TWI538572B - Circuit board and method for manufacturing same - Google Patents

Description

Circuit board and manufacturing method thereof

The invention relates to a circuit board manufacturing technology, in particular to a circuit board and a manufacturing method thereof.

Due to the thin and light requirements of the flexible circuit board, when the internal circuit is used as the signal line for external signal transmission, it is usually required to cover the outer layer of the flexible circuit board with an EMI shielding film to prevent signal loss caused by external electromagnetic interference.

The conductive silver foil is usually a four-layer structure, that is, a protective film, a metal film, a conductive paste, and a release film in this order. Before the bonding, the release film needs to be removed to bond the conductive paste and the flexible circuit board to each other. In the obtained product, in order to enable the metal film to be tightly combined with the flexible circuit board, it is necessary to first heat-bond the conductive silver foil to the circuit board, thereby increasing the time for manufacturing the circuit board. Moreover, the conductive silver foil is relatively fragile, and it is easy to be scrapped during the bonding process, thereby increasing the manufacturing cost of the circuit board. Further, the price of the conductive silver foil is relatively expensive, resulting in a high production cost of the circuit board.

Therefore, it is necessary to provide a circuit board and a method of fabricating the same that can achieve electromagnetic shielding of signal lines without using conductive silver foil.

A circuit board comprising a circuit board, a conductive polymer film layer and a copper plating mask layer which are sequentially disposed. The circuit substrate includes a conductive circuit layer and a third insulating layer. Said The conductive circuit layer and the conductive polymer film layer are formed on opposite sides of the third insulating layer. The conductive circuit layer includes a signal line and a ground line. The copper plating mask layer is formed on the surface of the conductive polymer film layer by electroplating. A second conductive hole is formed in the third insulating layer. The grounding line is electrically connected to the copper-plated mask layer through the second conductive hole. The circuit substrate further includes a second insulating layer and a ground conductive layer. The ground conductive layer is formed between the second insulating layer and the third insulating layer. A first conductive hole is formed in the second insulating layer. The ground conductive layer and the ground line are in electrical communication with each other through the first conductive hole.

A method of manufacturing a circuit board, comprising the steps of: providing a circuit substrate, wherein the circuit substrate comprises a conductive circuit layer and a third insulating layer, wherein the conductive circuit layer comprises a signal line and a ground line, and the third insulating layer is Forming a plurality of openings, the ground line is exposed from the opening; forming a conductive polymer film layer on a surface of the third insulating layer and an inner sidewall of the opening; and the conductive polymer film The surface of the layer and the surface of the grounding line exposed from the opening are formed by electroplating to form a copper-plated mask layer and a second conductive hole, and the grounding line is electrically connected to the copper-plated mask layer through the second conductive hole. The circuit substrate further includes a second insulating layer and a ground conductive layer. The ground conductive layer is formed between the second insulating layer and the third insulating layer. A first conductive hole is formed in the second insulating layer. The ground conductive layer and the ground line are in electrical communication with each other through the first conductive hole.

The circuit board and the manufacturing method thereof provided by the technical solution form a conductive polymer layer by forming a conductive polymer layer on the surface of the insulating layer, and then forming a ground conductive layer by electroplating. The grounding conductive layer can act as an electromagnetic shielding on the signal line, thereby preventing external electromagnetic interference generated on the signal line. Compared with the prior art, the conductive conductive silver foil is used to form the electromagnetic shielding layer, which can effectively shorten the process of circuit board fabrication. Low board manufacturing costs and improved board yield.

110‧‧‧ circuit board

101‧‧‧Electromagnetic mask area

102‧‧‧General area

111‧‧‧First insulation

112‧‧‧Grounding conductive layer

113‧‧‧Second insulation

1131‧‧‧first conductive hole

114‧‧‧ Conductive circuit layer

1141‧‧‧Signal line

1142‧‧‧ Grounding circuit

115‧‧‧ third insulation

Opening 1151‧‧

1152‧‧‧Second conductive hole

120‧‧‧ Conductive polymer film

130‧‧‧copper-coated mask

140‧‧‧ solder mask

100‧‧‧ boards

1 is a top plan view of a circuit substrate provided by an embodiment of the present technical solution.

