grooves 115a and 115b. The first metal member 116 includes a first protrusion 116a, a first extension 116b, and a first support 116c. The first extension 116b and the first support 116c are located at two ends of the first protrusion 116a. In other words, one end of the first protrusion 116a is connected to the first extension 116b, and the other end of the first protrusion 116a is connected to the first support 116c. Figure 1A In the embodiment, a portion of the first extension portion 116b is located in the first groove 115a, and the first support portion 116c is located in the first bottom of the first groove 115b.

[0028] In an embodiment of the present invention, the method for forming the first initial outer structure 110 includes the following steps: providing a substrate including an initial insulating layer and a metal layer, wherein the metal layer is disposed on the initial insulating layer, and the substrate may be a copper clad laminate (CCL). Then, etching the metal layer to form a Figure 1A A plurality of first grooves 115a and 115b are formed in the initial insulating layer to form a circuit layer 114. Figure 1A Then, the first extension portion 116b of the first metal member 116 is embedded in the first groove 115a, and the first support portion 116c of the first metal member 116 is disposed in the first groove 115b in the first insulating layer to form the following. Figure 1A The first initial outer structure 110.

[0029] In this embodiment, the circuit layer 114 is formed by etching a metal layer (e.g., the copper foil of a copper foil substrate), so the circuit layer 114 is formed using a subtractive process. However, in other embodiments, the circuit layer 114 may be formed using an additive process or a semi-additive process. Furthermore, in this embodiment, the plurality of first grooves 115a and 115b may be formed using routing or laser ablation.

[0030] In some embodiments, the insulating layer 112 may be made of, but is not limited to, insulating materials such as polyimide (PI), fiberglass epoxy resin (FR4), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or polyethylene (PE). In some embodiments, the circuit layer 114 may be made of, but is not limited to, a conductive material such as copper, gold, or silver. In some embodiments, the first metal member 116 may be made of, but is not limited to, a conductive material such as copper, gold, or silver. In some embodiments, the first metal member 116 is made of the same material as the circuit layer 114.

[0031] Similar to the first initial external structure 110, the second initial external structure 120 includes an insulating layer 122, a circuit layer 124, and a second metal member 126, wherein the insulating layer 122 includes a plurality of second grooves 125a and 125b. The second metal member 126 includes a second protrusion 126a, a second extension 126b, and a second support portion 126c. The second extension 126b and the second support portion 126c are respectively located at two ends of the second protrusion 126a, and the second extension 126b and the second support portion 126c are respectively disposed in the plurality of second grooves 125a and 125b in the insulating layer 122. Figure 1A In the embodiment, a portion of the second extension portion 126b is located in the second groove 125a, and the second support portion 126c is located in the second bottom of the second groove 125b.

[0032] It is understandable that in Figure 1A In the embodiment, the first initial external structure 110 and the second initial external structure 120 have similar structures. With the internal structure 130 as the axis of symmetry, the first initial external structure 110 and the second initial external structure 120 are substantially mirror-symmetrical. The materials of the various layers in the second initial external structure 120 are similar to those of the various layers in the first initial external structure 110 and are not described again herein. The method for forming the second initial external structure 120 is similar to the method for forming the first initial external structure 110 and is not described again herein.

[0033] The internal structure 130 includes a first internal insulating layer 132 and a circuit layer 134. The circuit layers 134 are located on opposite sides of the first internal insulating layer 132. The first internal insulating layer 132 and the circuit layer 134 are distributed along a direction parallel to the first direction D1 and are stacked along the second direction D2. Figure 1A shown.

[0034] The inner structure 130 is pre-cut (eg, laser cutting or stamping) to form an opening 136, wherein the opening 136 is aligned with the first metal member 116 of the first initial outer structure 110 and the second metal member 126 of the second initial outer structure 120 in the second direction D2. Figure 1A shown.

