1. SMT machine high assembly density
Compared with traditional perforated components, chip components take up less area and less quality. Using SMT can reduce the volume of electronic products by 60% ~ 70% and reduce the quality by 75%. Through hole installation technology is to install components according to 2.54mm grid; The SMT assembly component grid has developed from 1.27mm to the current 0.5mm grid, and the density of installed components is higher. For example, a 64-pin DIP block with a 25mm×75m assembly area, while the same lead with a 0.63mm lead pitch QFP has an assembly area of 12mm×12mm, 1/12 of the area of the through hole technology.
2. High reliability
Because the chip components of high reliability, small components and light, so the seismic capability is strong, can be used in the electronic processing automatic production, stick with high reliability, generally poor solder joint rate is less than ten over one million, lower than the through-hole components wave soldering technology, an order of magnitude in SMT assembly of electronic products MTBF for an average of 250000 hours, At present, almost 90% of electronic products are using SMT process.
3. Good high frequency characteristics
Because the chip components are firmly mounted, the components are usually leadless or short leads, which reduces the influence of parasitic inductance and parasitic capacitance, and improves the high frequency characteristics of the circuit. The highest frequency of the circuit designed by SMC and SMD is 3GHz, while that of the through-hole components is only 500MHz. The use of SMT can also reduce the transmission delay time, can be used in the clock frequency of 16MHz or more circuits. With MCM technology, the high end clock frequency of computer workstations can reach 100MHz, and the additional power consumption caused by parasitic reactivity can be reduced to 1/3 to 1/2 of the original.
4. Reduce the cost
The area used by the printed board is reduced, which is 1/12 of the through-hole technology. If CSP is used for installation, the area will be greatly reduced.
The number of holes drilled on the printed board is reduced, saving the cost of repair.
As the frequency characteristic is improved, the cost of circuit debugging is reduced.
Because chip components are small in size and light in weight, packaging, transportation and storage costs are reduced.
SMC and SMD are developing fast and the cost is falling rapidly. The price of a chip resistor and through-hole resistor is less than RMB 1 cent.
5. Easy to automate production
At present, to achieve complete automation of perforated mounting printed boards, it is necessary to expand the area of the original printed board by 40%, so that the insert head of the automatic plug-in can insert the components, otherwise there is not enough space clearance, and the components will be damaged. Automatic SMT adopts vacuum nozzle to absorb and release components. The vacuum nozzle is smaller than the shape of components, which can improve the installation density. In fact, small components and fine-spacing QFP components are produced by automatic SMT, in order to achieve full-line automatic production.