Circuit board and method of manufacturing the same

Abstract

The application provides a manufacturing method of a circuit board, comprising the following steps: providing an inner circuit board, wherein the inner circuit board comprises an inner substrate layer and an inner circuit layer arranged on the inner substrate layer; arranging ABF on the inner circuit layer; arranging an outer substrate on the ABF, wherein the outer substrate comprises an outer substrate layer and a copper foil layer arranged on the outer substrate layer, the outer substrate layer is arranged between the ABF and the copper foil layer, the outer substrate is provided with a first opening, and the first opening penetrates the outer substrate layer and the copper foil layer; arranging an electroplated layer on the copper foil layer, and part of the electroplated layer is filled into the first opening; removing the part of the electroplated layer filled into the first opening; and etching the copper foil layer and the electroplated layer to form an outer circuit layer. The manufacturing method provided by the application has a simple process and the circuit board manufactured by the device method has a small thickness. In addition, the application also provides a circuit board.

Description

Technical Field

[0001] This application relates to a circuit board and a method for manufacturing the same. Background Technology

[0002] The under-display camera has emerged as a result, and the industry has adopted punch-hole screens to replace notch screens. This has placed higher demands on the radio frequency transmission circuit board of the front-facing camera, namely, it needs to be thinner and also needs to maintain a certain degree of rigidity.

[0003] Typically, radio frequency (RF) transmission circuit boards are partially embedded, meaning that only a portion of the inner circuit board is exposed. To ensure overall flatness and rigidity, a cover layer is placed on the outer side of the inner circuit board. A rigid adhesive layer is then laminated onto the cover layer to add another layer. This makes it difficult to reduce the thickness of the embedded RF transmission circuit board and results in a longer manufacturing process. Furthermore, the embedded RF circuit board requires a blackening treatment (e.g., carbonization) after the cover is removed to improve the density of subsequent electroplating or electroless plating. However, the residues left after the blackening treatment (e.g., graphite) are not only difficult to remove from the cover layer or adhesive layer but can also contaminate the plating solutions. Summary of the Invention

[0004] To address the problems in the background art, this application provides a method for manufacturing a circuit board.

[0005] In addition, this application also provides a circuit board.

[0006] A method for manufacturing a circuit board includes the following steps: providing an inner circuit board, the inner circuit board including an inner substrate layer and an inner circuit layer disposed on the inner substrate layer; forming an ABF (Alternating Air Foil) on the inner circuit layer; forming an outer substrate on the ABF, the outer substrate including an outer substrate layer and a copper foil layer disposed on the outer substrate layer, the outer substrate layer being disposed between the ABF and the copper foil layer, the outer substrate having a first opening penetrating the outer substrate layer and the copper foil layer; forming an electroplated layer on the copper foil layer, a portion of the electroplated layer filling the first opening; removing the portion of the electroplated layer filling the first opening, and etching the copper foil layer and the electroplated layer to form the outer circuit layer, thereby obtaining the circuit board, wherein a portion of the ABF is exposed at the bottom of the first opening.

[0007] Furthermore, the ABF material includes epoxy resin, inorganic filler and polyimide resin, wherein the polyimide resin includes polybutadiene structure, urethane structure, imide structure and phenolic structure.

[0008] Further, the step "etching the copper foil layer and the electroplated layer" includes: depositing a dry film layer on the copper foil layer; exposing and developing the dry film layer to form a photosensitive pattern, the photosensitive pattern having a first window, the first opening being disposed corresponding to the first window; etching the copper foil layer and the electroplated layer to obtain the outer circuit layer and removing the photosensitive pattern.

[0009] Furthermore, before the step "depositing an electroplated layer on the copper foil layer", the method further includes: pressing the inner circuit board, the ABF, and the outer substrate together to obtain an intermediate body, and providing a second opening on the intermediate body, the second opening penetrating the inner circuit board, the ABF, and the outer substrate. The step "depositing an electroplated layer on the copper foil layer" further includes: filling a portion of the electroplated layer into the second opening to form a hollow first conductive body, the first conductive body electrically connecting the inner circuit layer and the outer circuit layer.

