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http://www.runyvmat.com/As the industry leader in phosphine ligands and catalysts for homogeneous catalysis, Solvay offers a range of phosphorus compounds used in a breadth of applications and markets. Our scalable phosphorus chemistry meets the unique requirements of reactions that are crucial to several manufacturing processes across markets and applications, including petrochemicals, life sciences, flavors and fragrances, agrochemicals, fine chemicals, and plastics and other polymers. And do you what is Phosphine Ligands? Phosphines are a three-valent phosphorus compound and act as a "soft" σ-donating ligand with an unshared electron pair. This gives solubilization and stabilization to organometallic complexes by forming complexes with various transition metal species including latter-period transition metals and others, and is also used for controlling the reactivity and selectivity of the transition metal promoted reactions. Electron density and bulkiness of phosphine ligands are greatly related to the reactivity of their forming metal complexes. Generally, the phosphine ligands with high electron density increase the reactivity of oxidative addition from a metal center, and their bulkiness improves the reductive elimination. For example, trialkylphosphines especially tert-butyl or cyclohexyl group substituted phosphines show the highest electron density while the electron density of triarylphosphines and phosphite are sequentially decreasing. On the other hand, as an index of the bulkiness of phosphine ligands, that of monodentate phosphine ligands shows the cone angle (θ) while bidentate phosphine ligands show the bite angle (ω). As the angle of the phosphine ligands is wider, their steric effect is greater and they are regarded as more bulky phosphine ligands. A monodentate phosphine ligand of tri(o-tolyl)phosphine, and bidentate phosphine ligands of 1,1'-bis(diphenylphosphino)ferrocene and Xantphos are known as representative bulky phosphine ligands. There are many different kinds of Phosphine Ligands, such as Chiral Phosphine Ligands, Chelated Phosphine Ligands, Biaryl Phosphine Ligand, Trisubstituted Phosphine Ligands and Other Phosphine Ligands. Homogeneous catalysis is an efficient alternative to its heterogeneous counterpart, and enables access to certain molecules that are not accessible through heterogeneous catalysis. Our high-performance phosphine ligands provide endless customization opportunities for catalytic processes. Phosphorus chemistry offers substantial diversity of structure, tunability and thermal stability, which leads to its use in many essential industries and an abundance of applications. A majority of Solvay's phosphorus technologies are available in liquid or solution form, which facilitates ease of handling and safe product stewardship. Solids are available if preferred. Produced via industry-recognized manufacturing processes, our phosphine ligands and catalysts can be manufactured at any scale. Solvay offers expertise and manufacturing wherewithal at any phase of the value chain, but specializes in developing ligand solutions from the initial R&D stage all the way to industrial-scale production and distribution. Except for Phosphine Ligands, there are also many other material Intermediate and Function Materials like Catalyst including Homogeneous Catalyst and Olefin Copolymerization Catalyst. posted an update 1년, 7개월전
http://www.betonpcb.com/What is Printed Circuit Board?
A Printed Circuit Board (PCB) is a Sheet of Insulating Material such as Fiberglass, with Metallic Circuit or Track Printed or Etched on it for Electrical Conductivity. A PCB is found in almost all electronic products that we use in our daily life – Mobile Phone, Tablet, TV, Computer, Laptop, Keyboard, Mouse, Military Weapons, Airplane, Satellite etc.
In applications where fine conductive traces are needed, such as computers, PCBs are made by a photolithographic process, in a larger scale version of the way conductive paths in processors are made.
Electronic components are typically placed by machine onto a finished PCB that has solder dabs in place. The PCB bakes in an industrial oven to melt the solder, which joins the connections. Most PCBs are made from fiberglass or glass-reinforced plastics with copper traces. PCBs can be single-layer for simple electronic devices. Printed circuit boards for complex hardware, such as computer graphics cards and motherboards, may have up to twelve layers. PCBs are most often green but they can come in any color.
Other methods of PCB manufacturing include silk-screening and CNC-milling.
Different types of printed circuit boards
The most basic type of PCB is the original single-layer board which, as the name suggests, involves mounting one layer of copper on a substrate. Later developments led to double-layer and multi-layer PCBs, which saw multiple copper layers applied to two or more substrate layers. This made it possible to add a much higher density of components to the PCB and use them to create more powerful devices. While multi-layer boards did make maintenance more difficult, they soon became so cheap to make that it is now often more cost-effective to replace an entire board than to repair it.
Today, the most common substrate is FR-4 glass epoxy, though new materials have emerged as the popularity of PCBs has grown. Examples of PCB configurations include rigid PCBs, flexible PCBs, rigid-flex PCBs, and high-frequency PCBs. The different configurations often use different substrates. And there are many different types of PCB such as Flexible PCB, Rigid-Flex PCB, HDI PCB Board, High Frequency PCB, Aluminum PCB, Ceramic PCB, Multilayer PCB, etc.
What is PCB Assembly?
Well, a PCB is of No use unless we solder some Active and Passive Electronic Components on to the Board. These Electronic Components can be either Thru-Hole of SMD (Surface Mount Components). Once all the Electronic Components are Soldered (Assembled) on to the Board, it is Termed as Printed Circuit Board Assembly or PCB Assembly. The assembly can be also divided into Aerospace PCB Assembly and Automotive PCB Assembly.
