KR20070058736A - Polyimide resin and flexible metal clad laminates - Google Patents

Abstract

Provided is a polyimide resin, which has a heat expansion coefficient similar to that of metal foil, forms a film having excellent adhesion to metal foil, dimensional stability and smoothness, and is useful for flexible printed circuit boards. The polyimide resin is obtained through thermal imidization of a polyamic acid precursor solution prepared by reacting an aromatic diamine with dicarboxylic dianhydride in the presence of a polar aprotic organic solvent. The polyamic acid precursor solution includes a polyamic acid-nanocomposite resin comprising a polyamic acid precursor and demineralized nanoclay. The demineralized nanoclay comprises at least one nanoclay selected from silicate having a thickness of 10-9 to 10-7m and a length of 10-8 to 10-6m, talc and mica, and a C5-C38 alkyl group bound to interstitial volumes thereof.

Description

Polyimide resin and flexible metal clad laminates

The present invention relates to an FCCL having a polyimide resin suitable for FCCL manufacturing use and a polyimide film layer formed therefrom, and more particularly, a polyimide having a coefficient of thermal expansion (CTE) close to the conductive metal foil after curing. A mid resin and FCCL having excellent dimensional stability.

Currently, flexible printed circuit boards (FPCBs) are widely used in consumer applications such as notebook computers, mobile phones, personal digital assistants and digital cameras. Due to the demand for smaller and lighter home appliances, the FPCB industry requires a thinner and lighter adhesive type FCCL than a three-layer type having an existing adhesive layer.

Generally, adhesive-free FCCL is produced by applying PAA to the surface of a copper foil and heat-treating at high temperature to imidize PAA to form a polyimide film. PAAs can be prepared by reacting dicarboxylic dianhydrides and aromatic diamine compounds in polar aprotic solvents.

On the other hand, the continuous process of manufacturing FPCBs involves many transfer carriers, and because they pass through narrow openers or slits, curl is the most important requirement for FCCL processing. It is one of the matters, and there should be no wrinkle before or after etching.

It is well known that the dimensional stability of adhesive-free FCCL is related to the coefficient of thermal expansion (CTE) of polyimide resins (Japanese Patent No. 2746555, Japanese Patent Publication No. 60-157286, Japanese Patent Publication 2003) -80630, Korean Patent Publication No. 2002-0040853). If there is a large CTE difference between the polyimide resin and the metal foil, tension is created in the FCCL, which causes the FCCL to decay and affect the dimensional stability of the FCCL. Therefore, the more similar the CTE of the polyimide resin and the metal foil can improve the dimensional stability of the FCCL.

As an example of the related technology, the technique disclosed in Korean Patent Laid-Open Publication No. 2004-0110065 may be mentioned, wherein an inorganic material such as talc or mica powder is added to a polyamic acid precursor obtained by reacting an aromatic tetracarboxylic dianhydride with an aromatic diamine. The polyimide resin was prepared by including a filler and thermally imidating it, and the obtained polyimide resin is disclosed to have a CTE of 10 to 30 ppm / ° C. Specifically, where the CTE of the polyimide resin is close to the CTE of the copper foil, some useful properties of the polyimide resin will have to be sacrificed, and in limited and substantially large scale production in the selection of dianhydride compounds and diamine compounds. The CTE of polyimide resins is always within a certain range and it is disclosed that the difference in CTE between polyimide resin and copper foil will be within a certain range. As an approach to solve this problem, sufficient inorganic filler was added to the polyamic acid precursor to improve the resistance to the CTE difference between the polyimide film and the copper foil, thereby sufficiently satisfying the CTE difference between the polyimide film and the copper foil. It has a strong resistance.

However, such inorganic fillers have limitations in improving the resistance to CTE differences between polyimide films and copper foils, and the addition of inorganic fillers has difficulties in dispersion due to incompatibility between organic and inorganic materials. The problem of limiting the improvement of dimensional stability was shown.

