Polyamic acid composition for packaging electronic components and method for packaging electronic components using the same

Abstract

The present invention relates to a polyamic acid composition for packaging electronic components and a method for packaging electronic components using the same. The polyamic acid composition contains a high proportion of a dianhydride-based monomer having a benzophenone structure as a main component, and a diamine-based monomer having a benzene ring as a diamine-based monomer. The polyamic acid composition can improve the thermal expansion coefficient, glass transition temperature, elongation, etc. of a polyimide thin film formed therefrom. When the polyimide thin film is used as a packaging material for inorganic materials such as silicon wafers, it exhibits excellent adhesion to the inorganic material, is easily removed by O2 plasma removal, and leaves significantly less organic residue on the surface of the inorganic material after removal, making it suitable for use as a packaging material for electronic components, etc.

Description

[Technical Field]

[0001] Cross-reference to related applications This application claims the benefit of priority based on Korean Patent Application No. 10-2018-0142507, filed November 19, 2018, and Korean Patent Application No. 10-2019-0062810, filed May 28, 2019, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] Technical Field The present invention relates to a polyamic acid composition for packaging electronic components and a method for packaging electronic components using the same. [Background technology]

[0003] Electronic devices such as MEMS (Micro Electro Mechanical Systems) and organic light-emitting diodes (OLEDs) are composite structures that include electronic components such as semiconductors, diode elements, and substrates, and for their manufacture, the electronic components can be packaged using a temporary adhesive means called a "sacrificial layer."

[0004] In one example, a MEMS may be a structure that assembles minute electronic components such as sensors, diodes, actuators, microfluidics, and RF circuits fabricated on a silicon-based wafer substrate, and may have a portion that is levitated in a manner that allows it to oscillate above the silicon-based wafer substrate, allowing for mechanical movement.

[0005] Here, the sacrificial layer may be adhered onto a silicon-based wafer substrate on which electronic devices are formed during the manufacturing process to package the electronic devices for bulk micromachining, which may form the raised portion or enable integration with IC circuits, and then removed.

[0006] Processes have been developed that use metals, nitrides, oxides, and fluorides as materials for the sacrificial layer, but these materials require physical / chemical vapor deposition to form the sacrificial layer, which makes packaging difficult, and all of these have the problem of being difficult to process at low temperatures.

[0007] For this reason, polyimide-based materials, which can be simply applied and are easy to package, and which are advantageous from the viewpoints of low-temperature processes and silicone alignment processes, specifically polyamic acid solutions, which can be applied to a predetermined thickness within a desired packaging range and, when hardened, can be bonded to inorganic materials in the form of polyimide resin, are emerging as next-generation materials for sacrificial layers.

[0008] However, polyimide-based materials have a relatively higher coefficient of thermal expansion (CTE) than inorganic-based materials, so they can apply thermal stress to silicon-based wafers, which have a relatively lower CTE, during packaging and subsequent processes.

[0009] Specifically, the difference in the thermal expansion coefficient between the polyimide-based material and the silicone-based wafer induces tensile stress in the silicone-based wafer during the heating process in the packaging process, and compressive stress during the cooling process after packaging, which can cause problems such as breakage or destruction of the silicone-based wafer.

[0010] Additionally, multiple membrane materials may be formed on the sacrificial layer, and thermal stress may be induced in the membrane materials due to the large thermal expansion coefficient of polyimide-based materials, which may result in the membrane materials also being damaged or destroyed, as in the case of silicon-based wafers.

[0011] Meanwhile, removal of sacrificial layers made of organic materials such as polyimide resin typically involves oxidizing and decomposing the organic material through etching using O2 plasma, but polyimide resin is not easily decomposed even when etched using O2 plasma due to its inherent excellent chemical resistance, and organic residues from the polyimide resin can remain on electronic components after removal of the sacrificial layer. These organic residues act as foreign matter on inorganic electronic components and can significantly degrade their quality.

[0012] Therefore, there is a need for a new polyimide-based material that can more stably package inorganic materials and minimize the formation of organic residues that act as foreign substances when removed as a sacrificial layer. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] Korean Patent Publication No. 2017-0069942 [Patent Document 2] Korean Patent Publication No. 2017-0051835 Summary of the Invention [Problem to be solved by the invention]

[0014] An object of the present invention is to provide a polyimide-based material that can stably package inorganic materials and minimize the formation of organic residues that act as foreign substances on the surface of inorganic materials when removed after being used as a packaging material, i.e., a sacrificial layer, and a packaging method using the same. [Means for solving the problem]

[0015] Therefore, in order to solve the above problem, In one embodiment, the present invention comprises: It includes a polyamic acid produced by polymerizing a dianhydride monomer and a diamine monomer, The dianhydride monomer contains 60 mol % or more of a dianhydride main component having a benzophenone structure, and When the content of the dianhydride having a benzophenone structure is less than 100 mol %, A polyamic acid composition is provided that further includes a dianhydride subcomponent having one benzene ring.

