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The advancement of PCB surface finishes continues to advance alongside technological manufacturing, driven by the need for greater complexity, higher reliability, and improved performance in modern electronic devices. A preferred surface finish in PCB manufacturing is essential, and protective coating is applied to the exposed copper areas to prevent oxidation, enhance solderability, and ensure long-term circuit board reliability. The choice of surface finishes significantly affects the final product's performance, durability, and cost-effectiveness.
ENEPIG is a type of surface finish done on a copper layer to protect it from corrosion and oxidation in printed circuit boards. It is an acronym for Electroless Nickel Electroless Palladium Immersion Gold. This type of surface finish was created about a decade ago and has become more and more popular recently due to its relatively low cost when compared to other types of PCB gold plating options. ENEPIG finish features a multi-layer metallic structure— Electroless Nickel as a diffusion barrier, Electroless Palladium to prevent oxidation, and Gold for enhanced solderability.
PCB plating services can lower plating prices by using palladium plating for PCBs rather than pure gold, which increases the use of ENEPIG as an electronic plating solution. ENEPIG finishes are primarily used to support soldering and gold and aluminum wire bonding.
ENEPIG is similar to ENIG in that both utilizes electroless nickel on top of copper plating. ENEPIG plating contains an additional layer of Palladium when compared to ENIG plating, which contains only Nickel and Gold. This additional layer aids in the prevention of what is known as the 'Black Pad' occurrence, which is caused by gold corrosion to the Nickel layer.
Excellent solderability and wettability
Low and stable contact resistance
Corrosion resistance comparable to gold
Good wirebondability
Lead-free solder compatibility
ENEPIG plating has steadily gained popularity as a plating option, with a recent surge driven by the decreasing cost of palladium. Its widespread acceptance is also attributed to its significant benefits, including the following:
Cheaper –
Although ENEPIG has more processing steps, it is still more cost-effective than electrolytic nickel/electrolytic gold (ENEG) plating. The main reason is that ENEPIG uses less expensive materials, making it a more affordable choice for high-reliability PCBs.
Durability –
ENEPIG’s multiple layers provide strong protection against corrosion, thanks to the anti-corrosive properties of gold and palladium. This helps prevent 'black nickel,' a type of nickel corrosion that can affect the PCB’s reliability and performance.
Outstanding Solderability –
ENEPIG plating creates strong and reliable solder joints. It works well with various lead-free solder alloys and can handle multiple reflow soldering cycles without breaking down or losing quality.
High Wire Bond –
ENEPIG plating works well with both aluminum and gold wires. Testing has shown that it provides strong protection, even under long-term stress, ensuring consistent performance.
Low Contact Resistance –
PCBs need low contact resistance to prevent overheating, energy loss, and poor grounding. ENEPIG ensures this by applying precise layers of nickel, palladium, and gold, creating a consistent and reliable electrical connection.
Shielding Barriers –
In an ENEPIG finish, nickel and palladium act as protective layers, stopping the tin in solder from affecting the copper. This helps create stronger & more reliable solder joints.
ENEPIG surface finishes are ideal for printed circuit boards that support various package types, including THT (through-hole technology), SMT, BGA, wire bonding, etc, as they are used in high-density, high-performance devices.
Aerospace & Defense Electronics
High-Speed & 5G Communication Devices
Semiconductor & IC Substrates
Recent increases in gold costs and the demand for lead-free finishes have driven improvements in the immersion gold processes for ENEPIG plating. It offers a comprehensive and desirable solution for your PCB plating needs.