Method for analyzing fillers in copper-clad plate samples by infrared spectroscopy

Abstract

The application discloses a method for analyzing fillers in a copper-clad plate sample by using infrared spectroscopy. Firstly, a resin-filler mixture powder on the copper-clad plate is scraped; then the mixture powder is calcined at high temperature to obtain mixture residual ash; the mixture residual ash is mixed with potassium bromide and uniformly ground, and then tabletting is carried out to prepare a light-transmitting sample tablet; finally, the infrared spectrum of the light-transmitting sample tablet is tested by using an infrared spectrometer, and the chemical composition of the fillers in the copper-clad plate sample is obtained by analyzing the infrared spectrum of the light-transmitting sample tablet. The method for analyzing fillers in a copper-clad plate sample by using infrared spectroscopy can improve the accuracy and reproducibility of the analysis result.

Description

Technical Field

[0001] This invention relates to copper clad laminate (CCL) production technology, and in particular to a method for analyzing fillers in CCL samples using infrared spectroscopy. Background Technology

[0002] Fillers have a significant impact on the cost and performance of copper-clad laminates (CCLs). Since using inorganic fillers can reduce the production cost of CCLs and improve their heat resistance, thermal conductivity, and mechanical strength, the analysis and identification of inorganic fillers in CCLs is an important research direction. However, because common inorganic fillers are mostly inert substances such as sparingly soluble metal salts and metal oxides, they are unlikely to react chemically with general analytical reagents. Therefore, current analytical methods for fillers are mainly spectroscopic analysis methods, which can be broadly categorized as follows:

[0003] Optical microscopy analysis: This method is currently mainly used to analyze the appearance and shape of fillers and their dispersion in copper-clad laminates. With visible light as a medium, the appearance of fillers and the interface between them and the copper-clad laminate resin can be observed. However, it is difficult to distinguish the interior of opaque fillers and even the basic chemical composition of fillers. It can only analyze the morphology of fillers but cannot analyze their specific material composition.

[0004] X-ray diffraction (XRD) spectroscopy: This method is currently mainly used to analyze the crystal structure and relative content of various phases in copper-clad laminates. Because X-rays have stronger penetrating power than visible light, this method can be used to analyze opaque samples. The obtained X-ray diffraction spectra can be analyzed by searching PDF (Powder Diffraction File) cards to identify specific crystalline substances. Furthermore, the peak heights of the diffraction peaks can be used to calculate the specific content of the substances using methods such as the "K-value method." However, currently, PDF cards do not completely cover all substances, and X-rays pose a certain radiation hazard, which also limits its widespread application in the production field. In addition, XRD diffractometers are relatively expensive.

[0005] Energy dispersive spectroscopy (EDS): This method can currently qualitatively and semi-quantitatively analyze the types and contents of elements in the micro-area of ​​copper clad laminates. It can quickly analyze samples with minimal damage. However, the energy spectra of complex substances often have problems such as peak overlap leading to incorrect element identification. Furthermore, the high price of EDS spectra further limits its practical application.

[0006] Infrared spectroscopy analysis: This method can currently provide relatively accurate qualitative analysis of the composition of copper-clad laminates. However, due to the weak penetrating power of infrared light and the generally strong infrared absorption of organic matter, direct analysis of fillers using infrared spectroscopy is rarely applied. Furthermore, test samples must be prepared and specially treated before infrared spectroscopy analysis. Currently, there are four main methods for preparing infrared spectroscopy test samples:

[0007] Solid compression method: The fine powder of a solid sample is uniformly dispersed in a medium such as potassium bromide and then pressed into a transparent sheet. Copper-clad laminates have high strength after hot pressing and contain glass fibers, making them difficult to grind. Therefore, direct solid compression is not effective.

[0008] Coating method: This method is only applicable to liquid samples. Copper-clad laminates form a cross-linked network after being heated and cured, which cannot be melted or dissolved, so this method cannot be used for sample preparation.

[0009] Hot-press film method: This method is only suitable for samples that can be heat-fused, but samples that cannot be heat-fused cannot be prepared using this method. Copper-clad laminates are heat-cured and belong to the category of samples that are difficult to heat-fuse and hot-press.

