Introduction

DFM stands for Design for Manufacturing. DFM check is the process of analyzing a product design to ensure it can be manufactured efficiently and cost-effectively.

With DFM analysis, engineers examine the design to identify and correct issues before releasing it to production. This avoids costly manufacturing problems down the line.

In this comprehensive guide, we will cover:

• The importance of DFM analysis
• When DFM checks should be performed
• The major areas analyzed in a DFM check
  • Tolerances
  • Clearances
  • Draft angles
  • Surface finishes
  • and more
• DFM principles and guidelines
• Performing manual vs automated DFM checks
• Fixing DFM violations
• FAQs

By the end of this article, you will have a strong understanding of what DFM analysis entails and how it improves manufacturability. Let’s get started!

The Importance of DFM Analysis

DFM analysis provides enormous benefits for manufacturing by optimizing the design early on. Here are some key reasons DFM checks are critical:

• Saves money – It is far cheaper to fix issues in design stage rather than after production starts. DFM optimizes costs.
• Prevents defects – Flaws from a problematic design get replicated in every manufactured unit. DFM catches problems before they occur at scale.
• Avoids delays – A faulty design necessitates reworks and retrofits, stalling production. DFM prevents this wasted time.
• Improves quality – DFM facilitates higher assembly success, fewer scrapped parts, and consistent quality.
• Increases manufacturability – The design gets tailored to the capabilities of the manufacturing process.

For these reasons, leading engineering teams perform extensive DFM checks before releasing any product to the factory floor. The ROI from avoiding manufacturing issues is tremendous.

When Should DFM Analysis Be Performed?

DFM checks should be performed at multiple stages of the design process:

• Conceptual design phase – Early DFM analysis ensures the design direction inherently accounts for manufacturing best practices.
• Detailed design phase – Rigorous DFM checks should be conducted once the detailed design is frozen before release to production.
• Design revisions – DFM checks also needed whenever design changes are made to ensure no new issues are introduced.

In general, DFM checks should be an ongoing process throughout development rather than a one-time step at the end. Issues caught early in design iterations can prevent costly changes later down the line.

For complex products, DFM checks may be performed by a dedicated manufacturability engineering team. They take the designer’s CAD model and run intensive DFM analysis on it as a service.

No matter the design phase, integrating DFM as early and often as possible is key for optimizing manufacturability.

Major Areas Analyzed in a DFM Check

DFM analysis involves assessing the design from multiple aspects that impact manufacturing. Here are some of the major areas checked in a DFM review:

Tolerances

• Tolerance stackups calculated to ensure parts will fit together within specified range
• Tolerances not too tight for process capabilities
• Statistical tolerance analysis conducted where possible

Clearances

• Sufficient clearances between components for material thickness
• Adequate clearances to access assemblies and fasteners
• Clearances checked for operation without interference
• Minimum electrical clearances met

Draft Angles

• Draft angles added on vertical faces to ease ejection from molds
• Uniform draft angle between adjacent faces
• Adequate draft for deep/high parts and materials used

Hole Sizes

• Hole diameters meet tap drill sizes for specified thread types
• Hole sizes account for plating tolerances if plated
• Large holes have web thicknesses for required strength

Surface Finishes

• Appropriate surface finish specs for functional needs
• Finishes avoid tight textures causing friction or galling
• Radius surface finishes specified where needed

Heat Sinks

• Heat sinks sized properly for heat load and air flow
• Thermal interface material thickness considered
• Fins aligned with air flow direction

Welds

• Weld types appropriate for materials and joint design
• Gaps provided for welding access
• Distortion from weld process and sequencing minimized

Part Symmetry

• Parts designed symmetric where possible to avoid orientation concerns
• Non-symmetric parts clearly identified in drawings

Stamping and Forming

• Draw depths and minimum radii suitable for material thickness
• Bend radiuses checked for sheet metal parts
• Stamping web widths adequate for strength

Molding

• Draft angles provided on molded parts
• Radii added to corners to ease fill
• Core pins accessible and adequate for details
• Undercuts eliminated unless using collapsible cores

Casting

• Casting draft present with proper direction
• Minimum thicknesses to avoid porosity observed
• Appropriate finish allowances specified

Fastening and Joining

• Fastener sizes appropriate for materials and assemblies
• Fastener spacings meet engineering requirements
• Adhesives and press fits designed for required strength

Part Handling

• Points identified for safe automated part handling
• Low friction surfaces checked where automated sliding occurs
• Weight limits observed for manual lifting and ergonomics

Assembly Sequence

• Efficient tabs snap features used where helpful
• Conditional assembly sequences enabled where needed
• Assembly performed from stable datum points first

Test and Inspection

• Test points provided to verify full assembly
• Key dimensions defined for in-process inspection
• Go/no-go assembly checks incorporated

This covers some of the major areas scrutinized during a thorough DFM analysis. The full scope depends on the specific design and manufacturing process.

Key DFM Principles and Guidelines

While checking the above details, DFM engineers are guided by fundamental DFM principles that influence the overall manufacturability of a design:

Simple and Intuitive

• Design should be as simple as possible while still meeting functional needs
• Avoid unnecessary complex geometries and mechanisms
• Intuitive assemblies are easier to manufacture correctly

Error Proofing

• Incorporate go/no-go checks to prevent incorrect assembly
• Include guides, keys, and asymmetry for foolproof assembly
• Eliminate ways to assemble incorrectly through smart design

Standardization

• Maximize use of standard parts, materials, processes
• Follow industry and in-house standards where possible

Process Capabilities

• Stay within known process capabilities -avoid pushing limits
• Account for inherent process variation in tolerances

Modularity

• Break complex designs into self-contained modules
• Standard interfaces between modules for flexibility
• Modules can be made and tested independently

Consolidation

• Combine parts into single parts where possible
• Avoid unnecessary joints/fasteners to consolidate

Handling

• Design parts to be easily handled and positioned
• Add fiducials and other features to assist automation

Service and Repair

• Enable access to lifecycle maintainable components
• Fasteners, connectors, etc. designed for serviceability

By adhering to DFM principles like these, engineers can design products with manufacturing in mind right from the start. This flows into all the detailed checks conducted later.

