Electronic power supply potting compound

Electronic Power Supply Potting Compound Testing Service – Comprehensive Performance and Reliability Validation for Brazilian Power Electronics and Industrial Applications

As an ISO/IEC 17025 accredited independent testing laboratory, we offer comprehensive testing services for potting compounds used in electronic power supplies across Brazilian industrial, automotive, renewable energy, telecommunications, and consumer electronics sectors. Potting compounds – typically two‑part epoxy, polyurethane, silicone, or hybrid resins – encapsulate sensitive electronic components to provide electrical insulation, thermal management, mechanical protection, and environmental sealing. In Brazil's demanding conditions – including high ambient temperatures, humidity, and voltage fluctuations – the potting material must maintain its dielectric strength, thermal conductivity, adhesion, and dimensional stability over the product's lifetime. Our test protocols evaluate the chemical, thermal, electrical, mechanical, and environmental performance of potting compounds under simulated service conditions. All methods are aligned with ABNT NBR standards, ASTM D149 (Dielectric strength), ASTM D257 (Insulation resistance), ASTM E1530 (Thermal conductivity), ISO 11357 (DSC), ASTM D2240 (Hardness), ASTM D638 (Tensile properties), ASTM D3359 (Adhesion), IEC 60068‑2‑1 (Cold), IEC 60068‑2‑2 (Dry heat), IEC 60068‑2‑78 (Humidity), and UL 94 (Flammability). Our reports are recognised by INMETRO (product certification), ANEEL (electrical equipment compliance), ABNT (technical standards), and Brazilian power electronics manufacturers, automotive suppliers, and renewable energy integrators for supplier qualification, quality assurance, and regulatory compliance.

Types of Electronic Power Supply Potting Compounds and Components We Regularly Test

Our laboratory accommodates a wide range of potting formulations, package configurations, and application scenarios. Typical test articles include:

• Epoxy potting compounds – rigid, thermally conductive, and flame‑retardant grades for industrial power supplies
• Polyurethane potting compounds – flexible, low‑viscosity, and moisture‑resistant types for outdoor and automotive modules
• Silicone potting compounds – high‑temperature, soft‑gel, and optically clear grades for LED drivers and high‑voltage systems
• Hybrid and specialty potting resins – with enhanced thermal cycling or chemical resistance
• Cured potting samples – cast as slabs, discs, or directly on functional power supply modules
• Encapsulated PCBs and assemblies – for real‑world performance verification
• Single and multi‑component liquid resins – for curing kinetics and rheology studies

Electrical Properties – Dielectric Strength, Insulation Resistance and Partial Discharge

• Dielectric strength (breakdown voltage) – ASTM D149 / IEC 60243‑1 / ABNT NBR IEC 60243‑1 – We prepare cured potting compound specimens (typically 1‑3 mm thick discs) and subject them to a rapidly increasing AC voltage (500 V/s) using a dielectric test set with a 25 mm diameter spherical electrode. The breakdown voltage (in kV) is recorded, and the dielectric strength is calculated as kV/mm. For Brazilian power supplies operating at 220‑480 V, a dielectric strength of at least 15 kV/mm is typically required. We also perform the test after humidity conditioning (40 °C, 93 % RH, 48 hours) to assess the wet dielectric strength retention.
• Volume and surface resistivity – ASTM D257 / IEC 60093 / ABNT NBR 14741 – Using a guarded electrode system and a high‑resistance meter, we measure the volume resistivity (Ω·cm) and surface resistivity (Ω) at 500 V DC. Measurements are taken at 23 °C and 50 % RH, and also after 24‑hour immersion in water. A volume resistivity of ≥ 10¹⁴ Ω·cm is typical for high‑quality potting compounds used in Brazilian industrial power supplies.
• Partial discharge inception voltage (PDIV) – IEC 60270 / ABNT NBR 15748 – For high‑voltage power supplies (e.g., traction drives, solar inverters), we measure the partial discharge inception voltage (in kV) and the apparent charge (in pC) using a PD‑free coupling capacitor and a phase‑resolved pattern analyser. A PDIV of at least 1.5× the operating voltage is required for Brazilian high‑reliability applications.
• Comparative tracking index (CTI) – IEC 60112 / ABNT NBR 15503 – We apply 50 drops of a standard electrolyte solution (0.1 % NH₄Cl) to the surface of the cured potting compound under an AC voltage (typically 100‑600 V), and record the maximum voltage at which the material does not form a conductive track (in volts). A CTI of ≥ 250 V is required for Brazilian power supply insulation systems.

