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What Temperature Is Solder Reflow?

Creation date: Feb 22, 2024 6:25pm     Last modified date: Feb 22, 2024 6:25pm   Last visit date: Apr 3, 2024 3:49pm
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Feb 22, 2024  ( 1 post )  
Wang Meihong (chenluseo)

In the intricate world of electronics manufacturing, solder reflow temperature holds a position of paramount importance. The process of solder reflow, wherein solder paste melts to form strong, reliable connections between electronic components and printed circuit boards (PCBs), relies heavily on precise temperature control. Understanding the optimal solder reflow temperature is crucial for ensuring the integrity, quality, and functionality of electronic devices.


The Basics of Solder Reflow


Solder reflow is the process by which solder paste, a mixture of tiny solder particles and flux, transitions from a solid to a liquid state and then solidifies again, forming strong electrical connections between electronic components and PCBs. This process typically occurs in a specialized machine called a reflow soldering oven.


Optimal Solder Reflow Temperature


The optimal solder reflow temperature is determined by several factors, including the composition of the solder paste, the melting point of the solder alloy, and the requirements of the components and PCBs being assembled. However, a typical temperature profile for solder reflow consists of three main stages:


  1. Preheat: During this stage, the PCB and components are gradually heated to a temperature slightly below the melting point of the solder paste. This allows for the removal of any moisture and flux volatiles and helps to prevent thermal shock when the solder paste melts.
  2. Reflow: In this stage, the temperature is raised to the melting point of the solder alloy, causing the solder paste to liquefy and form solder joints between the components and PCB pads. The duration of this stage is carefully controlled to ensure proper wetting and bonding between the solder and metallization on the PCB pads.
  3. Cooling: After reflow, the PCB is cooled to solidify the solder joints and stabilize the components in place. The cooling rate is controlled to prevent thermal stress and ensure the reliability of the solder joints.


Factors Influencing Solder Reflow Temperature


Several factors influence the selection of the solder reflow temperature profile:


  • Solder Alloy: Different solder alloys have different melting points, which dictate the reflow temperature required. Common solder alloys include lead-free options such as SAC (tin-silver-copper) and SnAgCu (tin-silver-copper) and lead-based alloys such as SnPb (tin-lead).
  • Component Sensitivity: Electronic components have maximum temperature ratings beyond which they may be damaged. The reflow temperature profile must be carefully selected to avoid exceeding these ratings.
  • PCB Material: The composition and thickness of the PCB substrate can affect the heat transfer characteristics and thus influence the reflow temperature profile.





In the realm of electronics manufacturing, solder reflow temperature plays a critical role in ensuring the quality, reliability, and performance of electronic devices. By understanding the optimal temperature profile for solder reflow and carefully controlling the heating and cooling stages, manufacturers can achieve consistent and robust solder joints, ultimately delivering high-quality products to consumers. As technology advances and electronic devices become more sophisticated, the importance of precise temperature control in solder reflow processes will only continue to grow.


We offer vacuum reflow ovens with several different footprint and vacuum chamber size options.