TW201616936A - Circuit board and method for manufacturing same - Google Patents

Abstract

A circuit board includes a flexible circuit substrate and a shield ground structure forming on the flexible circuit. The flexible circuit substrate includes a dielectric layer and a first wire layer and a second wire layer formed on the opposite sides of the dielectric layer. A conductive through hole is defined in the dielectric layer. The first wire layer is electrically connected to the second wire layer through the conductive through hole. A first insulating layer covers on the first wire layer. A plurality of first openings are defined in the first insulating layer. Portions of the first wire layer are exposed from the first openings defining first grounding pads. The shield ground structure includes a copper layer, a solder mask layer and a gold layer. The copper layer covers the first insulating layer and the first grounding pads and fills the first openings. The solder mask layer covers the copper layer. A plurality of second openings are defined in the solder mask layer. Portions of the copper layer are exposed from the second openings defining second grounding pads. The gold layer covers the second grounding pads.

Description

Circuit board and its manufacturing method

The invention relates to a circuit board and a method of manufacturing the same.

In order to prevent the electromagnetic radiation from being emitted when the circuit board is working and interfere with the normal operation of other electronic components, a mask grounding structure is usually selectively disposed on the circuit board.

At present, the mask grounding structure is disposed on the circuit board by: firstly, cutting a conductive conductive cloth having an anisotropic conductive paste and a ground conductive cloth having metal conductive particles into a desired shape; The masked conductive cloth is first attached to the area on the circuit board where the mask is grounded, and the anisotropic conductive paste is electrically connected to the circuit board; then, the conductive cloth on the mask is first aligned and then Thermally bonding and heat-bonding a layer of the grounding conductive cloth, the metal conductive particles piercing the mask conductive cloth during thermal compression, and electrically connecting with the anisotropic conductive glue to form a mask grounding structure In order to achieve the purpose of the grounding of the mask. Since the grounding conductive cloth is heat-bonded and heat-bonded to the mask conductive cloth, alignment is required, and the machine or manual bonding alignment accuracy is limited, so that the alignment is accurate and a good fit is ensured. Accuracy, the size of the mask conductive cloth and the ground conductive cloth is required, that is, the bonding size of the mask conductive cloth and the ground conductive cloth is limited by the fitting precision. This will result in a limited setting of the mask ground structure. In addition, the ground conductive cloth is electrically connected to the circuit board by the anisotropic conductive adhesive, so that the grounding resistance is large, which affects the mask effect.

In view of the above, it is necessary to provide a circuit board and a circuit board manufacturing method that overcome the above problems.

A method of manufacturing a circuit board, comprising the steps of: providing a flexible circuit board comprising a dielectric layer and a first conductive circuit layer and a second conductive circuit layer formed on opposite sides of the dielectric layer, the first conductive circuit layer The first conductive circuit layer is formed with a first insulating cover layer, and the first insulating cover layer is opened with a first opening to expose a portion of the first conductive line. Forming a first ground pad; forming a copper layer on a surface of the first insulating cover layer, the copper layer completely covering a surface of the first insulating cover layer and a first ground exposed from the first insulating cover layer Forming a surface of the pad and filling the first opening; forming a solder resist layer on the surface of the copper layer, the solder resist layer is provided with a plurality of second openings, exposing a portion of the copper layer to form a second ground pad; The surface of the second ground pad forms a gold layer.

A circuit board includes a flexible circuit board and a mask ground structure formed on a surface of the flexible circuit board. The flexible circuit board includes a dielectric layer and a first conductive circuit layer and a second conductive circuit layer formed on opposite sides of the dielectric layer. The first conductive circuit layer and the second conductive circuit layer are electrically connected to each other through the conductive holes. A surface of the first conductive circuit layer is formed with a first insulating cover layer. The first insulating cover layer is provided with a first opening, and the exposed portion of the first conductive circuit layer forms a first ground pad. The mask ground structure includes a copper layer, a solder resist layer and a gold layer. The copper layer covers the first insulating cover layer and the first ground pad surface, and fills the first opening. The solder resist layer covers the surface of the copper layer. The solder resist layer is formed with a second opening, and a portion of the copper layer is exposed to form a second ground pad. The gold layer covers the surface of the second ground pad.

