Low-dielectric photosensitive polyimide resin as well as preparation method and application thereof

Abstract

The invention discloses low-dielectric photosensitive polyimide resin as well as a preparation method and application thereof. The invention discloses a low-dielectric photosensitive polyimide resin for a flexible copper-clad circuit board, and aims to provide the low-dielectric photosensitive polyimide resin for the flexible copper-clad circuit board, the polyimide resin provided by the invention has low dielectric constant and is more beneficial to reduction of electric energy loss, and the technical scheme is as follows: after a photosensitive monomer is copolymerized with dianhydride and diamine, the low-dielectric photosensitive resin is obtained through imidization; the chemical structural formula is # imgabs0 #, and belongs to the technical field of high polymer materials.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and specifically relates to a low-dielectric photosensitive polyimide resin that can be used for a flexible copper-clad circuit board. The invention also provides a preparation method and application of the low-dielectric photosensitive polyimide resin. Background Art

[0002] As an excellent engineering plastic, polyimide is widely used in many different scientific research fields due to its excellent high and low temperature stability, product dimensional stability, chemical stability, insulation performance and electrical properties. In recent years, with the rapid development of 5G, big data, artificial intelligence and other fields, higher requirements have been placed on the dielectric properties of semiconductor packaging materials. The high frequency and high speed of 5G communications require packaging materials to have excellent dielectric properties, while the dielectric constants of some common photosensitive polyimide materials are relatively high (usually greater than 3.0), which cannot meet the performance requirements of the new generation of communication technology for low dielectric constants. In addition, as the requirements of the electronic device industry for fine circuit boards gradually increase, low-dielectric photosensitive polyimide, as a new type of polyimide, has a lower dielectric constant than traditional polyimide, which improves the utilization rate of electric energy, resulting in an increase in demand in many electronic device fields.

[0003] The current methods for preparing low-dielectric photosensitive polyimide are divided into subtractive method and molecular structure design method. The subtractive method is to apply adhesive to the surface of the polymer substrate, calender and bond the copper foil, then apply photoresist on the copper foil, expose the circuit pattern with a mask, etch the exposed copper area with a solution, and remove the photoresist. However, due to the side etching phenomenon of chemically etched copper wires and the resolution restriction of the photosensitive layer, the fine structure of the metal circuit board will be greatly reduced, and due to its complex process, high cost, large metal energy consumption, high copper foil cost and easy pollution to the environment, it cannot be industrialized on a large scale. Compared with the subtractive method, the molecular structure design method refers to the preparation of low-dielectric photosensitive polyimide resin through reasonable molecular design. Compared with traditional polyimide, the low-dielectric photosensitive polyimide prepared by the molecular structure design method can significantly reduce its dielectric constant and improve the utilization rate of electric energy. Summary of the invention

[0004] In view of the above-mentioned shortcomings, the object of the present invention is to provide a low dielectric photosensitive polyimide resin that can be used for flexible copper-clad circuit boards. The polyimide resin provided by the present invention can reduce its dielectric constant to below 2.6 by introducing fluorine element only on the non-photosensitive diamine monomer. If fluorine element is introduced on the dianhydride monomer at the same time, its dielectric constant can be further reduced to below 1.5, which is more conducive to reducing power loss.

[0005] The second object of the present invention is to provide a method for preparing the above-mentioned low-dielectric photosensitive polyimide resin, which is simple, easy to industrialize, and does not require additional equipment.

[0006] The third object of the present invention is to provide a low dielectric photosensitive polyimide material, which presents a metal pattern on the exposed area of ​​the low dielectric photosensitive polyimide resin by chemical plating, has lower dielectric properties, is better used in flexible circuit boards, and reduces power loss.

