Hard Gold PCBs

Hard gold is an electroplated finish that’s commonly applied to high-wear areas like edge connector fingers and keypads on PCB. It’s typically plated over a barrier layer of nickel.

This coating has poor solderability and contains non-noble elements such as nickel and cobalt, which oxidize at elevated temperatures. It’s also expensive.

Conductivity

Gold is a great conductor of electricity and is used in high-quality electronic components. Its conductive properties are aided by its ability to resist corrosion, which is why hard gold is used on PCBs. This makes it ideal for use in military and other harsh environments. Hard gold also helps reduce tarnishing, which is important for electronics that will be used frequently and exposed to salts, acids and other chemicals.

In addition to its excellent conductivity, hard gold has a dazzling appearance thanks to its refined grain structure. This is a major benefit for applications that require visually acceptable gold contacts, such as visible interconnect applications. Hard gold is also ideal for applications that must be soldered in harsh environments because of its ability to withstand higher temperatures.

The only drawback to hard gold is that it includes non-noble metals like nickel and cobalt, which oxidize at soldering temperatures, reducing the strength of the solder joint. For this reason, it is not suitable for ultrasonic wire hard gold bonding or thermosonic bonding. In these cases, ENIG is a better choice as its thickness and purity make it perfect for these operations.

When choosing a hard gold PCB manufacturer, look for one that has reliable screening systems and works collaboratively with engineers to produce top-quality products. They should also have a wide range of quality control testing equipment, such as flying probe test, which automatically checks all terminal points on a board to ensure consistency.

Durability

Hard Gold PCBs are able to withstand harsh conditions and have great durability compared to other PCBs. They have better resistance to oxidation and corrosion, making them ideal for use in medical, military, and aerospace devices. Additionally, they can withstand high temperatures and provide superior signal transmission, resulting in excellent performance and reliability. This durability can save you money in the long run, as it cuts down on repairs and replacement costs.

The hardness of gold plating makes it a better choice for areas that require sliding wear, such as edge connectors or keypads. This is because it has a higher resistance to sliding contact fatigue than ENIG. It is also ideal for applications that assert 50 grams or more of contact force. Moreover, it has a more lustrous appearance than ENIG.

However, the hardness of hard gold increases the risk of solderability issues because it contains impurities such as nickel and cobalt. These metals oxidize at soldering temperatures, and this can result in poor contact surface strength. It is, therefore, important to choose a PCB manufacturer that has experience and expertise in manufacturing hard gold PCBs. It is also important to choose a manufacturer that uses the best copper and gold plating technology. This will ensure that your PCBs are durable and have the highest possible conductivity.

Appearance

Hard gold has a bright appearance due to its refined grain structure. It is used on areas where visual appearance is important, such as gold contacts for PCBs and keypads. In addition, it is used for high-wear areas such as connector fingers and edge joints. The use of hard gold is usually followed by a barrier coat of nickel, to prevent oxidation and provide good solderability.

The difference between hard gold and soft gold is the amount of non-noble metals alloyed with the deposit – typically cobalt, nickel, and iron. This creates a harder deposit with a finer grain structure that is more glossy and resists sliding wear than soft gold. Hard gold is also a bit thinner than soft gold and has a higher hardness, 130-200 HK25.

In addition to its durability, hard gold is lead-free and environmentally friendly. It has a low rate of absorbing moisture and has a high thermal resistance. It is also a good choice for high-density circuits because of its smooth electron conduction. It is also useful for flat pads because it allows more features to be placed on the surface.

However, hard gold does not have the same properties as ENIG, which is preferred for applications like thermosonic wire bonding and ultrasonic wire bonding. This is because the presence of the non-noble metals in hard gold deposits reduces its corrosion resistance and makes it prone to oxidation at high temperatures.

Life Cycle

Gold is naturally resistant to oxidation, corrosion and tarnishing. As a result, it maintains its shiny appearance Hard Gold PCB Supplier over time and remains effective in harsh environments where other metals can corrode easily. In addition, it’s less sensitive to humidity and highly corrosive gases such as sulfur or chlorine. It can withstand electrical contact in these environments without degradation, while other materials may not be able to provide consistent current levels or prevent arcing.

Hard gold is typically used for high-wear areas like edge connector fingers or keypads. These contacts must withstand the many durability cycles of insertion and removal, and hard gold provides excellent wear resistance. It also provides excellent solderability and a good surface for wire bonding.

Compared to soft gold, which has a Knoop hardness between 91-115, hard gold has a finer grain structure and offers superior sliding wear resistance. However, the presence of non-noble elements such as nickel and cobalt in hard gold makes it difficult to solder. Additionally, its low melting point can cause the deposits to melt at soldering temperatures, which reduces conductivity.

Swiss researchers have created a way to harden pure gold without mixing it with other metals or using chemical processes that degrade its quality. The team from EPFL in Switzerland, led by metallurgy professor Andreas Mortensen and funded by luxury watchmaker Hublot, achieved a peak hardness value of HV 170 after cold working and ageing heat treatments.