PCB design cheats: teach you how to quickly make circuit boards

The circuit board is the carrier to realize the function of the electronic circuit. As a circuit design engineer, have you encountered such a problem in the product design and development stage: With the increase of the frequency of electronic communication, the requirements for the accuracy of the PCB circuit are getting higher and higher , the choice of the best makes the product reliability requirements higher and higher. R & D projects need to be repeatedly demonstrated and modified, and the electronic product R & D cycle is getting shorter and shorter. Circuit design engineers have to face higher challenges, how to quickly produce circuits in the shortest time Board, shortening project development time has become one of the keys to success.

The traditional rapid production circuit board method

Although there are many methods for making and processing circuit boards, the traditional fast board-making methods can be mainly divided into two categories: physical methods and chemical methods:

Physical method: By using various knives and electric tools, the unnecessary copper on the circuit board is carved away by hand.

Chemical method: By covering the blank copper clad laminate with a protective layer, the unnecessary copper is etched away in a corrosive solution, which is the method currently used by most developers. There are many ways to cover the protective layer, mainly including the most traditional manual painting method, pasting custom self-adhesive method, film photosensitive method, and the thermal transfer printing PCB board method that has only been developed in recent years.

Manual painting: Use a brush or a hard pen to manually trace the shape of the circuit on the blank copper clad board. After drying, it can be put into the solution for direct corrosion.

Adhesive stickers: There are various stickers on the market that are made into strips and discs. Combine different stickers on blank circuit boards according to needs, and they can be corroded after sticking.

Photosensitive film: Print the PCB circuit board diagram on the film through a laser printer, and pre-coat a layer of photosensitive material on the blank copper-clad board (there are coated copper-clad boards for sale in the market), expose, develop, fix, and clean in a darkroom environment After that, it can be etched in the solution.

Thermal transfer printing: The circuit is directly printed on a blank circuit board by a thermal transfer printer, and then etched in an etching solution.

The two methods of quickly making circuit boards also have their own advantages and disadvantages:

Physical method: This method is laborious and has low precision, and can only be used for relatively simple circuits. The main disadvantages are labor-intensive and time-consuming, the accuracy is not easy to control, and there is no recovery. It has high requirements for operation, and few people have adopted it so far.

Chemical method: The process is relatively complicated, but the precision is controllable. It is currently the most widely used method for rapid plate production, but there are still many problems.

a. Printing accuracy depends on the accuracy of the printer cartridges used. The lines printed by the printer with poor performance are uneven, and it is easy to cause disconnection and adhesion during the corrosion process.

b. The exposure and development time of photosensitive plates are not easy to control, and the optimal exposure time of each batch of plates will be different, which needs to be mastered through repeated experiments.

c. The control of the corrosion process is difficult: it is impossible for a single-chip corrosion board to be equipped with professional control equipment for mass production in circuit board factories, and the temperature, concentration, and pH of the corrosion solution will have a greater impact on the corrosion quality. If you want to make a good circuit board, you must have many times of experience accumulation. Otherwise, material scrap is very serious.

d. Photosensitive plates have high requirements on the environment and must be stored in complete darkness and low temperature conditions, and the exposure process must also be carried out under darkroom conditions.

e. Both silver salt (photosensitive material) and copper salt (corrosion product) are toxic, and the operation must be very careful during the corrosion process. It is difficult to clean if it is stained with people or clothes, and due to environmental protection reasons, it is troublesome to dispose of waste liquid after corrosion.

f. The etched finished board must be processed by hand, and it is difficult to control the accuracy of manual drilling.

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