CN106800908B - Thermoplastic polyimide adhesive for two-layer flexible copper clad laminate and preparation method and application thereof - Google Patents

Abstract

The invention relates to the technical field of printed circuit boards, in particular to a thermoplastic polyimide adhesive for a two-layer flexible copper clad laminate and a preparation method thereof; Thermoplastic polyimide is obtained by chemically forming, and then mixed with a certain proportion (5-20%) of epoxy resin to prepare a thermoplastic polyimide adhesive for two-layer flexible copper clad laminates; the prepared thermoplastic polyimide Amine adhesive has good heat resistance and aging resistance, and has good bonding strength to copper foil and PI film, effectively solving the problem that thermoplastic polyimide is difficult to directly bond PI film. The invention also provides the application of the thermoplastic polyimide adhesive.

Description

Thermoplastic polyimide adhesive for two-layer flexible copper clad laminate and preparation method thereof law, application

technical field

The invention relates to the technical field of printed circuit boards, in particular to a thermoplastic polyimide adhesive for a two-layer flexible copper clad laminate, a preparation method and an application thereof.

Background technique

Flexible printed circuit boards have been widely used in consumer electronic products such as notebook computers, mobile phones, and digital cameras. Products tend to be thinner and more integrated, so the corresponding flexible copper clad laminates are required to be lighter and thinner, and at the same time, due to the increasingly strong functions and better integration of electronic products, the resistance to flexible copper clad laminates Thermal performance, stability and reliability all put forward higher requirements. Compared with the plastic sheet, the two-layer flexible copper clad laminate has achieved rapid development in recent years due to the use of polyimide resin materials with high strength and high modulus, excellent heat resistance and electrical properties; and the two-layer flexible There are copper foils on both sides of the CCL, which is easier to meet the requirements of flexible PCB manufacturers. Therefore, the use of double-sided CCL without glue is increasing.

At present, PI film is difficult to bond due to its smooth surface, less polar groups, and compact molecular arrangement. Although the PI film can significantly increase the bonding strength after surface treatment, the treatment effect will weaken or even disappear completely after high temperature baking. It is still difficult to improve the adhesion between thermoplastic polyimide and PI film after imidization after coating the thermoplastic polyimide precursor on the surface of the PI film. Currently, the most effective method is to coat the thermosetting polyimide precursor and the thermoplastic polyimide precursor successively and then imidize them together to ensure effective bonding between the two. However, this method is difficult to produce, and at the same time it is difficult to prepare PI composite membranes with thicker specifications.

Therefore, it is necessary to provide a thermoplastic polyimide adhesive, which not only has excellent bonding effect with copper foil, but also has good bonding with PI film. The adhesive has a simple synthesis method, high glass transition temperature, good heat resistance and aging resistance.

SUMMARY OF THE INVENTION

One of the purposes of the present invention is to provide a thermoplastic polyimide adhesive; the second purpose of the present invention is to provide a method for preparing the above-mentioned thermoplastic polyimide adhesive; the third purpose of the present invention is to provide A two-layer bi-flexible copper clad laminate made of the thermoplastic polyimide adhesive.

In order to achieve this purpose, the present invention provides a thermoplastic polyimide adhesive for a two-layer flexible copper clad laminate. In terms of mass percentage, the thermoplastic polyimide adhesive comprises 80% of thermoplastic polyimide. ~ 95% and epoxy resin 5% ~ 20%. Thermoplastic polyimide can be 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93% or 94%; cyclic Oxygen resin can be: 6%, 8%, 10%, 12%, 13%, 15%, 16%, 17%, 18% or 19%.

Preferably, the epoxy resin is bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, biphenyl type epoxy resin or phenolic resin Any one or a mixture of at least two of the epoxy resins.

Preferably, the thermoplastic polyimide adhesive further includes a solvent, and the solid content of the thermoplastic polyimide adhesive is 5wt%-30wt%. For example, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 15wt%, 18wt%, 20wt%, 22wt%, 25wt%, 26wt%, 28wt% or 29wt%.

Preferably, the solvent is any one or a mixture of at least two of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone .

The present invention also provides a method for preparing the above-mentioned thermoplastic polyimide adhesive, the preparation method comprising the steps:

(1) Synthesis of thermoplastic polyimide precursor;

(2) chemically imidizing a thermoplastic polyimide precursor to obtain a thermoplastic polyimide; and

(3) adding epoxy resin according to the above mass percentage to obtain the thermoplastic polyimide adhesive.

Preferably, the thermoplastic polyimide precursor is polymerized from diamine monomer and dianhydride monomer.

(4,4’-二氨基-二苯醚)、

(3,4’-二氨基-二苯醚)、

(4,4’-二氨基-二苯硫醚)、

(2,2-双(4-氨基苯基)丙烷)、

(4,4’-双(氨基苯氧基)二苯醚)、

(2,2-双[4-(4-氨基苯氧基)苯基]丙烷)、

(1,3-双[3(4)氨基苯氧基]苯)、

(4,4’-双(氨基苯氧基)二苯砜)中的任意一种或至少两种的混合物。Preferably, the diamine monomer is

(4,4'-diamino-diphenyl ether),

(3,4'-diamino-diphenyl ether),

(4,4'-diamino-diphenyl sulfide),

(2,2-bis(4-aminophenyl)propane),

(4,4'-bis(aminophenoxy)diphenyl ether),

(2,2-bis[4-(4-aminophenoxy)phenyl]propane),

(1,3-bis[3(4)aminophenoxy]benzene),

(4,4'-bis(aminophenoxy)diphenylsulfone) any one or a mixture of at least two.

