TWI389951B - An opaque polyimide thin film and the manufacturing method thereof - Google Patents

Description

Opaque polyimide film and method of producing the same

The present invention relates to a polyimide film, and more particularly to an opaque, high-impedance polyimide film and a method of producing the same.

Currently, in general electronic devices, a printed circuit board (PCB) is often used to connect various electronic components in the device. Traditional circuit boards use printed etching methods to make circuits and drawings. With the continuous miniaturization and refinement of electronic products, most of the current circuit boards have been modified by lamination or coating, and then formed by exposure and development etching.

The design of the printed circuit board is based on the electronic circuit diagram to create the functions required by the user. Printed circuit board design requires good layout of internal electronic components, metal wiring, vias, and external connections, taking into account electromagnetic wave protection, heat dissipation, crosstalk, and many other factors. Excellent circuit design can save production costs and achieve good circuit performance and heat dissipation.

However, with the development of circuit board copying technology, the circuit on the circuit board is easily copied and plagiarized improperly, resulting in the loss of the original designer's intellectual property rights. If the circuit board is covered with an opaque film to completely cover the circuit design on the circuit board, the circuit on the circuit board can be difficult to be copied, effectively preventing theft problem. However, if the impedance of the film is too low, it may cause board failure problems when it is overlaid on the board. Therefore, there is a need in the art for a method that addresses the above problems.

One embodiment of the present invention provides an opaque, high-impedance polyimide film that can be overlaid on a commonly used circuit board and has sufficient resistance values to prevent the circuit board from failing, thereby effectively solving the current circuit board. Easy to be copied.

According to one embodiment of the present invention, there is provided a polyimine film comprising a polyimine which is formed by reacting at least one aromatic tetracarboxylic dianhydride and at least one aromatic diamine; and a char The carbon ash is wood ash produced by incomplete combustion of natural charcoal, wherein the carbon ash accounts for about 5-30% by weight of the solid content of the polyimide film, and the film resistance value is 10 ¹² -10 ¹⁶ Ω. According to an embodiment of the present invention, when the carbon solid content is 15% by weight, the surface resistivity of the above polyimide film is 10 ¹⁴ -10 ¹⁵ Ω. According to another embodiment of the present invention, when the carbon ash solid content is 30% by weight, the surface resistivity of the above polyimide film is 10 ¹² - 10 ¹³ Ω.

According to an embodiment of the present invention, the carbon ash described above is uniformly dispersed in the polyimide film. According to an embodiment of the present invention, the aromatic tetracarboxylic dianhydride is pyromellitic dianhydride, and the aromatic diamine is dimethyl diphenyl ether.

According to another embodiment of the present invention, a method for producing a polyimide film comprises forming a poly-proline solution, coating the polyamidite solution on one of the continuously rotating steel wheels to form a The polyaminic acid film; and heating the polyamic acid film to react to form a polyimine film. The above step of forming a polyaminic acid solution comprises (1) dissolving at least one aromatic diamine in a polar solvent, and (2) adding a char which is produced by incomplete combustion of natural charcoal (wood charcoal). Wood ash, wherein the carbon ash accounts for 5-30% by weight of the solid content in the polyimide film, and (3) at least one aromatic tetracarboxylic dianhydride is added.

According to an embodiment of the present invention, the carbon ash described above is uniformly dispersed in the polyimide film. According to another embodiment of the present invention, the polyamic acid film described above has a heating temperature of more than 80 to 400 °C. According to an embodiment of the present invention, the aromatic tetracarboxylic dianhydride is pyromellitic dianhydride, the aromatic diamine is diaminodiphenyl ether, and the polar solvent is dimethylacetamide.

In order to solve the problem that the circuit design in the prior art is easily stolen, the inventor of the present invention uses carbon ash which is a wood ash which is produced by incomplete combustion of natural charcoal by using a conventional polyimine film. The original translucent polyimide film can be converted into opaque light, and the opaque polyimide film is coated on the circuit board, so that the circuit design can no longer be easily seen by the naked eye, thereby enabling The purpose of the anti-theft copy is achieved; at the same time, the opaque polyimide film does not cause the impedance value to deteriorate due to the addition of the char, resulting in failure of the circuit board.

