Circuit board, method for manufacturing circuit board, and three dimensional electrical connection structure used therefor

Abstract

To provide a circuit board and a method of manufacturing the circuit board capable of significantly reducing manufacturing costs and management costs.SOLUTION: The circuit substrate includes a soft base material core substrate 10a, a first circuit layer, a first solder resist layer, a first protection layer, a rigid substrate, and a plurality of conductors. The soft base core substrate is flexible and has a first surface 10b and a second surface 10c. A first circuit layer having a plurality of electrical connections is disposed on the first surface 10b. The first solder resist layer is coated on the first circuit layer and the first surface 10b, wherein the first solder resist layer has a plurality of cavities, and the cavities are aligned with the electrical connecting portions. The first protective layer is disposed on the first solder resist layer, and a surface of the first protective layer is a flat surface. The rigid substrate is disposed on the first solder resist layer and corresponds to the cavity. A plurality of conductors are formed in the electrical connection portion and are exposed from the hollow portion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) The present invention claims priority to Taiwan Patent Application No. 113127163, filed on July 19, 2024, the entire contents of which are incorporated herein by reference. The present invention relates to the technical field of circuit boards, and more particularly to a circuit board having a core board formed of a soft base material, a method for manufacturing a circuit board, and a three-dimensional electrical connection structure used therein. [Background technology]

[0002] Circuit boards are used to mount electronic components and form electrical connections between them via wiring formed by conductor layers. Electronic components achieve specific functions by transmitting signals and supplying power to each other via the circuit board. Many conventional circuit boards use rigid boards made of glass fiber and epoxy resin as the core substrate. Therefore, to achieve electrical connections between two circuit boards of different heights, or between a circuit board and an electronic component, it is necessary to use a bendable cable or flexible printed circuit board (FPC).

[0003] Furthermore, since various wiring and flexible circuit boards must be manufactured in addition to the circuit board, the internal structure of the electronic device becomes more complex. Furthermore, as the number of electronic components on the circuit board increases, both manufacturing and management costs increase. Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention provides a circuit board, a method for manufacturing a circuit board, and a three-dimensional electrical connection structure used therein, which solves the problem of the prior art that cables or flexible circuit boards must be used when connecting two circuit boards or electronic components of different heights. The purpose of this invention is to solve problems such as the complexity of the configuration of electronic devices and the rising manufacturing and management costs. [Means for solving the problem]

[0005] The circuit board of the present invention includes a flexible substrate core substrate, a first circuit layer, a first solder resist layer, a first protective layer, a rigid substrate, and a plurality of conductors. The flexible substrate core substrate is flexible and has a first surface and a second surface. A first circuit layer is disposed on the first surface and has a plurality of electrical connections. A first solder resist layer is coated on the first circuit layer and the first surface and has a plurality of cavities, each cavity aligned with an electrical connection. The first protective layer is disposed on the first solder resist layer, and the surface of the first protective layer is flat. A rigid substrate is disposed on the first surface. A plurality of conductors are formed on the electrical connection portions and exposed from the hollow portion.

[0006] The manufacturing method of the circuit board structure of the present invention includes the following steps. Providing a circuit board including a flexible substrate core substrate and a first conductor layer disposed on a first surface of the flexible substrate core substrate. Forming a first circuit layer on the first conductor layer, the first circuit layer having a plurality of electrical connections. Coating the first circuit layer and the first surface with a first solder resist layer having a plurality of cavities, the cavities being aligned with the electrical connections. Bonding a first protective layer having a flat surface onto the first solder resist layer. Bonding a rigid substrate to the second surface of the flexible substrate core substrate. Depositing a plurality of conductors on each of the electrical connections by chemical vapor deposition, and exposing the conductors from the hollow portions.