(3,3’,4,4’-联苯四酸二酐)、

(3,3’,4,4’-二苯醚四酸二酐)、

(均苯四酸二酐)、

(2,2’,3,3’-联苯四酸二酐)中的任意一种或至少两种的混合物。Preferably, the dianhydride monomer is

(3,3',4,4'-biphenyltetracarboxylic dianhydride),

(3,3',4,4'-diphenyl ether tetraacid dianhydride),

(pyromellitic dianhydride),

(2,2',3,3'-biphtalic dianhydride) any one or a mixture of at least two.

Preferably, the dehydrating agent used in the chemical imidization is acetic anhydride, and the accelerator is any one or a mixture of at least two of pyridine, triethylamine or isoquinoline.

A two-layer method double-sided flexible copper clad laminate, comprising a PI composite film and a copper foil pressed on the PI composite film, the PI composite film comprising a PI film and a PI film coated on the PI film. Thermoplastic polyimide adhesive as described above.

A two-layer method double-sided flexible copper clad laminate, comprising an adhesive-coated copper foil and a PI film laminated on the adhesive-coated copper foil, the adhesive-coated copper foil comprising a copper foil and The thermoplastic polyimide adhesive as described above is coated on the copper foil.

A two-layer method double-sided flexible copper clad laminate, comprising at least two press-fit type glue-free single-sided boards that are pressed together with each other, and the press-fit type glue-free single-sided boards include glue-free single-sided boards and glue-free single-sided boards. The above-mentioned thermoplastic polyimide adhesive on a single panel, the adhesive-free single panel is composed of copper foil and PI film, and the thermoplastic polyimide adhesive is coated on the PI film.

Preferably, the thickness of the PI film is 12-125 μm. Can be 13 μm, 15 μm, 18 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 105 μm, 110 μm, 120 μm or 124 μm.

Preferably, the coating thickness of the thermoplastic polyimide adhesive is 2-10 μm. Can be 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm or 9 μm.

Preferably, the thickness of the copper foil is 9-70 μm, which can be 10 μm, 15 μm, 18 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm or 69 μm.

Compared with the prior art, the present invention has the following beneficial effects:

The thermoplastic polyimide adhesive of the present invention can be coated on the PI film for baking, and then pressed with the copper foil to obtain a two-layer flexible copper clad laminate, or coated on the rough surface of the copper foil and baked , and high temperature lamination with PI film to prepare two-layer flexible copper clad laminate. The method significantly improves the production efficiency, and the thermoplastic polyimide adhesive does not need thermal imidization, which greatly simplifies the production process and saves the production cost. At the same time, it successfully solves the difficult problem that the existing thermoplastic polyimide can not be effectively bonded to the surface of the PI film directly coated.

The thermoplastic polyimide adhesive for the two-layer flexible copper clad laminate prepared by the invention utilizes: thermoplastic polyimide has excellent heat resistance, high glass transition temperature, excellent copper foil adhesion and compressibility and the addition of epoxy resin significantly improved its adhesion to PI film. It is ensured that the final thermoplastic polyimide adhesive has high glass transition temperature, excellent heat resistance, aging resistance, flame retardancy and excellent bonding effect with PI film and copper foil.

In the prior art, the method of using polyimide acid to cure epoxy resin is that due to the low ratio of polyamic acid cyclization, many properties such as heat resistance and Tg are significantly lower than that of polyimide. In the present invention, a relatively complete imidized soluble polyimide is obtained by mild chemical imidization. A lower proportion of uncyclized carboxyl groups in the polyimide react to achieve partial cross-linking. At the same time, due to the introduction of epoxy, the adhesion of thermoplastic polyimide to PI film and copper foil is significantly improved. Due to the low proportion of epoxy resin (<20%) and the high degree of chemical imidization, many excellent properties of thermoplastic polyimide itself have not been significantly reduced. While basically maintaining the excellent performance of thermoplastic polyimide, the adhesive greatly improves its bonding effect to PI film, and solves the difficult problem in the industry that thermoplastic polyimide is difficult to bond PI film.

In addition, chemical imidization is adopted in the production process of the thermoplastic polyimide adhesive for the two-layer flexible copper clad laminate of the present invention, which can be directly used in the subsequent coating process without high-temperature imidization, thus significantly improving the The production efficiency greatly simplifies the production process and saves the production cost. At the same time, depending on the thickness of the PI film, thick products that cannot be produced by traditional TPI composite films and coating methods can be prepared.

Detailed ways

The technical solutions of the present invention are further described below through specific embodiments.

The raw materials and brief expressions of the synthetic thermoplastic polyimide adhesive in the present invention are described as follows:

NMP: polar solvent, N-methylpyrrolidone

DMAc: polar solvent, N,N-dimethylacetamide

ODA: 4,4'-diaminodiphenyl ether (molecular weight 200.24, CAS No: 101-80-4)

BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propane (MW 410.51, CAS No: 13080-86-9)

TPE-Q: 1,3-bis[4-aminophenoxy]benzene (molecular weight 292.33, CAS No: 2479-46-1)

BAPS: 4,4'-bis(4-aminophenoxy)diphenylsulfone (molecular weight 432.49, CAS No: 13080-89-2)

BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride (molecular weight 294.22, CAS No: 2420-87-3)

OPDA: 4,4'-biphenyl ether dianhydride (molecular weight 310.21, CAS No: 1823-59-2)

PMDA: pyromellitic dianhydride (molecular weight 218.12, CAS No: 89-32-7)

A polyimide adhesive for a two-layer flexible copper clad laminate, characterized in that the preparation method comprises the following steps:

(1) Synthesis of thermoplastic polyimide precursor (polyamic acid);

(2) chemically imidizing the thermoplastic polyimide precursor to obtain a thermoplastic polyimide solution with a relatively complete degree of imidization;

(3) An epoxy resin is provided, and a certain proportion of epoxy resin is added to the thermoplastic polyimide solution to obtain the polyimide adhesive for a two-layer flexible copper clad laminate.

