company tower banner
MG Chemicals Company Logo

MG Chemicals 834B - Black Flame Retardant Epoxy

834B potting and encapsulating compound is a black, flame retardant, thermally conductive two-part epoxy that offers extreme environmental, mechanical and physical protection for printed circuit boards and electronic assemblies. This product is designed for applications where thermal management and self-extinguishing are critical. It also provides excellent electrical insulation and protects components from static discharges, vibration, abrasion, thermal shock, environmental humidity, salt water, fungus, and many harsh chemicals. This epoxy has a convenient 2:1 volume mix ratio, making it compatible with most dispensing equipment. 834B can be cured at room temperature or higher.

Product Type: 2K (2 component) Sealant, Epoxy Sealant, Potting Compound

Compatible Substrates & Surfaces: Ceramic, Composites, Glass, Metal, Plastics

Cure Method: Air Dry

Chemical Family: Epoxy & Epoxy Derivatives

  • TypeDocument Name
View All Documents

Knowde Enhanced TDS

Identification & Functionality

Features & Benefits

Labeling Claims
Features & Benefits
  • Meets UL 94V-0 standard—flame retardant
  • Convenient 2A:1B volume mix ratio
  • Thermal conductivity of ~0.8 W/(m·K)
  • Low exotherm
  • Very high compressive and tensile strength
  • Excellent adhesion to a wide variety of substrates including metals, composites, glass, ceramics, and
  • many plastics
  • Excellent electrical insulating characteristics
  • Broad service temperature range of -40 to 175 °C (-40 to 347 °F)
  • Contains non-halogenated flame-retardant fillers
  • Solvent-free
Compatibility
Adhesion - As seen in the substrate adhesion table, 834B epoxy adheres to most plastics and metals used to house printed circuit assemblies; however, it is not compatible with contaminants like water, oil, or greasy flux residues that may affect adhesion. If contamination is present, first clean the surface to be coated with MG Chemicals 824 Isopropyl Alcohol.

Applications & Uses

Compatible Substrates & Surfaces
Cure Method
Application Instructions
  1. Scrape settled material free from the bottom and sides of the part A container; stir contents until homogenous.
  2. Scrape settled material free from the bottom and sides of the part B container; stir contents until homogenous.
  3. Measure 2 parts by volume of the pre-stirred part A, and pour into the mixing container. Ensure all contents are transferred by scraping the container.
  4. Measure 1 part by volume of the pre-stirred part B, and pour slowly into the mixing container while stirring. Ensure all contents are transferred by scraping the container.
  5. Thoroughly mix parts A and B together.
  6. Let sit for 15 minutes to de-air. -or- Put in a vacuum chamber at 25 inHg for 2 minutes to de-air.
  7. If bubbles are present at the top, break and stir them gently with the mixing paddle.
  8. Pour the mixture into a container holding the components to be protected.
  9. Close the part A and B containers tightly between uses to prevent skinning.

 

Attention!

Mixing >1 kg at a time decreases working life and can lead to a flash cure. Limit the size of hand-mixed batches. For large production volumes, contact MG Chemicals Technical Support for assistance.

