Surface treatment method of flexible printed circuit board

Abstract

The surface treatment method of the flexible printed circuit board comprises the following steps: forming fluoride on the surface of the flexible printed circuit board; and depositing a diamond-like carbon film on the surface of the fluoride, wherein in the deposition, precursor gas and isooctyltrimethylsilane are introduced into a reaction chamber, and chemical vapor deposition is carried out at a preset temperature to form the diamond-like carbon film. The method is simple and easy to implement and low in cost, the bonding strength between the diamond-like carbon film and the flexible printed circuit board can be improved, the residual stress of the diamond-like carbon film is reduced, and the stability of the diamond-like carbon film is improved.

Description

Technical Field

[0001] The present invention relates to the field of coating, and particularly to a surface treatment method for a flexible printed circuit board. Background Art

[0002] Diamond-like carbon (DLC) is a metastable amorphous material containing diamond and graphite structures, with excellent electrical properties such as stable surface resistance, low dielectric constant, and wide bandgap, as well as many advantages such as chemical stability and thermal stability. It is an ideal resistive electrode material. Forming a DLC layer on the surface of a flexible printed circuit board (FPC) is beneficial to performance improvement. Currently, directly plating a DLC layer on the surface of an FPC will cause the surface of the FPC to curl, thus affecting the processing of subsequent processes and subsequent applications.

[0003] Therefore, it is necessary to provide an improved surface treatment method for a flexible printed circuit board to overcome the above defects. Summary of the Invention

[0004] The purpose of the present invention is to provide an improved surface treatment method for a flexible printed circuit board, which is simple, easy to implement, and low in cost, can improve the bonding strength between the diamond-like carbon film and the flexible printed circuit board, reduce the residual stress of the diamond-like carbon film, and improve the stability of the diamond-like carbon film.

[0005] To achieve the above purpose, the surface treatment method for a flexible printed circuit board of the present invention includes the following steps:

[0006] Forming a fluoride on the surface of the flexible printed circuit board; and

[0007] Depositing a diamond-like carbon film on the surface of the fluoride;

[0008] Wherein, in the deposition, a precursor gas and isooctyltrimethylsilane are introduced into the reaction chamber, and chemical vapor deposition is carried out at a predetermined temperature to form the diamond-like carbon film.

[0009] Compared with the prior art, in the surface treatment method of the present invention, first a fluoride is formed on the surface of the flexible circuit board, and then a diamond-like carbon film is deposited on the fluoride by chemical vapor deposition. Moreover, during the deposition, isooctyltrimethylsilane is introduced. This gas can significantly reduce the residual stress of the diamond-like carbon film, effectively reduce the risk of surface microcracks caused by mechanical deformation, thereby improving the stability of the diamond-like carbon film; in addition, the fluoride can enhance the bonding strength of the diamond-like carbon film on the flexible printed circuit board. This method is simple, easy to implement, and low in cost, and is suitable for industrial promotion and application.

[0010] Preferably, the formation of the fluoride includes: introducing fluoropropane into a reaction chamber, controlling the pressure of the reaction chamber to be 1 - 2 kPa, and the temperature to be 300 - 500 °C.

[0011] Preferably, the precursor gas is a mixture of methyl methacrylate and hydrogen.

[0012] Preferably, the predetermined temperature is 300 - 500 °C.

[0013] Preferably, in the chemical vapor deposition, the pressure of the reaction chamber is 1.5 - 3 kPa.

[0014] Preferably, the time of the chemical vapor deposition is 3 - 5 minutes.

[0015] Preferably, the flow rate of isooctyltrimethylsilane accounts for 8% - 10% of the total gas flow rate.

[0016] Preferably, in the chemical vapor deposition, an additive is added to the reaction chamber.

[0017] Preferably, the additive includes at least one of lecithin, phosphatidylcholine, and glass powder. Detailed Description of the Invention

[0018] To make the above objects, features, and advantages of the present application more apparent and understandable, the following describes the specific embodiments of the present application in detail with reference to some embodiments. Many specific details are set forth in the following description to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0019] In the description of the present application, the terms "first" and "second" are used for descriptive purposes only and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present application, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0020] In this application, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the horizontal height of the first feature is less than that of the second feature.

[0021] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are only for the purpose of illustration and do not represent the only implementation.

[0022] The surface treatment method of the flexible printed circuit board of the present invention will be further described below in conjunction with embodiments, but the present invention is not limited thereby. The method of the present invention aims to provide a surface treatment method for a flexible printed circuit board, which is simple and easy to implement, has low cost, can improve the bonding strength between the diamond-like carbon film and the flexible printed circuit board, reduce the residual stress of the diamond-like carbon film, and improve the stability of the diamond-like carbon film.

[0023] In an embodiment of the surface treatment method of the flexible printed circuit board of the present invention, the following steps are included:

[0024] Forming a fluoride on the surface of the flexible printed circuit board; and

[0025] Depositing a diamond-like carbon film on the surface of the fluoride;

[0026] Wherein, in the deposition, a precursor gas and isooctyltrimethylsilane are introduced into the reaction chamber, and chemical vapor deposition is carried out at a predetermined temperature to form the diamond-like carbon film.

