Method for Preparing Cross-Section Observation Specimen of Metal-Resin Bonding Material

Abstract

To manufacture a high-quality and thin sample for observing a cross section by suppressing a deformation when a joint material of resin and metal is cut.SOLUTION: A method for manufacturing a sample for observing a cross section including a joint interface of a sample material formed by joining a metal material and a rein material includes: a trimming step of cutting a part around an end part where the joint interface of the sample material is exposed and making an edge surface smaller; a burying step of burying the end part into a burying resin to surround a part around the end part; and a cutting step of cutting the end part of the sample material buried in the burying resin and the burying resin to manufacture a piece of an observation sample including the joint interface.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for preparing a cross-sectional observation sample that is carried out when observing a cross-section of a metal-resin bonding material with a transmission electron microscope or the like.

Background Art

[0002] When observing the cross-section of a metal sample or the like with a transmission electron microscope (TEM), it is generally carried out to prepare an observation sample by cutting the sample material into an extremely thin slice using a microtome. In this case, an embedding process is performed to harden the sample material to be an observation sample using a synthetic resin or the like so that the sample does not deform during cutting, making it easier to perform operations with the microtome.

[0003] Patent Document 1 discloses that two resin chips are prepared by placing a photocurable resin on a mirror surface, defining the thickness of the photocurable resin and curing it, placing a sample material on one resin chip, covering the sample material with an uncured photocurable resin, and then placing another resin chip and curing the photocurable resin to prepare a primary sample, and cutting the primary sample according to the purpose to prepare an observation sample.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, when the sample material to be observed is metal or a resin alone, it is relatively easy to prepare an observation sample. However, when the sample material is a bonding material of resin and metal, there is a problem that the observation sample deforms, such as rounding when thinly sliced.

[0006] The present invention has been made in view of such circumstances, and an object thereof is to suppress deformation during cutting of a bonding material between a resin and a metal and to produce a high-quality thin cross-sectional observation sample.

Means for Solving the Problems

[0007] A method for producing a cross-sectional observation sample of a metal-resin bonding material according to the present invention is a method for producing an observation sample of a cross-section including a bonding interface of a sample material obtained by bonding a metal material and a resin material, the method including: a trimming step of cutting a peripheral portion of a tip portion where the bonding interface of the sample material is exposed to reduce the tip surface; an embedding step of embedding the tip portion in an embedding resin so as to surround the tip portion; and a cutting step of cutting the tip portion of the sample material embedded in the embedding resin together with the embedding resin to produce an observation sample composed of a section including the bonding interface.

[0008] Since the tip surface of the material sample is previously reduced by a tip portion processing step and the material sample is embedded with an embedding resin so as to surround the tip portion, the periphery of the material sample is hardened by the embedding resin, and deformation such as the sample becoming rounded during cutting is less likely to occur.

[0009] In the method for producing a cross-sectional observation sample of a metal-resin bonding material according to the present invention, in the embedding step, the sample material may be placed on an embedding resin plate made of an embedding resin, and the embedding resin may be dropped onto the sample material on the embedding resin plate to embed the sample material in the embedding resin.

[0010] In this embedding step, an embedding container or the like is used. However, when a sample material is placed on the bottom surface of the embedding container or the like and the embedding resin is dropped to produce an embedded sample, the periphery of the tip portion of the sample material cannot be surrounded by the embedding resin. By using the embedding resin plate as described above, the periphery of the tip portion of the sample material can be surely surrounded by the embedding resin.

[0011] In the method for producing a cross-sectional observation sample of a metal-resin bonding material according to the present invention, in the cutting step, a knife for producing a section may be applied in a direction orthogonal to the bonding interface, and the sample material may be cut along the bonding interface. By applying a knife for sectioning perpendicular to the bonding interface and cutting, deformation of the sample for observation can be further suppressed.

[0012] In the method for preparing a cross-sectional observation sample of the metal-resin bonding material of the present invention, it is preferable that the tip surface is a square with one side being 50 μm or more and 70 μm or less.

[0013] By using a small sample with one side being 70 μm or less, the burden on the knife can be reduced and deformation of the section can be suppressed. Making one side less than 50 μm makes production difficult. In addition, when the planar shape of the material sample is rectangular, the observation sample is likely to be deformed.

