Method for measuring glass transition temperature of copper clad laminate

Abstract

The application discloses a kind of copper-clad plate glass transition temperature measurement methods, scrape copper-clad plate powder and dry;Copper-clad plate powder is mixed with high-temperature calcination industrial-grade alumina powder and potassium bromide and is ground to obtain copper-clad plate mixed powder, and after copper-clad plate mixed powder is pressed in mould, it is taken out and cut and polished into the copper-clad plate mixed sample of specified size;Industrial-grade alumina powder after calcination and potassium bromide are pressed in mould, and after being taken out and cut and polished, it is the reference of specified size;Through temperature program, the DSC curve of copper-clad plate mixed sample and reference DSC curve are tested, then analysis obtains copper-clad plate glass transition temperature Tg.The method can measure the copper-clad plate sample of various different appearance sizes, while the influence of copper-clad plate thickness on DSC test Tg can be excluded, with the advantages of simple operation, low test cost, high accuracy and the like.

Description

Technical Field

[0001] This invention relates to copper clad laminate performance testing technology, and particularly to a method for measuring the glass transition temperature of copper clad laminates. Background Technology

[0002] Copper-clad laminates (CCLs), as one of the fundamental materials in the electronics industry, are an important raw material for the production of printed circuit boards (PCBs) and are currently widely used in many fields such as mobile phones, computers, and servers. With the development of technology, the performance of electronic products is constantly improving, thus placing higher demands on the performance of circuit boards and CCLs. The glass transition temperature (Tg) is an important performance indicator of CCLs, referring to the temperature at which the cured resin in the CCL transforms from a glassy state to a highly elastic state after heating. When the temperature exceeds this value, the resin layer and the entire CCL will exhibit significant softening, leading to a decrease in strength. Therefore, this temperature is of great reference value for the processing and use of CCLs.

[0003] Currently, commonly used methods for measuring the glass transition temperature of copper-clad laminates include dilatometer methods and thermal analysis methods. Among these, thermal analysis methods are widely used due to their high accuracy, good reproducibility, and ease of operation, and specific test methods are provided for reference in standards such as the International Electron Industries Connection (IPC). However, due to the rapid development of copper-clad laminate related technologies, some problems also exist in the actual testing process of IPC standard test methods.

[0004] Currently, the main thermal analysis methods for detecting Tg in the industry include differential scanning calorimetry (DSC), dynamic thermomechanical analysis (DMA), and thermomechanical analysis (TMA).

[0005] The DMA test method requires the material to be subjected to periodic stress, which places certain requirements on the material's strength. The TMA test method tests the process of material deformation under heat, which places certain requirements on the material's size. The external dimensions of the sample to be tested are limited by the test principle and the sensitivity of the instrument, and it needs to have a large thickness.

[0006] The Differential Scanning Calorimeter (DSC) method measures the power difference (e.g., in the form of heat) input to the sample and reference material relative to temperature under programmed temperature control. The curve recorded by the DSC is called the DSC curve. It plots the rate of heat absorption or release (dH / dt, in millijoules per second) on the ordinate and temperature (T) or time (t) on the abscissa. It can measure various thermodynamic and kinetic parameters, such as specific heat capacity, heat of reaction, heat of transformation, phase diagrams, reaction rates, crystallization rates, polymer crystallinity, and sample purity. This method has a wide operating temperature range (-175 to 725°C), high resolution, and requires small sample volumes, making it suitable for the analysis of inorganic substances, organic compounds, and pharmaceuticals.

[0007] The Direct Scaling (DSC) method has relatively low sample requirements and can test powders, chips, thin / thick plates, and even irregular samples. It is currently the most widely used thermal analysis method for testing the glass transition temperature (Tg). Because it measures the enthalpy change of a material, it requires the material to have good uniformity and thermal conductivity. When using the traditional DSC method to test the glass transition temperature of copper-clad laminates (CCLs), the results are affected by the different thicknesses and glass cloth structures of different CCLs. Since the thermal conductivity of the resin layer in CCLs is relatively low, thicker boards generally have higher Tg temperatures. This leads to differences in test results for different samples with the same resin composition, affecting the judgment of the actual application temperature range of CCLs and resulting in relatively lower accuracy compared to the previous two methods. Therefore, improving the testing method to enhance the sensitivity and accuracy of DSC testing is of great significance.