Compared with the prior art, the thermoplastic polyimide adhesive of the present invention can be coated on a PI film for baking, and then pressed with a copper foil to obtain a two-layer flexible copper clad laminate, or coated on a copper foil. After the foil matte surface is baked, it is laminated with the PI film at high temperature to prepare a two-layer flexible copper clad laminate. The method significantly improves the production efficiency, and the thermoplastic polyimide adhesive does not need thermal imidization, which greatly simplifies the production process and saves the production cost. At the same time, the difficult problem that thermoplastic polyimide directly coated on the surface of PI film cannot be effectively bonded is successfully solved.

Specifically, the diamine monomers for synthesizing the thermoplastic polyimide adhesive are 4,4'-diamino-diphenyl ether, 3,4'-diamino-diphenyl ether, 4,4'-diamino-diphenyl ether, Diamino-diphenyl sulfide, 4,4'-bis(aminophenoxy)diphenyl ether, 2,2-bis(4-aminophenyl)propane, 2,2-bis[4-(4-amino) One or more of phenoxy)phenyl]propane, 1,3-bis[3(4)aminophenoxy]benzene, and 4,4'-bis(aminophenoxy)diphenylsulfone.

Preferably, the synthetic thermoplastic polyimide adhesive dianhydride monomers are 3,3',4,4'-biphtalic dianhydride, 3,3',4,4'-diphenyl ether One or more of tetracarboxylic dianhydride, pyromellitic dianhydride, and 2,2',3,3'-biphthalic dianhydride.

To prepare a two-layer double-sided flexible copper clad laminate, a thermoplastic polyimide adhesive is first prepared, and one of the specific methods is as follows.

Synthesis Example 1

A total of 720g of polar solvents NMP (N-methylpyrrolidone) and DMAc (N,N-dimethylacetamide) were added to a 1L three-necked flask, and 25.95g of BAPS and 36.95g of BAPP were weighed and dissolved in the above polar solvent. A solution was obtained in the free solvent NMP and DMAc, the solution was cooled in a water bath, 22.07 g of BPDA and 23.27 g of ODPA were added under nitrogen flow, the reaction temperature was controlled to be 15-20 ° C, and the reaction was continued for 12 hours. Polyamic acid resin glue, the solid content of which is 13%;

Subsequent chemical imidization: mix 80 ml of acetic anhydride and 40 ml of pyridine, and add it to the polyamic acid resin glue prepared above. After stirring and reacting at room temperature for 24 hours, add 5% (relative to polyimide) bisphenol A type epoxy resin.

Synthesis Example 2

A total of 620g of polar solvents NMP (N-methylpyrrolidone) and DMAc (N,N-dimethylacetamide) were added to a 1L three-necked flask, and 25.95g of BAPS and 36.95g of BAPP were weighed and dissolved in the above polar solvent. A solution was obtained in the natural solvent NMP and DMAc, the solution was cooled in a water bath, 46.54 g of ODPA was added under nitrogen flow, the reaction temperature was controlled to be 15-20 ° C, and the reaction was continued for 12 hours, and the reaction was carried out to prepare the polyamic acid resin glue. liquid, the solid content of which is 15%;

Subsequent chemical imidization: Mix 80 ml of acetic anhydride and 40 ml of triethylamine and add it to the polyamic acid resin glue prepared above. After stirring and reacting at room temperature for 24 hours, add 10% (relative to polyimide) bisphenol Type A epoxy resin.

Synthesis Example 3

A total of 620g of polar solvents NMP (N-methylpyrrolidone) and DMAc (N,N-dimethylacetamide) were added to a 1L three-necked flask, and 25.95g of BAPS and 36.95g of BAPP were weighed and dissolved in the above polar solvent. A solution was obtained in the natural solvent NMP and DMAc, the solution was cooled in a water bath, 46.54 g of ODPA was added under nitrogen flow, the reaction temperature was controlled to be 15-20 ° C, and the reaction was continued for 12 hours, and the reaction was carried out to prepare the polyamic acid resin glue. liquid, the solid content of which is 15%;

Subsequent chemical imidization: mix 80 ml of acetic anhydride and 40 ml of triethylamine, add them to the polyamic acid resin glue prepared above, stir and react at room temperature for 24 hours, add 15% (relative to polyimide) bisphenol Type A epoxy resin.

Synthesis Example 4

A total of 828g of polar solvents NMP (N-methylpyrrolidone) and DMAc (N,N-dimethylacetamide) were added to a 1L three-necked flask, and 29.23g of TPE-R and 41.15g of BAPP were weighed and dissolved in Obtain solution in above-mentioned polar solvent NMP and DMAc, this solution is cooled in water bath, add the PMDA of 21.82g and 44.13g BPDA under nitrogen flow, control reaction temperature to be 15-20 ℃, continue stirring 12 hours, carry out reaction, prepare Polyamic acid resin glue, the solid content of which is 15%;

Subsequent chemical imidization: mix 128 ml of acetic anhydride and 64 ml of triethylamine, add them into the polyamic acid resin glue prepared above, stir and react at room temperature for 24 hours, add 15% (relative to polyimide) biphenyl type epoxy resin.

