Metal-organic composite phase change material with low thermal stress and preparation method thereof

Abstract

The invention discloses a metal-organic composite phase change material with low thermal stress and a preparation method thereof, and the inventor finds that stable compounding of paraffin and liquid metal gallium can be successfully realized by taking expanded graphite as a bridge medium in long-term in-depth research; the prepared composite material has the excellent characteristics of double phase change temperature points, high heat conductivity coefficient, excellent phase change latent heat, low thermal expansion coefficient and the like, can effectively cope with instantaneous thermal shock of electronic chips, and remarkably reduces thermal stress.

Description

Technical Field

[0001] This invention relates to the field of materials technology, specifically to a low thermal stress metal-organic composite phase change material and its preparation method. Background Technology

[0002] As semiconductor technology enters the 2-nanometer era and more advanced nodes, the heat flux density of electronic chips has exceeded 350W / cm². Furthermore, with the continuous increase in power density and the shrinking of package sizes, enormous thermal stresses are generated inside the chip and at its interfaces. This highly concentrated heat flux leads to significant localized thermal stress and deformation within the chip and at the package interface. These problems caused by thermal mismatch severely affect the structural integrity of the chip, the lifespan of solder joints, and even the long-term stability of the entire system.

[0003] Therefore, thermally conductive interface materials (TIMs) used to fill the gap between the chip and the heat sink are crucial for reducing interfacial thermal resistance and preventing thermal runaway of the chip. Currently, mainstream TIM materials each have significant drawbacks. Traditional silicone grease exhibits a pumping effect during long-term use, leading to a significant increase in thermal resistance. While liquid metals possess ultra-high thermal conductivity, their electrical conductivity and the risk of galvanic corrosion to aluminum require stringent protective coatings, increasing process complexity and cost.

[0004] Existing thermal interface materials mostly focus on improving static thermal conductivity. However, there is a lack of effective solutions for how to simultaneously achieve the three mutually restrictive goals of rapid heat conduction, efficient absorption of instantaneous thermal shock, and suppression of interfacial thermal stress under high heat flux density. Summary of the Invention

[0005] To address at least one of the aforementioned technical deficiencies, the present invention provides the following technical solution: The first aspect of this application discloses a low thermal stress metal-organic composite phase change material, comprising the following components by mass: paraffin: 15-25%, gallium: 65-75%, and expanded graphite: 0.5-2%.

[0006] Furthermore, by weight, it comprises the following components: paraffin: 24.75%, gallium: 74.25%, and expanded graphite: 1.0%.

[0007] The second aspect of this application discloses a method for preparing a low-thermal-stress metal-organic composite phase change material, comprising the following steps: First, according to the proportions recorded above, melt the paraffin and gallium together; Second, expandable graphite is added to a molten mixture of paraffin and gallium, heated and stirred to form a composite phase change slurry; Third, the obtained composite phase change slurry is cooled and solidified into the desired shape.

[0008] Furthermore, the expanded graphite is pre-dried at 75-85°C.

[0009] Furthermore, in the third step, the obtained composite phase change slurry is rapidly cooled and cured at -8℃ to -12℃ for 20-30 minutes.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Through long-term and in-depth research, the inventors have discovered that by using expanded graphite as a bridging medium, stable composite material of paraffin and liquid gallium can be successfully achieved. The prepared composite material has excellent properties such as dual phase change temperature point, high thermal conductivity, superior latent heat of phase change and low thermal expansion coefficient. It can effectively cope with the instantaneous thermal shock of electronic chips and significantly reduce thermal stress. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a physical diagram of the preparation of the present invention.

[0013] Figure 2 These are the test data for the thermal storage performance of this invention.

[0014] Figure 3 These are the thermal conductivity test data for this invention.

