CZ308571B6 - Composite for thermal protection, in particular for cooling electronic components - Google Patents

Abstract

The invention is to a composite (1) for thermal protection, in particular for cooling electronic components, which comprises at least one porous support layer (2) in which at least one metabolic material is deposited, the porous support layer (2) has on at least one of its surfaces a cover layer (3) which is impermeable to the material(s) of metabolism deposited in the carrier layer (2), at least one cover layer (3) is formed by a thermally conductive material in direct contact with the carrier layer (2).

Description

Composite for thermal protection, in particular for cooling electronic components

Field of technology

The invention relates to a composite for thermal protection, in particular for cooling electronic components.

Prior art

Various types of active or passive coolers are currently used to protect various components, such as electronic components, against the effects of high temperatures (from the environment or caused by the component's activities). Their goal is to prevent the component from overheating and thus damage or destroy it, and to keep its temperature in a relatively narrow temperature range optimal for its performance. Frequent and relatively rapid temperature fluctuations of these components require an immediate reaction of the heat sink and / or its sufficient heat capacity.

The disadvantage of active coolers is that they work with temperature sensors, which can be inaccurate or damaged, consume electricity and emit noise.

The main disadvantage of passive coolers is the need to oversize them for extreme cases and low flexibility.

A common disadvantage of both types of heatsinks is that they are not able to protect the component from other influences that limit its performance and life, such as low temperature or electromagnetic interference from the environment.

US 20030124318 discloses a thermal barrier which comprises two cover layers, between which a base material is embedded, in which at least one metabolic material is embedded. The base material layer is divided into several regions (within which the same or different material-transforming material is deposited), which are separated from one another. This separation is realized in one variant of the embodiment either by a barrier formed by any material impermeable to the material with a material transformation in the liquid state, such as a locally compacted base material, or by another non-porous material, or by joining the cover layers. Due to this construction, this barrier has a high rigidity (especially in bending), which makes it not suitable for many applications, as it is not able to adapt to the shape of the protected electronic component and / or the space.

It is an object of the invention to provide a composite for thermal protection, in particular electronic components, which is capable of this.

The essence of the invention

The object of the invention is achieved by a composite for thermal protection, in particular for cooling electronic components, the essence of which consists in comprising at least one porous carrier layer in which at least one metabolic material is deposited, the porous carrier layer being on at least one of its surfaces provided with a cover layer which is impermeable to the metabolically modified material (s) deposited in the carrier layer. At least one cover layer is formed of a thermally conductive material and is in direct contact with the carrier layer.

A suitable metabolic material is in particular polyethylene glycol or paraffin.

- 1 CZ 308571 B6

To increase efficiency, it is possible to incorporate nanoparticles and / or microparticles of thermally conductive material into the metabolic material, the presence of which improves the heat transfer through the internal structure of the composite.

The porous support layer consists of a material with a low filling factor - e.g. a textile (preferably non-woven), a layer of foam material, a layer of polymeric nanofibers, etc.

In a preferred variant, the porous support layer is provided with a cover layer on both of its surfaces.

Depending on the intended application, the at least one cover layer of the composite may be formed by a layer of electrically conductive material, such as a metal foil, which protects the component from external electromagnetic fields, or by a layer of electrically nonconductive and thermally conductive material, such as a layer of polymeric nanofibers or polymeric foils.

To improve the heat transfer between the individual layers of the composite, it is advantageous if at least one surface of the porous support layer is at least partially metallized.

For some applications, it may be advantageous if the porous support layer is discontinuous, which facilitates the shaping of the composite, e.g. according to the shape of the cooled part, and the achievement of a larger contact area.

