Sealing adhesive for metallographic sample preparation and preparation method thereof

Abstract

The invention relates to a solid sealing adhesive for metallographic sample preparation and a preparation method thereof.The preparation method comprises the following steps that S1, a diluent and a nanoscale filler are added into a resin matrix and then mixed, a defoaming agent is added, mixing continues, and a first material is obtained; mixing a curing agent and a curing accelerator to obtain a second material; s2, mixing the first material and the second material to obtain the sealing adhesive; wherein the resin matrix, the diluent, the nanoscale filler, the defoaming agent, the curing agent and the curing accelerator are prepared from the following components in parts by mass: 60 to 80 parts of the resin matrix, 10 to 20 parts of the diluent, 10 to 20 parts of the nanoscale filler, 0.5 to 2 parts of the defoaming agent, 20 to 50 parts of the curing agent and 30 to 70 parts of the curing accelerator, the diluent is an ether diluent with a chain structure. The prepared solid sealing glue for metallographic sample preparation has relatively high flowability and also has relatively high hardness after being cured.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a sealing adhesive for metallographic sample preparation and its preparation method. Background Technology

[0002] In semiconductor failure analysis, accurately locating the failure site of components is crucial. This process typically requires a detailed analysis of internal anomalies in the component or package structure to determine the specific cause of the failure. Therefore, metallographic sample preparation techniques are a standard practice for analyzing failure locations. This method involves cutting a sample, embedding it with an encapsulating agent to fix its position, then performing rough grinding, fine grinding, and polishing to a mirror finish, finally revealing the microstructure through chemical etching and microscopic observation and recording.

[0003] However, due to the high precision and complex internal structure of semiconductor components, it is necessary to ensure that the failure location does not shift during metallographic sample preparation. This places high demands on the encapsulation properties and hardness of the encapsulating adhesive used in metallographic sample preparation.

[0004] Currently, epoxy resin encapsulants commonly used in metallographic sample preparation have high viscosity (exceeding 5000 mPa·s). To improve their fluidity and ensure complete coating of the sample during preparation, the common method is to increase the diluent content. Although the diluent can participate in the curing reaction of the resin matrix, excessive diluent content will affect the overall strength of the cured encapsulant. To increase the hardness of the cured encapsulant, fumed silica is usually added, but this will significantly reduce the fluidity of the encapsulant, making it unable to effectively coat small components. Therefore, the failure location may shift during grinding, thus affecting the accuracy of failure analysis. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to overcome the defects or deficiencies of the prior art. On the one hand, it provides a method for preparing a sealing adhesive for metallographic sample preparation, wherein the prepared sealing adhesive has high fluidity and high hardness after curing.

[0006] A method for preparing a sealing adhesive for metallographic sample preparation includes the following steps: S1: Add diluent, nano-sized filler and defoamer to the resin matrix and mix them to obtain the first material; The curing agent and curing accelerator are then mixed to obtain the second material; S2: Mix the first material with the second material to obtain a sealant; The resin matrix, the diluent, the nano-filler, the defoamer, the curing agent, and the curing accelerator are configured in the following proportions by weight: Resin matrix: 60-80 parts Diluent: 10-20 parts Nanoscale filler: 10-20 parts Defoamer: 0.5-2 parts Hardener: 20-50 parts Curing accelerator: 30-70 parts The diluent is an ether-based diluent with a chain structure.

[0007] Compared to existing technologies, the method for preparing the metallographic sealant of this invention utilizes an ether-based diluent with a chain structure. The chain structure of the linear alkyl ether diluent breaks up the entanglement between resin matrix molecules through intermolecular forces, reducing intermolecular frictional resistance at the molecular level during raw material mixing, thus increasing the fluidity of the final sealant. Simultaneously, the epoxy groups in the ether diluent undergo a ring-opening reaction with the curing agent, increasing the degree of cross-linking after curing. The higher the degree of cross-linking of the cured resin matrix, the more stable its internal structure, thereby improving the hardness of the cured sealant. This solves the technical contradiction between the fluidity and hardness of traditional metallographic sealants, enabling effective coating of samples while meeting the hardness requirements for grinding, and preventing the accuracy of failure analysis from being affected by the shift of the sample's failure location during grinding.

