Bergquist ML-11006 specifications, part number decoded, multi-layer IMS stack-up guide, and comparison with HT, HPL, and MP Thermal Clad dielectric grades for power electronics design.

If you’ve been designing insulated metal substrate (IMS) PCBs for any length of time, you’ve probably run into a familiar constraint: standard single-layer Thermal Clad works brilliantly for straightforward power LED and motor control boards, but the moment your design demands multiple signal layers, combined power and control routing, or true multilayer stack-up integration, the options narrow quickly. That’s where the Bergquist ML-11006 earns its place.

The ML-11006 is Bergquist’s thermally conductive, multi-layer capable dielectric — specifically the CML (Ceramic Multi-Layer) family — offered in prepreg form and engineered for engineers who need to combine the superior thermal management of IMS technology with the routing complexity of conventional multi-layer PCB construction. This article covers the ML-11006’s specifications, how the naming convention decodes, where it fits in the broader Bergquist product ecosystem, and how to decide whether it’s the right material for your next high-power, thermally demanding design.

Understanding the Bergquist Thermal Clad Dielectric Family

Before diving into the ML-11006 specifically, it’s worth establishing how it sits within Bergquist’s broader Thermal Clad product architecture.

Thermal Clad circuit board materials are available from The Bergquist Company in four different thermal conductivities: High Power Lighting (HPL), High Temperature (HT), Low Modulus (LM) and Multi-Purpose (MP). The CML — Ceramic Multi-Layer — family is the fifth key member of the dielectric lineup, specifically distinguished by its availability in prepreg form for multi-layer constructions.

CML is available in prepreg form, which is what fundamentally separates it from the other Thermal Clad grades. Where HT, MP, HPL, and LM are single-substrate laminates applied to a metal base, CML/ML-series dielectrics can be laminated between circuit layers in the same way conventional FR4 prepregs are used — making true multi-layer IMS constructions possible.

Thermal Clad substrates minimize thermal impedance and conduct heat more effectively and efficiently than standard printed wiring boards (PWBs). These substrates are more mechanically robust than thick film ceramics and direct bond copper constructions that are often used in these applications. Thermal Clad is a cost-effective solution which can eliminate components, allow for simplified designs, smaller devices and an overall less complicated production process.

Decoding the Bergquist ML-11006 Part Number

What the Naming Convention Tells You

Bergquist’s Thermal Clad product codes follow a structured naming format that encodes the dielectric family, thermal characteristics, and dielectric thickness directly in the part number. For ML-series products:

• ML = Multi-Layer dielectric family (CML ceramic multi-layer, prepreg form)
• 110 = Thermal conductivity designator (nominally ~1.1 W/m·K)
• 06 = Dielectric thickness in mils (6 mil / 152 µm)

Cross-referencing with the broader CML family within the Bergquist product range:

Part Number	Family	Dielectric Thickness	Nominal Thermal Conductivity	Form Factor
ML-09003	CML / Multi-Layer	3 mil (76 µm)	~0.9 W/m·K	Prepreg
ML-09006	CML / Multi-Layer	6 mil (152 µm)	~0.9 W/m·K	Prepreg
ML-11006	CML / Multi-Layer	6 mil (152 µm)	~1.1 W/m·K	Prepreg
ML-11009	CML / Multi-Layer	9 mil (229 µm)	~1.1 W/m·K	Prepreg

The ML-11006 sits in the middle of the family: thicker than the 3-mil variants (giving more voltage isolation margin), thinner than the 9-mil version (giving lower thermal impedance), and at the higher thermal conductivity tier within the 6-mil options.

Bergquist ML-11006 Key Technical Specifications

The ML-11006’s specification profile reflects its dual role as both a thermal management material and a multi-layer dielectric bonding film. Based on published Bergquist/TCLAD CML series data:

Thermal Properties

Property	ML-11006 Value	Test Method
Thermal Conductivity	~1.1 W/m·K	ASTM D5470
Dielectric Thickness	6 mil (152 µm)	—
Maximum Continuous Use Temperature	130°C	UL 746B
Glass Transition Temperature (Tg)	130°C	ASTM E1356
Lead-Free Solder Compatibility	Yes (288°C / 10s)	IPC TM-650

Electrical Properties

Property	Value	Test Method
Dielectric Thickness	6 mil (152 µm)	—
Dielectric Breakdown Voltage	>5 kVAC (typical)	ASTM D149
Dielectric Constant (εr)	~4.2–4.7 at 1 MHz	ASTM D150
Dissipation Factor	~0.02 at 1 MHz	ASTM D150
Volume Resistivity	>10⁹ MΩ·cm	ASTM D257
Surface Resistivity	>10⁹ MΩ/sq	ASTM D257

