Lead vs. Lead-Free Solder in PCB Manufacturing – 2024 Ultimate Guide

Hi friends welcome to the new post. Here we will discuss Lead vs. Lead-Free Solder in PCB Manufacturing – 2023 Ultimate Guide. The manufacturing of PCB board is important in electronic, and the best option to use lead and lead free solders is important now. Here we will discuss the main factors of lead and lead-free solder in PCB manufacturing, helping us to define the best option that aligns with industry standards and environmental considerations. So let’s get started with Lead vs. Lead-Free Solder in PCB Manufacturing

Introduction to Solder in PCB Manufacturing

Soldering is the main component in the PCB industry, which helps to make the connection between different components on board. Whether phone, computer, or any other device solder is best to help the work. Now there are two main types of solder options lead and lead-free solder used in industry.

What is the Lead and Lead-free Solder?

Lead Solder

The lead solder or soft solder comes with tin and leads as main components. Its melting point is  (183 °C or 361 °F) less thatn lead-free solder which is a better featues than lead-free solder since has a low thermal effect on the PCB board and connected components.

With the lower thermal damage to the PCB board leaded solder offers smooth joints that are brighter than lead solder and results quality problems.

Lead-free Solder

The lead-free solder used by waste electrical and electronic equipment directive in 2006 due to health issues. Contrary to leaded solder lead-free solder has a different composition and is made with a mixture of different metals like tin, copper, silver, and nickel. But tin with copper is mostly used. The melting point of this solder is about  50 to 200 °C. The best wetting feature in lead-free solder best for about  2% flux by mass.

Types of Lead-free Solder

• Tin Copper:
  • This mostly used solder type, copper provides mechanical strength of solder.
• Tin-Silver: 
  • Silver is the best conductor. It reduces oxidation, offers good corrosion resistance, and increases conductivity.
• Tin-Zinc: 
  • Zinc has a low melting point.  some combination with tin reduces the melting point of lead-free solder and it is less costly..

Difference Between Lead and Lead-Free Solder? 

• Lead-free solder comes with a high melting point of about 50 to 218 degrees and lead solder has a fixed melting point of about 183 degrees.
• A low melting point helps to work with leaded solder and results in less heat affect on the board and components connected, with time. it also causes some technical problems due to softness.
• Though lead-free solder comes with high corrosion resistance, it has lower wettability than leaded solder which causes joint unreliability.
• Leaded solder is a cost-effective solution that offers smooth featues and results in less heat damage to the board it is harmful to human health and the environment and lead free solder is safe but difficult to handle

 Properties of Lead vs. Lead-Free Solder

 Lead-free Solder Has a Higher Melting

Lead solder has a melting point of about 1830 centigrade and lead-free solder has a melting point of about 2170C. So high melting points provdies these features of lead-free solder.

• the high temperature of lead-free soldering oxides solder faster than the low temperature of lead soldering.
• The board that has the plastic package and electronic capacitors are some components that are negatively affected by the high soldering temperature of lead-free solder.
• The high temperature of lead-free solder has component stress, so low dielectric components can affected.
• Lead-free solder components have different soldering surfaces. Manufacturers use tin on this surface type since it is a cost-effective solution. But tin causes a small oxidation coating on externally that causes electroplating.

Rusting

Rusting is the main issue for PCB boards. it reduces the working life of the board and generates other technical problems such as short circuits.

So it is an important feature to study. lead solder is best in some conditions but for rusting lead-free solder has high corrosion resistance due to low passivation curent density, and low corrosion current density after the breakdown of the passivation film.

Lead free solder is the best option for PCB board that comes with highly humid areas.

Health problem

Lead-free soldering is fastly covering uses due to the toxic nature of lead and its accumulation in the human body also from small and prolonged exposures.

Lead quickly enters in our body through the skin, mouth or nose.

The paint and gasoline sectors come with lead-free service. But solder is still in use. In an industry that has high lead emissions, workers are vulnerable to the effects of lead since they quickly inhale it or touch contaminated surfaces.

Cost

Leaded solder is cost-effective solution than lead-free solders. This is due to lead is a tenth of tin cost making lead solder easy to buy. Some manufacturers also replace tin with silver in lead-free solders, making it costly.

Lead or Lead-free: Which One is Better to Use?

• irrespective ot health and environmental details on lead electronics, Aviation corporation has made study ton use of lead in different consumers electronics.
• it is found that there is details of supporting details that lead use in electronic devices resulting in harmful effects on our life.
• The reality is that for electronic rework, the used lead does not have a bad effect on our lives.
• Use lead solder if it get in nearby stores. Since it is easy to use and has a low melting point and results in some quality issues with joints.
• The main reason we should use lead-free solder is if the government has banned lead use.
• With that, you can also use if it your products are for  European countries.
• note that lead used in manufacturing is not enough to affect our lives.

Disadvantages of Lead-Free Solder.

1. Lead free solder comes with tin content for replacing lead metal, but it increases melting point. So note that there is a need to melt solder to wet pads to bond components on board. Soldering for this high temperature affects the components but can damage plastic packages, electrolytes, capacitors, and components with low dielectric constants. High heat can also damage the board by applying signal track pads from dielectric surfaces.
2. Lead free solder does not flow freely on the board contact pad and connects them more easily then lead solder. So solder joints can have less tensile strength, self-regulation, and shear capacity.
3. Lead free solder makes alloy deposits, surface oxides, and flux impurities, all can affect solder joints by making weak electrical connections.
4. High ten content in lead-free solder can make TIn Tin whiskers when melt cools and become solid. These conductive structures can connect neibouring pins or pads, and short-circuiting boards.
5. Tin is safer for the environment than lead but has a high cost, which makes solder-free solder high cost. Some lead-free solder types come with silver which is a higher cost than tin

Lead Solder vs. Lead-Free Solder

Lead free solder was not spread out at the time of reflowing. It makes stronger bonds without affecting like rapid stencil wear. Lead soldering is likely to result in voids or fillet lifting. Overall solder without lead produces good results for boards used in electronics.

What are Lead and Lead-Free Solders Made Of?

Lead solder is a metallic alloy made with lead and tin as base components. it is used as SNPB solder. Lead pipes and water supply pipes are connected with lead solder banned due to hazardous effects. The lead alloy melting point is 183 degress.

The main benefit of using lead solder is

• it is easy to work in temperature conditions.
• It has resistance to shock
• There are some inner errors in the structure after the cooled

Lead-free solder is made with the use of differnt metals. Some components in lead-free solder are tin, copper, silver nickel, and zinc. A commonly used tin-copper combination that has a melting point of about 217 degrees.

The high melting point makes lead-free solder to difficult work.  So the main reason manufacturers are moving to the use of lead-free solder for removing lead in  electronic

 most common types of lead and lead-free solders: