What is Gold Plating? The 12 Key Things to Know 

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Brief Explanation of what gold plating is

Gold plating applies a layer of gold onto a base metal or substrate. This technique commonly produces gold-plated jewelry, such as necklaces, earrings, and bracelets. It is possible to apply the layer of gold in different ways. One standard method is electroplating, which involves using an electric current to deposit the gold onto the surface.

The thickness of the layer is measurable in microns, with a higher number indicating a thicker layer of gold. Gold plating improves the appearance and durability of plated jewelry, protecting it from Tarnish and wear. Sterling silver is a popular base metal for gold-plated jewelry, and 18k gold is a standard plating layer.

The 12 Key Things to Know about Gold Plating

The following are a few things that need consideration when considering gold plating. 

Explanation of how the gold plating works

The gold plating process involves a series of steps that ensure a clean and smooth surface for the metallic coating. Firstly, the character must clear any impurities or unwanted materials through sandblasting or any other appropriate method.
Next, the surface requires cleaning using a degreasing solution. Then rinsed thoroughly to ensure the surface is free from dirt and residues. Later, a strike solution applied to the cover helps improve the gold adhesion to the surface. After that, the covering rinses again to remove any excess chemicals.

A base coat comes in contact with the surface, acting as a final coating primer. Finally, the character gets a coating of a thin layer of actual gold. Then it gets a rinse one last time to ensure that the plating evenly applies and no residue is left behind. The gold makes the plating process result in a striking and durable finish that resists rust and tarnish. The execution of these series of technical steps brings precision to ensure a flawless result.

Most importantly, the electrical current passing through the solution causes the gold to adhere to the object's surface, called electrodeposition. Finally, the thing needs polishing to achieve a high gloss finish so it last much longer. The gold-plating process requires expert knowledge and precise execution to achieve a high-quality result.

What is the purpose of gold plating? 

In technical terms, gold plating aims to enhance metal components' conductivity and corrosion resistance. Gold is a highly conductive material that does not tarnish or corrode easily. So this makes it an ideal candidate as a coating material. The plating comes in handy extensively in electronic components. It includes connectors and semiconductor devices, as it helps to ensure good electrical contact and prevent oxidation.

Additionally, gold plating helps for decorative purposes as it adds beauty and glamour to the final product. While gold plating technology has advanced significantly over the years, the goal remains the same; to create lasting, top-quality components that will stand the test of time in both technical and aesthetic terms. Simply put, the purpose of gold Plating ensures that your products look and function their best.

The gold plating process can also provide a protective barrier against external elements such as moisture, chemicals, and oxygen. The thickness of the gold layer can vary depending on the application, ranging from a few microns to several micrometres. Overall, it plays an essential role in many industries. It does so by providing a range of benefits to enhance the quality and performance of products.

The Purpose of gold plated Jewelry

Gold layer jewelry provides an affordable alternative to solid gold jewelry without sacrificing a fabulous-looking style. In addition, the price dramatically reduces by adorning cheap metal with a thin layer of gold. Thus, it is a budget-friendly option for those who desire stunning jewellery pieces.

Gold electroplated jewelry offers unique designs at a better price than solid gold. That is why it is a better investment for some consumers. Additionally, they are an excellent option for those who want to look good but are on a tight budget. With unique designs and a diverse selection of pieces available, plated jewelry offers a way to add a touch of luxury to any outfit without breaking the bank.

The purpose is to provide a fashionable accessory that is desirable and luxurious while also being cost-effective. It offers the appearance of gold without a high price tag. You can find these products in bulk quantity and is readily available. 
The result shows in a beautiful and durable piece of wearable jewellery in any setting. Furthermore, gold-plated jewelry is versatile and comes in various designs and styles. Therefore, it makes it a popular choice for men and women who want to enhance their overall look with elegant jewelry.

What Metals Does Gold Plating Work With?

The process of gold plating works with various metals, such as stainless steel, copper, brass, and even nickel. However, the effectiveness of the coating depends on the composition of the substrate surface. For example, copper is a good candidate for gold Plating because it is highly conductive and has a uniform consistency.

On the other hand, nickel is more challenging to the plate. It tends to oxidize and form a passivating layer, which hinders the adhesion of gold. Therefore, unique pre-treatment processes, such as etching, activation, or de-passivation, may be necessary to achieve a durable and aesthetically pleasing result.

How Much Gold Is Part of the Plating?

The amount of gold used in plating varies depending on the desired thickness and overall purpose. In addition, different plating methods, such as electroplating and electroless plating, use different gold amounts.

A high-quality electronic connector that requires excellent conductivity and durability may use a layer of plating of heavy gold. Therefore, it requires a tremendous amount of gold. Additionally, some industries may use alternative materials or alloys for coating. Overall, the amount of gold used in plating depends on various factors and can vary widely.

Quality of gold used in plating

A plating thickness of 2.5 microns is a significant part of the jewelry industry. This thickness deems sufficient for most jewelry, making it a popular choice among manufacturers. Gold ions help in plating. The coating quality reflects through the number of ions added to the plating solution. With a 2.5-micron thickness, jewelry protects from wear and tear while maintaining its appearance.

Even with everyday use, this thickness quality is durable enough to keep jewelry looking beautiful for a long time. As a result, this provides the ideal balance of durability, quality, and beauty in the products.

The colour of the plating

The colour of the plating serves an aesthetic purpose and indicates the type of material used for this process. The plating thickness of the metal can alters the colour depiction. The thicker the chrome plating layer, the darker and more mirror-like finish it will have. Conversely, the thinner the plating, the brighter the metallic appearance the surface will have. 

Some gold coating processes use a colouration treatment. It is to achieve hues like gold or black, which add a specific design element to the product. Hence, choosing the right colour for plating can significantly enhance product functionality, durability, and marketability.

Types of Processes used in Gold Plating

There are five classes of gold plating chemistry, each with unique methods and applications. The first is immersion coating or electroless plating, where a chemical reaction deposits gold onto a substrate. The second is electroplating, which involves passing an electric current through a metal solution to the plate onto the substrate.

Moreover, the third is pulse electroplating. This plating uses high-current pulses to the metal solution to deposit the metal rapidly. The fourth is vacuum deposition, which involves vaporizing the gold and depositing it onto the substrate in a vacuum chamber.
The final class is brush plating. It involves using a specialized brush to deposit a thin layer of gold onto a specific substrate area. The process of the gold plating has its benefits and limitations. The selection of which depends on the particular application requirements.

You need to know about gold Plating Tarnish.

Gold plating can tarnish over time. Especially if the plating wears off or it has exposure to chlorinated or salty water. It is essential to know that gold Plating is different from real gold. Thus, it does not have the same durability properties. It is a thin layer of gold that places over a less expensive metal to give the appearance of natural gold.

However, this plating can wear off in areas that constantly rub against surfaces, like jewelry clasps or watchbands. Additionally, exposure to chlorine or salt can cause the plating to tarnish or even discolour. Therefore, if you plan on purchasing anything with gold plating, it may require frequent maintenance to preserve its appearance.

Benefits of Gold Plating and everything you need to know about it

Gold plating services are a popular process for many industries due to their attractive and valuable appearance. One of the key benefits of gold Plating is the ease of coating application, which makes it highly efficient for large-scale production. In addition, it offers protection against fretting degradation, which is the gradual deterioration of mechanical components caused by rubbing against one another.

Therefore, it is ideal for applications such as electrical connectors, jewelry, and medical devices that require durability and longevity. However, the cost of gold Plating can be high, depending on the coating thickness required. Proper maintenance is also essential to ensure the longevity of the gold plating. 
 
Gold plating has numerous benefits, making it an ideal choice for various applications. Firstly, it enhances durability and increases the longevity of the metal. Therefore, it is particularly beneficial for decorative and high-end jewelry pieces, as it preserves their shine and lustre for much longer. 

Gold plating also provides excellent heat protection, perfect for electronic components and circuits. Furthermore, it is resistant to corrosion. Hence it is ideal for use in high-humidity environments. Additionally, gold plating can increase electrical conductivity. So, it is a common choice for electronic connectors and other similar applications.

In conclusion, gold plating is incredibly versatile and durable, with many benefits. It dramatically improves the aesthetics and durability of their jewelry, electronics, and other products.

Is The Gold In Gold Plating Valuable?

Gold plating can make an item look more valuable. However, it is essential to note that the gold presence in scale is not always pure. Many gold-plated things contain only a tiny amount of actual gold - typically around 0.5 microns in thickness.

Although, 24k gold plating can add value to an object. It doesn't necessarily mean that the gold in the coating is valuable. If you want to know the importance of gold Plating, you need to know the purity of the gold used in the process. The higher the purity, the more valuable the plated gold will be.

Frequently Asked Questions about Gold Plating

What are the specifications for gold plating?

Gold plating is a process of plating a layer of gold onto a surface for decoration, corrosion resistance, and conductivity. The specifications for gold plating vary depending on the desired result. Generally, gold plating thickness ranges from 0.5 to 5 microns and can create a stunning and long-lasting decorative effect.

