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The difference between HASL and HASL lead-free

Laikas: 2018-08-13

One of the commonly used processes for surface treatment of PCB boards is: HASL, also called "hot air leveling", which is an important process in the production of pcb circuit boards. The main soldering of pcb circuit boards is lead-free HASL. There are two types of lead-spray tin, which are also commonly used. They are widely used in circuit board manufacturers. The quality of spray tin directly affects the quality of subsequent customers' welding, so spray tin has become the focus of quality control for circuit board manufacturers. , below to introduce the characteristics and related basic knowledge of pcb spray tin type.

1.PCB surface treatment spray tin features:

Spraying tin in PCB circuit board is the most commonly used process. This kind of process is more practical. It has good welding performance, good anti-oxidation effect, and the price is relatively affordable. There are also two types of lead and lead-free distinctions in PCB circuit board:

2.PCB surface treatment spray tin type:

First, lead-free HASL. Lead-free HASL is an environmentally friendly process. It is very harmful to the human body. It is also a process advocated at this stage. The lead content in lead-free tin is not more than 0.5, and the lead-free HASL has a high melting point, so that the solder joint is firm. In essence, lead spray tin and lead-free tin spray are a process. Only the purity of lead is different. Lead-free tin is a more environmentally friendly and safer environment for the human body, and it is also a development trend in the future. It is recommended that you use it. The characteristics and shortcomings of the two types of process hasl and lead-free hasl are introduced. Among them, hasl is easy to use, but it is unsafe, environmentally friendly and harmful to the human body. Therefore, it is recommended to use lead-free hasl, non-toxic and harmless, is also the surface treatment process currently advocated.

Second, HASL. The so-called lead-spraying tin means that tin is prepared according to a certain ratio. Lead will increase the activity of the tin wire during the welding process. Lead-tin wire is better than lead-free tin wire, but lead is poisonous and has lead. Lead is harmful to humans; lead eutectic temperature is lower than lead-free. Specifically, it depends on the composition of the lead-free alloy. The eutectic like SNAGCU is 217 degrees, and the soldering temperature is eutectic temperature plus 30 to 50 degrees. It depends on the actual adjustment. The lead eutectic is 183 degrees. Lead in mechanical strength, brightness, etc. is better than lead-free. Therefore, it is not environmentally friendly to have lead tin, and there is a certain discrepancy with the environmental protection advocated by the world. Therefore, lead-free spray tin was born.

So how to distinguish between lead and lead-free surface treatment, this is simple, take a piece of white paper to gently wipe the pad, the position of the tin, if it is black, there is lead spray tin, no black is no Lead spray tin.

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