[0035] The first inner insulating layer 132 has the same or similar material as the insulating layer 112 , the circuit layer 134 has the same or similar material as the circuit layer 114 , and the electroplating layer 133 has the same or similar material as the electroplating layer 113 , which will not be repeated here.

[0036] Please refer to Figure 1A The main substrate 100 further includes a first adhesive layer 140 and a second adhesive layer 150. The first adhesive layer 140 is disposed between the internal structure 130 and the first initial external structure 110 and is used to connect the internal structure 130 and the first initial external structure 110. The second adhesive layer 150 is disposed between the internal structure 130 and the second initial external structure 120 and is used to connect the internal structure 130 and the second initial external structure 120. The material of the first adhesive layer 140 and the second adhesive layer 150 can be a low-flow prepreg or a non-flow prepreg. In some embodiments, the first adhesive layer 140 and the second adhesive layer 150 can each include a polymer and glass fiber.

[0037] The first adhesive layer 140 is pre-cut (e.g., laser cutting or stamping) to have an opening 142. Similarly, the second adhesive layer 150 is pre-cut (e.g., laser cutting or stamping) to have an opening 152. The first protrusion 116a, the opening 142, the opening 136, the opening 152, and the second protrusion 126a are aligned with each other in the second direction D2.

[0038] Please refer to Figure 1B , Figure 1B For the general Figure 1A The components are pressed together to form a pressed structure, and then drilling is performed to form the main substrate 100a having the through hole 160. Since the first protrusion 116a, the opening 142, the opening 136, the opening 152 and the second protrusion 126a are aligned with each other in the second direction D2 (see Figure 1A ), thus, after lamination, the main substrate 100a has a cavity 170. The first protrusion 116a, the first support portion 116c, the second protrusion 126a, and the second support portion 126c are located in the cavity 170, wherein the first protrusion 116a has a first curved surface cs1 that protrudes toward the second protrusion 126a, and the second protrusion 126a has a second curved surface cs2 that protrudes toward the first protrusion 116a.

[0039] It should be noted that, because the first extension portion 116b is bonded between the first initial external structure 110 and the internal structure 130, the first protrusion 116a and the first support portion 116c are suspended above the first groove 115b and within the cavity 170. Similarly, because the second extension portion 126b is bonded between the second initial external structure 120 and the internal structure 130, the second protrusion 126a and the second support portion 126c are suspended above the second groove 125b and within the cavity 170.

[0040] It is worth noting that Figure 1B The through hole 160 exposes the first side wall ss1 of the first extension portion 116b of the first metal member 116 and the second side wall ss2 of the second extension portion 126b of the second metal member 126. Figure 1B In the embodiment, the first side wall ss1 and the second side wall ss2 are substantially coplanar.

[0041] Please refer to Figure 1C ,right Figure 1B The main substrate 100a is subjected to through-hole electroplating and a solder mask is formed to form Figure 1C It is worth noting that the metal layer (electroplating layer) in the plated through hole 180 covers and connects the first side wall ss1 of the first extension portion 116b and the second side wall ss2 of the second extension portion 126b. Therefore, the first metal member 116 and the second metal member 126 can be electrically connected to each circuit layer (for example, the circuit layer 114 and the circuit layer 124).

[0042] After forming the plated through hole 180, the solder mask 190 is filled in the plated through hole 180 and covers the upper surfaces of the circuit layers 114 and 124 to protect the circuit layers 114 and 124 of the main substrate 100b. In some embodiments, the material of the solder mask 190 may include a resin material.

[0043] Please refer to Figure 1D ,right Figure 1C The main substrate 100b is cut to expose the cavity 170 from the side of the main substrate 100b, and form Figure 1D Specifically, since a portion of the main substrate 100b is cut away, the original cavity 170 forms a side opening 170a, wherein the side opening 170a exposes the first protrusion 116a of the first metal member 116 and the second protrusion 126a of the second metal member 126. Figure 1C The first initial outer structure 110 is formed after the above steps Figure 1D The first outer structure 110a, and Figure 1C The second initial outer structure 120 is formed after the above steps. Figure 1D The second outer structure 120a.