Explanation of drawings

FIG. 1 schematically shows a section of a thermal protection composite, in particular for cooling electronic components, according to the invention, FIG. 2 shows the result of differential scanning calorimetry measurements for a thermal protection composite according to the invention in a variant with a porous layer provided on both surfaces FIG. 3 shows the result of measuring differential scanning calorimetry for a composite for thermal protection according to the invention in a variant with a porous layer provided on one surface with a cover layer made of aluminum foil and on the opposite surface a hydrophobized layer of polyamide nanofibers, and FIG. the result of the measurement of the differential scanning calorimetry for the composite for thermal protection according to the invention in a variant with a porous layer provided on both surfaces with a covering layer formed by a hydrophobized layer of polyamide nanofibers. Fig. 5 shows the temperature versus time curves of various composite variants according to the invention with marked inflection points when heated on a plate heated to 65 ° C, and Fig. 6 shows the temperature versus time curves of these composite variants with marked inflection points during their heating. on a plate heated to 75 ° C. Fig. 7 shows the temperature-time curves of other variants of the composite according to the invention with marked inflection points when heated on a plate heated to a temperature of 75 ° C.

Examples of embodiments of the invention

The composite 1 for thermal protection, in particular for cooling the electronic components according to the invention, comprises at least one porous carrier layer 2, in the pores of which at least one metabolic material is deposited. This porous carrier layer 2 is provided on at least one of its surfaces with a cover layer 3 which is impermeable to the metabolic material deposited in the carrier layer 2 and which thus prevents it from escaping from the structure of the carrier layer 2 when this material melts. layer 3 is thermally conductive and is in direct contact with the carrier layer 2, which facilitates the transfer of heat to, resp. from the porous support layer 2.

A number of known materials of organic and inorganic origin, or combinations thereof, can be used as the material with material transformation. With regard to the odor and toxicity of some of them, polyethylene glycols (PEG) appear to be the most suitable. Their other advantage is water solubility and therefore easy workability. To protect against high temperatures, it is advisable to use a material with a higher metabolic temperature (melting), such as PEG 1450

-2 CZ 308571 B6 with melting point 42 to 46 ° C, PEG 1500 with melting point 45 to 50 ° C, PEG 2000 with melting point 50 to 53 ° C, PEG 3000 with melting point 55 to 58 ° C, PEG 4000 s melting point 53 to 58 ° C or PEG 6000 with melting point 58 to 63 ° C, etc. Conversely, for protection against low temperatures it is suitable to use materials with a low transition temperature, such as PEG 300 with a melting point of -15 to -10 ° C or PEG 400 with a melting point of 5 ° C, etc. If necessary, materials with different types and / or metabolics can be combined within several or even one carrier layer 2 to increase the flexibility of the thermal protection composite 1. different transition temperatures.

Other suitable metabolic materials are, for example, paraffins.

As the porous support layer 2, various fibrous materials can be used, e.g. in the form of a nonwoven fabric, fabric, knitted fabric, polymer nanofiber layers, etc., or foam materials, e.g. polyurethane or other foam, etc., wherein the liquid-transformed material (s) due to the excellent wettability of these materials, they spontaneously penetrate / penetrate into their pores, which they (at least partially) fill. Due to its large specific surface area and large contact area, the metabolic material (s) thus absorbed (s) are stable in both the solid and liquid state in such a carrier. Preferred materials for the porous support layer 2 appear to be, in particular, materials comprising polymeric nanofibers or materials consisting of polymeric nanofibers. Suitable polymeric nanofibers are especially polyamide nanofibers - their advantage is their good availability and chemical and thermal resistance. The carrier layer 2 of these materials is preferably continuous, but can also be formed as discontinuous if necessary, if it is formed, for example, by mutually separated structures of the same or different size, which can be arranged in a suitable regular or irregular matrix or pattern. which allows easier shaping of the composite 1 according to the shape of the component, and thus increasing the heat exchange area.