[0007] To this end, the first technical solution provided by the present invention is as follows:

[0008] A low dielectric photosensitivity polyimide resin, the chemical structure of the polyimide resin is as follows:

[0009]

[0010] The number average molecular weight of the photosensitive polyimide is 2500-95000, the number average molecular weight of the photosensitive polyimide is 2500-95000, p is the number of component B is 2250-85500, n is a positive integer of 1-20, and m is the number of photosensitive monomers is 250-9500;

[0011] in:

[0012] The structural unit A is a tetrasubstituted, unsubstituted or fluorine-containing benzene ring structure;

[0013] The structural unit B is a benzene ring structure containing multiple fluorine elements;

[0014] The structural unit C is a benzene ring structure containing at least two hydroxyl groups.

[0015] The molar percentage of the photosensitive group in the polyimide main chain is 0.1% to 35%, and the polyimide main chain is connected to the specific photosensitive group through an ether bond via an alkane chain.

[0016] Furthermore, in the above-mentioned low dielectric photosensitive polyimide resin, the structural unit A is selected from one of the following structures:

[0018]

[0019] Furthermore, in the above-mentioned low dielectric photosensitive polyimide resin, the structural unit B is selected from one of the following structures:

[0021]

[0022] Furthermore, in the above-mentioned low dielectric photosensitive polyimide resin, the structural unit C is selected from one of the following structures:

[0024]

[0025] Where X = O, S,

[0026] Furthermore, in the above-mentioned low dielectric photosensitive polyimide resin, the photosensitive diamine monomer has the following chemical structure:

[0027]

[0028] Wherein X is a benzene ring structure containing at least two hydroxyl groups, connected to the photosensitive group via an alkane chain via an ether bond, and n is a positive integer of 1-20.

[0029] The second technical solution provided by the present invention is a method for preparing the above-mentioned low-dielectric photosensitive polyimide resin, which comprises the following steps:

[0030] (1) Under an inert environment, a diamine monomer having a structural unit B and a photosensitive diamine monomer having a structural unit C are added to a solvent, and then the dianhydride in the structural unit A is slowly added and stirred to dissolve, and then the reaction system is placed in a low-temperature water bath at -10 to 25° C. and stirred for reaction for 4 to 24 hours to obtain a low-dielectric photosensitive polyamic acid solution;

[0031] (2) placing the low dielectric photosensitive polyamic acid solution prepared in step (1) in an inert environment, maintaining it at 50-100° C. for 60-100 minutes, and maintaining it at 100-250° C. for 60-200 minutes, and heating it in stages to perform imidization, thereby obtaining a low dielectric photosensitive polyimide resin;

[0032] The molar ratio of diamine monomer with structural unit B: photosensitive diamine monomer with structural unit C: dianhydride with structural unit A is 0.1-9:0.1-1:1-11, and the total mass of dianhydride monomer and diamine monomer accounts for 3%-25% of the total mass of the reaction solution.

[0033] Furthermore, in the above-mentioned method for preparing low-dielectric photosensitive polyimide, the polar organic solvent is one or any combination of toluene, xylene, m-cresol, xylenol, N-methyl-2-pyrrolidone (NMP), N-vinyl-2-pyrrolidone, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), cyclopentanone, benzene or butyrolactone.

[0034] Another technical solution provided by the present invention is a low-dielectric photosensitive polyimide resin film material, which is prepared by using the low-dielectric photosensitive polyimide resin described in the first technical solution.

[0035] The present invention also provides a method for preparing the above-mentioned low-dielectric photosensitive polyimide resin film material, which comprises the following steps in sequence:

[0036] (1) uniformly coating the low dielectric photosensitive polyamic acid solution according to claim 1 on a glass sheet by a casting method to obtain a polyamic acid film;

[0037] (2) The polyamic acid film of step (1) is transferred to an oven, and kept at 50-100° C. for 60-100 minutes and 100-250° C. for 60-200 minutes under an inert environment, and heated in stages for imidization to obtain the low dielectric photosensitive polyimide film of claim 1.