Synthesis Example 5

Add 880 g of polar solvent DMAc (N,N-dimethylacetamide) to a 1L three-necked flask, weigh 31.04 g of 3,4'-diamino-diphenyl ether, and dissolve it in the above polar solvent DMAc A solution was obtained in , the solution was cooled in a water bath, 46.53 g of 3,3',4,4'-diphenyl ether tetraacid dianhydride was added under nitrogen flow, the reaction temperature was controlled to be 15-20 ° C, and stirring was continued for 12 hours , carry out the reaction, prepare the polyamic acid resin glue, wherein the solid content is 8%;

Subsequent chemical imidization: take 80 ml of acetic anhydride, 20 ml of pyridine, and 20 ml of triethylamine and add them to the polyamic acid resin glue prepared above. After stirring and reacting at room temperature for 24 hours, add 7% (relative to polyimide) of bisphenol S-type epoxy resin.

Synthesis Example 6

Add 440 g of polar solvent DMSO (dimethyl sulfoxide) to a 1 L three-necked flask, weigh 21.62 g of 4,4'-diamino-diphenyl sulfide, and dissolve it in the above polar solvent DMSO to obtain a solution , the solution was cooled in a water bath, 8.72g of pyromellitic dianhydride and 18.62g of 3,3',4,4'-diphenyl ether tetraacid dianhydride were added under nitrogen flow, and the reaction temperature was controlled to be 15-20°C , continue to stir for 12 hours, carry out the reaction, prepare the polyamic acid resin glue, wherein the solid content is 10%;

Subsequent chemical imidization: mix 80 ml of acetic anhydride, 20 ml of triethylamine, and 20 ml of isoquinoline, and add them to the polyamic acid resin glue prepared above. After stirring and reacting at room temperature for 24 hours, add 12% (relative polyimide amine) of the bisphenol AF epoxy resin.

Synthesis Example 7

A polar solvent NMP (N-methylpyrrolidone) 490g was added to a 1L three-necked flask, 62.01g of 2,2-bis(4-aminophenyl)propane was weighed, and it was dissolved in the above-mentioned polar solvent NMP to obtain solution, the solution was cooled in a water bath, and 29.42 g of 2,2',3,3'-biphenyltetracarboxylic dianhydride and 15.51 g of 3,3',4,4'-diphenylether tetraacid were added under nitrogen flow dianhydride, control the reaction temperature to be 15-20°C, continue stirring for 12 hours, carry out the reaction, and prepare a polyamic acid resin glue, wherein the solid content is 18%;

Subsequent chemical imidization: take 80 ml of acetic anhydride, 20 ml of pyridine, and 20 ml of isoquinoline, and add them to the polyamic acid resin glue prepared above. biphenyl type epoxy resin.

Synthesis Example 8

A total of 366g of polar solvent DMF (N,N-dimethylformamide) and DMAc (N,N-dimethylacetamide) were added to a 1L three-necked flask, and 57.67g of 4,4'-bis( Aminophenoxy) diphenyl ether was dissolved in the above polar solvents DMF and DMAc to obtain a solution, the solution was cooled in a water bath, 14.711g of BPDA and 31.02g of 3,3',4 were added under nitrogen flow ,4'-diphenyl ether tetraacid dianhydride, control the reaction temperature to be 15-20 ℃, continue to stir for 12 hours, carry out the reaction, and prepare the polyamic acid resin glue, wherein the solid content is 22%;

Subsequent chemical imidization: Mix 80 ml of acetic anhydride and 40 ml of triethylamine and add it to the polyamic acid resin glue prepared above. After stirring and reacting at room temperature for 24 hours, add 17% (relative to polyimide) phenolic ring Oxygen resin.

Synthesis Example 9

A total of 306g of polar solvent DMAc (N,N-dimethylacetamide) and DMSO (dimethyl sulfoxide) was added to a 1L three-necked flask, 61.57g of BAPP was weighed, and it was dissolved in the above polar solvent DMAc and DMSO to obtain a solution, the solution was cooled in a water bath, 14.711g of BPDA and 31.02g of 3,3',4,4'-diphenyl ether tetraacid dianhydride were added under nitrogen flow, and the reaction temperature was controlled to be 15- 20° C., stirring continuously for 12 hours, and reacting to prepare a polyamic acid resin glue, the solid content of which is 26%;

Subsequent chemical imidization: mix 80 ml of acetic anhydride and 40 ml of triethylamine, and add them to the polyamic acid resin glue prepared above. After stirring and reacting at room temperature for 24 hours, add 18% (relative to polyimide) bisphenol A type epoxy resin and biphenyl type epoxy resin.

Synthesis Example 10

A total of 272 g of polar solvent NMP (N-methylpyrrolidone) and DMSO (dimethyl sulfoxide) was added to a 1L three-necked flask, and 58.46 g of 1,3-bis[3aminophenoxy]benzene was weighed. It was dissolved in the above polar solvents NMP and DMSO to obtain a solution, the solution was cooled in a water bath, and 21.81 g of pyromellitic dianhydride and 31.02 g of 2,2',3,3'-bicarbonate were added under nitrogen flow. Phenyl ether tetraacid dianhydride, control the reaction temperature to be 15-20 ° C, continue to stir for 12 hours, carry out the reaction, and prepare the polyamic acid resin glue, wherein the solid content is 29%;

Subsequent chemical imidization: Mix 80 ml of acetic anhydride and 40 ml of triethylamine, and add them to the polyamic acid resin glue prepared above. After stirring and reacting at room temperature for 24 hours, add 9% (relative to polyimide) bisphenol F-type epoxy and phenolic resin.

