PCB surface treatment process refers to the PCB board components, electrical connections on the artificial formation of a layer, and the substrate's mechanical, physical, and chemical properties of the surface layer, the core purpose is to ensure that the PCB has a good solderability and electrical properties. Common PCB surface treatment technology, including hot air leveling (HASL), organic coating process (OSP), chemical nickel plating/immersion gold (ENIG), immersion silver process, immersion tin process, and other nickel gold plating and chemical palladium plating process.
1, hot air solder leveling (HASL) is a traditional PCB surface treatment technology, through the PCB surface coated with a layer of molten solder, and the use of hot air to make it flat. Applicable to SMT process, lead-free soldering, mature process, low cost, easy to operate, suitable for general requirements of electronic products, particularly thick or thin boards have limitations, not suitable for contact switch design.
2、Organic coating process (OSP) is a thin layer of organic protective film coated on the surface of the PCB, this film can prevent the oxidation of copper foil, and improve solderability. Suitable for lead-free soldering and SMT, low cost, environmentally friendly, OSP process is environmentally friendly, low cost, suitable for short-term storage and soldering of PCBs, the limitations of the number of reflow soldering, not suitable for crimping technology, wire bonding, and storage conditions require high.
3, chemical nickel plating/immersion gold (ENIG) is a layer of nickel chemically plated on the surface of the PCB, and then immersion gold treatment. Applicable to PTH (plated through-hole), flat surface, lead-free, good solderability and corrosion resistance, expensive, non-reworkable, long shelf life, suitable for high-density, fine-pitch electronic products.
4, the immersion silver process is the formation of a layer of silver on the surface of the PCB, with good conductivity and solderability. High solderability, good surface flatness, low cost and lead-free (RoHS compliant), low contact resistance, suitable for high-frequency circuits, high storage requirements, silver is easy to oxidize, easy to be contaminated, short assembly window after removing from the package, affecting solderability and corrosion resistance.
5, immersion tin process is coated with a layer of tin on the surface of the PCB, suitable for fine pitch / BGA / smaller components, excellent flatness can be achieved, medium cost, good solderability, but poor corrosion resistance, suitable for occasions that require high solderability, sensitive to handling, short shelf life, erosive to the solder mask.
6, chemical nickel plating - chemical palladium plating immersion gold (ENEPIG) is through the reducing agent (such as sodium dihydrogen hypophosphite) so that palladium ions in the catalytic surface reduction into palladium, the newborn palladium can be called to promote the reaction of the catalyst, and thus can be obtained at any thickness of palladium-plated layer, more environmentally friendly than the ENIG, can provide good electrical properties and protection, with good welding reliability, thermal stability, surface flatness. The disadvantage is that palladium is a rare precious metal, thus the cost will increase.
7, hard gold (electrolytic hard gold) is in the PCB surface conductor first plated on a layer of nickel and then plated on a layer of gold, nickel plating is mainly to prevent the diffusion of gold and copper between the welding will lead to electroplated gold becomes brittle, which will shorten the service life, and therefore to avoid soldering on the electroplated gold.
Choosing the right PCB surface treatment process can significantly improve the performance and reliability of electronic products, but also can greatly save costs. Topfast PCBA specializes in small and medium-volume PCB/PCBA one-stop service manufacturing, selecting the right solution for your project, and providing professional and efficient electronic manufacturing solutions.