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SO-820 Silicone Potting Compound | UL 94 V-0 RTV Encapsulation Material Taiwan
Two-component RTV silicone potting compound. UL 94 V-0 certified (E120665), 0.54 W/m·K thermal conductivity. For OBC, BMS, LED drivers, and industrial sensors. Supports manual and automated processes.
Description
Fong Yong Chemical Co., Ltd. is one of the leading manufacturers and suppliers of SO-820 Silicone Potting Compound | UL 94 V-0 RTV Encapsulation Material Taiwan in Taiwan. Welcome to wholesale bulk customized SO-820 Silicone Potting Compound | UL 94 V-0 RTV Encapsulation Material Taiwan at low price from our factory. If you have any enquiry about quotation and free sample, please feel free to email us.
SO-820 Flame Retardant Silicone Potting Compound
✓ UL 94 V-0 Certified | File No. E120665 | Two-Component RTV Silicone | 4:1 Mix Ratio
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This page is for you if: You are evaluating a potting material for electronic components and need to simultaneously satisfy flame retardancy, electrical insulation, and enclosed-space thermal management - without qualifying three separate materials. If only one of these requirements applies, see When NOT to Use SO-820 below. |
Page Overview
In electronic assemblies, reliability failures often originate inside the encapsulated region - not at external interfaces. Incomplete filling, air entrapment, and uneven material distribution are the three most common root causes that remain invisible after curing and surface only as delayed field failures.
SO-820 is a two-component flame-retardant RTV silicone potting compound engineered for full encapsulation of electronic components where dielectric insulation, controlled heat dissipation, and consistent void-free filling are simultaneously required.
By combining UL 94 V-0 flame retardancy, a thermal conductivity of 0.54 W/m·K, and a 20 kV/mm dielectric strength in a single formulation, SO-820 eliminates the need to trade off between fire safety, thermal management, and electrical insulation - properties that potting engineers must often balance separately. This combination allows initial evaluation using a single material system before committing to multi-material qualification strategies.
Why SO-820? Three Engineering Guarantees
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UL Global Compliance Passport UL 94 V-0 certification (File No. E120665) means your finished assembly can reference SO-820 during safety audits for export to the US and EU markets - reducing re-test cycles and shortening product development timelines. Certified at 3.5–3.9 mm, black and white. Verify at iq.ul.com: E120665. |
0.54 Active Thermal Management At 0.54 W/m·K - above the 0.2 W/m·K baseline of standard sealing silicones - SO-820 actively conducts heat away from enclosed components rather than trapping it, preventing performance degradation from thermal buildup. Reference: typical silicone sealants 0.15–0.25 W/m·K; thermal potting compounds 0.5–1.5 W/m·K. |
20kV High-Voltage Arc Protection A dielectric strength of 20 kV/mm provides reliable isolation for precision sensors and power modules. This guards against arc breakdown in high-voltage environments where voids in poorly-filled potting material would otherwise become failure points. Volume resistivity: 1 x 10^14 ohm-cm (standard conditions). |
Target Application Scenarios
SO-820 is suited to electronic assemblies where flame retardancy, electrical insulation, and enclosed-space thermal management must be addressed by a single potting material - eliminating the need to qualify separate materials for each function.
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Automotive Electronics On-board chargers (OBC) High charging currents generate sustained heat inside sealed enclosures. UL 94 V-0 supports automotive safety audits; 0.54 W/m·K aids thermal stability over long charge cycles.
Battery management modules (BMS) Moisture ingress and arc risk require simultaneous waterproofing and high-voltage isolation within a compact, potted structure. |
Industrial Power High-efficiency power adapters Switching losses in dense adapters require active thermal conduction out of the potted region. UL 94 V-0 meets standard safety requirements without a separate flame retardant coating.
Outdoor LED drivers Outdoor installation demands both IP-level moisture exclusion and flammability compliance; full potting with SO-820 addresses both simultaneously. |
Industrial Sensors Long-life moisture-resistant sensors Sensors in humid or washdown environments require complete encapsulation of signal electronics. Shore A 30 flexibility prevents cracking from thermal cycling or vibration.
Flame-rated sensing modules UL 94 V-0 allows the sensor module to serve as the flame-retardant element, simplifying end-product certification. |
Key Takeaways
✓ Full potting and encapsulation - not surface sealing
Designed for complete internal coverage, not interface-level protection.
✓ Two-component RTV (4:1) - manual or automated mixing
Defined ~20 min working time supports controlled dispensing in production environments.