Figure 2 is a schematic cross-sectional view taken along line II-II of Figure 1.

3 is a schematic cross-sectional view showing a conductive polymer film layer formed on the circuit board of FIG. 2.

4 is a schematic cross-sectional view showing the surface of the conductive polymer film layer of FIG. 3 as a copper plating mask layer.

FIG. 5 is a schematic cross-sectional view showing a circuit board obtained by forming a solder resist layer on the surface of the copper-plated mask layer of FIG. 4. FIG.

The circuit board provided by the technical solution and the manufacturing method thereof will be further described in detail below with reference to the accompanying drawings and embodiments.

The manufacturing method of the circuit board provided by the embodiment of the technical solution includes the following steps:

In the first step, please refer to FIG. 1 and FIG. 2 together to provide a circuit substrate 110.

In the present embodiment, the circuit substrate 110 is a circuit board on which a conductive line is formed. The circuit substrate 110 includes a first insulating layer 111, a ground conductive layer 112, a second insulating layer 113, a conductive wiring layer 114, and a third insulating layer 115 which are sequentially disposed.

The circuit substrate 110 has an electromagnetic mask forming region 101 and a common region 102 other than the electromagnetic mask forming region 101 for forming an electromagnetic mask structure.

In the electromagnetic shielding area 101, the conductive circuit layer 114 includes a signal line 1141 and a ground line 1142. The ground line 1142 surrounds the signal line 1141. The first A first conductive via 1131 is formed in the second insulating layer 113. The ground line 1142 is electrically connected to the ground conductive layer 112 through the first conductive via 1131. A plurality of openings 1151 are formed in the third insulating layer 115 such that the ground line 1142 located around the signal line 1141 is exposed from the opening 1151.

In this step, the conductive circuit layer 114 and the first conductive via 1131 can be formed by using the prior art conductive lines and conductive holes. The opening 1151 can be formed by laser ablation.

In the process of forming the opening 1151, a portion of the material of the original opening portion remains in the opening 1151, or is adsorbed to the inner wall of the opening 1151 to form a slag. After forming the opening 1151, the method further includes performing desmear treatment on the circuit substrate 110. That is, the circuit substrate 110 is processed by plasma so that the slag in the opening 1151 is removed.

In the second step, referring to FIG. 3, the conductive polymer film layer 120 is formed on the surface of the third insulating layer 115 and the inner sidewall of the opening 1151 in the electromagnetic mask region 101.

The conductive polymer film layer 120 can be formed by first immersing the surface of the third insulating layer 115 and the inner sidewall of the opening 1151 in the manganese dioxide solution, so that the third insulating layer 115 The surface and the inner side wall of the opening 1151 are adsorbed with manganese dioxide. It can be understood that before the surface of the third insulating layer 115 and the inner sidewall of the opening 1151 are immersed in the manganese dioxide solution, the surface of the third insulating layer 115 and the opening 1151 may be further included. The treatment such as cleaning causes the surface of the third insulating layer 115 and the opening 1151 to be cleaned.

Then, the circuit board 110 is immersed in the conductive polymer monomer to form a conductive polymer film on the surface of the third insulating layer 115 and the inner side wall of the opening 1151. Layer 120.

When the circuit substrate 110 is immersed in the conductive polymer monomer, the manganese dioxide is used as a catalyst to polymerize the conductive polymer monomer, thereby forming a conductive layer on the surface of the third insulating layer 115 and the inner sidewall of the opening 1151. Polymer film layer 120. The conductive polymer monomer is a monomer having conductivity in a polymer formed after polymerization. The conductive polymer monomer may specifically be aniline, pyrrole or thiophene, or may be a derivative of aniline, a pyrrole derivative or a thiophene derivative, such as 3,4-dioxyethylenethiophene, 2,5- Dimethoxyaniline and the like. The conductive polymer monomer is usually a liquid. Preference is given to 3,4-dioxyethylenethiophene.

The conductive polymer film layer 120 may be polyaniline, polypyrrole or polythiophene. Or a derivative of an aniline derivative, a pyrrole derivative or a thiophene derivative. Such as poly 3,4-ethylenedioxythiophene or poly 2,5-dimethoxyaniline.

