A kind of surface protection method of flexible printed circuit board

Abstract

The invention relates to a method for protecting surface of a flexible printed circuit board. The method comprises the following steps of: a, manufacturing a silk printing screen plate; b, aligning and regulating, so that a pattern on the silk printing screen plate is just opposite to a surface-protecting area of the circuit board; c, uniformly coating liquid polyimide (PI) on the surface-protecting area of the circuit board through the pattern on the silk printing screen plate; and d, drying the circuit board. In the method for protecting the surface of the flexible printed circuit board, the liquid PI is uniformly coated on the surface-protecting area of the flexible circuit board (FPC), and dried and cured at high temperature to form a protecting layer with excellent solder resistance and flexibility, so that the liquid PI has the same function of protecting the copper surface of a substrate as a common covering film, the working processes are reduced, the product producing time isshortened, manpower is saved, raw materials are saved, and production cost is reduced; and in the aspect of quality control, quality problems such as air bubbles generated in the process of manufacturing the common covering film, poor creases and the like are avoided, and the qualified rate of products is improved.

Description

technical field [0001] The invention belongs to the field of printed circuit boards and relates to a surface protection method for flexible printed circuit boards. Background technique [0002] FPC (Flexible Printed Circuit Board) generally uses FCCL (Flexible Copper Clad Laminate: Flexible Copper Clad Laminate) as the substrate for production. And plugging fingers (line ends) are exposed to the air, most of the lines need to be isolated from the air to prevent oxidation or corrosion, so as to increase the service life of metal copper, and also need to prevent electrical connection with other electronic components For reasons such as short circuit, it is necessary to cover the FPC with a layer of protective film to protect the copper surface. Now most of the flexible printed circuit board (FPC) products, refer to figure 1 As shown, including the substrate 1 and the substrate base film 4, a solid PI (full name: Polyimide, polyimide) covering film will be selected when coveri...

AI Technical Summary

Problems solved by technology

In addition, in terms of quality control, abnormalities such as creases and air bubbles often occur in the blanking, pressing and other processes, resulting in the scrapping of the product. In this way, the process with multiple processes, multiple costs, and multiple abnormalities must be improved.

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