JP6773956B2 - Bending and stretching deformation sensor device - Google Patents

Description

The present invention relates to electronic devices that are bendable and stretchable.

In recent years, research on flexible devices having flexibility and elasticity has been actively conducted, and flexible displays and flexible sensor sheets using liquid light emitting materials have been proposed. For example, research results on bendable displays, sensors, solar cells, etc. have been reported in Non-Patent Documents 1 and 2.

Non-Patent Document 1 relates to a deformable inorganic LED device using printing technology, in which small-sized LEDs are arranged on a flexible substrate such as polydimethylsiloxane (PDMS), and the LEDs are arched between the LEDs. The structure of connecting with the metal wiring of is disclosed. In this document, it is shown that this structure can relieve stress applied to LEDs and metal wiring, and can improve resistance to bending deformation.

Non-Patent Document 2 relates to a thin-film Si solar cell having flexibility, and discloses a structure in which a plurality of solar cells called Si microcells having a thickness of, for example, about 15 μm are arranged and connected by metal wiring. In this document, a polymer having a thickness of about 30 μm is sandwiched above and below the microcell, and the microcell is placed on a neutral surface where compression strain and tensile strain are less likely to be applied to bending deformation. It has been shown that such stress can be relaxed and resistance to bending deformation can be improved.

However, although these devices are capable of bending deformation, they have low resistance to stretching deformation. While there is a neutral surface where neither compressive strain nor tensile strain is applied in bending deformation, there is no place where the strain becomes zero in stretching deformation, so the approach of arranging the element and wiring part on the neutral surface allows stretching deformation. This is because the device cannot be realized. On the other hand, many studies have been conducted to realize a device that can be bent as well as stretched and deformed by using an organic material having stretch resistance (see, for example, Non-Patent Document 3).

S.-I. Park et al., "Printed Assemblies of Inorganic Light-Emitting Diodes for Deformable and Semitransparent Displays" Science, vol.325, pp.977-982, 2009. J. Yoon et al., "Ultrathin silicon solar microcells for semitransparent, mechanically flexible and microconcentrator module designs" Nature Materials, vol.7, pp.907-915, 2008. T. Sekitani et al., "Stretchable active-matrix organic light-LED diode display using printable elastic conductors" Nature Materials, vol.8, pp. 494-499, 2009.

As described above, devices based on research such as Non-Patent Documents 1 and 2 are capable of bending deformation while using general metal wiring and semiconductor devices, but resistance to expansion and contraction deformation is obtained. Absent. Non-Patent Document 3 reports a conductive gel that is said to have an extremely high conductivity as a stretchable wiring compared to the conventional one, and has a stretch resistance of 29% and 1.02 × 10 ⁴ S / m. It is reported that there is conductivity of. However, this is very low compared to Au's conductivity of 4.6 × 10 ⁷ S / m. Therefore, from the viewpoint of performance and cost, a device structure with high expansion and contraction resistance, which has high resistance to fracture due to expansion and contraction and fatigue fracture due to repeated expansion and contraction, is provided by using general metal wiring and semiconductor elements. desired.

The present invention has been made in view of such circumstances, and an electronic device that can be bent and deformed and stretched and deformed as compared with the prior art can be used with wiring using a general metal or the like and a semiconductor element. The challenge is to provide.

An electronic device that can be bent and deformed and stretched and deformed according to one feature of the present invention for solving the above problems is a flat plate portion, a hinge portion that can be bent by connecting between the plurality of flat plate portions, and the hinge portion. It includes a gap provided at an intersection between the two, and a neutral surface of the hinge portion in which distortion is substantially zero during bending deformation and expansion / contraction deformation.

According to the device of the present invention, the device has a folding structure consisting of a flat plate portion that is not subjected to bending deformation and a hinge portion that can be bent, and by arranging the wiring on the neutral surface of the hinge portion, wiring can be performed even by bending deformation. It is possible to provide an electronic device that realizes repeated deformation and large deformation without deteriorating at all. By providing a gap at the intersection of the hinges of the two-dimensional folding structure, it is possible to expand and contract two-dimensionally, and it is also possible to bend and deform two-dimensionally, with 3D graphics having a spherical surface or a complicated curved surface. It is possible to attach the device to a free curved surface that is handled (hereinafter, simply referred to as a free curved surface).

