CN113873771A

CN113873771A - Manufacturing process suitable for ultra-fine FPC (flexible printed circuit) circuit

Info

Publication number: CN113873771A
Application number: CN202111239952.5A
Authority: CN
Inventors: 李钰
Original assignee: Hi P Shanghai Housing Appliance Co ltd
Current assignee: Hi P Shanghai Housing Appliance Co ltd
Priority date: 2021-10-25
Filing date: 2021-10-25
Publication date: 2021-12-31

Abstract

The invention discloses a manufacturing process suitable for a hyperfine FPC (flexible printed circuit) circuit, which comprises the following steps: s1, providing a PI base material with a double-sided copper foil; s2, half-etching the double-sided copper foil; s3, pasting a dry film on the two sides; s4, developing the circuit pattern on the dry film completely through a developing process by using an LDI laser direct imaging exposure process in a positive mode; s5, electroplating the circuit at the position where the dry film is opened according to a circuit pattern electroplating process; s6, removing the residual film originally covered between the circuits by a film removing process; and S7, finally, etching the bottom copper with the residual thickness of the original copper foil between the circuits completely through a flash etching process, namely, finishing the manufacture of the secondary high-precision fine circuit. The invention can process the line width and line distance of about 20 mu m, and the copper foil can be processed in the specification of 12-30 mu m, thereby solving the problem that the current traditional production process can not process the ultra-fine line width and line distance soft board.

Description

Manufacturing process suitable for ultra-fine FPC (flexible printed circuit) circuit

Technical Field

The invention relates to the technical field of flexible circuit board production, in particular to a manufacturing process suitable for a hyperfine FPC circuit.

Background

The application field of the soft board is very wide, especially the precision requirement of the FPC used by wearing is higher, how to solve the design of all circuits, the consideration of the device Layout, the space structure and the like in a limited space, each soft board factory continuously improves the process capability parameters thereof, the process capability parameters are developed from an early single-double layer board to a multilayer board, a multilayer blind buried hole connecting board, a soft and hard combined board and the like, a circuit processing and forming method adopts the steps of pasting a dry film, exposing, developing, etching, removing a film, AOI … …, in an exposure process, the precision of a general dry film resolution combined film can only reach the precision of more than 35 microns, trapezoidal copper formed by the thickness of the dry film and the etching factor of a side copper foil after etching cannot be avoided, when the line distance is smaller, the bottom cannot be removed cleanly and the copper foil is short-circuited, the production operation can not be continued; in addition, because the line width and the line distance are limited, the requirement of a precise line order for a client cannot be accepted, and the order accepting capability of a factory and the trust of a client to the factory are greatly reduced.

Therefore, one of the most important parameters for the soft board factory is the minimum line width and the minimum distance between adjacent lines that can be processed. The traditional technology adopts the technology that the copper foil with redundant parts such as line distance in the circuit graph is corroded by liquid medicine to be removed completely, and the common dry film is used in the process of protecting the circuit width, the thickness of the copper foil of the circuit is received, the thickness of the dry film and the adhesive force influence of the dry film and the copper foil surface are received, even if the dry film can be effectively completed in the exposure analysis and developing process, the circuit part can not be effectively protected by the dry film under the pressure that the circuit body covered by the dry film is sprayed up and down in an etching groove body, because the dry film width and the height ratio on the surface of the ultra-fine circuit can not effectively ensure that the dry film can be completely attached to the surface layer of the circuit, and the ultra-fine circuit processing and manufacturing can not be completed.

Disclosure of Invention

In order to solve the technical problem, the invention provides a manufacturing process suitable for a hyperfine FPC (flexible printed circuit) circuit, which comprises the following steps:

s1, providing a PI base material with a double-sided copper foil, wherein the thickness of the PI base material is a, and the thickness of the copper foil is b;

s2, semi-etching the double-sided copper foil and reserving bottom copper with the thickness of c;

s3, pasting dry films on two sides according to the circuit thickness requirement, wherein the thickness d of the dry films is more than or equal to the circuit thickness;

s4, developing the circuit pattern on the dry film by using an LDI laser direct imaging exposure process in a positive mode through a developing process, developing the circuit width f part in the positive process, and reserving the residual film with the width of the circuit interval e;

s5, electroplating the circuit at the position where the dry film is opened according to a circuit pattern electroplating process, and stopping when the electroplating thickness meets the circuit thickness required by a customer;

s6, removing the residual film originally covered between the circuits by a film removing process;

and S7, finally, etching the bottom copper with the residual thickness of the original copper foil between the circuits completely through a flash etching process, and thus finishing the manufacture of the high-precision circuit.

In step S1, the thickness b of the copper foil is 12 to 30 μm.

In step S2, the thickness c of the base copper is 2 to 3 μm.

In step S3, the thickness d of the dry film is greater than or equal to the thickness of the circuit.

