Common ten industries VOCs production waste sources and characteristics

I Electronics industry

Electronic product types mainly include electronic special materials, electronic components, printed circuit boards, semiconductor devices, display devices and optoelectronic devices, electronic end products six categories.

Electronic special materials

① Laminates

The production process of copper laminate is a waterless process, except for cooling water, inspection and testing department will produce a small amount of sewage, other production processes will not produce sewage. The production process produces pollutants mainly in the exhaust gas, more from the use of acetone, toluene and other organic solvents volatilization.

② Electronic copper foil

The main pollutants in the exhaust gas of electronic copper foil production are sulfuric acid mist and a small amount of benzene.

③ Quartz crystal bar (wafer)

A small amount of VOCs is generated from diesel volatilization during the cutting process of quartz crystal rods and wafers processing.

④ Resistive paste

The resistive paste mainly consists of three parts: conductive phase (functional phase), adhesive phase (glass phase) and organic carrier. The main pollutants in the production exhaust are VOCs and dust.

Electronic components

① Organic dielectric capacitors

VOCs are generated when the organic dielectric capacitor paper is painted and the surface of the capacitor is coated.

② Aluminum electrolytic capacitors

Aluminum electrolytic capacitors are polished during the production preparation stage, and a small amount of dust is generated when deburring the edges; hydrochloric acid gas is generated when the aluminum foil is corroded, and a small amount of dust is generated when cutting.

③ Tantalum electrolytic capacitors

VOCs are generated during the sintering process of tantalum electrolytic capacitors and when soldering anode and cathode leads.

④ Mica capacitors

VOCs exhaust gas is generated during the aging process in the production of mica capacitors.

⑤ Film Resistors

Film resistors are polished in the production preparation stage, and a small amount of dust is generated when deburring the edges; VOCs exhaust is generated from surface coating.

⑥ Glass Glaze Resistors

During the production of glass shaft resistors, VOCs exhaust is generated from the preparation of organic carriers, screen printing, drying and sintering, and lead-end welding.

(vii) Metal foil resistors

A small amount of VOCs is generated during the production of metal foil resistors in the process of gluing and applying foil.

(8) Inductors

VOCs are generated during material preparation of inductors, including anhydrous ethanol, acetone, and a small amount of xylene; exhaust gases and dust are generated during the soldering process.

⑨ Electronic transformer

Electronic transformers have VOCs in the process of dispensing and baking.

Semiconductor devices

① Discrete devices, integrated circuits

As the semiconductor process requires high cleanliness in the operation room, fans are usually used to extract all kinds of exhaust gases volatilized during the process, so the semiconductor industry exhaust emissions have the characteristics of large exhaust volume and small emission concentration. These exhaust gas emissions can be divided into four main categories: acidic gases, alkaline gases, organic exhaust gases and toxic gases.

Acid and alkaline emissions mainly come from diffusion, CVD, CMP and etching processes, which use acid and alkaline cleaning solutions to clean wafers. Currently, the most common cleaning solvent used in the semiconductor manufacturing process is a mixture of hydrogen peroxide and sulfuric acid. The exhaust gases from these processes include volatile gases from sulfuric acid, hydrofluoric acid, hydrochloric acid, nitric acid and phosphoric acid, etc. The alkaline gas is ammonia.

Organic waste gas mainly comes from lithography, development, etching and diffusion processes, in which organic solutions (such as isopropyl alcohol) are used to clean the wafer surface, and the volatile waste gas is one of the sources of organic waste gas: Meanwhile, the photoresist (photoresist) used in lithography and etching processes contains volatile organic solvents, such as butyl acetate, which are also volatilized into the atmosphere during the wafer processing process , is another source of VOCs exhaust generation.

Toxic emissions mainly come from crystal epitaxy, dry etching and CVD processes, in which a variety of high-purity special gases are used for wafer processing, such as silane (SiH4), phosphorane (PH3), carbon tetrafluoride (CF4), borane, boron trichloride, etc. Some of the special gases are toxic, asphyxiating and corrosive.

