Low-Exotherm Clear Epoxy Potting Compound for Large Electronic Components | E-190 / H-190 | Fong Yong

Fong Yong Chemical Co., Ltd. is one of the leading manufacturers and suppliers of Low-Exotherm Clear Epoxy Potting Compound for Large Electronic Components | E-190 / H-190 | Fong Yong in Taiwan. With abundant experience, we warmly welcome you to buy high quality customized products at competitive price from our factory. If you have any enquiry about quotation, please feel free to email us.

 

What Is E-190/H-190?

E-190/H-190 is a two-component, low-exotherm clear epoxy potting compound manufactured by Fong Yong Chemical Co., Ltd., an IATF 16949 certified manufacturer, in Taiwan, formulated for large-component and large-volume electronic potting where heat generated during cure is a process design consideration. It is also the only Shore D 80 rigid clear formula in the Fong Yong potting range with a published glass transition temperature (Tg 75°C) and documented service temperature range (−30°C to +90°C) - making it the correct specification when temperature limits must appear in procurement or design documentation. Mix ratio is 100:40 by weight (E-190 resin : H-190 hardener), or 2:1 by weight for metered dispensing systems. Fully cured (80°C × 2 hours or 7 days at room temperature): Shore D 80 hardness, dielectric strength 18 KV/mm, volume resistivity 1.2×10¹⁶ Ω·cm.

 

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Standard rigid epoxy potting compounds generate heat during cure. In small potting volumes - connectors, sensors, compact PCB assemblies - this exothermic heat dissipates before it affects the component. In large transformers, large inductors, and high-volume casting applications, the same reaction in a greater mass of resin creates a peak temperature that the component, substrate, or assembly may not tolerate. Selecting a formula without accounting for cure-time exotherm in large-volume applications introduces a thermal stress variable that is absent in small-volume work.

E-190/H-190 is the low-exotherm formula in the Fong Yong clear epoxy potting range, formulated for larger component and large-volume potting where exothermic heat during cure is a process design consideration. It is also the only Shore D 80 rigid clear formula in this range with a published glass transition temperature (Tg 75°C) and documented service temperature range (-30°C to +90°C) - the appropriate specification when application temperature limits must be recorded in a procurement or design document.

 

Choose E-190/H-190 When:

• Potting volume or component size is large enough that exothermic heat during cure may stress the component or cause dimensional distortion in the finished assembly
• Procurement or design specifications require a documented service temperature range (-30°C to +90°C) or published Tg value (75°C)
• High electrical insulation is required - volume resistivity 1.2×10¹⁶ Ω·cm, dielectric strength 18 KV/mm

 

For standard small-to-medium volume potting with no exotherm concern and no temperature documentation requirement → E-700/H-190 is the default choice.

 

Where E-190/H-190 Is Specified

E-190/H-190 is specified where the component size, potting volume, or casting geometry is large enough that the exothermic reaction during cure requires active design consideration - and where a documented service temperature range is a specification requirement.

Primary applications include:

Large transformer cores and inductor housings requiring deep potting or high resin volume per unit

Large sensor housings and industrial electronic modules where enclosed potting geometry limits heat dissipation during cure

High-volume casting or batch potting applications where a large mass of mixed resin cures simultaneously

Electronic assemblies where procurement or qualification specifications require a stated service temperature range (-30°C to +90°C) or Tg value (75°C)

 

Typical Application Scenarios

Application	Why E-190/H-190
Large transformer / inductor potting	Large potting volume generates significant exothermic heat during cure - low-exotherm formulation reduces peak cure temperature and thermal stress on windings
Large sensor housing encapsulation	Enclosed potting cavity limits heat dissipation; low-exotherm design prevents thermal overstress on sensor elements during cure
Industrial electronic module with documented temperature specification	Service temperature -30°C to +90°C and Tg 75°C published in TDS - provides specification documentation basis unavailable from E-700/H-190

 

Low Exothermic Cure: What It Means for Larger Component Potting

All epoxy potting compounds generate heat during cure. The crosslinking reaction between resin and hardener is exothermic - heat output is intrinsic to the chemistry, not a defect. In small potting volumes, this heat releases into the surrounding environment before it accumulates to a level that affects the component. The surface-to-volume ratio is high, and dissipation is fast.

 

In large potting volumes, the same chemistry produces a proportionally larger total heat output, while the surface-to-volume ratio decreases. Heat accumulates in the interior of the curing mass faster than it can escape through the outer surfaces. The resulting peak temperature inside a large curing pour can be substantially higher than the ambient temperature - and can remain elevated for an extended period depending on component geometry and production environment conditions.

 

The consequences of unmanaged cure-time exotherm in large-component applications include:

Thermal overstress on encapsulated components during the cure cycle - particularly relevant for temperature-sensitive windings, magnetic cores, and film capacitors

Thermal stress at the epoxy-substrate interface, driven by differential expansion during the exothermic temperature peak, which may reduce adhesion or introduce micro-cracking

Dimensional distortion in the finished potted assembly if the cured geometry reflects stress from an elevated-temperature cure state

 

E-190/H-190 is formulated for a low exothermic cure - the design characteristic that makes it the correct specification for applications where component size or potting volume creates an exotherm management requirement. For small-to-medium volume potting where these conditions do not apply, a general-purpose formula is the appropriate choice.

 

Application note: The threshold at which exotherm becomes a design consideration depends on potting volume, component geometry, ambient temperature, and ventilation of the production environment. Customers should evaluate E-190/H-190 under their specific production conditions if component size or casting volume suggests exotherm may be a factor.

