# IMS PCB Material Selection & Design Guideline

_Published: 2025-07-22_

Table of Contents

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- What Is IMS Material?
- IMS PCB Material Properties
- IMS PCB Board Material Datasheet
- What Are Types of IMS PCB Material?
- How to Choose IMS PCB Material?
- How to Design IMS PCB Board?
- IMS PCB Board Design Considerations
- How to Select A Reliable IMS PCB Manufacturer?

Are you worried about how to choose** **[IMS PCB material](https://www.bestpcbs.com/blog/2025/07/ims-pcb-material-selection-design-guideline/)for your project? Let’s explore its definition, properties, datasheet, types, IMS PCB material selection and design guidelines through this blog.

- Wrong choice of substrate material leads to too high thermal resistance?
- Is the dielectric layer easy to delaminate during multi-layer IMS design?
- Is the dielectric loss too large under high-frequency application?

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## What Is IMS Material?

**[IMS material](https://www.bestpcbs.com/blog/2025/07/ims-pcb-material-selection-design-guideline/)**, known as** **insulated metal substrate, consists of a metal core, typically aluminum or copper, coated with a dielectric insulation layer and a conductive copper layer for circuit traces. This structure delivers outstanding thermal management, with aluminum-based versions achieving thermal conductivity of 1-3 W/(m·K), while copper-based variants exceed 400 W/(m·K) for accelerated heat dissipation.

It serves effectively in high-power applications like LED lighting systems and automotive electronics, where efficient cooling maintains device stability and extends operational lifespan under thermal stress.

[https://www.bestpcbs.com/blog/wp-content/uploads/2025/07/main-33.jpg](https://www.bestpcbs.com/blog/wp-content/uploads/2025/07/main-33.jpg)

## IMS PCB Material Properties

- Thermal Conductivity – Metal base (aluminum/copper) transfers heat 5-10x faster than FR4, keeping components cooler.
- Electrical Insulation– Dielectric layer provides high voltage isolation (1-10kV) while allowing heat flow.
- Mechanical Strength – Metal core resists bending/warping, ideal for heavy components or high-vibration environments.
- Thermal Expansion – Low CTE (Coefficient of Thermal Expansion) matches components, reducing solder joint stress.
- Temperature Resistance – Withstands 150-250℃ operating temperatures without degradation.
- Weight Efficiency – Aluminum bases offer lightweight heat dissipation, crucial for automotive/aerospace.
- Surface Flatness – Metal substrates ensure precise component mounting, critical for fine-pitch devices.

## IMS PCB Board Material Datasheet

**Property**
**Aluminum-Based IMS**
**Copper-Based IMS**
**Measurement Standard**

Thermal Conductivity
1-3 W/(m·K)
>400 W/(m·K)
ASTM E1461

Dielectric Strength
≥4 kV/mm
≥4 kV/mm
IPC-TM-650 2.5.6

CTE (Z-axis)
12-15 ppm/°C
16-18 ppm/°C
IPC-TM-650 2.4.24

Tg (Glass Transition)
130-150°C
150-170°C
IPC-TM-650 2.4.25

Td (Decomposition)
300-320°C
350-380°C
IPC-TM-650 2.3.40

Volume Resistivity
≥10¹² Ω·cm
≥10¹² Ω·cm
IPC-TM-650 2.5.17

Flexural Strength
100-150 MPa
200-250 MPa
IPC-TM-650 2.4.4

## What Are Types of IMS PCB Material?

**Aluminum-Based IMS**

- Thermal Conductivity: 1-2.5W/m·K.
- Application: LED lighting, consumer power supplies, and automotive controls where cost efficiency and moderate heat dissipation are prioritized.

**Copper-Based IMS**

- Thermal Conductivity: 3-4W/m·K.
- Application: High-power industrial drives, automotive powertrains, and aerospace components requiring extreme thermal performance.

**Stainless Steel-Based IMS**

- Thermal Conductivity: 0.2-0.5W/m·K.
- Application: Corrosive environments (e.g., marine, chemical processing) where mechanical durability outweighs thermal needs.

**Composite Metal Core IMS**

- Structure: Aluminum/copper layer bonded to a thin copper circuit layer.
- Application: Compact devices like mobile chargers and RF amplifiers needing both heat spreading and fine-pitch circuitry.

[https://www.bestpcbs.com/blog/wp-content/uploads/2025/07/3-4.jpeg](https://www.bestpcbs.com/blog/wp-content/uploads/2025/07/3-4.jpeg)

## How to Choose IMS PCB Material?

**[IMC PCB Material Selection Guideline](https://www.bestpcbs.com/blog/2025/07/ims-pcb-material-selection-design-guideline/)**:

**1. Assess Power Density Requirements**

- High-Power Applications (e.g., industrial drives, automotive power modules):
- Choose copper-based IMS (thermal conductivity 3-4W/m·K) for power densities exceeding 5W/cm².
- Standard Applications (e.g., LED lighting, consumer electronics):
- Prioritize aluminum-based IMS (1-2.5W/m·K) for power densities below 5W/cm².

