The full name of ENIG is Electroless Nickel/Immersion Gold, which is abbreviated as ENIG. In Chinese, it is called Electroless nickel immersion gold, chemical nickel gold or precipitated nickel gold. It is a type of PCB surface treatment process. ENIG is mainly used for surface treatment of circuit boards. It is used to prevent copper oxidation or corrosion on the surface of circuit boards. It is also used for welding and contact applications (such as buttons, gold fingers on memory modules, etc.)
(1) Surface smoothness (relative to tin spraying, etc.);
(2) It can be soldered, wired (gold wire, aluminum wire), and has good heat dissipation;
(3) Long storage time (more than 1 year in Vacuum packing);
(4) The SMT process is resistant to multiple reflow soldering and can be reworked multiple times.
(5) The thickness of ordinary plate nickel is generally 120-200u “, and the thickness of gold is 1-5u”; The general thickness of the nickel plated wire is 10u “or more, and the nickel thickness is 150u” or more.
HASL (Hot Air Solder Level)
The HASL process, commonly known as tin spraying or hot air leveling, involves immersing a PCB in molten solder and then blowing off excess solder on the surface and holes through strong hot air to obtain a bright coating. One method is to use lead-tin alloy, with a lead sprayed tin furnace temperature of around 240 degrees Celsius. The other method is to use pure tin, which is prohibited in many European countries due to the significant harm of lead to human health. Therefore, it is now popular to use pure tin or lead-free spray tin (LFHASL). The lead-free furnace has a temperature of up to 300 degrees Celsius, coupled with high temperature and high corrosion in the operating environment, which poses great harm to PCBs. Moreover, the surface smoothness is far inferior to that of chemical treatment. Advantages: good soldering performance, good reliability. Disadvantages: poor leveling and plug hole problems, high requirements for green oil, plate and lamination bonding force, and hidden dangers of plate bending and warping. The method to avoid this is to use high Tg plate material and PP, Only the cost of sheet metal increases by 100 yuan/m2 (calculated based on double-sided panels).
The most widely used surface treatment is HASL (Hot Air Solder Leveling). The production process involves immersing the PCB in molten solder and then using a hot air knife to remove excess parts, leaving the solder layer as thin as possible. This is usually the cheapest to complete and a great choice for general boards. One disadvantage of HASL is that even after the hot air knife has removed as much excess as possible, the meniscus of the solder still causes the edges of the solder pad to become slightly rounded. This may lead to inaccurate placement of components and visual issues with reference markings.
ENIG vs HASL, which one you prefer to choose?
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