KR20200025674A - A low dielectric constant polyimide film using nanosilicate particles and a method of manufacturing the same - Google Patents

Abstract

A low dielectric constant polyimide film using nano silicate particles and a method of manufacturing the same are disclosed. The method for preparing a polyimide film may include preparing a solution in which silica nanoparticles are dispersed through a sol-gel process, and a second solution containing polyamic acid (PAA) in which the silica nanoparticles are dispersed. Mixing with a solution, wherein the solution in the preparing step comprises silica nanoparticles of a predetermined size according to the process control by temperature and time.

Description

LOW DIELECTRIC CONSTANT POLYIMIDE FILM USING NANOSILICATE PARTICLES AND A METHOD OF MANUFACTURING THE SAME

An embodiment of the present invention relates to a method for producing a polyimide film, and more particularly, to a low dielectric constant polyimide film using nano silicate particles and a method for producing the same.

Polyimide (PI) is a polymer material with excellent thermal stability based on a rigid aromatic backbone. Based on the chemical stability of imide rings, it has excellent mechanical and insoluble properties, very high heat resistance, thermal oxidation resistance, heat resistance and radiation resistance. It has excellent properties such as low temperature, low temperature, chemical resistance, etc., and is developed as heat-resistant high-tech materials such as automotive materials, aviation materials, and spacecraft materials, electronic materials and packaging materials such as insulation coatings, insulating films, semiconductors, and TFT-LCD electrode protective films. It is used.

Meanwhile, the polyimide film used as an electronic material or a packaging material for securing a large amount of information and processing the obtained information at high speed and delivering the processed information at high speed in accordance with the electric vehicle and autonomous driving of automobiles is lower. Permittivity is required. In particular, electronic materials requiring high frequency characteristics require high density wiring and excellent moldability, processability, and ease of processing.

In addition, since the speed and accuracy of electrical signals are important according to the complex of electronic devices, noise occurs and accuracy is lowered when impedances between circuits do not coincide with each other. Impedance is closely related to the line width of the circuit, the thickness of the insulating layer, the top, and the dielectric constant of the material. The dielectric constant of the polyimide film currently used for an electronic component or a packaging component is about 3.5-3.7.

As such, the filming technology of polyimide may be represented by a technique of manufacturing a thin film by combining polytetrafluoroethylene (PTFE: Polytetrafluoroethylene) or a porous filler with a polyimide film having a dielectric constant of 3.5 to 3.7, At present, there is a demand for a composite material having excellent heat dissipation characteristics with low dielectric constant and easy to manufacture in a film form.

Republic of Korea Patent No. 10-1728100 (2017.04.12)

The present invention was derived to meet the requirements beyond the above-described limitations of the prior art, the object of which is to effectively disperse the particles obtained through the sol-gel process in a polyimide precursor with high heat dissipation characteristics It is to provide a method for producing a polyimide composite material having a low dielectric constant characteristics.

Another object of the present invention is to produce a polyimide film having a low dielectric constant for securing a large amount of information, processing the obtained information at high speed, and delivering the processed information at high speed according to an electric vehicle, autonomous driving, etc. To provide a method.

Still another object of the present invention is to provide a polyimide film having excellent thermal conductivity and low dielectric constant required for high performance and high integration of an electronic component, and a method of manufacturing the same.

Method for producing a polyimide film according to an aspect of the present invention for solving the above technical problem, preparing a solution in which silica nanoparticles are dispersed through a sol-gel process, wherein the silica nano The solution in which the particles are dispersed contains silica nanoparticles of a predetermined size according to temperature and time-dependent process control; And mixing the solution in which the silica nanoparticles are dispersed into a second solution containing poly amic acid (PAA).

In one embodiment, the preparing of the solution may include mixing distilled water and alcohol in a ratio of 4: 1; Making the solution obtained in the mixing step into a solution having a hydrogen ion concentration (pH) of 2.0 or less; And adding tetraethyl orthosilicate (TEOS) or a metal silane-based material to the solution having a hydrogen ion concentration (pH).

In one embodiment, the preparing of the solution, after adding the tetraethyl orthosilicate (TEOS) to the solution having a hydrogen ion concentration (pH) at room temperature to 50 ℃ temperature atmosphere, the tetraethyl Mixing a solution added with tetraethyl orthosilicate (TEOS) for several minutes to 60 minutes; And gelling and aging the mixed solution for several minutes to 60 minutes.

