KR102600194B1 - Heat dissipation device comprising Heat absorption pad - Google Patents

Abstract

The present invention relates to a heat dissipation device that includes a heat absorption pad and a capping film to seal the same, absorbing heat generated from a semiconductor chip and blocking heat transfer to the external case of an electronic device.

Description

Heat dissipation device comprising heat absorption pad}

The present invention relates to a heat dissipation device having a heat absorption pad. More specifically, the present invention relates to a heat dissipation device having a heat absorption pad and a capping film to seal the heat absorption pad to absorb heat generated from a semiconductor chip and block heat transfer to the external case of the electronic device. It is about a heat dissipation device.

In general, SSD (Solid State Drive) is a semiconductor disk that uses flash memory or DRAM as a storage medium, so it can read and write much faster than the conventional physically driven HDD, and it does not generate any noise, so it has recently been developed. The number of users is rapidly expanding.

A solid state drive (SSD) includes a printed circuit board (PCB), a host interface connector connected to the PCB, flash memory mounted on the PCB, and a controller (DRIVE IC chip). For SSDs, semiconductor chips such as flash memory or DRAM are mounted on a PCB and built into an SSD housing (case).

SDD generates a significant amount of heat from the semiconductor chip during operation. As the chip integration (capacity) gradually increases, the heat generated from the chip also increases. When the heat of the chip increases, product performance deteriorates due to a decrease in data transfer speed. do. To prevent this, HDDs or SSDs remove heat through thermally conductive pads, heat sinks, or cooling fans.

Korean Patent Publication No. 10-2014-0004864 discloses a heat dissipation case including a heat dissipation metal plate 32 made of a thermally conductive metal to dissipate heat generated from an SSD and an outlet 33 through which heat is dissipated (FIG. 1 reference). As shown in FIG. 1, when heat is removed through a thermally conductive metal, the heat must inevitably be discharged to the outside of the case, so the temperature of the case may rise, or heated air may be discharged through the discharge port, thereby transferring heat to the human body. For this reason, in the case of electronic products that come into contact with the consumer's body, there is a temperature limit on the contact area (temperature limit of 40℃ to prevent burns), so there is a limitation in transferring much of the heat from the chip to the case (as a result, there is a limit to the amount of heat dissipation). There were difficulties in increasing the efficiency (data movement speed) of the device.

The present invention provides a heat dissipation system that can significantly reduce the temperature rise of the case by blocking heat transfer to the outside of the case compared to existing methods.

The present invention provides a heat dissipation device that can increase the heat dissipation efficiency and durability of electronic devices such as SSDs.

This invention

A heat absorption pad (10) that contacts the upper surface of a semiconductor chip mounted on a printed circuit board and includes a cured silicone binder (11) and phase change microcapsules (12) dispersed within the silicone binder; and

A heat dissipation device including a capping film (20) that surrounds and seals the heat absorption pad (10),

The heat dissipation device is installed inside the housing (case) of the electronic device, and when heat generated from the semiconductor chip is transferred to the heat absorption pad via the capping film 20, the heat absorption pad is connected to the phase change micro It relates to a heat dissipation device characterized by absorbing heat into a capsule and blocking heat transfer to the outside of the housing (case).

The heat dissipation device of the present invention uses a silicon pad with phase change microcapsules dispersed and fixed inside, thereby sufficiently absorbing heat generated from the semiconductor chip through the phase change material to block heat transfer to the electronic device housing (case). there is. As a result, the heat dissipation device of the present invention can contribute to improving product performance by increasing the transmission speed or capacity of electronic devices (external storage devices, etc.) without significantly increasing the temperature of the housing compared to existing thermally conductive pads or metals.

In addition, since the heat dissipation device of the present invention does not use thermally conductive metal or filler inside, it is 2.5 to 3 times lighter in weight (under the same volume conditions) compared to existing thermally conductive pads, thereby increasing the marketability of electronic devices.

In addition, existing thermally conductive pads were made of rubber and sometimes stretched, making assembly difficult. However, the heat dissipation device of the present invention wraps the heat-absorbing pad with a capping film that has a lower elongation than a silicone binder, and is manufactured to the desired size. It is possible and does not stretch when used, improving assemblyability and durability.

In addition, if repeated thermal shock is applied to the heat absorption pad where the phase change microcapsules are dispersed, the microcapsules may be destroyed over time and the phase change material inside may leak out of the silicon binder. However, the heat dissipation device of the present invention By providing a capping film that seals the heat absorption pad, leakage of phase change material can be prevented and the durability of the heat absorption pad can be increased.

