TWI769781B - Manufacturing method of circuit board - Google Patents

Abstract

The application proposes a method for manufacturing a circuit board, which includes the following steps: providing a circuit board, the circuit board includes an outer conductive layer and at least one inner conductive layer, the outer conductive layer is arranged on opposite sides of the inner conductive layer, a first opening is arranged on the circuit board, the first opening passes through the outer conductive layer and the inner conductive layer, and a conductive sheet is arranged in the first opening, and the conductive sheet is connected with the inner conductive layer The conductive layer is electrically conductive, the conductive sheet is electrically isolated from the outer conductive layer, and electroplating is carried out in the first opening with the conductive sheet, and the conductive sheet is electrically connected with the electroplating cathode, so as to form a conducting column in the first opening to obtain the circuit board.

Description

Manufacturing method of circuit board

The present application relates to a method of manufacturing a circuit board.

The traditional through-hole electroplating process for circuit boards requires first drilling the circuit board, then metallizing the peripheral walls of the holes, and finally performing electroplating to fill the holes to form copper pillars. However, in order to improve the efficiency of electroplating hole filling, electroplating needs to be carried out at a high current density, which leads to the dog-bone effect in the process of electroplating hole filling. When the plating time is continuously increased, the throwing force in the hole will decrease. And the situation that the hole ring is gradually reduced, it is easy to generate cavities or burrs, which affect the thermal conductivity or electrical conductivity of the subsequent copper pillars.

In view of this, the present application provides a method for manufacturing a circuit board to reduce the generation of voids or burrs in the conduction column.

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 layers are disposed on opposite sides of the inner conductive layer. A first opening is provided on the circuit substrate, and the first opening penetrates the outer conductive layer and the inner conductive layer. A conductive sheet is arranged in the first opening, the conductive sheet is electrically connected to the inner conductive layer, and the conductive sheet is electrically isolated from the outer conductive layer. and performing electroplating in the first opening with the conductive sheet, and electrically connecting the conductive sheet with the electroplating cathode, so as to form a conductive column in the first opening to obtain the circuit board.

Further, the step of "arranging a conductive sheet in the first opening" includes: electroplating in the first opening to form a first metal layer, and the first metal layer includes a first end and a second end A portion and a conductive sheet connected between the first end portion and the second end portion, the first end portion and the second end portion are electrically connected to the outer conductive layer. and removing the first end portion and the second end portion to disconnect the electrical connection between the conductive sheet and the outer conductive layer.

Further, the circuit substrate further includes a plurality of insulating layers, the insulating layers are arranged between the outer conductive layer and the inner conductive layer, or the insulating layer is arranged between two adjacent inner conductive layers .

Further, the first end portion and the second end portion extend along the 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 the insulating layer.

Further, the method further includes the step of: disposing a second opening on the circuit substrate, and the second opening penetrates the outer conductive layer and the inner conductive layer. Electroplating is performed in the second opening to form a second metal layer, and the second metal layer is electrically connected to the outer conductive layer and the inner conductive layer.

Further, the step "electroplating in the first opening with the conductive sheet" includes:

A dry film layer is disposed on the outer conductive layer, an opening is covered on the dry film layer, the first opening is exposed at the bottom of the opening, and the dry film layer covers the second opening. The circuit substrate is immersed in an electroplating solution, the second metal layer is electrically connected to the electroplating cathode for electroplating, and the dry film layer is removed.

Further, the method further includes: removing the portion of the conductive post extending from the outer side surface of the outer conductive layer.

Further, the method further includes the step of: forming a cover layer by electroplating on the outer conductive layer, and the cover layer covers the conduction column.

Further, the inner diameter of the first opening is 0.1-0.8 mm.

Further, the thickness of the circuit substrate is 1-5 mm.

In the manufacturing method provided by the present application, by arranging 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 maintain the uniform plating force in the hole and reduce the loss of the first opening. The hole ring is gradually reduced, thereby reducing the generation of cavitation or burr.

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments.

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 intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. When an element is referred to as being "disposed on" another element, it can be directly disposed on the other element or intervening elements may also be present.

Referring to FIGS. 1 to 6 , the present invention provides a method for manufacturing a circuit board 100 to form conductive pillars 50 in the circuit substrate 10 , and the conductive pillars 50 are used to electrically conduct conductive layers or enhance circuits in the circuit substrate 10 . Thermal conductivity of the substrate 10 .