Synthesis Example 11

A total of 720g of polar solvents NMP (N-methylpyrrolidone) and DMAc (N,N-dimethylacetamide) were added to a 1L three-necked flask, and 25.95g of BAPS and 36.95g of BAPP were weighed and dissolved in the above polar solvent. A solution was obtained in the free solvent NMP and DMAc, the solution was cooled in a water bath, 22.07 g of BPDA and 23.27 g of ODPA were added under nitrogen flow, the reaction temperature was controlled to be 15-20 ° C, and the reaction was continued for 12 hours. Polyamic acid resin glue, the solid content of which is 13%;

Subsequent chemical imidization: 80 ml of acetic anhydride and 40 ml of pyridine were mixed and added to the polyamic acid resin glue solution prepared above, and the mixture was stirred and reacted at room temperature for 24 hours before use.

Synthesis Example 12

A total of 620g of polar solvents NMP (N-methylpyrrolidone) and DMAc (N,N-dimethylacetamide) were added to a 1L three-necked flask, and 25.95g of BAPS and 36.95g of BAPP were weighed and dissolved in the above polar solvent. A solution was obtained in the natural solvent NMP and DMAc, the solution was cooled in a water bath, 46.54 g of ODPA was added under nitrogen flow, the reaction temperature was controlled to be 15-20 ° C, and the reaction was continued for 12 hours, and the reaction was carried out to prepare the polyamic acid resin glue. liquid, the solid content of which is 15%;

Subsequent chemical imidization: 80 ml of acetic anhydride and 40 ml of pyridine were mixed and added to the polyamic acid resin glue solution prepared above, and the mixture was stirred and reacted at room temperature for 24 hours before use.

Synthesis Example 13

A total of 720g of polar solvents NMP (N-methylpyrrolidone) and DMAc (N,N-dimethylacetamide) were added to a 1L three-necked flask, and 25.95g of BAPS and 36.95g of BAPP were weighed and dissolved in the above polar solvent. A solution was obtained in the free solvent NMP and DMAc, the solution was cooled in a water bath, 22.07 g of BPDA and 23.27 g of ODPA were added under nitrogen flow, the reaction temperature was controlled to be 15-20 ° C, and the reaction was continued for 12 hours. Polyamic acid resin glue, the solid content of which is 13%;

Finally, the prepared thermoplastic polyimide adhesive is applied to the two-layer flexible copper clad laminate, and the specific preparation method is as follows.

Example 1

First, a PI film with a thickness of 25 μm is provided, and the thermoplastic polyimide adhesive (Synthesis Example 1) prepared in the previous step is coated on both sides of the PI film with a thickness of 25 μm, and the coating thickness is 5 μm, hot air drying at 160°C for 5 minutes; to obtain thermoplastic polyimide adhesive-PI film-thermoplastic polyimide adhesive (PI composite film);

Finally, the above-obtained PI composite film was bonded to the double-sided copper foil, and was pressed on a high-temperature press at a temperature of 340° C. to obtain a two-layer double-sided flexible copper clad laminate.

Example 2

First, a PI film with a thickness of 50 μm is provided, and the thermoplastic polyimide adhesive (Synthesis Example 1) obtained in the previous step is coated on both sides of the PI film with a thickness of 25 μm, and the coating thickness is 5 μm, hot air drying at 160°C for 5 minutes; to obtain thermoplastic polyimide adhesive-PI film-thermoplastic polyimide adhesive (PI composite film);

Finally, the above-obtained PI composite film is bonded to the double-sided copper foil, and is pressed on a high-temperature press at a temperature of 330° C. to obtain a two-layer double-sided flexible copper clad laminate.

Example 3

First, a PI film with a thickness of 75 μm is provided, and the thermoplastic polyimide adhesive (Synthesis Example 2) prepared in the previous step is coated on both sides of the PI film with a thickness of 25 μm, and the coating thickness is 5 μm, hot air drying at 160°C for 5 minutes; to obtain thermoplastic polyimide adhesive-PI film-thermoplastic polyimide adhesive (PI composite film);

Finally, the above-obtained PI composite film is bonded to the double-sided copper foil, and is pressed on a high-temperature press at a temperature of 330° C. to obtain a two-layer double-sided flexible copper clad laminate.

Example 4

First, a PI film with a thickness of 25 μm is provided, and the thermoplastic polyimide adhesive (Synthesis Example 3) prepared in the previous step is coated on both sides of the PI film with a thickness of 25 μm, and the coating thickness is 5 μm, hot air drying at 160°C for 5 minutes; to obtain thermoplastic polyimide adhesive-PI film-thermoplastic polyimide adhesive (PI composite film);

Finally, the above-obtained PI composite film is bonded to the double-sided copper foil, and is pressed on a high-temperature press at a temperature of 330° C. to obtain a two-layer double-sided flexible copper clad laminate.

Example 5

First, a PI film with a thickness of 50 μm is provided, and the thermoplastic polyimide adhesive (Synthesis Example 4) prepared in the previous step is coated on both sides of the PI film with a thickness of 25 μm, and the coating thickness is 5 μm, hot air drying at 160°C for 5 minutes; to obtain thermoplastic polyimide adhesive-PI film-thermoplastic polyimide adhesive (PI composite film);

Finally, the above-obtained PI composite film is bonded to the double-sided copper foil, and is pressed on a high-temperature press at a temperature of 330° C. to obtain a two-layer double-sided flexible copper clad laminate.

Example 6

First, a PI film with a thickness of 125 μm was provided, and the thermoplastic polyimide adhesive (Synthesis Example 5) obtained in the previous step was coated on both sides of the PI film with a thickness of 25 μm, and the coating thickness was 5 μm, hot air drying at 160°C for 5 minutes; to obtain thermoplastic polyimide adhesive-PI film-thermoplastic polyimide adhesive (PI composite film);

Finally, the above-obtained PI composite film is bonded to the double-sided copper foil, and is pressed on a high-temperature press at a temperature of 330° C. to obtain a two-layer double-sided flexible copper clad laminate.