Figure 1 is a cross-sectional view of a heat dissipation case disclosed in Korean Patent Publication No. 10-2014-0004864.
Figure 2 is a schematic diagram of an SSD in which the heat dissipation device of the present invention is installed.
Figure 3 is a cross-sectional view of the heat dissipation device of the present invention.
Figure 4 is an assembly diagram of sealing the heat absorption pad with a capping film.
Figure 5 is a schematic diagram of a heat dissipation characteristic testing device.

Hereinafter, implementation examples and examples of the present invention will be described in detail so that those skilled in the art can easily practice it.

The terminology used herein is only used to describe specific embodiments and is not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, operations, components, or a combination thereof described in the specification, but are not intended to indicate the presence of one or more other features or It should be understood that this does not exclude in advance the possibility of the presence or addition of numbers, steps, operations, components, or combinations thereof.

Figure 2 is a schematic diagram of an SSD on which the heat dissipation device of the present invention is installed, Figure 3 is a cross-sectional view of the heat dissipation device of the present invention, Figure 4 is an assembly diagram of sealing the heat absorption pad with a capping film, and Figure 5 is a heat dissipation characteristic test. This is an overview of the device.

Referring to Figures 2 and 3, the heat dissipation device of the present invention includes a heat absorption pad 10 and a capping film 20.

The heat absorption pad 10 may be installed in contact with the upper surface of the semiconductor chip 2 mounted on the printed circuit board 1.

The heat absorption pad 10 includes a cured silicone binder 11 and phase change microcapsules 12 dispersed within the silicone binder.

The phase change microcapsule 12 may contain a phase change material having a melting point in the range of 40 to 50° C. inside the capsule.

The phase change microcapsule includes a shell formed of a phase change material as the core and a high molecular weight polymer surrounding the core.

The phase change microcapsule may be a known product. For example, polymers forming the shell include polyhydroxyalconates, polyamides, polyamines, polyimides, polyacrylics (e.g. polyacrylamide, polyacrylonitrile and esters of methacrylic acid and acrylic acid), Polycarbonates (e.g. polybisphenol A carbonate and polypropylene carbonate), polydienes (e.g. polybutadiene, polyisoprene and polynorbornene), polyepoxides, polyesters (e.g. poly caprolactone, polyethylene adipate, polybutylene adipate, polypropylene succinate, polyesters based on terephthalic acid and polyesters based on phthalic acid), polyethers (e.g. polyethylene glycol or polyethylene oxide, polybutylene glycol, polypropylene oxide) seeds, polyoxymethylene or paraformaldehyde, polytetramethylene ether or polytetrahydrofuran and polyepichlorohydrin), polyfluorocarbons, formaldehyde polymers (e.g. urea-formaldehyde, melamine-formaldehyde and phenol) formaldehyde), natural polymers (e.g. polysaccharides such as cellulose, chitin, chitosan and starch; lignin; proteins; and waxes), polyolefins (e.g. polyethylene, polypropylene, polybutylene, polybutene and polyoctene), poly Phenylenes, silicon-containing polymers (e.g. polydimethyl siloxane and polycarbomethyl silane), polyurethanes, polyvinyls (e.g. polyvinylbutyral, polyvinyl alcohol, esters and ethers of polyvinyl alcohol, polyvinyl acetate) , polystyrene, polymethylstyrene, polyvinyl chloride, polyvinyl pyrrolidone, polymethyl vinyl ether, polyethyl vinyl ether and polyvinyl methyl ketone), polyacetals, polyarylates, alkyl-based polymers (e.g. glyceride oils) Base polymer), copolymers (e.g. polyethylene-co-vinyl acetate and polyethylene-co-acrylic acid), mixtures thereof, etc. may be polymerized to form.

The phase change materials include N-Paraffin series, unsaturated fatty acid series (Fatty Acids), polyglycol series, alcohol series, phenol series, aldehyde series, and ketone. Series, Ether series, etc. may be used.

Preferably, the phase change material may be a paraffin-based material with a melting point of 40 to 50°C and a latent heat amount of 180 J/g or more. The phase change material may be n-docosane, n-tricosane, or heneicosane.

The microcapsule 12 may have a size of 5 to 25 μm. The larger the size, the higher the heat capacity, but there is a problem that it is difficult to manufacture it in the form of a pad because there is a high probability that the capsule will be destroyed when dispersing.

The silicone binder 11 may be formed by curing liquid silicone rubber (LSR). The liquid silicone may be a polyorganosilonic acid resin such as polydimethylsiloxane.