FIG. 1A is a schematic view showing a state of bending deformation, FIG. 1B is a schematic view showing a state of expansion and contraction deformation, and FIG. 1C is a schematic view showing a state of folding deformation. A developed view of the Miura fold (registered trademark) and a prototype of Miura fold (registered trademark) shaped paper when no gap is provided. FIG. 2A is a developed view, and FIG. 2B is a photograph and a view showing the developed prototype. 2C is a folded photographic diagram of the prototype, and FIG. 2D is a bent photographic diagram of the prototype. A developed view of the Miura fold (registered trademark) and a prototype of Miura fold (registered trademark) shaped paper when a gap is provided. FIG. 3A is a developed view, FIG. 3B is a photographic view of the prototype, and FIG. 3C is a trial. It is a bent photograph of the work. It is explanatory drawing of the Miura fold (registered trademark) shape electronic circuit board of embodiment of this invention, FIG. 4A is a figure which shows one unit of an electronic circuit board, and FIG. 4B is one of the parallelograms in one unit. FIG. 4C is a diagram showing the yz plane in one unit. Same as above, it is a side view showing the structure of an electronic device, FIG. 5A is a view showing a structure in a state where the electronic device is unfolded, and FIG. 5B is a view showing a structure in a state where the electronic device is bent. Same as above, the manufacturing process of the electronic circuit board is shown. FIG. 6A is a diagram showing a polyimide copper substrate, FIG. 6B is a diagram showing a cut of a wiring layer and a wiring protection layer, and FIG. 6C is a diagram and a diagram showing copper patterning. 6D is a diagram showing the fabrication of the support layer, FIG. 6E is a diagram showing the cut of the support layer, FIG. 6F is a diagram showing the transfer of the support layer, and FIG. 6G is a diagram showing the folding of the device. Same as above, it is a photographic diagram showing a mold for forming a Miura fold (registered trademark) shape, FIG. 7A is a photographic diagram showing a lower mold, FIG. 7B is a photographic diagram showing an upper mold, and FIG. 7C is an upper mold and A photographic view showing a state in which the device is fitted between the lower molds, and FIG. 7D is a photographic view showing a state in which the device is formed in a Miura fold (registered trademark) shape. In the same as above, it is a figure for demonstrating the neutral surface of the hinge part, FIG. 8A is a figure in the case of a three-layer structure, and FIG. 8B is a figure in the case of a two-layer structure. The same is the stress distribution diagram of the hinge portion in the case of the two-layer structure. In the same as above, it is a figure which shows an example of the shape of a gap, FIG. 10A is a figure when a gap is provided in a parallelogram shape in one parallelogram in one unit, and FIG. 10B is a view between a point a and a point c. The figure when connecting with a straight line, FIG. 10C is a figure when connecting points a and c with an outwardly bulging curve, and FIG. 10D is a diagram connecting between points a and c with an inwardly bulging curve. It is a figure. Same as above, it is a side view showing the structure of the device for evaluating spherical followability, FIG. 11A is a diagram showing a structure in a state where the device is unfolded, and FIG. 11B is a diagram showing a structure in a state where the device is bent. In the same as above, the manufacturing process of the device for evaluating spherical followability is shown, FIG. 12A is a diagram showing a cut of a polyester film layer, FIG. 12B is a diagram showing the production of a support layer, and FIG. 12C is a diagram showing a cut of the support layer. 12D is a diagram showing the transfer of the support layer, and FIG. 12E is a diagram showing the folding of the device. Same as above, it is a photographic figure which shows the appearance of the test apparatus for evaluating the spherical surface followability. The same is the cross-sectional view of the test apparatus for evaluating the spherical followability. Same as above, it is explanatory drawing of the definition of a gap width and a hinge width. Same as above, it is a photographic diagram which shows the standard size spherical followability evaluation device (left) and the 1.5 times size spherical followability evaluation device (right). Same as above, it is a figure which shows the spherical surface followability evaluation result of a standard size and a 1.5 times size. FIG. 18A is a photographic diagram showing a spherical followability evaluation device, FIG. 18A is a photographic diagram showing a spherical followability evaluation device having a gap width of 0 mm as a comparative example, and FIG. 18B is a gap of the embodiment of the present invention. A photographic diagram showing a device for evaluating spherical followability having a width of 1 mm, FIG. 18C is a photographic diagram showing a device for evaluating spherical followability having a gap width of 3 mm according to an embodiment of the present invention, and FIG. 18D is a photographic diagram showing the device for evaluating spherical followability of the present invention. It is a photographic figure which shows the device for evaluation of the spherical surface followability with a void width of 5 mm of an embodiment. It is a figure which shows the spherical surface followability evaluation result at the time of changing the void width. FIG. 20A is a photographic diagram showing a Miura-folded (registered trademark) -shaped electronic device equipped with eight chip LEDs according to an embodiment of the present invention, and FIG. 20A shows an initial state of the electronic device (projected area 100% when viewed from above). ), FIG. 20B is a photographic diagram showing the folding of the electronic device (projected area 25% when viewed from above), and FIG. 20C is a photographic diagram showing the development of the electronic device (projected area 170% when viewed from above). FIG. 20D is a photographic diagram showing bending of an electronic device (radius of curvature 20 mm) and a photographic diagram showing spherical attachment of an electronic device (diameter 200 mm, load 300 N).

Hereinafter, embodiments of a device that can be bent, deformed, and stretched and deformed according to the present invention will be described with reference to the drawings.

First, the basic concept of the present invention will be described. According to the present invention, the sheet-shaped electronic device 1 can be attached to a curved surface and stretched and deformed by using folding.

FIG. 1A is a schematic view showing the state of bending deformation, and there is a neutral surface 101 near the center of the cross section of the object 100, which is not subjected to compressive strain or tensile strain. On the other hand, FIG. 1B is a schematic view showing the state of expansion and contraction deformation, and since tension or compression strain occurs in all regions of the object 102, there is no neutral plane. Therefore, if the light emitting part and the wiring part are made thin and arranged on the neutral surface of the substrate 101, it is easy to realize a flexible device that can be bent and deformed, whereas in the same approach, a flexible device that can be stretched and deformed. Cannot be realized. The inventors take advantage of the fact that an electronic device that can be bent and deformed is easy to realize, and by locally bending and deforming it, the device as a whole can be stretched and deformed while leaving a neutral surface. I came up with.

A folding structure can be mentioned as a means for locally bending and deforming to enable expansion and contraction deformation. For example, by using a bellows fold as shown in FIG. 1C as a one-dimensional folding structure, expansion and contraction deformation can be realized as a whole. In the figure, the upper figure is in a contracted state and the lower figure is in a stretched state. In this case, the device 103 as a whole can be expanded and contracted while leaving the neutral surface 104. Further, as a method of folding a two-dimensional sheet-like object, methods such as bellows folding, Miura folding (registered trademark), Yoshimura pattern, and sea cucumber folding are known.

