PCB Heat Transfer: Comprehensive Analysis and Solutions

 

Introduction to PCB Heat Transfer

Heat transfer in Printed Circuit Boards (PCBs) represents one of the most critical challenges in modern electronics design. As electronic devices continue to shrink in size while simultaneously increasing in processing power and functionality, the heat generated per unit area has dramatically increased. This fundamental thermal management challenge affects everything from consumer electronics to aerospace applications, making heat transfer understanding essential for engineers and designers across industries.

The efficient dissipation of heat in PCBs directly impacts product reliability, performance, and lifespan. Components operating at elevated temperatures experience accelerated degradation, while thermal cycling can lead to mechanical stresses that cause premature failures. Modern high-density PCBs with powerful processors, memory modules, and power components face particularly intense thermal management challenges that require sophisticated solutions based on solid heat transfer principles.

This article provides a comprehensive exploration of heat transfer mechanisms in PCBs, examining theoretical foundations, practical applications, and cutting-edge solutions. We'll investigate conduction, convection, and radiation as they apply specifically to PCB design, and explore both passive and active thermal management techniques. Additionally, we'll analyze how thermal considerations impact material selection, component placement, and overall PCB architecture.

Fundamentals of Heat Transfer Physics

Basic Heat Transfer Mechanisms

Heat transfer in PCBs occurs through three fundamental mechanisms: conduction, convection, and radiation. Understanding these mechanisms forms the foundation for effective thermal management strategies.

Conduction

Conduction represents the primary mode of heat transfer within PCB materials. It occurs through molecular vibrations and free electron movement without any bulk motion of the material. In PCBs, conduction follows Fourier's Law:

$q = -k \cdot A \cdot \frac{dT}{dx}$

Where:

• $q$ is the heat transfer rate (W)
• $k$ is the thermal conductivity of the material (W/m·K)
• $A$ is the cross-sectional area perpendicular to heat flow (m²)
• $\frac{dT}{dx}$ is the temperature gradient (K/m)

The thermal conductivity ($k$) varies significantly across PCB materials:

Material
Thermal Conductivity (W/m·K)
Copper
385
FR-4
0.25-0.3
Aluminum
205
Thermal vias (filled)
15-80
Ceramic substrates
20-270
Polyimide
0.12-0.35
Silicon
148

These values highlight the significant disparity between conducting materials like copper and insulating materials like FR-4, which creates challenges for heat distribution across PCBs.

Convection

Convection involves heat transfer between a solid surface and a moving fluid (liquid or gas). In PCB applications, this typically involves air or liquid coolants. Convection is characterized by Newton's Law of Cooling:

$q = h \cdot A \cdot (T_s - T_\infty)$

Where:

• $q$ is the heat transfer rate (W)
• $h$ is the convective heat transfer coefficient (W/m²·K)
• $A$ is the surface area exposed to the fluid (m²)
• $T_s$ is the surface temperature (K)
• $T_\infty$ is the fluid temperature (K)

The convective heat transfer coefficient varies significantly based on fluid properties and flow conditions:

Cooling Method
Convective Heat Transfer Coefficient (W/m²·K)
Natural air convection
5-25
Forced air convection
25-250
Water cooling
500-10,000
Immersion cooling
100-1,000
Phase-change cooling
2,500-100,000

Radiation

Radiation transfers heat through electromagnetic waves without requiring a medium. While often less significant in PCB applications compared to conduction and convection, radiation becomes increasingly important at higher temperatures. The Stefan-Boltzmann Law governs radiative heat transfer:

$q = \varepsilon \cdot \sigma \cdot A \cdot (T_s^4 - T_{surr}^4)$

Where:

• $q$ is the heat transfer rate (W)
• $\varepsilon$ is the emissivity of the surface (dimensionless)
• $\sigma$ is the Stefan-Boltzmann constant (5.67 × 10⁻⁸ W/m²·K⁴)
• $A$ is the surface area (m²)
• $T_s$ is the surface temperature (K)
• $T_{surr}$ is the surrounding temperature (K)

Thermal Resistance Concept

Thermal resistance provides a crucial framework for understanding heat flow in PCBs, analogous to electrical resistance in circuit analysis. The basic formula is:

$R_{th} = \frac{\Delta T}{P}$

Where:

• $R_{th}$ is the thermal resistance (K/W)
• $\Delta T$ is the temperature difference (K)
• $P$ is the power or heat flow (W)

