JP5911330B2 - Radiation detector and manufacturing method thereof. - Google Patents

Description

  Embodiments generally relate to a radiation detector that detects radiation and a method of manufacturing the same.

  A planar X-ray detector using an active matrix has been developed as a new generation X-ray diagnostic detector. This X-ray detector detects the irradiated X-rays and outputs an X-ray image or a real-time X-ray image as a digital signal. In this X-ray detector, X-rays are converted into visible light, that is, fluorescence by a scintillator film, and this fluorescence is converted into signal charges by a photoelectric conversion element such as an amorphous silicon (a-Si) photodiode or CCD (Charge Coupled Device). By acquiring the image.

As a material of the scintillator film, cesium iodide (CsI): sodium (Na), cesium iodide (CsI): thallium (Tl), sodium iodide (NaI), or gadolinium oxysulfide (Gd ₂ O ₂₎ S) or the like is used. The scintillator film can improve resolution characteristics by forming grooves by dicing or the like, or by depositing by a vapor deposition method so that a columnar structure is formed. There are various scintillator materials as described above, and they are properly used depending on the application and necessary characteristics.

  In order to improve the use efficiency of fluorescence and improve sensitivity characteristics, a reflective film may be formed on the scintillator film. In this case, of the fluorescence emitted from the scintillator film, the fluorescence directed to the opposite side with respect to the photoelectric conversion element side is reflected by the reflection film, and the fluorescence reaching the photoelectric conversion element side is increased.

  The reflective film is formed by coating a metal layer with high fluorescence reflectance such as silver alloy or aluminum on the scintillator film, or by applying a light-scattering reflective film made of a light-scattering substance such as TiO2 and a binder resin. It is formed by the method to do. In addition, a method of reflecting scintillator light by bringing a reflecting plate having a metal surface such as aluminum into close contact with the scintillator film instead of forming the reflective film on the scintillator film has been put into practical use.

  A moisture-proof structure for protecting a scintillator film, a reflective film, a reflective plate, and the like from an external atmosphere to suppress deterioration of characteristics due to moisture and the like is an important component for making a detector a practical product. In particular, when a CsI: Tl film or a CsI: Na film, which is a material greatly deteriorated by moisture, is used as a scintillator film, a high moisture-proof performance is required. As a moisture-proof structure, for example, a moisture-proof layer such as aluminum foil is adhered and sealed to the substrate at the periphery to maintain moisture-proof performance, or a moisture-proof layer such as aluminum foil or thin plate and the substrate are connected via a surrounding ring-shaped structure. There are structures that are adhesively sealed.

JP 2009-128023 A JP-A-5-242841

  The flat X-ray detector has a substrate in which TFT and photodiode pixels are formed on a glass plate. In some X-ray detectors, a hat-shaped metal foil or thin plate is used as a moisture-proof body, and the hat collar and the substrate surface are bonded and sealed to form a moisture-proof structure.

  The moisture-proof body is cut into a hat shape by pressing after cutting a metal foil or thin plate. Unnecessary protrusions (burrs) may occur on the metal cut surface. When a moisture-proof body in which burrs are generated on the adhesive layer side of the bag is bonded and sealed to the substrate, the burrs are pushed toward the substrate side, so that there is a risk that the substrate metal wiring and the moisture-proof body burr portion are electrically short-circuited. There is also a risk that the adhesive layer is destroyed by the spring back of the burrs that have been crimped. When the adhesive layer is broken, the moisture-proof performance is remarkably lowered.

  Then, embodiment aims at providing the radiation detector provided with the moisture-proof structure with high reliability.

In order to achieve the above-described object, according to one embodiment, a radiation detector includes an array substrate provided with a photoelectric conversion element layer in which photoelectric conversion elements that convert fluorescence into an electrical signal are arranged, and a surface of the array substrate A scintillator film that is provided so as to cover the photoelectric conversion element layer and converts radiation into fluorescence, and a hat-shaped metal foil or a thin plate, and a protrusion protruding in a direction away from the array substrate is formed on the outer edge. A moisture-proof body that surrounds the scintillator film; and an adhesive layer that bonds the outer periphery of the moisture-proof body and the array substrate.