[0016] In one embodiment, the present invention provides: applying the polyamic acid composition onto an inorganic electronic component; and heat-treating the applied polyamic acid composition at 20°C to 400°C, The polyamic acid composition is formed by a polyimide through ring closure and dehydration of the amic acid groups of the polyamic acid during a heat treatment process; When the heat treatment is completed, the polyimide resin is cured and adhered to the inorganic electronic component. [Effects of the Invention]

[0017] The polyamic acid composition according to the present invention contains a high proportion of a dianhydride main component having a benzophenone structure as a dianhydride-based monomer, and a diamine component having a benzene ring as a diamine-based monomer, and can improve the thermal expansion coefficient, glass transition temperature, elongation, etc. of a polyimide thin film formed therefrom.

[0018] Furthermore, when the polyimide thin film is used as a packaging material for inorganic materials such as silicone wafers, it exhibits excellent adhesive strength to the inorganic materials, can be easily removed by O2 plasma removal, and leaves significantly less organic residue on the surface of the inorganic materials after removal, making it suitable for use as a packaging material for electronic components, etc. [Brief explanation of the drawings]

[0019] [Figure 1]1 is a photograph of the surface of the polyimide resin of Example 1 after an adhesive strength test. [Figure 2] 1 is a photograph of the surface of the polyimide resin of Comparative Example 2 after an adhesive strength test. DETAILED DESCRIPTION OF THE INVENTION

[0020] While the present invention can be modified in various ways and can have various embodiments, specific embodiments are shown by way of example in the drawings and will be described in detail in the detailed description.

[0021] However, it should be understood that this is not intended to limit the invention to any particular embodiment, but rather to include all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

[0022] In the present invention, the terms "comprise" or "have" and the like are intended to specify the presence of features, numbers, steps, operations, components, parts or combinations thereof described in the specification, and should be understood as not precluding the presence or possibility of addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0023] As used herein, "dianhydride" is intended to include precursors or derivatives thereof, which may not technically be dianhydrides, but which nevertheless react with diamines to form polyamic acids, which can be further converted to polyimides.

[0024] As used herein, "diamine" is intended to include precursors or derivatives thereof, which may not technically be diamines, but which nevertheless react with dianhydrides to form polyamic acids, which can be further converted to polyimides.

[0025] When an amount, concentration, or other value or parameter is given herein as a range, a preferred range, or a list of upper and lower preferred values, it should be understood to specifically disclose all ranges that may be formed by any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether the range is otherwise disclosed. When a range of numerical values ​​is recited herein, unless otherwise stated, in the absence of limiting terms such as greater than, less than, etc., the range is intended to include the endpoints, and all integers and fractions within the range. It is not intended that the scope of the invention be limited to the specific values ​​recited when defining a range.

[0026] The present invention will now be described in more detail.

[0027] Polyamic acid composition In one embodiment, the present invention comprises: It includes a polyamic acid produced by polymerizing a dianhydride monomer and a diamine monomer, The dianhydride monomer contains 60 mol % or more of a dianhydride main component having a benzophenone structure, and When the content of the dianhydride having a benzophenone structure is less than 100 mol %, the polyamic acid composition further contains a dianhydride subcomponent having one benzene ring.

[0028] The polyamic acid composition according to the present invention includes a polyamic acid prepared by polymerizing a dianhydride-based monomer and a diamine-based monomer, and the dianhydride-based monomer may contain a significant proportion of a dianhydride-based component having a benzophenone structure.

[0029] The polyamic acid composition of the present invention contains a dianhydride main component having a benzophenone structure. The benzophenone structure may be present within the polyamic acid polymer chain. The benzophenone structure may also be present within the polyimide polymer chain converted from the polyamic acid polymer chain. The benzophenone structure present in the polyimide polymer chain contains a carbonyl group (C=O) connecting a pair of benzene rings, which can be easily oxidized and decomposed by O2 plasma. Polyimides containing such benzophenone structures may (i) increase the frequency of low-molecular-weight organic substances during O2 plasma treatment, and (ii) result in a decrease in the frequency of low-molecular-weight polymers. Furthermore, (iii) even if crosslinked low-molecular-weight polymers are inevitably present, the benzophenone structure present within these polymers allows for easy oxidative decomposition, inducing a virtuous cycle of generating even more low-molecular-weight organic substances, thereby significantly reducing the rate of organic residues remaining after O2 plasma treatment.

