There are generally two processes for PCBA processing, one is the lead-free process, and the other is the lead-based process. Everyone knows that lead is harmful to humans, so the lead-free process meets the requirements of environmental protection and is the general trend and an inevitable choice in history. Ucreate PCB CO LTD is engaged in the processing business of SMT OEM materials. We only do PCBA processing with lead-free technology. From a practical point of view, based on many years of industry experience, we do not believe that PCBA processing factories with less than 20 SMT lines have the ability to accept both lead-free and lead-based SMT processing orders, because the distinction between materials, equipment, and processes has greatly increased. The cost and difficulty of management, our SMT factory has 6 SMT lines, customers cover 50 countries around the world, and our lead-free process is deeply recognized by customers.

So, do you know the difference between lead and lead-free? Below I put forward a few points so that you can choose the correct lead-free PCBA manufacturer.

1. The alloy composition is different: the tin-lead composition of the common lead-based process is 63/37, while the lead-free alloy composition is SAC 305, that is, Sn: 96.5%, Ag: 3%, Cu: 0.5%. The lead-free process cannot absolutely guarantee that it does not contain lead at all, but only contains very low levels of lead, such as lead below 500 PPM.

2. Different melting points: The melting point of lead and tin is 180°~185°, and the working temperature is about 240°~250°. The melting point of lead-free tin is 210°~235°, and the operating temperature is 245°~280°. According to experience, for every 8%-10% increase in tin content, the melting point increases by about 10 degrees, and the operating temperature increases by 10-20 degrees.

3. Different costs: Tin is more expensive than lead. When the equally important solder replaces lead with tin, the cost of the solder increases significantly. Therefore, the cost of the lead-free process is much higher than that of the lead-based process. Statistics show that the tin bar used for wave soldering and the tin wire used for manual soldering are 2.7 times more expensive than the lead-based process. The solder paste used for reflow soldering is 2.7 times higher than that of the lead-based process. The cost increases by about 1.5 times.

4. Different processes: The lead process and lead-free process can be seen from the names. But when it comes to the specific process, the solder, components and equipment used such as wave soldering ovens, solder paste printers, soldering irons for manual soldering, etc. are all different. This is also the main reason why, as mentioned earlier, it is difficult to process lead-based processes and lead-free processes at the same time in a small-scale PCBA processing factory.

Differences in other aspects such as process window, weldability, environmental protection requirements, etc. are also different. The lead-based process has a larger process window and better solderability, but because the lead-free process is more in line with environmental requirements, and with the continuous advancement of technology, lead-free process technology has become increasingly reliable and mature.

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