Impact of 3 Oz PCB in Electronic Manufacturing

Copper is a core material used in the fabrication of PCB boards. The thickness of copper in PCBs varies. In the PCB industry, Copper thickness is usually measured in ounces (oz). In this article, we will be discussing 3 Oz PCB.

3 Oz PCB – What is it?

This is a type of PCB featuring copper layers that weigh 3 Oz. Manufacturers arrange copper layers in an order to fabricate 3 oz copper PCB. There are different PCBs with varying copper weights. 3 oz copper thickness is 4.2 mils and 105 micrometers. The 3oz copper board is a yardstick for determining a heavy copper PCB.

The copper separation around the PCB impacts the design of the circuit board. The finished copper thickness of 3 Oz copper PCB is 3 oz. The current carrying capacity of this PCB can determine its thickness.

3 oz copper thickness is about 10 mils. Also, 3 oz copper thickness is 105 microns. Due to the extreme thickness of the 3 oz PCB, it is also called a heavy copper board. Manufacturers use solder masks to adjust the copper layers over one another. This helps to achieve the required thickness level of the PCB.

Boards with thicker copper would require more spacing. Therefore, spacing is an important factor of consideration in 3 oz boards.  These boards can carry an average current of 30 Amps in a circuit.

Design Considerations for 3 oz PCB Fabrication

The manufacturer will need to determine the thickness of the copper conductor trace. This is very important before designing 3 Oz copper PCB. Below are design considerations for 3 oz PCB fabrication.

Trace spacing

Spacing is an important factor to consider when designing 3 oz PCB. It is important you understand that heavier copper PCBs require more spacing. There is minimum spacing for 3 oz metal copper boards at 10 mils. The creepage and clearance aspects define spacing in a board. Proper spacing will help to ensure flashover reduces.

Increased current carrying capacity will result in high trace spacing. Proper spacing can prevent flashover or tracking between traces. Tracking acts as an electrical breakdown on the surface of the PCB.

Connection points

These help to determine where the electronic components are on the PCB. Manufacturers should use clear markings in the design. This will enable the use of appropriate masking techniques.

Trace width

The trace width refers to the wideness of the conductive trace on the board surface. Also, it offers a connection to components on the board. The trace width will determine the current-carrying capacity of the conductor path.

Hole placement

This is a design consideration that determines the location of the drilled holes. Hole misplacement can interfere with the design of the board. This can lead to financial costs.

Benefits of 3 Oz Copper PCB

The major benefits of 3 oz copper PCB are:

  • It provides mechanical support to the PCB
  • Enhances conducting pathways in PCBs
  • It laminates the non-conductive pathways on the substrate
  • It enhances signal transmission in a circuit
  • Connects electronic components to the circuits
  • It prevents electricity wastage
  • Features great heat and electric conductor
  • Enhances heat transfer along with the circuit board

How to Determine 3 oz Copper Thickness

To determine 3 oz copper thickness, check the height of the copper traces available in the PCB. You can examine the PCB in three dimensions. Also, you can get some hints from the copper layer information on the Gerber Files.

Manufacturers measure copper layers in PCBs in ounces per sq. f. Furthermore, it is important to measure the copper thickness on PCB circuits. You can measure external factors like the pressure environment or standard temperature.

215.3 is the common scale factor for measuring external factors of the circuit. The conversion method is another approach for evaluating the copper thickness of this PCB. This method multiplies the thickness of the PCB layer by 1.37 mils.

Also, some substantial factors affect the copper thickness in heavy circuit boards. These factors include:

  • Base material tolerances
  • Flow characteristics
  • Prepreg tolerances
  • The copper layout on the circuit
  • PCB lamination process

Materials Used for 3 Oz Copper PCB

Manufacturers use several kinds of materials to fabricate 3 oz copper PCBs. Tin alloy is one of those materials. This material helps to add to the thickness of the heavy copper PCB. Also, 3 oz copper PCB comprises other conductive materials to help enhance functionality.

For instance, steel wood in PCB circuits helps to make the board sturdy and stable. Carbon steel is another type of material used in the fabrication of heavy copper boards. The manufacturer coats the prepreg with resin.

Manufacturers incorporate prepreg in 3 oz PCB to ensure the circuit can tolerate extended temperatures.  Fr-4 materials are commonly used for fabricating 3 oz PCBs. This material comprises epoxy reinforced fiberglass. FR-4 features poor electrical conductivity. Therefore, it is a good insulator. Also, Fr-4 is lightweight, although it features a rigid mechanical structure.

When selecting the materials for 3 oz copper boards, do the following:

  • Check the material’s thermal conductivity
  • Check the material’s impedance control
  • Inspect the material thickness
  • Check the Dk of the material

Factors to Consider when Choosing 3 Oz Copper PCB

There are factors you should consider when choosing 3 oz PCB. They include:

Space requirement

The space of the device you intend to use 3 oz copper PCB matters. If there is enough space for this PCB, you can use it. However, if there is no space for its installation, go for thinner boards.

PCB impedance

The PCB thickness should be compatible with the impedance of the circuit. The dielectric material in 3 oz PCB impacts the impedance control in the circuit.

Copper PCB weight

Ensure you consider this factor when choosing 3 oz copper PCB. Thinner boards are mostly used in flexible applications because their lightweight. However, thinner copper boards can break easily due to their flexibility. Thicker boards don’t break easily.

Components and connections availability

3 oz copper PCB comprises various types of connections and components. Therefore, ensure you choose the copper PCB that can withstand all types of connections and components.


3 Oz copper PCBs are very ideal in several applications. These heavy copper boards feature great properties and benefits. These boards feature more copper layers than 1 oz and 2 oz copper PCBs.

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