Carbon soot refers to a very fine carbon powder obtained by burning hydrocarbons in the absence of air, and then obtained as a pure black powder obtained by separating it from the exhaust gas. Because the charcoal color is extremely black and the coating power is extremely strong, it can be used as an ideal black pigment. The production of charcoal is mainly caused by the incomplete combustion of charcoal. Because it is the wood ash produced by natural charcoal, it has the characteristics of non-conductivity and high impedance. It is different from the general industrial use of heavy oil or creosote. (creosote oil) is burned in a closed reactor to produce carbon black of varying conductivity.

In a specific embodiment of the present invention, a high-impedance, opaque polyimide film is provided, characterized in that carbon ash is added to a polyimide film, and the char is incomplete from natural charcoal. Wood ash produced by combustion. The polyimine is formed by reacting at least one aromatic tetracarboxylic dianhydride with at least one aromatic diamine. In one example, when the carbon solid content is 15% by weight, the surface resistivity of the above polyimide film is 10 ¹⁴ -10 ¹⁵ Ω. In another example, when the carbon solid content is 30% by weight, the surface resistivity of the above polyimide film is 10 ¹² -10 ¹³ Ω.

Please refer to FIG. 1 , which illustrates a method 100 for fabricating an opaque polyimide film according to an embodiment of the present invention.

First, in step 110, a char ash-containing polyaminic acid solution is prepared, wherein the char ash is wood ash produced by incomplete combustion of natural charcoal. The polyaminic acid solution is prepared by first reacting a reactant (including an aromatic diamine monomer and an aromatic tetracarboxylic dianhydride monomer) for forming polyamic acid with a char in a suitable solvent. The mixture is uniformly mixed to obtain the above-mentioned char ash-containing polyaminic acid solution.

The aromatic tetracarboxylic dianhydride monomers suitable for use in step 110 include, but are not limited to, pyromellitic dianhydride (1,2,4,5 Benzene tetracarboxylic dianhydride), biphenyltetracarboxylic dianhydride (3) , 3'4,4'-Biphenyl tetracarboxylic dianhy dride), 4,4'-Oxydiphthalic anhydride, Benzophenonetetracarboxylicdianhydide, Diphenylphosphonium tetracarboxylate Acid dianhydride (3,3',4,4'-diphenyl sulfone tetracarboxylic dianhydride), 1,2,5,6-naph thalene tetracarboxylic dianhydride, naphthalene tetracaboxylic Dianhydride, Bis-(3,4-dicarboxypheny1)dimethylsilane dianhydride or a combination of the foregoing. In one example, the aromatic tetracarboxylic dianhydride monomer is pyromellitic dianhydride.

Suitable for the aromatic diamine monomer in step 110, including, but not limited to, 1,4 diamino benzene, 1,3 diamino benzene, 4,4'- 4,4'-oxydianiline, 3,4'-oxydianiline, 4,4'-diaminodiphenyl (4,4' -methylene dianiline), N,N'-Diphenylethylenediamine, diaminobenzophenone, diamino diphenyl sulfone, dinadiamine (1,5- Naphenylene diamine), 4,4'-diamino diphenyl sulfide, 1,3-bis(3-aminophenoxy)benzene , 1,4-Bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoloxy)benzene (1,3- Bis(4-aminophenoxy)benzene), 2,2-Bis[4-(4-aminophenphenoxy)phenyl]propane, 4,4'-bis(4-aminophenoloxy)biphenyl 4,4'-bis-(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoloxy)biphenyl 4, 4'-bis-(3-aminophenoxy)biphenyl, 1,3-dipropylamino-1,1,3,3-tetramethyl 1,3-Bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 1,3-dipropylamino-1,1,3,3-tetraphenyldioxane 1,3-Bis(3-aminopropyl)-1,1,3,3-tetraphenyldisiloxane), 1,3-dipropylamino-1,1-dimethyl-3,3-diphenyldioxane 1,3-Bis(aminopropyl)-dimethyldiphenyldisiloxane) or a combination of the foregoing. In one example, the aromatic diamine monomer is a diaminodiphenyl ether.

Suitable charcoal is wood ash produced by incomplete combustion of natural charcoal, which is a char with low electrical conductivity and high electrical resistance value, which can maintain the polyimine film made of polylysine solution. High impedance (for example, a film with a resistance value between 10 ¹⁴ -10 ¹⁶ Ω) and opaque.

Suitable solvents include, but are not limited to, N,N-Dimethyl formamide (DMF), Dimethylacetamide (DMAc), Dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP) or a combination of the foregoing. In one example, the solvent is dimethylacetamide.