Advantages of the Invention

[0014] According to the present invention, deformation during cutting of the bonding material between resin and metal can be suppressed, a high-quality thin cross-sectional observation sample can be prepared, and high-precision cross-sectional observation can be performed.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Mode for Carrying Out the Invention

[0016] Embodiments of the present invention will be described. The metal resin bonding material 1 used in this embodiment is not particularly limited as long as the metal material 2 and the resin material 3 are bonded by the bonding interface 4. However, as shown in FIGS. 2 and 3, for example, the metal material 2 made of copper with a thickness of about 0.3 mm to 0.4 mm is coated with the resin material 3 made of epoxy resin with a thickness of about several tens of nm to 100 nm. This metal resin bonding material 1 is usually formed in a plate shape with the above thickness, and the resin material 3 is formed on one side thereof.

[0017] Next, when preparing a cross-sectional observation sample for cross-sectional observation of this metal resin bonding material 1 with a transmission electron microscope or the like, it is carried out in the order of a sample material preparation step, a sample material trimming step, a metal film forming step, an embedding step, an embedded sample trimming step, a cutting step, and a section recovery step. Hereinafter, it will be described in the order of the steps.

[0018] (Sample Material Preparation Step) As shown in Fig. 2, it is cut from the plate-shaped metal resin bonding material 1 and cut into, for example, a strip shape with a rectangular shape of 3 mm × 2 mm. The surface of the metal material 2 is polished to form a strip-shaped sample material 11 with a thickness of 0.3 mm to 0.4 mm.

[0019] (Sample material trimming process) The end side surface of the obtained strip-shaped sample material 11 is cut and trimmed with a diamond knife for a microtome. Specifically, the peripheral part is cut off so that the end surface of the strip-shaped sample material 11 has a square surface of 50 μm to 70 μm including the bonding interface. As a result, as shown in Figs. 4 and 5, the tip part 13 of the trimmed sample material 12 is formed in a frustum of a pyramid shape, and the tip surface 13a of the frustum of the pyramid is a square surface of 50 μm to 70 μm. The bonding interface 4 between the metal material 2 and the resin material 3 is also exposed on the tip surface 13a of this square surface.

[0020] (Metal film forming process) A metal film 14 is formed on the surface of the resin material 3 of the trimmed sample material 12 (see Fig. 5). For example, a film formed by vapor deposition of gold (Au) may be formed to a thickness of about 10 nm. This metal film 14 is formed to identify the interface between the resin material 3 and the embedding resin when it is embedded in the embedding resin in the subsequent embedding process.

[0021] (Embedding process) In the embedding process, first, an embedding resin plate 21 is produced from a room temperature curable epoxy resin. This embedding resin plate 21 is formed in a plate shape of a size to be placed on the inner bottom surface of the dish-shaped embedding container 22 as shown in Fig. 7. Specifically, about 2 to 3 drops of the room temperature curable epoxy resin 23 are dropped into the silicon-made embedding container 22, cured at room temperature, taken out from the embedding container 22, and the surface is polished to form an embedding resin plate 21 with both sides parallel and smooth as shown in Fig. 7. The reason for polishing is that when it is cured in the embedding container 22, it is formed in a state where the peripheral part bulges due to surface tension, and mainly the corners are polished to finish smoothly.

[0022] Next, place the obtained embedded resin plate 21 on the inner bottom surface of the embedding container 22, and place the sample material 12 on the embedded resin plate 21. Since the embedded resin plate 21 previously placed in the embedding container 22 has been polished so that its front and back surfaces are formed into flat surfaces, the sample material 12 is horizontally placed on the embedded resin plate 21. Next, drop a room-temperature curable epoxy resin from above the sample material 12 on the embedded resin plate 21 to make the surfaces of the embedded resin plate 21 and the sample material 12 in a state of being filled with the epoxy resin, and cure the epoxy resin in that state. Thereby, an embedded sample 31 (see FIG. 8) in which the sample material 12 is buried in the embedded resin 25 is produced inside the embedding container 22.

[0023] As will be described later, it is necessary to produce an embedded sample in which the periphery of the sample material 12 is surrounded by the embedded resin 25. In this embedding process, if the sample material 12 is placed on the bottom surface of the embedding container 22 and the embedded resin 25 is dropped without using the embedded resin plate 21, the entire sample material 12 cannot be covered with the embedded resin 25, which is not preferable. Also, when dropping the embedded resin into the embedding container 22 and placing the sample material 12 thereon, the sample material is likely to sink due to its own weight. When the sample material 12 is placed after curing the embedded resin, the cured embedded resin does not become flat, so the sample material 12 is inclined and arranged, etc., and in any case, problems occur.

