Development and application of air clean (dust-free workshop, clean room) technology

2019-05-22 11:25:00   Editor: jushong shares    0

First, the concept of air clean technology


In scientific research, industrial production, and people's daily lives, it is often necessary to provide technical requirements for air temperature, humidity, cleanliness, and airflow velocity in a specific space, and to adopt certain technical means to create and maintain air in this space. Environment to meet the production process and human comfort requirements. This is what is commonly referred to as air conditioning. In buildings where air conditioning systems are used, the requirements for air temperature, humidity, cleanliness, and airflow speed are different due to different environmental conditions. In general, the focus of the air conditioning task is on the adjustment of air temperature, humidity and air speed, and there is no special requirement for air cleanliness. For some industrial production workshops, such as semiconductor, microelectronics, food, pharmaceutical, health and other fields, not only the environmental temperature, humidity, airflow speed have certain technical requirements, but more importantly, the air cleanliness ( That is, the concentration of dust in the production environment air has strict and special requirements. In order to achieve this, the technical measures taken are called air clean technology (commonly known as clean technology or purification technology). Therefore, the task of air cleaning technology is to remove the dust-containing suspended particles in the controlled environment air medium under the premise of meeting the indoor ambient air temperature and humidity requirements, and to meet the environmental conditions required for production, that is, we Often said air purification. A room (or a limited space) that uses air clean technology to control the concentration of suspended particles in the air and the concentration of bacteria to meet certain requirements is called a clean room.


Second, the origin of air clean technology


Air clean technology is a science gradually formed along with the development of science and technology and modern industry. Since the 18th century, people have had a preliminary understanding of clean technology. With the outbreak of international warfare, the development of military industry has been spurred, so higher requirements have been placed on the miniaturization, high precision, high purity, high quality and high reliability of products, which requires a high Clean production environment. Moreover, the more development of production technology, the higher the requirements for the cleanliness of the production environment. Therefore, air cleaning technology and the required equipment and filter materials are generated and rapidly developed.


In the 1920s, the United States first proposed the purification requirements of the production environment in the gyroscope manufacturing process of the aviation industry. In order to eliminate the pollution of airborne gears and bearings in the air, they established "control assembly" in the manufacturing workshop and laboratory. Zone" separates the assembly process of the bearing from other production and operation areas while supplying a certain amount of filtered air. The rapidly developing military industry requires a high-quality production environment, both in terms of improving the purity of raw materials, processing and assembling parts, and improving the reliability and service life of components and machines. It is said that a US missile company has found that when assembling an inertial guidance gyroscope in an ordinary workshop, it is necessary to reverse 120 times for every 10 products produced. When assembled in an environment that controls dust pollution in the air, the rework rate is reduced to two. Comparing the gyroscope bearings with a speed of 1200r/min in dustless and dusty (average diameter of dust particles is 3μm, dust particles is 1000pc/m3), the service life of the products is 100 times different. From these production practices, people recognize the importance and urgency of air purification in the military industry, and also constitute the driving force for the development of air clean technology at that time.


In the early 1950s, the United States invented and produced high-efficiency air particle filters, and achieved the first leap in clean technology, enabling the United States to establish a number of industrial clean rooms in the military industry and satellite manufacturing fields. It is widely used in aerospace, marine navigation devices, accelerators, gyroscopes, electronic instruments and other production plants.


At the same time as the rapid development of clean technology in the United States, the developed countries of the world have also begun research and application of clean technology.


In the 1950s, the United Kingdom established clean rooms in factories such as gyroscope production.


In the 1950s, Japan applied clean technology to the semiconductor industry.


In the early 1960s, when the US industrial clean room entered widespread use, it began to try to use the industrial clean room for biological aseptic experiments. Through research and experimentation, it has been recognized that bacteria and viruses in the air are attached to dust and exist in groups. Bacteria and viruses produced in the human body, other animal bodies, and soils may adhere to the air, dust, dander, hair, and water droplets. Thus, dust is the medium through which bacteria and viruses are transmitted. The more dust in the air, the more opportunities for the spread of bacteria and viruses. If the dust particles in the air are controlled and treated, the bacteria and viruses are controlled. On the basis of this theory, in the early 1970s, advanced technologies such as the United States used industrial clean room technology on a large scale to prevent air-borne microbial contamination, thus creating a modern biological clean room for the pharmaceutical industry. The quality of products in the cosmetics industry and the food industry has been greatly improved. In the operating room and special wards of the medical sector and biosafety, the promotion and application of clean rooms have ensured that disease treatment, surgery and anti-infection control are guaranteed.