[0030] For example, when the polyamic acid composition of the present invention is applied to an inorganic material to form a polyimide thin film, and then the thin film is removed, the concentration of organic residue remaining on the surface of the inorganic material is low, and the concentration of organic residue generated by the following test method (a) may be 1,000 ppm or less, specifically, 10 ppm to 900 ppm, 10 ppm to 800 ppm, 100 ppm to 500 ppm, or 400 ppm to 750 ppm:

[0031] - Test method (a): A polyamic acid composition was applied to a silicon wafer measuring 1 cm wide x 1 cm long, and heat-treated to form a polyimide thin film having a thickness of 12 μm to 15 μm. The formed polyimide thin film was then treated with O2 plasma at 75 Watts and 150 mT for 1 minute, and the concentration of organic residues originating from the polyimide thin film on the silicon wafer was measured. The concentration of organic residues refers to the weight of the organic residues after O2 plasma treatment relative to the total weight of the polyimide thin film before O2 plasma treatment.

[0032] The polyamic acid composition of the present invention contains a significantly lower concentration of organic residues than ordinary polyimide-based materials, as described above, and therefore can prevent side reactions during processing and deterioration of the insulating properties of inorganic materials due to high concentrations of organic residues.

[0033] In addition, the dianhydride-based component has a benzophenone structure and can induce interaction with hydrophilic groups present on the surface of an object to be bonded, for example, an inorganic material such as a silicone wafer, thereby improving the adhesive strength between the polyimide resin and the inorganic material.

[0034] Polyimide-based materials typically have high adhesive strength among polymeric materials, making them difficult to adhere. While there are various reasons for this, a major one is the formation of a weak boundary layer (WBL) at the contact interface with the adherend when a polyamic acid composition is applied to an adherend, such as a silicone substrate. The weak boundary layer can take various forms, including a lifted state where at least a portion of the cured polyimide resin at the contact interface no longer supports the adherend. This lifted state can occur, for example, due to weak attractive forces acting at the interface between the polyimide resin and the adherend, or due to moisture and / or organic solvents volatilizing during the conversion of the polyamic acid composition to polyimide resin.

[0035] However, the polyamic acid composition according to the present invention contains a substantial proportion of a dianhydride main component having a benzophenone structure, which may be advantageous in facilitating the volatilization of water and / or organic solvents at the initial stage of conversion from the polyamic acid composition to a polyimide resin, thereby preventing the formed polyimide resin from lifting off the object to be bonded.

[0036] For example, when a polyimide resin obtained by curing the polyamic acid composition is subjected to a cross-cut adhesion test according to ASTM D3359, the area of ​​the polyimide resin removed by peeling from an inorganic material may be less than 16% of the total area, specifically 15% or less, 10% or less, or 5% or less. In some cases, the area of ​​the polyimide resin removed without peeling may be 0% of the total area.

[0037] In this case, the content of the dianhydride-based monomer in the polyamic acid composition may be 60 mol% or more, specifically 60 mol% to 100 mol%, 65 mol% to 90 mol%, 65 mol% to 80 mol%, or 75 mol% to 90 mol%, and in some cases, the dianhydride-based monomer may be 100 mol%. By adjusting the content of the dianhydride-based monomer within this range, the present invention can significantly reduce the concentration of organic residues on the surface after removal of the polyimide thin film.

[0038] The dianhydride main component may be a dianhydride having a benzophenone structure, such as 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA). 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) has a benzophenone structure, which not only reduces the concentration of organic residues after O2 plasma treatment but also has a flexible molecular structure, which can advantageously help polyimide resins prepared from the polyamic acid composition to have an elongation of 9% or more, specifically, 9% to 15% or 9% to 13.5%.

[0039] In addition, when the content of the dianhydride main component in the polyamic acid composition of the present invention is less than 100 mol %, the polyamic acid composition may further contain a dianhydride subcomponent having one benzene ring.

[0040] For example, the dianhydride monomer may contain 60 mol % or more and less than 100 mol % of a dianhydride main component having a benzophenone structure, and more than 0 mol % and less than 40 mol % of a dianhydride subcomponent.

[0041] The benzophenone structure contained in the dianhydride-based component of the present invention can be a relatively flexible monomer from the viewpoint of molecular structure because a pair of benzene rings can be bent relative to the carbonyl group. Flexible monomers can increase the thermal expansion coefficient of polyimide resins derived from polyamic acid compositions. In this case, since the thermal expansion coefficient of inorganic materials such as silicone is generally low, at 9 ppm / °C or less, it may be undesirable for polyimide resins to be bonded to inorganic materials to have a high thermal expansion coefficient.

[0042] However, the polyamic acid composition of the present invention contains a dianhydride subcomponent having one benzene ring, which can reduce the thermal expansion coefficient of the polyimide resin formed from the composition. The dianhydride subcomponent has one benzene ring between two anhydride groups, and the polymer derived from this has a rigid molecular structure in which the main chain is difficult to bend. In this case, the polymer forms a rigid, not flexible, structure from the perspective of molecular structure, which can reduce the thermal expansion coefficient.