[0038] The present invention also has a technical solution:

[0039] A method for making a conductive metal comprises the following steps in sequence:

[0040] (1) exposing the low dielectric photosensitive polyimide film to an ultraviolet light source with a wavelength of 100 to 400 nm for a period of 5 to 6000 seconds;

[0041] (2) After the exposure, the film is developed at 25 to 65° C. using a solution containing a chemical plating catalyst for 1 to 150 seconds, and then rinsed with an organic solvent and dried with cold air;

[0042] (3) then immersing the catalyst in an active solution containing a chemical activator or heating the catalyst for activation, and then immersing the catalyst in a chemical copper plating solution for chemical plating to obtain a low-dielectric photosensitive polyimide resin film with conductive copper metal fixed on the surface;

[0043] The organic solvent is one of methanol, ethanol, acetonitrile, N,N-dimethylformamide (DMF), and N,N-dimethylacetamide (DMAC);

[0044] The heating activation method is to place the photosensitive polyimide resin film after the display treatment into a vacuum oven, and in an inert environment, adopt a segmented heating method, first keep it at 50-100°C for 60-100 minutes, and then raise the temperature to 100-250°C and keep it for 60-200 minutes.

[0045] Compared with the prior art, the technical solution provided by the present invention has the following technical advantages:

[0046] 1. The low-dielectric photosensitive polyimide resin provided by the present invention can reduce its dielectric constant to below 2.6 when fluorine element is introduced into the non-photosensitive diamine monomer. If fluorine element is introduced into the dianhydride monomer at the same time, its dielectric constant can be further reduced to below 1.5, which is more conducive to reducing power loss.

[0047] 2. The low-dielectric photosensitive polyimide resin provided by the present invention can be used to prepare a polyimide film having low dielectric properties and good stability under different environments due to the fluorine-containing monomers; after the photosensitive polyimide film is exposed, the exposed area undergoes a photoinduced structural change, so that the exposed area combines with the chemical plating catalyst in the solution, and the chemical plating catalyst is selectively fixed on the surface of the photosensitive polyimide. After the catalyst layer is activated, a metal pattern can be presented in the exposed area of ​​the low-dielectric photosensitive polyimide by chemical plating, and at the same time, it has a lower dielectric constant performance, reduces power loss, and improves power utilization.

[0048] 3. The technical solution provided by the present invention prepares conductive metal on the surface of polyimide material through an addition method. It is simple and safe to operate, has low energy consumption and high raw material utilization rate, which is beneficial to the industry to reduce costs, and can optimize product performance on the basis of low dielectric properties, improve power utilization rate, and thus improve product competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a 50um observation picture of the low dielectric photosensitive polyimide of Example 5 under an optical microscope;

[0050] Figure 2 This is a 20um observation picture of the low dielectric photosensitive polyimide of Example 5 under an optical microscope;

[0051] Figure 3 This is a 200um observation picture of the low dielectric photosensitive polyimide of Comparative Example 1 under an optical microscope;

[0052] Figure 4 It is an impedance analyzer test analysis diagram of the low dielectric photosensitive polyimide of the embodiment. DETAILED DESCRIPTION

[0053] The present invention will be described in detail with reference to the following examples; however, the present invention is not limited to these embodiments.

[0054] Unless otherwise specified, the methods used in the following implementations are conventional methods; the raw materials and reagents used are raw materials and reagents that can be obtained from commercial channels unless otherwise specified.

[0055] Example 1

[0056] The present embodiment provides a low dielectric photosensitive polyimide resin, which is prepared by the following method: weigh 64.1g of 4,4'-diamino-2,2-bistrifluoromethylbiphenyl, add 94.93g of photosensitive diamine monomer into a reactor equipped with a stirrer, mix evenly, place the reactor in a 20°C water bath, add 2598.14g of N,N-dimethylacetamide into the reactor, stir for 10 minutes until the diamine monomer is completely dissolved, continue to add 235.22g of 3,3',4,4'-biphenyl dianhydride into the reaction solution, continue to stir and react for 10 hours, and obtain a low dielectric photosensitive polyamide acid solution; a preparation method for a low dielectric photosensitive polyimide resin.