[0015] Figure 4 These are the thermal expansion performance test data for this invention. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0017] The paraffin (melting point: 52-54℃) used in the examples was purchased from Shanghai Yixing Biotechnology Co., Ltd., and the gallium (melting point: 33℃) was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0018] Example 1: A method for preparing a low thermal stress metal-organic composite phase change material includes the following steps: Step 1: Weigh 5g of paraffin and 15g of gallium, place them in a container, and stir at 300 rpm for 30 minutes at 65°C until they are completely melted and form a preliminary mixture.

[0019] The second step is to place 0.2g of expanded graphite (EG, 50 mesh) in an 80℃ oven and dry it for 2 hours to remove moisture.

[0020] The pretreated expanded graphite was added to the above molten mixture, the temperature was adjusted to 60°C, the stirring speed was increased to 400 rpm, and stirring was continued for 2 hours to form a composite phase change slurry.

[0021] Step 3: Quickly pour the obtained composite slurry into a mold of a predetermined shape, transfer it to a -10°C freezer for rapid cooling and curing for 25 minutes to obtain the desired metal-organic composite phase change thermal interface material.

[0022] Example 2: A method for preparing a low thermal stress metal-organic composite phase change material differs from Example 1 in that the mass ratio of paraffin, gallium, and expanded graphite in this example is 20:68:1.

[0023] Example 3: A method for preparing a low thermal stress metal-organic composite phase change material differs from Example 1 in that the mass ratio of paraffin, gallium, and expanded graphite in this example is 22:70:1.

[0024] The properties of the materials prepared above were tested, and it was found that the materials prepared in this embodiment exhibited consistent performance across all properties. The performance test data of the composite material prepared in Example 1 are presented in this article, such as... Figure 1 As shown, the material formed in Example 1 is relatively uniformly mixed, has a relatively stable structure, and is a regular circular shape. The heat storage performance of this material was measured using a DSC250 differential scanning calorimeter, and the results are as follows... Figure 2 As shown, the composite material exhibits two phase transition temperatures (-29.69℃ and -51.74℃), corresponding to the endothermic melting of gallium and paraffin, respectively. The thermal conductivity of this material was measured using a NETZSCH LFA 467 laser thermal conductivity meter, yielding an average thermal conductivity of 6.07 ± 0.03 W / m·K. (See [reference needed]). Figure 3 The thermal expansion properties of this material were measured using a Netzsch TMA402F3 thermal expansion meter (Germany). See [link to relevant documentation]. Figure 4 The results showed that it did not expand or contract significantly below 50℃, and exhibited a negative temperature coefficient in the 70-80℃ range and a positive temperature coefficient above 80℃, with low overall thermal stress.

[0025] The reason for this is that the composite material exhibits "negative thermal expansion behavior" dominated by the properties of liquid gallium at low temperatures, and "positive thermal expansion behavior" dominated by the thermal expansion of paraffin at high temperatures.

[0026] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A low-thermal-stress metal-organic composite phase change material, characterized in that, By mass, includes the following components: paraffin wax: 15-25%, gallium: 65-75%, expanded graphite: 0.5-2%.

2. A low thermal stress metal-organic composite phase change material as claimed in claim 1, characterized in that: By mass, includes the following components: Paraffin wax: 24.75%, gallium: 74.25%, expanded graphite: 1.0%.

3. A method of preparing a low-thermal-stress metal-organic composite phase change material, characterized by: Comprise the following steps: First, according to the proportion described in claim 1, melt paraffin wax and gallium into one body; Second, add expanded graphite to the molten mixture of paraffin wax and gallium, heat and stir to form a composite phase change slurry; Third, cool the obtained composite phase change slurry to solidify into the desired shape.

4. The method of claim 3, wherein the metal-organic composite phase change material has a low thermal stress. The expanded graphite is dried in advance at 75-85℃.

5. The method for preparing a low thermal stress metal-organic composite phase change material as described in claim 1, characterized in that: In the third step, the obtained composite phase change slurry is rapidly cooled and solidified at -8℃~-12℃ for 20-30min.

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