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ITEQ IT-859GT is a 3 W/mK halogen-free metal core PCB laminate for high-power LED and power electronics. Full specs, comparisons, fab tips, and FAQs.
If you’ve spent any time sourcing IMS (Insulated Metal Substrate) materials for LED driver boards, street lighting modules, or power converter assemblies, you’ve almost certainly landed on a shortlist that includes the ITEQ IT-859GT. This material — and its close relative the IT-859GTA — has quietly become one of the go-to metal core laminate choices among PCB engineers who need reliable thermal performance without chasing exotic substrate costs.

This article breaks down everything you need to know about the ITEQ IT-859GT: its key properties, how it stacks up against competing IMS laminates, where it fits in real-world designs, and how to specify it correctly when talking to your fabrication house.

What Is ITEQ IT-859GT? Understanding the Material Basics

ITEQ IT-859GT is a halogen-free, multifunctional filled-epoxy metal-base laminate reinforced with glass fabric. It sits squarely in ITEQ’s IMS (Insulated Metal Substrate) product family, specifically engineered to solve the thermal bottleneck that kills high-power LED and power electronics designs built on conventional FR-4.

The “GT” suffix signals that this is ITEQ’s glass-fabric reinforced thermal series. The companion grade, IT-859GTA, carries the same core formulation but with slightly refined dielectric characteristics and is listed separately under ITEQ’s UL certifications — both appear on the UL E178114 recognition for ITEQ Corporation.

At the heart of the IT-859GT’s value proposition are three characteristics that matter to working engineers:

• Thermal conductivity of 3 W/mK — a significant step above standard 1.0–1.5 W/mK IMS dielectrics
• Halogen-free formulation — RoHS compliant and suitable for environmentally sensitive markets
• 260°C lead-free assembly compatibility — survives modern reflow profiles without delamination concerns

That 3 W/mK figure is particularly worth dwelling on. Standard FR-4 sits around 0.3 W/mK for thermal conductivity. Even typical aluminum IMS boards with commodity dielectrics only reach 1.0–1.6 W/mK. At 3 W/mK, the IT-859GT’s dielectric layer transfers heat roughly twice as fast as standard IMS materials, which directly translates to lower junction temperatures in your LEDs and power devices.

ITEQ IT-859GT Key Technical Specifications

The table below summarizes the published properties for the ITEQ IT-859GT / IT-859GTA:

Property	Value	Test Method
Glass Transition Temperature (Tg)	100°C (DSC)	IPC-TM-650 2.4.25
Thermal Conductivity (Dielectric)	3.0 W/mK	—
Lead-Free Assembly Compatibility	Pass 260°C	IPC-TM-650 2.6.27
Halogen Content	Halogen-Free	IEC 61249-2-21
RoHS Compliance	Yes	EU RoHS Directive
Metal Base Material	Aluminum (standard)	—
Available Copper Weights	0.5 oz to 6 oz	—
Construction Options	Single-sided, Double-sided	—
UL Flame Rating	UL 94 V-0	UL 94
UL File Number	E178114	UL

Note on Tg: The 100°C Tg might look low compared to high-Tg FR-4 grades (Tg 170°C+). In an IMS context, this is not a red flag. The metal substrate (aluminum or copper) handles the mechanical load, and the dielectric layer’s primary job is thermal transfer and electrical isolation — not structural stiffness. The Tg is sufficient for the operating envelope of LED and power electronics applications.

Why 3 W/mK Matters: Thermal Performance in Context

One of the most common mistakes engineers make when evaluating IMS laminates is treating thermal conductivity as an abstract specification rather than tracing its effect through the thermal stack.

In a standard MCPCB structure, heat travels this path:

LED Junction → Solder → Copper Trace → Dielectric Layer → Metal Substrate → Heatsink/Chassis

The dielectric layer is almost always the dominant thermal resistance in this chain. Copper and aluminum conduct heat orders of magnitude faster than any polymer-based dielectric, so the dielectric’s conductivity — not the metal base — determines how quickly heat escapes the junction.

Consider a simplified comparison:

Dielectric Thermal Conductivity	Relative Thermal Resistance (Dielectric Layer)	Practical Impact
0.3 W/mK (standard FR-4)	Very high — not suitable for IMS	LED lifetime severely impacted
1.0 W/mK (standard IMS)	Moderate	Adequate for low-power LEDs
1.6 W/mK (standard IMS, upgraded)	Improved	Suitable for mid-power applications
3.0 W/mK (ITEQ IT-859GT)	Significantly lower	High-power LEDs, automotive lighting, street lighting
4.2+ W/mK (premium IMS)	Very low	Highest-power, cost-sensitive to trade-off

For a 10W LED module operating at a 40°C ambient, the difference between a 1.0 W/mK dielectric and a 3.0 W/mK dielectric can mean 15–25°C lower junction temperature — which can double the LED’s rated lifespan or allow higher drive currents for the same junction temperature budget.

