Inquire: Call 0086-755-23203480, or reach out via the form below/your sales contact to discuss our design, manufacturing, and assembly capabilities.
Quote: Email your PCB files to Sales@pcbsync.com (Preferred for large files) or submit online. We will contact you promptly. Please ensure your email is correct.
Notes: For PCB fabrication, we require PCB design file in Gerber RS-274X format (most preferred), *.PCB/DDB (Protel, inform your program version) format or *.BRD (Eagle) format. For PCB assembly, we require PCB design file in above mentioned format, drilling file and BOM. Click to download BOM template To avoid file missing, please include all files into one folder and compress it into .zip or .rar format.
Bergquist MP-06503 vs HT-04503: Cost vs Performance Trade-Off Analysis
The MP-06503 vs HT-04503 decision is more nuanced than the title suggests. Both products sit at 3 mil (76 µm) dielectric thickness. Both share the same applications list in their TDS documents — power conversion, heat-rails, solid state relays, motor drives, LED applications. Both are at the same price tier from authorized distributors. If you go looking for a straightforward “MP-06503 is the budget version of HT-04503” explanation, you will not find it in the specifications — because that framing is simply wrong.
The actual MP-06503 vs HT-04503 trade-off involves four distinct parameters where the products diverge significantly: thermal conductivity (1.3 W/m-K vs 2.2 W/m-K), glass transition temperature (90°C vs 150°C), solder process rating (300°C vs 325°C), and UL maximum operating temperature (130°C vs 140°C). Against those HT-04503 advantages, MP-06503 counters with a higher peel strength (9 lb/in vs 6 lb/in), a notably higher volume resistivity (10¹⁵ vs 10¹⁴ Ω·m), and a dielectric strength of 2800 V/mil versus HT-04503’s 2000 V/mil. The product with the lower thermal conductivity has the stronger adhesion, the better electrical insulation margin, and the higher dielectric strength per unit thickness. Understanding why those properties trade off the way they do — and which set matters more for your specific design — is the entire point of this comparison.
Before the differences, the common ground. Both products use a 3 mil (76 µm) dielectric thickness, which sets the baseline thermal resistance as the thickness-over-conductivity ratio. Both are RoHS compliant and lead-free solder compatible. Both carry UL 94 V-0 flammability. Both are available in panel and circuit configurations on aluminum or copper base metal. Both cover the same core IMS application territory — they are fully compatible with standard SAC305 reflow assembly, HASL, ENIG, OSP, and immersion silver surface finishes, and both support standard soldermask systems.
Both products also share a 90°C glass transition temperature — which is a critical point that is often missed. MP-06503 and HT-04503 have identical Tg. The 150°C Tg that distinguishes the HT family exists only in the HT-04503, HT-07006, and HT-09009 products. This matters because some engineers assume all HT-series products have 150°C Tg while MP sits at a lower value — the opposite of reality. HT-04503 has 150°C Tg. MP-06503 has 90°C Tg.
Wait — let us correct that immediately. Looking at the official Henkel TDS data: HT-04503 has Tg 150°C. MP-06503 has Tg 90°C. So the two products do differ on Tg, and significantly. The 150°C Tg of HT-04503 is the defining characteristic of the HT polymer family, not shared by MP.
MP-06503 vs HT-04503: Complete Specification Comparison
All values from the official Henkel/Bergquist TDS documents (March 2019 Henkel issue for MP-06503; Bergquist company TDS for HT-04503) and the Bergquist Thermal Clad Selection Guide (Q-6019).
The 1.3 W/m-K dielectric thermal conductivity of MP-06503 versus 2.2 W/m-K for HT-04503 is the most immediately visible specification difference, and it is the one that drives most engineers toward HT-04503 by default. But it is worth understanding why the MP formulation has lower conductivity before concluding it is simply inferior.
The MP-06503 polymer system was engineered to prioritize electrical insulation properties — higher volume resistivity, higher dielectric strength per unit thickness, and higher peel strength — at the cost of some thermal conductivity. The ceramic filler loading and polymer matrix chemistry that produce 2800 V/mil dielectric strength and 10¹⁵ Ω·m volume resistivity are different from the chemistry that produces 2.2 W/m-K thermal conductivity in HT-04503. These properties trade off at the material formulation level, and Bergquist made a deliberate choice with MP-06503 to favour the electrical and mechanical properties over maximum thermal performance.