It can be seen that the application of air purification technology can be divided into two aspects:


1. Industrial cleanliness. The air cleaning process for the purpose of industrial production processes is controlled by dust particles such as dust in the air. For such rooms, the main purpose is to control dust particles in the air, commonly referred to as industrial clean rooms.


2. Biological cleansing. The air cleaning process for the purpose of health and hygiene is controlled by particles such as bacteria and viruses in the air. For such rooms, due to the sterility treatment and the main purpose of preventing microbial contamination, it is often referred to as a biological clean room.


Third, the development of clean technology


Since the 18th century, people began to understand clean technology. In the 1920s, the United States applied to the military industry. Clean technology was developed along with the development of science and technology. With the application of clean technology, industrial products have also been continuously Improvement and progress. Its industrial products are developing towards miniaturization, precision, high quality, high purity and high reliability. This is especially true in modern industries, where aviation, aerospace, electronics, and medical, medical, and bioengineering applications are all applied. Especially for electronic, microelectronics, and integrated circuit products, from the initial installation in several rooms, to the miniaturization of large integrated circuits, the requirement for controlled particle size in air has grown from 0.3 to 0.5 μm to 0.05 μm. Even smaller, fully embodies the demand for clean technology in modern industry.


In the pharmaceutical industry, the quality of medicines is reflected in factors such as efficacy, safety and drug stability. The important link affecting these three elements is the formulation and production methods of the drug. The production method includes both production technology and production environment. The production environment is the result of a combination of measures for environmental control. Such as the construction and decoration of the pharmaceutical workshop, the design, operation, maintenance management of the air conditioning purification system. The purpose of environmental control is to prevent the occurrence of any product that threatens the quality of the product due to pollution or cross-contamination.


Clinical experience has shown that when used in intravenous injections and eye drops, which are contaminated by dust particles and enter human blood during the production process, the following symptoms may occur:


1. Some larger particle size particles enter the blood vessel with the drug solution, which may directly cause vascular obstruction, causing local water shortage and atrophy or edema;


2. If red blood cells accumulate on foreign matter such as invading particles, thrombosis may form, leading to vascular occlusion and phlebitis;


3. Microparticles invade tissue, which may also cause foreign body granuloma under the encirclement and cultivation of macrophages;


4. The interaction of foreign matter such as particles may cause symptoms such as allergic reactions and thrombocytopenia.


When the agent is contaminated by microorganisms in the production process, it will not only lead to a decrease in efficacy or deterioration of the drug, but also cause a disease that is unexpected in the clinic. For example, a polysaccharide produced by a microorganism causes a pyrogen reaction of a patient; a bacterial contamination drug may cause sepsis, endotoxin poisoning, and the like.


The clinical infections caused by the contamination of common pharmaceuticals such as tablets and powders in the production process have also been reported in foreign countries.


The hospital is a special occasion for patients to see, treat and recover, as well as a source of virus and bacteria. Infections and cross-infections in hospitals are associated with more patients and health care workers. The global SARS (commonly known as SARS) infection that occurred in the spring of 2003 illustrates the importance of taking control of the air environment in hospitals.


Based on the importance of applying air clean technology, the development of clean technology has become an indispensable indicator of modern industrial production and scientific experiment activities.


If the widespread application of clean technology in developed countries such as the United States and Europe in the 1960s is a period of great development of clean technology, then clean technology will be developed rapidly and in all areas of the world.


In 1961, the United States established the earliest clean room standard in the world (US Air Force Technical Order 203). The task of preparing federal government standards was handed over to the Atomic Energy Commission's publishing agency. At the same time, the one-way flow clean technology was basically improved, and a Class 100 clean room was built.


At the end of 1963, the United States issued the first federal standard FS-209 for the military component. Since then, the federal standard "209" is not only the famous clean technology standard in the United States, but also the universal clean technology standard.


In 1966, the United States issued the revised FS-209A.


In 1973 the United States promulgated the federal standard FS-209B;


In 1976, the United States revised the federal standard FS-209B;


In 1988 the United States issued the federal standard FS-209D;


In 1992, the United States issued the federal standard FS-209E.


During this period, the former Democratic Germany, France, the former Soviet Union, Japan, the United Kingdom, Australia, Russia and other countries have successively promulgated and formulated the clean technical standards and the Good Manufacturing Practices (GMP) of each country.


