CN109788661B - Flexible circuit board and preparation method thereof - Google Patents
Flexible circuit board and preparation method thereof Download PDFInfo
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- CN109788661B CN109788661B CN201711106075.8A CN201711106075A CN109788661B CN 109788661 B CN109788661 B CN 109788661B CN 201711106075 A CN201711106075 A CN 201711106075A CN 109788661 B CN109788661 B CN 109788661B
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Abstract
The utility model provides a flexible circuit board, includes a basic unit and is formed at two conductive circuit layers on the relative two surfaces of basic unit, its characterized in that, each conductive circuit layer includes a circuit wiring, and each circuit wiring includes an at least predetermined circuit, the basic unit is being formed with the trompil locating in at least one side of each predetermined circuit, is formed with a conduction portion in each trompil, conduction portion is used for two conductive circuit layers of electric connection, conduction portion does not form the hole ring, and the surface on each conductive circuit layer has covered an insulating layer and a solder mask in proper order.
Description
Technical Field
The invention relates to a flexible circuit board and a preparation method thereof.
Background
For the manufacturing process of the double-sided circuit board, through holes are formed based on laser drilling/mechanical drilling, and then through holes are obtained through a copper plating process to realize the electrical conduction of the double-sided circuit board. The conventional flexible circuit board technology has been well developed, however, there is still a need to provide a new flexible circuit board and a method for manufacturing the same, which can provide users with more diversified choices.
Disclosure of Invention
A method for manufacturing a flexible circuit board includes: providing a copper-clad substrate which comprises an insulating base layer and two copper foil layers formed on two opposite surfaces of the base layer; etching each copper foil layer to form circuit wiring, wherein each circuit wiring comprises at least one preset circuit; covering a photosensitive layer on the surface of each circuit wiring; etching each photosensitive layer to form a pattern opening in each photosensitive layer, wherein the pattern opening exposes the predetermined circuit and at least one side part of each predetermined circuit, so as to define a region to be conducted on at least one side of each predetermined circuit; removing the region to be conducted to form an opening; copper is plated on the surface of the preset circuit to form two conductive circuit layers on two opposite surfaces of the base layer, and copper is plated in the opening to form a conducting part, the conducting part is used for electrically connecting the two conductive circuit layers, and a hole ring is not formed in the conducting part; removing each photosensitive layer; and sequentially covering an insulating layer and a solder mask layer on the surface of each conductive circuit layer, thereby manufacturing the flexible circuit board.
The utility model provides a flexible circuit board, includes a basic unit and is formed at two conductive circuit layers on the relative two surfaces of basic unit, each conductive circuit layer includes a circuit wiring, and each circuit wiring includes an at least predetermined circuit, the basic unit is being located at least one side of each predetermined circuit and is being formed with the trompil, is formed with a conduction portion in each trompil, conduction portion is used for two conductive circuit layers of electric connection, conduction portion does not form the hole ring, and the surface on each conductive circuit layer has covered an insulating layer and a solder mask in proper order.
In the flexible circuit board and the preparation method thereof, the original copper is firstly adopted to manufacture the circuit wiring on the two surfaces of the base layer, then the opening is formed on at least one side of the base layer, which is positioned on the preset circuit, through the exposure and development process or the laser forming method, and the copper is plated in the opening to form the conduction part for connecting the two conductive circuit layers, so that the conduction is realized.
Drawings
Fig. 1 is a cross-sectional view of a copper-clad substrate according to a first embodiment of the present invention.
Fig. 2 is a cross-sectional view after etching the copper foil layer of the copper-clad substrate shown in fig. 1 to form a circuit wiring.
Fig. 3 is a cross-sectional view of the circuit wiring shown in fig. 2 covered with a photosensitive layer.
Fig. 4 is a cross-sectional view of the photosensitive layer shown in fig. 3 after exposure treatment.
Fig. 5 is a cross-sectional view of the photosensitive layer shown in fig. 4 after development treatment.
Fig. 6 is a cross-sectional view of the base layer shown in fig. 5 after exposure treatment.
Fig. 7 is a cross-sectional view of the base layer shown in fig. 6 after development processing to form openings.
Fig. 8 is a cross-sectional view after forming a conductive layer on the inner wall of the opening shown in fig. 7.
Fig. 9 is a cross-sectional view of the opening shown in fig. 8 with a conductive portion formed therein and the photosensitive layer removed.
Fig. 10 is a plan view of the opening shown in fig. 9 with the conductive portion formed therein and the photosensitive layer removed.