In practical terms, the 1.8× difference in thermal resistance at 3 mil (0.09 vs 0.05 °C·in²/W) matters significantly at high power density and relatively little at low to moderate power density. For a 5 W SMT transistor on a 0.5 cm² thermal pad (10 W/cm²), the temperature difference across the dielectric is 0.9°C for HT-04503 versus 1.6°C for MP-06503 — a 0.7°C difference that the rest of the thermal stack easily swamps. For a 50 W device on a 1 cm² thermal pad (50 W/cm² = 323 W/in²), the difference grows to 3.2°C vs 5.8°C — 2.6°C separation that starts to matter in tight thermal budgets.
The Solder Limit Difference: 300°C vs 325°C
This is the most consequential specification difference that most MP-06503 vs HT-04503 comparisons online miss entirely. The official Henkel TDS for MP-06503 (March 2019) states: UL solder limit 300°C / 60 seconds. HT-04503 is rated 325°C / 60 seconds.
That 25°C difference means MP-06503 is not compatible with AuSn eutectic die attach. The Au80Sn20 eutectic alloy melts at 280°C and typical reflow profiles reach 295–320°C peak — which exceeds MP-06503’s 300°C solder limit at the upper end of the process window. The Bergquist TDS for MP-06503 does list “Eutectic AuSn compatible” in its Features section — but this refers to the older company-era TDS. The current Henkel March 2019 TDS shows 300°C/60s, which narrows the AuSn margin significantly. Engineers targeting AuSn die attach should specify HT-04503 (or HPL-03015) rather than relying on MP-06503’s marginal headroom.
For standard SAC305 lead-free reflow assembly with a 245–260°C peak profile, both products provide adequate margin. The solder limit distinction only matters when the process temperature exceeds 260°C.
The Glass Transition and Storage Modulus Story
MP-06503’s 90°C Tg with a storage modulus of 0.3 GPa at 150°C tells the complete picture of why this material is unsuitable for applications above 130°C. At 150°C — well above the 90°C Tg — the dielectric is deeply in its elastomeric state. The storage modulus drops from 12 GPa at 25°C to just 0.3 GPa at 150°C, a 40× reduction. Compare this to HT-04503, which goes from 16 GPa at 25°C to 7 GPa at 150°C — still rigid, still mechanically capable.
For applications operating below 100°C substrate temperature, MP-06503’s low-Tg polymer is not a concern. The dielectric stays in its glassy state, peel strength holds at its rated 9 lb/in, and dimensional stability is maintained. For applications approaching or exceeding 100°C substrate temperature — automotive under-hood, industrial near-heat-source power electronics, high-ambient data centre power supplies — HT-04503’s 150°C Tg and 7 GPa modulus at 150°C are not optional safety margin. They are functional requirements.
MP-06503’s Genuine Advantages: Where It Wins
Given those HT-04503 advantages, what drives engineers to MP-06503? The answer lies in three specifications where MP-06503 is meaningfully better.
Peel Strength: 9 lb/in vs 6 lb/in
MP-06503 has the highest peel strength of any single-layer Thermal Clad laminate in the family — 9 lb/in (1.6 N/mm) versus HT-04503’s 6 lb/in (1.1 N/mm). That 50% improvement in copper-to-dielectric adhesion strength matters in two scenarios: heat-rail and forming applications where the metal base is mechanically formed after circuit fabrication (bending creates peel stress at the circuit edge); and high-vibration environments where mechanical shock cycles create cyclic peel loads at circuit features. For Bergquist PCB designs in automotive body electronics, audio amplifier chassis-integrated boards, or any application involving post-fabrication bending or forming, MP-06503’s peel strength advantage is a real design benefit.
Electrical Insulation Properties: Dielectric Strength and Volume Resistivity
MP-06503’s 2800 V/mil dielectric strength (112 kV/mm) versus HT-04503’s 2000 V/mil (80 kV/mm) means that at the same 3 mil thickness, MP-06503 provides 40% more dielectric strength per unit thickness. For applications where the working voltage is in the 300–480 VAC range and the applicable safety standard requires maximum insulation margin at 3 mil dielectric thickness — certain medical equipment classifications, reinforced insulation requirements, or grid-connected equipment with stringent partial discharge limits — MP-06503’s higher dielectric strength per unit thickness can be the decisive factor.
The 10× higher volume resistivity (10¹⁵ vs 10¹⁴ Ω·m) and 10× higher surface resistivity (10¹⁴ vs 10¹³ Ω/sq) are relevant for applications where leakage current is a measurable concern — humid environments, high-impedance measurement circuits near the IMS board, or designs that must meet specific leakage current limits in a product safety standard. In most power electronics applications these differences are inconsequential, but in precision medical or metering applications they can matter.
