JP6922565B2 - Method for manufacturing resin-embedded sample and transmission electron microscope sample - Google Patents

Description

The present invention relates to a resin-embedded sample and a method for producing the same, and a sample for a transmission electron microscope and a method for producing the same.

Many products manufactured using powdered raw materials (powder materials) are known. For example, paints are manufactured using pigments, magnets are manufactured using magnetic materials, and conductive pastes are manufactured using conductors. .. Since the characteristics of these products are affected by the characteristics of the powder material used, such as the shape, surface condition, composition and chemical condition of the powder, the characteristics of the powder material can be used to improve the characteristics of the product. Evaluation and analysis are important.

One of the methods for evaluating and analyzing the characteristics of powder materials is a transmission electron microscope (TEM). When a powder material is analyzed by TEM as a powder sample, it is necessary to fix and support the powder sample so as not to scatter. Therefore, for example, a method of mixing a powder sample with a liquid resin and curing it to prepare a resin-embedded sample is adopted. The resin-embedded sample is sliced using, for example, a focused ion beam (FIB) device and analyzed by TEM (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2000-21405

By the way, if the powder sample is small or absent in the observation area during the observation by TEM, not only the observation itself is wasted, but also sampling from the resin-embedded sample by the FIB device for TEM is wasteful. May become. In order to reduce these wastes as much as possible, the resin-embedded sample is required to increase the filling amount of the powder sample to increase the number density.

However, if the filling amount of the powder sample is increased in order to increase the number density, the viscosity of the liquid resin increases as the amount of the powder sample increases, and the stress for mixing increases. The powder sample may be damaged and deteriorated due to friction or collision.

On the other hand, it is conceivable to weaken the mixing force in order to suppress the deterioration of the powder sample, but in this case, the resin may not spread to the interface of the powder particles while a large amount of the powder sample forms an agglomerate. In this case, voids are formed in the aggregate, and the voids may reduce the analysis accuracy when analyzing by TEM.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique for suppressing deterioration and aggregation of a powder sample while increasing the number density of the powder sample in a resin-embedded sample.

The present inventor investigated a method of suppressing deterioration and aggregation of the powder sample even when the amount of the powder sample was increased, and focused on a method of spraying the powder sample on a coating layer coated with a liquid resin and precipitating the powder sample. According to the sedimentation, no external stress is applied as in the case of adding and mixing the powder sample, so that the powder sample is not deteriorated. Moreover, by spreading the liquid resin at the interface between the powder samples in the settling process, the powder samples and the resin can be brought into contact with each other, and the aggregation of the powder samples and the formation of voids accompanying the contact can be suppressed. Then, by curing the liquid resin after sedimentation, a resin-embedded sample in which the powder sample is unevenly distributed on one surface side of the resin layer can be obtained. According to this resin layer, for example, by preparing a flaky sample for TEM from a region where a large amount of powder sample exists, it is possible to improve the observation efficiency in TEM. The present invention has been made based on these findings.

That is, the first aspect of the present invention is
The coating process of applying liquid resin on the substrate to form a coating layer,
A settling step in which a powder sample is sprayed on the coating layer and settled in the coating layer.
It has a curing step of curing the coating layer to form a resin layer.
Provided is a method for producing a resin-embedded sample, which produces a resin-embedded sample in which the powder sample is unevenly distributed so that the number density increases from one surface to the other surface in the thickness direction of the resin layer. Will be done.

A second aspect of the present invention is the method for producing a resin-embedded sample of the first aspect.
The liquid resin is a thermosetting resin or a photocurable resin.

A third aspect of the present invention is the method for producing a resin-embedded sample according to the first or second aspect.
The liquid resin is a room temperature curable resin,
The coating layer is cured while the powder sample is precipitated in the coating layer, and the curing step is performed together with the precipitation step.

A fourth aspect of the present invention is the method for producing a resin-embedded sample according to any one of the first to third aspects.
The liquid resin is a room temperature curable epoxy resin.