Compared with the prior art, the circuit board provided by the present invention only needs to ground the second conductive circuit layer and the gold layer to realize the grounding of the mask. Therefore, the circuit board and the circuit board provided by the invention have the following advantages. First, since only a second opening is formed in the solder resist layer, a portion of the copper layer is exposed to form a second ground pad, and a gold layer is formed on the surface of the second ground pad to form a mask ground structure, which is not required in the process. Alignment and press-fit, therefore, the setting of the mask grounding structure is not affected by the fitting precision, and the setting is relatively flexible; the second is that the gold layer is electrically connected to the copper layer by forming a gold layer on the second ground pad With the gold layer directly grounded, it has a lower ground resistance, and the mask effect is less affected by the ground resistance.

1 is a schematic cross-sectional view of a flexible circuit board according to an embodiment of the present invention.

2 is a schematic cross-sectional view of a substrate provided by an embodiment of the present invention.

3 is a schematic cross-sectional view showing the through hole formed in the substrate of FIG. 2.

FIG. 4 is a schematic cross-sectional view showing the via hole plating of FIG. 3 filled with a conductive hole.

FIG. 5 is a cross-sectional view showing the first copper layer and the second copper layer in FIG. 4 formed into a first conductive wiring layer and a second conductive wiring layer.

Fig. 6 is a schematic cross-sectional view showing a layer of a catalytic ink layer formed on the insulating coating layer on the side of the first conductive wiring layer of Fig. 1.

Figure 7 is a schematic cross-sectional view showing the chemical deposition of a copper layer on the side of the catalytic ink layer of Figure 6.

8 is a schematic cross-sectional view showing the formation of a patterned solder mask on the surface of the copper layer of FIG. 7, and a portion of the copper layer is exposed to the solder resist layer to form a second ground pad.

FIG. 9 is a schematic cross-sectional view showing a transition metal layer formed on the surface of the second ground pad in FIG.

Figure 10 is a schematic cross-sectional view showing the formation of a gold layer on the surface of the transition metal layer of Figure 9.

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

The manufacturing method of the circuit board 100 provided by the embodiment of the present invention includes the following steps:

In the first step, referring to FIG. 1, a flexible circuit board 10 is provided.

The flexible circuit board 10 includes a first conductive wiring layer 11, a dielectric layer 12, a second conductive wiring layer 13, a first insulating cover layer 14, and a second insulating cover layer 15. The first conductive circuit layer 11 and the second conductive circuit layer 13 are located on opposite sides of the dielectric layer 12. The dielectric layer 12 is provided with a conductive hole 121 penetrating the dielectric layer 12 . The first conductive circuit layer 11 is electrically connected to the second conductive circuit layer 13 via the conductive holes 121. The first insulating cover layer 14 covers the surface of the first conductive wiring layer 11 and the dielectric layer 12 exposed from the first conductive wiring layer 11. The first insulating cover layer 14 is provided with a plurality of first openings 141, and the exposed portion of the first conductive circuit layer 11 forms a first ground pad 142. The second insulating cover layer 15 covers the surface of the second conductive wiring layer 13.

The flexible circuit board 10 can be obtained by:

First, referring to FIG. 2, a substrate 110 is provided. The substrate 110 can be a single panel or a double panel. In this embodiment, the substrate 110 is a double panel. The substrate 110 includes a first copper layer 111, a dielectric layer 12 and a second copper layer 113. The dielectric layer 12 may be a material having good flexibility such as polyimide or polyester. The first copper layer 111 and the second copper layer 113 are respectively located on opposite sides of the dielectric layer 12 .

Next, referring to FIG. 3, a through hole 1210 penetrating the substrate 110 is formed on the substrate 110. The through hole 1210 can be formed by laser ablation or mechanical drilling.

Next, referring to FIG. 4, the through holes 1210 are filled and formed to form the conductive holes 121. In the present embodiment, the plating material is copper.

Next, referring to FIG. 5, the first copper layer 111 is selectively removed to form the first conductive wiring layer 11 and the second copper layer 113 is selectively removed to form the second conductive wiring layer 13. A portion of the dielectric layer 12 is exposed from between the voids of the first conductive wiring layer 11. A portion of the dielectric layer 12 is exposed between the spaces of the second conductive wiring layer 13 (not shown). In the present embodiment, the first conductive wiring layer 11 and the second conductive wiring layer 13 may be formed by image transfer and etching.

