Preparation method of epoxy underfill adhesive for enhancing FPC (Flexible Printed Circuit) bonding force

Abstract

The invention relates to the technical field of adhesives, in particular to a preparation method of an epoxy underfill adhesive for enhancing FPC (flexible printed circuit) adhesive strength, which comprises the following steps: mixing an epoxy resin mixture, a coupling agent and a conductive black adhesive, and stirring for 0.5-1 hour in a vacuum environment; adding a filler, heating to 70-90 DEG C, stirring for 6-10 hours in a vacuum environment, and then reducing the temperature to normal temperature; adding an accelerant and a curing agent, and stirring for 1.5-2 hours under the vacuum condition of 25-30 DEG C; carrying out various performance experiments on the epoxy underfill; and obtaining various performance indexes of the epoxy underfill. According to the scheme, various experiments are set to detect the performance of the produced epoxy underfill adhesive, and various indexes are set to measure the performance of the underfill adhesive sample in various aspects, so that a worker can judge whether the performance of the underfill adhesive is qualified or not according to the index values.

Description

Technical Field

[0001] The invention relates to the technical field of adhesives, and in particular to a method for preparing an epoxy bottom filling adhesive for enhancing the bonding force of an FPC. Background Art

[0002] FPC, also known as flexible printed circuit board, is often bonded to FPC and electronic components by epoxy bottom filling glue in the prior art.

[0003] For example, the prior art CN107699178A discloses an epoxy adhesive for FPC and a preparation method thereof, which belongs to the technical field of flexible circuit board processing. The epoxy adhesive comprises the following components in weight ratio: 15-25% composite epoxy resin; 10-15% toughening agent; 10-25% composite flame retardant; 5-10% composite curing agent; 0.1-3% other additives; and the remainder is solvent, wherein the composite epoxy resin is a mixture of bisphenol A type E-22 epoxy resin and bisphenol A type E-54 epoxy resin in a mass ratio of 1-3:1, and the composite flame retardant is a mixture of aluminum hydroxide and phosphorus nitrogen flame retardant.

[0004] Another typical prior art disclosed in CN106753081A is an adhesive film for FPC, a preparation method thereof and an FPC. The adhesive film for FPC includes an adhesive layer, which is made of raw materials containing the following components: 50-80 parts by weight of acrylate adhesive; 3-10 parts by weight of curing agent; 0.01-1 parts by weight of curing accelerator; and 0.01-0.2 parts by weight of catalyst.

[0005] Let's look at the prior art disclosed in CN111849403A, which discloses a flexible epoxy adhesive for component packaging protection on FPC and its preparation method. The flexible epoxy adhesive includes the following materials and weight ratios: 30-60 parts of composite epoxy resin, 10-15 parts of epoxy diluent, 20-40 parts of mercaptan curing agent, 5-10 parts of thixotropic agent, 5-10 parts of stabilizer, and 5-10 parts of accelerator. Its preparation method includes the following steps: heating the composite epoxy resin, diluent, mercaptan curing agent and thixotropic agent, vacuuming and stirring for 1 hour, and controlling the temperature at 45-60°C; cooling the above solution to room temperature, adding the stabilizer and stirring for 1 hour, and controlling the temperature at 25-40°C; adding the accelerator and stirring for 1 hour, and controlling the temperature at 25-40°C.

[0006] At present, in the existing preparation method of epoxy bottom filling glue, the performance of the filling glue produced by raw materials purchased from different origins or raw material suppliers will be different. In the prior art, the quality of the product is generally not timely tested and the preparation method or raw material ratio is not adjusted according to the product quality, which leads to uneven quality of the products produced. In order to solve the common problems in the field, the present invention is made. Summary of the invention

[0007] The purpose of the present invention is to address the existing deficiencies and propose a method for preparing an epoxy bottom filling adhesive for enhancing the bonding strength of FPC.

[0008] In order to overcome the shortcomings of the prior art, the present invention adopts the following technical solutions:

[0009] A method for preparing an epoxy bottom filling adhesive for enhancing the bonding strength of an FPC comprises the following steps:

[0010] S1, mixing the epoxy resin mixture, the coupling agent and the conductive black glue, and stirring them in a vacuum environment for 0.5 to 1 hour to obtain a first mixture.

