Bergquist HT-07006 Metal Core PCB: Complete Specifications & Applications

When a power electronics design crosses the 480 VAC working voltage threshold, the thermal substrate question gets harder. Below that voltage, the Bergquist HT-04503 at 3 mil dielectric thickness handles both the thermal and isolation requirements in most applications. Above it, you need more dielectric headroom — and that’s exactly where the Bergquist HT-07006 sits in the Thermal Clad product family.

HT-07006 is the 6 mil (152 µm) member of Bergquist’s High Temperature MCPCB dielectric family, delivering 11 kVAC breakdown voltage while maintaining the same 2.2 W/m-K dielectric thermal conductivity and 150°C glass transition temperature as its 3 mil sibling. It was specifically noted in Bergquist’s own datasheet language as featuring “even higher dielectric breakdown characteristics than HT-04503.” For engineers designing three-phase motor drives, mains-isolated power converters, industrial inverters, solar inverters, and high-power solid-state relays, that combination of 11 kVAC isolation, 4.1 W/m-K system thermal conductivity, and 140°C UL RTI in a single substrate is the engineering value proposition.

This article gives you the complete HT-07006 specifications from the official datasheet, a full comparison against the Thermal Clad family, detailed application guidance, design and fabrication recommendations, and all the resources you need to evaluate whether HT-07006 is the right substrate for your design.

What Is Bergquist HT-07006? Understanding Thermal Clad Technology

Bergquist (acquired by Henkel in 2014) developed the Thermal Clad platform as an insulated metal substrate (IMS) solution — a three-layer construction combining a copper circuit foil, a thermally conductive polymer-ceramic dielectric, and a metal base (aluminum or copper) that serves as the structural heat spreader. The approach solves a fundamental problem in power electronics: FR-4’s thermal conductivity of 0.25 W/m-K simply cannot remove heat fast enough from high-density power devices, while traditional ceramics are fragile, expensive, and difficult to process using standard PCB manufacturing methods.

The entire performance differentiation of Thermal Clad lies in the dielectric layer. Bergquist’s proprietary polymer-ceramic blend achieves high thermal conductivity within a thin, electrically isolating layer by combining a polymer chosen for electrical isolation, thermal aging resistance, and high bond strength, with a ceramic filler that enhances thermal conductivity and maintains dielectric strength. The result is a dielectric that achieves 2.2 W/m-K thermal conductivity and 2000 V/mil dielectric strength simultaneously — properties that conventional organic dielectrics cannot combine.

The HT-07006 part number encodes its key specification: HT = High Temperature dielectric formulation, 070 = thermal impedance category reference, 06 = 6 mil (0.006 inch / 152 µm) dielectric thickness. It is available as both laminated panels and fabricated circuits, and can be supplied on aluminum or copper metal substrates.

For engineers specifying Bergquist PCB materials, HT-07006 sits between the HT-04503 (3 mil, 8.5 kVAC) and the HT-09009 (9 mil, 20 kVAC) in the high-temperature dielectric family, covering the voltage range where the 3 mil version runs out of isolation margin but a 9 mil dielectric imposes more thermal resistance than the design budget allows.

Bergquist HT-07006 Complete Datasheet Specifications

The following specifications are taken directly from the official BERGQUIST TCLAD TIC_TIP HT 07006 Technical Data Sheet (March 2019, Henkel Corporation) and represent typical properties of cured material.

HT-07006 Thermal Properties

Parameter	HT-07006 Value	Test Method
Product Thermal Conductivity	4.1 W/m-K	Bergquist MET 5.4-01-40000
Dielectric Thermal Conductivity	2.2 W/m-K	ASTM D5470
Thermal Resistance	0.71 °C·cm²/W (0.11 °C·in²/W)	ASTM D5470
Thermal Impedance	0.70 °C/W	Bergquist MET-5.4-01-40000

The product thermal conductivity of 4.1 W/m-K is a system-level figure measured including the copper circuit layer and aluminum/copper substrate. The dielectric thermal conductivity of 2.2 W/m-K is the dielectric-only measurement per ASTM D5470. When comparing materials, always use the dielectric thermal conductivity or thermal resistance values — product thermal conductivity includes metal layers and is not a dielectric comparison figure.