A fifth aspect of the present invention is the method for producing a resin-embedded sample according to any one of the first to fourth aspects.
Prior to the coating step, there is a roughening step of roughening the surface of the substrate to which the liquid resin is to be coated.

A sixth aspect of the present invention is the method for producing a resin-embedded sample according to any one of the first to fifth aspects.
In the settling step, after spraying the powder sample, a plate-shaped member is placed on the coating layer, and the powder sample is pushed into the coating layer to settle.

A seventh aspect of the present invention is the method for producing a resin-embedded sample according to any one of the first to fifth aspects.
In the sedimentation step, a centrifugal force is applied to the powder sample in the direction of the substrate to cause the powder sample to settle in the coating layer.

An eighth aspect of the present invention is the method for producing a resin-embedded sample according to any one of the first to fifth aspects.
The powder sample is a magnetic particle,
In the settling step, a magnetic force is applied to the powder sample in the direction of the substrate to cause the powder sample to settle in the coating layer.

In the ninth aspect of the present invention, the sample piece is collected from the surface side region where the powder sample is unevenly distributed and the number density is high in the resin-embedded sample obtained by the production method according to any one of the first to eighth aspects. A method for producing a sample for a transmission electron microscope is provided.

A tenth aspect of the present invention is
A resin layer formed from a cured product obtained by curing a liquid resin,
A powder sample embedded in the resin layer is provided.
A resin-embedded sample is provided in which the powder sample is unevenly distributed so that the number density increases from one surface to the other in the thickness direction of the resin layer.

An eleventh aspect of the present invention provides a transmission electron microscope sample in which the powder sample in the resin-embedded sample of the tenth aspect is unevenly distributed and collected from a region on the surface side having a high number density.

According to the present invention, it is possible to suppress alteration and aggregation of the powder sample while increasing the number density of the powder sample in the resin-embedded sample.

FIG. 1 is a manufacturing process diagram in a method for manufacturing a sample for a transmission electron microscope according to an embodiment of the present invention. FIG. 2A is a diagram for explaining polishing of the substrate, and FIG. 2B is a cross-sectional view taken along the line AA of FIG. 2A. FIG. 3 is a diagram for explaining the case where the plate-shaped member is placed on the coating layer.

<One Embodiment of the present invention>
Hereinafter, an embodiment of the present invention will be described as an example in which a sample for a transmission electron microscope is produced from a resin-embedded sample. FIG. 1 is a manufacturing process diagram in a method for manufacturing a sample for a transmission electron microscope according to an embodiment of the present invention.

The method for producing a transmission type electron microscope sample (TEM sample) of the present embodiment includes a preparation step, a roughening step, a coating step, a settling step, a curing step, a peeling step, and a processing step. Hereinafter, each step will be described in detail.

(Preparation process)
First, the powder sample 13 is prepared. Examples of the powder sample 13 include fine particles containing a metal, a metal compound, or an inorganic compound. The particle size of the powder sample 13 is, for example, about 1 μm to 10 μm.

In addition, the substrate 11 is prepared as a working plate for preparing the resin-embedded sample 10. The substrate 11 is not particularly limited, but may be formed of a material that is easily subjected to the roughening step described later, and may be formed of a material that does not interfere with analysis such as TEM. A resin film is preferable as the substrate 11, and for example, a polyimide film can be used.

(Roughening process)
Subsequently, before the coating step, the surface of the substrate 11 to which the liquid resin is applied is roughened in advance. Since the liquid resin has a large surface tension and tends to curl into a spherical shape when applied onto the substrate 11, the thickness of the coating layer 12 may increase. When the coating layer 12 becomes thick, the distance for the powder sample 13 to settle in the settling step described later becomes long, and the time for the powder sample 13 to settle becomes long, so that the productivity of the resin-embedded sample 10 may decrease. .. On the other hand, according to the roughening step, since the surface of the substrate 11 can be damaged and the surface tension of the liquid resin can be reduced, the coating layer 12 can be formed thinly by spreading the liquid resin thinly, and the resin-embedded sample 10 can be produced. The sex can be improved. As the abrasive, a known material such as sandpaper can be used.

