NOMACON ™ KPTD-2

Thermally conductive electrical insulating elastic silicone sheet materials, gaskets and substrates NOMACON ™ KPTD-2

 

• The elasticity of the silicone ligament and the thermal conductivity of ceramic fillers in combination with a small thickness provide minimal thermal resistance
•  The dielectric properties of the structural components of the materials guarantee them high electrical strength
• Installation of electronic heat-generating components is carried out without the application of heat-conducting pastes, which guarantees reliability and electrical safety, and also reduces assembly time
• Thanks to the fiberglass reinforcement, the materials are resistant to mechanical damage in case of strong compression between the flat pressure surfaces of the housing and the radiator - a pressure of up to 40 MPa does not damage the material. At the same time, an elastic silicone base with high thermal conductivity fills the unevenness of the microrelief of the compressive surfaces, increasing heat transfer
• The materials are non-toxic, do not emit harmful substances during installation and operation, are not affected by substances used when cleaning printed circuit boards
• For ease of installation, the surface of the material is covered with a sticky adhesive layer (LC) or sticky positioning grease (LP). Sticky positioning grease has a reduced adhesive shear strength, which allows the glued gasket to be moved slightly over the pressure surface with little effort - position during installation

KPTD-2 materials are produced in the form of rectangular sheets, as well as in the form of gaskets cut from sheets of KPTD-2 material according to drawings agreed with consumers. Standardized sheet sizes when ordering 150x220, 160x220 and 160x700 mm. The permissible deviations of the length and width of the sheet, as well as the linear dimensions of the gasket, do not exceed ± 1.0 mm per 100 mm.

The normalized thickness of sheets (gaskets) when ordering is 0,17, 0,20, 0,25, 0,30, 0,45, 0,50, 0,75, 1,00, 1,50, 2,00 mm. The tolerance for sheet thicknesses is 5-10%, depending on the thickness.

Materials grade KPTD-2/1 are made by filling the silicone base with micropowders of highly purified oxide ceramics, recrystallized using a special technology at temperatures above 2000 ºС (α-Crystalen ™).

KPTD-2/2 grade materials are made on the basis of oxide and nitride ceramic micropowders, sintered using a unique technology in a highly purified nitrogen environment at temperatures above 1200 ° C (β-Crystalen ™).

Materials grade KPTD-2/3 are made on the basis of nitride ceramic micropowders.

Materials grade KPTD-2/1-VN they are made by maximally filling the silicone base with fractions of micro-powders of highly purified oxide ceramics with particles of the correct spherical shape.

Materials grade KPTD-2/2-VN they are made by maximally filling the silicone base with fractions of micro-powders of highly purified oxide ceramics with particles of regular spherical shape in combination with fractions of micro-powders of oxide and nitride ceramics.

NOMACON ™ KPTD-2 sheet materials are manufactured by the step-by-step contact injection molding method. In this case, the sheet material is a close-packed structure of uniform thickness with a sufficiently smooth and even surface. High technical and consumer properties of KPTD materials are achieved due to the following technological methods:

• maximum filling of the rubber base with micropowder with an optimal combination of various fractions of micropowders of a heat-conducting ceramic filler;
• application of specially developed heat-conducting dielectric micropowders α-Kristalen ™, β-Kristalen ™, fractions of oxide ceramics of regular spherical shape, as well as nitride ceramics of various fractional composition;
• obtaining under pressure a close-packed structure of a material homogeneous in thickness in the absence of pronounced internal gas cavities;
• use of reinforcing electrical insulating fiberglass base of minimum thickness;
• application of the technology of glossy calibration of the sheet surface in order to achieve maximum conformity to the pressing surfaces.

Specifications

Technical characteristics of sheet materials NOMACON ™ KPTD-2

Technical characteristics of sheet materials NOMACON ™ KPTD-2-VN

KPTD-2 materials have a service life at a temperature of plus 200 ° C for at least 2500 hours, at a temperature of plus 250 ° C for at least 1500 hours.
Type of climatic modification of KPTD materials in the state of polymerization B1.1 in accordance with GOST 15150.
The service life in products with placement category 4 in accordance with GOST 15150 is at least 10 years.