[0010] ATR method: This method can only detect the surface structure of a material. Copper-clad laminates may have an uneven structure after processing, making accurate detection difficult.

[0011] Traditional infrared analysis sample preparation methods for copper-clad laminates (CCLs) face two challenges: firstly, preparing relatively stable CCLs with high mechanical strength into testable samples; and secondly, eliminating interference from organic matter and glass fibers that coexist with the filler.

[0012] Traditional transmissive infrared (TIR) ​​pelleting methods typically involve manual sample preparation, which often introduces significant random errors, such as water vapor in the air, opacity of the pellet, and unevenness during compression.

[0013] In addition, the infrared spectrum of the mixture is quite complex, and the peaks of the mixed filler components are very likely to overlap, which can cause significant interference in the determination of peak assignment. Simply searching the standard spectrum library based on the peak value may lead to misjudgment. Summary of the Invention

[0014] The technical problem to be solved by the present invention is to provide a method for analyzing fillers in copper-clad laminate samples using infrared spectroscopy, which can improve the accuracy and reproducibility of the analysis results.

[0015] To solve the above-mentioned technical problems, the present invention provides a method for analyzing fillers in copper-clad laminate samples using infrared spectroscopy, which includes the following steps:

[0016] S1. Scrape the resin-filler mixture powder off the copper-clad laminate;

[0017] S2. The mixture powder is calcined at high temperature to obtain residual ash from the mixture;

[0018] S3. After mixing and grinding the residual ash of the mixture with potassium bromide until uniform, the mixture is compressed into tablets to obtain a transparent sample.

[0019] S4. Measure the infrared spectrum of the transparent sample with an infrared spectrometer, and analyze the infrared spectrum of the transparent sample to obtain the chemical composition of the filler in the copper-clad laminate sample.

[0020] Preferably, in step S1, the copper foil on the surface of the copper-clad laminate is first removed by etching, and then the resin-filler mixture powder on the copper-clad laminate is scraped off with a tool.

[0021] Preferably, in step S2, the obtained mixture powder is first subjected to high-temperature drying treatment, and then the mixture powder is calcined at high temperature.

[0022] Preferably, in step S2, the temperature for high-temperature drying of the obtained mixture powder is 80℃~200℃, and the time is 0.5~8h.

[0023] The mixture powder is placed in a muffle furnace and calcined at a high temperature of 250℃~800℃ for 1~8h.

[0024] Preferably, in step S3, the potassium bromide is dried before mixing and grinding with the residual ash in the mixture.

[0025] Preferably, in step S3, the potassium bromide drying temperature is 80–200°C and the drying time is 2–6 hours.

[0026] In step S3, the weight ratio of residual ash in the mixture to potassium bromide is 1:50 to 1000.

[0027] Preferably, in step S3, the pressure of the tablet is 100-300 MPa and the pressure is maintained for 30-120 s to obtain the transparent sample.

[0028] Preferably, in step S4, the infrared spectrum of the transparent sample is searched using infrared software to obtain a standard spectrum and the infrared spectrum search results are analyzed and verified to obtain the chemical composition of the filler in the copper-clad laminate sample.

[0029] Preferably, the method for analyzing and verifying the infrared spectral search results is one or more of the following: peak resolution, difference spectrum, and spectrum addition.

[0030] A preferred method for analyzing and verifying the infrared spectral search results is as follows:

[0031] Based on the characteristic peak values ​​of the infrared absorption peaks in the infrared spectrum of the transmitted sample, a search is performed in a standard spectral library to obtain the N compounds with the highest similarity to the infrared spectrum, where N is an integer greater than 1. The fitted infrared spectrum of the mixture is obtained by adding the spectra of the N compounds with the highest similarity.

[0032] The infrared spectrum of the fitted mixture is compared with the infrared spectrum of the transmitted sample for quality inspection. If the similarity between the two is greater than the set value, the chemical composition of the filler in the copper clad laminate sample is determined to be the N compounds.

