Thickness Units: Understanding Measurement Standards in PCB Manufacturing

Introduction

Thickness measurement plays a crucial role in various industries, including PCB (Printed Circuit Board) manufacturing, metalworking, construction, and engineering. Different applications require precise thickness specifications, and various units of measurement are used to ensure consistency and accuracy.

This article provides a comprehensive overview of thickness units, their conversions, applications, and importance in PCB manufacturing.

thickness units

Common Thickness Units and Their Conversions

There are multiple units used to measure thickness, each relevant to specific industries and applications. Below is an overview of common thickness units and their conversions.

1. Millimeters (mm) and Micrometers (µm)

• 1 mm = 1,000 µm
• Widely used in PCB thickness measurement, electronics, and engineering.
• Standard PCB thicknesses include 0.8mm, 1.2mm, 1.6mm, and 2.0mm.

2. Inches and Mils (thousandths of an inch)

• 1 inch = 25.4 mm
• 1 mil = 0.001 inch = 25.4 µm
• Commonly used in PCB manufacturing, metalworking, and coatings.
• Example: Standard 1.6mm PCB thickness = 63 mils.

3. Gauge (Ga)

• Used for metal sheets, wires, and some PCB applications.
• Lower gauge numbers indicate thicker materials.
• Example: 16 Ga sheet metal ≈ 1.52mm (0.06 inches).

4. Ounces per Square Foot (oz/ft²)

• Used to specify copper thickness in PCBs.
• 1 oz copper = 35µm (1.4 mils) thickness.
• Common PCB copper thickness: 0.5oz, 1oz, 2oz, and 3oz.

Thickness Units in PCB Manufacturing

1. PCB Substrate Thickness

• Standard PCB substrates are available in thicknesses of 0.8mm, 1.2mm, 1.6mm, and 2.0mm.
• Thinner PCBs are used in flexible and wearable electronics.
• Thicker PCBs are used for high-power and industrial applications.

2. Copper Thickness in PCBs

• Expressed in ounces per square foot (oz/ft²).
• Common copper thickness values:
  • 0.5 oz = 17.5µm (0.7 mils)
  • 1 oz = 35µm (1.4 mils)
  • 2 oz = 70µm (2.8 mils)
• Higher copper thickness improves current-carrying capacity and heat dissipation.

3. Solder Mask and Surface Finish Thickness

• Solder mask thickness ranges between 10-50 µm (0.4-2 mils).
• Surface finishes like HASL, ENIG, and OSP have different thicknesses:
  • HASL (Hot Air Solder Leveling): 1-25µm (0.04-1.0 mils)
  • ENIG (Electroless Nickel Immersion Gold): 3-6µm (0.1-0.24 mils) gold, 120-250µm (4.7-9.8 mils) nickel

Importance of Thickness Measurement in PCBs

1. Electrical Performance

• Copper thickness impacts current flow and resistance.
• Thicker copper layers improve power distribution and signal integrity.

2. Mechanical Strength and Durability

• Thicker PCBs provide better mechanical support for components.
• Important for automotive, aerospace, and industrial electronics.

3. Heat Dissipation

• Higher copper thickness enhances thermal conductivity.
• Used in high-power applications like LED PCBs and power electronics.

4. Manufacturing Considerations

• Tolerance levels vary by manufacturer.
• Some PCB manufacturers offer custom thickness options.

Converting Thickness Units in PCB Design

1. Common Unit Conversions for PCB Thickness

2. Copper Thickness Conversions

Best Practices for Choosing PCB Thickness

1. Define Application Requirements

• Thin PCBs (0.8mm – 1.2mm) for flexible, lightweight applications.
• Standard 1.6mm PCBs for general electronics.
• Thicker PCBs (2.0mm – 3.2mm) for high-power applications.

2. Consider Mechanical Strength & Heat Dissipation

• Thicker PCBs withstand mechanical stress and improve thermal management.
• Used in automotive, power electronics, and aerospace.

3. Optimize Copper Thickness for Current-Carrying Capacity

• 1 oz copper is sufficient for most circuits.
• 2 oz or 3 oz copper is ideal for high-power applications.

4. Follow Manufacturer Guidelines

• Ensure PCB thickness aligns with assembly and manufacturing tolerances.
• Different PCB stack-ups may require custom layer thickness adjustments.

Conclusion

Understanding thickness units is essential in PCB manufacturing and design, ensuring optimal electrical performance, durability, and manufacturability. From substrate thickness to copper weight and solder mask coatings, precise measurement plays a vital role in electronics reliability and efficiency.

For high-quality custom PCB manufacturing, partnering with an experienced supplier like Shuoqiang Electronics ensures precision, compliance, and durability.

📩 Contact us today to discuss your PCB thickness requirements and explore tailored solutions!

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