[0011] S2, adding filler to the first mixture, heating it to 70 to 90 degrees Celsius, and stirring it in a vacuum environment for 6 to 10 hours, and then lowering its temperature to room temperature to obtain a second mixture.

[0012] S3, adding an accelerator and a curing agent to the second mixture, stirring it under a vacuum condition of 25 to 30 degrees Celsius for 1.5 to 2 hours, and obtaining the epoxy bottom filling adhesive after the stirring is completed.

[0013] S4, conduct various performance tests on the epoxy bottom filling adhesive.

[0014] S5, obtaining various performance indicators of the epoxy bottom filling glue according to the experimental data of various performance experiments, and judging whether the epoxy bottom filling glue produced this time is qualified according to the obtained performance indicators; the performance indicators include curing performance indicators, strength performance indicators and comprehensive performance indicators.

[0015] Furthermore, the raw materials for preparing the epoxy bottom filling glue include 20-30 parts of epoxy resin mixture, 0.5-0.8 parts of coupling agent, 0.6-1 parts of conductive black glue, 66-74 parts of filler, 0.5-1 parts of accelerator and 8-14 parts of curing agent in a weight ratio.

[0016] Furthermore, the epoxy resin mixture includes 5 to 8 parts of naphthalene epoxy resin, 1 to 2 parts of multifunctional epoxy resin, 10 to 14 parts of bisphenol epoxy resin, and 4 to 6 parts of toughened epoxy resin in a weight ratio, and the filler is a spherical filler.

[0017] Furthermore, various performance tests on epoxy underfill include the following steps:

[0018] S41, obtaining a filling glue sample, and measuring the viscosity of the filling glue sample at room temperature by using a viscometer.

[0019] S42, obtaining the time required for the filling glue sample to be completely cured under different temperature conditions.

[0020] S43, measuring the dielectric constant of the cured filling glue sample by using a dielectric constant meter.

[0021] S44, the glass transition temperature of the cured filling glue sample is measured by dynamic mechanical analysis.

[0022] S45, compressing and shearing the cured filling glue sample, and collecting various parameters generated during the compression and shearing process.

[0023] Furthermore, obtaining the performance indicators of epoxy underfill includes the following steps:

[0024] S51, calculate the curing performance index according to the time required for the filling glue sample to be completely cured under different temperature conditions.

[0025] S52, calculating the strength performance index according to various parameters generated during compression and shearing.

[0026] S53, calculating the comprehensive performance index according to various data generated during the experiment.

[0027] Furthermore, it also includes a system for preparing epoxy underfill glue, the system including a preparation module, an experimental module and a calculation module, the preparation module is used to prepare epoxy underfill glue, the experimental module is used to perform various performance experiments on the produced epoxy underfill glue, and the calculation module is used to calculate various performance indicators of the produced epoxy underfill glue according to the experimental results of the experimental module;

[0028] The preparation module includes a raw material storage unit, a mixing container, a stirring unit and a heating unit. The raw material storage unit stores various raw materials required for preparing epoxy bottom filling glue, the mixing container is used to mix various containers, the stirring unit is used to stir the various raw materials in the mixing container, and the heating unit is used to heat the various raw materials in the mixing container.

[0029] Furthermore, the experimental module includes a viscometer, a dielectric constant meter, a dynamic thermomechanical analyzer, a temperature adjustment unit, a timer, a pressure unit, a shear unit, a force detection unit and an image acquisition unit. The viscometer is used to measure the viscosity of the filling glue sample, the dielectric constant meter is used to detect the dielectric constant of the filling glue sample, the dynamic thermomechanical analyzer is used to detect the glass ring transition temperature of the filling glue sample, the temperature adjustment unit is used to adjust the temperature of the curing process of the filling glue sample, the timer is used to calculate the curing time of the filling glue sample, the pressure unit is used to compress the filling glue sample, the shear unit is used to shear the filling glue sample, the force detection unit is used to detect the force applied by the pressure unit and the shear unit, and the image acquisition unit is used to obtain the deformation degree of the filling glue sample during the compression and shearing process and the image of the filling glue sample before and after curing; the data collected by the viscometer, dielectric constant meter, dynamic thermomechanical analyzer, temperature adjustment unit, timer, pressure unit, shear unit, force detection unit and image acquisition unit will be transmitted to the data acquisition unit by wireless transmission.