[0010] Furthermore, the method includes the steps of: providing a third opening on the intermediate body, the third opening penetrating the outer substrate, and exposing a portion of the inner circuit layer at the bottom of the third opening; and filling a portion of the electroplated layer into the third opening to form a second conductor, the second conductor electrically connecting the inner circuit layer and the outer circuit layer.

[0011] Furthermore, the method includes the step of: providing a solder resist layer on the outer circuit layer, partially filling the hollow first conductor with the solder resist layer, the solder resist layer having a second opening, and the first opening being provided corresponding to the second opening.

[0012] Furthermore, the first opening, the second opening, and the third opening are formed by mechanical drilling or laser drilling.

[0013] Furthermore, the inner circuit board also includes a hollow third conductor, the two inner circuit layers are respectively disposed on opposite sides of the inner substrate layer, the third conductor connects the two inner circuit layers, and the step "setting ABF on the inner circuit layer" further includes: filling part of the ABF into the hollow third conductor.

[0014] A circuit board includes an inner circuit board, an outer circuit board, and an ABF (Automatic Partition Focal Frame). The ABF is disposed between the inner circuit board and the outer circuit board. The outer circuit board has a first opening, and a portion of the ABF is exposed at the bottom of the first opening.

[0015] Furthermore, the inner circuit board includes an inner substrate layer and inner circuit layers disposed on opposite sides of the inner substrate layer, the ABF is disposed between the inner circuit layers and the outer circuit board, and the total thickness of the ABF, the inner substrate layer and the two inner circuit layers is 50 to 70 micrometers.

[0016] Compared to existing technologies, the circuit board manufacturing method provided in this application provides an ABF (Automatic Partition Focal Frame) on the inner circuit layer. The ABF serves both to connect to the outer substrate and to protect the exposed portion of the inner circuit board, thereby replacing the cover layer and adhesive layer on the inner circuit board and reducing the overall thickness of the circuit board. Attached Figure Description

[0017] Figure 1 This is a cross-sectional schematic diagram of an inner circuit board provided in an embodiment of this application.

[0018] Figure 2 This is a cross-sectional schematic diagram of ABF provided in an embodiment of this application.

[0019] Figure 3 This is a cross-sectional schematic diagram of the outer substrate provided in an embodiment of this application.

[0020] Figure 4 For pressing Figure 1 The inner circuit board shown Figure 2 The ABF shown and Figure 3 A schematic diagram of the outer substrate shown.

[0021] Figure 5 For pressing Figure 1 The inner circuit board shown Figure 2 The ABF shown and Figure 3 A schematic diagram of the outer substrate shown.

[0022] Figure 6 for Figure 5 The diagram shows a cross-section of the copper foil layer after an electroplating layer has been applied.

[0023] Figure 7 This is a cross-sectional schematic diagram of a circuit board provided in an embodiment of this application.

[0024] Explanation of main component symbols

[0025] Circuit board 100

[0026] Inner circuit board 10

[0027] Inner substrate layer 11

[0028] Inner circuit layer 12

[0029] Third conductor 13

[0030] Third opening 14

[0031] ABF 20

[0032] outer substrate 30

[0033] Outer substrate layer 31

[0034] Copper foil layer 32

[0035] First opening 33

[0036] Covering part 331

[0037] Intermediate 40

[0038] Second opening 41

[0039] Third opening 42

[0040] Electroplating layer 43

[0041] First conductor 51

[0042] Second conductor 52

[0043] Outer circuit layer 53

[0044] outer circuit board 60

[0045] Solder resist layer 61

[0046] Thicknesses D1, D2, D3

[0047] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0048] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0049] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or may also exist in an intervening component. When a component is considered to be "set on" another component, it can be directly set on the other component or may also exist in an intervening component.

[0050] Please see also Figures 1 to 7 This application provides a method for manufacturing a circuit board 100, including the following steps:

[0051] S1: Please see Figure 1An inner circuit board 10 is provided, the inner circuit board 10 includes an inner substrate layer 11 and two inner circuit layers 12, the two inner circuit layers 12 are disposed on opposite sides of the inner substrate layer 11.

