What is The Meaning of Silk Screen on PCB Board?

There are many silk screen letters on the PCB, such as R109, c113, Q105, d206, etc. What do these letters / numbers mean? The letters on the PCB board represent the abbreviation of electronic components, and numbers often follow the letters, which are also meaningful.

The Letters on PCB Board

PCB Alphabet Meaning Table
Letter	Representative Components	Explain
D	Diode	VD also stands for diode, and D also stands for inverter.
Q	Transistor	Since transister appeared late, “t” has been used, so it is represented by Q. V & VT also stands for transistor.
C	Capacitor	Capacitor
L	Inductance	Since “I” has been used to represent current, “L” is used to represent inductance. L also stands for light or length
R	Resistance	Resistance
K	Relay	The national standard GB7159 stipulates that the basic character symbols of relay and contactor types are represented by K.
T	Transformer	Transformer
X, Y	Crystal oscillator	Crystal oscillator
U, IC	Chip	In the international standard, chip is “u”, while IC is the abbreviation of integrated circuit.
M	Motor	Motor
CX	High voltage ceramic capacitor	/
CY	High voltage film capacitor	/
CE	Electrolytic capacitor	/
CN	Drainage	/
RN	Resistance elimination	/
VR	Adjustable resistance	Variable resistor
RT	Thermistor	Resistance changes with temperature: R refers to resistance and T refers to temperature
PR	Potentiometer	Potentiometer
RG	Grounding resistance	G is the ground, GND
J	Joggle	Joggle, interface
JP	Jumper	Jumper
FU	Fuse	Fuse
N	Optocoupler	/
B, BZ	Buzzer	Buzzer
SCR	Unidirectional thyristor	/
TRIAC	Bidirectional thyristor	/
FB	Ferrite Bead	Ferrite Bead
ZD	Zener Diode	Zener Diode
PQ	field effect	/
LED	light-emitting diode	light-emitting diode
SPK	Speaker	Speaker
S, SW	Circuit board type or gear switch	Switch
BL	Liquid level sensor
BH, BM	Temperature sensor
DB	Bridge Diode	Bridge Diode
TP	Test Point	Test Point

The Number on PCB Board

The above are all commonly used component identifications, and there are many more examples here. After finishing the letters, let’s talk about the numbers. R107, c118, D202 and other numbers are often seen on the circuit board.

Generally, the first letter identifies the device category, such as R for resistor, C for capacitor, D for diode, etc;

The second is the number, which indicates the circuit function number. For example, “1” indicates the main board circuit, “2” indicates the power circuit, etc., which is determined by the circuit designer;

The third and fourth digits indicate the serial number of similar devices on the circuit board. For example, r117: the resistance on the main board, with the serial number of 17t101: the transformer on the main board, with the serial number of 01.

Finally, to mention another word, the meaning of letters / numbers on the PCB is not strictly regulated at present, and it is not always consistent with the above table. It can be defined by people. As long as the component label of the design schematic is consistent with that of the PCB, it is convenient for all parties to communicate and manufacture.