Example 7

First, an electrolytic copper foil with a thickness of 13 μm is provided, and the thermoplastic polyimide adhesive (Synthesis Example 6) obtained in the previous step is coated on the rough surface of the electrolytic copper foil with a thickness of 13 μm. The thickness is 4 μm, and the hot air is dried at 160°C for 5 minutes; the adhesive-coated copper foil is obtained;

Finally, the above-obtained adhesive-coated copper foil was laminated with a 125-micron PI film, and pressed on a high-temperature press at a temperature of 340° C. to obtain a two-layer double-sided flexible copper clad laminate.

Example 8

First, an electrolytic copper foil with a thickness of 13 μm is provided, and the thermoplastic polyimide adhesive (Synthesis Example 7) obtained in the previous step is coated on the rough surface of the electrolytic copper foil with a thickness of 13 μm, and the coating The thickness is 4 μm, and the hot air is dried at 160°C for 5 minutes; the adhesive-coated copper foil is obtained;

Finally, the adhesive-coated copper foil obtained above was bonded with a 50-micron PI film, and was pressed on a high-temperature press at a temperature of 340° C. to obtain a two-layer double-sided flexible copper clad laminate.

Example 9

First, an electrolytic copper foil with a thickness of 13 μm is provided, and the thermoplastic polyimide adhesive (Synthesis Example 8) prepared in the previous step is coated on the rough surface of the electrolytic copper foil with a thickness of 13 μm, and the coating The thickness is 4 μm, and the hot air is dried at 160°C for 5 minutes; the adhesive-coated copper foil is obtained;

Finally, the above-obtained adhesive-coated copper foil is bonded to a 25-micron PI film, and pressed on a high-temperature press at a temperature of 340° C. to obtain a two-layer double-sided flexible copper clad laminate.

Example 10

First, an electrolytic copper foil with a thickness of 13 μm is provided, and the thermoplastic polyimide adhesive (Synthesis Example 9) obtained in the previous step is coated on the rough surface of the electrolytic copper foil with a thickness of 13 μm. The thickness is 4 μm, and the hot air is dried at 160°C for 5 minutes; the adhesive-coated copper foil is obtained;

Finally, the above-obtained adhesive-coated copper foil is bonded to a 25-micron PI film, and pressed on a high-temperature press at a temperature of 340° C. to obtain a two-layer double-sided flexible copper clad laminate.

Example 11

First, a rolled copper foil with a thickness of 13 μm is provided, and the thermoplastic polyimide adhesive (Synthesis Example 10) obtained in the previous step is coated on the rough surface of the electrolytic copper foil with a thickness of 13 μm, and the coating The thickness is 4 μm, and the hot air is dried at 160°C for 5 minutes; the adhesive-coated copper foil is obtained;

Finally, the above-obtained adhesive-coated copper foil was bonded with a 75-micron PI film, and pressed on a high-temperature press at a temperature of 340° C. to obtain a two-layer double-sided flexible copper clad laminate.

Example 12

First, a rolled copper foil with a thickness of 13 μm is provided, and the thermoplastic polyimide adhesive (Synthesis Example 3) obtained in the previous step is coated on the rough surface of the electrolytic copper foil with a thickness of 13 μm, and the coating The thickness is 4 μm, and the hot air is dried at 160°C for 5 minutes; the adhesive-coated copper foil is obtained;

Finally, the above-obtained adhesive-coated copper foil was laminated with a 125-micron PI film, and pressed on a high-temperature press at a temperature of 340° C. to obtain a two-layer double-sided flexible copper clad laminate.

Comparative Example 1

First, a PI film with a thickness of 25 μm is provided, and the thermoplastic polyimide adhesive (Synthesis Example 11) prepared in the previous step is coated on both sides of the PI film with a thickness of 25 μm, and the coating thickness is 5 μm, hot air drying at 160°C for 5 minutes; to obtain thermoplastic polyimide adhesive-PI film-thermoplastic polyimide adhesive (PI composite film);

Finally, the above-obtained PI composite film is bonded to the double-sided copper foil, and is pressed on a high-temperature press at a temperature of 330° C. to obtain a two-layer double-sided flexible copper clad laminate.

Comparative Example 2

First, a PI film with a thickness of 50 μm is provided, and the thermoplastic polyimide adhesive (Synthesis Example 11) prepared in the previous step is coated on both sides of the PI film with a thickness of 50 μm, and the coating thickness is 5 μm, hot air drying at 160°C for 5 minutes; to obtain thermoplastic polyimide adhesive-PI film-thermoplastic polyimide adhesive (PI composite film);

Finally, the above-obtained PI composite film was bonded to the double-sided copper foil, and was pressed on a high-temperature press at a temperature of 340° C. to obtain a two-layer double-sided flexible copper clad laminate.

Comparative Example 3

First, a PI film with a thickness of 25 μm is provided, and the thermoplastic polyimide adhesive (Synthesis Example 12) obtained in the previous step is coated on both sides of the PI film with a thickness of 25 μm, and the coating thickness is 5 μm, hot air drying at 160°C for 5 minutes; to obtain thermoplastic polyimide adhesive-PI film-thermoplastic polyimide adhesive (PI composite film);

Finally, the above-obtained PI composite film was bonded to the double-sided copper foil, and was pressed on a high-temperature press at a temperature of 340° C. to obtain a two-layer double-sided flexible copper clad laminate.

