What are PCB Gold Fingers and How Are They Used?

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Nov 15, 2019|Product Innovations and Design, Technological Advancements and Materials

Even those familiar with printed circuit boards, or PCBs, may wonder what gold fingers are and how they relate to PCBs. You may be surprised to find just how prevalent PCB gold fingers are in consumer electronics. Let’s find out more!

What Are PCB Gold Fingers?

PCB gold fingers are essentially gold-plated connectors often located near the edges of a printed circuit board. They resemble columnar piano keys or small fingers. The exact type of gold used to create gold fingers is known as flash gold, and it is one of the hardest types of gold. This toughness keeps gold fingers from needing repair, in addition to ensuring that they last a very long time. Gold fingers must have a thickness of 3Us to 50Us. 

Types of Gold Fingers

There are two kinds of gold often used to create gold fingers. They are:

Electroless Nickel Immersion Gold (ENIG)

Electroless Nickel Immersion Gold, also known by the acronym ENIG, has a flat solderable face and is relatively inexpensive to produce. However, it is malleable and thin, making it a poor choice for PCBs that must be inserted into or removed from hardware components or that are in constant usage. 

Electroplated Hard Gold

Electroplated hard gold is thicker than ENIG, typically measuring at 30Us. The stable, robust nature of electroplated hard cold makes it an excellent choice for PCBs that are in constant use.

What Do PCB Gold Fingers Do?

PCB gold fingers are primarily responsible for electroplating the PCBs pads onto the motherboard. They are connection points between PCBs. They help to protect the PCB from failure. Gold is used for its conductivity in addition to its ability to resist abrasion and wear. 

However, PCBs are prone to overheating due to this perpetual flow of electrical currents. Using a trace width calculator can assist a PCB manufacturer in designing printed circuit boards that do not overheat while being transported or used. 

How Are PCB Gold Fingers Used?

PCB gold fingers have many various uses. Though they are chiefly used as interconnection points, they can also be used to enhance video graphics on a computer, connect to external speakers, and much more. 

Let’s explore some of the most common uses of PCB gold fingers!

Interconnection points

As mentioned above, gold fingers can help secondary PCBs communicate with the motherboard of a computer. Electronic signals flow through the gold fingers, and the information contained within those signals is transmitted to an internal card or device, which is, in turn, send that information to the motherboard. 

Special adapters

Gold fingers may also function as special adapters. Without them, it would be difficult, if not impossible, to make motherboard improvements. With gold fingers, you can make nearly unlimited enhancements to your personal computer. 

External connections

External components can be connected to the motherboard via gold fingers. Items such as speakers, monitors, printers, keyboards, and scanners are all connected to your personal computer by the gold fingers on PCBs. 

Consumer Usage

Gold fingers are critical to many popular consumer products. Personal computers, cell phones, Bluetooth speakers, and television all contain PCBs with gold fingers. 

Video and Graphics Card

A graphics processing unit (GPU), or graphics card, is a semi-permanent addition to your personal computer. A GPU is inserted into the proper slot and becomes active when its gold fingers receives electrical currents from the motherboard. A video and graphics card can improve the visual performance of your personal computer and can be updated every few years or so.

Network Adaptor Card

Network adaptor cards make it possible for our personal computers to connect to a network via a LAN connection. Without network adaptor cards, our electronic devices would be unable to connect to the internet or each other. Network adaptor cards are PCBs that attach directly to the motherboard. 

Audio Adaptor Card

An audio adaptor card allows personal computers to receive audio inputs in addition to outputting audio. Like a GPU or a network adaptor card, an audio adaptor card is a PCB with gold fingers. It attaches internally to the motherboard. An audio adaptor card can significantly improve the quality of audio your personal computer is capable of producing and can be replaced intermittently or as needed. 

TV or Other Specialty Adaptor Card

A TV adaptor card, also known as a TV tuner card, allows your television to communicate with your personal computer. Most modern television sets can communicate with your cell phone, your computer, and your remote control. With the touch of a button, you can stream entertainment onto multiple electronic devices. Much of this is due to the robust PCBs contained within these objects, each equipped with long-lasting, conductive gold fingers. 

PCB Gold Finger Specifications

As with many electrical components, gold fingers are required to meet strict specifications and requirements before being secured to a PCB. These standards ensure that all gold fingers function correctly and live a long life. 

Gold fingers must be of an appropriate length for the PCB, and the gold fingers must be appropriately aligned. Though gold finger placements vary from PCB to PCB, there are a few commonalities among all gold fingers. These include:

• Plated hole locations. Gold fingers must not be located near plated holes.
• Contact with solder mask. Gold fingers must not make contact or be too near solder masks or screen printing. 
• Gold finger orientation. Gold fingers must always be oriented so that they are facing the opposite of the center of the PCB.

In addition, gold fingers must adhere to IPC standards of thickness, chemical composition, appearance, and adhesiveness. 

Candor Industries Can Help

PCB gold fingers are a vital part of modern electronics and the communication that occurs among them. These components can be used as interconnection points, special adaptors, external connectors, and consumer-friendly improvements.

Candor Industries can help answer any additional questions you may have regarding PCBs, and their innovative process and designs may be the solution you’ve been looking for. Contact us today for more information, including a quote!