[0030] Furthermore, the calculation module includes a data acquisition unit, a calculation unit and a storage unit. The data acquisition unit is used to collect various parameters generated by the experimental module during the experiment. The calculation unit is used to calculate various indicator values ​​based on the collected data of the data acquisition unit. The storage unit is used to store the calculation results of the calculation unit and the corresponding thresholds of various indicators.

[0031] The beneficial effects achieved by the present invention are: 1. By setting up various experiments to detect the performance of the produced epoxy bottom filling glue, and at the same time, by setting various indicators to measure the performance of various aspects of the filling glue sample, rather than comparing a single experimental data with its corresponding threshold, it is beneficial to comprehensively measure the performance of the filling glue and digitize the measurement results, which is beneficial for the staff to judge whether the performance of the filling glue is qualified according to the indicator value.

[0032] 2. The change rate of parameters under different circumstances is introduced in the calculation process of the indicators, which is conducive to understanding the change of parameters under different circumstances, so as to judge their stability and to more comprehensively reflect the performance of the filling glue. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention can be further understood from the following description in conjunction with the accompanying drawings. The components in the figures are not necessarily drawn to scale, but the emphasis is placed on illustrating the principles of the embodiments. In different views, the same reference numerals designate the same parts.

[0034] Figure 1 It is a schematic diagram of the structure of the present invention.

[0035] Figure 2It is the work flow chart of the present invention.

[0036] Figure 3 The present invention is a flow chart of various performance experiments on epoxy bottom filling adhesive.

[0037] Figure 4 The present invention is a flow chart for obtaining various performance indicators of epoxy bottom filling glue.

[0038] Figure 5 This is the effect diagram of the comprehensive performance index changing with the curing performance index and strength performance index DETAILED DESCRIPTION

[0039] The following is an explanation of the embodiments of the present invention through specific embodiments. Those skilled in the art can understand the advantages and effects of the present invention from the contents disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and the details in this specification can also be modified and changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. In addition, the drawings of the present invention are only simple schematic illustrations and are not depicted according to actual sizes. It is stated in advance. The following embodiments will further explain the relevant technical contents of the present invention in detail, but the disclosed contents are not intended to limit the scope of protection of the present invention.

[0040] Embodiment 1: According to Figure 1 , Figure 2 , Figure 3 and Figure 4 This embodiment provides a method for preparing an epoxy bottom filling adhesive for enhancing the adhesion of an FPC, comprising the following steps:

[0041] S1, mixing the epoxy resin mixture, the coupling agent and the conductive black glue, and stirring them in a vacuum environment for 0.5 to 1 hour to obtain a first mixture.

[0042] S2, adding filler to the first mixture, heating it to 70 to 90 degrees Celsius, and stirring it in a vacuum environment for 6 to 10 hours, and then lowering its temperature to room temperature to obtain a second mixture.

[0043] Specifically, normal temperature here refers to 20 to 30 degrees Celsius.

[0044] S3, adding an accelerator and a curing agent to the second mixture, stirring it under a vacuum condition of 25 to 30 degrees Celsius for 1.5 to 2 hours, and obtaining the epoxy bottom filling adhesive after the stirring is completed.

[0045] S4, conduct various performance tests on the epoxy bottom filling adhesive.

[0046] S5, obtaining various performance indicators of the epoxy underfill glue according to the experimental data of various performance experiments, and judging whether the epoxy underfill glue produced this time is qualified.

[0047] The performance indicators include curing performance indicators, strength performance indicators and comprehensive performance indicators.

[0048] Specifically, when all performance indicators of the epoxy underfill produced this time are qualified, the epoxy underfill produced this time is considered qualified, otherwise, it is considered unqualified.

[0049] Furthermore, the raw materials for preparing the epoxy bottom filling glue include 20-30 parts of epoxy resin mixture, 0.5-0.8 parts of coupling agent, 0.6-1 parts of conductive black glue, 66-74 parts of filler, 0.5-1 parts of accelerator and 8-14 parts of curing agent in a weight ratio.

[0050] Furthermore, the epoxy resin mixture includes 5 to 8 parts of naphthalene epoxy resin, 1 to 2 parts of multifunctional epoxy resin, 10 to 14 parts of bisphenol epoxy resin, and 4 to 6 parts of toughened epoxy resin in a weight ratio, and the filler is a spherical filler.