What to know about gold-plated jewelry?

Gold-plated jewelry is a popular synthetic alternative costume jewelry to pure gold jewelry that is affordable. It is often less expensive than solid gold jewelry but less durable. Therefore, it is essential to buy from a reputable seller and to check for any signs of discolouration or damage.

How long does gold-plated jewelry last?

The durability of gold-plated jewelry depends on a variety of factors. Thus, it can last anywhere from six months to two years before the gold plating begins to wear off. 

How thick is mil-spec gold plating?

Mil-spec gold plating is part of the metal surfaces of various military equipment, weapons, and electronic devices. It can range from 0.0001 to 0.003 inches (2.54 to 76.2 microns) or more.

How do I know if my jewelry is gold-plated?

There are several ways to determine if the jewelry has a plating of gold. The first way is to look for any markings on the jewelry, such as "GP" or "GEP," which stands for gold plated or gold electroplated, respectively. Next, examine the colour of the jewelry. Additionally, you can use a magnet to determine if the jewelry is of gold since gold is not magnetic.

Once your board passes through the standard PCB fabrication process, the bare copper in your PCB will be ready for the application of a surface finish. PCB plating is applied to protect any copper in your PCB that would be exposed through the solder mask, whether it’s a pad, via, or other conductive element. Designers will often default to something like tin-lead (SnPb) plating, but other plating options may be better for your board’s application.

In this article, I’ll run over the different PCB plating material options and their advantages in your PCB. There are several options to choose from, and depending on your reliability or application needs, you may need to check that your fabricator can apply the plating you need in your design. We’ll look at these options as well as a brief discussion of how plating affects losses.

PCB plating materials come in several varieties. I’ve compiled the popular materials designers should know and understand in the sections below. I’ve never seen a manufacturer that doesn’t offer all of these options. If your intended manufacturer doesn’t explicitly state they offer one of the options in the list below, you can always email them to get a list of their capabilities, including their PCB plating material options.

This PCB surface finish is probably the cheapest option, but it will not comply with RoHS due to use of lead in the plating finish. Immersion tin is a lead-free alternative that can be used in entry-level boards.

Advantages

Disadvantages

Very flat surface

Not good for multiple assembly processing passes or rework

Inexpensive

Forms tin whiskers over time

Compatible with standard solders

Can experience damage from handling

Addition of Pb suppresses whisker formation

Sn diffusion into Cu can reduce shelf like, depending on intermetallic content

 

Could damage solder mask during the plating process

 

 

HASL was historically a very popular surface finish choice, but it is not as reliable as other plating materials. It is inexpensive and is available in a lead-free option, so it can be used as an entry-level plating option.

Advantages

Disadvantages

Inexpensive

Uneven surface makes it less useful for small SMD parts

Can be repaired

Can be damaged from thermal shock

 

Can be difficult to solder due to poor wetting

 

 

Given the disadvantages of SnPb and immersion tin, ENIG is now arguably the most popular surface finish in the industry. In this plating material, nickel acts as a barrier layer between copper and the thin gold surface layer where components will be soldered.

Advantages

Disadvantages

Very flat surface

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Not good for multiple assembly processing passes or rework

Easily plates PTH holes

Can be expensive

Widely available

Can experience phosphorous infiltration between gold and nickel layers, known as black pad syndrome

Easily solderable

Rough interface creates signal losses at high frequencies

Suitable for fine-pitch components

 

Highly reliable against mechanical damage

 

Wire-bondable (Al)

 

 

 

This organic water-based surface finish selectively bonds to copper to provide a highly planar surface finish. As an organic material, it is sensitive to handling and contaminants, although the application process is simpler than for other PCB plating materials. It also has very low loss at high frequencies.

Advantages

Disadvantages

Very flat surface

Easily damaged

Repairable after application

Short shelf life

Simple application process

 

Very low loss in high frequency interconnects

 

Wire-bondable (Al)

 

 

 

This is my PCB plating material of choice for high-frequency applications. It forms a smooth interface against bare copper, so it does not add as much conductor loss as other PCB surface finishes. The main drawback is tarnishing on bare boards, so it should be soldered and packaged ASAP after fabrication.

Advantages

Disadvantages

Easily solderable and wire-bondable for aluminum

Silver whiskering can occur over time

Very flat surface

Exposed (un-soldered) conductor can tarnish over time, although added OSP helps prevent this

Suitable for fine pitch

Can be difficult to plate into small-diameter vias

Preferable for high frequency interconnects in high reliability systems

 

Wire-bondable (Al)

 

 

 

This plating material has a copper-nickel-palladium-gold layer structure that is wire-bondable directly to the plating. The final layer of gold is very thin, just as is the case in ENIG. The gold layer is soft, just as in ENIG, so excessive mechanical damage or deep scratches might expose the palladium layer.