Comparative Example 4

First, a PI film with a thickness of 75 μm is provided, and the thermoplastic polyimide adhesive (Synthesis Example 12) prepared in the previous step is coated on both sides of the PI film with a thickness of 75 μm, and the coating thickness is 5 μm, hot air drying at 160°C for 5 minutes; to obtain thermoplastic polyimide adhesive-PI film-thermoplastic polyimide adhesive (PI composite film);

Finally, the above-obtained PI composite film was bonded to the double-sided copper foil, and was pressed on a high-temperature press at a temperature of 340° C. to obtain a two-layer double-sided flexible copper clad laminate.

Comparative Example 5

First, a PI film with a thickness of 25 μm is provided, and the thermoplastic polyimide adhesive (Synthesis Example 13) prepared in the previous step is coated on both sides of the PI film with a thickness of 25 μm, and the coating thickness is 5 μm, 160 ℃ hot air drying for 5 minutes; then in a high temperature oven with 160 ℃, 200 ℃, 250 ℃, 300 ℃, 320 ℃ for 10 minutes, respectively, to complete the imidization of the thermoplastic polyamic acid resin. A thermoplastic polyimide adhesive-PI film-thermoplastic polyimide adhesive (PI composite film) is obtained;

Finally, the above-obtained PI composite film was bonded to the double-sided copper foil, and was pressed on a high-temperature press at a temperature of 340° C. to obtain a two-layer double-sided flexible copper clad laminate.

Comparative Example 6

First, a PI film with a thickness of 125 μm is provided, and the thermoplastic polyimide adhesive (Synthesis Example 13) prepared in the previous step is coated on both sides of the PI film with a thickness of 125 μm, and the coating thickness is 5 μm, 160 ℃ hot air drying for 5 minutes; then in a high temperature oven with 160 ℃, 200 ℃, 250 ℃, 300 ℃, 320 ℃ for 10 minutes, respectively, to complete the imidization of the thermoplastic polyamic acid resin. A thermoplastic polyimide adhesive-PI film-thermoplastic polyimide adhesive (PI composite film) is obtained;

Finally, the above-obtained PI composite film was bonded to the double-sided copper foil, and was pressed on a high-temperature press at a temperature of 340° C. to obtain a two-layer double-sided flexible copper clad laminate.

Comparative Example 7

First, a rolled copper foil with a thickness of 13 μm is provided, and the thermoplastic polyimide adhesive (Synthesis Example 12) obtained in the previous step is coated on the rough surface of the electrolytic copper foil with a thickness of 13 μm, and the coating The thickness is 4 μm, and it is dried with hot air at 160°C for 5 minutes to obtain the copper foil coated with adhesive;

Finally, the above-obtained adhesive-coated copper foil is bonded to a 25-micron PI film, and pressed on a high-temperature press at a temperature of 340° C. to obtain a two-layer double-sided flexible copper clad laminate.

Comparative Example 8

First, a rolled copper foil with a thickness of 13 μm is provided, and the thermoplastic polyimide adhesive (Synthesis Example 12) obtained in the previous step is coated on the rough surface of the electrolytic copper foil with a thickness of 13 μm, and the coating The thickness is 4 μm, and it is dried with hot air at 160°C for 5 minutes to obtain the copper foil coated with adhesive;

Finally, the adhesive-coated copper foil obtained above was bonded with a 50-micron PI film, and was pressed on a high-temperature press at a temperature of 340° C. to obtain a two-layer double-sided flexible copper clad laminate.

Comparative Example 9

First, a rolled copper foil with a thickness of 13 μm is provided, and the thermoplastic polyimide adhesive (Synthesis Example 13) obtained in the previous step is coated on the rough surface of the electrolytic copper foil with a thickness of 13 μm, and the coating The thickness is 4 μm, and it is dried by hot air at 160 °C for 5 minutes; then, it is treated in a high-temperature oven at 160 °C, 200 °C, 250 °C, 300 °C, and 320 °C for 10 minutes, respectively, to complete the imidization of the thermoplastic polyamic acid resin. adhesive copper foil;

Finally, the above-obtained adhesive-coated copper foil was bonded with a 75-micron PI film, and pressed on a high-temperature press at a temperature of 340° C. to obtain a two-layer double-sided flexible copper clad laminate.

The double-sided flexible copper clad laminates prepared in the above examples and comparative examples were tested, and various performance data were shown in the following table.

The test method of the above performance test is as follows:

Glass transition temperature test: use a dynamic thermomechanical analyzer (DMA2980, TA, USA); give a vibration frequency of 1 Hz, and heat up from room temperature to 400 °C at a heating rate of 3 °C/min in a nitrogen atmosphere. The glass transition temperature is obtained by measuring the maximum value of (Tanδ);

Thermal decomposition temperature (Td5%): use a thermogravimetric analyzer (TGA) to increase the temperature from room temperature to 800°C at a rate of 10°C/min, observe the weight change, and obtain the 5% weight reduction temperature;

Dimensional stability is tested according to: IPC-TM-650 method 2.2.4, where "+" means expansion and "-" means shrinkage;

Thermal expansion coefficient: using a thermomechanical analyzer (TMA), the polyimide sample used for testing is heated to 250 ° C in TMA, and after maintaining at this temperature for 10 minutes, with a cooling rate of 5 ° C/min, obtain 240 Coefficient of thermal expansion between °C and 100 °C;

Moisture absorption rate (RMA): 3 sheets of 40cm×20cm polyimide films were dried at 120°C for 2 hours and then placed in a constant temperature and humidity chamber of 23°C/50%RH for 24 hours or more. The weight change before and after is calculated by the following formula

RMA(%)=[(weight after moisture absorption-weight after drying)/weight after drying]×100%;

Flame retardancy: tested according to UL94 standard;

Peel strength: Peel strength: tested according to IPC-TM-650 2.4.9 method, peeling angle 90°, "T" means separation of copper foil and polyimide; "M" means thermoplastic polyimide and low dielectric polyimide The imide layer is separated.