[0044] exist Figure 1D In one embodiment, the first outer structure 110a and the second outer structure 120a protrude beyond the boundary 130s of the inner structure 130 in the first direction D1. The inner structure 130, the first outer structure 110a, and the second outer structure 120a are stacked in the second direction D2, and the side opening 170a is located in the inner structure 130, the first outer structure 110a, and the second outer structure 120a. The side opening 170a exposes the boundary 130s of the inner structure 130. In other words, the side opening 170a exposes the boundary 130s of the inner structure 130. In some embodiments, the main substrate 100c can be a printed circuit board (PCB) or a high-density interconnect (HDI) board.

[0045] exist Figure 1D In the embodiment, the first protrusion 116a has a first curved surface cs1 protruding toward the second external structure 120a, and the second protrusion 126a has a second curved surface cs2 protruding toward the first external structure 110a, and the first curved surface cs1 and the second curved surface cs2 are arranged opposite to each other, and the first protrusion 116a and the second protrusion 126a are both located in the side opening 170a.

[0046] Please refer to Figure 2 , Figure 2 for Figure 1D 100c is a side view of the main substrate 100c. Figure 2 Two side openings 170a and two pairs of metal parts (a pair of metal parts includes a first metal part 116 and a second metal part 126) are shown, and the solder mask 190 is omitted, wherein the insulating layer 112 and the insulating layer 122 expose the side openings 170a. Figure 2 From the perspective of FIG, it can be seen that the side opening 170a exposes the first protrusion 116a of the first metal member 116 and the second protrusion 126a of the second metal member 126. It should be noted that, Figure 2 The number of the middle side openings 170 a and the metal pieces is only used to describe one embodiment. However, in other implementations, fewer or more side openings 170 a and metal pieces may be included.

[0047] Please refer to Figure 3, which is a cross-sectional view of an extended substrate 300 according to at least one embodiment of the present invention. The extended substrate 300 includes a second inner insulating layer 312, a circuit layer 314, and a circuit layer 316. The second inner insulating layer 312 is disposed between the circuit layer 314 and the circuit layer 316, wherein the circuit layer 314, the circuit layer 316, and the second inner insulating layer 312 are stacked along a second direction D2, as shown in FIG. Figure 3 shown.

[0048] The extended substrate 300 further includes a plurality of plated through holes 320 and a solder mask 330, wherein the solder mask 330 is filled in the plated through holes 320 and covers a portion of the circuit layer 314 and a portion of the circuit layer 316. It is worth noting that the solder mask 330 does not cover another portion of the circuit layer 314 and another portion of the circuit layer 316. In other words, the surface 314s of the circuit layer 314 and the surface 316s of the circuit layer 316 are exposed to the air. The extended substrate 300 can be separated from Figure 1D The side opening 170a is inserted into the main substrate 100c.

[0049] The second inner insulating layer 312 has a material similar to that of the first inner insulating layer 132, and the circuit layer 314 has a material similar to that of the circuit layer 114. The details are not repeated here. In some embodiments, the extension substrate 300 can be a flexible printed circuit (FPC), PCB, or HDI board.

[0050] Please refer to Figure 4 , which is a connection according to an embodiment Figure 1D The main substrate 100c and Figure 2 Schematic cross-sectional view of the circuit board 400 of the extension substrate 300. The circuit board 400 includes the main substrate 100c and the extension substrate 300, and the extension substrate 300 is inserted into the main substrate 100c through the side opening 170a.

[0051] exist Figure 4 In the embodiment, when the extension substrate 300 is inserted into the main substrate 100c through the side opening 170a, the extension substrate 300 is sandwiched between the first metal member 116 and the second metal member 126, and the first inner insulating layer 132 is aligned with the second inner insulating layer 312 in the first direction D1. The first protrusion 116a of the first metal member 116 presses the first circuit layer 314, while the second protrusion 126a of the second metal member 126 presses the second circuit layer 316. Specifically, the first curved surface cs1 of the first protrusion 116a directly contacts the surface 314s of the first circuit layer 314, while the second curved surface cs2 of the second protrusion 126a directly contacts the surface 316s of the second circuit layer 316, thereby achieving electrical continuity between the extension substrate 300 and the main substrate 100c.