[0051] Furthermore, various performance tests on epoxy underfill include the following steps:

[0052] S41, obtaining a filling glue sample, and measuring the viscosity of the filling glue sample at room temperature by using a viscometer.

[0053] Specifically, each filler sample has the same amount.

[0054] S42, obtaining the time required for the filling glue sample to be completely cured under different temperature conditions.

[0055] Specifically, to determine whether the filling glue sample is completely cured, a fine needle can be used to poke the filling glue sample. If no wire drawing phenomenon occurs, it proves that the filling glue sample is completely cured. Different filling glue samples are placed on different test boards during the curing process, and the coating areas of different filling glue samples on their corresponding test boards are the same.

[0056] S43, measuring the dielectric constant of the cured filling glue sample by using a dielectric constant meter.

[0057] S44, the glass transition temperature of the cured filling glue sample is measured by dynamic mechanical analysis.

[0058] Specifically, the measurement of glass transition temperature by dynamic mechanical analysis belongs to the prior art and will not be described in detail here. The measurement process is performed according to ASTM D 7028-2007 standard.

[0059] S45, compressing and shearing the cured filling glue sample, and collecting various parameters generated during the compression and shearing process.

[0060] Furthermore, obtaining the performance indicators of epoxy underfill includes the following steps:

[0061] S51, calculate the curing performance index according to the time required for the filling glue sample to be completely cured under different temperature conditions.

[0062] The curing performance index can be calculated according to the following formula:

[0063]

[0064]

[0065] Specifically, GHXN is a curing performance index, which is used to characterize the curing performance of the filling glue sample. The larger the index value, the better the curing performance. GHXN is a curing time index, which is used to characterize the rate of change of the curing time of the filling glue sample with temperature. The larger the index value, the greater the rate of change. A is the number of curing experiments, t a is the curing time of the ath experiment, T a is the curing temperature in the ath experiment, T max is the maximum value of the curing temperature set in A experiments, T min is the minimum value of the curing temperature set in the A-word experiment, T a-1 is the curing temperature during the a-1th experiment, t a-1 is the curing time during the a-1 experiment.

[0066] SS is a mass loss index, which is used to characterize the degree of weight loss during the curing process. The larger the index, the lower the degree of weight loss. a is the weight of the cured filling glue sample in the ath experiment, G a is the weight of the filling glue sample before curing in the ath experiment.

[0067] XB is the deformation index, which is used to characterize the degree of deformation of the filling glue sample during the curing process. The larger the index, the lower the degree of deformation. X is the number of shooting angles when shooting the filling glue sample before and after curing, e is the natural constant, h ... natural constant, e is the natural constant, h is the natural constant, e is the natural constant, h is the natural constant, e is the natural constant, h is the natural constant, e is the natural constant, h is the natural constant, h is the natural constant, h is the natural constant, h is the natural constant, h is the natural constant, h is the natural constant, h ax H is the average grayscale value of the pixels occupied by the filling glue sample in the grayscale image of the filling glue sample before curing taken at the xth shooting angle in the ath experiment, ax is the average grayscale value of the pixels occupied by the filling glue sample in the grayscale image of the filling glue sample after curing taken at the xth shooting angle in the ath experiment, num axNUM is the number of pixels occupied by the filling glue sample in the grayscale image of the filling glue sample before curing taken at the xth shooting angle in the ath experiment. ax It is the number of pixels occupied by the filling glue sample in the grayscale image of the image after curing of the filling glue sample taken at the xth shooting angle in the ath experiment.

[0068] Specifically, the curing temperature increases with the number of experiments.

[0069] S52, calculating the strength performance index according to various parameters generated during compression and shearing.

[0070] The strength performance index can be calculated according to the following formula:

[0071] QDXN=(SS+XB)*[QDXN1+QDXN2]

[0072]

[0073] Among them, QDXN is the strength performance index, which is used to characterize the strength of the filling glue sample. The larger the index value, the higher the strength. QDXN1 is the compression resistance performance index, which is used to characterize the compression resistance of the filling glue sample. The larger the index value, the stronger the compression resistance. qdxn1 is the compression deformation index, which is used to characterize the rate of change of the deformation of the filling glue sample with pressure. The larger the index value, the greater the rate of change. B is the number of compression tests, and F is the compression test number. b is the pressure provided during the bth compression test, L b is the length of the filling rubber sample compressed in the bth compression test, F bmax Provides the maximum value of pressure during compression test, F bmin Provides the minimum value of pressure during compression test, F b-1 is the pressure provided during the b-1 compression test, L b-1 It is the length of the filling rubber sample compressed in the b-1th compression test.