  Moreover, according to one embodiment, the manufacturing method of a radiation detector covers the said photoelectric conversion element layer on the surface of the array substrate which provided the photoelectric conversion element layer in which the photoelectric conversion element which converts fluorescence into an electric signal was arranged. A step of providing a scintillator film for converting radiation into fluorescence, and a part of a metal plate having a first surface and a second surface that is wider than the scintillator film and larger than the projection height of the scintillator film from the array substrate Forming a recessed portion that is recessed from the first surface deep toward the second surface, the outer surface of the flange portion provided on the outer periphery of the recessed portion, the outer surface of the first surface relative to the inner side Forming a moisture-proof body by cutting by shearing to be displaced in the direction from the first to the second surface, and the moisture-proof body so that the first surface faces the array substrate and surrounds the scintillator film with the moisture-proof body. Outside the body Parts and with said array substrate comprises a the steps of adhesively bonded.

It is a typical perspective view of the radiation detection device by one embodiment. It is a circuit diagram of the radiation detector by one Embodiment. It is a block diagram of the radiation detection apparatus by one Embodiment. It is a partially expanded sectional view of the radiation detector by one Embodiment. It is a top view of the radiation detector by one Embodiment. It is a side view of the radiation detector by one Embodiment. It is an expanded sectional view near a collar part of a moisture-proof body by one embodiment. It is sectional drawing which shows a part of manufacturing process of the moisture-proof body by one Embodiment. It is an expanded sectional view near a collar part of a radiation detector using a moisture proof body in which a burr protruding toward the adhesive layer side is formed.

  Hereinafter, a radiation detector according to an embodiment will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or similar structure, and the overlapping description is abbreviate | omitted. This embodiment is merely an example, and the present invention is not limited to this.

  FIG. 1 is a schematic perspective view of a radiation detection apparatus according to an embodiment.

  The radiation detector 11 of this embodiment is an X-ray plane sensor that detects an X-ray image that is a radiation image, and is used for general medical applications, for example. The radiation detection apparatus 10 includes the radiation detector 11, a support plate 31, a circuit board 30, and a flexible board 32. The radiation detector 11 has an array substrate 12 and a scintillator film 13. The radiation detector 11 detects incident X-rays and converts them into fluorescence, and converts the fluorescence into electrical signals. The radiation detection apparatus 10 drives the radiation detector 11 and outputs an electrical signal output from the radiation detector 11 as image information. The image information output by the radiation detection apparatus 10 is displayed on an external display or the like.

  The array substrate 12 has a glass substrate 16. A plurality of fine pixels 20 are arranged in a square lattice pattern on the surface of the glass substrate 16. Each pixel 20 includes a thin film transistor 22 and a photodiode 21. On the surface of the glass substrate 16, the same number of gate lines 18 as the square lattice rows in which the pixels 20 are arranged extend between the pixels 20. Further, the same number of data lines 19 as the number of square lattice columns in which the pixels 20 are arranged extend between the pixels 20 on the surface of the glass substrate 16. The scintillator film 13 is formed on the surface of the region where the pixels 20 of the array substrate 12 are arranged.

  The scintillator film 13 is provided on the surface of the array substrate 12 and generates fluorescence in the visible light region when X-rays enter. The generated fluorescence reaches the surface of the array substrate 12.

The scintillator film 13 is formed by forming, for example, cesium iodide (CsI): thallium (Tl) or sodium iodide (NaI): thallium (Tl) into a columnar structure by a vacuum deposition method. The thickness of the pillar (pillar) of the columnar structure crystal of CsI: Tl is, for example, about 8 to 12 μm at the outermost surface. Alternatively, gadolinium oxysulfide (Gd ₂ O ₂ S) phosphor particles are mixed with a binder material, applied onto the array substrate 12, fired and cured, and formed into a square column by forming grooves by dicing with a dicer. Then, the scintillator film 13 may be formed. Between these columns, air or an inert gas such as nitrogen (N ₂ ) for preventing oxidation may be enclosed, or a vacuum state may be provided.

  The array substrate 12 receives the fluorescence generated by the scintillator film 13 and generates an electrical signal. As a result, the visible light image generated on the scintillator film 13 by the incident X-rays is converted into image information expressed by an electrical signal.

