Circuit board and manufacturing method thereof

Abstract

The application provides a preparation method of a circuit board, comprising the following steps: providing a substrate comprising a base material layer and a conductive layer, the conductive layer comprising a first surface and a second surface; cutting the conductive layer to form a plurality of first openings arranged at intervals and penetrating through the second surface, the cross section of each first opening being an inverted trapezoid or an inverted triangle; forming a first filling layer in each first opening; removing the base material layer and forming a pattern film provided with a plurality of windows on the first surface, part of the first surface being exposed in the windows; etching the exposed first surface to form second openings communicating with the first openings, so that the conductive layer is divided into a plurality of conductive bodies arranged at intervals, part of the first openings and the second openings jointly forming first hole portions, and the remaining first openings forming second hole portions, the cross section of the second hole portions being an inverted trapezoid, and the first hole portions and the second hole portions jointly forming through holes; and removing the pattern film. The preparation method provided by the application is beneficial to improving the processing efficiency. The application also provides a circuit board.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of circuit board processing, in particular to a circuit board and a preparation method thereof. BACKGROUND

[0002] In the preparation of a circuit board, a horizontal spray etching method is usually used to etch a conductive layer (e.g. a copper layer) to prepare a conductive circuit layer. The etching liquid reacts with the top layer of the conductive layer and can quickly flow out of the board, so the etching liquid is quickly updated and does not cause side etching of the conductive circuit layer. However, as the etching depth increases, the etching liquid will stagnate in the conductive layer, causing the update speed of the etching liquid to slow down, thereby affecting the longitudinal etching speed of the etching liquid. Therefore, the above preparation method has the disadvantage of low processing efficiency. SUMMARY

[0003] Therefore, the present application provides a preparation method of a circuit board which is beneficial to improve the processing efficiency.

[0004] In addition, the present application also provides a circuit board.

[0005] The present application provides a preparation method of a circuit board, comprising the following steps: providing a substrate, the substrate comprising a substrate layer and a conductive layer stacked along a first direction, the conductive layer comprising a first surface connected to the substrate layer and a second surface arranged away from the first surface; cutting the conductive layer to form a plurality of first openings penetrating at least the second surface, the plurality of first openings being arranged at intervals along a second direction perpendicular to the first direction, and each of the first openings being a reversed trapezoid or a reversed triangle in cross section parallel to the first direction and the second direction; forming a first filling layer in each of the first openings; removing the substrate layer and forming a pattern film on the first surface, the pattern film being provided with a plurality of windows arranged at intervals along the second direction, one window corresponding to one first opening, and part of the first surface being exposed in the window; etching the exposed first surface to form a second opening communicating with the first opening along the first direction, so that the conductive layer is divided into a plurality of conductive bodies arranged at intervals along the second direction, the plurality of conductive bodies forming a conductive circuit layer, part of the first opening and the second opening adjacent to the second opening in the first direction together forming a first hole part, and the remaining first openings forming a second hole part, the second hole part being a reversed trapezoid in cross section parallel to the first direction, and the first hole part and the second hole part together forming a through hole; and removing the pattern film.

[0006] In some possible embodiments, the conductive body comprises a third surface divided by the first surface, and after the pattern film is removed, the preparation method further comprises the step of: forming a second filling layer in the first hole part, the second filling layer also covering the third surface.

[0007] In some possible implementation, the conductive body further comprises a fourth surface partitioned by the second surface, the first filling layer further covers the fourth surface, and the manufacturing method further comprises: forming a first protective layer on the first filling layer; and forming a second protective layer on the second filling layer.

[0008] In some possible implementation, the first hole portion is square in cross section parallel to the first direction and the second direction.

[0009] In some possible implementation, the second hole portion is inverted isosceles trapezoid in cross section parallel to the first direction and the second direction.

[0010] The application further provides a circuit board comprising conductive circuit layers and a first filling layer stacked along a first direction. The conductive circuit layers comprise a plurality of conductive bodies arranged at intervals along a second direction perpendicular to the first direction. A through hole is formed between two adjacent conductive bodies. The through hole comprises a first hole portion and a second hole portion communicating along the first direction. The second hole portion is inverted trapezoid in cross section parallel to the first direction. The first filling layer is arranged in the second hole portion. Part of the first filling layer further extends into the first hole portion.

