KR102559169B1 - Silicone based thermal interface material having improved characteristics of a change with the passage of time by water absorption and the manufacturing method of the same - Google Patents

Abstract

The present invention relates to a silicone-based heat carrier material composition that is stable at high temperature and a method for producing the same, wherein a silicon-based heat carrier material composition characterized in that a silicon-based heat carrier material composition is composed of a mixture of a silicon-based heat carrier material and an organic acid, and a silicon precursor in which silicon is generated by a reaction and a dispersed inorganic filler containing free alkali metal ions are mixed to prepare a mixture; and further adding an organic acid to the mixture.

Description

Silicone based thermal interface material having improved characteristics of a change with the passage of time by water absorption and the manufacturing method of the same}

The present invention relates to a silicone-based thermal interface material composition having little change in hardness at a high operating temperature and stability against rupture by adding a moisture scavenger to a composition of a silicon-based thermal interface material containing free alkaline metal ions and an inorganic filler containing moisture, and a method for manufacturing the same.

As electronic components such as semiconductors, transistors, and integrated circuits, and display products such as TVs and monitors become more high-performance, the amount of heat generated is greatly increasing. In addition, chargers for various batteries tend to generate a large amount of heat during operation. Generation of heat is inevitable, and therefore, technologies for cooling and removing such heat have been developed to a considerable extent.

If the heat generated from these electronic components is not sufficiently removed, the heat is eventually accumulated inside the heat generating source, resulting in malfunction due to deterioration of component performance, shortening of the mean time between failures, or thermal runaway.

In order to solve these problems, a method of removing heat generated from the heat generating source by transferring heat to an active or passive heat sink is used.

On the other hand, the surface of plastic, ceramic, or metal, which is a housing material that surrounds the heat generating source from the outside, and the metal used as the heat sink form a considerable portion of irregularities to widen the contact area, but there is a limit. Since the space between the housing and the heat generating source is filled with air, which is a heat nonconductor, thermal impedance actually occurs between the heat generating source and the heat sink, so it is difficult to efficiently remove heat.

Accordingly, a method of reducing thermal impedance by interposing various types of Thermal Interface Material (TIM) between a heat generating source and a heat sink to increase heat transfer efficiency is common (Korean Registered Patent No. 10-1011940, Korean Patent Publication No. 10-2017-0058382, Korean Patent Publication No. 10-2020-011080 No. 8, etc.).

Most thermal interface materials (TIMs) are manufactured by mixing and dispersing additives such as inorganic fillers with high thermal conductivity, antioxidants and dispersants in thermosetting or thermoplastic resins. The resin is a base material forming a continuous phase, and silicone rubber, which maintains elasticity in a wide temperature range from low temperature to high temperature and has excellent heat resistance, is mainly used as the resin. In addition, as the dispersed phase, relatively inexpensive alumina is mainly used. The alumina has a spherical structure that facilitates high packing density and has excellent thermal conductivity.

However, the above-described alumina is manufactured by dissolving bauxite in sodium hydroxide to produce aluminum tri-hydroxide (ATH) and then calcining it, so that the product contains a large amount of free alkaline metal ion represented by sodium ion.

Free Alkaline Metal Ion (Free Alkaline Metal Ion) acts to continuously increase the hardness of silicone rubber by inducing an additional curing reaction by reacting with organic silicone rubber at a high temperature of 100 ℃ or more with strong oxidizing power (see FIG. 1).

In addition, free alkali metal ion (Free Alkaline Metal Ion) has strong absorbency (hygroscopicity), so it absorbs moisture when stored for a long time at room temperature, and usually contains less than 2,000ppm of moisture.

Therefore, the continuous increase in hardness of silicone rubber increases the contact area by interposing a thermal interface material (TIM) between the heat generating source and the heat sink, thereby reducing the thermal resistance in the space between the heat generating source and the heat sink. There is a problem that works against the original purpose of use.

In addition, when the hardness is increased, the performance of filling the irregularities formed by the heat source and the heat sink by elasticity is reduced at the interface between the heat source and the heat intermediary material formed for each of the heat source and the heat sink, and since a large amount of voids are generated, there is a problem in that the thermal resistance increases at the interface.

Republic of Korea Patent No. 10-1011940 Republic of Korea Patent Publication No. 10-2017-0058382 Republic of Korea Patent Publication No. 10-2020-0110808

The present invention has been made to solve the above-mentioned problems, and the present invention minimizes the effect of moisture contained in alumina added as a dispersed phase on a silicone rubber matrix to the increase in hardness of silicone rubber at a high temperature of 100 ° C. or higher (Shore 00 hardness initial value ± 10 is aimed) and to provide a thermal interface material (TIM) composition capable of preventing rupture.