  The radiation detector 11 is supported by the support plate 31 so that the surface opposite to the surface on which the scintillator film 13 is formed and the support plate 31 are in contact with each other. The circuit board 30 is disposed on the opposite side of the support plate 31 with respect to the radiation detector 11. The radiation detector 11 and the circuit board 30 are electrically connected by a flexible board 32.

  FIG. 2 is a circuit diagram of the radiation detector according to the present embodiment.

  Each photodiode 21 is connected to the gate line 18 and the data line 19 through a thin film transistor 22 which is a switching element. In addition, a storage capacitor 27 is connected to each photodiode 21 in parallel. The storage capacitor 27 may also serve as the capacitance of the photodiode 21 and is not always necessary.

  The photodiode 21 and the storage capacitor 27 connected in parallel to the photodiode 21 are connected to the data line 19 via the thin film transistor 22. A gate electrode of the thin film transistor 22 is connected to the gate line 18.

  The thin film transistors 22 of the pixels 20 located in the same row of the array are connected to the same gate line 18. The thin film transistors 22 of the pixels 20 located in the same column of the array are connected to the same data line 19.

  Each thin film transistor 22 has a switching function for accumulating and discharging charges generated by the incidence of fluorescence on the photodiode 21. The thin film transistor 22 is at least partially composed of a semiconductor material such as amorphous silicon (a-Si) as an amorphous semiconductor, which is a crystalline semiconductor material, or polysilicon (P-Si), which is a polycrystalline semiconductor. Has been.

  In FIGS. 1 and 2, the pixels are described only for 5 rows and 5 columns or 4 rows and 4 columns, but actually, more pixels are formed according to the resolution and the imaging area.

  FIG. 3 is a block diagram of the radiation detection apparatus according to the present embodiment.

  The radiation detection apparatus 10 includes a radiation detector 11, a gate driver 39, a row selection circuit 35, an integration amplifier 33, an A / D converter 34, a parallel / serial converter 38, and an image synthesis circuit 36. Have. The gate driver 39 is connected to each gate line 18 of the radiation detector 11. The gate driver 39 controls the operation state of each thin film transistor 22, that is, on and off. The integrating amplifier 33 is connected to each data line 19 of the radiation detector 11.

  The row selection circuit 35 is connected to the gate driver 39. The parallel / serial converter 38 is connected to the integrating amplifier 33. The A / D converter 34 is connected to a parallel / serial converter 38. The A / D converter 34 is connected to the image composition circuit 36.

  The integrating amplifier 33 is provided on a flexible substrate 32 that connects the radiation detector 11 and the circuit board 30, for example. The other elements are provided on the circuit board 30, for example.

  The gate driver 39 receives the signal from the row selection circuit 35 and sequentially changes the voltage of the gate line 18. The row selection circuit 35 sends a signal for selecting a predetermined row for scanning the X-ray image to the gate driver 39. The integrating amplifier 33 amplifies and outputs a very small charge signal output from the radiation detection panel 21 through the data line 19.

  FIG. 4 is a partially enlarged sectional view of the radiation detector according to the present embodiment.

  On the surface of the array substrate 12, an insulating protective film 28 that covers detection elements such as photodiodes 21 and thin film transistors 22, and metal wirings such as gate lines 18 (see FIG. 1) and data lines 19 (see FIG. 1). Is formed. The scintillator film 13 is formed on the surface of the protective film 28 so as to cover the region where the pixels 20 are arranged.

  A reflection film 14 is provided on the surface of the scintillator film 13. The reflection film 14 reflects the fluorescent light generated in the scintillator film 13 that moves away from the array substrate 12 to the array substrate 12 side. As a result, the amount of fluorescent light reaching the photodiode 21 increases.

The reflective film 14 is formed by a method of depositing a metal having high fluorescence reflectance such as a silver alloy or aluminum on the scintillator film. Alternatively, a reflecting plate having a metal surface such as aluminum adhered to the scintillator film 13, or a diffuse reflecting film 14 made of a light scattering material such as TiO ₂ and a binder resin may be formed by coating. Note that the reflective film 14 is not necessarily required due to characteristics such as resolution and luminance required for the radiation detector 11.