[0052] It is understandable that, since the first extension portion 116b is used as a fixed axis, the first protrusion 116a and the first support portion 116c are suspended on the first groove 115b, so when the extension substrate 300 is inserted into the main substrate 100c, the first protrusion 116a and the first support portion 116c will have a force toward the insulating layer 112, such as Figure 4 Similarly, since the second extension portion 126b is used as a fixed axis, the second protrusion 126a and the second support portion 126c are suspended on the second groove 125b. Therefore, when the extension substrate 300 is inserted into the main substrate 100c, the second protrusion 126a and the second support portion 126c will have a force toward the insulating layer 122, as shown in FIG. Figure 4 drawn.

[0053] exist Figure 4 In the embodiment, when the extension substrate 300 is inserted into the main substrate 100c, the first support portion 116c of the first metal member 116 does not contact the first bottom surface 115bs of the first groove 115b, and the second support portion 126c of the second metal member 126 does not contact the second bottom surface 125bs of the second groove 125b.

[0054] Please refer to Figure 5 , which is a connection according to another embodiment Figure 1D The main substrate 100c and Figure 2 FIG2 is an enlarged cross-sectional view of the circuit board 400 of the extension substrate 300. When the extension substrate 300 is inserted into the main substrate 100c, the first support portion 116c of the first metal member 116 contacts the first bottom surface 115bs of the first groove 115b, and the second support portion 126c of the second metal member 126 contacts the second bottom surface 125bs of the second groove 125b.

[0055] In some embodiments, as Figure 1D As shown, when the extension substrate 300 is separated from the main substrate 100c, the first support portion 116c of the first metal member 116 does not contact the first bottom surface 115bs of the first groove 115b, and the second support portion 126c of the second metal member 126 does not contact the second bottom surface 125bs of the second groove 125b.

[0056] In some embodiments, when the extension substrate 300 is separated from the main substrate 100c, the minimum distance between the first curved surface cs1 of the first protrusion 116a and the second curved surface cs2 of the second protrusion 126a is equal to the distance between the surface 314s of the first circuit layer 314 and the surface 316s of the second circuit layer 316. In other embodiments, when the extension substrate 300 is separated from the main substrate 100c, the minimum distance between the first curved surface cs1 of the first protrusion 116a and the second curved surface cs2 of the second protrusion 126a is less than the distance between the surface 314s of the first circuit layer 314 and the surface 316s of the second circuit layer 316.

[0057] The overall thickness of the extension substrate 300 (including the thickness of the solder mask 330) is less than or equal to the height of the side opening 170a of the main substrate 100c. Figure 4 shown.

[0058] It should be noted that the terms "separable" and / or "detachable" mentioned above indicate that the extended substrate 300 can be repeatedly separated and combined with the main substrate 100c without damaging the overall functions of both the extended substrate 300 and the main substrate 100c. The aforementioned situation of "not damaging the overall function" includes slight scratches caused by friction between the surfaces 314s and 316s, and the first curved surface cs1 and the second curved surface cs2 due to multiple insertions and extractions of the extended substrate 300 and the main substrate 100c.

[0059] In other words, even if the surfaces 314s and 316s, the first curved surface cs1, and the second curved surface cs2 are scratched due to repeated insertion and extraction of the extended substrate 300 and the main substrate 100c, the overall functions of the extended substrate 300 and the main substrate 100c will not be damaged, that is, there will be no significant adverse effect on the electrical connection between the extended substrate 300 and the main substrate 100c.