Mechanical and Compliance Properties

Property	Value
Peel Strength	≥5 lb/in (0.9 N/mm)
Flammability	UL 94V-0
RoHS Compliance	Yes
Halogen-Free	Yes
Water Absorption	<0.20%
Available Form	Prepreg (glass carrier)

Important: Always verify against the current Henkel/TCLAD technical data sheet before finalizing your design. Properties may vary with copper foil weight and lamination parameters.

What Makes the ML-11006 Distinctly a Multi-Layer Material

The Prepreg Form Factor Is the Key Differentiator

CML is the one exception because of its prepreg form — a glass carrier is needed for handling purposes. This single characteristic is what separates the ML family from every other Bergquist Thermal Clad grade. The glass carrier enables the CML dielectric to be handled, cut, and stacked exactly like conventional FR4 prepreg in a standard multilayer press cycle, without the handling challenges that a loose polymer/ceramic film would present in a production lamination environment.

Thermal Clad dielectric film is easy to laminate, simplifying the fabrication of advanced multi-layer circuit boards. By vertically stacking copper foils with glass-fiber-reinforced dielectric layers, we create complex circuit structures that deliver superior thermal conductivity, electrical isolation, and mechanical strength.

This architecture opens up a design space that single-layer IMS simply cannot address: high-power boards that also require dedicated control circuitry, isolated power rails on separate layers, or complex signal routing that a single-sided board cannot accommodate.

Thermal Conductivity in Context: Why 1.1 W/m·K Matters

An IMS PCB can be designed with a very low thermal resistance. If, for example, you compare a 1.60 mm FR4 PCB to an IMS PCB with a 0.15 mm thermal prepreg, you may well find the thermal resistance is more than 100 times that of the FR4 PCB.

Standard FR4 has a thermal conductivity of approximately 0.24 W/m·K. The ML-11006’s ~1.1 W/m·K represents roughly a 4.5× improvement in the dielectric layer itself — and because IMS construction uses a thin dielectric (6 mil vs. the 62-mil thickness of a typical FR4 board), the actual thermal impedance improvement at the system level is dramatically larger than the conductivity ratio alone suggests.

When selecting a material for an application, thermal impedance has to be taken into consideration. The thermal resistance (Rth) defines the interior thermal resistance of a material against a possible heat flow. The lower this value, the better the heat can be dissipated through the material.

For the ML-11006, the 6-mil dielectric thickness combined with 1.1 W/m·K conductivity gives a thermal impedance that is workable for moderate-power applications where the routing complexity of a multi-layer construction is more critical than achieving the absolute minimum thermal resistance.

Bergquist ML-11006 vs. Other Thermal Clad Dielectrics: Choosing the Right Grade

This comparison is where most engineers need to spend their time before finalizing a material specification.

Full Bergquist Thermal Clad Family Comparison

Dielectric Series	Thermal Conductivity	Dielectric Thickness Options	Max Temp (UL)	Multi-Layer Capable	Best Application
HPL (High Power Lighting)	2.2 W/m·K	3 mil	140°C	No	Power LED, maximum heat transfer
MP (Multi-Purpose)	1.7 W/m·K	3, 6 mil	130–140°C	No	General IMS, cost-effective
HT (High Temperature)	2.2 / 4.1 W/m·K	3, 6, 9 mil	140°C	No	High-temp, >480V, AuSn solder
LTI (Low Thermal Impedance)	3.0 W/m·K	3 mil	130°C	No	Tight thermal budget, LED
ML / CML (Multi-Layer)	~0.9–1.1 W/m·K	3, 6, 9 mil	130°C	Yes	Multi-layer power+control boards

The trade-off is explicit: the ML-11006 offers lower thermal conductivity than HPL, HT, or LTI grades in exchange for multi-layer lamination capability. This is a fundamental materials engineering constraint — the glass carrier required for prepreg handling introduces a glass content that slightly reduces thermal conductivity compared to the glass-free Bergquist dielectrics used in single-layer configurations.

Glass carriers degrade thermal performance which is why our dielectrics are glass-free. CML is the one exception because of its prepreg form — a glass carrier is needed for handling purposes.

