Bergquist Thermal Clad PCB FAQ: 25 Most Asked Questions Answered

If you have specified Bergquist Thermal Clad on a board or are evaluating it for the first time, these are the questions that come up repeatedly — in engineering reviews, during prototype sign-off, in supplier qualification conversations, and during failure analysis. This Bergquist thermal clad FAQ compiles 25 of the most technically substantive questions engineers ask, with answers drawn from TCLAD datasheet specifications, the Bergquist Thermal Clad Selection Guide, IPC standards, and practical MCPCB design and assembly experience.

For design application guidance, grade selection examples, and sourcing background, the Bergquist PCB reference page covers the full product overview.

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Section 1: What Is Bergquist Thermal Clad?

Q1: What is Bergquist Thermal Clad and who manufactures it in 2026?

Bergquist Thermal Clad is a proprietary insulated metal substrate (IMS) laminate — a three-layer construction consisting of a metal base (aluminium or copper), a thermally conductive but electrically insulating ceramic-filled polymer dielectric, and a copper circuit foil. The technology was originally developed by The Bergquist Company in the late 1980s as one of the first commercially viable high-performance IMS laminates for power electronics and LED applications.

The ownership chain matters for sourcing in 2026: Bergquist was acquired by Henkel Corporation in 2014, which operated the Thermal Clad product line under its electronics brand for seven years. In 2021, Polytronics Technology Corporation acquired the Thermal Clad business from Henkel, and the product line is now manufactured and sold by TCLAD Inc., headquartered in Prescott, Wisconsin. TCLAD operates with the same manufacturing facility, technical team, and product formulations as the original Bergquist Thermal Clad business. The grade designations (HPL-03015, HT-04503, HT-07006, etc.) remain unchanged. When engineers refer to “Bergquist PCB” or “Bergquist Thermal Clad” today, they are referring to the authentic TCLAD-manufactured laminate.

Q2: What is the difference between Bergquist Thermal Clad and a generic MCPCB?

Both Bergquist Thermal Clad and generic MCPCB use the same physical construction — copper circuit layer, thermally conductive dielectric, metal base — but the dielectric is different in ways that matter for demanding applications. The proprietary polymer-ceramic blend in Thermal Clad achieves higher thermal conductivity (up to 3.0 W/m·K for HPL-03015), verified and tested dielectric breakdown voltages (up to 20 kVAC for HT-09009), defined glass transition temperatures, and UL material recognition for specific grade and construction combinations. Generic IMS dielectric from commodity suppliers may nominally state a thermal conductivity figure but without the same test traceability, breakdown voltage headroom, or UL recognition. For applications where those properties are design requirements rather than preferences — automotive, medical, high-voltage power electronics — the distinction is material.

Q3: What are the standard Bergquist Thermal Clad grades?

There are six principal grades in the current TCLAD Thermal Clad product range. The table below summarises their key differentiating properties.

Table 1: Bergquist Thermal Clad Grade Summary

Grade	Thermal Conductivity	Dielectric Thickness	Breakdown Voltage	Tg	Primary Use
MP-06503	1.0 W/m·K	6.5 mil / 165 µm	~3 kVAC	~130 °C	General purpose, cost-optimised
HPL-03015	3.0 W/m·K	1.5 mil / 38 µm	2.5 kVAC	185 °C	High-power LED, maximum thermal performance
HT-04503	2.2 W/m·K	4.5 mil / 114 µm	11.0 kVAC	>170 °C	High-temp automotive, power electronics
HT-07006	2.2 W/m·K	6 mil / 152 µm	11.0 kVAC	>150 °C	High-temp with higher isolation
CML-11006	1.1 W/m·K	6 mil / 152 µm	10.0 kVAC	90 °C	Cost-optimised multi-layer, moderate temperature
HT-09009	2.2 W/m·K	9 mil / 229 µm	20.0 kVAC	150 °C	High-voltage EV, 800 VDC bus applications

Q4: What does the grade designation code mean? For example, what does “HT-07006” indicate?

