TWI459880B - Circuit board and method for manufactuing same - Google Patents

Description

Circuit board and manufacturing method thereof

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

As a soft printed circuit board (hereinafter referred to as FPC), which is an indispensable component of consumer electronics, a flexible copper-clad substrate (FCCL) including single-sided copper foil or double-sided copper foil is commonly used, through image transfer process and etching process. The conductive circuit is fabricated, and then the cover film or the solder resist ink is printed to protect the conductive line, and finally the surface of the conductive film (such as the electrical contact pad) which is not covered by the cover film or the ink is surface-treated.

In the above FPC products, the insulating layer between the conductive lines is usually polyimine (PI), and the dielectric constant Dk value is between 3.4 and 4.0, and the insulating layer of the cover film as the protective layer is also PI, and the glue thereof The layer is usually an ordinary acrylic or epoxy thermoset. At present, the signal transmission speed of consumer electronic products is increasing. In the process of high-frequency transmission of signals, due to the large Dk value of the above-mentioned insulation layer and cover film, the integrity of the signal caused by FPC products cannot be guaranteed. A new FPC is needed to ensure the integrity of the signal transmission of high frequency, high speed electronics.

In view of the above, there is provided a circuit board and a method thereof, which can make an insulating layer in a circuit board have a small dielectric constant, so that the circuit board can be used for high frequency electricity. Sub-products are necessary.

A circuit board comprising a first conductive circuit layer, a dielectric layer and a second conductive circuit layer, the first conductive circuit layer and the second conductive circuit layer being formed on opposite surfaces of the dielectric layer, the dielectric The layer includes a layer of insulating substrate and at least one layer of Teflon material. Conductive through holes and conductive blind holes are formed in the circuit board. The conductive via extends through the first conductive wiring layer, the dielectric layer, and the second conductive wiring layer. The conductive blind via penetrates through the first conductive wiring layer and the dielectric layer. The first cover layer is press-bonded on one side of the first conductive circuit layer, and the first cover layer includes a first insulating material layer and a first adhesive layer. The first adhesive layer is in contact with the first conductive circuit layer. A second cover layer is press-bonded on one side of the second conductive circuit layer, and the second cover layer includes a second insulating material layer and a second adhesive layer. The second adhesive layer is in contact with the second conductive circuit layer. The conductive via and the conductive via are filled by the first adhesive layer and the second adhesive layer. The material of the first adhesive layer and the second adhesive layer is a fluorine-containing acrylic resin or a fluorine-containing epoxy resin.

A method of manufacturing a circuit board, comprising the steps of: providing a copper clad substrate, the copper clad substrate comprising a dielectric layer, a first copper foil layer and a second copper foil layer, the first copper foil layer and the second copper foil layer Forming on opposite surfaces of the dielectric layer, the dielectric layer includes an insulating substrate layer and at least one layer of Teflon material; and forming the first copper foil to form a first conductive circuit layer, and The second copper foil is formed to form a second conductive circuit layer to obtain a circuit board. Conductive through holes and conductive blind holes are formed in the copper clad substrate. The conductive via extends through the first conductive wiring layer, the dielectric layer, and the second conductive wiring layer. The conductive blind via penetrates through the first conductive wiring layer and the dielectric layer. The first cover layer is press-bonded on one side of the first conductive circuit layer, and the first cover layer includes a first insulating material layer and a first adhesive layer. The first adhesive layer is in contact with the first conductive circuit layer. In the second conductive circuit layer The second cover layer is press-fitted on one side, and the second cover layer includes a second insulating material layer and a second adhesive layer. The second adhesive layer is in contact with the second conductive circuit layer. The conductive via and the conductive via are filled by the first adhesive layer and the second adhesive layer. The material of the first adhesive layer and the second adhesive layer is a fluorine-containing acrylic resin or a fluorine-containing epoxy resin.

The circuit board and the circuit board manufacturing method provided by the technical solution, since the dielectric layer adopts a stack of an insulating substrate layer and at least one layer of Teflon material, it is now only used as an dielectric layer in the prior art. The layer can reduce the dielectric constant of the dielectric layer, thereby enabling the circuit board to be applied to high frequency electronic products. The manufacturing method of the circuit board and the circuit board is also applied to the production of the rigid-flex board and the rigid-flex board.