[0043] For this reason, the dianhydride minor component may be any dianhydride minor component having a structure in which one benzene ring is present between two anhydride groups. For example, the dianhydride minor component may be pyromellitic dianhydride (PMDA). The pyromellitic dianhydride may be combined with a dianhydride major component having a benzophenone structure to provide a polyimide resin prepared from the polyamic acid composition with an appropriate thermal expansion coefficient, specifically, a thermal expansion coefficient of 9 ppm / °C or less, which is a level with a small deviation from the thermal expansion coefficient of inorganic materials, specifically, 1 ppm / °C to 9 ppm / °C, 5 ppm / °C to 9 ppm / °C, or 7 ppm / °C to 9 ppm / °C.

[0044] In addition, the polyamic acid composition of the present invention includes a diamine monomer, and the diamine monomer may contain a diamine component having one benzene ring in a content of more than 50 mol%, specifically more than 60 mol% or more than 70 mol%, based on the total number of moles, and in some cases, may contain 100 mol% to constitute the entire diamine monomer.

[0045] The diamine component, like the dianhydride subcomponent, contains one benzene ring between two amine groups, allowing polymers derived therefrom to have a rigid molecular structure with a main chain that is less prone to bending. The dianhydride subcomponent exhibits a synergistic effect with the diamine component having one benzene ring, allowing polyimide resins prepared from the polyamic acid composition to exhibit an excellent glass transition temperature. For example, the glass transition temperature of the polyimide resin may be 420°C or higher, specifically 430°C or higher, or 440°C or higher, 420°C to 450°C, or 425°C to 445°C.

[0046] Furthermore, this can advantageously act to exhibit a tensile strength, which is a mechanical property necessarily required of the polyimide resin, of 300 MPa or more, specifically 310 MPa or more, 300 MPa to 350 MPa, 305 MPa to 345 MPa, 310 MPa to 335 MPa, 320 MPa to 350 MPa, or 330 MPa to 345 MPa.

[0047] The diamine component may include one or more selected from 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene, and 3,5-diaminobenzoic acid. Among these, 1,4-diaminobenzene is preferred as the diamine component having one benzene ring, as it is advantageous in improving tensile strength and can advantageously act to induce a desirable level of thermal expansion coefficient when combined with the pyromellitic dianhydride.

[0048] Furthermore, the polyamic acid composition of the present invention may further contain an additive including at least one selected from acetic anhydride (AA), propionic anhydride, lactic anhydride, quinoline, isoquinoline, β-picoline (BP), and pyridine. When the polyamic acid composition is converted into a polyimide resin after film formation, such an additive may promote a ring-closure reaction through a dehydrating effect on the polyamic acid, thereby helping to obtain the desired polyimide resin.

[0049] The additive may be contained in an amount of 0.01 to 10 moles per mole of amic acid groups in the polyamic acid, specifically, 0.05 to 1 mole, 0.05 to 0.5 moles, or 0.05 to 0.1 moles per mole of amic acid groups.

[0050] By controlling the content of the additive within the above range, the present invention can sufficiently promote the ring-closure reaction at an appropriate rate through the dehydration action on the polyamic acid, and can prevent the generation of cracks or a decrease in strength of the converted polyimide due to a small amount of additive, while preventing the difficulty in forming a thin film or the damage of the converted polyimide due to an excessive amount of additive.

[0051] The polyamic acid composition of the present invention may further contain a filler for the purpose of improving various properties of the polyimide resin, such as slidability, thermal conductivity, and loop hardness.

[0052] Examples of the filler include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, and mica.

[0053] The average particle size of the filler can be determined depending on the properties of the polyimide resin to be modified and the type of filler to be added. In one example, the average particle size of the filler can be 0.05 μm to 100 μm, specifically 0.1 μm to 75 μm, 0.1 μm to 50 μm, or 0.1 μm to 25 μm.

[0054] The amount of the filler added may be 0.01 to 100 parts by weight, specifically 0.01 to 90 parts by weight, or 0.02 to 80 parts by weight, relative to 100 parts by weight of the polyamic acid composition.

[0055] By adjusting the average particle size and amount of the filler within the above ranges, the present invention can fully realize the polyimide modification effect of the filler and prevent the filler from damaging the surface properties of the polyimide or reducing its mechanical properties.

[0056] In addition, the polyamic acid composition of the present invention may further include an organic solvent in which the polyamic acid composition can be dissolved. In this case, the organic solvent may be an aprotic polar solvent.