The thermal resistance of 0.11 °C·in²/W is the key thermal design parameter. For a 1 cm² device footprint dissipating 10 W, this translates to 0.11 × 10 / 0.155 = approximately 7°C temperature rise across the dielectric. That’s the number to use in junction temperature budgets.

HT-07006 Electrical Properties

Parameter	HT-07006 Value	Test Method
Dielectric Constant (Dk)	7	ASTM D150
Dissipation Factor @ 1 kHz	0.0038	ASTM D150
Dissipation Factor @ 1 MHz	0.0129	ASTM D150
Capacitance	43 pF/cm²	ASTM D150
Volume Resistivity	1 × 10¹⁴ Ω·m	ASTM D257
Surface Resistivity	1 × 10¹³ Ω/sq	ASTM D257
AC Breakdown Voltage	11 kVAC	ASTM D149

The 11 kVAC breakdown voltage is the headline electrical specification that distinguishes HT-07006 from HT-04503 (8.5 kVAC). For safety-isolated mains-voltage designs, the working voltage is only a fraction of the breakdown voltage — safety standards require significant derating. IEC 61558 and similar standards for isolated power converters require the substrate to withstand 2× working voltage plus 1000V for routine hipot testing. For a 600V working voltage system, that requires a test voltage of 2200V minimum, and HT-07006 at 11 kVAC provides a comfortable margin above that.

The capacitance of 43 pF/cm² (compared to 85 pF/cm² for HT-04503 at 3 mil thickness) is halved because the dielectric is twice as thick. This matters in high-frequency power conversion — lower substrate capacitance between the circuit layer and the grounded metal base reduces common-mode EMI coupling, which can simplify filtering and shield design in motor drives and inverters.

HT-07006 Physical and Mechanical Properties

Parameter	HT-07006 Value	Test Method
Technology	Epoxy	—
Appearance	White	Visual
Dielectric Thickness	0.006″ (152 µm)	—
Peel Strength @ 25°C	1.1 N/mm	ASTM D2861
Glass Transition Temperature (Tg)	150°C	ASTM E1356
CTE (XY/Z Axis, below Tg)	25 µm/m·°C	ASTM D3386
CTE (XY/Z Axis, above Tg)	95 µm/m·°C	ASTM D3386
Storage Modulus @ 25°C	16 GPa	ASTM D4065
Storage Modulus @ 150°C	7 GPa	ASTM D4065

HT-07006 Chemical Properties and Outgassing

Parameter	HT-07006 Value	Test Method
Water Vapor Retention	0.21% wt.	ASTM E595
Outgassing Total Mass Loss (TML)	0.23% wt.	ASTM E595
Collected Volatile Condensable Material (CVCM)	< 0.01% wt.	ASTM E595

HT-07006 Agency Ratings and Certifications

Parameter	HT-07006 Rating	Standard
UL Maximum Operating Temperature (RTI)	140°C	UL 746B
UL Flammability	V-0	UL 94
Comparative Tracking Index (CTI) — ASTM	0	ASTM D3638
Comparative Tracking Index (CTI) — IEC	600	IEC 60112
UL Solder Limit Rating	325°C / 60 seconds	UL 796
Max Operating Temperature	140°C	UL 796
Max Soldering Temperature	325°C	UL 796

CTI 600 under IEC 60112 represents Material Group I — the highest possible tracking resistance classification. This affects the required creepage distances in safety-certified designs under IEC 60664 and similar standards. A CTI Group I material requires shorter creepage distances than lower-rated materials, directly benefiting board layout density in high-voltage power designs.

The UL solder limit of 325°C/60 seconds enables use of Eutectic Gold/Tin (AuSn) solders, which require higher process temperatures than standard SAC305. This is important for high-reliability applications in automotive, avionics, and defense where AuSn solder joints offer better thermal fatigue resistance.

How HT-07006 Fits Into the Bergquist Thermal Clad Family

Understanding where HT-07006 sits relative to its siblings helps engineers make the right selection for their specific voltage and thermal requirements.