[0011] In some possible implementation, the conductive body comprises a third surface arranged away from the first filling layer, and the circuit board further comprises a second filling layer arranged in the first hole portion and covering the third surface.

[0012] In some possible implementation, the conductive body further comprises a fourth surface arranged away from the third surface, the first filling layer further covers the fourth surface, and the circuit board further comprises a first protective layer arranged on a surface of the first filling layer away from the fourth surface and a second protective layer arranged on a surface of the second filling layer away from the third surface.

[0013] In some possible implementation, the first hole portion is square in cross section parallel to the first direction and the second direction.

[0014] In some possible implementation, the second hole portion is inverted isosceles trapezoid in cross section parallel to the first direction and the second direction.

[0015] In the present application, the first opening is formed by cutting, and the second opening which is communicated with the first opening along the first direction is formed by etching. The etching liquid only needs to etch part of the thickness (along the first direction) of the conductive layer, so that the conductive layer forms a conductor. Therefore, the preparation method of the present application can reduce the etching depth to facilitate the updating speed of the etching liquid, so as to improve the etching speed of the etching liquid in the first direction. Therefore, the preparation method provided by the present application can improve the processing efficiency of the circuit board. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 A cross-sectional view of a substrate provided by an embodiment of the present application;

[0017] Figure 2 A cross-sectional view of forming a first opening in a conductive layer of a substrate shown in Figure 1

[0018] A cross-sectional view of forming a first filling layer in the first opening and forming a first protective layer on the first filling layer shown in Figure 3 Figure 2 A cross-sectional view of removing a base material layer of the substrate shown in

[0019] Figure 4 A cross-sectional view of forming a dry film layer on the first filling layer and the conductive layer shown in Figure 3

[0020] A cross-sectional view of selectively exposing the dry film layer to light to form an exposed area; Figure 5

[0021] A cross-sectional view of forming an opening window by removing the exposed area shown in Figure 6 Figure 5 A cross-sectional view of etching the first surface of the conductive layer exposed to the opening window shown in

[0022] Figure 7 Figure 6 A cross-sectional view of removing the patterned film and the dry film layer shown in

[0023] Figure 8 A cross-sectional view of forming a second filling layer in the through hole shown in Figure 7

[0024] A cross-sectional view of forming a second protective layer on the second filling layer shown in Figure 9 Figure 8 MAIN ELEMENT SYMBOL EXPLANATION

[0025] Circuit board 100 Conductive circuit layer 10

[0026] First hole part 101 Second hole part 102

[0027] ​​​​​

[0028] via hole 103 first opening 104

[0029] second opening 105 conductive layer 106

[0030] first surface 107 second surface 108

[0031] substrate layer 109 substrate 110

[0032] conductor 11 third surface 111

[0033] fourth surface 112 first filling layer 20

[0034] second filling layer 30 first protective layer 40

[0035] second protective layer 50 window 71

[0036] dry film layer 60 first direction X

[0037] second direction Y exposure area 61

[0038] pattern film 70

[0039] The following detailed description will further describe the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be described clearly and completely in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all.

[0041] It should be noted that when an element is referred to as being "fixed" to another element, it can be directly on the other element or there can be an intervening element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or there can be an intervening element. When an element is referred to as being "disposed" on another element, it can be directly disposed on the other element or there can be an intervening element.

[0042] Embodiment 1

[0043] The present application provides a preparation method of a circuit board. According to different needs, the order of steps of the preparation method can be changed, and some steps can be omitted or combined. The preparation method comprises the following steps:

[0044] Step one: refer to Figure 1, providing a substrate 110. The thickness direction of the substrate 110 is defined as a first direction X, and the extension direction of the substrate 110 is defined as a second direction Y. The substrate 110 includes a base layer 109 and a conductive layer 106 stacked along the first direction X. In this embodiment, a conductive layer 106 is provided on one surface of the base layer 109. In another embodiment, a conductive layer 106 may be provided on two opposite surfaces of the base layer 109. Exemplarily, the material of the base layer 109 may be one of polyimide, liquid crystal polymer or polyethylene terephthalate. Exemplarily, the material of the conductive layer 106 may be one of copper or a copper alloy. The conductive layer 106 includes a first surface 107 connected to the base layer 109 and a second surface 108 disposed away from the first surface 107. In some embodiments, the spacing between the first surface 107 and the second surface 108 may be greater than or equal to 35 μm.

