KR20220064257A - 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 mediation material composition which is stable at a high temperature, and a method for producing the same. Provided are a silicone-based heat mediation material composition which is formed by mixing a silicone-based heat mediation material and an organic acid; and a method for producing a silicone-based heat mediation material composition which is stable at a high temperature, wherein the method comprises: a step of producing a mixture by mixing a silicone precursor for generating silicone by reaction, and a dispersed phase inorganic filler containing free alkali metal ions; and a step of 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 is by adding a moisture scavenger to a composition of a silicone-based thermal interface material containing free alkali metal ions and an inorganic filler containing moisture. The present invention relates to a silicone-based thermal intermediary material composition having little change in hardness at operating temperature and stability against rupture, and a method for manufacturing the same.

As electronic components such as semiconductors, transistors, integrated circuits, and display products such as TVs and monitors have improved in performance, the amount of heat generated is increasing significantly. In addition, there is a tendency that a large amount of heat is generated during operation of the charger of various batteries. Generation of heat is inevitable, and therefore, technologies for cooling and removal of such heat are being developed at a considerable level.

If the heat generated from these electronic components is not sufficiently removed, heat will eventually accumulate inside the heat source, causing malfunctions due to deterioration of component performance, shortening the mean time between failures, or thermal runaway ( It may cause fire due to thermal runaway).

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

On the other hand, the surface of the plastic, ceramic, or metal, which is a housing material that surrounds the heat generating source from the outside, and the metal used as a heat sink form a considerable amount of irregularities, so that the contact area is widened, but there is a limit, Since the space between the housing and the heat source is filled with air, which is a thermal insulator, there is actually a thermal impedance between the heat source and the heat sink, making it 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 the efficiency of heat transfer has been generalized ( Korean Patent Registration No. 10-1011940, Korean Patent Publication No. 10-2017-0058382, Korean Patent Publication No. 10-2020-0110808, 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 matrix material for forming a continuous phase, and silicone rubber having excellent heat resistance and maintaining elasticity in a wide temperature range from low to high temperature 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 increasing packing density and has excellent thermal conductivity.

However, the above-described alumina is manufactured by dissolving bauxite in sodium hydroxide in the manufacturing method to prepare aluminum tri-hydroxide (ATH) and then calcining it. It contains a large amount of free alkali metal ions represented by sodium ions.

Free alkali metal ion (Free Alkaline Metal Ion) acts to continuously increase the hardness of silicone rubber by inducing an additional curing reaction by reacting with silicone rubber, which is an organic material, at a high temperature of 100° C. or higher with strong oxidizing power (see FIG. 1).

In addition, free alkali metal ion (Free Alkaline Metal Ion) has strong water absorption (hygroscopicity), so it absorbs moisture when stored for a long time at room temperature, and usually contains less than 2,000 ppm of moisture. It ruptures the silicon-based heating medium during vaporization, which causes performance degradation.

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

In addition, when the hardness increases, the performance of filling the unevenness formed by the heat generating source and the heat sink by elasticity at the interface between the heat generating source and the heat sink formed for each of the heat sinks by elasticity is lowered. Since a large amount is generated, there is a problem in that thermal resistance is increased at the interface.

Republic of Korea Patent Registration 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 devised to solve the problems described above, and the present invention minimizes the effect of moisture contained in alumina added as a dispersed phase on a silicone rubber matrix on the increase in hardness of silicone rubber at a high temperature of 100° C. or more ( Shore 00 hardness initial value ±10) and aims to provide a thermal interface material (TIM) composition that can prevent rupture.

In addition, the present invention is a thermal interface material (TIM) that can minimize the effect of moisture contained in alumina on the increase in hardness of silicone rubber at a high temperature of 100° C. or more 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 thermal intermediary composition comprising a silicone-based thermal intermediary material in which a silicone-based polymer material and a dispersed inorganic filler are mixed, and a moisture removing agent is added.

The moisture removing agent is preferably 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).

It is preferable that the amount of the water remover added is 20 mol% or more and 100 mol% or less relative to the moisture contained in the dispersed inorganic filler (Inorganic Filler).

In addition, the present invention provides a silicone-based thermal medium stable at high temperature, characterized in that it is prepared by drying the above-mentioned composition.

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

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

Preferably, the drying is carried out at 70°C or more and 120°C or less and under reduced pressure.

The reduced pressure is to reduce the pressure in a vacuum 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 silicon precursor, which is produced by the reaction, and a dispersed inorganic filler containing free alkali metal ions; And it provides a method for producing a silicone-based heat medium composition stable at high temperature comprising a; and the step of further adding a moisture remover to the mixture.

The moisture removing agent is preferably 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).

It is preferable that the amount of the water remover added is 20 mol% or more and 100 mol% or less relative to the moisture contained in the dispersed inorganic filler (Inorganic Filler).

