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Hysol MG21F-02 | Black Epoxy Mold Compound

Harmonization Code : 3907.30.00.90 |   Polyacetals, other polyethers and epoxide resins, in primary forms; polycarbonates, alkyd resins, polyallyl esters and other polyesters, in primary forms : Epoxide resins : Other
Main features
  • Amazing HTRB performance
  • Excellent adhesion to Sn, Si and Cu
  • Encapsulation of low voltage diodes

Product Description

Hysol MG21F-02 is a high productivity, low cost, epoxy molding compound, designed specifically for high volume encapsulation of low voltage diodes and small signal transistors. It offers excellent reliability & HTRB data and has been used for diode bridge, axial diodes, diode metal electrode leadlesss face (MELF) and other high voltage and discrete semiconductor packages. It offers excellent adhesion to Sn, Si and Cu and amazing HTRB performance.

Hysol MG21F-02 performs very well during high-temperature reverse bias testing for devices running up to 800V and at 150°C. The largest cause of failure of epoxy molding compounds on these devices is the result of gate leakage and then ultimately catastrophic run-away current when tested under bias at temperature. MG21F-02 performs very well under these conditions.

Hysol MG21F-02 was developed many years ago, but is still one of the best EMC on the market for diodes, bridges and high voltage diodes. Many competitors have tried and failed to compete against this MG21F-02. Those that did manage to meet the same performance targets as the MG21F-02 did so at prices that were nearly twice that of the MG21F-02, leaving this product leading with an excellent price/performance correlation. Typical applications and uses of MG21F-02 include but are not limited to  28, 28 and 56 pin DL TSSOP, SOT, SOIC, PDIP and other power discrete and high voltage semiconductor packages.

We are currently developing the Green version of this product, to ensure it does not contain TBBP-A or antimony trioxide while also maintaining its flame retardant and electrically stable properties. Contact us for more information.

Product Family
40 mm
40 gr 31 gr
15 kg

Catalog Product

Unlike other products we offer, the products listed on this page cannot currently be ordered directly from the website.
Shipping in 8 - 12 weeks Shipping in 8 - 12 weeks

Technical Specifications

General Properties
The color
Filler Content 71 %
Specific Gravity
Specific Gravity
Specific gravity (SG) is the ratio of the density of a substance to the density of a reference substance; equivalently, it is the ratio of the mass of a substance to the mass of a reference substance for the same given volume.

For liquids, the reference substance is almost always water (1), while for gases, it is air (1.18) at room temperature. Specific gravity is unitless.
Shelf Life
Shelf Life
Shelf life is the amount of time after manufacturing that a product is guaranteed to retain its properties.

It differs vastly per product and it is based on temperature and storage conditions.

The properties can be guaranteed for the temperature and time range indicated on the TDS since those are the ones tested to be the best for the product.
Shelf Life @ 5°C 365 days
Chemical Properties
Ionic Content
Chloride (Cl-)
Chloride (Cl-)
The amount of Chloride (Cl-) ion extracted from the product in parts per million (ppm)
6 ppm
Potassium (K+)
Potassium (K+)
The amount of Potassium (K+) ion extracted from the product in parts per million (ppm)
1 ppm
Sodium (Na+)
Sodium (Na+)
The amount of Sodium (Na+) ion extracted from the product in parts per million (ppm)
4 ppm
Moisture Absorption
Moisture Absorption
Moisture absorption shows the capacity of a polymer to absorb moisture from its environment.

Absorbed moisture can reduce the glass transition temperature and strength of a polymer and can also result in popcorning, unreliable adhesion or voids in the bond line due to moisture desorption or entrapment.

Moisture absorption should always be mentioned with the test conditions to provide a meaningful frame of reference.
Moisture absorption - 168h @ 85ºC | 85% RH 0.22 %
Mechanical Properties
Flexural Modulus
Flexural Modulus @ 21°C
Flexural Modulus @ 21°C
Flexural Modulus taken at 21°C
13,726 N/mm2
Flexural Modulus @ 25°C 14,710 N/mm2
Flexural Modulus @ 260°C
Flexural Modulus @ 260°C
Flexural Modulus taken at 260°C
1,268 N/mm2
Flexural Strength
Flexural Strength @ 25°C
Flexural Strength @ 25°C
Flexural strength, also known as modulus of rupture, or bend strength, or transverse rupture strength is a material property, defined as the stress in a material just before it yields in a flexure test. This is the flexural strength tested at Room Temperature, 25°C
127 N/mm2
Hardness is a dimensionless quantity. There is no direct relationship between measurements in one scale and their equivalent in another scale or another hardness test.
Hot Hardness, Shore D @ 175°C / 347°F after 90 seconds 85
Molded Shrinkage 0.23 %
Water Extract Data
Water Extract Data
Water Extract Data, 20hrs water boil
pH of extract 4.5
Storage (DMA) Modulus
Storage (DMA) Modulus @ 175°C 9,416 N/mm2
Storage (DMA) Modulus @ 25°C 14,285 N/mm2
Storage (DMA) Modulus @ 260°C 1,308 N/mm2
Electrical Properties
Dielectric Constant
Dielectric Constant
Dielectric Constant (k), commonly known as relative permittivity, is a number relating the ability of a material to carry alternating current to the ability of vacuum to carry alternating current.