 

Figure 1. In small potting volumes, cure-time exotherm dissipates without affecting the component. In large-volume applications, heat accumulates inside the curing mass - where a low-exotherm formulation becomes a process requirement.

 

Documented Service Temperature Range: -30°C to +90°C (Tg 75°C)

E-190/H-190 carries a documented use temperature range of -30°C to +90°C, supported by a measured glass transition temperature (Tg) of 75°C. This makes it the appropriate specification when temperature limits must be recorded in procurement or design documentation.

 

What Tg 75°C means. The glass transition temperature is the point at which the cured epoxy polymer transitions from a rigid, glassy state toward a more compliant behavior. For E-190/H-190, this transition occurs at 75°C. The -30°C to +90°C range covers standard industrial electronics operating environments - from cold-start outdoor conditions to elevated temperatures inside enclosed power assemblies and panels. Actual operating temperature at the encapsulant depends on component heat generation, assembly geometry, and installation environment - customers should verify that system operating temperature remains within this range under their specific conditions.

 

When documented temperature limits are a specification requirement. For applications where procurement documentation, quality records, or design qualification require a stated service temperature - including industrial control equipment, power electronics, and assemblies subject to environmental testing per IEC or similar standards - E-190/H-190 provides the specification basis with its stated Tg and use temperature range. For applications without either requirement, the selection guide covers all six formulas by application condition.

 

Precision note on property values at temperature. The mechanical and electrical property values in the specifications - Shore D 80, dielectric strength 18 KV/mm, volume resistivity 1.2×10¹⁶ Ω·cm - are measured under standard test conditions. These values do not represent retained performance at the upper limit of the service temperature range. For applications where property retention at elevated operating temperature must be quantified, testing under actual service conditions is required.

 

Cure Conditions and Mix Ratio

E-190/H-190 cures at room temperature or with heat. Both options produce equivalent cured properties under the published conditions.

Room temperature cure: Full cure in 7 days. Gel time 3–24 hours at ambient temperature. For large-component potting where oven heating would add external thermal stress on top of the curing exotherm - RT cure eliminates this combined thermal load. Also appropriate for production lines without oven infrastructure handling transformer cores, motor stators, or other large assemblies where section geometry makes heat-cure cycle management complex.

 

Heat cure: 80°C × 2 hours. Single-stage cure at one temperature - appropriate for production lines where shortened cycle time is required.

Pot life is 60 minutes at 25°C (60g sample). Actual pot life is affected by batch size, ambient temperature, and dispensing system conditions.

 

Two mix ratio options. E-190/H-190 is supplied with two valid mix ratios per TDS:

100:40 by weight (E-190 resin : H-190 hardener) - traditional weight-based measurement, equivalent to a 2.5:1 ratio

2:1 by weight (E-190 resin : H-190 hardener) - convenient for metered dispensing systems configured at a 2:1 pump ratio

Both ratios achieve full cure under the published cure conditions. Select the ratio appropriate to your production equipment. Accurate weighing or metering is required for both options - incomplete mixing or incorrect ratio will affect cure quality.

 

Electrical Insulation and Environmental Properties

E-190/H-190 provides the following electrical insulation properties:

Dielectric strength: 18 KV/mm

Volume resistivity: 1.2×10¹⁶ Ω·cm

 

These values are measured under standard test conditions. For assemblies operating at elevated temperature, electrical insulation performance at operating temperature is the relevant specification - testing under actual service conditions is required.

 

Mechanical properties: flexural strength 5,400 psi, tensile strength 9,000 psi, compressive strength 7,100 psi. Shore D 80 provides rigid mechanical encapsulation. Cured surface is high-gloss.

 

Environmental protection: E-190/H-190 provides moisture and chemical resistance as a cured encapsulant. Suitability for specific environmental exposure conditions - including humidity cycling, chemical exposure, or outdoor installation - should be verified under the actual conditions of the application.

 

Not Sure Which Formula Your Application Needs?

E-190/H-190 is the right choice when exotherm is a design concern or when a documented service temperature range is required. For standard small-to-medium volume electronic potting with no special requirement, E-700/H-190 is the default. Use the selection guide to route all six formulas by application requirement:

→ Clear epoxy potting compound selection guide - four variables, six formulas

 

Manufactured in Taiwan Under IATF 16949 Quality Standards

E-190/H-190 is produced by Fong Yong Chemical Co., Ltd. at its manufacturing facility in Taiwan. Fong Yong holds IATF 16949 certification - the international quality management system standard for automotive supply chains - governing incoming material controls, process traceability, production consistency, and quality documentation across its resin manufacturing operations.

 

Procurement teams specifying E-190/H-190 typically do so because application documentation requires stated material properties - service temperature range, Tg value, dielectric strength. The same documentation requirement that drives Tg specification in the material datasheet applies to the manufacturer: IATF 16949 certification means the processes producing E-190/H-190 are subject to audit-ready quality controls and traceability. For industrial, power electronics, or automotive supply chain applications where both material specifications and supplier quality documentation are required, this provides the manufacturer-level foundation to support those requirements.

 

Fong Yong has manufactured epoxy potting and encapsulant systems in Taiwan for over 40 years. Full TDS documentation, batch records, and application engineering support are available on request.

 

Work With Fong Yong's Technical Team

Request a sample, obtain TDS documentation, get a quotation, or discuss your application with our engineering team.

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Related Knowledge

How to Select a Clear Epoxy Potting Compound for Electronic Components: Four Variables That Determine the Right Formula

Why Potted Electronic Components Fail: Cracking, Delamination, and Moisture Ingress

 

Technical content prepared by: Fong Yong Chemical Co., Ltd. Technical Team | Source: TDS E-190/H-190, revision 2023/04/06

 

 

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