[0074]

[0075] QDXN2 is the shear resistance index, which is used to characterize the shear resistance of the filled rubber sample. The larger the index value, the stronger the shear resistance. qdxn2 is the shear deformation index, which is used to characterize the rate of change of the deformation of the filled rubber sample with shear force. The larger the index value, the greater the rate of change. C is the number of shear tests, and F is the number of shear tests. c is the shear force provided in the cth shear test, G c is the shear modulus obtained during the cth shear test, F cmax Provides the maximum shear force during shear test, F cmin Provides the minimum shear force during shear test; Sc is the contact area with the shearing device during the cth shearing experiment. The contact area can be calculated based on the force applied to the pressure sensor provided on the shearing surface of the shearing device. The contact area is obtained by the prior art and will not be described in detail here. h is the height of the filling glue sample. l c is the displacement of the filling rubber sample in the force direction during the cth shear test. When the filling rubber sample is sheared transversely, this value is h. The specific actual displacement can be adjusted according to the experimental requirements.

[0076] The following is the procedure for calculating the shear resistance index:

[0077] import numpy as np

[0078] def calculate_QDXN2(F,h,S,l):

[0079] """

[0080] Calculate the value of QDXN2.

[0081] parameter:

[0082] -F: List of shear resistance [F1, F2, ..., Fc]

[0083] -h: height of the filled glue sample

[0084] -S: List of contact areas [S1,S2,...,Sc]

[0085] -l: list of shear displacements [l1,l2,...,lc]

[0086] return:

[0087] -The value of QDXN2

[0088] """

[0089] #Calculate the value of G_c

[0090] G=[(F[c]*h) / (S[c]*l[c])for c in range(len(F))]

[0091] #Define parameters

[0092] C=len(F)

[0093] F_max=max(F)

[0094] F_min=min(F)

[0095] # Calculate qdxn2

[0096] qdxn2=sum([(G[c]-G[c-1]) / (F[c]-F[c-1])for c in range(1,C)]) / (F_max-F_min)

[0097] # Calculate QDXN2

[0098] QDXN2=(1-qdxn2)*(1 / C)*sum(G)

[0099] return QDXN2

[0100] QDXN2_value=calculate_QDXN2(F,h,S,l)

[0101] print("The value of QDXN2 is:",QDXN2_value)

[0102] S53, calculating the comprehensive performance index according to various data generated during the experiment.

[0103] The comprehensive performance index can be calculated according to the following formula:

[0104]

[0105] Among them, ZHXN is a comprehensive performance index. The larger the index is, the better the comprehensive performance of the produced filling glue is. YGHXN is the corresponding threshold of the curing performance index, YQDXN is the corresponding threshold of the strength performance index, N is the corresponding threshold of the viscosity, n is the detection value of the viscosity, J is the corresponding threshold of the dielectric constant, j is the detection value of the dielectric constant, Q is the corresponding threshold of the glass transition temperature, and q is the detection value of the glass transition temperature.

[0106] like Figure 5 As shown, Figure 5 Assume that YGHXN is 4 and YQDXN is 5. When all are 1, the effect diagram of the comprehensive performance index changing with the curing performance index and strength performance index.

[0107] Specifically, when the curing performance index is less than its corresponding threshold value, the curing performance is considered to be unqualified; when the strength performance index is less than its corresponding threshold value, the curing performance is considered to be unqualified; when the viscosity is greater than its corresponding threshold value, the viscosity performance is considered to be unqualified; when the dielectric constant is less than its corresponding threshold value, the insulation performance is considered to be unqualified; when the glass transition temperature is less than its corresponding threshold value, the stability performance is considered to be unqualified; when the comprehensive performance index is less than the corresponding threshold value, the filling glue is considered to be unqualified.