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

1 is a reaction formula showing that hardness increases by the reaction of 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 present invention may be implemented in several different forms and is not limited to the embodiments described herein.

<Production Example>

The present invention relates to one or more vinyl-terminated poly(dimethylsiloxane), dimethylsiloxane-methylhydrosiloxane copolymers having different viscosities in a planetary mixer (Poly(dimethylsiloxane-co-(methylhydrosiloxane)) ) and alumina having an average particle diameter of 2 μm, 10 μm, and 70 μm, an average free alkali metal ion content of 400 ppm, and an average moisture content of 700 ppm, followed by uniform stirring, and then at 70° C. or higher Moisture is removed at a temperature of 120°C or lower for 1 hour or more and 3 hours or less, and 20 mol% or more and 100 mol% or less of the moisture contained in the dispersed inorganic filler with Oxazolidine Derivatives After adding and leaving it at a high temperature of 150℃ or more and 200℃ or more for 250 hours or more, it maintains a stable state so that the Shore 00 hardness has an error within ±10 from the initial value and does not burst due to evaporation of absorbed moisture. A thermal interface material (TIM) was prepared.

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

Before adding Oxazolidine Derivatives, which are moisture scavengers, in the composition, the moisture pre-existing in the inorganic filler is reduced to 70°C or more and 120°C or less, 100 mmHg or less under vacuum for 1 hour. By drying for more than 3 hours and removing it in advance, aminoalcohol and ketone or aldehyde produced by the reaction of moisture (reaction formula 1) with oxazolidine derivatives, which are moisture scavengers, and water By minimizing by-products such as aldehyde, the change in the physical properties of silicone-based thermal interface material (TIM) is minimized, and when left at room temperature, it reacts only with moisture absorbed, improving the efficiency as a moisture scavenger. can do it

(Scheme 1)

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

In addition, when the content of Oxazolidine Derivatives, which is the added moisture scavenger, is less than the lower limit, the shelf-life of the silicone-based Thermal Interface Material (TIM) decreases, and , when the upper limit is exceeded, excess oxazolidine derivative and reaction by-products with moisture leak, causing an increase in thermal impedance at the interface, so oxazolidine as a moisture scavenger The amount of derivatives (Oxazolidine Derivatives) added has a critical significance within the above numerical range.

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

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

1. Quantification of the amount of free alkali metal ions contained in dispersed inorganic fillers

Put 100 g of dispersed inorganic filler in the same amount of deionized water with a specific resistance of 10㏁ cm or more, and leave it for 24 hours while stirring in a constant temperature bath maintained at 80°C, and then collect the supernatant water.

Thereafter, the amount of free alkali metal ions was obtained by analysis with an inductively coupled plasma spectrometer (model name: ULTIMA Ⅱ, HORIBA).

2. Quantification of moisture content in dispersed inorganic filler (Karl-Fischer method)

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

3. Hardness (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, the sample was stabilized at room temperature for 2 hours or more. The hardness values of the 3 items and the thermal conductivity values of the 4 items were obtained and compared with the initial values, and heat resistance was evaluated from this. In addition, the rupture test of the following 6 items was performed.

6. Burst test

After the sample was tested under the heat-resistance test conditions of the above 5 items, it was cut with a knife and ruptured in the cross section was observed.

Hereinafter, specific examples are presented to help the understanding of the present invention, and the following examples are only examples for describing the present invention in detail, and the scope of the present invention is not limited to the following examples.

Example 1.

(1) 49g of Vinyl Terminated Poly(dimethylsiloxane) with a viscosity of 1,000cps at 25°C, 49g of Vinyl Terminated Poly(dimethylsiloxane) with a viscosity of 2,000cps at 25°C, dimethylsiloxane- 2g of methylhydrogensiloxane copolymer (Poly(dimethylsiloxane-co-(methylhydrosiloxane)) and average particle diameters of 2㎛, 10㎛, and 70㎛, respectively, with an average free alkali metal ion content of 400ppm and an average moisture content 900 g of 700 ppn alumina (each mixing ratio of 1:1:1) was added to a planetary mixer and uniformly stirred for 0.5 hours.

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

(3) After cooling the dry 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 at 3.24 g, 50 mol% relative to the moisture content contained in alumina, and stirred uniformly for 0.5 hours. After that, a platinum catalyst was added and molded into a desired shape to form a silicone-based fruit. A thermal interface material (TIM) was completed. The content of Oxazolidine Derivatives, a moisture scavenger, was calculated by the following formula.

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

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

Example 2.

Except for adding 6.48 g of 3-ethyl-2-methyl-2-(3-methylbutyl)-1,3-oxazolidine 100 mol% to the composition of Example 1 based on the water content in alumina The same as in Example 1.

Example 3.

Except for adding to the composition of Example 1, 1.30 g of 3-ethyl-2-methyl-2-(3-methylbutyl)-1,3-oxazolidine 20 mol% relative to the water content contained in alumina was added The same as in Example 1.