The designation encodes the grade family and key dimensional parameters. “HT” stands for High Temperature, indicating the dielectric polymer system is formulated for elevated operating temperatures with UL RTI ratings of 140–150 °C. “070” refers to the nominal dielectric thickness in tenths of a mil — 070 = 7.0 mil, though the actual specification for HT-07006 is 6 mil (152 µm) in some documentation contexts, as the naming scheme reflects the product’s historical evolution. “06” historically referred to the copper foil weight available. The most reliable interpretation is to always cross-reference the designation against the published datasheet for exact thickness, because the code is a product identifier rather than a strict dimensional specification. The “HPL” in HPL-03015 stands for High Power Lighting, reflecting its design purpose. “MP” in MP-06503 stands for Multi-Purpose, indicating its general applicability across voltage and temperature conditions that do not require the HT or HPL series.

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Section 2: Material Properties and Grade Selection

Q5: What is the difference between thermal conductivity and thermal resistance, and which number should I use for design calculations?

Thermal conductivity (k, in W/m·K) is a material property that describes how well a material conducts heat per unit thickness per unit area. It is geometry-independent. Thermal resistance (R_θ, in °C·in²/W or °C·cm²/W for specific resistance, or °C/W for absolute resistance) is a system property that depends on both the material conductivity and the geometry — thickness and area. For design calculations that determine junction temperature, you almost always need thermal resistance, not conductivity alone. The relationship is R_θ(specific) = t / k, where t is dielectric thickness and k is thermal conductivity. For a given pad footprint area (A), absolute thermal resistance R_θ = t / (k × A). Use the specific thermal resistance value from the TCLAD datasheet (e.g., HT-04503: 0.05 °C·in²/W; HT-07006: 0.11 °C·in²/W) and divide by your thermal pad area to get the contribution of the dielectric to total junction-to-ambient thermal resistance.

Q6: Which Bergquist grade should I use for a high-power LED application?

HPL-03015 is the grade designed specifically for high-power LED applications. Its 3.0 W/m·K thermal conductivity and ultra-thin 38 µm dielectric give it the lowest thermal resistance in the range (0.02 °C·in²/W), which is the parameter that most directly reduces LED junction temperature and extends L70 luminous lifetime. HPL-03015’s Tg of 185 °C is the highest in the range, making it dimensionally stable through the reflow process and at elevated luminaire operating temperatures. Its 2.5 kVAC breakdown voltage is adequate for 12–48 V LED driver circuits but is not suitable for mains-voltage applications.

For street lighting, automotive headlamps, or industrial high-bay fixtures where the LED driver operates at mains voltage and the same board hosts both the LED and the driver circuit, HT-04503 or HT-07006 provides the combination of useful thermal performance (2.2 W/m·K) and adequate isolation voltage (11.0 kVAC). HP-03015 should be reserved for boards where the LED is electrically separated from mains potential.

Q7: Which Bergquist grade is correct for automotive electronics applications?

The HT series — HT-04503, HT-07006, and HT-09009 — are the grades for automotive applications. The selection within the HT series depends on two variables: bus voltage and maximum continuous operating temperature. Use this decision framework:

For 12 V and 48 V automotive (LED headlamp, interior lighting, ADAS compute): HT-04503 or HT-07006 based on whether the dielectric thickness needs to be minimised for thermal performance (HT-04503, thinner) or voltage isolation is the primary requirement (HT-07006, thicker). For 400 V DC bus (standard BEV traction systems): HT-07006 minimum; HT-09009 where operating temperature approaches 130 °C and isolation margin must be maximised. For 800 V DC bus (high-performance BEV, emerging standard): HT-09009 is the correct grade — its 20 kVAC breakdown voltage provides the necessary headroom above the 800 VDC working voltage with a compliant safety factor. All HT grades carry UL RTI ratings at 140–150 °C for both electrical and mechanical properties, meeting the AEC-Q200 material temperature requirements for automotive qualification.

Q8: What does Tg (glass transition temperature) mean for Bergquist Thermal Clad, and why does it matter in practice?

