Skip to main content


PCB Manufacturing
PCB Assembly
PCB Design and Layout
PCB Basics
Vias, Drilling & Throughplating
PCB Fabrication
PCB Ordering

In today’s digital age, communication signals are transferred between many devices. Gold fingers enable connections between circuit boards and other devices.


Gold fingers are gold-plated connectors found on the edge of circuit boards. They interconnect to boards using sockets, like a computer’s motherboard. Gold fingers are used in different devices and applications such as smartphones, smartwatches, and more typically in industrial applications such as electronic card cages to communicate with digital signals. They also help in protecting the board connections from deterioration and failures.

Gold fingers on computer RAM microchip module


Gold is chosen for plating because of its high corrosion resistance, high electrical conductivity, and the ability to be alloyed with cobalt or nickel to improve its resistance to wear and tear. The thickness of the gold plating varies between 0.003 and 0.005 mils.


ENIG is cost-effective and easy to solder. Since it is thin and soft (0.002-0.005 mils) it is unsuited for some boards due to abrasive effects such as insertion and removal.


Hard gold comes with a thickness of 0.03 mils. They can sustain abrasive effects occurring on a board due to constant usage.

Hard gold plating on a PCB


  • Can be easily placed on one or both sides of a board to a depth of 1 inch from the outer edge
  • Should be connected with 8 mil conductor traces. It makes manufacturing easier
  • Plated through-holes should not be situated close to them
  • Should be kept at a distance from solder mask or silkscreen printing
  • Must always face the opposite direction from the middle of the circuit board (if you want the edge to be beveled)
Gold fingers on a PCB


On a board, the gold finger plating process is performed after the application of the solder mask and before the surface finish. The plating process involves the following steps:

Nickel plating

Firstly, 0.004 to 0.008 mils of nickel is plated onto the connector edges of the fingers.

Gold plating

Later, 0.04 to 0.08 mils of hard gold is plated over the nickel. The gold is usually mixed with cobalt for increasing the surface resistance.

Edge beveling

Edge beveling is a process of creating a transitional edge between two faces of a circuit board, generally performed on the outer edge of the board. Beveling allows for smoother insertion into other PCB sockets. The edge connection pins are called gold fingers as they are gold plated and some of them are grouped in parallel. For gold fingers the following options available:

  • Available beveling angles: 20⁰, 30⁰, 45⁰, and 60⁰
  • Residual thickness after beveling:12 mils

The depth or residual thickness of the beveling can be calculated using the geometry shown below:

Edge beveling of gold finger

𝑑 = 𝑡 − 𝑡𝑟/ 2 ∗ sin 𝑎

Where, d = depth, 𝑎 = bevel angle, t = board thickness, and 𝑡𝑟= residual thickness.


  • Chemical composition: The gold plating should consist of 5-10% cobalt for maximum rigidity across the board edges.
  • Thickness: The plating thickness of gold fingers must fall between 0.002- 0.005 mils. The standard thickness dimensions are 3 mils, 62 mils, 93 mils, and 125 mils.
  • Visual test: A visual test is conducted with a magnifying lens to ensure edges are smooth, clean, and free of excess plating.
  • Tape test: It is done to check the adhesiveness of the gold plating. In this test, a strip of tape is placed along the contact edges. After removing it, the strip is inspected for traces of plating. If any gold plating is observed on the tape, then the plating lacks adequate adhesiveness.


They have a wide range of applications in several industries including:

  • Telecommunication industry: Connection for network data transfer (communication adapter)
Gold fingers inside the USB cable adapter
  • Computer application industry: Data transfer (laptop memory card, graphics card, etc.)
Gold fingers on various sizes of memory cards
  • Industrial control system: Connection to different devices (factory robot arm, high-end consumer electronics, computerized industrial machines, etc.)


A PCB edge connector consists of traces that lead to the board’s edge and are designed to plug into a matching socket. It facilitates the connection between two boards or from one board to an external electrical connection. These edge connectors are fairly reliable, affordable, and robust. Typically, they are used in computers as expansion slots, such as PCI Express, PCI, and AGP cards.

PCI express port slot on a PCB

Edge connector sockets are bounded by a plastic box that is open on one side, with pins on one or both ends of the longer edges. Often, connectors contain bumps or notches for polarity and to ensure the correct device type is inserted into the connector. The socket’s width is selected according to the thickness of the connecting board. On the other side of the socket is usually an insulation-piercing connector attached to a ribbon cable. A motherboard or daughter card may also be connected to the other side.

Card edge connector


For designing edge connectors circuit sizes, configuration, pitch, and board attach terminations are the predominant factors involved.


Sierra Circuits is
headquartered in Silicon Valley.
We welcome visitors at
our 70,000 sqft facility,
located at 1108 West Evelyn Avenue
in Sunnyvale, California.
Book a tour with an account manager today!
Let us introduce you to one of the most innovative communities of engineers and designers in the world.
We can help you plan your project from design to assembled board.


Our 70,000 sqft state-of-the-art campus in the heart of Silicon Valley contains the most advanced equipment required for the manufacture and assembly of your PCBs. Whether you’re looking for standard quick turn PCBs or boards with the tightest tolerances, made from exotic metals, there’s a reason Sierra Circuits leads the industry in quality and performance.

PCBs manufactured and assembled in the United States


Sierra Circuits can manufacture your PCB and have it expedited to you within 24 hours.

Full turnkey boards, with assembly and components in as fast as 5 days.

Get an Instant, Itemized Quote


24 hours a day, 7 days a week.

Call us: +1 (800) 763-7503
Email us: through our Customer Care form

澳洲8历史结果 极速飞艇最新开奖结果 极速赛车计划网 澳洲幸运8开奖预测 SG赛车怎么玩的