[0057] Examples of such aprotic polar solvents include amide solvents such as N,N'-dimethylformamide (DMF) and N,N'-dimethylacetamide (DMAc), phenol solvents such as p-chlorophenol and o-chlorophenol, N-methyl-pyrrolidone (NMP), gamma-butyrolactone (GBL), and diglyme, which may be used alone or in combination of two or more.

[0058] In some cases, auxiliary solvents such as toluene, tetrahydrofuran, acetone, methyl ethyl ketone, methanol, ethanol, water, etc. may be used to adjust the solubility of the polyamic acid.

[0059] As an example, the polyamic acid composition of the present invention can contain N-methyl-pyrrolidone, N,N'-dimethylformamide, and N,N'-dimethylacetamide as organic solvents.

[0060] Furthermore, the polyamic acid composition containing such an organic solvent may have a viscosity of 2,000 cP to 5,000 cP, specifically 2,500 cP to 4,000 cP, 2,500 cP to 3,500 cP, or 3,000 cP to 3,500 cP, measured at 23°C. The viscosity may be measured using a Brookfield viscometer with an RV-7 spindle at a temperature of 23°C and a rotation speed of 0.5 rpm. In the present invention, the polyamic acid composition may have a solids content within the range of 5 to 30%, 10 to 25%, or 12 to 20%.

[0061] By controlling the viscosity of the polyamic acid composition within the above range, the present invention can prevent clogging of the dispenser nozzle by the polyamic acid composition during the coating process, and can appropriately control the fluidity of the polyamic acid composition, making it possible to easily control the shape and thickness of the coated composition. Furthermore, it can prevent a decrease in the adhesive strength of the polyimide resin due to low viscosity.

[0062] Generally, the polyamic acid composition can be produced by the following method: (1) A method in which the entire amount of diamine monomers is placed in an organic solvent, and then a dianhydride monomer is added in an amount substantially equimolar to the diamine monomers to polymerize them; (2) A method in which the entire amount of the dianhydride monomer is placed in an organic solvent, and then a diamine monomer is added in an amount substantially equimolar to the dianhydride monomer to polymerize it; (3) A method in which a part of the diamine monomer components is placed in an organic solvent, and then a part of the dianhydride monomer components is mixed in a ratio of about 95 mol % to 105 mol % relative to the reaction components, and the remaining diamine monomer components are added, and then the remaining dianhydride monomer components are added successively to polymerize the diamine monomer and the dianhydride monomer in substantially equimolar amounts; (4) A method of polymerizing a dianhydride monomer in an organic solvent, mixing a portion of a diamine compound with the reaction components in a ratio of 95 mol% to 105 mol%, and then adding other dianhydride monomer components and subsequently adding the remaining diamine monomer components so that the diamine monomer and the dianhydride monomer are substantially equimolar; and (5) A method of forming a first polymer by reacting some diamine monomer components and some dianhydride monomer components in an organic solvent so that one of them is in excess, and then forming a second polymer by reacting some diamine monomer components and some dianhydride monomer components in another organic solvent so that one of them is in excess, and then mixing the first and second polymers to complete the polymerization. In this case, if the diamine monomer component is in excess when forming the first polymer, the dianhydride monomer component is in excess in the second polymer, and if the dianhydride monomer component is in excess in the first polymer, the diamine monomer component is in excess in the second polymer, and then mixing the first and second polymers to polymerize the diamine monomer components and dianhydride monomer components used in these reactions in a substantially equimolar amount.

[0063] The above methods are merely examples to aid in the practice of the present invention, and the scope of the present invention is not limited to these methods. It goes without saying that any known method can be used.

[0064] Packaging method using polyamic acid In one embodiment, the present invention provides a method for packaging inorganic electronic components, such as silicon wafers, using the polyamic acid composition described above.

[0065] Specifically, the packaging method includes: Applying a polyamic acid composition according to the present invention onto an inorganic electronic component; and heat-treating the applied polyamic acid composition at 20°C to 400°C, The polyamic acid composition is formed by a polyimide through ring closure and dehydration of the amic acid groups of the polyamic acid during a heat treatment process; When the heat treatment is completed, the polyimide resin is cured and adhered to the inorganic electronic component.

[0066] The packaging method according to the present invention can be carried out by applying the above-described polyamic acid composition onto an inorganic electronic component and then heat-treating the applied composition to harden it into a polyimide thin film.

[0067] In this case, the average thickness of the cured polyimide thin film may be 0.5 μm to 15 μm, specifically 2 μm to 14 μm, or 2 μm to 5 μm. The polyamic acid composition may be applied to the inorganic electronic component so that the average thickness of the polyimide thin film falls within the above range. Specifically, the average thickness of the polyamic acid composition applied to the inorganic electronic component may be 1 μm to 30 μm, specifically 2 μm to 15 μm, or 2 μm to 5 μm.