Finally, referring again to FIG. 1, a first insulating cover layer 14 is formed on the first conductive wiring layer 11, and a second insulating cover layer 15 is formed on the surface of the second conductive wiring layer 13. The first insulating cover layer 14 covers the surface of the first conductive circuit layer 11 and the dielectric layer 12 exposed from the first conductive circuit layer 11, and the first insulating cover layer 14 is provided with a plurality of first The opening 141 exposes a portion of the first conductive wiring layer 11 to form a first ground pad 142. The second insulating cover layer 15 covers the entire surface of the second conductive wiring layer 13.

In the second step, referring to FIG. 6, a catalytic ink layer 21 is formed on the surface of the first insulating cover layer 14. In the present embodiment, the catalytic ink layer 21 is formed by printing.

The catalytic ink layer 21 can catalyze the subsequent chemical precipitation of copper and have the effect of increasing the bonding strength between the copper layer and the first insulating coating layer 14. In this embodiment, the thickness of the catalytic ink layer 21 ranges from 2.5 to 17.5 micrometers. The catalytic ink layer 21 covers the surface of the first insulating cover layer 14 away from the dielectric layer 12, and a plurality of sidewalls of the first opening 141, that is, the catalytic ink layer 21 covers the first insulating layer a surface away from the surface of the dielectric layer 12 and the first insulating cover layer 14 exposed from the first opening 141, such that the catalytic ink layer 21 partially fills each of the first openings 141 and A partial region of each of the first ground pads 142 is exposed from the catalytic ink layer 21.

It can be understood that, before forming a layer of the catalytic ink layer 21 on the surface of the first insulating cover layer 14, the step of roughening the first ground pad 142 is further included.

In a third step, referring to FIG. 7, a copper layer 22 is chemically deposited on the surface of the catalytic ink layer 21 and the first ground pad 142 exposed from the catalytic ink layer 21.

The copper layer 22 fills the first opening 141, and the copper layer 22 is located in the same horizontal plane away from the surface of the first conductive circuit layer 11. In this embodiment, the thickness of the copper layer 22 on the surface of the catalytic ink layer 21 ranges from 0.5 to 1.5 micrometers.

In the fourth step, referring to FIG. 8, a solder resist layer 23 is formed on the surface of the copper layer 22.

The solder resist layer 23 is provided with a plurality of second openings 231, and a portion of the copper layer 22 is exposed to form a second ground pad 232. In the present embodiment, the solder resist layer 23 is a photosensitive ink. In the embodiment, the solder resist layer 23 has a thickness ranging from 10 to 30 micrometers.

In the fifth step, referring to FIG. 9, a transition metal layer 24 is formed on the surface of the second ground pad 232. The transition metal layer 24 may be a material such as nickel, nickel palladium or the like. The transition metal layer 24 can be formed by chemical deposition. The thickness of the transition metal layer 24 is smaller than the thickness of the solder resist layer 23. In the embodiment, the transition metal layer 24 has a thickness ranging from 2 to 8 micrometers.

Referring to FIG. 10, a gold layer 25 is formed on the surface of the transition metal layer 24, and the gold layer 25 and the second conductive circuit layer 13 are grounded to realize the flexible circuit board 10. The mask is grounded.

The gold layer 25 can be formed by chemical deposition or electroplating. In this embodiment, the thickness of the gold layer ranges from 0.0075 to 0.025 micrometers.

It can be understood that the gold layer 25 can be formed by electroplating directly on the surface of the second ground pad 232. At this time, the step of forming the transition metal layer 24 between the second ground pad 232 and the gold layer 25 is not required.

Referring to FIG. 10 again, an embodiment of the present invention further provides a circuit board 100 including a flexible circuit board 10 and a mask ground structure 20.