Fig. 11 is a sectional view of a flexible circuit board obtained by covering the circuit wiring shown in fig. 9 with an insulating layer and a solder resist layer.
Fig. 12 is a sectional view of a flexible circuit board according to another embodiment of the present invention.
Fig. 13 is a sectional view of a flexible circuit board according to still another embodiment of the present invention.
Description of the symbols
The following detailed description will further illustrate the invention in conjunction with the above-described figures.
Detailed Description
Referring to fig. 1 to 10, a method for manufacturing a flexible circuit board 100 according to a preferred embodiment of the present invention includes the following steps:
referring to fig. 1, a copper-clad substrate 10 is provided. The copper-clad substrate 10 includes an insulating base layer 11 and two copper foil layers 12 formed on opposite surfaces of the base layer 11.
Referring to fig. 2, each copper foil layer 12 is etched by image transfer technique to form the desired circuit traces 20. Wherein each circuit wiring 20 includes at least one predetermined trace 21 (fig. 2 shows that each circuit wiring 20 includes two predetermined traces 21), and the predetermined traces 21 of the two circuit wirings 20 correspond in position.
Referring to fig. 3, a photosensitive layer 30 is covered on the surface of each circuit wiring 20, and the photosensitive layer 30 flows and fills the gap formed by the circuit wiring 20.
Referring to fig. 4 and 5, each photosensitive layer 30 is etched by an exposure and development process to form a pattern opening 31 in each photosensitive layer 30, and the pattern opening 31 exposes the predetermined circuit 21 and portions on both sides of each predetermined circuit 21, so as to form a region to be connected 110 defined on both sides of each predetermined circuit 21.
Specifically, each photosensitive layer 30 is a negative photosensitive film.
As shown in fig. 4, exposure processing is performed on each photosensitive layer 30: firstly, a pattern (not shown) is coated on the photosensitive layer 30 at a position corresponding to the predetermined line 21, and then the photosensitive layer 30 is subjected to an ultraviolet irradiation treatment, so that an uncovered area (i.e., an exposed area) of the photosensitive layer 30 is cured by the ultraviolet irradiation, and a covered area (i.e., an unexposed area) of the photosensitive layer 30 is not cured by the ultraviolet irradiation.
As shown in fig. 5, each photosensitive layer 30 after exposure is subjected to a developing process: the photosensitive layer 30 is soaked in a developing solution so that the unexposed region is removed by reaction with the developing solution, thereby forming the pattern opening 31 in the photosensitive layer 30. Specifically, the developing solution adopts NaCO with the concentration of 1%3。
Referring to fig. 6 and 7, the region to be conducted 110 of the base layer 11 is removed to form an opening 40.
In the present embodiment, the base layer 11 is made of positive photosensitive Polyimide (PI), and the opening 40 is formed by an exposure and development process.
Specifically, as shown in fig. 6, the base layer 11 is subjected to exposure treatment: the base layer 11 is first subjected to ultraviolet irradiation treatment, so that the uncovered area of the base layer 11 (i.e., the area to be connected 110, i.e., the exposed area) is cured by being irradiated with light, and the covered area of the base layer 11 (i.e., the portion of the base layer 11 except the area to be connected 110, i.e., the unexposed area) is not cured by being not irradiated with light.
As shown in fig. 7, the base layer 11 after exposure is subjected to a developing process: the base layer 11 is soaked in a developing solution, so that the exposed regions are removed by reaction with the developing solution, thereby forming the open pores 40.
In another embodiment, the material of the base layer 11 may also be negative photosensitive polyimide. At this time, when the photosensitive layer 30 is exposed, since the region 110 to be conducted of the base layer 11 is also located in an unexposed region, when the photosensitive layer 30 is developed, the region 110 to be conducted of the base layer 11 can be removed by over-development, that is, it is not necessary to additionally perform an exposure process on the base layer 11.
In other embodiments, the base layer 11 may also be made of a non-photosensitive material. For example, the material of the base layer 11 may be one of Polyimide (PI), Polyethylene Terephthalate (PET), Polyethylene Naphthalate (PEN), and the like. At this time, the opening 40 is formed by laser drilling.
Referring to fig. 8, a conductive layer 50 is formed on the inner wall of each opening 40.
In the present embodiment, the conductive layer 50 may be a conductive seed layer, an electroless copper plating layer, or an organic conductive film layer. Of course, the conductive layer 50 may be omitted.