Tg is the temperature at which the dielectric polymer transitions from a rigid, glassy state to a softer, rubbery state. Below Tg, the dielectric is dimensionally stable, mechanically stiff, and reliably bonded to both the copper foil and the metal substrate. Above Tg, the material becomes more compliant, begins to exhibit thermomechanical creep, and the copper peel strength decreases — increasing the risk of delamination at the copper-dielectric interface under the stress of further thermal cycling.

The practical rule: the dielectric Tg should be at least 20–30 °C above the maximum continuous operating temperature of the assembly, accounting for self-heating from mounted components. CML-11006’s Tg of 90 °C is the lowest in the range and disqualifies it for many power electronics applications where ambient temperature alone may approach 85 °C. HPL-03015’s Tg of 185 °C is the highest and is appropriate for reflow profiles reaching 260 °C peak with appropriate process controls. For most automotive under-hood applications, HT-04503 (Tg >170 °C) or HT-07006 (Tg >150 °C) is the correct choice.

Q9: Can Bergquist Thermal Clad be used on a copper base instead of aluminium?

Yes. All standard Bergquist Thermal Clad grades are available laminated to copper base metal as well as aluminium. Copper base offers significantly better thermal spreading than aluminium — copper’s thermal conductivity is approximately 385 W/m·K vs 138 W/m·K for 5052 aluminium — which is important when a single large component (such as a power module) dominates the heat input and lateral spreading is critical to minimising hotspot temperature. Copper base also has a lower coefficient of thermal expansion (17 ppm/°C vs 23 ppm/°C for aluminium), which reduces CTE-driven stress at solder joints and via interfaces under thermal cycling. The cost penalty for copper base is substantial — typically 3.5–4.5× the substrate material cost of aluminium at equivalent thickness — and the weight increase is significant for portable or vehicle applications where mass matters. Copper base MCPCB is most commonly specified for EV power modules, high-density LED arrays, and applications where aluminium spreading is insufficient even with the highest-k dielectric.

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Section 3: Design Rules and Layout

Q10: Can I use through-hole components on Bergquist Thermal Clad?

Standard plated through-holes (PTH) are not possible on a single-layer Bergquist Thermal Clad board without via isolation processing. A drill that passes through the copper circuit layer, the dielectric, and the metal substrate will touch the metal base, creating a short circuit between the PTH and the grounded (or floating) baseplate. For single-layer SMD-only designs, this is not an issue — through-hole components are simply not used.

For designs that require through-hole connections, two approaches are available. First, via isolation: the fabricator drills an oversized hole through the metal layer, fills it with insulating resin, cures and re-drills to the final diameter, then plates. This process adds fabrication cost and complexity but produces a reliable PTH isolated from the metal base. Second, hybrid construction: a standard FR-4 circuit layer is bonded above the Thermal Clad layer, with through-holes processed entirely within the FR-4 portion above the IMS dielectric. This is the more common approach for designs requiring both SMD power devices and THT signal connectors. The TCLAD Selection Guide explicitly describes the use of Thermal Clad in multi-layer assemblies as FR-4 replacement.

Q11: What are the minimum trace width and spacing rules for Bergquist Thermal Clad?

Bergquist Thermal Clad uses the same IPC-2221 trace width and spacing framework as standard FR-4. For copper weights of 1 oz (35 µm), standard fabricators can hold 4 mil (0.1 mm) minimum trace width and spacing without premium. For 2 oz copper, the minimum practical trace width increases to approximately 6–8 mil because the etch process must compensate for the sidewall taper at heavier copper weights. For 3 oz copper, 10 mil minimum is a conservative guideline. The important MCPCB-specific rule is copper-to-board-edge clearance: maintain at least 0.5 mm (20 mil) clearance between copper features and the routed board edge to avoid shorting copper to the aluminium substrate at routing burrs. This clearance rule is not present in standard FR-4 DFM guidelines but is commonly flagged by MCPCB fabricators in their DFM review process.

