Soldering is critical in printed circuit board (PCB) assembly to create strong and reliable connections. There are two different types of soldering: lead and lead-free. Depending on what you are looking for, each type of soldering can impact reliability, compliance, and the cost of your project. In this blog, we will outline lead and lead-free solder pros and cons to help you determine which is best for your application.
What is Lead-Based Solder in PCB Manufacturing?
Lead-based soldering is composed of lead and tin, with the typical composition being Sn63/Pb37 (63% tin, 37% lead). This soldering method is commonly used in legacy and high-reliability applications, such as military and aerospace products.
Pros of Lead-Based Solder
Lead-based soldering has a few benefits. Lead has a low melting point of 183ºC, which simplifies reflow and wave soldering because it is easier to bring to a working temperature. This method also offers shock resistance, fewer flaws after cooling, reduced risk of cracking, ease of inspection, and proven long-term reliability in demanding environments.
Cons of Lead-Based Solder
Lead-based soldering also has various disadvantages that you will want to consider before settling on this option:
- Toxicity and occupational health risks during handling: Lead is readily absorbed by the body and can cause harm in various ways, including developmental delays, abdominal pain, neurological changes, and irritability, and may even be fatal.
- Not RoHS compliant: Lead is a restricted material that poses risks to human health and the environment, so it is not RoHS compliant. Lead use must be limited in consumer and commercial electronics, and the risks associated with disposal must also be considered.
- Declining availability: With the health and environmental concerns connected to lead, the availability of this soldering method in global markets is declining.
What is Lead-Free Solder in PCB Manufacturing?
Lead-free soldering uses common alloys that do not contain lead. These alloys include SAC305, which is a combination of tin, silver, and copper, and SN100C, and some others. RoHS compliance has caused this soldering method to be adopted widely in PCB manufacturing, and it is used in nearly all consumer electronics today.
Pros of Lead-Free Solder
Lead-free soldering has many advantages, making it a common choice for PCB manufacturing.
- No risk to human or environmental safety: There is no risk to human health or the environment when using lead-free soldering.
- Suitable for high-density and fine-pitch components
- Improved reliability: This process also has improved reliability and process compatibility due to its popularity.
- Better for global distribution: It has better long-term sustainability for global distribution.
Cons of Lead-Free Solder
There are a few downsides to lead-free soldering. With the higher melting temperatures, this process requires tighter thermal profiles. Additionally, it puts increased thermal stress on sensitive components and substrates. It is also more challenging to rework, and there is a potential for brittle joints. Finally, this process may result in higher material and production costs.
Making the Right Choice for Your PCB Project
When choosing the right soldering technique for your project, there are a few important considerations to make:
- Are there any regulatory compliances you need to consider? Do you need to meet RoHS-regulated markets? If so, lead-free soldering may be best for you.
- What is your application? Are you working with consumer electronics or medical applications? Here, lead-free soldering is the right choice. Lead-based soldering might be better suited for aerospace or defense applications.
- What are your component compatibility and thermal limitations? These considerations both need to be made when choosing which method, since they use different temperatures.
- What is your budget? If you are looking to lower costs and don’t need to meet any regulations, then lead-based soldering is a good choice.
Explore Lead-Free Solder Pros and Cons with Printed Circuit Corp
For years, our team has specialized in PCB assembly and electronic manufacturing. We have extensive experience in a wide range of industries and provide various services to best serve all our customers. From PCB assembly and box build to system integration and prototyping, we have you covered.
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