Performing Manual vs Automated DFM Checks

DFM analysis is traditionally conducted manually by experienced engineers trained in manufacturing processes. However, automated DFM checking software has also emerged to supplement manual review.

Manual DFM Checking

With manual DFM analysis, engineers use their expertise to:

• Visually inspect CAD models for issues using a checklist
• Calculate key dimensions, stacks, and clearances by hand
• Simulate assembly sequences to validate manufacturability
• Judge surface finishes, drafts, radiuses by sight
• Suggest design changes to fix found issues

Manual checking taps into an engineer’s manufacturing knowledge. But it can be tedious and prone to human error.

Automated DFM Checking

DFM software automatically checks models for common issues like:

• Insufficient draft angles on faces
• Tight component clearances
• Hole dimensioning errors
• Thickness and radius violations
• Interference detection
• Standard violation checking

Automated tools provide consistent, rapid analysis. But software cannot fully replace an engineer’s judgement and insight yet.

In practice, the two methods are combined – engineers first run an automated DFM analysis then manually review the flagged issues. This gives the best results.

Fixing DFM Violations

When issues are identified from DFM checks, the designer needs to modify the CAD model to address them. Here are typical ways DFM violations are fixed:

• Relaxing tolerances – Increase tolerance windows to viable ranges
• Changing dimensions – Resize parts and geometry to meet requirements
• Adding draft – Add or increase draft angles where lacking
• Altering surface finishes – Change surface specs to better finishes
• Revising hole features – Modify hole sizes to suit tap sizes or add webbing
• Adding clearance – Provide adequate clearance between components
• Eliminating undercuts – Remove undercuts in molded parts through design changes
• Changing joinery – Revise joints, fasteners to improve assemble-ability
• Simplifying geometry – Simplify complex shapes to the basic functional geometry
• Separating parts – Break convoluted parts into simpler individual parts
• Refining assembly sequence – Optimize assembly steps for efficiency and clarity

Usually, many small changes are required versus one major redesign. The designer iterates to incrementally improve the design based on the DFM feedback.

Frequently Asked Questions

Here are some common questions that arise regarding DFM analysis:

Q: When should DFM analysis be done – by designers or by manufacturing engineers?

A: DFM principles should first be applied during the initial design phase. Later extensive DFM checks can be done by manufacturing engineers as an independent quality check.

Q: What are some limitations of automated DFM analysis tools?

A: Automated tools miss context-specific issues and have limited capability to suggest fixes. But they rapidly find basic issues like insufficient drafts.

Q: How is DFM analysis different for machined parts versus plastic injection molded components?

A: Each process has unique DFM considerations – for machining, avoid thin walls, deep pockets, and surfaces hard to reach with cutters. For molding, check drafts, radii, tolerances.

Q: What is the right level of detail for a DFM analysis?

A: It depends on the design complexity, production volume, cost, lead time, and other factors. Higher volume or cost products warrant extremely exhaustive DFM review.

Q: Is DFM analysis applicable beyond mechanical and physical product design?

A: Yes, the principles of optimizing a design for ease of execution extend to many fields. DFM concepts are relevant even in UX design, process design, and more.

Conclusion

DFM analysis is a critical step in optimizing a product design for manufacturing and assembly. By thoroughly checking key areas like tolerances, clearances, surface finishes, and reviewing the design from a manufacturing perspective, engineers can catch and correct issues early.

Performing DFM checks systematically at each stage of design, incorporating both automated tools and manual review by experienced engineers, results in the highest quality analysis. The ROI from avoiding manufacturing problems is well worth the effort invested into rigorous DFM practices.

With the methodology and best practices covered in this guide, you now have strong knowledge of what an effective DFM analysis entails. Leverage DFM practices in your organization to save costs, reduce defects, shorten time-to-market, and ultimately create products optimized for manufacture.

Free of Cost DFM Check

DFM (Design for Manufacturing ) is known as file check and it is basically an added value service that most of PCB manufacturers offer. The services of DFM are related to the checking of PCB design for any possibility of issues which may hinder the process of PCB manufacturing and fabrication. In case if any issues are sorted, customers are got in touch on immediate basis and issues are resolved at higher priority and fabrication of PCBs is arranged accordingly.

The DFM check offered by RayPCB is cost-effective of the system we use for DFM check is an autonomous way for enabling the manufacturing and fabrication system of PCBs hassle-free and sort out issues which cause trouble. The autonomous system of FDA check is known as Valor DFM. The system helps in lowering cost of PCB and saves time as well. The DFM is conducted on the basis of five aspects at RayPCB known as single layer and mixed layer checks, silkscreen checks, drill checks, and ground/power checks. The details are given below.

1. Drill Checks:

The action of drill checks is for finding out the potential defects which may hinder the manufacturing process in different layers of PCB. Statistics are generated on drill layers. The drill checks is supposed to be operated on drill layers only. It is using drill stack, bottom and top layers along with ground or power layer in stack. The checklists are given below.

2. Mixed and Single Layered Checks:

The mixed and single layered checks is designed for finding potential manufacturing defects and generation of statistics in mixed and single layers. The action is dedicated for single layers, however it can also be implemented on mixed and other layers. The main checklist are given below.

3. The Ground/Power Checks:

The intentions of the ground/power checks is to have an identification of the manufacturing defects in ground and power in mixed layers. It has utilization of various algorithms for diagnosis of positive and negative power along with ground layer. Checklist is given as follow.

