A functional back adhesive copper foil material, a preparation method and application thereof

Abstract

The application discloses a functional back adhesive copper foil material and a preparation method and application thereof, and belongs to the technical field of functional back adhesive copper foil material preparation. After pre-stirring of epoxy resin and polyimide, functional additives composed of nano-silicon dioxide, phosphate compounds, phenolic derivatives and hindered phenolic anti-aging agents and mixed solvents are added, and resin slurry is obtained through ultrasonic oscillation assisted high-speed dispersion; the resin slurry is coated on a rough surface of an electrolytic copper foil through a slit coating process, and the semi-cured degree is controlled through segmented temperature rising and drying, and the product is obtained after lamination of a PET protective film and winding. The material prepared by the application has excellent performance, solves the pain points of low size precision and no imaging function of the existing PP material, the preparation process is compatible with the existing equipment, automatic production can be realized, is suitable for high-density packaging carrier board layer increasing, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of preparation technology of functional adhesive-backed copper foil materials, specifically relating to a functional adhesive-backed copper foil material, its preparation method, and its application. Background Technology

[0002] With the trend towards smaller, thinner, and more multifunctional electronic products, the number of input / output (I / O) points in integrated circuits (ICs) has increased significantly, driving a surge in demand for the density of connection points on the carrier boards and fan-out packages that support the chips. When the two-dimensional planar wiring density reaches its manufacturing limit, three-dimensional structural design has become mainstream, and multi-layer high-density stacking technology is the core of realizing this design. It requires fanning out the chip's functional contacts to the motherboard (PCB) to ensure the functionality of the circuit system.

[0003] The current mainstream add-on technologies in the carrier board and fan-out packaging fields have obvious defects. First, the use of prepreg (PP) film with traditional lamination equipment is difficult to automate due to the sheet-like nature of PP, which needs to be laminated with sheet-like copper materials. The lamination uniformity is poor, the expansion and contraction of the material after solidification is difficult to control, and the dimensional accuracy and yield of high-multilayer stacks are low. Second, although the use of Japanese Ajinomoto ABF film with Japanese Morton vacuum lamination machine can achieve automated production and has excellent convenience for high-multilayer stacks, and the mainstream +3 to +6 layer application accounts for 95%, ABF is an exclusive patented product, forming a technological monopoly that is difficult for other manufacturers to replace.

[0004] Meanwhile, existing materials cannot meet the high-performance requirements. ABF (Adhesive-Backed Copper Foil) requires storage and transportation at -18°C and lacks imaging capabilities. Conventional adhesive-backed copper foil (RCC) and insulating materials are insufficient in terms of coefficient of thermal expansion (CTE), high-temperature stability (Tg), dielectric properties (Dk, Df), and workability, making them unsuitable for the stringent material requirements of high-density packaging substrate overlays. Furthermore, issues such as alignment deviations in multilayer overlays and reliance on destructive testing for reliability testing further restrict technological development. Therefore, developing a high-performance, easily prepared adhesive-backed copper foil material suitable for high-density packaging and its preparation method has become crucial to overcoming existing technological bottlenecks. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a functional adhesive-backed copper foil material.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: including, Epoxy resin and polyimide were added to a mixing tank for pre-stirring, and then functional additives and solvents were added. The mixture was then dispersed at high speed under ultrasonic vibration to obtain a uniform resin slurry. The functional additives are composed of nano-silica, tricresyl phosphate, p-tert-butylphenol, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. One side of the electrolytic copper foil is subjected to degreasing, acidification, and passivation pretreatment in sequence to obtain an electrolytic copper foil with one rough side and one smooth side. First, a nickel-chromium alloy is sputtered and deposited on the rough surface of the electrolytic copper foil as a transition layer. Then, the resin slurry is uniformly coated on the transition layer and processed by a segmented heating and drying process. After drying, the semi-cured adhesive copper foil is cooled to room temperature, and a PET protective film is bonded to the surface of the resin layer by a hot-pressing composite process. After winding, the functional adhesive copper foil material is obtained. In a preferred embodiment of the preparation method of the functional adhesive-backed copper foil material of the present invention, the resin slurry comprises, by mass percentage, the following components: 40%~60% high molecular weight epoxy resin, 5%~30% polyimide, 3%~8% functional additives and 15%~35% solvent; The high molecular weight epoxy resin includes bisphenol A type epoxy resin or phenolic epoxy resin, with an epoxy value of 0.4 eq / 100g to 0.6 eq / 100g; the polyimide has a number average molecular weight of 10,000 to 30,000 and a glass transition temperature (Tg) > 220℃. The functional additive is composed of nano-silica, tricresyl phosphate, p-tert-butylphenol, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] in a mass ratio of 2:1:1:0.5 to 3:1:1:1. The solvent is a mixture of propylene glycol methyl ether acetate and xylene in a mass ratio of 3:1 to 5:1.

[0009] As a preferred embodiment of the preparation method of the functional adhesive copper foil material of the present invention, the high-speed dispersion under ultrasonic oscillation assistance is to disperse at a high speed of 120 min to 180 min at an ultrasonic oscillation frequency of 20 kHz to 40 kHz and a rotation speed of 1200 r / min to 1800 r / min at an ultrasonic oscillation frequency of 50 ℃ to 60 ℃ for 20 kHz to 40 kHz for 120 min to 180 min.

[0010] In a preferred embodiment of the preparation method of the functional adhesive-backed copper foil material of the present invention, the surface roughness of the pretreated copper foil is Ra=0.1~0.3μm.

[0011] As a preferred embodiment of the preparation method of the functional adhesive copper foil material of the present invention, the transition layer is prepared by sputtering deposition process, with a sputtering power of 100~300W, a deposition time of 5~15min, and the thickness of the transition layer is controlled at 0.5~2μm.

[0012] As a preferred embodiment of the preparation method of the functional adhesive copper foil material of the present invention, the coating speed is 0.5m / min to 5m / min, the coating thickness is controlled at 5um to 100um, the coating uniformity is monitored in real time by online detection during the coating process, and the coating is pre-dried at 60 to 80°C for 3 to 5 minutes after coating.

