The difference between lead-free and lead-free PCB materials
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When receiving users, we will encounter some problems more or less. The most common user consultation is about the speed of plate making and whether the quality can be guaranteed. In fact, when a factory's production line is mature enough, speed will not affect quality. The factors affecting quality are mainly the selection of raw materials and the internal quality control of the factory. At present, the domestic board grades are arranged from high to low: Shengyi Jiantao and the commonly used Guoji materials. Shengyi S1141 (TG value 140) board, Jiantao and Guoji material TG value is 130. The ink is also the best Sun 2000 series ink. Of course, the precision of the board is mainly determined by the production machines of each factory. Some users do not understand the difference between leaded tin spraying and lead-free tin spraying. Let's first understand what tin spraying is: One of the most common pad coating forms of circuit board surface treatment is tin spraying. The standard thickness of tin spraying in the industry is 20uM, but tin spraying is divided into leaded and lead-free, and there are differences between the two: 1) From the meaning of the words on the surface of leaded and lead-free, one is environmentally friendly and the other is not environmentally friendly. The lead content of lead reaches 37 and the lead-free content does not exceed 5. And lead is still harmful to the human body, but lead-free is not harmful. 2) But from the appearance color: it can also be distinguished, the lead-sprayed solder pad is brighter, and the lead-free solder pad is darker. And the lead-sprayed solder pad has better wettability than the lead-free solder pad, and the cost performance is relatively high. If the price is concerned, it is recommended to choose the lead-sprayed solder pad. 3) In terms of performance. If the melting point of lead is around 183 degrees, then the temperature of the tin spray furnace needs to be controlled at 245 to 260 degrees, the peak temperature needs to be controlled at 250 degrees, and the reflow temperature is between 245 and 255 degrees. If the melting point of lead-free is around 218 degrees, then the temperature of the tin spray furnace needs to be controlled at 280 to 300 degrees, the peak temperature needs to be controlled at 260 degrees, and the reflow temperature is between 260 and 270 degrees. Lead will increase the activity of tin during the welding process. Lead-tin wire is easier to use than lead-free tin wire, and the melting point of lead-free tin spray is higher than that of lead-free tin spray, and the welding point will be much stronger. 51, 51)] The above is the difference between lead-free tinning and lead-free tinning that I know about. However, many countries now require environmental protection, so it is recommended to use lead-free.
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