Flexible circuit board with fine conductor diameter and its production process

Abstract

The present invention provides a flexible circuit board with fine conductor diameter and a production process thereof, which belongs to the technical field of flexible circuit board production. The production process of the flexible circuit board with fine conductor diameter is suitable for coiled materials, wherein the coiled materials have a substrate and a metal, and the steps are as follows: S10, covering the surface of the metal with a photosensitive material, and arranging an exposure lamp; S20, making a film with a shielding area and a light-transmitting area, placing the film between the exposure lamp and the coiled material, and exposing the photosensitive material with light emitted by the exposure lamp through the light-transmitting area; S30, removing the unexposed photosensitive material by a developer to form a bare area, and the exposed photosensitive material forms a masking layer; S40, first removing the metal in the bare area by an acidic solution, and then removing the masking layer by an alkaline solution to form a circuit area; S50, insulation printing, bridge printing; S60, quality inspection; S70, slitting and packaging.

Description

Technical Field

[0001] The invention belongs to the technical field of flexible circuit board production, and in particular relates to a flexible circuit board with fine conductor diameter and a production process thereof. Background Art

[0002] Flexible circuit boards, also known as "soft boards", are printed circuits made of flexible insulating substrates. They can be bent, wound, and folded freely. They can withstand millions of dynamic bendings without damaging the wires. They can be arranged arbitrarily according to spatial layout requirements and can be moved and stretched arbitrarily in three-dimensional space, thereby achieving the integration of component assembly and wire connection.

[0003] At present, the preparation process of flexible circuit boards adopts a printing method to print anti-corrosion ink on the double-sided antenna pattern area of ​​a thin film sheet. The pattern obtained by the printing method has low precision, which makes the final product have low precision. Summary of the invention

[0004] The embodiment of the present invention provides a flexible circuit board with fine conductor diameter and a production process thereof, aiming to solve the technical problem of low precision of finished products.

[0005] In a first aspect, an embodiment of the present invention provides a production process for a flexible circuit board with a fine diameter of a conductor, which is applicable to a coil, wherein the coil has a substrate and a metal fixed on the surface of the substrate, and the steps are as follows:

[0006] S10, covering the metal surface with a photosensitive material, and arranging an exposure lamp on top of the photosensitive material;

[0007] S20, preparing a film having a shielding area and a light-transmitting area, placing the film between the exposure lamp and the coil, and allowing the light emitted by the exposure lamp to pass through the light-transmitting area to expose the photosensitive material;

[0008] S30, removing the unexposed photosensitive material by a developer to form a bare area, and the exposed photosensitive material forms a masking layer;

[0009] S40, first removing the metal in the exposed area by an acidic solution, and then removing the masking layer by an alkaline solution to form a circuit area;

[0010] S50, performing insulation printing and bridge printing in the circuit area in sequence to form a finished coil;

[0011] S60, performing quality inspection on the finished coil;

[0012] S70, cutting and packaging the finished coils that have passed the quality inspection.

[0013] In combination with the first aspect, in a possible implementation, in the step S20, the exposure lamp is used to expose multiple processing areas on the photosensitive material along the extension direction of the roll, and a positioning point is exposed at the end of each processing area, and a control point corresponding to the positioning point is provided on the film, and by aligning the control point with the positioning point, the film is moved to align with the next processing area.

[0014] In combination with the first aspect, in a possible implementation, in the step S20, two groups of cameras are provided above the photosensitive material, wherein one group of cameras is used to capture the positioning points, and the other group of cameras is used to capture the edge of the photosensitive material.

[0015] In combination with the first aspect, in a possible implementation, the step S30 is completed in a developing cylinder, and the temperature in the developing cylinder is 24-30° C.;

[0016] The concentration of the drug solution in the developer is 0.8-1.2 g / L.

[0017] In combination with the first aspect, in a possible implementation manner, a nozzle for spraying the developer is provided in the developing cylinder, and the pressure of the nozzle is 1-2 kg / ㎡.

[0018] In combination with the first aspect, in a possible implementation, the step S40 is completed in an etching tank and a film stripping tank in sequence, and the temperatures in the etching tank and the film stripping tank are both 40-50°C.

[0019] In combination with the first aspect, in a possible implementation manner, a nozzle for spraying the acid solution is provided in the etching cylinder, and the pressure of the nozzle is 1-2 kg / ㎡.

