KR102209746B1 - Heat Radiation and Adhesive Sheet for LED Package - Google Patents

Abstract

As a multilayer heat dissipation adhesive sheet used in a heat generating element, as a multilayer heat dissipation adhesive sheet used in a heat generating element, it includes a core layer including an acrylic resin and expandable graphite, an acrylic adhesive resin, and an inorganic heat dissipation filler, , It provides a multilayer heat dissipation adhesive sheet comprising two skin layers forming the outermost layer on both sides of the core layer.

Description

Heat Radiation and Adhesive Sheet for LED Package

The present invention is a multilayer heat dissipation adhesive sheet used in a heat generating element, comprising a core layer including an acrylic resin and expandable graphite, an acrylic adhesive resin, and an inorganic heat dissipation filler, and includes an outermost layer on both sides of the core layer. It relates to a multilayer heat-dissipating adhesive sheet comprising two skin layers forming.

With the development of technology, semiconductor chips are miniaturized and highly integrated, and accordingly, high functionality and high capacity of electronic devices are accelerating. High-functionality and high-capacity electronic devices are one product that handles the work that many products had to do in the past, improving work efficiency and space efficiency, while the amount of heat and electromagnetic waves generated when electronic devices are operating is remarkably reduced. With the increase, a problem has arisen that causes malfunction of the electronic device itself, or severely deteriorates or ignites the electronic device itself.

In particular, since the inside of the electronic device contains not only the electronic components that actually operate the product, but also the housing of the electronic product made of a material that is vulnerable to heat, the internal substrate and adhesive, etc., it is necessary to remove the heat generated when the electronic device is operated. It has emerged as a very important problem directly related to the stability of electronic devices.

In general, small electronic products such as miniaturized displays, tablets, portable personal terminals, etc., if the heat generated internally cannot be properly diffused to the outside, screen defects may occur due to excessive accumulated heat, causing system failure and failure. have. The most problematic part in the application of LED, which has become a hot topic in recent years, is that only 15 to 25% of the energy supplied by heat is converted into light and emit light, and the remaining 75 to 85% is consumed as heat. will be. A significant portion of this power is consumed as heat, and the temperature of the LED module rises, affecting the luminous efficiency and the life of the product, and causing problems that lower the overall reliability of the product, such as the durability of the package.

Despite these problems, in the case of LEDs used in electronic products such as displays, tablets, PCs, and lighting, it is impossible to install a heat dissipation fan and a heat sink due to the reduction in the thickness of the module due to the aforementioned miniaturization and integration. Instead, it uses a method of dissipating the heat generated by the LED to the plate using a metal such as aluminum. A heat dissipating member capable of efficient heat transfer between the LED and the aluminum plate is required.

For this, a highly heat-dissipating sheet of about 0.1 to 3.0 W/mK can be used, but in order to strongly bond the LED and the aluminum plate, an additional process of attaching the LED and the aluminum plate with separate bonding, bolts, rivets, etc. The disadvantage is that it is difficult to reinstall or separate after performing the process.

In order to solve this problem, an adhesive heat dissipation sheet is used on the market to allow efficient heat dissipation by transferring heat generated from the LED to the plate while adhering the LED and the aluminum plate.

However, the existing heat dissipation sheet has a high thermal conductivity and does not have strong adhesive strength, and in the case of an adhesive sheet having high thermal conductivity, there is a problem that the adhesive strength is low, resulting in poor workability and product stability problems of electronic devices using the same. , In the case of a heat dissipation sheet with high adhesion, the thermal conductivity decreases and the generated heat is not sufficiently discharged, which may cause malfunction or failure of the electronic device itself.After it has been adhered, it is removed and reattached. There is a problem that it is difficult to further work such as.

On the other hand, high-integration devices may deteriorate as other components or devices themselves in the event of excessive heat generation and cause fire. Usually, adhesive sheets or adhesive tapes are made of polymer materials and are easily deformed or deteriorated by heat. Although a flame-retardant material is used in a device, there is a problem in that it has a function as a basic adhesive sheet, an adhesive tape, or a heat dissipating material, and it is difficult to secure flame retardance, and various attempts for this have been continued.

As mentioned above, with the advancement of technology, electronic devices are gradually becoming more functional and high-capacity, and heat generated by multiple electronic devices is explosively generated in one electronic device. It is necessary to develop a heat-dissipating adhesive sheet having an adhesive strength that can be reworked, such as separating and re-adhering the LED and the heat sink later.

