What does the pcb 1 oz copper thickness refer to?

What does the pcb 1 oz copper thickness refer to?

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The copper thickness of 1 oz in a PCB refers to the thickness of the copper foil on the circuit board, typically measured in ounces (OZ). This thickness is a critical parameter in PCB design, affecting the board’s conductivity, heat dissipation, and overall performance. During design and production, the appropriate copper thickness must be selected based on specific requirements. In this article, we will explore the concept, significance, and applications of a 1 oz copper thickness PCB.

What is a 1 oz copper thickness PCB?

A 1 oz copper thickness PCB refers to the thickness of the copper foil on the circuit board, commonly expressed in OZ (ounces). In the electronics industry, 1 oz of copper thickness usually equals a copper foil thickness of 35 microns. The copper thickness of a circuit board is one of the key factors influencing its performance and quality.

Conversion Method

Area-to-Weight Relationship: In the PCB industry, the definition of 1 oz copper thickness is the weight of copper foil per square foot (FT²) or square inch, equaling 1 oz.

  • Conversion specifics:
    • 1 square foot is approximately 0.0929 square meters.
    • 1 oz equals 28.35 grams.
    • Using the density of copper (around 8.92 grams per cubic centimeter), the physical thickness of copper foil per square foot or square inch can be calculated.

The basic materials used to manufacture a 1 oz copper PCB typically include epoxy resin and polytetrafluoroethylene (PTFE). A 1 oz copper layer is generally applied to each thin layer of the PCB. If not otherwise specified in the design, most manufacturers will default to using a 1 oz copper layer. The thickness of 1 oz copper in millimeters is approximately 0.089 mm.

The Role of a 1 oz Copper Thickness PCB

A 1 oz copper thickness PCB plays a vital role in enhancing electrical conductivity, improving heat dissipation, increasing current-carrying capacity, improving signal transmission quality, boosting mechanical strength, and meeting the demands of high-performance applications.

  1. Enhancing Electrical Conductivity

    • Superior conductive material: Copper is an excellent conductor, far surpassing other common metals. Increasing the copper foil thickness, such as using 1 oz copper, significantly enhances the board’s electrical conductivity.
    • Improved stability: Thicker copper foil allows for more stable current transmission, reducing signal attenuation or instability caused by current fluctuations.

  2. Improving Heat Dissipation

    • Heat dissipation: Copper foil not only serves as a conductor but also helps dissipate heat. A 1 oz copper thickness provides better thermal performance, effectively releasing heat from the PCB, keeping the board’s temperature stable, and preventing performance degradation or damage due to overheating.
    • Increased safety: Good thermal performance protects electronic components from high temperatures, improving the overall safety and reliability of electronic products.

  3. Increasing Current-Carrying Capacity

    • Enhanced capacity: Thicker copper foil can handle higher current loads, which is crucial for high-power, high-frequency electronic devices. A 1 oz copper thickness PCB meets the current-carrying demands of such devices, ensuring circuit stability and reliability.

  4. Improving Signal Transmission Quality

    • Reduced impedance: The thickness of the copper foil affects the impedance of the PCB. Thicker copper foil reduces impedance, thus improving signal transmission quality—especially important for devices requiring high-speed, high-quality signal transmission.

  5. Boosting Mechanical Strength

    • Increased strength: The thickness of the copper foil also influences the mechanical strength of the PCB. A 1 oz copper thickness increases the board’s overall mechanical strength, making it more durable and capable of withstanding greater mechanical stress.

  6. Wide Application Range

    • High-demand applications: Due to its numerous advantages, a 1 oz copper thickness PCB is widely used in electronic devices that require high conductivity, excellent heat dissipation, strong current-carrying capacity, and superior signal transmission quality, such as communication equipment, computer systems, medical devices, and military hardware.
The Role of a 1 oz Copper Thickness PCB

Why Use 1 Ounce Copper?

Here are some of the main reasons 1 ounce copper became the standard for PCB fabrication:

Electrical Performance
●Thick enough for low resistance power distribution on supply layers.
●Thin enough for controlled impedance on signals below 100 MHz.

Physical Strength
●Provides adequate structural integrity minimizing risk of cracking.
●Durable enough for multiple via holes, component holes, and cutouts.