[0057] The synthetic route for preparing the low dielectric photosensitive polyamic acid solution is as follows:

[0058]

[0059] The photosensitive diamine monomer is prepared by the following method:

[0060] 1.30g 3,3'-diamine-[1,1'-biphenyl]-4,4'-diol (Compound B), 50ml anhydrous THF and 5.99g Compound A were added to a two-necked flask, and 8.4g anhydrous potassium carbonate was added to the reaction bottle under stirring; under nitrogen protection, the reaction was heated for 15h; after the reaction was completed, the reaction solution was cooled to room temperature, the filtrate was dried after suction filtration, and the solid was recrystallized from ethanol to obtain a yellow solid photosensitive diamine monomer (Compound C)

[0061] The synthetic route for preparing the photosensitive diamine monomer is as follows:

[0062]

[0063]

[0064] Example 2

[0065] The present embodiment provides a low dielectric photosensitive polyimide resin, which is prepared by the following method: weigh 268.86g of diamine monomer 3,3'-di(trifluoromethyl)aniline, add 98.1g of photosensitive diamine monomer into a reactor equipped with a stirrer, mix well and place the reactor in a 10°C water bath, then add 3520.5g of N,N-dimethylacetamide into the reactor, stir for 10 minutes until the diamine monomer is completely dissolved, continue to add 133.2g of 4,4'-(hexafluoroisopropylene) diphthalic anhydride into the reaction solution, continue to stir and react for 10 hours, and obtain a low dielectric photosensitive polyamide acid solution;

[0066] The synthetic route for preparing the low dielectric photosensitive polyamic acid solution is as follows:

[0067]

[0068] The photosensitive diamine monomer is prepared by the following method:

[0069] 1.39g 2-amino-5-(4-amino-2-hydroxyphenoxy)phenol (compound B), 50ml anhydrous THF and 5.99g compound A were added to a two-necked flask, and 8.4g anhydrous potassium carbonate was added to the reaction bottle under stirring; under nitrogen protection, the reaction was heated for 15h; after the reaction was completed, the reaction solution was cooled to room temperature, the filtrate was dried after suction filtration, and the solid was recrystallized from ethanol to obtain a yellow solid photosensitive diamine monomer (compound C)

[0070] The synthetic route for preparing the photosensitive diamine monomer is as follows:

[0071]

[0072] Example 3

[0073] The present embodiment provides a low dielectric photosensitive polyimide resin, which is prepared by the following method: weigh 292.86g of 4,4'-diamino-2,2-bistrifluoromethylbiphenyl, add 96.4g of photosensitive diamine monomer into a reactor equipped with a stirrer, mix well, place the reactor in a 15°C water bath, add 3475.56g of N,N-dimethylacetamide into the reactor, stir for 10 minutes until the diamine monomer is completely dissolved, continue to add 104.3g of 5,5'-(propane-2,2-diylbis(4,1-phenylene)bis(oxy)bis(isobenzofuran-1,3-dione) into the reaction solution, continue stirring and reacting for 10 hours, and obtain a low dielectric photosensitive polyamide acid solution;

[0074] The synthetic route for preparing the low dielectric photosensitive polyamic acid solution is as follows:

[0075]

[0076] The photosensitive diamine monomer is prepared by the following method:

[0077] 1.30g 4,4'-diamino[1,1'-biphenyl]-3,3'-diol (Compound B), 50ml anhydrous THF and 5.99g Compound A were added to a two-necked flask, and 8.4g anhydrous potassium carbonate was added to the reaction bottle under stirring; under nitrogen protection, the reaction was heated for 15h; after the reaction was completed, the reaction solution was cooled to room temperature, the filtrate was dried after suction filtration, and the solid was recrystallized from ethanol to obtain a yellow solid photosensitive diamine monomer (Compound C)