[0007] The three-dimensional electrical connection structure of the present invention includes a first circuit board, a second circuit board, and a connection circuit board. The first circuit board is disposed in a first position and has a first height. The second circuit board is disposed in a second position and has a second height. The connection circuit board connects the first circuit board and the second circuit board. The first circuit board, the second circuit board and the connecting circuit board are an integrated structure, and have the structure according to the circuit boards. [Effects of the Invention]

[0008] The circuit board structure of the present invention does not require cables or flexible substrate circuit boards and can realize an integrated three-dimensional electrical connection structure, thereby simplifying the internal structure of electronic devices and significantly reducing manufacturing and management costs. [Brief explanation of the drawings]

[0009] [Figure 1] 1A to 1C are schematic diagrams illustrating an embodiment of a method for manufacturing a circuit board according to the present invention. [Figure 2] 1A to 1C are schematic diagrams illustrating an embodiment of a method for manufacturing a circuit board according to the present invention. [Figure 3] 1A to 1C are schematic diagrams illustrating an embodiment of a method for manufacturing a circuit board according to the present invention. [Figure 4] 1A to 1C are schematic diagrams illustrating an embodiment of a method for manufacturing a circuit board according to the present invention. [Figure 5] 1A to 1C are schematic diagrams illustrating an embodiment of a method for manufacturing a circuit board according to the present invention. [Figure 6] 1A to 1C are schematic diagrams illustrating an embodiment of a method for manufacturing a circuit board according to the present invention. [Figure 7] 1A to 1C are schematic diagrams illustrating an embodiment of a method for manufacturing a circuit board according to the present invention. [Figure 8] 1A to 1C are schematic diagrams illustrating an embodiment of a method for manufacturing a circuit board according to the present invention. [Figure 9] 1A to 1C are schematic diagrams illustrating an embodiment of a method for manufacturing a circuit board according to the present invention. [Figure 10] 1A to 1C are schematic diagrams illustrating an embodiment of a method for manufacturing a circuit board according to the present invention. [Figure 11] 1A to 1C are schematic diagrams illustrating an embodiment of a method for manufacturing a circuit board according to the present invention. [Figure 12]1 is a schematic diagram illustrating an embodiment of a circuit board according to the present invention. [Figure 13] 5A to 5C are schematic diagrams illustrating another embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 14] 5A to 5C are schematic diagrams illustrating another embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 15] 5A to 5C are schematic diagrams illustrating another embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 16] 5A to 5C are schematic diagrams illustrating another embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 17] 5A to 5C are schematic diagrams illustrating another embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 18] 5A to 5C are schematic diagrams illustrating another embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 19] 5A to 5C are schematic diagrams illustrating another embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 20] 5A to 5C are schematic diagrams illustrating another embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 21] 5A to 5C are schematic diagrams illustrating another embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 22] 5A to 5C are schematic diagrams illustrating another embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 23] 5A to 5C are schematic diagrams illustrating another embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 24] 5A to 5C are schematic diagrams illustrating another embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 25] 5A to 5C are schematic diagrams illustrating another embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 26] 5A to 5C are schematic diagrams illustrating a third embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 27] 5A to 5C are schematic diagrams illustrating a third embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 28] 5A to 5C are schematic diagrams illustrating a third embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 29] 5A to 5C are schematic diagrams illustrating a third embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 30]5A to 5C are schematic diagrams illustrating a third embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 31] 5A to 5C are schematic diagrams illustrating a third embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 32] 5A to 5C are schematic diagrams illustrating a third embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 33] 5A to 5C are schematic diagrams illustrating a third embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 34] 5A to 5C are schematic diagrams illustrating a third embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 35] 5A to 5C are schematic diagrams illustrating a third embodiment of the method for manufacturing a circuit board according to the present invention. [Figure 36] 1 is a schematic diagram illustrating an embodiment of a three-dimensional electrical connection structure of the present invention. DETAILED DESCRIPTION OF THE INVENTION [Example]

[0010] Referring to Figures 1 to 11, one embodiment of a circuit board structure, i.e., a method for manufacturing a circuit board, provided by the present invention is shown. The circuit board of this embodiment is a circuit board having a single conductor layer. As shown in Figure 1, a circuit board substrate 10 is provided. The circuit board substrate 10 includes a core substrate 10a, i.e., a flexible substrate core substrate, and a first conductor layer 11 pre-pressed onto a first surface 10b of the core substrate 10a. In this embodiment, the core substrate 10a is made of a flexible material. Next, as shown in Figure 2, a photoresist layer 12 is coated on the first conductor layer 11. Next, as shown in Figure 3, the photoresist layer 12 is exposed using a photomask M corresponding to the circuit pattern, and the photoresist layer 12 in the portion corresponding to the circuit pattern is hardened. Next, as shown in Figure 4, the unhardened photoresist layer 12 is removed, and the portion corresponding to the circuit pattern is covered with the hardened photoresist layer 12, exposing the first conductor layer 11 not corresponding to the circuit pattern. Next, as shown in FIG. 5, the first conductor layer 11 exposed from the photoresist layer 12 is removed by etching. Then, as shown in FIG. 6, the photoresist layer 12 is removed to obtain a first circuit layer 13. As shown in FIG. 7, a first solder resist layer 14 is coated on the first circuit layer 13. Next, as shown in FIG. 8, the first solder resist layer 14 corresponding to the electrical connection portion 131 on the first circuit layer 13 is removed to form a hollow portion 141. The electrical connection portion 131 can be a gold finger structure for inserting an electrical connector or a solder pad structure for soldering a pin of an electronic component.