[0068] The step of heat-treating the polyamic acid composition is a step of inducing the dianhydride monomer and the diamine monomer present in the composition to form polyimide chains by reacting them while heating the applied polyamic acid composition at a variable or constant heating rate, and may include a first heat-treatment step of heat-treating at 20°C to 200°C and a second heat-treatment step of heat-treating at 200°C to 400°C, and the first and second heat-treatment steps may be performed continuously or discontinuously.

[0069] In this case, the first heat treatment step may be performed by raising the temperature to an appropriate temperature and then leaving the heated temperature for a predetermined time, and the predetermined time may be, for example, 25 to 45 minutes, and more specifically, 25 to 35 minutes.

[0070] The second heat treatment step is a step of inducing the formation of further polymer chains by reacting substantially all of the dianhydride-based monomers and diamine-based monomers that have not reacted in the first heat treatment step at a temperature of 200°C to 400°C. The heat treatment temperature may be 250°C to 400°C, 300°C to 400°C, or 320°C to 380°C, and may be performed by increasing the temperature from the treatment temperature of the first heat treatment step to the above temperature range at a variable or constant rate of temperature increase.

[0071] In the present invention, by heat-treating the polyamic acid composition within the above temperature range and allowing it to stand for a predetermined period of time, the dianhydride monomer and diamine monomer in the polyamic acid composition can be converted into a polyimide resin having an appropriate molecular weight, for example, a weight-average molecular weight of 50,000 g / mole or less, specifically, 50,000 g / mole to 100,000 g / mole. Polyimide resins having such a weight-average molecular weight have a thermal expansion coefficient, glass transition temperature, elongation, and tensile strength suitable for use as packaging materials for inorganic electronic components, exhibit excellent adhesive strength, and are easily removable by O2 plasma.

[0072] Meanwhile, the packaging method using the polyamic acid composition according to the present invention may further include a step of cooling the formed polyimide resin to room temperature (22±3° C.) after the heat treatment step is completed.

[0073] In addition, the present invention may further include a step of removing the polyimide resin from the inorganic electronic component by treating the polyimide resin cooled to room temperature with O2 plasma. In this case, the inorganic electronic component from which the polyimide resin has been removed may have a significantly low concentration of organic substances derived from the polyimide resin remaining on the surface, such as 1,000 ppm or less, specifically 10 ppm to 900 ppm or 10 ppm to 800 ppm. [Example]

[0074] The present invention will be described in more detail below with reference to examples and experimental examples.

[0075] However, the following examples and experimental examples are merely illustrative of the present invention, and the content of the present invention is not limited to the following examples and experimental examples.

[0076] Examples 1 to 6 A dianhydride major component, a dianhydride minor component, a diamine major component, and a diamine minor component were added to a reactor filled with N-methylpyrrolidone (NMP) at 40°C in the molar ratios shown in Table 1 below and stirred for approximately 30 minutes to polymerize polyamic acid. Isoquinoline was then added in an amount of 0.05 to 0.1 moles per mole of amic acid groups, and the mixture was aged at 80°C for approximately 2 hours to produce a polyamic acid composition. The viscosity of the polyamic acid composition is shown in Table 1.

[0077] [Table 1]

[0078] Comparative Examples 1 to 5 The dianhydride major component, dianhydride minor component, diamine major component, and diamine minor component were added to a 40°C reactor filled with N-methylpyrrolidone (NMP) in the molar ratios shown in Table 2 below and stirred for approximately 30 minutes to polymerize polyamic acid. Isoquinoline was then added in an amount of 0.05 to 0.1 moles per mole of amic acid groups, and the mixture was aged at 80°C for approximately 2 hours to produce a polyamic acid composition. The viscosity of the polyamic acid composition is shown in Table 2.

[0079] [Table 2]

[0080] Experimental Example 1 To evaluate the physical properties of polyimide thin films prepared using the polyamic acid compositions according to the present invention, each of the polyamic acid compositions prepared in Examples 1 to 3 and Comparative Examples 1 to 5 was applied to the surface of a stainless steel support and heat-treated at 350°C to form a polyimide thin film (average thickness: 12 to 13 µm) in which the polyamic acid composition was cured. The formed polyimide thin film was then peeled off from the surface of the stainless steel support to obtain a polyimide thin film.

[0081] The following experiments were carried out on each of the obtained polyimide thin films, and the measurement results are shown in Table 3 below:

[0082] A) Evaluation of coefficient of thermal expansion (CTE) Using a TA Thermomechanical Analyzer Q400 model, the polyimide film was cut into a width of 2 mm and a length of 10 mm, and then heated from room temperature to 500°C at a rate of 10°C / min while applying a tension of 0.05 N in a nitrogen atmosphere. Then, the temperature was further cooled at a rate of 10°C / min, and the slope was measured in the 100°C to 350°C range. The CTE was measured in the 100°C to 350°C range.