[0052] Please see Figure 1 In this embodiment, the inner circuit board 10 further includes a hollow third conductor 13. The inner circuit board 10 is provided with a third opening 14, which penetrates one of the inner circuit layers 12 and the inner substrate layer 11. Part of the other first inner circuit layer 12 is exposed at the bottom of the third opening 14. The third conductor 13 is disposed in the third opening 14 and electrically connects the two inner circuit layers 12.

[0053] In this embodiment, the material of the inner substrate layer 11 includes, but is not limited to, polyimide (PI), polyester resin (PET), polyethylene naphthalate (PEN), liquid crystal polymer (LCP), and modified polyimide (MPI).

[0054] S2: Please see Figure 2 and Figure 4 An ABF20 (Ajinomoto build-up film, ABF) is respectively disposed on the two inner circuit layers 12, and the thickness D1 of the ABF20 is 10-18 micrometers. The ABF is made of a resin composition for interlayer insulation of multilayer printed circuit boards. The resin polymer includes polyimide resin, epoxy resin, and inorganic filler. The polyimide resin includes polybutadiene, urethane, and imide structures, and has phenolic structures at the molecular ends. The specific surface area of ​​the inorganic filler is 18-50 m². 2 / g.

[0055] S3: Please see Figure 3 and Figure 4 An outer substrate 30 is disposed on each of the two ABF20s. The outer substrate 30 is a single-sided copper-clad laminate. The outer substrate 30 includes an outer substrate layer 31 and a copper foil layer 32 disposed on the outer substrate layer 31. The outer substrate layer 31 is disposed facing the ABF20. The outer substrate 30 is provided with a first opening 33, which penetrates the outer substrate layer 31 and the copper foil layer 32.

[0056] In this embodiment, the material of the outer substrate layer 31 includes, but is not limited to, polyimide (PI), polyester resin (PET), polyethylene naphthalate (PEN), liquid crystal polymer (LCP), and modified polyimide (MPI).

[0057] S4: Please see Figure 4 and Figure 5 The inner circuit board 10, the two ABF20s, and the two outer substrates 30 are pressed together to obtain an intermediate body 40. The first opening 33 of one outer substrate 30 corresponds to the first opening 33 of the other outer substrate 30.

[0058] Please see Figure 5 In this embodiment, during step S4, when pressing the ABF20, a portion of the ABF20 is filled into the hollow third conductor 13, thereby enhancing the bonding strength between the ABF20 and the inner circuit board 10.

[0059] Please see Figure 6 In this embodiment, step S4 further includes: providing a second opening 41 and a third opening 42 on the intermediate body 40. The second opening 41 penetrates the two outer substrates 30, the two ABF20s, and the inner circuit board 10. The third opening 42 penetrates the outer substrates 30 and the ABF20, with a portion of the inner circuit layer 12 exposed at the bottom of the third opening 42. The third openings 42 on the two outer substrates 30 are correspondingly provided.

[0060] S5: Please see Figure 6 An electroplated layer 43 is formed on the two copper foil layers 32. Part of the electroplated layer 43 fills the first opening 33 to form a cover portion 331, and the two cover portions 331 are correspondingly arranged. The cover portion 331 is attached to the inner periphery of the first opening 33. Since the ABF20 has good electroplating adhesion, a dense cover portion 331 can be formed by electroplating on the ABF20 without the need to deposit a graphite layer, thereby reducing the process and lowering the risk of contamination from the electroplating solution.

[0061] In this embodiment, please refer to Figure 6 Step S5 also includes:

[0062] S51: Part of the electroplated layer 43 is filled into the second opening 41 to form a hollow first conductor 51, which electrically connects the two inner circuit layers 12 and the two copper foil layers 32.

[0063] S52: Part of the electroplated layer 43 is filled into the third opening 42 to form a solid second conductor 52. The second conductor 52 is electrically connected to an inner circuit layer 12 and a copper foil layer 32. Two second conductors 52 are arranged correspondingly.

[0064] S6: Please see Figure 7 The portion of the electroplated layer 43 (i.e., the cover portion 331) filling the two first openings 33 is etched away, while the copper foil layer 32 and the electroplated layer 43 are etched to form the outer circuit layer 53. A portion of the ABF20 is exposed at the bottom of the first opening 33 (i.e., a portion of the inner circuit board 10 is exposed in the first opening 33).