It determines the ability of an insulator to store electrical energy and is the ratio of electric permeability in vacuum against the electric permeability of a material.

The lower the dielectric constant (κ) and dissipation factor, the less energy is absorbed from an electric field, making it a much better insulator.

It is a dimensionless property that can be affected by various factors such as the
thickness uniformity of a material, insufficient contact between the sample and electrodes, water adsorption and contact resistance.
Dielectric Constant @ 25 ˚C/1000 kHz 3.6
Volume Resistivity
Volume Resistivity
Volume resistivity, also called volume resistance, bulk resistance or bulk resistivity is a thickness dependent measurement of the resistivity of a material perpendicular to the plane of the surface.
2.0x1016 Ohms⋅cm
Thermal Properties
Coefficient of Thermal Expansion (CTE)
Coefficient of Thermal Expansion (CTE)
CTE (Coefficient of thermal expansion) is a material property that is indicative of the extent to which a material expands with a change in temperature. This can be a change in length, area or volume, depending on the material.

Knowing the CTE of the layers is helpful in analyzing stresses that might occur when a
system consists of an adhesive plus some other solid component.
Coefficient of Thermal Expansion (CTE), α1
Coefficient of Thermal Expansion (CTE), α1
CTE α1 (alpha 1) is the slope of the Coefficient of thermal expansion in a temperature range below the Glass transition temperature (Tg).

It explains how much a material will expand until it reaches Tg.
21 ppm/°C
Coefficient of Thermal Expansion (CTE), α2
Coefficient of Thermal Expansion (CTE), α2
CTE α2 (alpha 2) is the slope of the Coefficient of thermal expansion in a temperature range above the Glass transition temperature (Tg).

It explains the extent to which a material will expand after it passes Tg.
62 ppm/°C
Gel Time
Gel Time
Gel time is the time it takes for a material to reach such a high viscosity (gel like) that it is no longer workable.

It is usually measured for different temperature conditions and even though it does not refer to full cure it is advisable to never move or manipulate the material after it reached its gel time since it can lose its desired end properties.
Gel Time @ 175°C / 347°F 22 s
Glass Transition Temperature (Tg)
Glass Transition Temperature (Tg)
The glass transition temperature for organic adhesives is a temperature region where the polymers change from glassy and brittle to soft and rubbery. Increasing the temperature further continues the softening process as the viscosity drops too. Temperatures between the glass transition temperature and below the decomposition point of the adhesive are the best region for bonding.

The glass-transition temperature Tg of a material characterizes the range of temperatures over which this glass transition occurs.
179 °C
Thermal Conductivity
Thermal Conductivity
Thermal conductivity describes the ability of a material to conduct heat. It is required by power packages in order to dissipate heat and maintain stable electrical performance.

Thermal conductivity units are [W/(m K)] in the SI system and [Btu/(hr ft °F)] in the Imperial system.
0.7 W/m.K
Spiral Flow
Spiral Flow @ 175°C 65 cm
UL94 Rating
UL94 @ 1/8 inch V0
Curing Conditions
Curing Time
Curing Time @ 175°C / 347°F (Automold) 50 - 70 s
Curing Time @ 175°C / 347°F (Conventional Mold) 70 - 90 s
Mold Temperature 160 - 190 °C
Preheat Temperature 75 - 95 °C
Transfer Pressure 35 - 105 kg/cm2
Transfer Time 12 - 25 s
Post Mold Cure
Post Mold Cure @ 175°C / 347°F 2 - 6 hrs

Additional Information

Here's a rough comparison of MG21F-02 with our new, Green formulations.

Judging from the "Ionic conductivity VS Temperature figure", halogen-free products GR21F-02, GR21F-02F4, GR21F-02F4A and GR21F-02F4B have similar electrical stability as MG21F-02 up to 200℃.








Formula Enhancement

Flame Retardant

TBBP-A & Antimony Trioxide

Not Contained

Green Flame Retardant X

Green Flame Retardant X+

Green Flame Retardant X+

Ion Capture

Not contained

Not Contained

Ion Capture A

Ion Capture B

Ion Capture A

Ion Capture B

Ion Capture A+




UL94 V-0 (1/8 inches)


Improved Electrical Stability




Customer reliability tests - Not Hysol Specifications


Diode type: TVS 500V/1,5μA

  • Standard Assembly process
  • HTRB test / Reliability
  • Temperature: 140°C
  • Reverse Bias: 375V
  • Duration: 24h

Compound / Colour Code

Molding Temperature (°C)

Transfer Time (sec)

Curing Time (sec)

Pre-heating (sec)

Post-Curing (h)

Product A




25 (0.4A)

8 @ 175°C





24 (0.4A)

6 @ 175°C