Table of Contents
The best quality of PCB depends on PCB trace thickness. It is a design parameter and determines the current carrying capacity of a trace, affects thermal management, and ensures long-term survivability.
Main Components of PCB Trace Thickness
1. Copper Trace
Different components are connected through copper traces that are conductive pathways embedded on the PCB.
The electrical and thermal properties of the trace are determined by the copper layer thickness, in terms of ounces per square foot. Standard pcb copper thickness levels are 1 oz/ft², 2 oz/ft², and 3 oz/ft².
2. Trace Width vs. Current
Trace width decides how much current a trace on a PCB can handle. A trace of larger width may get hot while carrying high current, and a thin trace will be more costly to produce and will take more space.
You can use the IPC-2221 standard to keep trace width for specific current levels.
PCB Trace Calculator for PCB Design
PCB trace design determines copper trace thickness, width and length to be on the PCB. They are accountable for representing the current carrying capacity, signal integrity and board performance. A well-designed trace prevents overheating, provides good current flow and minimizes EMI.
PCB Trace Thickness Calculator
A PCB trace thickness calculator is utilized to determine the appropriate trace thickness as a function of current, allowable temperature increase. It is one of the key instruments for effective and accurate PCB design.
PCB Trace Width Calculator
The trace width calculator calculates the minimum trace width in order to safely conduct a specified current. The calculators consider copper thickness, trace length, and the operating temperature.
How to Calculate
PCB Trace Current of Width?
A 2 oz copper PCB trace of around 20 mils would suffice for the 2A of current external; internally it would do around 35 mils trace width. Based on these cases, one would be able to design the traces accordingly using calculators, taking stringent design constraints into consideration.
A manufacturer must design a PCB trace that will carry at least 2A on a 1 oz/ft² copper PCB. The trace is on an outer layer, and the acceptable temperature rise will be 10°C.
Step 1: Estimating Thickness of Copper
For copper of 1 oz/ft², the thickness is approximately 35 µm (1.37 mils).
Step 2: Utilizing a Trace Width Calculator
Input the parameters through the calculator:
| Current | Copper Thickness | Temperature Rise |
| 2A | 1 oz/ft² (35 µm) | 10°C |
The calculator suggests trace width for outer layer should be 25 mils.
Step 3: Design Verification
Apply IPC-2221 standards to recheck the calculation for compliance with industry standards. Then, simulate the design on PCB software to confirm that trace width satisfies current and thermal demands.
PCB Trace Width and Thickness
Calculation Guide
For ease of understanding, let’s detail the step-by-step process for trace width and thickness calculation.
Case Type: High-Current PCB (5A/Inner Layer)
Standards and Tools
Standards
- IPC-2152-2022: General Specification for Current Carrying Capacity of PCBs (Main)
- IEC-62391-1: Reliability Design Specification (Mechanical Stress)
- UL 60950-1: Equipment Safety Requirements (Temperature Rise Limits)
Design Tools
- Saturn PCB Toolkit V8.03 (Current Carrying Calculation Module)
- IPC-2152 Temperature Rise Curve Atlas (2018 Revision)
- ANSYS Icepak Thermal Simulation Suite
Parameter Settings
- Copper Foil Thickness: 2 oz/ft² (70μm) ±10% (meets IPC-6012B Class 2 standard)
- Continuous current: 5A (6A peak, meets IEC-62391 transient requirements)
- Temperature rise limit: ΔT=10℃ (FR4 substrate Tg≥130℃)
Calculation Process of Current-Carrying
Formula:
I_{max} = 5A \times 1.2 (\text{safety}) = 6A
- Select IPC-2152 Figure A.7 (inner layer natural convection curve)
- Theoretical calculated value: 68 mils
Engineering Correction:
- Manufacturing Tolerance Compensation: +10%
- Aging margin: +10%
W_{final} = 68 \times 1.2 = 82 \text{ mils} \quad (\text{Rounded to 80 mils})
Thermal Through-Hole Array Design
Process and Layout Requirements
- Staggered Array to reduce thermal resistance by 30%.
- Density control: 4 / inch (pitch = 250 mils)
- Hole size specification: drill 10 mil → product ≥ 8 mil (in line with IPC-6012 Class 3)
Three-Stage Heat Dissipation System
Heat Sink Pad Design
- Minimum size: 400 x 400 mils² (heat flux 0.25W/mm² verified)
- Approach to connection: Full Perimeter Soldering (Reduce Contact Thermal Resistance)
Copper Mesh Optimization Strategy
- Mesh parameters: 20/20 mils (line width/spacing)
- Window opening rate: ≥60% (Heat dissipation and EMC considerations)
Verification Test Flow
ANSYS Icepak Simulation Steps
1. Import PCB stacked layer structure (material thermal conductivity)
2. Specify boundary conditions: ambient temperature 40 ℃ / natural convection
3. Apply 5A continuous current (running time ≥ 30 minutes)
4. Acceptance criteria: Maximum temperature ≤48℃ (ΔT=8℃)
Typical Simulation Report
| Parameter | Theoretical value | Simulation value | Deviation |
| Wire Width | 80 mil | 80 mil | 0 |
| Number of vias | 32 | 28 | -0.125 |
| Peak Temperature | 48℃ | 49.2℃ | 0.025 |
Physical Testing
Infrared Thermal Imaging Test
Test environment: closed constant temperature box (40 ± 1 ℃)
Loading method: 5A DC source (ripple ≤ 3%)
Sampling period: Record heat distribution map every 5 minutes
Safety threshold: local hot spot ≤105℃ (FR4 glass transition temperature -20℃)
Accelerated Aging Test
Test standard: IEC-60068-2-14
Cycling conditions: -40℃(30min) → +125℃(30min)
Failure Judgment
Resistance change > 15%
Micro-cracks are seen (200 times microscope detection)
Validation Checklist for High Current Boards
- Hot over-hole and thermal pad contact area ≥ 80%
- Icepak simulation run time ≥ 3 thermal time constant
- Insulation resistance ≥100MΩ after aging test
Conclusion
PCB trace thickness is a concern for manufacturers who want to produce efficient and reliable PCBs. In terms of trace design, copper thickness, and current carrying capacity, using trace thickness and width calculators, you can get the best out of it.
No matter if you are manufacturing for low current or high power purposes, this will ensure success in your PCB production project. And do not forget to contact ELEPCB for quality PCB services.
FAQs
A1: For traces on the outer layers of a 1 oz copper PCB that carry 2A, use about 25 mils. For precise values, use a calculator.
A2: Thicker traces are less resistant; this reduces voltage drop and hence heat generation. They do, however, consume more copper; therefore adding expense.
A3: No. Internal layers have poor heat dissipation and usually require wider traces of the same current as external layers.
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