For example, the development view of Miura fold (registered trademark), which is also used for the development structure of solar cell panels in space, is as shown in Fig. 2A, and the folds 105 shown as mountain folds and valley folds in the figure. By bending in each direction, it becomes possible to fold it. However, when considering the degree of freedom of deformation, it is known that the Miura fold (registered trademark) has one degree of freedom, and only a certain degree of expansion and contraction deformation can be performed. For example, when the structure of the Miura fold (registered trademark) shown in FIG. 2B is to be bent, it can be two-dimensionally expanded and contracted into a cylindrical shape as shown in FIG. 2C in a certain direction, but in another direction. As shown in FIG. 2D, the saddle shape is warped. Therefore, the shape cannot cover the spherical surface.

As a result of the study, the inventors can obtain a degree of freedom that can be attached to a free curved surface by making a gap (hole) 106 that penetrates the paper at the intersection of the creases 105, as shown in the developed view of FIG. 3A. I found that for the first time. That is, it was found that by using the structure of Miura fold (registered trademark) having a gap 106 as shown in FIG. 3B, it can be bent as shown in FIG. 3C without warping the saddle shape. With such a structure, it is possible to realize a telescopic device that can be two-dimensionally stretched and deformed or attached to a free curved surface as a whole device while leaving a neutral surface.

As an application example using the Miura fold (registered trademark), there is a prior art in which through holes are provided at the intersections of the dividing lines that divide the area where the solar cell modules are arranged in the sheet in which the solar cells are arranged ( JP-A-2015-88561). However, this prior art is merely configured to suppress the influence of distortion due to folding and to fold more compactly when folded by Miura fold (registered trademark). There is no description about the fact that by using folding that locally bends and deforms, it is possible to expand and contract as a whole while having a neutral surface without distortion, and it is possible to attach it to a curved surface.

Next, as an embodiment of the electronic device according to the present invention, the configuration of the electronic device 1 using the Miura fold (registered trademark) will be described.

In designing the dimensions of the Miura fold (registered trademark) -shaped substrate, the relationship between the shape of the Miura fold (registered trademark) and the variables will be described with reference to FIGS. 4A to 4C. FIG. 4A shows one unit of Miura fold (registered trademark) having four parallelogram faces as repeating units. The parallelogram ABCD in the unit of FIG. 4A is represented by the surface height L _a [mm] and the surface length L _b [mm], and the acute angle γ [deg] of the parallelogram ABCD as shown in FIG. 4B. The shape of one unit is determined by these three variables and the four variables of the angle ψ [deg] between the xy plane and the Miura fold (registered trademark) plane shown in FIG. 4C. Assuming that the angle between the Y-axis and the side AB is ζ [deg], the acute angle γ and the angle ψ of the parallelogram ABCD are related to Eq. (1).

From equation (1), the angle ζ can be expressed as equation (2).

Further, 2a in FIG. 4A and 2b and h in FIG. 4C can be represented by the formulas (3) to (5), respectively. The thickness of the substrate is ignored.

Based on these, the dimensions of the Miura-folded (registered trademark) -shaped substrate can be designed.

As an example, to have a size of the substrate from the plane can be folded by hand to a three-dimensional, L _a, L _b, gamma, the ψ as follows.

Ζ, 2a, 2b, and h are calculated from the equations (2) to (5) as follows.

These dimensions are adopted in the electronic circuit board, the device for evaluating spherical followability, and the electronic device manufactured in the present embodiment. Furthermore, as shown in FIG. 4A, the parallelogram surface is one unit with four surfaces, and there are a total of 25 units (10 surfaces vertically and 10 surfaces horizontally), 5 units vertically and 5 units horizontally. It was a device.

FIG. 5A shows the basic structure of the electronic circuit board 10 on which the mounted object 2 of the present embodiment is mounted. In FIG. 5B, the electronic circuit board 10 of FIG. 5A is bent. A flat portion that cannot be bent is connected between the flat plate portion 3 and a plurality of flat plate portions 3, and the bendable portion is a hinge portion 4. The flat plate portion 3 of the electronic circuit board 10 has a three-layer structure of, for example, a wiring layer 11 made of copper, a wiring protection layer 12 made of polyimide, and a support layer 15 made of, for example, Kent paper 13 and double-sided tape 14. The support layer 15 is not formed on the hinge portion 4. Kent paper 13 was used as the constituent material of the support layer 15 of the flat plate portion 3 from the viewpoint of ease of processing and hardness. The support layer 15 has a role of forming a flat surface 16 for arranging the mounted object 2 and a role of facilitating folding along a groove 17 formed in the Kent paper 13 when folding from the flat surface 16. The mounted object 2 mounted on the flat plate portion 3 may include, for example, at least one electronic element, optical element, light emitting element, sensor element, semiconductor element, power generating element, piezoelectric element, battery element, actuator element, and the like. However, it is not limited to these. Since no stress is applied to the mounted object 2 even during bending deformation and expansion / contraction deformation, the material of the mounted object 2 can include at least one inorganic material, metal material, semiconductor material, organic material, and the like. That is, devices such as optical elements and sensors that do not have stretch resistance can be arranged on the flat plate portion 3, and by using an inorganic material, a metal material, a semiconductor material, and an organic material, the performance of the electronic device 1 is improved. And / or cost reduction and / or high stretch resistance can be achieved. Here, although the organic material has a certain degree of elasticity as described above, further expansion / contraction resistance can be obtained by the electronic device 1. As the organic material, for example, a rubber material, a gel material, or the like can be used. For example, even organic materials such as carbon nanotubes (CNTs) and graphene have almost no stretch resistance, but the electronic device 1 can impart stretch resistance to these.