✓ Flowable with good leveling behavior
Supports uniform filling and reduces void formation inside complex geometries.
✓ Vacuum de-air compatible
Reduces air entrapment in enclosed regions where post-cure inspection is not feasible.
✓ UL 94 V-0 (File No. E120665)
Verified flammability compliance - directly referenceable in safety audit documentation.
✓ 0.54 W/m·K thermal conductivity + 20 kV/mm dielectric strength
Simultaneous heat dissipation and electrical insulation from a single material qualification.
When to Use SO-820
- Full potting is required - internal components need complete coverage, not only interface sealing.
- Mixing, vacuum de-air, and controlled filling can be integrated into the manufacturing process.
- Uniform, void-free material distribution is critical to insulation reliability.
- Both dielectric insulation and thermal dissipation are required inside the same assembly.
- UL 94 V-0 compliance is required for the potting material itself.
When NOT to Use SO-820
- Only external sealing is required (enclosure seams, cable exits, connector glands).
- A single-component, no-mix process is required due to equipment or process constraints.
- Precise mix ratio control or vacuum de-air cannot be maintained in production.
- The application requires only partial or localized protection rather than full encapsulation.
- Focus is on external ingress protection only, with no internal thermal or insulation requirement.
Engineering Prevention Guide: Common Failure Modes
The following process guidance reflects known failure patterns in two-component silicone potting. Addressing these at the process design stage - before the first production run - is significantly less costly than troubleshooting field returns.
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[Failure Mode 1] Internal Voids - Long-Term Insulation Breakdown Root cause: Air entrapped during mixing or dispensing remains inside the cured elastomer as micro-voids. Under sustained high voltage, these voids become sites for partial discharge, accelerating dielectric degradation over time. This failure mode is particularly critical in assemblies where post-cure inspection of internal regions is not feasible. Prevention: Given SO-820's ~20 minute working time, vacuum de-air at 10–20 torr is recommended immediately after mixing and before dispensing. This pressure range collapses micro-bubbles without initiating premature cure. For complex enclosure geometries, a second de-air cycle after filling - before gelation - can further reduce residual void content. |
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[Failure Mode 2] Incomplete Cure - Mechanical and Electrical Property Variation Root cause: SO-820 uses a 4:1 A:B ratio by weight. Deviations from this ratio - even within ±5% - produce an off-stoichiometric mix with reduced hardness, lower dielectric strength, and compromised adhesion. Volume-based mixing is particularly prone to ratio error due to the density difference between Part A (1.57 g/cm3) and Part B (0.96 g/cm3). Prevention: Always measure by weight using a calibrated electronic scale. For automated dispensing, verify the metering ratio with a gravimetric check at the start of each production shift. Avoid volumetric measurement - the density difference between Part A and Part B means volume ratios will not produce the correct stoichiometric mix. |
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[Failure Mode 3] Interface Delamination - Moisture and Contaminant Ingress Root cause: Oil residues from component handling, flux from soldering, or moisture on PCB surfaces create a weak interface layer that separates under thermal cycling - reintroducing the moisture pathways and electrical exposure that potting was designed to eliminate. Prevention: Clean all substrate surfaces with IPA using a lint-free cloth before potting. Do not use soap or water-based detergents - residual surfactants impair adhesion. For assemblies with post-solder flux residues, ensure flux-cleaning is complete and surfaces are fully dry. SO-820 does not require a primer for most metals, glass, ceramics, or PCB substrates under standard conditions. |
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Technical Properties
Quick Fit legend: ✓ Fits most applications △ Verify for your scenario → 🔗Consult our team
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Property |
Value |
Test Method |
Engineering Significance |
Quick Fit |
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Mix ratio (A:B) |
4 : 1 (wt/wt) |
- |
Weight-based only - density diff A (1.57) vs B (0.96) makes volume mixing unreliable |
△ Scale req. |
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Pot life at 25°C |
~20 min |
- |
Plan mix + de-air + fill within this window; automated lines must fit cycle time |
△ Verify |
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Mixed viscosity |
~3,000 cps |
ASTM D-2196 |
Flows into complex geometries; does not require forced injection under standard conditions |
✓ Most |
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Cure time (3 mm) |
~24 hrs |
- |
Thickness-dependent; thicker sections require extended cure - test your geometry |
△ Verify |
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Hardness |
Shore A 30 |
ASTM D-2240 |
Flexible elastomer - absorbs thermal expansion stress; does not transmit load to components |
✓ Most |
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Thermal conductivity |
0.54 W/m·K |
ASTM D5334 |
Above typical sealants (0.15–0.25); actively conducts heat out - not just thermally neutral |
✓ Most |
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Dielectric strength |
~20 kV/mm |
ASTM D-149 |
Void-free fill is critical - micro-voids reduce effective dielectric performance significantly |
△ Process-dep. |
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Volume resistivity |
1×10¹⁴ Ω·cm |
ASTM D-257 |
High bulk insulation at standard conditions; consult for high-temp or transient environments |
△ Verify |
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Flame rating |
UL 94 V-0 |
UL 94 (E120665) |
Referenceable in safety audit docs; covers WT and BK at 3.5–3.9 mm |
✓ Most |
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Operating temp. |
-45°C to +150°C |
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Covers automotive and industrial thermal cycles without additional over-mold |
✓ Most
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* Curing time varies with temperature, humidity, and section thickness. Validate under actual production conditions before committing to process parameters.