[0045] Step 2: Reference Figure 2 , cutting the conductive layer 106 to form a plurality of first openings 104 that at least penetrate the second surface 108. Exemplarily, the conductive layer 106 can be cut by a cutter to form the first openings 104. The plurality of first openings 104 are spaced apart along the second direction Y. The cross-section of each first opening 104 parallel to the first direction X and the second direction Y is an inverted trapezoid or an inverted triangle. In this embodiment, the cross-section of the first opening 104 is an inverted triangle. Alternatively, the cross-section of the first opening 104 is an inverted isosceles triangle. The first opening 104 only penetrates the second surface 108.

[0046] In another embodiment, the first opening 104 may penetrate both the first surface 107 and the second surface 108 to facilitate positioning and windowing of the graphic film in subsequent steps.

[0047] Step 3: Form a first filling layer 20 within each first opening 104. Optionally, the first filling layer 20 also covers the second surface 108 without the first opening 104. Exemplarily, the first filling layer 20 can be an insulating adhesive or insulating ink. Exemplarily, the first filling layer 20 can be formed by lamination or printing.

[0048] In some embodiments, a first protective layer 40 is formed on the first filling layer 20 such that the first protective layer 40 is disposed away from the substrate layer 109. For example, the material of the first protective layer 40 can be polyimide or polyethylene terephthalate. The first filling layer 20 and the first protective layer 40 can be formed in separate steps or simultaneously.

[0049] Step 4: Reference Figure 3 and Figure 4 , remove the base material layer 109. A dry film layer 60 is formed on the first surface 107 and the first protective layer 40 respectively.

[0050] Step five: referring to FIG. 1 1, the dry film layer 60 disposed on the first surface 107 is selectively exposed, such that the dry film layer 60 disposed on the first surface 107 forms a plurality of exposed regions 61 arranged along the second direction Y. One exposed region 61 of the dry film layer 60 corresponds to one first opening 104. Figure 5

[0051] Step six: referring to FIG. 1 1, the plurality of exposed regions 61 are removed by developing, such that a plurality of windows 71 arranged along the second direction Y are formed, and the dry film layer 60 disposed on the first surface 107 forms a patterned film 70. One window 71 corresponds to one first opening 104. Part of the first surface 107 is exposed by the window 71. Optionally, the window 71 has a square shape along a cross section parallel to the first direction X and the second direction Y. Figure 5 Figure 6

[0052] In another embodiment, steps four to six can be omitted. After the substrate layer 109 is removed, the patterned film 70 having a plurality of windows 71 arranged along the second direction Y can be formed on the first surface 107 by screen printing. One window 71 corresponds to one first opening 104. Part of the first surface 107 is exposed by the window 71.

[0053] Step seven: referring to FIG. 1 1, the first surface 107 exposed by the window 71 is etched to form a second opening 105 communicating with the first opening 104 along the first direction X, and the first opening 104 and the second opening 105 together divide the conductive layer 106 into a plurality of conductive bodies 1 1 arranged along the second direction Y. The plurality of conductive bodies 1 1 form the conductive line layer 10. Exemplarily, the second opening 105 can be formed by etching using an acidic etching solution (e.g., a mixture of copper chloride and hydrochloric acid) or an alkaline etching solution (e.g., a mixture of copper chloride and ammonia). After the conductive layer 106 is divided, the first surface 107 and the second surface 108 of the conductive layer 106 are also divided into a plurality of third surfaces 1 1 1 and a plurality of fourth surfaces 1 12, respectively. Each conductive body 1 1 includes one third surface 1 1 1 divided from the first surface 107 and one fourth surface 1 12 divided from the second surface 108. The first filling layer 20 also covers the fourth surface 1 12. The first protective layer 40 is disposed away from the fourth surface 1 12. Part of the first opening 104 and the second opening 105 disposed adjacent to each other along the first direction X form a first hole portion 101, and the part of the first opening 104 is surrounded by the second opening 105. The remaining first openings 104 form a second hole portion 102. The first hole portion 101 and the second hole portion 102 together form a through hole 103. The second hole portion 102 has an inverted trapezoidal structure along a cross section parallel to the first direction X and the second direction Y. Figure 6 Figure 7

[0054] ​​​​​In some embodiments, the cross section of the second hole portion 102 parallel to the first direction X and the second direction Y is an inverted isosceles trapezoid, so as to increase the distribution density of the conductors 11 .

