JP2007083317A - Joint structure and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a joint structure that can be joined with another material without requiring a joining member, material or device for welding, an adhesive or the like. <P>SOLUTION: The joint structure has a plurality of columnar structures 1 each having a radius of 500 nm or less on a substrate surface, with the layout spacing, length, radii of the columnar structures 1 partially varying. The top end of the columnar structure 1 is a sphere having a radius of 300 nm or less. The columnar structure 1 is made of a material having a dielectric constant of 2 or larger. The flexural modulus of the columnar structure is 5 GPa or less. The aspect ratio of the columnar structure 1 is 1 to 15. The columnar structure 1 is coated with a thin film having a thickness of 300 nm or less. The columnar structures 1 are formed integrally with a substrate by a transfer method to obtain the joint structure 1. The columnar structures 1 and the substrate are separately formed and then integrated with the substrate to produce the joint structure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bonded structure and a method for manufacturing the same, and more specifically, by forming a fine structure on the surface of a substrate, it is possible to bond to a non-bonded material without using welding or an adhesive. The present invention relates to a bonded structure and a manufacturing method thereof.

  Conventionally, in joining materials, joining using welding or an adhesive, a joining structure via a fastening member such as a hook-and-loop fastener (for example, Velcro (registered trademark)), a bolt, or the like has been adopted.

  However, in these joining structures, for example, there are joining members and materials such as bolts, hook-and-loop fastener bodies, adhesives, and fastening devices such as tooling machines, adhesive applicators, spot welders for fastening bolts. Since they exist, there are problems in various processes due to these constraints.

For example, in welding, it is necessary to take a welding apparatus and measures to prevent sparks, and for the adhesive, it is necessary to cope with the work environment such as solvent volatilization and adhesion to clothes of workers. Further, in the joining by the hook-and-loop fastener, an adhesive is used for fixing the hook-and-loop fastener itself to the material to be joined.
In order to solve these problems, in terms of the environment, for example, measures such as changing the adhesive to a hot-melt non-solvent type have been taken, but the process includes a coating process and a heating process. There are problems such as increase in working time and cost.
Friction welding and the like have also been developed in welding, but this requires very new equipment development and introduction, and does not lead to reduction in process time or cost.

On the other hand, functional substrates and functional elements having organic polymer microprojections, and microbiochips and optical devices using these have been proposed (see, for example, Patent Document 1).
JP 2004-170935 A

  The present invention has been made in view of such problems of the prior art, and the object of the present invention is not to require a joining member / material or device such as welding or adhesive, An object of the present invention is to provide a bonded structure that can be bonded to a mating material and a method for manufacturing the bonded structure.

  As a result of intensive studies to achieve the above object, the present inventor has found that the above object can be achieved by forming a fine columnar structure on the surface of a substrate such as a structure, and has completed the present invention. It was.

That is, the bonded structure of the present invention is a bonded structure including a plurality of columnar structures with a radius of 500 nm or less on the substrate surface,
The columnar structure is characterized in that at least one selected from the group consisting of an arrangement interval, a length and a radius is partially different.

  Moreover, the suitable form of the joining structure of this invention is characterized by the average arrangement | positioning space | interval of the said columnar structure being so small that it leaves | separates from the starting point on the said base | substrate.

  Furthermore, another preferred embodiment of the bonded structure of the present invention is characterized in that the average length of the columnar structure increases as the distance from the starting point on the substrate increases.

  Still another preferred embodiment of the bonded structure of the present invention is characterized in that the average radius of the columnar structure is larger or smaller as the distance from the starting point on the substrate is larger.

  In another preferred embodiment of the bonded structure of the present invention, the columnar structure is made of a material having a dielectric constant of 2 or more.

On the other hand, the manufacturing method of the bonded structure of the present invention, in manufacturing the bonded structure,
The columnar structure and the substrate are integrally formed by a transfer method.

In addition, the manufacturing method of the other bonded structure of the present invention, in manufacturing the bonded structure,
A columnar structure and a substrate are separately formed and then integrated with the substrate.

By forming a fine columnar structure on the surface of a substrate such as a structure, it is possible to join a mating member without the need for joining members / materials / devices such as welding or adhesives.
This makes it possible to simplify and shorten the manufacturing process of industrial products and reduce costs.

  Hereinafter, the bonded structure of the present invention will be described in detail. In the present specification, “%” represents mass percentage unless otherwise specified.

As described above, the bonded structure of the present invention is provided with a plurality of columnar structures on the substrate surface whose radius in a vertical section with respect to the longitudinal direction is 500 nm or less. The radius of the columnar structure is preferably 300 nm or less.
In addition, the columnar structure is such that the arrangement interval, length or radius, and any combination thereof are partially different.