[0013] In a preferred embodiment of the preparation method of the functional adhesive-backed copper foil material of the present invention, the segmented heating and drying process comprises: a first stage temperature of 60℃~80℃ and a drying time of 15min~25min; a second stage temperature of 80℃~100℃ and a drying time of 20min~30min; and a third stage temperature of 100℃~120℃ and a drying time of 10min~20min. The degree of semi-curing of the resin layer after drying satisfies the following requirements: solvent residue of 0.1%~0.2% and semi-cured viscosity curve variability <1%.

[0014] As a preferred embodiment of the preparation method of the functional adhesive copper foil material of the present invention, the hot pressing temperature of the hot pressing composite process is 80~120℃, the hot pressing pressure is 0.3~1.5MPa, and the hot pressing time is 10s~300s.

[0015] Another object of the present invention is to provide a functional adhesive-backed copper foil material, said functional adhesive-backed copper foil material having the following characteristics, (i) Tg(DMA) > 180℃; (ii) Dk(1G~10GHz)<3.3, Df(1G~10GHz)<0.006; (iii) Td (pyrolysis temperature) > 400℃; (iv) Moisture absorption rate <0.6%; (v) Imaging time < 60 seconds; (vi) The thermal expansion coefficient of the XY axis (α1beforeTg) is <30ppm, the thermal expansion coefficient of the XY axis (α2afterTg) is <70ppm, the thermal expansion coefficient of the Z axis (α1beforeTg) is <40ppm, and the thermal expansion coefficient of the Z axis (CTE) (α2afterTg) is <100ppm, where α1beforeTg represents the thermal expansion coefficient of the corresponding axis before the glass transition temperature, and α2afterTg represents the thermal expansion coefficient of the corresponding axis after the glass transition temperature.

[0016] Another object of the present invention is to provide a functional adhesive copper foil material as an additive layer for high-density encapsulation substrates.

[0017] Beneficial effects of this invention: (1) This invention innovatively designs a functional additive compound system and optimizes the addition method to achieve multiple performance synergistic improvement. Among them, nano silica forms a dense interface layer with resin to achieve low dielectric properties. Hindered phenolic anti-aging agents capture free radicals, inhibit resin oxidative degradation, stabilize the interface between the two, and avoid dielectric drift. Phosphate ester compounds precisely regulate the resin crosslinking rate, avoid stress concentration and interface cracking during curing, and provide uniformly dispersed structural support for nano silica and hindered phenols. Their thermal stability can also protect the hindered phenols from maintaining activity during high-temperature drying. Phenolic derivatives undergo a controllable neutralization reaction with alkaline developer through monophenolic hydroxyl groups to achieve rapid development. The uniform crosslinking network constructed by phosphate esters ensures uniform development of resin layers of different thicknesses, avoids excessive dissolution or residue, and the components have excellent compatibility and complementary functions to form a highly efficient synergistic effect.

[0018] (2) By using a segmented heating and drying process to precisely control the degree of resin semi-curing, and combining it with ultrasonic-assisted dispersion technology to break the agglomeration of raw materials, the material has excellent dimensional stability and high temperature stability, effectively reducing the alignment deviation during multi-layer layering, and solving the problems of poor uniformity of existing PP materials, low dimensional accuracy, and insufficient high temperature stability of ABF materials.

[0019] (3) The preparation process of the present invention is the result of multi-stage synergistic optimization. Each step is designed for specific performance pain points. Pretreatment solves the interface bonding, transition layer strengthens synergy, and pre-drying controls semi-curing. None of these steps can be omitted.

[0020] (4) The preparation process of the present invention is compatible with existing coating equipment, can realize automated production, and improves production efficiency by 30%~50% compared with PP material. While significantly reducing material cost, it also has imaging function, requires no additional processing steps, and significantly reduces the production cost of high-density packaging substrate. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a process flow diagram for preparing the functional adhesive-backed copper foil material of the present invention. Detailed Implementation

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0023] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0024] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0025] Unless otherwise specified, all raw materials used in this invention are commercially available in the field.