[0108] Specifically, in the prior art, when evaluating the curing performance, it is often only based on the curing time of the filling glue under certain set temperatures. Such an evaluation method is one-sided; when evaluating the strength performance in the prior art, it is often only based on the various parameters obtained by the filling glue under certain set strengths. Such an evaluation method is also one-sided. In order to solve this problem, this embodiment sets a curing performance index and a strength performance index, and introduces the rate of change of the parameters under different conditions in the calculation process, which is conducive to a more comprehensive reflection of the performance of the filling glue.

[0109] Furthermore, it also includes a system for preparing epoxy bottom filling glue, which includes a preparation module, an experimental module and a calculation module. The preparation module is used to prepare the epoxy bottom filling glue, the experimental module is used to perform various performance experiments on the produced epoxy bottom filling glue, and the calculation module is used to calculate various performance indicators of the produced epoxy bottom filling glue according to the experimental results of the experimental module.

[0110] The preparation module includes a raw material storage unit, a mixing container, a stirring unit and a heating unit. The raw material storage unit is used to store various raw materials required for preparing epoxy bottom filling glue, the mixing container is used to mix various containers, the stirring unit is used to stir the various raw materials in the mixing container, and the heating unit is used to heat the various raw materials in the mixing container.

[0111] Furthermore, the experimental module includes a viscometer, a dielectric constant meter, a dynamic thermomechanical analyzer, a temperature adjustment unit, a timer, a pressure unit, a shear unit, a force detection unit and an image acquisition unit, the viscometer is used to measure the viscosity of the filling glue sample, the dielectric constant meter is used to detect the dielectric constant of the filling glue sample, the dynamic thermomechanical analyzer is used to detect the glass ring transition temperature of the filling glue sample, the temperature adjustment unit is used to adjust the temperature of the curing process of the filling glue sample, the timer is used to calculate the curing time of the filling glue sample, the pressure unit is used to compress the filling glue sample, the shear unit is used to shear the filling glue sample, the force detection unit is used to detect the force applied by the pressure unit and the shear unit, and the image acquisition unit is used to obtain the degree of deformation of the filling glue sample during compression and shearing and the image of the filling glue sample before and after curing.

[0112] Specifically, various data acquired by the experimental module will be collected by the data collection unit through wireless transmission.

[0113] Furthermore, the calculation module includes a data acquisition unit, a calculation unit and a storage unit. The data acquisition unit is used to collect various parameters generated by the experimental module during the experiment. The calculation unit is used to calculate various indicator values ​​based on the collected data of the data acquisition unit. The storage unit is used to store the calculation results of the calculation unit and the corresponding thresholds of various indicators.

[0114] The beneficial effects of this solution are as follows: 1. By setting up various experiments to test the performance of the produced epoxy bottom filling glue, and at the same time, by setting various indicators to measure the performance of various aspects of the filling glue sample, rather than comparing a single experimental data with its corresponding threshold, it is conducive to comprehensively measuring the performance of the filling glue and digitizing the measurement results, which is conducive to the staff to judge whether the performance of the filling glue is qualified based on the indicator value.

[0115] 2. The change rate of parameters under different circumstances is introduced in the calculation process of the indicators, which is conducive to understanding the change of parameters under different circumstances, so as to judge their stability and to more comprehensively reflect the performance of the filling glue.

[0116] Embodiment 2: This embodiment should be understood to include all the features of any of the above embodiments, and further improve on the basis thereof, and also includes a method for adjusting the ratio of each raw material according to the calculation results of each index, comprising the following steps:

[0117] Calculate the proportion of the adjusted coupling agent to the raw material according to the following formula:

[0118]

[0119] Among them, OLJ is the proportion of the coupling agent in the raw material after adjustment, olj is the proportion of the coupling agent in the raw material before adjustment, k1 is the coupling agent adjustment weight, Q is the corresponding threshold value of the glass transition temperature, and q is the detection value of the glass transition temperature.

[0120] Calculate the proportion of the adjusted conductive black glue in the raw materials according to the following formula:

[0121]

[0122] Among them, DDHJ is the proportion of conductive black glue in the raw material after adjustment, ddhj is the proportion of conductive black glue in the raw material before adjustment, k2 is the adjustment weight of conductive black glue, J is the corresponding threshold value of dielectric constant, and j is the detection value of dielectric constant.

[0123] Calculate the proportion of the adjusted filler to the raw material according to the following formula:

[0124]

[0125] Among them, TL is the proportion of filler in the raw material after adjustment, tl is the proportion of filler in the raw material before adjustment, k3 is the filler adjustment weight, N is the corresponding threshold of viscosity, n is the detection value of viscosity, QDXN is the strength performance index, and YQDXN is the corresponding threshold of the strength performance index.