[0008] The IPC testing standard provides reference testing methods for grinding or filing samples. However, directly testing the resin powder of copper-clad laminate samples also presents certain problems. On the one hand, increasing the sample amount is necessary to improve the sensitivity of DSC testing. However, the low thermal conductivity of resin powder means that excessively thick samples will also increase the measured Tg, making it difficult to reflect the actual Tg of the resin layer. On the other hand, the finely filed, dried, and fully cured resin powder is loose and difficult to mold, making it difficult to directly press and transfer it to the DSC test sample tray. Pressing the resin powder directly into the sample tray is problematic. Insufficient pressure will result in voids that affect the test results, while excessive pressure will damage the sample tray.

[0009] Adding an inert reference material can improve the thermal conductivity of the sample and the sensitivity of DSC testing. However, the cost and purity of the inert reference material must be considered. High-purity materials are too expensive and not conducive to their use in industrial production. On the other hand, low-cost industrial products are not pure enough and may react with resin powder to generate additional enthalpy, which may interfere with the DSC test results. Summary of the Invention

[0010] The technical problem to be solved by the present invention is to provide a method for determining the glass transition temperature of copper clad laminates (CCLs). This method can measure CCL samples with various appearances and sizes, thus expanding the testing range. At the same time, it can eliminate the influence of CCL thickness and structure on the glass transition temperature (Tg) of CCLs measured by DSC, reflecting the true glass transition temperature of the resin layer. The method is simple to operate, has low testing cost, good reproducibility and stability, and high accuracy.

[0011] To solve the above-mentioned technical problems, the present invention provides a method for measuring the glass transition temperature of copper-clad laminates, which includes the following steps:

[0012] S1. After removing the surface copper foil of the copper-clad laminate by etching, scrape off the copper-clad laminate powder and dry it;

[0013] Industrial-grade alumina powder and potassium bromide are subjected to high-temperature calcination.

[0014] S2. Mix and grind copper-clad laminate powder with industrial-grade alumina powder and potassium bromide after high-temperature calcination to obtain copper-clad laminate mixed powder. Press the copper-clad laminate mixed powder in a mold, take it out and cut and grind it into copper-clad laminate mixed samples of specified size, and put them into a sample tray.

[0015] After calcination, industrial-grade alumina powder and potassium bromide are pressed together in a mold, then removed, cut and polished into reference samples of specified sizes, and placed in a reference tray.

[0016] S3. By using a heating program, test the DSC curves of the copper-clad laminate mixed sample and the reference sample, and then analyze to obtain the glass transition temperature Tg of the copper-clad laminate.

[0017] Preferably, the industrial-grade alumina powder is spherical, near-spherical, or composite in shape, with a particle size of 1μm to 100μm.

[0018] Preferably, in step S1, industrial-grade alumina powder and potassium bromide are subjected to high-temperature calcination treatment at a temperature of 250℃ to 800℃ for a time of 1h to 8h.

[0019] Preferably, in step S1, the temperature for drying the scraped copper-clad laminate powder is 80℃~200℃, and the time is 0.5h~8h.

[0020] Preferably, in step S2, the copper-clad laminate powder is mixed and ground with calcined industrial-grade alumina powder and potassium bromide to obtain a mixed copper-clad laminate powder, wherein the mass ratio of alumina, potassium bromide and copper-clad laminate sample powder is 1:1:3 to 5:5:1.

[0021] Preferably, in step S2, the copper-clad laminate mixture powder is pressed in a mold, and the pressure during the pressing process is controlled to be 10MPa to 100MPa and held for 30s to 120s. Then, it is taken out and cut and polished into a copper-clad laminate mixture sample of a specified size.