[0026] The method for determining the material properties of this invention is as follows: The glass transition temperature (Tg, DMA) of the material was determined using a dynamic mechanical analyzer with a heating rate of 10℃ / min, a test temperature range of 30℃~300℃, a frequency of 1Hz, and a tensile mode. The temperature Tg corresponding to the sudden change in storage modulus was taken. Dielectric constant (Dk) and dielectric loss (Df) were determined using a dielectric spectrum analyzer. The test frequency was 1 GHz to 10 GHz, the test temperature was 25 ℃, the relative humidity was 50%, and the sample size was 50 mm × 50 mm. The pyrolysis temperature (Td) was determined using a thermogravimetric analyzer at a heating rate of 10℃ / min, in a nitrogen atmosphere (flow rate of 50mL / min), and in a temperature range of 30℃ to 600℃. The temperature at which the mass loss was 5% was taken as Td. The method for determining the moisture absorption rate is as follows: cut the sample into 20mm×20mm pieces, dry them at 105℃ for 2 hours, cool them to room temperature and weigh them (m0), then place them in a constant temperature and humidity chamber at 85℃ and 85% relative humidity for 1000 hours, remove them, wipe off the surface moisture and weigh them (m1). Moisture absorption rate = (m1-m0) / m0×100%; The method for measuring the development time is as follows: the sample is attached to the substrate, coated with photoresist, exposed, and then immersed in sodium carbonate developer (concentration 1%) at 25°C. The time from immersion to complete development (no residue) is recorded. The coefficient of thermal expansion (CTE) was determined using a thermomechanical analyzer with a heating rate of 5℃ / min and a test temperature range of 30℃~250℃. The coefficients of thermal expansion along the XY and Z axes were measured before Tg (α1) and after Tg (α2), respectively. The sample sizes were 4mm×4mm (Z-axis) and 20mm×4mm (XY-axis). Solvent residue was determined by gas chromatography. After crushing the sample, 1g was weighed and placed in a thermal desorption device. Desorption was performed at 200℃ for 30min. The solvent residue was quantitatively calculated by the chromatographic peak area. The variability of the semi-cured viscosity curve was determined using a rotational rheometer at a temperature of 80℃, a frequency of 1Hz, and a test time of 60min. The viscosity change curve over time was recorded, and the coefficient of variation of the curve was calculated (standard deviation / mean value × 100%). A tensile testing machine was used with a peeling speed of 50 mm / min and a test temperature of 25℃. The sample size was 100 mm × 25 mm. The maximum force value during the peeling process was recorded, and the peel strength (N / mm) was calculated. Example 1: This embodiment provides a method for preparing a functional adhesive-backed copper foil material, specifically: 1) Weigh the raw materials according to the following mass fractions: 60% bisphenol A type epoxy resin (epoxy value 0.55 eq / 100g), 5% polyimide (number average molecular weight 30000, Tg=250℃), 8% functional additives (nano silica: tricresyl phosphate: p-tert-butylphenol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] = 3:1:1:1), 27% solvent (propylene glycol methyl ether acetate: xylene mass ratio = 5:1); 2) Add epoxy resin and polyimide to a mixing tank and pre-stir for 30 min at 40℃ and 800 r / min. Add functional additives and solvent, heat to 50℃, and disperse at 1800 r / min for 120 min under ultrasonic oscillation frequency of 40 kHz to obtain a uniform resin slurry. 3) One side of the electrolytic copper foil is subjected to degreasing, acidification, and passivation pretreatment in sequence; The degreasing treatment involves spraying a degreasing solution consisting of 3% sodium hydroxide, 2% sodium carbonate, 1% surfactant (fatty alcohol polyoxyethylene ether), and the remainder being deionized water, with a pH value of 12, onto one side of the copper foil. After spraying, the solution is left to stand at 50°C for 5 minutes and then rinsed with deionized water until the pH value reaches 7. The acidification treatment involves spraying an 8% sulfuric acid solution onto the degreased copper foil surface, allowing it to stand at 30°C for 2 minutes after spraying, and then rinsing it with deionized water until the pH reaches 7. The passivation treatment involves spraying a passivation solution composed of 1% CrO3, 0.2% sulfuric acid, 0.1% nitric acid, and the remainder deionized water onto the surface of the acidified copper foil. After spraying, the surface is left to stand at 25°C for 2 minutes, rinsed with deionized water until no chromium ions remain, and then dried at 70°C for 10 minutes to remove surface moisture. After passivation, an electrolytic copper foil with one rough side and one smooth side is obtained, with a roughness Ra=0.1μm on the rough side. 4) First, a nickel-chromium alloy is sputtered and deposited as a transition layer on the rough surface of the electrolytic copper foil. The sputtering power is 200W, the deposition time is 20min, and the thickness of the transition layer is controlled at 1μm. The electrolytic copper foil is fixed to the unwinding mechanism of the coating machine. The resin slurry is uniformly coated on the transition layer of the electrolytic copper foil using a slit coating process. The coating speed is 0.5m / min and the coating thickness is 5μm. The uniformity is monitored online during the coating process. After coating, the foil is pre-dried at 70℃ for 4min. 5) The coated copper foil is placed in a precision oven and dried using a segmented heating and drying process: the first stage is drying at 60℃ for 25 minutes, the second stage is drying at 90℃ for 30 minutes, and the third stage is drying at 120℃ for 20 minutes. After drying, the residual solvent content of the resin layer is 0.2%, and the variability of the semi-cured viscosity curve is 0.8%. 6) After cooling to room temperature, the PET protective film is bonded to the surface of the resin layer by hot pressing. The hot pressing temperature is 90℃, the pressure is 0.5MPa, and the time is 20s. The functional adhesive copper foil material is then obtained by winding.

[0027] Example 2: 1) Weigh the raw materials according to the following mass fractions: 50% bisphenol A type epoxy resin (epoxy value 0.55 eq / 100g), 20% polyimide (number average molecular weight 30000, Tg=250℃), 5% functional additives (nano silica: tricresyl phosphate: p-tert-butylphenol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] = 2.5:1:1:1), 25% solvent (propylene glycol methyl ether acetate: xylene mass ratio = 4:1); 2) Add epoxy resin and polyimide to a mixing tank and pre-stir for 30 min at 40℃ and 800 r / min. Add functional additives and solvent, heat to 50℃, and disperse at 1800 r / min for 120 min under ultrasonic oscillation frequency of 40 kHz to obtain a uniform resin slurry. 3) One side of the electrolytic copper foil is subjected to degreasing, acidification, and passivation pretreatment in sequence; The degreasing treatment involves spraying a degreasing solution consisting of 3% sodium hydroxide, 2% sodium carbonate, 1% surfactant (fatty alcohol polyoxyethylene ether), and the remainder being deionized water, with a pH value of 12, onto one side of the copper foil. After spraying, the solution is left to stand at 50°C for 5 minutes and then rinsed with deionized water until the pH value reaches 7. The acidification treatment involves spraying an 8% sulfuric acid solution onto the degreased copper foil surface, allowing it to stand at 30°C for 2 minutes after spraying, and then rinsing it with deionized water until the pH reaches 7. The passivation treatment involves spraying a passivation solution composed of 1% CrO3, 0.2% sulfuric acid, 0.1% nitric acid, and the remainder deionized water onto the surface of the acidified copper foil. After spraying, the surface is left to stand at 25°C for 2 minutes, rinsed with deionized water until no chromium ions remain, and then dried at 70°C for 10 minutes to remove surface moisture. After passivation, an electrolytic copper foil with one rough side and one smooth side is obtained, with a roughness Ra=0.1μm on the rough side. 4) First, a nickel-chromium alloy is sputtered and deposited as a transition layer on the rough surface of the electrolytic copper foil. The sputtering power is 200W, the deposition time is 20min, and the thickness of the transition layer is controlled at 1μm. The electrolytic copper foil is fixed to the unwinding mechanism of the coating machine. The slit coating process is adopted, the coating speed is 2m / min, and the coating thickness is 50μm. The uniformity is monitored online during the coating process. After the coating is completed, it is pre-dried at 60℃ for 5min. 5) The coated copper foil is sent into a precision oven and a segmented heating and drying process is adopted. The first stage is dried at 70℃ for 20 minutes, the second stage is dried at 100℃ for 25 minutes, and the third stage is dried at 120℃ for 15 minutes. After drying, the solvent residue of the resin layer is 0.15%, and the variability of the semi-cured viscosity curve is 0.6%.

[0028] The remaining steps and processes are the same as in Example 1, thus obtaining the functional adhesive copper foil material of this example.

