Complete datasheet and design guide for the Bergquist CML-11006 ceramic multi-layer PCB — specs, thermal performance, layout rules, assembly notes, and FAQ.

If you’ve spent any time sourcing materials for high-power or high-isolation PCB designs, you’ve probably bumped into the Bergquist Thermal Clad lineup. The Bergquist CML-11006 sits in a specific niche within that family — it’s the ceramic multi-layer (CML) dielectric variant engineered for applications where both elevated voltage isolation and strong thermal performance need to coexist. This guide walks through the key electrical and thermal specs, design considerations, assembly notes, and practical usage advice from an engineer’s perspective.

What Is the Bergquist CML-11006?

The Bergquist CML-11006 is a Thermal Clad Insulated Metal Substrate (IMS) material featuring a ceramic-filled multi-layer dielectric. The product code itself tells you a lot: “CML” stands for Ceramic Multi-Layer, “110” references the thermal impedance characteristic, and “06” refers to the 6-mil (150 µm) dielectric thickness. It’s part of Bergquist’s broader Thermal Clad portfolio, which was developed as a thermal management solution for watt-dense surface-mount applications where conventional FR-4 boards simply can’t keep up.

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.

The CML-11006 specifically targets applications that need multi-layer dielectric construction — a key differentiator from single-layer Thermal Clad variants. The multi-layer build increases dielectric thickness and breakdown voltage while preserving reasonable thermal conductivity, making it a go-to choice for applications in the 500–1000V operating range.

Bergquist CML-11006 Key Specifications

The table below summarizes the core performance parameters for the Bergquist CML-11006 based on the Thermal Clad Selection Guide. Note that the CML designation indicates the ceramic multi-layer dielectric formulation:

Thermal & Electrical Performance Table

Parameter	CML-11006	HT-04503	MP-06503	HT-07006
Dielectric Thickness	6 mil / 150 µm	3 mil / 75 µm	3 mil / 75 µm	6 mil / 150 µm
Thermal Conductivity	~1.3 W/m·K	2.2 W/m·K	1.3 W/m·K	2.2 W/m·K
Thermal Impedance (°C·in²/W)	~0.11	0.05	0.09	0.07
Dielectric Constant (Permittivity)	~6	7	6	7
Proof Test (VDC)	>2500	1500	1500	2500
Breakdown Voltage (kVAC)	>11	6.0	8.5	11.0
Glass Transition Temperature (°C)	90	150	90	150

Engineering Note: The CML-11006’s multi-layer dielectric construction is the critical distinction. By stacking the ceramic-filled layers, you get a significantly higher proof voltage capability compared to a single-layer 6-mil dielectric — important when designing for reinforced insulation requirements in IEC 60950 or IEC 62368-1 compliant products.

Physical & Construction Specs

Parameter	CML-11006 Value
Dielectric Type	Ceramic polymer multi-layer blend
Nominal Dielectric Thickness	0.006 in (150 µm)
Copper Foil Range	1 oz to 10 oz (35–350 µm)
Standard Base Metal	Aluminum (1.6 mm / 0.062 in typical)
Base Metal Options	Copper also available
UL Certification	Yes (lab certified)
RoHS Compliance	Yes
Manufacturing Standard	ISO 9001:2000

Understanding the Multi-Layer Ceramic Dielectric

The technology of Thermal Clad resides in the dielectric layer. It is the key element for optimizing performance in your application. The dielectric is a proprietary polymer/ceramic blend that gives Thermal Clad its excellent electrical isolation properties and low thermal impedance.

What makes the CML series different from other Thermal Clad grades is the multi-layer structure of that dielectric. While products like the MP-06503 use a single homogeneous dielectric layer, the CML-11006 bonds multiple ceramic-filled dielectric layers together. The result is two important engineering benefits:

Higher defect tolerance. Any micro-void or inclusion in a single-layer dielectric creates a direct breakdown path. With multiple layers, a defect in one layer is blocked by the intact layers on either side. This is particularly relevant for HiPot testing and long-term field reliability in AC line-connected products.

Improved isolation voltage. For applications with an expected voltage over 480 Volts AC, Bergquist recommends a dielectric thickness greater than 0.003″ (75µm). The CML-11006 at 150 µm multi-layer construction exceeds this recommendation and is well-suited for 480 VAC industrial or 600 VDC bus applications.

The ceramic filler helps to boost thermal conductivity. High-frequency applications need the best dielectric material. In the CML-11006, the ceramic loading is balanced to give acceptable thermal performance without sacrificing the dielectric integrity that multi-layer construction provides.