Table 2: Minimum Design Rule Reference for Bergquist Thermal Clad

Parameter	1 oz Copper	2 oz Copper	3 oz Copper
Minimum trace width	4 mil (0.1 mm)	6–8 mil (0.15–0.2 mm)	10 mil (0.25 mm)
Minimum trace spacing	4 mil (0.1 mm)	6 mil (0.15 mm)	10 mil (0.25 mm)
Copper-to-board-edge clearance	20 mil (0.5 mm) min.	20 mil (0.5 mm) min.	20 mil (0.5 mm) min.
Minimum annular ring (PTH)	5 mil (0.125 mm)	5 mil (0.125 mm)	5 mil (0.125 mm)
Via to board edge (if through metal)	50 mil (1.27 mm)	50 mil (1.27 mm)	50 mil (1.27 mm)

Q12: Does Bergquist Thermal Clad support multi-layer PCB construction?

Yes, but with constraints. The TCLAD Selection Guide explicitly describes two multi-layer approaches. In the first, Thermal Clad replaces the FR-4 core in a multi-layer assembly, providing the thermal and isolation function at the base while standard FR-4 prepreg and copper layers are built above it. The second uses selective Thermal Clad areas in a mixed construction — Thermal Clad under power devices and FR-4 under signal routing. For both configurations, via isolation is required for any via penetrating the metal substrate, and the fabricator must be qualified for the additional lamination cycles that multi-layer metal core construction requires. CML-11006 is the grade within the Thermal Clad range specifically formulated for multi-layer applications, with a peel strength of 10 lb/in (1.8 N/mm) — the highest in the range — to maintain bond integrity through multiple press cycles.

Q13: What surface finish should I specify for Bergquist Thermal Clad?

ENIG (electroless nickel immersion gold) is the recommended surface finish for Bergquist Thermal Clad. The specification for ENIG should reference IPC-4552: Ni 3–5 µm, Au 0.05–0.1 µm. HASL (hot air solder leveling) is available at lower cost but carries disbonding risk on Bergquist Thermal Clad, particularly on thin-dielectric grades like HPL-03015 (38 µm dielectric). The thermal shock of the HASL process — immersion in molten solder at 260 °C followed by hot air knifing — can cause disbonding at the copper-to-dielectric interface if the adhesion bond is not perfect. HPL-03015’s ultra-thin dielectric makes this risk higher than on HT-04503 or HT-07006. ENIG provides a flat, solderable surface ideal for LED thermal pads and QFN thermal slugs, is compatible with both SAC305 lead-free and eutectic SnPb processes, and does not introduce thermal shock to the board during application. OSP is acceptable for simple LED boards with low isolation requirements but is not preferred for precision or long-shelf-life production.

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Section 4: Assembly and Soldering

Q14: Is Bergquist Thermal Clad compatible with standard SMT reflow assembly?

Yes. Bergquist Thermal Clad is designed for standard SMT reflow assembly using conventional convection reflow ovens. The metal base acts as a significant heat sink, which means the assembly requires a modified reflow profile compared to FR-4 of the same size. The thermal mass of the aluminium substrate means the board takes longer to reach peak temperature from a standing start, and the reflow oven conveyor speed and zone temperatures need to be adjusted accordingly. The recommended approach is to profile the specific board using thermocouples on the actual thermal pad locations before committing to a production profile. The key point is that the peak oven temperature must deliver 235–250 °C peak at the component solder joint for SAC305 lead-free assembly, regardless of the fact that the substrate itself absorbs heat.

Q15: What is the maximum reflow temperature Bergquist Thermal Clad can withstand?

All HT-series grades (HT-04503, HT-07006, HT-09009) are rated at 325 °C for 60 seconds, making them compatible with eutectic AuSn (gold-tin) soldering as well as SAC305 lead-free and SnPb eutectic processes. HPL-03015 is also rated at 325 °C / 60 s for AuSn compatibility. MP-06503 is rated at 288 °C as its maximum solder temperature — it is compatible with SAC305 lead-free (peak typically 245–250 °C) but not with AuSn processes that require higher peak temperatures. CML-11006, with its lower Tg of 90 °C, requires particular care: the reflow peak temperature will significantly exceed the Tg during processing. This is acceptable because the excursion is brief and the board returns to below Tg before components are mounted and cooled, but it means CML-11006 should not be subjected to extended soak times above 90 °C during reflow profiling.