[0011] 9, a heat-resistant adhesive film is pressure-bonded to the surface of the first solder resist layer 14 to form the first protective layer 15. The surface of the first protective layer 15 is flat, and the unevenness of the first solder resist layer 14 caused by the difference in height between the first circuit layer 13 and the first surface 10b of the core substrate 10a is filled in by the first protective layer 15, ultimately forming a completely flat surface. The area of ​​the first protective layer 15 does not extend beyond the first solder resist layer 14 where the electrical connection portion 131 of the first circuit layer 13 is located.

[0012] 10, the rigid substrate 16 is adhered to the second surface 10c of the core substrate 10a, that is, arranged at a position corresponding to the electrical connection portion 131 of the first circuit layer 13. The rigid substrate 16 strengthens the edge of the core substrate 10a and can function as a plug-in structure.

[0013] 11, conductors 17 are deposited by chemical vapor deposition on the electrical connection portions 131 of the first circuit layer 13, and the conductors 17 are exposed from the hollow portions 141 of the first solder resist layer 14 so as to be electrically connected to electronic components. In this embodiment, the conductors 17 are made of gold (Au). In this embodiment, the electrical connection portions 131 are formed on the edge of the core substrate 10a, and cooperate with the conductors 17 to form a gold finger structure for plug connection.

[0014] 12, one embodiment of the circuit board provided by the present invention is shown. The circuit board is cut to a desired size and shape. Conductors 17 are placed on the edge of the circuit board and surrounded by a first solder resist layer 14, and the edge of a first protective layer 15 is close to but does not extend to the conductors 17.

[0015] 13 to 24, another embodiment of the method for manufacturing a circuit board of the present invention is shown. The circuit board of this embodiment is a circuit board having two conductor layers. As shown in FIG. 13, a circuit board substrate 10 is provided. The circuit board substrate 10 includes a core substrate 10a, a first conductor layer 11 pre-bonded to a first surface 10b of the core substrate 10a, and a second conductor layer 21 pre-bonded to a second surface 10c of the core substrate 10a. The core substrate 10a of this embodiment is formed of a soft material, and the first conductor layer 11 and the second conductor layer 21 are copper foil layers. Next, as shown in FIG. 14, through holes H are formed by drilling, and then a conductor is plated on the wall of the through hole H by electroplating, thereby establishing electrical continuity between the first conductor layer 11 and the second conductor layer 21. Next, as shown in FIG. 15, a photoresist layer 12 is coated on the first conductor layer 11. Next, as shown in FIG. 16, the photoresist layer 12 is exposed using a photomask M corresponding to the circuit diagram, and the portions of the photoresist layer 12 corresponding to the circuit pattern are hardened. Next, as shown in FIG. 17, the unhardened photoresist layer 12 is removed, and the portions corresponding to the circuit pattern are covered with hardened photoresist layer 12, exposing the first conductor layer 11 not corresponding to the circuit pattern from the photoresist layer 12. Next, as shown in FIG. 18, the first conductor layer 11 exposed from the photoresist layer 12 is removed by etching. As shown in FIG. 19, the photoresist layer 12 is removed to obtain the first circuit layer 13.

[0016] As shown in Fig. 20, a second circuit layer 23 is formed on the second conductor layer 21 using a similar process. Next, as shown in Fig. 21, a first solder resist layer 14 is coated on the first circuit layer 13, and a second solder resist layer 24 is coated on the second circuit layer 23. Next, as shown in Fig. 22, the first solder resist layer 14 corresponding to the electrical connection portion 131 on the first circuit layer 13 is removed to form a hollow portion 141. The electrical connection portion 131 can be a gold finger structure for inserting an electrical connector, or a solder pad structure for soldering the pin of an electronic component.