An object of the present invention is to solve the problems of the prior art and technical problems that have been requested from the past.

The present invention relates to a heat-dissipating adhesive sheet used in a highly integrated device having a large amount of heat, such as a high-density device, having excellent heat dissipation properties and adhesive properties, and having flame retardancy and suitable for use in highly integrated devices.

In particular, the present invention provides a multilayer heat-dissipating adhesive sheet having high heat dissipation characteristics, excellent workability, and excellent adhesion of the heat-dissipating adhesive sheet for use in LED devices with a large amount of heat.

Specifically, the multilayer heat dissipation adhesive sheet according to the present invention includes a core layer including an acrylic resin and expandable graphite, an acrylic adhesive resin, and an inorganic heat dissipation filler, and comprises two outermost layers on both sides of the core layer. It includes a skin layer.

The multilayer heat dissipation adhesive sheet according to the present invention may include an expandable graphite having an average particle diameter of 10 to 100 μm (micrometer), and may be included in an amount of 1 to 100 parts by weight based on 100 parts by weight of the acrylic resin of the core layer. .

The inorganic heat dissipating filler of the skin layer constituting the present invention is aluminum hydroxide (Al(OH) ₃ ), aluminum oxide (Al ₂ O ₃ ), aluminum nitride (AlN), boron nitride (BN), beryllium oxide (BeO) ferrite It may be at least one selected from the group consisting of Fe ₂ O ₃ ) and silicon oxide (SiO ₂ ), and may be included in an amount of 10 to 300 parts by weight based on 100 parts by weight of the acrylic adhesive resin of the skin layer.

Specifically, the inorganic heat dissipation filler may include boron nitride (BN) and an aluminum-based filler, and the average particle diameter may be 0.1 to 20 μm (micrometer).

Meanwhile, the multilayer heat dissipation adhesive sheet according to the present invention may further include an additional inorganic heat dissipation filler in the core layer, and the inorganic heat dissipation filler may be an aluminum-based filler.

The core layer may further include a dispersant, and the dispersant may be included in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the acrylic resin.

As described above, the heat dissipation adhesive sheet according to the present invention is suitable for use in high-capacity electronic devices, has high heat dissipation properties particularly suitable for use in LED packaging with a large amount of heat, and at the same time has excellent adhesive properties. .

Since the heat dissipation sheet itself has adhesiveness, after installing the heat dissipation sheet, there is an effect of simplifying the process as additional work by rivets, bolts, etc. for attaching the LED to the heat sink is not required.

1 is a schematic diagram showing the configuration of a heat dissipating adhesive sheet in the present invention;
2 and 3 are images of specimens manufactured according to Experimental Example 1.
4 and 5 are graphs showing the results of measuring adhesion and heat dissipation properties of a specimen prepared according to Experimental Example 1;
6 to 8 are graphs showing the adhesive strength of the specimen prepared according to Experimental Example 2;
9 is an image of a specimen prepared according to Experimental Example 2;
10 is an image showing the experimental results of Experimental Example 3.

Hereinafter, each configuration will be described in more detail, but this is only an example, and the scope of the present invention is not limited by the following content.

The present invention is a heat-dissipating adhesive sheet, which has a characteristic particularly suitable for use in LED packaging with a large amount of heat, and transfers heat generated from the LED to a heat sink to enable efficient heat dissipation, and at the same time, both sides of the heat-radiating sheet are LED It relates to a heat-dissipating adhesive sheet having adhesive properties to adhere to and a heat-dissipating plate.

It has been difficult for the conventional heat-dissipating adhesive sheet to simultaneously satisfy adhesive properties and high heat-dissipating properties. In the case of a heat-dissipating adhesive sheet having high heat dissipation characteristics, as the amount of heat increases, a sweating phenomenon of the adhesive layer occurs, resulting in a problem that the adhesive strength decreases, which causes various problems such as safety or failure of electronic devices. Triggered. On the contrary, in the case of introducing a heat-dissipating adhesive sheet that does not change its physical properties even at high temperatures, heat dissipation is caused by problems such as poor heat dissipation properties, or the sheet layer is denatured, so that the fillers inside the sheet are not evenly distributed and clumped in a specific part of the sheet. There was a problem that it could not function properly as a sheet.

In order to solve this problem, the present invention is a heat-dissipating adhesive sheet used in a heat generating element, comprising: a core layer comprising an acrylic resin and expandable graphite; Two skin layers comprising an acrylic pressure-sensitive adhesive resin and an inorganic heat dissipating filler, and forming an outermost layer on both surfaces of the core layer; It provides a heat-dissipating adhesive sheet having excellent heat dissipation properties and adhesive properties by having a multi-layered structure including.