[0083] B) Evaluation of glass transition temperature (Tg) In addition, the loss modulus and storage modulus of the polyimide thin film were measured using a dynamic mechanical analyzer (DMA), and the glass transition temperature was calculated from the tangent θ calculated from the measurement results.

[0084] C) Evaluation of tensile strength The tensile strength was measured according to KS 6518.

[0085] D) Evaluation of growth rate According to ASTM D1708, the polyimide thin film was fixed to a universal testing machine and stretched at a rate of 1.3 mm / min to measure the elongation of the thin film.

[0086] [Table 3]

[0087] As shown in Table 3, the examples according to the present invention exhibited appropriate thermal expansion coefficients suitable for application to inorganic substrates such as silicone, etc. Furthermore, the examples also satisfied the appropriate levels for glass transition temperature, tensile strength, and elongation intended in the present invention.

[0088] Experimental Example 2 To evaluate the adhesion and desorption performance of the polyimide thin film prepared using the polyamic acid composition according to the present invention, each of the polyamic acid compositions prepared in Examples 1 to 6 and Comparative Examples 1 to 5 was applied to a silicon wafer and heat-treated at 350°C to form a polyimide thin film (average thickness: 12 to 13 μm) in which the polyamic acid composition was cured.

[0089] A) Evaluation of adhesive strength to inorganic materials According to ASTM D3359 B. Cross-cut tape method, a 25mm wide transparent pressure-reducing tape was adhered to the surface of the polyimide resin, and 6 horizontal and 6 vertical lines were cut with 2mm spacing between each line. The transparent pressure-reducing tape was then pulled 180° and removed, and the presence or absence of detachment of the polyimide thin film was checked with the naked eye. The degree of detachment of the polyimide thin film was graded according to the following criteria: 5B: The desorbed area is 0% of the total area of ​​the polyimide thin film. 4B: The desorbed area is less than 5% of the total area of ​​the polyimide thin film; 3B: The desorbed area is 5% or more and less than 15% of the total area of ​​the polyimide thin film; 2B: The desorbed area is 15% or more and less than 35% of the total area of ​​the polyimide thin film; 1B: The desorbed area is 35% or more and less than 65% of the total area of ​​the polyimide thin film; 0B: The desorbed area is 65% or more of the total area of ​​the polyimide thin film.

[0090] B) Evaluation of residue concentration after desorption of polyimide thin film The silicon wafer on which the polyimide thin film was formed was cut into a 1 cm wide x 1 cm long piece, and the weight of the polyimide thin film formed on the surface of the wafer was measured. The polyimide thin film was then treated with 75 Watt, 150 mT O2 plasma for 1 minute to remove the polyimide thin film, and the weight of the organic residue after the O2 plasma treatment was measured to calculate the concentration of the organic residue.

[0091] The measured results are shown in Figures 1 and 2 and Table 4.

[0092] [Table 4]

[0093] As shown in Figures 1 and 2 and Table 4, the examples according to the present invention exhibited excellent adhesion, the polyimide thin film was easily removed using O2 plasma, and the concentration of organic residues after removal was significantly low. Specifically, Figure 1 is a photograph of the surface of the polyimide thin film after an adhesion test was conducted on the polyimide thin film of Example 1. Referring to Figure 1, it can be seen that even when tape was applied to the grid pattern and then peeled off, there was almost no visible area that had been removed due to the release of adhesion.

[0094] On the other hand, FIG. 2 is a photograph of the surface of the polyimide thin film of Comparative Example 1 after the adhesion test, and it can be seen that a considerable portion of the polyimide thin film has been detached.

[0095] Furthermore, referring to Table 4, in Comparative Examples 3 and 5, polyamic acid compositions were prepared from a combination of monomers having relatively rigid molecular structures without using BTDA, a monomer having a benzophenone structure. In Comparative Examples 3 and 5, serious defects such as surface damage occurred after heat treatment, making it impossible to evaluate the physical properties.

[0096] This is because low-viscosity polyamic acid compositions with a viscosity of around 3,000 cP tend to harden rapidly during heat treatment. In this case, the polyamic acid compositions of Comparative Examples 3 and 5 contain polymer chains with rigid structures derived from monomers with rigid molecular structures, which is presumably why cracks were induced during the rapid hardening process.

[0097] It can also be seen that the use of BTDA, a monomer having a benzophenone structure, can be advantageous in converting a low viscosity polyamic acid composition of about 3,000 cP into a polyimide resin.

[0098] In addition, Comparative Example 1 is a case where the main component BTDA was contained in a relatively small amount and PMDA was contained in a relatively excessive amount based on the content range of the present invention, and Comparative Example 2 is a case where BPDA was used instead of BTDA. These Comparative Examples showed poor adhesive strength and high residue concentration compared to the Examples.