Lower Dielectric Constant and Capacitance
MP-06503’s Dk of 6 (versus HT-04503’s Dk of 7) and lower 65 pF/cm² capacitance (versus HT-04503’s 85 pF/cm²) reduce the capacitive coupling between circuit layer and base plate. For most power electronics this is irrelevant. For designs with high dV/dt switching — SiC or GaN transistors with nanosecond switching edges — the capacitance from circuit to metal base can create common-mode current paths that affect EMC performance and gate drive stability. In those designs, MP-06503’s lower Dk provides a small but real advantage over HT-04503.
The “Multi-Purpose” Name Decoded: What It Actually Means
The “MP” designation causes confusion. Engineers sometimes interpret it as a generic or entry-level material. It is neither. The “Multi-Purpose” name reflects the fact that MP-06503 was Bergquist’s original proven workhorse dielectric — the TDS describes it as having “twenty plus years of industry proven” performance in a multitude of applications. HT-04503 came later as a higher-Tg formulation for the expanding automotive and high-temperature industrial market. MP-06503 is not a downgraded HT-04503. It is a differently optimised dielectric for the same 3 mil application space, trading thermal conductivity and high-temperature capability for adhesion, electrical insulation, and a lower Dk.
Application Decision Guide: MP-06503 vs HT-04503
Application
Recommended Product
Key Reason
Standard industrial power conversion, 48–240 VDC, ≤85°C ambient
HT-04503 (marginal) or MP-06503
If thermal limited, use HT-04503; if isolation margin or peel is priority, use MP-06503
SSR, 120–480 VAC, ≤85°C ambient
MP-06503
Higher dielectric strength and insulation margin at 3 mil; substrate temp within 130°C RTI
Higher peel strength for vibration resistance; typically ambient ≤70°C
Motor drive at 240 VAC input, ≤85°C ambient
MP-06503 or HT-04503
Either works thermally; MP-06503 if isolation headroom at 3 mil is preferred
COB LED with AuSn die attach
HT-04503
325°C solder limit required; MP-06503’s 300°C limit is insufficient
High-vibration industrial environment
MP-06503
Higher peel strength reduces delamination risk under vibration loading
High dV/dt SiC/GaN switching at low substrate temp
MP-06503
Lower Dk and capacitance reduce common-mode current via base plate capacitance
Medical equipment requiring maximum leakage current margin
MP-06503
10× higher volume resistivity reduces leakage current through dielectric
The Real Cost vs Performance Trade-Off
The article title frames this as a cost trade-off, but the official pricing from authorised distributors shows MP-06503 and HT-04503 panels at comparable cost levels — neither is a consistent budget option for the other. The real trade-off is a performance triangle between thermal conductivity, operating temperature range, and electrical insulation properties:
Choose HT-04503 when: substrate temperature may exceed 100°C continuously; AuSn die attach or thermosonic gold wire bonding is required; maximum thermal performance at 3 mil thickness is the primary design objective; or automotive qualification requiring 140°C UL RTI is mandatory.
Choose MP-06503 when: substrate temperature stays reliably below 100°C; electrical isolation margin and dielectric strength per unit thickness are the priority (SSR, medical, high-voltage 3 mil designs); high peel strength is required for forming, heat-rail, or high-vibration applications; or lower board-to-baseplate capacitance matters for GaN/SiC high-dV/dt designs.
Useful Resources for MP-06503 vs HT-04503 Decisions
Q1: The MP-06503 TDS says “Eutectic AuSn compatible” but the solder limit is only 300°C. Can I use it for AuSn die attach or not?
This is a genuine discrepancy between the older Bergquist company TDS and the current Henkel March 2019 TDS. The older TDS document listed AuSn compatibility explicitly. The current Henkel TDS shows a 300°C/60s solder limit, which provides marginal or insufficient headroom for typical AuSn reflow profiles that reach 295–320°C peak. Bergquist’s intent when labelling MP-06503 as AuSn compatible was likely that the material survives brief AuSn temperatures — but the 300°C limit means you are operating at or above the material’s UL solder rating for a standard AuSn process. The conservative, correct engineering decision is to specify HT-04503 (325°C/60s rated) for any AuSn die attach process and not rely on MP-06503’s borderline temperature margin. If your AuSn profile stays strictly below 300°C at the substrate, MP-06503 may work in practice — but HT-04503 is the published-specification-compliant choice.
Q2: For a 240 VAC industrial SSR application with 70°C max ambient, does the thermal difference between MP-06503 and HT-04503 matter?