Target Applications for ITEQ IT-859GT

ITEQ’s own documentation lists these primary applications for the IT-859GT and IT-859GTA:

• Notebook light bar LED lighting
• LCD TV light bar assemblies
• Automobile lighting modules
• Traffic lighting systems
• Street lamps and outdoor luminaires

In practice, the material sees equally strong use in power electronics where the LED angle is less relevant:

Power Electronics Applications:

• Switching power supply base boards (SMPS)
• Motor drive inverter boards
• DC-DC converter assemblies
• Solid-state relay substrates
• Solar inverter power stage boards

The 260°C lead-free assembly pass and the RoHS-compliant halogen-free chemistry make it particularly well-suited for automotive lighting and lighting products sold into EU markets where both environmental and reliability standards are stringent.

IT-859GT vs. Competing IMS Laminates: How Does It Compare?

If you’re evaluating the ITEQ IT-859GT against other IMS materials in the same thermal class, here’s a practical comparison:

Material	Manufacturer	Thermal Conductivity	Halogen-Free	Key Differentiator
IT-859GT / IT-859GTA	ITEQ	3.0 W/mK	Yes	Glass fabric reinforced, broad UL coverage
VT-4B3	Ventec	3.0 W/mK	Yes	Similar spec, Ventec distributor network
VT-4B5	Ventec	4.2 W/mK	Yes	Higher conductivity premium grade
T-Lam DS 1KA	Laird	~3.0 W/mK	Varies	Widely referenced; IT-859GT benchmarked against it
VT-4A1	Ventec	1.6 W/mK	Varies	Standard-grade aluminum IMS
Bergquist GP3000	Henkel	~3.0 W/mK	Varies	Well-known in North American supply chains

One important detail: ITEQ’s published data for IT-859GTA references thermal conductivity “based on Laird 1KA04 as reference.” This is a common industry benchmark, confirming that the IT-859GT is directly competitive with — and in many cases a drop-in replacement for — Laird’s T-Lam DS 1KA grade. This matters for procurement engineers who need to qualify alternative suppliers or second-source their IMS material.

Construction Options and Design Flexibility

The IT-859GT is available in both single-sided and double-sided configurations across a wide range of copper weights (0.5 oz through 6 oz). This range gives designers real flexibility:

Copper Weight Selection Guide:

Copper Weight	Typical Use Case
0.5–1 oz (17–35 µm)	Standard LED lighting, fine-pitch component placement
2 oz (70 µm)	Power electronics, moderate current carrying
3 oz (105 µm)	High-current bus bars, heavy-load power stages
4–6 oz (140–210 µm)	Extreme-duty power electronics, motor drives

For LED applications, 1 oz copper is the most common choice. For power electronics — particularly SMPS and motor drives — 2–3 oz copper on an IT-859GT substrate provides an effective combination of current capacity and thermal dissipation.

On board thickness, standard IMS offerings run from 1.0mm to 2.0mm. The metal base (typically aluminum 5052 alloy for most IMS builds) provides the majority of this thickness, with the dielectric and copper layers adding a comparatively thin profile on top.

Fabrication Considerations for ITEQ IT-859GT Boards

Working with IT-859GT differs from standard FR-4 fabrication in several important ways. If you’re communicating with your PCB fabrication house, here are the parameters worth specifying explicitly:

Drilling: IMS laminates require carbide tooling. The aluminum base can cause drill wander if tool selection and feed rates aren’t tuned for the metal substrate. Blind vias and buried vias are generally not possible in single-layer IMS — the metal core is the termination.

Solder Mask: For LED applications, specify a white solder mask. White solder mask typically achieves over 85% light reflectivity, directly boosting luminous efficiency of your LED array by reflecting light that would otherwise be absorbed by the board surface.

Surface Finish: HASL (lead-free) is workable for larger LED pads. For fine-pitch components or wire bonding, specify ENIG (Electroless Nickel Immersion Gold). ENIG provides a flatter surface and better solderability for repeated thermal cycling.

Hi-Pot Testing: Because IMS boards are used in high-voltage power applications, always specify a hipot (dielectric withstand voltage) test. Typical requirements are 1500–3000V AC. The IT-859GT’s glass fabric reinforcement in the dielectric layer contributes to consistent dielectric strength across the panel.

V-Score and Routing: Aluminum-base IMS boards cannot be routed or scored the same way as FR-4. Your fabricator will need to use scoring blades rated for aluminum. Discuss panelization and depaneling method early in the design process to avoid tooling surprises.