Properties

Flame Rating
Physical Properties
ValueUnitsTest Method / Conditions
Compressive Strength ⁽ᵃ⁾74 (11,000)mPa (psi)ASTM D 695
Density (at 25°C, 77°F)1.59g/mLASTM D 1475
FlammabilityMeets 94 V-0UL 94
Hardness D85Shore D Durometer
Lap Shear Strength (ABS) ⁽ᵃ⁾1.8 (260)mPa (psi)ASTM D 1002
Lap Shear Strength (Aluminum) ⁽ᵃ⁾11 (1600)mPa (psi)ASTM D 1002
Lap Shear Strength (Brass) ⁽ᵃ⁾17 (2500)mPa (psi)ASTM D 1002
Lap Shear Strength (Copper) ⁽ᵃ⁾11 (1600)mPa (psi)ASTM D 1002
Lap Shear Strength (Polycarbonate) ⁽ᵃ⁾2.2 (320)mPa (psi)ASTM D 1002
Lap Shear Strength (Stainless steel) ⁽ᵃ⁾8.2 (1200)mPa (psi)ASTM D 1002
Tensile Strength17 (2400)mPa (psi)ASTM D 638
Thermal Properties
ValueUnitsTest Method / Conditions
CTE (After Tg) ⁽ᵇ⁾ 107 (225)ppm/˚C (ppm/°F)ASTM E 831
CTE (Prior Tg) ⁽ᵇ⁾ 74 (165)ppm/˚C (ppm/°F)ASTM E 831
Glass Transition Temperature (Tg)56 (133)°C(°F)ASTM D 3418
Specific Heat Capacity (at 25°C, 77°F)1.5J/(g·K)ASTM E 1269 01
Thermal Conductivity (at 100°C, 212°F)0.72W/(m·K)ASTM E 1461 92
Thermal Conductivity (at 25°C, 77°F)0.79W/(m·K)ASTM E 1461 92
Thermal Conductivity (at 50°C, 122°F)0.59W/(m·K)ASTM E 1461 92
Thermal Diffusivity (at 25°C, 77°F)0.33mm2/sASTM E 1461 92
Typical Properties
ValueUnitsTest Method / Conditions
Working Life (at 22°C, 72°F)1h
Full Cure (at 100°C, 212°F)20minute
Full Cure (at 22°C, 72°F)72h
Full Cure (at 65°C, 149°F)2.5h
Full Cure (at 80°C, 176°F)1h
Electrical Properties
ValueUnitsTest Method / Conditions
Breakdown Voltage (at 2.4 mm)40,700 (40.7)V (kV)ASTM D 149
Breakdown Voltage (at 3.175 mm) [1/8"]47,000 (47)V (kV)Reference fit ⁽ᵃ⁾
Conductivity4.8 x 10⁻¹³S/cmASTM D 257
Dielectric Constant, k´ (at 1 MHz)3.1ASTM D 150-11
Dielectric Dissipation, D (at 1 MHz)0.01ASTM D 150-11
Dielectric Strength (at 2.4 mm)431 (17)V/mil (kV/mm)ASTM D 149
Dielectric Strength (at 3.175 mm) [1/8"]376 (14.8)V/mil (kV/mm)Reference fit ⁽ᵃ⁾
Resistivity2.1 x 10¹²Ω·cmASTM D 257
Temperature Properties
ValueUnitsTest Method / Conditions
Constant Service Temperature-40 to 175 (-40 to 347)°C(°F)
Intermittent Temperature Limit ⁽ᵃ⁾-50 to 200 [-58 to 392]°C(°F)
Storage Temperature of Unmixed Parts16-27 (61-81)˚C(˚F)
Uncured Properties
ValueUnitsTest Method / Conditions
Density1.57g/mL
Mix Ratio2:1Volume
Mix Ratio2.4:1Weight
Viscosity (at 25 ˚C, 77°F)16200 (16.2)cP (Pa·s)
Substrate Adhesion (In Decreasing Order)
Physical Properties Adhesion
Brass Stronger
Aluminum/Copper MG Chemicals 834B - Black Flame Retardant Epoxy - Substrate Adhesion (In Decreasing Order)
Steel
Fiberglass
Wood
Paper, Fiber
Glass
Rubber
Acrylic
Polycarbonate Weaker
Polypropylene Does not bond
Teflon™ Does not bond

 

Temperature Properties
a) Brookfield viscometer at 30 rpm with spindle LV S64
Cured Properties

Note: Specifications are for epoxy samples cured at 80 °C for 1 h and conditioned at ambient temperature and humidity.
a) To allow comparison between products, the dielectric strength was recalculated with the Tautscher equation fitted to 5 experimental values and extrapolated to a standard thickness of 1/8” (3.175 mm).
b) Coefficient of Thermal Expansion (CTE) units are in ppm/°C = in/in/°C × 10-6 = unit/unit/°C × 10-6.

Uncured Properties
Physical Properties Part A Part B
Viscosity at 25 °C (77 °F) 27500 cP [27.5 Pa·s] Brookfield viscometer at 100 rpm with spindle RV S07 2100 cP [2.1 Pa·s] Brookfield viscometer at 100 rpm with spindle RV S05
Density 1.69 g/mL 1.40 g/mL

 

Uncured Properties

a) Brookfield viscometer at 30 rpm with spindle LV S64

Cure Instructions

Room temperature cure:

  • Let cure at room temperature for 72 h.

 

Heat cure:

  • Put in oven at 65 °C [149 °F] for 1.5 h.
  • Put in oven at 80 °C [176 °F] for 1 h.
  • Put in oven at 100 °C [212 °F] for 20 min.

 

Attention!
Due to exothermic reaction, heat cure temperatures should be at least 25% below the maximum temperature the most fragile PCB component can tolerate. For larger potting blocks, reduce heat cure temperature by greater margins.

Regulatory & Compliance

Certifications & Compliance

Safety & Health

Safety & Health
Please see the 834B Safety Data Sheet (SDS) parts A and B for further details on transportation, storage, handling, safety guidelines, and regulatory compliance.

Packaging & Availability

Packaging and Supporting Products
Cat. No. Packaging Net Volume Net Weight Packaging Weight
834B-375ML 2 Bottle kit 375 mL [12.6 fl oz] 597 g [1.31 lb] 730 g [1.61 lb]
834B-2.7L 3 Can kit 2.7 L [2.85 qt] 4.30 kg [9.48 lb] 4.75 kg [10.5 lb]
834B-10.8L 3 Can kit 10.8 L [2.85 gal] 17.2 kg [37.9 lb] TBD
834B-60L 3 Can kit 60 L [15.8 gal] 95.6 kg [210 lb] TBD

Storage & Handling

Shelf Life
5 Years
Storage and Handling
Store between 16 and 27 °C [61 and 81 °F] in dry area, away from sunlight. Storage below 16 °C [61 °F] can result in crystallization. If crystallization occurs, reconstitute the product to its original state by temporarily warming it to between 50 and 60 °C [122 and 140 °F]. To ensure full homogeneity, stir the warm product thoroughly. Make sure to reincorporate all settled material, close the lid, and then let cool before use.