In addition, the present invention is a thermal interface material (TIM) capable of minimizing the effect of moisture contained in alumina on the hardness increase of silicone rubber at a high temperature of 100 ° C. or higher by adding a heat treatment process under vacuum to the composition. Another object is to provide a manufacturing method.

In order to achieve the above object, the present invention provides a silicone-based heat-interceptor composition, characterized in that a water removal agent is added to a silicone-based heat-interceptor material in which a silicone-based polymer material and a dispersed inorganic filler are mixed.

The moisture removing agent is preferably an oxazolidine derivative having a structure shown in Chemical Formula 1 below.

(Formula 1)

Here, R ₁ is a linear or branched hydrocarbon having 1 to 4 carbon atoms, R ₂ is a linear or branched hydrocarbon having 1 to 12 carbon atoms, and R ₃ is a methyl group (CH ₃ -) or hydrogen (H).

The added amount of the water removing agent is preferably 20 mol% or more and 100 mol% or less relative to the water contained in the dispersed phase inorganic filler.

In addition, the present invention provides a silicone-based heat carrier material stable at high temperature, characterized in that prepared by drying the above-described composition.

The drying temperature is preferably 70 °C or more and 120 °C or less.

The drying time is preferably 1 hour or more and 3 hours or less.

The drying is preferably carried out at 70° C. or more and 120° C. or less and under reduced pressure.

The reduced pressure is reduced to a vacuum state of 10 mmHg or less, and the drying time is preferably 1 hour or more and 3 hours or less.

In addition, the present invention comprises the steps of preparing a mixture by mixing a dispersed phase inorganic filler containing a silicon precursor and free alkali metal ions, in which silicon is produced by the reaction; And further adding a water removing agent to the mixture; provides a method for producing a stable silicone-based heat carrier material composition at a high temperature, characterized in that it comprises a.

The moisture removing agent is preferably an oxazolidine derivative having a structure shown in Chemical Formula 1 below.

(Formula 1)

Here, R ₁ is a linear or branched hydrocarbon having 1 to 4 carbon atoms, R ₂ is a linear or branched hydrocarbon having 1 to 12 carbon atoms, and R ₃ is a methyl group (CH ₃ -) or hydrogen (H).

The added amount of the water removing agent is preferably 20 mol% or more and 100 mol% or less relative to the water contained in the dispersed phase inorganic filler.

According to the present invention as described above, by adding a moisture removing agent to the heat transfer material, at a high temperature of 100 ° C. or higher, the effect of the moisture contained in the alumina added as a dispersed phase to the silicone rubber matrix on the increase in the hardness of the silicone rubber is minimized, and therefore, the effect of improving the heat dissipation effect and reducing the thermal resistance is expected.

1 is a reaction formula showing that hardness is increased by the reaction between free alkali metal ions and silicone rubber.
2 to 8 are photographs corresponding to Examples 1 to 7.
9 to 14 are photographs corresponding to Comparative Examples 1 to 6.

Hereinafter, the present invention will be described in detail based on the accompanying drawings and preferred embodiments. The invention may be embodied in many different forms and is not limited to the embodiments set forth herein.

<Production Example>

In the present invention, one or more types of vinyl terminated poly(dimethylsiloxane) having different viscosities, dimethylsiloxane-methylhydrosiloxane copolymer (Poly(dimethylsiloxane-co-(methylhydrosiloxane)), and average particle diameters of 2 μm, 10 μm, and 70 μm, respectively, and average free alkali metal ion content are After adding alumina with an average moisture content of 400 ppm and an average moisture content of 700 ppm and stirring uniformly, the moisture is removed at a temperature of 70 ° C or more and 120 ° C or less for 1 hour or more and 3 hours or less. After being left for more than 250 hours at a high temperature below, the Shore 00 hardness maintains a stable state so that it has an error within ±10 from the initial value, and there is no bursting due to evaporation of absorbed moisture. A thermal interface material (TIM) was prepared.

The oxazolidine derivative has a structure shown in Formula 1 below.

(Formula 1)

Here, R ₁ is a linear or branched hydrocarbon having 1 to 4 carbon atoms, R ₂ is a linear or branched hydrocarbon having 1 to 12 carbon atoms, and R ₃ is a methyl group (CH ₃ -) or hydrogen (H).

