Method for manufacturing circuit board

Abstract

The present application proposes a method for manufacturing a circuit board, comprising the steps of: providing a circuit substrate, the circuit substrate comprising an outer conductive layer and at least one inner conductive layer, the outer conductive layer being arranged on opposite sides of the inner conductive layer; providing a first opening in the circuit substrate, the first opening penetrating the outer conductive layer and the inner conductive layer; providing a conductive sheet in the first opening, the conductive sheet being electrically connected to the inner conductive layer and electrically isolated from the outer conductive layer; and performing electroplating in the first opening having the conductive sheet, and electrically connecting the conductive sheet to the electroplating cathode, thereby forming a conductive column in the first opening to obtain a circuit board. The manufacturing method provided in the present application provides a conductive sheet electrically connected to the electroplating cathode, so that the electroplating deposition starts from the conductive sheet and slowly fills the first opening, which is beneficial to maintaining the uniform plating force in the hole and reducing the gradual shrinkage of the hole ring of the first opening, thereby reducing the generation of cavitation or burrs.

Description

Technical Field

[0001] The present application relates to a method for manufacturing a circuit board. Background Art

[0002] The traditional through-hole electroplating process for PCBs requires drilling the PCB, then metallizing the hole walls, and finally filling the holes with electroplating to form copper pillars. However, to improve the efficiency of electroplating, high current density is required. This can easily lead to a dog-bone effect during the electroplating process. As the electroplating time increases, the throwing power decreases and the annular ring gradually shrinks. This can easily lead to cavitation or burrs, which can affect the thermal and electrical conductivity of the subsequent copper pillars. Summary of the Invention

[0003] In view of this, the present application provides a method for manufacturing a circuit board to reduce the generation of cavitation or burrs in conductive pillars.

[0004] A method for manufacturing a circuit board comprises the following steps: providing a circuit substrate, the circuit substrate comprising an outer conductive layer and at least one inner conductive layer, the outer conductive layers being disposed on opposite sides of the inner conductive layer; providing a first opening in the circuit substrate, the first opening penetrating the outer conductive layer and the inner conductive layer; providing a conductive sheet in the first opening, the conductive sheet being electrically connected to the inner conductive layer and electrically isolated from the outer conductive layer; and performing electroplating in the first opening having the conductive sheet, and electrically connecting the conductive sheet to an electroplating cathode, thereby forming a conductive column in the first opening, thereby obtaining the circuit board.

[0005] Furthermore, the step of "disposing a conductive sheet in the first opening" includes: electroplating in the first opening to form a first metal layer, the first metal layer including a first end, a second end, and a conductive sheet connected between the first end and the second end, the first end and the second end being electrically connected to the outer conductive layer; and removing the first end and the second end to disconnect the conductive sheet from the outer conductive layer.

[0006] Furthermore, the circuit substrate further includes a plurality of insulating layers, wherein the insulating layer is disposed between the outer conductive layer and the inner conductive layer, or the insulating layer is disposed between two adjacent inner conductive layers.

[0007] Furthermore, the first end portion and the second end portion extend along a thickness direction of the circuit substrate, and the first end portion or the second end portion corresponds to the outer conductive layer and at least one of the insulating layers.

[0008] Furthermore, the method further includes the steps of: providing a second opening in the circuit substrate, the second opening penetrating the outer conductive layer and the inner conductive layer, and electroplating in the second opening to form a second metal layer, the second metal layer electrically conducting the outer conductive layer and the inner conductive layer.

[0009] Furthermore, the step of “performing electroplating in the first opening having the conductive sheet” includes:

[0010] A dry film layer is disposed on the outer conductive layer, the dry film layer having an opening, the first opening being exposed at the bottom of the opening, and the dry film layer covering the second opening. The circuit substrate is immersed in an electroplating solution, and the second metal layer is electrically connected to the electroplating cathode to perform electroplating, and the dry film layer is removed.

[0011] Furthermore, the method further includes: removing a portion of the conductive pillar extending outward from an outer side surface of the outer conductive layer.

[0012] Furthermore, the method further comprises the step of electroplating to form a covering layer on the outer conductive layer, wherein the covering layer covers the conducting pillar.

[0013] Furthermore, the inner diameter of the first opening is 0.1 to 0.8 mm.

[0014] Furthermore, the thickness of the circuit substrate is 1 to 5 mm.

[0015] The manufacturing method provided in the present application sets a conductive sheet electrically connected to the electroplating cathode, so that the electroplating deposition starts from the conductive sheet and then fills the first opening, which is beneficial to maintaining the uniform plating force in the hole and reducing the occurrence of the hole ring of the first opening gradually shrinking, thereby reducing the generation of cavitation or burrs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of a circuit substrate provided in an embodiment of the present application.

[0017] Figure 2 yes Figure 1 The schematic diagram of the substrate after the first opening is set is shown.

[0018] Figure 3 yes Figure 2 Schematic diagram of disposing a first metal layer in the first opening.