Complete Thermal Clad Family Comparison

Parameter	HT-04503	HT-07006	HT-09009	MP-06503	HPL-03015
Dielectric Thickness	3 mil (76 µm)	6 mil (152 µm)	9 mil (229 µm)	3 mil (76 µm)	1.5 mil (38 µm)
Dielectric Thermal Cond. (W/m-K)	2.2	2.2	2.2	1.3	3.0
Thermal Resistance (°C·cm²/W)	0.32	0.71	1.03	0.58	0.13
Thermal Impedance (°C/W)	0.45	0.70	0.90	0.65	0.30
Breakdown Voltage (kVAC)	8.5	11.0	20.0	8.5	2.5
Capacitance (pF/cm²)	85	43	—	—	—
Dielectric Constant (Dk)	7	7	7	6	6
Glass Transition Temp (Tg)	150°C	150°C	150°C	90°C	185°C
UL Max Operating Temp	140°C	140°C	150°C	130°C	—
Peel Strength (N/mm)	1.1	1.1	1.1	1.6	0.9
Lead-free Compatible	Yes	Yes	Yes	Yes	Yes
AuSn Compatible	Yes	Yes	Yes	Yes	—
RoHS	Yes	Yes	Yes	Yes	Yes

The HT family (HT-04503, HT-07006, HT-09009) share the same 2.2 W/m-K dielectric thermal conductivity and 150°C Tg. What changes across the family is dielectric thickness — which increases breakdown voltage and thermal resistance in direct proportion. Engineers choose within the HT family based on voltage requirements, then accept the associated thermal resistance that comes with the needed isolation thickness.

When to Choose HT-07006 Over HT-04503

The decision is largely about working voltage and required hipot test levels:

• Working voltage above 480 VAC (typical three-phase industrial) → HT-07006 provides margin; HT-04503 at 8.5 kVAC may be too close to the required test voltage
• Design requires IEC 60664 or UL 508A compliance with 480–600 VAC working voltage → HT-07006’s 11 kVAC provides better safety factor
• Lower substrate capacitance is beneficial for EMI (43 vs 85 pF/cm²) → HT-07006 halves the capacitive coupling versus HT-04503
• Thermal budget can absorb 0.11 vs 0.05 °C·in²/W thermal resistance → if your thermal model shows adequate headroom for HT-07006’s higher resistance, the extra isolation margin is worth it

When to Choose HT-04503 Over HT-07006

• Working voltage stays below 480 VAC and thermal budget is tight → HT-04503’s lower thermal resistance (0.05 vs 0.11 °C·in²/W) delivers meaningfully better junction temperature performance
• Low-voltage, high-power LED applications → HT-04503 or even HPL-03015 provides better thermal performance for the voltage levels involved
• Every degree of junction temperature matters in the thermal budget → the 2× difference in thermal resistance between HT-04503 and HT-07006 translates directly to component lifetime

Bergquist HT-07006 Applications: Where It Gets Specified

Three-Phase Motor Drives and Variable Frequency Drives

Three-phase motor drives represent one of the most demanding MCPCB application environments. The power section operates at 480 VAC three-phase (line-to-line), with IGBTs or silicon carbide MOSFETs switching continuously under load. Thermal management requirements are severe: IGBTs dissipate significant power in both conduction and switching losses, and the junction temperature directly determines device lifetime and safe operating area. At the same time, the 480 VAC working voltage means that the dielectric isolation between the IGBT collector/drain (at switching voltage) and the grounded aluminum heatsink must withstand not just the nominal voltage but transient overvoltages and hipot test requirements.

HT-07006 addresses this intersection: the 11 kVAC breakdown voltage provides safety margin above 480 VAC hipot requirements, while 2.2 W/m-K dielectric thermal conductivity efficiently removes IGBT junction heat into the aluminum substrate. In a direct-drive motor drive module, HT-07006 can replace both the PCB substrate and a separate thermal interface material between the board and heatsink — eliminating one thermal resistance in the stack entirely.

Mains-Isolated Power Converters and Industrial SMPS

Switch-mode power supplies for 400–600 VAC industrial input operate at mains potential on the primary side. The aluminum substrate of an MCPCB is typically grounded or at enclosure potential, making the dielectric the isolation barrier between the hazardous mains circuit and the chassis. IEC 61558 (safety of transformers) and IEC 62477 (safety requirements for power electronic converter systems) require the isolation to withstand both operating conditions and test voltages derived from the working voltage class. HT-07006’s 11 kVAC isolation, CTI 600 tracking resistance, and UL 94 V-0 flammability rating satisfy the typical safety certification requirements for EN/IEC standards in industrial power converters.

