KR102445961B1 - Method of preparing heat dissipation device comprising Heat absorption pad - Google Patents

Abstract

The present invention relates to a method for manufacturing a heat dissipation device comprising a heat absorption pad. According to the present invention, a method of manufacturing a heat dissipation device comprising a heat absorbing pad includes a step of mixing a mixture of liquid silicone rubber and microcapsules; a molding step; a curing step; and a sealing step. Accordingly, the heat dissipation efficiency and durability of an electronic device such as an SSD can be improved.

Description

Method of manufacturing a heat dissipation device comprising a heat absorption pad

The present invention relates to a method for manufacturing a heat dissipation device having a heat absorbing pad, and more particularly, to a thermal shock comprising mixing, molding, curing and sealing a mixture of liquid silicone rubber and microcapsules. It relates to a method of manufacturing a heat dissipation device that provides reliability, high temperature reliability and heat dissipation characteristics.

In general, a solid state drive (SSD) is a disk using a semiconductor, and by using flash memory or DRAM as a storage medium, it can read and write much faster than HDDs that are physically driven and used. The trend of users is spreading rapidly.

A solid state drive (SSD) includes a printed circuit board (PCB), a host interface connector connected to the PCB, a flash memory mounted on the PCB, a controller (DRIVE IC chip), and the like. In the SSD, a semiconductor chip such as flash memory or DRAM is mounted on a PCB and embedded in a housing (case) for SSD.

SDD generates a significant amount of heat from the semiconductor chip during operation. As the chip's density (capacity) increases, the heat generated from the chip also increases. do. To prevent this, the HDD or SSD removes heat through a thermally conductive pad, heat sink, or cooling fan.

Korean Patent Application Laid-Open No. 10-2014-0004864 discloses a heat dissipation case having a heat dissipation metal plate 32 formed of a thermally conductive metal to dissipate heat generated by an SSD and a dissipation hole 33 through which heat is dissipated (FIG. 1). Reference). As shown in FIG. 1 , when heat is removed through a thermally conductive metal, heat must inevitably be radiated to the outside of the case, so that the temperature of the case rises, or the heated air is discharged through the outlet, so that heat can be transferred to the human body. For this reason, in the case of electronic products that touch the consumer's body, there is a temperature limit on the contact part (40℃ temperature limit to prevent burns), so there is a limit that the heat of the chip cannot be transferred much to the case (as a result, there is a limit on the amount of heat dissipation) It was difficult to increase the efficiency (data transfer speed) of the device).

The present invention is to provide a heat dissipation system that can significantly lower the temperature rise of the case compared to the conventional method by preventing the heat from being transferred to the outside of the case.

An object of the present invention is to provide a heat dissipation device and method capable of increasing heat dissipation efficiency and durability of electronic devices such as SSDs.

the present invention

A mixing step of mixing the liquid silicone rubber, the phase change microcapsule and the curing agent;

Forming the blended mixture with a roll to roll device to prepare a heat absorbing pad (pad);

curing the heat absorbing pad by applying heat;

It relates to a method for manufacturing a heat absorbing and dissipating device comprising the step of enclosing and sealing the cured heat absorbing pad with a capping film.

The heat dissipation device of the present invention and its manufacturing method use a silicon pad having a phase-change microcapsule dispersed and fixed therein to sufficiently absorb heat generated from a semiconductor chip through a phase-change material and transfer the heat to the electronic device housing (case). can be prevented from being As a result, the heat dissipation device and manufacturing method of the present invention increase the transmission speed or capacity of electronic devices (external storage devices, etc.) without significantly increasing the temperature of the housing compared to the existing thermally conductive pad or metal, thereby contributing to product performance improvement. can

In addition, since the heat dissipation device and method of the present invention do not use a thermally conductive metal or filler therein, it is 2.5 to 3 times lighter in weight (under the same volume condition) compared to the existing thermally conductive pad, thereby increasing the commercial value of electronic devices.

In addition, the conventional thermal conductive pad is stretched using a rubber material, so there was a difficulty in assembly. It can be manufactured in any size and does not stretch when used, increasing assembly and durability.

