SMD Resistor, also known as Chip Fixed Resistor, is one of the metal glass glaze resistors.
SMD Resistor, also known as Chip Fixed Resistor, is one of the metal glass glaze resistors. It is a resistor made by mixing metal powder and glass glaze powder and printing it on the substrate by screen printing. Resistant to humidity and high temperature, with a small temperature coefficient. It can greatly save the cost of circuit space and make the design more refined.
Chip resistors are divided into: conventional series thick film chip resistors and high precision and high stability chip resistors
Conventional series thick film chip resistors include: 1 General purpose General purpose 0201 - 0805, 2 General purpose 1206 - 2512
High precision and high stability chip resistors include: 1 High precision - high stability High precision - high stability 0201 - 0603, 2 High precision - high stability 0805 - 1210, 3 High precision - high stability, 2010 - 2512
Chip resistors have the advantages of small size, light weight, high installation density and strong shock resistance. It has the advantages of strong anti-interference ability and good high-frequency characteristics, and is widely used in computers, mobile phones, electronic dictionaries, medical electronic products, camcorders, electronic watt-hour meters and VCD players. SMD components can be divided into three categories: rectangular, cylindrical and special-shaped according to their shape. According to the type, there are resistors, capacitors, inductors, transistors and small integrated circuits. The nominal method of SMD components is different from that of general components.
Chip resistors have 5 parameters, namely size, resistance, tolerance, temperature coefficient and packaging.
1. Size series The chip resistor series generally has 7 sizes, which are represented by two size codes. One size code is the EIA (Electronic Industries Association) code represented by a 4-digit number, with the first and last two digits representing the length and width of the resistor, in inches. The other is the metric code, also represented by a 4-digit number, and its unit is millimeters. Resistors of different sizes have different power ratings. Table 1 lists the codes and power ratings for these seven resistor sizes.
2. Resistance series Nominal resistance values are determined by series. Each series is divided by the tolerance of the resistance (the smaller the tolerance, the more the resistance is divided), the most commonly used is E-24 (the tolerance of the resistance is ±5%). On the surface of the chip resistor, three digits are used to represent the resistance value, of which the first and second digits are significant numbers, and the third digit represents the number of followed zeros. When there is a decimal point, "R" is used to represent it, and it occupies one significant digit. The nominal resistance code representation method is shown in Table 3.
3. Tolerance The tolerance of chip resistors (carbon film resistors) has 4 grades, namely F grade, ±1%; G grade, ±2%; J grade, ±5%; K grade, ±10%.
4. The temperature coefficient of the temperature coefficient chip resistor has two grades, namely the w grade, ±200ppm/℃; the X grade, ±100ppm/℃. Only the resistors with a tolerance of class F use class x, and resistors with tolerances of other classes are generally of class w.
5. There are two main types of packaging: bulk and tape rolls.