Table 0-1 Cleanroom standards promulgated by some countries in the world


Announcement time

National standards

1961.3

US Air Force Technical Order TO.00-25-203

1963.7

US Air Force Technical Directive TO.00-25-203 First Revision

1963.12

US Federal Standard FS-209

1964

(former) Soviet standard (weighting method)

1965.8

US Air Force Technical Directive TO.00-25-203 Second Revision

1965

(former) Soviet standard CH317-65 (counting method)

1966.6

Federal German Standard

1966.8

US Federal Standard FS-209A

1967.8

National Aeronautics and Astronautics Administration NASA Standard NHB5340.2

1968

Democratic German Standard

(Continued)

1972

French standard ASPEC Communication 7202

1973.4

US Federal Standard FS-209B

1973

(former) Soviet standard OCT11II-170-050.001-73

1975

Japanese Industrial Standard B9920

1976.5

US Federal Standard FS-209B Revision

1976,1977

Federal German Standard VDI 2083

1976

British standard

1976

Australian Standard

1987.10

US Federal Standard FS-209C

1988

Japanese industrial standard JIS B 9920 clean room aerosol measurement method and clean room cleanliness evaluation method (amendment)

1988

Japan Air Cleansing Association Standard

1988.6

US Federal Standard FS-209D

1992.11

US Federal Standard FS209E

1996

Russian standard GOSTR 50766-95

1999.5

International standard ISO 14644-1

Table 0-2 Quality Control Practices for Pharmaceutical Production (GMP) promulgated by some countries, regions and organizations in the world

Announcement time

Promulgated countries, regions, organizations

1973

Japanese Pharmaceutical Production Quality Management Regulations (JGMP)

1983

UK Pharmaceutical Production Quality Management Practice (Orange Guide)

1984

Canadian Good Manufacturing Practice

1984

Korean pharmaceutical production quality management practices

1985

China Pharmaceutical Production Quality Management Regulations

1988

ASEAN Pharmaceutical Production Quality Management Regulations (ASEAN GMP)

1989

China Veterinary Drug Production Quality Management Regulations (Trial)

1990

Pharmaceutical Production Inspection Mutual Recognition of the Convention's Good Manufacturing Practices (PIC GMP)

1990(Revision)

"Good Pharmaceutical Manufacturing Standards" in Taiwan, China

1991

US Current Good Manufacturing Practice (CFR GMP)

1991

US FDA Biotechnology Inspection Guide

1991

US FDA API inspection guide

1992

World Health Organization Good Manufacturing Practice (WHO GMP)

1992

European Community Good Manufacturing Practice (EEC GMP)

1992(Revision)

China Pharmaceutical Production Quality Management Regulations

1997

European Union Good Manufacturing Practice (EU GMP)

1998(Revision)

China Pharmaceutical Production Quality Management Regulations

China's clean room technology research began in the early 1960s. In the 1970s, clean room technology was mainly used in China's electronics industry, especially in the clean room of semiconductor integrated circuit production. A number of clean workshops were built and successfully developed. (100 grade), 6 grade (1000 grade) one-way flow industrial clean room and surgical clean room.


Although clean technology research started late in China, it has developed rapidly. Not only has the theory of clean technology been gradually improved, but also the equipment and materials used in clean workshops, such as high-efficiency filters, clean benches, laminar flow hoods, air shower rooms, and clean transfer windows, have been successfully developed and put into production. By the end of the 1970s, the development of clean room design, construction and clean technology in China was at a mature stage.


In 1984, China promulgated the national standard "Code for Design of Clean Plants" (GBJ73-1984);


In 1991, the industry standard "Code for Construction and Acceptance of Cleanrooms" (JGJ7190) was issued;


In 1994, the Laboratory Animal Environment and Facilities was promulgated (GB/T14925-1994);


In 1996, the State Administration of Medicine promulgated the "Code for the Design of Cleanrooms for the Pharmaceutical Industry" (GMP-97);


In 2001, the original "Code for Design of Clean Plants" (GBJ73-1984) was revised, and a new national standard "Code for Design of Clean Plants" (GB50073-2001) was promulgated;


In 2002, the national standard "Building Technical Specification for Hospital Cleansing Department" GB50333-2002 was promulgated;


The completion of high cleanliness clean rooms and the promulgation of technical specifications have marked the beginning of a new stage in the development of clean technology in China.