In addition, when repeated thermal shock is applied to the heat-absorbing pad in which the phase-change microcapsules are dispersed, the microcapsules are destroyed over time so that the internal phase-change material may flow out of the silicone binder, but the heat dissipation device of the present invention The method may provide a capping film sealing the heat-absorbing pad to prevent leakage of the phase change material and increase durability of the heat-absorbing pad.

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

Hereinafter, embodiments and examples of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily carry out the present invention.

The terminology used herein is used only to describe specific embodiments, and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate that a feature, number, step, operation, element, or combination thereof described in the specification exists, but is one or more other features or It should be understood that the possibility of the presence or addition of numbers, steps, acts, elements, or combinations thereof is not precluded in advance.

2 is a schematic diagram of an SSD in which the heat dissipation device of the present invention is installed, FIG. 3 is a cross-sectional view of the heat dissipation device of the present invention, FIG. 4 is an assembly view of sealing the heat absorbing pad with a capping film, and FIG. 5 is a heat dissipation characteristic test It is a schematic diagram of the device.

2 and 3 , the heat dissipation device of the present invention includes a heat absorption pad 10 and a capping film 20 . The method for manufacturing a heat absorbing and dissipating device of the present invention includes molding and curing a heat absorbing pad, and sealing the cured heat absorbing pad with a capping film. More specifically, the method for manufacturing a heat absorbing and dissipating device of the present invention includes a mixing step, a pad manufacturing step, a curing step, and a sealing step.

First, 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 a phase change microcapsule 12 dispersed in the silicone binder. The silicone binder 11 may be formed by curing a liquid silicone rubber to be described later.

The mixing step is a step of mixing the liquid silicone rubber, microcapsules and curing agent.

The phase change microcapsule 12 may include 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 polymer polymer surrounding the core.

As the phase change microcapsule, a known product may be used. For example, shell-forming polymers include polyhydroxyalkonates, polyamides, polyamines, polyimides, polyacrylics (such as polyacrylamide, polyacrylonitrile and esters of methacrylic acid and acrylic acid); Polycarbonates (such as polybisphenol A carbonate and polypropylene carbonate), polydiene (such as polybutadiene, polyisoprene and polynorbornene), polyepoxides, polyesters (such as 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 (such as urea-formaldehyde, melamine-formaldehyde and phenol) formaldehyde), natural polymers (such as polysaccharides such as cellulose, chitin, chitosan and starch; lignin; proteins; and waxes), polyolefins (such as polyethylene, polypropylene, polybutylene, polybutene and polyoctene), poly phenylene, silicon-containing polymers (eg polydimethyl siloxane and polycarbomethyl silane), polyurethanes, polyvinyl (eg 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 (eg glyceride oil) base polymers), copolymers (eg, polyethylene-co-vinyl acetate and polyethylene-co-acrylic acid), and mixtures thereof, and the like.

The phase change material is paraffin (N-Paraffin) series, unsaturated fatty acid series (Fatty Acids), polyglycol (Polyglycol) series, alcohol (Alcohol) series, phenol (Phenol) series, aldehyde (Aldehyde) series, ketone (Keton) series, ether series, etc. may be used.

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

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

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 mixing step may be a step of mixing 50 to 130 parts by weight, preferably 100 to 130 parts by weight of the microcapsule, and 1-2 parts by weight of the curing agent, based on 100 parts by weight of the silicone binder. If the microcapsule exceeds 130 parts by weight, there is a problem that the slurry (semi-finished product) cannot be mixed (particle dispersion problem), and if it is less than 50 parts by weight, the heat absorption capacity of the heat absorption pad is deteriorated.

In the mixing step, the silicone binder, the phase change microcapsules and the curing agent may be mixed at 25±10° C. and the stirrer RPM of 7 or less for 4 to 7 hours.

More specifically, in the mixing step, the phase change microcapsules are mixed for a sufficient time (5 to 6 hours) so that there is no agglomerated part in the silicone binder, and then a curing catalyst is put into the blended mixture and vacuum (-700 mm/Hg). In the following) state, it can be further stirred for about 1 hour with a planetary mixer for high viscosity.

