An Introduction
People talk about the development trend of PCB, the PCB is often thought of moving high-precision, high density and reliability direction, which is the development trend. On the other hand, the appearance of the user requirements of the PCB more strict. PCB solder mask is like a "coat", in addition to requiring a certain degree of thickness and hardness, solvent resistance test and adhesion test standard, but also requires the surface color of uniform, shiny (general requirements for domestic rooms the brighter the better), the surface no garbage, no extra marks. We can say that the appearance of solder resist is not only a good or bad quality of enterprise technology and management level of expression, but also directly affect the "order." Therefore, how to improve the appearance of printed circuit board solder quality has become the PCB plant need to be addressed for each subject. According to my practical experience following from the solder resist printing, exposure, developing and post-cured in four areas to talk about how to improve their appearance.
Affect the quality of the appearance of two factors solder resist
1, screen:
Photosensitive solder mask of the screen printing process, the flatness of the blade, clean the environment between the degree of screen printing, screen printing, when used close up tape and ink formulation, printing pressure, pre-screen appearance of the brush plate and so will the quality of impact. According to the actual situation of production, the most influential factor is the first three. Scraper is not easy to solder flat surface scraper marks; screen cleaning is not enough room in the solder surface is easy to waste; close up tape improper use, easy to make plastic dissolved in solvent ink resulting surface compounds.
2 Exposure:
Solder mask exposure process, because solder has not completely cured, solder and solder resist film prone to stick together when the imprint, which is affecting the quality of the main reasons for the appearance of solder resist.
3, developing:
The current level of solder mask imaging commonly used transmission-type imaging, the solder has not completely cured, imaging machine drive wheel, roller and so easy to damage its surface, resulting in roll mark, thus affecting the appearance quality of solder resist. In addition, incorrect exposure will also affect the energy of the solder resist gloss, but this can be controlled through the wedge table.
4, after the curing
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After the curing temperature of the solder resist non-uniform color likely to cause uneven solder resist, even when the temperature is too high, resulting in local yellow, black, affecting the appearance of solder resist.
Conclusion
To improve the appearance of printed circuit board solder quality is required from the process methods, materials, equipment, operator of integrated process control and other aspects of discipline, in particular, be on the screen, exposure, developing, after the curing process of the parameters strict monitoring.
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2011年9月2日星期五
Petrochemical construction and efficient welding technology and the current situation
Visit to China National Petroleum Offshore Engineering Company Zhijian Senior Engineer
As competition intensifies, the prices of petroleum, petrochemical construction cycle is short and efficient welding technology, equipment and materials applications is the trend. But efficient welding technology, equipment and materials in petroleum, chemical construction applications, there are still many problems. The following combination of specific projects to talk about the efficient application of welding technology and practical needs, necessity and importance.
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First, the offshore oil project in the construction of large marine structures. The weight of large offshore oil steel, structure and size of offshore oil development with increasing water depth, marine structures has been increasing, the volume of structures and the use of the plate thickness is increasing. With the rise in steel prices and offshore structures, offshore installation capacity requirements, the application of high strength steel is also a large area using, so that you can reduce the amount of steel. Small marine structures using materials mostly 355MPa even lower intensity level of the material, large-scale structure of 420MPa steel for offshore platforms is increasing the use of proportion. In addition, with the plate thickness increases, bringing a large number of post weld heat treatment of the workload. For example, the offshore platform jacket of a 95mm, φ3750mm ring weld, using double-sided groove (groove depth of 1 / 3, outside the groove depth of 2 / 3), weld metal weight of nearly 271kg, so the use of efficient welding technology, equipment, welding technology and high-performance materials (eliminating weld annealing treatment) is inevitable. Solve the above problem, from two aspects: First, the use of efficient submerged arc welding, the waveform control technology, dual-wire submerged arc welding system (U.S. Lincoln's products); the other hand, high strength, high toughness welding material through the evaluation of weld toughness CTOD test, the abolition of annealing after welding, thus shortening the construction cycle of marine structures.
Secondly, a large LNG storage tank construction. Large LNG storage tank for the 9Ni steel base metal. The material in the welding parameters welding requires very strict, welding heat input is small, low-temperature layer, which doomed the welding of low efficiency. Therefore, LNG girth welding using submerged arc welding in the horizontal welding, and welding and the use of both sides of the same side welding backing forming welding submerged arc process, using AC square-wave high-efficiency submerged arc welding machine and other new technologies, can effectively improve the welding efficiency.