The manufacturing method includes the steps:

S1: Referring to FIG. 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, and the outer conductive layer 11 is disposed on the opposite sides of the inner conductive layer 12, An insulating layer 13 is provided 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 1-5 mm.

In this embodiment, inner conductive lines 121 are formed on the inner conductive layer 12 , and the inner conductive lines 121 are used to electrically connect electronic components (eg, integrated circuits, etc.) to achieve corresponding functions.

S2: Please refer to FIG. 2 and FIG. 4 , the circuit substrate 10 is provided with a first opening 14 , and the first opening 14 penetrates the outer conductive layer 11 , the inner conductive layer 12 and the insulating layer 13 Then, a conductive sheet 15 is disposed on the inner sidewall of the first opening 14 , the conductive sheet 15 is electrically connected to the inner conductive layer 12 , and the conductive sheet 15 is electrically isolated from the outer conductive layer 11 . In this embodiment, the inner diameter of the first opening 14 is 0.1-0.8 mm, and preferably, the inner diameter of the first opening 14 is 0.5 mm.

In this embodiment, step S2 includes:

S21 : Referring to FIG. 3 , a first opening 14 is provided in the circuit substrate 10 , and electroplating is performed in the first opening 14 to form a first metal layer 141 . The first metal layer 141 includes a first end portion 142 , a second end portion 143 , and the conductive sheet 15 connected between the first end portion 142 and the second end portion 143 . The first end portion 142 extends along the thickness direction of the circuit substrate 10 , and the first end portion 142 corresponds to at least one of the outer conductive layers 11 and one of the insulating layers below the outer conductive layer 11 . 13. The second end portion 143 extends along the thickness direction of the circuit substrate 10 , and the second end portion 143 corresponds to at least one of the outer conductive layers 11 and one of the outer conductive layers 11 under the outer conductive layer 11 . insulating layer 13 .

S22 : Referring to FIG. 4 , remove the first end portion 142 and the second end portion 143 to disconnect the electrical connection between the conductive sheet 15 and the outer conductive layer 11 . In this embodiment, the removing includes milling away the first end portion 142 and the second end portion 143 by means of mechanical drilling.

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

In the present embodiment, step S2 also comprises:

S23: Referring to FIG. 2, a second opening 16 is provided in the circuit substrate 10, and the second opening 16 penetrates the outer conductive layer 11, the inner conductive layer 12 and the insulating layer 13;

S24 : Referring to FIG. 3 , electroplating is performed in the second opening 16 to form a second metal layer 161 , and the second metal layer 161 electrically conducts the outer conductive layer 11 and the inner conductive layer 12 .

S3: Referring to FIG. 5 and FIG. 6 , electroplating is performed on the conductive sheet 15 to form conductive pillars 50 , and the conductive pillars 50 fill the first openings 14 to obtain the circuit board 100 .

In this embodiment, step S3 includes:

S31: a dry film layer 111 is provided on the outer conductive layer 11, 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 the second opening 16;

S32: Immerse the circuit substrate 10 in an electroplating solution (not shown), and electrically connect the electroplating cathode (not shown) to the outer conductive layer 11 near the opening 112, so that in the second opening Holes 16 are electroplated to obtain vias 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 electroplating cathode. Therefore, during the electroplating process, the electroplating material first begins to deposit at the conductive sheet 15 (ie, as shown in FIG. 5 , the conductive sheet 15 changes from a sheet shape to an arc shape), and then fills the first opening 14 .

S33: The dry film layer 111 is removed. It can be understood that when the dry film layer 111 is removed, the openings 112 of the dry film layer 111 are also filled with the conductive pillars 50 during the electroplating process, so the end surfaces of the conductive pillars 50 protrude from the outer surface of the outer conductive layer 11 .

In this embodiment, the manufacturing method of the circuit board 100 further includes:

S4 : smoothing the conduction column 50 , and the end surface of the conduction column 50 is flush with the outer surface of the outer conductive layer 11 .

S5: Electroplating on the outer conductive layer 11 to form a cover layer (not shown), and the cover layer covers the conduction column 50 .

Compared with the prior art, the manufacturing method of the circuit board provided by the present invention has the following advantages:

(1) By setting the conductive sheet electrically connected to the electroplating cathode, the electroplating deposition starts from the conductive sheet, and then fills the first opening, which is conducive to maintaining the uniform plating force in the hole and reducing the gradual increase of the hole ring of the first opening. Reduce the situation of shrinkage, thereby reducing the generation of cavitation or burr.