[0060] In summary, the extension substrate disposed on the side of the main substrate can reduce the thickness of the circuit board, facilitating the development of thinner circuit boards. Furthermore, the main substrate includes two opposing metal pieces, each with a corresponding protrusion, allowing the extension substrate to be removably and / or detachably inserted into the main substrate through the side opening of the main substrate, facilitating the reuse of the original main substrate and extension substrate.

[0061] The foregoing summary of the features of the embodiments is presented for purposes of summarizing the application so that those skilled in the art can better understand the application. It is intended that the summary provide a brief overview of the application to assist with understanding the application. It is to be understood that the above-described embodiments are only examples of the many possible arrangements that can be utilized to implement the application. Those skilled in the art will readily appreciate that other arrangements can be utilized and the generic principles of the present application can be applied to other arrangements without departing from the spirit and scope of the present application. Thus, the present application is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the claims, the principles and the practical applications of the application.

[0062] SYMBOL DESCRIPTION

[0063] 100, 100a, 100b, 100c: main substrate

[0064] 110: first initial external structure

[0065] 110a: first external structure

[0066] 112: insulating layer

[0067] 114: circuit layer

[0068] 115a, 115b: first recess

[0069] 115bs: first bottom surface

[0070] 116: first metal piece

[0071] 116a: first protrusion

[0072] cs1: first curved surface

[0073] 116b: first extension

[0074] ss1: first side wall

[0075] 116c: first support

[0076] 120: second initial external structure

[0077] 120a: second external structure

[0078] 122: insulating layer

[0079] 124: circuit layer

[0080] 125a, 125b: second recess

[0081] 125bs: second bottom surface

[0082] 126: second metal piece

[0083] 126a: second protrusion

[0084] cs2: second curved surface

[0085] 126b: Second extension

[0086] ss2: second side wall

[0087] 126c: Second support portion

[0088] 130: Internal structure

[0089] 130s: Boundary

[0090] 132: First inner insulation layer

[0091] 134: Circuit layer

[0092] 140: First adhesive layer

[0093] 150: Second adhesive layer

[0094] 160: Through hole

[0095] 170: Cavity

[0096] 170a: Side opening

[0097] 180: Plated through hole

[0098] 190: solder mask

[0099] 300: Extended substrate

[0100] 312: Second inner insulation layer

[0101] 314: Circuit layer

[0102] 314s: Surface

[0103] 316: Circuit layer

[0104] 316s: Surface

[0105] 320: Plated through hole

[0106] 330: solder mask

[0107] 400: Circuit board

[0108] D1: First direction

[0109] D2: Second direction.

Claims

1. A circuit board, characterized in that: Include: The main substrate includes: A first external structure comprising a first metal member having a first protrusion; a second external structure comprising a second metal member having a second protrusion; an internal structure disposed between the first external structure and the second external structure, wherein the first external structure and the second external structure protrude beyond a boundary of the internal structure in a first direction, wherein the inner structure, the first outer structure, and the second outer structure are stacked in a second direction perpendicular to the first direction, and a side opening is located in the inner structure, the first outer structure, and the second outer structure, and the side opening exposes the boundary, The first convex portion has a first curved surface convex toward the second external structure, and the second convex portion has a second curved surface convex toward the first external structure, and the first curved surface and the second curved surface are arranged opposite to each other, and the first convex portion and the second convex portion are both located in the side opening; a first adhesive layer disposed between the internal structure and the first external structure and connecting the internal structure and the first external structure, wherein the first metal member further comprises a first extension portion disposed between the first adhesive layer and the first external structure, wherein the first extension portion is connected to the first protrusion; as well as a second adhesive layer disposed between the internal structure and the second external structure and connecting the internal structure and the second external structure, wherein the second metal member further comprises a second extension portion disposed between the second adhesive layer and the first external structure, wherein the second extension portion is connected to the second protrusion; and The extension substrate is detachably inserted into the main substrate through the side opening.