Before adding the oxazolidine derivatives, which are moisture scavengers in the composition, the moisture already present in the inorganic filler is removed by drying in a vacuum of 70 ° C. or more and 120 ° C. or less and 100 mmHg or less for 1 hour or more and 3 hours or less. By minimizing by-products such as aminoalcohol, ketone, or aldehyde produced by the reaction of rivatives and moisture (reaction formula 1 below), the change in physical properties of the silicon-based thermal interface material (TIM) is minimized, and the efficiency as a moisture scavenger can be improved by allowing it to react only with moisture that absorbs moisture when left at room temperature.

(Scheme 1)

Here, R ₁ is a linear or branched hydrocarbon having 1 to 4 carbon atoms, R ₂ is a linear or branched hydrocarbon having 1 to 12 carbon atoms, and R ₃ is a methyl group (CH ₃ -) or hydrogen (H).

In addition, here, if the content of the oxazolidine derivatives (Moisture Scavenger) to be added is less than the lower limit, the shelf-life of the silicone-based thermal interface material (TIM) is reduced. Since it causes an increase in , the addition amount of the oxazolidine derivatives, which are the moisture scavengers, has critical significance in the above numerical range.

In addition, here, if the water removal time is less than the lower limit of 1 hour, the water contained in the dispersed phase inorganic filler is not sufficiently removed, and the change over time due to the additionally absorbed water when left at room temperature increases, and even if the reaction exceeds the upper limit, there is no change in the amount of water, which is not preferable in terms of productivity. Therefore, the water removal time has a critical significance in the above range.

The evaluation method of the silicon-based thermal interface material (TIM) prepared using the present invention is as follows.

1. Quantification of Free Alkaline Metal Ion Contained in Dispersed Phase Inorganic Filler

100 g of the dispersed inorganic filler is put in the same amount of deionized water having a specific resistance of 10 MΩ cm or more, and left for 24 hours while stirring in a thermostat maintained at 80 ° C. Then, the supernatant is collected.

Then, the amount of free alkali metal ion was determined by analyzing with an inductively coupled plasma spectrometer (model name: ULTIMA II, HORIBA).

2. Quantification of the amount of moisture contained in the dispersed phase inorganic filler (Karl-Fischer method)

The amount of moisture contained in the dispersed phase inorganic filler was measured using a moisture meter (Model: 831 KF Coulometer, METROHM AG Karl-Fischer).

3. Shore 00

The hardness value of the sample having a thickness of 8 mm was obtained according to ASTM D2240.

4. Thermal conductivity

Thermal conductivity values were obtained using TIM TESTER 1401 (ANALYSIS TECH) according to ASTM D5470.

5. Heat resistance test

After leaving the sample in a drying oven maintained at 180 ° C. for 250 hours, it was stabilized at room temperature for more than 2 hours, and the hardness values of the three items and the thermal conductivity values of the four items were obtained and compared with the initial values, and heat resistance was estimated therefrom. In addition, the burst test of the following 6 items was performed.

6. Burst test

After testing the sample under the heat resistance test conditions of the above 5 items, it was cut with a knife and observed for rupture in multi-section.

Hereinafter, specific examples are provided to aid understanding of the present invention, and the following examples are only examples for explaining the present invention in detail, but the scope of the present invention is not limited to the following examples.

Example 1.

(1) 49g of vinyl terminated poly(dimethylsiloxane) having a viscosity of 1,000 cps at 25 ° C, 49 g of vinyl terminated poly(dimethylsiloxane) having a viscosity of 2,000 cps at 25 ° C, dimethylsiloxane-methylhydrosiloxane copolymer (Poly (dimethylsiloxane-co-(methylhydrosiloxane) )) 2 g and 900 g of alumina having an average particle diameter of 2 μm, 10 μm, and 70 μm, an average free alkaline metal ion content of 400 ppm and an average water content of 700 ppm (each mixing ratio 1: 1: 1) was added to a planetary mixer and stirred uniformly for 0.5 hours.

(2) The composition was dried at 100° C. under a vacuum of 10 mmHg for 2 hours to remove moisture contained in alumina.

(3) After cooling the dried composition to room temperature, 3-ethyl-2-methyl-2-(3-methylbutyl)-1,3-oxazolidine [3-ethyl-2-methyl-2-(3-methylbutyl)-1,3-oxazolidine] was weighed and added in an amount of 3.24 g, which is 50 mol% based on the moisture content contained in alumina, and stirred uniformly for 0.5 hour. It was molded to complete a silicon-based thermal interface material (TIM). The content of oxazolidine derivatives, which are moisture scavengers, was calculated by the following formula.