100‧‧‧ boards

101‧‧‧ conductive through holes

102‧‧‧ Conductive blind holes

110‧‧‧Copper substrate

112‧‧‧ dielectric layer

1121‧‧‧Insulating substrate layer

1122‧‧‧Teflon material layer

111‧‧‧First copper foil layer

113‧‧‧Second copper foil layer

114‧‧‧through hole

115‧‧‧Blind holes

116‧‧‧ Conductive metal layer

117‧‧‧Anti-electroplating film

120‧‧‧First conductive circuit layer

130‧‧‧Second conductive circuit layer

140‧‧‧First cover

142‧‧‧First bonding layer

141‧‧‧First insulating material layer

150‧‧‧second cover

152‧‧‧Second adhesive layer

151‧‧‧Second layer of insulating material

FIG. 1 is a cross-sectional view of a copper clad substrate provided by an embodiment of the present technical solution.

2 is a cross-sectional view showing a through hole and a blind hole in the copper clad substrate of FIG. 1.

3 to FIG. 5 are schematic cross-sectional views showing the formation of conductive vias in the via holes of FIG. 2 and the formation of the via holes to form conductive vias.

6 is a schematic cross-sectional view showing a first copper foil layer in a copper-clad substrate formed into a first conductive wiring layer, and a second copper foil layer formed into a second conductive wiring layer.

FIG. 7 is a schematic cross-sectional view of a circuit board provided by the technical solution.

The circuit board manufacturing method provided by the technical solution includes the following steps: First, referring to FIG. 1, a copper clad substrate 110 is provided.

In this embodiment, the copper clad substrate 110 is a double-sided copper clad substrate including a first copper foil layer. 111, dielectric layer 112 and second copper foil layer 113. The first copper foil layer 111 is on one surface of the dielectric layer, and the second copper foil layer 113 is on the other opposite surface of the dielectric layer 112. The copper clad substrate 110 is a Flexible Copper Clad Laminate (FCCL). That is, the dielectric layer 112 is made of a flexible material.

The dielectric layer 112 includes an insulating substrate layer 1121 and at least one layer of Teflon material 1122. The material of the insulating base material layer 1121 is a material used in the art for producing a flexible circuit board insulating layer such as polyimide. The specific material of the Teflon material layer may be a polytetrafluoroethylene resin. In this embodiment, the dielectric layer 112 includes two layers of Teflon material 1122 and an insulating substrate layer 1121. The insulating substrate layer 1121 is disposed between the two layers of Teflon material layers 1122. The dielectric layer 112 has a dielectric constant between 2.3 and 2.5.

In the second step, referring to FIG. 2, at least one through hole 114 and at least one blind hole 115 are formed in the copper clad substrate 110.

In this step, the through holes 114 may be formed by laser ablation. The through hole 114 penetrates through the first copper foil layer 111, the dielectric layer 112, and the second copper foil layer 113. The through hole 114 can also be formed by mechanical drilling. The number of the through holes 114 may be one or plural. In FIG. 2, a through hole 114 is formed as an example for description.

The blind holes 115 can be formed by laser ablation. The blind via 115 penetrates only the first copper foil layer 111 and the dielectric layer 112. The second copper foil layer 113 is exposed from the bottom of the blind via 115 near the surface of the dielectric layer 112.

In the third step, referring to FIG. 3 to FIG. 5, a conductive metal layer 116 is formed on the inner wall of the through hole 114 and the inner wall of the blind hole 115, thereby obtaining the conductive via 101 and the conductive via hole 102.

The step specifically includes: first, a table of the first copper foil layer 111 and the second copper foil layer 113 The surface of the anti-plating film 117 is formed such that the blind via 115 and a portion of the first copper foil layer 111 surrounding the blind via 115 are exposed, the via 114 and a portion of the first copper foil layer 111 and the second copper foil layer 113 surrounding the via 114. Being exposed. Then, the inner wall of the through hole 114, the inner wall of the blind hole 115, and the portions of the first copper foil layer 111 and the second copper foil layer 113 exposed from the plating resist 117 are formed by electroless plating. Conductive metal layer 116. Finally, the surfaces of the first copper foil layer 111 and the second copper foil layer 113 are removed to form an anti-plating film 117.

In the fourth step, referring to FIG. 6, a portion of the first copper foil layer 111 is selectively removed to form a first conductive wiring layer 120, and a portion of the second copper foil layer 113 is selectively removed to form a second conductive wiring layer 130.

In this step, the first copper foil layer 111 is formed into a first conductive wiring layer 120 by using an image transfer process and a chemical etching process, and the second copper foil layer 113 is formed into a second conductive wiring layer 130.

