1. Hot air leveling (HASL)
Hot air leveling also known as hot air solder leveling (commonly known as HASL), it is the PCB surface coated with molten tin (lead) solder and heated compressed air leveling (blow) process, so that it can form a layer of copper oxidation resistance, but also provide a good weldability coating layer.The solder and copper form copper Sikkim intergeneric compound at the junction of hot air conditioning.PCB for hot air rectification usually to sink in the molten solder;The knife blows the liquid solder before it solidifies.The knife minimizes the meniscus of solder on copper surfaces and prevents solder bridging.
2. Organic weldable protective agent (OSP)
OSP is printed circuit board (PCB) copper foil surface treatment in accordance with the requirements of the RoHS directive a process.OSP is the abbreviation of Organic Solderability Preservatives, which can be translated as Organic welding film, also known as copper Preservatives, also known as Preflux in English.Simply put, OSP is on the clean bare copper surface, to grow a chemical method of organic skin film.This film has oxidation resistance, heat shock resistance, moisture resistance, to protect the surface of copper in the normal environment no longer continue to rust (oxidation or vulcanization, etc.);However, at subsequent high welding temperatures, this protective film must be easily removed by the flux quickly, so that the exposed clean copper surface can be combined with the molten solder in a very short time to form a solid solder spot.
3, full board nickel gold plating
Nickel plating is the first layer of nickel plating on the PCB surface conductor and then another layer of gold plating, nickel plating is mainly to prevent the diffusion between gold and copper.There are now two types of nickel gold plating: soft gold (pure gold, gold does not look bright) and hard gold (smooth and hard, wear-resistant, containing cobalt and other elements, gold looks bright).Soft gold is mainly used for chip packaging gold line;Hard gold is mainly used for electrical interconnection at non-welded locations.
4, ENIG (Chemical gold)
ENIG (Chemical gold) is a thick layer of good electrical properties of nickel gold alloy on the copper surface, which can protect the PCB for a long time.It also has environmental tolerance that other surface treatment processes do not.It also prevents the dissolution of copper, which would be beneficial for lead-free assembly.
5, Chemical Tin
Since all solder currently is based on tin, the tin coating can be matched to any type of solder.Sinktin process can form flat copper sikjin intergeneric compound, which makes sinktin has as good weldability as hot air leveling without the headache of flatness.Chemical Tim pcb can not be stored for too long, assembly must be according to the sequence of sink tin.
6, Chemical Silver
The silver deposition process is between organic coating and electroless nickel/gold deposition.Silver remains solderable even when exposed to heat, humidity, and pollution, but loses luster. Chemical silver does not have the physical strength of electroless nickel/Chemical gold because there is no nickel underneath the silver layer.
7. Chemical nickel palladium
Chemical nickel palladium Compared with chemical gold, there is an extra layer of palladium between nickel and gold. Palladium can prevent the corrosion caused by displacement reaction and make full preparation for submerged gold.Gold covers palladium tightly, providing a good contact surface.
8, Electroplate hard gold
In order to improve the wear resistance of the product and increase the number of plug and pull electroplating hard gold.As the user requirements are more and more high, the environment requirements are more and more strict, surface treatment technology is more and more, in the end should choose the kind of development prospects, the surface treatment technology with stronger versatility, it seems a little dazzling, confusing.It is impossible to predict exactly where PCB surface treatment technology will go in the future.Anyway, meeting user requirements and protecting the environment must be done first!