Thermal Properties – Conductivity, Glass Transition and Heat Deflection

• Thermal conductivity – ASTM E1530 / ISO 22007‑2 / ABNT NBR 15957 – Using a guarded heat flow meter or a transient plane source (hot disk) method, we measure the thermal conductivity (in W/m·K) of the cured potting compound at 25 °C and at the maximum operating temperature (e.g., 100 °C). For power supplies with high dissipation, a thermal conductivity ≥ 0.8 W/m·K is typically required; thermally filled grades may reach 2‑4 W/m·K. We report the conductivity at both temperatures and the temperature coefficient.
• Glass transition temperature (Tg) – ASTM E1356 / ISO 11357‑2 / ABNT NBR 15840 – Using differential scanning calorimetry (DSC), we heat the cured sample from ‑40 °C to +200 °C at 10 °C/min and record the midpoint of the step change in heat capacity. The Tg (in °C) is reported. For epoxy potting compounds, a Tg above 120 °C is typical for Brazilian applications to avoid softening under thermal stress.
• Coefficient of thermal expansion (CTE) – ASTM E831 / ISO 11359‑2 / ABNT NBR 15840 – Using thermomechanical analysis (TMA), we measure the linear CTE (in ppm/°C) of the cured material from 25 °C to the Tg (and above Tg). A low CTE (e.g., < 40 ppm/°C) is desirable to match the expansion of copper and PCB materials, reducing the risk of stress‑induced failures during thermal cycling.
• Heat deflection temperature (HDT) – ASTM D648 / ISO 75 / ABNT NBR 11298 – We apply a standard bending stress (1.82 MPa or 0.45 MPa) to a cured bar specimen and measure the temperature at which a defined deflection (0.25 mm) occurs. For Brazilian power supplies operating in hot environments, an HDT ≥ 100 °C is typically required.

Mechanical Properties – Hardness, Tensile Strength, Elongation and Adhesion

• Shore hardness (A or D) – ASTM D2240 / ISO 7619‑1 / ABNT NBR 14394 – Using a calibrated durometer, we measure the Shore A (for soft silicones) or Shore D (for rigid epoxies) at five points on the cured sample. The average hardness is reported. For Brazilian automotive power supplies, a hardness of Shore A 50‑70 (silicone) or Shore D 70‑85 (epoxy) is typical.
• Tensile strength and elongation at break – ASTM D638 / ISO 527 / ABNT NBR 14535 – We prepare dog‑bone specimens from the cured potting compound (type V or I) and pull them at 5 mm/min in a universal testing machine. The tensile strength (in MPa), the elongation at break (in %), and the modulus of elasticity (in MPa) are recorded. A tensile strength ≥ 20 MPa and elongation ≥ 2 % are typical for structural potting compounds; silicones may have lower strength but > 100 % elongation.
• Adhesion to substrates – ASTM D3359 / ISO 2409 / ABNT NBR 15044 – We apply the uncured potting compound to standard substrates (aluminium, copper, FR‑4 PCB, and galvanised steel) and cure it. We then perform a cross‑hatch cut and tape peel test, assigning a rating from 0B (poor) to 5B (excellent). For Brazilian power supplies, a rating of ≥ 4B is required on all substrates.
• Lap shear strength – ASTM D1002 / ISO 4587 – For adhesive bonding performance, we prepare lap shear specimens (two metal plates bonded with the potting compound) and test at 1 mm/min. The maximum shear stress (in MPa) is reported. A lap shear strength of ≥ 5 MPa is typical for high‑reliability potting.

Environmental and Ageing Resistance – Temperature, Humidity, Salt and Chemical Exposure

• Thermal cycling – IEC 60068‑2‑14 / ABNT NBR IEC 60068‑2‑14 – We subject cured potting specimens (and encapsulated modules) to 100 or 500 cycles from ‑40 °C to +125 °C (with a 30‑minute dwell at each extreme and a ramp rate of 10 °C/min). After cycling, we inspect for cracks, delamination, and perform dielectric strength and adhesion tests. Any visible crack or a drop in dielectric strength > 20 % is reported as a failure.
• Damp heat (steady state) – IEC 60068‑2‑78 / ABNT NBR IEC 60068‑2‑78 – We expose cured samples to 40 °C, 93 % RH for 56, 336, or 1,000 hours. After exposure, we measure the water absorption (weight gain in %), dielectric strength, and insulation resistance. A weight gain of > 2 % or a dielectric strength drop of > 30 % is reported as a moisture sensitivity issue.
• Salt spray resistance – ASTM B117 / ABNT NBR 8096 – For power supplies used in marine or coastal Brazilian environments, we expose encapsulated test boards (with components) to a 5 % NaCl fog at 35 °C for 240 or 500 hours, then inspect for corrosion of terminals, and measure the insulation resistance. Any visible corrosion or insulation resistance < 100 MΩ is a failure.
• Chemical resistance – ASTM D543 / ISO 175 / ABNT NBR 15257 – We immerse cured samples in common industrial chemicals (synthetic engine oil, brake fluid, 5 % H₂SO₄, 5 % NaOH, isopropanol) for 168 hours at 23 °C. The weight change, hardness, and tensile strength retention are measured. A retention of ≥ 80 % in tensile strength is required for Brazilian industrial power supplies.