[0022] Preferably, in step S2, the calcined industrial-grade alumina powder and potassium bromide are pressed together in a mold at a mass ratio of 1:1, then removed, cut, and polished into a reference product of a specified size.

[0023] Preferably, in step S3, the heating program is a dual-scan program. First, the copper-clad laminate mixed sample and the reference are heated to 80℃~(Tg′-20)℃ at a heating rate of 5℃ / min~25℃ / min, then cooled to 25℃~50℃ and held at a constant temperature for 1min~7min. Then, the copper-clad laminate mixed sample and the reference are heated to (Tg′+20)℃~(Tg′+50)℃ at a heating rate of 5℃ / min~25℃ / min. Then, the glass transition temperature Tg of the copper-clad laminate is read from the DSC curve of the copper-clad laminate mixed sample and the reference using the midpoint method, referring to the measurement method of IPC-TM-650 2.4.25.

[0024] Tg′ is the reference glass transition temperature, a rough value obtained by direct measurement of the copper-clad laminate sample.

[0025] Preferably, the DSC testing instrument used is the TA Q20DSC tester, and the fixed test conditions are: copper-clad laminate mixed sample of 28mg to 30mg, sample tray of aluminum tray, protective gas of nitrogen, and protective gas flow rate of 50mL / min.

[0026] The method for determining the glass transition temperature of copper-clad laminates (CCLs) of this invention employs a thermal analysis method. It involves scraping CCL sample powder and testing the DSC curve. Compared to traditional DMA, TMA, and direct DCS measurement methods, this method can measure CCL samples of various sizes and shapes, expanding the testing range. Simultaneously, it eliminates the influence of CCL thickness on the CCL glass transition temperature (Tg) measured by DSC, reflecting the true glass transition temperature of the resin layer. This method is simple to operate, has low testing costs, and provides good reproducibility, stability, and accuracy. Attached Figure Description

[0027] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the present invention 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.

[0028] Figure 1 This is a schematic flowchart of an embodiment of the method for determining the glass transition temperature of copper-clad laminates according to the present invention.

[0029] Figure 2 These are the DSC spectra of Experimental examples one and two;

[0030] Figure 3 These are the DSC spectra of comparative examples one and two;

[0031] Figure 4These are the DSC spectra of Comparative examples three and four. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] The terms "first," "second," and similar words used in this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Words such as "including" or "comprising" mean that the element or object preceding the word encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," "right," "front," and "back" are used only to indicate relative positional relationships; these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0034] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0035] Example 1

[0036] A method for determining the glass transition temperature of copper-clad laminates, such as... Figure 1 As shown, it includes the following steps:

[0037] S1. After removing the surface copper foil of the copper-clad laminate by etching, scrape off the copper-clad laminate powder with a specific tool and dry it;

[0038] Industrial-grade alumina powder and potassium bromide are subjected to high-temperature calcination.

[0039] S2. Mix and grind copper-clad laminate powder with industrial-grade alumina powder and potassium bromide after high-temperature calcination to obtain copper-clad laminate mixed powder. Press the copper-clad laminate mixed powder in a mold, take it out and cut and grind it into copper-clad laminate mixed samples of specified size, and put them into a sample tray.

[0040] After calcination, industrial-grade alumina powder and potassium bromide are pressed together in a mold, then removed, cut and polished into reference samples of specified sizes, and placed in a reference tray.

[0041] S3. By designing a special heating program, the DSC curves of the copper-clad laminate mixed sample and the reference sample were tested, and then the glass transition temperature Tg of the copper-clad laminate was obtained by analysis.

[0042] Preferably, the industrial-grade alumina powder has a spherical, near-spherical, or composite shape, with a particle size of 1 μm to 100 μm. This shape and particle size of the alumina powder allows for thorough mixing with potassium bromide and resin powder to form a uniform, tightly packed mixture with good thermal conductivity.