[0099] It should also be noted that Comparative Example 2, which did not use any BTDA, showed more negative results in adhesion and residue concentration than Comparative Example 1, which used a relatively small amount of BTDA.

[0100] This suggests that the benzophenone structure of BTDA can improve the adhesion of polyimide resins and is directly related to minimizing the generation of organic residues caused by O2 plasma. However, from the results of Comparative Example 1, it can be seen that the improved adhesion and the concentration of organic residues caused by O2 plasma can only be achieved at the desired levels when BTDA and PMDA are combined within the content range of the present invention.

[0101] Moreover, in Comparative Example 4, a dianhydride monomer in which BTDA and BPDA were combined was used instead of a combination of BTDA and PMDA. Comparative Example 4 showed a significantly higher organic residue concentration than the Examples, suggesting that even if BTDA, a monomer having a benzophenone structure that is representative of the main dianhydride component, is used in a preferred amount, the intended effect of the present invention may not always be achieved.

[0102] Therefore, it is demonstrated that when the content of the dianhydride main component of the present invention is less than 100 mol %, the effects of the present invention can be suitably realized when BTDA, a monomer having a benzophenone structure, and PMDA, which has a rigid molecular structure due to one benzene ring, are combined in an optimal ratio.

Claims

1. applying a polyamic acid composition onto an inorganic electronic component; and heat-treating the applied polyamic acid composition at 20°C to 400°C; The polyamic acid composition is formed by a polyimide through ring closure and dehydration of the amic acid groups of the polyamic acid during a heat treatment process; A packaging method in which, upon completion of the heat treatment, the polyimide resin is cured and adhered to the inorganic electronic component, The polyamic acid composition is It includes a polyamic acid produced by polymerizing a dianhydride monomer and a diamine monomer, The concentration of organic residues produced by the following test method (a) is 1,000 ppm or less; Dianhydride monomers are The dianhydride copolymer comprises 70 mol % or more and less than 100 mol % of a dianhydride major component having a benzophenone structure and more than 0 mol % and 30 mol % or less of a dianhydride minor component having one benzene ring between two anhydride groups, The diamine monomer contains a diamine component having one benzene ring in an amount of more than 70 mol% based on the total number of moles, A polyamic acid composition, wherein the viscosity of the polyamic acid is 2,000 cP to 5,000 cP at 23°C: Test method (a) A polyamic acid composition is applied to a silicon wafer of 1 cm width x 1 cm length, and heat-treated to form a polyimide thin film of 10 μm to 15 μm thickness. The formed polyimide thin film is then treated with 75 Watt, 150 mT O 2 plasma for 1 minute, and the concentration of organic residues originating from the polyimide thin film present on the silicon wafer is measured. A packaging method characterized by:

2. The heat treatment step is A first heat treatment step of heat treating at 20°C to 200°C; A packaging method according to claim 1, further comprising a second heat treatment step of heat treating at 200°C to 400°C.

3. 2. The packaging method of claim 1, further comprising the step of cooling the polyimide resin formed after the second heat treatment to room temperature.

4. After cooling the polyimide resin to room temperature, Polyimide resin ２ 4. The packaging method according to claim 3, further comprising the step of removing the polyimide resin from the inorganic electronic component by treating with plasma.

5. 2. The packaging method of claim 1, wherein the dianhydride base is 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA).

6. 2. The packaging method of claim 1, wherein the dianhydride subcomponent is pyromellitic dianhydride (PMDA).

7. 2. The packaging method according to claim 1, wherein the diamine component having one benzene ring is at least one selected from the group consisting of 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene, and 3,5-diaminobenzoic acid.

8. 2. The packaging method according to claim 1, wherein the diamine component having one benzene ring is 1,4-diaminobenzene (PPD).

9. 2. The packaging method according to claim 1, wherein the polyamic acid composition further comprises an additive comprising at least one selected from acetic anhydride (AA), propionic anhydride, lactic anhydride, quinoline, isoquinoline, β-picoline (BP), and pyridine.

10. 10. The packaging method according to claim 9, wherein the additive is contained in an amount of 0.01 to 10 moles per mole of amic acid groups in the polyamic acid.

11. The polyimide resin produced from the polyamic acid composition is The thermal expansion coefficient is 9 ppm / °C or less, The glass transition temperature is 420°C or higher, 2. The packaging method according to claim 1, wherein the area of ​​the polyimide detached from the inorganic substrate when measuring adhesion strength according to ASTM D3359 is less than 16% of the entire polyimide.

12. 2. The packaging method according to claim 1, wherein the polyimide resin has a tensile strength of 300 MPa or more and an elongation of 9% or more.

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