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4 Oz Copper PCB

Jarnistech > Heavy Copper PCB > 4 Oz Copper PCB
4 Oz Copper PCB

The 4 oz PCB, also known as a heavy copper PCB, holds a prominent position in the electronics industry. Its widespread demand can be attributed to its unique characteristics and its application versatility.

For those seeking a deeper understanding of 4 oz PCBs and the significance of 4 oz copper thickness, this article aims to provide comprehensive insights. By delving into this topic, readers will gain a thorough understanding and expand their knowledge in this area.

What is a 4 oz Copper PCB?

The copper thickness of a printed circuit board (PCB) is typically measured in ounces per square foot (oz/ft2). This measurement refers to the weight of copper foil per square foot of board area, excluding the fiberglass substrate.

Standard copper weights for PCBs include:

●1 oz: 1 oz/ft2 (equivalent to 35 μm)
●2 oz: 2 oz/ft2 (equivalent to 70 μm)
●3 oz: 3 oz/ft2 (equivalent to 105 μm)
●4 oz: 4 oz/ft2 (equivalent to 140 μm)

Therefore, a 4 oz copper PCB contains approximately 4 ounces of copper foil weight per square foot on each conductive layer. In terms of thickness, 4 oz copper equates to approximately:

●140 μm (micrometers)
●5.5 mils
●0.14 mm (millimeters)

This heavy copper foil thickness offers exceptional performance and is well-suited for demanding electronics applications that require robust conductivity and power handling capabilities.

What is the Base Material of 4 Oz Copper PCB?

The choice of base material is a critical factor in the manufacturing of printed circuit boards (PCBs), as it directly impacts their functionality and performance efficiency.

For 4 oz copper PCBs, the commonly used base material is FR-4, which conforms to the standard operating temperature of 140 degrees Celsius. Additionally, there is the option to utilize High Transition Temperature (High Tg) material, which can withstand higher temperatures, typically around 170 degrees Celsius. The selection of the base material depends on the specific requirements of the project at hand, taking into consideration factors such as project type and complexity.

It is important to note that the choice of base material significantly influences the properties of the 4 oz copper PCB. Each base material possesses its own distinct characteristics and performance attributes. When comparing FR-4 and High Tg base materials, the resulting properties of the 4 oz copper PCB will exhibit notable differences based on the chosen base material.

Ultimately, the selection of the base material is driven by the specific requirements and preferences of the clients. By understanding the unique properties associated with different base materials, PCB manufacturers can work closely with their clients to identify the most suitable option that aligns with their project needs and objectives.

What is the 4 Oz Copper Thickness?

To ensure optimal performance of your printed circuit board (PCB), careful attention must be paid to its thickness. The thickness of a PCB plays a crucial role in its overall functionality and reliability.

When manufacturing 4 oz PCBs, precision is paramount to ensure accurate thickness. The standard thickness for 4 oz PCBs typically falls within the range of 0.6mm to 0.65mm. This standardized thickness helps maintain consistency and reliability across various applications.

In addition to thickness, the configuration of the PCB includes provisions for adding additional components based on the specific project requirements. Furthermore, the size of the PCB can vary depending on the project’s needs. The standard dimensions of the PCB can range from 6mm by 6mm to 467mm by 610mm.

It is important to note that the size and thickness of the PCB are influenced by the complexity of the project. These features are vital for the effective operation of the PCB and must be carefully considered during the design and manufacturing phases. Moreover, customization options are available to tailor the thickness and size of the PCB to meet the specific requirements of your clients.

By prioritizing precision and customization, you can ensure that the thickness and size of your PCB align with the project’s specifications, resulting in an optimized and reliable PCB solution.

How Many Layers Does 4 Oz Copper PCB Have?

The number of layers in a 4 oz copper PCB is a significant factor in its configuration. The choice of layer count depends on the specific requirements of the project at hand.

In general, a 4 oz copper PCB can be designed with either two layers or multiple layers. The simpler configurations typically utilize two layers, while more complex designs require multiple layers to accommodate the intricate circuitry and components.

The spacious nature of the 4 oz copper PCB allows for the addition of various components. In certain cases, an extra layer may be incorporated to accommodate additional components and enable enhanced functionality.

For projects with simpler electronic applications, a double-layer 4 oz copper PCB may suffice. However, for projects involving high-tech electronics and complex functionality, multiple layers of 4 oz copper PCB are generally employed.

It is worth noting that the standard number of layers for 4 oz copper PCBs typically ranges from 2 to 24. However, this can be customized based on the specific requirements and preferences of the clients.

Where to Use for 4 Oz PCB?

4 oz PCBs are highly valuable and versatile components that play a crucial role in the realm of electronics. Their unique characteristics make them applicable in various domains.