Where to Source ITEQ IT-859GT and Get Design Support

For production boards built on ITEQ IT-859GT, your best starting point is working with a PCB fabricator that has the material pre-qualified and stocked. For a full overview of ITEQ PCB solutions — including IT-859GT availability, stack-up support, and volume pricing — ³Ô¹Ïtv is a strong resource for both prototypes and production runs.

Useful Resources for Engineers

Resource	Description	Link
ITEQ IT-859GTA Product Page	Official ITEQ IMS product listing with application notes
ITEQ UL Recognition (E178114)	UL Prospector listing for IT-859GT and IT-859GTA certifications
PCB Directory – ITEQ IT-859GTA	Third-party laminate database with downloadable datasheet
IPC-TM-650 Test Methods	Standard test methods referenced in laminate datasheets
Lasance – PCB Thermal Management for LED (PDF)	Technical paper on MCPCB thermal design fundamentals
Saturn Electronics UL Materials Chart	Cross-reference for UL-certified IMS materials by manufacturer

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5 Frequently Asked Questions About ITEQ IT-859GT

1. Is ITEQ IT-859GT the same material as IT-859GTA?

They are closely related but carry separate UL listings. The IT-859GTA is the more recent and more widely documented variant in ITEQ’s official IMS product line. Both share the same 3 W/mK thermal conductivity and halogen-free filled epoxy formulation, and both appear under ITEQ’s UL E178114 recognition. In most fabrication contexts, IT-859GT and IT-859GTA are functionally interchangeable — confirm with your fabrication house which variant they stock and whether your UL listing (if required) covers that specific grade suffix.

2. Can ITEQ IT-859GT be used for double-sided or multilayer assemblies?

The IT-859GT is available in both single-sided and double-sided constructions. True multilayer IMS (more than two conductive layers) is possible but adds fabrication complexity and cost. For most LED and power electronics applications, single-sided IMS is sufficient and preferable. If your design genuinely needs multilayer capability, discuss stack-up options with your fabricator — some shops laminate an IMS base with standard FR-4 prepreg layers for hybrid constructions, though thermal performance through those FR-4 layers will be significantly reduced.

3. Why does ITEQ IT-859GT have a Tg of only 100°C if it’s used in high-temperature applications?

This is a common question from engineers familiar with high-Tg FR-4. In metal core boards, the Tg specification primarily governs the dielectric polymer layer, not the overall board rigidity. The aluminum substrate carries the mechanical load and maintains dimensional stability well beyond the polymer’s Tg. For standard LED and power electronics operating environments — typically 85°C maximum continuous junction temperature — a 100°C Tg dielectric performs reliably. The 260°C lead-free assembly pass is the more operationally critical thermal specification for manufacturing.

4. How does ITEQ IT-859GT compare to standard aluminum PCB (1.0 W/mK IMS)?

At 3.0 W/mK versus 1.0 W/mK, the IT-859GT’s dielectric transfers heat roughly three times faster than a standard IMS dielectric at the same thickness. In a high-power LED design, this can reduce junction-to-substrate thermal resistance by 50% or more, enabling either higher drive currents for the same junction temperature, or the same drive current at a significantly lower junction temperature (and correspondingly longer LED lifespan). The trade-off is cost: 3 W/mK IMS materials carry a price premium over commodity 1.0 W/mK boards. For applications above roughly 5W per LED cluster or 50W total power density, the IT-859GT’s thermal step-up is typically worth the additional material cost.

5. Does ITEQ IT-859GT require special handling or storage compared to FR-4?

Yes. IMS laminates with aluminum bases are susceptible to surface oxidation if stored in humid environments, which can affect adhesion during lamination. Store panels in sealed packaging with desiccant, and follow ITEQ’s recommended bake-out procedures before lamination if the material has been in ambient storage for an extended period. The copper foil surface on incoming laminate should be inspected for oxidation before use. Unlike FR-4, IMS panels cannot be flexed or scored arbitrarily — the aluminum core will deform rather than fracture cleanly, so depaneling must be planned into the design from the start.

Engineer’s Takeaway

The ITEQ IT-859GT earns its place in high-power LED and power electronics designs through a combination of attributes that individually exist elsewhere, but rarely stack this neatly together: 3 W/mK thermal conductivity, halogen-free chemistry, glass fabric reinforcement for consistent dielectric properties, 260°C lead-free assembly compatibility, and a broad range of copper weights from 0.5 oz to 6 oz.

It isn’t the highest thermal conductivity IMS available — if you’re chasing 4+ W/mK you’ll look at Ventec VT-4B5 or similar premium grades. But for the broad middle of the market — street lighting, automotive LED modules, LCD backlights, SMPS boards — the IT-859GT hits the thermal performance target while keeping supply chain complexity manageable and BOM cost predictable.

Specify it with a white solder mask for LED work, call out hipot testing requirements in your fabrication notes, discuss depaneling early with your fab house, and you’ll find it a very well-behaved material to build with.