MANUFACTURING METHOD FOR FLEXIBLE PRINTED CIRCUIT BOARD

Abstract

The invention provides a manufacturing method for flexible printed circuit board, by liquefying the flexible insulating material and the metal material, coating the liquefied materials and solidifying the coated layers to form respectively the flexible insulating layer and the anti-EMI layer of the anti-EMI structure. As such, an adhesive layer is eliminated to achieve reducing the thickness of the flexible insulating layer and the anti-EMI layer and the material consumption, resulting in reduced production cost, reduced thickness of the flexible printed circuit board with anti-EMI structure, and improved quality.

Claims

1. A manufacturing method for flexible printed circuit board, which comprises: Step 1: providing a flexible substrate, and forming a printed circuit on at least a side of the flexible substrate; Step 2: coating a liquefied flexible insulating material over the printed circuit, and solidifying the liquefied flexible insulating material to form a flexible insulating layer of the printed circuit; controlling the thickness of the flexible insulating layer to be less than 10 um through coating; Step 3: coating a liquefied metal material over the flexible insulating layer, and solidifying the liquefied metal material to form an anti-electromagnetic interference (anti-EMI) layer; controlling the thickness of the anti-EMI layer to be less than 18 um through coating.

2. The manufacturing method for flexible printed circuit board as claimed in claim 1, wherein in Step 1, a printed circuit is formed respectively on both sides of the flexible substrate, and each printed circuit comprises a conductive layer; in Step 2, a flexible insulating layer is formed respectively on the conductive layer of each printed circuit; and in Step 3, an anti-EMI layer is formed respectively on each flexible insulating layer.

3. The manufacturing method for flexible printed circuit board as claimed in claim 1, wherein in Step 1, a printed circuit is formed respectively on both sides of the flexible substrate, and each printed circuit comprises a stack of conductive layers, with an insulating protective layer disposed between two adjacent conductive layers, an adhesive layer is disposed on a side of each insulating protective layer close to the flexible substrate; in Step 2, a flexible insulating layer is formed respectively on the conductive layer of each printed circuit farthest from the flexible substrate; and in Step 3, an anti-EMI layer is formed respectively on each flexible insulating layer.

4. The manufacturing method for flexible printed circuit board as claimed in claim 1, wherein in Step 1, a printed circuit is formed on a side of the flexible substrate, and the printed circuit comprises a conductive layer; in Step 2, a flexible insulating layer is formed on the conductive layer of the printed circuit; and in Step 3, an anti-EMI layer is formed on the flexible insulating layer.

5. The manufacturing method for flexible printed circuit board as claimed in claim 1, wherein in Step 1, a printed circuit is formed on a side of the flexible substrate, and the printed circuit comprises a stack of conductive layers, with an insulating protective layer disposed between two adjacent conductive layers, an adhesive layer is disposed on a side of each insulating protective layer close to the flexible substrate; in Step 2, a flexible insulating layer is formed on the conductive layer of the printed circuit farthest from the flexible substrate; and in Step 3, an anti-EMI layer is formed on the flexible insulating layer.

6. The manufacturing method for flexible printed circuit board as claimed in claim 1, wherein in Step 2, the liquefied flexible insulating material is liquid polyimide (PI), or liquid polyethylene terephthalate (PET).

7. The manufacturing method for flexible printed circuit board as claimed in claim 1, wherein in Step 3, the liquefied metal material is liquid aluminum, or liquid silver.

8. The manufacturing method for flexible printed circuit board as claimed in claim 1, wherein in Step 2, the thickness of the flexible insulating layer is 4 um-6 um.

9. The manufacturing method for flexible printed circuit board as claimed in claim 1, wherein in Step 3, the thickness of the anti-EMI layer is 8 um-12 um.

10. The manufacturing method for flexible printed circuit board as claimed in claim 1, wherein in Step 2, a scratch process is used to coat a layer of the liquefied flexible insulating material; and in Step 3, a scratch process is used to coat a layer of the liquefied metal material.

