KR101479484B1 - Thermally conductive and electrically insulate material and preparation method thereof - Google Patents

Abstract

The present invention relates to a water-soluble organic-inorganic composite sol which can be used as a high-thermal-insulating material and a method for producing the same. Inorganic hybrid sol formed by hydrolysis of condensed acidic alumina sol with functional alkylsilane and hydrolysis by condensation, condensation and functional group polymerization, and a small amount of surfactant and organic binder.
The thermal conductivity of the composite sol of the present invention is 0.45 to 0.63 W / mK and the withstand voltage is 5.2 to 6.7 kV / mm, which is 2 to 3 times higher than the thermal conductivity of an epoxy or silicone resin used as a matrix binder of existing heat- high. This composite sol is mixed with inorganic filler and used as a high thermal insulation material. It can be applied to metal printed board (M-PCB), LED, heat sink, thermal gap filler.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat dissipation insulating material used in a semiconductor package.

Due to the high functionality and high integration of electronic circuits, heat dissipation and withstand voltage are required for metal printed circuit boards (MPCB). The insulating layer used in a metal-based copper clad laminate (MCCL), in which an insulating layer is formed on a metal substrate such as aluminum or copper, and a thin copper plate is applied thereon as a circuit, is generally made of a thermosetting epoxy resin A prepreg impregnated with a woven glass fabric has been used for the solution dissolved in a solvent. However, since the heat generated due to the multifunctionality and the high integration of the electronic parts increases, it is necessary to release the heat well to reduce the malfunction caused by the heat, and to improve the stability of the performance and the lifetime of the parts. Good inorganic thermal conductivity in order to improve the heat radiation performance (silica, alumina, carbon, AlN, BN, SiC, Si ₃ N _4, MgO, etc.), the addition of a filler to the epoxy solution and the glass cloth prepreg used as a support leg (woven glass fabric impregnation of the impregnant is not uniformly distributed in the impregnation, and the filler is not uniformly distributed, and it is difficult to handle due to drying after drying . Japanese Patent Publication No. 2006-36916 discloses a method of dispersing 0.1 to 5 탆 spherical silica powder and < 50 nm nanosilica powder in an organic solvent such as epoxy to improve dispersibility by repulsion due to the same zeta potential, Discloses a method of producing an epoxy slurry having a high concentration of a filler, thereby producing a uniform pre-flag with a high filling property. However, the epoxy used here was a liquid epoxy and a small amount of organic solvent was used. U.S. patent no. 2011/0083890 uses solid epoxy instead of liquid epoxy. Discloses a method for producing a highly filled and homogeneous prepreg by increasing the amount of filler by using an epoxy resin and an epoxy slurry in which two kinds of silica of micron size and nano size are dispersed in an organic solvent. Silica has a low thermal conductivity of ~ 2 W / mK, but is higher than 0.1 ~ 0.2 W / mK of matrix epoxy binder. (20 ~ 30 W / mK) with high thermal conductivity to increase the thermal conductivity of epoxy and silicone resin (~ 0.2 W / mK), which is currently used as a base binder, , Boron nitride (~ 200 W / mK) and aluminum nitride (~ 180 W / mK) as fillers. The thermal conductivity of minerals is highly influenced by purity and varies greatly depending on the orientation.

Japanese Patent No. 9137060 and U.S. Patent No. 2006 / 0127686A1 disclose a method for improving the thermal conductivity by filling polyimide with an inorganic material, and U.S. Patent Publication No. 2012/0156459 A1 disclose a method for simply laminating polyimide having different thermal conductivity to obtain excellent withstand voltage. Polyimide has a disadvantage of higher working temperature than epoxy or silicone resin. WO 0143800 discloses a method of forming an MCCL having excellent heat dissipation resistance and withstand voltage resistance by using a ceramic coating layer containing an inorganic filler in an alkylsilane-based inorganic binder together with an epoxy adhesive layer.