Fourth, the application of clean technology


The wide application of clean technology in countries around the world has experienced more than half a century of development, from the military industry to the electronics industry, and gradually developed into other industries, its application range is more and more extensive, and technical requirements are getting higher and higher, application The field has been involved in military, electronics, food, medicine, health, biological experiments and so on.


1. Electronic (microelectronics) industry


The electronics industry has evolved from past tubes to semiconductor discrete devices, integrated circuits and even very large scale integrated circuits. Therefore, it has greatly promoted the development of air cleaning technology. It has been proved that in integrated circuit manufacturing processes, the higher the integration, the larger the graphic size. Fine, the smaller the particle size of the air dust particles controlled by the clean room, and the lower the dust content in the air. Table 0-3 shows the process development of large-scale integrated circuits. Table 0-4 shows the development of VLSI and the particle size of the corresponding control particles.


The yield of the finished chip is related to the defect density of the chip. The defect density is related to the number of dust particles in the air. If it is assumed that 10% of the chip defect density is caused by the deposition of dust particles in the air onto the silicon wafer, the maximum allowable value of airborne dust particles per square meter of chip can be derived, as shown in Table 0-5. Therefore, the rapid development of integrated circuits not only has higher requirements on the size of the control particles in the air, but also has control requirements on the number of dust particles, that is, the air cleanliness level of the production environment has control requirements. In addition, the integrated circuit production environment also has very strict requirements for chemical pollution control, as shown in Table 0-6.


Table 0-3 Process development status of large-scale integrated circuits


years


Process characteristics


1980

1984

1987

1990

1993

1996

1999

2004

Wafer diameter / mm

75

100

125

150

200

200

200

300

DRAM technology

64K

256K

1M

4K

16M

64M

256M

1G

Feature size / μm

2

1.5

1

0.8

0.5

0.35

0.25

0.20.1

Process steps

100

150

200

300

400

500

600

700800

Cleanliness level

1000-100

100

10

1

0.1 μm

0.1 μm

0.1 μm

0.1 μm

Table 0-4 Development of VLSI and corresponding control of particle size

Production year


project


1997

1999

2001

2003

2006

2009

2012

Integration (DRAM)

256M

1G

1G

4G

16G

64G

256G

Line width / μm

0.25

0.18

0.15

0.13

0.10

0.07

0.05

Control particle diameter / μm

0.125

0.09

0.075

0.065

0.05

0.035

0.025

Table 0-5 Maximum allowable values of airborne dust particles per square meter of chip

Integration


Yield Y (%)


64M

256M

1G

4G

16G

64G

90

55

38

25

16

11

8

80

124

84

56

37

24

7

70

195

132

Control particle size / μm

0.035

0.025

0.018

0.013

0.01

0.007

Table 0-6 Chemical Contaminant Control Indicators

years


project


1995

19971998

19992001

20032004

20062007

20092010

DRAM integration

64M

256M

1G

4G

16G

64G

Line width / μm

0.35

0.25

0.18-0.15

0.13

0.10

0.07

Wafer diameter / μm

200

200

300

300

400450

400450

Controlled particle size / μm

0.12

0.08

0.06

0.04

0.03

0.02

Number of particles (gate cleaning) / (pc / m2)

1400

950

500

250

200

150

Heavy metal (Fe) / (atoms / cm2)

5×1010

2.5×1010

1×1010

5×109

2.5×109

2.5×109

Organic matter (C) / (atoms / cm2)

1×1014

5×1013

3×1013

1×1013

5×1012

3×1012

2. Food industry


The processes of the food industry mainly include fermentation, brewing, processing, potting, and packaging. In these processes, clean sterilization of air is one of the keys to ensuring product quality. For example, in the process of potting and packaging, if the packaging container is not completely sterilized and has bacteria, the shelf life of the food will be shortened, which will affect the health of the consumer.


Practice has proved that we must not only pay attention to the sterilization of food contents and filling containers, but also not to despise air pollution. The pollution of air generally comes from two aspects. First, the air that enters the room from the outside is not purified, and has a large amount of microorganisms. On the other hand, on the ground, walls and ceiling of the food processing workshop, because of the sugar, starch, protein and other particles, when the temperature and humidity are suitable, the bacteria will multiply on these surfaces and blow away with the air flow. Every corner of the room. Therefore, the food production process requires aseptic processing.