The viscosity of the liquid silicone may be in the range of 200 cps to 40,000 cps.

The liquid silicone may be a polyorganosiloxane resin having at least one vinyl group.

The cured silicone binder may have a hardness of 40 to 50 (Shore 00 type), an elongation of 30 to 70%, and a thermal conductivity of 0.2 to 0.25.

The heat absorption pad may include 50 to 130 parts by weight, preferably 100 to 130 parts by weight, of microcapsules relative to 100 parts by weight of the silicone binder. Alternatively, the heat absorption pad may include 30% to 60% by weight of microcapsules. If the microcapsule exceeds 130 parts by weight, there is a problem of slurry (semi-finished product) mixing (particle dispersion problem), and if it is less than 50 parts by weight, the heat absorption capacity of the heat absorption pad decreases.

The heat-absorbing pad is mixed with 50 to 130 parts by weight of microcapsules and 1 to 2 parts by weight of a curing agent relative to 100 parts by weight of a silicone binder, and the mixture is molded into a pad shape by using a roll to roll device. , and can be manufactured by curing it.

The mixing process involves mixing the silicone binder, phase change microcapsules, and curing agent at 25±10°C and the stirrer RPM below 7 for 4 to 7 hours.

More specifically, the mixing process involves mixing the phase change microcapsules for a sufficient period of time (5 to 6 hours) to ensure that there are no lumps within the silicone binder, and then adding a curing catalyst to the mixed mixture and vacuuming (below -700 mm/Hg). ) state, it can be stirred for an additional hour using a planetary mixer for high viscosity.

Among the above mixing conditions, if the RPM exceeds 7 or the temperature exceeds the above conditions, shock is continuously applied to the microcapsules, which may reduce durability. In other words, it may cause cracks or damage to the capsule during mixing or molding, and furthermore, it may cause leakage or damage of the PCM material in the microcapsule during use of the heat absorption pad.

The blended mixture can be put into a roll to roll device and formed into a pad with a thickness of 1 to 20 mm, preferably 2 to 10 mm. If the thickness is less than 1 mm, it cannot contain a sufficient amount of microcapsules, which limits its use as a heat dissipation device for electronic devices subject to continuous and repeated thermal shock.

The heat absorption pad can be manufactured by curing a pad formed to a predetermined thickness. The curing reaction is a reaction in which a temperature of 120 ± 5° C. is applied to the pad for 10 to 20 minutes. If the curing reaction is performed below 110℃, the silicone binder is not sufficiently cured, and if the curing reaction is performed above 130℃, the capsule is damaged and the material in the capsule interferes with the curing of the silicone, partially preventing curing, resulting in product defects. Additionally, due to high curing temperature, the phase change microcapsule wall may be damaged, reducing thermal shock reliability (85℃ to -40℃).

The heat-absorbing pad of the present invention is more effective in protecting microcapsules from impact than other high-hardness polymers by using silicone, which has low hardness and high elongation and thermal conductivity, as a binder.

The capping film 20 surrounds and seals the heat absorption pad 10.

The capping film 20 may have a density of 1.2 g/cm3 or more, preferably 1.3 g/cm3 or more. The capping film 20 has a high density of 1.2 g/cm3 or more, so even when the shell of the phase change microcapsule is damaged, it can prevent the internal phase change material from penetrating the capping film and leaking into the electronic device. If the density of the capping film 20 is less than 1.2 g/cm3, the leaked phase change material may slowly pass through the film and flow out.

The capping film 20 may be PET (polyethylene terephthalate) or polyimide, which has excellent heat resistance (melting point, glass transition temperature).

Figure 3 is an exploded and assembled view of coupling the capping film 20 to the heat absorption pad 10. Referring to FIG. 3, capping films 20a and 20b are located on the upper and lower sides of the heat absorption pad 10, respectively, and the capping films 20a and 20b can be heat-sealed with an adhesive film (3, thermosetting hot melt film).

The thickness of the capping film may be 10 to 350 μm, preferably 50 to 100 μm. If the thickness of the capping film is less than 50㎛, the film may be severely deformed during heat compression and thermal shock reliability may be reduced.

As above, the capping film can prevent the phase change material from leaking and increase the assemblyability and durability of the heat absorption pad.

In another aspect, the present invention relates to a method of manufacturing a heat absorption and heat dissipation device, and the manufacturing method of the present invention includes a mixing step of mixing liquid silicone rubber, phase change microcapsules, and a curing agent, and a roll to roll of the blended mixture. It includes the steps of manufacturing a heat-absorbing pad by molding it with a roll device, curing the heat-absorbing pad by applying heat, and sealing the cured heat-absorbing pad by surrounding it with a capping film. .

