ALD PCB can offer following outstanding pcb surface finishing technologies for customers: HAL, HAL LF, OSP, ENIG, Gold Finger and so on.

Hot Air Solder Leveling or HASL Lead-free

Solder Mask over bare copper (SMOBC) and HAL-lead free (RoHS) is a common final surface treatment. it's a way of coating exposed copper with solder via inserting a panel into a bath of molten tin solder then transfering the panel quickly over a series of hot air jets.

OSP (Organic Solderability Preservatives)

OSP is different from other PCB surface treatments: it is an isolated layer between the copper and air; simply, OSP is the method to grow a layer of organic chemical coating on the clean bare copper surface. This membrane with the feature of oxidation, thermal shock and moisture resistance, can protect the copper surface in the normal environment without rustiness (oxidation or sulfidation, etc.); at the same time, can be easily removed by the flux in the following welding temperature. OSP is very robust and is designed for lead-free assembly. it can handle multiple heat cycles and have a one year shelf life.

ENIG (Electroless Nickel/Immersion Gold)

The ENIG surface finish is considered to be the best fine pitch surface and lead-free option in the industry. Its good electrical properties of nickel-gold alloy can protect PCB in a long-term; just like OSP as a rust barrier layer which can offer excellent shelf life for PCB. In addition it also has outstanding patience of the environment. The typical Nickel thickness is 75 micro inches and 3-5 micro inches of gold. Disadvantages include; limited availability, higher cost. 

Gold Finger

In order to plug the connector as an external connection interface, gold finger process technology is the solution; the finger is coated by a layer of the thick, hard, anti-plug gold through plating (note: it’s different from Electroless Nickel/Immersion Gold).