[0078] The synthetic route for preparing the photosensitive diamine monomer is as follows:

[0079]

[0080] Example 4

[0081] This embodiment provides a low dielectric photosensitive polyimide resin and a method for preparing a conductive metal thereon, which is prepared by the following methods in sequence:

[0082] (1) At room temperature and in the dark, the polyamic acid solution prepared in Example 1 was filtered through a 0.22 mesh filter membrane to remove bubbles, and then uniformly cast on a glass sheet. The polyamic acid film was placed in a nitrogen environment, maintained at 60° C. for 100 minutes and 120° C. for 100 minutes, and heated in stages for imidization. The solvent was evaporated to obtain a 20 μm self-supporting photosensitive polyimide film with good properties;

[0083]

[0084] (2) The photosensitive polyamic acid film filtered and defoamed in step (1) was dried in a blast heating device at 70° C. for 5 h, and then sent to an ultraviolet exposure device capable of emitting a wavelength of 200 nm for exposure. The total exposure time was 1.2×10 2 s;

[0085] (3) Immersing the photosensitive polyamic acid film after exposure in step (2) in a developer at room temperature for 60 seconds, then rinsing with ethanol and drying with cold air. Subsequently, in a nitrogen atmosphere, first maintaining at 60° C. for 100 minutes, and then maintaining at 120° C. for 100 minutes, to obtain a photosensitive polyimide film with a Ag metal catalyst pattern on the surface;

[0086] Wherein: the developer is prepared by dissolving 50 g of silver nitrate in 1 liter of ethanol solvent and mixing evenly.

[0087] (4) Immersing the photosensitive polyimide film having a Ag metal catalyst pattern on its surface prepared in step (3) in a metal copper plating solution for chemical plating to obtain a polyimide resin film material having a specific conductive copper metal pattern on its surface.

[0088] The metal copper plating solution is obtained by uniformly mixing 10 g / L of copper sulfate pentahydrate aqueous solution, 15 g of potassium sodium tartrate, and 10 mL of formaldehyde, and the temperature of the chemical copper plating solution is 30°C.

[0089] Example 5

[0090] This embodiment provides a low dielectric photosensitive polyimide resin and a method for preparing a conductive metal thereon, which is prepared by the following methods in sequence:

[0091] (1) At room temperature and in the dark, the polyamic acid solution prepared in Example 2 was filtered through a 0.22 mesh filter membrane to remove bubbles, and then uniformly cast on a glass sheet. The glass sheet was placed in a blast heating device to evaporate the solvent at 60° C. for 5 h. The polyamic acid film was placed in a nitrogen environment and maintained at 60° C. for 100 min and 150° C. for 100 min. The film was imidized by heating in stages, and the solvent was evaporated to obtain a 20 μm self-supporting photosensitive polyimide film with good properties.

[0092]

[0093] (2) The photosensitive polyamic acid film filtered and defoamed in step (1) was dried at 60° C. for 5 h in a blast heating device, and then sent to an ultraviolet exposure device with an emission wavelength of 200 nm for exposure. The total exposure time was 1.2×10 2 s;

[0094] (3) Immersing the photosensitive polyamic acid film after exposure in step (2) in a developer at room temperature for 60 seconds, then rinsing with methanol and drying with cold air. Subsequently, in a nitrogen atmosphere, first maintaining at 60° C. for 100 minutes, then maintaining at 150° C. for 100 minutes, heating in stages for imidization, and obtaining a photosensitive polyimide film having a palladium metal catalyst pattern on the surface;

[0095] Wherein: the developer is prepared by dissolving 0.5 g of palladium chloride in 1 L of methanol solvent and mixing evenly.

[0096] (4) Immersing the photosensitive polyimide film having a palladium metal catalyst pattern on the surface prepared in step (3) in a metal copper plating solution for chemical plating to obtain a polyimide resin film material having a specific conductive metal copper pattern on the surface.