Advantages

Disadvantages

Easily solderable and wire-bondable

Expensive

Very flat surface

Palladium layer can make the material more difficult to wet and solder

Suitable for fine pitch

May require separate processing line

Lowest corrosion level among commercially available PCB plating materials

 

Wire-bondable (Al and Au)

 

 

 

This plating material is essentially ENIG but with a very thick gold outer layer, thus it is among the most expensive PCB plating materials. The gold layer provides a hard surface that can be damaged, but its thickness makes it difficult to totally expose the nickel layer.

Advantages

Disadvantages

Wire-bondable (Al and Au)

Very expensive

Very durable surface

Not suitable for solderable areas

 

Requires additional processing steps to selectively apply

 

Can experience slivering

 

Among all of the above options, ENIG is arguably the best balance of cost durability, and range of application. For most low-frequency analog systems or digital systems that don't always run at fast edge rates (e.g., SPI or I2C), ENIG will often be the plating of choice, including in high reliability systems that need to reach IPC Class 3 compliance. It’s also suitable for pads on dense BGAs or QFN packages. Once we look at alternative plating materials shown above, we see some other applications that are more ideal: immersion silver or OSP are best for RF systems, while immersion tin is probably fine for throwaway (Class 1) products that just need lead-free compliance. In more specialized applications like very high speed digital and RF, the thickness is very important, as I’ll detail below.

Typical PCB plating thickness values are somewhere around 100 micro-inches. For immersion silver and OSP, the typical thickness can be as low as approximately 10 micro-inches. Specifying the type and thickness of PCB plating is easy: you include it in your fabrication notes (see the example below). If you’re producing a prototype and the manufacturer has a standard quote form, you’ll have an opportunity to specify the plating type in their form. In these forms, they might not ask you for the thickness, so make sure you specify this if you need a specific thickness. Once you’ve specified the required plating value, it’s up to your fabricator to ensure the plating can be reliably deposited to the required thickness.

Example fabrication note specifying PCB plating. Here the thickness of the plating specifically is un-specified and is instead lumped in with the finished copper weight. Read this blog to find a link to download the full fabrication notes.

Why should the thickness of the plating material matter? There are two reasons for this. First, the IPC-2221A standard specifies a minimum plating thickness for each of the IPC product classes (see Table 4.3, you can download a copy of this standard from my site at this link). If you want your product to be compliant with any of the standard IPC product classes, then you’ll want to ensure your plating thickness meets their spec. Normally, if you specify a product class as you would typically do in your fabrication notes, then the minimum plating thickness is implied. Just make sure you don’t contradict yourself, otherwise your fabricator will email you asking about the plating note.

The other reason to worry about PCB plating thickness is the effect it has on losses. At low frequencies, you probably won’t notice any effects on frequency, so low-speed digital signals and sub-GHz radios won’t need to worry so much about PCB plating thickness. I’ve done custom printed emitters operating at 5.8 GHz WiFi with ENIG (not the best for high frequency) that swamped the receiver in our test setup, so you can even get away with most platings at these frequencies if your circuit is designed correctly.

The issue with losses arises at mmWave frequencies, like short range radar (24 GHz) and higher. At these frequencies, copper roughness becomes a very noticeable contributor to losses, especially on low-loss RF substrates like Rogers. The plating thickness will determine the amount of roughness experienced by signals as they propagate, which will manifest itself in the skin effect resistance. For some example results, look at the results from John Coonrod in this article, specifically the set of graphs showing insertion loss. As can be seen, larger amounts of rough plating can increase losses. For convenience, I’ve reproduced one graph below for microstrips.

Insertion loss per unit length for bare copper and ENIG-plated copper with two thicknesses. Thicker ENIG plating produces more loss. [Source]

Once you’ve determined the PCB plating you need in your design and you’re ready to specify your fabrication requirements, you can create your documentation with the easy-to-use manufacturing tools in Altium Designer®. Once your design is ready for a thorough design review and manufacturing, your team can share and collaborate in real time through the Altium 365™ platform. Design teams can use Altium 365 to share manufacturing data and fabrication requirements through a secure cloud platform.

We have only scratched the surface of what’s possible with Altium Designer on Altium 365. Start your free trial of Altium Designer + Altium 365 today.

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