Moreover, since the core layer contains expandable graphite, it does not burn even when the amount of heat generated is excessive, and thus has particularly excellent flame retardancy.

The core layer constituting the multilayer heat-radiating adhesive sheet of the present invention contains expandable graphite, that is, expanded graphite, as a heat-radiating filler. Expandable graphite is included as a main filler of the core layer and has an effect of improving the heat dissipation characteristics of the core layer, and the flame retardancy of the pressure-sensitive adhesive sheet is also improved by the flame-retardant properties of the expandable graphite itself.

The expandable graphite may have an average particle diameter of 10 to 100 μm (micrometer), preferably 25 to 75 μm (micrometer), most preferably 30 to 70 μm (micrometer).

In the case of having a particle size smaller than the above size, there is a problem in that the photocuring efficiency is lowered in the secondary polymerization process, so that the expandable graphite does not have a level of strength that can be used as a tape or sheet, and the expandable graphite has an effect of blocking UV. Since the UV curing rate using the resin is relatively reduced, it is impossible or difficult to cure the sheet by irradiation with UV. In the case of having a particle size larger than the above size, there is a problem in that the dispersibility of the expandable graphite in the core layer is lowered and the heat dissipation characteristic is reduced.

The expandable graphite may be included in an amount of 1 to 100 parts by weight based on 100 parts by weight of the acrylic resin of the core layer. Preferably, it may be included in 5 to 80 parts by weight, most preferably, 12 to 30 parts by weight.

When added in a small amount than the above content, there is a problem that the heat dissipation property is deteriorated as the thermal conductivity of the expandable graphite decreases, and when it is added in excess than the above content, the curing efficiency for manufacturing the sheet is decreased. It is difficult to manufacture a sheet, and even when a sheet is manufactured, there is a problem that the durability of the finished sheet is deteriorated and the sheet is destroyed.

The multilayer heat dissipation adhesive sheet according to the present invention may further include an additional inorganic heat dissipation filler. Specifically, aluminum hydroxide (Al(OH) ₃ ), aluminum oxide (Al ₂ O ₃ ), aluminum nitride (AlN), boron nitride (BN), beryllium oxide (BeO), ferrite (Fe ₂ O ₃ ), silicon Oxide (SiO ₂ ), carbon nano tube (CNT), carbon black (Carbon Black) and may be one or more selected from the group consisting of graphite, and more specifically, an aluminum-based filler, that is, aluminum hydroxide (Al It may be one or more selected from the group consisting of (OH) ₃ ), aluminum oxide (Al ₂ O ₃ ), and aluminum nitride (AlN).

The additional inorganic heat dissipation filler may be included in an amount of 100 to 400 parts by weight, preferably, 120 to 350 parts by weight, and most preferably 150 to 300 parts by weight, based on 100 parts by weight of the acrylic resin of the core layer.

When added in a smaller amount than the above content, the effect of adding an additional inorganic filler is not great compared to when only the expandable graphite is added, and when it is added in excess than the above content, the content of the filler is excessive, thereby preparing the core layer. It is difficult to do and there is a problem that the dispersibility of the filler is greatly deteriorated.

The additional inorganic heat dissipating filler may have a particle size of 0.5 to 100 µm (micrometer), and preferably, the additional inorganic heat dissipating filler having the particle size is used as a heat dissipating filler having various particle sizes and shapes of different sizes. It is desirable to configure.

For example, a configuration including an additional inorganic heat dissipation filler having a size of 10 μm (micrometer) and an additional inorganic heat radiation filler having a size of 50 μm (micrometer) at the same weight ratio is 10 μm (micrometer). The heat dissipation characteristics can be further improved compared to the case of using only the heat dissipation filler of the size or the case of using only the heat dissipation filler of 50 μm (micrometer).

By including the additional inorganic heat dissipating fillers of different particle sizes as described above, the heat transfer path between the inorganic heat dissipating fillers through which heat is transferred between the heat dissipating fillers in the core layer can be formed densely with a higher density. It can be transferred to the heat sink.

In the case of using a size smaller than the particle size, the dispersibility of the filler is inferior, so the heat dissipation characteristic does not appear uniformly throughout the adhesive sheet, and there is a problem that the quality of the multilayer heat dissipation adhesive sheet is deteriorated, and a size larger than the particle size In the case of using, there is a problem that the filler protrudes to the surface of the core layer, and there is a problem that it is difficult to configure the adhesive sheet as the flexibility of the core layer decreases.

