TW202124613A - Method for reducing surface tension between indium-bismuth alloy and substrate by coating rosin as well as composite material manufactured by the method - Google Patents

Abstract

The present invention relates to a method for reducing the surface tension between an indium-bismuth alloy and a substrate by coating a rosin. The method includes: providing a rosin between a substrate and an indium-bismuth alloy; and heating them above a melting point of the indium-bismuth alloy, so that the indium-bismuth alloy in a liquid state is combined with the substrate. After cooling, the indium-bismuth alloy returns to a solid state and remains combined with the substrate without falling off. By using the rosin, the surfaces of the substrate and the indium-bismuth alloy are joined together and will not be separated after the temperature is lowered. The present invention also relates to a composite material manufactured by the aforesaid method.

Description

Method for coating rosin to reduce surface tension of indium-bismuth alloy and substrate and composite material produced by the method

The invention relates to a method for coating rosin to reduce the surface tension of an indium-bismuth alloy and a substrate and a composite material produced by the method. The surface of the substrate and the indium-bismuth alloy are joined by the rosin and will not separate after cooling.

The heat generating element (herein referred to as the substrate) continuously generates heat during use, and overheating may easily cause the performance of the substrate to deteriorate, such as a decrease in optical characteristics or a decrease in electrical characteristics. Therefore, the heat generated by the substrate needs to be conducted away by the heat dissipating element. Generally, the heat dissipating element uses heat dissipation materials with heat dissipation functions such as metal plates and heat dissipation fins. A large number of pores are formed at the interface due to the bonding of the pores. The pores (the thermal conductivity of the air layer is 0.024W/mK) are prone to thermal siltation, which causes severe thermal resistance and increases the temperature of the substrate. As a result, the heat dissipation effect of the heat sink is not as expected. In order to solve this problem, heat dissipation paste is used to fill the interface pores, but the heat dissipation paste is a polymer material, which is easily degraded by long-term heating. The service life is only 1 to 3 years, and its thermal conductivity is about 2 to 5W/mK, although it is high It is better than air, but still not as good as the thermal conductivity of metal thermal conductive layers (such as alloy materials).

At the solid-liquid interface, the fluidity of the liquid can avoid the generation of pores. Therefore, in order to reduce the pores between the substrate and the heat dissipation material, the metal thermally conductive layer can be melted and then attached to the substrate, and then solidified. However, when the metal thermally conductive layer is in a liquid state, the surface tension is very large, resulting in poor contact between the substrate and the heat sink. Taking indium-bismuth alloy as an example, due to the low wettability of the substrate surface, when the indium-bismuth alloy changes to a liquid state, The surface of the substrate is easy to condense into a spherical shape. Please refer to the third figure. At this time, the contact angle between the liquid indium-bismuth alloy and the substrate is 154.187 degrees. When the substrate moves or tilts, such a large contact angle makes the bonding ability between the indium-bismuth alloy and the substrate poor, and the indium-bismuth alloy may overflow outside the substrate. When the substrate is a part of the electronic product, if the conductive indium-bismuth alloy overflows, it may even cause a short circuit of the substrate and damage the entire electronic product.

In summary, the present invention proposes a method for coating rosin to reduce the surface tension of the indium-bismuth alloy and the substrate. The rosin reduces the surface tension of the indium-bismuth alloy to improve the bonding with the substrate and improve the thermal conductivity of the indium-bismuth alloy to the substrate.

The method of the present invention includes the presence of a rosin between a substrate and an indium-bismuth alloy; making the indium-bismuth alloy above the melting point of the indium-bismuth alloy and the indium-bismuth alloy in a liquid state are combined with the substrate. After cooling, the indium can still be maintained in a solid state. The bismuth alloy is combined with the substrate without separation.

Further, the heating temperature of the indium-bismuth alloy is between 80 and 250°C.

Further, the substrate is copper.

Furthermore, the contact angle between the indium-bismuth alloy and the substrate is less than 50 degrees.

Further, tin metal is added to the indium-bismuth alloy, and the tin metal content is less than 40 wt%.

Furthermore, before the rosin is coated on the substrate, the surface of the substrate is cleaned.

Further, the base phase of the indium-bismuth alloy is BiIn ₂ phase or BiIn phase.

The present invention further provides a composite material coated with rosin to reduce the surface tension of indium-bismuth alloy and substrate, including a substrate, a rosin and an indium-bismuth alloy. The rosin coats the substrate. The indium-bismuth alloy is connected to the rosin; the contact angle between the indium-bismuth alloy and the substrate is increased by the rosin.

