Harmonization Code : 3920.99.28.90 |   Other plates, sheets, film, foil and strip, of plastics, non-cellular and not reinforced, laminated, supported or similarly combined with other materials ; Of other plastics ; Other; Other
Main features
  • Reworkable
  • Flexible
  • Thermally conductive

Product Description

LOCTITE ABLESTIK 561K is a white epoxy film designed for substrate attach and heat sink bonding. This adhesive film is designed for bonding materials with severely mismatched coefficients of thermal expansion. All data and results will vary with different thicknesses.

LOCTITE ABLESTIK 561K is a reworkable assembly film that passes NASA outgassing standards. If you require a low temperature cure  you can consider LOCTITE ABLESTIK 566K. It is mainly used for substrate attach and heat sink bonding and has a glass fabric carrier.


Cure Schedule

  • 30min @150°C
  • 2 hours @ 125°C
Product Family
0.10 0.125
12 x 12 inch sheet

Catalog Product

Unlike other products we offer, the products listed on this page cannot currently be ordered directly from the website.

Technical Specifications

General Properties
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 @ -40°C 365 days
Work life @25°C
Work life @25°C
Work life is the amount of time we have to work with a material until it is no longer able to be easily worked and applied on a substrate.

It is based on the change in viscosity and it can rely on the application requirements.
4392 hours
Chemical Properties
Ionic Content
Chloride (Cl-)
Chloride (Cl-)
The amount of Chloride (Cl-) ion extracted from the product in parts per million (ppm)
110 ppm
Potassium (K+)
Potassium (K+)
The amount of Potassium (K+) ion extracted from the product in parts per million (ppm)
9 ppm
Sodium (Na+)
Sodium (Na+)
The amount of Sodium (Na+) ion extracted from the product in parts per million (ppm)
35 ppm
Moisture absorption 0.9 %
Water Extract pH 8
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 @ 1000 kHz 5.7
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.
9.1x1012 Ohms⋅cm
Mechanical Properties
Tensile Modulus
Tensile Modulus
Tensile modulus is a mechanical property that measures the stiffness of an elastic material. It is the slope of stress / strain curve of a material under direct tensile loading.

It can be used to predict the elongation or elastic deformation of an object as long as the stress is less than the tensile strength of the material. Elastic deformation is caused by stretching the bonds between atoms and the deformation can be reversed when the load is removed.

Tensile modulus is affected by temperature and is an important engineering attribute since we generally want to keep elastic deformation as small as possible.
Tensile Modulus @-65°C 6,138 N/mm2
Tensile Modulus @150°C 2,000 N/mm2
Tensile Modulus @25°C 4,345 N/mm2
Tensile Modulus @250°C 1,862 N/mm2
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.
85 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.
300 ppm/°C
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.
55 °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.
0.9 W/m.K

Additional Information

How does ABLESTIK 561K compares to ABLESTIK 566K?

The storage temperature of both materials is as low as -40 °C to guarantee its material properties over a longer range of time.
The 561K is a great reference material that can be stored at -40 °C for 12 months but can also be stored at ambient (25 °C) for up to 6 months without loss of performance.
The difference with 561K however, in the higher minimum cure schedule of 125 °C for 2 hours.
The 566K material  can cure at 100 °C but this is achieved by an increased catalyst load making the material more reactive, giving it shorter shelf life. (We would expect -20 °C storage to be sufficient for the 566K for 3-6 months)

Essentially you end up with two options:

  • Use 561K with 6 months storage at 25 °C and accept a higher 125 °C cure
  • Use 566K with 3-6 months storage at -20 °C and cure at 100 °C