Why and How to choose proper surface finish type for your PCB

As we all know, PCB's have copper finishes on their surface. If they are left unprotected then the copper will oxidize and deteriorate, making the circuit board unusable. The surface finish forms a critical interface between the component and the PCB. The finish has two essential functions, to protect the exposed copper circuitry and to provide a solderable surface when assembling (soldering) the components to the printed circuit board.

The advantages and disadvantages of The main type of surface finish:

1) ENIG (Electroless Nickel Immersion Gold)

Electroless nickel immersion gold (ENIG) is a type of surface plating used for printed circuit boards. It consists of an electroless nickel plating covered with a thin layer of immersion gold, which protects the nickel from oxidation.

2) HASL (Hot Air Solder Leveling)

There’s two type of HASL,One is HASL with lead, the other one is HASL with lead free. HASL(LF) is a kind of environmental surface finish process without Pb. The price difference between HASL(with lead) and HASL(LF) is not that much, So HASL(LF) is widely used by engineers.

HASL is a conventional type of surface finish applied on PCBs. The PCB is typically dipped into a bath of molten solder so that all exposed copper surfaces are covered by solder. Extra solder is removed by passing the PCB between hot air knives. 

Gold plating is a method of depositing a thin layer of gold onto the surface of another metal, most often copper or silver (to make silver-gilt), by chemical or electrochemical plating. This article covers plating methods used in the modern electronics industry

3) Gold – Hard Gold:

OSP is a type of surface finish with transparent organic material participated. It uses a water-based organic compound that selectively bonds to copper and protects the copper until soldering 

4) OSP (Organic Solderability Preservatives)

Except those surface finish above, there are also some other ways, such as IMSN(Immersion Tin) ,Immersion Silver,ENEPIG ect.. PCBASTORE will guide you get your PCB surface well Finished!!!

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