What Are the Differences Between PCB ENIG and Gold Plating?

October 13, 2025

ENIG (Electroless Nickel Immersion Gold) and gold plating are commonly used processes in today's PCB production. With the increasing integration of ICs, their pins have become more numerous and densely spaced. The vertical hot air leveling (HASL) process struggles to achieve a flat surface on very fine pads, which poses challenges for SMT assembly. Additionally, HASL boards have a short shelf life. Gold plating effectively addresses these issues. For surface mount technology, especially for 0603 and 0402 ultra-small components, the flatness of the pads directly impacts the quality of solder paste printing and plays a decisive role in subsequent reflow soldering. Therefore, entire board gold plating is often seen in high-density and ultra-small SMT processes. During the prototyping stage, components are often not immediately assembled upon the board’s arrival due to factors like part procurement delays, and boards may need to wait for several weeks or even months before use. Gold-plated boards have a much longer shelf life than tin boards, making them a preferred choice. Moreover, the cost of gold-plated PCBs during the sampling phase is nearly comparable to that of lead-tin alloy boards.

I. What Is Gold Plating?

Whole-board gold plating typically refers to [electroplated gold], [electroplated nickel gold board], [electrolytic gold], [electro-gold], and [electroplated nickel gold board]. It is categorized into soft gold and hard gold (commonly used for gold fingers). The principle involves dissolving nickel and gold (commonly known as gold salts) in chemical solutions, immersing the circuit board in an electroplating tank, and applying an electric current to deposit a nickel-gold layer on the copper foil of the board. Due to its high hardness, wear resistance, and oxidation resistance, electroplated nickel gold is widely used in electronic products.

What Is ENIG?

ENIG involves forming a plating layer through chemical oxidation-reduction reactions. Generally, the gold layer is relatively thick, as it is a method of depositing chemical nickel and gold, allowing for a substantial gold thickness. This process is commonly referred to as immersion gold.

II. Differences Between ENIG and Gold-Plated Boards

1.The crystal structure formed by ENIG and gold plating is different. ENIG results in a much thicker gold layer than gold plating, appearing more golden-yellow and thus more visually appealing to customers.

2.The crystal structure formed by ENIG and gold plating differs. ENIG is easier to solder compared to gold plating, reducing the likelihood of soldering defects and customer complaints. The stress of ENIG boards is easier to control, making them more suitable for bonding processes, especially for products requiring bonding. However, because ENIG is softer than gold plating, ENIG boards are less wear-resistant when used as gold fingers.

3.On ENIG boards, nickel and gold are only present on the pads. In skin effect, signal transmission occurs in the copper layer, so it does not affect the signal.

4.The crystal structure of ENIG is denser than that of gold plating, making it less prone to oxidation.

5.As circuit traces become denser, with line widths and spacing reaching 3-4 MIL, gold plating is more likely to cause gold wire short circuits. ENIG boards, having nickel and gold only on the pads, do not produce gold wire short circuits.

6.Since ENIG boards have nickel and gold only on the pads, the solder mask on the traces adheres more firmly to the copper layer. This ensures that engineering compensation does not affect spacing.

7.ENIG is generally used for boards with relatively high requirements, where good flatness is essential. ENIG typically avoids the black pad phenomenon after assembly. The flatness and shelf life of ENIG boards are as good as those of gold-plated boards.