What is tin spray? The difference between lead-free tin spray and lead-free tin spray on PCB

Date：2023-01-12 15:22:34 Views：1303

The tin spraying process is a process of spraying tin on PCB and blowing it flat with hot air. It has excellent solderability. There are two kinds of tin spraying processes: lead tin spraying and lead-free tin spraying. To help you understand in depth, this article will summarize the relevant knowledge of tin spraying. If you are interested in the content to be covered in this article, please read on.

Tin spraying is a step and process flow in the production and manufacturing process of PCB board. Specifically, the PCB board is immersed in the molten solder pool, so that all exposed copper surfaces will be covered by solder, and then the excess solder on the PCB board will be removed by the hot-air cutter. Because the surface of the circuit board after tin spraying is the same material as the solder paste, the welding strength and reliability are better. However, due to its processing characteristics, the surface flatness of tin spraying treatment is not good, especially for small electronic components such as BGA packaging type, due to the small welding area, if the flatness is poor, it may cause short circuit and other problems, so a process with good flatness is needed to solve the problem of tin spraying plate.

Then let's explain the difference between lead-free tin spray and lead-free tin spray on PCB

Security differences

The first is the difference in safety. The first tin spraying process is only lead tin spraying. Lead-free tin spraying is extended from lead tin spraying process. The reason is that lead tin spraying has safety defects. The solder used for lead tin spraying contains lead, which is toxic. Long-time exposure will not only harm human health, but also pollute the surrounding environment,

In order to ensure the health of operators and meet the national environmental protection policy, lead-free tin spraying came into being. In terms of safety, the harm of lead-free tin spraying process to human body and the environment will be reduced to the minimum, in line with the RoHS of the European Union. With the development of lead-free tin spraying process, now lead-free tin spraying has been gradually eliminated;

Different melting points

The lead content of lead tin with lead is different from that of lead-free tin. The lead content of lead tin with lead is generally 37, that is, the proportion of tin and lead is 64:37, while the lead content of lead-free tin is about 0.5, mainly for other metal alloys, and the melting point of lead is different from that of other metals, so the melting point of lead spray tin and lead-free spray tin will also be different; Generally, the melting point of lead-free tin spray is about 218 ℃, while that of lead-free tin spray is about 183 ℃;

Performance difference

Because the lead component will improve the activity in the welding process, the solderability of the board after the lead spray tin treatment is better than that of the lead-free spray tin process. However, because the lead-free spray tin process has a higher melting point, the lead-free spray tin is better than the lead-free spray tin in terms of welding firmness and wettability;

In addition to the above differences, the cost of lead-free tin spraying is much higher than that of lead-free tin spraying. In terms of appearance, the appearance of lead-free tin spraying is brighter and the gloss of lead-free tin spraying is darker.

The above is the PCB lead-free tin spraying and lead-free tin spraying organized by Chuangxin Testing. I hope it can help you. Our company has a team of professional engineers and industry elites, and has three standardized laboratories with an area of more than 1800 square meters, which can undertake various test projects such as electronic component testing and verification, IC authenticity identification, product design and material selection, failure analysis, functional testing, factory incoming material inspection and tape weaving.