[0008] In one embodiment, the resin matrix is ​​one or more of hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin, glycidyl ether epoxy resin, and alicyclic epoxy resin.

[0009] In one embodiment, the diluent is one or more of C12-C14 alkyl glycidyl ether and butyl glycidyl ether.

[0010] In one embodiment, the nanoscale filler is an inorganic filler with a carboxylated surface, and the inorganic filler is one or more of silicon dioxide, alumina, and glass.

[0011] In one embodiment, the defoamer is one or more of polydimethylsiloxane and BYK-50.

[0012] In one embodiment, the curing agent is one or more of aliphatic polyamines and alicyclic polyamines.

[0013] In one embodiment, the curing accelerator is one or more of modified dicyandiamide, modified imidazole, and modified substituted urea.

[0014] In one embodiment, in step S2, the mass ratio of the first material to the second material is 1:(0.3-0.6).

[0015] In one embodiment, in step S1, the mixing process of the first material and the second material is carried out under vacuum conditions.

[0016] On the other hand, the present invention also provides a sealing adhesive for metallographic sample preparation, which is composed of a first material and a second material; The first material includes: Resin matrix: 60-80 parts Diluent: 10-20 parts Nanoscale filler: 10-20 parts Defoamer: 0.5-2 parts The diluent is an ether-based diluent with a chain structure; The second material includes: Hardener: 20-50 parts Curing accelerator: 30-70 parts. Detailed Implementation

[0017] Metallographic encapsulants need to possess a certain degree of fluidity to ensure effective encapsulation of micro-components and structures. However, commonly used epoxy resins, such as bisphenol A, have relatively high viscosity, resulting in poor fluidity. To improve the fluidity of epoxy encapsulants, the amount of diluent added is often increased; however, excessive diluent addition can affect the hardness of the cured encapsulant. Conversely, to improve the strength of the cured encapsulant, fumed silica is typically added, but this significantly reduces the fluidity. Therefore, existing metallographic encapsulants fail to balance the dual properties of fluidity and hardness.

[0018] Based on this, the present invention provides a method for preparing a sealing adhesive for metallographic sample preparation. By using an ether-based diluent with a chain structure, the chain structure of the linear alkyl ether diluent opens the entanglement between resin matrix molecules through intermolecular forces. During the mixing of raw material components, it can reduce the frictional resistance between molecules at the molecular structure level, thereby increasing the fluidity of the final sealing adhesive. At the same time, the epoxy groups in the ether diluent undergo a ring-opening reaction with the curing agent, increasing the degree of crosslinking after curing. The higher the degree of crosslinking of the cured resin matrix, the more stable its internal structure, thereby improving the hardness of the cured sealing adhesive.

[0019] In addition, on the one hand, in order to further improve the fluidity of the sealant, the present invention selects a modified epoxy resin with lower viscosity as the resin matrix and selects a curing agent with lower viscosity to participate in the preparation; on the other hand, in order to further improve the hardness of the sealant after curing, in addition to the curing agent, a curing accelerator is added to promote the crosslinking reaction rate between the curing agent and the resin matrix, so as to increase the degree of crosslinking per unit time. The higher the degree of crosslinking per unit time, the higher the hardness.

[0020] Based on the above design concept for the composition of the sealant, the sealant for metallographic sample preparation and its preparation method of the present invention will be described in detail below.

[0021] This invention provides a sealing adhesive for metallographic sample preparation, one embodiment of which includes the following steps: S1: Add diluent, nano-sized filler and defoamer to the resin matrix and mix them to obtain the first material; then mix the curing agent and curing accelerator to obtain the second material; Specifically, weigh out 60-80 parts of resin matrix, 10-20 parts of diluent, 10-20 parts of nano-filler and 0.5-2 parts of defoamer by weight. Diluent and nano-sized filler are added to the resin matrix in sequence, and then stirred and mixed evenly at room temperature. Then defoamer is added and stirred and mixed evenly to obtain the first material.