(Applying process)
Subsequently, a liquid resin is applied to the roughened surface (roughened surface) of the substrate 11 to form the coating layer 12. In the present embodiment, the coating layer 12 is formed thin by applying a liquid resin to the roughened surface of the substrate 11. Thereby, the thickness of the coating layer 12 can be set to, for example, 100 μm to 1000 μm.

The liquid resin is not particularly limited as long as the powder sample 13 can be precipitated and can be cured after sedimentation. For example, a thermosetting resin or a photocurable resin can be used.
As the thermosetting resin, either a room temperature curable resin or a heat curable resin can be used, but a room temperature curable resin is preferable. According to the room temperature curable resin, heating is not required, and the coating layer 12 can be gradually cured while the powder sample 13 is precipitated in the coating layer 12 in the sedimentation step described later, so that the number of steps is large. Can be reduced to simplify manufacturing. A room temperature curable epoxy resin is preferable as the thermosetting resin because it is easy to handle when analyzing the TEM sample 20 and has been used in many cases.
As the photocurable resin, an acrylic resin, an epoxy acrylate resin, or the like can be used.

If the viscosity of the liquid resin is too high, it becomes difficult to settle the powder sample 13 in the settling step, while if it is too low, the ratio of low molecular weight components increases, and the coating layer 12 (resin layer 14) maintains a predetermined thickness. It may be difficult to form. Therefore, the viscosity of the liquid resin may be adjusted within a range in which the powder sample 13 can be easily settled and the coating layer 12 (resin layer 14) can be maintained at a predetermined thickness.

(Settlement process)
Subsequently, as shown in FIG. 1A, the powder sample 13 is sprayed on the coating layer 12 made of a liquid resin. In the present embodiment, the powder sample 13 is sprayed and then allowed to stand. The sprayed powder sample 13 will settle in the coating layer 12 due to its own weight. Therefore, the powder sample 13 does not deteriorate due to external stress and does not come into contact with the liquid resin and aggregate with each other. Then, as shown in FIG. 1B, the powder sample 13 settles on the substrate 11 side of the coating layer 12 with the lapse of a predetermined time, so that the number density increases toward the substrate 11 side of the coating layer 12. Will be unevenly distributed in. Since the settling time varies depending on the viscosity of the liquid resin and the density of the powder sample 13, it may be appropriately changed according to the type of the liquid resin or the powder sample 13.

The amount (filling amount) of the powder sample 13 to be sprayed is not particularly limited. In this embodiment, since the powder sample 13 is precipitated, the filling amount can be increased as compared with the case where the powder sample 13 is added to the conventional liquid resin and mixed.

(Curing process)
Subsequently, as shown in FIG. 1 (b), after the powder sample 13 is settled, the coating layer 12 made of liquid resin is cured to form the resin layer 14. The resin layer 14 will be formed from a cured product of a liquid resin. As a result, the powder sample 13 is fixed and supported in a state of being unevenly distributed on the substrate 11 side of the resin layer 14, and the powder sample 13 is embedded in the resin layer 14 and the resin layer is increased in number density toward the substrate 11 side. A resin-embedded sample 10 unevenly distributed in 14 is formed.

The curing method in the curing step may be appropriately changed according to the type of the liquid resin. If the liquid resin is a room temperature curable resin, it may be allowed to stand as it is from the above-mentioned sedimentation step, and if it is a thermosetting resin, it may be heated at a predetermined temperature after the powder sample 13 is precipitated. If the liquid resin is a photocurable resin, the coating layer 12 may be irradiated with light.