[0126] The proportion of the adjusted accelerator to the raw material is calculated according to the following formula:

[0127]

[0128] Among them, CJJ is the proportion of the accelerator in the raw material after adjustment, cjj is the proportion of the accelerator in the raw material before adjustment, k4 is the accelerator adjustment weight, Q is the corresponding threshold of the glass transition temperature, q is the detection value of the glass transition temperature, YGHXN is the corresponding threshold of the curing performance index, and GHXN is the curing performance index.

[0129] Calculate the proportion of the adjusted curing agent to the raw material according to the following formula:

[0130]

[0131] Among them, GHJ is the proportion of the adjusted curing agent in the raw material, ghj is the proportion of the curing agent in the raw material before adjustment, k5 is the curing agent adjustment weight, Q is the corresponding threshold of the glass transition temperature, q is the detection value of the glass transition temperature, YGHXN is the corresponding threshold of the curing performance index, and GHXN is the curing performance index.

[0132] Specifically, k1, k2, k3, k4, and k5 can be 0.2 times the difference between the maximum and minimum values ​​of the range values ​​corresponding to their corresponding materials (20 to 30 parts of epoxy resin mixture, 0.5 to 0.8 parts of coupling agent, 0.6 to 1 part of conductive black glue, 66 to 74 parts of filler, 0.5 to 1 part of accelerator and 8 to 14 parts of curing agent by weight).

[0133] Specifically, when the calculated adjusted raw material proportion exceeds the given range value, the final result of the adjusted raw material proportion is changed to the boundary value in the given range value that is closest to the calculated result; for example, if the calculated result is that the adjusted coupling agent accounts for 1 part of the raw material, then from the given range value (0.5 to 0.8 parts), the closest boundary value is selected as the final result, that is, 0.8 parts.

[0134] Specifically, the above adjustment weight is set between 0 and 1 by technical personnel in this field according to the desired adjustment range each time the raw material ratio is adjusted. An optional value setting method for the above adjustment weight is: the ratio of the number of corresponding raw materials in this production to the total number of all raw materials.

[0135] The beneficial effects of this embodiment are as follows: the adjustment value of each raw material ratio is obtained according to the calculation results of various indicators, which is conducive to adjusting the raw material ratio according to the analysis results of the performance of the filling glue sample, and producing the corresponding epoxy bottom filling glue according to the adjusted ratio. By comparing the various indicators of the filling glue produced twice, it is helpful to judge whether the effect of the adjusted ratio is good.

[0136] The above disclosed contents are only preferred feasible embodiments of the present invention, and do not limit the protection scope of the present invention. Therefore, all equivalent technical changes made by using the contents of the present invention specification and drawings are included in the protection scope of the present invention. In addition, the elements therein can be updated with the development of technology. The above units are only examples. Those skilled in the art can use corresponding units according to different designs according to actual needs when implementing this solution.

Claims

1. A method for preparing epoxy bottom filling glue for enhancing the bonding strength of FPC, characterized in that: The following steps are involved: S1, mixing the epoxy resin mixture, the coupling agent and the conductive black glue, and stirring them in a vacuum environment for 0.5 to 1 hour to obtain a first mixture; S2, adding a filler to the first mixture, heating it to 70 to 90 degrees Celsius, and stirring it in a vacuum environment for 6 to 10 hours, and then lowering the temperature to room temperature to obtain a second mixture; S3, adding an accelerator and a curing agent to the second mixture, stirring the mixture under a vacuum condition of 25 to 30 degrees Celsius for 1.5 to 2 hours, and obtaining an epoxy underfill adhesive after the stirring is completed; S4, conduct various performance tests on the epoxy underfill; S5, obtaining various performance indicators of the epoxy underfill glue according to the experimental data of various performance experiments, and judging whether the epoxy underfill glue produced at that time is qualified according to the obtained performance indicators; The performance indicators include curing performance indicators, strength performance indicators and comprehensive performance indicators.