An example of a method for manufacturing the electronic circuit board 10 having the structure will be described with reference to FIGS. 6A to 6G. First, a polyimide copper substrate 18 (manufactured by Panasonic, R-F775) having 18 μm-thick copper layers 20 and 21 on both sides of a 50 μm-thick polyimide 19 is prepared in advance (FIG. 6A). This substrate 18 is cut into an unfolded planar shape by a cutting plotter device (manufactured by GRAPHTEC, CE6000-40) (not shown) (FIG. 6B). For example, in the case of Miura fold (registered trademark), it is cut into a shape as shown in FIG. 3A. The shape and size of the gap provided at the intersection of the hinge portions 4 will be described later. By using a cutting plotter device, it is possible to automatically cut an object into a desired shape by preparing data of the shape to be cut and setting pressure, speed, etc. as cutting conditions. When cutting, attach the sample to the special mount 22 of the sticky cutting plotter. Next, the copper layer 20 on one side of the substrate 18 is processed into a desired wiring shape, and the copper 21 on the other side is removed (FIG. 6C). On the other hand, double-sided tape 14 (3M, 4591HH) with a thickness of 0.092mm and an adhesive strength of 4.3N / cm on one side of Kent paper 13 (made by Sakae Paper Industry, Silver Hill Kent paper S115) with a thickness of 220 μm. Is pasted (Fig. 6D). The Kent paper 13 to which the double-sided tape 14 is attached is attached to the special mount 23 of the cutting plotter, and is cut off by the cutting plotter device (FIG. 6E). Subsequently, the adhesive surface of the double-sided tape 14 and the polyimide 19 are bonded together, and then removed from the special mount 23 (FIG. 6F) to prepare a substrate. At this time, since the adhesive strength of the double-sided tape 14 is stronger than the adhesive strength of the special mount 23 of the cutting plotter, transfer is possible. In the present embodiment, as described above, Kent paper 13 and double-sided tape 14 are used as the support layer 15 from the viewpoint of ease of processing and the like. However, the material of the support layer 15 is not limited to these, and various materials described later as examples of the substrate material can be used by performing a process such as laminating and patterning.

FIG. 6G shows how the planar substrate is bent, and FIGS. 7A and 7B are photographic views showing the entire upper mold 24 and lower mold 25 used at that time. The upper mold 24 and the lower mold 25 can be manufactured by, for example, a 3D printer (manufactured by Stratasys, ObjectEden260v). Fold the sheet of the electronic circuit board 10 of FIG. 6F by hand to the extent that creases are formed, fit it into the upper mold 24 and lower mold 25 as shown in FIG. 7C, and press from one side or both sides. Therefore, the bent electronic circuit board 10 can be manufactured. Note that FIG. 7D shows a molded product that is folded and molded using paper and a polyester film for convenience for easy viewing. In the present embodiment, the electronic circuit board 10 has a Miura fold (registered trademark) shape, but the above-mentioned manufacturing method can be applied to the manufacturing of devices of other folding methods. In the case of a smaller scale microscale, it can be folded by incorporating a mechanism called self-folding that automatically folds.

The wiring 7 (wiring layer 11 in FIG. 5A) of the present embodiment has a flat plate portion 3 that cannot be bent and a neutral surface 6 of a hinge portion 4 that has substantially zero distortion during bending deformation and expansion / contraction deformation. It is arranged in the vicinity. The neutral surface 6 is a surface on which the bending stress becomes 0 N / m ² when bending deformation is applied and expansion and contraction deformation does not occur. Since there is a concern that the hinge portion 4 may be broken due to repeated folding of the substrate, the influence of distortion on the wiring 7 is reduced by providing the wiring 7 in the vicinity of the neutral surface, and even if the hinge portion 4 is repeatedly folded and deformed, the wire is broken. It can be difficult to do. The vicinity of the neutral surface does not necessarily include the above-mentioned neutral surface 6, but it is preferable to include the neutral surface 6 up to a region where it can be said that there is almost no influence of deterioration due to distortion on the wiring 7. It is more preferable that it contains. The fact that there is almost no effect of deterioration due to distortion means that even if the device is deformed, the wiring 7 is hardly mechanically and electrically deteriorated due to the deformation. For example, the wiring 7 is deformed only in the elastic region and is used in a region where it is not plastically deformed. Specifically, although it depends on the material of the wiring 7, the stress applied to the wiring 7 when bent and deformed is equal to or less than the yield stress or proof stress of the material of the wiring 7 and the fatigue limit. It is preferable that it contains. Further, since the wiring 7 is not affected by the strain, the material of the wiring 7 can include at least one of an inorganic material, a metal material, a semiconductor material, and an organic material. As the organic material, a rubber material, a gel material, CNT, graphene, or the like can be used as in the case of the mounted object 2. While the flat plate portion 3 is left as it is and the hinge portion 4 can be bent to achieve expansion and contraction deformation by local bending deformation, the wiring 7 is arranged on the neutral surface 6 of the hinge portion 4 to bend the hinge portion 4. The wiring 7 is not deteriorated at all by the deformation. That is, since only the region that does not deteriorate, such as the elastic region of the wiring 7, is used, it is possible to realize repeated deformation and large deformation of the electronic device 1 without fatigue fracture due to plastic deformation.

The wiring 7 is provided in the vicinity of the neutral surface 6 at least a part of the hinge portion 4. Further, when the wiring 7 is provided on at least a part of the hinge portion 4 without mounting the object 2 to be mounted, it can be used as an electric wiring that can be bent and deformed and stretched and deformed. Further, when the object 2 to be mounted is not mounted and the wiring 7 is not provided, it can be used as an electronic circuit board capable of bending deformation and expansion / contraction deformation. It is also possible to mount the object 2 to be mounted and not to provide wiring.