[0022] The resin matrix is ​​one or more of hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin, glycidyl ether epoxy resin and alicyclic epoxy resin, preferably hydrogenated bisphenol A type epoxy resin or glycidyl ether epoxy resin. The bisphenol A type epoxy resin used in the traditional way has a high viscosity. By selecting a modified epoxy resin with a lower viscosity as the resin matrix, it is beneficial to improve the flowability of the prepared sealant. The diluent is an ether-based diluent with a straight-chain structure, specifically one or more of ether-based diluents such as C12-C14 alkyl glycidyl ether and butyl glycidyl ether, preferably C12-C14 alkyl glycidyl ether. The chain structure of the diluent can reduce intermolecular resistance during the mixing of raw materials, thereby improving the flowability of the sealant. At the same time, the epoxy groups in the ether bonds of the diluent will undergo ring-opening reactions with the subsequently added curing agent, increasing the degree of crosslinking of the sealant after curing. The higher the degree of crosslinking of the sealant after curing, the more stable its internal structure and the higher its hardness.

[0023] The nanoscale filler is an inorganic filler with a carboxylated surface, and its particle size is 10-100 nm, preferably 50 nm. Specifically, the inorganic filler is one or more of silica, alumina, and glass, preferably silica. After carboxylation treatment, the surface of the inorganic filler has carboxyl functional groups. The inorganic filler can penetrate into the spaces between the macromolecules of the resin matrix. The polarity of its carboxyl functional groups can repel each other in the resin matrix, increasing fluidity and allowing the inorganic filler to be uniformly dispersed in the resin matrix, avoiding agglomeration that would affect the hardness and transparency of the cured sealant. Furthermore, the nanoscale particle size helps the uniformly dispersed inorganic filler fill into the tiny gaps in the sample, achieving effective coating of the sample.

[0024] The defoamer is polydimethylsiloxane or BYK-50, which is used to reduce the surface tension of the material and eliminate air bubbles mixed into the material during the mixing process, thereby increasing the hardness and transparency of the cured sealant.

[0025] Furthermore, weigh out 20-50 parts of curing agent and 30-70 parts of curing accelerator by weight; The curing agent and curing accelerator are stirred and mixed evenly at room temperature to obtain the second material.

[0026] The curing agent is one or more of aliphatic polyamines and alicyclic polyamines, preferably aliphatic polyamines. Since the curing agent lacks rigid aromatic rings, its viscosity is low, which is beneficial to further improve the fluidity of the sealant. In addition, besides undergoing a cross-linking reaction with the epoxy groups of the resin matrix to form a three-dimensional network structure, the curing agent can also cross-link with the epoxy groups of the diluent, thereby improving the degree of cross-linking inside the sealant after curing.

[0027] The curing accelerator is one or more of modified dicyandiamide, modified imidazole, and modified substituted urea, preferably modified imidazole. "Modification" refers to introducing the functional group urea group "-NH-CO-NH-" through reaction with urea derivatives, or introducing a quaternary ammonium salt "-N" through alkylation / salting reactions. + -RX -For example, substituted ureas are generated by reacting the amino group (-NH2) on dicyandiamide with isocyanate (-NCO) or monourea. Substituted ureas are powerful curing accelerators that significantly reduce the decomposition activation energy of dicyandiamide, thereby greatly lowering the curing temperature. Simultaneously, the modified product is usually a viscous liquid or a low-melting-point solid, greatly improving its compatibility with epoxy resins. Another example is the formation of imidazole onium salts by reacting the pyrrole nitrogen atom on the imidazole ring with halogenated hydrocarbons, acids, etc. After the onium salt is formed, the basicity of imidazole is "blocked," and its reactivity temporarily disappears, resulting in excellent storage stability. When heated to a certain temperature, the onium salt decomposes, releasing the active imidazole, thus initiating the curing reaction and greatly extending the service life of the epoxy resin system. Therefore, the addition of curing accelerators can accelerate the curing reaction, shorten the curing time, lower the curing temperature, and achieve controlled curing of the sealant; it can also accelerate the curing reaction and improve compatibility with epoxy resins, preventing precipitation during storage.