② Encapsulation

The exhaust gas generated by the encapsulation process is relatively simple, mainly acidic gas, epoxy resin and dust. The acidic exhaust gas is mainly generated from electroplating and other processes; baking exhaust gas is generated from the baking process after die attaching and sealing; the scribing machine generates exhaust gas containing trace sand dust during the wafer cutting process.

Display devices and optoelectronic devices

From the perspective of pollution, the representative products of display devices are TFT-LCD (thin film transistor liquid crystal display device), and the representative products of optoelectronic devices are LED optoelectronic devices.

Electronic terminal products

Potential pollutants from the electronic end product manufacturing industry are mainly tin and tin compounds, lead and lead compounds and VOCs (benzene and ethanol, isopropanol, acetone, etc.).

Pharmaceutical industry

The pharmaceutical process often requires the use of organic solvents for the separation and extraction of pharmaceuticals, so VOCs are one of the most important air pollutants in the pharmaceutical industry.

Fermentation

The exhaust gases from the production of fermented pharmaceuticals mainly include fermentation exhaust gas, solvent-containing exhaust gas, dust-containing exhaust gas, acid and alkali exhaust gas and malodorous gas from wastewater treatment devices. The main components of fermentation exhaust (including fermentation tank sterilization exhaust) are air and carbon dioxide, and contain a small amount of medium material and the smell of mycelium when bacteria start to produce antibiotics in the late stage of fermentation.

The organic solvent exhaust gas (such as toluene, ethanol, formaldehyde, acetone, etc.) from the production processes such as separation and extraction refining is the main source of organic exhaust gas pollution.

Chemical synthesis class

Chemical synthesis of the main sources of air pollution in pharmaceutical enterprises include: distillation, evaporation and concentration of organic non-condensable gas generated by the section; synthesis reaction, separation and extraction process generated organic solvent exhaust; the use of hydrochloric acid, ammonia to adjust the pH value of acid and alkali exhaust; crushing, drying emissions of dust; sewage treatment plant produces malodorous gas.

The main air pollutants of chemical synthesis process include inorganic substances such as particulate matter, hydrogen chloride and ammonia, as well as organic raw materials and organic solvents used in chemical synthesis, such as benzene, toluene, chlorobenzene, chloroform, acetone, aniline, dimethyl sulfoxide, ethanol, methanol, formaldehyde, etc.

Extraction class

The air pollutants in the extraction process mainly come from the dust generated during cleaning, crushing, drying and packaging; the solvents commonly used in the extraction section include water, dilute salt, dilute alkali, dilute acid, organic solvents (such as ethanol, acetone, trichloromethane, trichloroacetic acid, ethyl acetate, oxalic acid, acetic acid, etc.), and the volatilization of organic solvents is involved in the extraction, precipitation and crystallization processes, as well as in the acid digestion, alkaline digestion, isoelectric point In the process of acid digestion, alkali digestion, isoelectric point precipitation, pH mediation, etc., it also involves the volatilization of acid and base exhaust gas.

Bioengineering

The exhaust gas of bioengineering production process mainly comes from the use of solvents, including toluene, ethanol, propanol, acetone, formaldehyde and acetonitrile, etc. The main pollution producing points are the exhaust air of bottle washing, solvent extraction, peptide synthesizer, etc., as well as the exhaust air of laboratory and the drug dust in the preparation process. The fermentation process also produces a small amount of cellular respiratory gas, the main components of which are CO2 and N2.

Chinese medicine

Among them, the core process is extraction, separation and concentration of active ingredients. According to the different solvents, there are water extraction and solvent extraction, among which the solvent extraction is mainly ethanol extraction.

The exhaust gas of proprietary Chinese medicine production is mainly the drug dust generated from the process of crushing herbs and the volatilization of some VOCs used in the pharmaceutical process, such as ethanol, etc.

Formulation

The active ingredients and excipients are mixed, processed and formulated to form various dosage forms of drugs. Pharmaceutical preparations can be divided into solid formulations, injectables and other preparations by dosage form. Solid formulations and injections in the production process of exhaust gas pollution sources are mainly dust.