Accordingly, the present inventors have made diligent efforts to solve the problem of the polyimide resin obtained from the PAA precursor including the PAA and the inorganic filler, and to solve the problem of the FCCL having the polyimide film layer formed therefrom, such as talc and mica. As a result of manufacturing a polyimide nanocomposite type resin using a nanoscale and organicized inorganic filler rather than an inorganic filler, it is easy to control CTE of polyimide resin and improves heat resistance and mechanical properties, and a polyimide film layer formed therefrom In the case of FCCL having a smoothness and dimensional stability was found to be improved to complete the present invention.

An object of the present invention is to provide a polyimide resin having a CTE value similar to that of a metal foil, easy to control CTE, good smoothness, excellent dimensional stability, and excellent heat resistance, mechanical properties, and flame retardancy.

It is also an object of the present invention to provide an FCCL having excellent smoothness and dimensional stability by having a polyimide film layer formed from such a polyimide resin.

It is also an object of the present invention to provide a polyimide resin which is particularly useful in the preparation of adhesive-free FCCL, in which the polyimide resin is obtained after application and curing directly onto the surface of a metal foil without any adhesive layer such as epoxy or acrylic adhesive.

Another object of the present invention is to provide a polyimide resin useful for the production of FCCL having high peel strength, excellent dimensional stability and flatness, and FCCL composed of a polyimide film layer and metal foil obtained by thermosetting the polyimide resin Flexible printed circuit products can be made thinner and reliability can be improved.

The polyimide resin of the present invention for achieving the above object is obtained by thermally imidating a polyamic acid precursor solution obtained by reacting an aromatic diamine and a dicarboxylic dianhydride under a polar aprotic organic solvent, and the polyamic acid precursor solution. Is a polyamic acid-nanocomposite resin comprising a polyamic acid precursor and an organicized nanoclay.

In addition, in the flexible metal foil laminate of the present invention, a polyimide obtained by applying a polyamic acid precursor solution obtained by reacting an aromatic diamine and a dicarboxylic dianhydride under a polar aprotic organic solvent on at least one surface of the metal foil, and then thermally imidizing Having a film layer, the polyamic acid precursor solution is characterized in that the polyamic acid-nanocomposite resin comprising a polyamic acid precursor and an organicized nanoclay.

The present invention will be described in more detail as follows.

The polyimide resin of the present invention is obtained by thermally imidating a polyamic acid precursor solution obtained by reacting a dicarboxylic dianhydride with an aromatic diamine under a polar aprotic organic solvent, wherein the polyamic acid precursor solution is organicized with a polyamic acid precursor. Polyamic acid-nanocomposite comprising nanoclays.

Herein, the organic nanoclay is used to extend the interlayer distance of nano-sized inorganic particles by using an organic agent, and it is called a nanocomposite in which a polymer is inserted into the widened interlayer. Such nanocomposites have been known to improve the poor physical properties of polymers such as gas permeability, flame retardancy, gas and water vapor barrier properties ( Polymer-Clay Nanocomposites , TJ Pinnavaia & W. Beall, John Wilwy & Sons, Ltd.). , New York, 2001, Prog.Polym. Sci .; 2003; 28; 1539). Polymers used in the production of such nanocomposites include polyamides such as nylon 6 and nylon 66, polyester, polypropylene, and polyethylene.

Ultimately, the polyimide resin in the present invention is a polyimide nanocomposite obtained by inserting a PAA precursor between layers of organicized nanoclays and thermal imidization.

In the present invention, the polyimide nanocomposite resin is prepared by thermosetting PAA obtained by reacting a dicarboxylic dianhydride and an aromatic diamine in a polar aprotic solvent, and the PAA solution is prepared in an appropriate amount with various molar ratios of aromatic diamine compounds. Nanoscale Organically Inorganic Fillers. In addition, by changing the molar ratio of the two aromatic diamine compounds it is possible to prepare a polyimide nanocomposite resin having a thermal expansion coefficient of 16 to 38 ppm / ℃.

