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Solder resistors are made by sputtering an alloy resistance film on a ceramic substrate in a vacuum, followed by the addition of a glass protective layer and three layers of electroplating. They offer high reliability, uniform physical dimensions, precision, as well as low temperature coefficients and resistance value tolerances. Features of surface-mount resistors: small size and light weight; suitable for reflow soldering and wave soldering; stable electrical performance and high reliability; low assembly cost and compatibility with automatic mounting equipment; high mechanical strength and excellent high-frequency performance. Part specifications: Part specifications refer to the external dimensions of the parts. Over the course of SMT’s development, the industry has established a standard series of parts to facilitate manufacturing processes, and all part suppliers produce their products in accordance with these standards. The dimensional specifications for standard components are expressed in both imperial and metric units, as shown in the table below: Imperial notation: 1206, 0805, 0603, 0402; Metric notation: 3216, 2125, 1608, 1005. Meanings: L: 1.2 inches (3.2 mm), W: 0.6 inches (1.6 mm); L: 0.8 inches (2.0 mm), W: 0.5 inches (1.25 mm); L: 0.6 inches (1.6 mm), W: 0.3 inches (0.8 mm); L: 0.4 inches (1.0 mm), W: 0.2 inches (0.5 mm). 102 represents a resistance value with a precision of 5%; the first two digits indicate the significant figures, while the third digit shows the number of zeros. The basic unit is Ω, and 102 = 1000 Ω = 1 KΩ. 2. 1002 is the representation of a resistance value in terms of 1%. The first three digits represent the significant figures, while the fourth digit indicates the number of zeros. The basic unit is Ω; therefore, 1002 = 10000Ω = 10KΩ. 3. If it is a decimal, use “R” to represent the decimal point. And it occupies one significant digit, with the remaining two being significant digits. For example, “2R4” means “2.4Ω”; “R15” means “0.15Ω”. The operating temperature range for surface mount resistors is -55°C to +125°C. The maximum operating voltage varies depending on the size: it is lowest for 0201 components, 50V for 0402 and 0603 components, 150V for 0805 components, and 200V for other sizes.