ITEQ IT-859GTA vs Bergquist HT: Metal Core PCB Material Comparison

In the world of power electronics and high-brightness LED arrays, heat is the ultimate enemy of reliability. When a design pushes past the limits of standard FR-4, the selection of an Insulated Metal Substrate (IMS) or Metal Core PCB (MCPCB) becomes a critical architectural decision.

For engineers, the choice often boils down to two heavyweights: ITEQ IT-859GTA and Bergquist Thermal Clad HT. Both materials are designed to solve the “thermal wall” by replacing fiberglass with a thermally conductive dielectric and a metal base. However, they represent different regional and market approaches to the same problem.

This deep-dive comparison strips away the marketing jargon to analyze the technical DNA of IT-859GTA vs. Bergquist, providing the engineering data needed to decide which substrate belongs in your next high-power stackup.

---

The Engineering Logic: Why Move to Metal Core?

Before pitting these materials against each other, it is essential to understand the physics of the transition. Standard FR-4 has a thermal conductivity ($k$) of roughly $0.25\text{ W/m}\cdot\text{K}$. In a high-power LED or a GaN/SiC power converter, this resin acts as a thermal insulator, trapping heat at the component junction.

An MCPCB solves this by utilizing a three-layer sandwich: a circuit layer, a thin, highly conductive dielectric, and a metal base (typically Aluminum 5052 or 6061).

The dielectric is the “engine” of the board. It must be thin enough to transfer heat rapidly but robust enough to prevent electrical breakdown between the high-voltage circuit and the grounded metal base.

---

ITEQ IT-859GTA: The Reliable High-Volume Contender

ITEQ IT-859GTA is a high-performance, halogen-free Aluminum-based laminate. It has become a staple in the Asian manufacturing hub, favored for its balanced thermal performance and aggressive cost-to-performance ratio.

Key Engineering Features

Thermal Conductivity: Typically rated at $>2.0\text{ W/m}\cdot\text{K}$ for the dielectric.

Halogen-Free Chemistry: Strictly “Green” and RoHS compliant, meeting the most stringent environmental mandates for global consumer electronics.

Mechanical Stability: With a $T_g \geq 100^\circ\text{C}$ (by DSC) and a high decomposition temperature ($T_d$ of $380^\circ\text{C}$), it offers excellent reliability through lead-free assembly.

Manufacturing “Friendly”: Known in the factory for having a predictable drilling and v-scoring profile, which leads to higher yields in mass production.

---

Bergquist Thermal Clad HT: The Industry Benchmark

Bergquist Thermal Clad HT (High Temperature) is part of the legendary Thermal Clad family, now manufactured by Henkel. It is widely considered the premium benchmark in North America and Europe for mission-critical power electronics.

Key Engineering Features

Superior Conductivity: The HT-04503 variant offers a dielectric conductivity of $2.2\text{ W/m}\cdot\text{K}$ and a system-level conductivity of $4.1\text{ W/m}\cdot\text{K}$.

Extreme Thermal Resilience: Boasts a $T_g$ of $150^\circ\text{C}$, significantly higher than ITEQ’s entry-level GTA, allowing it to survive continuous elevated operating temperatures without mechanical degradation.

AuSn & Wire Bond Compatible: Rated for $325^\circ\text{C}$ for 60 seconds, making it one of the few IMS materials that can handle Eutectic Gold-Tin die attach or thermosonic gold wire bonding.

Advanced Dielectric Physics: Bergquist uses a proprietary ceramic-polymer blend that maintains higher dielectric strength even at ultra-thin thicknesses (3 mil).

---

Side-by-Side: Technical Specifications Comparison

When evaluating IT-859GTA vs. Bergquist, the datasheet provides the primary constraints for your thermal simulation software (like Ansys Icepak or FloTHERM).

Table 1: Comparative Material Properties (Typical Values)

Property	Units	ITEQ IT-859GTA	Bergquist HT (HT-04503)
Dielectric Conductivity ($k$)	$\text{W/m}\cdot\text{K}$	~2.2	2.2 (ASTM D5470)
Thermal Resistance ($R_{th}$)	$^\circ\text{C}\cdot\text{in}^2/\text{W}$	0.8 (estimated)	0.05 (for 3 mil)
Glass Transition ($T_g$)	$^\circ\text{C}$ (DSC)	100 – 105	150
Decomposition Temp ($T_d$)	$^\circ$C	380	330+ (Solder limit 325°C)
Dielectric Strength	$\text{V/mil}$	1000	2000
Breakdown Voltage	$\text{kVAC}$	4.0 (for 4 mil)	8.5 (for 3 mil)
Z-Axis CTE ($\alpha 1$)	$\text{ppm}/^\circ\text{C}$	40	25
Halogen-Free	–	Yes	Yes

Analysis of the Data

Thermal Impedance: While both offer similar raw conductivity numbers ($\sim 2.2\text{ W/m}\cdot\text{K}$), Bergquist’s $R_{th}$ is exceptionally low due to the ability to maintain dielectric integrity at thinner layers.