Three-Layer Board Architecture

Thermal Clad is a unique, three-layered system comprised of: a Circuit Layer (the printed circuit foil with thickness of 1oz to 10oz / 35–350µm in standard Thermal Clad); a Dielectric Layer (which offers electrical isolation with minimum thermal resistance, the multi-layer dielectric bonds the base metal and circuit metal together and has UL recognition); and a Base Layer (often aluminum, but other metals such as copper may also be used, with the most widely used base material thickness being 0.062 in / 1.6mm in aluminum).

For the CML-11006 specifically, that dielectric layer is where most of the engineering magic — and most of the design constraints — live.

Choosing the Base Metal for CML-11006

When selecting the base metal for a Bergquist CML-11006 board, the primary tradeoff is thermal conductivity versus cost and machinability:

Base Metal	Thermal Conductivity	Typical Use Case
Aluminum (6061)	~160 W/m·K	Cost-sensitive, LED drivers, consumer power
Copper	~390 W/m·K	Highest heat spreading, industrial power converters
Aluminum (1100 series)	~220 W/m·K	Moderate performance with better formability

Aluminum at 1.6 mm is the default and handles the vast majority of power electronics applications. If you’re designing a high-density motor drive or DC-DC converter pushing serious watt density, the copper base option is worth the cost premium.

Thermal Performance: What the Numbers Actually Mean

The thermal impedance value for the CML-11006 is approximately 0.11 °C·in²/W. That sounds abstract, but here’s how to use it in practice.

Thermal impedance in °C·in²/W tells you the temperature rise across the dielectric per watt of heat per unit area. To get the actual junction-to-board-back temperature drop through the dielectric:

ΔT = Impedance × Power / Area

For a 1 in² footprint with 10W dissipation:

ΔT = 0.11 × 10 / 1 = 1.1°C across the dielectric

Lower thermal impedance results in lower junction temperatures. The lower the thermal impedance, the more efficiently heat travels out of the components.

This is why the CML-11006 competes favorably against thick ceramic substrates. Direct-bonded copper (DBC) on alumina has very good thermal performance but is brittle and expensive. The CML-11006 gives you a mechanically robust metal substrate with a thermally competitive ceramic-filled dielectric — at standard PCB fabrication costs.

Thermal Performance vs. FR-4

Material	Thermal Conductivity	Relative Heat Dissipation Efficiency
Standard FR-4	0.25 W/m·K	Baseline (poor)
MP-06503 (single layer)	1.3 W/m·K	~5× better than FR-4
CML-11006 (multi-layer)	~1.3 W/m·K	~5× better than FR-4
HT-04503	2.2 W/m·K	~9× better than FR-4
Aluminum substrate (bare)	160 W/m·K	— (base layer, not dielectric)

The CML-11006 isn’t the thermal champion in the Thermal Clad lineup — that goes to the HT or HPL grades. But it delivers a reasonable thermal path while its multi-layer isolation is the real design driver.

Design Considerations for Bergquist CML-11006 PCB Layouts

Trace and Clearance Guidelines

High thermal conductivity is relevant to your application when the thickness of the dielectric material is taken into consideration. Impedance to heat flow is proportional to the ratio of thickness to thermal conductivity.

For high-voltage designs on CML-11006, trace clearances on the top copper must be designed to the operating voltage, not just the dielectric capability. The board-level clearance on the copper surface is the most common failure mode — not the dielectric itself. Use IPC-2221 creepage and clearance tables as your baseline, and remember that the metal base on an IMS board may be connected to chassis ground in many designs, which creates a specific creepage path to consider.

Key layout rules for CML-11006 designs:

• Maintain copper-to-board-edge clearance of at least 0.5 mm minimum; 1.0 mm is safer for 500V+ designs
• Avoid sharp trace corners — use 45° or radiused bends to reduce E-field concentration at trace edges
• Keep high-power component pads large enough to spread heat effectively — don’t minimize pad size on MOSFETs or diodes just to save board space
• When designing multi-row LED strings, balance the thermal footprint across the board to avoid hot spots

Drilling and Routing CML-11006

Unlike standard FR-4, the CML-11006 has an aluminum or copper base layer. This requires carbide tooling for routing and drilling. Key notes:

• Use sharp, uncoated carbide drill bits — TiN coating can cause aluminum buildup and smearing
• Drill speeds should follow recommendations for metal-clad boards, not FR-4 parameters
• Depaneling is best done by V-score or CNC routing — tab-routed panels with perforated tabs can stress the dielectric at the break points on thicker base materials

Copper Weight Selection

The circuit layer is the printed circuit foil with thickness of 1oz to 10oz (35–350µm) in standard Thermal Clad.

For power electronics on CML-11006, 2 oz copper (70 µm) is a common starting point for moderate current designs. If you’re running bus bars or high-current traces for motor drives or converters above 20A, 3 oz or heavier copper is worth specifying. Heavier copper also improves the thermal spreading in the circuit layer itself, which is an additional benefit beyond the current-carrying improvement.