Korean Patent Publication No. 2009-0071774 discloses an adhesive in which polyimide is mixed with an epoxy to increase strength and heat resistance. Korean Patent Publication No. 2010-0133665 describes a method of mixing an alkyl silane and a silica slurry as an inorganic binder in a ceramic layer and adding an oxide filler thereto to apply a ceramic layer to an aluminum substrate.

Therefore, it is necessary to develop a binder having thermal conductivity higher than that of epoxy or silicone resin, which is a currently used matrix binder.

The present invention relates to a binder material constituting a heat dissipation / insulation base used for an electronic component package, and has developed a binder material having thermal conductivity higher than the thermal conductivity of a conventional epoxy or silicone resin, By providing high thermal insulation material, it is aimed to improve the lifetime of parts by eliminating the instability of parts caused by heat by rapidly radiating heat generated by high performance of electronic parts and highly integrated circuit.

In order to solve the above-mentioned problem, it is expected that if a binder is made by using an inorganic precursor having a higher thermal conductivity than a polymer or silicon, the thermal conductivity is expected to be high and the sol having a good adhesion can be hardened through a gel state to serve as a binder Based solids and alumina sol were mixed with each other to develop a water-soluble organic-inorganic hybrid sol.

The present invention relates to a process for preparing an acidic water-soluble alumina sol and reacting the sol with an epoxy group such as 3-glycidoxypropyltrimethoxysilane (GPTMS, 3-glycidoxypropyltrimethoxysilane) and an organosilane having an alkoxy group, Hydrolysis and condensation proceeds to form a water-soluble complex sol. The viscosity of this sol varies with the composition ratio and the gelation time differs. Since this complex sol is thixotropy and can form a thick film of several hundreds of micrometers, it can form a high heat dissipation insulating layer by mixing with an inorganic material and form a layer having excellent adhesion to an aluminum substrate, a copper substrate, and a ceramic substrate .

The organic-inorganic hybrid sol of the present invention is a uniform translucent milky water-soluble sol of excellent adhesiveness to glass, metal or alloy and has a thermal conductivity of 0.4 to 0.6 W / mK, which is 0.1 to 0.2 W / mK, it is expected to be used as a base binder of high heat-insulating insulating material, and it is also economical advantageous to use inexpensive alumina without using expensive nitrided boron (BN) having high thermal conductivity as a thermally conductive filler.

Also, since it is a water-soluble complex sol, it is eco-friendly and economical because it does not use an organic solvent.

The present invention will be described in more detail with respect to each component constituting the sol which is synthesized by mixing the water-soluble, thixotropic alumina acidic sol and the alkyl silane {RSi (OR ') ₃ }.

In the present invention, an acidic alumina sol is synthesized. The boehmite {AlO (OH)} powder is dispersed in distilled water. Acetic acid is added to this slurry and stirred. It may also be heated to ~ 60 ° C to promote the reaction. As the reaction progresses, it changes from an opaque slurry to a translucent milky sol. This sol is coated on a glass plate and dried to give a transparent film, which is transparent even at 100 ° C. However, there is no adhesion. In the present invention, boehmite is dispersed in distilled water at 5 to 30 wt%, preferably 10 to 25 wt%. The acid used as the catalyst is nitric acid, acetic acid, hydrochloric acid, formic acid, boric acid, phosphoric acid, citric acid, maleic acid and the like. The mixing ratio of acids is 3 ~ 60 wt% with respect to the amount of boehmite. The viscosity, pH, adhesion, and thixotropy of the alumina sol produced vary depending on the type and amount of acid used.

There are various kinds of alkylsilanes according to functional groups in which polymerization can take place. For example, 3-glycidoxypropyltrimethoxysilane (GPTMS) having an epoxy group and an alkoxy group as a binder is selected and stirred at room temperature with the alumina sol To prepare an organic-inorganic hybrid sol. The mixing ratio of alumina sol to alkylsilane is 0.3 to 5 in molar ratio of alumina to silane. The alkyl silane may be diluted with alcohol and then added with alumina sol. Use alcohol that can easily be mixed with water, such as methanol, ethanol, and isopropyl alcohol.