[0028] S2: Mix the first material and the second material to obtain the sealant.

[0029] Specifically, the first material and the second material are mixed evenly at room temperature in a mass ratio of 1:(0.3-0.6) to obtain the finished sealant, wherein the preferred ratio is 1:0.5.

[0030] In the above mixing process, the mixing treatment is not limited to stirring; other means can also be used to achieve mixing, as long as the raw material components are fully and uniformly mixed. To further eliminate air mixed in during the mixing process, in step S1 above, the mixing processes of the first material and the second material are both carried out under vacuum conditions (1*10). -6 The curing process is carried out at a temperature of Mp to completely eliminate air bubbles inside the finished sealant, ensuring the hardness and transparency of the cured sealant.

[0031] Based on the above method for preparing the sealing adhesive for metallographic sample preparation, this invention further conducted experimental operations and verifications on various parameters, which are described in detail below: Examples 1-3 Using the above preparation method, curing adhesives for metallographic sample preparation were prepared according to the raw material components and their mass fractions shown in Table 1 below and the mass ratio of the first material to the second material in Table 2.

[0032] Table 1

[0033] Table 2

[0034] Comparative Examples 1-2 Using the above preparation method, the curing adhesives for metallographic sample preparation of Examples 1-2 and Comparative Examples 1-2 were prepared according to the raw material components shown in Table 3 and the mass ratio of the first material to the second material in Table 4, respectively. The only difference between Comparative Example 1 and Example 1 is that Comparative Example 1 uses styrene as a diluent, while the other raw material components, their addition amounts, and the mass ratio of the first material to the second material are the same as in Example 1.

[0035] The only difference between Comparative Example 2 and Example 2 is that Comparative Example 2 uses uncarboxylated silicon carbide particles as nanoscale fillers, while the other raw material components, their addition amounts, and the mass ratio of the first material to the second material are the same as in Example 2.

[0036] Table 3

[0037] Table 4

[0038] Performance testing The viscosity of the sealants prepared in Examples 1-3 and Comparative Examples 1-2 was measured using a viscorrometer, and the hardness and light transmittance of the cured sealants were measured using a hardness tester and a spectrophotometer. The test results are shown in Table 5 below. Table 5

[0039] As shown in Table 5, the viscosity of the metallographic sample preparation sealant prepared in Examples 1-3 of this invention is all below 2000 mPa·s, far lower than the viscosity of traditional epoxy resin (5000 mPa·s), effectively improving the fluidity of the sealant and achieving good encapsulation effect when embedding and fixing small-volume samples. Furthermore, the hardness of the cured sealant prepared in Examples 1-3 reaches above 90D, ensuring that the sample is not easily deformed during grinding and polishing. In addition, the light transmittance of the cured sealant prepared in Examples 1-3 all reaches above 90%, exhibiting high transparency, which helps improve the accuracy of sample analysis.

[0040] Comparing the test results of Example 1 and Comparative Example 1, it can be seen that the viscosity of the sealant prepared by Comparative Example 1, which uses styrene without a chain structure as a diluent, is twice that of the sealant prepared in Example 1 of this invention. This indicates that the sealant has poor flowability and may not be able to completely cover the sample when it is used to mount and fix small-volume samples. In addition, compared with Example 1, the sealant of Comparative Example 1 has a lower hardness (below 90D). Therefore, it is not as effective as Example 1 of this invention in preventing the failure position from shifting due to grinding.

[0041] Comparing the test results of Example 2 and Comparative Example 2, it can be seen that Comparative Example 2 uses silicon carbide particles with a particle size of 80 nm as filler. Although the viscosity of the encapsulant in Comparative Example 2 is lower than that in Comparative Example 1, it is still higher than 2000 mPa·s, indicating that its fluidity is not as good as that of Example 2. When embedding and fixing samples with small volumes, the encapsulant in Comparative Example 2 may not be able to completely cover the sample. Although the hardness of the encapsulant in Comparative Example 2 after curing can reach above 90D, its light transmittance is less than 90%, indicating that its transparency is not as good as that of Example 2.