At 70°C ambient with a moderate power dissipation typical of an SSR (thyristor at 8–15 W), the substrate temperature will stay comfortably within both products’ operating range (130°C for MP-06503, 140°C for HT-04503). The thermal resistance difference — 0.09 vs 0.05 °C·in²/W — translates to roughly 1–2°C additional temperature rise across the MP-06503 dielectric for a typical SSR at that power level. That difference is not thermally significant in a 70°C ambient design with a generous heatsink. What matters more in SSR design is the electrical insulation — specifically, that the dielectric can withstand 240 VAC (peak 339 VDC) switching continuously plus transient overvoltages, and pass the agency proof test voltage required by the applicable standard (typically UL 508 or IEC 60947). MP-06503’s 2800 V/mil dielectric strength and 8.5 kVAC breakdown give more electrical headroom than needed at that voltage, but for a 3 mil product at 240 VAC, its higher dielectric strength per unit thickness versus HT-04503 is a meaningful safety margin argument. MP-06503 is the better-matched specification for that SSR scenario.
Q3: I keep seeing MP-06503 described as “the older” Bergquist material. Does that mean it is being discontinued or phased out?
No. The “twenty plus years industry proven” language in the Bergquist TDS refers to MP-06503’s track record, not its age as a limitation. It remains an active product in the Henkel Thermal Clad portfolio, available through the same distribution channels as HT-04503, with the same manufacturing support. The fact that it has been in production for longer than HT-04503 actually reflects its reliability pedigree in the field. Field-proven materials with long production histories are generally preferred in safety-critical applications over newer formulations with shorter qualification records. MP-06503’s decades of deployment in industrial SSRs, power conversion, and motor drives is an argument for its specification, not against it.
Q4: What happens mechanically when MP-06503 operates above its 90°C Tg? Is it safe to run above 90°C?
The UL Maximum Operating Temperature for MP-06503 is 130°C, validated through UL 746E RTI testing. Operating above 90°C Tg does not mean the material fails — it means the polymer transitions from a glassy, rigid state to a compliant, elastomeric state. Above the Tg, MP-06503’s electrical properties remain acceptable (the UL RTI testing confirms this at 130°C), but the mechanical properties change dramatically: storage modulus drops from 12 GPa at 25°C to 0.3 GPa at 150°C. In practice, this means the dielectric layer above 90°C becomes stress-relieving rather than rigid. It can actually reduce CTE-mismatch solder joint stress compared to a rigid dielectric — but it also means the circuit layer has less mechanical support from the dielectric at elevated temperature. Peel strength above Tg is lower than the rated 9 lb/in. For static power electronics that do not experience mechanical shock or vibration above 90°C, this is acceptable within the 130°C UL limit. For vibrating assemblies or those with large copper features that create peel forces at temperature, the significantly reduced modulus of MP-06503 above its Tg is a material concern, and HT-04503 (7 GPa modulus at 150°C) is the safer specification.
Q5: Does the lower dielectric constant (Dk 6 vs 7) of MP-06503 make any practical difference to circuit design?
For standard power electronics operating below 100 kHz, the Dk difference between 6 and 7 has no measurable effect on circuit behaviour. Impedance of power traces, current carrying capacity, and thermal performance are all independent of Dk. The Dk becomes relevant in two specific scenarios. First, if you have signal traces on the same IMS board as power devices — unusual but possible in integrated power modules — a lower Dk slightly increases trace impedance and reduces the signal-frequency capacitive coupling to the metal base, which can marginally improve high-frequency signal integrity. Second, for high-frequency power switching above 1 MHz (such as SiC or GaN resonant converters), the capacitance from power node copper to the grounded metal base creates a common-mode current path. MP-06503’s 65 pF/cm² (versus HT-04503’s 85 pF/cm²) reduces that common-mode capacitance by 24% — which translates to a 24% reduction in the high-frequency common-mode current driven through the base metal, potentially improving EMC compliance margins at the board level without additional filtering. This is a real but secondary benefit; for most designs, both products perform identically at the system level.
Inquire: Call 0086-755-23203480, or reach out via the form below/your sales contact to discuss our design, manufacturing, and assembly capabilities.
Quote: Email your PCB files to Sales@pcbsync.com (Preferred for large files) or submit online. We will contact you promptly. Please ensure your email is correct.
Notes: For PCB fabrication, we require PCB design file in Gerber RS-274X format (most preferred), *.PCB/DDB (Protel, inform your program version) format or *.BRD (Eagle) format. For PCB assembly, we require PCB design file in above mentioned format, drilling file and BOM. Click to download BOM template To avoid file missing, please include all files into one folder and compress it into .zip or .rar format.