In an embodiment, the mixing of the second solution may include preparing a second solution in which dimethyl formamide (DMF) or dimethyl acetamide (N, N-dimethyl acetamide, DMAC) is mixed with the polyamic acid. step; Adding a solution containing the silica nanoparticles to the second solution; Mixing the mixed solution of the second solution and the solution containing the silica nanoparticles at a room temperature atmosphere with a mixer having a rotation speed of 1500 to 2500 rpm for 2 to 4 minutes; And removing bubbles generated in the mixed solution.

In one embodiment, the method for producing a polyimide film may further include casting the mixed solution in which the bubble is removed. The casting may include: first curing the mixed solution at a temperature of 100 ° C. for 20 minutes; And second curing the composite material obtained through the first curing at 400 ° C. for 20 minutes.

Polyimide film according to another aspect of the present invention for solving the above technical problem is produced by any one of the manufacturing method of the polyimide film of the above-described embodiments.

In one embodiment, the polyimide film, silica nanoparticles, poly amic acid (poly amic acid, PAA) and dimethylformamide (dimethylformamide, DMF), or silica nanoparticles, poly amic acid (PAA) And dimethyl acetamide (N, N-dimethyl acetamide, DMAC), wherein the dielectric constant of the polyimide film is less than 3.0 in a room temperature atmosphere and a measurement frequency of 300 MHz to 10 Hz.

In one embodiment, the thickness of the polyimide film may be 7.5㎛ to 125㎛.

In the case of using the low dielectric constant polyimide film using the nanosilicate particles of the present invention and a method for producing the same, the structure in which the nanoparticles (or fillers) are hardly exposed to the film surface and well impregnated into the film (particle arrangement of fillers) Structure) to effectively implement the properties of the low dielectric constant with high heat dissipation in the polyimide composite material and the polyimide film prepared using the same.

In addition, according to the present invention, a polyimide film and a method of manufacturing the same are useful for securing a large amount of information according to the length of an automobile, autonomous driving, etc., processing such information at high speed, and delivering the processed information at high speed. Can provide.

In addition, according to the present invention, it is possible to provide a polyimide composite material having excellent thermal conductivity and low dielectric constant required for high performance and high integration of an electronic component, and a method for manufacturing the same. Since the flow can be effectively performed, there is an advantage of minimizing the loss in the power signal or the power transmission.

In addition, the present invention is useful for products such as flexible printed circuit boards (FPCBs), flat wire harnesses, and the like used in automotive electronics, autonomous driving, high performance and highly integrated electronic components, and are suitable for room temperature atmosphere and measurement frequency. It is possible to provide a high heat-resistant and high heat-resistant polyimide composite material having a dielectric constant of 3.0 or less in the range of 300 MHz to 10 Hz and a method of manufacturing the same. If the dielectric constant is 3.0 or less, relatively high performance can be exhibited in the electronic component and the packaging component compared to the case where the dielectric constant is greater than three.

1 is a flowchart illustrating a method of manufacturing a polyimide (PI) film according to an embodiment of the present invention.
FIG. 2 is a flow chart illustrating a first step process that may be employed in some processes of the method of FIG. 1.
FIG. 3 is a flow chart illustrating a second step process that the method of FIG. 1 may employ for the remaining processes.
FIG. 4 is a photograph of a polyimide composite material and a solution in which silica nanoparticles are prepared by the method of FIG. 1.
5 is a scanning electron microscope (SEM) photograph showing enlarged polyimide films prepared according to Comparative Examples and Examples in three steps, respectively.

Specific features and advantages of the present invention will become more apparent from the following detailed description set forth with reference to the accompanying drawings. In the following description, the terms and words used are in accordance with the spirit and concept of the present invention based on the principle that the inventor can appropriately define the concept of terms in order to explain the invention in the best way. To be interpreted.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “characterize”, “comprise” or “having” are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described on the specification, It is to be understood that it does not exclude in advance the possibility of the presence or addition of one or more other features or numbers, steps, operations, components, components or combinations thereof.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention. In describing the present invention, descriptions of functions or configurations already known may be omitted to clarify the gist of the present invention.

1 is a flowchart illustrating a method of manufacturing a polyimide (PI) film according to an embodiment of the present invention.

Referring to FIG. 1, the method of manufacturing a polyimide film according to the present embodiment includes a process of preparing silica nanoparticles using a sol-gel process. In the sol-gel process, the size of particles may be changed according to the reaction temperature and reaction time of the solution. In this embodiment, the hydrogen ion concentration (pH) is 2.0 or less, and preferably the hydrogen ion concentration. (pH) A sol-gel reaction is performed in a temperature atmosphere of 0.5 to 2.0, and room temperature to 50 ° C. Silica has very low solubility at a hydrogen ion concentration (pH) of 2.0 or less.

