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The difference between lead-tin PCB and lead-free tin PCB?
2020-11-06
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Author:Dag      Share

Process requirements in PCB production are a very important factor, which directly determines the quality and positioning of a PCB.

For example, spraying tin and immersion gold, relatively speaking, immersion gold is to face high-end PCB. Immersion gold is relatively high relative to cost due to its good quality.

Therefore, many customers choose the commonly used tin spraying process. Many people know the tin spraying process, but they don't know that tin is divided into lead tin and lead-free tin.


Today, ipcb will tell you in detail the difference between lead-tin PCB and lead-free tin PCB for your reference.


1. From the surface of tin, lead-tin is brighter, and lead-free tin (SAC) is relatively dim. The wettability of lead-free is slightly worse than that of lead-free.


2. Lead in lead is harmful to human body, but lead-free is not. The leaded eutectic temperature is lower than that of lead-free PCB. How much depends on the composition of the lead-free alloy,

The eutectic of SNAGCU is 217 degrees, and the welding temperature is the eutectic temperature plus 30-50 degrees. It depends on actual adjustments. The leaded eutectic is 183 degrees. Lead is better than lead-free in mechanical strength and brightness.


lead-free tin PCB

Lead-free tin PCB

3. The lead content of lead-free tin does not exceed 0.5, and the lead content reaches 37.


4. 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, but lead is toxic, and long-term use is not good for the human body, and the lead-free tin will have a higher melting point than the lead-tin. This makes the solder joints much stronger.


5. What is the difference between lead-free tin-sprayed PCB and lead-sprayed tin-sprayed PCB? What is the temperature?

5.1, PCB lead-free tin spraying belongs to the environmental protection category and does not contain harmful substances "lead", the melting point is about 218 degrees; the temperature of the tin spraying furnace needs to be controlled at 280-300 degrees; the peak temperature needs to be controlled at about 260 degrees; the reflow temperature 260-270 degrees.


5.2. PCB with lead and tin spray does not belong to the environmental protection category. It contains harmful substances "lead", with a melting point of about 183 degrees; the temperature of the tin spray furnace needs to be controlled at 245-260 degrees; the peak temperature needs to be controlled at about 250 degrees; over. Reflow temperature 245-255 degrees