[0019] Figure 4 Remove some of the Figure 3 Schematic diagram after the first metal layer is removed to leave a conductive sheet.

[0020] Figure 5 It is Figure 4 Schematic diagram of electroplating on the conductive sheet shown.

[0021] Figure 6 A schematic diagram of a circuit board provided in an embodiment of the present application.

[0022] Description of main component symbols

[0023] Circuit board 100

[0024] Circuit board 10

[0025] Outer conductive layer 11

[0026] Dry film layer 111

[0027] Opening 112

[0028] Inner conductive layer 12

[0029] Insulation layer 13

[0030] First opening 14

[0031] First metal layer 141

[0032] First end portion 142

[0033] Second end portion 143

[0034] Conductive sheet 15

[0035] Second opening 16

[0036] Second metal layer 161

[0037] Conductive column 50

[0038] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0040] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. When an element is referred to as being "disposed on" another element, it may be directly disposed on the other element or there may be an intermediate element.

[0041] See Figures 1 to 6The present invention provides a method for manufacturing a circuit board 100 to form a conductive column 50 in a circuit substrate 10. The conductive column 50 is used to electrically connect the conductive layers in the circuit substrate 10 or enhance the thermal conductivity of the circuit substrate 10.

[0042] The manufacturing method comprises the steps of:

[0043] S1: See Figure 1 A circuit substrate 10 is provided. The circuit substrate 10 includes an outer conductive layer 11 and at least one inner conductive layer 12. The outer conductive layer 11 is disposed on opposite sides of the inner conductive layer 12. An insulating layer 13 is disposed between the outer conductive layer 11 and the inner conductive layer 12, and between two adjacent inner conductive layers 12. The thickness of the circuit substrate 10 is 1 to 5 mm.

[0044] In this embodiment, an inner conductive circuit 121 is formed on the inner conductive layer 12 . The inner conductive circuit 121 is used to electrically connect electronic components (eg, integrated circuits, etc.) to achieve corresponding functions.

[0045] S2: See Figure 2 and Figure 4 A first opening 14 is provided in the circuit substrate 10. The first opening 14 penetrates the outer conductive layer 11, the inner conductive layer 12, and the insulating layer 13. A conductive sheet 15 is provided on the inner wall of the first opening 14. The conductive sheet 15 is electrically connected to the inner conductive layer 12 and electrically isolated from the outer conductive layer 11. In this embodiment, the inner diameter of the first opening 14 is 0.1 to 0.8 mm, and preferably, the inner diameter of the first opening 14 is 0.5 mm.

[0046] In this embodiment, step S2 includes:

[0047] S21: See Figure 3 A first opening 14 is provided in the circuit substrate 10, and a first metal layer 141 is formed by electroplating in the first opening 14. The first metal layer 141 includes a first end 142, a second end 143, and the conductive sheet 15 connected between the first end 142 and the second end 143. The first end 142 extends along the thickness direction of the circuit substrate 10, and the first end 142 corresponds to at least one of the outer conductive layers 11 and the insulating layer 13 located below the outer conductive layer 11. The second end 143 extends along the thickness direction of the circuit substrate 10, and the second end 143 corresponds to at least one of the outer conductive layers 11 and the insulating layer 13 located below the outer conductive layer 11.

[0048] S22: See Figure 4 , the first end portion 142 and the second end portion 143 are removed to disconnect the electrical connection between the conductive sheet 15 and the outer conductive layer 11. In this embodiment, the removal includes milling off the first end portion 142 and the second end portion 143 by mechanical drilling.

[0049] In this embodiment, in step S2 , the conductive sheet 15 is substantially annular, and two opposite outer sides of the conductive sheet 15 along the diameter direction are connected to the inner conductive layer 12 .

[0050] In this embodiment, step S2 further includes:

[0051] S23: See Figure 2 , a second opening 16 is provided on the circuit substrate 10 , wherein the second opening 16 passes through the outer conductive layer 11 , the inner conductive layer 12 and the insulating layer 13 ;

[0052] S24: See Figure 3 , electroplating is performed in the second opening 16 to form a second metal layer 161 , and the second metal layer 161 is electrically connected to the outer conductive layer 11 and the inner conductive layer 12 .

[0053] S3: See Figure 5 and Figure 6 , electroplating is performed on the conductive sheet 15 to form a conducting column 50 , and the conducting column 50 fills the first opening 14 to obtain the circuit board 100 .

[0054] In this embodiment, step S3 includes:

[0055] S31: Disposing a dry film layer 111 on the outer conductive layer 11, wherein the dry film layer 111 is provided with an opening 112, the first opening 14 is exposed at the bottom of the opening 112, and the dry film layer 111 covers the second opening 16;

[0056] S32: Immerse the circuit substrate 10 in a plating solution (not shown), and electrically connect the plating cathode (not shown) to the outer conductive layer 11 near the opening 112, thereby electroplating the second opening 16 to obtain a conductive column 50. Since the outer conductive layer 11 is electrically connected to the second metal layer 161, the second metal layer 161 is electrically connected to the inner conductive layer 12, and the inner conductive layer 12 is electrically connected to the conductive sheet 15, that is, the conductive sheet 15 is electrically connected to the plating cathode. Therefore, during the electroplating process, the electroplating material first begins to deposit at the conductive sheet 15 (that is, as shown in FIG. Figure 5 As shown, the conductive sheet 15 changes from a sheet shape to an arc shape, and then fills the first opening 14 .