The use of the above defined conditions in the aforementioned sol-gel process can have a good effect on the surface smoothness of the film depending on its content in the mixed structure of silica ceramics for thermal conductivity and dielectric constant. That is, when manufacturing the composite film using the silica nanoparticles prepared by the sol-gel process described above, it is possible to minimize the exposure of the silica nanoparticles, which is a kind of inorganic filler, to the surface of the film. . This is because particle size and orientation are controlled by temperature and time conditions in the sol-gel process.

In more detail, first, a silica alkoxide and water are mixed, and a solvent and an acid are added to prepare a solution in which nanoparticles are dispersed (S10). At this time, the hydrogen ion concentration (pH), the reaction temperature and the reaction time of the mixed solution are controlled to adjust the size and orientation of the silica nanoparticles (corresponding to the following 'first step process').

Next, a solution containing silica nanoparticles is added to the polyamic acid solution and synthesized in the polyamic acid state. That is, the polyimide is produced by thermal imidation or chemical imidization (corresponding to the 'second step process' below).

Specifically, in the second step process, first, a solution in which the nanoparticles are dispersed in a polyamic acid (PAA) solution (S20) prepared in advance is hydrolyzed and mixed (S21). Next, a mixed solution in which silica nanoparticles are added to a polyamic acid (PAA) solution is dried in a temperature atmosphere of 80 to 100 ° C. to produce a sol or gel composite material (S24). Next, the composite material is cured in a 100 ~ 400 ℃ temperature atmosphere to prepare a polyimide hybrid film (S26).

Table 1 shows the components and contents of the silica solution obtained using the sol-gel process described above.

Kinds Molecular Weight Confiscation Molar ratio (R) TEOS 208.3 0.086 One EtOH 46.07 0.086 One H ₂ O 18 0.360 4 CH ₃ COOH 60.05 - - HCl 36.5 - -

In the sol-gel process, the sol is composed of particles of about 1 nm to 1000 nm and is colloid dispersed without causing precipitation due to van der Waals attraction or surface charge. This sol is transferred to the gel through solvent removal and filmed through heat treatment and aging.

Variables of the sol-gel process in this embodiment are the ratio of water and alkoxide, the hydrogen ion concentration (pH) of the solution, and the nature and concentration of the catalyst. That is, nanosized silica particles can be synthesized from tetraethyl orthosilicate (TEOS) and silica alkoxide in a water solution using a predetermined catalyst.

The first scheme of the sol-gel process using tetraethyl orthosilicate (TEOS) is represented by the following Chemical Formula 1.

In the present embodiment, the reaction proceeds even when the molar ratio (R) is less than 4 with H ₂ O present in the condensation reaction of water in the sol-gel process. As the amount of H ₂ O increases, the alkoxide concentration is diluted to slow the gel formation time, so it is preferable to proceed with the theoretical 1: 4 molar ratio.

In other words, if the gel formation time of tetraethyl orthosilicate (TEOS) becomes longer, the subsequent hydrolysis rate is lowered, and the reaction time is adjusted in consideration of this point in setting conditions.

Silica alkoxide is weakly hydrophobic and does not mix well with water, so ethanol can be used as a co-solvent, and the lower the co-solvent ratio, the less the gel time, so that the concentration can be adjusted by adding anhydrous ethanol.

In addition, since the reaction and particle size change depending on the pH of the solution (pH), it is preferable to proceed with the hydrogen ion concentration (pH) 2.0 or less, and hydrochloric acid (HCl) ) And ethanol (CH ₃ COOH) may be added.

On the other hand, according to the implementation, since the chlorine (Cl) component may cause corrosion in electronic components, an acid catalyst selected from various acid catalysts such as acetic acid may be used as a material for adjusting the hydrogen ion concentration (pH).

Acid catalysts that can be employed in this embodiment include solid acid catalysts, inorganic acid catalysts, zeolites or zeolites in acid form, heteropolyacids, HF, H ₂ SO ₄ , H ₃ PO ₄ , carrier-mounted H ₂ PO ₄ , SiO ₂ -Al ₂ At least one or more selected from O ₃ and the like may be used alone or in combination.

According to the above embodiment, a solution in which silica nanoparticles are dispersed is prepared, and the prepared solution is added to a second solution containing poly amic acid (PAA), wherein the pH of the solution in the above processes, By controlling the reaction temperature and time it is possible to produce a polyimide composite material in which silica nanoparticles are well dispersed. By using such a polyimide composite material, it is possible to produce a polyimide film having excellent dielectric constant and low dielectric constant.