(Peeling process)
Subsequently, as shown in FIG. 1C, the substrate 11 is removed from the resin layer 14, and the resin-embedded sample 10 is taken out. FIG. 1C shows a case where the resin-embedded sample 10 is arranged so that the surface on which the powder sample 13 is unevenly distributed faces upward. The resin-embedded sample 10 includes a resin layer 14 formed from a cured product obtained by curing a liquid resin and a powder sample 13 filled in the resin layer 14, and the powder sample 13 is embedded in the resin layer 14. It is configured to be unevenly distributed in the resin layer 14 so that the number density increases toward one surface side.

(Processing process)
Subsequently, the resin-embedded sample 10 is processed into a shape suitable for TEM. Specifically, for example, using a FIB device, as shown in the broken line region of FIG. 1 (c), a part of the powder sample 13 of the resin-embedded sample 10 is used as a sample piece from the region on the surface side where the powder sample 13 is unevenly distributed. By cutting and slicing, the TEM sample 20 shown in FIG. 1 (e) is obtained.

As described above, the TEM sample 20 is prepared.

<Effect of this embodiment>
According to this embodiment, one or more of the following effects are exhibited.

In the present embodiment, the powder sample 13 is sprayed on the coating layer 12 made of a liquid resin and settled in the coating layer 12 by its own weight. Therefore, even when the filling amount of the powder sample 13 is increased, the powder is powdered. It is possible to prevent the powder sample 13 from being damaged and deteriorated as in the case where the sample 13 is added to the liquid resin and mixed. Moreover, by spreading the liquid resin at the interface between the powder samples 13 in the sedimentation process, the formation of voids due to the aggregation of the powder samples 13 can be suppressed. Then, after sedimentation, the liquid resin is cured in a state where the powder sample 13 is unevenly distributed on one surface side of the coating layer 12, so that the resin embedding has a higher number density toward one surface side. Sample 10 can be prepared. According to this resin-embedded sample 10, by collecting a sample piece from the unevenly distributed surface side of the powder sample 13, a TEM sample 20 having a high number density of the powder sample 13 and excellent analysis efficiency is produced. be able to. Therefore, according to the present embodiment, it is possible to increase the number density of the powder sample 13 while suppressing alteration and aggregation of the powder sample 13, and to improve the analysis efficiency and analysis accuracy by the TEM.

It is preferable to use a thermosetting resin or a photocurable resin as the liquid resin. According to such a resin, the powder sample 13 can be unevenly distributed in the sedimentation direction of the resin layer 14 by forming the coating layer 12 and precipitating the powder sample 13 and then curing the powder sample 13.

Further, it is preferable to use a room temperature curable resin as the liquid resin, and among them, a room temperature curable epoxy resin is more preferable. According to the room temperature curable resin, heating is not required, and the coating layer 12 can be gradually cured while the powder sample 13 is settled on the coating layer 12 in the sedimentation step, so that the step can be shortened. The production of the resin-embedded sample 10 can be simplified.

Further, it is preferable to roughen the surface of the substrate 11 to which the liquid resin is applied. As a result, the surface tension of the liquid resin applied to the substrate 11 can be reduced. As a result, the coating layer 12 can be formed thinly, the time for the powder sample 13 to settle in the coating layer 12 can be shortened, and the resin-embedded sample 10 can be formed with high productivity.

<Other Embodiments>
Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment and can be appropriately modified without departing from the gist thereof.

In the above-described embodiment, the case where the TEM sample 20 is prepared from the resin-embedded sample 10 has been described, but the present invention is not limited to this, and the shape can be appropriately changed to a shape suitable for other analytical methods. For example, it can be processed into a sample of any microscope field such as a scanning electron microscope (SEM) and a scanning probe microscope (SPM).