4. The Solder Mask Checks:

This function is for checking layers of solder masks for any potential manufacturing defects. The layers of solder masks are considered negative and the positive features are describing clearance of the solder masks. The function is also checking the solder paste which is deposited on the pads. This function is operating on single layer solder mask and below is its major checklist.

5. The Silkscreen Checks:

This function has an intention of finding potential manufacturing defects present in layers of silkscreen and also generation of statistics. This function is only used for checking silk screen layers because it has a reliance on job matrix related to external copper, layers of drills and solder mask. Below are details of checklist.

You can avail advantage of DFM free check offered by RayPCB right away. Don’t waste time and contact us right now for availing this amazing deal of free DFM check.

More PCB Design guides :

• PCB Loyout Rules
• PCB Design Tips
• PCB To Schematic

Introduction

Printed circuit board (PCB) design requires specialized software tools to lay out connectivity and translate circuit schematics into physical board fabrication. Many solutions are available for PCB designers. This article outlines the top 8 PCB design software options based on popularity and capabilities.

Overview of PCB Design Software

PCB design software provides features such as:

• Schematic capture – draw circuit diagrams
• Board layout – arrange components and routing
• Autorouting – automated trace routing
• Design rule checks – validate manufacturability
• 3D modeling – visualize board and enclosure
• Analysis tools – signal, thermal, power integrity
• Library management – component footprints
• Manufacturing outputs – Gerber, drill files, BOM

Choosing software with capabilities matching the application requirements and designer skills ensures efficient and successful development.

Top 8 PCB Design Software

Here are the most widely used PCB design software tools for professional engineers:

1. Altium Designer

Altium Designer is one of the most fully featured and commonly used PCB design solutions. Key features:

• Unified environment for schematic and PCB design
• Sophisticated routing with timing-aware topology
• Extensive component database and 3D modeling
• Scripting and programming for automation
• Variants and version control
• Manufacturing-ready outputs and documentation

Altium provides advanced capabilities for high-speed, high-complexity board design. But it also has a significant learning curve.

2. Cadence Allegro

Allegro from Cadence is another leading professional PCB design suite. It includes:

• Full schematic and layout environment
• Constraint-driven routing and editing
• Integrated cross-probing between schematic and PCB
• RF design features
• Analysis tools for signal and power integrity
• PCB librarian for footprint management
• Back annotation and ECO changes

Allegro excels at large team-based designs but also has a steep learning curve.

3. Mentor Graphics Xpedition

Xpedition from Mentor Graphics (now Siemens) offers complete front-to-back PCB design:

• Unified schematic, layout, routing flow
• DFM design rule checks and visualization
• Automated routing with manufacturability awareness
• Multi-channel length matching
• Integrated thermal analysis
• Design data management and workflow

Xpedition balances powerful performance with reasonable ease of use.

4. CadSoft Eagle

Eagle from CadSoft (Autodesk) is very popular for smaller design teams and prototyping:

• More affordable cost
• Available in free version with limited capability
• Easy to learn and intuitive UX
• Large component library
• Routing autorouter included
• Good for open-source community designs

Eagle is ideal for smaller boards but has limitations in advanced functionality.

5. KiCad

KiCad is a capable open-source PCB design tool suitable for many applications. Benefits include:

• Free and community supported
• Good feature set for the price
• Flexible customization and extensibility
• Part library spanning many footprints
• Capable PCB editor and visualization

KiCad lacks some polish and documentation compared to commercial tools but is under active development.

6. OrCAD

From Cadence, OrCAD provides a more affordable PCB design solution:

• Lower cost than Cadence Allegro
• Easy-to-use schematic capture
• Integrated library tools with thousands of parts
• Blind and buried via support
• Revision control and annotation
• rulers provide manufacturing dimension feedback

OrCAD delivers a solid schematic/layout tool for a reasonable price point.

7. Pads from Mentor Graphics

For entry-level users, Mentor Graphics offers Pads for layout and routing. Benefits:

• Affordable for individual engineers
• Straightforward layout tools
• Drag and drop placement
• Includes autorouter
• Validation against design rules
• Simple cloud-based license

Pads provides an easy to adopt design environment without advanced features.

8. Zuken CR-8000

The CR-8000 from Zuken targets high-speed signal integrity applications:

• Focus on signal and power integrity
• Timing-driven routing optimization
• Extensive analysis features
• Multi-board system connectivity
• Manufacturability-aware design rule checks
• Parametric part creation

The CR-8000 excels at SI-centric and constraint-driven PCB development.

Comparing Top PCB Design Software

Selecting among these top options depends on specific project needs and team experience.

Important PCB Software Considerations

Beyond core schematic and layout capabilities, key considerations when choosing PCB design software include:

Cost – How the pricing fits within your budget. Perpetual license, subscription, free?

Learning curve – Match software complexity with team experience level.

EDA environment – Integration with other tools like simulation for a unified workflow.

Libraries – Availability of extensive component libraries frees designers from creating footprints.

Scalability – The ability to handle everything from DIY to enterprise-level designs.

Output generation – Does it support manufacturing requirements like Gerber, IPC netlists, BOM?

Matching software strengths to the organization and application maximizes the benefit.

Integrated PCB Design Software Environments

Many EDA vendors offer integrated design environments spanning simulation, PCB layout, and physical verification:

Cadence Allegro + OrCAD + PSpice

• Tight integration for schematic-based simulation and PCB design
• Covers range from entry level to advanced tools

Mentor Xpedition + PADs + HyperLynx

• Unified PCB design workflow with analysis under one interface
• Scales individual to enterprise-wide needs

Altium + Altium Designer

• Single solution from schematic through manufacturing
• Additional tools for FPGA and embedded development

Using tools from one vendor improves design workflow and data exchange while providing a convenient single vendor support point. But beware of vendor lock-in limiting future options.

