COOLTHERM 6403

Harmonization Code : 3910.00.00.90 | Silicones in Primary Forms; Others

COOLTHERM 6403

Main features

  • 900 cP Mixed Viscosity
  • 45-Minute 25 deg C Cure
  • 50 to 120 deg C Service Range

Product Description

Circalok™ 6403 A SLW / B Urethane Encapsulant is a general-purpose, two-component urethane system for electrical and electronic encapsulation applications requiring fast cure and resistance to mechanical shock. The amber liquid components mix at a 22:10 resin-to-hardener ratio by weight and produce a mixed viscosity of 900 cP at 27 °C. The encapsulant can be poured or applied with automatic meter/mix/dispense equipment and cures in 30–45 minutes at 25 °C or 5–10 minutes at 100 °C. Once cured, it provides electrical insulation, moisture resistance, hydrolytic stability, and an operating temperature range of -50 to 120 °C.

Key features

  • Low mixed viscosity: Provides a typical mixed viscosity of 900 cP at 27 °C for pouring or automated meter/mix/dispense application.
  • Fast, heat-accelerated cure: Cures in 30–45 minutes at 25 °C or 5–10 minutes at 100 °C, with complete cure in 2–3 days at 25 °C.
  • Electrical and environmental protection: The cured urethane provides electrical insulation, moisture resistance, and hydrolytic stability.

Applications / Suitable for

  • General-purpose electrical and electronic encapsulation
  • Encapsulated assemblies requiring fast cure and resistance to mechanical shock
  • Parts and devices operating from -50 to 120 °C
Product Family

COOLTHERM 6403

Catalog Product

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TDS, SDS & Technical Documents

Technical Specifications

General Properties
ColorColor
Amber Liquid
Physical Properties
Viscosity (Part A)Viscosity (Part A)
750 mPa.s
Viscosity (Part B)Viscosity (Part B)
1200 mPa.s
Electrical Properties
Dielectric StrengthDielectric Strength
0.6 kV/mm
Volume ResistivityVolume Resistivity
1 x 10^14 Ohms⋅cm

Additional Information

Technical properties

As-supplied / before-processing properties

Typical properties of the separate components and mixed encapsulant before cure. Values are not intended for specification purposes.

Property Value Unit Method / condition
Appearance Amber liquid 6403 A SLW resin, 6403 B hardener, and mixed material
Mix ratio 22:10 By weight 6403 A SLW resin : 6403 B hardener
Viscosity — resin 750 cP 6403 A SLW resin at 27 °C; test method not stated
Viscosity — hardener 1,200 cP 6403 B hardener at 27 °C; test method not stated
Viscosity — mixed 900 cP Mixed material at 27 °C; test method not stated
Specific gravity 0.96 / 1.19 / 1.04 Resin / hardener / mixed material; test conditions not stated
Gel time 10–15 minutes Mixed material; test temperature and method not stated
Shelf life 6 months Each component, from date of manufacture; stored at 25–40 °C in the original unopened container
Technical properties

After-processing / final-state properties

Typical properties of Circalok 6403 A SLW / B after mixing and cure. Values are not intended for specification purposes.

Property Value Unit Method / condition
Cure time 30–45 minutes At 25 °C; complete cure in 2–3 days at 25 °C
Heat-accelerated cure time 5–10 minutes At 100 °C after the material reaches the target temperature
Operating temperature range -50 to 120 °C Parts and devices; retained-property data across the full range are not stated
Hardness 80 Shore A Cured material; test method and cure condition not stated
Tensile strength 1,935 psi Cured material; test method and cure condition not stated
Dielectric strength 600 V/mil Cured material; specimen thickness and test method not stated
Volume resistivity 1 × 1014 Ω·cm ASTM D257 at 25 °C
Dielectric constant 3.6 At 25 °C and 1 kHz

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