Further, in the roughening step, as long as an appropriate surface roughness can be imparted to the substrate 11, the roughening method is not particularly limited, but as shown in FIG. 2A, one abrasive material is applied to the surface of the substrate 11. It is preferable to move it in the direction (the direction of the arrow in the figure) to roughen it. By roughening in this way, a streak-like groove 15 can be formed on the surface of the substrate 11, and the TEM sample 20 can be efficiently produced from the resin-embedded sample 10. Specifically, as shown in FIG. 2B, the surface shape of the substrate 11 is transferred to the unevenly distributed surface of the powder sample 13 in the resin-embedded sample 10. When the TEM sample 20 is prepared from the resin-embedded sample 10, it is necessary to collect a smooth region from the surface side where the powder sample 13 is unevenly distributed in the resin-embedded sample 10, but when the substrate 11 is polished in one direction. Since a large amount of smooth region can be left as compared with the case of polishing in a random direction, the TEM sample 20 can be efficiently prepared.

Further, in the above-described embodiment, the case where the powder sample 13 is sprayed on the coating layer 12 and allowed to stand to naturally settle due to the weight of the powder sample 13 has been described, but the present invention is not limited to this. In the present invention, from the viewpoint of obtaining the above-mentioned effects and promoting the sedimentation of the powder sample 13 to shorten the time until the powder sample 13 is settled, an external force is applied to the powder sample 13 forcibly as shown below. It can also be settled.

For example, as shown in FIG. 3, it is preferable to spray the powder sample 13 on the coating layer 12 and then place the plate-shaped member 30 on the coating layer 12. According to the plate-shaped member 30, by pushing the powder sample 13 into the coating layer 12, the time until the powder sample 13 starts to settle in the coating layer 12 can be shortened. Thereby, the production efficiency of the resin-embedded sample 10 can be improved. As the plate-shaped member 30, the coating layer 12 does not have to be significantly deformed, and for example, a metal foil such as a resin film or an aluminum foil can be used.

Further, for example, after spraying the powder sample 13 on the coating layer 12, a centrifugal force in the direction of the substrate 10 may be applied to the powder sample 13. Specifically, the substrate 10 on which the powder sample 13 is sprayed on the coating layer 12 may be placed on, for example, a centrifuge and rotated. According to the centrifugal force, the time until the powder sample 13 is settled can be significantly shortened, and the production efficiency of the resin-embedded sample 10 can be further improved. Moreover, since the powder sample 13 can be forcibly settled, a resin having a relatively high viscosity can be used as the liquid resin constituting the coating layer 12. Further, the filling amount of the powder sample 13 in the coating layer 12 is not limited and can be changed as appropriate. That is, according to the centrifugal force, the powder sample 13 can be forcibly settled regardless of the viscosity of the liquid resin, so that the filling amount of the powder sample 13 can be increased. On the other hand, according to the centrifugal force, the powder sample 13 can be more unevenly distributed in the coating layer 12, so that the desired high number density can be maintained even when the filling amount of the powder sample 13 is reduced. can.

Further, for example, when the powder sample 13 is a magnetic particle, the powder sample 13 may be sprayed on the coating layer 12 and then a magnetic force may be applied to the powder sample 13 in the direction of the substrate 10. Specifically, after spraying the powder sample 13 on the coating layer 12, a magnet may be arranged on the outside of the substrate 10. According to the magnetic force, the time until the powder sample 13 is settled can be shortened, and the production efficiency of the resin-embedded sample 10 can be improved.

Hereinafter, the present invention will be described based on more detailed examples, but the present invention is not limited to these examples.

(Example 1)
A polyimide film was prepared as a substrate, and a paper scraper (mesh: No. 1000) was moved in one direction to roughen one surface to scratch it. Next, an epoxy resin (“MA2 +” manufactured by PRESI, curing temperature: normal temperature, curing time: 8 hours) was prepared as a liquid resin and applied to the roughened surface of the polyimide film to form a coating layer having a predetermined thickness. .. Next, the battery positive electrode active material was sprayed on the coating layer as a powder sample. After spraying, an intact polyimide film as a plate-like member was placed on the coating layer and allowed to stand as it was until the epoxy resin was cured in order to promote the sedimentation of the powder sample on the liquid resin. After curing, the substrate was removed to obtain a resin-embedded sample in which powder samples were unevenly distributed on one side.