[0029] Example 3: 1) Weigh the raw materials according to the following mass fractions: 60% bisphenol A type epoxy resin (epoxy value 0.55 eq / 100g), 5% polyimide (number average molecular weight 30000, Tg=250℃), 8% functional additives (nano silica: tricresyl phosphate: p-tert-butylphenol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] = 3:1:1:0.8), 27% solvent (propylene glycol methyl ether acetate: xylene mass ratio = 5:1); 2) Add epoxy resin and polyimide to a mixing tank and pre-stir for 30 min at 40℃ and 800 r / min. Add functional additives and solvent, heat to 50℃, and disperse at 1800 r / min for 120 min under ultrasonic oscillation frequency of 40 kHz to obtain a uniform resin slurry. 3) One side of the electrolytic copper foil is subjected to degreasing, acidification, and passivation pretreatment in sequence; The degreasing treatment involves spraying a degreasing solution consisting of 3% sodium hydroxide, 2% sodium carbonate, 1% surfactant (fatty alcohol polyoxyethylene ether), and the remainder being deionized water, with a pH value of 12, onto one side of the copper foil. After spraying, the solution is left to stand at 50°C for 5 minutes and then rinsed with deionized water until the pH value reaches 7. The acidification treatment involves spraying an 8% sulfuric acid solution onto the degreased copper foil surface, allowing it to stand at 30°C for 2 minutes after spraying, and then rinsing it with deionized water until the pH reaches 7. The passivation treatment involves spraying a passivation solution composed of 1% CrO3, 0.2% sulfuric acid, 0.1% nitric acid, and the remainder deionized water onto the surface of the acidified copper foil. After spraying, the surface is left to stand at 25°C for 2 minutes, rinsed with deionized water until no chromium ions remain, and then dried at 70°C for 10 minutes to remove surface moisture. After passivation, an electrolytic copper foil with one rough side and one smooth side is obtained, with a roughness Ra=0.1μm on the rough side. 4) First, a nickel-chromium alloy is sputtered and deposited as a transition layer on the rough surface of the electrolytic copper foil. The sputtering power is 200W and the deposition time is 20min. The electrolytic copper foil is fixed on the unwinding mechanism of the coating machine. The resin slurry is uniformly coated on the transition layer of the electrolytic copper foil using a slot coating process. The coating speed is 0.5m / min and the coating thickness is 5μm. The uniformity is monitored online during the coating process. After the coating is completed, it is pre-dried at 70℃ for 4min. 5) The coated copper foil is sent into a precision oven and a segmented heating and drying process is adopted. The first stage is dried at 80℃ for 15 minutes, the second stage is dried at 100℃ for 20 minutes, and the third stage is dried at 120℃ for 10 minutes. After drying, the solvent residue of the resin layer is 0.1%, and the variability of the semi-cured viscosity curve is 0.5%.

[0030] The remaining steps and processes are the same as in Example 1, thus obtaining the functional adhesive copper foil material of this example.

[0031] Example 4: 1) Weigh the raw materials according to the following mass fractions: 45% Bisphenol A type epoxy resin (epoxy value 0.55 eq / 100g), 25% polyimide (number average molecular weight 30000, Tg=250℃), 4% functional additives (nano silica: tricresyl phosphate: p-tert-butylphenol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] = 2.2:1:1:0.5), 26% solvent (propylene glycol methyl ether acetate: xylene mass ratio = 3.5:1); 2) Add epoxy resin and polyimide to a mixing tank and pre-stir for 35 min at 35℃ and 700 r / min. Add functional additives and solvent, heat to 50℃, and disperse at 1800 r / min for 120 min under ultrasonic oscillation frequency of 40 kHz to obtain a uniform resin slurry. 3) One side of the electrolytic copper foil is subjected to degreasing, acidification, and passivation pretreatment in sequence; The degreasing treatment involves spraying a degreasing solution consisting of 3% sodium hydroxide, 2% sodium carbonate, 1% surfactant (fatty alcohol polyoxyethylene ether), and the remainder being deionized water, with a pH value of 12, onto one side of the copper foil. After spraying, the solution is left to stand at 50°C for 5 minutes and then rinsed with deionized water until the pH value reaches 7. The acidification treatment involves spraying an 8% sulfuric acid solution onto the degreased copper foil surface, allowing it to stand at 30°C for 2 minutes after spraying, and then rinsing it with deionized water until the pH reaches 7. The acidification treatment involves spraying a 5%-10% sulfuric acid solution onto the degreased copper foil surface, allowing it to stand at 30°C for 2 minutes after spraying, and then rinsing it with deionized water until the pH reaches 7. The passivation treatment involves spraying a passivation solution composed of 1% CrO3, 0.2% sulfuric acid, 0.1% nitric acid, and the remainder deionized water onto the surface of the acidified copper foil. After spraying, the surface is left to stand at 25°C for 2 minutes, rinsed with deionized water until no chromium ions remain, and then dried at 70°C for 10 minutes to remove surface moisture. After passivation, an electrolytic copper foil with one rough side and one smooth side is obtained, with a roughness Ra=0.1μm on the rough side. 4) First, a nickel-chromium alloy is sputtered and deposited on the rough surface of the electrolytic copper foil as a transition layer. The sputtering power is 200W, the deposition time is 20min, and the thickness of the transition layer is controlled at 1μm. The electrolytic copper foil is fixed to the unwinding mechanism of the coating machine. The slit coating process is adopted, the coating speed is 3m / min, and the coating thickness is 30μm. The uniformity is monitored online during the coating process. 5) The coated copper foil is sent into a precision oven and a segmented heating and drying process is adopted. The first stage is drying at 65℃ for 22 minutes, the second stage is drying at 95℃ for 22 minutes, and the third stage is drying at 115℃ for 18 minutes. After drying, the solvent residue in the resin layer is 0.18%, and the variability of the semi-cured viscosity curve is 0.7%.

[0032] The remaining steps and processes are the same as in Example 1, thus obtaining the functional adhesive copper foil material of this example.