The functional group R in the alkylsilane {R _x Si (OR ') _4-x , x = 1 to 3} is an alkyl group such as acryloxy, glycidoxy, methacryloxy, aryl, vinyl, carboxy, Amide alkyl and the like, and R 'is methyl, ethyl, isopropyl, 1-propyl, 1-butyl, isobutyl and the like, and R and R' functional groups may be mixed more than one kind. Examples of the compound include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3- Acryloxypropyltriethoxysilane, 3- (meth) acryloxypropyltrimethoxysilane, and 3- (meth) acryloxypropyltriethoxysilane.

(Polyvinyl alcohol (PVA), polymethacrylate (PMMA), polyacrylate (PA), polyacrylate), and the like can be used in the preparation of the composite sol. , Ethylene glycol polymer (PEG, polyethyleneglycol)} can be added in small quantities. The concentration of the synthesized complex sol can be concentrated or it can be diluted with water or alcohol.

In order to measure the thermal conductivity of the organic-inorganic hybrid sol of the present invention, a disk of 35 x 0.6 mm was produced. The complex sol was poured into a mold, gelled at room temperature, dried, dried at 60 DEG C and then dried at 130 DEG C for 2 hours or more to prepare a semi-transparent sample. Density was 1.5 ~ 1.62 g / ㎤, which showed difference in physical properties depending on the composition ratio and manufacturing process. The specimen was cut to 10 x 10 mm and measured by laser flash (LFA) method to obtain a thermal conductivity of 0.45 to 0.63 W / mK. This value is 2 to 3 times higher than that of the conventional epoxy polymer of 0.2 to 0.2 W / mK and 0.2 W / mK of the silicone resin. An attempt to manufacture a base binder on the basis of an inorganic material is a synthesis of an organic- . The dielectric strength of several dried specimens annealed at 130 ℃ for more than 2 hours is 5.3 ~ 6.7 kV / ㎜.

Disk specimens were prepared by adding alumina powders with thermal conductivity of 20 ~ 30 W / mK as inorganic filler to increase the thermal conductivity. The alumina powder was added as a powder or dispersed with a water-soluble slurry. In order to investigate the effect of alumina powders on particle size, powders of average grain size of 0.4 ㎛ and two kinds of powders of 3 ㎛ were used. When the amount of alumina in the composite was ~ 60 wt%, the thermal conductivity of the specimen added with the coarse powder with the average particle size of 3 ㎛ was 2.75 W / mK and the thermal conductivity of the specimen with the average particle size of 0.4 ㎛ was 1.85 W / And 2.33 W / mK, respectively, in the weight ratio of 3: 1 of the coarse powder and the fine powder. This is because when the fine powder is used, the interface increases and the thermal resistance increases. As far as the thickness of the insulating layer permits, the thermal conductivity can be increased by using a thicker powder and mixing with fine powder to increase the packing density.

The higher the amount of alumina filler, the higher the thermal conductivity. When 50 wt% alumina with an average particle size of 3 ㎛ was added, the thermal conductivity of 1.83 W / mK was expected to be improved to 3.45 W / mK when 74 wt% alumina was added.

The composite with 11% boron nitride shows a thermal conductivity of 1.14 W / mK at a density of 1.72 g / ㎤, and ~ 40 wt% is required when using alumina as a filler.

The specimens annealed at 130 ℃ for 2 hours were held at 200 ℃ or 250 ℃ for 10 min. The thermal conductivity did not deteriorate, and the change in density was negligible.

Both the organic-inorganic composite sol and the filler-containing specimen disclosed in the present invention exhibited a pencil strength> 6H after heat treatment at 130 ° C. for 2 hours and showed strong adhesion to glass and aluminum substrates, .

The use of fillers such as boron nitride (BN), graphite, and aluminum nitride (AlN), which have a higher thermal conductivity than alumina, will exhibit higher heat dissipation.