Most of the conventional telescopic electronic devices are intended to have stretch resistance only by using an organic material. However, if sensors and wirings such as inorganic materials, metal materials, and semiconductor materials can be used in addition to organic materials, it is possible to realize an electronic device having overwhelmingly high performance and low cost. The present invention focuses on a structure such as an origami structure or a foldable structure, and provides high elasticity as a whole device while using the above-mentioned materials having high functionality, high performance, and high sensitivity. INDUSTRIAL APPLICABILITY According to the present invention, a high-performance and low-cost large-deformable telescopic electronic device can be realized.

Here, the position of the neutral surface 6 of the hinge portion 4, which has an important meaning in the present invention, will be described. As shown in FIG. 8A, when the hinge portion 4 has a three-layer structure of polyimide / copper / polyimide, assuming that the thickness of the polyimide 30 in the outer layer and the thickness of the polyimide 31 in the inner layer are the same and constant, the neutral surface. Reference numeral 6 exists in the vicinity of the center of the cross section of the copper wiring 32. On the other hand, if the outer layer polyimide 30 is omitted and a copper / polyimide two-layer structure is used, the structure of the device can be simplified. Therefore, the neutral surface 6 in the case of the two-layer structure will be described. In FIG. 8B, the distance from the surface of the copper 34 to the neutral surface 6 is Y _neut [m], the radius of curvature of the hinge portion 4 is ρ [m], the thickness of the copper 34 is t _cu [m], and the polyimide 33. If the thickness of is t _PI [m], the Young's modulus of copper is E _Cu [GPa], and the Young's modulus of polyimide is E _PI [GPa], the sum of the bending stresses of the cross section of the hinge portion 4 is zero. The relationship shown in equation (6) is established.

By solving equation (6) for Y _neut , the position of the neutral plane 6 can be calculated. In this embodiment, a tensile test was performed using copper and polyimide test pieces, and the Young's modulus E _Cu and E _PI were calculated, and the results were E _Cu = 13.1 GPa and E _PI = 1.63 GPa, respectively. Substituting these Young's moduli with the above-mentioned thickness t _Cu = 18 μm of copper 34 and t _PI = 50 μm of polyimide 33 into equation (6), the distance from the surface of copper 34 to the neutral surface 6 solving for Y _neut, the Y _neut = 17.7μm. The stress distribution diagram of the cross section of the hinge portion 4 at this time is shown in FIG. From the stress distribution diagram, it can be seen that the neutral surface 6 exists in the copper wiring 34. That is, the neutral surface 6 can be present on the surface of the hinge portion 4, and in this case, the wiring 7 is arranged on the surface of the hinge portion 4, and the mounted object 2 and the wiring are provided on the flat plate portion 3 which is not subjected to bending deformation. If 7 is arranged, even if the wiring 7 and the mounted object 2 do not have bending resistance and expansion / contraction resistance, the device as a whole can have expansion / contraction resistance. This makes it possible to realize an electronic device 1 that can be stretched and deformed by using a high-performance and highly functional material that does not have bending resistance and stretch resistance, such as an inorganic material, a metal material, and a semiconductor material.

In this embodiment, polyimide is used for the wiring protection layer 12 as the substrate material, but in addition to polyimide, polyethylene terephthalate (PET), polyethylene (PE), polyethylene naphthalate (PEN), acrylic resin (PMMA), etc. ABS resin, Teflon (registered trademark), etc. can be used. Further, the hinge portion 4 may be integrally formed with the flat plate portion 3 by using the same material as the substrate material, but the material of the hinge portion 4 may have elasticity or has elasticity. In some cases, rubber materials such as silicone rubber and acrylic rubber, and gel materials such as hydrogel can be used.

10A-10D show an example of the shape of the void 5. The gap 5 provided at the intersection o of the hinge portions 4 can have various shapes and sizes, but must satisfy a predetermined condition. Even when the gap 5 is provided, if the gap 5 is too small, it will warp as shown in FIG. 3C when it is bent and deformed as in the case where there is no gap 5. When the gap 5 has a sufficient size, a degree of freedom that can be attached to a free curved surface can be obtained as shown in FIG. 3E. On the other hand, the surface area of the surface 40 on which the object to be mounted 2 is mounted can be increased as the gap 5 is smaller. Therefore, it is preferable to make the surface area of the surface 40 on which the object to be mounted 2 is mounted as large as possible while satisfying the size of the gap 5 that can be attached to a spherical surface or a more complicated free curved surface.

In FIGS. 10A to 10E, points a to d are taken so that the distance between the points a and b on the hinge portion 4 and the distance between the points c and d are the same. The distance is the void width W _ho . However, these distances do not have to be the same, and for example, the distance between points a and o does not have to be the same as the distances between points c and o, and the positions of points a to d are It can be arbitrarily set on each hinge portion 4. In FIG. 10A, the side ae and the side ce of the gap 5 are formed parallel to the side oc and the side oa of the hinge portion 4, respectively. Similarly, the sides bf and cf of the gap 5 are parallel to the sides oc and ob of the hinge portion 4, respectively, and the sides bh and dh of the gap 5 are parallel to the sides od and side ob of the hinge portion 4, respectively. There, the side ag and the side dg of the gap 5 are parallel to the side od and the side oa of the hinge portion 4, respectively. In this case, the surface area of the surface 40 on which the object to be mounted 2 is mounted is slightly reduced, but the effect of preventing the saddle-shaped warp is increased.