Etching Capability
●Thin traces/spaces can be reliably etched compared to higher copper weights
Cost.
●Lower material cost compared to thicker copper foils.
●Reduces fabrications steps like sequential lamination.

Soldermask Process
●Compatible mask thicknesses exist that can cover 1 oz copper.
●Thicker copper requires screen printing process.

The 1 oz weight occupies the sweet spot balancing electrical, mechanical, and fabrication requirements while avoiding the cost and complexity of thicker copper PCBs.

Manufacturing Process of a 1 oz Copper Thickness PCB

  • Substrate Preparation
    The substrate undergoes cleaning, drying, and other pre-treatments to ensure the surface is clean and free of impurities.

  • Copper Foil Bonding
    The copper foil is firmly bonded to the substrate surface using a lamination process. This step requires precise control of temperature, pressure, and time to ensure a strong bond between the copper foil and the substrate.

  • Pattern Transfer
    A layer of photoresist or light-sensitive film is applied to the surface of the copper foil.
    The circuit design is then transferred onto the photoresist using exposure and development processes. High-precision exposure machines and developing equipment are used to ensure the accuracy of the pattern.

  • Etching
    Chemical etching solutions remove the unprotected areas of the copper foil, leaving only the desired circuit pattern. Since 1 oz copper thickness is relatively thick, the etching process may take longer and require stronger etching solutions.

  • Plating (Optional)
    If there is a need to further increase the copper thickness or improve its conductivity, electroplating may be performed. During this process, a layer of metallic copper is deposited onto the copper foil through electrolysis, increasing its thickness and conductivity.

  • Surface Treatment
    Surface treatments like Hot Air Solder Leveling (HASL), lead-free tin spraying, or Electroless Nickel Immersion Gold (ENIG) are applied to protect the copper circuits from oxidation and corrosion, as well as to improve solderability.

  • Drilling and Cutting
    Drilling tools are used to create holes in the PCB for component installation and circuit connections.
    The board is then cut into the desired size and shape, ready for further assembly and use.

Application Scenarios of 1 oz Copper Thickness PCBs

1 oz copper thickness PCBs play a crucial role in a wide range of applications. Below is a summary of their primary use cases:

  1. High-Power Electronic Devices

    • Power supply systems: Including power modules, DC-DC converters, and high-power distribution boards. These devices require handling high current and power demands, and 1 oz copper thickness PCBs can efficiently carry the current and reduce resistance, ensuring system stability.
    • Electric vehicle components: Such as battery management systems (BMS) and electric power steering (EPS) systems. These systems demand high levels of current and heat dissipation, and 1 oz copper thickness PCBs provide excellent conductivity and heat management.

  2. High-Frequency Electronic Devices

    • Communication equipment: Including base stations, routers, and switches. These devices deal with high-speed signal transmission, and the superior conductivity of 1 oz copper thickness PCBs helps reduce signal attenuation and interference, enhancing signal quality.
    • Computer systems: Such as servers, workstations, and high-end graphics cards. These devices require high stability and efficient heat dissipation, which 1 oz copper thickness PCBs can provide.

  3. High-Reliability Equipment

    • Medical devices: For life-support systems and precision instruments, reliability and stability are critical. 1 oz copper thickness PCBs offer excellent durability and conductivity to meet these stringent demands.
    • Military equipment: Including radar systems and missile control systems, which must operate in harsh environments. The superior performance of 1 oz copper thickness PCBs ensures these devices function reliably under extreme conditions.

  4. Other Specialized Applications

    • High-power LED lighting: LEDs generate significant heat during operation, and 1 oz copper thickness PCBs help dissipate heat effectively, extending the lifespan of the LED lights.
    • Industrial control equipment: For automation systems, motor drivers, and other industrial machinery, which require handling complex control signals and drive currents. 1 oz copper thickness PCBs meet both conductivity and heat dissipation needs.

Conclusion

1 oz copper thickness PCBs, with their excellent conductivity, heat dissipation, and mechanical strength, are widely used in high-power, high-frequency, and high-reliability electronic devices. When selecting a PCB, it is essential to choose the copper thickness according to specific application needs to ensure optimal performance and reliability. As electronic technologies continue to evolve, higher demands on PCB performance will likely drive the adoption of new materials and manufacturing processes in the future.