Cloud-Based PCB Design

Many EDA software companies now offer cloud-hosted options:

Benefits

• Reduced IT infrastructure needs
• Usage-based pricing model
• Automatic updates
• Access designs from anywhere

Limitations

• Requires reliable high-speed internet
• Potential for latency during editing
• Information security concerns
• Vendor dependent

Cloud-based tools facilitate collaboration but may not suit every design scenario.

Open Source PCB Design Software

In addition to KiCad, open source PCB design software options include:

• gEDA – Full suite of EDA tools focused on open collaboration
• HorizonEDA – Web-based schematic and layout tool
• PCBWeb – Browser-based editor for simple boards
• Fritzing – Emphasis on DIY and maker community

Open source provides free access but typically lacks vendor support and advanced capabilities. The open approach facilitates customization and community development.

Evaluating PCB Design Software

When selecting a PCB design solution:

• Review product brochures and feature lists
• Compare pricing tiers and availability of educational licenses
• Join online user forums to research experiences
• Download trial versions to experiment firsthand
• Seek feedback from colleagues
• Contact vendor sales teams

Taking time to thoroughly evaluate software against requirements ensures the optimal choice long-term.

Training Resources

Extensive training resources are available for most leading PCB software:

• Built-in tutorials – Interactive step-by-step guidance
• Videos – Recorded demonstrations of workflows
• Webinars – Live deep dives into capabilities
• Documentation – Manuals and help files
• Forums/FAQs – Q&A databases
• Training courses – Formal virtual or on-site classes

Leverage training to ramp designers up effectively on chosen solutions.

PCB Software Trends

Emerging trends shaping PCB design software include:

• Increasing automation – More tasks automated by optimization algorithms like routing. Reduces manual work.
• Simulation integration – Tighter coupling with analysis tools like thermal and SI.
• Virtual prototyping – Interactive 3D visualization replacing physical prototyping.
• Cloud adoption – Web-based tools facilitating collaboration.
• Artificial intelligence – Limited use of AI for tasks like design rule checking.
• User experience – Simplification and intuitive interactions.

Software will continue adapting to leverage new technologies while serving designer needs.

Summary

Key takeaways on PCB design software:

• Many capable software options exist from open source to advanced commercial tools
• Match software capabilities with organization size, experience level, and application complexity
• Leading solutions include Altium, Cadence, Mentor, Eagle, KiCad, Zuken
• Integrated environments improve workflow and collaboration
• Cloud-based access aids collaboration while introducing potential risks
• Open source provides free access with community-driven development
• Thoroughly evaluate options against needs and leverage training resources

Choosing the optimal software maximizes the efficiency, capabilities, and ease-of-use for any PCB development effort.

Frequently Asked Questions

What is most important when comparing PCB software?

The core layout and routing capabilities are essential, but also consider learning curve, integration, output generation, and other productivity factors.

Which is better – perpetual license or subscription model?

Subscriptions allow flexible scaling and updating but require ongoing payments. Perpetual licenses require large upfront costs and additional purchases for upgrades. Evaluate total long term cost.

Is cloud-based PCB software more efficient for teams?

Cloud tools facilitate real-time collaboration, but designers must be comfortable with cloud security policies and inevitable internet dependencies.

Should I use the built-in autorouter?

Built-in autorouters provide a starting point but generally can’t match the quality of manual routing for complex designs. Use judiciously.

Can students or hobbyists access professional tools cost-effectively?

Many leading vendors offer free or discounted educational licenses, sometimes limited in capabilities. Student versions can provide advanced tools for learning prior to entering industry.

Introduction

When designing printed circuit boards (PCBs), the width and thickness of copper traces impact how much current they can safely carry without overheating. Traces must be appropriately sized based on expected current levels. Copper weight, trace width, and current capacity have a direct mathematical relationship. This article provides an in-depth examination of these parameters and their correlation in PCB design.

Copper Weight

Copper weight refers to the thickness of the copper foil used to form PCB traces, pads, and planes. The most common weights are:

• 1 oz – 1 ounce per square foot, equivalent to a thickness of 1.4 mils (34 μm)
• 2 oz – 2 ounce per square foot, equivalent to 2.8 mils (68 μm)

Heavier copper foil allows for higher current capacity. But it costs more and can complicate fine-pitch PCB fabrication.

Trace Width

Trace width is the manufactured width of a PCB track, typically measured in mils (1 mil = 0.001 inches). Wider traces can handle more current due to reduced resistance. Minimum widths are dictated by current levels.

Current Carrying Capacity

The current carrying capacity defines how much continuous DC or RMS AC current a trace can conduct without exceeding temperature limits, usually 10-30°C above ambient. Excess current causes overheating damage.

Factors Affecting Current Capacity

Current capacity depends on:

• Copper weight – Heavier copper has lower resistance
• Trace width – Wider traces have lower resistance
• Temperature rise – Allowable increase over ambient
• Environment – Operating temperature influences limits
• Heat sinking – Thermal dissipation enables higher current

Appropriately sizing traces for expected currents prevents overheating while minimizing unnecessary PCB space and cost.

Copper Weight and Resistance

The primary factor relating copper weight to current capacity is the change in electrical resistance:

• Heavier copper has lower resistance
• Lower resistance results in less heating from a given current
• Reduced heating allows higher current capacity

For example, the table below shows typical per-length resistances relative to common copper weights:

The resistance drops as copper weight increases, enabling higher current capacity.

Calculating Resistance from Weight

The resistance through a length of conductor is calculated using:

Where:

• ρ is the resistivity of copper (1.678 x 10^-8 Ωm)
• L is the length (m)
• A is the cross-sectional area (m²)

For a rectangular PCB trace, the cross-sectional area is:

Where:

• W is trace width (m)
• T is copper thickness (m)

Combining the equations allows resistance calculation based on trace dimensions and copper weight.