Assembly and Soldering Recommendations

Reflow Soldering

The CML-11006 is compatible with standard SMT reflow processes. A few practical notes:

• Peak reflow temperature: Standard 245–260°C SAC305 profile is acceptable; the aluminum base acts as a heat sink and may require a longer soak zone to bring the board to temperature uniformly
• Thermal mass: The metal substrate has higher thermal mass than FR-4, so ensure your oven profile accounts for slower ramp rates to temperature
• Flux residue: Chemical soak cleaning with Loncoterge or alcohol for 15 minutes is evaluated during qualification testing. Standard no-clean flux is acceptable for most designs; if you do clean, verify that your cleaning chemistry does not attack the dielectric edge if the board has been routed or scored

Component Mounting and Mechanical Fasteners

Thermal Clad is compatible with mechanical fasteners and is highly reliable. It can be used in almost every form-factor and fabricated in a wide variety of substrate metals, thicknesses and copper foil weights.

When mounting through-hole components or hardware to a CML-11006 board, use standard metalwork practices for the aluminum base — avoid over-torquing fasteners, which can cause the dielectric to delaminate locally around the hole. Thread-lock compounds compatible with aluminum are fine.

Qualification and Reliability Testing

New materials undergo a rigorous 12 to 18-month qualification program prior to being released to the market. In state-of-the-art laboratories and test facilities, Bergquist performs extensive testing on all their thermal materials for electrical integrity. Bergquist utilizes stringent development procedures outlined in Bergquist document #Q-6019. The lab facilities at Bergquist are UL certified and manufacturing facilities are ISO 9001:2000 certified.

For the CML-11006 specifically, the qualification test matrix covers:

Test	Condition
Thermal Bias Aging	125°C / 100V / 2000 hours
Temperature Cycling	500 cycles, -40°C to +150°C
Temp/Humidity/Bias	85°C / 85% RH / 100V / 2000 hours
Thermal Shock	Sand bath 300°C / 1 min
Solder Shock	230°C / 10 min
Breakdown Voltage	DC and AC
Peel Adhesion	Sequential aging

This kind of test rigor is one reason why the Bergquist Thermal Clad family has become a trusted baseline for industrial and automotive power electronics designs. The CML-11006’s multi-layer construction adds an additional margin in the breakdown voltage tests specifically.

Bergquist CML-11006 vs. Other Thermal Clad Grades: Which One to Use?

This is the question I see come up most often from engineers evaluating the Thermal Clad lineup:

Grade	Best For	Trade-off
CML-11006	High isolation voltage + moderate thermal	Lower thermal conductivity vs. HT grades
HT-04503	Highest thermal performance at 3 mil	Lower isolation voltage than CML
HT-07006	High thermal + high isolation at 6 mil	Single-layer dielectric; CML multi-layer offers higher breakdown margin
MP-06503	Cost-effective general purpose	Lowest thermal conductivity in the family
LTI-04503/06005	Lower Tg applications, cost-driven	Not suitable for high temperature environments
HPL-03015	Maximum thermal — LED street lighting	Thinnest dielectric, lowest isolation voltage

If your design operates above 480VAC or in an environment where reinforced insulation to chassis ground is required by your safety standard, the CML-11006 is the right starting point. If pure thermal performance is your driver and voltage isolation is modest, the HT-04503 or HT-07006 will serve you better.

Typical Applications for the Bergquist CML-11006

Due to the size constraints and watt-density requirements in DC-DC conversion, Thermal Clad has become the favored choice. It offers a variety of thermal performances, is compatible with mechanical fasteners and is highly reliable. Compact high reliability motor drives built on Thermal Clad have set the benchmark for watt-density.

The CML-11006 sees frequent use in:

Industrial Power Converters: AC-DC converters operating from 277VAC or 480VAC mains benefit from the CML’s higher isolation rating. The ceramic dielectric also performs well in environments where capacitive coupling between the power circuit and chassis needs to be minimized.

Motor Drive Inverters: Three-phase inverter bridges for BLDC and PMSM motor control where the intermediate DC bus runs at 400–800VDC. The CML-11006 provides the isolation headroom needed between the switching node copper and the aluminum heatsink base.

Solid State Relays: The implementation of Solid State Relays in many control applications calls for very thermally efficient, and mechanically robust substrates. Thermal Clad offers both. The material construction allows mounting configurations not reasonably possible with ceramic substrates. New dielectrics meet the high thermal performance expectations and can even out-perform existing ceramic-based designs.