This makes it possible to bond materials without using a van der Waals force acting between the columnar structure and the object to be bonded, without requiring a bonding member such as an adhesive or a device for constructing the bonding member.
Further, by changing each element of the columnar structure, since the bonding strength with the object to be bonded is partially different, detachment from the object to be bonded is facilitated and repeated bonding can be performed.

Here, the mechanism by which the bonded structure of the present invention is bonded to the bonded object will be described.
As shown in FIG. 1, between the atoms, the following general formula F ／ A / D2
(A in the formula represents a constant determined by the substance, and D represents the proximity distance between the columnar structure and the joined body.)
The van der Waals force expressed by

  In addition, as shown in FIG. 2, the bonding structure of the present invention has a plurality of nano-level protrusions, so that the bonding structure of the present invention enters the unevenness on the surface of the object to be bonded at a nano level compared to the micron-level protrusions. Can demonstrate power. Such bonding force requires that D is close to the interatomic bond distance.

When the radius of the columnar structure exceeds 500 nm, the columnar structure is prevented from entering the fine irregularities on the surface of the joined body, and van der Waals force does not work.
On the other hand, if the radius is less than 50 nm, the columnar structures may stick to each other.

Further, the tip of the columnar structure can have various shapes as shown in FIG. 3, but is preferably spherical (FIG. 3d) in particular. Specifically, a spherical surface having a radius of 300 nm or less is preferable.
By being spherical, the columnar structure can more easily enter the fine uneven structure of the surfaces to be joined, and the joining force can be improved.

  FIG. 4 shows the relationship between the tip radius of the columnar structure and the adhesive force. As shown in this graph, if the radius is 300 nm or less, stronger adhesive force than that of the conventional product (surface fastener: adhesive strength 20 to 40 N / cm 2) can be obtained.

  In the bonded structure of the present invention, in consideration of detachment (repeated use) from the bonded object, the columnar structure is preferably disposed so as to have anisotropy. For example, as shown in FIGS. 5 and 6, it is possible to form a direction in which peeling easily occurs by changing part of the columnar structure without changing the arrangement interval.

  Typically, a starting point is set on a substrate on which a plurality of the columnar structures exist, and the arrangement interval, length, radius, and the like of the columnar structures can be changed as appropriate based on the starting point.

  For example, as shown in FIG. 7, the distance between the columnar structures can be reduced as the distance from the starting point 6 on the substrate increases. Note that a plurality of joined structures having different columnar structure arrangement intervals can be formed side by side, such as this joined structure.

  Moreover, the average length of the columnar structure can be increased as the distance from the starting point on the substrate increases. Furthermore, as shown in FIG. 8, when partially changing the length of the columnar structure, temporary fastening and permanent fastening can be selected depending on the strength of the pressing force.

  Furthermore, as shown in FIG. 9, the average radius of the columnar structure can be increased or decreased as the distance from the starting point on the substrate increases.

The “starting point” may be linear or point-like, and a plurality of “starting points” may be provided on one substrate.
In addition, when there are a plurality of columnar structures at the same distance from the starting point, the above “average” is obtained by comparing the average value of the elements for all of them with the corresponding elements of the columnar structure on the starting side from these. Often, it indicates that some of the elements may be reversed.

The columnar structure is preferably made of a material having a dielectric constant of 2 or more (ASTMD150 @ 1 MHz 20 ° C.).
When the dielectric constant is less than 2, the van der Waals force acting at the tip of the columnar structure is not sufficient, and the joining strength tends to be insufficient.

Furthermore, from the viewpoint of controlling the dielectric constant of the material, the columnar structure is preferably a composite material containing a conductive substance.
Examples of such conductive substances include carbon-based materials such as carbon black, graphite, graphite, and carbon nanotubes, metal fine particles such as copper, silver, and nickel, metal fibers such as ITO powder, titanium oxide, and stainless steel fibers. .

Furthermore, the material of the columnar structure is preferably a resin.
When the columnar structure is made of resin, the number of contacts to the fine irregularities on the surface of the object to be bonded is due to the deformation of the columnar structure due to the flexibility and collapse of the resin when it contacts the surface of the object to be bonded. As a result, the bonding strength can be further secured.

Examples of the resin constituting the columnar structure include acrylic resins such as polymethacrylate and polyacrylate, polyamide resins such as 6-nylon and 66-nylon, polyolefin resins such as polystyrene, polyethylene, and polypropylene, polyvinyl chloride, polyurethane, and polycarbonate. , Polyacetal, polytetrafluoroethylene and the like can be suitably used. In addition, composite resin materials such as particle reinforced, fiber reinforced, and mineral reinforced can also be suitably used.
These resins are more preferably materials belonging to the above-described ranges of dielectric constant and flexural modulus.