Meanwhile, the core layer according to the present invention includes an acrylic resin, and its type is not particularly limited, and any one having affinity with expandable graphite and additional inorganic heat dissipating fillers is not particularly limited and may be used.

Therefore, the acrylic resin is not particularly limited and can be used as long as it is obtained by polymerizing an acrylic monomer.

For example, an acrylic resin obtained by polymerization of one or more selected from the group consisting of alkyl acrylate, hydroxy acrylate, vinyl acetate and acrylic acid may be used, and in detail, 2-ethylhexyl acrylate (2-Ethylhexyl Acrylate) , 2-hydroxypropyl acrylate (2-Hydroxy Propyl Acrylate), 2-hydroxyethyl acrylate (2-Hyderoxy Ethyl Acrylate), isooctyl acrylate, isobornyl acrylate, methyl acrylate, ethyl acrylate, butyl It may be a polymerized one or more monomers selected from the group consisting of acrylate, vinyl acetate, and acrylic acid.

The alkyl acrylate refers to an acrylate that contains only branched and chain alkyl groups as a substituent and does not contain other substituents such as a hydroxy group or a carboxyl group.

The hydroxy acrylate is used as a generic term for an acrylate containing a hydroxy group, and refers to an acrylate containing a hydroxy group and having additional substituents.

Since the core layer constituting the multilayer heat dissipating adhesive sheet of the present invention includes expandable graphite and may further include an additional inorganic heat dissipation filler, as a large amount of filler is filled in the core layer, the filler of the core layer A dispersant may be further included to improve dispersibility.

The dispersant may be included in an amount of 0.1 to 10 parts by weight, preferably 0.15 to 3 parts by weight, and most preferably 0.2 to 1 part by weight, based on 100 parts by weight of the acrylic resin.

If added in a small amount than the above content, there is a problem that there is no significant difference from the case of not adding because the effect on the dispersibility of the filler is not large, and if it is added in an excessive amount, there is a problem that the physical properties of the core layer are reduced due to side reactions. .

Specifically, the dispersant may be at least one selected from a silane-based dispersant, a siloxane-based dispersant, and an ammonium-based dispersant, and preferably, a mixture of a silane-based dispersant and a siloxane-based dispersant, or a mixture of a silane-based dispersant and an ammonium-based dispersant. Can be configured.

Specifically, the silane-based dispersant is γ-Glycidoxypropyltrimethoxysilane, the siloxane-based dispersant is alkoxysiloxane, and the ammonium-based dispersant is an alkylol ammonium salt (Alkylol Ammonium salt).

The multilayer heat dissipation adhesive sheet according to the present invention further includes two units of skin layers on both sides of the core layer. In the present invention, one core layer and two skin layers are the most basic units constituting the present invention, and are similar in structure to the core layer and further include an additional heat dissipation layer to further improve heat dissipation properties, etc. It may be composed of a multilayer heat-dissipating adhesive sheet in which an additional layer is further inserted.

The core layer is located at the most central layer of the multilayer heat dissipating adhesive sheet according to the present invention, but does not need to be symmetrically positioned on the vertical cross section of the multilayer heat dissipating adhesive sheet. That is, it is possible to configure the two skin layers to form the outermost layer on both sides of the core layer, and to provide an additional layer between the core layer and the skin layer, or to have the two skin layers independently have different thicknesses.

The skin layer serves to connect the heat-generating component and other components to each other when the adhesive sheet of the present invention is applied to the LED packaging.

Accordingly, the skin layer has a configuration including an acrylic adhesive resin and an inorganic heat dissipating filler.

In this way, the skin layer must perform the adhesive function directly, so it is configured to have excellent adhesiveness.Because it is a part that directly contacts the device through which current flows, it contains an acrylic adhesive resin so that it does not have electrical conductivity. As one or more selected from the group consisting of aluminum (Al(OH) ₃ ), aluminum oxide (Al ₂ O ₃ ), aluminum nitride (AlN), and boron nitride (BN), it is configured not to contain a conductive carbon-based filler. . Preferably, it may be configured to include boron nitride (BN) and an aluminum-based filler.

When the boron nitride filler is added to the skin layer, there is an advantage of having a high thermal conductivity compared to the content of the radiating filler compared to the case of adding another inorganic radiating filler.