Heat conducting properties

Heat-conducting properties of gaskets made of KPTD-2 materials

To assess the heat-conducting properties of rubber, a mathematical model for calculating thermal resistance is used, presented above on the site page "DESCRIPTION - Thermal resistance of KPTD materials". In this case, the total specific thermal resistance to heat transfer R (see formula 2) includes thermal resistance at the boundary "heat-transfer contact surface - gasket surface" R_1S, thermal resistance depending on thickness δ and thermal conductivity λ gasket material δ / λ, as well as thermal resistance at the boundary "gasket surface - heat-receiving contact surface" R_2S.

It should be noted that due to the conformal surface and elasticity, the thermal resistance of KPTD-2 materials is stabilized even at a compression stress of 0.5-0.7 MPa (see the graph of the dependence of the specific thermal resistance on the compression stress). At a compression stress of up to 3.5 MPa, the change in the thickness of the KPTD-2 material due to compression can be calculated with sufficient accuracy by formula 5, taking into account dependence 10 of the section "DESCRIPTION - Elasticity (compressibility) of KPTD materials". When using a one-sided sticky layer or positioning grease, the total specific thermal contact resistance is reduced (see value R_0S ).

The table below shows the calculated values of thermal resistance of typical gaskets for various grades and thicknesses of KPTD-2 materials, obtained with the following values empirical coefficients:

• sheet material KPTD-2/1 R_S = 0.90 (K⋅ cm²) / W, R_0S = 0.58 (K⋅ cm²) / W, λ = 0.87 W / (m⋅K);
• sheet material KPTD-2/2 R_S = 1.03 (К⋅ cm²) / W, R_0S = 0.79 (K⋅ cm²) / W, λ = 1.14 W / (m⋅K);
• sheet material KPTD-2/3     R_S = 0.97 (К⋅ cm²) / W, R_0S = 0.67 (K⋅ cm²) / W, λ = 1.44 W / (m⋅K);

The above mathematical model for calculating the thermal resistance of sheet materials KPTD-2 at compressive stresses in the range of 0.5-1.7 MPa gives good convergence of the results provided that the requirements for compressive contact surfaces are met, which are presented in the section "Instructions for use".

Example 2.

The power element (diode), in order to remove the generated heat, is installed on an aluminum radiator through a heat-conducting electrical insulating gasket 2A4229 (TO-3) made of NOMAKON ™ KPTD-2 / 1-0.20 material. It is required to determine the thermal resistance of the gasket R_F to assess the sufficiency of heat dissipation, as well as to calculate the temperature difference ΔT between the diode body and the radiator at the value of the dissipated thermal power Q = 25 W.

1. According to the marking of the material, we take the initial thickness of the gasket δ₀ = 0.20 mm;
2. Determine the area of the contact surface of the gasket F = 7.99 cm²;
3. Accept values R_S = 0.90 (K⋅ cm²) / W, λ = 0.87 W / (m⋅K); for material KPTD-2/1;
4. Accept compression gasket stress σ = 0.7 MPa, elastic modulus E = 157.8 MPa / mm and calculate its residual thickness in compression using formula 5: δ = 0.196 mm;
5. We calculate the specific thermal resistance R = R_S + δ / λ, R = 3.15 (К⋅ cm²) / W;
6. Determine the thermal resistance of the gasket R_F according to formula 4: R_F = 0.394 K / W;
7. We calculate the temperature difference using formula 1: ΔT = R_F ⋅ Q ΔT = 9.85 ° C.

For example 2, when using the material KPTD-2 / 3-0.20-LK, we have:

R_0S = 0.67 (K⋅ cm²) / W, E = 157.8 MPa / mm, λ = 1.44 W / (m⋅ K), R = 2.03 (K⋅ cm²) / W, R_F = 0.254 K / W, ΔT = 6.35 ° C.