[0042] A comparison of the test results of Examples 1-2 and Comparative Examples 1-2 shows that the diluent and nano-filler have a synergistic effect on the flowability of the sealant. Through the synergistic effect of the diluent and nano-filler, the viscosity of the sealant can be reduced and its flowability improved while ensuring that the cured hardness of the sealant reaches 90D or higher. This ensures that the sealant of the present invention achieves complete coating of the sample and prevents the failure location of the sample from deviating during subsequent grinding, thus affecting the accuracy of failure analysis.

[0043] Compared to existing technologies, the method for preparing the metallographic sealant of this invention utilizes an ether-based diluent with a chain structure. The linear alkyl ether diluent, with its chain structure, breaks up the entanglement between resin matrix molecules through intermolecular forces. During the mixing of raw materials, it reduces intermolecular frictional resistance at the molecular level, increasing the fluidity of the final sealant. Simultaneously, the epoxy groups in the ether diluent undergo a ring-opening reaction with the curing agent, increasing the degree of cross-linking after curing. A higher degree of cross-linking in the cured resin matrix results in a more stable internal structure, thereby improving the hardness of the cured sealant. This allows for effective coating of the sample while meeting the hardness requirements for grinding, preventing the accuracy of failure analysis from being affected by the shift in the failure location of the sample during grinding.

[0044] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a sealing adhesive for metallographic sample preparation, characterized in that: Includes the following steps: S1: Add diluent, nano-sized filler and defoamer to the resin matrix and mix them to obtain the first material; The curing agent and curing accelerator are then mixed to obtain the second material; S2: Mix the first material with the second material to obtain a sealant; The resin matrix, the diluent, the nano-filler, the defoamer, the curing agent, and the curing accelerator are configured in the following proportions by weight: Resin matrix: 60-80 parts Diluent: 10-20 parts Nanoscale filler: 10-20 parts Defoamer: 0.5-2 parts Hardener: 20-50 parts Curing accelerator: 30-70 parts The diluent is an ether-based diluent with a chain structure.

2. The method for preparing the sealing adhesive for metallographic sample preparation according to claim 1, characterized in that: The resin matrix is ​​one or more of hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin, glycidyl ether epoxy resin, and alicyclic epoxy resin.

3. The method for preparing the sealing adhesive for metallographic sample preparation according to claim 1, characterized in that: The diluent is one or more of C12~C14 alkyl glycidyl ether and butyl glycidyl ether.

4. The method for preparing the sealing adhesive for metallographic sample preparation according to claim 1, characterized in that: The nanoscale filler is an inorganic filler whose surface has been carboxylated, and the inorganic filler is one or more of silicon dioxide, alumina and glass.

5. The method for preparing the sealing adhesive for metallographic sample preparation according to claim 1, characterized in that: The defoamer is one or more of polydimethylsiloxane and BYK-50.

6. The method for preparing the sealing adhesive for metallographic sample preparation according to claim 1, characterized in that: The curing agent is one or more of aliphatic polyamines and alicyclic polyamines.

7. The method for preparing the sealing adhesive for metallographic sample preparation according to claim 1, characterized in that: The curing accelerator is one or more of modified dicyandiamide, modified imidazole, and modified substituted urea.

8. The method for preparing the sealing adhesive for metallographic sample preparation according to claim 1, characterized in that: In step S2, the mass ratio of the first material to the second material is 1:(0.3-0.6).

9. The method for preparing the sealing adhesive for metallographic sample preparation according to claim 1, characterized in that: In step S1, the mixing process of the first material and the second material is carried out under vacuum conditions.

10. A sealing adhesive for metallographic sample preparation, characterized in that: It consists of a first material and a second material; The first material includes: Resin matrix: 60-80 parts Diluent: 10-20 parts Nanoscale filler: 10-20 parts Defoamer: 0.5-2 parts The diluent is an ether-based diluent with a chain structure; The second material includes: Hardener: 20-50 parts Curing accelerator: 30-70 parts.

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