Generation Of Optical Drawing Data For Printed Circuit Boards

The basis of PCB board production is the film negative. When making a film plate in the early days, it was necessary to first make a film base map, and then use the base map for photography or reprinting. The accuracy of the base map must be consistent with that required by the printed board, and consideration should be given to compensating for deviations caused by the production process. The base map can be provided by the customer or made by the manufacturer, but the two parties should cooperate and negotiate closely so that it can not only meet the user's requirements, but also adapt to the production conditions. In the case that the user provides the base map, the manufacturer should inspect and approve the base map, and the user can evaluate and approve the original or the first printed board product. The base map production methods include manual drawing, texture mapping and CAD drawing. With the development of computer technology, the CAD technology of printed boards has been greatly improved, and the production technology level of printed boards has also been rapidly improved in the direction of multi-layer, thin wire, small aperture, and high density. The original film plate making process has been unable to To meet the design needs of printed boards, light painting technology emerged. Using the photoplotter, the PCB graphics data file designed by CAD can be directly sent to the computer system of the photoplotter, and the photoplotter can be controlled to draw graphics directly on the negative by using light. Then, after developing and fixing, a film negative is obtained. The printed board film plate made by light-painting technology has high speed, high precision and good quality, and avoids human errors that may occur when manually mapping or drawing base maps, greatly improving work efficiency and shortening the printed board. Production cycle. Using our company's laser photoplotter, the work that many people used to do for a long time can be completed in a very short time, and the thin wires and high-density plates drawn by it are unmatched by manual operations. According to the structure of the laser photoplotter, it can be divided into flat plate type, internal drum type (Internal Drum) and external drum type (External Drum). Yuzhiguang's series of photoplotters are all internationally popular outer drum type. The standard data format used by the light plotter is the Gerber-RS274 format, which is also the standard data format in the printed board design and production industry. The name of the Gerber format is a reference to the pioneer of the design and production of light plotters, the Gerber Company of the United States. The generation of light drawing data is to transform the design data generated by CAD software into light drawing data (mostly Gerber data), which is modified and edited by the CAM system to complete the light drawing preprocessing (imposition, mirroring, etc.), so that it can achieve Requirements for the production process of printed boards. Then, the processed data is sent to the photoplotter, which is converted into raster data by the raster image data processor of the photoplotter. .