11. A manufacturing method for flexible printed circuit board, which comprises: Step 1: providing a flexible substrate, and forming a printed circuit on at least a side of the flexible substrate; Step 2: coating a liquefied flexible insulating material over the printed circuit, and solidifying the liquefied flexible insulating material to form a flexible insulating layer of the printed circuit; controlling the thickness of the flexible insulating layer to be less than 10 um through coating; Step 3: coating a liquefied metal material over the flexible insulating layer, and solidifying the liquefied metal material to form an anti-electromagnetic interference (anti-EMI) layer; controlling the thickness of the anti-EMI layer to be less than 18 um through coating; wherein in Step 2, the liquefied flexible insulating material being liquid polyimide (PI), or liquid polyethylene terephthalate (PET); wherein in Step 3, the liquefied metal material being liquid aluminum, or liquid silver; wherein in Step 2, the thickness of the flexible insulating layer being 4 um-6 um; wherein in Step 3, the thickness of the anti-EMI layer being 8 um-12 um.

12. The manufacturing method for flexible printed circuit board as claimed in claim 11, wherein in Step 1, a printed circuit is formed respectively on both sides of the flexible substrate, and each printed circuit comprises a conductive layer; in Step 2, a flexible insulating layer is formed respectively on the conductive layer of each printed circuit; and in Step 3, an anti-EMI layer is formed respectively on each flexible insulating layer.

13. The manufacturing method for flexible printed circuit board as claimed in claim 11, wherein in Step 1, a printed circuit is formed respectively on both sides of the flexible substrate, and each printed circuit comprises a stack of conductive layers, with an insulating protective layer disposed between two adjacent conductive layers, an adhesive layer is disposed on a side of each insulating protective layer close to the flexible substrate; in Step 2, a flexible insulating layer is formed respectively on the conductive layer of each printed circuit farthest from the flexible substrate; and in Step 3, an anti-EMI layer is formed respectively on each flexible insulating layer.

14. The manufacturing method for flexible printed circuit board as claimed in claim 11, wherein in Step 1, a printed circuit is formed on a side of the flexible substrate, and the printed circuit comprises a conductive layer; in Step 2, a flexible insulating layer is formed on the conductive layer of the printed circuit; and in Step 3, an anti-EMI layer is formed on the flexible insulating layer.

15. The manufacturing method for flexible printed circuit board as claimed in claim 11, wherein in Step 1, a printed circuit is formed on a side of the flexible substrate, and the printed circuit comprises a stack of conductive layers, with an insulating protective layer disposed between two adjacent conductive layers, an adhesive layer is disposed on a side of each insulating protective layer close to the flexible substrate; in Step 2, a flexible insulating layer is formed on the conductive layer of the printed circuit farthest from the flexible substrate; and in Step 3, an anti-EMI layer is formed on the flexible insulating layer.

16. The manufacturing method for flexible printed circuit board as claimed in claim 11, wherein in Step 2, a scratch process is used to coat a layer of the liquefied flexible insulating material; and in Step 3, a scratch process is used to coat a layer of the liquefied metal material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] To make the technical solution of the embodiments according to the present invention, a brief description of the drawings that are necessary for the illustration of the embodiments will be given as follows. Apparently, the drawings described below show only example embodiments of the present invention and for those having ordinary skills in the art, other drawings may be easily obtained from these drawings without paying any creative effort. In the drawings:

[0020] FIG. 1 is a schematic view showing the structure of a known electronic product with LCD;

[0021] FIG. 2 is a schematic view showing the structure of a known flexible printed circuit board with anti-EMI structure;

[0022] FIG. 3 is a schematic view showing the manufacturing method for flexible printed circuit board provided by a first embodiment of the present invention;

[0023] FIG. 4 is a schematic view showing the manufacturing method for flexible printed circuit board provided by a second embodiment of the present invention;

[0024] FIG. 5 is a schematic view showing the manufacturing method for flexible printed circuit board provided by a third embodiment of the present invention;

[0025] FIG. 6 is a schematic view showing the manufacturing method for flexible printed circuit board provided by a fourth embodiment of the present invention; and

[0026] FIG. 7 is a schematic view showing the flowchart of the manufacturing method for flexible printed circuit board provided by an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] To further explain the technical means and effect of the present invention, the following refers to embodiments and drawings for detailed description.