Further, the substrate is made of metal, plastic, or ceramic.

Furthermore, the indium-bismuth alloy contains less than 40wt% tin.

According to the above technical features, the following effects can be achieved:

1. The present invention coats rosin between the substrate and the indium-bismuth alloy. The rosin reduces the surface tension of the indium-bismuth alloy when heated to a liquid state, improves the bond between the liquid indium-bismuth alloy and the substrate, and improves the resistance of the indium-bismuth alloy to the substrate. Thermal effect.

2. The use of rosin in the present invention can make the contact angle between the indium-bismuth alloy and the substrate less than 50 degrees.

3. The base phase of the indium-bismuth alloy of the present invention is BiIn ₂ phase or BiIn phase.

Based on the above technical features, the method for reducing the surface tension of the indium-bismuth alloy and the substrate of the present invention with coated rosin and the main effects of the composite material produced by the method will be clearly presented in the following embodiments.

It should be particularly noted that in the following different composition ratios, components with the same name are marked with the same symbols.

Please refer to the first figure. The composite material coated with rosin to reduce the surface tension of indium-bismuth alloy and substrate of the present invention includes a substrate (3), a rosin (2) and an indium-bismuth alloy (1). The substrate (3) is made of metal, plastic or ceramic. The indium-bismuth alloy (1) contains less than 40wt% tin. The rosin (2) is coated between the substrate (3) and the indium-bismuth alloy (1), and a contact angle of the indium-bismuth alloy (1) and the substrate (3) is increased by the rosin (2).

Please refer to the first and second figures, the method for reducing the surface tension of the indium-bismuth alloy and the substrate by coating rosin of the present invention is to bond the indium-bismuth alloy (1) to the substrate (3) through the rosin (2) , And heat the indium-bismuth alloy (1) to a temperature between 80 and 250°C. The rosin (2) reduces the surface tension of the indium-bismuth alloy (1) on the substrate (3) by reducing the surface tension of the indium-bismuth alloy (1) on the substrate (3) by the rosin (2) and cleaning impurities on the surface of the substrate (3). The contact angle between the alloy (1) and the substrate (3) is reduced from more than 150 degrees to less than 50 degrees. The substrate (3) is made of metal, plastic or ceramic. The indium-bismuth alloy (1) can be added with tin metal, and the tin metal content is less than 40 wt%. Furthermore, before the rosin (2) is coated on the substrate (3), the surface of the substrate (3) is cleaned. The cleaning process is mainly to remove grease or oxide on the surface of the substrate (3) first, so that the rosin (2) is coated between the substrate (3) and the indium-bismuth alloy (1), which can be further improved Increase the contact angle and contact area.

The above-mentioned rosin has the effects of assisting heat conduction, removing oxides, reducing the surface tension of the material, removing oil on the surface of the material, increasing the contact area, and preventing reoxidation. Among these effects, the more critical functions are: removal of oxides And reduce the surface tension of the material.

Please refer to the third and fourth figures, this embodiment shows the contact angle of the indium-bismuth alloy with the substrate (3) at the first composition ratio. The composition ratio of the indium-bismuth alloy (1) is 67wt% indium and 33wt% bismuth. When the substrate (3) is heated to the melting point of the indium-bismuth alloy (1), it can be observed that the contact angle of the indium-bismuth alloy (1) without the liquid phase of the rosin (2) and the substrate (3) is 154.187. When the rosin (2) is bonded to the substrate (3), the contact angle of the indium-bismuth alloy (1) in the liquid phase with the substrate (3) is 50 degrees.

Table 1. The relationship between the total thermal conductivity and the total thermal resistance of the indium-bismuth alloy of this example under the first composition ratio versus time Time (hr) Uncoated rosin Coated rosin Total heat transfer rate U(W/m ² °C) Total thermal resistance R(°C/W) Total heat transfer rate U(W/m ² °C) Total thermal resistance R(°C/W) 1 26.01 10.68 26.71 10.4 2 26.06 10.66 26.76 10.38 3 25.96 10.7 26.81 10.36

Table 1. The total heat transfer rate of the indium-bismuth alloy (1) without the rosin (2) is 25.96 to 26.06 (W/m ² °C), and the total thermal resistance is 10.66 to 10.7R (°C/ W). The indium-bismuth alloy (1) coated with the rosin (2) has a total heat transfer rate of 26.71 to 26.81 (W/m ² °C), and a total thermal resistance value of 10.36 to 10.4R (°C/W), and It can be observed from the above table that the indium-bismuth alloy (1) coated with the rosin (2) is better than uncoated in total heat transfer rate and total thermal resistance. Please refer to the fifth figure, when the indium-bismuth alloy (1) coated with the rosin (2) is continuously heated, the total heat transfer rate increases with the heating time from the first hour to the third hour, and the total thermal resistance The value will decrease with the heating time.