**2. Align with Budget Constraints**

- Aluminum-based IMS costs 20-30% less than copper, making it suitable for cost-driven projects like household appliances.
- Reserve copper-based IMS for premium sectors (aerospace, medical devices) where long-term reliability outweighs upfront costs.

**3. Match Environmental Conditions**

- Corrosive Environments (marine, chemical processing): Select stainless steel-based IMS for corrosion resistance, despite lower thermal efficiency.
- High-Temperature Zones (engine compartments, RF amplifiers): Use copper-based IMS with polyimide insulation (withstanding temperatures >200°C).

**4. Account for Spatial Limitations**

- Compact Devices (mobile chargers, wearables): Choose aluminum composite IMS (0.8mm thickness) to balance heat dissipation and space efficiency.
- Multi-Layer Designs: Prioritize copper-based IMS for structural rigidity, preventing warping in complex PCB stacks.

**5. Validate Compliance with Standards**

- Critical Systems (automotive ECU, aerospace): Demand IPC-6013-certified copper-based IMS with documented thermal cycling test results.
- Consumer Products (TVs, monitors): Aluminum-based IMS meets 85°C operational requirements for typical use cases.

**6. Decision-Making Framework**

- Start with power density thresholds to narrow material options.
- Cross-reference with budget allocation and environmental exposure.
- Finalize with space constraints and certification needs.

**7. Application Examples**

- Industrial Motor Control: Copper-based IMS for sustained 100A+ current handling.
- Outdoor LED Displays: Aluminum-based IMS with conformal coating for humidity resistance.
- Automotive Powertrain: Copper-based IMS + high-temperature dielectric for under-hood reliability.

**8. Critical Precautions**

- Request third-party thermal resistance reports to verify supplier claims.
- Avoid materials with unspecified dielectric breakdown voltage in high-voltage applications.
- Test prototypes under real-world thermal stress before mass production.

## How to Design IMS PCB Board?

**[IMS PCB Design Guideline](https://www.bestpcbs.com/blog/2025/07/ims-pcb-material-selection-design-guideline/):**

**1. Define Design Objectives**

- Clarify power density (W/cm²), operating environment (temperature/humidity), space limits, and budget. Example: Automotive ECU board needing 50A current handling in 100°C engine bay.

**2. Material Selection Recap**

- High-Power (>5W/cm²): Copper-based IMS (3-4W/m·K).
- Cost-Sensitive: Aluminum-based IMS (1-2.5W/m·K).
- Corrosive Environments: Stainless steel-based IMS.

**3. Layer Stackup Design**

- Place metal base directly below high-power components.
- Keep dielectric layer thickness ≤100µm for optimal thermal performance.
- Example: 2-layer IMS (copper base + 35µm circuit layer).

**4. Thermal Management Strategies**

- Thermal Vias: Use 0.5mm diameter filled vias under hot components, spaced 1mm apart.
- Reserved Cooling Zones: Allocate 30-50% of board area as unpopulated metal regions.
- Component Placement: Center power devices (MOSFETs/IGBTs) over the metal core; keep ≥2mm spacing between high-power parts.

**5. Electrical Layout Optimization**

- Trace Width: Use 3oz (105µm) copper for traces carrying >50A. Widen traces by 2x near heat sources.
- Avoid Sharp Bends: Maintain ≥3x trace width for bend radii to reduce resistance.
- Impedance Control: For RF/high-speed signals, keep dielectric thickness consistent (±10µm tolerance).

**6. Manufacturing Compatibility**

- Design Rules: Minimum trace width/spacing ≥0.2mm for aluminum IMS; ≥0.15mm for copper IMS.
- Solder Mask: Remove mask in thermal zones to maximize metal exposure.
- Panelization: Add 2mm border around boards for handling during assembly.

**7. Validation & Testing**

- Thermal Imaging: Test under max load to identify hotspots. Junction temp should stay ≤85°C.
- Electrical Testing: Verify current capacity and signal integrity (e.g., 400 W/mK) is ideal for high-power modules requiring rapid heat dissipation.
- Dielectric Thickness‌: Thinner layers (50-100μm) improve heat transfer but reduce voltage isolation. Match thickness to operational voltage (e.g., 100μm for 500MHz).

**Mechanical Design‌**

- Board Thickness‌: Standard metal cores (1.0-3.0mm) prevent flexing but increase weight. For lightweight needs, consider 1.0mm aluminum.
- Mounting Hardware‌: Use insulated standoffs to prevent short circuits with the metal base. Account for CTE mismatch, aluminum expands 23ppm/°C versus 17ppm/°C for copper.
- Cutouts & Edges‌: Smooth, rounded edges minimize stress concentrations. Internal cutouts require laser processing to avoid burrs.

**Manufacturing & Cost‌**

- Fabrication Tolerance‌: IMS requires specialized drilling (carbide bits) due to metal hardness. Allow ±0.1mm for hole positioning.
- Panel Utilization‌: Standard panel sizes (18″×24″) optimize cost. Odd shapes increase waste.
- Finish Options‌: HASL is cost-effective but limits thermal performance. ENIG (Ni/Au) enhances solderability for fine-pitch components.

**Application-Specific Tips‌**

- LED Arrays‌: Use 1.5mm aluminum cores with 80μm dielectric to balance cost and heat dissipation (ΔT