Operating Window: Bergquist HT has a clear edge in $T_g$ ($150^\circ\text{C}$ vs $105^\circ\text{C}$). For automotive under-hood applications or high-wattage industrial motor drives where the substrate temperature exceeds $100^\circ\text{C}$, Bergquist is the safer engineering choice.

Dielectric Strength: Bergquist provides double the dielectric strength per mil ($2000\text{ V/mil}$ vs $1000\text{ V/mil}$). This allows for a thinner board with higher isolation safety—critical for mains-connected power supplies.

---

Fabrication Realities: Processing in the Factory

A laminate is only useful if it can be manufactured with high yields.

ITEQ IT-859GTA Advantage: It is designed to be “fabricator friendly.” The resin-glass-aluminum bond is optimized for standard mechanical drilling and punching. It is widely stocked in Asia, meaning lead times for high-volume LED light bar production are typically shorter.

Bergquist HT Advantage: While more expensive, Bergquist is the “gold standard” for reliability. It is remarkably forgiving during reflow and rework. Its high solder limit ($325^\circ\text{C}$) means you can perform multiple rework cycles on a dense power module without worrying about the dielectric delaminating from the aluminum base.

---

Which Material Is Right for You?

The “winner” of the IT-859GTA vs. Bergquist showdown depends on your specific power density and target market.

Choose ITEQ IT-859GTA If:

Cost is the Priority: You are designing high-volume consumer LED products (street lamps, LCD TV light bars, or notebook backlighting).

Moderate Power Density: Your component junction temperatures are managed well enough that the substrate stays below $90^\circ\text{C}$.

Asian Supply Chain: Your manufacturing is based in China or Taiwan, where ITEQ is the dominant, readily available local brand.

Choose Bergquist Thermal Clad HT If:

Mission-Critical Reliability: You are designing automotive headlamps, motor drives, or solid-state relays where failure is not an option.

High Power Density: You are using GaN or SiC transistors where the heat flux is extremely high, requiring the lowest possible thermal resistance ($0.05^\circ\text{C}\cdot\text{in}^2/\text{W}$).

Advanced Assembly: You require AuSn die attach or gold wire bonding.

High Voltage: Your application operates at or above 480V AC, requiring the superior dielectric breakdown headroom of the HT family.

---

Essential Resources for Design Engineers

Before finalizing your stackup, lean on verified technical data:

ITEQ IT-859GTA Official Datasheet: Access the full material properties and processing guidelines for the ITEQ PCB family.

Bergquist Thermal Clad Selection Guide: A comprehensive tool to choose between HT, MP, and HPL dielectric grades.

ASTM D5470: Familiarize yourself with this test method; it is the industry standard for measuring thermal conductivity in dielectrics.

UL 746B / 796: Check the Maximum Operating Temperature (MOT) and Solder Limit ratings for your chosen grade to ensure safety compliance.

---

Frequently Asked Questions (FAQs)

1. Can I use ITEQ IT-859GTA for a 480V motor drive?

Technically, yes, if the dielectric thickness is sufficient. However, Bergquist HT is specifically recommended for applications above 480V due to its higher dielectric strength and verified breakdown voltage at thinner layers.

2. Is Bergquist HT halogen-free?

Yes, the modern Thermal Clad HT family is halogen-free and environmentally green, complying with RoHS and REACH standards.

3. Are these materials interchangeable in a design?

Not exactly. Because they have different $T_g$ ratings and dielectric constants ($D_k \approx 5$ for ITEQ vs $D_k \approx 7$ for Bergquist), a design optimized for the thermal expansion of one might behave differently with the other. Always perform a fresh thermal and mechanical simulation before switching.

4. Why is the metal base usually Aluminum 5052?

Aluminum 5052 offers a good balance of thermal conductivity ($\sim 138\text{ W/m}\cdot\text{K}$), corrosion resistance, and cost. For extreme applications, Copper bases can be used with both materials to provide even higher heat spreading.

5. Does ITEQ IT-859GTA require special drilling bits?

Yes. Like all MCPCB materials, the ceramic fillers are abrasive. Using standard FR-4 drill bits will result in rapid tool wear and poor hole wall quality. Specialized carbide bits are mandatory.