Flammability, Toxicity and Outgassing – Safety and Regulatory Compliance

• Flammability rating – UL 94 / ABNT NBR 15123 – We test cured specimens (125 × 13 × 3 mm) in the vertical or horizontal orientation and classify them as V‑0, V‑1, V‑2, or HB. For Brazilian power supplies, a minimum rating of V‑1 is typically required; V‑0 is preferred for high‑reliability and fire‑sensitive applications. The afterflame time and dripping behaviour are reported.
• Halogen content and RoHS compliance – IEC 62321 / ABNT NBR 15475 – We analyse the cured or uncured material for bromine, chlorine, and other restricted substances using XRF or IC. The result is reported as “compliant” or “non‑compliant” with Brazilian RoHS and the EU RoHS directive (which Brazil follows for electrical/electronic equipment).
• Toxic gas emission – smoke and fume analysis (ISO 5659‑2 / ASTM E662 adapted) – For fire safety, we measure the smoke density (Ds) and the toxicity index (using FTIR for gases such as HCN, CO, HCl) during combustion. A smoke density of < 300 at 4 minutes and a CO concentration < 2,000 ppm are typical acceptance criteria for Brazilian public transportation and building applications.
• Outgassing under vacuum – ASTM E595 / NASA reference – For aerospace and satellite power supplies, we measure the total mass loss (TML) and collected volatile condensable materials (CVCM) at 125 °C for 24 hours in vacuum. A TML < 1 % and CVCM < 0.1 % are required for Brazilian space projects.

Curing Kinetics and Processability – Rheology, Gel Time and Exotherm

• Viscosity and rheological behaviour – ASTM D2196 / ISO 2555 / ABNT NBR 15833 – We measure the viscosity (in mPa·s) of the liquid potting compound at 25 °C and at 40 °C using a rotational viscometer with different shear rates. The thixotropic index (ratio of viscosity at low shear to high shear) is calculated. A suitable viscosity (typically 2,000‑20,000 mPa·s) is critical for penetrating tight spaces without void formation in Brazilian power supply assembly.
• Gel time and pot life – ISO 3679 / ASTM D2471 – We monitor the viscosity increase over time at 25 °C and at the curing temperature (e.g., 60 °C) to determine the working time (pot life) and the gel point. The gel time (in minutes) is reported, which is essential for process planning in Brazilian manufacturing.
• Peak exotherm temperature – ASTM D3553 / ISO 11357 – Using DSC or a thermocouple embedded in a 100‑gram bulk sample, we measure the maximum temperature reached during the exothermic curing reaction. A peak exotherm that exceeds 180 °C may cause damage to sensitive electronic components; we report the value and recommend a cure profile.
• Glass transition of uncured / partially cured material (by DSC) – to assess cure degree – We also perform DSC on samples cured at different temperatures (e.g., room temperature, 60 °C, 80 °C) to determine the residual enthalpy and calculate the degree of cure (%). A degree of cure ≥ 95 % is required for full performance.

Report Acceptance & Compliance with Brazilian Electrical, Automotive and Industrial Standards

All electronic power supply potting compound tests described above are conducted under our ISO/IEC 17025:2017 accreditation, using calibrated dielectric testers, thermal analysers, tensile machines, hardness testers, environmental chambers, and analytical instruments, all traceable to INMETRO and international reference standards. Our final test reports include: a comprehensive description of the potting compound (chemistry, cure schedule, recommended application), a summary of all measured parameters (dielectric strength, thermal conductivity, Tg, hardness, adhesion, water absorption, flammability, etc.), statistical summaries (mean, standard deviation, coefficient of variation), photographic evidence of any failures (cracks, delamination, corrosion), and a clear pass/fail verdict against your specified acceptance criteria (e.g., dielectric strength ≥ 15 kV/mm, Tg ≥ 120 °C, UL 94 V‑0 rating). We also provide an expanded uncertainty (k=2) for all key quantitative measurements. These reports are widely accepted by INMETRO for product certification of power supplies, by ANEEL for electrical equipment compliance, by ABNT for normative conformity, and by Brazilian manufacturers of industrial drives, inverters, chargers, UPS systems, and automotive power modules for supplier qualification, process validation, and quality assurance. Bilingual (Portuguese/English) versions are available to facilitate submissions to regulatory bodies and to support your engineering, procurement and quality teams. With our rigorous and comprehensive potting compound testing, you can confidently select the optimal encapsulation material to ensure long‑term reliability, safety and performance of your power supply products in the Brazilian market.