The manufacturing method of the present invention can refer to the heat dissipation device described above with reference to FIGS. 2 to 5.

The mixing step may be a step of mixing 50 to 130 parts by weight of microcapsules and 1 to 2 parts by weight of a curing agent relative to 100 parts by weight of the liquid silicone rubber.

The phase change microcapsule 12 contains a phase change material having a melting point in the range of 40 to 50° C., the heat capacity of the phase change microcapsule 12 is 180 J/g or more, and the size is 5 to 25°C. It may be ㎛.

The mixing step may be a step of mixing for 4 to 7 hours at a stirrer RPM of 7 or less while maintaining 25 ± 10°C.

The mixing step may be mixing for 4 to 7 hours at an RPM of the stirrer of 7 or less.

The heat absorption pad manufacturing step may be a step of molding the pad to a thickness of 2 to 20 mm.

In the curing reaction step, the temperature may be 120 ± 5°C and the curing time may be 10 to 20 minutes.

The capping film 20 may have a density of 1.2 g/cm3 or more and a thickness of 50 to 350 μm.

The capping film 20 may be PET (polyethylene terephthalate) or polyimide.

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention in more detail, and it is obvious to those skilled in the art that the scope of the present invention is not limited by these examples according to the gist of the present invention.

Example 1

Add 48g of Silicone Binder (WACKER sil-gel 650), 52g of phase change capsule powder (Insilico P-Thermoball 45BN, see Table 1 below), and 0.1g of hardener (HANS CHEMICAL CL200) and mix using a planetary mixer for high viscosity. proceeded. During mixing, the temperature was maintained at 25°C using a cooler, and the RPM was maintained at a maximum of 7 (stirring at rpm 6).

After mixing the phase change capsule powder (PCM Capsule powder) for a sufficient period of time (approximately 5 to 6 hours) to prevent any lumps, add 0.2 g of curing catalyst (DY SILICONE PTC310) and place under vacuum (-700 mm/Hg or less) for 1 hour. It was further stirred using a planetary mixer for high viscosity.

The completed mixture was put into a roll to roll molding equipment, molded to a thickness of 2 mm, and cured at 120°C for about 10 minutes. Afterwards, it was dried at room temperature to obtain a heat absorption pad.

The manufactured heat-absorbing pad was cut into 50 mm horizontally and 30 mm vertically, wrapped with a 0.1 mm thick PET film (XP35, Toray), and then adhered with a hot melt film (INH-5050PH, Instek) (see Figure 4).

capsule size Capsule wall thickness Substance in Capsule Insilico P-Thermoball 45BN 7~20um 200~300nm N-Docosane

Comparative Example 1

A heat absorption pad was manufactured in the same manner as in Example 1, except that the phase change capsule powder was changed to Microtek 43D (see Table 2 below).

capsule size Capsule wall thickness Substance in Capsule Microtek 43D 15~30um 60~100nm Paraffin Wax

Comparative Example 2

A heat absorption pad was manufactured in the same manner as in Example 1, except that 65 g of the phase change capsule powder was added.

Comparative Example 3

A heat absorption pad was manufactured in the same manner as in Example 1, except that the mixing conditions were stirred at a mixer RPM of 15 for about 2 hours.

Comparative Example 4

A heat absorption pad was manufactured in the same manner as in Example 1, except that the molded pad was cured at a temperature of 150°C for about 5 minutes.

Comparative Example 5

The heat absorption pad prepared in Example 1 was used without being sealed with a PET film.

Comparative Example 6

The heat absorption pad prepared in Example 1 was sealed with PE film.

Comparative Example 7

A heat absorption pad was manufactured in the same manner as Example 1, except that an acrylic binder was used instead of a silicone binder.

Comparative Example 8

A thermally conductive silicone pad was manufactured in the same manner as Example 1, except that thermally conductive ceramic (alumina) powder was used instead of heat-absorbing capsule powder.