High-Brightness LED Drivers: Where the LED driver operates from line voltage and the board must isolate the aluminum heatsink from live circuits while managing LED thermal load.

Automotive Power Electronics: EV onboard chargers (OBC) and DC-DC converters where high-voltage isolation to the vehicle chassis is a hard requirement.

Comparison with Alternative PCB Substrate Technologies

Engineers sometimes ask how CML-11006 compares to Arlon PCB materials or standard ceramic substrates. Here’s a practical comparison:

Technology	Thermal Conductivity	Isolation	Mechanical Durability	Relative Cost
Bergquist CML-11006	~1.3 W/m·K	Excellent (multi-layer)	High (metal base)	Moderate
Arlon IMS Materials	Varies (1–3 W/m·K)	Good	High (metal base)	Moderate
Direct Bond Copper (DBC) on Alumina	~24 W/m·K substrate	Excellent	Brittle, fragile	High
Standard FR-4	0.25 W/m·K	Basic	Good	Low
Aluminum Nitride (AlN) Ceramic	170–200 W/m·K	Excellent	Brittle	Very High

The CML-11006 sits in a sweet spot: it’s not trying to beat DBC or AlN on thermal performance, but it gives you a mechanically rugged, cost-manageable substrate with multi-layer isolation that’s difficult to achieve at comparable cost any other way.

Useful Resources and Datasheets

Engineers working with the Bergquist CML-11006 should keep the following references on hand:

Resource	Description	Link
Bergquist Thermal Clad Selection Guide	Complete dielectric comparison, design rules, assembly guidelines	Digikey PDF
Thermal Clad Selection Guide (TJK)	Updated version with full CML-11006 parameter table	TJK PDF
Bergquist HT-04503 Datasheet	Reference for high-performance HT dielectric specs	MCLPCB PDF
Bergquist MP-06503 Datasheet	Multi-purpose dielectric baseline datasheet	MCLPCB PDF
Bergquist HPL-03015 Datasheet	High-power LED dielectric specs	Suntechcircuits
IPC-2221 Design Standard	Clearance and creepage design rules	IPC.org
Henkel/Bergquist Product Page	Current product availability and ordering	Henkel Adhesives
RayPCB Bergquist Materials Overview	Practical guide to Bergquist material selection	RayPCB Article

Frequently Asked Questions About the Bergquist CML-11006

What does “CML” stand for in Bergquist CML-11006?

CML stands for Ceramic Multi-Layer — it describes the dielectric construction type. Unlike single-layer Thermal Clad dielectrics, the CML uses a stacked, multi-layer ceramic-filled polymer system to achieve higher breakdown voltage and better defect tolerance while maintaining acceptable thermal conductivity for power electronics use.

Can the Bergquist CML-11006 be used with copper base instead of aluminum?

Yes. While aluminum at 1.6 mm is the most common base metal, Bergquist Thermal Clad products including the CML-11006 are available on copper base. Copper provides roughly 2.4× better thermal spreading than aluminum but is heavier and more expensive. For extremely high watt-density converters where every degree of junction temperature matters, copper base CML-11006 is a legitimate option.

What is the maximum operating voltage for the Bergquist CML-11006?

The proof test voltage for the CML-11006 is above 2500 VDC, with AC breakdown exceeding 11 kVAC. In practice, operating voltages should be derated from these test values for long-term reliability. For 480 VAC industrial applications, the CML-11006 provides appropriate safety margin for reinforced insulation classifications when properly designed with adequate surface clearances.

Is the Bergquist CML-11006 compatible with lead-free solder processes?

Yes. Like the rest of the Bergquist Thermal Clad family, the CML-11006 is RoHS compliant and designed for lead-free assembly. Bergquist MP-06503 is lead-free solder compatible, eutectic AuSn compatible, and RoHS compliant and environmentally green. The CML-11006 carries the same compliance posture across the Thermal Clad lineup.

How does the Bergquist CML-11006 compare to direct bond copper (DBC) substrates?

DBC on alumina or aluminum nitride offers higher thermal conductivity through the substrate itself, but requires a ceramic carrier that is fragile, difficult to machine, and cannot be easily formed or routed. The CML-11006 on an aluminum base is mechanically robust, can be CNC routed to complex shapes, and can accommodate mounting hardware — advantages that often outweigh the thermal conductivity difference in real-world production designs. DBC remains the better choice in discrete power module packaging where thermal resistance through the substrate is the dominant constraint.

The Bergquist CML-11006 is a mature, well-qualified thermal substrate for engineers who need voltage isolation alongside thermal management — not one at the expense of the other. Its multi-layer ceramic dielectric is the defining characteristic that separates it from the rest of the Thermal Clad lineup, and understanding that distinction is the starting point for knowing whether it belongs in your next power electronics design.