2. The circuit board according to claim 1, wherein the internal structure comprises a first internal insulating layer, and the extended substrate comprises: First circuit layer; A second circuit layer; and a second inner insulating layer disposed between the first circuit layer and the second circuit layer, wherein the first circuit layer, the second circuit layer, and the second inner insulating layer are stacked along the second direction; When the extended substrate is inserted into the main substrate from the side opening, the extended substrate is sandwiched between the first metal member and the second metal member, wherein the first protrusion of the first metal member presses the first circuit layer, and the second protrusion of the second metal member presses the second circuit layer. 3 . The circuit board according to claim 2 , wherein the first inner insulating layer is aligned with the second inner insulating layer in the first direction.

4. The circuit board according to claim 1, wherein: The first external structure further includes a first groove, and the first metal member further includes a first supporting portion connected to the first protrusion, wherein the first supporting portion is disposed in the first groove; and The second external structure further includes a second groove, and the second metal part further includes a second supporting portion connected to the second protrusion, wherein the second supporting portion is arranged in the second groove, and the first supporting portion and the second supporting portion are located between the first bottom of the first groove and the second bottom of the second groove.

5. The circuit board according to claim 4, wherein the extended substrate comprises: First circuit layer; A second circuit layer; and a second inner insulating layer disposed between the first circuit layer and the second circuit layer, wherein the first circuit layer, the second circuit layer, and the second inner insulating layer are stacked along the second direction; When the extension substrate is separated from the main substrate, the first support portion of the first metal member does not contact the first bottom surface of the first groove, and the second support portion of the second metal member does not contact the second bottom surface of the second groove.

6. The circuit board according to claim 2 or 5, wherein the minimum distance between the first curved surface of the first convex portion and the second curved surface of the second convex portion is less than or equal to the distance between the surface of the first circuit layer and the surface of the second circuit layer. 7 . The circuit board according to claim 1 , wherein an overall thickness of the extension substrate is less than or equal to a height of the side opening of the main substrate.

8. A method for manufacturing a circuit board, characterized in that: Include: Providing a first initial external structure, wherein the first initial external structure includes a first insulating layer and a first metal member, the first insulating layer includes a plurality of first grooves, the first metal member includes a first protrusion, a first extension, and a first support portion, the first extension and the first support portion are respectively located at two ends of the first protrusion, and the first extension and the first support portion are disposed in the plurality of first grooves in the first insulating layer; Providing a second initial external structure, wherein the second initial external structure includes a second insulating layer and a second metal member, the second insulating layer includes a plurality of second grooves, the second metal member includes a second protrusion, a second extension, and a second support portion, the second extension and the second support portion are respectively located at two ends of the second protrusion, and the second extension and the second support portion are disposed in the plurality of second grooves in the second insulating layer; Provide internal structure; Laminating the first initial external structure, the internal structure, and the second initial external structure to form an initial circuit substrate, wherein the initial circuit substrate includes a cavity, and the first protrusion, the first supporting portion, the second protrusion, and the second supporting portion are located in the cavity, wherein the first protrusion has a first curved surface that is convex toward the second protrusion, and the second protrusion has a second curved surface that is convex toward the first protrusion; forming a through hole in the initial circuit substrate so that the first supporting portion and the second supporting portion are exposed in the through hole; electroplating the through-hole; The initial circuit substrate is cut to expose the cavity from one side of the initial circuit substrate and form the circuit board.

9. The method for manufacturing a circuit board according to claim 8, wherein the method for manufacturing the first initial external structure comprises: Providing a first substrate including the first insulating layer and a first circuit layer; Etching the first circuit layer to form a first circuit layer; forming the plurality of grooves in the first insulating layer; providing the first metal member; The first extension portion and the first support portion of the first metal member are embedded in the plurality of grooves in the first insulating layer to form the first initial external structure.

10. The method for manufacturing a circuit board according to claim 8, wherein after the through-holes are electroplated, a solder resist is formed to fill the plated through-holes and cover the surface of the initial circuit substrate.

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