Solar Inverters and Grid-Tied Power Electronics

Utility-scale and commercial solar inverters operate at string voltages that can reach 1000–1500 VDC on the DC bus, with the AC output side at 400–600 VAC three-phase. Power density in modern inverter designs is high — kW/liter figures that would have been impossible a decade ago are now standard, with the thermal substrate as one of the critical enablers. HT-07006 is listed as a recommended application in the Bergquist datasheet for solar receiver applications. The combination of high breakdown voltage for the DC bus isolation, high thermal conductivity for dense power components, UL-certified operating temperature for outdoor enclosure environments, and RoHS compliance for international installation markets fits the solar inverter application profile closely.

Solid-State Relays and Contactors

High-power solid-state relays (SSRs) controlling industrial machinery typically switch 480 VAC three-phase loads at currents from a few amps to hundreds of amps. The SCR or TRIAC power elements in these relays generate continuous thermal losses that must be removed through the substrate. SSR manufacturers specify HT-07006 when the combination of high working voltage and high continuous thermal load exists simultaneously. The 325°C solder limit rating also enables AuSn die attachment, which gives better thermal resistance and reliability at elevated temperatures than standard solder systems.

High-Reliability LED Assemblies in Industrial and Automotive Contexts

While HPL-03015 is Bergquist’s highest-performance dielectric for LED applications at low voltage, HT-07006 is specified for “high reliability LED applications” where operating in industrial or automotive environments requires elevated temperature ratings (140°C UL RTI) alongside thermal management. Automotive LED headlight driver assemblies, industrial machine vision illuminators, and UV curing LED arrays that operate continuously at elevated ambient temperatures with mains-referenced circuitry are examples where HT-07006’s combination of thermal performance and electrical isolation adds value over lower-rated MCPCB materials.

Heat-Rails in Telecom and Avionics

The “heat-rail” is a configuration where an MCPCB substrate simultaneously serves as the circuit interconnect and as a structural thermal conduction rail, transferring heat from component mounting points along the rail length to a heatsink or cold plate at the rail ends. This configuration is common in 19-inch rack-mounted telecom and avionics electronics where convective cooling is limited. HT-07006’s higher breakdown voltage compared to HT-04503 makes it appropriate for heat-rail designs in telecom power distribution where bus voltages exceed 400 V.

HT-07006 Design Guide: Thermal Budget, Stackup, and Layout

Thermal Resistance Calculation and Junction Temperature Budget

The thermal resistance of HT-07006 (0.11 °C·in²/W) is the starting point for building a junction temperature budget for any power device mounted on the substrate. The full thermal chain from device junction to ambient typically looks like this:

Total thermal resistance (junction to ambient) = R_jc (device) + R_contact (solder) + R_substrate (HT-07006 dielectric) + R_base (aluminum spreading) + R_interface (substrate to heatsink) + R_heatsink

For a device with 1 cm² thermal pad:

• HT-07006 dielectric contribution: 0.11 °C·in²/W ÷ 0.155 in²/cm² = 0.71 °C/W per cm² device area

This is the thermal impedance value listed on the datasheet (0.70 °C/W), which was measured with a standard TO-220 test setup per Bergquist MET-5.4-01-40000 with 0.062″ aluminum substrate and 2 oz copper. For smaller devices with sub-1 cm² footprints, the thermal resistance per device increases proportionally — smaller thermal pad area means less dielectric cross-section removing heat.

Aluminum Substrate Thickness and Alloy Selection

Standard aluminum substrate options for HT-07006 boards follow the same specifications as other Thermal Clad products:

Substrate	Alloy	Thermal Conductivity	Typical Thickness	Best For
Aluminum	5052	~155 W/m-K	0.8–2.0 mm	General industrial, motor drives
Aluminum	6063	~200 W/m-K	1.0–3.0 mm	High heat spreading, chassis integration
Copper	1100	~385 W/m-K	0.5–2.0 mm	Maximum thermal, CTE-sensitive devices

For most HT-07006 applications in motor drives and industrial power converters, 1.5 mm (0.062″) 5052 aluminum is the standard starting point. Thicker substrates (2.0 mm or 3.0 mm) improve lateral heat spreading and mechanical rigidity, which matters in large-panel motor drive assemblies. Copper substrates are specified for applications where the CTE match to bare-die devices is critical or where lateral heat spreading needs maximizing, accepting the weight and cost premium.