[0043] Industrial-grade alumina powder and potassium bromide were chosen as inert references because alumina has a high thermal conductivity and is widely used in the copper clad laminate industry. It is also low in cost and readily available. Potassium bromide has good chemical stability and is easy to compress and form, which is beneficial for subsequent sample preparation. Moreover, using industrial-grade alumina powder and potassium bromide as inert references is low in cost, and the influence of impurities on DSC measurements can be completely removed through high-temperature calcination.

[0044] The method for determining the glass transition temperature of copper-clad laminate (CCL) in Example 1 employs a thermal analysis method. This method involves scraping CCL sample powder and testing the DSC curve. Compared to traditional DMA, TMA, and direct DCS measurement methods, it can measure CCL samples of various sizes and shapes, expanding the testing range. Simultaneously, it eliminates the influence of CCL thickness on the CCL glass transition temperature (Tg) measured by DSC, reflecting the true glass transition temperature of the resin layer. This method is simple to operate, has low testing costs, good reproducibility and stability, and high accuracy.

[0045] Example 2

[0046] Based on the method for determining the glass transition temperature of copper-clad laminate in Example 1, in step S1, industrial-grade alumina powder and potassium bromide are subjected to high-temperature calcination treatment at a temperature of 250°C to 800°C for a time of 1 to 8 hours.

[0047] The inert reference material, industrial-grade alumina powder, and potassium bromide, can be effectively removed by calcination under these conditions, thus eliminating interference with DSC testing.

[0048] Example 3

[0049] Based on the method for determining the glass transition temperature of copper-clad laminate in Example 1, in step S1, the temperature for drying the scraped copper-clad laminate powder is 80℃~200℃, and the time is 0.5h~8h.

[0050] These drying conditions effectively remove moisture from the copper-clad laminate sample powder, eliminating its interference with DSC testing, and yield a fluffy solid, which is beneficial for subsequent grinding and mixing.

[0051] Example 4

[0052] Based on the method for determining the glass transition temperature of copper-clad laminate in Example 1, in step S2, copper-clad laminate powder is mixed and ground with calcined industrial-grade alumina powder and potassium bromide to obtain copper-clad laminate mixed powder, wherein the mass ratio of alumina, potassium bromide and copper-clad laminate sample powder is 1:1:3 to 5:5:1.

[0053] Using this ratio is beneficial for obtaining copper clad laminate mixed samples with good thermal conductivity. The copper clad laminate mixed samples obtained after lamination have good formability and mechanical strength. If the alumina content is too low, the thermal conductivity of the copper clad laminate mixed sample is poor, and the measured Tg is too high. If the potassium bromide content is too low, the formability of the mixture is poor, and the strength of the block copper clad laminate mixed sample after lamination is low. It is easy to break when removing it from the mold and when grinding the edges. If the copper clad laminate powder content in the copper clad laminate mixed sample is too low, the glass transition of the DSC test results is not obvious, and it is too susceptible to interference from noise signals, which will reduce the sensitivity and accuracy of the test.

[0054] Preferably, in step S2, the calcined industrial-grade alumina powder and potassium bromide are pressed together in a mold at a mass ratio of 1:1, then removed, cut, and polished into a reference product of a specified size.

[0055] The method for determining the glass transition temperature of copper-clad laminate in Example 4 optimizes the ratio of inert reference material to copper-clad laminate powder in the copper-clad laminate mixed sample, which can improve the thermal conductivity and strength of the copper-clad laminate mixed sample and increase the accuracy and sensitivity of DSC test.

[0056] Example 5

[0057] Based on the method for determining the glass transition temperature of copper-clad laminate in Example 1, in step S2, the copper-clad laminate mixed powder is pressed in a mold, the pressure during the pressing process is controlled to be 10MPa~100MPa and held for 30s~120s, and then taken out and cut and polished into a copper-clad laminate mixed sample of a specified size.