In step 120, the polyaminic acid solution prepared according to the procedure described in step 110 is applied to a continuously rotating steel strip or steel wheel surface. In one example, the polyphthalic acid solution can be applied to the continuously rotating steel strip or steel wheel surface by gravity driven or pressure driven (e.g., by gas extrusion of a polydecanoic acid solution).

Finally, in step 130, the polyamic acid solution is heated to react to form a polyimide film. In an example, this heating step can be performed by a transmission. The poly-proline solution coated on the steel strip is rotated by a transmission device, and the stepwise heating is performed at a temperature of 80-400 ° C through a heating device to react the poly-proline to form a polyimide film.

Production examples and test results of the polyimide film are provided below. Among them, the test sample is a 10 cm×10 cm polyimide film of different thickness. The test method is based on the standard test method of surface resistance and volume resistance specified by American Society for Testing and Materials (ASTM) (ASTM D257). )get on.

Example 1 Production of Polyimine Film

First, 14.51 g of diaminodiphenyl ether was uniformly dissolved in 170 g of dimethylacetamide. Thereafter, 4.5 g of charcoal (this charcoal is wood ash produced by incomplete combustion of natural charcoal) was added to the above solution and stirred for 1 hour. Next, 15.49 g of pyromellitic dianhydride was slowly added to the above solution, and stirred at 30 ° C for 6 hours, and the solid content of the carbon ash was 15 wt% of the solid content of the entire polyimide film.

The polyamic acid solution described above is applied to a steel wheel or a steel strip, and is heated stepwise at a temperature of 80 to 400 ° C in an air or nitrogen atmosphere to prepare a black polyimide film of different thickness.

Table 1 is the average of the surface resistance test results of the produced polyimide film at different thicknesses. (1mil=0.0254mm)

It can be found from Table 1 that the polyimide films of different thicknesses produced have good impedance properties and their surface resistances are between 10 ^{15 and} 10 ¹⁶ Ω.

Example 2 Production of Polyimine Film

First, 19.34 g of diaminodiphenyl ether was uniformly dissolved in 160 g of dimethylacetamide. Thereafter, 4 g of charcoal (this charcoal is wood ash produced by incomplete combustion of natural charcoal) was added to the above solution and stirred for 1 hour. Next, 20.65 g of pyromellitic dianhydride was slowly added to the above solution, and stirred at 30 ° C for 6 hours. The solid content of the char is 10% by weight of the solid content of the entire polyimide film. A polyimide film having a thickness of 1 mil has a surface resistance measurement of 3.65 x ^{10 15} Ω.

The polyamic acid solution described above is applied to the above-mentioned steel wheel, and is heated stepwise at a temperature of 80 to 400 ° C in an air or nitrogen atmosphere to prepare a black polyimide film of different thickness.

Example 3 Production of Polyimine Film

First, 12.54 g of diaminodiphenyl ether was uniformly dissolved in 174 g of dimethylacetamide. Thereafter, 7.8 g of charcoal (this charcoal is wood ash produced by incomplete combustion of natural charcoal) was added to the above solution and stirred for 1 hour. Next, 13.46 g of pyromellitic dianhydride was slowly added to the above solution, and stirred at 30 ° C for 6 hours. The solid content of the char was 30% by weight of the solid content of the entire polyimide film, and the thickness was 1 mil. The yttrium imide film has a surface resistance measurement of 7.5 x 10 ¹² Ω.

The polyamic acid solution described above is applied to the above-mentioned steel wheel, and is heated stepwise at a temperature of 80 to 400 ° C in an air or nitrogen atmosphere to prepare a black polyimide film of different thickness.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and the present invention can be modified and modified without departing from the spirit and scope of the present invention. The scope is subject to the definition of the scope of the patent application attached.

100. . . method

110. . . step

120. . . step

130. . . step

The above and other objects, features, advantages and embodiments of the present invention will become more apparent and understood.

1 is a flow chart of a method for fabricating a polyimide film according to an embodiment of the present invention.