In the blending step, when the RPM of the mixer exceeds 7 or the temperature exceeds the above conditions, the impact is continuously applied to the microcapsules, which can be a factor to reduce durability. That is, it may cause cracking or breakage of the capsule during compounding or molding, and further may cause leakage or breakage of the PCM material in the microcapsule during use of the heat absorbing pad.

The heat absorbing pad manufacturing step is a step of molding the blended mixture into a pad shape by molding it with a roll to roll device.

The blended mixture may be introduced into a roll to roll device and molded into a pad having a thickness of 1 to 20 mm, preferably 2 to 20 mm, more preferably 2 to 10 mm. If the thickness (L) is less than 1mm, it is impossible to support a sufficient amount of microcapsules, so there is a limit to being used as a heat dissipation device for electronic devices that are subjected to continuous and repeated thermal shock.

The curing (reaction) step is a step of curing the heat absorbing pad by applying heat. The curing (reaction) step is a reaction in which a temperature of 120±5° C. is applied to the pad for 10 to 20 minutes. When the curing reaction is carried out at 110° C. or lower, the silicone binder is not sufficiently cured, and when the curing reaction is performed at 130° C. or higher, the capsule is broken, and the material in the capsule interferes with the curing of the silicone, resulting in product defects due to partial curing. In addition, due to the high curing temperature, the phase change microcapsule wall may be damaged, resulting in poor thermal shock reliability (85°C to -40°C).

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

The sealing step is a step of enclosing and sealing the cured pad with a capping film. That is, the capping film 20 surrounds and seals the heat absorption pad 10 .

The capping film 20 may have a density of 1.2 g/cm 3 or more, preferably 1.3 g/cm 3 or more. The capping film 20 has a density of 1.2 g/cm 3 or more, so that even when the shell of the phase change microcapsule is broken, it is possible to prevent the internal phase change material from penetrating the capping film and leaking to the electronic device side. When the density of the capping film 20 is less than 1.2 g/cm 3 , the leaked phase change material may slowly pass through the film and flow out.

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

4 is an assembly view of coupling the capping film 20 to the heat absorption pad 10 . Referring to FIG. 4 , capping films 20a and 20b are respectively positioned on the upper and lower sides of the heat absorbing pad 10 , and the capping films 20a and 20b may be heat-sealed with an adhesive film 3 (thermosetting hot melt film).

The thickness (S) of the capping film may be 10 ~ 350㎛, preferably 50 ~ 100㎛. When the thickness of the capping film is less than 50 μm, the film may be severely deformed during thermocompression bonding, and thermal shock reliability may be deteriorated.

As described above, the capping film may prevent the phase change material from leaking out and increase the assembly and durability of the heat absorption pad.

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

Silicone Binder (WACKER sil-gel 650) 48g, phase change capsule powder (Insilico P-Thermoball 45BN, refer to Table 1 below) 52g, hardener (HANS CHEMICAL CL200) 0.1g, mixed using a planetary mixer for high viscosity proceeded. At the time of mixing, the temperature was maintained at 25° C. using a cooler, and the RPM was carried out so that the maximum did not exceed 7 (stirring at rpm 6).

After mixing (about 5 to 6 hours) for a sufficient time so that the phase change capsule powder (PCM Capsule powder) does not have agglomerated parts, 0.2 g of curing catalyst (DY SILICONE PTC310) is added and vacuum (-700mm/Hg or less) for 1 hr. It was further stirred using a planetary mixer for high viscosity.

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

The prepared heat-absorbing pad was cut to 50 mm in width and 30 mm in length, wrapped with a 0.1 mm thick PET film (XP35, Toray), and then adhered with a hot melt film (INH-5050PH, Instek) (see FIG. 4 ).

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

Comparative Example 1

A heat-absorbing pad was prepared 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 substances in capsules Microtek 43D 15 to 30um 60~100nm Paraffin Wax

Comparative Example 2

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

Comparative Example 3

A heat absorption pad was prepared in the same manner as in Example 1, except that the mixer RPM was stirred for about 15 and 2 hours among the mixing conditions.