Specifically, when the manufacturing process of the polyimide resin is examined, the dicarboxylic dianhydride and the aromatic diamine are first reacted under a polar aprotic organic solvent to prepare PAA. As the dicarboxylic anhydride used herein, pyromellitic dianhydride ( PMDA), 4,4'-oxydi (phthalate) (ODPA), 3,4,3 ', 4'-biphenyltetracarboxylic dianhydride (BPDA), 3,4,3', 4'-benzo Phenonetetracarboxylic dianhydride (BTDA) and 3,4,3 ', 4'-diphenylsulfontetracarboxylic dianhydride (DSDA). Preferably they are PMDA and BPDA.

Aromatic diamines include 4,1,3-bis (3-aminophenoxy) benzene (APB), 4,4'-diaminodiphenylether (ODA), p-phenylenediamine (PDA), 4,4 ' -Methylenebisaniline (MDA), 4,4'-aminophenyl sulfone (DDS), 4,4'-diaminobenzaniline (DABA) and 2-methyl-4,4'-diaminobenzaniline (MABA) One or two or more selected mixtures are used, preferably PDA and ODA are used in at least 0.5 to 6.0 molar ratio relative to the dicarboxylic dianhydride. And the molar ratio of total amine to dicarboxylic dianhydride is preferably 0.95 to 1.05.

As the organic solvent used for the PAA polymerization is N, N - dimethylacetamide (DMAc), N, N - dimethylformamide (DMF), N - methyl-2-pyrrolidone alone or in combination of two selected from the money (NMP) The above mixture is used, Preferably, it is DMF or NMP.

In order to prevent a decrease in physical properties in the PAA polymerization, the water content of the organic solvent is preferably 500 ppm or less, and more preferably 100 ppm or less. In addition, the reaction temperature for preparing the PAA is usually carried out at 0 ℃ to 90 ℃ or less, preferably 50 ℃ or less.

The organophilic nanoclay is added to produce the polyimide nanocomposites there is a silicate, montmorillonite, talc, mica, etc. mainly used, in the present invention, thickness of 10 ^-9 m to 10 ^-7 m, length 10 m to 10 ^{-8 - As} having a size of ⁶ m, those having an alkyl group of 5 to 38 carbon atoms are used.

Among them, montmorillonite, a silicate sheet capable of efficient interpenetration with polymers due to thermal stability, molecular barrier properties, high mechanical properties and swelling ability, is used as a nanoclay, and among them, hexadecylamine as an organic agent. It was used to prepare montmorillonite, that is, organic clay (C16-MMT) to which an alkyl group having 16 carbon atoms was bonded by binding to montmorillonite of nanoscale using.

However, organicized nanoclays are not limited to such C16-MMTs.

The content of such organicized nanoclays is 0.01 to 20 parts by weight based on 100 parts by weight of PAA solid content. If the content is more than 20 parts by weight based on 100 parts by weight of PAA solid content, the mechanical properties of polyimide deteriorate and 0.01 If less than the weight part, there is a problem in that smoothness and dimensional stability, which are objects of the present invention, are lowered.

As an example of the method for preparing C16-MMT in the organic nanoclay, first, Na ⁺ -montmorillonite (trade name: Kunipia-F) manufactured by Kunimine having an ion exchange capacity of 119 meq / 100 g (Kunipia-F) was prepared. After adding decylamine, it adds to the hexadecylamine ammonium salt obtained by heating up at 80 degreeC and reacting for about 1 hour. After stirring for 1 hour, the precipitated white powder was collected well, and further stirred for 1 hour in warm water after the filter. Repeat the above steps several times to remove residual ammonium salt, filter and dry to obtain C16-MMT.

The method of dispersing the organicized nanoclay obtained in this manner in a PAA solution may be a known dispersion method, for example, a ball mill, Henschel mixer, homogenizer (Homogenizer Stirrer) Etc. Dispersing the organicized nanoclays in the PAA solution can produce a PAA-nanocomposite resin.

Then, when the obtained PAA-nanocomposite resin is imidated to produce a polyimide nanocomposite, the polyimide resin of the present invention can be obtained, and the imidation method can be adjusted to suit the intended use. For example, a thermosetting method in which the temperature is raised, the solvent is volatilized and dried, and the imidized at the same time, or the PAA dissolved in the organic solvent is precipitated as a non-solvent, followed by imidization in a hot air oven. Drying and aging to obtain the final imide. In the present invention, a thermosetting method was used.