In the modern landscape of the BARE PCB industry, 4 oz copper thickness is employed in electronic devices that demand cutting-edge technology. Additionally, these PCBs find utility in welding equipment, where their capabilities are effectively harnessed.

Power converters rely on the configurations provided by 4 oz PCBs. Moreover, these PCBs are instrumental in high-tech space systems and radar systems, showcasing their significance in such advanced applications.

Furthermore, the automotive sector and solar panel systems benefit from the utilization of 4 oz copper PCBs. These PCBs serve vital roles in electric and general power supply systems, enhancing their performance and efficiency.

Control panels are integral in various industries, and 4 oz PCBs play a pivotal role in the manufacturing of industrial panels. Additionally, these PCBs can be found in vending machines, car dashboards, amplifier systems, and lighting systems, further exemplifying their wide-ranging applications.

How Does Manufacturing and Assembling for 4 Oz Copper PCB?

Manufacturing and assembling a 4 oz copper PCB involves a series of steps that encompass both the fabrication of the PCB itself and the subsequent component assembly. Here is a comprehensive overview of the process:

PCB Manufacturing:

a. Design and Layout: Create the PCB design using computer-aided design (CAD) software, defining the circuitry, component placement, and layer configuration.

b. Material Selection: Choose the appropriate base material, typically FR-4 or High Tg material, and copper foil with a thickness of 4 oz per square foot.

c. Substrate Preparation: Clean and prepare the substrate material, such as fiberglass-reinforced epoxy laminate sheets, by cutting them to the desired size and shape for the PCB.

d. Copper Foil Bonding: Apply heat and adhesive to bond the copper foil to the substrate, ensuring a strong and uniform bond.

e. Imaging and Etching: Apply a photoresist layer, expose it using a photomask with the desired circuit pattern, and then etch away the unwanted copper using an etchant solution, leaving behind the circuit traces.

f. Drilling: Precisely drill holes, known as vias, for component mounting and interconnection. These vias are typically plated with copper for electrical conductivity between layers.

g. Plating: Electroplate the PCB to deposit a thin layer of copper over the exposed circuitry and vias, enhancing conductivity and protecting the traces.

h. Solder Mask and Legend Printing: Apply a solder mask over the PCB surface, leaving only the desired soldering areas exposed. Print component designators, labels, and other markings using ink.

i. Surface Finish: Apply a surface finish, such as HASL, ENIG, or OSP, to protect exposed copper surfaces from oxidation and facilitate soldering.

j. Testing and Inspection: Thoroughly test and inspect the manufactured PCBs using electrical testing, visual inspection, and functional testing to ensure quality and adherence to specifications.

Component Assembly:

a. Bill of Materials (BOM): Prepare a comprehensive BOM listing all the required components for the PCB assembly.

b. Component Procurement: Source and procure the necessary electronic components from reliable suppliers.

c. SMT (Surface Mount Technology) Assembly: Utilize automated assembly equipment to mount surface-mounted components (SMDs) onto the PCB, using solder paste and reflow soldering techniques.

d. Through-Hole Component Assembly: Mount through-hole components onto the PCB using manual or automated processes, such as wave soldering or selective soldering.

e. Inspection: Conduct visual inspection and automated optical inspection (AOI) to verify the correct placement and soldering quality of components.

f. Testing: Perform functional testing, electrical testing, and any required programming or firmware loading to ensure the assembled PCB meets performance and functional requirements.

g. Final Quality Check: Conduct a final inspection to ensure the PCB assembly is free from defects and meets all quality standards.

h. Packaging and Delivery: Clean, package, and prepare the assembled PCBs for shipment to customers, ensuring proper protection during transportation.

Throughout the manufacturing and assembly process, quality control measures are implemented to detect and rectify any defects, ensuring the production of high-quality 4 oz copper PCBs and reliable PCB assemblies.

What Are Key Indicators of 4 oz PCB Fabrication Quality?

To ensure the reliable production of high-quality 4 oz copper boards, there are several critical metrics and process capability markers that indicate the technical competence of a PCB manufacturer:

Tight Laminate Thickness Variation (<5%): The manufacturer should maintain a narrow range of laminate thickness deviation, ensuring consistent board thickness across the PCB.

Excellent Foil-to-Foil Registration (<0.10mm): Precise alignment of copper foils during lamination is crucial for accurate circuitry and signal integrity.

Void-Free Hole Fill Down to 0.15mm Vias: The manufacturer must achieve complete hole fill during the plating process, ensuring reliable conductivity and interconnection within the PCB.

Fine Line Resolution Down to 1 mil Line/Space: The ability to produce fine features with high precision is necessary for intricate circuitry and dense PCB designs.

High Peel Strengths Between Layers (>9 N/mm) with 0% Delamination: Adequate adhesion between PCB layers is vital to prevent delamination and ensure the structural integrity of the board.