For the mechanical protection of the carrier layer 2 and the metabolic material deposited therein, at least one cover layer 3 is deposited on at least one surface of the carrier layer 2, but preferably on both surfaces thereof. This cover layer 3 can be formed of a number of different materials as required. , or suitable combinations of two or more materials. According to the considered application of composite 1, at least one cover layer 3 is made of thermally and possibly also electrically conductive material, which at the same time protects the component from external electromagnetic field - such material are eg metal foils (copper, aluminum, etc.) or thermally conductive. , but an electrically non-conductive material - such material is, for example, polymeric foils (eg polyester, etc.) or layers of polymeric nanofibers (eg polyamide, etc.). A variant in which the cover layer 3 on one surface of the porous support layer 2 is formed by a thermally and electrically conductive material and at the same time the cover layer 3 on the opposite surface of the porous support layer 2 is a thermally conductive but electrically non-conductive material. due to the presence of an electrically conductive cover layer 3) for its protection against electromagnetic radiation, resp. interference from the environment.

If a layer of polymeric nanofibers is used, this layer is preferably provided with a hydrophobic and possibly also oleophobic treatment, eg in the form of a hydrophobic agent embedded in a discontinuous layer in its darkness according to CZ 2011-306, or in the form of a film formed by plasma spraying according to CZ 305675 B6, etc., where it prevents the penetration of water to the metabolically modified material in the porous support layer 2. The polymeric nanofiber layer can be used either alone or in combination with a layer of a conventional fabric to which it is bonded by natural adhesion or lamination.

To prevent leakage of the exchange material (s) around the circumference of the carrier layer 2 between the cover layers 3, the carrier layer 2 is preferably covered on its circumference with a layer of material with hydrophobic properties and suitable mechanical and chemical resistance (which may or may not be identical to the cover layer material). / layers 3) and / or at least one cover layer 3 extends over the circumference of the carrier layer 2 and is, e.g., connected by means of lamination points to a cover layer 3 deposited on the opposite surface of the carrier layer 2, or the cover layers 3 are connected, e.g. by means of lamination points around the circumference of the carrier layer 2.

-3GB 308571 B6

The cover layer (s) 3 may be bonded directly to the carrier layer 2 by a metabolic material (s) which, in the molten state (during the manufacture or first use of the composite 1), also wets the material of the cover layers 3 and, after solidification, these It connects the cover layers 3 to the carrier layer 2. However, if necessary, the cover layers 3 can be connected to the carrier layer 2 by gluing or other suitable technology according to the type and material of these layers.

To improve the heat transfer to and in the structure of the composite 1, it is advantageous if at least one surface of the porous support layer 2 is at least partially metallized. A further improvement in heat transfer is achieved by placing nanoparticles and / or microparticles of thermally conductive materials (especially metals such as copper, aluminum, silver, etc., or non-metallic materials such as carbon, etc.) in the metabolically deposited material deposited in the porous The amount of these particles, depending on their type and size, preferably corresponds to about 1 to 25% by weight of the metabolic material in the composite 1, but can be higher or lower if necessary.

The structure of the composite 1 according to the invention makes it possible to achieve a high proportion (even more than 90% by weight) of the material (s) with metabolism and thus a significant thermal effect.

Example 1

The thermal protection composite 1 contained a carrier layer 2 formed by a layer of polyamide 6 nanofibers with a basis weight of 20 g / m ² and a fiber diameter of 180 nm. A cover layer 3 consisting of an aluminum foil with a basis weight of 50 g / m ² was placed on both surfaces of this carrier layer ² . PEG 4000 was used as the metabolic material, which was applied in the molten state at a temperature of 80 ° C, completely filling the pores of the carrier layer 2 and, after solidification, joining the carrier layer 2 with both cover layers 3. Total basis weight of the composite 1 thus formed was 420 g / m ² , of which 300 g / m ² , i.e. 71.4%, was PEG 4000. The composite thus formed is cohesive, flexible and mechanically resistant and has good thermal conductivity and very good electromagnetic shielding properties.

