Compared with the through hole interpolation, surface mount technology has the following advantages:
(1) realize miniaturization.PCB electronic components, its geometric size and occupied space volume than the through-hole plug components are much smaller, generally can be reduced by 60% to 70%, or even 90%.Weight loss: 60% ~ 90%.
(2) high signal transmission speed.Compact structure, high assembly density, PCB assembly density can reach 5 when PCBS are pasted on both sides.5 ~ 20 solder joints/cm., because the connection is short and the delay is small, high speed signal transmission can be achieved.At the same time, more vibration resistance, impact resistance.This is of great significance for the ultra-high speed operation of electronic equipment.
(3) good high-frequency characteristics.Because the components have no lead or short lead, the distributed parameters of the circuit are naturally reduced and the rf interference is reduced.
(4) it is conducive to automatic production, improving the yield and production efficiency.Due to the standardization, serialization and consistency of welding conditions of chip components, SMT automation degree is very high (automatic production line solution), which greatly reduces the failure of components caused by welding process and improves reliability.
(5) low material cost.At present, except for a small number of varieties that are difficult to be flaked or whose packaging precision is particularly high, the packaging cost of most PCB components has been lower than iFHT components of the same type and function. Consequently, the sales price of SMT components is lower than THT components.
(6) SMT (surface mount technology) technology simplifies the production process of electronic complete machine products and reduces the production cost.In the PCB assembly, the components of the lead does not bend, cut short, so that the whole production process is shortened, production efficiency has been improved.The processing cost of the same functional circuit is lower than that of through-hole interpolation, which can generally reduce the total production cost by 30% ~ 50%.
Disadvantages of surface assembly technology
1. Generally, the power is small
2. Small volume
3. Easy to broken
4. High requirements on welding technology: easy to appear virtual welding, tin receiving, "crater", leakage welding, bridge (with tin), "monument" and other phenomena
5. Components are easy to be dropped or damaged during installation
6. It is not easy to use visual inspection, which is difficult to test
7. Miniaturization and numerous solder joint types complicate the process and inspection
8. Large investment in equipment
9. Technical complexity requires high training and learning costs
10. Rapid development requires continuous follow-up