What is the difference between lead-free tin spraying and lead tin spraying on PCB?
Process requirements in circuit board production are a very important factor, which directly determines the quality and positioning of a PCB board. For example, spraying tin and immersion gold, relatively speaking, immersion gold is a high-end board. Immersion gold is relatively high relative to cost due to its good quality. Therefore, many customers choose the most commonly used tin spraying process.
Many people know the tin spraying process, but they don't know that tin can be divided into lead tin and lead-free tin. So, what is the difference between lead-free tin spraying and lead tin spraying on PCB circuit boards?
1. Lead-free tin spraying is an environmentally friendly process and does not contain harmful substances "lead". The melting point is about 218 degrees; the temperature of the tin furnace must be controlled at 280-300 degrees; the temperature of wave soldering must be controlled at about 260 degrees; over reflow soldering The temperature is around 260-270 degrees.
2. Lead spraying is not an environmentally friendly process, and contains harmful substances "lead", with a melting point of about 183 degrees; the temperature of the tin furnace must be controlled at 245-260 degrees; the temperature of wave soldering must be controlled at about 250 degrees; the temperature of over reflow soldering Around 245-255 degrees.
3. From the surface of tin, lead-tin is brighter, and lead-free tin is dull; the wettability of lead-free board is a little bit worse than that of leaded board.
4. The lead content of lead-free tin does not exceed 0.5, and the lead content of leaded tin reaches 37.
5. Lead will increase the activity of the tin wire during the soldering process. The lead-tin wire is better than the lead-free tin wire; however, lead is poisonous, and long-term use is not good for the human body. Lead-free tin has a higher melting point than lead tin, and the solder joints will be much stronger.
6. In the surface treatment of pcb boards, the price of lead-free tin spraying and lead tin spraying is usually the same.
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