Step seven, referring to fig. 9 and fig. 10, copper is plated on the surface of the predetermined circuit 21 to form two conductive circuit layers 60 on two opposite surfaces of the base layer 11, and copper is plated in the opening 40 formed with the conductive layer 50 to form a conductive portion 61. The conducting part 61 is wrapped on two sides of the predetermined circuit 21, and is used for electrically connecting the two conductive circuit layers 60 and realizing double-sided conduction. The conduction part 61 is not formed with a grommet. Then, each photosensitive layer 30 is removed.
Referring to fig. 11, an insulating layer 70 and a solder mask layer 80 are sequentially covered on the surface of each conductive trace layer 60, so as to obtain the flexible circuit board 100.
In this embodiment, the insulating layer 70 is made of an insulating adhesive resin, and the adhesive resin may be at least one selected from polypropylene (PP), epoxy resin, polyurethane, phenol resin, urea resin, melamine-formaldehyde resin, and polyimide adhesive resin.
Referring to fig. 11, a flexible circuit board 100 according to a preferred embodiment of the invention is provided. The flexible circuit board 100 includes a base layer 11 and a conductive trace layer 60 formed on each surface of the base layer 11. Each conductive line layer 60 includes a circuit trace 20. Each circuit wiring 20 includes at least one predetermined line 21, and the predetermined lines 21 of the two circuit wirings 20 correspond in position.
The base layer 11 is formed with openings 40 at both sides of each predetermined line 21. A conductive layer 50 is formed on the inner wall of each opening 40. A conducting portion 61 is formed in the opening 40 formed with the conductive layer 50, and the conducting portion 61 is wrapped on two sides of the predetermined circuit 21 and is used for electrically connecting the two conductive circuit layers 60 and realizing double-sided conduction. The conduction part 61 is not formed with a grommet.
The surface of each conductive trace layer 60 is sequentially covered with an insulating layer 70 and a solder mask 80.
In the flexible circuit board 100 and the manufacturing method thereof, the circuit wiring 20 is firstly manufactured on two surfaces of the base layer 11 by using original copper, then the openings 40 are opened on two sides of the predetermined circuit 21 of the base layer 11 by an exposure and development process or a laser opening method, and copper is plated in the openings 40 to form the conducting parts 61 which are coated on two sides of the predetermined circuit 21 to connect the two conductive circuit layers 60. Thus, not only is double-sided conduction achieved and the signal transmission speed improved, but also the advantage of using the original copper to make the conductive wiring (e.g., thin wiring (L/S </> 25/25 μm) is obtained). In addition, the problems of annular ring breakage, annular ring connection, annular ring deviation and the like caused by the annular ring can be avoided.
Furthermore, since the pattern opening 31 of the photosensitive layer 30 above the circuit wiring 20 is used to define the conducting position (i.e. the region to be conducted 110), the aperture of the opening 40 can be smaller, which is more beneficial to manufacturing high-density circuit boards.
Referring to fig. 12, another embodiment of the present invention further provides a flexible circuit board 200, which is different from the flexible circuit board 100 in that: in the flexible circuit board 200, the opening 40 is formed only on the left side of each predetermined line 21 of the base layer 11 due to the exposure left shift during the opening process. That is, the conduction part 61 covers only the left side of the predetermined line 21, and thereby realizes one-side conduction.
Referring to fig. 13, another embodiment of the present invention further provides a flexible circuit board 300, which is different from the flexible circuit boards 100 and 200 in that: in the flexible circuit board 300, the opening 40 is formed only on the right side of each predetermined line 21 of the base layer 11 due to the exposure right-hand deviation occurring during the opening process. That is, the conduction part 61 covers only the right side of the predetermined line 21, and thereby realizes one-side conduction.
Therefore, even if exposure deviation occurs in the hole opening process, conduction can be achieved, and the defects caused by the exposure deviation of the existing circuit board can be avoided.
It should be understood that the above examples are only for illustrating the present invention and are not to be construed as limiting the present invention. It will be apparent to those skilled in the art that various other changes and modifications can be made in the technical spirit of the present invention within the scope of the appended claims.
Claims (7)
1. A method for manufacturing a flexible circuit board includes:
providing a copper-clad substrate which comprises an insulating base layer and two copper foil layers formed on two opposite surfaces of the base layer;
etching each copper foil layer to form circuit wiring, wherein each circuit wiring comprises at least one preset circuit;
covering a photosensitive layer on the surface of each circuit wiring;
etching each photosensitive layer to form a pattern opening in each photosensitive layer, wherein the pattern opening exposes the predetermined circuit and two opposite sides of each predetermined circuit, so as to define a region to be conducted on the base layer at two sides of each predetermined circuit, respectively, and the projection of the predetermined circuit on the base layer is connected between the two regions to be conducted;
removing the region to be conducted to form an opening;
copper is plated on the surface of the preset circuit to form two conductive circuit layers on two opposite surfaces of the base layer, copper is plated in the open holes to form conducting parts, the conducting parts are located on two sides of each preset circuit and used for electrically connecting the two conductive circuit layers, and no hole ring is formed in each conducting part;
removing each photosensitive layer; and
and sequentially covering an insulating layer and a solder mask layer on the surface of each conductive circuit layer, thereby manufacturing the flexible circuit board.
