Bergquist MCPCB for power electronics: how Thermal Clad solves thermal management in motor drives, DC/DC converters, and inverters — with grade selection tables and design rules.

Power electronics keeps pushing in one direction — more watts in less space. Motor drives are shrinking while their current ratings climb. Inverters are moving to SiC and GaN, which switch faster and run hotter than the silicon IGBTs they replace. DC/DC converters are expected to hit efficiencies that leave almost no room for thermal error. Every one of these trends increases the thermal load on the PCB substrate, and that is exactly where MCPCB power electronics design begins to separate the successful designs from the ones that come back as warranty failures.

Bergquist Thermal Clad, now under Henkel’s Electronic Materials division, has been the benchmark insulated metal substrate (IMS) in this space for decades. This article looks at how Bergquist MCPCB technology specifically addresses the thermal, electrical, and reliability demands of motor drives, DC/DC converters, and inverter systems — the three hardest thermal environments in mainstream power electronics.

Why Standard PCBs Fail in MCPCB Power Electronics Applications

Before getting into Bergquist specifics, it is worth understanding why the problem exists in the first place. Motor drives, inverters, and industrial control circuits generate significant heat while conducting currents that can exceed 100 amperes in concentrated areas. Traditional FR4 printed circuit boards struggle under these conditions, with limited thermal conductivity around 0.3 W/mK and copper traces that overheat under sustained high-current operation.

The thermal conductivity gap is only part of the story. The real failure mode in high-power FR-4 designs is cumulative thermal fatigue. Traditional PCB construction experiences gradual degradation as thermal cycles stress solder joints and copper interconnections, eventually leading to increased contact resistance or open circuits. A motor drive in a factory might execute tens of thousands of start-stop cycles over a ten-year service life. Each cycle is a thermal stress event on every solder joint and copper-to-laminate interface. FR-4’s relatively high CTE mismatch with power semiconductors, combined with its poor Z-axis thermal conductivity, makes it a poor fit for this environment.

The solution is a substrate with a metal base that acts as an integral heatsink, a thermally conductive dielectric to move heat from the copper circuit layer into that base, and a controlled, well-characterized thermal resistance stack that an engineer can actually model. That is exactly what Bergquist Thermal Clad delivers.

How Bergquist Thermal Clad Works in a Power Electronics Substrate

The three-layer Thermal Clad architecture is straightforward but worth stating precisely for anyone new to IMS design. The copper circuit layer carries the electrical circuit and component mounting — same as any PCB. Beneath it, the proprietary polymer-ceramic dielectric blend provides electrical isolation while conducting heat at 2.2–4.1 W/mK depending on grade. Below that, the aluminum or copper base acts as a heatsink spreader, bolting directly to a cold plate, chassis, or forced-air heatsink.

For power conversion systems, heat is an adversary and too much of it can damage semiconductors, pushing components past recommended safe operating temperatures and reducing their working life. Or worse, can cause catastrophic failure. The Thermal Clad architecture eliminates the worst bottleneck in FR-4 power designs — the dielectric layer — and replaces it with a material engineered specifically for low thermal resistance.

Bergquist Thermal Clad Dielectric Grades for Power Electronics

Dielectric Grade	Thermal Conductivity	Thermal Resistance (°C·cm²/W)	Dielectric Thickness	Breakdown Voltage	Primary Power Electronics Use
MP-06503	2.4 W/mK	0.58	76 µm	~8.5 kVAC	Low-voltage power supplies, SSRs
HT-04503	4.1 W/mK	0.45	76 µm	~8.5 kVAC	Motor drives, DC/DC converters, <480V
HT-07006	4.1 W/mK	0.71	152 µm	11 kVAC	Inverters, VFDs, mains-connected systems
HT-09009	4.1 W/mK	0.90	229 µm	~20 kVAC	High-isolation industrial and traction
HPL-03015	~3.0 W/mK	0.30	38 µm	~2.5 kVAC	Low-voltage LED power stages only

The right column makes the selection logic clear: voltage isolation requirement drives the dielectric thickness, which in turn determines thermal resistance. The thermal conductivity of the HT family is constant at 4.1 W/mK regardless of thickness — so specifying the thinnest dielectric that satisfies your isolation requirement gives you the best thermal performance.