[0058] The method of pre-pressing and compacting copper-clad laminate powder into a special mold, cutting and polishing it to the specified size, and then placing it into the sample tray can avoid damaging the sample tray and obtain a dense sample. Controlling the pressure during the pressing process to 10-100 MPa and holding it for 30-120 seconds can yield a dense sample block with high mechanical strength. Insufficient pressure and time may result in voids in the sample block, interfering with DSC testing, and may also cause breakage during subsequent cutting and polishing. Excessive pressure and time may damage the pressing fixture. After demolding, the sample is sanded to obtain a smooth surface and the powder adhering to the surface is wiped away to prevent burrs and powder from affecting the DSC test results.

[0059] The method for determining the glass transition temperature of copper-clad laminate in Example 5 optimizes the pressing and sample preparation process of copper-clad laminate mixed powder, which can obtain dense and regular appearance copper-clad laminate mixed samples, and improve the accuracy, reproducibility and sensitivity of DSC test results.

[0060] Example 6

[0061] Based on the method for determining the glass transition temperature of copper-clad laminate in Example 1, in step S3, the heating program is a dual-scan program. First, the copper-clad laminate mixed sample and the reference are heated to 80℃~(Tg′-20)℃ at a heating rate of 5℃ / min~25℃ / min, and then cooled to 25℃~50℃ and held at a constant temperature for 1min~7min. Then, the copper-clad laminate mixed sample and the reference are heated to (Tg′+20)℃~(Tg′+50)℃ at a heating rate of 5℃ / min~25℃ / min. Then, the glass transition temperature Tg of the copper-clad laminate is read from the DSC curve of the copper-clad laminate mixed sample and the reference using the midpoint method, referring to the measurement method of IPCTM2.4.25.

[0062] Tg′ is the reference glass transition temperature, a rough value obtained by direct measurement of the copper-clad laminate sample.

[0063] The method for determining the glass transition temperature of copper-clad laminate in Example 6 involves a low-temperature heating and cooling process to release the extra enthalpy value of special structures such as crystals generated during the preparation of the copper-clad laminate mixed sample. Setting a specified heating rate and maximum temperature ensures that the glass transition steps can be clearly and completely reflected through the second heating scan, thereby obtaining an accurate Tg.

[0064] The method for determining the glass transition temperature of copper-clad laminate in Example 6 uses a dual-scanning procedure to measure the DSC curve of the sample, which can eliminate the influence of the inert reference and the sample preparation process of the mixed copper-clad laminate on the DSC results, and improve the accuracy and reproducibility sensitivity of the DSC test results.

[0065] Example 7

[0066] Based on the method for determining the glass transition temperature of copper-clad laminate in Example 1, the DSC testing instrument used was a Q20DSC tester from TA Corporation. The fixed test conditions were as follows: the copper-clad laminate mixed sample was 28mg to 30mg, the sample pan was an aluminum pan, the protective gas was nitrogen, and the protective gas flow rate was 50mL / min.

[0067] Experimental Example 1

[0068] Industrial-grade alumina powder (spherical, 10μm particle size) and potassium bromide were calcined at 800℃ for 1 hour. After slight cooling, the powder was placed in a desiccator to cool to room temperature. The copper foil on the copper-clad laminate to be tested was etched off with sodium persulfate. After washing and cleaning the surface, about 0.10g of powder with a thickness of 0.2mm was scraped from the surface of the copper-clad laminate with a specified adhesive system using a special tool. This powder was dried at 120℃ for 2 hours and then mixed with the calcined alumina powder and potassium bromide at a mass ratio of 2:1:1 and ground evenly. The mixed powder was placed in a pressing mold and pressed on a hydraulic press with a pressure of 50MPa for 60s. After removing the pressure, the sample was cut with a blade and the edges were sanded to obtain the sample of the specified size. A sample block adapted to an aluminum DSC sample pan was placed in the pan and tested using a DSC analyzer. Similarly, a reference block was prepared by pressing calcined alumina and potassium bromide (total mass 0.05 g, mass ratio 1:1) together and placed in the reference pan. The heating program was set to a dual-scan program. First, the sample was heated to 80℃~130℃ (Tg′≈170℃) at a heating rate of 20℃ / min, then cooled to 45℃ and held at that temperature for 5 min. Then, the sample was heated to 210℃ at a heating rate of 20℃ / min. The accurate glass transition temperature Tg was then read from the DSC curve using the midpoint method, which was 161.22℃. The obtained DSC spectrum is shown in [reference needed]. Figure 2 .

