R5 in PCB refers to the resistance. There are many resistors in the circuit diagram, which are listed in sequence, R1, R2? … (the previous “R” refers to the resistance in general; The Arabic numerals at the back are components; Here is the sequence number of the resistor. There will be a lot of component numbers on many boards. For some boards, we can see that the resistor of R50/R80 is the serial number of this board.) C5 in the PCB refers to the capacitor, and the anti-interference capacitor at the power input (the same “C” in front refers to the capacitor; The Arabic numerals at the back are the sequence numbers of components (capacitors here).
Each letter represents a different word, and each word is the name of this component.
The following are the meanings of some common letters on our PCB boards:
R represents resistance and c represents capacitance.
RP stands for exclusion u generally stands for integrated circuit chip.
Q triode d diode
IC stands for integrated circuit DB rectifier bridge
Jumper or plug of LED J
F fuse l is inductance.
Y crystal oscillator (crystal) CN is the connector.
Usually, most of the characters in PCB design are resistors and capacitors, especially multilayer boards or boards with large size and many components. We can even see R200 and C300 on some boards, which shows that there are several hundred resistors or capacitors on a board (of course, some of the resistance and capacitance values are the same while others are different). No. is the placement position of components to facilitate the welding of components (for example, when designing, a resistance element with a specific parameter needs to be placed at a specified position of the circuit, so this position needs to be numbered, such as R1). A PCB has many tag capacitors, resistors, inductors, diodes, triodes, crystal oscillators, LED lights, fuses, etc. (SMD plug-ins all have them).
The same tag character can only appear once in the same circuit board, and each tag has its own fixed position. For example, when two R5 tags appear in a PCB, especially when the resistance values of the resistors are different, it is easy to misplace the machine on SMT. Two identical tag characters appeared in the PCB drawn by a customer before, resulting in the wrong welding position.