Table 3: Bergquist Thermal Clad Assembly Compatibility Reference

Grade	Lead-Free SAC305	SnPb Eutectic	AuSn Eutectic	Max Solder Temp
MP-06503	Yes	Yes	No	288 °C
HPL-03015	Yes	Yes	Yes	325 °C / 60 s
HT-04503	Yes	Yes	Yes	325 °C / 60 s
HT-07006	Yes	Yes	Yes	325 °C / 60 s
CML-11006	Yes	Yes	No	288 °C (brief)
HT-09009	Yes	Yes	Yes	325 °C / 60 s

Q16: What causes pad lift on Bergquist Thermal Clad and how can I prevent it?

Pad lift — the physical separation of a copper pad from the dielectric surface — is the most common assembly failure mode on Bergquist MCPCB. It has three root causes: low laminate peel strength (typically a material quality issue), excessive thermal stress during reflow or rework, and mechanical stress from over-torqued mounting screws or heavy through-hole component leads.

Prevention has three corresponding actions. First, specify a minimum copper peel strength in the fabrication notes — standard Bergquist Thermal Clad grades specify peel strength in the range of 5–10 lb/in, and specifying the minimum prevents substitution with lower-adhesion generic dielectric. Second, profile the reflow oven with the actual MCPCB thermal mass and use a gradual preheat ramp (1–3 °C/s) rather than a rapid thermal shock approach. When reworking individual components, preheat the entire board to at least 100 °C before applying localised hot-air heat to the rework site. Third, for boards with mounting holes that bolt to a heatsink, specify torque values in the assembly drawing and use a calibrated torque screwdriver — over-tightened mounting screws warp the board and concentrate stress on nearby pads.

Q17: Can I rework components on a Bergquist Thermal Clad board?

Yes, with the right process. The critical difference from FR-4 rework is the thermal mass of the aluminium substrate — it absorbs heat rapidly during hot-air rework, which means local heat dissipates faster and the rework station needs more power or longer dwell time to reach liquidus at the joint. Preheating the board to 100–120 °C on a preheater before applying directional hot air reduces the required energy input and minimises the temperature gradient across the dielectric and copper-dielectric interface. Limit rework attempts on any single pad to two cycles — repeated thermal cycling of the copper-dielectric interface increases the cumulative stress on the adhesion bond and raises pad lift risk with each cycle. Use flux generously during rework on MCPCB: the ENIG surface on reworked pads oxidises more quickly after the first soldering cycle than on a fresh finish, and adequate flux activity is essential for reliable solder wetting on the second assembly.

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Section 5: Testing, Quality, and Reliability

Q18: What hipot test voltage should I apply to a Bergquist Thermal Clad board?

Hipot (high potential) testing between the copper circuit layer and the metal substrate verifies dielectric integrity of the fabricated board. The test voltage should be determined by your design working voltage and the applicable safety standard, not by the dielectric’s maximum breakdown voltage.

A common rule of thumb for production hipot testing is twice the working voltage plus 500 V, applied as AC RMS. For a board with a 240 VAC working voltage, this gives 480 + 500 = 980 VRMS, typically rounded to 1.0 kVAC. For automotive 800 VDC bus applications, the working voltage for dielectric test purposes is often taken as the peak voltage (1,131 V for 800 VDC), and the test voltage is calculated accordingly against the relevant standard (IEC 60664-1 or automotive equivalent). As a reference: IPC-6012 Class 3 requires hipot testing on all MCPCB boards, with the test voltage specified in the fabrication drawing. The TCLAD Selection Guide notes that the ramp rate matters for Thermal Clad hipot — ramp slowly (recommended: <500 V/s) to avoid nuisance tripping from displacement current due to the board’s capacitive structure.