Comparative Example 4

A heat-absorbing pad was prepared in the same manner as in Example 1 except for curing (the molded pad) at a temperature of 150° C. for about 5 minutes.

Comparative Example 5

The heat-absorbing 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 a PE film.

Comparative Example 7

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

Comparative Example 8

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

[exam]

Example 1 and Comparative Examples 1 to 8 were tested for compounding properties, moldability, thermal shock reliability, high temperature reliability and heat dissipation properties, 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 - The capsule wall is thin and the size of the capsule is large, so after the thermal shock test, the capsule is destroyed and paraffin leaks inside the encapsulated PET film. (It exists as a liquid at high temperature and becomes very hard at room temperature) Comparative Example 2 O X X O - Mixing is not done because the amount of capsule powder is too large. Comparative Example 3 O X X O - When mixing, the RPM is too high and the capsule is destroyed by physical force, and the paraffin inside the capsule leaks to the outside. Pad is not molded because it exists as a liquid at high temperature after spillage. Comparative Example 4 O O X O - During molding, the curing temperature was too high, and the capsule wall was broken a lot, 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, resulting in poor appearance. Comparative Example 6 O O X O - After a little paraffin leaks, it passes through a relatively low density PE film in a gaseous state and leaks to the outside of the film and causes 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, so Fail.

Formability conditions: Whether the mixture is molded into a pad after curing reaction and drying Thermal shock reliability conditions: Keep the manufactured heat-absorbing pad at 20°C for 10 minutes → Raise the temperature to 60°C for 10 minutes → Maintain at 60°C for 10 minutes → Cool to 20°C for 10 minutes → Repeated 1,000 cycles of holding at 0°C for 10 minutes (1 cycle).

High-temperature reliability conditions: Expose the manufactured heat-absorbing pad at 150°C for 1,000 hours

In addition, the heat dissipation characteristic was measured as follows.

Measurement conditions (25°C condition temperature) - Refer to the heat dissipation characteristic test apparatus in FIG. 5

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

(2) After the heating element was completely cooled, the sample was put in and the PC plate was set so that it completely touches the upper part of the sample.

(3) The temperature of T1 and T2 was measured 15 minutes after the heating element was powered on.

* T1 is less than 55℃, T2 is less than 40℃.

So far, specific embodiments of the present invention have been described. Those of ordinary skill 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 the essential characteristics. The scope of the present invention is indicated in the claims rather than the foregoing description, and all differences within the scope equivalent thereto should be construed as being included in the present invention.

Claims (8)

A mixing step of mixing the liquid silicone rubber, the phase change microcapsule and the curing agent;
Forming the blended mixture with a roll to roll device to prepare a heat absorbing pad (pad);
curing the heat absorbing pad by applying heat;
enclosing and sealing the cured heat-absorbing pad with a capping film,
The mixing step is a step of mixing with 50 to 130 parts by weight of a phase change microcapsule, 1 - 2 parts by weight of a curing agent compared to 100 parts by weight of the liquid silicone rubber,
The heat absorption pad manufacturing step is a step of forming a thickness of 1 to 20 mm,
The capping film has a density of 1.2 g/cm 3 or more, and a thickness of 50 to 350 μm,
The capping film has a lower elongation than the liquid silicone rubber,
The capping film is a method of manufacturing a heat absorption and heat dissipation device, characterized in that even when the shell of the phase change microcapsule is broken, the phase change material inside the capping film is passed through the capping film to prevent leakage to the electronic device side. delete According to claim 1, wherein the phase change microcapsule contains a phase change material having a melting point in the range of 40 ~ 50 ℃,
A method for manufacturing a heat absorbing and dissipating device, characterized in that the phase change microcapsule has a heat capacity of 180J/g or more and a size of 5 to 25 μm. The method of claim 1, wherein the mixing step is a step of mixing the RPM of the stirrer at 7 or less for 4 to 7 hours. delete The method of claim 1, wherein the curing reaction step has a temperature of 120±5° C. and a curing time of 10 to 20 minutes. delete The method of claim 1, wherein the capping film is made of polyethylene terephthalate (PET) or polyimide.

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