In the present invention, it is also possible to use other additives used in the polymer nanocomposites depending on the intended use. For example, Abrasion resistance improvers, such as a silica powder, molybdenum disulfide, and a fluororesin; Reinforcing agents such as glass fibers; Flame retardant improvers such as antimony trioxide, magnesium carbonate and calcium carbonate; Electrical property enhancers such as clay and mica; Tracking resistance agents such as asbestos and silica; Acid-resistant flavoring agents such as barium sulfate, silica and calcium metasilicate; Thermal conductivity enhancers such as iron powder, zinc powder, aluminum powder and copper powder; Coloring agents such as glass beads, talc, diatomaceous earth, alumina or hydrated alumina metal oxides; And mold release agents.

In the PAA solution polymerized by the above composition, in certain compositions, the CTE after curing is very close to the CTE of the copper foil. As described above, when the CTE of the polyimide resin is close to the CTE of the copper foil, the FCCL has less strain. However, FCCL, the result of pure polyimide resin without organic nanoclay, does not satisfy the dimensional stability of less than 0.2% of the average value required in the flexible printed circuit industry. The CTE difference between film and metal foil is improved.

In addition, the use of such an organic nanoclay may exhibit an excellent effect on the improvement of dimensional stability and smoothness according to their excellent dispersibility, unlike the use of a general inorganic filler.

In FCCL in which the polyimide film layer made of the above polyimide resin is laminated on the metal foil, the metal foil may be aluminum foil, copper foil or stainless foil, and the thickness thereof is preferably 4 to 38 microns.

Hereinafter, the present invention will be described in detail with reference to Examples. However, the present invention is not limited to these examples.

Synthesis Example: Preparation of montmorillonite (C16-MMT) to which hexadecylamine is bound

After removing impurities from Kunimine's Na ⁺ -montmorillonite (trade name: Kunipia-F) with an ion exchange capacity of 119 meq / 100g (trade name: Kunipia-F) with a 325 mesh sieve, concentrated hydrochloric acid solution and hexadecylamine were added to distilled water at 80 ° C. The mixture was added to 200 g of hexadecylamine ammonium salt obtained by reacting for about 1 hour, stirred for 1 hour, and the precipitated white powder was collected well, and further filtered for 1 hour in warm water after filtering. The above steps were repeated several times to remove residual ammonium salt and then dried after filtration to prepare hexadecylammonium montmorillonite organic clay (C16-MMT).

Examples 1-16

In a 2000 ml reactor equipped with a stirrer, a nitrogen purifier, a thermometer, and a cooling device, NMP was used as a PDA, an ODA, and a solvent, and dissolved under nitrogen flow at 50 ° C. and 200 rpm until a uniform diamine solution was formed. The mixture was added dropwise and reacted for 3 hours to synthesize PAA resins having different composition ratios of anhydride and amine. Add C16-MMT organic clay prepared in Synthesis Example to 1, 3, 5, 10 parts by weight based on 100 parts by weight of solids content of PAA, and homogenizer (Homogenizer; IKA, T-25) at 50 ° C. Was vigorously stirred at 1000 rpm for 30 minutes to prepare a PAA-nanocomposite resin. PAA-nanocomposite resin prepared above was applied to the surface of copper foil (Furukawa, F2-WS, t = 12 μm, CTE = 19 ppm / ° C.), 10 minutes at 90 ° C., 10 minutes at 130 ° C., 10 minutes at 150 ° C. The polyimide nanocomposite FCCL composed of the polyimide nanocomposite film layer and the copper foil was prepared by drying and curing under conditions of 10 minutes and 370 ° C. for 30 minutes to form a polyimide nanocomposite film on the copper foil.

Comparative Examples 1 to 4

In Comparative Examples 1 to 4, C16-MMT was not used, but other procedures were followed. Specific compositions are as shown in Table 1 below.