In FIG. 10B, the side ac connecting the points a and b with a straight line, the side cb connecting the points c and b with a straight line, the side bd connecting the points b and d with a straight line, and the points d and a with a straight line. A gap 5 is formed in a portion surrounded by a side da connecting the above with a straight line. On the other hand, in FIG. 10C, points a and b are connected by an outwardly bulging curve, and between points c and b, between points b and d, and between points d and a. Each is connected by a curve that bulges outward. In this case, the void is formed in a circular shape or a shape close to it. By doing so, the area of the gap 5 can be increased when the gap width W _ho is the same as that in the case of FIG. 10B. On the other hand, as shown in FIG. 10D, a curve bulging inward between points a and b, between points c and b, between points b and d, and between points d and a, respectively. When tied, the area of the gap 5 can be reduced and the surface area of the surface 40 on which the object to be mounted 2 is mounted can be increased when the gap width W _ho is the same as that of FIGS. 10A to 10C. The shape of these voids 5 is not limited to the shapes shown in FIGS. 10A to 10D, and is appropriately designed according to the curvature of the free curved surface to which the electronic device 1 is attached, the size of the mounted object 2 to be mounted, and the like. be able to.

In manufacturing the electronic device 1 according to the present invention, followability to a spherical surface is a major issue. Therefore, an evaluation device using Kent paper and a polyester film having a simple manufacturing process was manufactured, and the followability to a spherical surface was evaluated.

FIG. 11A shows the basic structure of the spherical followability evaluation device 41, which has a configuration corresponding to the electronic device 1 of the present embodiment and is a test device used for evaluating the spherical followability, and is shown in FIG. 11B. Is a bent substrate of FIG. 11A. A polyester film layer 42 was formed in place of the wiring layer 11 and the wiring protection layer 12 of the electronic circuit board 10 of FIG. 5A, and had a two-layer structure with the support layer 15 (Kent paper 13, double-sided tape 14). Since it is considered that the followability to the spherical surface changes depending on the flexural rigidity of the hinge portion 4, attention was paid to the Young's modulus of the substrate material, which is one of the parameters for determining the flexural rigidity, and the polyimide 19 was provided with copper 20 as a wiring. The flexural rigidity of the hinge portion 4 of the polyester film 42 used as a substitute for the one was designed to be about the same. A tensile test was performed using a test piece of polyimide 19 with copper 20 as wiring (polyimide thickness t _PI = 50 μm, copper thickness t _Cu = 18 μm), and the calculated polyimide 19 was copper 20 as wiring. The Young's modulus is E _PICu = 4.92 MPa, and the bending rigidity of the hinge portion 4 of the electronic circuit board 10 in FIG. 5A is 1.13 × 10 ^-6 N / m ² . On the other hand, a tensile test was performed using a test piece of a polyester film 42 having a thickness of t _PE = 125 μm, and the Young's modulus of the polyester film 42 calculated was E _PE = 1.95 MPa, which is polyester when the thickness is 100 μm. The bending rigidity of the hinge portion 4 of the film 42 is 3.17 × 10 ^-6 N / m ² , which is about the same as the bending rigidity of the polyimide copper substrate 10.

In manufacturing the device 41 for evaluating spherical followability, first, a polyester film 42 (TORAY, Lumirror T60) to which a special mount 43 for the cutting plotter is attached is used as a device with a cutting plotter device (GRAPHTEC, CE6000-40). Is cut into a developed planar shape (Fig. 12A). Next, double-sided tape 14 (3M, 4591HH) was attached to one side of 220 μm-thick Kent paper 13 (Silver Hill Kent paper S115, manufactured by Sakae Paper Industry Co., Ltd.) (Fig. 12B), and Kent paper 13 to which the double-sided tape 14 was attached. Is attached to the special mount 44 of the cutting plotter and cut out with the cutting plotter device (FIG. 12C). Finally, the adhesive side of the double-sided tape 14 and the polyester film 42 are stuck together and removed from the special mount 44 (FIG. 12D). At this time, since the adhesive strength of the double-sided tape 14 is stronger than the adhesive strength of the special mount 44 of the cutting plotter, transfer is possible. FIG. 12E shows a state in which a flat substrate is changed to a bent substrate. As in the case of the electronic circuit board of FIG. 6G, the substrate is folded by hand to the extent that creases are formed, and the upper mold is used. A bent spherical followability evaluation device 41 can be manufactured by fitting it into the 24 and the lower mold 25 and pressing it from one side or both sides. The device 41 for evaluating spherical followability has a Miura fold (registered trademark) shape, but the above-mentioned manufacturing method can be applied to the manufacture of devices having other folding methods.

The spherical followability evaluation method and the evaluation result will be described. FIG. 13 shows the appearance of the test apparatus 50 for evaluating the spherical followability. In the test apparatus 50, two hemispherical domes 51 and 52 are superposed in the same direction with the spherical surface facing upward, and a spherical surface followability evaluation device 41 is installed between the two domes to form an upper dome 51. A weight 53 is placed on the top, and a load F [N] is applied from above.

As shown in FIG. 14, the distance H'[mm] from the lower surface 54 of the test apparatus 50 to the upper dome 51 is measured, and the distance between the dome H [mm], which is the distance between the upper dome 51 and the lower dome 52. ] Is calculated. Here, the thickness of the dome 51 and 52 is H _t [mm], and the correction value H _g [mm], which is a value for correcting the individual difference in the size of the dome, is obtained by actual measurement, and the dome is _calculated by the equation (7). Calculate the distance H [mm]. Correction value H _g is vertically 10mm between two dome vertically stacked, horizontal 10mm, sandwiched thick specimen 5 mm, by measuring the distance H _g 'from the lower surface of the lower dome to the upper dome, H _{It is} assumed that the thickness H _{t of the} dome and the thickness 5 mm of the test piece are subtracted from _g '.