Since the conductive polymer film layer 120 is formed on the surface of the third insulating layer 115 and the inner sidewall of the opening 1151 and is an organic material, the bonding force between the surface of the third insulating layer 115 and the inner sidewall of the opening 1151 is higher. Large, but not formed on the surface of the ground line 1142 exposed by the opening 1151.

The conductive polymer film layer 120 has electrical conductivity and has a conductivity of about 5 kilohms per inch. The conductive polymer film layer 120 has a thickness of 100 nm to 500 nm.

In the third step, referring to FIG. 4, the surface of the conductive polymer film layer 120 corresponding to the electromagnetic shielding region 101 is plated with metal to form a copper-plated mask layer 130, and at the same time, a metal is plated in the opening 1151 to form a second conductive layer. The hole 1152 is electrically connected to the copper plating mask layer 130 through the second conductive hole 1152.

Soaking the circuit substrate 110 in a soluble metal salt solution for electroplating, The conductive polymer obtained after the polymerization has the property of being converted in an oxidation/reduction state, and during the oxidation/reduction state conversion of the conductive polymer, free electrons can be released, so that the metal ions in the soluble metal salt solution can be made The metal element is reduced to a simple metal, and a metal layer is formed on the surface of the conductive polymer film layer 120. In the present embodiment, a copper sulfate solution will be described as an example. After the circuit board 110 is immersed in a copper sulfate solution, copper is reduced on the surface of the conductive polymer film layer 120.

The conductive polymer film layer 120 has electrical conductivity, and reduction of the metal formed on the conductive polymer film layer 120 can increase the conductivity of the conductive polymer film layer 120. Therefore, the conductive polymer film layer 120 can be quickly formed inside the opening 1151 and the conductive polymer. The film layer 120 forms a plated metal layer, and the material of the plated metal layer may be copper, thereby obtaining a copper plated mask layer 130 and a second conductive hole 1152. The copper-plated mask layer 130 has a thickness of 5 micrometers to 15 micrometers.

In the fourth step, referring to FIG. 5, a solder resist layer 140 is formed on the surface of the copper plating mask layer 130 and the second conductive via 1152 to obtain the circuit board 100.

The solder resist layer 140 can be formed by printing ink. The solder resist layer 140 has a thickness of 2 micrometers to 10 micrometers.

Referring to FIG. 5 , the technical solution further provides a circuit board 100 formed by the above method. The circuit board 100 includes a circuit board 110 , a conductive polymer film layer 120 , a copper plating mask layer 130 , and an anti-static layer . Solder layer 140.

The circuit substrate 110 includes a first insulating layer 111, a ground conductive layer 112, a second insulating layer 113, a first conductive wiring layer 114, and a third insulating layer 115 which are sequentially disposed. The first conductive circuit layer 114 includes a signal line 1141 and a ground line 1142. The ground line 1142 surrounds the signal line 1141. Forming a first guide in the second insulating layer 113 Electrical hole 1131. The ground line 1142 is electrically connected to the ground conductive layer 112 through the first conductive via 1131. A second conductive via 1152 is formed in the third insulating layer 115.

The circuit substrate 110 includes an electromagnetic mask region 101 and a common region 102 other than the electromagnetic mask region 101. The conductive polymer film layer 120, the copper plating mask layer 130, and the solder resist layer 140 are all formed in the electromagnetic mask region 101. The copper-plated mask layer 130 is electrically connected to the ground line 1142 via the second conductive via 1152.

The conductive polymer film layer 120 may be polyaniline, polypyrrole or polythiophene. Or a derivative of an aniline derivative, a pyrrole derivative or a thiophene derivative. Such as poly 3,4-ethylenedioxythiophene or poly 2,5-dimethoxyaniline. The conductive polymer film layer 120 is formed on the surface of the third insulating layer 115 and in the second conductive hole 1152.

The conductive metal and the copper-plated mask layer 130 in the second conductive via 1152 are simultaneously formed by plating metal.

The conductive polymer film layer 120 has a thickness of 100 nm to 500 nm. The copper-plated mask layer 130 has a thickness of 5 micrometers to 15 micrometers. The solder resist layer 140 has a thickness of 2 micrometers to 10 micrometers.

