Features and differences of low, medium, high temperature solder paste

In the solder industry, each manufacturer has different solder paste formulas, different production processes, and different types. Among them, lead-free solder paste is roughly divided into low temperature solder paste, medium temperature solder paste and high temperature solder paste. So what are the characteristics of low temperature, medium temperature and high temperature solder paste, and what are the differences? From the surface, we should be able to see why it is named this way, the temperature must be different, then the specific characteristics and differences, we summarize for you as follows:

Low temperature solder paste:The melting point is 138°C, and its alloy composition is Sn/Bi (lead-free). When the components of the SMD cannot withstand the temperature of 200 ℃ and above, use low temperature solder paste for soldering. It can protect welding components and PCBs that cannot withstand high temperature welding, and is widely used in the LED industry. Its composition is tin-bismuth alloy. The maximum temperature of low temperature solder paste soldering is 165~170℃.

Feature:

1. Low melting point.
2. Suitable for components not resistant to high temperature.

Medium temperature solder paste:The melting point is 172℃~183℃, and its composition is Sn/Pb (lead-containing) or Sn/Ag/Bi (lead-free). It is also used for welding components that cannot withstand high temperature, and is widely used in the LED industry.

Feature:

1. Use high-quality rosin, which has good adhesion and is not easy to collapse.
2. After reflow, there is not much residue and it is transparent.
3. Can pass the ICT test.

High temperature solder paste: The melting point is 210~227℃, which is composed of tin, silver, copper and other metal elements. If the components of the SMD can withstand high temperature, it is recommended to use high-temperature lead-free solder paste, because high-temperature solder paste has higher reliability and more advantages. High temperature solder paste is more widely used than low temperature solder paste, such as the welding of some BGA, QFN, SMT, and mobile phone precision components, the effect of high temperature solder paste will be better.

Feature:

1. The reliability is relatively high, and it is not easy to desolder and crack.
2. No rinse, low residue.
3. High insulation resistance.
4. Pass the ICT probe test.
5. Climbing tin effect is good.
6. Long service life and high activity.
7. Low void rate, not easy to collapse.
8. The solder joints are full and bright.
9. High strength and excellent electrical conductivity.
10. Easy demolding and easy handling of fine pin pitches.
11. Using imported flux, it can be used for a long time without affecting the wettability and viscosity of solder paste.