In the fifth step, referring to FIG. 7, the first cover layer 140 is pressed on the side of the first conductive circuit layer 120, and the second cover layer 150 is pressed on the side of the second conductive line layer 130, thereby obtaining the circuit board 100.

In this step, the first cover layer 140 includes a first insulating material layer 141 and a first adhesive layer 142. The second cover layer 150 includes a second insulating material layer 151 and a second adhesive layer 152. The material of the first insulating material layer 141 and the second insulating material layer 151 may be a material commonly used as a cover film in the art, such as polyimide or the like. The material of the first adhesive layer 142 and the second adhesive layer 152 is a fluorine-containing acrylic resin or a fluorine-containing epoxy resin. Since the first adhesive layer 142 and the second adhesive layer 152 are made of a fluorine-containing material, the dielectric constants of the first cover layer 140 and the second cover layer 150 can be lowered. In this embodiment, the first cover layer 140 and the second cover layer 150 are interposed. The electrical constant is 2.6 to 2.9.

During the nip process, the first adhesive layer 142 and the second adhesive layer 152 are also filled inside the conductive via 101 and the conductive via 102, so that the inside of the circuit board 100 does not have gas.

It can be understood that a plurality of first openings may be formed in the first cover layer 140 such that the electrical contact pads of the first conductive circuit layer 120 are exposed from the corresponding first openings, such that the first conductive circuit layer 120 The electrical contact pads can be connected to other electronic components. A plurality of second openings may also be formed in the second cover layer 150 such that the electrical contact pads of the second conductive circuit layer 130 are exposed from the corresponding second openings, so that the electrical contact pads of the second conductive circuit layer 130 can be combined with other The electronic components are connected.

It can be understood that the circuit board manufacturing method provided by the technical solution can also be applied to the fabrication of the rigid-flex board.

The technical solution also provides a circuit board 100 including a dielectric layer 112, a first conductive circuit layer 120, a second conductive circuit layer 130, a first cover layer 140, and a second cover layer 150. The circuit board 100 can be a flexible circuit board.

The dielectric layer 112 includes at least one insulating substrate layer 1121 and a layer of Teflon material 1122. The material of the insulating base material layer 1121 is a material used in the art for producing a flexible circuit board insulating layer such as polyimide. The specific material of the Teflon material layer may be a polytetrafluoroethylene resin. In this embodiment, the dielectric layer 112 includes two layers of Teflon material 1122 and an insulating substrate layer 1121. The insulating substrate layer 1121 is disposed between the two layers of Teflon material layers 1122. The dielectric layer 112 has a dielectric constant between 2.3 and 2.5.

The first conductive wiring layer 120 and the second conductive wiring layer 130 are formed on opposite surfaces of the dielectric layer 112. In the circuit board 100, a conductive via 101 and a conductive via 102 are also formed. The conductive vias 101 extend through the first conductive wiring layer 120 , the dielectric layer 112 , and the second conductive wiring layer 130 to electrically conduct the first conductive wiring layer 120 and the second conductive wiring layer 130 . The conductive via hole 102 penetrates only the first conductive wiring layer 120 and the dielectric layer 112 to electrically conduct the first conductive wiring layer 120 and the second conductive wiring layer 130.

The first cover layer 140 includes a first insulating material layer 141 and a first adhesive layer 142. The second cover layer 150 includes a second insulating material layer 151 and a second adhesive layer 152. The material of the first insulating material layer 141 and the second insulating material layer 151 may be a material commonly used as a cover film in the art, such as polyimide or the like. The material of the first adhesive layer 142 and the second adhesive layer 152 is a fluorine-containing acrylic resin or a fluorine-containing epoxy resin. Since the first adhesive layer 142 and the second adhesive layer 152 are made of a fluorine-containing material, the dielectric constants of the first cover layer 140 and the second cover layer 150 can be lowered. In this embodiment, the first cap layer 140 and the second cap layer 150 have a dielectric constant of 2.6 to 2.9. The first adhesive layer 142 of the first cover layer 140 is bonded to the first conductive circuit layer 120, and the second adhesive layer 152 of the second cover layer 150 and the second conductive circuit layer 130 are bonded to each other. The first adhesive layer 142 and the second adhesive layer 152 are also filled inside the conductive via 101 and the conductive via 102.