Please refer to Figures 6 and 7. This embodiment shows the contact angle of the indium-bismuth alloy with the substrate (3) at the second composition ratio. The second composition ratio is different from the first composition ratio in that the liquid phase indium The bismuth alloy (2) contains 16.5wt% tin, and contains 51wt% indium and 32.5wt% bismuth. When the substrate (3) is heated to the melting point of the indium-bismuth alloy (1), it can be observed that the contact angle between the indium-bismuth alloy (1) and the substrate (3) without using the liquid phase of the rosin (2) is 155.186 When the rosin (2) is bonded to the substrate (3), the contact angle of the indium-bismuth alloy (1) in the liquid phase with the substrate (3) is 49.091 degrees.

Table 2. The relationship between the total thermal conductivity and the total thermal resistance of the indium-bismuth alloy of this example under the second composition ratio versus time Time (hr) Uncoated rosin Coated rosin Total heat transfer rate U(W/m ² °C) Total thermal resistance R(°C/W) Total heat transfer rate U(W/m ² °C) Total thermal resistance R(°C/W) 1 26.01 10.68 27.18 10.22 2 26.11 10.64 27.18 10.22 3 26.11 10.64 26.71 10.4

Table 2. The total heat transfer rate of the indium-bismuth alloy (1) without the rosin (2) is 26.01 to 26.11 (W/m ² °C), and the total thermal resistance is 10.64 to 10.68R (°C/ W). The indium-bismuth alloy (1) coated with the rosin (2) has a total heat transfer rate of 26.71 to 27.18 (W/m ² °C), and a total thermal resistance value of 10.22 to 10.4R (°C/W), and It can be observed from the above table that the indium-bismuth alloy (1) coated with the rosin (2) is better than uncoated in total heat transfer rate and total thermal resistance. Please refer to the fifth figure, when the indium-bismuth alloy (1) coated with the rosin (2) is continuously heated, the total heat transfer rate increases with the heating time from the first hour to the third hour, and the total thermal resistance The value will decrease with the heating time.

For the third embodiment of the present invention, please refer to the ninth and tenth figures. In this embodiment, the contact angle between the indium-bismuth alloy and the substrate (3) at the third composition ratio, the third composition ratio and the second composition ratio The difference is that the liquid phase indium-bismuth alloy (2) increases tin metal to 18wt% tin, and contains 25wt% indium and 57wt% bismuth. When the substrate (3) is heated to the melting point of the indium-bismuth alloy (1), it can be observed that the contact angle of the indium-bismuth alloy (1) without the liquid phase of the rosin (2) and the substrate (3) is 150.422. When the rosin (2) is bonded to the substrate (3), the contact angle between the indium-bismuth alloy (1) and the substrate (3) in the liquid phase is 48.683 degrees.

Table 3. The relationship between the total thermal conductivity and the total thermal resistance of the indium-bismuth alloy of this example under the third composition ratio versus time Time (hr) Uncoated rosin Coated rosin Total heat transfer rate U(W/m ² °C) Total thermal resistance R(°C/W) Total heat transfer rate U(W/m ² °C) Total thermal resistance R(°C/W) 1 26.51 10.48 26.56 10.46 2 26.40 10.52 26.76 10.38 3 26.35 10.54 26.71 10.4

Table 3, the total heat transfer rate of the indium-bismuth alloy (1) without the rosin (2) is 26.35 to 26.51 (W/m ² °C), and the total thermal resistance is 10.48 to 10.54R (°C/ W). The indium-bismuth alloy (1) coated with the rosin (2) has a total heat transfer rate of 26.56 to 27.76 (W/m ² °C), and a total thermal resistance value of 10.38 to 10.46R (°C/W), and It can be observed from the above table that the indium-bismuth alloy (1) coated with the rosin (2) is better than uncoated in total heat transfer rate and total thermal resistance. Please refer to the fifth figure, when the indium-bismuth alloy (1) coated with the rosin (2) is continuously heated, the total heat transfer rate increases with the heating time from the first hour to the third hour, and the total thermal resistance The value will decrease with the heating time.