Copper Circuit Layer Weight and Current Capacity

Copper Weight	Thickness	Approx. Current (1 cm trace, 10°C rise)	Notes
1 oz (35 µm)	35 µm	~3.5 A	Signal and low-current power
2 oz (70 µm)	70 µm	~5.0 A	Standard for most HT-07006 power designs
3 oz (105 µm)	105 µm	~6.5 A	Motor drive bus bars, high-current paths
4 oz (140 µm)	140 µm	~8.0 A	Heavy copper for bus bar replacement

Heavy copper on HT-07006 substrates requires adjusted etching processes for trace sidewall profile control, and may require double-pass solder mask printing. Current capacity increases sub-linearly with copper weight due to I²R heating — verify with IPC-2221 current capacity tables or thermal simulation for critical current-carrying traces.

High-Voltage Layout Rules for HT-07006 Designs

Working with an 11 kVAC substrate doesn’t eliminate the need for proper PCB-level clearance and creepage design. The substrate provides vertical isolation, but horizontal clearance between conductors at different potentials still follows IEC 60664 creepage and clearance requirements:

For 600 VAC working voltage, CTI Group I material (CTI 600, which HT-07006 achieves), Pollution Degree 2: minimum creepage distance is approximately 3.2 mm under IEC 60664-1. For 1000 VDC, the creepage requirement is approximately 4.5 mm. These are trace-to-trace, trace-to-edge, and trace-to-via distances that the PCB designer must implement — the substrate dielectric strength does not substitute for horizontal spacing.

Bergquist’s selection guide recommends a minimum edge-to-conductor distance appropriate to the design’s voltage class, and suggests a 45° chamfer on board edges where edge connectors are used. For applications expected to exceed 480 VAC working voltage, confirm that your specific design’s test voltage and hipot requirements are met with an appropriate safety factor against the 11 kVAC specification — avoid designing with < 2× safety margin between proof test voltage and material breakdown rating.

Through-Hole and Via Design on HT-07006 MCPCB

The aluminum base of an HT-07006 MCPCB is at a defined potential (typically chassis ground) and must be isolated from all plated circuit features that pass through it. For through-holes in aluminum-substrate HT-07006 boards:

Minimum punched non-plated through-hole diameter is 0.030″ (0.76 mm). For plated vias that pass through the aluminum substrate, the standard approach is to drill an oversized hole in the metal (typically 2× the final via diameter), fill the oversized cavity with insulating epoxy resin, cure fully, then drill the final via size through the epoxy fill, followed by standard copper plating. This isolation plug must maintain its integrity through thermal cycling. Most HT-07006 designs favor surface-mount power devices specifically because through-hole isolation adds process complexity and potential reliability risk at high voltages.

Surface Finish Recommendations for HT-07006 Applications

Surface Finish	Application	Notes
Lead-Free HASL	Standard SMT assembly, cost-sensitive designs	Good for larger pads; less suited to fine pitch
ENIG (Electroless Nickel / Immersion Gold)	Wire bonding, fine pitch, AuSn solder, long shelf life	Required for AuSn eutectic die attach at 325°C
OSP (Organic Solderability Preservative)	Immediate assembly in controlled production	Limited shelf life; not suitable for storage
ENEPIG	Advanced wire bonding with gold wire	Nickel barrier prevents gold embrittlement

For high-reliability HT-07006 applications where the 325°C AuSn solder capability is being used, ENIG is standard. For industrial motor drive assemblies using standard SAC305 reflow, lead-free HASL provides a cost-effective finish with adequate solderability.

HT-07006 vs FR-4 and Other Substrate Materials: The Numbers

Substrate Type	Thermal Conductivity	Thermal Resistance (per cm² device)	Voltage Isolation	Max Temp
Standard FR-4 (1.5mm)	0.25 W/m-K	~6.0 °C/W	Limited	130°C Tg
High-Tg FR-4 (1.5mm)	0.30 W/m-K	~5.0 °C/W	Limited	170°C Tg
Generic MCPCB (1.0 W/m-K dielectric)	~1.0 W/m-K	~0.6 °C/W	Varies	Varies
Bergquist MP-06503	1.3 W/m-K	0.09 °C·in²/W	8.5 kVAC	130°C RTI
Bergquist HT-04503	2.2 W/m-K	0.05 °C·in²/W	8.5 kVAC	140°C RTI
Bergquist HT-07006	2.2 W/m-K	0.11 °C·in²/W	11 kVAC	140°C RTI
Bergquist HT-09009	2.2 W/m-K	0.16 °C·in²/W	20 kVAC	150°C RTI
DBC (Direct Bond Copper on AlN)	~170 W/m-K (AlN)	Very low	Very high	200°C+

DBC on aluminium nitride is the only approach that outperforms Thermal Clad for both thermal and electrical performance simultaneously — but at substrate costs that are typically 10–30× higher and with the brittleness and process constraints of ceramic. For the cost bracket that MCPCB occupies, HT-07006 represents a well-optimized solution for the 480–600 VAC operating range.