FIG. 2 is a flow chart illustrating a process of a first step that may be employed in some processes of the method of FIG. 1.

Referring to FIG. 2, a first step process (hereinafter, simply referred to as a 'first step') that may be employed in the method for manufacturing a polyimide film according to the present embodiment may prepare silica nanoparticles having a desired size and orientation. As a step, the step of mixing distilled water and alcohol in a ratio of 4: 1 (S11), making a mixed solution into a solution of hydrogen ion concentration (pH) 2 or less (S12), and the hydrogen ion concentration (pH Adding tetraethyl orthosilicate (TEOS) or a metalsilane-based material to the solution having (S13).

In the adding step (S13), tetraethyl orthosilicate (TEOS) may be added in a dropwise addition method to adjust the content or turbidity of tetraethyl orthosilicate (TEOS) in the reactants. . The amount of tetraethyl orthosilicate (TEOS) added may be about four times the content of distilled water. In addition, the adding step (S13) may be implemented to add tetraethyl orthosilicate (TEOS) in a temperature atmosphere in the range of room temperature to about 50 ℃ to a solution having a predetermined hydrogen ion concentration (pH). .

In addition, the first step, after the addition step (S13), may further comprise the step of mixing the reactants (reactants) by stirring for about 20 minutes at room temperature to about 50 ℃ temperature atmosphere (S14).

In addition, in the first step, the colloidal silica (collaidal SiO ₂ ) generated in the step (S14) is mixed with the reactants by further stirring for several minutes to about 60 minutes in a temperature atmosphere of the room temperature to about 50 ℃ range Step S15 may be further included.

In addition, the first step, the step of gelling (aging) the gel solution of the sol state produced in the step (S15) by stirring for a few minutes to 60 minutes at room temperature to about 50 ℃ temperature atmosphere It may further include (S16).

As such, according to this embodiment, a solution in which nanosilicate particles having a desired size and orientation exist by controlling the reaction temperature and reaction time of a silica solution to which tetraethyl orthosilicate (TEOS) is added is prepared. It can manufacture.

FIG. 3 is a flow chart illustrating a second step process that may be employed in the remaining steps of the method of FIG. 1.

Referring to FIG. 3, the second step process (hereinafter, also simply referred to as 'second step') that may be employed in the method for producing a polyimide film according to the present embodiment may include polyamic acid (PAA) or varnish dimethyl formamide. preparing a second solution (polyamic acid solution) in which (dimethylformamide, DMF) or dimethyl acetamide (N, N-dimethyl acetamide, DMAC) is mixed (S20), and silica in which silica nanoparticles are present in the second solution. Adding a solution (silica solution) includes a step (S21). The content of the silica solution added in the step of adding (S21) is more than 0% ~ 90% or less.

In addition, the second step, mixing the mixture solution of the second solution and the silica solution at high temperature for 2 minutes to 4 minutes in a room temperature atmosphere, for example by stirring with a mixer at a rotational speed of 1500 to 2500rpm (high speed mixture, S22) It includes more.

In addition, the second step further includes a step (defoaming, S23) of preparing a composite material by removing bubbles generated in the mixed solution by stirring in a room temperature atmosphere.

In addition, the second step may further include the steps (S25 and S26) of manufacturing a film by casting a polyamic acid (PAA) / silica composite obtained through the bubble removing process.

In addition, the second step may further include the step of drying the colloidal silica in a temperature atmosphere of 80 ° C to l00 ° C to form a composite material before the step of manufacturing the film through casting (see S24 of Figure 1).

In addition, the casting may include the step of first curing the composite material in a temperature atmosphere of about 100 ° C. for 20 minutes to remove the solvent (S26a), and the composite material from which the solvent has been removed from the first curing. The second step of curing in a temperature atmosphere of about 400 ℃ 20 minutes to prepare a polyimide film containing silica nanoparticles (S26b).

Polyamic acid (PPA), dimethyl formamide (DMF) and silica solution in the embodiments (Samples 1, 2 and 3) for the method for producing a polyimide film using the aforementioned sol-gel process (silica solution) The content of each is shown in Table 2 below.

Kinds Sample 1 Sample 2 Sample 3 PPA 15 15 15 DMF 7.5 7.5 7.5 Silica solution 7.5 12.5 15.0

FIG. 4 is a photograph of a polyimide composite material and a solution in which silica nanoparticles are prepared by the method of FIG. 1.