When measuring the distance H', consider the case where the upper dome 51 cannot be overlapped in parallel with the lower surface 54 of the test device 50, measure two points on the diagonal lines of the dome 51 and 52, and take the average value. It was.

The dimensions of the evaluation device (La, L _b , γ, Ψ, ζ, 2a, 2b) are as described above, and when the void width W _ho and the hinge width W _hi are defined as shown in FIG. 15, W _ho = 3 mm and W _hi = 1 mm. The thickness of the polyester film is 125 μm. The evaluation device 41 actually produced is the device shown on the left side of FIG. This evaluation device 41 was made to follow a dome of φ200, and the weight of the weight 53 was changed to 50 g, 75 g, 100 g, and after 100 g to 500 g every 50 g for measurement. FIG. 17 shows the measurement results. The vertical axis is the ratio H / L _a [-] of the distance between the dome and the representative dimension, and the horizontal axis is the applied load F [N]. It can be seen that the evaluation device 41 follows the spherical surface as the load increases.

The electronic device 1 according to the present invention can correspond to any scale. In the present embodiment, a standard-scale electronic device 1 having a scale that can be folded by hand is manufactured, but a similarity rule holds for the evaluation of spherical followability, and a large scale with a larger scale and a smaller scale are established. It has been confirmed that it can also be used for the microscale scale of.

Explain that the law of similarity holds by actual measurement. To evaluation device 41 described above, to prepare the length L _b of the height L _a and the surface of the parallelogram plane which is typical dimension, the gap width W _ho and an evaluation device 41 1.5-fold, respectively ' .. The device shown on the right side of FIG. 16 is a 1.5 times device 41'. FIG. 17 shows the result of making the evaluation device 41'follow the dome of φ300 and performing the same measurement as described above in comparison with the measurement result of the evaluation device 41 described above. Than 17, it can be said that since the trend of the plot are equal at each load, similarity rule holds between the typical dimension L _a dome distance H. Therefore, even when the spherical followability is evaluated on a standard scale, the evaluation result can be applied to a large scale or microscale electronic device.

In order to evaluate the influence of the size of the gap 5 on the spherical followability, a device for evaluating the spherical followability with the gap widths W _{ho set} to 0 mm, 1 mm, 3 mm, and 5 mm was produced. Other typical dimensions are the same as the evaluation device 41 described above. The evaluation devices 60, 61, 62, and 63 in which the gap widths W _ho actually created are 0 mm, 1 mm, 3 mm, and 5 mm are shown in FIGS. 18A to 18D, respectively.

Each evaluation device 60, 61, 62, 63 was made to follow a dome of φ200, and the weight of the weight 53 was changed to 50 g, 75 g, 100 g, and after 100 g, up to 500 g every 50 g for measurement. FIG. 19 shows the measurement results, the vertical axis is the ratio H / L _a [-] of the distance between the dome and the representative dimension, and the horizontal axis is the applied load F [N]. In the figure, the dotted line is the boundary that the evaluation device follows, and represents the thickness of the evaluation device. When W _ho is 3 mm and 5 mm, it follows the spherical surface with a low load. On the other hand, when W _ho without opening the gap 5 is 0 mm, the result is far from the thickness of the evaluation device 60 even if the load F is applied by 5 N. Since the hinge widths W _hi of these evaluation devices 60, 61, 62, 63 are 1 mm, in the electronic device 1 of the scale of the present embodiment, if the gap width W _ho is made larger than the hinge width W _hi , spherical tracking is performed. It can be said that the sex becomes higher.

From the evaluation of spherical followability, the spherical followability was improved when W _ho was set to 3 mm and 5 mm. Therefore, in consideration of the surface area of the surface 40 on which the object to be mounted 2 is mounted, the electron according to the present embodiment in which the electronic element is mounted on the Miura fold (registered trademark) shaped electronic circuit board 10 with the void width W _{ho set} to 3 mm. Device 1 was manufactured.

In the electronic device 1, four chip LEDs 70 having a forward voltage of 2.9 V are mounted in series and two in parallel using a special cream solder (Sunhayato, SMX-H05) on the wiring 7, for a total of eight (SMLE12BC7TT86, Rohm), power supply (TEXIO, PA18-3B) (not shown) to give 10.50V, 0.01A. With a voltage applied to the electronic device 1, expansion and contraction deformation and bending deformation were applied. FIG. 20A shows the initial state, FIG. 20B shows the state of contracting to 25% in the area ratio of the projected area seen from above (folding), and FIG. 20C shows the state of expanding to 170% in the same area ratio (expanded). FIG. 20D is a photographic view showing a state of having a cylindrical shape with a radius of 20 mm (bending), and FIG. 20E is a photographic view showing a state of being attached to a spherical dome 71 having a diameter of 200 mm (load 300 N). In either state, the chip LED 70 continued to light. Further, the electronic device 1 was repeatedly folded, unfolded, bent, and spherically followed about 100 times, but the light of the chip LED 70 was not extinguished or dimmed, and no disconnection was confirmed.

Although the embodiments of the present invention have been described above, the present invention can be modified in various ways. For example, as a means for producing a foldable substrate, a method of printing metal nanoparticle wiring on tracing paper using an inkjet printer can be adopted. Further, as a method of automatically folding the substrate without using hands, there is a method of printing a solution on tracing paper using an inkjet printer and utilizing the phenomenon that the paper bends when the solution dries. By using these methods, it is possible to realize an electronic device that is folded up from a flat surface to a three-dimensional structure only by printing.

Further, when applied to an actual device, the electronic circuit board 10 may be covered with an elastic material (for example, polydimethylsiloxane (PDMS)) and attached to an object.