Bergquist MCPCB in Motor Drive Applications

The Thermal Challenge in Motor Drive PCB Design

Modern-day motor drives are integrating more complex power devices to manage growing energy efficiency requirements. The customer’s next-generation motor controller required a thermal interface material (TIM) to manage new performance challenges and higher power densities. As the IC power module is subjected to motor vibration, reliability and stability of the thermal interface material — with no material migration — is critical to enable operational integrity. Any thermal material selected had to meet challenging metrics: electrical isolation with high dielectric strength (>5000 Volts) and low thermal resistance are necessary to meet in-application conditions.

That description captures exactly why motor drive design pushes engineers toward Bergquist MCPCB rather than FR-4 with bolted heatsinks. The combination of high isolation voltage, low thermal resistance, and vibration-tolerant assembly is a specific set of requirements that IMS meets better than any workaround on a conventional substrate.

In a three-phase inverter bridge for a 7.5 kW BLDC motor, the six switching devices — typically IGBTs or SiC MOSFETs in a half-bridge configuration — are the dominant heat sources. Each device dissipates both conduction losses (I²·Rds(on)) and switching losses at every transition. IGBT devices are generally limited to around 20 kHz switching frequency due to tail-current losses; SiC MOSFETs can push to 50 kHz and beyond with far lower switching losses, but they also concentrate that heat in a smaller die area at higher junction temperatures.

Why HT-04503 Is the Motor Drive Workhorse

The Bergquist HT-04503 at 4.1 W/mK thermal conductivity and 0.45 °C·cm²/W thermal resistance handles the IGBT and SiC MOSFET power stage requirements of most industrial motor drives operating from 48V to 480V DC bus. Its 8.5 kVAC breakdown voltage is sufficient for systems up to approximately 480V AC input when the aluminum base is chassis-referenced — though engineers must verify this against their specific safety agency clearance requirements per IEC 60664-1.

The assembly simplification is equally important. Using Bergquist Thermal Clad in motor drives eliminates the need for individual TO-247 or TO-263 isolators under each power device — mica sheets, Kapton pads, or silicone insulators applied one component at a time with thermal compound, hardware, and torque specifications. The board dielectric handles isolation for the entire assembly. This reduces BOM count, eliminates manual assembly steps, and removes a source of field failure (improperly seated insulator pads are a classic cause of motor drive field returns).

Thermal Cycling Reliability: The Motor Drive-Specific Requirement

Motor drive applications are particularly demanding in terms of thermal cycle count. A pump or HVAC drive might see four to eight start-stop cycles per hour, translating to 35,000–70,000 thermal cycles over a ten-year life. Each cycle imposes a temperature swing from near-ambient to operating temperature. Solder joint fatigue, dielectric delamination, and copper trace cracking are all driven by CTE mismatch under those cycles.

Bergquist’s Low Modulus (LM) dielectric addresses this specifically — its lower modulus polymer reduces the mechanical stress transmitted to solder joints during thermal cycling. For HVAC drives, industrial servo amplifiers, and any other application with high cycle count, LM is worth evaluating alongside HT-04503 even if the thermal resistance is slightly higher.

Bergquist MCPCB in DC/DC Power Converter Design

Watt Density in Converter Applications

Inverter PCB designs for solar, UPS, and motor drive applications similarly benefit from the thermal management that Power MCPCB provides. These circuits convert DC power to AC through rapid switching, with power levels ranging from several hundred watts to megawatt-scale industrial systems. The concentration of heat in power modules requires efficient extraction to maintain switching frequency and prevent thermal runaway.

In DC/DC conversion — telecom rectifiers, onboard EV chargers, industrial power supplies — the switching frequency is typically higher than motor drives (100 kHz to 1 MHz for modern resonant topologies), and the form factor pressure is severe. A 48V-to-12V brick converter for telecom infrastructure might need to deliver 300W from a footprint smaller than a credit card. That power density simply cannot be managed with FR-4 and bolted heatsinks in the available space.

Henkel’s liquid gap fillers for DC-DC power converter manufacturing helped a client reduce production costs by 20–30%. That figure reflects what happens when a thermal interface is engineered into the substrate rather than applied as a separate manufacturing step — process cost reduction follows naturally from design simplification.