<Equation> Moisture removal agent input (g) = [(700 × 900 / (18 × 1,000,000)] × 0.5 × 185

Here, 700 is the amount of moisture (ppm) contained in the measured dispersed phase inorganic filler, 18 is the molecular weight of water, and 185 is the molecular weight of the water removing agent.

Example 2.

It is the same as in Example 1 except for adding 6.48 g of 3-ethyl-2-methyl-2-(3-methylbutyl)-1,3-oxazolidine to the composition of Example 1, which is 100 mol% based on the moisture content of alumina.

Example 3.

The same as in Example 1 except that 1.30 g of 3-ethyl-2-methyl-2-(3-methylbutyl)-1,3-oxazolidine was added to the composition of Example 1, which is 20 mol% based on the moisture content of alumina.

Comparative Example 1.

A silicone-based thermal interface material (TIM) was completed in the same manner as in Example 1 without adding oxazolidine derivatives, which are moisture scavengers, to the composition of Example 1.

Comparative Example 2.

The same as in Example 1 except that 0.65 g of 3-ethyl-2-methyl-2-(3-methylbutyl)-1,3-oxazolidine was added to the composition of Example 1, which is 10 mol% based on the moisture content of alumina.

Comparative Example 3.

It is the same as in Example 1 except for adding 9.71 g of 3-ethyl-2-methyl-2-(3-methylbutyl)-1,3-oxazolidine to the composition of Example 1, which is 150 mol% based on the moisture content of alumina.

Example 4.

It is the same as Example 1 except that 3.97g of 3-butyl-2-(1-methylpentyl)-1,3-oxazolidine was added instead of 3-ethyl-2-methyl-2-(3-methylbutyl)-1,3-oxazolidine to the composition of Example 3.

Example 5.

Same as Example 1 except that the composition of Example 1 was dried at 70°C instead of 100°C.

Example 6.

Same as Example 1 except that the composition of Example 1 was dried at 120°C instead of 100°C.

Comparative Example 4.

Same as Example 1 except that the composition of Example 1 was dried at 50°C instead of 100°C .

Comparative Example 5.

Same as Example 1 except that the composition of Example 1 was dried at 150°C instead of 100°C.

Example 7.

It is the same as Example 1 except that the composition of Example 1 was dried at 100 ° C. for 3 hours instead of drying at 100 ° C. for 2 hours.

Comparative Example 6.

It is the same as Example 1 except that the composition of Example 1 was further dried at 100°C for 5 hours instead of drying at 100°C for 2 hours.

The main variables of the Examples and Comparative Examples are summarized in Table 1, and the evaluation results are shown in Table 2.

Comparison of test conditions division variable detail note Example 1 Added amount of moisture remover 50 mol% of water content standard mix Example 2 100 mol% of water content Example 3 20 mol% of water content Comparative Example 1 0 mol% relative to water content Comparative Example 2 10 mol% of water content Comparative Example 3 150 mol% of water content Example 4 type of moisturizer Add 3-butyl-2-(1-methylpentyl)-1,3-oxazolidine instead of 3-ethyl-2-methyl-2-(3-methylbutyl)-1,3-oxazolidine Example 5 drying temperature 70℃ 2 hours Example 6 120℃ 2 hours Comparative Example 4 50℃ 2 hours Comparative Example 5 150℃ 2 hours Example 7 drying time 100℃ 3 hours Comparative Example 6 100℃ 5 hours

Evaluation results division Hardness (Shore 00) Thermal conductivity (W/m K) Exploded or not division Early After heat resistance test Early After heat resistance test Exploded or not Observation photo Example 1 50 53 3.2 3.2 radish Figure 2 Example 2 47 55 3.3 3.2 radish Figure 3 Example 3 52 60 3.2 3.1 radish Figure 4 Comparative Example 1 52 60 3.2 2.5 you Figure 9 Comparative Example 2 55 67 3.1 2.7 you Figure 10 Comparative Example 3 45 53 3.3 3.1 radish Figure 11 Example 4 52 57 3.2 3.1 radish Figure 5 Example 5 50 54 3.2 3.2 radish Figure 6 Example 6 50 52 3.2 3.2 radish Figure 7 Comparative Example 4 50 62 3.2 2.8 you Figure 12 Comparative Example 5 50 52 3.2 3.2 radish Figure 13 Example 7 50 53 3.2 3.1 radish Figure 8 Comparative Example 6 50 52 3.2 3.2 radish Figure 14

Comparing Examples 1 to 3 with Comparative Examples 1 and 2, when no or little moisture scavenger is used, the absorbed moisture evaporates at high temperature, causing the specimen to expand and burst, resulting in a void inside the TIM. It can be seen that the thermal conductivity is reduced.