[0033] Example 5: 1) Weigh the raw materials according to the following mass fractions: 55% bisphenol A type epoxy resin (epoxy value 0.55 eq / 100g), 15% polyimide (number average molecular weight 30000, Tg=250℃), 6% functional additives (nano silica: tricresyl phosphate: p-tert-butylphenol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] = 2.8:1:1:0.6), 26% solvent (propylene glycol methyl ether acetate: xylene mass ratio = 4.5:1); 2) Add epoxy resin and polyimide to a mixing tank and pre-stir at 32°C and 650 r / min for 40 min. Add functional additives and solvent, heat to 50°C, and disperse at 1800 r / min for 120 min under ultrasonic oscillation at 40 kHz to obtain a uniform resin slurry. 3) One side of the electrolytic copper foil is subjected to degreasing, acidification, and passivation pretreatment in sequence; The degreasing treatment involves spraying a degreasing solution consisting of 3% sodium hydroxide, 2% sodium carbonate, 1% surfactant (fatty alcohol polyoxyethylene ether), and the remainder being deionized water, with a pH value of 12, onto one side of the copper foil. After spraying, the solution is left to stand at 50°C for 5 minutes and then rinsed with deionized water until the pH value reaches 7. The acidification treatment involves spraying an 8% sulfuric acid solution onto the degreased copper foil surface, allowing it to stand at 30°C for 2 minutes after spraying, and then rinsing it with deionized water until the pH reaches 7. The passivation treatment involves spraying a passivation solution composed of 1% CrO3, 0.2% sulfuric acid, 0.1% nitric acid, and the remainder deionized water onto the surface of the acidified copper foil. After spraying, the surface is left to stand at 25°C for 2 minutes, rinsed with deionized water until no chromium ions remain, and then dried at 70°C for 10 minutes to remove surface moisture. After passivation, an electrolytic copper foil with one rough side and one smooth side is obtained, with a roughness Ra=0.1μm on the rough side. 4) First, a nickel-chromium alloy is sputtered and deposited as a transition layer on the rough surface of the electrolytic copper foil. The sputtering power is 200W, the deposition time is 20min, and the thickness of the transition layer is controlled at 1μm. The electrolytic copper foil is fixed to the unwinding mechanism of the coating machine. The slit coating process is adopted, the coating speed is 4m / min, and the coating thickness is 80μm. The uniformity is monitored online during the coating process. After the coating is completed, it is pre-dried at 70℃ for 4min. 5) The coated copper foil is sent into a precision oven and a segmented heating and drying process is adopted. The first stage is drying at 75℃ for 18 minutes, the second stage is drying at 85℃ for 22 minutes, and the third stage is drying at 105℃ for 12 minutes. After drying, the solvent residue in the resin layer is 0.12%, and the variability of the semi-cured viscosity curve is 0.4%.

[0034] The remaining steps and processes are the same as in Example 1, thus obtaining the functional adhesive copper foil material of this example.

[0035] The properties of the functional adhesive copper foil materials prepared in Examples 1 to 2 were measured, and the results are shown in Table 1.

[0036] Table 1: Example 1 Example 2 Example 3 Example 4 Example 5 Glass transition temperature (Tg, DMA) (°C) 185 195 205 190 200 Dielectric constant (Dk, 5GHz) 3.2 3.1 3.0 3.15 3.05 Dielectric loss (Df, 5GHz) 0.005 0.004 0.003 0.0045 0.0035 Pyrolysis temperature (Td) (°C) 410 425 435 420 430 Moisture absorption rate (%) 0.55 0.50 0.45 0.52 0.48 Imaging time (s) 55 50 45 52 48 XY axis CTE (α1, before Tg) (ppm / ℃) 28 25 22 26 23 XY axis CTE (α2, afterTg) (ppm / ℃) 65 60 55 62 58 Z-axis CTE (α1, before Tg) (ppm / ℃) 38 35 32 36 33 Z-axis CTE (α2, afterTg) (ppm / ℃) 95 90 85 92 88 Solvent residue (%) 0.2 0.15 0.1 0.18 0.12 Variation of semi-cured viscosity profile (%) 0.8 0.6 0.5 0.7 0.4 Bond strength with copper foil (N / mm) 1.8 2.1 2.3 1.9 2.2 As can be seen from Table 1, the functional adhesive copper foil material prepared under the process conditions of the present invention exhibits excellent stability and adjustability. In the present invention, the interfacial interaction between nano-silica and the resin system can stably achieve low dielectric properties. By controlling the content of polyimide and combining it with the segmented drying temperature gradient, the high-temperature stability can be improved. Overall, there is no single performance shortcoming, indicating that the technical solution of the present invention can achieve synergistic improvement of multiple properties and meet the stringent requirements of high-density packaging substrates for materials.

[0037] Copper foil pretreatment, nickel-chromium transition layer, and coating pre-drying are all key control points in the preparation process. Omitting any step will lead to a decrease in interfacial adhesion, an increase in solvent residue, and a surge in moisture absorption, which in turn will cause a chain reaction of degradation in dielectric, dimensional stability, and high-temperature performance, ultimately resulting in the material failing to meet the requirements of high-density packaging substrate layering.

[0038] Comparative Example 1: The difference between this comparative example and Example 2 is that the mass ratio of nano silica, tricresyl phosphate, p-tert-butylphenol, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] is 1:1:1:1. The proportions of other raw materials and the process steps are the same as in Example 2, thus obtaining the functional adhesive copper foil material of this comparative example.

[0039] Comparative Example 2: The difference between this comparative example and Example 2 is that the functional additive, dielectric modifier nano-silica, is replaced with nano-titanium dioxide. The remaining raw material ratios and process steps are the same as in Example 2, thus obtaining the functional adhesive copper foil material of this comparative example.

[0040] Comparative Example 3: The difference between this comparative example and Example 2 is that the crosslinking inhibitor tricresyl phosphate in the functional additives is replaced with salicylic acid, while the other raw material ratios and process steps are the same as in Example 2, thus obtaining the functional adhesive copper foil material of this comparative example.

[0041] Comparative Example 4: The difference between this comparative example and Example 2 is that the imaging promoter p-tert-butylphenol in the functional additives is replaced with hydroquinone, while the other raw material ratios and process steps are the same as in Example 2, thus obtaining the functional adhesive copper foil material of this comparative example.

[0042] The performance of the functional adhesive copper foil materials prepared in Comparative Examples 5 to 8 was measured and compared with that in Example 2. The results are shown in Table 2.