[test]

Example 1 and Comparative Examples 1 to 8 were tested for compoundability, moldability, thermal shock reliability, high temperature reliability, and heat dissipation characteristics, and are shown in Table 3 below.

item Compatibility Formability Thermal shock reliability High temperature
reliability radiation
characteristic note Example O O O O T1:45℃
T2:32℃ All results, including heat dissipation characteristics, are stable. Comparative Example 1 O O X O - Because the thickness of the capsule wall was thin and the size of the capsule was large, the capsule was destroyed after the thermal shock test and paraffin leaked heavily inside the encapsulated PET film. (At high temperatures, it exists in a liquid state and becomes very hard at room temperature.) Comparative example 2 O X X O - The amount of capsule powder added is too large, so mixing is not possible. Comparative example 3 O X X O - When mixing, the RPM is too high and the capsule is destroyed by physical force, causing the paraffin inside the capsule to leak out. After spilling, it exists in liquid form at high temperature, so pad molding does not occur. Comparative Example 4 O O X O - Because the curing temperature during molding was too high, the capsule wall was largely destroyed, resulting in the same phenomenon as Comparative Example 1 after thermal shock reliability. Comparative Example 5 O O X O - After the thermal shock test, paraffin leaked to the outside, causing appearance defects. Comparative Example 6 O O X O - After a small amount of paraffin leaks, it passes through the relatively low-density PE film in a gaseous state, leaking out of the film and causing poor appearance. Comparative example 7 O O O X T1:46℃
T2:33℃ After high temperature reliability, the hardness of the pad increases, resulting in poor assembly. Comparative example 8 O O O O
T1:43℃
T2:40℃ The temperature of T1 (heating part chipset) is very stable, but the temperature of T2 (case) is too high, resulting in failure.

Formability conditions: After curing and drying, whether the mixture is molded into a pad.

Thermal shock reliability conditions: The manufactured heat absorption pad was kept at 20℃ for 10 minutes → temperature raised to 60℃ for 10 minutes → maintained at 60℃ for 10 minutes → cooled to 20℃ for 10 minutes → maintained at 0℃ for 10 minutes (1 cycle), repeated for 1,000 cycles.

High-temperature reliability conditions: The manufactured heat-absorbing pad was exposed to 150°C for 1,000 hours.

Additionally, heat dissipation characteristics were measured as follows.

Measurement conditions (condition temperature of 25℃) - Refer to the heat dissipation characteristic test device in Figure 5.

(1) In the absence of a test sample (manufactured heat absorption pad), the heating element was set so that the temperature of T1 was approximately 90°C for 15 minutes.

(2) After the heating element was completely cooled, the sample was introduced and the PC plate was set so that it completely touches the top of the sample.

(3) T1 and T2 temperatures were measured 15 minutes after turning on the heating element.

* T1 is under 55℃, T2 is under 40℃.

So far, we have looked at specific embodiments of the present invention. A person skilled in the art to which the present invention pertains will understand that the present invention may be implemented in a modified form without departing from its essential characteristics. The scope of the present invention is indicated in the claims rather than the foregoing description, and all differences within the equivalent scope should be construed as being included in the present invention.

Claims (7)

A heat absorption pad (10) that contacts the upper surface of the semiconductor chip (2) mounted on the printed circuit board (1) and includes a cured silicone binder (11) and phase change microcapsules (12) dispersed within the silicone binder. ) ; and
A heat dissipation device including a capping film (20) that surrounds and seals the heat absorption pad (10),
The heat dissipation device is installed inside the housing (30, casing) of the electronic device, and when heat generated from the semiconductor chip is transferred to the heat absorption pad via the capping film 20, the heat absorption pad is installed on the upper surface. A heat dissipation device characterized in that it absorbs heat with change microcapsules and blocks heat transfer to the outside of the housing (30, casing). The heat dissipation device according to claim 1, wherein the heat absorption pad includes 50 to 130 parts by weight of microcapsules (12) relative to 100 parts by weight of the silicon binder. The method of claim 1, wherein the heat absorption pad (10) is a plate-shaped pad with a thickness (L) of 1 to 20 mm,
The capping film is a film with a thickness (S) of 10 to 350㎛, wrapped around the heat-absorbing pad, and then the film is adhered, or the heat-absorbing pad is placed between the upper film and the lower film and then attached to the upper film and the lower film. A heat dissipation device characterized in that the edges of the are bonded. The method of claim 1, wherein the microcapsule (12) contains a phase change material having a melting point in the range of 40 to 50° C.,
A heat dissipation device characterized in that the heat capacity of the phase change material is 180 J/g or more, and the size of the microcapsule (12) is 5 to 25 ㎛. The heat dissipation device according to claim 1, wherein the film (20) has a density of 1.2 g/cm3 or more and a glass transition temperature of 60°C or more. The heat dissipation device according to claim 1, wherein the film (20) is made of PET (polyethylene terephthalate) or polyimide. The heat dissipation device according to claim 1, wherein the silicone binder has a hardness of 40 to 50 (Shore 00 type) and an elongation of 30 to 70%.

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