For example 2, when using the material KPTD-2M / 3-0.20, we have:

R_0S = 0.19 (K⋅ cm²) / W, E = 98.1 MPa / mm, λ = 1.44 W / (m⋅ K), R = 1.53 (K⋅ cm²) / W, R_F = 0.191 K / W, ΔT = 4.79 ° C.

Thermal Conductive Properties of Typical Gaskets

Thermal conductivity properties of standard gaskets made of NOMACON ™ KPTD-2 materials

Designation when ordering

Directions for use

1. Sheet materials KPTD-2 (KPTD-2M) and products made from them (gaskets and substrates) are used as delivered. Before use, remove the protective plastic film from the surface of the material.
2. Determine the required compression force of the contact surfaces between which the gasket is installed. It should be borne in mind that the nominal working compressive stress (MPa) determines the permissible relative deformation of the material sheet in the range from 10% to 50 % from its original thickness, at which the manufacturer guarantees the strength, electrical insulating and heat-conducting properties presented in the table "Technical characteristics".
3. The ultimate compressive stress determines the relative deformation of the material within the range of up to 50% from its original thickness at which there is no loss of elasticity, and subsequently, when the compressive stress is removed, the material is restored to its original thickness and retains its properties. Operation of gaskets made of KPTD-2 (KPTD-2M) materials when exceeding the limiting compression stress is not allowed.
4. The quality of the compressive surfaces (the device and the radiator must comply with GOST 265 in order to achieve the normalized heat transfer properties of the gasket. The roughness of the compressive surfaces should not exceed Ra = 0.63 μm in accordance with GOST 2789. The deviation of the geometry of the compression surfaces in terms of flatness and parallelism should not exceed the degree of accuracy 7 in GOST 24643. The presence of burrs and other defects on the contact surfaces can violate the integrity of the gasket, and, accordingly, the required electrical insulation.
5. The efficiency of heat removal through a gasket made of KPTD-2 material is determined by the compressive force of the surfaces of the device and the radiator, their flatness and parallelism during assembly, as well as the presence of residual air cavities between the gasket and the clamping surfaces. In order to maximize the squeezing out of air pockets, it is recommended to apply the gasket with a glossy surface or a surface with a sticky layer to the highest quality pressure surface and roll it with a rubber roller.
6. To isolate semiconductor devices from the heatsink housing when fastening with screws, use insulating sleeves NOMACON ™ M2.5 and M3 made of heat-resistant polyamide.
7. When using large format gaskets with a surface area of 20 to 1200 cm², there is often a problem of high-quality preparation of contact surfaces. At the same time, the thickness and elasticity of the gasket is not enough to compensate for the defects of the surfaces themselves during compression, as well as their flatness and parallelism during assembly. In order not to increase the thickness of the gasket, leading to an increase in thermal resistance, it is recommended to first apply the appropriate heat-conducting paste NOMACON ™ KPTD-3 to the contact surfaces and then install and roll the gasket.
8. It is prohibited to store, manipulate and use the KPTD-2 (KPTD-2M) materials at temperatures below minus 60 ° C and above plus 250 ° C.

manufacturer's warranty

1. The manufacturer guarantees the conformity of sheet materials NOMACON ™ KPTD-2 and NOMACON ™ KPTD-2M to the requirements of technical specifications, subject to the conditions of transportation, storage and use.
2. The shelf life of KPTD-2 (KPTD-2M) materials without a sticky layer in the manufacturer's packaging is 24 months.
3. The shelf life of materials KPTD-2 (KPTD-2M) with a sticky layer and positioning grease in the manufacturer's packaging is 6 months.
4. The loss of stickiness of materials KPTD-2 (KPTD-2M) after the expiration of the shelf life of the consumer is not a rejection factor.
5. After the expiration of the shelf life, the materials KPTD-2 and KPTD-2M are tested before each use for compliance with the requirements of the technical specifications. Subject to compliance, the materials can be used for their intended purpose.
6. Complaints and claims for quality are accepted when returning products in the manufacturer's packaging with the provision of copies of accompanying documents for the products received from the manufacturer (invoice, quality certificate).