[0043] Table 2: Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Glass transition temperature (Tg, DMA) (°C) 195 180 192 155 193 Dielectric constant (Dk, 5GHz) 3.1 3.8 5.8 3.2 3.1 Dielectric loss (Df, 5GHz) 0.004 0.008 0.021 0.006 0.005 Pyrolysis temperature (Td) (°C) 425 415 420 360 422 Moisture absorption rate (%) 0.50 0.58 0.52 0.75 0.51 Imaging time (s) 50 75 52 25 65 XY axis CTE (α1, before Tg) (ppm / ℃) 25 30 27 42 26 XY axis CTE (α2, afterTg) (ppm / ℃) 60 70 63 90 62 Z-axis CTE (α1, before Tg) (ppm / ℃) 35 40 37 52 36 Z-axis CTE (α2, afterTg) (ppm / ℃) 90 100 93 118 91 Variation of semi-cured viscosity profile (%) 0.6 1.0 0.16 0.25 0.15 Bond strength with copper foil (N / mm) 2.1 1.6 2.0 1.2 2.0 As can be seen from Table 2, the specific types and specific ratios of the functional additives of the present invention are the key to achieving the core performance of the material. Deviation of the additive ratio will lead to a comprehensive and significant deterioration of the material performance. The limited range of 2:1:1:0.5 to 3:1:1:1 is the key to achieving synergistic performance such as dielectric properties, dimensional stability, and process control. After deviation, the functions of each additive cannot be effectively complementary, directly leading to the deterioration of the overall performance of the material.

[0044] The performance defects of the materials obtained by replacing the dielectric modifier from nano-silica with nano-titanium dioxide are concentrated in dielectric properties and high-frequency compatibility. The core reason for this phenomenon is that the dielectric constant of nano-titanium dioxide is much higher than that of nano-silica, and its interfacial compatibility with the resin system is poor. It cannot reduce the overall dielectric performance through interfacial interaction. Instead, its high dielectric properties significantly reduce the high-frequency compatibility of the material.

[0045] The performance of the material obtained by replacing the crosslinking inhibitor from tricresyl phosphate with salicylic acid deteriorated significantly. This is because although salicylic acid has a certain ability to inhibit crosslinking, its poor thermal stability and strong acidity make it impossible to achieve the specific advantages of the phosphate ester compounds of this invention in regulating the resin crosslinking reaction and ensuring the overall stability of the material.

[0046] Replacing the imaging promoter from p-tert-butylphenol with hydroquinone revealed performance defects focused on imaging accuracy and circuit integrity. The core reason is that hydroquinone contains two phenolic hydroxyl groups, resulting in excessively high reactivity with alkaline developer. Its dissolution rate far exceeds the controllable range of the resin layer. Although it can develop quickly, it excessively erodes the edges of the circuit, compromising circuit accuracy. Furthermore, the other properties of this comparative example are basically consistent with those of Example 2, demonstrating that the single phenolic hydroxyl structure of p-tert-butylphenol can precisely control the imaging rate, achieving a balance between rapid development (<60s) and circuit integrity. In contrast, highly reactive phenolic derivatives such as hydroquinone, due to their poor reaction controllability, cannot meet the requirements of high-density packaging for fine circuits.

[0047] Comparative Example 5: The difference between this comparative example and Example 2 is that the ultrasonic vibration assistance in step 2) is omitted, and the material is dispersed at a high speed of 1500 r / min for 150 min. The other raw material ratios and process steps are the same as in Example 2, thus obtaining the functional adhesive copper foil material of this comparative example.

[0048] Comparative Example 6: The difference between this comparative example and Example 2 is that the segmented heating and drying process in step 5) is adjusted to a constant temperature drying at 100℃ for 60 minutes. The remaining raw material ratios and process steps are the same as in Example 2, thus obtaining the functional adhesive copper foil material of this comparative example.

[0049] Comparative Example 7: The difference between this comparative example and Example 2 is that the mass ratio of propylene glycol methyl ether acetate to xylene in the solvent of step 1) is adjusted to 2:1. The other raw material ratios and process steps are the same as in Example 2, thus obtaining the functional adhesive copper foil material of this comparative example.

[0050] The performance of the functional adhesive-backed copper foil materials prepared in Comparative Examples 9 to 11 was measured and compared with that in Example 2. The results are shown in Table 3.

[0051] Table 3: Example 2 Comparative Example 5 Comparative Example 6 Comparative Example 7 Glass transition temperature (Tg, DMA) (°C) 195 188 170 182 Dielectric constant (Dk, 5GHz) 3.1 3.5 3.6 3.7 Dielectric loss (Df, 5GHz) 0.004 0.007 0.009 0.010 Pyrolysis temperature (Td) (°C) 425 418 400 410 Moisture absorption rate (%) 0.50 0.62 0.70 0.68 Imaging time (s) 50 68 82 79 XY axis CTE (α1, before Tg) (ppm / ℃) 25 32 38 33 XY axis CTE (α2, afterTg) (ppm / ℃) 60 73 82 75 Z-axis CTE (α1, before Tg) (ppm / ℃) 35 42 48 43 Z-axis CTE (α2, afterTg) (ppm / ℃) 90 105 115 106 Solvent residue (%) 0.15 0.21 0.25 0.23 Variation of semi-cured viscosity profile (%) 0.6 1.1 1.5 1.3 Bond strength with copper foil (N / mm) 2.1 1.5 1.3 1.4 As can be seen from Table 3, ultrasonic vibration-assisted dispersion, segmented heating and drying, and specific solvent ratio are indispensable key steps in the preparation process of this invention. Deviation of any process parameter will lead to failure or deterioration of key material properties, failing to meet the stringent requirements of high-density packaging substrate layering.

[0052] Comparative Example 5, lacking ultrasonic vibration-assisted dispersion, exhibited performance degradation primarily in the uniformity of additive dispersion and its consequent effects on dielectric properties, dimensional stability, and hygroscopicity. This was because the absence of ultrasonic vibration to break up agglomerates led to uneven dispersion of additives such as nano-silica in the resin system, forming localized dielectric islands and resulting in a decrease in overall dielectric properties. Furthermore, the tiny voids formed by additive agglomerates easily absorb moisture, increasing hygroscopicity. Uneven additive dispersion caused inconsistent resin curing shrinkage, and the accumulation of internal stress exacerbated dimensional expansion and contraction, reducing interfacial bonding strength from 2.1 N / mm to 1.5 N / mm. Uneven contact between the resin layer and the rough surface of the copper foil further reduced the bonding strength. These data demonstrate that ultrasonic vibration-assisted dispersion is not simply a process optimization, but rather a crucial element in ensuring uniform additive dispersion and achieving synergistic performance of various materials. Its absence directly leads to overall material performance degradation, failing to meet the uniformity and stability requirements of high-density packaging.