For conduction through a uniform material, thermal resistance can be calculated as:

$R_{th} = \frac{L}{k \cdot A}$

Where:

• $L$ is the material thickness (m)
• $k$ is the thermal conductivity (W/m·K)
• $A$ is the cross-sectional area (m²)

In PCB design, thermal resistances are often considered in series and parallel configurations:

Series thermal resistance: $R_{total} = R_1 + R_2 + R_3 + ... + R_n$

Parallel thermal resistance: $\frac{1}{R_{total}} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3} + ... + \frac{1}{R_n}$

Thermal Models and Junction Temperature

The junction temperature ($T_j$) of a component is a critical parameter that directly affects reliability and performance. It can be calculated using the thermal resistance model:

$T_j = T_a + P \cdot R_{th(j-a)}$

Where:

• $T_j$ is the junction temperature (°C)
• $T_a$ is the ambient temperature (°C)
• $P$ is the power dissipation (W)
• $R_{th(j-a)}$ is the junction-to-ambient thermal resistance (°C/W)

The junction-to-ambient thermal resistance can be broken down into several components:

$R_{th(j-a)} = R_{th(j-c)} + R_{th(c-s)} + R_{th(s-a)}$

Where:

• $R_{th(j-c)}$ is the junction-to-case thermal resistance
• $R_{th(c-s)}$ is the case-to-sink thermal resistance
• $R_{th(s-a)}$ is the sink-to-ambient thermal resistance

This model allows engineers to predict component temperatures and design appropriate thermal management solutions.

PCB Materials and Thermal Properties

Substrate Materials

The substrate forms the foundation of any PCB and significantly impacts its thermal characteristics. Common substrate materials include:

FR-4 (Flame Retardant-4)

The most widely used PCB substrate material, FR-4 consists of woven fiberglass cloth impregnated with epoxy resin. While cost-effective and offering good electrical insulation properties, FR-4 has relatively poor thermal conductivity (typically 0.25-0.3 W/m·K).

High-Tg FR-4

High glass transition temperature (Tg) variants of FR-4 can withstand higher temperatures before softening, with Tg values ranging from 170°C to 180°C compared to standard FR-4's 130°C to 140°C. While thermal conductivity remains similar, the higher Tg allows operation at elevated temperatures.

Ceramic Substrates

Ceramic substrates offer superior thermal conductivity compared to FR-4:

Ceramic Material
Thermal Conductivity (W/m·K)
Key Applications
Aluminum Nitride (AlN)
170-260
High-power LEDs, RF components
Aluminum Oxide (Al₂O₃)
20-30
Power electronics, automotive
Silicon Nitride (Si₃N₄)
80-120
High-temperature applications
Beryllium Oxide (BeO)
250-300
Military, aerospace (limited due to toxicity)

Metal Core PCBs (MCPCBs)

Metal core PCBs incorporate a metal base layer, typically aluminum or copper, offering significantly improved heat dissipation:

Metal Core Type
Thermal Conductivity (W/m·K)
Advantages
Aluminum core
1.0-3.0 (composite)
Cost-effective, lightweight
Copper core
2.0-5.0 (composite)
Higher thermal performance
Hybrid metal core
1.5-4.0 (composite)
Balanced performance/cost

Polyimide

Polyimide substrates offer excellent thermal stability and flexibility, with a thermal conductivity of 0.12-0.35 W/m·K. They maintain mechanical integrity at temperatures up to 260°C, making them suitable for high-temperature applications and flexible PCBs.

Conductor Materials

Copper

Copper remains the primary conductor material for PCBs, with an excellent thermal conductivity of approximately 385 W/m·K. Standard copper thicknesses in PCBs include:

Copper Weight
Thickness
Thermal Considerations
0.5 oz/ft²
17.5 μm
Limited thermal capacity
1 oz/ft²
35 μm
Standard for most applications
2 oz/ft²
70 μm
Improved thermal performance
3 oz/ft²
105 μm
Better for high-current designs
4 oz/ft²
140 μm
Enhanced thermal management

Heavier copper weights improve thermal dissipation but present manufacturing challenges including etching precision and impedance control.

