With the continuous improvement of electronic communication technology, more and more traditional circuit board manufacturing methods have been far from meet the rapid development of this era, want to really fast production of high-precision, good performance, and can save the cost of the circuit board, this is undoubtedly the biggest challenge for PCB circuit design engineers.
First, PCB rapid board making method
There are a variety of manufacturing and processing methods of circuit boards, but the main manufacturing methods are physical PCB board method and chemical PCB board method of two categories:
Physical PCB board method: By using a variety of cutting tools and power tools, the unnecessary copper on the circuit board is engraved by hand.
Chemical PCB method: By coating a blank copper coated plate with a protective layer, in a corrosive solution to remove unnecessary copper, is currently used by most developers. There are a variety of methods to cover the protective layer, including the most traditional manual paint method, paste custom self-adhesive method, film sensitive method and recently developed thermal transfer printing PCB board method.
There are several methods to cover the protective layer of PCB chemical board:
1, manual painting paint: paint with a brush or a hard pen on the blank copper coated plate manually depict the shape of the line, after drying can be put into the solution directly corrosion.
2, Paste adhesive: there are a variety of adhesive on the market is made into strips and round sheets, in the blank circuit board according to the need to combine different adhesive, sticky can be corroded.
3. Film sensitization: the PCB circuit board is printed on the film by laser printer, and the blank copper coated plate is pre-coated with a layer of sensitive material (there are already coated copper coated plate for sale on the market), which can be corroded in the solution after exposure, development, fixing and cleaning in the darkroom environment.
4, heat transfer printing: through the heat transfer printer to print the line directly on the blank circuit board, and then put into the corrosion liquid corrosion.
Two, the advantages and disadvantages of two kinds of rapid PCB board making methods
Physical PCB board method: This method is more laborious, and low precision, only relatively simple lines can be used. The main shortcomings are time-consuming, precision is not easy to control and there is no recovery, the operation requirements are very high, so few people have adopted.
Chemical PCB board making method: the process is relatively complex, but the precision is controllable. It is the most widely used rapid board making method at present, but there are still many problems.
PCB chemical board production has the following problems:
1, printing accuracy depends on the accuracy of the printer cartridge. Poor performance of the printer to print out uneven lines, corrosion process is easy to cause line break, adhesion.
2, the exposure and development time of the photographic plate is not easy to control, and the best exposure time of each batch of plates will be different, need to be mastered through repeated tests.
3. The control difficulty of the corrosion process is high: it is impossible for a single corrosion board to be equipped with professional control equipment used in mass production of the circuit board factory, and the temperature, concentration and pH of the corrosion solution will have a great impact on the corrosion quality. Want to do a piece of circuit board, must have a lot of experience. Otherwise, the material scrap is very serious.
4. The photosensitive plate has a high requirement on the environment and must be kept in all black and low temperature. The exposure process must also be carried out in the darkroom.
5, silver salt (sensitive material) and copper salt (corrosion products) are toxic, corrosion process operation should be very careful, stained with human or clothing is difficult to clean, and due to environmental protection reasons, after corrosion waste liquid treatment is more troublesome.
6, etched out of the finished plate must be manually worked, and manual punching to control the accuracy is difficult.
Three, PCB quick board summary
At present, electronic and digital products, automobiles, medical products and other products such as circuit board production requirements for the process and speed is relatively strict, so, as a PCB circuit design engineer, must have a solid and solid circuit production foundation and skilled operation skills, and slowly accumulate and summarize.