  The radiation detector 11 is provided with a moisture-proof body 15 so as to surround the scintillator film 13 and the reflective film 14.

  FIG. 5 is a top view of the radiation detector according to the present embodiment. FIG. 6 is a side view of the radiation detector according to the present embodiment.

  The moisture-proof body 15 is formed in a hat shape with a raised central portion. The peripheral portion of the moisture-proof body 15 is a flat belt-like collar portion 50. The flange portion 50 is formed in a band shape surrounding the outside of the region where the scintillator film 13 is formed on the surface of the array substrate 12. A top plate portion 51 is formed inside the collar portion 50. The top plate portion 51 is a flat plate portion that is slightly larger than the scintillator film 13. A slope portion 52 is formed between the flange portion 50 and the top plate portion 51.

  The flange 50 faces the array substrate 12. The flange 50 and the array substrate 12 are bonded. The scintillator film 13 (see FIG. 4) and the reflective film 14 (see FIG. 4) formed on the array substrate 12 are covered with the top plate portion 51 and the slope portion 52 of the moisture-proof body 15. The moisture-proof body 15 protects the scintillator film 13 and the reflective film 14 from outside air and humidity.

  The moisture-proof body 15 is made of, for example, an aluminum alloy foil having a thickness of 0.1 mm. The moisture-proof body 15 is formed of an aluminum alloy foil such as A1N30-O material or an aluminum foil. The width | variety of the collar part 50 is 5 mm, for example.

  The array substrate 12 is provided with a terminal group 26 in which ends of the gate lines 18 (see FIG. 1) and the data lines 19 (see FIG. 1) are exposed. The terminal group 26 is arranged along the side of the array substrate 12. The terminal group 26 connected to the gate line 18 and the terminal group 26 connected to the data line 19 are arranged along different sides. These terminal groups 26 are electrically connected to the circuit board 30 (see FIG. 1) via the flexible board 32 (see FIG. 1).

  FIG. 7 is an enlarged cross-sectional view of the vicinity of the collar portion of the moisture-proof body according to the present embodiment.

  An adhesive layer 40 is interposed between the flange portion 50 of the moisture-proof body 15 and the array substrate 12. The adhesive layer 40 is provided in a band shape that surrounds the outside of the region where the scintillator film 13 is formed on the surface of the array substrate 12 along the flange 50. Therefore, at least a part of the flange 50 has a protective film 28 and a wiring 29 extending from the gate line 18 (see FIG. 1) or the data line 19 (see FIG. 1) to the terminal group 26 provided on the outer periphery of the array substrate 12. Opposite the adhesive layer 40.

  The inner edge of the adhesive layer 40, that is, the edge closer to the region where the scintillator film 13 is formed on the surface of the array substrate 12 is located inside the inner edge of the flange 50 over the entire circumference. The adhesive layer 40 is formed of a heat curable or ultraviolet curable epoxy adhesive.

  A burr 53 is formed on the outer edge of the moisture-proof body 15, that is, on the side opposite to the slope portion 52 of the flange portion 50. The burr 53 protrudes in a direction away from the array substrate 12.

  Next, the manufacturing method of the radiation detector of this embodiment is demonstrated.

  First, a photodiode 21, a thin film transistor 22, a gate line 18, a signal line 19 and the like are formed on the surface of the glass substrate 16 to obtain the array substrate 12. Next, a scintillator film 13 and a reflective film 14 are sequentially formed on the array substrate 12. Moreover, the moisture-proof body 15 is manufactured separately.

  FIG. 8 is a cross-sectional view showing a part of the manufacturing process of the moisture-proof body according to the present embodiment.

  The moisture-proof body 15 is manufactured from a roll material of AL alloy foil, for example. First, this roll material is cut into a predetermined length. Thereby, a rectangular metal plate 73 is obtained. The metal plate 73 is pressed in the direction in which the second surface 72 side is pushed in from the first surface 71 side to form the top plate portion 51 and the slope portion 52.

