Barebone PCB prototype is a powerful testing tool for the designers that offers time and cost-saving benefits while ensuring a top-quality final product. The vital parameters that should be tested include component value, frequency at which component is operated, operating and storage temperature ranges, shock/vibration resistant property, and power supply range. The PCB design testing is sometimes done by building breadboard circuits, prototype PCB, and subjecting them to rigorous testing.

What is a barebone PCB?

barebone PCB without soldermask

Barebone PCB

Barebone PCB is the basic and fastest board manufacturing technique used for prototype making and a cheap way to test a circuit design. This prototype replaces the traditional “breadboard” or other manually wired variants for testing new designs. Barebone boards typically consist of etched copper on bare FR4

These boards are produced quickly by eliminating some of the common steps like image transferring involved in PCB fabrication. Barebone boards will not have soldermask, internal cutouts, and silkscreen. The reduced manufacturing process enables the fabricators to achieve a quick turnaround time.

Barebone PCBs are generally used to test the functionality of any new design. However, the bare board often refers to the state of a PCB before component placement and through-hole drilling. Bare boards generally consist of dielectric material, copper traces, and metal coating.

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Materials used in barebone prototypes

Barebone circuit boards are generally made of the following PCB materials: FR-4 fiberglass, copper traces, and plated holes.


PCB Material Design Guide

The below table shows some of the key considerations for barebone PCBs.

Parameter Specifications
Dielectric material FR-4 with glass transition temperature ranging from 135°C to 180°C and dielectric constant of 4.5±0.2
Metal foil 1oz copper foil is preferred
Soldermask Not allowed
Operating temperature 125°C maximum
Internal slots and cutouts Not allowed
Layers 1 (or 2, if required)
Minimum trace width 0.005”
Annular ring size 0.005” or greater

HDI PCB material selector by Sierra Circuits

How to use barebone circuit boards?

Barebone circuit board assembly process:

  1. Place all the components you need on your PCB to get your desired functionality.
  2. Take a print of the schematic diagram and examine the placed components. Ensure that components are placed precisely according to the diagram.
  3. Solder all your components onto the board. Extra care should be taken when handling the polarity of capacitors and diodes.
  4. Mount your microcontroller IC socket on the corresponding footprint and solder it carefully.
  5. Place and solder the programming headers and power source connector jacks.

How to solder barebone PCBs?

We know that most PCBs use solder masks to prevent the formation of solder bridges between pads. Since barebone PCBs do not have a solder mask, extra care should be taken during the soldering process. When soldering a barebone prototype, it is recommended to avoid over-usage of solder paste which could lead to the formation of bridges between the pads. Hand soldering is also a good option.

See how to achieve perfect PCB soldering.

Advantages of barebone circuit boards 

Lower costs: Using barebone PCBs reduces the materials to be used to fabricate the PCBs. This in turn will reduce the overall production expenses.

Eco-friendly: Since these PCBs require fewer materials when compared to other PCBs, they will eventually emit fewer waste products to the environment.

Barebone boards are necessary to carry out tests to verify whether a PCB design will perform its intended function. It is always recommended to use barebone PCBs to test your new designs and revisions to ensure design success. If there’s anything specific that you would like to know about PCBs then please let us know in the comments section.


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This post was first published on: Sierra Circuits