Simple PCB surface treatment ways

Foreword: PCB surface treatment technology refers to the PCB components and electrical connections on artificial forming a layer and substrate mechanical, physical and chemical properties of different surface processing methods.Its purpose is to ensure the PCB good weldability or electrical performance.Because of copper in air tend to exist in the form of oxide, seriously affect the weldability and electrical properties of PCB, so need to surface treatment of PCB.

The common way of surface treatment are the following:

1, hot air leveling

In the PCB surface coating heating molten tin lead solder and compressed air leveling play (flat) process, to form a layer of copper oxidation resistance and can provide good weldability of the coating layer.Hot air the usual solder tin and copper in the junction copper compounds, its thickness is about 1 ~ 2 mil.

2, there are writers oxidation (OSP)

On clean bare copper surface, a layer of organic chemical method to skin membrane.Impact the membrane oxidation resistant, heat resistant, moisture resistant, to protect the copper surface in normal environment does not continue to rust (oxide or sulfide, etc.);Must be in the subsequent welding heat again at the same time, can easily be quickly removed by flux, so that the welding;

3, chemical nickel gold

On the copper wrapped a thick layer of, good electric properties of nickel and gold alloy can be long-term protection of PCB.Not only as rust like OSP blocking layer, it can in the PCB in the process of long-term use of useful and achieve good performance.It also has other surface treatment process does not have the patience to the environment;

4, chemical silver

Between OSP and electroless nickel/immersion gold, the craft is simple, fast.Exposed to the hot, wet and pollution of the environment, still can provide good performance and keep good weldability, but will lose its luster.Because there is no nickel silver layer below, so heavy silver does not have the chemical plating nickel/gold leaching all good physical strength;

5, electroplating nickel gold

On the PCB surface conductor plating first again after a layer of nickel electroplating a layer of gold plating nickel mainly is to prevent the spread between gold and copper.Now there are two types of electroplating nickel gold: soft gold plating (gold, gold does not look bright) and hard gold plating, surface smooth, hard, wear-resisting, containing cobalt and other elements, the surface looks more light).Soft gold play gold wire is mainly used in chip packaging;Hard gold is mainly used in the welding of electrical interconnection (e.g., gold finger).

6, mixed PCB surface treatment technology

Choose two or more than two kinds of surface treatment, surface treatment methods of common forms include: heavy nickel gold + anti-oxidation, gold + heavy nickel plating nickel, plating nickel gold + hot air leveling, heavy nickel gold + hot air leveling.

All forms of the surface treatment of hot air leveling (lead-free)/lead is the most common and the cheapest way to handle it, but please note that the European Union RoHS regulations.

RoHS: RoHS is a compulsory standards set by the eu legislation, it is the full name of "about limit use of certain harmful components in electrical and electronic equipment directive (Restriction of Hazardous Substances).This standard has been started on July 1, 2006 formally implemented, it is mainly used for electrical product specification material and craft standard, make it more conducive to human health and environmental protection.The purpose of this standard is to eliminate electrical electronic products in the lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PCBS) and polybrominated diphenyl ether, a total of 6 substances, and the key specifies the amount of lead that the should not exceed 0.1%.