[0069] Experimental Example 2

[0070] Industrial-grade alumina powder (spherical, 10 μm particle size) and potassium bromide were calcined at 800℃ for 1 hour. After slight cooling, the powder was placed in a desiccator to cool to room temperature. The copper foil on the copper-clad laminate to be tested was etched off with sodium persulfate. After washing and cleaning the surface, about 0.10 g of the same adhesive system as in Test Example 1 was scraped off with a special tool. The powder was dried at 120℃ for 2 hours and then mixed with the calcined alumina powder and potassium bromide at a mass ratio of 2:1:1 and ground evenly. The mixed powder was placed in a pressing mold and pressed on a hydraulic press at 50 MPa for 60 seconds. After removing the pressure, the sample was cut with a blade and sanded to obtain the final product. A sample block of suitable size for an aluminum DSC sample pan was placed in the pan and tested using a DSC analyzer. Similarly, a reference block was prepared by pressing calcined alumina and potassium bromide (total mass 0.05 g, mass ratio 1:1) together and placed in the reference pan. A dual-scan heating program was set. The sample was first heated to 80℃~130℃ (Tg′≈170℃) at a heating rate of 20℃ / min, then cooled to 45℃ and held at that temperature for 5 min. The sample was then heated to 210℃ at a heating rate of 20℃ / min. The accurate glass transition temperature Tg was then read from the DSC curve using the midpoint method, which was 161.07℃. The obtained DSC spectrum is shown in [reference needed]. Figure 2 .

[0071] Comparative Example 1

[0072] The DSC curves of a 0.2 mm thick copper-clad laminate with the same adhesive system as the one used in Example 1 were directly measured. Other processing methods were the same as in Example 1. The glass transition temperature Tg was 167.24℃. The obtained DSC spectra are shown in [reference needed]. Figure 3 .

[0073] Comparative Example 2

[0074] The DSC curves of a 1.0 mm thick copper-clad laminate with the same adhesive system as the one used in Example 1 were directly measured. Other processing methods were the same as in Example 1. The glass transition temperature Tg was 171.36℃. The obtained DSC spectra are shown in [reference needed]. Figure 3 .

[0075] Comparative Example 3

[0076] The copper-clad laminate used was the same 0.2 mm thick as in Example 1. No alumina was added to the inert reference. Other treatment methods were the same as in Example 1. The glass transition temperature (Tg) was 170.24 °C. The obtained DSC spectrum is shown in [reference needed]. Figure 4 .

[0077] Comparative Example 4

[0078] The copper-clad laminate used was the same 0.2 mm thick as in Example 1. The heating program was a single-scan program, meaning there was no step of heating to a lower temperature and then cooling down. The sample was directly heated to 210 °C at a heating rate of 20 °C / min. Other processing methods were the same as in Example 1. The glass transition temperature Tg was 177.83 °C. The obtained DSC spectrum is shown in [reference needed]. Figure 4 .