[0055] In some embodiments, the cross section of the first hole portion 101 parallel to the first direction X and the second direction Y is square. The symmetrical arrangement of the first hole portions 101 also facilitates increasing the distribution density of the conductors 11. The shape of the first hole portion 101 can be controlled by controlling the spacing between two adjacent third surfaces 111 in the second direction Y. Specifically, referring to Figure 7 When the distance between two adjacent third surfaces 111 in the second direction Y is smaller, the etching depth required to form the second opening 105 is smaller, thereby facilitating the rapid replacement of the etching solution during etching. The rapid replacement of the etching solution can avoid side etching of the conductor 11, thereby making the cross-section of the first hole portion 101 parallel to the first direction X and the second direction Y square. The preparation method provided in this application facilitates the formation of thick copper and fine-pitch circuit boards, and can reduce side etching of the conductor 11 by controlling the range of the line pitch.

[0056] Step 8: Reference Figure 7 and Figure 8 , remove the graphic film 70 and the dry film layer 60. Exemplarily, the graphic film 70 and the dry film layer 60 can be removed by an alkaline cleaning solution (such as a sodium carbonate solution) or an acidic cleaning solution (such as a nitric acid solution).

[0057] Step 9: Reference Figure 9 , forming a second filling layer 30 within the first hole 101. The second filling layer 30 also covers the third surface 111 and is connected to the first filling layer 20 disposed within the second hole 102. Exemplarily, the second filling layer 30 may be an insulating adhesive layer or insulating ink. The second filling layer 30 may be formed by lamination or printing.

[0058] In some embodiments, a second protective layer 50 is formed on the second filling layer 30 to obtain the circuit board 100. The second protective layer 50 is disposed away from the third surface 111. For example, the material of the second protective layer 50 can be polyimide or polyethylene terephthalate. The second protective layer 50 and the second filling layer 30 can be formed simultaneously or in separate steps.

[0059] In another embodiment, step nine may be omitted.

[0060] In the present application, a first opening 104 is first formed by cutting, and then a second opening 105 is formed by etching, which is connected to the first opening 104 along the first direction X. The etching liquid only needs to etch a portion of the thickness (along the first direction X) of the conductive layer 106 to form the conductive body 11 from the conductive layer 106. Therefore, the preparation method of the present application can reduce the etching depth to increase the etching liquid renewal speed, thereby increasing the etching speed of the etching liquid in the first direction X. Therefore, the preparation method provided by the present application can improve the processing efficiency of the circuit board 100.

[0061] Example 2:

[0062] Reference Figure 9 In one embodiment of the present application, a circuit board 100 is provided. The circuit board 100 can be prepared by the method of Example 1. The circuit board 100 includes a conductive circuit layer 10 and a first filling layer 20 stacked along a first direction X. The conductive circuit layer 10 includes a plurality of conductors 11 arranged at intervals along a second direction Y perpendicular to the first direction X. A through hole 103 is formed between two adjacent conductors 11. The through hole 103 includes a first hole portion 101 and a second hole portion 102 connected along the first direction X. Exemplarily, the first hole portion 101 is formed by etching. The second hole portion 102 is formed by cutting. The cross-section of the second hole portion 102 parallel to the first direction X is an inverted trapezoid. The first filling layer 20 is disposed in the second hole portion 102. Part of the first filling layer 20 also extends into the first hole portion 101.

[0063] In some embodiments, the cross section of the first hole portion 101 parallel to the first direction X and the second direction Y is square, so as to improve the distribution density of the conductors 11 .

[0064] In some embodiments, the cross section of the second hole portion 102 parallel to the first direction X and the second direction Y is an inverted isosceles trapezoid, which also facilitates improving the distribution density of the conductors 11 .

[0065] The conductor 11 includes a third surface 111 disposed away from the first filling layer 20 and a fourth surface 112 disposed away from the third surface 111. In some embodiments, the first filling layer 20 also covers the fourth surface 112. In some embodiments, the circuit board 100 also includes a second filling layer 30. The second filling layer 30 is fixed within the first hole 101 and also covers the third surface 111 and is connected to the first filling layer 20 located within the second hole 102. The arrangement in which the first filling layer 20 also covers the fourth surface 112 and the second filling layer 30 also covers the third surface 111 facilitates protection of the conductor 11 and stabilizes the line spacing of the conductor 11.