[0053] Comparative Example 6 replaced segmented heating drying with constant temperature drying. The performance defects were concentrated in the control of the degree of semi-curing, high temperature stability and moisture absorption. Because constant temperature drying cannot achieve the process of gradual solvent removal and slow cross-linking of the resin, the resin is not fully cured and is prone to softening at high temperatures. Uneven curing of the resin layer leads to defects in the interface with the copper foil. The above data show that the segmented heating drying process in this invention, through the gradient design of low temperature solvent removal, medium temperature pre-cross-linking and high temperature stability, accurately controls the degree of resin semi-curing. This is the core of ensuring the material's high temperature stability, low moisture absorption and dimensional accuracy. Single temperature drying cannot achieve this goal, directly causing the material to lose its high-density encapsulation adaptability.

[0054] Comparative Example 7 showed performance degradation due to the solvent ratio deviating from the specified range of 3:1 to 5:1. The degradation focused on resin solubility, coating uniformity, and derived dielectric and hygroscopic properties. This is because the ratio of propylene glycol methyl ether acetate (highly polar with strong dissolving power) to xylene (viscosity adjuster) of 3:1 to 5:1 is the basis for ensuring sufficient resin dissolution, slurry stability, and uniform coating. When deviated from this ratio, the stability of the resin system decreases, directly affecting the overall performance of the material, further highlighting the necessity of solvent ratio design.

[0055] Comparative Example 8: The difference between this comparative example and Example 2 is that step 3) of pre-treating one side of the electrolytic copper foil is omitted. The remaining raw material ratios and process steps are the same as in Example 2, thus obtaining the functional adhesive copper foil material of this comparative example.

[0056] Comparative Example 9: The difference between this comparative example and Example 2 is that step 4) is omitted, in which a nickel-chromium alloy is first sputtered and deposited on the rough surface of the electrolytic copper foil as a transition layer. Instead, the slurry is directly coated on the rough surface of the pretreated copper foil to obtain the functional adhesive copper foil material of this comparative example.

[0057] Comparative Example 10: The difference between this comparative example and Example 2 is that the step of pre-drying at 70°C for 4 minutes after coating in step 4) is omitted. The remaining raw material ratios and process steps are the same as in Example 2, thus obtaining the functional adhesive copper foil material of this comparative example.

[0058] The performance of the functional adhesive-backed copper foil materials prepared in Comparative Examples 8 to 10 was measured and compared with that in Example 2. The results are shown in Table 4.

[0059] Table 4: Example 2 Comparative Example 8 Comparative Example 9 Comparative Example 10 Glass transition temperature (Tg, DMA) (°C) 195 175 180 165 Dielectric constant (Dk, 5GHz) 3.1 3.9 3.7 3.8 Dielectric loss (Df, 5GHz) 0.004 0.012 0.009 0.011 Pyrolysis temperature (Td) (°C) 425 385 395 370 Moisture absorption rate (%) 0.50 0.85 0.72 0.88 Imaging time (s) 50 95 80 105 XY axis CTE (α1, before Tg) (ppm / ℃) 25 39 35 42 XY axis CTE (α2, afterTg) (ppm / ℃) 60 88 82 95 Z-axis CTE (α1, before Tg) (ppm / ℃) 35 50 46 53 Z-axis CTE (α2, afterTg) (ppm / ℃) 90 125 118 132 Solvent residue (%) 0.15 0.32 0.28 0.45 Variation of semi-cured viscosity profile (%) 0.6 1.8 1.4 2.1 Bond strength with copper foil (N / mm) 2.1 0.9 1.2 1.0 As shown in Table 4, the copper foil in Comparative Example 8 was not pretreated by degreasing, acidification, and passivation. Its surface contained oil, oxide layers, and impurities, preventing the resin slurry from effectively bonding with the rough surface of the copper foil. The interfacial adhesion dropped sharply from 2.1 N / mm in Example 2 to 0.9 N / mm, only 42.9% of its original performance, severely impacting the material's structural integrity. Simultaneously, interfacial defects created moisture channels, compromising the material's insulation stability; stress concentration at the resin-copper foil interface led to a comprehensive deterioration of the thermal expansion coefficient and loss of dimensional stability. Therefore, copper foil pretreatment is a prerequisite for ensuring interfacial adhesion, inhibiting moisture absorption, and stabilizing dielectric and dimensional properties; omitting this pretreatment results in the complete failure of the material's core performance.

[0060] The core function of setting a transition layer before coating the slurry is to bridge the copper foil and the resin layer, improving interfacial compatibility and bonding strength. In Comparative Example 9, where this is omitted, the resin and copper foil are in direct contact, resulting in significantly reduced bonding strength. This leads to localized resin residue during development, prolonging the development time and making it unsuitable for the fine circuit processing of high-density packaging.

[0061] The core function of pre-drying after coating is to initially remove the solvent and avoid solvent boiling during subsequent segmented drying, which would lead to pores in the resin layer. Without this step, the residual solvent content is three times higher than in Example 2 (0.15%). This residual solvent causes uncontrolled resin semi-curing, making uneven resin flow likely during subsequent hot-pressing. The internal pores of the resin layer, combined with the residual solvent, are prone to thermal decomposition at high temperatures. Simultaneously, the pores and residual solvent disrupt dielectric uniformity (Dk=3.8, Df=0.011), and the residual solvent affects developer penetration during development, extending the development time to 105 seconds. Furthermore, the moisture absorption rate increases to 0.88%, deteriorating insulation performance.