[0065] In this embodiment, step S6 includes:

[0066] S61: A dry film layer (not shown) is provided on the copper foil layer 32;

[0067] S62: Expose and develop the dry film layer to form a photosensitive pattern (not shown), the photosensitive pattern having a first window (not shown), the window corresponding to two first openings 33.

[0068] S63: Etching removes a portion of the electroplated layer 43 and a portion of the copper foil layer 32 exposed in the photosensitive pattern to form the outer circuit layer 53. The outer substrate layer 31 and the outer circuit layer 53 disposed on the outer substrate layer 31 together constitute the outer circuit board 60.

[0069] S64: Remove the photosensitive pattern.

[0070] Please see Figure 7 In this embodiment, the following steps are also included:

[0071] S7: A solder resist layer 61 is provided on the two outer circuit layers 53. The solder resist layer 61 has a second opening 611, and the first opening 33 is provided corresponding to the second opening 611, so that the inner circuit board 10 covered by the ABF20 is exposed to the second opening 611. At the same time, a portion of the solder resist layer 61 is filled into the hollow first conductor 51 to obtain the circuit board 100.

[0072] Compared with the prior art, the manufacturing method of the circuit board 100 provided in this application has the following advantages:

[0073] (i) By providing the ABF20 on the inner circuit layer 12, the ABF20 can both connect the outer substrate 30 and protect the exposed part of the inner circuit layer 12, thereby replacing the cover layer and adhesive layer provided on the inner circuit layer 12, which helps to reduce the overall thickness D2 of the circuit board 100 (thickness D2 is less than 180 micrometers).

[0074] (ii) By pressing the inner circuit board 10 and the outer substrate 30 together on opposite sides of the ABF20 in one step, the number of pressing steps is reduced, thus achieving energy saving and emission reduction. Understandably, if the cover layer is pressed onto the inner circuit layer 12 first, and then the adhesive layer and the outer substrate 30 are pressed together, the number of pressing steps will increase, reducing the manufacturing efficiency of the circuit board 100.

[0075] (III) By first creating a first opening 33 through the outer substrate 30, then electroplating a cover portion 331 between the inner circumferences of the first opening 33, and finally removing the cover portion 331, the inner circuit board 10 partially covered with ABF20 is exposed, which simplifies the manufacturing process. Understandably, if a method of pressing before cutting the opening is used, a release film needs to be placed between the outer substrate 30 and the inner circuit board 10 beforehand, resulting in a lengthy manufacturing process.

[0076] Please see Figure 7 This application embodiment also provides a circuit board 100, which includes an inner circuit board 10, an outer circuit board 60, and an ABF20. The ABF20 is disposed between the inner circuit board 10 and the outer circuit board 60, and the thickness D1 of the ABF20 is 10-18 micrometers (see...). Figure 2 The outer circuit board 60 is provided with a first opening 33, and part of the ABF20 is exposed at the bottom of the first opening 33.

[0077] Please see Figure 7 In this embodiment, the inner circuit board 10 includes an inner substrate layer 11 and inner circuit layers 12 disposed on opposite sides of the inner substrate layer 11. The ABF20 is disposed between the inner circuit layer 12 and the outer circuit board 60. The total thickness D3 of the ABF20, the inner substrate layer 11 and the two inner circuit layers 12 is 50 to 70 micrometers.

[0078] The specific embodiments of this application have been described above with reference to the accompanying drawings. However, those skilled in the art will understand that various changes and substitutions can be made to the specific embodiments of this application without departing from the spirit and scope of this application. All such changes and substitutions fall within the scope defined by this application.