[0057] S33: removing the dry film layer 111. It is understood that after removing the dry film layer 111, the end surface of the via 50 extends out of the outer side surface of the outer conductive layer 11 because the via 50 still fills the opening 112 of the dry film layer 111 during the electroplating process.

[0058] In this embodiment, the method for manufacturing the circuit board 100 further includes:

[0059] S4: Grind the conductive pillar 50 so that the end surface of the conductive pillar 50 is flush with the outer side surface of the outer conductive layer 11.

[0060] S5: forming a covering layer (not shown) by electroplating on the outer conductive layer 11 , wherein the covering layer covers the conducting pillar 50 .

[0061] Compared with the prior art, the method for manufacturing a circuit board provided by the present invention has the following advantages:

[0062] (1) By providing a conductive sheet electrically connected to the electroplating cathode, the electroplating deposition starts from the conductive sheet and then fills the first opening, which is beneficial to maintaining the plating force in the hole and reducing the gradual shrinkage of the hole ring of the first opening, thereby reducing the generation of cavitation or burrs.

[0063] (2) The conductive sheet has a larger outer surface (it can be understood that, compared with the conductive sheet and the second metal layer opposite to the conductive sheet, the conductive sheet also has two end surfaces that can be exposed to the electroplating solution), which is conducive to the use of high current density electroplating process and improves electroplating efficiency.

[0064] (3) This method is suitable for mass production. For example, at least five conductive columns can be formed by electroplating at the same time. It is simple to operate and highly efficient.

[0065] The above description is only an optimized specific implementation of the present application, but it is not limited to this implementation in actual application. For ordinary technicians in this field, other variations and changes made according to the technical concept of the present application should fall within the scope of protection of the present application.

Claims

1. A method for manufacturing a circuit board, characterized in that: Including steps: Providing a circuit substrate, the circuit substrate comprising an outer conductive layer and at least one inner conductive layer, the outer conductive layer being disposed on two opposite sides of the inner conductive layer; A first opening is provided on the circuit substrate, wherein the first opening passes through the outer conductive layer and the inner conductive layer; A conductive sheet is disposed in the first opening, wherein the conductive sheet is electrically connected to the inner conductive layer and electrically isolated from the outer conductive layer; as well as Electroplating is performed in the first opening having the conductive sheet, and the conductive sheet is electrically connected to the electroplating cathode, thereby forming a conductive column in the first opening to obtain the circuit board, wherein the step of "arranging the conductive sheet in the first opening" includes: Electroplating in the first opening to form a first metal layer, the first metal layer including a first end, a second end, and a conductive sheet connected between the first end and the second end, the first end and the second end being electrically connected to the outer conductive layer; and The first end portion and the second end portion are removed to disconnect the electrical connection between the conductive sheet and the outer conductive layer.

2. The manufacturing method according to claim 1, wherein The circuit substrate further includes a plurality of insulating layers, wherein the insulating layers are arranged between the outer conductive layer and the inner conductive layer, or between two adjacent inner conductive layers.

3. The manufacturing method according to claim 2, wherein: The first end portion and the second end portion extend along a thickness direction of the circuit substrate, and the first end portion or the second end portion corresponds to the outer conductive layer and at least one of the insulating layers.

4. The manufacturing method according to claim 1, wherein: Also includes the steps: A second opening is provided on the circuit substrate, wherein the second opening passes through the outer conductive layer and the inner conductive layer; Electroplating is performed in the second opening to form a second metal layer, wherein the second metal layer is electrically connected to the outer conductive layer and the inner conductive layer.

5. The manufacturing method according to claim 4, wherein: The step of “performing electroplating in the first opening having the conductive sheet” includes: Disposing a dry film layer on the outer conductive layer, wherein the dry film layer is covered with an opening, wherein the first opening is exposed at the bottom of the opening, and the dry film layer covers the second opening; Immersing the circuit substrate in an electroplating solution and electrically connecting the second metal layer to the electroplating cathode for electroplating; The dry film layer is removed.

6. The manufacturing method according to claim 1, wherein: Also includes: The portion of the conductive pillar extending out from the outer side surface of the outer conductive layer is removed.

7. The manufacturing method according to claim 1, wherein: Also includes the steps: A covering layer is formed on the outer conductive layer by electroplating, and the covering layer covers the conducting column.

8. The manufacturing method according to claim 1, wherein: The inner diameter of the first opening is 0.1-0.8 mm.

9. The manufacturing method according to claim 1, wherein: The thickness of the circuit substrate is 1-5 mm.

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