Also, the composite sol or filler-composite sol slurry of the present invention can be used together with glass fiber or glass cloth used as a support.

The composite sol of the present invention can be used not only as an insulation layer material for a metal printed substrate (M-PCB) but also as a support for LED fluorescent material, a sealant, a thermally conductive sheet, a spacer and an adhesive.

The present invention as described above is explained in more detail based on the following examples, but the present invention is not limited thereto.

Preparation Example 1: Preparation of alumina sol

In the alumina sol used in the present invention, 45 g of boehmite powder was added to 240 ml of distilled water with stirring to form a slurry. Then, 15 g of acetic acid was added and stirred at room temperature for 6 hours or more to obtain 15 wt% of translucent alumina The sol is synthesized and the concentration of alumina and the concentration of acid are expressed as 15 / 33Ac. 20 wt% and 30 wt% alumina sol were prepared in a similar manner. When the agitation time is prolonged, or when the acid concentration or the boehmite concentration is increased, gelation is easily occurred, and thixotropy is used.

A translucent alumina sol was coated on the glass substrate to obtain a transparent film, but there was no adhesion after drying.

Example 1.

10.0 g of GPTMS (KBM 403, Shin-Etsu Co., Ltd.) was placed in a beaker, and various alumina sols prepared according to Production Example 1 were added with stirring at room temperature. The semi-transparent organic-inorganic hybrid sol obtained by stirring for 6 hours or longer was coated on a slide glass and dried at room temperature to give a transparent coating film, which was sticky. A small amount of silicone compound (BYK 333) and fluoride compound (FS 3100) was added as a surfactant. The effect of polyvinyl alcohol on thermal conductivity was investigated. The composite sol was poured into a paper cup having a diameter of 35 mm and dried at room temperature and 60 캜 to prepare a disk having a thickness of ~ 600 탆. The disk was cut to a size of 10 x 10 mm and heat treated at 130 ° C for 2 hours or more. The thermal conductivity was measured by a laser flash method (Netzsch LFA 447, Germany). The withstand voltage was measured using an electric strength tester (Tos 5101, Japan Kikusui Co.) Respectively. Density is measured by alkimedes method in water and the results are shown in the table below.

sample Alumina sol Additive (wt%) PVA
(wt%) density
(g / cm3) Thermal conductivity
(W / mK) Withstand voltage
(kV / mm) Concentration / acetic acid
wt% / sheep Amount (ratio)
(g) BKY333 FS3100 One 15/33 29 - - - 1.62 0.631 5.7 2 15/37 29 0.3 - 0.22 1.59 0.582 3

10/50,
15/33

29 (1: 1)
- - - 1.56 0.535 5.3 4 0.36 - - 1.52 0.455 5 - 0.053 - 1.56 0.495 6 0.15 0.026 - 1.55 0.526 7 - 0.03 0.2 1.57 0.498 8 23 (1: 1) - 0.03 0.2 1.51 0.463 6.7 9
15/40 25 0.3 - 0.1 1.57 0.513 5.6 10 25 - 0.025 0.1 1.57 0.511 11 29 0.3 - 0.1 1.60 0.491

An alumina powder having an average particle size of 3 占 퐉 was dispersed in water and dispersed in water to prepare a composite sol of Sample 7 of Example 1, and the 80 wt% slurry was mixed at room temperature at different amounts. A mixed alumina-composite sol slurry was made into a disk by the method described in Example 1, and its density and thermal conductivity were measured and shown in the table below.

sample Filler density
(g / cm3) Thermal conductivity
(W / mK) Kinds wt% One Boron nitride 11.1 1.72 1.14 2 Alumina 15.8 1.84 0.75 3 Alumina 28.4 2.01 0.86 4 Alumina 46.6 2.29 1.33 5 Alumina 50.9 2.37 1.83 6 Alumina 60.3 2.57 2.75 7 Alumina 73.7 2.92 3.45

Similar densities were obtained by mixing similar amounts of alumina powders of different sizes into the composite sol of Sample 1 of Example 1. Alumina powders of average particle size of 3 ㎛ and 0.4 ㎛ powder were prepared by dispersing aqueous slurries of 80 wt% and 75 wt% respectively with dispersant and mixed with composite sol. Mixed sol - alumina The slurry was measured for density and thermal conductivity by the method described in Example 1, and the results are shown in the table below.

