ENEPIG PCB Technology
As a surface finishing,Electroless nickel/electroless palladium/immersion gold (ENEPIG) has received increased attention for both packaging/IC-substrate and PWB applications. With a lower gold thickness than conventional electroless nickel / immersion gold (ENIG) the ENEPIG finish offers the potential for higher reliability, better performance and reduced cost.
ENEPIG vs ENIG and Flash Gold,ENEPIG has more advantages:
- Gold and Aluminum Wirebonding
- Good Solderability
- No excessive corrosion of the EP layer
- No concern with “Back Pad”
- Good surface wear resistance
- Low cost than Flash Gold
The ENEPIG Process :
Oil Removal–>Micro Etching–>Acid Cleaning–>Impregnation–>Activation of Palladium–>Chemical Nickel(reduction)—>Chemical Palladium(reduction)–>Chemical Gold(replacement)
Of course, the process will be different due to differences in the characteristics of suppliers.For example, some manufacturers will increase corrosion after micro corrosion and chemical palladium,in the micro etching increased after pickling is designed to increase the cleaning effect, avoid the semi plug hole due to residual nickel leakage drops. The purpose of increasing acid washing in the presence of chemical palladium is to increase the cleaning effect,avoid chemical palladium residual lead to gold coating color difference.Some manufacturers of chemical leaching process is composed of thin and thick gold two gold chemical chemical process, chemical reaction principle is thin gold nickel replacement, the chemical is thick in the thin gold on the basis of the reduction of the thick thin gold; chemical and chemical process is designed to ensure the thick gold layer uniformity.
By contrast can be seen in Table 1, ENEPIG (ENEPIG) process in both chemical nickel gold (ENIG) process of welding performance, smooth coating rate is high, long-term reliability, relative ENIG surface treatment technology, introducing chemical palladium, palladium and nickel diffusion barrier migration by blocking contact at the same time nickel and gold leaching solution, which can effectively prevent the chemical nickel gold surface treatment process of common black plate (Black Pad), ENEPIG coating and thin can obtain better wear resistance and performance of gold, so ENEPIG is regarded as a versatile surface treatment technology, especially suitable for use in SMT and WB mixed plate and mobile phone board high connection reliability products, completely replace the current technology of chemical nickel gold.