[0020] In combination with the first aspect, in a possible implementation manner, a nozzle for spraying the alkaline solution is provided in the film removal cylinder, and the pressure of the nozzle is 0.5-1 kg / ㎡.

[0021] In combination with the first aspect, in a possible implementation, both step S30 and step S40 need to be dried after completion, and the drying temperature is 65-75°C.

[0022] Compared with the prior art, the production process of the flexible circuit board with fine conductor diameter shown in the embodiment of the present application is as follows:

[0023] The pattern is transferred to a photosensitive material by exposure. This process allows complex circuit patterns to be created in a very small space. This process can also capture tiny patterns, thereby improving the accuracy of the finished product.

[0024] In a second aspect, an embodiment of the present invention further provides a flexible circuit board manufactured using the production process for a fine-diameter flexible circuit board with a conductor, wherein the minimum line width of the flexible circuit board is 0.04 mm and the line width accuracy is ±20 μm. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A flowchart showing a flexible circuit board production process is provided for an embodiment of the present invention;

[0026] Figure 2 Provided for an embodiment of the present invention is a schematic diagram of the structure of a flexible circuit board. DETAILED DESCRIPTION

[0027] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0028] See also Figure 1 , the production process of the flexible circuit board with fine diameter of the conductor of the present invention is described. A production process of the flexible circuit board with fine diameter of the conductor is suitable for coils, the coils have a substrate and a metal fixed on the surface of the substrate, and the steps are as follows: S10, covering the surface of the metal with a photosensitive material, and arranging an exposure lamp on the top of the photosensitive material; S20, making a film with a shielding area and a light-transmitting area, placing the film between the exposure lamp and the coil, and the light emitted by the exposure lamp exposes the photosensitive material through the light-transmitting area; S30, removing the unexposed photosensitive material by a developer to form a bare area, and the exposed photosensitive material forms a masking layer; S40, first removing the metal in the bare area by an acidic solution, and then removing the masking layer by an alkaline solution to form a circuit area; S50, performing insulation printing and bridge printing in the circuit area in sequence to form a finished coil; S60, performing quality inspection on the finished coil; S70, cutting and packaging the finished coil that passes the quality inspection.

[0029] Compared with the prior art, the production process of the flexible circuit board with fine conductor diameter provided in this embodiment is as follows:

[0030] The pattern is transferred to a photosensitive material by exposure. This process allows complex circuit patterns to be created in a very small space. This process can also capture tiny patterns, thereby improving the accuracy of the finished product.

[0031] In some embodiments, in step S20, an exposure lamp is used to expose multiple processing areas on the photosensitive material along the extension direction of the roll, and a positioning point is exposed at the end of each processing area. There is a control point corresponding to the positioning point on the film, and by aligning the control point with the positioning point, the film is moved to align with the next processing area.

[0032] In some embodiments, in step S20, two groups of cameras are arranged above the photosensitive material, one group of cameras is used to capture the positioning points, and the other group of cameras is used to capture the edge of the photosensitive material.

[0033] Specifically, the exposure lamp energy is 50-90mj, the positioning accuracy is ±0.1mm, and the line accuracy is ±0.01mm.

[0034] The camera captures the positioning point and the edge of the photosensitive material to move the film so that it is aligned with the next processing area, thereby improving the alignment accuracy.

[0035] In some embodiments, step S30 is completed in a developing tank, the temperature in the developing tank is 24-30° C., and the concentration of the drug solution in the developer is 0.8-1.2 g / L.

[0036] Specifically, the liquid medicine component is sodium carbonate, and has excellent developing effect; the liquid medicine is a single component, is easy to prepare, and has low preparation cost.

[0037] The increase in temperature will accelerate the chemical reaction in the developer, resulting in a faster development speed, which may cause a certain degree of development in the unexposed parts of the film, that is, the fog will increase, affecting the clarity and contrast of the pattern; high-temperature development will make the pattern coarser and reduce the clarity. At the same time, due to the excessive expansion of the film at high temperature, water-like ripples may appear, and even cause the film to fall off, seriously affecting the integrity of the pattern.

[0038] Lowering the temperature will slow down the chemical reaction rate in the developer, resulting in a slower development speed, which may cause incomplete development of the exposed part on the film, affecting the integrity and clarity of the pattern; in a low temperature environment, the development efficiency of the developer will be significantly reduced, and it is difficult to achieve the development effect at room temperature. This may require increasing the development time or increasing the concentration of the developer to compensate, but it will also increase the complexity and cost of the development process.

[0039] Changes in developer concentration will affect relative sensitivity. Within a certain range, as developer concentration increases, the relative sensitivity of the photosensitive material will also increase, thereby improving the photosensitivity effect of the pattern. However, too high a concentration may also cause excessive pattern contrast, affecting pattern quality.

[0040] In some embodiments, a nozzle for spraying developer is provided in the developing cylinder, and the pressure of the nozzle is 1-2 kg / ㎡.

[0041] When the nozzle pressure is too small, the spray cone angle may be small and the spray uniformity may be poor, which will result in insufficient developer coverage in certain areas, thereby affecting the development effect and causing incomplete removal of the photosensitive material, leaving photosensitive material residues and affecting subsequent process steps.

[0042] When the nozzle pressure is too high, the spray cone angle may reach the maximum and the spray uniformity is better. However, if the pressure is too high, the fluid may be broken too violently, which will affect the uniformity of the spray and cause excessive removal or damage of the photosensitive material, thereby affecting the development effect. Especially in the fine production of wires, excessive pressure may lead to poor development effect.

[0043] In some embodiments, step S40 is completed in the etching tank and the film stripping tank in sequence, and the temperatures in the etching tank and the film stripping tank are both 40-50°C.

[0044] Specifically, the temperatures in the etching tank and the film stripping tank are the same.

[0045] Increased temperature will lead to faster chemical reaction rate, so the etching speed will also increase accordingly, but this may make it difficult to accurately control the etching depth, or even cause over-etching; too high a temperature will accelerate the volatilization of the etching solution, especially the etching solution containing volatile components, which will not only change the concentration of the etching solution, but also affect the uniformity of the etching effect.

[0046] At high temperatures, photosensitive materials may soften, flow or even bubble, resulting in morphological distortion and affecting subsequent process steps. At the same time, too high a temperature will cause the film to be stripped too quickly, which may leave photosensitive material residues and affect the accuracy and stability of subsequent process steps.

[0047] Lowering the temperature will slow down the chemical reaction rate, resulting in a slower etching speed, which may lead to insufficient etching, that is, failure to completely remove the photosensitive material; the solubility of the etching solution may decrease at low temperatures, resulting in unsatisfactory etching results.

[0048] The lower temperature will slow down the chemical reaction rate, resulting in a slower stripping speed, which may result in the photosensitive material not being completely removed, leaving photosensitive material residues; at the same time, due to the slower stripping rate, the entire processing time will be extended, thereby reducing production efficiency.

[0049] In some embodiments, a nozzle for spraying an acid solution is provided in the etching tank, and the pressure of the nozzle is 1-2 kg / ㎡.

[0050] As the nozzle pressure becomes larger, the etching rate may increase because the stronger jet pressure helps the acid solution to better penetrate the surface of the photosensitive material, but too much pressure may cause over-etching, especially in the etching of fine diameter wires, which may damage the wires.

[0051] When the nozzle pressure decreases, the etching rate may slow down because the acid solution cannot fully penetrate the surface of the photosensitive material due to insufficient jet pressure, and the etching may be incomplete.

[0052] In some embodiments, a nozzle for spraying alkaline solution is provided in the film removal cylinder, and the pressure of the nozzle is 0.5-1 kg / ㎡.

[0053] As the nozzle pressure increases, the stripping rate may increase because stronger jet pressure helps the alkaline solution to better penetrate the surface of the photosensitive material, but excessive pressure may cause the film to be stripped too quickly, which may leave photosensitive material residues and affect the accuracy and stability of subsequent process steps.

[0054] The nozzle pressure becomes smaller, the film stripping rate slows down, and the time of the entire processing process will be prolonged, thereby reducing production efficiency.

[0055] In some embodiments, both step S30 and step S40 need to be dried after completion, and the drying temperature is 65-75°C.

[0056] If the drying temperature after development is too high, the photosensitive material may decompose, and the gases and impurities produced by the decomposition may remain in the product, causing performance degradation or failure. If the drying temperature after development is too low, the solvent in the photosensitive material may not be completely evaporated, resulting in solvent residue. Solvent residue may cause bubbles, delamination or unstable performance during use of the product.