Converter Stage Dielectric Selection Guide

Converter Type	Input Voltage	Recommended Dielectric	Rationale
Telecom DC/DC (48V in)	48V DC	HT-04503	Low voltage; thermal priority
Industrial SMPS (230V AC)	325V DC bus	HT-04503 or HT-07006	Verify isolation margin per IEC 60664-1
EV Onboard Charger (Level 2)	400V DC bus	HT-07006	High bus voltage; isolation critical
EV Onboard Charger (800V systems)	800V DC bus	HT-07006 / HT-09009	Very high bus; verify creepage clearance
Solar Microinverter	200–400V DC	HT-07006	Mains-referenced; isolation required
Server PSU (12V output, 48V bus)	48V DC	HT-04503	Low voltage; thermal efficiency wins
UPS Inverter Stage (480V)	680V DC bus	HT-07006	High voltage; standard mains isolation

Current Carrying Capability: Heavy Copper on Thermal Clad

One of the underappreciated advantages of Thermal Clad in converter applications is the ability to use heavy copper circuit layers — up to 10 oz (350µm) in standard configurations — without the thermal management problems that heavy copper creates on FR-4. On FR-4, thick copper traces carrying high DC currents generate I²R heat that has nowhere to go except laterally, creating hot spots. On Thermal Clad, that same I²R heat conducts directly downward through the low-resistance dielectric into the aluminum base. The heat path geometry works in your favor.

For high-current busbars on a converter output stage (say, 50–100A continuous), 3 oz or heavier copper on Thermal Clad gives you the current capacity without requiring external copper busbars or cable jumpers.

Bergquist MCPCB in Inverter and Renewable Energy Applications

Solar Inverter and Grid-Tie Applications

Solar power inverters convert the direct current (DC) generated by solar panels into alternating current (AC) for use in the grid. This process generates substantial heat, which can impair the inverter’s performance and lifespan. MCPCBs can be used in photovoltaic (solar) panels to efficiently dissipate heat generated during electricity production. Inverters with MCPCBs can achieve efficiency rates exceeding 98%, compared to lower efficiencies in systems using traditional PCBs. The enhanced thermal management provided by MCPCBs allows for more compact inverter designs, saving space and reducing material costs.

A grid-tied string inverter for residential solar runs its SiC MOSFET bridge at high frequency against a 400V DC bus referenced to mains ground. The HT-07006 dielectric’s 11 kVAC breakdown voltage and 152µm dielectric thickness give a comfortable safety margin for this architecture. The aluminum base bolts directly to the inverter chassis, eliminating a separate heatsink-to-PCB TIM interface.

For utility-scale inverters with higher DC bus voltages (600–1000V), HT-09009 or a custom thick-dielectric configuration is worth evaluating to maintain isolation margin under the relevant IEC/UL standards.

EV Traction Inverter and Onboard Charger Applications

Bergquist PCBs are designed to handle components like inverters, battery management systems (BMS), and electronic control units (ECUs) with ease. These systems require proper heat dissipation to avoid overheating and ensure long-lasting performance.

In EV traction inverters, the power semiconductor stack — whether silicon IGBTs in legacy platforms or SiC MOSFETs in modern 800V architectures — operates continuously at high junction temperature under full torque demand. SiC MOSFETs can operate reliably at junction temperatures up to 175°C, but the package and substrate need to support that consistently over hundreds of thousands of thermal cycles across the vehicle’s service life.

Bergquist MCPCB addresses this by providing a well-characterized, low thermal resistance substrate path from junction to cooling plate. The HT dielectric’s 150°C Tg and UL 746B maximum operating temperature rating of 140°C fit the underhood continuous operating range. For the most demanding EV power module applications — direct die-attach on bare SiC die — the HT dielectric’s compatibility with eutectic AuSn (Au80/Sn20) solder enables die-attach processes that approach the thermal resistance of DBC ceramics at lower material cost.

Bergquist MCPCB vs Other Power Electronics Substrates

Selecting the right substrate for MCPCB power electronics design requires knowing the full landscape, not just Bergquist vs FR-4.