Example 2

The thermal protection composite 1 contained a carrier layer 2 formed of a viscose nonwoven fabric with a basis weight of 47 g / m ² . A cover layer 3 consisting of an aluminum foil with a basis weight of 20 g / m ² was placed on both surfaces of this carrier layer ² . PEG 1500 was used as the metabolic material, which was applied in the molten state at a temperature of 80 ° C, completely filling the pores of the carrier layer 2 and, after solidification, joining the carrier layer 2 with both cover layers 3. Total basis weight of the composite 1 thus formed was 387 g / m ² , of which 300 g / m ² , ie 77.5%, was PEG 1500. The composite j. thus formed is cohesive, flexible and mechanically resistant and has good thermal conductivity and very good electromagnetic shielding properties. .

Fig. 2 shows the result of differential scanning calorimetry (DSC) measurements of this composite 1, from which it is clear that the composite 1 of the above-described construction can absorb (or deliver) about 123 J / g during a group change.

Example 3

The thermal protection composite 1 contained a carrier layer 2 formed of a polyester nonwoven fabric with a basis weight of 12 g / m ² with surfaces plated with a layer of copper. On one surface of this support layer 2 a cover layer 3 was placed, consisting of an aluminum foil with a basis weight of 20 g / m ² and on the opposite surface a hydrophobized layer of polyamide fibers with a basis weight of 3 g / m ² and a fiber diameter of 200 nm. PEG 1500 was used as the metabolic material, which was applied in the molten state at a temperature of 80 ° C, completely filling the pores of the carrier layer 2 and, after solidification, joining the carrier layer 2 with both cover layers 3. Total basis weight of the composite 1 thus formed was 125 g / m ² , of which 90 g / m ² , i.e. 72%, was PEG 1500. Thus

-4CZ 308571 B6 formed composite j. Is cohesive, flexible and mechanically resistant and has excellent thermal conductivity and very good electromagnetic shielding properties.

Fig. 3 shows the result of DSC measurements of this composite 1, from which it is clear that the composite of the above-described construction can absorb (or dispense) about 104 J / g during the group change.

Example 4

The thermal protection composite 1 contained a carrier layer 2 formed of a polyester nonwoven fabric with a basis weight of 12 g / m ² with surfaces plated with a layer of copper. On one surface of this support layer 2 a cover layer 3 was placed, formed by an aluminum foil with a basis weight of 20 g / m ² , the opposite surface being free. PEG 1500 was used as the metabolic material, which was applied in the molten state at a temperature of 80 ° C, completely filling the pores of the carrier layer 2 and, after solidification, joining the carrier layer 2 with the cover layers 3. The total basis weight of the composite 1 thus formed was 122 g / m ² , of which 90 g / m ² , i.e. 73.7%, were PEG 1500. The composite 1 thus formed is cohesive, flexible and mechanically resistant and has excellent thermal conductivity and very good electromagnetic shielding properties. The DSC measurement result of this composite 1 was the same as in Example 3 - the absence of the cover layer 3 formed by the hydrophobized layer of polyamide fibers did not substantially affect the measurement.

Example 5

The thermal protection composite 1 contained a carrier layer 2 formed of a polyester nonwoven fabric with a basis weight of 15 g / m ² with surfaces plated with a layer of copper. On both surfaces of this support layer 2, a cover layer 3 was deposited, formed by a hydrophobized layer of polyamide nanofibers with a basis weight of 3 g / m ² and a diameter of nanofibers of 200 nm. PEG 1500 was used as the metabolic material, which was applied in the molten state at a temperature of 80 ° C, completely filling the pores of the carrier layer 2 and, after solidification, joining the carrier layer 2 with both cover layers 3. Total basis weight of the composite 1 thus formed was 81 g / m ² , of which 60 g / m ² , i.e. 74%, was PEG 1500. The composite 1 thus formed is cohesive, flexible and mechanically resistant and has excellent thermal conductivity, while being electrically non-conductive.

Fig. 4 shows the result of DSC measurements of this composite 1, from which it is clear that the composite of the above-described construction can absorb (or dispense) about 117 J / g during the group change.