Comparative Examples 5 to 8

Comparative Examples 5 to 8 refer to the method disclosed in Korean Patent Laid-Open Publication No. 2004-011065, in which 3 parts by weight of mica powder is used based on 100 parts by weight of the solid content of PAA instead of the organic nanoclay. Specific compositions are as shown in Table 1 below.

And the properties of FCCL obtained by applying PAA-nanocomposite resin and PAA of Example and Comparative Example to copper foil and imidizing, respectively, were measured by the following method and the results are shown in Table 1 below.

(1) Intrinsic Viscosity (IV): ASTM D 2857-95

(2) Coefficient of Thermal Expansion (CTE): IPC-TM-650-2.4.24.5

(3) Peel Strength: IPC-TM-650-2.2.9

(4) Dimension Stability: IPC-TM-650-2.2.4

(5) Curl: ASTM D 3813M-98

Polyamic Acid Nanocomposite Resin Polyimide Nanocomposite FCCL Dianhydride Diamine solvent Organoclay Viscosity curl Adhesion CTE Dimensional stability BPDA (g) PDA (g) ODA (g) NMP (g) C ₁₆ -MMT (parts by weight based on 100 parts by weight of PAA solids) IV (dl / g) (mm) (Kg / cm) (ppm / ℃) (%) Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Comparative Example 5 148.6 148.6 148.6 148.6 148.6 148.6 37.9 37.9 37.9 37.9 37.9 37.9 30.0 30.0 30.0 30.0 30.0 30.0 1600 1600 1600 1600 1600 1600 0 1 3 5 10 3 ^* 1.11 1.09 1.09 1.11 1.11 1.00 6 0 0 0 1 6 1.01 1.00 1.02 1.01 1.01 1.00 22.1 20.0 19.5 18.6 20.5 24.0 0.04 0.02 0.01 0.01 0.05 0.20 Comparative Example 2 Example 5 Example 6 Example 7 Example 8 Comparative Example 6 148.6 148.6 148.6 148.6 148.6 148.6 27.0 27.0 27.0 27.0 27.0 27.0 50.1 50.1 50.1 50.1 50.1 50.1 1660 1660 1660 1660 1660 1660 0 1 3 5 10 3 ^* 1.09 1.19 1.06 1.00 1.08 0.99 7 0 0 0 0 6 1.20 1.22 1.19 1.20 1.21 1.10 25.0 21.0 18.1 19.5 21.0 27.0 0.09 0.04 0.02 0.01 0.04 0.20 Comparative Example 3 Example 9 Example 10 Example 11 Example 12 Comparative Example 7 148.6 148.6 148.6 148.6 148.6 148.6 16.2 16.2 16.2 16.2 16.2 16.2 70.1 70.1 70.1 70.1 70.1 70.1 1720 1720 1720 1720 1720 1720 0 1 3 5 10 3 ^* 1.02 1.02 1.09 1.04 0.97 1.11 9 4 0 0 0 8 1.80 1.70 1.75 1.78 1.80 1.60 34.0 23.5 19.5 18.8 20.2 36.0 0.19 0.11 0.06 0.04 0.08 0.23 Comparative Example 4 Example 13 Example 14 Example 15 Example 16 Comparative Example 8 148.6 148.6 148.6 148.6 148.6 148.6 5.4 5.4 5.4 5.4 5.4 5.4 90.1 90.1 90.1 90.1 90.1 90.1 1820 1820 1820 1820 1820 1820 0 1 3 5 10 3 ^* 1.09 0.95 1.07 1.09 1.05 1.10 8 5 0 0 2 8 2.10 2.15 2.05 2.20 1.95 2.01 38.0 26.8 20.8 20.2 21.5 40.0 0.22 0.14 0.09 0.05 0.10 0.25 * Is mica powder.