[0097] The metal copper plating solution is obtained by uniformly mixing 10 g / L of copper sulfate pentahydrate aqueous solution, 15 g of potassium sodium tartrate, and 10 mL of formaldehyde, and the temperature of the chemical copper plating solution is 30°C.

[0098] Example 6

[0099] This embodiment provides a low dielectric photosensitive polyimide resin and a method for preparing a conductive metal thereon, which is prepared by the following methods in sequence:

[0100] (1) At room temperature and in the dark, the polyamic acid solution prepared in Example 3 was filtered through a 0.22 mesh filter membrane to remove bubbles, and then uniformly cast on a glass sheet. The glass sheet was placed in a blast heating device and the solvent was evaporated at 70° C. for 5 h. The polyamic acid film was placed in an inert environment and maintained at 70° C. for 100 min and 210° C. for 100 min. The polyamic acid film was imidized by heating in stages. The solvent was evaporated to obtain a 20 μm self-supporting photosensitive polyimide film with good properties.

[0101]

[0102] (2) The photosensitive polyamic acid film filtered and defoamed in step (1) was dried in a blast heating device at 70° C. for 5 h, and then sent to an ultraviolet exposure device capable of emitting a wavelength of 200 nm for exposure. The total exposure time was 1.2×10 2 s;

[0103] (3) Immersing the photosensitive polyamic acid film after exposure in step (2) in a developer at room temperature for 60 seconds, then rinsing with ethanol and drying with cold air. Subsequently, in a nitrogen atmosphere, first maintaining at 70° C. for 100 minutes, then maintaining at 210° C. for 100 minutes, heating in stages for imidization, and obtaining a photosensitive polyimide film having a palladium metal catalyst pattern on the surface;

[0104] Wherein: the developer is prepared by dissolving 0.5 g of palladium chloride in 1 L of methanol solvent and mixing evenly.

[0105] (4) Immersing the photosensitive polyimide film having a palladium metal catalyst pattern on the surface prepared in step (3) in a metal copper plating solution for chemical plating to obtain a polyimide resin film material having a specific conductive copper metal pattern on the surface.

[0106] The metal copper plating solution is obtained by uniformly mixing 10 g / L of copper sulfate pentahydrate aqueous solution, 15 g of potassium sodium tartrate, and 10 mL of formaldehyde, and the temperature of the chemical copper plating solution is 30°C.

[0107] Comparative Example 1

[0108] This embodiment provides a low dielectric photosensitive polyimide resin and a method for preparing a conductive metal thereon, which is prepared by the following method:

[0109] (1) 292.86 g of diamine monomer 4,4'-diamino-2,2-bis(trifluoromethyl)biphenyl and 96.5 g of photosensitive diamine monomer were added to a reactor equipped with a stirrer, and after being mixed evenly, the reactor was placed in a 15° C. water bath, and 3746.1 g of N,N-dimethylacetamide was added to the reactor, and stirred for 10 minutes until the diamine monomer was completely dissolved, and 134.1 g of dianhydride monomer 2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diylbis(3,4-dimethylbenzoate) was added to the reaction solution, and the reaction was continued by stirring for 10 hours to obtain a low dielectric photosensitive polyamic acid solution;

[0110]

[0111] The photosensitive diamine monomer is prepared by the following method:

[0112] 1.30g 4,4'-diamino[1,1'-biphenyl]-3,3'-diol (Compound B), 50ml anhydrous THF and 5.99g Compound A were added to a two-necked flask, and 8.4g anhydrous potassium carbonate was added to the reaction bottle under stirring; under nitrogen protection, the reaction was heated for 15h; after the reaction was completed, the reaction solution was cooled to room temperature, the filtrate was dried after suction filtration, and the solid was recrystallized from ethanol to obtain a yellow solid photosensitive diamine monomer (Compound C)