From the first composition ratio to the third composition ratio, it can be observed that the presence of the rosin between the substrate and the indium-bismuth alloy can significantly reduce the surface tension of the indium-bismuth alloy, so that the antennae of the indium-bismuth alloy is increased from more than 150 degrees , Reduced to less than 50 degrees, the total heat transfer rate of the indium-bismuth alloy can be increased by the contact angle less than 50 degrees, and the total thermal resistance value can be reduced so that the indium-bismuth alloy can achieve the effect of leading out the substrate, and the heating is continued. The effect is better under the circumstances.

Based on the description of the above embodiments, when one can fully understand the operation and use of the present invention and the effects of the present invention, but the above embodiments are only the preferred embodiments of the present invention, and the implementation of the present invention cannot be limited by this. The scope, that is, simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the content of the description of the invention, are all within the scope of the present invention.

(1): Indium-bismuth alloy (2): Rosin (3): Substrate

[The first figure] is a cross-sectional view of the composite material manufactured by the method of the present invention. [The second figure] is a flowchart of the manufacturing method of the present invention. [The third figure] is a photo of the contact angle of the indium-bismuth alloy with the substrate at the first composition ratio when the rosin is not coated. [Fourth figure] is a photograph of the contact angle of the indium-bismuth alloy with the substrate at the first composition ratio in the embodiment of the present invention. [Fifth Figure] is a graph showing the relationship between the total thermal conductivity and the total thermal resistance of the indium-bismuth alloy at the first composition ratio versus time according to the embodiment of the present invention. [Figure 6] This is a photo of the contact angle of the indium-bismuth alloy with the substrate at the second composition ratio when the rosin is not coated. [The seventh figure] is a photograph of the contact angle of the indium-bismuth alloy with the substrate at the second composition ratio in an embodiment of the present invention. [Eighth Figure] is an example of the present invention, the total thermal conductivity and total thermal resistance of the indium-bismuth alloy at the second composition ratio versus time. [Figure 9] This is a photo of the contact angle of the indium-bismuth alloy with the substrate at the third composition ratio when the rosin is not coated. [Tenth Figure] is a photograph of the contact angle between the indium-bismuth alloy and the substrate at the third composition ratio in an embodiment of the present invention. [The eleventh figure] is an example of the present invention, the total thermal conductivity and total thermal resistance of the indium-bismuth alloy at the third composition ratio versus time.

(1): Indium-bismuth alloy

(2): Rosin

(3): Substrate

Claims (10)

A method for coating rosin to reduce the surface tension of indium-bismuth alloy and substrate, comprising: There is a rosin between a substrate and an indium-bismuth alloy; When the melting point of the indium-bismuth alloy is higher than the melting point, the liquid-state indium-bismuth alloy is combined with the substrate, and after cooling, the solid-state indium-bismuth alloy is combined with the substrate without separation. The method for reducing the surface tension of the indium-bismuth alloy and the substrate by coating rosin as described in item 1 of the scope of the patent application, wherein the heating temperature of the indium-bismuth alloy is between 80 and 250°C. The method for reducing the surface tension of the indium-bismuth alloy and the substrate by coating rosin as described in item 1 of the scope of the patent application, wherein the substrate is made of metal, plastic, or ceramic. The method for reducing the surface tension of the indium-bismuth alloy and the substrate by coating rosin as described in item 1 of the scope of the patent application, wherein the contact angle between the indium-bismuth alloy and the substrate is less than 50 degrees. The method for reducing the surface tension of the indium-bismuth alloy and the substrate by coating rosin as described in item 1 of the scope of the patent application, wherein the liquid phase indium-bismuth alloy contains less than 40wt% tin. The method for reducing the surface tension between the indium-bismuth alloy and the substrate by coating rosin as described in item 1 of the scope of the patent application, furthermore, before the rosin is coated on the substrate, the surface of the substrate is cleaned. The method for reducing the surface tension of the indium-bismuth alloy and the substrate by coating rosin as described in item 1 of the scope of patent application, wherein the base phase of the indium-bismuth alloy is BiIn ₂ phase or BiIn phase. A composite material coated with rosin to reduce the surface tension of indium-bismuth alloy and substrate, comprising A substrate; A rosin, which coats the substrate; An indium-bismuth alloy, the indium-bismuth alloy is connected to the rosin; The rosin increases the contact angle between the indium-bismuth alloy and the substrate. As described in item 8 of the scope of patent application, the composite material coated with rosin to reduce the surface tension of the indium-bismuth alloy and the substrate, wherein the substrate is made of metal, plastic or ceramic. As described in item 8 of the scope of patent application, the rosin-coated composite material for reducing the surface tension of the indium-bismuth alloy and the substrate, wherein the indium-bismuth alloy contains less than 40wt% tin.

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