Trace Resistance Example

For a 50 mm long, 0.5 mm wide trace in 1 oz (34 μm) foil:

Increasing to 2 oz (68 μm) thickness halves the resistance:

Heavier copper foil significantly reduces electrical resistance due to the larger cross-sectional area.

Lower Resistance Increases Current

The power dissipated as heat in a conductor is:

Where I is the current and R is the resistance.

For a given temperature rise, higher current is possible with lower resistance before reaching power dissipation limits. The reduced resistance of thicker copper enables higher current capacity.

Trace Width and Resistance

In addition to copper weight, trace width also impacts resistance:

• Wider traces have a larger cross-sectional area
• Larger area produces lower resistance
• Lower resistance allows higher current capacity

For example, a 100 mm long trace with 0.25 mm width has 4X the resistance of a 0.5 mm wide trace in the same 1 oz copper:

Wider traces reduce resistance and enable increased current carrying capacity.

Combining Weight and Width

The effects of copper weight and trace width are multiplicative. For example, the combination of:

• Doubling copper weight from 1 oz to 2 oz (halves resistance)
• Doubling trace width from 0.25 mm to 0.5 mm (halves resistance again)

Decreases resistance to 1/4 of the original, increasing current capacity by a factor of 4X.

Optimizing both copper weight and trace width provides the maximum current capacity for a given PCB area.

Trace Temperature Rise

While lower resistance allows more current, we must also consider the resulting temperature rise. Power dissipated as heat raises trace temperature:

Where:

• ΔT is temperature rise
• P is power dissipation
• Rθ is thermal resistance

Rθ depends on trace size, environment, and heat sinking. Allowable ΔT determines current capacity.

Calculating Current Capacity

An analysis combining electrical and thermal considerations calculates current capacity:

• Start with fixed constraints:
  • Target temperature rise ΔT
  • Ambient temperature Tambient
  • Max allowable temperature Tmax
• Determine acceptable power dissipation:
  • P = ΔT / Rθ
  • Use Rθ for given construction
• Use Ohm’s law to find current at target power:
  • I = (P / R)**0.5
• Resulting I is the current capacity for the constraints

More thorough calculations maximize accuracy but often use assumed standard conditions for simplicity.

IPC-2152 Current Capacity Tables

IPC-2152 provides current capacity tables based on:

• Copper weight
• Trace width
• Assumed temperature rise and conditions

The tables relate width and weight to maximum current for common PCB parameters. An excerpt is shown below:

This simplifies current capacity estimates based on standard assumptions.

Current Density Rule of Thumb

For approximating current capacity, a general rule of thumb is:

Maximum current (A) = Current density (A/mm2) x Cross-sectional area (mm2)

Where the current density is:

• 0.8 to 1 A/mm2 for external traces without heat sinking
• 1.8 to 2 A/mm2 for external traces with heat sinking
• 3 to 4 A/mm2 for internal plane layers

The cross-sectional area is calculated from trace width and copper thickness.

Heat Sinking Effects

Heat sinking to nearby plane layers enables narrower trace widths and higher current density, increasing capacity for a given area.

For example, with 2 oz copper:

• External trace, 0.5 mm wide -> 3.9 A capacity
• Internal trace, 0.25 mm wide -> 5 A capacity

The thinner internal trace matches the capacity of the thicker external trace by utilizing heat sinking.

Estimating Required Width

To estimate the trace width needed for a target current:

• Select an appropriate current density based on heat sinking
• Calculate the required cross-sectional area:
  • Area = Target current / Current density
• Use area and copper weight to get minimum width:
  • Width = Area / Copper thickness

Then verify capacity using IPC-2152 tables or more detailed analysis.

Trace Width Design Factors

• Match trace widths to expected currents
• Ensure high-current traces meet minimum width needs
• Use larger widths than required when possible
• Maximize heat sinking from ground planes
• Confirm key traces with thermal modeling
• Document assumptions and design rules used

Careful trace sizing optimizes cost, reliability, and PCB performance.

Case Study: USB 3.0 Cable

As a case study, we can examine PCB trace sizes for a USB 3.0 cable.

Key parameters:

• 5V supply current: 0.9 A
• Data pairs carry 1.0 A per pair, 8 pairs total = 8 A
• Target ΔT = 20°C ambient, 60°C max temperature
• 1 oz external traces with ground plane heat sinking

Using IPC-2152:

• 5V trace: 0.25 mm width
• Data traces: 0.5 mm width

This case study illustrates appropriate trace sizing for standard USB currents.

Summary

• Heavier copper weight reduces electrical resistance
• Lower resistance allows increased current capacity
• Wider traces also decrease resistance due to larger area
• Trace width must be sized based on target current
• IPC-2152 tables relate width and weight to current capacity
• Heat sinking improves capacity for a given trace size
• Matching trace size to current prevents overheating damage

Correctly correlating copper weight, trace width, and current carrying capacity ensures safe and reliable PCB performance under expected current loads.

Frequently Asked Questions

How accurate must current capacity calculations be?

Rough estimations are often sufficient early in design to determine minimum widths. More detailed analysis may be warranted for high-power or long-life applications.

What copper weight should be used?

1 oz copper offers the best balance of cost, manufacturability, and performance for most applications. 2 oz provides higher capacity for high-power boards.

Is it always better to use thicker copper?

Not always – thicker copper increases material and fabrication costs. Use the minimum weight that satisfies capacity needs. Excessive thickness can also lead to thermal stresses.

How much margin should be added to current capacity?

A 10-20% margin above calculated capacity is recommended to account for analysis inaccuracies and environmental variations during operation.

Can vias decrease current capacity?

Yes, narrower vias can create bottlenecks increasing resistance and heating. Size vias at least as wide as connected traces to prevent reductions in capacity.

A PCB trace width is simply a parameter defining the distance covered across a circuit board’s trace.  Some other well-known parameters here include trace thickness and spacing. Four major factors influence the PCB trace width. These include:

• The desired length of the trace
• The spacing required between these traces
• The size of the board’s conductive layer
• The capacity of the trace necessary to carry current

PCB Trace Width Calculator: What does this mean?