In step S4, the line width f is less than or equal to 25 μm, and the line pitch e is less than or equal to 25 μm.

According to the technical scheme, the original copper foil is subjected to a half-etching process firstly, the thickness of the copper foil on the surface of a standard PI base material is only kept at 2-3 mu m, a dry film is pasted and then a positive film mode is used for directly LDI laser forming a circuit, and then development is carried out, the line distance part between the circuit and the line is not covered by the dry film, the circuit part developed by the dry film can be directly electroplated to obtain the required copper thickness by using an electroplating process according to a pattern electroplating process mode, then the film is removed, a flash etching process is carried out to completely etch the 2-3 mu m bottom copper remained between the original circuit and the line, and finally the required line part is remained.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below.

FIG. 1 is a schematic view of a double-sided copper foil PI substrate of step S1 according to the embodiment of the present invention;

FIG. 2 is a schematic diagram illustrating the step S2 after the half etching process according to the embodiment of the present invention;

FIG. 3 is a schematic diagram of the embodiment of the invention after adhering dry films in step S3;

FIG. 4 is a schematic diagram of the imaging exposure process of step S4 according to the embodiment of the present invention;

FIG. 5 is a schematic diagram illustrating the electroplating process of step S5 according to the embodiment of the present invention;

FIG. 6 is a schematic diagram illustrating the step S6 after the stripping process according to the embodiment of the present invention;

FIG. 7 is a schematic diagram of the flash etching process of step S7 according to the embodiment of the present invention.

In the figure: a PI substrate; 2. copper foil; 3. bottom copper; 4. drying the film; 5. residual membrane; 6. and (4) a line.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

The manufacturing process suitable for the ultra-fine FPC circuit provided by the embodiment comprises the following steps:

s1, providing a PI substrate 1 having a double-sided copper foil 2, the thickness a of the PI substrate 1 being 25 μm, and the thickness b of the double-sided copper foil 2 being 12 μm;

s2, half-etching the double-sided copper foil 2 and reserving bottom copper 3 with the thickness c of 3 mu m;

s3, double-sided pasting of a dry film 4 with the thickness d being 25 mu m according to the circuit thickness requirement;

s4, developing the pattern of the circuit 6 on the dry film 4 completely by using an LDI laser direct imaging exposure process in a positive mode, developing the part with the width f of the circuit 6 being 25 mu m under the positive process, and reserving the residual film 5 with the width being 25 mu m between the circuit 6 and the interval e;

s5, electroplating the circuit 6 at the position where the dry film 4 is opened according to a circuit 6 pattern electroplating process, and stopping when the electroplating thickness meets the thickness of the circuit 6 required by a customer;

s6, removing the residual film 5 originally covered between the circuit 6 and the circuit 6 by a film removing process;

and S7, finally, etching the bottom copper 3 with the residual thickness of the original copper foil 2 between the circuits 6 through a flash etching process, namely, finishing the manufacture of the high-precision circuits with the line width and the line distance of less than or equal to 25 mu m.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to the above-described embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A manufacturing process suitable for a hyperfine FPC circuit is characterized by comprising the following steps:

s1, providing a PI base material (1) with a double-sided copper foil (2), wherein the thickness of the PI base material (1) is a, and the thickness of the copper foil (2) is b;

s2, half-etching the double-sided copper foil (2) and reserving bottom copper (3) with the thickness of c;

s3, pasting a dry film (4) on two sides according to the circuit thickness requirement, wherein the thickness d of the dry film (4) is more than or equal to the circuit thickness;

s4, developing the pattern of the circuit (6) on the dry film (4) by using an LDI laser direct imaging exposure process in a positive mode through a developing process, developing the width f part of the circuit (6) in the positive process, and reserving a residual film (5) with the width of the space e between the circuits (6);

s5, electroplating the circuit (6) at the position where the dry film (4) is opened according to a circuit (6) pattern electroplating process, and stopping when the electroplating thickness meets the thickness of the circuit (6) required by a customer;

s6, removing the residual film (5) originally covered between the circuit (6) and the circuit (6) by a film removing process;

and S7, finally, etching the bottom copper (3) with the residual thickness of the original copper foil (2) between the circuits (6) through a flash etching process to be clean, and finishing the manufacture of the high-precision circuit.

2. The process of claim 1, wherein in step S1, the thickness b of the copper foil (2) is 12-30 μm.

3. The process for manufacturing ultra-fine FPC lines according to claim 1, wherein in step S2, the thickness c of the base copper (3) is 2-3 μm.

4. The process for manufacturing ultra-fine FPC according to claim 1, wherein in step S3, the thickness d of the dry film (4) is greater than or equal to the thickness of the circuit (6).

5. The process for manufacturing ultra-fine FPC according to claim 1, wherein in step S4, the width f of the traces (6) is less than or equal to 25 μm, and the pitch e of the traces (6) is less than or equal to 25 μm.