As described above, the present invention realizes a highly functional and high-performance electronic device that can be bent and deformed and stretched and deformed as compared with the prior art by a new highly versatile approach called "origami type device". It opens up new areas for telescopic devices. In a folding structure such as origami, that is, a planar structure composed of a flat plate portion 3 and a hinge portion 4, a structure that provides local bending deformation realizes expansion and contraction deformation of the entire device. By providing a gap 5 at the intersection of the hinge portions 4 of the two-dimensional folding structure, it is possible to expand and contract two-dimensionally, and it is also possible to attach the electronic device 1 to a spherical surface or a more complicated free curved surface. .. Further, the present invention realizes an electronic device 1 that can be expanded and contracted by a folding structure including a flat plate portion 3 and a hinge portion 4, and also forms a stress-free neutral surface 6 on the hinge portion 4, so that the expansion and contraction device In spite of this, by arranging the wiring 7 made of metal or the like in the vicinity of the neutral surface 6 of the bending deformation of the hinge portion 4, the wiring 7 does not undergo plastic deformation, and fatigue failure occurs even in repeated deformation or large deformation. There is nothing to do. Therefore, hard but high-performance and low-cost inorganic materials, metal materials, semiconductor device materials, organic materials and the like can be used.

The electronic device 1 according to the present invention can be used for being attached to a surface formed by a curved surface such as a human body, a robot, or a vehicle body of an automobile or an airplane. When used on moving parts such as the elbows of robots, or when realizing a sensor sheet that can be attached to a person to acquire body temperature and health information, it is an application that requires expansion and contraction during use. The present invention can be considered not only for applications that require expansion and contraction during use, but also for applications that require expansion and contraction for pasting. For example, if it is attached to a cylinder and used, the whole can be covered by simply bending a flat sheet-like device. However, when it is used by being attached to a spherical surface, the entire surface cannot be covered unless the flat sheet-like device is expanded and contracted. These applications are areas where the market is growing in the field of wearable devices and flexible devices. Currently, wristwatch-type health information monitoring devices and smart watches (registered trademarks) are commercially available, but according to the present invention, a wearable telescopic display can be realized.

A large market is expected for tire pressure and slip detection sensors that are used by embedding them in tires. Regarding the measurement of tire pressure, legislation is being developed in various countries around the world. Detection of slip between the tire and the ground greatly contributes to the improvement of automobile safety.

As another application example, application to a sensor embedded in sportswear can be considered. For example, in the development of a swimsuit for swimming, the current high-sensitivity sensor can be used in response to the need to embed a sensor in the swimsuit and measure the fluid resistance of water and the swimsuit. Since it can be expanded and contracted, it can be said that it is highly feasible.

As described above, the electronic device 1 according to the present invention has greatly contributed to the development of the rapidly expanding market for wearable devices such as smart watches (registered trademarks) in recent years, and is further embedded in tires, swimwear and the like. It also has the potential to open up new markets such as built-in sensors.

Although the idea of the present invention is original, it may be realized in a wide range of application fields because it is not only original but also the knowledge of the conventionally realized bendable and deformable device can be directly used. high. According to the electronic device 1 capable of bending deformation and expansion / contraction deformation using folding of the present invention, it is possible to use an inorganic material or a metal material which is expected to have high performance, or a high-sensitivity sensor, so that the performance and sensitivity can be used. In terms of cost, it can overwhelmingly surpass conventional telescopic devices that use only organic materials.

1 Electronic device 2 Mounted object 3 Flat plate part 4 Hinge part 5 Air gap 6 Neutral surface 7 Wiring
11 Wiring layer
12 Wiring protection layer
15 Support layer
W _ho void width
W _hi hinge width

Claims (10)

With multiple flat plates
A plurality of sensor elements mounted on the plurality of flat plate portions, and
A foldable hinge portion having a structure in which the plurality of flat plate portions are connected and folded into a mountain fold or a valley fold so as to be foldable .
The gaps provided at the intersections of the hinges and
At least part of the hinge, music GEO preliminary stretch deformation, characterized in that it comprises the strain at bending deformation and stretching deformation and wiring provided in the vicinity of the neutral plane of the hinge portion is substantially zero Sensor device. The bending and stretching deformation sensor device according to claim 1, wherein the bent state is a bent state in which the angles of mountain folds and valley folds are changed from the initial state following a spherical surface or a free curved surface. The bending and stretching / contracting deformation sensor device according to claim 1 or 2, wherein the state at the time of use is the bent state. The material of the wiring, an inorganic material, metallic material, songs GEO preliminary stretch deformation sensor device according to any one of claims 1 to 3 comprising at least one of a semiconductor material and an organic material. The neutral plane was present on the surface of the hinge portion, the song GEO preliminary stretch deformation sensor device of the wiring any one of claims 1-4 disposed on the surface of the hinge portion. Wherein the flat plate portion, claim 1-5 songs GEO preliminary stretch deformation sensor device according to any one of the further mounting the mountable object other than the sensor element. The material of the mounted object is, an inorganic material, metallic material, songs GEO preliminary stretch deformation sensor device of claim 6, further comprising at least one of a semiconductor material and an organic material. Wherein by bending the hinge portion, the bellows-like folded shape, Miura fold shape, Yoshimura pattern or sea cucumber song according to any one of the folded shape foldable claims 1-7 GEO preliminary stretch deformation sensor device. Songs GEO preliminary stretch deformation sensor device according to any one of claims 1-8 gap width is greater than the hinge width of the hinge portion of the air gap. The flat plate portion includes a structure in which a wiring layer, a wiring protection layer, and a support layer are laminated in this order.
Songs GEO preliminary stretch deformation sensor device according to any one of claims 1 to 9 comprising a structure consisting of the hinge portion are laminated in this order of the wiring layer and the wiring protective layer.