At present, China Petroleum and Chemical efficient welding technology gap with foreign countries than not, the new welding equipment, welding and welding materials in the same starting line. Because the current structure in the marine LNG storage projects and large-scale projects using welding equipment and welding materials are mostly imported, welding technology and welding auxiliary facilities with foreign companies is not much difference. But the most crucial question is: those in the field of welding equipment and welding materials and more dependent on imports, our own production equipment and welding materials can not meet the industry's production requirements, but also our welding equipment and welding materials businesses to work together.
Our company is an offshore steel construction companies, hope that China's welding business with foreign companies to develop a very technical level, even higher level of technology of welding equipment and welding materials, welding technology reduces the high dependence on foreign .
keywords: Aluminium Welding Wire, Nickel Welding Rod, Copper Alloy Welding Wire
As competition intensifies, the prices of petroleum, petrochemical construction cycle is short and efficient welding technology, equipment and materials applications is the trend. But efficient welding technology, equipment and materials in petroleum, chemical construction applications, there are still many problems. The following combination of specific projects to talk about the efficient application of welding technology and practical needs, necessity and importance.
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First, the offshore oil project in the construction of large marine structures. The weight of large offshore oil steel, structure and size of offshore oil development with increasing water depth, marine structures has been increasing, the volume of structures and the use of the plate thickness is increasing. With the rise in steel prices and offshore structures, offshore installation capacity requirements, the application of high strength steel is also a large area using, so that you can reduce the amount of steel. Small marine structures using materials mostly 355MPa even lower intensity level of the material, large-scale structure of 420MPa steel for offshore platforms is increasing the use of proportion. In addition, with the plate thickness increases, bringing a large number of post weld heat treatment of the workload. For example, the offshore platform jacket of a 95mm, φ3750mm ring weld, using double-sided groove (groove depth of 1 / 3, outside the groove depth of 2 / 3), weld metal weight of nearly 271kg, so the use of efficient welding technology, equipment, welding technology and high-performance materials (eliminating weld annealing treatment) is inevitable. Solve the above problem, from two aspects: First, the use of efficient submerged arc welding, the waveform control technology, dual-wire submerged arc welding system (U.S. Lincoln's products); the other hand, high strength, high toughness welding material through the evaluation of weld toughness CTOD test, the abolition of annealing after welding, thus shortening the construction cycle of marine structures.
Secondly, a large LNG storage tank construction. Large LNG storage tank for the 9Ni steel base metal. The material in the welding parameters welding requires very strict, welding heat input is small, low-temperature layer, which doomed the welding of low efficiency. Therefore, LNG girth welding using submerged arc welding in the horizontal welding, and welding and the use of both sides of the same side welding backing forming welding submerged arc process, using AC square-wave high-efficiency submerged arc welding machine and other new technologies, can effectively improve the welding efficiency.
At present, China Petroleum and Chemical efficient welding technology gap with foreign countries than not, the new welding equipment, welding and welding materials in the same starting line. Because the current structure in the marine LNG storage projects and large-scale projects using welding equipment and welding materials are mostly imported, welding technology and welding auxiliary facilities with foreign companies is not much difference. But the most crucial question is: those in the field of welding equipment and welding materials and more dependent on imports, our own production equipment and welding materials can not meet the industry's production requirements, but also our welding equipment and welding materials businesses to work together.
Our company is an offshore steel construction companies, hope that China's welding business with foreign companies to develop a very technical level, even higher level of technology of welding equipment and welding materials, welding technology reduces the high dependence on foreign .
keywords: Aluminium Welding Wire, Nickel Welding Rod, Copper Alloy Welding Wire
2011年9月1日星期四
Riverstone laser "galvanometer scanning laser welding machine" project supported by the State
Recently, the Guangzhou Science and Technology Bureau and the Guangzhou Riverstone miles Laser Equipment Co., Ltd. on the "galvanometer scanning laser welding machine" entered into a project mission statement, the project supported by the National SME Technology Innovation Fund.
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SME Technology Innovation Fund was approved in 1999 by the State Council, Ministry of Science, the Ministry of Finance jointly administered with the promotion of a special high-tech achievements, high-tech industries to speed up the process, foster growth, and innovation capability, management specification, to participate in international competition SME group of government special fund.
Scan welding (Scanner Welding) is also known as remote welding (Remote Welding), which is a dynamic group using the scanning mirror welding. This technique of scanning movement of the lens instead of the traditional moving parts or welding lens group moves to provide greater welding efficiency, greater flexibility and better economy. The product is mainly to solve the precision metal parts, electronic packaging and circuit board industry in the sheet component lead-free soldering problems. After completion of the project, will reach an annual output capacity of 300. For precision welding equipment in China to contribute.
keywords: Electrodes
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