In recent years, with the vigorous development of communications, electronics, automotive, medical and other industries, it has strongly promoted the development of the PCB industry. In the PCB production process, a large amount of waste gas will be generated, which needs to be effectively treated, otherwise it will cause serious pollution to the atmospheric environment. The PCB production process is complex, and the exhaust air volume and pollution factor concentration generated in each process are quite different, and it needs to be treated by quality and flow. The waste gas can be divided into the following categories.

1. Acidic Waste Gas  

This kind of waste gas is mainly produced in the process flow of inner layer pretreatment, horizontal PTH copper immersion wire, DVCP electroplating wire, gold immersion, inner layer etching, browning, dry film pretreatment, etc. Its main components are hydrogen chloride and sulfuric acid mist.

2. Alkaline Waste Gas 

This type of waste gas is mainly produced by alkaline etching and solder mask development process, and its main component is ammonia gas.

3. Cyanide-containing Waste Gas 

This type of exhaust gas is mainly produced by the gold immersion process, and its main component is hydrogen cyanide.

4. Organic Waste Gas (VOCs)

This type of waste gas is mainly produced by solder mask electrostatic spraying, solder mask pre-baking, text post-baking, inner coating, printing line, reflow oven tin spraying and other processes, and its main components are resin, organic solvent, ink, rosin oil, etc.

Acidic waste gas, alkaline waste gas and cyanide-containing waste gas are generally treated with scrubbers. The air unit collects the exhaust gas into the scrubber, so that the exhaust gas is in full contact with the washing liquid flowing on the surface of the filling to absorb the acid or alkaline dirt contained in the exhaust gas.

After washing, the waste liquid is collected in the sump, and then discharged to the wastewater system for treatment. The gas to be treated enters the circulating liquid through mass transfer and chemically reacts with the medicament in the circulating liquid to form salts that are easy to dissolve and hard to volatile, so that the gas is purified.

Organic waste gas is generally treated by activated carbon adsorption device. Taking advantage of the characteristics of activated carbon with developed internal pore structure and large specific surface area (1000~1200㎡/g), when organic waste gas passes through the fixed-bed activated carbon adsorption box, a certain component or some components in the waste gas can be attracted to the activated carbon The surface is concentrated on it. After the activated carbon is saturated, it can be replaced regularly (usually 3 months).