The flexible circuit board 10 includes a first conductive wiring layer 11, a dielectric layer 12, a second conductive wiring layer 13, a first insulating cover layer 14, and a second insulating cover layer 15. The first conductive circuit layer 11 and the second conductive circuit layer 13 are located on opposite sides of the dielectric layer 12. The dielectric layer 12 is provided with a conductive hole 121 penetrating the dielectric layer 12 . The first conductive circuit layer 11 is electrically connected to the second conductive circuit layer 13 via the conductive holes 121. The first insulating cover layer 14 covers the surface of the first conductive wiring layer 11 and the dielectric layer 12 exposed from the first conductive wiring layer 11. The first insulating cover layer 14 is provided with a plurality of first openings 141, and the exposed portion of the first conductive circuit layer 11 forms a first ground pad 142. The second insulating cover layer 15 covers the surface of the second conductive wiring layer 13.

The mask ground structure 20 is formed on the first insulating cover layer 14 of the flexible circuit board 10.

The mask ground structure 20 includes a catalytic ink layer 21, a copper layer 22, a solder resist layer 23, a transition metal layer 24, and a gold layer 25. The catalytic ink layer 21 covers the surface of the first insulating cover layer 14 away from the dielectric layer 12 and the sidewalls of the plurality of first openings 141, that is, the catalytic ink layer 21 covers the first insulating cover The layer 14 is away from the surface of the dielectric layer 12 and the surface of the first insulating cover layer 14 exposed from the first opening 141 such that the catalytic ink layer 21 partially fills each of the first openings 141. A partial region of the first ground pad 142 is exposed from the catalytic ink layer 21. The copper layer 22 covers a portion of the surface of the catalytic ink layer 21 and the first ground pad 142 exposed from the catalytic ink layer 21. The copper layer 22 fills the first opening 141, and the copper layer 22 is located in the same horizontal plane away from the surface of the dielectric layer 12. The solder resist layer 23 covers the copper layer 22. The solder resist layer 23 is provided with a plurality of second openings 231, and a portion of the copper layer 22 is exposed to form a second ground pad 232. The transition metal layer 24 covers the second ground pad 232. The gold layer 25 covers the transition metal layer 24. In this embodiment, the thickness of the catalytic ink layer 21 ranges from 2.5 to 17.5 micrometers. The copper layer 22 has a thickness ranging from 0.5 to 1.5 microns. The solder resist layer 23 has a thickness ranging from 10 to 30 micrometers. The thickness of the transition metal layer 24 is smaller than the thickness of the solder resist layer 23. In this embodiment, the transition metal layer 24 has a thickness ranging from 2 to 8 micrometers. The thickness of the gold layer ranges from 0.0075 to 0.025 microns.

Compared with the prior art, the circuit board provided by the present invention only needs to ground the second conductive circuit layer and the gold layer to achieve the grounding of the mask. Therefore, the circuit board and the circuit board provided by the present invention have the manufacturing method. The advantages are as follows: firstly, only a second opening is opened in the solder resist layer, a part of the copper layer is exposed to form a second ground pad, and a gold layer is formed on the surface of the second ground pad to form a mask ground structure, in the process There is no need for alignment and pressing. Therefore, the setting of the mask grounding structure is not affected by the fitting accuracy, and the setting is relatively flexible. Second, the gold layer and the copper layer are formed on the second grounding pad. The electrical connection is directly grounded by the gold layer and has a low grounding resistance value. The shielding effect is less affected by the grounding resistance value; in addition, the gold layer has a better anti-oxidation function.

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 is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application in this case. 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

10‧‧‧Soft circuit board

11‧‧‧First conductive circuit layer

12‧‧‧Dielectric layer

13‧‧‧Second conductive circuit layer

14‧‧‧First insulating cover

15‧‧‧Second insulation cover

121‧‧‧Electrical hole

141‧‧‧ first opening

142‧‧‧First grounding pad

110‧‧‧Substrate

111‧‧‧First copper layer

113‧‧‧Second copper layer

1210‧‧‧through hole

20‧‧‧Mask grounding structure

21‧‧‧ Catalytic ink layer

22‧‧‧ copper layer

23‧‧‧ solder mask

231‧‧‧ second opening

232‧‧‧Second grounding pad

24‧‧‧Transition metal layer

25‧‧‧ gold layer

no

100‧‧‧ boards

10‧‧‧Soft circuit board

11‧‧‧First conductive circuit layer

12‧‧‧Dielectric layer

13‧‧‧Second conductive circuit layer

14‧‧‧First insulating cover

15‧‧‧Second insulation cover

141‧‧‧ first opening

142‧‧‧First grounding pad

20‧‧‧Mask grounding structure

21‧‧‧ Catalytic ink layer

22‧‧‧ copper layer

23‧‧‧ solder mask

231‧‧‧ second opening

232‧‧‧Second grounding pad

24‧‧‧Transition metal layer

25‧‧‧ gold layer

Claims (9)