[0017] 23, a heat-resistant adhesive film is pressure-bonded to the surface of the first solder resist layer 14 to form a first protective layer 15, which has a flat surface. Furthermore, the first protective layer 15 fills in any irregularities in the first solder resist layer 14 caused by the difference in height between the first circuit layer 13 and the first surface 10b of the core substrate 10a, ultimately forming a completely flat surface. The area of ​​the first protective layer 15 does not extend to the first solder resist layer 14 where the electrical connection portions 131 of the first circuit layer 13 are located. Using the same process, a heat-resistant adhesive film is pressure-bonded to the surface of the second solder resist layer 24 to form a second protective layer 25.

[0018] 24, the rigid substrate 16 is placed at a position corresponding to the electrical connection portion 131 of the first circuit layer 13 and is adhered to the second protective layer 25. The rigid substrate 16 strengthens the edge of the core substrate 10a and can function as a plug-in structure.

[0019] 25, conductors 17 are deposited by chemical vapor deposition on the electrical connection portions 131 of the first circuit layer 13, and the conductors 17 are exposed from the hollow portions 141 of the first solder resist layer 14 to form electrical connections with electronic components. In this embodiment, the conductors 17 are made of gold (Au). In this embodiment, the electrical connection portions 131 are formed on the edge of the core substrate 10a, and cooperate with the conductors 17 to form a gold finger structure for plug connection.

[0020] Next, reference will be made to Figures 26 to 35. That is, a third embodiment of the method for manufacturing a circuit board of the present invention is shown. Figure 26 shows a circuit board as shown in Figure 20. This circuit board has a core substrate 10a, a first circuit layer 13 formed on a first surface 10b of the core substrate 10a, and a second circuit layer 23 formed on a second surface 10c of the core substrate 10a. Next, as shown in Figures 27 and 28, a first insulating layer 18 and a third conductor layer 19 are pressure-bonded onto the first circuit layer 13, and a second insulating layer 28 and a fourth conductor layer 29 are pressure-bonded onto the second circuit layer 23. The first insulating layer 18 and the second insulating layer 28 are polypropylene (PP) plates, and the third conductor layer 19 and the fourth conductor layer 29 are copper foil layers.

[0021] 29, through holes H1 and blind holes H2 are formed in the circuit board by drilling, and through holes H that penetrated core substrate 10a, first circuit layer 13, and second circuit layer 23 are converted into buried holes. Next, conductors are formed on the hole walls of through holes H1 and blind holes H2 by electroplating, thereby establishing electrical continuity between first circuit layer 13 and third conductor layer 19, second circuit layer 23 and fourth conductor layer 29, and / or between third conductor layer 19, first circuit layer 13, second circuit layer 23, and fourth conductor layer 29.

[0022] Next, as shown in Fig. 30, a third circuit layer 19a is formed on the third conductor layer 19, and a fourth circuit layer 29a is formed on the fourth conductor layer 29. Next, as shown in Fig. 31, a first solder resist layer 14 is coated on the third circuit layer 19a, and a second solder resist layer 24 is coated on the fourth circuit layer 29a. Next, as shown in Fig. 32, the first solder resist layer 14 corresponding to the electrical connection portion 191 on the third circuit layer 19a is removed to form a hollow portion 141. The electrical connection portion 191 may have a gold finger structure for inserting an electrical connector or a solder pad structure for soldering a pin of an electronic component.

[0023] 33, a heat-resistant adhesive film is pressure-bonded to the surface of the first solder resist layer 14 to form the first protective layer 15. The surface of the first protective layer 15 is flat, and the first protective layer 15 fills in the irregularities in the first solder resist layer 14 caused by the difference in height between the third circuit layer 19a and the first insulating layer 18, ultimately forming a completely flat surface. The area of ​​the first protective layer 15 does not extend to the first solder resist layer 14 where the electrical connection portions 191 of the third circuit layer 19a are located. Using the same process, a heat-resistant adhesive film is pressure-bonded to the surface of the second solder resist layer 24 to form the second protective layer 25.

