With the continuous improvement of electronic communication technology, more and more traditional circuit board production methods have been far from meeting the rapid development of this era, some PCBA processing manufacturers on the quality of the circuit board is also increasingly high, want to really quickly produce high precision, good performance, and can save the cost of PCB circuit board, This is undoubtedly the biggest challenge for circuit design engineers today.
First: rapid production of circuit board method
Circuit board production and processing methods have a variety of, but the main production methods have physical methods and chemical methods of two categories:
Physical methods: By using a variety of tools and power tools, the board is manually carved off the unwanted copper.
Chemical method: By coating a blank copper sheet with a protective coating, the unnecessary copper is eroded away in a corrosive solution, which 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.
Paint by hand: Paint is painted on the blank copper coated plate by hand with a brush or a hard pen. After drying, it can be put into the solution for direct corrosion.
Sticker: There are various stickers on the market are made into strips and round sheets, and different stickers are combined on the blank circuit board according to the needs, which can be corroded after sticking.
Photographic film: the PCB circuit board is printed on the film through a laser printer, and the blank copper coated plate is coated with a layer of sensitive material in advance (there are already coated copper coated plates sold in the market). After exposure, development, fixing and cleaning in the darkroom environment, it can be corroded in the solution.
Thermal transfer printing: The circuit is printed directly on the blank circuit board by a thermal transfer printer, and then put into the corrosion solution.
Second: the advantages and disadvantages of the two methods of rapid fabrication of circuit boards
Physical method: This method is more laborious, and low accuracy, 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 method: The process is relatively complex, but the precision is controllable. It is the most widely used rapid plate making method at present, but there are still many problems.
(1) The printing accuracy depends on the accuracy of the printer cartridge used. 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, so it must be kept in all black and low temperature, and the exposure process must also be carried out in the darkroom.
(5) Silver salt (sensitive material) and copper salt (corrosion products) are toxic, the corrosion process should be very careful operation, stained with human or clothing is difficult to clean, and due to environmental protection reasons, the waste liquid treatment after corrosion is more troublesome
(6) etched out into the circuit board must use manual work, and manual punching to control accuracy is very difficult.
At present, electronic and digital products, automotive, medical and other products such as circuit board production requirements for the process and speed is relatively strict, so, as a circuit design engineer, must have a solid and solid circuit production foundation and skilled operating skills, and slowly accumulate and summarize.