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.

Except for adding 3-ethyl-2-methyl-2-(3-methylbutyl)-1,3-oxazolidine to the composition of Example 1, 0.65 g, 10 mol%, based on the water content contained in alumina The same as in Example 1.

Comparative Example 3.

Except for adding 3-ethyl-2-methyl-2-(3-methylbutyl)-1,3-oxazolidine to the composition of Example 1, 9.71 g of 150 mol% based on the water content contained in alumina The same as in Example 1.

Example 4.

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

Example 5.

The same as in Example 1 except that the composition of Example 1 was dried at 70° C. instead of drying at 100° C.

Example 6.

The same as in Example 1 except that the composition of Example 1 was dried at 120° C. instead of drying at 100° C.

Comparative Example 4.

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

Comparative Example 5.

It is the same as Example 1 except that the composition of Example 1 was dried at 150° C. instead of drying at 100° C.

Example 7.

It is the same as in 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 in 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 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 Addition amount of moisture remover 50 mol% of water content standard formulation Example 2 100 mol% of water content Example 3 20 mol% of water content Comparative Example 1 0 mol% of water content Comparative Example 2 10 mol% of water content Comparative Example 3 150 mol% of water content Example 4 Moisture remover type Addition of 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) Explosion division Early After heat resistance test Early After heat resistance test Explosion 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 water removal agent is used or a small amount is used, the sample expands and bursts as the absorbed water evaporates at a high temperature. It can be seen that voids are generated and thermal conductivity is lowered.

On the other hand, as shown in Comparative Example 3, even when the moisture removing agent is added in excess of 150 mol% or more compared to the contained moisture, there is no bursting phenomenon or further improvement in thermal conductivity compared to Examples 1 to 3, whereas the initial hardness value is low in the same composition Since there is only a loss, it is judged that there is no meaning in adding more than necessary.

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

Comparing Examples 5 and 6 with Comparative Example 4, when the drying temperature is low, the moisture contained therein is not sufficiently removed, and thus the specimen burst occurs. It can be seen that the thermal conductivity decreases. On the other hand, as shown in Comparative Example 5, even if it is dried at a high temperature of 150° C. or higher, compared to Examples 5 and 6, there is no burst phenomenon or further improvement in thermal conductivity. is judged

Comparing Example 7 and Comparative Example 6, since there is no additional improvement effect 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 not preferable in terms of productivity.

Looking at the above Examples and Comparative Examples, when 20 to 100 mol% of the oxazolidine derivative is added relative to the initial moisture content, the absorbed moisture is converted into aminoalcohol and ketone or aldehyde as shown in Scheme 1, thereby increasing the evaporation of the absorbed moisture during high temperature storage. It can be seen that the burst phenomenon can be effectively controlled.

Although the present invention has been described in more detail with reference to examples above, the present invention is not necessarily limited to these examples, and various modifications may be made within the scope without departing from the spirit of the present invention. Accordingly, 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 by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

Claims (11)

A silicone-based thermal media composition comprising a silicone-based thermal media in which a silicone-based polymer material and a dispersed inorganic filler are mixed, and a moisture eliminator is added. According to claim 1,
The moisture removing agent is a silicone-based thermal medium composition stable at high temperature, characterized in that it is an oxazolidine derivative having a structure as shown in the following Chemical 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). 3. The method of claim 2,
The added 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). A silicone-based thermal medium stable at high temperature, characterized in that it is prepared by drying the composition of claim 1 . 5. The method of claim 4,
The silicone-based thermal medium stable at high temperature, characterized in that the drying temperature is not less than 70 ℃ and not more than 120 ℃. 5. The method of claim 4,
The silicone-based thermal medium stable at high temperature, characterized in that the drying time is 1 hour or more and 3 hours or less. 5. The method of claim 4,
A silicone-based thermal medium stable at a high temperature, characterized in that the drying is carried out at 70°C or more and 120°C or less and under reduced pressure. 8. The method of claim 7,
The pressure reduction is to reduce the pressure in a vacuum state of 10 mmHg or less, and the drying time is a silicone-based thermal medium stable at high temperature, characterized in that it is 1 hour or more and 3 hours or less. preparing a mixture by mixing a silicon precursor in which silicon is produced by the reaction and a dispersed inorganic filler containing free alkali metal ions; and
further adding a moisture remover to the mixture;
A method for producing a silicone-based thermal medium composition, which is stable at high temperature, comprising: 10. The method of claim 9,
The method for producing a silicone-based thermal medium composition stable at high temperature, characterized in that the moisture remover 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). 11. The method of claim 10,
The method for producing a silicone-based thermal intermediary material composition stable at high temperature, characterized in that the amount of the water remover added is 20 mol% or more and 100 mol% or less relative to the moisture contained in the dispersed inorganic filler.

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