Storage and Handling of Bergquist HT-07006 Substrates

The HT-07006 datasheet (March 2019, Henkel) specifies optimal storage conditions as 5–25°C with a 12-month shelf life from date of manufacture in unopened containers. In practice:

Store panels flat on a level surface to prevent warping under their own weight. Keep panels away from direct UV light and solvent fumes that can affect the epoxy dielectric. For high-humidity environments, desiccants or controlled-humidity storage cabinets are appropriate to prevent moisture uptake into the dielectric. Do not store cut panels in contact with ferrous metal surfaces that can cause surface contamination of the copper circuit side. Track production lot dates and implement first-in, first-out (FIFO) inventory management — shelf life management is important for consistent lamination and peel strength performance when panels are bonded or processed downstream.

Useful Resources for Bergquist HT-07006 Design and Procurement

Resource	What You’ll Find	Link
Bergquist HT-07006 Official Datasheet (Henkel/mclpcb PDF)	Complete thermal, electrical, mechanical, and agency rating specifications	mclpcb.com (PDF)
Bergquist HT-04503 Datasheet	Comparison reference: 3 mil HT dielectric for lower-voltage, maximum thermal performance	mclpcb.com (PDF)
Bergquist Thermal Clad Selection Guide	Complete family comparison, dielectric selection guide, fabrication recommendations, and application guidance	Digikey (PDF)
Henkel Electronics Product Portal	Current Thermal Clad documentation, SDS (Safety Data Sheets), and technical support contacts	henkel.com/electronics
IPC-2221 Generic Standard on PCB Design	Design rules for current capacity, clearance, and layout applicable to MCPCB	ipc.org
IEC 60664-1 Insulation Coordination	Creepage and clearance requirements for HV power electronics designs	iec.ch
ASTM D5470 Standard	Thermal conductivity test method cited in HT-07006 datasheet	astm.org
Digikey Product Listing	Bergquist Thermal Clad stock, pricing, and order quantities	digikey.com — Bergquist

FAQs: Bergquist HT-07006 MCPCB

Q1: What is the main reason to choose HT-07006 over HT-04503, and what performance do I give up by making that switch?

The primary reason to choose HT-07006 over HT-04503 is higher working voltage. HT-07006 provides an 11 kVAC breakdown voltage versus 8.5 kVAC for HT-04503, and Bergquist explicitly describes HT-07006 as featuring “even higher dielectric breakdown characteristics than HT-04503.” For mains-voltage designs above 480 VAC — three-phase industrial power, 600 VAC bus systems, high-voltage solar inverters — HT-07006 provides more comfortable safety margin above hipot test requirements. The performance tradeoff is thermal resistance: HT-07006’s 0.11 °C·in²/W versus HT-04503’s 0.05 °C·in²/W means each watt dissipated by a component produces 2.2× more temperature rise across the HT-07006 dielectric. If your thermal budget can absorb that difference, the additional isolation margin HT-07006 provides is worth it. If you’re running close to maximum junction temperature with HT-04503, moving to HT-07006 will push you over budget.

Q2: Why does HT-07006 have lower capacitance (43 pF/cm²) than HT-04503 (85 pF/cm²) despite having the same dielectric material?

Capacitance scales inversely with dielectric thickness — C = ε₀ × εᵣ × A / d, where d is dielectric thickness. Since HT-07006 has twice the dielectric thickness of HT-04503 (6 mil vs 3 mil) with the same dielectric constant (Dk = 7), the capacitance is exactly halved: 85 pF/cm² × (3/6) = 42.5 pF/cm², which rounds to the 43 pF/cm² published value. This lower capacitance has a practical benefit in high-frequency power conversion: the capacitive coupling between the circuit layer (at switching potential) and the aluminum base (at chassis ground) creates a common-mode current path. Lower substrate capacitance means less common-mode EMI injection into the chassis and lower common-mode filtering requirements in the EMI filter design. In motor drive and solar inverter applications where conducted EMI compliance to EN 55011 or CISPR 11 is required, the lower substrate capacitance of HT-07006 versus HT-04503 can simplify filter design.

