Soldering temperature for circuit boards (2023)
One of the crucial aspects of soldering electronics circuit boards is temperature setting, the right temperature can ensure strong and reliable joints or connections. But determining the ideal soldering temperature for circuit boards can challenge because a lot of factors should be considered before deciding the temperature for a circuit board.
For circuit boards, the suited temperature range is 350°C to 450°C. Several factors influence the selection of temperature for soldering circuit boards. These include the type of alloy, the size and thermal characteristics of the components being soldered, and the type of circuit board material.
In this article, we will discuss the importance of temperature in soldering, the factor that influences the choice of temperature and provide you guidelines for finding the best temperature for a circuit board.
Let’s get started.
Soldering temperature for circuit boards
The recommended soldering temperature for electronic circuits can vary depending on several factors, including the type of components you’re soldering, the soldering technique you’re using, and whether you’re working with lead-based or lead-free solder. Here are some general temperature guidelines:
a. Lead Based Soldering
- For traditional lead-based solder (typically a mixture of tin and lead), a soldering iron temperature in the range of 350°C to 400°C (662°F to 752°F) is commonly used.
- Delicate components like SMD (Surface Mount Device) components and integrated circuits (ICs) might require slightly lower temperatures, around 300°C to 350°C (572°F to 662°F), to avoid damage.
b. Lead Free Soldering
- Lead-free solder has higher melting points than lead-based solder due to environmental regulations. The recommended temperature range for lead-free solder is typically between 370°C and 420°C (698°F to 788°F).
- Again, sensitive components may require lower temperatures, typically around 330°C to 370°C (626°F to 698°F).
c. SMD Soldering
- When soldering small SMD components, a lower temperature in the range of 250°C to 350°C (482°F to 662°F) is often used. Hot air rework stations are also commonly used for SMD soldering.
d. Thermal Considerations
- If you’re soldering large components or components connected to larger copper areas (such as power connectors or heat sinks), you might need to use slightly higher temperatures to ensure proper heat transfer.
e. Soldering Technique
- Different soldering techniques, such as drag soldering or touch-and-release soldering, might require slight temperature adjustments based on the soldering iron’s thermal recovery time.
Remember that these temperature ranges are general guidelines and might vary based on the specific soldering iron, solder, and components you’re using. We will discuss these factors in the sections of this posts.
Role of Temperature in Soldering
One of the important role temperature plays in soldering is that it guarantees strong, reliable and durable solder joints.
When we heat the solder, it goes through the phase-changing process from solid to liquid to solder the components and create a strong bond.
If less heat is provided it can result in weak joints or connections and if excess heat is given it can damage the delicate components.
The appropriate temperature is necessary for the solder to melt, spread evenly, and establish a strong bond without doing any damage. This appropriate temperature depends on many factors.
a. Melting Solder
Solder has a specific melting point, which is typically lower than the melting point of the components being soldered.
The soldering iron’s temperature needs to be high enough to melt the solder, allowing it to flow and create a solid connection between the components.
b. Proper Flow and Wetting
When the soldering iron tip contacts the joint, it should provide enough heat to allow the solder to flow smoothly.
This results in a process called wetting, where the solder forms a smooth and shiny connection between the components. Proper wetting ensures a strong and reliable electrical connection.
c. Avoiding Cold Joints
If the soldering iron’s temperature is too low, it might not melt the solder completely, leading to what’s called a “cold joint.”
Cold joints have poor electrical conductivity and mechanical strength, which can result in intermittent connections or component failure.
d. Component Sensitivity
Different electronic components have varying heat tolerance levels. Sensitive components like integrated circuits (ICs) and transistors can be damaged if exposed to excessive heat for prolonged periods.
Using a soldering iron with adjustable temperature control allows you to set the appropriate temperature for the specific components you’re working with.
Factors that influence the temperature selection
Let’s discuss the factors that may affect the selection the of temperature for soldering circuit boards.
1. Solder
The solder you used for soldering can influence the right temperature choice for the circuit board. As it determines the temperature that should be selected.
Different solder has different melting points. Lead-free solder (such as SAC305), the most popular solder, typically melts at a temperature of 217°C (423°F).
Lead-based solders, on the other hand, typically have melting values between 183°C and 188°C (361°F and 370°F), which are lower.
The melting point of the solder alloy should be considered when determining the suitable temperature for the circuit board.
2. Components size and thermal characteristic
Another factor that contributes to temperature selection is the component’s size and thermal characteristics.
Smaller components may need lower temperatures to prevent thermal damage, while the components larger in size required higher temperatures to ensure effective soldering.
Components with heat-sensitive parts, such as integrated circuits (ICs) or surface-mounted devices (SMDs), often have recommended temperature ranges provided by the manufacturer. By following these recommendations, components are protected from harm while soldering.
3. Circuit board material
The circuit board material is also an aspect of a temperature selection. The heat transfer during soldering is impacted by the different thermal characteristics of circuit board materials.
Multilayer boards can dissipate more heat effectively than single-layer boards. It is essential to review the specifications and guidelines provided by the circuit board material manufacturer and consider the specific requirements of the components used.
For setting the temperature it’s important to consider board characteristics.
Guideline for choosing the best temperature
You must stick to basic guidelines to choose the right temperature.
1. Consult manufacturer guideline
Regarding the circuit board and components, the manufacturer provides complete guidelines like how to solder it and what the right temperature should be used.
Read the guidelines carefully and implement them because these are your starting points for determining the suitable temperature for your board.
2. Experimentation and testing
Experimentation and testing are required if manufacturer guidelines are unavailable or the information given is not sufficient.
Test the small batch of the board with a different temperature setting and see how the board are responding. Inspect the solder joints for quality, strength, and any signs of thermal damage.
You can determine the ideal soldering temperature for your unique components and circuit boards by gradually increasing the temperature and analyzing the results.
3. Thermal stress
Excessive temperature or temperature changes can cause thermal stress in components and circuit boards, which eventually leads to failure.
Thermal stress can be reduced with gradual heating and cooling as well as by preheating the circuit board. Utilizing a hot air gun or other specific preheating tools before soldering the board helps to obtain a more even temperature distribution.
Take the thermal stress into consideration also while soldering as frequent changes in temperature can negatively affect the board.
4. Use temperature-control soldering stations
Using temperature-control soldering stations can also minimize the risk of thermal stress and damage to the board.
These stations provide precise temperature control, ensuring stability and accuracy during the soldering process. Avoid using uncontrolled soldering irons or heat guns since they can produce unpredictability and temperature fluctuations.
Start investing in the temperature-controlled soldering iron and investing in it is highly recommended.
Conclusion
Choosing the right temperature for the circuit board is crucial for producing reliable and durable connections. The ideal temperature depends on several factors.
The solder is used, and the component’s size and circuit board material plays a vital role in the selection of temperature. The circuit board is sensitive the inappropriate temperature may damage it.
One can determine the ideal temperature for soldering particular components and circuit boards by taking manufacturer recommendations into account, performing experiments, and giving thermal stress management priority.
Remember, soldering requires a delicate balance of heat—too little compromises joint strength, while too much can cause irreversible damage. You can attain consistent, reliable results with thought and practice.
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