Specifically, the inorganic heat dissipation filler may be included in an amount of 10 to 200 parts by weight based on 100 parts by weight of an acrylic adhesive resin, preferably 20 to 150 parts by weight, most preferably 30 to 100 parts by weight. .

When added in a small amount than the above content, there is a problem that the heat dissipation property is slightly lowered in the entire heat-dissipating adhesive sheet, and when it is added in excess than the above content, the adhesive strength of the skin layer decreases, and the process of mixing the acrylic resin and the radiating filler Since it is difficult to disperse the filler, it is difficult to manufacture the skin layer itself.

The inorganic heat dissipating filler of the skin layer may have a particle size of 0.1 to 20 μm (micrometer). If the size is larger than the above size, there is a problem that the adhesive strength of the skin layer is lowered, and if it is smaller than the size, there is a problem that the physical properties of the skin layer are deteriorated due to poor dispersibility.

The multilayer heat dissipation adhesive sheet according to the present invention is manufactured as a single adhesive sheet by bonding a plurality of layers, thereby securing high heat dissipation characteristics and flame retardancy by the core layer, and is configured to have excellent adhesive properties by the skin layer.

The acrylic adhesive resin constituting the skin layer can be obtained by polymerizing the monomers described in the acrylic resin of the core layer. The acrylic adhesive resin may be composed of a resin identical to or similar to the acrylic resin of the core layer.

The acrylic adhesive resin constituting the skin layer may be a polymerized monomer selected from the group consisting of alkyl acrylate, hydroxyacrylate, vinyl acetate and acrylic acid, and in detail, 2-ethylhexyl acrylate (2-Ethylhexyl Acrylate) ), 2-hydroxypropyl acrylate (2-Hydroxy Propyl Acrylate), 2-hydroxyethyl acrylate (2-Hyderoxy Ethyl Acrylate), isooctyl acrylate, isobornyl acrylate, methyl acrylate, ethyl acrylate, It may be a polymerized one or more monomers selected from the group consisting of butyl acrylate, vinyl acetate and acrylic acid.

In the multilayer heat dissipating adhesive sheet according to the present invention, the core layer may have a thickness of 100 to 500 μm (micrometer), and the skin layers may each independently have a thickness of 30 to 100 μm (micrometer).

Hereinafter, the present invention will be described in more detail through examples, but the scope of the present invention is not limited thereto.

Experimental Example 1

Based on the contents of Table 1, a core layer was prepared as follows, and a skin layer was prepared based on Table 2.

A core layer including expandable graphite and an additional inorganic heat dissipating filler was prepared in an acrylic resin obtained by polymerizing the monomers of Table 1, and an inorganic heat dissipating filler was added to the acrylic adhesive resin obtained by polymerizing the monomers of Table 2 to prepare a skin layer. I did.

Classification (parts by weight) 1-1 1-2 1-3 1-4 1-5 1-6 1-7 Monomer 2-EHA 100.0 100.0 100.0 100.0 100.0 100.0 100.0 HPA 14.0 14.0 14.0 14.0 14.0 14.0 14.0 Initiator PI-184 0.6 0.6 0.6 0.6 0.6 0.6 0.6 Crosslink HDDA 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Expandable-Graphite 9.0 um 3.0 - - - - - - 12.0 um - 3.0 - - - - - 20.0 um - - 3.0 - - - - 80.0 um - - - 3.0 10.0 15.0 20.0 Al ₂ O ₃ 20.0-50.0 um 120.0 120.0 120.0 120.0 120.0 120.0 120.0 Al(OH) ₃ 1.0-20.0 um 90.0 90.0 90.0 90.0 90.0 90.0 90.0 BN 1.0-5.0 um 10.0 10.0 10.0 10.0 10.0 10.0 10.0

Classification (parts by weight) 1-1 1-2 1-3 1-4 1-5 1-6 1-7 Monomer 2-EHA 100.0 100.0 100.0 100.0 100.0 100.0 100.0 HPA 14.0 14.0 14.0 14.0 14.0 14.0 14.0 Initiator PI-184 0.6 0.6 0.6 0.6 0.6 0.6 0.6 Crosslink HDDA 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Al(OH) ₃ 1.0-10.0 um 30.0 30.0 30.0 30.0 30.0 30.0 30.0 BN 1.0-5.0 um 10.0 10.0 10.0 10.0 10.0 10.0 10.0

An image of the heat dissipating adhesive sheet specimen prepared according to Tables 1 and 2 was taken, and an experiment was conducted to confirm the physical properties of the manufactured specimen except for the case in which the state of the manufactured specimen was defective.