Standardized Potting Workflow (7 Steps)
Figure 1. Representative industrial workflow for two-component silicone potting, including pre-mixing, ratio control, vacuum de-air, and controlled filling. Actual processes may vary depending on equipment and application conditions.
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1 |
Surface Preparation Clean substrate with IPA and a lint-free cloth to remove dust, flux residues, oil, and handling contamination. Do not use soap or water-based cleaners. Allow to dry fully before potting. |
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2 |
Pre-Mix in Original Containers Stir Part A and Part B separately in their original containers before combining. Part A contains dense fillers that may partially settle during storage - pre-mixing restores uniformity. |
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3 |
Measure A & B by Weight (4:1) Weigh Part A and Part B into a clean, dry container using a calibrated electronic scale. Record the weights. Weight-based measurement compensates for the density difference (A: 1.57 g/cm3, B: 0.96 g/cm3). |
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4 |
Mix Thoroughly Mix with a clean, dry metal rod, scraping walls and bottom to eliminate unmixed pockets. Mix until visually homogeneous. Incomplete mixing produces partial cure and non-uniform mechanical properties. |
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5 |
Vacuum De-Air (10–20 torr) Place mixed material in a vacuum chamber. Apply 10–20 torr to collapse entrapped micro-bubbles. Maintain until bubble evolution ceases. Typically 5–10 minutes of the 20-minute working time is sufficient. |
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6 |
Controlled Filling Slowly pour or dispense at a low angle to allow self-leveling and air displacement. Do not drop from height - this reintroduces air. For complex geometries, tilt the enclosure to guide flow away from critical components. |
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7 |
Room Temperature Cure Allow to cure at ~25°C. Do not disturb during initial gel phase (first 2–4 hours). Full cure for 3 mm sections: ~24 hours. Thicker sections require proportionally longer cure time. |
**If your process involves mixing, vacuum de-air, and controlled filling, early-stage sample evaluation is recommended to verify flow behavior, void control, and curing consistency under actual production conditions.
► 🔗Ready to test this workflow in your process?
Apply for the SO-820 Rapid Evaluation Kit - a Part A + Part B sample set sized for initial hardness, adhesion, and potting flow evaluation. Include a brief description of your enclosure geometry and target application when requesting.
Supply & Procurement Information
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Item |
Details |
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Product type |
Two-component RTV silicone potting compound | 4:1 mix ratio (A:B by weight) |
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Standard packaging |
Part A: 5 kg / 10 kg / 20 kg sets Part B: 1 kg sealed metal can (moisture-sensitive - supplied in smaller containers to minimize exposure during use) |
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Minimum order quantity |
1 set (Part A + Part B, ratio-matched). Larger volume options available on request. |
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Shelf life |
Part A: 9 months | Part B: 6 months (unopened, stored at 25°C or below, dry, away from moisture and light) |
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Lead time |
10–14 business days after order confirmation (made-to-order production) |
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Documentation |
🔗UL Certification (File No. E120665) · 🔗Technical Data Sheet (TDS) · Safety Data Sheet (SDS) - available on request |
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⚠ Part B Storage & Handling - Critical Points Part B reacts with atmospheric moisture. Unlike Part A, it cannot be left open between uses. Reseal the Part B container immediately after each use - even briefly leaving it open in humid air causes surface skinning and viscosity change. Use Part B within a single production session where possible. If unused material remains, reseal tightly and store below 25°C in a dry environment. Do not transfer Part B to a different container type. The original sealed metal can is designed to minimize headspace and moisture contact. Shelf life of 6 months applies only to the original, unopened container. Once opened, use within the session or re-evaluate before next use. Visual check before use: if Part B appears cloudy, thickened, or shows gel particles, do not use - moisture contamination has occurred. |
Next Steps
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Primary Action Request Pricing & Delivery for Your Project Volume
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Secondary Request SO-820 Sample Kit |
Secondary Discuss Your Potting Process |
FAQ
Q: What type of material is SO-820?