No matter the type of industry you work in, every day you may use a printed circuit board. These devices are very important to how electronics function. Also, they connect and offer mechanical support to electrical components. This is to ensure that they operate properly.

When utilizing Printed Circuit Boards to sustain computers, lighting technology, or medical equipment, they must operate with the right trace width. Using a circuit calculator, you will be sure of the safety of your printed circuit board. They will also stay functional all the time.

The use of the IPC-2221 standard is the major factor in the derivation of a PCB trace width calculator. This standard helps in calculating the conductive track width of a printed circuit board (PCB). It is advisable that you design the PCB traces in order to bear the highest current load even before they start malfunctioning.

The determination of the copper width calculation, at a specific thickness, is necessary. This helps in allowing the transfer or movement of a particular current value. In addition, the copper thickness and width need to be enough to help maintain the rise in temperature at levels below the input.

How to get Trace Width Making Use of a PCB Trace Width Calculator

This calculator needs the imputation of some values to know the trace’s desired width. The representation of this width is in mils & deals with the utilization of some values. These include:

• The conductive layer’s area, which is usually in mils square
• The trace’s thickness, which is in ounces/sq ft

What differentiates the External vs. Internal PCB Trace Width Calculators?

Internal PCB trace width calculators are tools that determine the required width of an internal trace. The determination of this internal trace width is to help carry a specific current amount.

External PCB trace width calculators are similar tools, which tell an external trace’s width. The result of the trace width also, is useful for the transfer of the current of a particular amount.

Consequently, the difference seen between the external and internal traces has to do with their location. This location relates to the substrate of the board.

Also read about SMT Engineer

Why is Using a PCB Trace Width Calculator Important?

During the production of PCBs, you will discover that the limitations of current-carry are a major constraint.

You may trace a PCB successfully and then later discover that it will not be able to carry the needed amount of current effectively. Consequently, the printed circuit board’s intended application experiences a setback. This is due to the inadequate current capacity.

Making use of your PCB trace width calculator ensures the conductance of the right current value. Using this circuit calculator, you may utilize the highest current rating you desire to know the width of your trace.

In addition, you may influence the rise in temperature which your PCB records. This is possible by making use of your PCB trace width calculator.

More Facts about the PCB Trace Width Calculator

Engineers often utilize the PCB trace width calculator in the fabrication process of a PCB. This tool helps to detect a lot of things in a circuit board. Before fabricating a PCB, you need to understand how the element works. Other important things you need to know about this tool are discussed here.

It is very important you detect the conductive layer’s area. You can use some constant values to determine this area. The IPC-2221 can help you to derive the constant values which are b, k, and c. These values vary depending on the location of the trace. The location of the trace can either be internal or external. The values of these constants are requirements for conductive material.

Detecting the temperature of the trace helps to know your PCB’s thermal performance. This plays a significant role in knowing the important properties of a PCB. You can sum the highest desired increase in the temperature.  This will help you to get the overall temperature trace. The values of the temperature are in °C.

The PCB trace width calculator has a mil. This mil plays a vital role. In the PCB world, mil is a terminology. It is frequently used when talking about the thickness of the circuit board layer. For instance, you can express copper thickness in ounces and as well as convert it to mils.

You don’t need the trace width to determine dissipated power and the voltage decrease. However, you need to understand the resistance value and the value of maximum current. This will help to tell or reveal the loss of power and voltage drop.

Use the overall resistance value and the maximum current value to get voltage drop. Multiply the maximum current value’s square and the value of resistance to get the power loss. All of these things should be taken into consideration.  This will help calculate the voltage drop and the dissipated power.

What Does It Mean To Experience a Rise In Temperature When Calculating The PCB Trace Width?

When there is a flow of current via a conductive trace, there is a generation of heat. This is a result of the resistance it gives to the conductor’s flow of current.

The increase in temperature defines the generation of heat. We refer to this as the rise in temperature. Also, you may determine how much rise in temperature your PCB will be able to sustain. This is possible by making use of a PCB trace width calculator.

When you provide PCB trace widths that are wider, you will be able to reduce the buildup of heat. This then results in a rise in temperature.

For many printed circuit boards, a temperature rise of 10 degrees is safe. Otherwise, you can fabricate boards to withstand a higher value in temperature rise. Also, you will find the application’s environment. This will help influence the board’s overall temperature.

Can You Extract Other Measurements By Using the PCB Trace Width Calculator?

PCB trace width calculators allow you to be able to establish different PCB measures. You can include additional input parameters. These include the trace’s length and the temperature for operation. This helps to extract additional measurements. Due to this, you can determine the measures below.

• The power dissipated along the trace
• A drop in voltage across the pcb trace
• The trace’s resistance value
• The trace’s rise in temperature

Can Board Spokes Be Subject to Trace Width Calculation?

Now PCB wagon wheels or spokes are features of the board design. These features help in simplifying the process of soldering for any ground plane.

They look like traces. However, they have a short length and are usually inserted inside the plane. Whenever you are making use of a trace width calculator, people hardly consider the spoke. This is because not all printed circuit boards have them.

It is however compulsory to ensure that spokes have a reduced width compared to actual traces. This is done without basing it on calculations.

Can we regard the Cross sectional Area of the Conductive Layer as an Important Parameter in Calculating a PCB Trace Width?

Yes, this is a very important parameter. The conductive layer’s cross sectional area is a very significant input when ascertaining the PCB trace width calculator.

This area in question is given in mils squared. This area is useful as the numerator for the calculation of the division of the trace width.

 Determining the conductive layer’s cross sectional area requires some parameters. These parameters are highlighted below.