On the other hand, as shown in Comparative Example 3, even if the water scavenger is added in excess of 150 mol% or more relative to the water content, there is no additional improvement in the cracking phenomenon or thermal conductivity compared to Examples 1 to 3, while the initial hardness value in the same composition. There is only a phenomenon that is lowered, so it is judged that the excessive addition of more than necessary is meaningless.

In Example 4, it is judged that the effect is expressed regardless of the type of substituent of the oxazolidine derivative, as there is no significant difference in terms of effect even when the type of water scavenger is changed.

Comparing Examples 5 and 6 with Comparative Example 4, when the drying temperature is low, the contained moisture is not sufficiently removed, resulting in a bursting phenomenon of the specimen, which causes voids to be generated inside the heat intercalating material (TIM). It can be seen that the thermal conductivity is reduced. On the other hand, as shown in Comparative Example 5, even when dried at a high temperature of 150 ° C. or higher, there is no additional improvement in thermal conductivity or bursting compared to Examples 5 and 6, so it is judged that a drying temperature higher than necessary is meaningless in terms of productivity and energy consumption.

Comparing Example 7 and Comparative Example 6, even if the drying time is increased from 3 hours to 5 hours, it is judged that a drying time of 3 hours or more is undesirable in terms of productivity, as there is no additional improvement effect.

Looking at the above examples and comparative examples, when the oxazolidine derivative is added in an amount of 20 to 100 mol% relative to the initial moisture content, the absorbed moisture is converted into aminoalcohol, ketone, or aldehyde as shown in Scheme 1, so that the cracking phenomenon caused by evaporation of the absorbed moisture can be effectively controlled during storage at high temperatures.

Although the present invention has been described in more detail by way of examples above, the present invention is not necessarily limited to these embodiments and may be variously modified and implemented without departing from the spirit of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed according to the following claims, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

Claims (11)

It is composed by adding a moisture remover to a silicone-based heat carrier material mixed with a silicone-based polymer material and a dispersed inorganic filler,
The water removal agent is a silicone-based heat carrier material composition, characterized in that the oxazolidine derivative having a structure as shown in the following formula (1).
(Formula 1)

Here, R ₁ is a linear or branched hydrocarbon having 1 to 4 carbon atoms, R ₂ is a linear or branched hydrocarbon having 1 to 12 carbon atoms, and R ₃ is a methyl group (CH ₃ -) or hydrogen (H). delete According to claim 1,
The addition amount of the moisture remover is 20 mol% or more and 100 mol% or less of the moisture contained in the dispersed inorganic filler (Inorganic Filler), characterized in that the silicone-based heat carrier material composition. A silicone-based heat carrier material, characterized in that it is prepared by drying the composition of claim 1. According to claim 4,
The temperature during drying is 70 ℃ or more and 120 ℃ or less, characterized in that the silicon-based heat carrier material. According to claim 4,
The drying time is 1 hour or more and 3 hours or less, characterized in that the silicon-based heat carrier material. According to claim 4,
A silicon-based heat transfer material, characterized in that the drying is carried out at 70 ° C. or more and 120 ° C. or less and under reduced pressure. According to claim 7,
The reduced pressure is reduced to a vacuum state of 10 mmHg or less, and the drying time is 1 hour or more and 3 hours or less. preparing a mixture by mixing a silicon precursor from which silicon is produced by the reaction and a dispersed inorganic filler containing free alkali metal ions; and
further adding a water removing agent to the mixture;
Including,
The method for producing a silicone-based heat carrier material composition, characterized in that the moisture removing agent is an oxazolidine derivative having a structure as shown in Formula 1 below.
(Formula 1)

Here, R ₁ is a linear or branched hydrocarbon having 1 to 4 carbon atoms, R ₂ is a linear or branched hydrocarbon having 1 to 12 carbon atoms, and R ₃ is a methyl group (CH ₃ -) or hydrogen (H). delete According to claim 9,
The method of producing a silicone-based heat carrier material composition, characterized in that the addition amount of the moisture remover is 20 mol% or more and 100 mol% or less relative to the moisture contained in the dispersed phase inorganic filler (Inorganic Filler).