3. Electroless Nickel/Immersion Gold: The process of electroless nickel/immersion gold differs from organic coating and is commonly used for boards with connection requirements and longer storage periods, such as mobile phone keypads and router housings. The edge connection area of the chip processor is elastically connected to the electrical contact area. Electroless nickel/immersion gold gained popularity in the 1990s due to issues with hot air leveling flatness and the removal of organic coating flux. Despite challenges with black discs and brittle nickel-phosphorus alloys, the use of this process has decreased. However, nearly every high-tech PCB factory now utilizes electroless nickel plating/immersion gold wire. Portable electronic products, like mobile phones, typically use copper-tin intermetallic compound solder joints formed by organic coating, immersion silver, or immersion tin, with electroless nickel/immersion gold used for key areas, contact areas, and EMI shielding areas. Currently, about 10%-20% of PCBs use electroless nickel/immersion gold processes.
4. Immersion Silver: Immersion silver is a cost-effective alternative to electroless nickel/immersion gold for PCBs with connection requirements. The good flatness and contact of immersion silver make it a favorable choice for reducing costs. It finds many applications in communication products, automobiles, computer peripherals, and high-speed signal design. Due to its superior electrical properties, immersion silver can be used in high-frequency signals and is recommended by EMS for its ease of assembly and better checkability. Although the growth of immersion silver has been slow due to tarnishing and solder joint voids, approximately 10%-15% of PCBs currently use this process.
5. Immersion Tin: Immersion tin has been introduced into surface treatment processes in the past decade to meet the demands of production automation. It does not introduce new elements into solder joints and is ideal for communication backplanes. However, tin can lose its solderability beyond the board’s storage period, requiring optimal storage conditions. The use of immersion tin is limited due to the presence of carcinogenic substances. Approximately 5%-10% of PCBs currently undergo the immersion tin process.
Concluding Remarks: As customer demands and environmental regulations become more stringent, the variety of surface treatment processes continues to expand. Choosing a surface treatment process with development prospects and versatility can be overwhelming. The future direction of PCB surface treatment processes remains uncertain, but it is essential to prioritize meeting customer requirements and environmental protection.
4. Immersion Silver: Immersion silver is a cost-effective alternative to electroless nickel/immersion gold for PCBs with connection requirements. The good flatness and contact of immersion silver make it a favorable choice for reducing costs. It finds many applications in communication products, automobiles, computer peripherals, and high-speed signal design. Due to its superior electrical properties, immersion silver can be used in high-frequency signals and is recommended by EMS for its ease of assembly and better checkability. Although the growth of immersion silver has been slow due to tarnishing and solder joint voids, approximately 10%-15% of PCBs currently use this process.
5. Immersion Tin: Immersion tin has been introduced into surface treatment processes in the past decade to meet the demands of production automation. It does not introduce new elements into solder joints and is ideal for communication backplanes. However, tin can lose its solderability beyond the board’s storage period, requiring optimal storage conditions. The use of immersion tin is limited due to the presence of carcinogenic substances. Approximately 5%-10% of PCBs currently undergo the immersion tin process.
Concluding Remarks: As customer demands and environmental regulations become more stringent, the variety of surface treatment processes continues to expand. Choosing a surface treatment process with development prospects and versatility can be overwhelming. The future direction of PCB surface treatment processes remains uncertain, but it is essential to prioritize meeting customer requirements and environmental protection.