  In this case, the flexural modulus of the columnar structure is preferably 5 GPa or less. When the flexural modulus exceeds 5 GPa, it becomes difficult to ensure flexibility for the columnar structure to follow the fine uneven shape of the joined body. More preferably, it is 0.3-3GPa.

The columnar structure preferably has an aspect ratio (diameter / height) in the range of 1-15.
If the aspect ratio is less than 1, it is difficult to follow the columnar structure to the adherend, and the overall adhesive strength tends to be lowered. If the aspect ratio exceeds 15, the columnar structure may be broken by an input during pressing.
Furthermore, the aspect ratio is more preferably in the range of 2-4. At this time, the columnar structures are less likely to fall during manufacturing, and the yield can be improved.

In the bonded structure of the present invention, the columnar structure can be coated with a thin film having a thickness of 300 nm or less. For example, the thin film 3 can be formed as shown in FIG.
If the thickness of the thin film exceeds 300 nm, the radius of the tip of the columnar structure becomes too large, and the fine irregularities on the surface to be joined cannot be entered, and the expression of van der Waals force tends to be hindered.

The material constituting the thin film preferably has a dielectric constant of 2 or more as in the above-described columnar structure.
Similarly, the thin film constituent material is preferably a composite material formed by adding a resin or a conductive substance as in the above-described columnar structure.
In addition, the said columnar structure may be a hollow shape formed only with a thin film.

  Such a thin film can be typically formed by a chemical vapor deposition method (CVD) using a vacuum state or plasma, a physical vapor deposition method (PVD), dipping into a solution, or the like.

  In addition, as shown in FIG. 5, for example, the bonding structure of the present invention is formed by projecting a plurality of fine columnar structures 1 on a substrate 4, and such columnar structures are densely packed at about 106 to 1011 pieces / cm2. It is good to have.

Furthermore, the bonding structure of the present invention can have a distribution of adhesive strength.
For example, by arranging the center-to-center distances of the columnar structures at unequal pitches, it is possible to facilitate detachment when reusing or disassembling a strongly bonded adhesive structure.

  In addition, the unequal pitches of the columnar structures can be freely set in any of the vertical and horizontal directions, and each columnar structure or a columnar structure for each unit with an arbitrary number of units. It is also possible to set the distance.

  Furthermore, the columnar structure can be integrally formed on the substrate surface by a transfer method, an injection molding method, or the like. By these methods, it is possible to form a columnar structure on the surface of the composite resin material. Resin material mixed with reinforcing material is generally covered with a skin layer without exposing the reinforcing material to the surface, so the columnar structure composed only of the resin component by softening and molding the resin component of the surface skin layer Can be configured.

In the bonded structure of the present invention, as the base for forming the columnar structure described above, the same material as that of the columnar structure can be used, and various materials can be appropriately selected and used according to the application.
For example, a metal oxide substrate such as silicon or alumina, a resin substrate such as polyimide resin or epoxy resin, metals such as aluminum, iron, titanium, or magnesium, glass, or the like can be used.

Next, the manufacturing method of the joined structure of the present invention will be described in detail.
In the manufacturing method of the present invention, the above-described joined structure is obtained by integrally forming the columnar structure and the substrate by a transfer method.
For example, it is possible to form the columnar structure by thermally deforming the base body by stamp molding or the like and pressing the mold material to flow the resin (FIG. 10a).

In another manufacturing method of the present invention, the columnar structure and the base are separately formed, and then integrated with the base to obtain the above-described bonded structure.
For example, after a columnar structure is formed in advance on a film or the like, it can be integrated with a substrate such as glass, metal, ceramics, or resin (FIG. 10b). Further, it can be formed by embedding a columnar structure produced separately in the substrate surface (FIG. 10c).

Here, the transfer method (nanoimprint method) is a method that enables mass production of an ultra-precision resin surface at a low cost by using a mold finely processed into a nano size. As a mold (stamper) to be used, there are a mold formed by electron beam lithography on silicon, ceramics (SiC) or the like, and a metal mold formed by reversal by electroforming from these. Further, the transfer method includes a heating type (hot embossing method) and an ultraviolet curing type (UV curing method).
FIG. 11 shows the nanoimprint process of the hot embossing method. In the UV curing method, a transparent material such as quartz is used for the mold, and as shown in FIG. 12, a UV curable resin is used for the base material, and the resin is cured by irradiating UV through the mold to obtain a molded product. obtain.

  Note that the columnar structure can also be formed on the surface of the object to be bonded. In this case, the columnar structures also have an effect of being entangled with each other, and a stronger bonding structure can be obtained.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in full detail, this invention is not limited to these Examples.