[0024] (Embedded Sample Trimming Process) This embedded sample trimming process is performed by precision trimming after rough cutting. First, take out the obtained embedded sample 31 from the embedding container 22, and trim the whole including the peripheral part of the frustum-shaped tip 13 of the sample material 12 with an ultrasonic cutter (not shown), and scrape off a part of the embedded resin 25 as shown by the dashed line in FIG. 9 (rough cutting).

[0025] Thereafter, the embedded sample 31 after rough cutting is fixed to a sample stage for a microtome (not shown), and as shown in FIG. 10, the rough cut portion is further precisely trimmed with a diamond knife 36 (precision trimming). This precision trimming exposes the tip surface 13a of the sample material 12 and leaves an embedding resin 25 with a substantially uniform thickness around the tip portion 13. For example, the tip surface 13a of the frustum of a pyramid of the sample material 12 described above is surrounded by an embedding resin 25 with a substantially uniform thickness so as to form a square surface of 70 μm to 100 μm with respect to a square surface of 50 μm to 70 μm.

[0026] FIG. 11 shows the embedded sample 32 after being precisely trimmed in this way. The periphery of the tip portion 13 of the sample material 12 is surrounded by an embedding resin 25 with a substantially uniform thickness, and the tip surface 13a of the sample material 12 is exposed from the embedding resin 25.

[0027] (Cutting process) As shown in FIG. 12, with distilled water in the boat 42 on the ultrasonic vibration diamond knife (knife for preparing sections) 41 of the microtome, the embedded sample 32 is cut with the ultrasonic vibration diamond knife 41 to prepare sections (samples for cross-sectional observation).

[0028] At this time, the tip surface 13a of the sample material 12 in the embedded sample 32 is exposed together with the metal material 2, the resin material 3, and the bonding interface 4 as described above. As shown in FIG. 13, it is arranged and cut so that the bonding interface 4 is perpendicular to the length direction of the blade 41a of the diamond knife 41. Thereby, it is possible to cut without deforming the bonding material between the metal material 2 and the resin material 3. Also, the feed rate of the ultrasonic vibration diamond knife 41 with respect to the embedded sample 32 (since the embedded sample 32 is moved with respect to the fixed diamond knife 41, it is the moving speed of the embedded sample 32) is preferably 0.4 mm / second to 0.6 mm / second, and the feed width is preferably 40 nm to 80 nm.

[0029] (Section recovery process) The sections are floating on the surface of the distilled water in the boat 42, and are taken out using an auxiliary tool (not shown) called a loop, and placed on a grid mesh for a transmission electron microscope (hereinafter referred to as a TEM grid mesh).

[0030] The sections placed on the TEM grid mesh in this way are installed in a transmission electron microscope in the state of being placed on this TEM grid mesh and observed.

[0031] In the method for preparing a cross-sectional observation sample of this embodiment, the tip 13 of the sample material 12 is slightly shaved, and for the slightly shaved tip, an embedded sample 32 is prepared in a state where the periphery of the metal material 2 and the resin material 3 is surrounded by the embedding resin 25, and sections are obtained from the portion surrounded by the embedding resin 25, so that deformations such as curling of the sections are less likely to occur. In this case, since the blade is applied for cutting in a direction perpendicular to the bonding interface 4 between the metal material 2 and the resin material 3, deformation of the sections can be more reliably suppressed. Therefore, high-precision cross-sectional observation can be performed using high-quality sections with little deformation.

Example

[0032] For a bonding material composed of a metal material made of copper and a resin material made of an epoxy resin, an embedded sample was prepared by the above method, and sections were prepared using a diamond knife of a microtome. As the diamond knife (knife for section preparation), the "trim45" trimming knife of DiATOME was used as the bonding material and processed into a sample material as described above. The tip surface of the sample material was a square of 50 μm × 50 μm. In addition, a vapor deposition film of gold with a thickness of 10 nm was applied as a metal film on the surface of the resin material.

[0033] On a silicon embedding container, 2 or 3 drops of a room-temperature curing epoxy resin ("NER-814" manufactured by Nisshin EM Co., Ltd.) as an embedding resin were dropped with a dropper, leveled with a pin-shaped object, and then held at room temperature for 48 hours or more to cure. After curing, an embedded resin plate was produced by polishing using SiC waterproof abrasive paper #800. Next, this embedded resin plate was placed in an embedding container, a sample material was placed on it, and further, 2 or 3 drops of a new room-temperature curing epoxy resin were dropped from above and cured to embed the sample material in the embedded resin.