  Thereafter, the metal plate 73 is cut so that the flange portion 50 has a predetermined width. The moisture-proof body 15 is obtained by this outer shape processing. A first die 81 and a second die 82 are used for this outer shape processing. The first die 81 is pressed against the first surface 71 of the metal plate 73, and the second die 82 is pressed against the second surface 72 of the metal plate 73. The first die 81 has a hole 74 having substantially the same shape as the outer shape of the moisture-proof body 15. The outer shape of the second die 82 is slightly smaller than the hole 74 formed in the first die 81. In the outer shape processing, the second die 82 is pushed into the hole 74 of the first die 81, and the metal plate 73 is cut. That is, the metal plate 73 is sheared so as to move relatively in the direction from the first surface 71 side to the second surface 72 side with respect to the portion where the cut portion becomes the flange portion 50. As a result, a burr protruding in the direction from the first surface 71 side to the second surface side is formed on the outer edge of the moisture-proof body 15.

  Next, the array substrate 12 and the moisture-proof body 15 are bonded so that the scintillator film 13 and the reflective film 14 are accommodated in the recessed portion of the moisture-proof body 15, that is, the space surrounded by the slope portion 52 and the top plate portion 51. .

  An ultraviolet curable adhesive is applied to the surface of the flange portion 50 of the moisture-proof body 15 facing the array substrate 12, that is, the first surface 72. The adhesive is applied over the entire circumference of the flange 50. Next, the moisture-proof body 15 to which the adhesive is applied is pressed against the array substrate 12 in a reduced-pressure atmosphere, and both are pressure-bonded. The atmosphere during the pressure bonding is a reduced pressure atmosphere of about 0.1 atm, for example.

  At this time, the first surface 71 side of the flange portion 50 is disposed so as to face the array substrate 12. The burr 53 formed on the outer edge of the moisture-proof body 15 protrudes from the first surface 71 side to the second surface 72 side of the end edge of the flange portion 50. For this reason, the burr 53 protrudes in a direction away from the array substrate 12.

  In this manner, the radiation detector 11 is completed by forming the moisture-proof structure. A wiring is connected to each terminal group 26 of the gate line 18 and the data line 19 of the radiation detector 11 by TAB connection, connected to a circuit after the amplifier, and further incorporated into a housing to complete the radiation detection apparatus 10.

  FIG. 9 is an enlarged cross-sectional view of the vicinity of the buttocks of the radiation detector using the moisture-proof body in which burrs protruding toward the adhesive layer side are formed.

  When the moisture-proof body 80 formed with the burr 83 protruding toward the adhesive layer 40 is used, the burr 83 may break through the wiring protective film (insulating film) formed on the adhesive layer 40 and the array substrate 12. is there. That is, there is a risk that the burrs of the metal moisture barrier 80 and the metal wiring on the array substrate 12 are electrically short-circuited. Further, the burr 83 deformed when the moisture-proof body 80 is pressure-bonded springs back to return to its original shape, and as a result, the adhesive layer 40 may be broken. As described above, when the burr 83 generated when the AL alloy foil is processed into a hat shape is generated on the adhesive layer 40 side, a fatal defect such as an electrical short-circuit and destruction of the adhesive layer may occur. high.

  Therefore, a method of suppressing the occurrence of these defects by deburring at the manufacturing stage of the moisture-proof body is conceivable. As a deburring method, there are a mechanical removal method such as crushing and scraping, and a removal method by chemical polishing and electrolytic polishing. In this case, in addition to the demerit of increased man-hours due to deburring, there is a concern about contamination of the AL hat with scraps and abrasive chemicals.

  However, according to the present embodiment, the direction of the burr 53 generated when the AL alloy foil is processed into a hat shape is managed so as to be opposite to the adhesive layer 40. As a result, the outer edge of the moisture-proof body 15 has a structure in which burrs are generated on the opposite side of the adhesive layer 40 and the array substrate 12. In this structure, an electrical short circuit between the burr 53 and the substrate metal wiring does not occur, and the stress due to the spring back of the burr portion does not work in the direction of peeling off the adhesive layer, so that the adhesive layer does not break. Therefore, defects that may occur due to the burr 53 can be avoided without increasing the deburring process.