[0113] The synthetic route for preparing the photosensitive diamine monomer is as follows:

[0114]

[0115] (2) At room temperature and in the dark, the polyamic acid solution prepared in step (1) is filtered through a 0.22 mesh filter membrane to defoam, and then uniformly cast on a glass sheet, which is placed in a blast heating device to evaporate the solvent at 70° C. for 5 hours. The polyamic acid film is placed in an inert environment, maintained at 70° C. for 100 minutes and 210° C. for 100 minutes, and is heated in stages for imidization. The solvent is evaporated to obtain a 20 μm self-supporting photosensitive polyimide film with good properties.

[0116]

[0117] (3) Immersing the photosensitive polyimide film exposed in step (2) in a developer at room temperature for 60 seconds, then rinsing with ethanol and drying with cold air. Subsequently, in a nitrogen atmosphere, first maintaining at 70° C. for 100 minutes, then maintaining at 210° C. for 100 minutes, and heating in stages for imidization to obtain a photosensitive polyimide film having a palladium metal catalyst pattern on the surface;

[0118] Wherein: the developer is prepared by dissolving 0.5 g of palladium chloride in 1 L of methanol solvent and mixing evenly.

[0119] (4) Immersing the photosensitive polyimide film having a palladium metal catalyst pattern on the surface prepared in step (3) in a metal copper plating solution for chemical plating to obtain a polyimide resin film material having a specific conductive copper metal pattern on the surface.

[0120] The metal copper plating solution is obtained by uniformly mixing 10 g / L of copper sulfate pentahydrate aqueous solution, 15 g of potassium sodium tartrate, and 10 mL of formaldehyde, and the temperature of the chemical copper plating solution is 30°C.

[0121] The low dielectric photosensitive polyimide resin film obtained in Example 5 is observed under an optical microscope. Figure 1 , Figure 2 The low dielectric photosensitive polyimide resin film obtained in Comparative Example 1 is observed under an optical microscope. Figure 3 As shown. Under room temperature, the low dielectric photosensitive polyimide resin flexible copper-clad circuit board was observed under an optical microscope. It can be seen that after copper plating, the circuit resolution is improved and the edge is clear. This embodiment successfully prepared a low dielectric photosensitive polyimide resin film.

[0122] At room temperature, a thin impedance analyzer test analysis chart was performed on the low dielectric photosensitive polyimide resin films prepared in Example 6, Example 4, Example 5, and Comparative Example 1. The test sample had a film thickness of 10 um and a length and width of 2 cm x 2 cm.

[0123] Test results such as Figure 4 At 1mHz, the dielectric constant of Example 6 is 2.6, the dielectric constant of Comparative Example 1 is 1.5, the dielectric constant of Example 4 is 2.1, and the dielectric constant of Example 5 is 1.7. It can be seen that under the same diamine fluorine-containing monomer and the same photosensitive diamine monomer, the introduction of fluorine elements into the dianhydride monomer can further significantly reduce the dielectric constant, and the film has been double-sided gold spraying before testing.

Claims

1. A low dielectric photosensitive polyimide resin, characterized in that: The chemical structural formula of the polyimide resin is as follows: The number average molecular weight of the photosensitive polyimide is 2500-95000, the number average molecular weight of the photosensitive polyimide is 2500-95000, p is the number of component B is 2250-85500, n is a positive integer of 1-20, and m is the number of photosensitive monomers is 250-9500; in: The structural unit A is a tetrasubstituted, unsubstituted or fluorine-containing benzene ring structure; The structural unit B is a benzene ring structure containing multiple fluorine elements; The structural unit C is a benzene ring structure containing at least two hydroxyl groups. The molar percentage of the photosensitive group in the polyimide main chain is 0.1% to 35%, and the polyimide main chain is connected to the specific photosensitive group through an ether bond via an alkane chain.

