RoHS & REACH Compliant PCB Assembly
Introduction of Lead-Free PCB Assembly
We all know PCB assembly means soldering components on a printed circuit board, whether by SMT reflow soldering, by waving soldering, or by manually soldering. So it is obvious that lead-free PCB assembly means the solder used in PCB assembly does not contain lead (Pb) which is not RoHS compliant. so we all call it RoHS-compliant PCB assembly. To understand lead-free PCB assembly, or lead-free printed circuit board assembly, we had to know what is leaded solder and lead-free solder first.
Leaded solder is commonly used in the electronic PCB assembly industry for many years widely. Because it has very good solderability and is also cost-effective. The composition of tin and lead commonly used in leaded PCB assembly processing is Tin: 63%, Lead: 37%, or around Tin: 60, Lead: 40%.
Lead-free solder is more and more commonly used nowadays. The reason is lead (PB) is harmful to the human body and also not environmentally friendly. The typical type of lead-free solder is SAC305 usually, which contains: Tin: 96.5%, Silver: 3%, and Copper: 0.5%. Of course, there is a very minor percentage of other elements.
A practical standard lead-free solder (Tin) used in the PCB assembly process includes:
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Viasion has a skilled production team. We use lead-free technology to carry out the manufacturing. Our RoHS PCB board meet the requirements of environmental protection.
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Usage of Lead-Free PCB Assembly?
Lead-free PCB assembly is applied in RoHS-compliant electronic products. Lead-free PCB assembly has become an irreversible trend in the electronics assembly industry. With the gradual improvement of international environmental protection requirements, the lead-free process has become an inevitable process in the development of the electronics industry. Although the lead-free process has been implemented for so many years, there are still some enterprises using the leaded process, but the lead-free process will completely replace the leaded process, which is an inevitable result. So Lead-Free PCB Assembly are used in any electronics products in all industry areas.
When Should You Use Lead-free PCB Assembly?
PCBA Manufacturers are subject to RoHS standards. Manufacturing RoHs-compliant PCB assembly means replacing traditional lead-based solders with lead-free alternatives.
If you encounter the following situations, you may benefit from using lead-free PCB assembly.
Differences between Leaded and Lead-Free PCB Assembly
Please refer to the following main difference between leaded PCB assembly and lead-free PCB assembly (also RoHS PCB assembly):
How to Distinguish Lead-Free PCB Assembly and Leaded PCB Assembly?
How to judge whether a print circuit board is lead-free or not when we get a PCB? Since lots of customers need RoHS-compliant PCB assembly. Concerning this question, let’s discuss it from the following several aspects.
For experienced workers, it is easy to distinguish the PCBs soldered by lead-free solder or leaded solder. Because the color of the solder joint is different: the color of the leaded solder appears bright white, but the color of the lead-free solder looks darker and a little yellow.
Leaded solder contains 70% of tin and 30% of lead normally. But lead-free solder normally contains 96% of tin, 3% of silver, 0.5% of copper, and a little very low percentage of other elements.
Leaded solder is only used in the products allowed lead exists. But lead-free solder can be used in most electronic products. Lead-free solder is RoHS and REACH compliant, and can be exported to Europe and the United States.
With the introduction of the above aspects, you will quickly identify whether it is a lead-free PCB or not when you get a PCB.
6 Important Factors in Lead-Free PCB Assembly
Lead-free PCBA is more and more common by far. What should we do to produce qualified lead-free PCB? The following points are the things we need to pay close attention to:
For PTH assembly, the welding time should be controlled as accurately as possible. Generally speaking, it should be completed within a few seconds from heating the welding point to melting the solder and filling the welding point. If the time is too long, the flux on the welding point is completely volatile, and eventually loses the role of welding aid, or because the time is too short, the temperature of the welding point can not reach the welding temperature, so the solder can not fully melt, the solder spot is only a small amount of tin welding, resulting in poor contact, it is called the virtual welding phenomenon.
Why Does Leaded PCB Assembly Still Exist in the Industry?
We all know leaded printed circuit board assembly is not good for the human body, and also not good for the environment. But why does leaded custom PCB assembly still exist by far? The main reasons are as below. But in Viasion, we only produce lead free PCB assembly which is RoHS and REACH compliant.
What Should Consider If We Choose Lead-Free PCB Assembly?
For some customers, lead-free PCBA is not a must. So they may be confused about whether they should use lead-free assembly or leaded assembly on their products when they need custom PCB assembly services. The following introductions may be helpful to the customer to choose the right method.
First of all, lead-free custom PCB assembly is mainly about environmental protection, which is healthier for users and has a much lower impact on the environment. So if the products need to meet RoHS and REACH, the customer must choose lead-free electronic PCB Assembly. But since lead-free solder is more expensive, the assembly cost for lead-free assembly is a little higher than leaded assembly. So for customers, it is better to consider the use environment of the product need to used, the price, and the profit of the product, rather than blindly pursuing lead-free welding.