[0027] In the surface treatment method of the present invention, first, a fluoride is formed on the surface of the flexible circuit board, and then a diamond-like carbon film is deposited on the fluoride by chemical vapor deposition. Moreover, during the deposition, isooctyltrimethylsilane is introduced. This gas can significantly reduce the residual stress of the diamond-like carbon film, effectively reduce the risk of surface microcracks caused by mechanical deformation, and thus improve the stability of the diamond-like carbon film. In addition, the fluoride can enhance the bonding strength of the diamond-like carbon film on the flexible printed circuit board. This method is simple and easy to implement, with low cost, and is suitable for industrial promotion and application.

[0028] Specifically, in a specific embodiment, first, the flexible printed circuit board is cleaned and placed in a reaction chamber. Then, a hydrophilic fluoride such as fluoropropane is used to react chemically with the surface of the flexible printed circuit board, thereby forming a layer of fluoride covering the surface of the flexible printed circuit board. Preferably, the reaction conditions in the reaction chamber are controlled as follows: the temperature is 300 - 500 °C, the pressure is 1 - 2 kPa, and the reaction time is 8 - 10 minutes.

[0029] Next, a diamond-like carbon film is deposited on the surface of the fluoride. In this step, a mixture of methyl methacrylate and hydrogen is first introduced into the reaction chamber to form a precursor gas for the diamond-like carbon film. Specifically, isooctyltrimethylsilane is introduced while introducing the precursor gas. Optionally, isooctyltrimethylsilane can be first mixed with the precursor gas and then introduced into the reaction chamber together, or independently of the precursor gas and introduced into the reaction chamber separately. Specifically, the flow rate of isooctyltrimethylsilane accounts for 8% - 10% of the total gas flow rate. The reaction chamber is heated to 300 - 500 °C, the pressure is 1.5 - 3 kPa, and the reaction time is 3 - 5 minutes. Under these conditions, the precursor gas undergoes a chemical reaction on the surface of the flexible circuit board to deposit a diamond-like carbon film. The carbon-hydrogen bond of the isooctyltrimethylsilane is cut by the diamond-like carbon film, generating free aromatic rings, enabling the excess carbon atoms to form stronger bonds with the flexible circuit board, and thus having a stronger bonding force.

[0030] Optionally, during the deposition process of this embodiment, other additives such as lecithin, phosphatidylcholine, and glass powder can also be added as needed to enhance the performance of the diamond-like carbon film.

[0031] In summary, in the present invention, first, a fluoride is formed on the surface of the flexible circuit board, and then a diamond-like carbon film is deposited on the fluoride by chemical vapor deposition. Moreover, during the deposition, isooctyltrimethylsilane is introduced. This gas can significantly reduce the residual stress of the diamond-like carbon film, effectively reduce the risk of surface microcracks caused by mechanical deformation, and thus improve the stability of the diamond-like carbon film. In addition, the fluoride can enhance the bonding strength of the diamond-like carbon film on the flexible printed circuit board. This method is simple and easy to implement, with low cost, and is suitable for industrial promotion and application.

[0032] The above-disclosed are only the preferred embodiments of the present invention. Certainly, the scope of rights of the present invention cannot be limited thereby. Therefore, equivalent changes made according to the scope of the patent application of the present invention still fall within the scope covered by the present invention.

Claims

1. A surface treatment method for a flexible printed circuit board, characterized in that, Including the following steps: Forming a fluoride on the surface of a flexible printed circuit board; And Depositing a diamond-like carbon film on the surface of the fluoride; Wherein, in the deposition, a precursor gas and isooctyltrimethylsilane are introduced into a reaction chamber, and chemical vapor deposition is carried out at a predetermined temperature to form the diamond-like carbon film.

2. The surface treatment method of the flexible printed circuit board according to claim 1, characterized in that, The formation of the fluoride includes: introducing fluoropropane into a reaction chamber, controlling the pressure of the reaction chamber to be 1-2 kPa, and the temperature to be 300-500 °C.

3. The surface treatment method of the flexible printed circuit board according to claim 1, wherein, The precursor gas is a mixture of methyl methacrylate and hydrogen.

4. The surface treatment method of the flexible printed circuit board according to claim 1, wherein, The predetermined temperature is 300-500 °C.

5. The surface treatment method of the flexible printed circuit board according to claim 1, characterized in that, In the chemical vapor deposition, the pressure of the reaction chamber is 1.5-3 kPa.

6. The surface treatment method of the flexible printed circuit board according to claim 5, characterized in that, The time of the chemical vapor deposition is 3-5 minutes.

7. The surface treatment method of the flexible printed circuit board according to claim 1, characterized in that, The flow rate of the isooctyltrimethylsilane accounts for 8%-10% of the total gas flow rate.

8. The surface treatment method of the flexible printed circuit board according to claim 1, characterized in that, In the chemical vapor deposition, an additive is added to the reaction chamber.

9. The surface treatment method of the flexible printed circuit board according to claim 8, wherein, The additive includes at least one of lecithin, phosphatidylcholine, and glass powder.