Lead-Free PCB Assembly

As printed circuit boards (PCBs) are primary unit in virtually all electronics systems, the RoHS directive applied directly manufacturing is circuit board assembly, where RoHS compliance means replacing traditional lead-based solder with a lead-free alternative. But what does this mean for your PCB circuit board development? Before addressing this question, let’s take a look at both leaded and lead-free printed circuit board assembly. Then, you will be better prepared to decide whether you should use lead-free PCB assembly.

Leaded vs. Lead-Free Circuit Board Assembly

During the assembly of your circuit boards, the components, either SMT or thru-hole, are attached through a soldering process. For decades, most solder used for PCB assembly (PCBA) has be a tin-lead (Sn-Pb) alloy. Popular tin to lead ratios are 60/40 and 63/37, which have melting point temperatures of 188°C and 183°C, respectively. During reflow soldering, which is the preferred method for attaching SMD packages, temperatures up to 235°C may be reached as solder changes to a liquid form prior to cooling down.

Temperatures for lead free PCBA are typically higher than for Sn-Pb solder. For example, the melting point temperature for tin-silver (Sn-Ag) is 220°C for 96.5/3.5 and 240°C for 95/5, respectively. Reflow oven temperatures may peak at 250°C. These higher temperatures have implications for circuit board construction and component selection. If circuit board materials are selected with decomposition temperature that is too low, irreversible damage may occur following exposure to the elevated temperatures involved in lead free PCB assembly. Care must also be taken when choosing components to ensure there is no damage, especially during reflow where high temperatures are present on the circuit board for extended periods of time.

From a PCB manufacturing perspective, the major concern for lead free circuit board assembly is PCB damage due to higher temperatures. Rework is also more difficult. Materials are another consideration as substrates and laminates must be selected based upon their temperature attributes. Before prematurely deciding that opting for lead free circuit board is not justifiable, however, let’s explore other reasons for making the change.

Lead free PCB assembly is used in RoHS-compliant electronic products. Lead free PCB assembly has become an irreversible trend in the PCB assembly industry. With the gradual improvement of international environmental protection requirements, the lead-free PCB assembly process has become inevitable in the development and production of the electronics industry. So generally speaking, lead-free PCB assembly is used in most electronic products and will be more and more commonly used. Lead free PCB assembly manufacturers are subject to RoHS standards. Manufacturing RoHs-compliant PCB assembly means replacing traditional lead-based solders with lead-free alternatives.

Although the lead-free PCB assembly process has been implemented for so many years, there are still some companies using the leaded process due to its excellent solderability, but the lead-free PCB assembly process will be more and more used worldwide because it is environment friendly. So should we use leaded or lead-free PCB assembly in our devices? If you encounter the following situations, you may benefit from using lead-free PCB assembly.

You Should Use Lead Free Circuit Board If…

If any entry in the list below describes your situation, you will likely benefit from using lead free PCB assembly.

• Your products may be sold in countries that have regulatory requirements, such as the EU.
• Your state or local government mandates a lead-free circuit board and assembly manufacturing process, such as in California.
• The electronics manufacturing for your circuit boards requires that you meet regulatory standards, such as IBM and Hewlett Packard.
• You are concerns about the health risks for those who work with and use lead-based products.
• You understand the breakthroughs in smaller PCB fabrication that lead-free PCB assembly has made possible and want to promote the continued advancement in this area.
• You recognize the thrust for green electronic manufacturing and want to attract customers that place a high premium on these issues.

Ensuring that your circuit boards are fabricated to meet the RoHS requirements means that you must ensure the contract manufacturer (CM) that you select has a defined lead-free process, including soldering, materials, components, solder mask, and surface finish. Lead free circuit board Assembly is rapidly becoming the standard for PCB fabrication. This is due to regulatory requirements, environmental concerns, and other reasons.

QFPCB is recognized as a professional and reliable electronics contract manufacturing (ECM) provider for fast, high-quality PCB prototyping and low to high volume PCB and assembly production. We utilize advanced equipment and a software-based process to manufacture circuit boards that meet your regulatory requirements. And our range of PCB capabilities and PCB assembly capabilities allow us to ensure that your PCB design objectives intent are satisfied, while providing you with the best manufacturing experience.

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.

Appearance Difference
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.

Composition Difference
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.

Usage Difference
Leaded solder is only used in the products allowed lead exists. But lead-free solder for lead free PCB assembly 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.