How to choose between low temperature solder paste, medium temperature solder paste and high temperature solder paste?

When choosing between low-temperature solder paste, medium-temperature solder paste and high-temperature solder paste, the main factors to be considered are the soldering temperature, the application scenario and the heat resistance of the components.

The following are recommendations for the selection of these three types of solder pastes:

1. Temperature range of use

Low-temperature solder paste: melting point is usually around 138 ° C, peak reflow temperature of 170 ~ 200 ° C, commonly used in temperature-sensitive components of the welding, such as plastic packaging components or other high-temperature sensitive components. Low-temperature solder paste mainly contains SnIn system / SnBi system / SnBiAg system and trace amounts of silver, copper, antimony and other micro-alloyed low-temperature high-reliability solder.

Medium temperature solder paste: melting point is generally between 180 ° C to 220 ° C, peak reflow temperature of 210 ~ 260 ° C, commonly used in general welding of electronic components, suitable for most of the electronic products manufacturing. Medium temperature solder pastes include leaded Sn63Pb37 solder paste, lead-free SnAgCu alloy (SAC305), and high reliability medium temperature solder optimised for reliability on the basis of SnAgCu.

High Temperature Solder Paste: The melting point is usually above 240°C, with a peak reflow temperature of 270~360°C. It is used in applications that require high temperature soldering, such as power supply modules, automotive electronics, or other equipment devices that need to work in a high temperature environment. High-temperature market is dominated by high-lead solder (Pb>90%) as well as high-temperature lead-free SnSb alloy, AuSn alloy solder paste is common. Currently there are also some solder manufacturers have introduced a new high-temperature lead-free alloy solder to replace the high-lead solder, the peak reflow temperature of 350 ~ 360 ° C, the solder joints temperature resistance can reach 280 ° C or more.

2. Soldering process

Low temperature solder paste: suitable for low temperature reflow soldering process, which can effectively reduce the damage of thermal stress on components.

Medium temperature solder paste: suitable for standard reflow process, is the most common choice.

High-temperature solder paste: suitable for high-temperature reflow process, to ensure that the solder joints in the high-temperature environment can still maintain good electrical and mechanical properties.

3. Components and PCB materials

Low-temperature solder paste is suitable for soldering temperature-sensitive components, such as LED lights, plastic encapsulated components.

Medium temperature solder paste is suitable for most standard components and PCBs.

High-temperature solder paste is suitable for components working in high-temperature environments and special PCB materials, such as ceramic substrates, copper bracket substrates.

4. Application Fields

Low temperature solder paste: consumer electronics, LED lighting, wearable devices, FPC, etc.

Medium temperature solder paste: communication equipment, household appliances, computers and peripherals, etc.

High temperature solder paste: automotive electronics, industrial control, aerospace and military equipment, power devices, etc.

5. Cost

The cost of low temperature solder paste is relatively low, suitable for low-cost electronic products.

Medium temperature solder paste has a medium cost and is suitable for most electronic product manufacturing.

High-temperature solder paste has a higher cost and is suitable for products with high requirements and high reliability, requiring a secondary encapsulation process.

Selection of a suitable solder paste requires comprehensive consideration of soldering temperature, process requirements, component and PCB materials, application areas and cost factors. Generally speaking, priority is given to medium temperature solder paste because it is widely applicable and can meet the needs of most electronic products. If there are special temperature or process requirements, then choose low temperature or high temperature solder paste.

Here I would like to recommend Fitech's high/medium/low temperature solder paste products, Fitech's solder paste products have the following advantages; good sphericity, uniform particle size distribution, excellent wettability, adjustable viscosity and other characteristics, which can meet the needs of different application scenarios. At the same time, Fitech also provides customised service, can be customised according to the customer's specific needs for special alloys and particle size of the solder paste. If you are interested in Fitech's high and low temperature solder paste products, or need to get more detailed product information and technical support, please feel free to contact our technical support team. Our professional engineers will provide you with the most accurate and professional advice and assistance to ensure that you can choose the most suitable solder paste products for your needs. We look forward to working with you to create quality soldering processes and products.