A: SO-820 is a two-component RTV silicone potting compound that cures at room temperature to a flexible, flame-retardant elastomer. It is designed for full encapsulation of electronic components - not surface sealing.
Q: What is the pot life and why does it matter for my process?
A: Approximately 20 minutes at 25°C. This defines the total available time for mixing, vacuum de-air, and controlled filling. For automated dispensing, verify that the complete cycle time - including de-air - fits within the working time before finalizing line parameters.
Q: Why is vacuum de-air recommended, and what pressure is needed?
A: Vacuum de-air removes micro-bubbles entrapped during mixing. Internal voids in the cured elastomer reduce dielectric strength and create partial discharge sites under sustained high voltage. The recommended vacuum range is 10–20 torr, applied immediately after mixing and before dispensing.
Q: Why must I measure by weight, not volume?
A: Part A (density 1.57 g/cm3) and Part B (density 0.96 g/cm3) have a significant density difference. A 4:1 volume mix would deliver a substantially different stoichiometric ratio than 4:1 by weight, resulting in off-ratio cure with reduced hardness, lower dielectric strength, and potential surface tack. Always use a calibrated electronic scale.
Q: What are the dielectric and thermal properties in the context of my application?
A: Dielectric strength: ~20 kV/mm (ASTM D-149). Volume resistivity: 1 x 10^14 ohm-cm. Thermal conductivity: 0.54 W/m·K. These are measured on fully cured, void-free samples. Internal voids from inadequate de-air or incomplete filling will reduce effective dielectric performance.
Q: What flame rating does SO-820 carry, and how do I reference it in safety documentation?
A: UL 94 V-0, File No. E120665. The certification covers white (WT) and black (BK) color variants at 3.5–3.9 mm minimum thickness. The UL file can be verified at iq.ul.com using E120665. When referencing SO-820 in end-product safety documentation, cite the file number and material producer: Fong Yong Chemical Co., Ltd.
Q: How should SO-820 be stored, and what is the shelf life?
A: Store sealed, dry, below 25°C, away from moisture and direct light. Part A shelf life: 9 months (unopened). Part B shelf life: 6 months (unopened). Part B reacts with atmospheric moisture - reseal immediately after each use. See the Part B Storage & Handling section above for full handling guidance.
Q: What substrates does SO-820 adhere to without a primer?
A: SO-820 exhibits good adhesion to most materials under standard conditions, including metals, glass, ceramics, and PCB substrates (FR-4, polyimide) without primer. Surface preparation with IPA is required to remove oil, flux, and particulates. Water-based cleaners or soaps should not be used.
Q: I have the SO-820 sample kit. How should I evaluate it?
A: A structured three-stage evaluation is recommended: Stage 1 - Mix and flow verification: Mix a small batch at 4:1 by weight. Observe flow behavior and leveling on a flat surface. Confirm the material stays fluid for at least 15 minutes after mixing. Check that the mixed viscosity allows filling without forced injection. Stage 2 - Cure and hardness check: Pour a 3 mm layer into a mold or flat container. Cure at room temperature (~25°C) for 24 hours. Check Shore A hardness - target: 30 ±5. If significantly softer or tacky, recheck mix ratio accuracy. Stage 3 - Adhesion pull test on your substrate: Apply SO-820 to your actual PCB or enclosure substrate after IPA cleaning. Cure 24 hours. Attempt peel or pull separation by hand. Good adhesion should resist separation without interface failure. If delamination occurs at the substrate interface, verify surface cleanliness before concluding adhesion incompatibility.
Q: Is SO-820 suitable for my application?
A: A: SO-820 is typically evaluated when full encapsulation, controlled filling behavior, and internal insulation performance are required within enclosed electronic assemblies. Final suitability should be verified through sample testing under actual process conditions.
The data presented on this page are based on laboratory testing conducted under standard conditions and are provided for reference only. Properties of the cured material are dependent on process
conditions including mix ratio accuracy, de-air completeness, substrate surface preparation, and environmental cure conditions. Final suitability determination for any specific application is the customer's sole responsibility. Fong Yong Chemical Co., Ltd. makes no warranty, expressed or implied, and assumes no liability for application outcomes.
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