Substrate	Thermal Conductivity	Typical Thermal Resistance	Isolation Voltage	Relative Cost	Best Fit Application
Standard FR-4	0.3 W/mK	50–70 °C·cm²/W	Standard	Low	Low-power logic, signal processing
Generic Al MCPCB	1.0–2.0 W/mK	1.5–3.0 °C·cm²/W	Varies	Medium	Mid-power LED, simple power stages
Bergquist MP-06503	2.4 W/mK	0.58 °C·cm²/W	~8.5 kVAC	Medium	General-purpose power electronics
Bergquist HT-04503	4.1 W/mK	0.45 °C·cm²/W	~8.5 kVAC	Medium-High	Motor drives, DC/DC <480V
Bergquist HT-07006	4.1 W/mK	0.71 °C·cm²/W	11 kVAC	Medium-High	Inverters, VFDs, OBC
DBC Alumina Ceramic	24 W/mK (ceramic)	0.10–0.20 °C·cm²/W	>10 kVAC	High	High-power modules, traction
Arlon PCB (AD/CLTE series)	0.3–0.7 W/mK	N/A (RF focus)	Standard	High	RF/Microwave amplifiers, radar

The Arlon comparison is worth a note for engineers who specify across multiple application types. Arlon PCB materials excel in controlled-impedance RF and microwave applications where loss tangent and Dk stability matter more than thermal conductivity. A high-power inverter with an integrated wireless communication module might actually use both: Bergquist Thermal Clad for the power stage and an Arlon PTFE-based substrate for the RF section, interconnected within the same assembly.

DBC ceramic (alumina or aluminum nitride) remains the choice for very high power density bare-die modules — traction inverters above 100kW, railway converters, wind power converters — where Bergquist’s thermal resistance is still too high. But for the broad middle ground of industrial and automotive power electronics from a few hundred watts to 20–30kW, Bergquist Thermal Clad hits the right balance of thermal performance, isolation voltage, mechanical robustness, and manufacturing cost.

Design Rules and DFM Checklist for MCPCB Power Electronics

Getting the most out of Bergquist Thermal Clad in a power electronics design requires discipline at the layout stage. Here are the checks that matter most:

Design Parameter	Recommendation	Reason
Dielectric grade selection	Choose thinnest grade meeting isolation voltage (IEC 60664-1)	Minimizes thermal resistance
Copper circuit weight	2 oz minimum for power traces; 3 oz for >20A continuous	Reduces I²R heat in traces
Component footprint size	Maximize copper pad area under power devices	Reduces spreading resistance
Creepage and clearance	Per IEC 60664-1 Table F.2 for working voltage and pollution degree	Safety certification compliance
Non-plated holes	Min 0.76 mm (0.030″); use carbide drill bits	Aluminum base requires different tooling
Board edge copper keepout	0.5 mm minimum	Prevents edge delamination
Thermal interface (base to heatsink)	Specify TIM material and bondline in assembly drawing	Thermal resistance stack is only as good as weakest link
SDR (selective dielectric removal)	Specify areas requiring direct metal contact for die-attach	Advanced process; confirm with fabricator
Base metal alloy	5052 or 6061 aluminum for structural; 1050 for highest conductivity	Alloy selection affects both thermal and mechanical properties
Solder mask color	White for LED stages; black for stray light control; standard green for logic area	Application-specific optical requirement

Useful Resources for MCPCB Power Electronics Engineers

Every engineer designing power electronics with Bergquist Thermal Clad should have these references open during the design phase:

Resource	Description	Link
Bergquist Thermal Clad Selection Guide	Full dielectric comparison, design rules, assembly guidelines	Digi-Key PDF
HT-04503 Datasheet	4.1 W/mK, 76µm, motor drive and converter primary grade	mclpcb.com PDF
HT-07006 Datasheet	4.1 W/mK, 152µm, 11 kVAC, inverter and VFD grade	mclpcb.com PDF
MP-06503 Datasheet	2.4 W/mK general-purpose power electronics dielectric	mclpcb.com PDF
IEC 60664-1	Insulation coordination for low-voltage systems — working voltage vs dielectric thickness	IEC Webstore
IEC 62477-1	Safety requirements for power electronic converter systems	IEC Webstore
UL 508C	Power conversion equipment (motor drive safety standard)	UL Standards
IPC-2221B	Generic standard on printed board design — trace/spacing rules	IPC.org
Henkel Thermal Management for Industrial Automation	Application notes for motor drive and power conversion	Henkel
JEDEC JESD51	Thermal measurement methods for power components	JEDEC.org

5 FAQs: Bergquist MCPCB Power Electronics Design

Q1: What is the maximum continuous current that Bergquist Thermal Clad copper traces can carry?

