Harmonization Code : 3506.91.90.99 |   Prepared glues and other prepared adhesives, not elsewhere specified or included; products suitable for use as glues or adhesives, put up for retail sale as glues or adhesives, not exceeding a net weight of 1 kg ; Adhesives based on polymers of headings 3901 to 3913 or on rubber; Other ; Other
Main features
  • Electrical isolation
  • Thermally conductive
  • Bond metallic heat sinks

Product Description

LOCTITE SI 5404 is designed to bond metallic heat sinks, ceramic chips and circuit board substrates. LOCTITE SI 5404 applications include the bonding of various heat generating devices (power devices) to their respective heat sinks.

LOCTITE SI 5404 is designed to provide a strong bond between the device and its heat sink as well as low resistance to the flow of heat from the electronic device to the heat sink. A typical application would be the bonding of any power semiconductor, module, graphics processor or other heat generating device to a heat sink or metal enclosure in an electronics circuit.

LOCTITE SI 5404 is a "heavy paste" type of substance and that’s why extrusion rate is mentioned on TDS, instead of viscosity. This is a measurement of a certain amount per minute which will be squeezed out of the cartridge after applying pressure. If you need TC higher than 1 W/mK you might be interested in SI5406M RTV silicone with 1.5 W/mK.

Cure Schedule

  • 10 minutes for 150°C
  • 15 minutes for 130°C

IR or Convection oven

Product Family
30CC Syringe

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
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.
Mechanical Properties
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.
Durometer (Shore A) 55
Elongation is the process of lengthening something.

It is a percentage that measures the initial, unstressed, length compared to the length of the material right before it breaks.

It is commonly referred to as Ultimate Elongation or Tensile Elongation at break.
65 %
Tensile Strength
Tensile Strength
The tensile strength of a material is the maximum amount of tensile stress that it can withstand while being stretched or pulled before failure.

Some materials break very sharply, without plastic deformation, in what is called a brittle failure. Others, which are more ductile, including most metals, experience some plastic deformation and possibly necking before fracture.
Tensile Strength @ 21°C 1.3 N/mm2
Electrical Properties
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.
2.9x1014 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.
1.04 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.
-40 °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.
0.95 W/m.K

Additional Information


We are dealing with multiple materials in our lab. How should we approach Silicones? Any standards or methods?

We are not aware of any standards that deal with the compatibility of silicones and other adhesives. It is clear that silicones are bad for adhesion for non-silicone materials so you should try to avoid cross-contamination. We would keep these separate or apply silicone as the last step, if possible.


Regarding Pot life, this heat-curing silicone material is stable for days at temperatures below 30°C. We do not have specific test data on this.