According to the resin-embedded sample of Example 1, it was confirmed that the powder sample can be immediately identified when the sample piece is microsampled from the surface on the side where the sample powder is unevenly distributed using the FIB device. Further, it was confirmed that the sample piece obtained by microsampling contains many powder samples, has a wide effective range when observing by TEM, and is excellent in time efficiency when observing.

(Comparative Example 1)
In Comparative Example 1, a resin-embedded sample was prepared in the same manner as in Example 1 except that the positive battery active material was added to the epoxy resin, mixed with a nail tooth branch, and then cured. When the resin-embedded sample of Comparative Example 1 was microsampled by the FIB apparatus, it was confirmed that the observation efficiency by TEM was low because the number density of the powder sample was low and it took time to determine the sampling location.

(Comparative Example 2)
In Comparative Example 2, a coated metal powder was used instead of the battery positive electrode active material as the powder sample, and more powder samples than in Example 1 were mixed with the liquid resin in order to increase the number density. A resin-embedded sample was prepared in the same manner as in Example 1. As a result of TEM observation using this resin-embedded sample, it was confirmed that the coating material on the surface of the powder particles was peeled off due to the stress during mixing, and the original shape of the sample could not be captured.

As described above, by precipitating the powder sample in the coating layer of the liquid resin and then curing it to prepare a resin-embedded sample, the number density of the powder sample is increased to improve the analysis efficiency, and the powder sample is improved. It was confirmed that the aggregation and alteration of the sample can be suppressed.

10 Resin-embedded sample 11 Substrate 12 Coating layer 13 Powder sample 14 Resin layer 15 Streaky groove 20 TEM sample 30 Plate-shaped member

Claims (8)

A coating process in which a liquid resin is applied onto a substrate to form a coating layer,
A settling step of spraying a powder sample on the coating layer and causing it to settle in the coating layer.
It has a curing step of curing the coating layer to form a resin layer.
Prior to the coating step, the surface of the substrate to which the liquid resin is to be coated is further roughened with an abrasive in one direction.
In the roughening step, grooves that reduce the surface tension of the liquid resin are formed in a streak shape by extending in one direction on the surface of the substrate.
A method for producing a resin-embedded sample, wherein the powder sample is unevenly distributed from one surface to the other surface in the thickness direction of the resin layer so that the number density increases. The method for producing a resin-embedded sample according to claim 1, wherein the liquid resin is a thermosetting resin or a photocurable resin. The liquid resin is a room temperature curable resin,
The method for producing a resin-embedded sample according to claim 1 or 2, wherein the coating layer is cured while the powder sample is settled in the coating layer, and the curing step is performed together with the precipitation step. The method for producing a resin-embedded sample according to any one of claims 1 to 3, wherein the liquid resin is a room-temperature curable epoxy resin. Wherein in the precipitation step, placing the plate-like member on the coating layer after spraying the powder sample to sediment pushing the powder sample in the coating layer, according to any one of claims 1 to 4 Method for producing a resin-embedded sample. The method for producing a resin-embedded sample according to any one of claims 1 to 5 , wherein in the sedimentation step, a centrifugal force is applied to the powder sample in the direction of the substrate to cause the powder sample to settle in the coating layer. The powder sample is a magnetic particle,
The method for producing a resin-embedded sample according to any one of claims 1 to 6 , wherein in the settling step, a magnetic force is applied to the powder sample in the direction of the substrate to cause the powder sample to settle in the coating layer. Permeation in which the powder sample in the resin-embedded sample obtained by the production method according to any one of claims 1 to 7 is unevenly distributed and a sample piece is collected from a region on the surface side having a high number density to be thinned. A method for producing a sample for a type electron microscope.

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