Table 4: Bergquist Thermal Clad Grade Breakdown Voltages vs Typical Application Working Voltages

Grade	Hipot Breakdown (AC)	Safe Working Voltage (2x + 500V rule)	Suitable for Application
MP-06503	~3.0 kVAC	Up to ~1.25 kVAC working	12–48 V LED, low-voltage power supply
HPL-03015	2.5 kVAC	Up to ~1.0 kVAC working	12–48 V LED only
HT-04503	11.0 kVAC	Up to ~5.25 kVAC working	240–480 VAC motor drives, converters
HT-07006	11.0 kVAC	Up to ~5.25 kVAC working	400 V DC bus, 240–480 VAC mains
CML-11006	10.0 kVAC	Up to ~4.75 kVAC working	240 VAC HVAC drives, moderate voltage
HT-09009	20.0 kVAC	Up to ~9.75 kVAC working	800 VDC EV bus, 690 VAC industrial

Q19: What is dielectric void failure in Bergquist Thermal Clad and how is it detected?

Dielectric void failure occurs when the lamination process traps air between the copper foil and the dielectric layer, or between the dielectric and the metal substrate. These micro-voids create two problems. Thermally, voids at the copper-dielectric interface have air thermal conductivity (~0.026 W/m·K), creating a local thermal hotspot that can be orders of magnitude hotter than the surrounding area at the same power density. Electrically, at the dielectric voltage ratings that make Bergquist grades valuable — 11–20 kVAC — a micro-void in the dielectric is a local weak point that can fail in partial discharge or complete breakdown at voltages well below the grade’s specification.

Void detection is performed by C-SAM (scanning acoustic microscopy), which detects the acoustic impedance contrast between a properly bonded dielectric and a void. C-SAM is a non-destructive inspection method and can map the entire board area for void locations. Cross-section analysis of sample coupons from each press lot is a destructive alternative used for production process verification. Visual inspection alone cannot detect dielectric voids — they are internal to the laminate stack and are not visible from the board surface. When qualifying a Bergquist PCB manufacturer, asking about their void detection process is a direct test of whether their IMS fabrication process includes this critical quality step.

Q20: How do I measure the actual thermal resistance of a Bergquist Thermal Clad board?

The steady-state measurement method for specific thermal resistance (ASTM D5470, which TCLAD uses for its published datasheet values) uses a calibrated hot press with controlled temperature and pressure at both faces of the laminate to measure heat flux and temperature differential. This is a laboratory instrument that most engineering teams do not have.

For practical board-level verification, a simpler approach works well: mount a known-power resistor on the copper circuit layer with solder paste (or thermally conductive adhesive), attach a thermocouple to the copper pad adjacent to the resistor and another to the baseplate directly below, apply a known DC power to the resistor, and wait for steady-state temperature. R_θ(dielectric) = (T_copper − T_baseplate) / P. Compare the result to the expected value from the TCLAD datasheet specific resistance divided by the resistor footprint area. A result more than 30% above the expected value indicates dielectric voiding or material substitution. This test is inexpensive, uses bench instruments, and takes about 20 minutes per board. It is one of the most reliable incoming inspection tests available for verifying that the boards you received match the thermal performance of the Bergquist grade you specified.

Q21: Is Bergquist Thermal Clad UL recognised, and how does UL recognition work for fabricated boards?

Yes. Bergquist Thermal Clad grades carry UL material recognition for specific grade and construction combinations. UL recognition applies to the laminate material as manufactured by TCLAD, for specific copper weight, base metal, and dielectric grade combinations that have been tested and listed under UL’s Component Recognition programme.

When a PCB fabricator uses authentic TCLAD laminate in a construction that matches the recognised grade and configuration, the fabricated board inherits the UL material recognition. The fabricator does not independently apply for UL recognition for each board design — the recognition flows from the TCLAD material listing. This means that if a fabricator substitutes generic dielectric (even with nominally similar thermal and electrical properties), the UL material recognition chain is broken and the end product cannot claim UL-listed MCPCB material. For products requiring CE, UL mark, or CSA certification, verifying that the board uses authentic TCLAD laminate with a traceable lot CoC is a regulatory requirement, not just a preference.