Psalter The average particle size of alumina
(탆) density
(g / cm3) Thermal conductivity
(W / mK) One 0.4 2.62 1.85 2 3 2.57 2.75 3 3: 0.4
(3: 1 weight ratio) 2.56 2.33

The composite of the alumina-composite sol of the present invention is heat-treated at 130 DEG C for 2 hours. The composite is heat-treated again at 200 ° C for 10 minutes and at 250 ° C for 10 minutes, and the density and thermal conductivity are measured and shown in the table below.

sample Heat treatment condition Post heat treatment condition density
(g / cm3) Thermal conductivity
(W / mK) One 130 ° C / 2 hours - 2.92 3.45 200 ° C / 10 min 2.88 3.76 2
130 ° C / 2 hours
- 2.55 1.92 200 ° C / 10 min 2.53 1.92 250 ° C / 10 min 2.57 1.91 3 130 ° C / 2 hours - 2.53 1.90 250 ° C / 10 min 2.56 2.03

Claims (14)

Inorganic hybrid sol adhesive obtained by reacting an alkyl silane {RSi (OR ') ₃ } with alumina sol;
I) dispersing boehmite powder in distilled water, adding an acid and stirring to prepare an alumina sol;
II) mixing the alkylsilane and the alumina sol;
III) adding and mixing the surfactant and the organic binder to II);
IV) coating, drying at room temperature, and heat treatment to prepare a thick film.
Wherein R represents an alkyl compound having a functional group capable of undergoing polymerization such as epoxy, vinyl, acryloxy and the like, and R 'represents methyl, ethyl, propyl, isopropyl, 1-propyl, 1-butyl or isobutyl.
The method according to claim 1,
Wherein the alumina sol is prepared by acid hydrolysis and polymerization of a boehmite slurry.
3. The method according to claim 1 or 2,
Wherein said acid comprises nitric acid, acetic acid, hydrochloric acid, phosphoric acid, formic acid and organic acid.
The method according to claim 1,
Wherein the alkylsilane is selected from the group consisting of 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3- (Meth) acryloxypropyltriethoxysilane, 3- (meth) acryloxypropyltrimethoxysilane, and 3- (meth) acryloxypropyltriethoxysilane.
The method of claim 1, wherein
Wherein the alkyl silane can be diluted with 5 to 50 wt% of alcohol.
6. The method of claim 5,
Wherein the alcohol comprises at least one of methanol, ethanol, isopropanol, propanol, butanol, isobutanol, ethylene glycol, and methoxyethanol.
The method according to claim 1 or 2,
Wherein the concentration of the water-soluble alumina sol is 5 to 30 wt% in alumina.
The method according to claim 1,
Wherein the mixing ratio of alumina sol to alkylsilane is in the range of 0.3 to 5 in terms of alumina.
The method according to claim 1,
The additive is a surfactant, and includes at least one of a silicone compound and a fluorine compound.
The method according to claim 1,
The organic binder is a water-soluble binder and comprises at least one of polyvinyl alcohol, acrylic, and polyethylene glycol.
The method of claim 1, wherein
Followed by drying at room temperature followed by heat treatment at 60 to 150 占 폚.
A composite according to claim 1, wherein the inorganic sol is mixed with the composite sol in an amount of 10 to 80 wt% to prepare an inorganic-complex sol slurry and heat-treated.
The composite according to claim 12, wherein the inorganic material is a thermally conductive inorganic material and at least one of alumina, silica, boron nitride, aluminum nitride, carbon, silicon carbide, silicon nitride, magnesium oxide and the like is contained.
The composite according to claim 12, wherein the heat treatment temperature is 60 to 150 占 폚.