Table 3 shows the adhesive holding power at high temperature and whether or not it is lifted (peeling) for the adhesive sheet obtained by bonding i) the core layer, ii) the skin layer and iii) the core layer and the skin layer prepared based on Tables 1 and 2 above. The experiment, the insulation breakdown confirmation experiment, and the measurement result of flame retardancy are shown, and FIG. 2 shows the surface image of each specimen of the preparation example.

First, in the experiment to measure the holding power at high temperature, after attaching the core layer specimen to the adherend surface, measure the time until the 1 kg weight is dropped by foot, but in this experiment, the adhesion under the temperature condition of 80 ℃. The holding power was measured.

The lifting (peeling) test was conducted to determine whether lifting (peeling) appeared on the attached surface under conditions of a temperature of 60°C and a relative humidity of 90% with one side of each specimen attached to the surface of a stainless steel plate (SUS-304). It is an experiment to confirm.

The insulation breakdown check test is an experiment to check the insulation performance limit of an insulator, and the insulation breakdown check test was conducted under the applied voltage condition of 6.0 kV in the same way as the insulation resistance test standard for industrial electric devices.

The flame retardancy test was measured based on the UL-94 standard (VTM).

evaluation 1-1 1-2 1-3 1-4 1-5 1-6 1-7 Core layer Holding Power
(hr) Measure
Impossible Measure
Impossible Measure
Impossible 24 24 24 16 Exfoliation Measure
Impossible Measure
Impossible Measure
Impossible More than
none More than
none More than
none Out of grade
(NG) Insulation breakdown Measure
Impossible Measure
Impossible Measure
Impossible Sheet
Destruction Sheet
Destruction Sheet
Destruction Sheet
Destruction Flame retardant properties Measure
Impossible Measure
Impossible Measure
Impossible VTM-2 VTM-0 VTM-0 VTM-0 Skin layer Holding Power
(hr) 24 -
Exfoliation More than
none Insulation breakdown More than
none Flame retardant properties Out of grade
(NG) Adhesive sheet
(Core layer+
2 skin layers) Holding Power
(hr) Measure
Impossible Measure
Impossible Measure
Impossible 24 24 24 24 Exfoliation Measure
Impossible Measure
Impossible Measure
Impossible More than
none More than
none More than
none More than
none Insulation breakdown Measure
Impossible Measure
Impossible Measure
Impossible More than
none More than
none More than
none More than
none Flame retardant properties Measure
Impossible Measure
Impossible Measure
Impossible VTM-2 VTM-2 VTM-0 VTM-0

2, when using expandable graphite having small particles having a particle size of 20 μm or less in Preparation Example 1-1 having different particle sizes of the expandable graphite, as the particles block UV, acrylic resin Since it is not cured sufficiently, there is a problem that the core layer is not produced. (Preparation Example 1-1) In the case of Preparation Examples 1-2 and 1-3, it was confirmed that it did not have sufficient adhesiveness as the surface hardening occurred, and when bonding the core layer to the skin layer, it was not completely bonded. There is a problem that it is difficult to manufacture a multilayer heat dissipation adhesive sheet. In comparison, when using the expandable graphite of 80 μm, it was confirmed that the surface was not cured and the adhesive strength was maintained, and it was confirmed that it is preferable to use the expandable graphite having a particle size exceeding 20 μm. .

3 and 4 are graphs showing an image of an adhesive force measurement experiment of the adhesive sheets of Preparation Examples 1-4 to 1-7 and a graph of an adhesive force measurement experiment result.

Referring to FIG. 3, when using expandable graphite of the same particle size, when 20 parts by weight or more of expandable graphite is added as in Preparation Example 1-7, the sheet is destroyed in the process of removing the adhered sheet. As it was confirmed, it was confirmed that it was difficult to attach and detach as an adhesive sheet, and re-work was inferior.

Referring to FIG. 4, there was no significant difference in the adhesive strength of the specimen after the lapse of the initial 30 minutes, but the adhesive strength of the specimen after the lapse of 24 hours was slightly reduced when the content of expandable graphite was added in an amount of 15 parts by weight or more. have. As shown in Table 3, when 20 parts by weight is added, the holding power is reduced to 2/3 level compared to the other preparation examples, and it can be seen that the adhesive strength (retention power, seatability, stability and high temperature stability) is somewhat lowered.