[0033] The present invention provides a method for analyzing fillers in copper-clad laminate samples using infrared spectroscopy. The residual ash of the mixture obtained by high-temperature calcination of resin-filler mixture powder on the copper-clad laminate, which is free of organic matter, is mixed with potassium bromide, ground evenly, and then pressed into a tablet to obtain a transparent sample. This method can eliminate the influence of organic matter and glass fiber on the analysis results, and at the same time, it is beneficial to use the potassium bromide tableting method to prepare the sample, which can improve the accuracy and reproducibility of the analysis results. Attached Figure Description

[0034] 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.

[0035] Figure 1 This is a flowchart of an embodiment of the method for analyzing fillers in copper-clad laminate samples using infrared spectroscopy according to the present invention;

[0036] Figure 2 This is an example of the infrared spectrum of a transparent sample from an embodiment of the method for analyzing fillers in copper-clad laminate samples using infrared spectroscopy according to the present invention;

[0037] Figure 3 This is the infrared spectrum of talc.

[0038] Figure 4 It is the infrared spectrum of silicon dioxide;

[0039] Figure 5 It is the fitted infrared spectrum of the mixture;

[0040] Figure 6 It is a comparison of the infrared spectra of the transmitted sample and the infrared spectra of the fitted mixture. Detailed Implementation

[0041] The technical solutions of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0042] Example 1

[0043] like Figure 1As shown, the method for analyzing fillers in copper-clad laminate samples using infrared spectroscopy includes the following steps:

[0044] S1. Scrape the resin-filler mixture powder off the copper-clad laminate;

[0045] S2. The mixture powder is calcined at high temperature to obtain a mixture containing no organic matter and residual ash;

[0046] S3. After mixing and grinding the residual ash of the mixture with potassium bromide until uniform, the mixture is compressed into tablets to obtain a transparent sample.

[0047] S4. Measure the infrared spectrum of the transparent sample with an infrared spectrometer, and analyze the infrared spectrum of the transparent sample to obtain the chemical composition of the filler in the copper-clad laminate sample.

[0048] Example 1 describes a method for analyzing fillers in copper-clad laminate (CCL) samples using infrared spectroscopy. The residual ash from a resin-filler mixture powder on the CCL, obtained by high-temperature calcination and free of organic matter, is mixed with potassium bromide, ground evenly, and then pressed into a pellet to prepare a transparent sample. This method eliminates the influence of organic matter and glass fibers on the analytical results and facilitates the use of the potassium bromide pelleting method, improving the accuracy and reproducibility of the analytical results. The infrared spectrum of the mixture in the transparent sample is then measured. Infrared spectroscopy analysis of the fillers in the CCL samples accurately reveals their chemical composition. Furthermore, the testing instrument is safe, low-cost, and simple to operate.

[0049] Example 2

[0050] Based on the method of infrared spectroscopy analysis of fillers in copper clad laminate samples in Example 1, in step S1, the surface copper foil of the copper clad laminate is first removed by etching, and then the resin-filler mixture powder on the copper clad laminate is scraped off with a tool.

[0051] The method of using infrared spectroscopy to analyze the filler in the copper-clad laminate sample in Example 2 uses a knife to scrape off the copper-clad laminate powder instead of directly calcining the copper-clad laminate sample. This is beneficial for obtaining a white mixture of residual ash in the subsequent calcination operation, and it is also easier to grind the mixture of residual ash into a mixture of appropriate particle size, which is beneficial for subsequent tableting.

[0052] Example 3

[0053] Based on the method of using infrared spectroscopy to analyze the filler in the copper clad laminate sample in Example 1, in step S2, the obtained mixture powder is first subjected to high-temperature drying treatment, and then the mixture powder is calcined at high temperature.

[0054] Preferably, in step S2, the high-temperature drying treatment of the obtained mixture powder is carried out at a temperature of 80℃ to 200℃ for 0.5 to 8 hours. Under these drying conditions, the mixture powder can fully remove moisture and obtain a loose solid, which is beneficial for its full contact with air, thereby improving the subsequent calcination efficiency and saving energy.

[0055] Preferably, in step S2, the mixed powder is placed in a muffle furnace and calcined at a high temperature of 250℃ to 800℃ for 1 to 8 hours. Calcination of the mixed powder at high temperature until the residual ash content no longer changes effectively removes interfering substances such as organic matter, avoiding interference with subsequent infrared spectroscopy analysis and improving the accuracy of the infrared spectroscopy analysis.