From the results of Table 1, it can be seen that the polyimide resin not containing any inorganic filler, including C16-MMT as in Comparative Examples 1 to 4 has a thermal expansion coefficient between 22-38ppm / ℃. However, as shown in the results of Examples 1 to 16, as C16-MMT was added, they showed some difference in the coefficient of thermal expansion between the polyimide resin and the copper foil, but the coefficient of thermal expansion of the polyimide nanocomposite was Show that they are becoming similar. And it can be seen that the polyimide nanocomposite FCCL has smoothness, excellent adhesion and excellent dimensional stability of less than 0.2% to satisfy the requirements of flexible printed circuit board processing companies. In addition, such a result is due to the addition effect of the organic nano-organic filler, it can be seen that the control of CTE during the production of polyimide.

On the other hand, when mica powder is used as the inorganic filler as in Comparative Examples 5 to 8, Although the adhesion is excellent, it can be seen that the dimensional stability, smoothness and CTE are too large to be used for FPCB applications.

As described in detail above, the polyimide resin prepared using the PAA-nanocomposite resin prepared by mixing the organicized nanoclay with the PAA has a thermal expansion coefficient similar to that of metal foil, and is easy to control the thermal expansion coefficient. The FCCL formed with the polyimide film layer has excellent adhesion, dimensional stability and smoothness, and is useful for use as a flexible printed circuit board.

Claims (10)

In a polyimide resin obtained by thermally imidating a polyamic acid precursor solution obtained by reacting an aromatic diamine and a dicarboxylic dianhydride under a polar aprotic organic solvent, The polyamic acid precursor solution is a polyimide resin, characterized in that the polyamic acid-nanocomposite resin comprising a polyamic acid precursor and an organic nanoclay. The method according to claim 1, wherein the organic nanoclay has a carbon number between the layers of one nanoclay selected from silicates, talc and mica having a thickness of 10 ^-9 m to 10 ^-7 , length 10 ^-8 m to 10 ^-6 m A polyimide resin, characterized in that the alkyl group of 5 to 38 is bonded. The polyimide resin according to claim 1 or 2, wherein the organicized nanoclay is included in an amount of 0.01 to 10.0 parts by weight based on 100 parts by weight of the polyamic acid precursor solid content. The method of claim 1, wherein the aromatic diamine is 4,1,3-bis (3-aminophenoxy) benzene, 4,4'-diaminodiphenylether, p-phenylenediamine, 4,4'-methylenebisaniline , At least one selected from 4,4'-aminophenyl sulfone, 4,4'-diaminobenzaniline and 2-methyl-4,4'-diaminobenzaniline, and is from 0.95 to dicarboxylic dianhydride A polyimide resin, characterized in that 1.05 molar ratio. The dicarboxylic dianhydride according to claim 1, wherein the dicarboxylic dianhydride is pyromellitic dianhydride, 4,4'-oxydi (phthalic anhydride), 3,4,3 ', 4'-biphenyltetracarboxylic dianhydride, 3, A polyimide resin, characterized in that at least one selected from 4,3 ', 4'-benzophenonetetracarboxylic dianhydride and 3,4,3', 4'-diphenylsulfontetracarboxylic dianhydride. In at least one surface of the metal foil, a flexible metal foil laminate having a polyimide film layer obtained by applying a polyamic acid precursor solution obtained by reacting an aromatic diamine and a dicarboxylic dianhydride under a polar aprotic organic solvent and then thermally imidizing the same. , The polyamic acid precursor solution is a flexible metal foil laminate, characterized in that the polyamic acid-nanocomposite resin comprising a polyamic acid precursor and an organic nanoclay. The method of claim 6, wherein the organic nanoclay is between the layer of one nanoclay selected from silicates, talc and mica of size 10 ^-9 m to 10 ^-7 m, length 10 ^-8 m to 10 ^-6 m. Flexible metal foil laminate, characterized in that the alkyl group having 5 to 38 carbon atoms are bonded. The flexible metal foil laminate according to claim 6 or 7, wherein the organicized nanoclay is included in an amount of 0.01 to 10.0 parts by weight based on 100 parts by weight of the polyamic acid precursor solid content. The flexible metal foil laminate according to claim 6, wherein the metal foil is one of aluminum foil, copper foil, and stainless foil. The flexible metal foil laminate according to claim 6 or 9, wherein the metal foil has a thickness of 4 to 38 microns.