Current carrying capacity depends on copper weight, trace width, allowable temperature rise, and ambient temperature — the same as any PCB, following IPC-2221 tables. The difference with Thermal Clad is that excess heat generated by I²R losses in traces dissipates downward through the dielectric into the aluminum base rather than building up in the surrounding laminate. This means you can sustain higher current densities than equivalent trace geometries on FR-4, but you should still calculate using IPC-2221 external conductor tables and validate with thermal simulation. For bus-width traces on 2 oz copper (70µm), 10A per mm of trace width is a reasonable starting estimate before detailed calculation.

Q2: Can Bergquist Thermal Clad MCPCB handle the high switching frequencies of SiC MOSFETs?

Yes, with no dielectric-related frequency constraint in the 10 kHz to 1 MHz range typical of power electronics. The HT dielectric’s dissipation factor of 0.0129 at 1 MHz means dielectric losses are negligible at power switching frequencies. The design challenges with SiC at high switching frequency are about EMI (dV/dt and dI/dt), gate drive loop inductance, and common-mode current through parasitic capacitance to the aluminum base — not about dielectric frequency response. The capacitance of the dielectric (43 pF/cm² for HT-07006) is worth factoring into common-mode EMC analysis, particularly in designs where the aluminum base is chassis-grounded.

Q3: How does Bergquist MCPCB compare to DBC ceramic for power module applications?

DBC (Direct Bonded Copper) on alumina or aluminum nitride ceramic offers significantly lower thermal resistance than Bergquist Thermal Clad — alumina at 24 W/mK and AlN at 170–200 W/mK, versus HT’s 4.1 W/mK. For bare-die power modules above 50–100kW, DBC ceramics remain the preferred substrate. Bergquist Thermal Clad occupies the space below DBC in both performance and cost — it handles packaged power devices (TO-247, D2PAK, DPAKs, module packages) more cost-effectively than DBC, with better mechanical toughness and machinability than ceramics. For applications where DBC is overspecified, Thermal Clad delivers comparable results at lower material and fabrication cost.

Q4: Is Bergquist Thermal Clad available with a copper base instead of aluminum?

Yes. All Bergquist HT and MP dielectric grades are available bonded to copper base metal as well as aluminum. Copper base offers approximately 90% higher thermal conductivity (390 W/mK vs 205 W/mK for aluminum) and is used when the thermal path to the heatsink is critical and the board cannot be directly bolted to cooling — for example, in applications where the board must flex slightly or mount with spring pressure rather than rigid fasteners. Copper base adds significant weight and cost. For the majority of industrial power electronics applications, aluminum base is the standard choice and more than adequate.

Q5: What is the recommended approach for combining control circuitry and power stage on a Bergquist MCPCB design?

The standard approach for power electronics with significant digital control circuitry is a hybrid assembly: the power stage on Bergquist Thermal Clad, and the gate driver and microcontroller sections on a conventional FR-4 PCB panel attached via press-fit pin headers or soldered pins. The FR-4 section can use standard multilayer construction with full via and routing flexibility. This approach gives you the IMS thermal performance where you need it — under the power switches — without paying the Thermal Clad material cost for logic circuitry that generates minimal heat. The two panels can be singulated from the same assembly panel and connected by pin header during assembly, maintaining automated SMT processing for both boards.

Closing Thoughts on MCPCB Power Electronics with Bergquist

The convergence of higher switching frequencies, wider bandgap semiconductors, and aggressive power density targets is making thermal management one of the defining constraints in modern power electronics design. Metal-backed construction enables direct mounting of power modules to the PCB with thermal interface material providing low-resistance heat transfer to the base plate, which then bolts directly to cooling systems. Industrial control systems demand long-term reliability under continuous operation spanning years or decades.

Bergquist Thermal Clad is not the solution to every power electronics thermal problem — DBC ceramics handle the highest end, and generic aluminum MCPCB handles the low end. But for the broad middle ground where motor drives, converters, and inverters live — tens to thousands of watts, industrial service life expectations, safety agency certification requirements — Bergquist’s HT dielectric family sits at the right intersection of thermal performance, voltage isolation, manufacturing maturity, and supply chain depth. Knowing which grade to specify, and when to reach for it, is the practical skill that turns a thermal analysis model into a board that works reliably in the field.