Engineers who need both maximum thermal performance and multi-layer routing must evaluate whether a hybrid approach — using a high-conductivity single-layer dielectric on the thermally critical outer layer and ML-series prepreg for inner-layer bonding — can deliver the best of both.

ML-11006 vs. ML-11009: When to Go Thicker

Parameter	ML-11006	ML-11009
Dielectric Thickness	6 mil (152 µm)	9 mil (229 µm)
Thermal Impedance	Lower	Higher
Breakdown Voltage	~5–7 kVAC	~7–10 kVAC
Inter-Layer Isolation	Good	Better
Cost per Panel	Lower	Higher

Choose ML-11009 when your inter-layer isolation voltage requirements demand more headroom — for example, in multilayer boards where high-voltage bus layers and low-voltage control layers coexist in the same stack-up at voltages approaching or exceeding 480V AC. Choose ML-11006 when thermal impedance is the tighter constraint and your voltage levels are moderate.

Primary Application Areas for the Bergquist ML-11006

Multi-Layer Power + Control Boards

This is the canonical ML-series use case. Many modern power conversion designs require both high-current power switching circuitry and dedicated microcontroller or gate driver circuitry on the same board — functions that benefit from the thermal management of IMS construction but require at least two signal layers to route effectively.

Two-layer constructions can provide shielding protection and additional electrical routing capability. The ML-11006 enables this two-layer or multi-layer construction while maintaining the thermal management benefits of Thermal Clad technology throughout the stack-up.

Advanced LED Driver and Lighting Systems

By maintaining standard FR4 layouts, this solution streamlines the transition to improved thermal performance with IMS. The integration of Thermal Clad dielectric and base metal enhances heat dissipation, increases mechanical strength, boosts component reliability, and delivers effective EMI shielding.

High-specification architectural lighting, horticultural LED systems, and stadium lighting fixtures increasingly use multi-layer driver boards where LED power circuitry, PWM control circuits, and communication interfaces all share the same physical board. The ML-11006 allows this integration without abandoning the thermal advantages of IMS.

Automotive Power Electronics

Automotive-grade power modules — DC-DC converters, OBC (onboard charger) modules, and EV battery management units — demand multi-layer routing for signal integrity, EMC compliance, and functional safety circuit separation, while simultaneously managing significant thermal loads from switching devices. The ML-11006’s multi-layer capability makes it a practical substrate option for these hybrid-architecture boards.

Industrial Motor Controls and Inverters

Compact high-reliability motor drives built on Thermal Clad have set the benchmark for watt-density. For motor control designs where a dedicated power layer handles high-current IGBT or MOSFET circuits and separate signal layers manage encoder feedback, CAN bus communication, or gate drive logic, the ML-11006 provides the lamination chemistry to build that stack-up with integrated thermal management.

Satellite Systems and High-Reliability Electronics

Multi-layer thermal clad PCBs using CML-type dielectrics are found in satellite systems, atomic accelerators, heart monitors, and file servers — applications where the combination of dense circuit routing and reliable thermal management in a compact form factor justifies the material’s higher engineering effort and cost relative to conventional FR4.

Fabrication and Design Considerations for ML-11006 Multi-Layer IMS PCBs

Stack-Up Design with ML-11006 Prepreg

The ML-11006 is used as the bonding prepreg between circuit layers in a multi-layer IMS stack-up. A typical two-signal-layer IMS construction using ML-11006 would be:

Layer 1 (Top): Circuit copper (1–3 oz) Bond Layer: ML-11006 prepreg (6 mil) Layer 2 (Bottom circuit): Circuit copper (1–3 oz) IMS Dielectric: ML-11006 or single-layer Thermal Clad Base Metal: Aluminum 5052/6061 or Copper C1100

When paired with a copper base plate, blind vias can be implemented to create conductive pathways between circuit layers and the base — boosting thermal conduction and electrical performance.

Base Metal Selection

Copper and aluminum Thermal Clad is normally purchased in one of the standard-gauge thicknesses. Non-standard thicknesses are also available. For ML-11006 multi-layer applications, 1.5 mm aluminum (5052 or 6061 alloy) is the most common base metal selection, offering a practical balance of thermal spreading, mechanical rigidity, weight, and machinability. Copper base is specified for the most thermally demanding designs.

Copper Foil Weight and Current Carrying Capability

The advantage of Thermal Clad is that the circuit trace interconnecting components can carry higher currents because of its ability to dissipate heat due to I²R loss in the copper circuitry.