[0057] If the drying temperature after etching and film stripping is too high, the product will be over-drying, causing problems such as warping, cracking or deformation. These deformations may affect the dimensional accuracy and flatness of the product, and thus affect subsequent processes; if the drying temperature after etching and film stripping is too low, the drying will not be thorough, which may cause moisture or other impurities on the product surface, thereby affecting the quality and reliability of the product. These quality problems may gradually appear during use, resulting in product performance degradation or failure.

[0058] In some embodiments, in step S60, the quality inspection includes appearance, circuit open and short circuit, gap and electrical performance inspection. The quality inspection can be completed manually or with the help of AOI equipment.

[0059] It should be noted that products with no defects in appearance, no open or short circuits, a gap rate below 50%, and good or above electrical performance are qualified, and the rest are unqualified.

[0060] In some embodiments, the quality inspection further includes wiping impurities on the surface of the finished product with a cotton swab dipped in alcohol to reduce the impact of the impurities on the performance of the finished product.

[0061] In some embodiments, in step S70, the coil width accuracy is ±0.5 mm, the slitting accuracy is 0.15 mm, and the coiling accuracy is ±1 mm.

[0062] Based on the same inventive concept, see Figure 2 The embodiment of the present application also provides a flexible circuit board made using the production process of the fine-diameter flexible circuit board with a conductor, wherein the minimum line width of the flexible circuit board is 0.04 mm, and the line width accuracy of the flexible line is ±20 μm.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A production process for a flexible circuit board with fine conductor diameter, characterized in that: Applicable to a coiled material, the coiled material has a substrate and a metal fixed on the surface of the substrate, the steps are as follows: S10, covering the metal surface with a photosensitive material, and arranging an exposure lamp on top of the photosensitive material; S20, preparing a film having a shielding area and a light-transmitting area, placing the film between the exposure lamp and the coil, and allowing the light emitted by the exposure lamp to pass through the light-transmitting area to expose the photosensitive material; The exposure lamp is used to expose a plurality of processing areas on the photosensitive material along the extension direction of the coil, and a positioning point is exposed at the end of each processing area. The film has a reference point corresponding to the positioning point, and the film is moved to align with the next processing area by aligning the reference point with the positioning point. Two groups of cameras are arranged above the photosensitive material, one group of the cameras is used to capture the positioning point, and the other group of the cameras is used to capture the edge of the photosensitive material. S30, removing the unexposed photosensitive material by a developer to form a bare area, and the exposed photosensitive material forms a masking layer; S40, first removing the metal in the exposed area by an acidic solution, and then removing the masking layer by an alkaline solution to form a circuit area; S50, performing insulation printing and bridge printing in the circuit area in sequence to form a finished coil; S60, performing quality inspection on the finished coil; S70, cutting and packaging the finished coils that have passed the quality inspection.

2. The production process of a flexible circuit board with fine conductor diameter according to claim 1, characterized in that: The step S30 is completed in a developing tank, and the temperature in the developing tank is 24-30° C.; The concentration of the drug solution in the developer is 0.8-1.2 g / L.

3. The production process of a flexible circuit board with fine conductor diameter as claimed in claim 2, characterized in that: A nozzle for spraying the developer is arranged in the developing cylinder, and the pressure of the nozzle is 1-2 kg / ㎡.

4. The production process of a flexible circuit board with fine conductor diameter according to claim 1, characterized in that: The step S40 is completed in the etching tank and the film stripping tank in sequence, and the temperatures in the etching tank and the film stripping tank are both 40-50°C.

5. The production process of a flexible circuit board with fine conductor diameter as claimed in claim 4, characterized in that: The etching cylinder is provided with a nozzle for spraying the acid solution, and the pressure of the nozzle is 1-2 kg / ㎡.

6. The production process of a flexible circuit board with fine conductor diameter according to claim 4, characterized in that: The film removal cylinder is provided with a nozzle for spraying the alkaline solution, and the pressure of the nozzle is 0.5-1 kg / ㎡.

7. The production process of a flexible circuit board with fine conductor diameter according to claim 1, characterized in that: After the step S30 and the step S40 are completed, drying is required, and the drying temperature is 65-75°C.

8. A flexible circuit board with fine conductor diameter, characterized in that: The flexible circuit board is manufactured using the production process for a fine-diameter flexible circuit board with a conductor as described in any one of claims 1 to 7, wherein the minimum line width of the flexible circuit board is 0.04 mm and the line width accuracy is ±20 μm.

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