In summary, the present invention relates to a thermoplastic polyimide adhesive for two-layer flexible copper clad laminates, which does not require thermal imidization in the production process. The imide adhesive can be directly laminated with copper foil or PI film after drying, thereby greatly simplifying the production process and improving the production efficiency; the two-layer flexible copper clad laminate prepared by the present invention is adhesively bonded with thermoplastic polyimide. Agent utilization: TPI has excellent heat resistance, high glass transition temperature, excellent copper foil adhesion and lamination, and the addition of epoxy resin significantly improves its adhesion to PI film. It is ensured that the final thermoplastic polyimide adhesive has high glass transition temperature, excellent heat resistance, aging resistance, flame retardancy and excellent bonding effect with PI film and copper foil. The production process of the thermoplastic polyimide adhesive prepared by the invention adopts chemical imidization, which can be directly used in the subsequent coating process without high temperature imidization, so the production efficiency is significantly improved and the production is greatly simplified process, saving production costs. Compared with the TPI composite film used in the double-sided flexible copper clad laminate in the prior art, the thermoplastic polyimide adhesive prepared by the invention has a simple and convenient production process for preparing the two-layer double-sided flexible copper clad laminate. , which can produce thick products that cannot be produced by traditional TPI composite films and coating methods.

The above are only preferred embodiments of the present invention. For those of ordinary skill in the art, various other corresponding changes and deformations can be made according to the technical solutions and technical ideas of the present invention, and all these changes and deformations are should belong to the scope of the claims of the present invention.

The present invention illustrates the detailed method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed method, that is, it does not mean that the present invention must rely on the above-mentioned detailed method to be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims (13)

1. a preparation method of thermoplastic polyimide adhesive for two-layer method flexible copper clad laminate, is characterized in that, according to mass percent, described thermoplastic polyimide adhesive is following component: Thermoplastic polyimide 80% to 95%; and Epoxy resin 5%～20%; The preparation method comprises the steps: (1) Synthesis of thermoplastic polyimide precursor; (2) chemically imidizing a thermoplastic polyimide precursor to obtain a thermoplastic polyimide; and (3) adding epoxy resin to obtain the thermoplastic polyimide adhesive, The thermoplastic polyimide precursor is polymerized from diamine monomer and dianhydride monomer, Wherein, the epoxy group of the epoxy resin and the uncyclized carboxyl group in the thermoplastic polyimide are cross-linked and cured. 2. the preparation method of thermoplastic polyimide adhesive as claimed in claim 1, is characterized in that, described epoxy resin is bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S Any one or a mixture of at least two of the epoxy resin, bisphenol AF type epoxy resin, biphenyl type epoxy resin or phenolic epoxy resin. 3 . The method for preparing a thermoplastic polyimide adhesive according to claim 1 , further comprising a solvent, and the solid content of the thermoplastic polyimide adhesive is 5wt% to 30wt%. 4 . 4. The preparation method of thermoplastic polyimide adhesive as claimed in claim 3, wherein the solvent is N,N-dimethylformamide, N,N-dimethylacetamide, two Any one or a mixture of at least two of methyl sulfoxide and N-methylpyrrolidone. 5. the preparation method of thermoplastic polyimide adhesive as claimed in claim 1, is characterized in that, described diamine monomer is

any one or a mixture of at least two. 6. the preparation method of thermoplastic polyimide adhesive as claimed in claim 1, is characterized in that, described dianhydride monomer is

any one or a mixture of at least two. 7. the preparation method of thermoplastic polyimide adhesive as claimed in claim 1, is characterized in that, the dehydrating agent that described chemical imidization adopts is acetic anhydride, and accelerator is pyridine, triethylamine or isoquinoline Any one or a mixture of at least two of them. 8. A two-layer method double-sided flexible copper clad laminate, comprising a PI composite film and a copper foil pressed onto the PI composite film, the PI composite film comprising a PI film and being coated on the PI film The thermoplastic polyimide adhesive prepared by the method for preparing the thermoplastic polyimide adhesive according to any one of claims 1 to 7. 9. A two-layer method double-sided flexible copper clad laminate, comprising an adhesive-coated copper foil and a PI film laminated on the adhesive-coated copper foil, the adhesive-coated copper foil comprising a copper foil A foil and a thermoplastic polyimide adhesive prepared by the method for preparing a thermoplastic polyimide adhesive according to any one of claims 1 to 7 coated on the copper foil. 10. A two-layer method double-sided flexible copper clad laminate, comprising at least two press-fit type glue-free single-sided boards that are pressed against each other, the press-fit type glue-free single-sided boards comprising glue-free single-sided boards and coated on A thermoplastic polyimide adhesive prepared by the method for preparing a thermoplastic polyimide adhesive according to any one of claims 1 to 7 on a non-adhesive single panel, wherein the non-adhesive single panel is made of copper foil and PI film, the thermoplastic polyimide adhesive is coated on the PI film. 11 . The two-layer double-sided flexible copper clad laminate according to claim 8 , wherein the PI film has a thickness of 12 to 125 μm. 12 . 12 . The two-layer double-sided flexible copper clad laminate according to claim 8 , wherein the thermoplastic polyimide adhesive has a coating thickness of 2 to 10 μm. 13 . 13 . The two-layer double-sided flexible copper clad laminate according to claim 8 , wherein the copper foil has a thickness of 9 to 70 μm. 14 .