Example 6

The thermal protection composite 1 contained a carrier layer 2 formed by a layer of polyurethane foam with a basis weight of 108 g / m ² . On both surfaces of this support layer 2, a cover layer 3 was deposited, formed by a hydrophobized layer of polyamide nanofibers with a basis weight of 2.5 g / m ² and a diameter of the nanofibers of 200 nm. PEG 1450 was used as the metabolic material, which was applied in the molten state at a temperature of 80 ° C, completely filling the pores of the carrier layer 2 and, after solidification, joining the carrier layer 2 to both cover layers 3. Total basis weight of the composite 1 thus formed was 4176 g / m ² , of which 4063 g / m ² , i.e. 97.3%, was PEG 1450. The composite 1 thus formed is cohesive, flexible and mechanically resistant and has excellent thermal conductivity, while being electrically non-conductive.

This composite was placed on a thermostated plate heated to 65 ° C and its surface temperature was monitored with an infrared non-contact thermometer. The result of the measurement is the time when PEG 1450 melted in the whole volume of the sample (even in the measured surface). Achieving this state was indicated as an inflection point on the sample temperature versus time curve. The inflex occurs when the surface temperature of the sample reaches 44 ° C, which is the melting point of the PEG 1450 used. In this case, the inflex occurred in 1060 seconds.

-5CZ 308571 B6

The same experiment was then repeated with the thermostated plate heated to 75 ° C. In this case, an inflection occurred in 460 seconds.

Example 7

In three samples of composite 1 for thermal protection according to Example 6, copper microparticles with a diameter of 35 μm (CuTEC50, supplier of pchemistry) were incorporated into their internal structure and into the structure of PEG 1450 in an amount of 313 g / m ² , 625 g / m ^2. , resp. 928 g / m ² , ie 7.7%, 15.4%, resp. 22.8% by weight of PEG 1450.

For the samples thus prepared, the inflection time was measured with the methods described in Example 6 - see Table 1.

Table 1

Sample Amount of copper microparticles fg / m ² ] Proportion of copper microparticles to PEG 1450 [%] Inflex at thermostated plate temperature 65 ° C [s] Inflex at thermostated plate temperature 75 ° C [s] B 313 7.7 600 460 C 625 15.4 282 290 D 928 22.8 267 190

Both measurements showed a positive effect of the addition of copper microparticles - due to their presence there was a faster melting of PEG 1450 (reaching the inflex), which with the same content of PEG 1450 in composite 1 means that thermal energy in the presence of copper microparticles was absorbed faster - ie composite 1 of this the structure is able to absorb more energy per unit time and is therefore able to protect against high temperature more effectively than without the presence of copper microparticles.

Fig. 5 shows curves of the temperature dependence of the sample of composite 1 with marked inflection points for the variant of composite 1 according to Example 6, i.e. without copper microparticles (curve A) and for the above-described variants of composite 1 with different content of copper microparticles (curves B to D), when using a thermostated heated plate heated to 65 ° C.

Fig. 6 shows curves of the temperature dependence of the sample of composite 1 with marked inflection points for the variant of composite 1 according to Example 6, i.e. without copper microparticles (curve A) and for the above-described variants of composite 1 with different content of copper microparticles (curves B to D), when using a thermostated heated plate heated to 75 ° C.

The optimal dose of copper microparticles in the structure of the composite thus appears to be about 600 g / m ² , resp. about 10 to 15% by weight of PEG 1450 (this value refers to the microparticles used, in the case of smaller particles the value may be smaller to achieve the same or comparable effect). A possible higher dose is not harmful, but the inflection point no longer significantly shifts.

Example 8

The thermal protection composite 1 contained a carrier layer 2 formed by a layer of polyurethane foam with a basis weight of 104 g / m ² . On both surfaces of this support layer 2, a cover layer 3 was deposited, formed by a hydrophobized layer of polyamide nanofibers with a basis weight of 3 g / m ² and a diameter of nanofibers of 200 nm. PEG 1450 was used as the metabolic material, which was applied in the molten state at a temperature of 80 ° C, completely filling the pores of the carrier layer 2 and, after solidification, joining the carrier layer 2 with both cover layers 3. Total basis weight of the composite 1 thus formed was 4910 g / m ² , of which 4800 g / m ² , i.e. 97.8%, was PEG 1450. The composite 1 thus formed is cohesive, flexible and mechanically resistant and has excellent thermal conductivity, while being electrically non-conductive.