Alternative Conductors

While less common, alternative conductor materials offer specific advantages:

Material
Thermal Conductivity (W/m·K)
Advantages
Silver
429
Higher conductivity than copper
Gold
318
Excellent corrosion resistance
Aluminum
205
Lightweight, cost-effective
Carbon nanotube composites
3,000-5,000
Emerging technology, extremely high thermal conductivity

Thermal Interface Materials (TIMs)

Thermal interface materials fill microscopic gaps between components and heat sinks, reducing thermal resistance:

TIM Type
Thermal Conductivity (W/m·K)
Applications
Thermal greases
0.4-10
CPU/GPU interfaces
Thermal pads
0.8-15
Component-to-heatsink interfaces
Phase change materials
0.7-5
High-performance computing
Thermal adhesives
0.5-7
Component attachment
Metal TIMs (solder, liquid metal)
20-80
High-performance applications
Carbon-based TIMs
5-25
Advanced electronic systems

Thermal Via Technology

Thermal vias create conductive paths through the PCB substrate, significantly enhancing heat transfer between layers:

Via Type
Thermal Conductivity (effective)
Characteristics
Non-filled vias
1-5 W/m·K
Air-filled, limited thermal performance
Plated vias
5-20 W/m·K
Copper plating on via walls
Filled vias (copper)
15-80 W/m·K
Superior thermal performance
Filled vias (thermal compound)
2-10 W/m·K
Cost-effective alternative

The effective thermal conductivity of a via array depends on:

• Via diameter (typically 0.2-0.8mm)
• Via pitch (center-to-center spacing)
• Plating thickness
• Fill material properties
• Via aspect ratio

Thermal Management Techniques in PCB Design

Passive Cooling Strategies

Passive cooling relies on natural physical processes without requiring additional power input, making these approaches reliable and energy-efficient.

Copper Spreading Planes

Copper planes distribute heat across a larger surface area, reducing thermal concentrations:

Design Parameter
Guideline
Impact
Copper weight
1-4 oz/ft²
Heavier copper provides better thermal performance
Plane connection
Direct to thermal pads
Minimizes thermal resistance
Thermal relief design
Modified or eliminated
Improves thermal conductivity
Plane fragmentation
Minimize splits
Maintains thermal spreading capability

Heat Sink Integration

Heat sinks increase surface area for improved convective heat transfer:

Heat Sink Type
Thermal Resistance Range (°C/W)
Application
Stamped heat sinks
3-15
Low-power components
Extruded aluminum
0.5-5
Medium-power applications
Skived heat sinks
0.3-2
High-performance computing
Die-cast
0.7-3
Complex geometries
Forged
0.2-1
High-performance applications

Heat sink performance factors include:

• Fin density (typically 8-25 fins per inch)
• Fin height (typically 5-50mm)
• Base thickness (typically 2-10mm)
• Surface treatment (anodized, painted, or bare)

Thermal Vias Implementation

Thermal via arrays enable vertical heat transfer through PCB layers:

Parameter
Typical Range
Design Considerations
Via diameter
0.2-0.8mm
Larger diameters reduce thermal resistance
Via pitch
0.5-2.0mm
Tighter pitch improves performance
Aspect ratio
1:1 to 10:1
Lower aspect ratios preferred for thermal vias
Via pattern
Grid, concentric
Pattern should match heat source geometry
Via fill
Air, solder, copper
Filled vias offer superior performance

For optimal thermal performance, the following formula can approximate the number of vias needed:

$N_{vias} ≈ \frac{P \cdot k_{substrate}}{ΔT_{max} \cdot d \cdot k_{via}}$

Where:

• $N_{vias}$ is the number of vias required
• $P$ is the power to be dissipated (W)
• $k_{substrate}$ is the substrate thermal conductivity (W/m·K)
• $ΔT_{max}$ is the maximum allowable temperature rise (K)
• $d$ is the via diameter (m)
• $k_{via}$ is the via thermal conductivity (W/m·K)

Component Placement Optimization

Strategic component placement significantly impacts thermal management:

Principle
Implementation
Benefit
Thermal decoupling
5-20mm spacing between high-power components
Prevents thermal coupling
Thermal grouping
Group components by operating temperature
Optimizes cooling solutions
Edge placement
Place high-power components near board edges
Improves convection cooling
Vertical stacking
Avoid placing heat-sensitive components above heat sources
Prevents thermal cascading
Air flow alignment
Align components in direction of air flow
Maximizes convective cooling

Active Cooling Techniques

Active cooling techniques use powered mechanisms to enhance heat removal from PCBs.