2. The low dielectric photosensitive polyimide resin according to claim 1, characterized in that: The structural unit A is selected from one of the following structures:

3. The low dielectric photosensitive polyimide resin according to claim 1, characterized in that: The structural unit B is selected from one of the following structures:

4. The low dielectric photosensitive polyimide resin according to claim 1, characterized in that: The structural unit C is selected from one of the following structures: Where X = O, S, 5. The low dielectric photosensitive polyimide according to claim 1, characterized in that: The photosensitive diamine monomer has the following chemical structure: Wherein X is a benzene ring structure containing at least two hydroxyl groups, connected to the photosensitive group via an alkane chain via an ether bond, and n is a positive integer of 1-20.

6. A method for preparing the low dielectric photosensitive polyimide resin according to claim 1, characterized in that: The steps are as follows: (1) Under an inert environment, a diamine monomer having a structural unit B and a photosensitive diamine monomer having a structural unit C are added to a solvent, and then the dianhydride in the structural unit A is slowly added and stirred to dissolve, and then the reaction system is placed in a low-temperature water bath at -10 to 25° C. and stirred for reaction for 4 to 24 hours to obtain a low-dielectric photosensitive polyamic acid solution; (2) placing the low dielectric photosensitive polyamic acid solution prepared in step (1) in an inert environment, maintaining it at 50-100° C. for 60-100 minutes, and maintaining it at 100-250° C. for 60-200 minutes, and heating it in stages to perform imidization, thereby obtaining a low dielectric photosensitive polyimide resin; The molar ratio of diamine monomer with structural unit B: photosensitive diamine monomer with structural unit C: dianhydride with structural unit A is 0.1-9:0.1-1:1-11, and the total mass of dianhydride monomer and diamine monomer accounts for 3%-25% of the total mass of the reaction solution.

7. The method for preparing low dielectric photosensitive polyimide according to claim 6, characterized in that: The polar organic solvent is one or any combination of toluene, xylene, m-cresol, xylenol, N-methyl-2-pyrrolidone (NMP), N-vinyl-2-pyrrolidone, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), cyclopentanone, benzene or butyrolactone.

8. A low dielectric photosensitive polyimide resin film material, characterized in that: It is prepared by using the low dielectric photosensitive polyimide resin described in claim 1.

9. The method for preparing a low dielectric photosensitive polyimide resin film material according to claim 8, characterized in that: The steps are as follows: (1) uniformly coating the low dielectric photosensitive polyamic acid solution according to claim 1 on a glass sheet by a casting method to obtain a polyamic acid film; (2) The polyamic acid film of step (1) is transferred to an oven, and kept at 50-100° C. for 60-100 minutes and 100-250° C. for 60-200 minutes under an inert environment, and heated in stages for imidization to obtain the low dielectric photosensitive polyimide film of claim 1.

10. A method for making a conductive metal, characterized in that: The steps are as follows: (1) exposing the low dielectric photosensitive polyimide film of claim 8 to an ultraviolet light source with a wavelength of 100 to 400 nm for a period of 5 to 6000 seconds; (2) After the exposure, the film is developed at 25 to 65° C. using a solution containing a chemical plating catalyst for 1 to 150 seconds, and then rinsed with an organic solvent and dried with cold air; (3) then immersing the catalyst in an active solution containing a chemical activator or heating the catalyst for activation, and then immersing the catalyst in a chemical copper plating solution for chemical plating to obtain a low-dielectric photosensitive polyimide resin film with conductive copper metal fixed on the surface; The organic solvent is one of methanol, ethanol, acetonitrile, N,N-dimethylformamide (DMF), and N,N-dimethylacetamide (DMAC); The heating activation method is to put the photosensitive polyimide resin film after the display treatment into a vacuum oven, and in an inert environment, use a segmented heating method, first keep it at 50-100°C for 60-100 minutes, and then heat it to 100-250°C and keep it for 60-200 minutes.

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