[0028] Refer to FIG. 7. The present invention provides a manufacturing method for flexible printed circuit board, which comprises: Step 1: providing a flexible substrate 101, and forming a printed circuit on at least a side of the flexible substrate 101.

[0029] Step 2: coating a liquefied flexible insulating material over the printed circuit, and solidifying the liquefied flexible insulating material to form a flexible insulating layer 103 of the printed circuit; controlling the thickness of the flexible insulating layer to be less than 10 um through coating.

[0030] Preferably, the liquefied flexible insulating material is a liquid polyimide (PI), or liquid polyethylene terephthalate (PET). Specifically, in Step 2, by using a coating knife in coating the liquefied flexible insulating material, the thickness of the liquefied flexible insulating material and the thickness of the formed flexible insulating layer 103 can be better controlled. Specifically, the process comprises: stirring the liquefied flexible insulating material, extracting the flexible substrate 101 with formed printed circuit from the roll of flexible circuit board, using scratch coating to coat a layer of liquefied flexible insulating material on the printed circuit, drying and solidifying the coated liquefied flexible insulating material on the flexible substrate 101 to form the flexible insulating layer 103, and then rewinding the flexible substrate 101 with formed flexible insulating layer 103 into a roll for transferring to the next step for subsequent processing. In other words, the roll-to-roll manner is used in manufacturing.

[0031] Moreover, the flexible insulating layer 103 is usually thicker than 1 um. Preferably, the thickness of the flexible insulating layer 103 is 4 um-6 um.

[0032] Step 3: coating a liquefied metal material over the flexible insulating layer 103, and solidifying the liquefied metal material to form an anti-electromagnetic interference (anti-EMI) layer 104; controlling the thickness of the anti-EMI layer 104 to be less than 18 um through coating.

[0033] Preferably, the liquefied metal material is a liquid aluminum (Al), or liquid silver (Ag). Specifically, in Step 3, by using a coating knife in coating the liquefied metal material, the thickness of the liquefied metal material and the thickness of the formed anti-EMI layer 104 can be better controlled. Specifically, the process comprises: stirring the liquefied metal material, extracting the flexible substrate 101 with formed flexible insulating layer 103 from the roll of flexible circuit board from Step 2, using scratch coating to coat a layer of liquefied metal material on the flexible insulating layer 103, drying and solidifying the coated liquefied metal material on the flexible substrate 101 to form the anti-EMI layer 104, and then rewinding the flexible substrate 101 with formed anti-EMI layer 104 into a roll. Moreover, the anti-EMI layer 104 is usually thicker than 2 um. Preferably, the thickness of the anti-EMI layer 104 is 8 um-12 um.

[0034] Specifically, the manufacturing method for flexible printed circuit board is applicable to the manufacturing of double-sided single-layered flexible printed circuit board, double-sided multi-layered flexible printed circuit board, single-sided single-layered flexible printed circuit board, and single-sided multi-layered flexible printed circuit board.

[0035] Specifically, refer to FIG. 3. In the first embodiment of the present invention, the flexible printed circuit board is a double-sided single-layered flexible printed circuit board. In other words, a printed circuit is formed respectively on both sides of the flexible substrate 101, and each printed circuit comprises a conductive layer 1021. Correspondingly, in Step 2, a flexible insulating layer 103 is formed respectively on the conductive layer 1021 of each printed circuit; and in Step 3, an anti-EMI layer 104 is formed respectively on each flexible insulating layer 103. Preferably, the conductive layer 1021 is made of copper or gold, specifically, copper foil or gold foil so as to make the conductive layer 1021 flexible.