Forced Air Cooling

Forced air cooling uses fans or blowers to increase convective heat transfer:

Fan Specification
Range
Considerations
Airflow
5-200 CFM
Higher airflow improves cooling
Static pressure
0.5-5 mmH₂O
Higher pressure for dense components
Noise level
20-60 dBA
Lower noise preferred for consumer products
Size
25-200mm
Larger fans typically quieter
Power consumption
0.5-15W
Energy efficiency important for battery devices

The convective heat transfer coefficient increases with air velocity according to:

$h ≈ C \cdot V^{0.8}$

Where:

• $h$ is the convective heat transfer coefficient (W/m²·K)
• $C$ is a constant dependent on geometry
• $V$ is the air velocity (m/s)

Liquid Cooling Systems

Liquid cooling offers significantly higher heat transfer capabilities than air cooling:

Liquid Cooling Type
Heat Dissipation
Complexity
Cold plates
500-2,000 W
Medium
Microchannels
1,000-5,000 W
High
Jet impingement
2,000-10,000 W
High
Two-phase cooling
5,000-20,000 W
Very high

Common coolants include:

Coolant
Thermal Conductivity (W/m·K)
Specific Heat (J/kg·K)
Advantages
Water
0.6
4,180
Excellent thermal properties
Ethylene glycol mixtures
0.25-0.4
2,200-3,600
Lower freezing point
Dielectric fluids
0.06-0.15
1,000-1,500
Direct component contact
Nanofluids
0.2-2.0
2,000-4,000
Enhanced thermal performance

Thermoelectric Cooling

Thermoelectric coolers (TECs) use the Peltier effect to actively pump heat:

Parameter
Typical Range
Considerations
Power consumption
5-200W
Significant power requirement
Temperature differential
10-70°C
Maximum ΔT depends on heat load
Cooling capacity
10-250W
Decreases with increasing ΔT
COP (Coefficient of Performance)
0.2-0.6
Lower than conventional refrigeration

TECs are particularly useful for targeted cooling of specific components rather than entire PCBs.

Phase Change Cooling

Phase change cooling utilizes the latent heat of vaporization to achieve high heat transfer rates:

Technology
Thermal Performance
Implementation Complexity
Heat pipes
50-500 W
Low to medium
Vapor chambers
200-1,500 W
Medium
Immersion cooling
500-10,000 W
High
Two-phase cold plates
1,000-5,000 W
High

Heat pipes, for example, can have effective thermal conductivities of 5,000-200,000 W/m·K, far exceeding solid metals.

Thermal Analysis and Simulation

Computational Fluid Dynamics (CFD)

CFD simulation provides detailed analysis of heat transfer in PCBs by solving the governing equations for fluid flow and heat transfer:

Governing Equations

CFD solvers typically address the following equations:

1. Continuity equation (mass conservation): $\frac{\partial \rho}{\partial t} + \nabla \cdot (\rho \vec{V}) = 0$
2. Momentum equation (Navier-Stokes): $\rho \frac{D\vec{V}}{Dt} = -\nabla p + \nabla \cdot \tau + \rho \vec{g}$
3. Energy equation: $\rho c_p \frac{DT}{Dt} = \nabla \cdot (k \nabla T) + \Phi$

Where:

• $\rho$ is density
• $\vec{V}$ is velocity vector
• $p$ is pressure
• $\tau$ is stress tensor
• $\vec{g}$ is gravitational acceleration
• $c_p$ is specific heat
• $T$ is temperature
• $k$ is thermal conductivity
• $\Phi$ is viscous dissipation function

CFD Workflow for PCB Thermal Analysis

Step
Activities
Considerations
Geometry creation
Import PCB design, simplify complex geometries
Balance detail and computational cost
Meshing
Generate computational grid
Refinement in high-gradient regions
Material assignment
Define thermal properties for all components
Use manufacturer data when available
Boundary conditions
Define inlets, outlets, heat sources
Match actual operating conditions
Solution
Run simulation with appropriate solver settings
Check for convergence
Post-processing
Analyze temperature distribution, flow patterns
Identify hotspots and flow restrictions

Accuracy Considerations

CFD simulation accuracy depends on several factors:

Factor
Impact on Accuracy
Best Practice
Mesh resolution
Critical
Conduct mesh independence study
Turbulence modeling
Significant for forced air
Validate model selection
Radiation modeling
Important at high temperatures
Include for T > 85°C
Component power modeling
Directly affects results
Use actual power distributions
Material property accuracy
Moderate to high
Use temperature-dependent properties

Thermal Resistance Networks

Thermal resistance networks provide simplified yet powerful models for PCB thermal analysis:

Network Construction

A typical thermal resistance network for a PCB-mounted component includes:

Resistance Path
Typical Range (°C/W)
Definition
Junction-to-case (R_jc)
0.1-20
Within component package
Case-to-board (R_cb)
5-50
Interface between package and PCB
Board-to-ambient (R_ba)
10-100
From PCB to surrounding environment
Junction-to-ambient (R_ja)
R_jc + R_cb + R_ba
Total thermal path

The board-to-ambient resistance can be further broken down into:

$R_{ba} = \frac{1}{\frac{1}{R_{conduction}} + \frac{1}{R_{convection}} + \frac{1}{R_{radiation}}}$

Network Analysis Methods

Method
Complexity
Advantages
Hand calculations
Low
Quick estimates, design insights
Spreadsheet models
Medium
Parametric analysis capability
SPICE-like simulators
Medium-High
Transient analysis, component interactions
Specialized thermal tools
High
Detailed 3D analysis

Infrared Thermography

Infrared thermography provides actual temperature measurements of operating PCBs:

Parameter
Typical Range
Considerations
Temperature resolution
0.05-0.5°C
Higher resolution detects subtle variations
Spatial resolution
0.1-1mm
Depends on lens and detector array
Emissivity correction
0.1-1.0
Critical for accurate temperature readings
Measurement range
-20 to 1500°C
Select appropriate camera for application

Thermal imaging challenges for PCBs include:

Challenge
Solution
Varying emissivity
Apply uniform high-emissivity coating
Reflections
Control surrounding thermal environment
Component obscuration
Use angled views or multiple cameras
Transient effects
Synchronize imaging with operational states

Thermal Simulation Software

Modern thermal simulation tools provide specialized capabilities for PCB analysis:

Software Category
Examples
Specialization
General-purpose CFD
ANSYS Fluent, COMSOL
Detailed fluid and heat transfer
PCB-specific thermal
Mentor Graphics FloTHERM, Ansys Icepak
Electronics cooling focus
EDA-integrated
Cadence Celsius, Altium Thermal Modeler
Direct PCB design integration
Simplified tools
ThermalWorks, HeatCalc
Quick estimates, early design

Key features to consider include:

• Component library comprehensiveness
• PCB layer modeling capabilities
• Integration with EDA software
• Solution speed vs. accuracy trade-offs
• Post-processing and reporting tools

PCB Layout Considerations for Thermal Management

Component Placement Strategies

Strategic component placement forms the foundation of effective PCB thermal management:

Thermal Zoning

Dividing the PCB into thermal zones helps isolate heat-sensitive components:

Zone Type
Characteristics
Components
High-power zone
Maximum thermal management
Power converters, processors
Medium-power zone
Moderate heat generation
Memory, interfaces
Low-power zone
Minimal heat concerns
Sensors, low-power logic
Temperature-sensitive zone
Protected from heat sources
Precision components, oscillators

Critical Component Positioning

Component Type
Placement Recommendation
Rationale
High-power ICs
Board edges or corners
Maximizes cooling paths
Power converters
Near board edge, away from sensitive components
Access to cooling, EMI isolation
Clock generators
Away from thermal gradients
Prevents frequency drift
Sensors
Isolated from heat sources
Measurement accuracy
Memory
Away from highest heat zones
Reliability and performance

Vertical Considerations in Multi-layer PCBs

Layer Strategy
Thermal Impact
Implementation
Power/ground plane sandwiching
Improved heat spreading
Place components above/below plane pairs
Through-board thermal paths
Enhanced vertical heat transfer
Align thermal features across layers
Layer copper density balancing
Uniform thermal expansion
Maintain similar copper percentages
Thermal barrier layers
Heat flow control
Use low-k materials for isolation

Copper Pour and Thermal Relief Design

Copper pours significantly impact heat distribution in PCBs:

Copper Pour Guidelines

Aspect
Recommendation
Impact
Copper weight
1-4 oz/ft²
Heavier copper improves thermal performance
Pour connectivity
Minimize fragmentation
Continuous pours enhance thermal spreading
Pour size
Maximize around hot components
Larger area improves heat dissipation
Multi-layer coordination
Align pours vertically
Creates thermal columns through board

Thermal Relief Configurations

Thermal reliefs balance solderability with thermal performance:

Relief Type
Thermal Performance
Solderability
No relief (solid connection)
Excellent
Poor
Standard 4-spoke
Fair
Good
Wide 4-spoke
Good
Good
2-spoke
Good
Fair
Custom relief patterns
Varies
Varies

The thermal conductivity reduction from standard thermal reliefs is typically 40-60% compared to solid connections.