Figure 4 (a) is a photograph of the before volatilization (left) and after volatilization (right) of the solvent in the solution in which the silica nanoparticles are dispersed. And (b) of Figure 4 is a photograph of the before (left), after the first curing (middle) and after the second curing (right) of the polyimide composite material.

Before curing the polyimide film, the composite material is removed before the solvent is removed. After the first curing of the polyimide film, the composite material from which the solvent is removed through the first curing is removed. After the second curing of the polyimide film, the solvent is removed. Each of the composites obtained by performing secondary curing on the composites is shown.

5 is a scanning electron microscope (SEM) photograph showing the morphology of the polyimide film prepared according to the comparative example and the present example.

(A) of FIG. 5 shows the polyimide film of a comparative example, and FIG. 5 (b) shows this Example.

5 (b) shows that the silica nanoparticles in the polyimide film of this embodiment are well dispersed in the polyimide so that they do not protrude on the polyimide surface, and the surface of the polyimide surface and the silica nanoparticles is almost flat. Forming.

On the other hand, in the polyimide film of the comparative example of FIG.

As described above, the polyimide film according to the present embodiment has excellent interfacial properties in which the silica nanoparticles synthesized in the polyimide are clearly contrasted with the comparative examples, thereby having high thermal conductivity and low dielectric constant. That is, the present invention can provide a polyimide composite material having a low dielectric constant while increasing thermal conductivity.

For reference, in the case of the existing technology, considering the composite material to increase the thermal conductivity and lower the dielectric constant is bound to increase the use and content of the composite filler. In particular, according to the content of the inorganic filler in the mixed structure of the silica ceramics, the surface smoothness of the film is affected, and the thermal conductivity increases with the increase of the dielectric constant, and the dielectric constant decreases with the decrease of the thermal conductivity.

On the other hand, according to this embodiment, the inorganic on the polyimide film prepared by controlling the size and orientation of the nano-silicate particles, which is a kind of inorganic filler, by controlling the temperature and time-specific process conditions in the sol-gel process It is possible to minimize the surface exposure of the filler, thereby effectively providing a polyimide composite material or a polyimide film having a low dielectric constant while increasing thermal conductivity.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (7)

Preparing a solution in which silica nanoparticles are dispersed through a sol-gel process, wherein the solution contains silica nanoparticles having a predetermined size according to process control by temperature and time; And
Mixing the solution in which the silica nanoparticles are dispersed into a second solution containing poly amic acid (PAA);
Method for producing a polyimide film comprising a. The method according to claim 1,
The preparing step,
Mixing distilled water and alcohol in a ratio of 4: 1;
Making the solution obtained in the mixing at the above ratio a solution having a hydrogen ion concentration (pH) of 2.0 or less; And
Method of producing a polyimide film comprising the step of adding tetraethyl orthosilicate (TEOS) or a metal silane-based material to the solution having a hydrogen ion concentration (pH). The method according to claim 2,
The preparing step, after the adding step,
Mixing the tetraethyl orthosilicate (TEOS) -added solution for several minutes to 60 minutes; And
Method for producing a polyimide film further comprising the step of aging the solution obtained in the mixing step for several minutes to 60 minutes. The method according to claim 1,
The mixing step,
Preparing a second solution in which dimethylformamide (DMF) or dimethyl acetamide (N, N-dimethyl acetamide, DMAC) is mixed with the polyamic acid;
Adding a solution containing the silica nanoparticles to the second solution;
Stirring and mixing the mixed solution of the second solution and the solution containing the silica nanoparticles in a room temperature atmosphere; And
Removing bubbles generated in the mixed solution;
Method for producing a polyimide film comprising a. The method according to claim 4,
Casting the mixed solution in which the bubble is removed;
The casting step,
Primary curing the mixed solution at a temperature of 100 ° C. for 20 minutes; And
Method for producing a polyimide film comprising the step of secondary curing the mixture produced in the first curing 20 minutes at 400 ℃. The polyimide film manufactured by the manufacturing method of the polyimide film in any one of Claims 1-5. The method according to claim 6,
The polyimide film may include silica nanoparticles, poly amic acid (PAA) and dimethylformamide (DMF), or silica nanoparticles, poly amic acid (PAA) and dimethyl acetamide ( N, N-dimethyl acetamide, DMAC), the dielectric constant of the polyimide film is less than 3.0 in a room temperature atmosphere, the measurement frequency 300MHz to 10kHz range.

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