Characteristic of SMT components
SMT components are commonly known as no pin components or chip components. It is customary to refer to SMT passive components such as chip resistors, capacitors, and inductors as SMC (Surface Mounted Components), and active devices such as small form factor transistors SOT and flat assembly (QFP) as SMD (Surface Mounted) Devices). Both SMC and SMD are functionally identical to traditional through-hole components. Originally created to reduce volume, however, they have shown great vitality as soon as they are available. Their volume is significantly reduced, their high-frequency characteristics are improved, their vibration resistance and compactness are unmatched by traditional through-hole components. This has greatly stimulated the development of electronic products in the direction of multi-function, high performance, miniaturization and low cost. At the same time, these microelectronic products have promoted the continued development of SMC and SMD. The chip resistors and capacitors have been reduced from the early 3.2mm*1.6mm to 0.4mm*0.2mm. The pin center distance of the IC has been reduced from 1.27mm to 0.3mm, and with the development of bare chip technology, BGA and CSP classes Multi-pin devices have been widely used in production. In addition, some electromechanical components, such as switches, relays, filters, and delay lines, are also chipped.
1. On the electrodes of SMT components, some solder terminals have no leads at all, and some have very short leads; the distance between adjacent electrodes of SMT integrated circuits is much smaller than the standard lead pitch (2.54mm) of conventional THT integrated circuits. At present, the center distance of the pins has reached 0.3mm. In the case of the same degree of integration, the size of the SMT device is much smaller than that of the THT device; in the same volume, the integration of the SMT device is increased many times.
2. The SMT components are mounted directly on the surface of the PCB and the electrodes are soldered to the pads on the same side as the components. Thus, the diameter of the through hole on the PCB is determined only by the process level of the metallized hole when the sound quality circuit board is made, and there is no pad around the through hole, so that the wiring density and the assembly density of the PCB are greatly improved.