A method of manufacturing a circuit board, comprising the steps of:
Providing a flexible circuit board comprising a dielectric layer and a first conductive circuit layer and a second conductive circuit layer formed on opposite sides of the dielectric layer, wherein the first conductive circuit layer and the second conductive circuit layer are The first conductive layer is formed with a first insulating cover layer, the first insulating cover layer is provided with a first opening, and the exposed portion of the first conductive circuit layer forms a first ground pad;
Forming a copper layer on a surface of the first insulating cover layer, the copper layer completely covering a surface of the first insulating cover layer and a first ground pad surface exposed from the first insulating cover layer and filling the surface First opening;
Forming a solder resist layer on a surface of the copper layer, the solder resist layer is provided with a plurality of second openings, exposing a portion of the copper layer to form a second ground pad; and forming a gold layer on a surface of the second ground pad. The method of manufacturing the circuit board of claim 1, wherein the flexible circuit board is obtained by:
Providing a substrate, the substrate includes a first copper layer, a dielectric layer and a second copper layer, wherein the first copper layer and the second copper layer are respectively located on opposite sides of the dielectric layer;
Forming a through hole penetrating the substrate;
Electroplating fills the through holes to form conductive holes;
Selectively removing a portion of the first copper layer to form a first conductive circuit layer, and selectively removing a portion of the second copper layer to form a second conductive line;
Forming a first insulating cover layer on a surface of the first conductive circuit layer and a surface of the dielectric layer exposed from the first conductive circuit layer, wherein the first insulating cover layer is provided with a plurality of first openings to expose a portion of the first conductive The circuit layer forms a first ground pad. The method of fabricating a circuit board according to claim 1, wherein before forming a copper layer on the surface of the first insulating cover layer, further comprising forming a catalytic ink layer on the surface of the first insulating cover layer, the catalysis An ink layer covering a surface of the first insulating cover layer away from the dielectric layer and a surface of the first insulating cover layer exposed from the first opening, the first ground pad portion being exposed from the catalytic ink layer . The method of fabricating a circuit board according to claim 3, further comprising the step of roughening the surface of the first ground pad before forming a layer of the catalytic ink on the surface of the first insulating cover layer. The method of manufacturing a circuit board according to claim 1, wherein the second layer is further included in the second layer after the solder resist layer is formed on the surface of the copper layer and before the gold layer is chemically deposited on the surface of the second ground pad A layer of transition metal is deposited on the surface of the ground pad. A circuit board comprising a flexible circuit board and a mask ground structure formed on a surface of the flexible circuit board, the flexible circuit board comprising a dielectric layer and a first conductive circuit layer formed on opposite sides of the dielectric layer And a second conductive circuit layer, the first conductive circuit layer and the second conductive circuit layer are electrically connected to each other by a conductive hole, and a surface of the first conductive circuit layer is formed with a first insulating cover layer, An insulating cover layer is provided with a first opening, and a portion of the first conductive circuit layer is formed to form a first ground pad. The mask ground structure comprises a copper layer, a solder resist layer and a gold layer, and the copper layer covers the first insulation Covering layer and first ground pad surface, and filling the first opening, the solder resist layer covers the surface of the copper layer, the solder resist layer is formed with a second opening, and a portion of the copper layer is exposed to form a second ground pad The gold layer covers the surface of the second ground pad. The circuit board of claim 6, wherein the flexible circuit board further comprises a second insulating cover layer, the second insulating cover layer covering the surface of the second conductive circuit layer. The circuit board of claim 6, wherein the mask ground structure further comprises a catalytic ink layer, the catalytic ink layer being located between the copper layer and the first insulating cover layer, the catalytic ink layer Covering a surface of the first insulating cover layer away from the dielectric layer and a surface of the first insulating cover layer exposed from the first opening, the first ground pad portion being exposed from the catalytic ink layer. The circuit board of claim 6, wherein the mask ground structure further comprises a transition metal layer between the gold layer and the second ground pad.