[0036] Specifically, refer to FIG. 4. In the second embodiment of the present invention, the flexible printed circuit board is a double-sided multi-layered flexible printed circuit board. In other words, a printed circuit is formed respectively on both sides of the flexible substrate 101, and each printed circuit comprises a stack of conductive layers 1021, with an insulating protective layer 1022 disposed between two adjacent conductive layers 1021, an adhesive layer 1023 is disposed on a side of each insulating protective layer 1022 close to the flexible substrate 101. Correspondingly, in Step 2, a flexible insulating layer 103 is formed respectively on the conductive layer 1021 of each printed circuit farthest from the flexible substrate 101; and in Step 3, an anti-EMI layer 104 is formed respectively on each flexible insulating layer 103. Preferably, the conductive layer 1021 is made of copper or gold, specifically, copper foil or gold foil so as to make the conductive layer 1021 flexible. The insulating protective layer 1022 is preferably made of PI.

[0037] Specifically, refer to FIG. 5. In the third embodiment of the present invention, the flexible printed circuit board is a single-sided single-layered flexible printed circuit board. In other words, a printed circuit is formed on a side of the flexible substrate 101, and the printed circuit comprises only a conductive layer 1021. Correspondingly, in Step 2, a flexible insulating layer 103 is formed on the conductive layer 1021 of the printed circuit; and in Step 3, an anti-EMI layer 104 is formed on the flexible insulating layer 103. Preferably, the conductive layer 1021 is made of copper or gold, specifically, copper foil or gold foil so as to make the conductive layer 1021 flexible.

[0038] Specifically, refer to FIG. 6. In the fourth embodiment of the present invention, the flexible printed circuit board is a single-sided multi-layered flexible printed circuit board. In other words, a printed circuit is formed on a side of the flexible substrate 101, and the printed circuit comprises a stack of conductive layers 1021, with an insulating protective layer 1022 disposed between two adjacent conductive layers 1021, an adhesive layer 1023 is disposed on a side of each insulating protective layer 1022 close to the flexible substrate 101. Correspondingly, in Step 2, a flexible insulating layer 103 is formed on the conductive layer 1021 of each printed circuit farthest from the flexible substrate 101; and in Step 3, an anti-EMI layer 104 is formed on the flexible insulating layer 103. Preferably, the conductive layer 1021 is made of copper or gold, specifically, copper foil or gold foil so as to make the conductive layer 1021 flexible. The insulating protective layer 1022 is preferably made of PI.

[0039] In summary, the present invention provides a manufacturing method for flexible printed circuit board, by liquefying the flexible insulating material and the metal material, coating the liquefied materials and solidifying the coated layers to form respectively the flexible insulating layer and the anti-EMI layer of the anti-EMI structure. As such, an adhesive layer is eliminated to achieve reducing the thickness of the flexible insulating layer and the anti-EMI layer and the material consumption, resulting in reduced production cost, reduced thickness of the flexible printed circuit board with anti-EMI structure, and improved quality.

[0040] It should be noted that in the present disclosure the terms, such as, first, second are only for distinguishing an entity or operation from another entity or operation, and does not imply any specific relation or order between the entities or operations. Also, the terms comprises, include, and other similar variations, do not exclude the inclusion of other non-listed elements. Without further restrictions, the expression comprises a . . . does not exclude other identical elements from presence besides the listed elements.

[0041] Embodiments of the present invention have been described, but not intending to impose any unduly constraint to the appended claims. Any modification of equivalent structure or equivalent process made according to the disclosure and drawings of the present invention, or any application thereof, directly or indirectly, to other related fields of technique, is considered encompassed in the scope of protection defined by the claims of the present invention.