[0062] In summary, this invention innovatively designs a functional additive compound system and optimizes the addition method to achieve synergistic improvement of multiple properties. By clearly defining the specific types and functions of dielectric regulators, crosslinking inhibitors, imaging promoters, and anti-aging agents, and employing an addition process of pre-stirring homogenization + ultrasonic-assisted dispersion, the additives are uniformly dispersed in the resin system. Among them, nano-silica reduces the dielectric constant and dielectric loss of the material through interfacial interaction, phosphate ester crosslinking inhibitors precisely regulate the resin crosslinking rate and avoid internal stress concentration during curing, phenolic derivative imaging promoters shorten the material imaging time to within 60 seconds, solving the technical pain points of existing materials having no imaging function or low imaging efficiency and poor dielectric properties, and hindered phenolic anti-aging agents capture free radicals, inhibit resin oxidative degradation, stabilize interfacial bonding, and avoid dielectric drift.

[0063] By precisely controlling the semi-curing degree of the resin through a segmented heating and drying process, and combining it with ultrasonic-assisted dispersion technology to break up raw material agglomeration, the material has excellent dimensional stability and high-temperature stability, effectively reducing the alignment deviation during multi-layer lamination, and solving the problems of poor pressing uniformity and low dimensional accuracy of existing PP materials, as well as insufficient high-temperature stability of ABF materials.

[0064] The preparation process of this invention is the result of multi-stage synergistic optimization. Each step is designed to address specific performance pain points. Pretreatment solves interface bonding, the transition layer strengthens synergy, and pre-drying controls semi-curing; none of these steps can be omitted. The preparation process of this invention is compatible with existing coating equipment, enabling automated production. Production efficiency is increased by 30% to 50% compared to PP materials, significantly reducing material costs while providing imaging functionality. No additional processing steps are required, significantly reducing the production cost of high-density encapsulation substrates.

[0065] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a functional adhesive-backed copper foil material, characterized in that: include, Epoxy resin and polyimide were added to a mixing tank for pre-stirring, and then functional additives and solvents were added. The mixture was then dispersed at high speed under ultrasonic vibration to obtain a uniform resin slurry. The functional additives are composed of nano-silica, tricresyl phosphate, p-tert-butylphenol, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. One side of the electrolytic copper foil is subjected to degreasing, acidification, and passivation pretreatment in sequence to obtain an electrolytic copper foil with one rough side and one smooth side. First, a nickel-chromium alloy is sputtered and deposited on the rough surface of the electrolytic copper foil as a transition layer. Then, the resin slurry is uniformly coated on the transition layer and processed by a segmented heating and drying process. After drying, the semi-cured adhesive copper foil is cooled to room temperature, and a PET protective film is bonded to the surface of the resin layer by a hot-pressing composite process. After winding, the functional adhesive copper foil material is obtained.

2. The method for preparing the functional adhesive-backed copper foil material as described in claim 1, characterized in that: The resin slurry comprises, by weight percentage, the following components: 40%~60% high molecular weight epoxy resin, 5%~30% polyimide, 3%~8% functional additives and 15%~35% solvent; The high molecular weight epoxy resin includes bisphenol A type epoxy resin or phenolic epoxy resin, with an epoxy value of 0.4 eq / 100g to 0.6 eq / 100g; the polyimide has a number average molecular weight of 10,000 to 30,000 and a glass transition temperature (Tg) > 220℃. The functional additive is composed of nano-silica, tricresyl phosphate, p-tert-butylphenol, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] in a mass ratio of 2:1:1:0.5 to 3:1:1:

1. The solvent is a mixture of propylene glycol methyl ether acetate and xylene in a mass ratio of 3:1 to 5:

1.

3. The method for preparing the functional adhesive-backed copper foil material as described in claim 1, characterized in that: The high-speed dispersion under ultrasonic oscillation assistance is defined as high-speed dispersion at an ultrasonic oscillation frequency of 20kHz to 40kHz and a rotation speed of 1200r / min to 1800r / min for 120min to 180min.

4. The method for preparing the functional adhesive-backed copper foil material as described in claim 1, characterized in that: The surface roughness of the pretreated copper foil is Ra = 0.1~0.3μm.

5. The method for preparing the functional adhesive-backed copper foil material as described in claim 1, characterized in that: The transition layer is prepared by sputtering deposition process with a sputtering power of 100~300W, a deposition time of 5~15min, and a thickness of 0.5~2μm.

6. The method for preparing the functional adhesive-backed copper foil material as described in claim 5, characterized in that: The coating speed is 0.5m / min to 5m / min, and the coating thickness is controlled between 5um and 100um. During the coating process, the coating uniformity is monitored in real time by online detection. After the coating is completed, the coating is pre-dried at 60 to 80°C for 3 to 5 minutes.

7. The method for preparing the functional adhesive-backed copper foil material as described in claim 6, characterized in that: The segmented heating and drying process has the following steps: the first stage temperature is 60℃~80℃, and the drying time is 15min~25min; the second stage temperature is 80℃~100℃, and the drying time is 20min~30min; the third stage temperature is 100℃~120℃, and the drying time is 10min~20min. After drying, the semi-cured resin layer meets the following requirements: solvent residue is 0.1%~0.2%, and the variation of the semi-cured viscosity curve is <1%.

8. The method for preparing the functional adhesive-backed copper foil material as described in claim 1, characterized in that: The hot-pressing composite process has a hot-pressing temperature of 100℃~120℃, a hot-pressing pressure of 0.3~1.5MPa, and a hot-pressing time of 10s~300s.

9. The functional adhesive-backed copper foil material prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The functional adhesive-backed copper foil material has the following characteristics. (i) Tg(DMA) > 180℃; (ii) Dk(1G~10GHz)<3.3, Df(1G~10GHz)<0.006; (iii) Td (pyrolysis temperature) > 400℃; (iv) Moisture absorption rate <0.6%; (v) Imaging time < 60 seconds; (vi) XY axis thermal expansion coefficient (α1beforeTg) < 30ppm, XY axis thermal expansion coefficient (α2afterTg) < 70ppm, Z axis thermal expansion coefficient (α1beforeTg) < 40ppm, Z thermal expansion coefficient CTE (α2afterTg) < 100ppm; where α1beforeTg represents the corresponding axis thermal expansion coefficient before the glass transition temperature, and α2afterTg represents the corresponding axis thermal expansion coefficient after the glass transition temperature.

10. The application of the functional adhesive-backed copper foil material as described in claim 9 as an addendum to a high-density encapsulation substrate.

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