Claims

1. A method for manufacturing a circuit board, characterized in that, The steps include: providing an inner circuit board, the inner circuit board including an inner substrate layer and two inner circuit layers disposed on the inner substrate layer, the two inner circuit layers being disposed on opposite sides of the inner substrate layer; ABFs are respectively provided on the two inner circuit layers; An outer substrate is disposed on each of the two ABFs. Each outer substrate includes an outer substrate layer and a copper foil layer disposed on the outer substrate layer. The outer substrate layer is disposed between the corresponding ABF and the copper foil layer. Each outer substrate is provided with a first opening that penetrates the outer substrate layer and the copper foil layer. The first opening of one outer substrate corresponds to the first opening of the other outer substrate. The inner circuit board, the two ABFs and the two outer substrates are pressed together to obtain an intermediate body; An electroplated layer is provided on the two copper foil layers, and a portion of the electroplated layer is filled into the two first openings to form a cover portion. The two cover portions are provided correspondingly and are attached to the inner periphery of the first openings. The cover portion is formed by electroplating without depositing a graphite layer on the ABF. The circuit board is obtained by etching away a portion of the electroplated layer filling the two first openings, and etching the two copper foil layers and the electroplated layer to form two outer circuit layers, wherein a portion of the ABF is exposed at the bottom of the first opening, such that a portion of the inner circuit board covered by the ABF is exposed in the first opening.

2. The manufacturing method as described in claim 1, characterized in that, The ABF material includes epoxy resin, inorganic filler and polyimide resin, and the polyimide resin includes polybutadiene structure, urethane structure, imide structure and phenolic structure.

3. The manufacturing method as described in claim 1, characterized in that, The step "etching the two copper foil layers and the electroplated layer" includes: A dry film layer is disposed on the two copper foil layers; the dry film layer is exposed and developed to form a photosensitive pattern, the photosensitive pattern having a first window, the first window corresponding to two first openings; Etching the two copper foil layers and the electroplated layer to obtain the two outer circuit layers; and Remove the photosensitive pattern.

4. The manufacturing method as described in claim 1, characterized in that, The step of "applying an electroplating layer on the two copper foil layers" includes the following prior steps: A second opening is provided on the intermediate body, and the second opening penetrates the two outer substrates, the two ABFs and the inner circuit board; The step "to provide an electroplated layer on the two copper foil layers" further includes: filling a portion of the electroplated layer into the second opening to form a hollow first conductor, the first conductor being electrically connected to the two inner circuit layers and the two copper foil layers.

5. The manufacturing method as described in claim 4, characterized in that, The method also includes the step of: providing two third openings on the intermediate body, each third opening penetrating the corresponding outer substrate and the ABF, with a portion of the inner circuit layer exposed at the bottom of each third opening, and the two third openings being provided correspondingly; as well as Two second conductors are formed by filling a portion of the electroplated layer into each of the two third openings. Each second conductor is electrically connected to an inner circuit layer and a copper foil layer. The two second conductors are arranged correspondingly.

6. The manufacturing method as described in claim 5, characterized in that, The method also includes the steps of: providing a solder resist layer on the two outer circuit layers, filling a portion of the solder resist layer with the hollow first conductor, the solder resist layer having a second window, and the first opening being provided corresponding to the second window.

7. The manufacturing method as described in claim 6, characterized in that, The first opening, the second opening, and the third opening are formed by mechanical drilling or laser drilling.

8. The manufacturing method as described in claim 1, characterized in that, The inner circuit board also includes a hollow third conductor, which connects the two inner circuit layers. The step "setting ABF on the two inner circuit layers respectively" further includes: A portion of the ABF is filled into the hollow third conductive body.

9. A circuit board manufactured by the method of manufacturing a circuit board according to any one of claims 1 to 8, characterized in that, The device includes an inner circuit board, two outer circuit boards, and two ABFs. The two outer circuit boards are respectively disposed on opposite sides of the inner circuit board. The inner circuit board includes an inner substrate layer and two inner circuit layers disposed on opposite sides of the inner substrate layer. The two ABFs are respectively disposed between the two inner circuit layers and the two outer circuit boards. The two outer circuit boards are each provided with a first opening. The two first openings are correspondingly disposed, and part of the ABF is exposed at the bottom of the first opening, so that part of the inner circuit board covered by the ABF is exposed in the first opening.

10. The circuit board as described in claim 9, characterized in that, Each ABF has a thickness of 10 to 18 micrometers, and the total thickness of the two ABFs, the inner substrate layer, and the two inner circuit layers is 50 to 70 micrometers.

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