-6GB 308571 B6

This composite was placed on a thermostated plate heated to 75 ° C and its surface temperature was monitored with an infrared non-contact thermometer. The result of the measurement is the time when PEG 1450 melted in the whole volume of the sample (even in the measured surface). Achieving this state was indicated as an inflection point on the sample temperature versus time curve. The inflex occurs when the surface temperature of the sample reaches 44 ° C, which is the melting point of the PEG 145 0 used. In this case, the inflex occurred in 535 seconds.

Example 9

In four samples of the thermal protection composite 1 of Example 8, 100 micron carbon microparticles (ground Carbiso® carbon fibers, MF SM45R-100, manufactured by ELG Carbon Fiber, Ltd.) were incorporated into their internal structure and PEG 1450 structure during their preparation. ) in an amount of 80 g / m ² , 160 g / m ² , 240 g / m ² , resp. 320 g / m ² , ie 1.7%, 3.3%, 5.0% resp. 6.7% by weight of PEG 1450.

For the samples thus prepared, the inflection time was measured with the methods described in Example 6 - see Table 2.

Table 2

Sample Amount of copper microparticles fg / m ² ] Proportion of copper microparticles to PEG 1450 [%] Inflex at thermostated plate temperature 75 ° C [s] B 80 1.7 522 C 160 3.3 446 D 240 5.0 411 E 320 6.7 316

The measurement showed a positive effect of the addition of carbon microparticles - due to their presence there was a faster melting of PEG 1450 (reaching inflex), which with the same content of PEG 1450 in composite 1 means that thermal energy in the presence of carbon microparticles was absorbed faster - ie composite 1 of this construction it is able to absorb more energy per unit time and is therefore able to protect against high temperature more effectively than without the presence of carbon microparticles.

Fig. 7 shows curves of the temperature dependence of the sample of composite 1 with marked inflection points for the variant of composite 1 according to Example 8, i.e. without carbon microparticles (curve A) and for the above-described variants of composite 1 with different content of carbon microparticles (curves B to E), when using a thermostated heated plate heated to 75 ° C.

Claims (11)

PATENT CLAIMS Composite (1) for thermal protection, in particular for cooling electronic components, characterized in that it comprises at least one porous carrier layer (2) in which at least one metabolic material is deposited, the porous carrier layer (2) being provided at least on its surface with a cover layer (3) which is impermeable to the material (s) of metabolism deposited in the carrier layer (2), the at least one cover layer (3) being made of a thermally conductive material and in direct contact with carrier layer (2). Composite (1) according to Claim 1, characterized in that the metabolic material is polyethylene glycol. Composite (1) according to Claim 1, characterized in that the metabolic material is paraffin. Composite (1) according to one of the preceding claims, characterized in that nanoparticles and / or microparticles of thermally conductive material are deposited in the at least one metabolically modified material in the porous support layer (2). Composite (1) according to Claim 1 or 4, characterized in that the porous carrier layer (2) is formed by a fabric or a layer of foam material. Composite (1) according to any one of claims 1, 4 or 5, characterized in that the at least one porous support layer (2) is formed by a layer of polymeric nanofibers. Composite according to Claim 1, characterized in that the porous carrier layer (2) is provided with a cover layer (3) on both of its surfaces. Composite according to Claim 1 or 7, characterized in that the at least one cover layer (3) is formed by a layer of electrically conductive material. Composite (1) according to Claim 1 or 7, characterized in that the at least one cover layer (3) is formed by a layer of electrically non-conductive material. Composite (1) according to any one of claims 1, 4, 5, 6 or 7, characterized in that at least one surface of the porous support layer (2) is at least partially metallized. Composite (1) according to any one of claims 1, 4, 5, 6, 7 or 10, characterized in that the porous support layer (2) is discontinuous.