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From product design to procurement of electronic passive components is a supporting role , PCB material costs throughout the electronic products accounted for about one to share , but the large number of passive components in electronic products . In the capacitor , for example, the development from 2G to 3G, in the light of a cell phone number on the MLCC increased from an average of 165 288 ; television in the number of capacitors from the CRT era more than 200 pieces to the LCD TV era more than 1000 pieces . Many in number, the reliability of the result of the accumulation device reliability is much lower than the passive IC, any failure of a tiny passive devices may cause failure of the whole system.

Passive device reliability problems can be preferred suppliers , product suppliers and other periodic sampling to detect the incoming quality measures to minimize the risk , but things did not end . The selected circuit element parameters meet the requirements , you can also work, but the question is whether these elements selected so that the system works in the best condition , ESD meets the requirements, change and adjust your phone resistive and capacitive components are obtained the perfect audio effect.

If performance is met, then the component price is appropriate? For high-end electronic products, performance requirements higher than the price asked ; For low-end electronic products, the price is higher than the required performance requirements . How to master the balance point ? Good quality products of high prices and low prices are always people worried about the quality of products . If the price is satisfactory , but the suppliers' delivery cycle a little longer, then how to do ?

This ring set problems are passive component selection process to solve the problem . Selection is a complex systems engineering , is a design engineer, process PCB material certified engineers , purchasing, suppliers and even interact with third-party testing organization , from any participation in a role , this process might be very difficult. Procurement officers often seen complaining in forums : Design Engineer specifications given hard to find. In fact, many newly recruited engineers to develop the theoretical calculation only and does not understand the actual production suppliers , often lists some rare or nonexistent production specifications . For example, by theoretical calculation 0603/C0G/25V/3300pF specifications MLCC, but 0603/C0G/25V the MLCC generally do 1000pF. Due to the design engineer to understand some cases selection , resulting in rising procurement costs and the impact of delivery .

Component selection in each role should be quite familiar with the whole process . Design engineer to understand the vendor's situation , but also to understand the product case . Procurement specification design engineer must determine whether a given realistic. It is based on the situation , Electronic Components Technology Network launched a selection of thematic series , the current launch is the capacitance selection essentials , will be launched after the selection of topics inductors , connectors , MOSFET and other components . We think that is the basis for the selection of innovative start circuit .

Capacitance is the largest amount of electronic equipment passive components . China produces more than 40 percent of the world's capacitance , capacitance level of quality gap between domestic and foreign capacitance narrowing. In the domestic component replacement , the capacitor plays an important role. And to the largest number of MLCC capacitors and electrolytic capacitors , the most widely used , so the current choice is the capacitance MLCC selection and electrolytic capacitors. Foreign capacitor manufacturers websites usually provide selection tools to assist selection, there are two : Parametric Selection and by application selection, Special Issue will introduce some mainstream selection tool . Another optional component of the final but also through simulation tools to optimize , what mainstream simulation tools and their characteristics are described in this topic in .