100. . . method

110. . . step

120. . . step

130. . . step

Claims (15)

An opaque polyimide film comprising: a polyimine, which is formed by reacting at least one aromatic tetracarboxylic dianhydride and at least one aromatic diamine; and a char, the char is natural Wood charcoal is a wood ash produced by incomplete combustion, wherein the char ash accounts for 5-30% by weight of the solid content in the polyimide film, and the surface resistance of the polyimide film is 10 ¹² -10 ¹⁶ Ω. The opaque polyimide film according to claim 1, wherein the carbon ash is uniformly dispersed in the polyimide film. The opaque polyimide film according to claim 1, wherein the aromatic tetracarboxylic dianhydride is pyromellitic dianhydride, biphenyl tetracarboxylic dianhydride, diphenyl ether tetracarboxylic dianhydride, Benzophenone tetracarboxylic dianhydride, diphenylphosphonium tetracarboxylic dianhydride, naphthyltetracarboxylic dianhydride, naphthalic anhydride, bis-(3,4-phthalic anhydride) dimethyl decane or a combination thereof . The opaque polyimide film according to claim 3, wherein the aromatic tetracarboxylic dianhydride is pyromellitic dianhydride. The opaque polyimide film according to claim 1, wherein the aromatic diamine is p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 3,4' -diaminodiphenyl ether, 4,4'-diaminodiphenyl, di-p-phenylenediamine, diaminobenzophenone, diamine diphenyl hydrazine, dinadiamine, diaminodiphenyl Thioether, 1,3-bis(3-aminophenoloxy)benzene, 1,4-bis(4-aminophenol) Benzo, 1,3-bis(4-aminophenoloxy)benzene, 2,2-bis[4-(4-aminophenoloxy)phenyl]propane, 4,4'-bis (4) -aminophenoloxy)biphenyl, 4,4'-bis(3-aminophenoloxy)biphenyl, 1,3-dipropylamino-1,1,3,3-tetramethyldioxan Alkane, 1,3-dipropylamino-1,1,3,3-tetraphenyldioxane, 1,3-dipropylamino-1,1-dimethyl-3,3-diphenyl A siloxane or a combination of the foregoing. The opaque polyimide film according to claim 5, wherein the aromatic diamine is diaminodiphenyl ether. The invention relates to a method for producing an opaque polyimide film, comprising: forming a poly-proline solution, comprising: dissolving at least one aromatic diamine in a polar solvent; adding a charcoal, the char is made of natural charcoal ( Wood charcoal) wood ash produced by incomplete combustion; and at least one aromatic tetracarboxylic acid dianhydride; coated with the polyamidite solution to continuously rotate a steel belt or a steel wheel surface to form a polyamine An acid film; and heating the polyamic acid film to react to form the opaque polyimide film, wherein the carbon ash accounts for 5-30 wt% of the solid content in the polyimide film, the poly The surface resistance of the imine film is 10 ¹² -10 ¹⁶ Ω. The method of claim 7, wherein the char is uniformly dispersed in the polyamic acid solution. The method of claim 7, wherein the polyglycolic acid film has a heating temperature of 80 to 400 °C. The method of claim 7, wherein the aromatic tetracarboxylic dianhydride is pyromellitic dianhydride, biphenyltetracarboxylic dianhydride, diphenyl ether tetracarboxylic dianhydride, benzophenone. Tetracarboxylic dianhydride, diphenylphosphonium tetracarboxylic dianhydride, naphthotetracarboxylic dianhydride, naphthalic anhydride, bis-(3,4-phthalic anhydride) dimethyl decane or a combination thereof. The method of claim 9, wherein the aromatic tetracarboxylic dianhydride is pyromellitic dianhydride. The method of claim 7, wherein the aromatic diamine is p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodi Phenyl ether, 4,4'-diaminodiphenyl, di-p-phenylenediamine, diaminobenzophenone, diamine diphenylphosphonium, dinadiamine, diaminodiphenyl sulfide, 1, 3-bis(3-aminophenoloxy)benzene, 1,4-bis(4-aminophenoloxy)benzene, 1,3-bis(4-aminophenoloxy)benzene, 2,2- Bis[4-(4-aminophenoloxy)phenyl]propane, 4,4'-bis(4-aminophenoloxy)biphenyl, 4,4'-bis(3-aminophenoloxyl) Biphenyl, 1,3-dipropylamino-1,1,3,3-tetramethyldioxane, 1,3-dipropylamino-1,1,3,3-tetraphenyldioxan Alkane, 1,3-dipropylamino-1,1-dimethyl-3,3-diphenyldioxane or a combination of the foregoing. The method of claim 11, wherein the aromatic diamine is a diaminodiphenyl ether. The method of claim 7, wherein the polar solvent is dimethylformamide, dimethylacetamide, dimethylhydrazine, butyrolactone, N-methylrrolidone or Combination of the foregoing. The method of claim 13, wherein the polar solvent is dimethylacetamide.