Example 1
A 200 μm-thick polystyrene (dielectric constant 2.5) film was produced by spin casting. On this surface, a 5 mm square sample in which cylinders having a radius of 90 nm and a height of 1.2 μm were arranged at intervals of 1 mm, 400 nm, 360 nm, 270 nm, 180 nm, and 90 nm by nanoimprinting was prepared.
When the peel adhesive strength with the iron plate was measured using this sample, the adhesive strength gradually increased, so that peeling from the end portion was easy as shown in FIG.

(Comparative Example 1)
A 200 μm-thick polystyrene (dielectric constant 2.5) film was produced by spin casting. On this surface, a 5 mm square sample in which cylinders having a radius of 90 nm and a height of 1.2 μm were arranged at intervals of 90 nm was prepared by the nanoimprint method.
When the peel adhesion strength to the iron plate was measured using this sample, the bond strength was constant, and as shown in FIG. 13, it was difficult to peel off from the end.

(Evaluation methods)
With respect to the tensile adhesive strength, the adherend and the bonded structure of the present invention are combined and 200 g of the weight is placed and left, and then the bonded body and the bonded structure of the present invention are attached to the tensile tester chuck portion with an epoxy adhesive. After fixing with a tension speed of 1 mm / min. The measurement was carried out.
Regarding the tensile peel strength, after attaching an L-shaped iron plate to the adherend and the bonded structure of the present invention with an epoxy adhesive, the L-shaped metal fitting was attached at a tensile speed of 1 mm / min. It was set as the tensile peel strength.

It is the schematic explaining van der Waals force. It is the schematic which shows the mechanism in which the joining structure of this invention exhibits adhesive force. It is a cross-sectional schematic diagram which shows an example of the front-end | tip part of a columnar structure. It is a graph which shows the relationship between the radius of a front-end | tip part, and adhesive strength. It is the schematic which shows an example of the joining structure of this invention. It is the schematic which shows an example of the anisotropy of a columnar structure. It is the schematic which shows the other example of the anisotropy of a columnar structure. It is the schematic which shows the further another example of the anisotropy of a columnar structure. It is the schematic which shows the other example of the anisotropy of a columnar structure. It is the schematic which shows the other example of the joining structure of this invention. It is the schematic which shows the process of a nanoimprint method. It is the schematic which shows UV hardening method. It is a graph which shows the peeling strength of the joining structure of which a columnar structure is unequal pitch and equal pitch.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Columnar structure of this invention 2 To-be-joined body 3 Thin film 4 Base | substrate 5 Columnar structure and the separately produced base | substrate 6 Micron-sized columnar structure 7 Starting point
8 micron size surface

Claims (16)

A junction structure including a plurality of columnar structures having a radius of 500 nm or less on a substrate surface,
A joining structure characterized in that at least one member selected from the group consisting of an arrangement interval, a length and a radius of the columnar structure is partially different.   The joining structure according to claim 1, wherein an average interval between the columnar structures decreases as the distance from the starting point on the base increases.   3. The joined structure according to claim 1, wherein an average length of the columnar structure increases as the distance from the starting point on the substrate increases.   The bonded structure according to any one of claims 1 to 3, wherein an average radius of the columnar structure is larger or smaller as the distance from the starting point on the substrate is larger.   The junction structure according to any one of claims 1 to 4, wherein a tip portion of the columnar structure is a spherical surface having a radius of 300 nm or less.   The joined structure according to any one of claims 1 to 5, wherein the columnar structure is made of a material having a dielectric constant of 2 or more.   The joined structure according to any one of claims 1 to 6, wherein the columnar structure is a composite material containing a conductive substance.   The joined structure according to any one of claims 1 to 7, wherein the columnar structure is made of a resin.   The joint structure according to any one of claims 1 to 9, wherein the columnar structure has a flexural modulus of 5 GPa or less.   The joined structure according to any one of claims 1 to 9, wherein the columnar structure satisfies a range of an aspect ratio of 1 to 15.   The joined structure according to any one of claims 1 to 10, wherein the columnar structure is covered with a thin film having a thickness of 300 nm or less.   The bonded structure according to claim 11, wherein the thin film is made of a material having a dielectric constant of 2 or more.   The bonded structure according to claim 11 or 12, wherein the thin film is a composite material containing a conductive substance.   The bonded structure according to any one of claims 11 to 13, wherein the thin film is made of a resin. In manufacturing the joined structure according to any one of claims 1 to 14,
A method for manufacturing a joined structure, wherein a columnar structure and a substrate are integrally formed by a transfer method. In manufacturing the joined structure according to any one of claims 1 to 14,
A method for manufacturing a joined structure, wherein a columnar structure and a substrate are separately formed and then integrated with the substrate.

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