What is Gold Plating? The Basics

Ever found yourselves inspecting your circuit boards and wondered how they made them? What is gold plating and how can it affect you and your daily life?

Well, saddle up as we explore what gold plating is and what it is used for, as well as how you can go about doing it at home.

Table of Contents

• What is Gold Plating Actually?
• What are the Different Types of Gold Plating?
• What is Gold Plating Used For?
  • Jewelry
  • Electronics
• How to Gold Plate
  • Step 1: Preparing
  • Step 2: Rinsing
  • Step 3: Striking
  • Step 4: Rinsing (Again)
  • Step 5: Coating
  • Step 6: Rinsing (Once More)
• Final Words
• FAQs Gold Plating

What is Gold Plating Actually?

Gold plating is a method of depositing a thin layer of gold onto the surface of another metal, most commonly copper or silver (to make silver gilt), via chemical or electrochemical plating.

In a lot of ways, it really is as simple as that, though it can be as complex as you want it to be.

What are the Different Types of Gold Plating?

As already alluded to, just because something is gold-plated, it doesn’t necessarily mean that it was built the same as other things with a gold layer.

• Soft, pure gold plating is used in the semiconductor industry. The gold layer is easily soldered and wire-bonded with a Knoop hardness ranging from between 60 and 85. Most importantly, the plating baths have to be kept free of contamination lest they be spoiled.
  • Soft, pure gold is deposited from special electrolytes from which entire printed circuit boards can be plated. This technology can then be used for depositing layers suitable for wire bonding.
• Bright hard gold on contacts, on the other hand, has a Knoop hardness between 120–300 and a purity of 99.7–99.9% gold. This form often contains a small amount of nickel and/or cobalt. These elements, however, interfere with die bonding, thus the plating baths cannot be used as semiconductors.
  • Bright hard gold on printed circuit board tabs is deposited using a lower concentration of gold in the baths, as well as containing nickel and/or cobalt in ample measures. Edge connectors are often made by controlled-depth immersion of only the edge of the boards.

What is Gold Plating Used For?

Gold plating service has several uses in project management and elsewhere. Just see for yourself:

Jewelry

Jewelry is regularly manufactured by gold-plating silver. The thickness of gold plating on jewelry is noted in microns (or micro-meters), the microns of thickness ultimately determining how long the gold plating lasts with usage.

Gold-plated silver jewelry can (and will) still tarnish as the silver atoms diffuse into the gold layer, causing slow gradual fading of its color and eventually causing tarnishing of the surface.

The length of this process can vary and may take months and even years, depending on the thickness of the gold layer. A barrier metal layer is used to counter this effect – often nickel or rhodium.

Copper, which also migrates into gold, does so more slowly than silver., especially since the copper is usually further plated with nickel. A gold-plated silver article is usually a silver substrate with layers of copper, nickel, and gold deposited on top of it for extra protection.

Electronics

This is certainly one of the major uses of gold electroplating that has arisen in the past 50 or so years, where gold plating is used to provide a corrosion-resistant electrically-conductive layer on copper, typically in electrical connectors and printed circuit boards.

With direct gold-on-copper plating, just some of the alternative metal leaves, the copper atoms tend to diffuse through the gold layer, causing tarnishing of its surface and a formation of an oxide and/or a sulphide layer.

A layer of suitable barrier metal, usually nickel, is, then, often deposited on the copper substrate before the gold plating. The layer of nickel provides mechanical backing for the gold layer, improving its wear resistance, while also reducing the impact of pores present in the gold layer.

How to Gold Plate

As with anything, there are a number of different steps to follow here.

Step 1: Preparing

First, you will want to choose a surface upon which to gold plate – ideally it will be clean and free of any dirt, oils, or contaminants. You can do this by using various methods, including ultrasonic cleaners, alkaline cleaners, solvent cleaners, or a simple soap and water solution.

This step is crucial for ensuring that the gold adheres properly to the surface while keeping the plating tanks clean and free from contamination.

Step 2: Rinsing

Rinse the work surface with distilled water and dry it completely before moving on to the next step. This helps remove any leftover cleaner residue and gives you a clean slate to work with.

Step 3: Striking

Apply a strike layer (a thin plating layer) of high-quality nickel to the surface of the clean base metal, helping to improve the adhesion of the gold to the surface and prevent tarnishing that can occur down the road.

Step 4: Rinsing (Again)

After the strike layer has been applied, rinse the surface again with distilled water to help remove any impurities that may be present here and later down the line.

Step 5: Coating

Once you confirm the temperature, time, and voltage have been set correctly, hang the piece of metal you want to gold plate from a negative hook (cathode bar) and lower it into the gold solution.

Once submerged in the solution, an electrical charge will be applied, causing the negatively charged metal to attract the positively charged ions present in the solution. This will cause a thin layer of gold to be deposited on the surface of the metal.

Step 6: Rinsing (Once More)

Finally, rinse the gold-plated surface with distilled water one final time to help remove any impurities that may be present, then hang the piece up to dry completely.

Final Words

So, there you have it! Hopefully, you are now feeling ready and able to give it a go yourself.

FAQs Gold Plating