1 physical and chemical aspects
1) etching liquid concentration: type of structure should be based on the principle of metal corrosion and copper by test method to determine the concentration of etching solution, it should have greater choice in reference to a wide range of technology.
2) Etchant chemical composition: Etchant chemical compositions are different, the etch rate is not the same etching coefficient is also different. Such as the widespread use of acid etching coefficient of cupric Chloride etchant is typically &; alkaline cupric Chloride etchant coefficient may reach 3.5-4. Is in the development stage with nitric acid etching solution can be achieved almost no corrosion problems, etched wire wall close to the vertical.
3) temperature: temperature effects of etching solution properties of large, usually in the process of chemical reaction temperature on the fluidity and speed up the solution of reducing the viscosity of etching solution, increase the etch rate plays an important role. But the temperature is too high, can easily lead to etching liquid chemical components in volatile, causing Etchant chemical imbalance, and high temperature, may create resistance of polymers
Corrosion damage and affect the life of etching equipment. Therefore, etching liquid temperature control within a certain range.
4) using the copper foil thickness: thickness of copper foil circuit wire density plays an important role. Thin copper foil, etching time is short, lateral erosion is small and vice versa, lateral erosion is very big. Therefore, must be based on technical requirements and circuit wires wire precision and density requirements, to select the thickness of copper foil. While copper elongation, crystal structure, and so on, you will have direct effects on the etching properties.
5) geometry of the circuit: the circuit conductors in the x-direction and y-direction if unevenly distributed, will directly affect the etching solution in PCB on the flow velocity of the plate surface. If at the same intervals narrowest wire on the PCB Board part States wide wire parts and interval, interval width of wire distribution of parts, etching will be excessive. Therefore, this requires the designers at design time, you should first understand the technical feasibility, as far as possible the entire PCB circuit board surface evenly distributes, and the thickness of the wire should be aligned as far as possible. Especially in production of multilayer printed circuit board, the large area of copper as the ground floor, has a great impact on the quality of the etching, it is recommended that design into a Web.
2 mechanical aspects
1) device type: equipment structures are Etchant properties of one of the most important factors of influence. Initial stage of immersion tank immersion method, etched wire width of printed circuit boards, accuracy is not high, we can use the device structure. For fine wire, and narrow spacing, precision high, and density high of printed circuit board for, immersion type of etched equipment structure has not adapted, appeared level mechanical drive structure form of etched equipment and used swing spray Tsui device, makes base Board of copper surface printed circuit etched more uniform, but level type equipment structure will caused PCB Board surface of had corrosion phenomenon, thus development and development has vertical spray got technology. Meanwhile, etching equipment must have to prevent thin in etching, the CCL is wound on rollers and waste caused by the transport wheel device, and line graph metal abrasions or scratches on the surface. So, in choosing etching equipment, with special emphasis on structure, can achieve faster etching rates, uniform etching etching and high quality requirements.
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