• The maximum rise in temperature permitted which is in °C
• Three constants c, b, and k are different when there are external or internal traces.
• The maximum current permitted which is calculated in Amperes

Can the PCB Trace Width Calculator Detect the Trace Resistance?

To get your trace’s resistance value, you can make use of a PCB trace width calculator. PCB engineers have to calculate the trace width to know the value of resistance. The below parameters is needed for the trace width:

• The trace length in centimeters
• The overall or total temperature of trace
• The trace thickness measured in ounces/ sq ft
• The conductive layer’s cross sectional area
• The conductive material’s resistivity value

Calculating the current-carrying capacity

Calculating the current of the trace width of a PCB is very important. You can achieve this by using different methods. There is a method that utilizes a circuit calculator that determines the current of a PCB trace.  Another method utilizes the PCB width calculator.

It is very important to detect the current carrying capacity of the board.  You need it when you have to evaluate the application limit of the board.  Knowing the current limitations of the PCB trace width is important. It will help you to prevent exposing the circuit boards to possible damaging use.

What Determines Maximum Current-carrying Capacity?

The cross sectional area of the trace often determines the current carrying capacity. The temperature rise is also important. The trace’s cross sectional area is directly proportional to the copper thickness. The same goes for the trace width.

To get the maximum carrying capacity, you need a simple formula. Some practical cases are not easy to calculate. This is due to the rise in temperature and cross sectional area. Other things also determine the current carrying capacity of the trace.  These things may include vias, components, and pads.

Traces that have many pads will function more than ordinary traces. Engineers place circuit boards on some trace between pads. This happens when there is abundant solder paste on pins or components. When this occurs, it results in an increased cross sectional area. Increasing the trace width provides a solution to this problem.

When you can’t widen a trace, you can apply a solder mask on traces. The surface Mount Technology procedure needs solder paste. Trace width will increase after reflow soldering. This will help the current carrying-capacity to also rise.

One can get the trace current carrying capacity of a PCB using a formula. This application is ideal for straightforward trace calculation. It is important to consider contaminant pollution in the fabrication of a PCB. Pollution can result in the breaking down of some traces. There must be a security factor to prevent the issue of overloading.

Engineers also need to pay special attention to turning traces. If there is an acute angle in a trace, there will be a non-smooth transfer. This can have an effect on small traces or current with a large width. However, when the current-carrying capacity is low, there might be issues.

What is the difference between external and internal trace widths?

People wonder how to differentiate between the external and internal traces. You can know the differences through their location. Internal traces are PCB’s inner layers while external traces are on the outer surfaces of the PCB.

You will realize that the internal traces are greater than the external traces. It is vital you note that the parameters ‘values for both internal and external traces may vary. These parameters are the conductive material’s constant values and cross sectional area.

With time, you will notice that this is due to the various thermal requirements and construction differences. The major function of this PCB trace width calculator is taking control of the rise in temperature.  When you expose external traces, they allow heat to discharge partly via convection.

Layers that are not conductive cover internal layers which lead to the accumulation of heat. To increase heat dispersion’s surface area, the internal traces have to be bigger.

Are there other ways to detect the amount of current a PCB can carry?

There is no doubt that the PCB trace width calculator helps to detect the current capacity a trace can take. However, you need to understand some features of the board. These things can help to add more to the carrying capacity of the trace.

For example, the vias system and the pads can affect the amount of current that can move via a trace. In a PCB, conductive vias provide alternative ways for the flow of current. This allows the production of narrower traces.

Due to this, there can be a huge circuit density that boosts the performance capabilities of the board. Another factor that can cause current flow of trace is the amount of attached parts onboard. You will realize that some electronic components feature great power demands. These components come with exceptional thermal dissipations.

With this explanation, one can easily say that a PCB trace width calculator is very important. In the fabrication of a printed circuit board, engineers need this tool. It is a very important tool that cannot be overlooked in the PCB industry. It has got a lot of benefits and has also made the fabrication of PCB an easy process. PCB manufacturers are very much familiar with the PCB trace width calculator.

Formulas Associated with PCB Trace Width Calculator

For a PCB trace width calculator, you have to understand some basic formulas. These formulas will help understand your calculator better.

Trace Temperature

This is an important element that helps you get your trace width. You can calculate the trace temperature by summing T RISE and T AMB. You only need three total parameters to calculate trace temperature.

• T TEMP is Trace temperature
• The T AMB is ambient temperature
• T RISE is the maximum rise of the desired temperature

Power Dissipation Calculator

When an electronic device produces heat then there is power dissipation. This can lead to loss or waste of energy. To get the power dissipation, you need the maximum current and resistance value. Therefore, P Loss= R * I²

• Power loss = P Loss
• Resistance = R
• Maximum current = I

The maximum current uses ohms for its measurement while resistance uses watts.

Max Current

To get the maximum current, use A= (T X W X 1.378 [mils/oz/ ft²)

• [Mils2] is the trace thickness
• A is the cross section area
• [oz/ft2] W is the width of the trace

After solving this equation you can now detect the maximum current. Use this IMAX = A^c x (k x T RISE^b) to achieve this.

The parameters mean

• Maximum current= [mils] I_MAX 
• Maximum rise of desired temperature= [A] TRISE
• Constants =b, k, and c

Voltage Drop Calculation

When calculating the voltage drop of a PCB, you need trace resistance and maximum current. The voltage drop measures the reduction of electrical potential in an electrical circuit.

Voltage drop= Maximum current * trace resistance.

Resistance Calculation

You will have to convert the cross-section area when you want to calculate the PCB’s trace resistance. Resistance= (1 + a * (T TEMP – 25 degree Celsius) (p * L / A).

• Trace thickness= T
• The trace temperature = [1/ °C] T TEMP
• Trace width= [oz/ft2]
• Resistivity temperature coefficient =[cm] α
• Trace resistance= [mils] R
• Trace length= [Ω · cm] L

Frequently Asked Questions

It could be a difficult and confusing process when you are calculating the trace width. This holds especially for those new to using a trace width calculator. Some questions have been bothering you with respect to this calculator. It may be with the results or formula, and you may find an answer to them here.