2. The method for manufacturing a flexible circuit board according to claim 1, wherein: the material of basic unit is photosensitive polyimide, and the step "remove treat that the conducting region further includes in order to form the trompil" the material of basic unit:
carrying out ultraviolet illumination treatment on the base layer, wherein an exposure area is formed in the area to be conducted; and
and soaking the exposed base layer in a developing solution to remove the exposed area, thereby forming the open pore.
3. The method for manufacturing a flexible circuit board according to claim 1, wherein: the base layer is made of non-photosensitive polyimide, and the hole is formed in a laser drilling mode.
4. The method for manufacturing a flexible circuit board according to claim 1, wherein: the copper plating method further comprises the following steps:
a conductive layer is formed on the inner wall of each opening.
5. The utility model provides a flexible circuit board, includes a basic unit and is formed at two conductive circuit layers on the relative two surfaces of basic unit, its characterized in that, each conductive circuit layer includes a circuit wiring, and each circuit wiring includes an at least predetermined circuit, the basic unit is formed with the trompil respectively in the part that is located the both sides of each predetermined circuit, predetermined circuit is in projection connection in two in the basic unit between the trompil, be formed with a conduction portion in each trompil, conduction portion is used for two conductive circuit layers of electric connection, conduction portion does not form the hole ring, and the surface on each conductive circuit layer covers in proper order has an insulating layer and a welding-proof layer.
6. The flexible circuit board of claim 5, wherein the base layer is made of positive photosensitive polyimide.
7. The flexible circuit board of claim 5, wherein an electrically conductive layer is formed on an inner wall of each opening.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711106075.8A CN109788661B (en) | 2017-11-10 | 2017-11-10 | Flexible circuit board and preparation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711106075.8A CN109788661B (en) | 2017-11-10 | 2017-11-10 | Flexible circuit board and preparation method thereof |
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| Publication Number | Publication Date |
|---|---|
| CN109788661A CN109788661A (en) | 2019-05-21 |
| CN109788661B true CN109788661B (en) | 2021-08-24 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201711106075.8A Active CN109788661B (en) | 2017-11-10 | 2017-11-10 | Flexible circuit board and preparation method thereof |
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Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115529745A (en) * | 2021-06-25 | 2022-12-27 | 宏启胜精密电子(秦皇岛)有限公司 | Circuit board and method for manufacturing the same |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6442898A (en) * | 1987-08-11 | 1989-02-15 | Nec Corp | Manufacture of landless through-hole printed wiring board |
| JP2004146668A (en) * | 2002-10-25 | 2004-05-20 | Sharp Corp | Multilayer printed circuit board and manufacturing method thereof |
| CN1585594A (en) * | 2003-08-22 | 2005-02-23 | 日东电工株式会社 | Double-sided wiring circuit board and process for producing the same |
| CN105657988A (en) * | 2014-11-21 | 2016-06-08 | 宏启胜精密电子(秦皇岛)有限公司 | Flexible circuit board and manufacturing method thereof |
| CN106163102A (en) * | 2015-04-02 | 2016-11-23 | 富葵精密组件(深圳)有限公司 | Flexible PCB and preparation method thereof |
-
2017
- 2017-11-10 CN CN201711106075.8A patent/CN109788661B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6442898A (en) * | 1987-08-11 | 1989-02-15 | Nec Corp | Manufacture of landless through-hole printed wiring board |
| JP2004146668A (en) * | 2002-10-25 | 2004-05-20 | Sharp Corp | Multilayer printed circuit board and manufacturing method thereof |
| CN1585594A (en) * | 2003-08-22 | 2005-02-23 | 日东电工株式会社 | Double-sided wiring circuit board and process for producing the same |
| CN105657988A (en) * | 2014-11-21 | 2016-06-08 | 宏启胜精密电子(秦皇岛)有限公司 | Flexible circuit board and manufacturing method thereof |
| CN106163102A (en) * | 2015-04-02 | 2016-11-23 | 富葵精密组件(深圳)有限公司 | Flexible PCB and preparation method thereof |
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| CN109788661A (en) | 2019-05-21 |
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