Method for acquiring optimal focal plane distance of laser direct imaging equipment

Abstract

In the prior art, the exposure focal plane of laser direct imaging equipment is difficult to rapidly acquire. Based on the difficult problem in the prior art, the present invention provides a method for acquiring the optimal focal plane distance of laser direct imaging equipment. The method comprises: inputting a focal plane detection pattern into laser direct imaging equipment; installing and debugging a substrate; carrying out primary exposure on the substrate; carrying out primary displacement exposure on the substrate; repeatedly performing the displacement exposure on the substrate; developing the substrate; and finding the least shedding pattern on the substrate. According to the present invention, the necessarily-used detection step for measuring the line width by using a microscope in the traditional method is eliminated, the optimal expose focal plane can be quickly, intuitively and accurately found, the detection efficieny and the accuracy of the focal plane are improved, and the PCB reject risk caused by the insufficient exposure is reduced.

Description

technical field [0001] The invention relates to the technical field of printed circuit board pattern transfer, in particular to a method for obtaining the optimal focal plane distance of a laser direct imaging device. Background technique [0002] For the field of printed circuit board processing, especially the manufacture of high-precision HDI boards and packaging substrates, image transfer equipment is undoubtedly the core part. [0003] At present, there are two types of printed circuit board (PCB) image transfer equipment: traditional projection exposure equipment and laser direct imaging equipment (LDI). The graphics of the traditional projection exposure equipment have been printed on the film film, and the film film is irradiated with ultraviolet rays to transfer the figure to the PCB with a photosensitive dry film on the surface. After the dry film is exposed, the unexposed part of the dry film is dissolved by a chemical solution. In the laser direct imaging equipm...

AI Technical Summary

Problems solved by technology

Since the laser is focused on the dry film through an optical lens, when the focal plane is just on the surface of the dry film, the intensity of light received by the dry film is the strongest and the image is the clearest, so it is necessary to determine the position of the focal plane before exposure Whether it is on the surface of the dry film, if the focal plane is shifted (that is, commonly known as defocus), it will cause insufficient light intensity received by the exposure pattern on the dry film, and insufficient light intensity will lead to insufficient exposure of the dry film. Completely, after chemical development, it will be dissolved by the chemical solution or fall off due to the reduction of adhesion, which will seriously affect the image quality of the image.

[0004] At present, the commonly used focal plane detection method is to expose and develop the PCB covered with dry film, and then use a microscope to measure whether the actual circuit is consistent with the design value. If not, continue to adjust the distance from the optical path to the board surface, and repeat the exposure and development measurement. Until the optimal exposure focal plane is found, this detection method is cumbersome and time-consuming, and it is not accurate enough due to the measurement error of the microscope

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