The aseptic operation of food production is not only the impact of the product's anti-corrosion and shelf life, but more importantly, the air-cleaning technology in the production of food, especially in the brewing, fermentation, pure breeding, isolation, inoculation, expansion of yeast And to prevent contamination of the bacteria, improve product quality and maintain food in color, fragrance, taste, nutrition and other aspects have an important role.


3. Medical


As mentioned earlier, in the special environment of the hospital, it is very important to control the air environment. The so-called control of the air environment includes two aspects, one of which is to improve the comfort of the environment. A comfortable air conditioning environment is an important factor in treatment and rehabilitation, and in some cases, even the main treatment. A large number of medical clinical studies have shown that patients in a suitable air-conditioned environment usually recover faster than in a non-controlled environment. For example, a relatively dry and suitable air temperature can prevent a surgical or traumatic patient from infecting the wound due to sweating of the skin. On the other hand, through the control of the air environment, the spread of viruses and bacteria can be prevented, especially in certain special wards, such as operating rooms, leukemia treatment rooms, burn wards, and organ transplant wards.


4. Biological experiment


In genetic engineering, pathological testing, cell tissue culture, vaccine culture, etc., it is often necessary to operate in a sterile and dust-free environment. On the one hand, the test piece is not contaminated by other microorganisms to ensure the accuracy of the experiment. It is required that the materials studied, such as viruses, high-risk pathogens, and radioactive materials, do not overflow, to prevent harm to the operator's health and environmental pollution. For such experimental clean rooms, in addition to the necessary setup requirements for general clean rooms, two levels of isolation are required. The first level usually uses biosafety cabinets to isolate workers from dangerous specimens such as pathogens; the second level isolates the experimental area from other environmental areas. At the same time, the laboratory is under negative pressure.


5. Experimental animal breeding


For the needs of clinical trials, some hospitals or research institutes often set up experimental animal breeding houses of a certain scale, and raise certain experimental animals for testing medical devices, surgical procedures, pharmaceutical preparations, etc. used in human body. Monitor its safety. In experimental animals, the control of microorganisms is particularly important and is also a means of studying their effects on human health. If the experimental animal is infected with a pathogenic microorganism, virus or parasite, it may cause all trials to fail. Therefore, environmental factors affecting the experimental animal housing, such as air temperature, humidity, air velocity, microbes and dust particles, must be controlled according to animal species and facility environment requirements.


Air clean (dust-free workshop, clean room) technology is also widely used in aerospace, instrumentation, precision machinery manufacturing and other production industries.


Guangdong Yuhong Technology Co., Ltd. was established in 2016 by Shenzhen Kebiao, Dongguan Liren and Dongguan Antai, with a registered capital of 100 million yuan. Shenzhen Kebiao Purification Equipment Co., Ltd. was established in 1999. With years of industry accumulation and precipitation, it has developed into a clean room system full industrial chain group company covering three major business segments: material production, equipment production, intelligent control and engineering installation. . In 2018, the group completed a total sales of 700 million yuan.


The group has 1,062 employees, including 113 R&D and engineering technicians, 249 production, management and sales personnel, and 700 engineering installers. In Shenzhen Nanshan Science and Technology Park, 2200m2 of high-quality office buildings were purchased, and Dongguan Tangxia built 13000m2 industrial park. The professional production of industrial clean industry supporting high-end sheet production capacity of 2 million m2, clean equipment FFU annual output of 60,000 units, and the establishment of South China's first wind tunnel laboratory in line with the US AMCA ventilation standards. Fully integrate the clean room industry chain system, set up a group research center, and continuously innovate and develop new products and processes of clean systems. Subsidiary Shenzhen Kebiao has the qualifications of the State Construction Department to award the architectural decoration engineering design B, the architectural decoration and decoration engineering contractor grade, the mechanical and electrical installation and the steel structure. It is the overall builder of the large industrial clean room in China. Professional construction of high-grade industrial clean room and air pressure, vacuum, special gas, ultra-pure gas, process exhaust, pure water, process cooling water, wastewater, electricity, weak electricity, monitoring, fire protection, chemical supply and secondary distribution systems engineering. Future Group will focus on the development, production and sales of clean room construction and supporting materials and products in industrial electronics, flat panel display, precision instruments, biomedicine, medical and health industries.


"Care on the ground, professional integrity" is the company's business philosophy and core values that have been upheld for 20 years. The company's vision is to grow into the most competitive clean room system in China.