[0056] Example 4

[0057] Based on the method of using infrared spectroscopy to analyze the filler in the copper clad laminate sample in Example 1, in step S3, before mixing and grinding potassium bromide with the residual ash in the mixture, the potassium bromide is first dried.

[0058] Preferably, in step S3, the potassium bromide drying temperature is 80–200°C and the drying time is 2–6 hours.

[0059] Preferably, in step S3, the weight ratio of residual ash in the mixture to potassium bromide is 1:50 to 1000. Using this ratio to prepare a transparent sample is beneficial for obtaining accurate and well-defined infrared absorption spectra. If the residual ash concentration in the mixture is too high, a flat absorbance peak may appear, making it impossible to determine the peak position. If the residual ash concentration in the mixture is too low, the results are easily affected by sample preparation errors and impurities.

[0060] In Example 4, the method for analyzing filler in copper-clad laminate samples using infrared spectroscopy effectively eliminates the influence of moisture after potassium bromide is dried. This avoids the impact of water vapor's infrared absorption peaks on the results, thus improving the accuracy of infrared testing. The dried potassium bromide should be stored in a desiccator for later use; it needs to be dried again after prolonged storage.

[0061] Example 5

[0062] Based on the method of analyzing filler in copper-clad laminate samples using infrared spectroscopy in Example 1, in step S3, the pressure of the pressing sheet is 100-300 MPa and the pressure is maintained for 30-120 s to obtain the light-transmitting sample.

[0063] Using the above conditions can yield a more ideal transparent sample. Insufficient pressure and time may result in the transparent sample not being transparent enough, leading to spectral baseline drift. Excessive pressure and time may damage the pressing fixture.

[0064] Example 6

[0065] Based on the method of infrared spectroscopy analysis of filler in copper clad laminate sample according to Example 1, in step S4, the infrared spectrum of the transparent sample is searched using infrared software to perform standard spectrum retrieval and the infrared spectral retrieval results are analyzed and verified to obtain the chemical composition of filler in copper clad laminate sample.

[0066] Preferably, Fourier transform infrared spectrometer is used to perform infrared testing on the transmitted sample, with the following testing conditions: test resolution of 4 cm⁻¹. -1 The number of scans was 16, and the test range was 400–4000 cm. -1 Temperature: Room temperature. Humidity: Dry environment below 45%.

[0067] Preferably, the method for analyzing and verifying the infrared spectral search results is one or more of the following: peak resolution, difference spectrum, and spectrum addition.

[0068] A preferred method for analyzing and verifying the infrared spectral search results is as follows:

[0069] Based on the characteristic peak values ​​of the infrared absorption peaks in the infrared spectrum of the transmitted sample, a search is performed in a standard spectral library to obtain the N compounds with the highest similarity to the infrared spectrum, where N is an integer greater than 1. The fitted infrared spectrum of the mixture is obtained by adding the spectra of the N compounds with the highest similarity.

[0070] The infrared spectrum of the fitted mixture is compared with the infrared spectrum of the transmitted sample for quality inspection. If the similarity between the two is greater than the set value, the chemical composition of the filler in the copper clad laminate sample is determined to be the N compounds.

[0071] The method of using infrared spectroscopy to analyze the filler in copper-clad laminate samples in Example 6, which uses infrared software to search for standard spectra of the mixture in the transparent sample and verify the results, can improve the accuracy of the analysis.

[0072] Example 7

[0073] Based on the method of infrared spectroscopy analysis of filler in copper clad laminate samples according to Example 6, in step S1, the copper clad laminate sample to be tested is etched with sodium persulfate solution to remove the surface copper foil, washed with water and wiped clean, and the resin-filler mixture on the surface of the copper clad laminate is scraped off with a special tool to obtain a yellow initial mixture powder.

