When working on an application that requires gold plating services, there are two design options available: hard gold plating and ENIG plating. The hard plating process features a refined grain surface and harder deposits that emerge from the gold itself being alloyed with a different element — like iron, nickel or cobalt. ENIG plating, or “electroless nickel immersion gold” plating, is much closer to pure gold in that no other elements are used for alloy — making the ENIG plating softer than hard plating.
Which is the best plating approach for your project? Read on to learn more about the advantages and disadvantages of hard gold plating vs. ENIG, as well as important questions to ask as you try to choose between the two.
Hard Gold Plating: Advantages and Disadvantages
Let’s talk details first. Hard gold plating typically includes the smallest possible grain sizes, which run 20 to 30 nanometers, and its hardness runs between 130 and 200 HK25. These characteristics make hard plating’s surface finish far more lustrous than ENIG plating. It also means hard plating is adept at preventing sliding wear. Hard plating can withstand applications that assert 50 grams of contact force or more. Hard plating can withstand far more cycles than ENIG plating as well, with the exact number of cycles dependent on the thickness of the plating.
The drawback to hard plating is its bonding ability. Given that hard plating includes nickel, iron, cobalt and other non-noble metals, soldering of hard gold is much more difficult than with ENIG plating. If you’re planning to undertake ultrasonic wire bonding, thermostatic bonding or other sensitive joining, hard plating makes the process extremely difficult.
ENIG Plating: Advantages and Disadvantages
ENIG plating is much softer than hard gold plating. Grain sizes are about 60 times larger with ENIG plating, and hardness runs between 20 and 100 HK25. ENIG plating holds up well at only 35 grams of contact force or less, and ENIG plating typically lasts for fewer cycles than hard plating.
ENIG plating is also better for the joining applications noted above. Though it may be likelier to scratch given its softness, the purity of ENIG plating makes it far more resistant to corrosion over time than hard gold plating.
How to Choose the Right Plating Approach
Which is the best gold plating for your application? When considering immersion gold and other options for a circuit board or other applications, consider four different characteristics:
- Contact force absorption and resistance to wear: Hard plating will perform better against high levels of contact force and wear.
- Appearance: Hard plating provides a more lustrous surface finish. (Should we remove?)
- Bonding: ENIG plating is best for sensitive joining applications.
- Corrosion resistance: ENIG plating is more resistant to corrosion.
Quality Plating Services at Sharretts Plating Company
At SPC, we provide high-quality metal plating and finishing services, including hard plating and ENIG plating. Contact us today with questions about immersion gold and gold plating, or inquire about a free quote on circuit boards or other projects.