Q3: Is HT-07006 approved for use in safety-certified products, and what certifications does it carry?

Yes — HT-07006 carries the following agency certifications documented in the official datasheet: UL 94 V-0 flammability rating, UL 746B Relative Thermal Index (RTI) of 140°C (both electrical and mechanical), and UL 796 solder limit rating of 325°C/60 seconds. The Comparative Tracking Index (CTI) of 600 per IEC 60112 places it in Material Group I — the highest tracking resistance category, which is recognized by IEC 60664 insulation coordination standards for determining creepage distance requirements. Bergquist’s manufacturing facilities hold ISO certification and UL recognition. For product submissions to UL, TÜV, VDE, or other safety certification bodies, confirm with your certification engineer that the Bergquist file numbers and recognition certificates align with your product’s standard requirements.

Q4: Can HT-07006 be used as the sole isolation between mains voltage and chassis ground in an end product, without any additional creepage or clearance provisions?

No — the substrate dielectric breakdown voltage of 11 kVAC is the intrinsic material performance under ideal conditions (clean, flat, defect-free material), not a replacement for system-level insulation coordination. In an end product, the complete isolation system must satisfy IEC 60664-1 (or equivalent) for working voltage, overvoltage category, and pollution degree, which determines both the required clearance (through-air distance) and creepage (along-surface distance). HT-07006 contributes the solid insulation component of that system, but horizontal clearances between circuit conductors and the board edge (where the metal substrate is exposed), between high-voltage traces and chassis-referenced features, and between circuit pads and via isolations all require separate layout and spacing provisions. Think of HT-07006 as providing the vertical isolation — your PCB layout provides the horizontal isolation. Both are needed for a properly certified design.

Q5: How do I specify HT-07006 to a PCB fabricator, and what are the key parameters to include in the drawing notes?

When specifying HT-07006 for fabrication, include the following on your assembly drawing or fabrication notes: (1) Base material: Bergquist Thermal Clad HT-07006 (6 mil dielectric) — do not allow generic substitution without prior approval; (2) Metal substrate: specify alloy and thickness, e.g., 5052 aluminum, 1.5 mm; (3) Copper weight: 1 oz, 2 oz, or 3 oz — specify which is the circuit foil; (4) Surface finish: ENIG, HASL-LF, OSP, or as required by assembly process; (5) Solder mask: white (LED/reflectivity applications) or black/green as required; (6) Hipot test voltage: specify the routine test voltage and dwell time your product requires; (7) IPC class: Class 2 or Class 3 depending on application reliability requirements. Also notify the fabricator that the metal substrate through-holes require insulating via plug fill before drilling if your design includes plated through-vias, and confirm their experience specifically with Bergquist Thermal Clad materials before committing production.

Conclusion

The Bergquist HT-07006 occupies a specific and well-defined position in high-power electronics design: it’s the substrate of choice when a design needs both high-temperature MCPCB thermal performance and electrical isolation rated for operation above 480 VAC. The 11 kVAC breakdown voltage, CTI 600 (Material Group I) tracking resistance, 2.2 W/m-K dielectric thermal conductivity, 150°C Tg, 140°C UL RTI, and AuSn solder compatibility address the simultaneous requirements of industrial motor drives, mains-isolated power converters, solar inverters, solid-state relays, and high-reliability LED assemblies in a way that no combination of FR-4 plus separate thermal interface material can match.

The tradeoff is straightforward and quantified: HT-07006’s 0.11 °C·in²/W thermal resistance is 2.2× higher than HT-04503’s 0.05 °C·in²/W. If your design’s thermal budget can accommodate that difference in exchange for 11 kVAC isolation instead of 8.5 kVAC, HT-07006 is the right specification. Build that tradeoff calculation into your thermal model early, cross-reference the 11 kVAC breakdown voltage against your specific hipot test requirements with an appropriate safety factor, verify creepage and clearance compliance separately in your PCB layout, and you have a substrate platform that can carry a high-power design through to production without thermal or electrical reliability surprises.