What is a Bare PCB Board

As the name suggests, bare boards are printed circuit boards (PCBs) without the functional components, including the circuitry and through-holes. These boards consist of only a substrate, metal coating, and conductive pathway, forming the foundation for the future PCB.

Bare boards are designed to be configured, so they can be used to test design, concept, and functionality before more expensive components are assembled. Because of this, bare boards offer a lot of benefits in cost and time savings, early defect detection, time-to-market for a competitive edge.

Benefits of a Bare PCB Board

The greatest benefit of a bare PCB board is the cost savings. Concept, design, testing, and basic assembly and fabrication take place early in the process, ensuring that the board is durable and functional. Because problems can be identified early, it prevents money being lost from improper assembly with expensive components.

Another benefit of a bare PCB board is time. Like the cost savings, early prototyping and testing ensures everything functions according to the specifications of the design, so no time is wasted building a full, but ineffective, PCB board. Despite the upfront time investment, the streamlined process can improve the turnaround time and time-to-market.

Finally, without components, boards are easier to test and evaluate. The board’s layout, printing, and surfaces aren’t obfuscated by electrical components or other obstacles, so they can be evaluated on the basis of the layout and design. Any issues in the circuitry or desired components can be assessed and corrected before the full circuit is in place.

What Are Bare PCB Boards Used for?

Bare PCB boards are used for proof-of-concept and as a foundation for a fully functional PCB. Once assembled, a PCB may be used across a variety of industries, including medical devices, automotive components, and consumer electronics.

Some of the specific devices include:

  • Infusion pumps
  • Medical imaging, such as ultrasonic scanners and CAT scans
  • Pacemakers
  • LED lighting for residential and commercial use
  • Computer displays and components
  • Automotive indicator lights, headlights, and brake lights
  • Smartphones and tablets
  • Entertainment systems, such as televisions, stereos, and video game consoles
  • Appliances, such as refrigerators, microwaves, and coffee makers
  • DC-to-AC Power inverters
  • Pressure and temperature monitors for industrial equipment
  • Accelerometers for aircraft, marine craft, and vehicles
  • Satellite systems
  • Communications systems
  • GPS and radar systems
  • Cameras
  • Smoke and carbon monoxide detectors
  • Modern electronic door locks
  • Modems, routers, and VoIP devices

As the manufacturing and assembly processes became more accessible, practical, and cost-effective, more and more products and devices were able to use PCBs.

Ultimately, bare PCB boards are used to test the design and save time and money in the production process, which may occur due to errors or defects. A well-designed bare board can streamline production and eliminate delays or wasted resources.

Why Use Bare Board Testing?

Bare boards are advantageous for their testing capabilities. Once the design is rendered and the bare board moves into the fabrication process, it must be tested for proof-of-concept. Several steps are involved in the fabrication process, including printing circuitry images onto the layers, laminating them (multilayer boards), drilling through holes, and applying solder mask and surface finish. Testing is done to verify and validate each of these measures before the production process continues.

Types of Bare Board Testing

Bare boards may be tested several ways:

  • In-Circuit Testing: This is the most robust type of testing. Also known as “bed of nails” testing, this method powers up and actuates the individual circuitry using fixed probes laid out to match the circuitry design. Each probe checks the integrity of the solder connection. Planning for in-circuit testing must occur in the design phase.
  • Flying Probe Testing: This type of testing is commonly used and involves nonpowered testing, checking for opens, shorts, resistance, capacitance, inductance, and diode issues. To test, needles are attached to the probe on an X/Y grid from the CAD to match the circuit board.
  • Automated Optical Inspection (AOI): AOI uses a single 2D camera or two 3D cameras to photograph the board and compare them to a schematic. If the board doesn’t match the schematic, it can be flagged for visual inspection from a technician. AOI is useful for detecting issues early and changing production plans, but it doesn’t power the board and is not 100 percent effective. Typically, AOI is combined with other testing methods.
  • Burn-In Testing: This type of testing can be used to detect failures early and establish the load capacity of the board. It uses burn-in methods and pushes through the electronics to see if the board fails. Because of its intense method, this type of testing can be destructive to the board, but may identify serious defects before product launch.
  • X-Ray Inspection: This method of testing is used more for inspection, as an x-ray technician can use radiographs to identify defects in the early stages of manufacturing, such as solder connections, barrels, and internal traces. This is used to check elements that may be hidden from view.

How Testing Saves Time

Full PCB production can take weeks, if not months, to complete. High-volume orders may take even longer. If a PCB design proceeds to fabrication, assembly, and mass production with a defect or dangerous failure, the entire project needs to be scrapped and started over. Even if a defect is caught in pre-production phases, it could still be too late to correct the issue.

Bare board testing solves this problem. Testing of bare boards takes place when the foundation of the board and its basic layout are complete. If the bare board passes the test, it indicates that the circuit should function as intended. At that point, manufacturers and designers have the confidence to move forward with the rest of production.

Bare Board Production at Gerber Labs

Whether an experienced engineer or a beginner hobbyist, Gerber Labs is your partner-in-design to turn your project dream into reality. We provide superior bare PCBs for both small- and large-scale production, and we’re here to help you through every step of the process. Contact us today to discuss your project!