The ground conductive layer 112 and the copper plating mask layer 130 may be a sheet conductor, and the signal line 1141 is located between the ground conductive layer 112 and the copper plating mask layer 130. The areas of the grounding conductive layer 112 and the copper-plated mask layer 130 are both larger than the area where the signal line 1141 is distributed, and are electrically connected to the ground line 1142 so as to function as an electromagnetic mask for the signal line 1141. It can be understood that the circuit board 100 may also include the grounding conductive layer 112 as needed, and only the copper plating mask layer 130 is formed on one side of the signal line 1141.

The circuit board provided by the technical solution and the manufacturing method thereof, the surface shape of the insulating layer A conductive polymer layer is formed, and then a ground conductive layer is formed by electroplating. The grounding conductive layer can act as an electromagnetic shielding on the signal line, thereby preventing external electromagnetic interference generated on the signal line. Compared with the prior art, the use of the laminated conductive silver foil to form the electromagnetic mask layer can effectively shorten the process of circuit board fabrication, reduce the manufacturing cost of the circuit board, and improve the yield of the circuit board.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by persons skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.

111‧‧‧First insulation

112‧‧‧Grounding conductive layer

113‧‧‧Second insulation

1131‧‧‧first conductive hole

114‧‧‧ Conductive circuit layer

1141‧‧‧Signal line

1142‧‧‧ Grounding circuit

115‧‧‧ third insulation

1152‧‧‧Second conductive hole

120‧‧‧ Conductive polymer film

130‧‧‧copper-coated mask

140‧‧‧ solder mask

100‧‧‧ boards

Claims (6)

A circuit board comprising a circuit substrate, a conductive polymer film layer and a copper plating mask layer which are sequentially disposed, the circuit substrate comprising a conductive circuit layer and a third insulating layer, the conductive circuit layer and the conductive polymer film The layer is formed on opposite sides of the third insulating layer, the conductive circuit layer includes a signal line and a ground line, and the copper-plated mask layer is formed on the surface of the conductive polymer film layer by electroplating, and the third insulating layer is Forming a second conductive hole, the ground line is electrically connected to the copper-plated mask layer through the second conductive hole, the circuit substrate further includes a second insulating layer and a ground conductive layer, wherein the ground conductive layer is formed on the first Between the second insulating layer and the third insulating layer, a first conductive hole is formed in the second insulating layer, and the ground conductive layer and the ground line are electrically connected to each other through the first conductive hole. The circuit board according to claim 1, wherein the conductive polymer film layer has a thickness of 100 nm to 500 nm, and the copper plating mask layer has a thickness of 5 μm to 15 μm. The circuit board of claim 1, further comprising a solder resist layer formed on a surface of the copper plating mask layer, the solder resist layer having a thickness of 2 micrometers to 10 micrometers. A method of manufacturing a circuit board, comprising the steps of: providing a circuit substrate, wherein the circuit substrate comprises a conductive circuit layer and a third insulating layer, wherein the conductive circuit layer comprises a signal line and a ground line, and the third insulating layer is Forming a plurality of openings, the ground line is exposed from the opening, the circuit substrate further includes a second insulating layer and a ground conductive layer, wherein the ground conductive layer is formed on the second insulating layer and the third insulating layer a first conductive hole is formed in the second insulating layer, and the ground conductive layer and the ground line are electrically connected to each other through the first conductive hole; the surface of the third insulating layer and the inner sidewall of the opening Forming a conductive polymer film layer; and passing electricity on a surface of the conductive polymer film layer and a surface of the ground line exposed from the opening The plating method forms a copper plating mask layer and a second conductive hole, and the ground line is electrically connected to the copper plating mask layer through the second conductive hole. The method for fabricating a circuit board according to claim 4, wherein the forming the conductive polymer film layer comprises the steps of: immersing the surface of the third insulating layer and the inner sidewall of the opening in manganese dioxide In the solution, the surface of the third insulating layer and the inner sidewall of the opening are adsorbed with manganese dioxide; and the circuit substrate is immersed in the conductive polymer monomer so as to be in the surface of the third insulating layer and in the opening A conductive polymer film layer is formed on the sidewall. The method for producing a circuit board according to claim 5, wherein the conductive polymer monomer is 3,4-dioxyethylenethiophene.