[0024] 34, the rigid substrate 16 is placed at a position corresponding to the electrical connection portion 131 of the first circuit layer 13 and is adhered to the second protective layer 25. The rigid substrate 16 strengthens the edge of the core substrate 10a and can function as a plug-in structure.

[0025] 35, conductors 17 are deposited by chemical vapor deposition on the electrical connection portions 191 of the third circuit layer 19a, and the conductors 17 are exposed from the hollow portions 141 of the first solder resist layer 14 to form electrical connections with electronic components. In this embodiment, the conductors 17 are made of gold (Au). In this embodiment, the electrical connection portions 191 are formed on the edge of the core substrate 10a, and cooperate with the conductors 17 to form a gold finger structure for plug connection.

[0026] Further, refer to FIG. 36. This shows one embodiment of the three-dimensional electrical connection structure of the present invention. The three-dimensional electrical connection structure of this embodiment includes a first circuit board 100, a second circuit board 200, and a connection circuit board 300. The first circuit board 100 is disposed at a first position, and the first position has a first height. The second circuit board 200 is disposed at a second position, and the second position has a second height. The first height and the second height are based on a certain reference plane, such as the bottom surface of the housing of an electronic device, and the first height and the second height may be the same or different. The connection circuit board 300 connects the first circuit board 100 and the second circuit board 200. The first circuit board 100, the second circuit board 200, and the connection circuit board 300 are integrated, and the first circuit board 100, the second circuit board 200, and the connection circuit board 300 have structures related to the above circuit boards. That is, in the above manufacturing method, after the circuit board is completed, it can be cut into a desired shape and size according to the design configuration. The first circuit board 100 and the second circuit board 200 are used to mount electronic components. The connecting circuit board 300 has a circuit that connects the first circuit board 100 and the second circuit board 200.

[0027] The circuit board of the present invention does not require cables or flexible substrate circuit boards and can realize an integrated three-dimensional electrical connection structure, thereby simplifying the internal structure of electronic devices and significantly reducing manufacturing and management costs.

[0028] The foregoing has outlined several features of the embodiments so that those skilled in the art may better understand aspects of the embodiments of the present invention. Those skilled in the art will appreciate that the embodiments of the present invention may readily be used as a basis for designing or modifying other processes or structures to achieve the same purposes and / or advantages as those described herein. Those skilled in the art will also appreciate that such equivalent constructions do not depart from the spirit and scope of the present invention, and that changes, substitutions, and alterations can be made therein without departing from the spirit and scope of the present invention. The scope of the present invention is defined by the claims. [Explanation of symbols]

[0029] 10 Circuit board base material 10a core board 10b 1st surface 10c 2nd surface 11 First conductor layer 12 Photoresist layer 13 1st circuit layer 14 First solder resist layer 15 1st protective layer 16 Rigid substrate 17 Conductor 18 First insulating layer 19 Third conductor layer 19a 3rd circuit layer 21 Second conductor layer 23 2nd circuit layer 25 Second protective layer 28 Second insulating layer 29 4th conductor layer 29a 4th circuit layer 100 1st circuit board 131 Electrical Connections 141 Hollow part 200 2nd circuit board 300 Connection circuit board H through hole H1 through hole H2 blind hole M Photomask

Claims

1. a flexible substrate core substrate having a first surface and a second surface; a first circuit layer disposed on the first surface and having a plurality of electrical connections; a first solder resist layer coated on the first circuit layer and the first surface, the first solder resist layer having a plurality of hollow portions, the hollow portions being aligned with the electrical connection portions; a first protective layer disposed on the first solder resist layer and having a flat surface; a rigid substrate disposed on the first surface; a plurality of conductors formed on the electrical connection portion and exposed from the hollow portion; A circuit board comprising:

2. a flexible substrate core substrate having a first surface and a second surface; a first circuit layer disposed on the first surface and having a plurality of electrical connections; a second circuit layer disposed on the second surface; a first solder resist layer coated on the first circuit layer and the first surface, the first solder resist layer having a plurality of hollow portions aligned with the electrical connection portions; a second solder resist layer coated on the second circuit layer and the second surface; a first protective layer disposed on the first solder resist layer and having a flat surface; a second protective layer disposed on the second solder resist layer and having a flat surface; a rigid substrate disposed on the second protective layer; a plurality of conductors formed on the electrical connection portion and exposed from the hollow portion; A circuit board comprising:

3. 3. The circuit board according to claim 1, wherein the first circuit layer is made of copper, the conductor is made of gold, and the first protective layer is a heat-resistant adhesive film.