[0066] In some embodiments, the circuit board 100 further comprises a first protective layer 40 and a second protective layer 50. The first protective layer 40 is arranged on the surface of the first filling layer 20 away from the fourth surface 112. The second protective layer 50 is arranged on the surface of the second filling layer 30 away from the third surface 111. The arrangement of the first protective layer 40 and the second protective layer 50 can protect the first filling layer 20 and the second filling layer 30.

[0067] The materials of the elements in this embodiment are the same as those of the corresponding elements in Embodiment 1, and thus will not be described again.

[0068] The above description is merely one specific implementation of the present application, but in practical applications, it cannot be limited to this implementation. Other modifications and changes made by those skilled in the art according to the technical concept of the present application should all fall within the protection scope of the present application.

Claims

1. A method for preparing a circuit board, characterized in that: The steps include: Providing a substrate, the substrate comprising a base material layer and a conductive layer stacked along a first direction, the conductive layer comprising a first surface connected to the base material layer and a second surface disposed away from the first surface; cutting the conductive layer to form a plurality of first openings penetrating at least the second surface, wherein the plurality of first openings are spaced apart along a second direction perpendicular to the first direction, and each of the first openings has a cross-section parallel to the first direction and the second direction that is an inverted trapezoid or an inverted triangle; forming a first filling layer in each of the first openings; The substrate layer is removed and a graphic film is formed on the first surface, wherein the graphic film has a plurality of windows arranged at intervals along the second direction, each window being arranged corresponding to each first opening, and a portion of the first surface is exposed through the window; Etching the exposed first surface to form a second opening connected to the first opening along the first direction, so that the conductive layer is divided into a plurality of conductive bodies arranged at intervals along the second direction, the plurality of conductive bodies forming a conductive circuit layer, the first opening and the second opening in a portion adjacent to the second opening in the first direction jointly forming a first hole portion, and the remaining first opening forming a second hole portion, the second hole portion having an inverted trapezoidal cross-section along the first direction parallel to the first direction, and the first hole portion and the second hole portion jointly forming a through hole; and The graphic film is removed.

2. The preparation method according to claim 1, wherein The conductor includes a third surface obtained by dividing the first surface. After removing the pattern film, the preparation method further includes the steps of: A second filling layer is formed in the first hole portion, and the second filling layer also covers the third surface.

3. The preparation method according to claim 2, wherein The conductor further includes a fourth surface obtained by dividing the second surface, the first filling layer further covers the fourth surface, and the preparation method further includes: forming a first protective layer on the first filling layer; A second protective layer is formed on the second filling layer.

4. The preparation method according to claim 1, wherein A cross section of the first hole portion parallel to the first direction and the second direction is square.

5. The preparation method according to claim 4, wherein A cross section of the second hole portion parallel to the first direction and the second direction is an inverted isosceles trapezoid.

6. A circuit board manufactured by the method for manufacturing a circuit board according to any one of claims 1 to 5, the circuit board comprising a conductive circuit layer and a first filling layer stacked along a first direction, the conductive circuit layer comprising a plurality of conductors spaced apart along a second direction perpendicular to the first direction, with a through hole formed between two adjacent conductors, characterized in that: The through hole includes a first hole portion and a second hole portion connected along the first direction, the cross section of the second hole portion along the first direction is an inverted trapezoid, the first filling layer is arranged in the second hole portion, and part of the first filling layer also extends into the first hole portion.

7. The circuit board according to claim 6, wherein: The conductor includes a third surface disposed away from the first filling layer. The circuit board further includes a second filling layer, which is disposed in the first hole and also covers the third surface.

8. The circuit board according to claim 7, wherein: The conductor also includes a fourth surface arranged away from the third surface, and the first filling layer also covers the fourth surface. The circuit board also includes a first protective layer and a second protective layer. The first protective layer is arranged on the surface of the first filling layer away from the fourth surface, and the second protective layer is arranged on the surface of the second filling layer away from the third surface.

9. The circuit board according to claim 6, wherein: A cross section of the first hole portion parallel to the first direction and the second direction is square.

10. The circuit board according to claim 6 or 9, characterized in that: A cross section of the second hole portion parallel to the first direction and the second direction is an inverted isosceles trapezoid.

Images