[0079] To verify that the test method of the present invention can accurately measure the glass transition temperature of copper-clad laminate mixed samples, four comparative examples were set up relative to Test Example 1 and Test Example 2. Comparative Examples 1 and 2 directly tested the DSC curves of copper-clad laminates of different thicknesses, and the heating program was the same as that of Test Example 1. In Comparative Example 3, no alumina was added to the inert reference, and other test conditions were the same as those of Test Example 1. In Comparative Example 4, only a single scan program was set, and other test conditions were the same as those of Test Example 1. Comparing the DSC curves obtained by each method, it can be seen that there are significant differences in the Tg values ​​of Comparative Example 1, Comparative Example 2, and Comparative Example 3. The Tg values ​​of Experimental Example 1 and Experimental Example 2 are basically the same. This is because the test results are biased due to the low thermal conductivity of the pure copper-clad laminate resin in the comparative test samples. Adding alumina can significantly improve this problem. However, the DSC curve of Comparative Example 4 shows obvious fluctuations, and the Tg value differs significantly from other test results. This may be due to the influence of the crystallization enthalpy of the inert reference material. Using the measurement method adopted in this invention, the DSC curves obtained in Experimental Example 1 and 2 are smooth and have similar glass transition temperatures, which can accurately measure the glass transition temperature of the copper-clad laminate.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for measuring the glass transition temperature of copper-clad laminates, characterized in that, Includes the following steps: S1. After removing the surface copper foil of the copper-clad laminate by etching, scrape off the copper-clad laminate powder and dry it; Industrial-grade alumina powder and potassium bromide are subjected to high-temperature calcination treatment at a temperature of 250℃~800℃ for 1h~8h. S2. The copper-clad laminate powder is mixed and ground with industrial-grade alumina powder and potassium bromide after high-temperature calcination to obtain copper-clad laminate mixed powder, wherein the mass ratio of alumina, potassium bromide and copper-clad laminate sample powder is 1:1:3 to 5:5:1; the copper-clad laminate mixed powder is pressed in a mold, then taken out and cut and polished into copper-clad laminate mixed samples of specified size, and placed in a sample tray. After calcination, industrial-grade alumina powder and potassium bromide are pressed together in a mold, then removed, cut and polished into reference samples of specified sizes, and placed in a reference tray. S3. By using a heating program, test the DSC curves of the copper-clad laminate mixed sample and the reference sample, and then analyze to obtain the glass transition temperature Tg of the copper-clad laminate.

2. The method for measuring the glass transition temperature of copper-clad laminate according to claim 1, characterized in that, The industrial-grade alumina powder is spherical, near-spherical, or composite in shape, with a particle size of 1μm to 100μm.

3. The method for measuring the glass transition temperature of copper-clad laminate according to claim 1, characterized in that, In step S1, the temperature for drying the scraped copper-clad laminate powder is 80℃~200℃, and the time is 0.5h~8h.

4. The method for measuring the glass transition temperature of copper-clad laminate according to claim 1, characterized in that, In step S2, the copper-clad laminate mixture powder is pressed in a mold, and the pressure during the pressing process is controlled to be 10 MPa to 100 MPa and held for 30s to 120s. Then, it is taken out and cut and polished into a copper-clad laminate mixture sample of the specified size.

5. The method for measuring the glass transition temperature of copper-clad laminate according to claim 1, characterized in that, In step S2, the calcined industrial-grade alumina powder and potassium bromide are pressed together in a mold at a mass ratio of 1:1, then removed, cut, and polished into a reference sample of a specified size.

6. The method for measuring the glass transition temperature of copper-clad laminate according to claim 1, characterized in that, In step S3, the heating program is a dual-scan program. First, the copper-clad laminate mixed sample and the reference are heated to 80℃~(Tg´-20)℃ at a heating rate of 5℃ / min~25℃ / min, then cooled to 25℃~50℃ and held at a constant temperature for 1 min~7 min. Then, the copper-clad laminate mixed sample and the reference are heated to (Tg´+20)℃~(Tg´+50)℃ at a heating rate of 5℃ / min~25℃ / min. Then, the glass transition temperature Tg of the copper-clad laminate is read from the DSC curve of the copper-clad laminate mixed sample and the reference using the midpoint method, referring to the measurement method of IPC-TM-650 2.4.

25. Tg´ is the reference glass transition temperature, a rough value obtained by directly measuring the copper-clad laminate sample in advance.

7. The method for measuring the glass transition temperature of copper-clad laminate according to claim 1, characterized in that, The DSC testing instrument used was the TA Q20 DSC tester. The fixed test conditions were: 28mg to 30mg of copper-clad laminate mixed sample, aluminum sample tray, nitrogen protective gas, and a protective gas flow rate of 50mL / min.

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