[0074] In step S2, about 0.05g of the initial mixture powder is placed in a porcelain crucible, covered, and dried at 120°C for 2 hours to obtain a fluffy mixture powder. Then, the porcelain crucible containing the fluffy mixture powder is placed in a muffle furnace and heated at 500°C for 2 hours. After the temperature inside the muffle furnace cools to about 120°C, the crucible is removed and placed in a desiccator to cool naturally to room temperature, resulting in a pale yellow to nearly white mixture with residual ash.

[0075] In step S3, potassium bromide is dried at 120°C for 2 hours, and then cooled in a desiccator for later use. 1 mg of residual ash from the mixture is mixed with 400 mg of potassium bromide and ground to obtain a uniform powder. This powder is placed in a mold and pressed under 50 MPa pressure on a hydraulic press for 60 seconds. After removing the pressure, a transparent sample is obtained.

[0076] In step S4, infrared testing is performed on the transparent sample to obtain its infrared spectrum (see...). Figure 2 Infrared spectroscopy was used to analyze the filler in the copper-clad laminate samples.

[0077] Based on the characteristic peak values ​​of the infrared absorption peaks in the infrared spectrum of the transmitted sample, a search was performed in a standard spectral library. The results showed that its infrared spectra were similar to those of silica and talc (see [reference]). Figure 3 , Figure 4 The spectra have a high degree of similarity, and by adding the spectra together, the fitted infrared spectrum of the mixture can be obtained (see...). Figure 5 The quality of the spectrum was compared with that of the original infrared spectrum, and the results were as follows: Figure 6 As shown, the two have a high degree of similarity (>95%), which indicates that the filler in the copper-clad laminate sample is silica and talc.

[0078] 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 analyzing fillers in copper-clad laminate samples using infrared spectroscopy, characterized in that... Includes the following steps: S1. First, the copper foil on the surface of the copper-clad laminate is removed by etching, and then the resin-filler mixture powder on the copper-clad laminate is scraped off with a tool. S2. First, the mixture powder is subjected to high-temperature drying treatment at a temperature of 80℃~200℃ for 0.5~8h; then, the mixture powder is placed in a muffle furnace for high-temperature calcination to obtain residual ash of the mixture at a temperature of 250℃~800℃ for 1~8h; S3. First, potassium bromide is dried, then the residual ash of the mixture is mixed and ground evenly with potassium bromide and pressed into tablets to obtain translucent samples; the potassium bromide drying temperature is 80~200℃ and the drying time is 2~6h; the weight ratio of residual ash of the mixture to potassium bromide is 1:50~1000; S4. The infrared spectrum of the transparent sample is measured using an infrared spectrometer, and the chemical composition of the filler in the copper-clad laminate sample is obtained by analyzing the infrared spectrum of the transparent sample.

2. The method for analyzing fillers in copper-clad laminate samples using infrared spectroscopy according to claim 1, characterized in that, In step S3, the pressure of the tablet is 100-300 MPa and maintained for 30-120 s to obtain the transparent sample.

3. The method for analyzing fillers in copper-clad laminate samples using infrared spectroscopy according to claim 1, characterized in that, In step S4, infrared software is used to perform standard spectrum retrieval on the infrared spectrum of the transparent sample and the infrared spectrum retrieval results are analyzed and verified to obtain the chemical composition of the filler in the copper-clad laminate sample.

4. The method for analyzing fillers in copper-clad laminate samples using infrared spectroscopy according to claim 3, characterized in that, The methods for analyzing and verifying infrared spectral search results include one or more of the following: peak resolution, difference spectrum, and spectrum addition.

5. The method for analyzing fillers in copper-clad laminate samples using infrared spectroscopy according to claim 3, characterized in that, The method for analyzing and verifying the infrared spectral search results is as follows: Based on the characteristic peak values ​​of the infrared absorption peaks in the infrared spectrum of the transmitted sample, a search is performed in a standard spectral library to obtain the N compounds with the highest similarity in infrared spectrum, where N is an integer greater than 1. The fitted infrared spectrum of the mixture is obtained by adding the spectra of the N compounds with the highest similarity. The infrared spectrum of the fitted mixture is compared with the infrared spectrum of the transmitted sample for quality inspection. If the similarity between the two is greater than the set value of 95%, the chemical composition of the filler in the copper clad laminate sample is determined to be the N compounds.

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