Printed circuit board design-printed circuit board manufacturer
Printed circuit board design is based on circuit picture shows the basis for the circuit designer to achieve the required functionality. The main printed circuit board design layout refers to the need to consider the layout of the external connection. Optimize the layout of the internal electronic components. Metal wires and vias to optimize the layout. Electromagnetic protection. Heat dissipation and other factors. Good layout can save the cost of production to achieve a good circuit performance and heat dissipation. Simple layout can be achieved by hand, with the help of complex computer-aided layout design requires design (CAD) to achieve.
About PCB design
Specific methods
1 Purpose and role 2. Scope 3. Responsibility attitude 4 qualifications and training 5. Work guide (with units of length as MM)
1, 2 hole used as little as possible, silkscreen (Overlay) 3, SMD specificity 4, 5 grid populated areas, pad (Pad) 6, various types of film (Mask) 7, fly line - there is double meaning
1 Purpose and role 2. Scope 3. Responsibility attitude 4 qualifications and training 5. Work guide (with units of length as MM)
1, 2 hole used as little as possible, silkscreen (Overlay) 3, SMD specificity 4, 5 grid populated areas, pad (Pad) 6, various types of film (Mask) 7, fly line - there is double meaning
In the high-speed design, controlled impedance boards and line characteristic impedance is the most important and one of the most common problems. First look at the definition of transmission lines: transmission line consists of two components with a length of conductor, a conductor used to transmit signals, and the other to receive the signal (remember "loop" instead of "land" concept). In a multilayer, each line is a transmission line component of the nearby reference plane can be used as second line or loop. One line to become "good performance" The key is to make it the transmission line characteristic impedance remains constant throughout the circuit board. Board as "controlled-impedance board," the key is to make the characteristic impedance of all lines meet a specified value, usually 25 ohms and 70 ohms. In the multi-layer circuit board, the transmission line is the key to good performance make it the characteristic impedance of the constant in the entire line. However, what is the characteristic impedance? Understanding of the characteristic impedance The easiest way is to look at the signal in the transmission of what they encountered. When the cross-section along a transmission line has the same moves, similar to Figure 1 of the microwave transmission. Assuming that 1 volt of the voltage step wave and to this transmission line, such as the 1-volt battery connected to the front of the transmission line (which is located between the send line and loop), once connected, the voltage wave along the line the speed of light communication, its speed is usually about 6 inches / nsec. Of course, this is really sending the signal line and the voltage difference between the loop, it can send a line from any point and loop point adjacent to measure. Figure 2 is a schematic diagram of the voltage signal transmission. Zen approach is to "generate signal", and then along this transmission line to six inches / ns speed transmission. The first 0.01 ns 0.06 inches forward, then send the line have extra positive charge, while the loop with the excess negative charge, the charge is the difference between the two maintained between the two conductors 1 volt voltage difference, and These two conductors and form a capacitor. 0.01 ns in the next, but also a section of 0.06 inches of the transmission line voltage adjustment from 0 to 1 volt, which must add some positive charge to send a line, and add some negative charge to the receiving line. Every move 0.06 inches, must be more positively charged He Jia to send line, while the more negative charge added to the circuit. Every 0.01 ns, the other must be a transmission line charge, then the signal began to spread along this section. Charge the battery from the front of the transmission line, when moving along this line, give a continuous part of the transmission line charge, which sent the line and loop in the formation of 1 volt between the voltage difference. 0.01 nanoseconds of each move, you get some from the battery charge (± Q), constant time intervals (± t) within a constant outflow from the battery power (± Q) is a constant current. Into the loop current is actually negative and positive current flow is equal, and just in front of the signal wave, alternating current through the upper and lower circuit composed of capacitors, the end of the cycle. PCB (Printed Circuit Board) PCB abbreviation edit the specific methods of this paragraph.