For ML-11006 multi-layer builds, 1 oz and 2 oz copper are most common in inner layers. Heavier copper (3–6 oz) on outer power layers improves current carrying and heat spreading but increases lamination pressure requirements and demands verification with your fabricator’s qualified process parameters.

HiPot Testing Protocol

Any micro-fractures, delaminations or micro-voids in the dielectric will breakdown or respond as a short. Due to the capacitive nature of the circuit board construction, it is necessary to control the ramp up of the voltage to avoid nuisance tripping of the failure detect circuits in the tester and to maintain effective control of the test.

For ML-11006 multi-layer IMS boards, all completed assemblies should undergo hi-pot dielectric breakdown testing. Use a controlled voltage ramp of 100–500 V/s rather than step-application. Test voltage should be specified per IPC or UL requirements for your end application — typically 1.5–2× the working voltage.

Solder Mask and Surface Finish Compatibility

ML-11006 boards process through standard SMT solder mask and surface finish steps. ENIG (Electroless Nickel Immersion Gold) and HASL LF (Lead-Free Hot Air Solder Leveling) are both widely used. For applications requiring maximum thermal performance at the component pad interface, ENIG is preferred as it provides the flattest surface for SMD component solder joints.

Bergquist ML-11006 vs. Competing Multi-Layer IMS Dielectrics

Material	Supplier	Thermal Conductivity	Multi-Layer Form	Dielectric Thickness	Notes
ML-11006 (CML)	Bergquist/TCLAD	~1.1 W/m·K	Prepreg	6 mil	Glass carrier, FR4-like process
ML-09006 (CML)	Bergquist/TCLAD	~0.9 W/m·K	Prepreg	6 mil	Lower cost, same form factor
Isola IS450	Isola	1.0 W/m·K	Prepreg/Laminate	Various	Mixed-layer multilayer capable
Arlon PCB 92ML	Arlon	~1.5–2.0 W/m·K	Laminate/Prepreg	Various	Military/aerospace grade
Ventec VT-4B2	Ventec	1.0 W/m·K	Prepreg	4 mil	IMS, halogen-free option
Standard FR4	Various	~0.24 W/m·K	Prepreg standard	Various	No IMS thermal benefit

A Note on Arlon Multi-Layer IMS Materials

Arlon PCB materials, particularly the 92ML series, are worth evaluating as an alternative when your project has strict military or aerospace qualification requirements. Arlon’s heritage in demanding environmental applications means their materials carry well-documented reliability data across temperature cycling, humidity exposure, and vibration profiles that some commercial IMS datasheets don’t fully address. For commercial industrial projects, the ML-11006 remains the most widely available and fabricator-qualified choice.

Useful Resources for Bergquist ML-11006 and Multi-Layer IMS Design

Official Documentation

• TCLAD Product Page — Board-Level Solutions — Current Henkel/TCLAD product information, multi-layer IMS capability overview, and contact for technical support
• Bergquist Thermal Clad Selection Guide (via Digikey) — The most comprehensive engineering reference for the full Thermal Clad product family, including CML/ML-series dielectrics, stack-up configurations, and assembly guidelines
• Bergquist MP-06503 TDS Reference (MCLPCB) — Representative TDS format for Bergquist Thermal Clad grades; ML-series format follows the same structure

Standards and Testing

• IPC-4101: Specification for Base Materials for Rigid and Multilayer Printed Boards — Qualification standard for laminate and prepreg materials
• ASTM D5470: Thermal Transmission Properties of Thin Thermally Conductive Solid Electrical Insulation — Primary thermal conductivity test method cited in Bergquist datasheets
• IPC-2221: Generic Standard on Printed Board Design — Design rules covering conductor spacing, voltage clearance, and current carrying capacity applicable to ML-11006 designs

Distributor and Supply

• Digi-Key Bergquist Thermal Substrates — Search “Bergquist TCLAD” for stocked IMS panels; ML-series may require inquiry for specific configurations
• Mouser Bergquist Products — Alternative stocking distributor with cross-reference capability
• NCAB Group IMS PCB Specifications — Useful third-party resource for IMS design rules and fabricator specifications

5 Frequently Asked Questions About Bergquist ML-11006

Q1: What exactly does the “ML” prefix in ML-11006 mean, and is it the same as CML?

Yes, ML and CML refer to the same product family. CML stands for Ceramic Multi-Layer, and the ML product code prefix is used in the commercial part numbering system. The “ML” in ML-11006 indicates this is a multi-layer capable dielectric available in prepreg form — with a glass carrier added specifically to enable handling and lamination in standard multilayer press equipment. The numbers that follow (110 for thermal conductivity, 06 for 6-mil thickness) encode the key performance parameters. When ordering through distributors or discussing with fabricators, ML-11006 and CML-11006 refer to the same material.