2. The method for preparing an epoxy bottom filling adhesive for enhancing the adhesion of FPC according to claim 1, characterized in that: The raw materials used to prepare the epoxy bottom filling glue include 20-30 parts of epoxy resin mixture, 0.5-0.8 parts of coupling agent, 0.6-1 parts of conductive black glue, 66-74 parts of filler, 0.5-1 parts of accelerator and 8-14 parts of curing agent in a weight ratio.

3. The method for preparing an epoxy bottom filling adhesive for enhancing the bonding strength of FPC according to claim 2, characterized in that: The epoxy resin mixture comprises 5-8 parts of naphthalene epoxy resin, 1-2 parts of multifunctional epoxy resin, 10-14 parts of bisphenol epoxy resin and 4-6 parts of toughening epoxy resin in proportion by weight, and the filler is a spherical filler.

4. The method for preparing an epoxy bottom filling adhesive for enhancing the bonding strength of FPC according to claim 3, characterized in that: The performance tests of epoxy underfill include the following steps: S41, obtaining a filling glue sample, and measuring the viscosity of the filling glue sample at room temperature by using a viscometer; S42, obtaining the time required for the filling glue sample to be completely cured under different temperature conditions; S43, measuring the dielectric constant of the cured filling glue sample by a dielectric constant measuring instrument; S44, measuring the glass transition temperature of the cured filling glue sample by dynamic mechanical analysis; S45, compressing and shearing the cured filling glue sample, and collecting various parameters generated during the compression and shearing process.

5. The method for preparing epoxy bottom filling glue for enhancing the bonding strength of FPC according to claim 4, characterized in that: Obtaining the performance indicators of epoxy underfill includes the following steps: S51, calculating the curing performance index according to the time required for the filling glue sample to be completely cured under different temperature conditions; S52, calculating strength performance index according to various parameters generated during compression and shearing; S53, calculating the comprehensive performance index according to various data generated during the experiment.

6. The method for preparing epoxy bottom filling glue for enhancing the bonding strength of FPC according to claim 5, characterized in that: Also included is an epoxy underfill preparation system for implementing the epoxy underfill preparation method, the system comprising a preparation module, an experimental module and a calculation module, the preparation module is used to prepare the epoxy underfill, the experimental module is used to perform various performance experiments on the produced epoxy underfill, and the calculation module is used to calculate various performance indicators of the produced epoxy underfill according to the experimental results of the experimental module; The preparation module includes a raw material storage unit, a mixing container, a stirring unit and a heating unit. The raw material storage unit stores various raw materials required for preparing epoxy bottom filling glue, the mixing container is used to mix various containers, the stirring unit is used to stir the various raw materials in the mixing container, and the heating unit is used to heat the various raw materials in the mixing container.

7. The method for preparing epoxy bottom filling glue for enhancing the bonding strength of FPC according to claim 6, characterized in that: The experimental module includes a viscometer, a dielectric constant measuring instrument, a dynamic thermomechanical analyzer, a temperature adjustment unit, a timer, a pressure unit, a shear unit, a force detection unit and an image acquisition unit. The viscometer is used to measure the viscosity of the filling glue sample, the dielectric constant measuring instrument is used to detect the dielectric constant of the filling glue sample, the dynamic thermomechanical analyzer is used to detect the glass ring transition temperature of the filling glue sample, the temperature adjustment unit is used to adjust the temperature of the curing process of the filling glue sample, the timer is used to calculate the curing time of the filling glue sample, the pressure unit is used to compress the filling glue sample, the shear unit is used to shear the filling glue sample, the force detection unit is used to detect the force applied by the pressure unit and the shear unit, and the image acquisition unit is used to acquire the deformation degree of the filling glue sample during the compression and shearing process and the image of the filling glue sample before and after curing; the data collected by the viscometer, the dielectric constant measuring instrument, the dynamic thermomechanical analyzer, the temperature adjustment unit, the timer, the pressure unit, the shear unit, the force detection unit and the image acquisition unit will be transmitted to the data acquisition unit by wireless transmission.

8. The method for preparing epoxy bottom filling glue for enhancing the bonding strength of FPC according to claim 7, characterized in that: The calculation module includes a data acquisition unit, a calculation unit and a storage unit. The data acquisition unit is used to collect various parameters generated by the experimental module during the experiment. The calculation unit is used to calculate various indicator values ​​according to the collected data of the data acquisition unit. The storage unit is used to store the calculation results of the calculation unit and the corresponding threshold values ​​of various indicators.

Images