A: A PCB Copper Weight refers to the thickness or amount of copper present on the PCB’s surface, particularly on the conductive layers. Copper is used in PCBs to create electrical connections and traces that carry signals between components, such as integrated circuits (ICs), resistors, capacitors, and other electronic components.

Copper weight is typically measured in ounces per square foot (oz/ft²) or micrometers (µm), depending on the unit system used. The two most common copper weights for PCBs are:

  1. 1 oz/ft² (approximately 35 µm): This is often called “1-ounce copper.” It means a layer of copper on the PCB’s surface is 1 ounce in weight per square foot.
  2. 2 oz/ft² (approximately 70 µm): This is called “2-ounce copper.” It signifies a thicker layer of copper, which is 2 ounces in weight per square foot.

Designers choose the appropriate PCB copper weight based on the specific requirements of the circuit. Thicker copper layers can carry more current and dissipate heat better than thinner ones. Therefore, high-power applications or circuits with high current requirements may use 2-ounce copper layers or even thicker PCBs. On the other hand, lower-power or less demanding circuits may use 1-ounce copper layers.

For example, a PCB copper weight of 1 ounce would have a thickness over 1 square foot of 1.4 mils (thousandth of an inch). 2-ounce would have a 2.8 mils thickness as indicated in the table below:

Copper Weight in ozCopper Thickness
1 oz1.4 mils
2 oz2.8 mils
3 oz4.2 mils
4 oz5.6 mils
Table: PCB Copper Weight and Copper Thickness

Selecting the right copper weight for your PCB design is essential to ensure it meets your application’s electrical and thermal requirements without causing issues such as excessive heat buildup or voltage drop. The choice of copper weight can affect the PCB’s cost, size, and performance, so it should be carefully considered during the design process.