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Section 6: Sourcing, Cost, and Logistics

Q22: Where can I buy authentic Bergquist Thermal Clad PCBs?

Authentic Bergquist Thermal Clad PCBs (fabricated using genuine TCLAD laminate) are available from PCB fabricators that source TCLAD material through the authorised distribution chain. TCLAD distributes laminate through Digikey, Mouser, and Arrow for stocking distributors, and sells direct to larger PCB fabricators. To verify authenticity, require a TCLAD Certificate of Conformance with lot numbers at delivery. In the US, ASC International (asc-i.com) is a documented Bergquist/TCLAD fabricator with quick-turn capability. In Asia, a number of qualified fabricators source TCLAD from TCLAD Technology Corp. in Taiwan. Contact TCLAD directly via tclad.com to request a list of authorised fabricators in your region for production quantities.

Q23: What is the shelf life of Bergquist Thermal Clad laminate?

TCLAD datasheets specify optimal storage at 5–25 °C with a 12-month shelf life from the date of manufacture when stored unopened in the original container. Beyond 12 months, the laminate is not automatically unusable, but its solder compatibility and adhesion properties may have degraded and it should be retested before use in production. For fabricators holding stock, this means that high-turnover grades (HT-04503, HT-07006 at standard configurations) are less likely to have shelf life concerns than slow-moving grades ordered specifically for a project. When receiving laminate or fabricated boards, verify the manufacturing date on the TCLAD CoC to confirm the material was within shelf life at the time of fabrication.

Q24: Is Bergquist Thermal Clad RoHS compliant?

Yes. All current Bergquist Thermal Clad grades are RoHS compliant and lead-free solder compatible. The datasheets explicitly state RoHS compliance and SAC305 lead-free compatibility. The dielectric formulation does not contain any of the restricted substances in the EU RoHS 2 directive (Directive 2011/65/EU and its recast). AuSn (eutectic gold-tin) solder compatibility is stated separately for HT and HPL grades — this is not a contradiction of RoHS compliance because AuSn is itself lead-free. The aluminium and copper base metals used in Thermal Clad construction are also free of restricted substances. When documenting compliance for CE or REACH purposes, the TCLAD product datasheets serve as the material compliance declaration at the component material level.

Q25: When is it NOT worth specifying Bergquist Thermal Clad — when is generic MCPCB adequate?

This is the question that generic Bergquist thermal clad FAQ pages avoid answering, but it is genuinely useful to engineers balancing performance and cost. Generic MCPCB with commodity IMS dielectric is adequate when: the board voltage is below 12–24 V and dielectric breakdown voltage is not a concern; the operating temperature is reliably below 70–80 °C and Tg matters less; the end product does not require UL recognition, automotive qualification, or medical certification; the thermal performance requirement is modest and any 1 W/m·K IMS dielectric meets the junction temperature budget; and cost pressure is significant relative to performance headroom.

Conversely, Bergquist Thermal Clad is clearly the correct choice when the design has a regulated or certified end use requiring UL recognition; when the bus voltage requires a verified breakdown voltage above ~5 kVAC; when operating temperature is above 100 °C and Tg headroom matters; when the thermal conductivity must be verified to a specific value with a traceable test method; or when automotive or medical supply chain qualification requires documented material lot traceability. For the in-between cases — moderate voltage, moderate temperature, no regulatory driver — the decision comes down to whether the 20–40% price premium for authentic Bergquist buys meaningful system-level risk reduction for the specific application.