  As described above, by managing the direction of the burr 53 generated on the outer edge of the moisture-proof body 15 formed of a hat-shaped metal foil or metal plate having high moisture-proof performance so as to be opposite to the adhesive layer 40, 53 has a structure formed on the opposite side to the adhesive layer 40. For this reason, it is possible to prevent the occurrence of defects such as an electrical short circuit with the metal wiring of the array substrate 12 and the destruction of the adhesive layer due to the spring back of the burr 53 after the adhesive is bonded. As a result, the radiation detector 11 having a highly reliable moisture-proof structure that is stable in terms of electrical and strength can be obtained.

  Further, the material of the moisture-proof body 15 is not limited to AL or AL alloy, and the same applies when other metal materials are used. In the case of AL or AL alloy foil material, since the X-ray absorption coefficient is small as a metal material, there is a great merit in that the X-ray absorption loss in the moisture-proof body 15 can be suppressed. Is excellent in workability.

  Adhering the moisture-proof body 15 to the array substrate 12 in a reduced-pressure atmosphere is also effective in that a moisture-proof structure excellent in mechanical strength under reduced pressure assuming airplane transportation can be formed. When sealed in a reduced-pressure atmosphere, the risk of adhesive layer destruction increases because the AL hat is pushed at the external atmospheric pressure. According to the present embodiment, the risk of destruction of the adhesive layer due to the spring back of the burr can be eliminated, which leads to improvement in the reliability of the adhesive part when sealed in a reduced pressure atmosphere.

  In the present embodiment, the moisture-proof body 15 performs the outer shape shearing process after the top plate part 51 and the inclined surface part 52 are pressed, but may be subjected to the pressing process after the outer shape process. Alternatively, for example, when both sides of the roll material are used as outer edges as they are, the outer shape may be subjected to shearing before and after pressing.

  Although one embodiment of the present invention has been described, this embodiment is presented as an example and is not intended to limit the scope of the invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 ... Radiation detection apparatus, 11 ... Radiation detector, 12 ... Array substrate, 13 ... Scintillator film, 14 ... Reflection film, 15 ... Moisture-proof body, 16 ... Glass substrate, 18 ... Gate line, 19 ... Data line, 20 ... Pixel 21 ... Photodiode, 22 ... Thin film transistor, 26 ... Terminal group, 27 ... Storage capacitor, 28 ... Protective film, 30 ... Circuit substrate, 31 ... Support plate, 32 ... Flexible substrate, 33 ... Integral amplifier, 34 ... A / D Converter: 35 ... Row selection circuit, 36 ... Image composition circuit, 38 ... Parallel / serial converter, 39 ... Gate driver, 40 ... Adhesive layer, 50 ... Gutter part, 51 ... Top plate part, 52 ... Slope part, 53 ... Burr, 71 ... First surface, 72 ... Second surface, 73 ... Metal plate, 80 ... Dampproof body, 83 ... Burr

Claims (2)

An array substrate provided with a photoelectric conversion element layer in which photoelectric conversion elements for converting fluorescence into an electrical signal are arranged;
A scintillator film that is provided on the surface of the array substrate so as to cover the photoelectric conversion element layer and converts radiation into fluorescence;
A moisture-proof body made of a hat-shaped metal foil or a thin plate, and a protrusion protruding in a direction away from the array substrate on the outer edge to surround the scintillator film;
An adhesive layer for bonding the outer periphery of the moisture-proof body and the array substrate;
A radiation detector comprising: A step of providing a scintillator film for converting radiation into fluorescence so as to cover the photoelectric conversion element layer on the surface of an array substrate provided with a photoelectric conversion element layer in which photoelectric conversion elements for converting fluorescence into electrical signals are arranged;
A part of the metal plate having the first surface and the second surface is recessed from the first surface toward the second surface, which is wider than the scintillator film and deeper than the protruding height of the scintillator film from the array substrate. A hollow portion is formed and cut by shearing to displace the outer side of the outer edge of the collar portion provided on the outer periphery of the hollow portion relative to the inner side in the direction from the first surface to the second surface. And forming a moisture barrier,
Bonding the outer periphery of the moisture-proof body and the array substrate with an adhesive so that the first surface faces the array substrate and surrounds the scintillator film with the moisture-proof body;
The manufacturing method of the radiation detector characterized by comprising.

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