[0034] The sample was taken out from the embedding container and trimmed using an ultrasonic cutter ("EM-240" manufactured by Nisshin EM Co., Ltd.) and a diamond knife ("trim45" manufactured by DiATOME) to obtain the shape shown in Fig. 11. The outer shape of the embedded resin was 90 μm × 90 μm with respect to the tip surface of 50 μm × 50 μm of the sample material. Specifically, it was made 150 - 200 μm × 150 - 200 μm with an ultrasonic cutter and then 90 μm × 90 μm with a diamond knife. Distilled water was filled in the boat of the ultrasonic vibration diamond knife ("ULTRA SONIC" manufactured by DiATOME) of the microtome and held for 30 minutes. Then, the amount of water was adjusted using a syringe, and the embedded sample was cut under the conditions of a feed rate of 0.4 mm / second to 0.6 mm / second and a feed width of 40 nm to 80 nm to produce sections.

[0035] In this case, two types of sections were produced: a section cut with the bonding interface of the sample material perpendicular to the edge of the diamond knife and a section cut with the bonding interface and the edge arranged in parallel. In both cases, the sections were formed with the thickness of the feed width. The obtained sections were placed on a TEM grid mesh using a loop and observed with a transmission electron microscope.

[0036] For comparison, an embedded sample was also produced by directly placing the sample material on the inner bottom surface of the embedding container without using an embedded resin plate and dropping several drops of a room-temperature curing epoxy resin from above to cure it.

[0037] Among the sections prepared as the samples for cross-sectional observation in this way, when cutting with the interface between the blade of the diamond knife and the sample material being parallel, in some of the sections, there was a tendency to round, and in the thinner sections, some could not be placed on the TEM grid mesh. Those cut in the direction perpendicular to the interface between the blade of the diamond knife and the sample material had little deformation and samples of a quality that could be provided as observation samples were obtained.

[0038] Figure 14 is an enlarged photograph of a section obtained from the embedded sample of the example placed on a TEM grid mesh. This section was 40 nm thick and since the four sides were solidified with the embedding resin, it could be recovered as an ultrathin section. Figure 15 shows the state of the section of the comparative example placed on a TEM grid mesh, but the section has become rounded. The image of the section of the example observed with a transmission electron microscope is shown in Figure 16. As is clear from this Figure 16, not only the cross-section of the metal material and the resin material, but also the bonding interface can be clearly captured.

Explanation of Signs

[0039] 1 Metal-resin bonding material 2 Metal material 3 Resin material 4 Bonding interface 11 Strip-shaped sample material 12 Sample material after trimming 13 Tip 13a Tip surface 14 Metal film 21 Embedding resin plate 22 Embedding container 23 Room temperature curing type epoxy resin 25 Embedding resin 36 Diamond knife 41 Ultrasonic vibration diamond knife (knife for section preparation) 41a Blade 42 Boat

Claims

1. A method for preparing an observation sample of a cross-section including a bonding interface of a sample material formed by bonding a metal material and a resin material, comprising: a trimming step of cutting away a peripheral portion of a tip portion where the bonding interface of the sample material is exposed to reduce the tip surface area; an embedding step of embedding the tip portion so as to surround the tip portion with an embedding resin; and a cutting step of cutting the tip portion of the sample material embedded in the embedding resin together with the embedding resin to prepare an observation sample composed of a section including the bonding interface. The method for preparing a cross-section observation sample of a metal-resin bonding material, wherein the tip surface of the sample material is square.

2. The method for preparing a cross-section observation sample of a metal-resin bonding material according to Claim 1, wherein in the embedding step, the periphery of the tip surface of the sample material is surrounded with a uniform thickness such that the tip surface of the embedding resin is square.

3. The method for preparing a cross-section observation sample of a metal-resin bonding material according to Claim 1 or 2, wherein in the cutting step, a knife for section preparation is applied in a direction perpendicular to the bonding interface, and the sample material is cut along the bonding interface.

4. The method for preparing a cross-section observation sample of a metal-resin bonding material according to any one of Claims 1 to 3, further comprising a metal film forming step of forming a metal film on a surface of the resin material of the sample material on the side opposite to the metal material between the trimming step and the embedding step.

Images