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Reference Resources for Bergquist Thermal Clad FAQ

Resource	Description	Link
Bergquist Thermal Clad Selection Guide	Complete grade comparison, processing guidelines, UL recognition, application notes	Digikey PDF
TCLAD Inc. Official Website	Current manufacturer; product catalogue, distributor contacts, technical support	tclad.com
Bergquist HPL-03015 Datasheet	Full specifications for the highest thermal conductivity LED grade	MCLPCB PDF
Bergquist HT-04503 Datasheet	Full specifications for HT-04503, the thinnest HT-series dielectric	MCLPCB PDF
Bergquist HT-07006 Datasheet	Full specifications for the most widely used HT-series grade	MCLPCB PDF
Bergquist MP-06503 Datasheet	Full specifications for the multi-purpose, cost-accessible grade	MCLPCB PDF
IPC-6012 Rigid PCB Qualification Standard	MCPCB-specific acceptance criteria, hipot requirements, Class 2/3	IPC.org
IPC-4552 ENIG Plating Specification	Nickel and gold thickness requirements for ENIG surface finish	IPC.org
ASTM D5470 Thermal Conductivity Test Method	Test method used for TCLAD datasheet thermal resistance values	ASTM.org

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Quick Reference: Bergquist Thermal Clad FAQ Summary Table

Table 5: The 25 Questions at a Glance

#	Question	Short Answer
1	Who makes Bergquist Thermal Clad in 2026?	TCLAD Inc., Prescott, Wisconsin (since 2021)
2	How does it differ from generic MCPCB?	Verified breakdown voltage, Tg, thermal conductivity, UL recognition
3	What grades are available?	MP-06503, HPL-03015, HT-04503, HT-07006, CML-11006, HT-09009
4	What does the grade code mean?	Family prefix + dimensional/performance identifiers; always verify against datasheet
5	Thermal conductivity vs thermal resistance — which to use?	Use thermal resistance (°C·in²/W) for junction temperature calculations
6	Best grade for high-power LED?	HPL-03015 for maximum performance; HT-04503/07006 if mains voltage present
7	Best grade for automotive?	HT-04503/07006 for up to 400 VDC; HT-09009 for 800 VDC
8	What is Tg and why does it matter?	Dielectric softening point; keep 20–30 °C below max operating temperature
9	Can I use copper base?	Yes — higher thermal performance and lower CTE; 3.5–4.5× material cost
10	Can I use through-hole components?	Only with via isolation process; SMD-only strongly preferred
11	Minimum trace width / spacing?	4 mil at 1 oz; 0.5 mm copper-to-edge clearance mandatory
12	Multi-layer designs possible?	Yes; CML-11006 optimised for this; via isolation required through metal
13	Best surface finish?	ENIG per IPC-4552; HASL carries disbonding risk on thin dielectrics
14	Standard SMT reflow compatible?	Yes; adjust reflow profile for higher thermal mass vs FR-4
15	Maximum reflow temperature?	HT/HPL: 325 °C / 60 s; MP-06503: 288 °C maximum
16	Why do pads lift and how to prevent?	Low peel strength, thermal shock, mechanical over-stress; slow preheat + torque control
17	Can I rework Bergquist boards?	Yes; preheat to 100–120 °C, limit to 2 rework cycles per pad
18	What hipot test voltage to apply?	(2 × working voltage + 500 V) AC; ramp slowly to avoid nuisance tripping
19	What is dielectric void failure?	Trapped air at laminate interface → thermal hotspot and breakdown risk; detect by C-SAM
20	How to measure actual thermal resistance?	Bench heater-thermocouple method; compare vs TCLAD datasheet ±30% tolerance
21	Is it UL recognised?	Yes; recognition flows from TCLAD laminate to fabricated board when authentic material is used
22	Where to buy authentic boards?	Fabricators stocking TCLAD laminate; require lot CoC at delivery
23	Shelf life of laminate?	12 months from manufacture; store at 5–25 °C, unopened
24	Is it RoHS compliant?	Yes; all grades are lead-free and SAC305 compatible
25	When is generic MCPCB adequate instead?	Low voltage (<24 V), low temperature (<70 °C), no regulatory certification required

For the complete Bergquist Thermal Clad product overview, grade selection guidance, and sourcing information, visit the Bergquist PCB reference page.