The welding temperature without lead is around 35 Celsius degree higher than that of with lead. In the SMT assembly process, the welding temperature is also higher than the Tg of the PCB substrate, and the lead-free welding temperature is higher than the lead welding temperature, which will cause the PCB easily thermal deformation and components damage when cooling if the TG of the PCB material is too low. So the PCB materials with higher Tg should be appropriately selected.
The lead-free welding process requires PCB with good heat resistance, high glass transition temperature Tg, low thermal expansion coefficient, and low cost. So the influence of high temperature on component packaging should be considered. Since the packaging material of traditional surface mounting components can meet the welding temperature of lead solder as long as it can withstand 240Celsius degrees, and the welding temperature of complex products can reach 260 Celsius degree in lead-free welding, whether the packaging of components can withstand high temperature is a problem that must be considered.
In addition, the influence of high temperature on the internal connection of the device should be considered. IC internal connection method has gold wire ball welding, ultrasonic pressure welding, and reverse welding methods, especially BGA, CSP, and composite components, modules, and other new components, their internal connection with the material is the same as the surface assembly of the solder, is also the use of reflow welding process.
From the point of view of cost, currently developed lead-free solder cost is higher than tin-lead alloy. Many people may think that the proportion of the cost of solder is very high. However, according to some statistics, PCB manufacturers generally control the cost of the solder to 0.1% of the total cost, especially for the high technology electronics/PCBs, so it will not have too much impact on the overall cost of the final product. So most customers choose lead free PCB assembly in their RoHS compliant PCB.
Characteristics of the Material Used to Replace Lead in Solder Alloy
Today, solder producers are still researching to find the most suitable metal to replace lead. To meet the 2 simple goals: the solderability is good and the cost is low. The following are the characteristics that need to be considered in choosing a substitution for lead.
Compatible with the electronic industry
Key Points in Lead-Free Solder Research
To protect our environment, all countries in the world call for green products, so more and more PCB factories are going to produce more PCB products with lead-free hot air solder level surface finish treatment. And SMT factories will choose the PCB with a lead-free hot air solder level to supply RoHS circuit board.
From a technical point of view, many and many countries pay attention to being lead-free. Many countries have lead-free solder research and development specialized institutions, these research and development institutions and solder manufacturers, have developed a variety of lead-free solder, and a considerable part of the experiment has been proven to be a substitute for tin-lead solder products. Key points in lead-free solder research are:
Some people have this concern “Will some factories add new toxic or harmful substances to the lead-free solder to remove the lead?” I understand this kind of concern. We should realize that such a practice is absurd and undesirable, and runs counter to environmental protection requirements. Others have the view that “Although we should pay attention to whether it meets environmental requirements, can we take its solderability and post-solder reliability lightly?” The answer is of course “NO”. What’s more, some people are concerned about the cost-effectiveness of lead-free solder. Through the above discussion, we can know what kind of lead-free solder will be more popular.
Production Environment of a Lead-Free PCB Assembly Workshop
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Frequently Asked Questions
Lead-free PCB assembly refers to the PCB assembly manufactured by a lead-free process. All materials, such as printed circuit board, components and solder, must be lead-free.
Lead-free PCB assembly is rapidly becoming the standard for PCBA manufacturing due to regulatory requirements, environmental concerns, and other reasons.
The following is a brief introduction to some processing points of the lead-free process.
1) The inspection of solder paste and PCBs:
The lead-free process requires inspection of the PCB and solder paste parameters to ensure that the lead-free materials are used.
Check the bill of materials first to ensure that the components are made of lead-free materials.
3) Solder paste printing:
In the step of printing solder paste, the lead-free stencil of the forming stage is placed on the circuit board and then printed with lead-free solder paste.
4) Pick and place components:
This is a pick-and-place operation, but the components used need to be identified and marked during the BOM verification phase. The machine or operator selects a labeled component and places it in a specified location.
5) Testing and packaging:
Test the solder joints in this step. Visual inspection is followed by AOI and X-ray inspection. Physical and functional tests are performed before packaging.
Both terms say the same thing: it means the assembled PCB boards are environmental friendly.
Lead free PCBA is short fro lead free printed circuit board assembly. It means PCB assembly without lead.
Improve environmental protection and ensure the sustainable development of the industry.
Significantly reduce or avoid health damage caused by using products containing lead.
Seen from the perspective of PCBA manufacturing, the main problem with lead-free PCB assembly is the effect on the circuit board caused by temperature rise. Rework of lead free PCB assembly is also more difficult.
We think the following factors are the more important ones in lead free board assembly: printed circuit board is lead free, solder bar or solder paste used in SMT assembly or PTH assembly is lead free, the whole lead free PCBA line is only prepared for lead free PCB assembly, then no lead remains in any tools or equipment.
Yes, we only supply lead-free PCB assembly because of environmental protection.