Is there a limit to the current that this calculator can use in calculating the width? Of course, this has to do with whichever formula you are using. This tool can calculate trace width of about 35 amps, 400 mils, and copper falling within 0.5 – 3 ounces /sq ft and an increase in temperature falling in the range of 10 to 100 degrees Celsius. This calculator extrapolates the data anytime you use it outside any of these ranges.

What is the mils unit of measurement? The word “Mil” is from a Latin term called “mille,” which means “thousand.”  One mil is an inch divided into a thousand places.

Why is it that the calculator reveals the width of the internal trace higher than that of the external trace? High heat transfer is usually associated with external trace layers. Internal layers, on the other hand, don’t also conduct heat. This means that internal traces will be able to store more heat.

In this context, what do we mean by temperature rise? A rise in temperature has to do with the difference between the maximum operating temperature of your PCB regarded as safe, and its normal operating temperature.

While using this calculator, I put in a current requirement of 65 amps, and it brought back an incorrect track width. So what are its limits? This tool works with an original graph that only covers about 35 amps. It also works with a trace width of 0.4 inches. Also, it only deals with a rise in temperature from 10 – 100 degrees centigrade. Lastly, it works with a copper of about 0.5 – 3 ounces for every square foot. Anything outside these ranges will lead to an extrapolation of these formulas.

Conclusion

As already mentioned, printed circuit boards serve as backbones for many electronic products. By now, we hope you have been enlightened on why you need to establish the trace width of your printed circuit board. This helps to prevent and safeguard it from any destruction. When you establish the trace width, you will be able to know the amount of current. Lastly, make sure you abide by all the standards set. These help in creating a good PCB.

Trace width of a Printed Circuit Board (PCB) is a basic yet very crucial parameter which needs to be defined while designing a PCB. Calculation of trace width is important for both power and signal boards. This parameter defines the current carrying capacity of a PCB. Before going into the details of trace width, it is important to look at the factors which limit the flow of current through a conductor.  Any conductor with a specific (cross sectional) area ‘A’ carrying the electrical current ‘I’ offers an electrical resistance of ‘R’ towards the flow of current. The electrical resistance results in the loss of electrical energy into the heat dissipation which depends on the square of the current flowing through the conductor (hence these losses are known as I²R losses). With the rising current, the heat dissipation also increases and beyond a certain point excessive heat results in failure of the current carrying conductor. To reduce the heat dissipation (I²R losses) in the conductor the resistance needs to be decreased. Electrical resistance of a conductor is inversely proportional to the area ‘A’ and directly proportional to the length ‘L’ of the conductor.

‘ρ’ is the electrical resistivity of the conductor material under consideration. For copper, the resistivity is 1.7×10^-8 (ohm-m). If the length needs to remain constant, area can be increased to reduce the electrical resistance. Or in other words, increasing the area of the conductor increases its current carrying capacity (by reducing the heat losses or I²R losses).

This methodology of increasing current carrying capacity through increase in area now can be extended towards PCBs as well. ‘Traces’ on a PCB (sometimes also referred to as tracks) are the copper electrical connections responsible for carrying the electrical current. Due to the two-dimensional nature of a PCB circuit, the ‘width’ of traces is used to define the maximum amperage of a PCB board rather than the cross-sectional area (as height becomes a constant after choosing a thickness of copper). The formula for calculating the trace width is derived from following mathematical expression below (published in IPC-2221 standard):

Where,

I= Maximum current (A)

dT= increase in temperature above ambient (°C)

A= cross-sectional area (mils²)

‘k’ is constant which depend on the position of traces on the board

k (for internal traces) = 0.024

k (for external traces) = 0.048

Reason for different values of k is that the traces on the outer side of the PCB have a better chance of heat dissipation through the process of convection as compared to the internal layers. As a result of that, heat starts to accumulate on the internal layers. Higher value of ‘k’ for the internal layer means wider trace width which helps dissipate the accumulated heat. However, if the circuit is placed inside complete vacuum, the outer layers cannot lose heat through the process of convection. So, while designing PCBs in a vacuum, same value of ‘k’ needs to be chosen for internal and external layers i.e. 0.024.

The exponents of ‘dT’ and ‘A’ are a result of physical constants of copper such as resistivity of copper and temperature coefficient of copper. Area of trace (mil²) can be calculated by rearranging (2) as shown below:

With a chosen thickness ‘T’ (mils), the trace width ‘w’ (mils) can be calculated:

Figure below depicts the (for a contact thickness of 1oz or 35 um) current capacity against the calculated trace width for different changes in temperature from ambient.

Although the formula in the equation (4) does not have a mathematical limit, its accuracy keeps decreasing with higher values of current and trace width. For values of current higher than 35 A for outer traces 17.5A for internal traces or trace width higher than 400 mil, this formula will result in significant error value. Additionally, the mathematical formula to calculate the trace width does not keep into account some other factors such as count of electronic components, vias and pads in the circuit.  And finally, factors like dust are also taken into account in large scale production of PCBs. This mathematical formula also assumes that the components do not cause any hindrance in heat dissipation. That’s why an additional buffer is added to the calculated value to avoid complexities arising from external factors.

It is also important to maintain proper spacing between the traces to avoid any transient short circuit condition in power circuit boards or signal interference in signal boards. A general rule is to maintain spacing between two parallel running traces which is three times the trace width. Location of power, ground and signal traces on the board is also important. It is recommended to strategically place the power traces and not have the power traces go from one component to the other in a complex daisy chain configuration. In nutshell, calculation of proper trace width according to the expected current requirements of your board is an important step for the continuous operation of a PCB within safe operating temperature range.