Referring to the results of the insulation breakdown confirmation experiment, it was possible to confirm the lack of insulation resistance in the specimen composed of only the core layer, so that the heat dissipating adhesive sheet according to the present invention can be used in electronic devices such as LED packaging. The surface of the adhesive sheet in direct contact was composed of a skin layer. Accordingly, in the case of a multi-layered adhesive sheet having a reinforced skin layer having insulation resistance, it was found to have insulation stability even under an applied voltage condition of 6.0 kV.

Referring to Table 3, it was confirmed that the skin layer and the pressure-sensitive adhesive sheet (core layer + two skin layers are bonded) can be used without abnormality in the test to confirm whether or not the insulation is broken under the same conditions.

As a result of the flame retardancy measurement experiment, it was confirmed that the core layer including expandable graphite has excellent flame retardancy.

For the specimen, an experiment was further conducted to measure heat dissipation characteristics (thermal conductivity, thermal diffusivity). The experiment was conducted based on the ASTM E 1461 standard, and the experimental results are shown in FIG. 5. When the expandable graphite of the same size is included, if it is included in an amount of 20 parts by weight or more, the thermal conductivity and thermal diffusivity have decreased due to reasons such as a decrease in the density of the core layer and an increase in the depletion layer between the acrylic resin on the interface and the heat dissipation filler. I guess.

Experimental Example 2

With reference to the manufacturing method of Preparation Example 1-6 of Experimental Example 1, a core layer containing the same acrylic resin, expandable graphite, and inorganic heat dissipating filler as the specimen was prepared, but the types and contents of the dispersant according to Table 4 below. Preparation Examples 2-1 to 4-5 of the different core layers were prepared.

The following experiment was performed using the same skin layer as in Preparation Example of Experimental Example 1.

division 2-1 2-2 2-3 2-4 2-5 DOW 6040
(Silane dispersant) - 0.1 0.3 0.5 0.7 division 3-1 3-2 3-3 3-4 3-5 DOW 11-100
(Siloxane-based dispersant) - 0.1 0.3 0.5 0.7 division 4-1 4-2 4-3 4-4 4-5 BYK 180
(Ammonium dispersant) - 0.1 0.3 0.5 0.7

The adhesive strength of the prepared adhesive sheet (core layer + skin layer) was measured and shown in FIGS. 6 to 8 below. In Tables 5 and 6, the test for confirming the adhesive holding power and insulation breakdown at high temperatures for the core layer, skin layer, and adhesive sheet (core layer + skin layer) prepared according to Preparation Examples 2-1 to 4-5, respectively, was measured. The results are shown.

The evaluation of adhesion holding power at high temperature and the test for checking whether insulation breakdown were conducted in the same manner as in Experimental Example 1.

division 2-1 2-2 2-3 2-4 2-5 Manufacturing Example 2 Core layer 24 24 24 24 24 Skin layer 24 24 24 24 24 Adhesive sheet 24 24 24 24 24 division 3-1 3-2 3-3 3-4 3-5 Manufacturing Example 3 Core layer 24 24 24 18 12 Skin layer 24 24 24 24 24 Adhesive sheet 24 24 24 16 11 division 4-1 4-2 4-3 4-4 4-5 Manufacturing Example 4 Core layer 24 24 24 15 9 Skin layer 24 24 24 24 24 Adhesive sheet 24 24 24 13 7

division 2-1 2-2 2-3 2-4 2-5 Manufacturing Example 2 Core layer Fail Fail Fail Fail Fail Skin layer Pass Pass Pass Pass Pass Adhesive sheet Pass Pass Pass Pass Pass division 3-1 3-2 3-3 3-4 3-5 Manufacturing Example 3 Core layer Fail Fail Fail Fail Fail Skin layer Pass Pass Pass Pass Pass Adhesive sheet Pass Pass Pass Pass Pass division 4-1 4-2 4-3 4-4 4-5 Manufacturing Example 4 Core layer Fail Fail Fail Fail Fail Skin layer Pass Pass Pass Pass Pass Adhesive sheet Pass Pass Pass Pass Pass

Referring to Table 5, it was confirmed that when the siloxane-based dispersant and the ammonium-based dispersant were added in an amount of 0.5 parts by weight or more, the adhesive retention at high temperature was somewhat inferior. 9 is a photograph of a specimen after the adhesive retention test at high temperature. As the core layer contains a large amount of dispersant, the physical properties of the core layer are reduced, so that peeling occurs in the core layer, or when the adhesive sheet is removed, the multilayer is separated. It was confirmed that the addition of less than 0.5 parts by weight was preferable, considering the physical properties of the core layer.