4. a flexible substrate core substrate having a first surface and a second surface; a first circuit layer disposed on the first surface; a second circuit layer disposed on the second surface; a first insulating layer disposed on the first circuit layer; a third circuit layer disposed on the first insulating layer, the first circuit layer having a plurality of electrical connections; a second insulating layer disposed on the second circuit layer; a fourth circuit layer disposed on the second insulating layer; a first solder resist layer coated on the third circuit layer and the first insulating layer, the first solder resist layer having a plurality of hollow portions, the hollow portions being aligned with the electrical connection portions; a first protective layer disposed on the first solder resist layer and having a flat surface; a second solder resist layer coated on the second circuit layer and the second surface; a second protective layer disposed on the second solder resist layer and having a flat surface; a rigid substrate disposed on the second protective layer; a plurality of conductors formed on the electrical connection portion and exposed from the hollow portion; A circuit board comprising:

5. providing a circuit board including a flexible substrate core substrate and a first conductor layer disposed on a first surface of the flexible substrate core substrate; forming a first circuit layer on the first conductor layer, the first circuit layer having a plurality of electrical connections; coating the first circuit layer and the first surface with a first solder resist layer having a plurality of hollows, the hollows being aligned with the electrical connections; bonding a first protective layer having a flat surface onto the first solder resist layer; bonding a rigid substrate to a second surface of the flexible substrate core substrate; depositing a plurality of conductors on the electrical connection portions by chemical vapor deposition, and exposing the conductors from the hollow portions; A method for manufacturing a circuit board, comprising:

6. providing a circuit board including a flexible substrate core substrate, a first conductor layer disposed on a first surface of the flexible substrate core substrate, and a second conductor layer disposed on a second surface of the flexible substrate core substrate; forming a first circuit layer having a plurality of electrical connections on the first conductor layer; forming a second circuit layer on the second conductor layer; coating the first circuit layer and the first surface with a first solder resist layer having a plurality of hollows, the hollows being aligned with the electrical connections; coating the second circuit layer and the second surface with a second solder resist layer; bonding a first protective layer having a flat surface onto the first solder resist layer; bonding a second protective layer having a flat surface on the second solder resist layer; bonding a rigid substrate to the second protective layer; depositing a plurality of conductors on the electrical connection portions by chemical vapor deposition, and exposing the conductors from the hollow portions; A method for manufacturing a circuit board, comprising:

7. 7. The method for manufacturing a circuit board according to claim 6, wherein the first protective layer and the second protective layer are bonded to the first solder resist layer and the second solder resist layer by a thermocompression bonding process via a heat-resistant adhesive film.

8. providing a circuit board including a flexible substrate core substrate, a first conductor layer disposed on a first surface of the flexible substrate core substrate, and a second conductor layer disposed on a second surface of the flexible substrate core substrate; forming a first circuit layer on the first conductor layer; forming a second circuit layer on the second conductor layer; providing a first insulating layer, a third conductor layer, a second insulating layer, and a fourth conductor layer; bonding the first insulating layer to the first circuit layer and the first surface, and bonding the second insulating layer to the second circuit layer and the second surface; bonding the third conductor layer to the first insulating layer and bonding the fourth conductor layer to the second insulating layer; forming a third circuit layer having a plurality of electrical connections on the third conductor layer and forming a fourth circuit layer on the fourth conductor layer; coating the third circuit layer with a first solder resist layer having a plurality of hollow portions, the hollow portions being aligned with the electrical connection portions; coating the fourth circuit layer with a second solder resist layer; bonding a rigid substrate to the second protective layer; depositing a plurality of conductors on the electrical connections by a chemical vapor deposition process, the conductors being exposed from the hollow portion; A method for manufacturing a circuit board, comprising:

9. a first circuit board disposed at a first position and having a first height; a second circuit board disposed in a second position and having a second height; a connection circuit board that connects the first circuit board and the second circuit board; Equipped with The first circuit board, the second circuit board, and the connecting circuit board have a structure according to the circuit board of any one of claims 1, 2, and 4, and are an integrated structure. Three-dimensional electrical connection structure.

10. 10. The three-dimensional electrical interconnect structure of claim 9, wherein the first height is not equal to the second height.

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