Critical Dimensions for Thermal Reliefs

Dimension
Typical Range
Thermal Impact
Spoke width
0.2-0.5mm
Wider spokes improve thermal performance
Number of spokes
2-8
More spokes reduce thermal resistance
Air gap width
0.2-0.4mm
Smaller gaps improve thermal performance
Connection overlap
0.1-0.3mm
Greater overlap enhances thermal transfer

Thermal Vias Implementation Strategies

Thermal vias significantly enhance vertical heat transfer through PCB substrates:

Via Patterns

Pattern
Application
Effectiveness
Grid array
General purpose
Good uniform distribution
Concentric
Centered heat sources
Excellent for package cooling
Linear
Heat spreading in one direction
Good for edge components
Gradient density
Non-uniform heat sources
Optimized for complex thermal profiles

Via Design Parameters

Parameter
Recommendation
Rationale
Via diameter
0.3-0.8mm
Balance between thermal performance and board space
Via pitch
1.0-2.0mm
Closer spacing improves thermal performance
Via plating thickness
25-50μm
Thicker plating reduces thermal resistance
Via fill
Copper or solder filled
Filled vias offer 2-4x better performance

Via Array Sizing

The total thermal conductance of a via array can be estimated by:

$G_{via-array} = N_{vias} \cdot \frac{\pi \cdot d^2}{4} \cdot \frac{k_{eff}}{L}$

Where:

• $G_{via-array}$ is the thermal conductance (W/K)
• $N_{vias}$ is the number of vias
• $d$ is the via diameter (m)
• $k_{eff}$ is the effective thermal conductivity (W/m·K)
• $L$ is the via length (m)

For typical FR-4 PCBs with thermal vias, this results in approximately 5-20 vias per cm² for moderate thermal applications, increasing to 50-100 vias per cm² for high-power applications.

Trace Routing for Thermal Management

While traces primarily serve electrical connections, they also impact thermal behavior:

Thermal Considerations for Trace Design

Trace Characteristic
Thermal Impact
Design Guideline
Width
Current carrying capacity, heat generation
Size for <10°C temperature rise
Copper weight
Heat dissipation capacity
Increase for high-current paths
Length
Total heat generation, voltage drop
Minimize for high-current paths
Layer placement
Heat dissipation path
Place high-current traces on outer layers
Proximity to components
Thermal coupling
Route high-current traces away from sensitive components

Current Capacity and Temperature Rise

The IPC-2152 standard provides guidelines for trace current capacity based on acceptable temperature rise:

Trace Width (mm)
Copper Thickness (oz)
Current for 10°C Rise (A)
Current for 20°C Rise (A)
Current for 30°C Rise (A)
0.5
1
1.0
1.5
1.9
1.0
1
1.7
2.5
3.2
2.0
1
2.8
4.1
5.3
3.0
1
3.7
5.5
7.0
1.0
2
2.6
3.9
5.0
2.0
2
4.3
6.4
8.2

Advanced Thermal Management Solutions

Embedded Heat Pipes and Vapor Chambers

Heat pipes and vapor chambers utilize phase change to achieve very high effective thermal conductivities:

Heat Pipe Integration in PCBs

Integration Method
Thermal Performance
Manufacturing Complexity
Surface-mounted
Good
Low
Partially embedded
Very good
Medium
Fully embedded
Excellent
High
Integrated in metal core
Excellent
High

Heat pipe performance characteristics:

Parameter
Typical Range
Impact
Effective thermal conductivity
5,000-200,000 W/m·K
Orders of magnitude better than copper
Operating temperature range
-40 to 150°C
Working fluid dependent
Heat transport capacity
10-250W
Size and design dependent
Form factor
2-12mm diameter
Application dependent

Vapor Chamber Technology

Vapor chambers function similarly to heat pipes but spread heat in two dimensions:

Aspect
Characteristic
Application
Thickness
0.5-5mm
Space-constrained designs
Effective area
Up to 20x20cm
Large area heat spreading
Thermal resistance
0.1-0.5°C/W
High-performance cooling
Integration complexity
Medium to high
High-value applications

Thermal Stackup Design

Advanced PCB stackup design significantly impacts thermal performance:

Thermally Optimized Layer Configurations

| Stackup Strategy | Thermal Benefit | Implementation