Referring to Table 6, irrespective of whether or not a dispersant is applied, a lack of insulation resistance was confirmed in the insulation breakdown test of the core layer added with expandable graphite, but the heat dissipation adhesion of a multilayer structure reinforced with a skin layer having insulation resistance In the case of the sheet, it was found to have insulation stability even under an applied voltage of 6.0 kV.

On the other hand, referring to FIG. 6 below, when a silane-based dispersant is used, the adhesive strength of the core layer is slightly lower, but as can be seen in Table 5, the adhesive holding power at high temperature is on the high side, so the adhesive holding power at high temperature In consideration of, it is judged to be preferable to add a part of the silane-based dispersant in consideration of dispersibility and adhesion retention of the core layer at high temperature.

In the case of adding the siloxane-based dispersant and the ammonium-based dispersant in FIGS. 7 and 8, the adhesive strength is excellent, but as shown in Table 5, the adhesive holding power at high temperature is slightly lower, so considering the initial adhesive strength, the siloxane-based dispersant It can be seen that it is preferable to add a dispersant and an ammonium-based dispersant.

Therefore, according to the above experimental results, it was confirmed that the use of a mixture of a silane-based dispersant and a siloxane-based dispersant or an ammonium-based dispersant is most preferable in consideration of the physical properties of the multilayer heat dissipating adhesive sheet.

Experimental Example 3

With reference to the manufacturing method of Preparation Example 1-6 of Experimental Example 1, a combustion test was performed on the adhesive sheet of Example prepared by preparing a core layer and a skin layer and bonding them.

In the pressure-sensitive adhesive sheet, the same skin layer was used, and the content of expandable graphite was 5 parts by weight, and 10 parts by weight of the pressure-sensitive adhesive sheet of Comparative Example comprising a core layer further containing boron nitride (BN) was prepared. The combustion experiment was conducted.

The combustion test results for the two adhesive sheets are shown in FIG. 10 below.

Referring to FIG. 10 below, when the pressure-sensitive adhesive sheet is burned by a fire, the pressure-sensitive adhesive sheet of the embodiment swells as the expandable graphite expands by the fire, and the fire does not spread.

On the other hand, in the case of the pressure-sensitive adhesive sheet of Comparative Example in which a small amount of expandable graphite and a boron nitride filler were further added, it was confirmed that fire spread despite the expansion of a small amount of expandable graphite by fire.

Therefore, when the adhesive sheet of the embodiment is used in an electronic device, it is not only resistant to heat, but also has the advantage of not suppressing the spread of fire even when a fire occurs, and is suitable for use in an electronic device with a large amount of heat, such as a highly integrated circuit. It is expected that it can be used not only for LED packaging, but also for various electronic devices developed in the future.

Claims (9)

As a multilayer heat dissipation adhesive sheet used for a heat generating element,
A core layer including an acrylic resin, expandable graphite, and an additional inorganic heat dissipating filler; And
Two skin layers comprising an acrylic pressure-sensitive adhesive resin and an inorganic heat dissipating filler and forming an outermost layer on both surfaces of the core layer; Including,
The expandable graphite has an average particle diameter of 80 to 100 μm,
The expandable graphite is included in an amount of 3 to 15 parts by weight based on 100 parts by weight of an acrylic resin in the core layer,
The additional inorganic heat dissipation filler of the core layer is aluminum oxide (Al ₂ O ₃ ) having an average particle diameter of 20 to 50 µm, aluminum hydroxide (Al(OH) ₃ ) having an average particle diameter of 1 to 20 µm, and an average particle diameter of 1 to 5 Including boron nitride (BN) of ㎛,
The inorganic heat dissipation filler of the skin layer is a multilayer heat dissipation adhesive sheet comprising aluminum oxide (Al ₂ O ₃ ) having an average particle diameter of 1 to 10 µm and boron nitride (BN) having an average particle diameter of 1 to 5 µm. delete delete delete The method of claim 1,
The inorganic heat dissipation filler is a multilayer heat dissipation adhesive sheet, characterized in that it is included in an amount of 10 to 300 parts by weight based on 100 parts by weight of the acrylic adhesive resin. delete delete delete The method of claim 1,
The core layer may further include a dispersant,
The dispersant is a multilayer heat-dissipating adhesive sheet, characterized in that contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the acrylic resin.

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