**Firstly, methods for rapid manufacturing of circuit boards**
There are many methods for manufacturing and processing circuit boards, but they mainly include physical and chemical methods:
Physical method: Manually carve unwanted copper layers on circuit boards using various cutting tools and power tools.
Chemical method: Cover a protective layer on a blank copper-clad laminate and etch off excess copper layer through a corrosive solution. This method is currently used by most developers. There are many methods to cover the protective layer, including the most traditional manual painting method, self-made self-adhesive method, photosensitive film method, and the recently developed PCB heat transfer printing method.
**Paint by Hand:** Use a brush or a hard pen to manually draw the circuit design on a blank copper-clad laminate. After the drawing is complete, allow it to dry, then immerse it in a corrosive solution to etch the circuit.
**Adhesive Stickers:** Various types of stickers, available in strips or discs, can be applied to a blank circuit board. After adhering the stickers according to the desired pattern, place the board in a corrosive solution to etch the circuit.
**Film Photosensitive:** Print the PCB circuit design onto a film using a laser printer. Apply a layer of photosensitive material to the blank copper-clad laminate (pre-coated laminates are available commercially). Expose, develop, fix, and clean the laminate in a darkroom environment before etching it in a corrosive solution.
**Thermal Transfer:** Directly print the circuit design onto the blank circuit board using a thermal transfer printer. Subsequently, immerse the board in a corrosive liquid to etch the circuit.
**Second: The Advantages and Disadvantages of Two Rapid Circuit Board Production Methods**
**Physical Method:** This approach is labor-intensive and has low accuracy, suitable only for relatively simple designs. Its main drawbacks include significant labor and time requirements, difficulty in controlling accuracy, and irrecoverability. It demands high skill levels, and its adoption is currently limited.
**Chemical Method:** Although more complex, this method offers controllable precision and is the most widely used rapid plate-making technique today. However, it has several issues:
1) **Printing Accuracy:** The quality of the circuit design depends on the printer cartridge’s accuracy. Poor-performing printers can produce uneven lines, leading to disconnections and adhesion problems during the etching process.
2) **Exposure and Development Time:** Controlling the exposure and development time of photosensitive plates is challenging. The optimal exposure time varies with each batch, requiring repeated trials to perfect.
3) **Corrosion Process Control:** Achieving consistent quality in the corrosion process is difficult without the professional equipment used in mass production. Factors such as temperature, concentration, and pH of the corrosive solution significantly impact the quality of the etching. Accumulating experience is crucial to minimize material waste.
4) **Environmental Requirements:** Photosensitive plates require storage in complete darkness and low temperatures, and the exposure process must occur in a darkroom.
5) **Toxicity:** Both silver salts (photosensitive material) and copper salts (corrosion products) are toxic. Caution is needed during the corrosion process, and cleaning up spills from people or clothing can be challenging. Additionally, disposing of the waste liquid is problematic due to environmental concerns.
6) **Manual Processing:** The finished etched board requires manual post-processing, making it difficult to achieve accurate results with hand-punched holes.
Currently, circuit board production for electronic digital products, automobiles, and medical devices demands high precision and speed. Therefore, as a circuit design engineer, it is essential to have a robust foundation in circuit production and proficient operating skills, developed through extensive experience and practice.