Q2: Can the ML-11006 be used as a drop-in replacement for standard FR4 prepreg in an existing multilayer design?

Partly, with caveats. The ML-11006 is physically compatible with standard multilayer lamination equipment and processes — that’s the whole point of the glass carrier. However, several design parameters will differ: the Tg of 130°C is on the lower end compared to modern high-Tg FR4 grades (150–180°C), so thermal cycling requirements need to be evaluated. The dielectric constant (~4.2–4.7) is similar to FR4, so impedance-controlled traces won’t change dramatically. The key benefit of swapping in ML-11006 is the thermal conductivity improvement — roughly 4–5× over standard FR4 — which enables higher-power components to be mounted without a separate heatsink or with a smaller metal base. Run your thermal model before and after the substitution to quantify the actual temperature reduction at your critical components.

Q3: What is the typical breakdown voltage of the ML-11006, and is it suitable for 480V AC industrial applications?

The ML-11006 at 6-mil dielectric thickness provides a typical dielectric breakdown voltage in the range of 5–7 kVAC. For applications with an expected voltage over 480 Volts AC, Bergquist recommends a dielectric thickness greater than 0.003″ (75µm). At 6 mil (152 µm), the ML-11006 is well above that minimum threshold and is generally suitable for 480V AC applications with appropriate creepage and clearance design. For applications at or above 690V AC, or any design subject to frequent inductive switching transients, evaluate the ML-11009 (9 mil) for additional voltage margin.

Q4: How does the ML-11006 compare to using thermal vias in a standard FR4 multilayer board?

Both approaches improve thermal performance over basic FR4, but they address the problem differently and at different performance levels. Thermal vias in FR4 can reduce junction-to-board thermal resistance by 20–40% depending on via density and copper weight — meaningful, but still limited by FR4’s poor bulk thermal conductivity (~0.24 W/m·K). The ML-11006 replaces FR4 prepreg with a 1.1 W/m·K dielectric, achieving roughly 4–5× better conduction through the bonding layers, independent of via drilling. In standard FR4 products, it is very difficult to dissipate a large amount of heat away from components. For designs where component power density is moderate (under ~3–5 W/cm²), thermal vias in FR4 may be sufficient and cheaper. Above that density, or where a metal base plate is part of the thermal design, ML-11006 in a true IMS construction delivers performance that thermal vias in FR4 cannot match.

Q5: Are there fabricators outside of Bergquist’s direct network who can process ML-11006 boards?

Yes. ML-11006 is among the Bergquist materials that several qualified Asian and Western PCB manufacturers can process, though availability varies by region. When qualifying a fabricator for ML-11006 production, confirm specifically that they have experience laminating CML prepreg in a multi-layer press cycle (not just single-layer IMS), that they can perform hi-pot dielectric testing on completed assemblies, and that their solder mask and surface finish processes are qualified on TCLAD substrates. Ask for previous production lot data or reliability test results if your application is safety-critical. Lead times for ML-series material are typically 4–8 weeks from non-stocking fabricators, so factor this into your program schedule.

Final Thoughts: Is the Bergquist ML-11006 Right for Your Design?

The ML-11006 answers a specific engineering question: how do you get the thermal management benefits of Bergquist Thermal Clad IMS technology into a design that genuinely needs more than one circuit layer?

If your design is a straightforward single-layer power LED board or a simple motor control circuit, the ML-11006 is probably not your best choice — the HPL, LTI, or HT grades offer better thermal conductivity and lower cost for those applications. But if you’re designing a multi-layer power electronics board where combining power and control layers on a thermally managed substrate is an engineering requirement rather than a preference, the ML-11006 is exactly the material the Bergquist product family developed for that scenario.

The prepreg form factor, multi-layer lamination capability, glass carrier handling, UL 94V-0 compliance, RoHS compliance, and reasonable thermal conductivity improvement over FR4 make it a practical and well-characterized choice for the specific intersection of “needs multiple signal layers” and “needs serious thermal management” that increasingly defines modern power electronics design.

For multi-layer IMS PCB fabrication using Bergquist ML-11006, TCLAD, and other thermally conductive dielectrics, work closely with your fabricator’s engineering team during stack-up development to ensure compatible lamination processes and qualified hi-pot testing procedures.