Minimal Surface Roughness (<2 μm Ra): A smooth surface finish is essential for consistent solderability, component mounting, and reliable electrical performance.

Very Low Impedance Power/Ground Planes (<5 mΩ): Maintaining low impedance in power and ground planes is critical for minimizing signal noise and ensuring stable power distribution.

Well-Controlled Gold Plating Thickness (+/- 5%): Gold plating thickness should be tightly controlled to meet specific requirements for corrosion resistance and reliable electrical contacts.

Rigorous Incoming Material QC and Lot Traceability: Thorough quality control of incoming materials, along with comprehensive lot traceability, ensures consistency and reliability throughout the manufacturing process.

Extensive Inspection and Reliability Testing Capabilities: The manufacturer should have robust inspection and testing procedures in place to identify and address any potential defects or reliability issues.

Stringent Process Controls and Change Management: Well-defined and controlled processes, along with effective change management protocols, are necessary to maintain consistency and prevent deviations during production.

Zero-Defect Quality Culture at All Organizational Levels: A strong quality-oriented culture, supported by staff training and adherence to strict quality standards, ensures a focus on delivering defect-free products.

By evaluating a PCB manufacturer against these metrics and capabilities, you can assess their technical competence and determine their ability to reliably produce high-quality 4 oz copper boards.

Benefits of Partnering with a High Quality Manufacturer

Choosing a PCB manufacturer capable of flawless volume production with 4 oz copper offers significant advantages for electronics companies:

Accelerated Time-to-Market:

By avoiding the need for new process engineering efforts, companies can bring advanced 4 oz designs to the market faster.

Smooth Introduction with Reduced Risks:

Leveraging the expertise of manufacturers experienced in 4 oz fabrication minimizes initial issues and ensures a seamless transition to volume production.

Enhanced Performance:

Precision 4 oz fabrication enables companies to achieve their electrical, thermal, and reliability goals, resulting in improved overall product performance.

Robust Quality:

By partnering with manufacturers known for consistently delivering defect-free boards, companies can minimize delays and shortages caused by quality issues.

Reliable Long-Term Supply:

Strategic relationships with manufacturers specializing in 4 oz PCB fabrication ensure a steady supply of high-quality boards, while also allowing for ongoing performance improvements.

Cost Savings:

Taking advantage of economies of scale, companies can benefit from cost transparency and make informed decisions regarding tradeoffs, leading to cost savings in the production process.

On-Demand Flexibility:

Manufacturers proficient in 4 oz copper technology can quickly adapt to changing requirements by offering responsive small batch builds, providing companies with the flexibility needed to meet evolving market demands.

Why Choose JarnisTech for Your 4 Oz Copper PCB

If you are seeking a reliable supplier for 4 oz copper (140um or 56mil) PCBs, JarnisTech is the optimal choice. With over 12 years of experience in PCB manufacturing, JarnisTech possesses extensive expertise in producing 4 oz copper PCBs.

Our 4 oz copper PCBs, commonly known as heavy copper or thick copper PCBs, are particularly suitable for power supply products. At JarnisTech, we offer customized options, allowing you to specify the size, number of layers, surface finishes, and appropriate solder mask for your PCB requirements.

We cater to a wide range of 4 oz copper PCB types, including single-sided circuit boards, double-sided PCBs, multilayer PCBs, rigid printed circuit boards, flexible circuit boards, and rigid-flex PCBs. Our comprehensive inventory includes a full range of raw laminations, ensuring prompt production and timely delivery. Furthermore, we prioritize the use of high-quality materials in the manufacturing process, guaranteeing the reliability and performance of our 4 oz copper PCBs.

As a leading manufacturer and factory of 4 oz copper PCBs in China, JarnisTech is committed to meeting all of our customers’ requirements. Our dedicated team of over 1000 skilled workers operates in two shifts, enabling us to accommodate orders for prototypes, small volumes, and large volumes of 4 oz copper PCBs.

When designing your 4 oz copper PCB, we recommend a minimum trace width/space of 8 mil/8 mil. This ensures optimal performance and manufacturability.

For further information or inquiries, please do not hesitate to contact us. We are readily available to assist you with any questions or concerns you may have.


To fully leverage the capabilities of advanced thick copper technology, it is essential for electronics product designers to establish a collaborative partnership with a skilled and dependable PCB manufacturer like JarnisTech. Our manufacturing expertise enables us to deliver flawless quality multilayer boards with 4 oz copper, offering numerous advantages such as low loss, high current capacity, improved thermal performance, and enhanced layout density.

By choosing JarnisTech as their partner, engineers can effectively mitigate risks, elevate the overall performance of their end products, and seamlessly embrace the cutting-edge 4 oz PCB technology. Our commitment to precision and reliability ensures that designers can confidently rely on us to meet their specific requirements and achieve successful outcomes.

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