(2) The conductive sheet has a larger outer surface (it can be understood that comparing the conductive sheet and the second metal layer opposite to the conductive sheet, the conductive sheet also has two end faces that can be exposed to the electroplating solution), which is conducive to the use of high current Density electroplating process to improve electroplating efficiency.

(3) The method is suitable for mass production, for example, at least five conduction columns can be formed by electroplating at the same time, the operation is simple, and the efficiency is high.

The above description is only an optimized specific implementation manner of the present application, but it cannot be limited only to this implementation manner in the actual application process. For those of ordinary skill in the art, other modifications and changes made according to the technical concept of the present application should all belong to the scope of the patent of the present application.

100: circuit board 10: circuit substrate 11: Outer conductive layer 111: dry film layer 112: Opening 12: inner conductive layer 13: Insulation layer 14: The first opening 141: first metal layer 142: First End 143: Second End 15: Conductive sheet 16: The second opening 161: Second metal layer 50: Conduction column

FIG. 1 is a schematic diagram of a circuit substrate provided by an embodiment of the present application.

FIG. 2 is a schematic diagram of the substrate shown in FIG. 1 after the first opening is provided.

FIG. 3 is a schematic diagram of disposing a first metal layer in the first opening shown in FIG. 2 .

FIG. 4 is a schematic view after removing part of the first metal layer of FIG. 3 to leave a conductive sheet.

FIG. 5 is a schematic diagram of electroplating on the conductive sheet shown in FIG. 4 .

FIG. 6 is a schematic diagram of a circuit board provided by an embodiment of the present application.

11: Outer conductive layer

12: inner conductive layer

13: Insulation layer

16: The second opening

161: Second metal layer

50: Conduction column

100: circuit board

Claims (10)

A method for manufacturing a circuit board, comprising the steps of: A circuit substrate is provided, the circuit substrate includes an outer conductive layer and at least one inner conductive layer, the outer conductive layers are disposed on opposite sides of the inner conductive layer; A first opening is provided on the circuit substrate, and the first opening penetrates the outer conductive layer and the inner conductive layer; A conductive sheet is arranged in the first opening, the conductive sheet is electrically connected to the inner conductive layer, and the conductive sheet is electrically isolated from the outer conductive layer; and Electroplating is performed in the first opening with the conductive sheet, and the conductive sheet is electrically connected to the electroplating cathode, so as to form a conductive column in the first opening to obtain the circuit board. The manufacturing method according to claim 1, wherein the step of "arranging a conductive sheet in the first opening" comprises: Electroplating in the first opening to form a first metal layer, the first metal layer includes a first end portion, a second end portion and is connected between the first end portion and the second end portion the conductive sheet, the first end and the second end are 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. The manufacturing method according to claim 2, wherein the circuit substrate further comprises a plurality of insulating layers, the insulating layers are arranged between the outer conductive layer and the inner conductive layer, or the insulating layers are arranged adjacent to each other between the two inner conductive layers. The manufacturing method according to claim 3, wherein the first end portion and the second end portion extend in the thickness direction of the circuit board, and the first end portion or the second end portion corresponds to the outer conductive layer and at least one of the insulating layers. The manufacturing method as claimed in claim 1, further comprising the steps of: A second opening is arranged on the circuit substrate, and the second opening penetrates the outer conductive layer and the inner conductive layer; Electroplating is performed in the second opening to form a second metal layer, and the second metal layer is electrically connected to the outer conductive layer and the inner conductive layer. The manufacturing method according to claim 5, wherein the step of "electroplating in the first opening having the conductive sheet" comprises: A dry film layer is arranged on the outer conductive layer, the dry film layer is covered with an opening, 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. The manufacturing method of claim 1, further comprising: A portion of the conductive post extending from the outer side surface of the outer conductive layer is removed. The manufacturing method as claimed in claim 1, further comprising the steps of: A capping layer is formed by electroplating on the outer conductive layer, and the capping layer covers the conduction column. The manufacturing method according to claim 1, wherein the inner diameter of the first opening is 0.1-0.8 mm. The manufacturing method according to claim 1, wherein the circuit substrate has a thickness of 1 to 5 mm.

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