The circuit board and the circuit board manufacturing method provided by the technical solution, since the dielectric layer adopts a stack of an insulating substrate layer and at least one layer of Teflon material, it is now only used as an dielectric layer in the prior art. The layer can reduce the dielectric constant of the dielectric layer, thereby enabling the circuit board to be applied to high frequency electronic products. Further, the adhesive layer in the cover layer is made of a fluorine-containing adhesive material, and the dielectric constant of the cover layer can also be reduced, thereby further improving the signal integrity of the circuit board when transmitting high-frequency signals. Sex.

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.

100‧‧‧ boards

101‧‧‧ conductive through holes

102‧‧‧ Conductive blind holes

1121‧‧‧Insulating substrate layer

1122‧‧‧Teflon material layer

120‧‧‧First conductive circuit layer

130‧‧‧Second conductive circuit layer

140‧‧‧First cover

142‧‧‧First bonding layer

141‧‧‧First insulating material layer

150‧‧‧second cover

152‧‧‧Second adhesive layer

151‧‧‧Second layer of insulating material

Claims (12)

A method of manufacturing a circuit board, comprising the steps of: providing a copper clad substrate, the copper clad substrate comprising a dielectric layer, a first copper foil layer and a second copper foil layer, the first copper foil layer and the second copper foil layer Forming on opposite surfaces of the dielectric layer, the dielectric layer includes an insulating substrate layer and at least one layer of Teflon material; and forming the first copper foil layer to form a first conductive circuit layer, and Forming a second conductive circuit layer to form a second conductive circuit layer, to obtain a circuit board, wherein the copper-clad substrate is formed with a conductive via and a conductive via hole, the conductive via penetrating through the first conductive circuit layer, the dielectric layer and the first a conductive layer, the conductive via hole penetrating through the first conductive circuit layer and the dielectric layer, and pressing a first cover layer on a side of the first conductive circuit layer, the first cover layer comprising a first insulating material layer and a first An adhesive layer, the first adhesive layer is in contact with the first conductive circuit layer, and the second cover layer is pressed on one side of the second conductive circuit layer, the second cover layer includes a second insulating material layer and a second adhesive layer, the second adhesive layer is in contact with the second conductive circuit layer The conductive via and the conductive via are filled by the first adhesive layer and the second adhesive layer, and the first adhesive layer and the second adhesive layer are made of fluorine-containing acrylic. Resin or fluorine-containing epoxy resin. The method of fabricating a circuit board according to claim 1, wherein the dielectric layer has a dielectric constant greater than 2.3 and less than 2.5. The method of manufacturing the circuit board of claim 1, wherein the first cover layer and the second cover layer each have a dielectric constant greater than 2.6 and less than 2.9. The method of fabricating a circuit board according to claim 1, wherein the conductive via electrically conducts the first conductive wiring layer and the second conductive wiring layer. The method of fabricating a circuit board according to claim 1, wherein the conductive via hole electrically conducts the first conductive circuit layer and the second conductive circuit layer. The method of manufacturing a circuit board according to claim 1, wherein the copper clad substrate is a flexible copper clad substrate. A circuit board comprising a first conductive circuit layer, a dielectric layer and a second conductive circuit layer, the first conductive circuit layer and the second conductive circuit layer being formed on opposite surfaces of the dielectric layer, the dielectric The layer comprises a layer of insulating substrate and at least one layer of Teflon material, wherein the circuit board defines a conductive via and a conductive via, the conductive via extending through the first conductive layer, the dielectric layer and the second conductive line a layer, the conductive via hole penetrating through the first conductive circuit layer and the dielectric layer, and pressing a first cover layer on a side of the first conductive circuit layer, the first cover layer comprising a first insulating material layer and a first bonding layer a layer, the first adhesive layer is in contact with the first conductive circuit layer, and the second cover layer is pressed on one side of the second conductive circuit layer, the second cover layer includes a second insulating material layer and a second adhesive layer The second adhesive layer is in contact with the second conductive circuit layer, and the conductive via and the conductive via are filled by the first adhesive layer and the second adhesive layer, The material of the adhesive layer and the second adhesive layer is fluorine-containing acrylic resin or fluorine-containing Epoxy resin. The circuit board of claim 7, wherein the dielectric layer has a dielectric constant greater than 2.3 and less than 2.5. The circuit board of claim 7, wherein the first cover layer and the second cover layer each have a dielectric constant greater than 2.6 and less than 2.9. The circuit board of claim 7, wherein the conductive via electrically conducts the first conductive wiring layer and the second conductive wiring layer. The circuit board of claim 7, wherein the conductive via hole electrically conducts the first conductive wiring layer and the second conductive wiring layer. The circuit board of claim 7, wherein the circuit board is a flexible circuit board.