JP2010210580A - Radiation detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray detector having high reliability for temperature variation. <P>SOLUTION: A periphery of a protector 15 is stuck and sealed to an array substrate, and a scintillator layer on the array substrate is covered with the protector 15. The protector 15 includes an emboss 38 as a thermal expansion difference absorption section 37 for absorbing the thermal expansion difference from the array substrate. The emboss 38 absorbs the stress generated by difference between the thermal expansion coefficient of the protector 15 and the thermal expansion coefficient of the array substrate and thermal expansion coefficient of an adhesive layer, the stress to the array substrate and adhesive layer is reduced, and the camber of the array substrate and breakage of the adhesive layer are prevented. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radiation detector for detecting radiation.

  A planar X-ray detector using an active matrix has been developed as a new generation X-ray diagnostic detector. By detecting the X-rays irradiated to the X-ray detector, an X-ray image or a real-time X-ray image is output as a digital signal. In this X-ray detector, X-rays are converted into visible light, that is, fluorescence by a scintillator layer, and this fluorescence is signaled by an amorphous silicon (a-Si) photodiode or a photoelectric conversion element such as a CCD (Charge Coupled Device). Images are acquired by converting them into electric charges.

The scintillator layer is generally made of 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, and the resolution characteristics can be improved 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.

  There is a method of forming a reflective layer on the scintillator layer in order to improve the sensitivity characteristics by increasing the utilization efficiency of fluorescence from the scintillator layer. That is, of the fluorescence emitted from the scintillator layer, the fluorescence directed to the opposite side with respect to the photoelectric conversion element side is reflected by the reflection layer, and the fluorescence reaching the photoelectric conversion element side is increased.

Examples of the reflective layer include a method of forming a metal layer having a high fluorescence reflectance such as a silver alloy or aluminum on the scintillator layer, or a light scattering reflective material composed of a light scattering material such as TiO ₂ and a binder resin. A method of coating and forming a reflective layer is known. In addition, a method of reflecting scintillator light by bringing a reflector having a metal surface such as aluminum into close contact with the scintillator layer instead of forming on the scintillator layer has been put into practical use.

  In addition, a moisture-proof structure that protects the scintillator layer, the reflective layer, the reflective plate, etc. from the external atmosphere and suppresses the deterioration of characteristics due to humidity is an important component for making a radiation detector a practical product. . In particular, when a CsI: Tl film or a CsI: Na film, which is a material having a large deterioration with respect to humidity, is used as a scintillator layer, high moisture-proof performance is required.

  As a conventional moisture-proof structure, there is a structure in which a surrounding member surrounding the scintillator layer is bonded to the substrate with an adhesive and a moisture-proof cover is bonded to the surrounding member with an adhesive to seal the scintillator layer (for example, , See Patent Document 1).

JP-A-5-242841 (page 3-5, FIG. 1)

  However, the conventional moisture-proof structure has the following problems.

  In the moisture-proof structure mentioned above, it is generally known that a metal foil or a thin plate is used as the moisture-proof cover. Alternatively, a low moisture-permeable film material having a multilayer structure of a resin and an inorganic thin film may be used as the moisture-proof cover. As the substrate, TFTs or photodiode pixels are formed on a glass substrate. Due to the difference in coefficient of thermal expansion between the metal or multilayer film and glass when these moisture-proof covers and substrates are bonded at the periphery when exposed to high-temperature or low-temperature environments during the manufacturing process. Then, stress is generated in the moisture-proof cover, the substrate, or the adhesive sealing portion, and the substrate is warped. Further, when the temperature change is repeated, including after the production, the adhesive seal portion or the like is easily broken. Incidentally, the thermal expansion coefficient of aluminum or aluminum alloy is about 24 ppm / deg, and the thermal expansion coefficient of a general glass substrate used for TFT applications is about 4 ppm / deg. That is, there is a difference in thermal expansion coefficient of about 20 ppm / deg. The thermal expansion coefficient of the multilayer film varies depending on the resin material constituting the multilayer film and the thermal expansion coefficient of the inorganic thin film, but the thermal expansion coefficient of the resin material is generally larger than that of aluminum or the like. Therefore, even in the case of a moisture-proof cover using a resin such as a multilayer film, it is considered that the difference in thermal expansion coefficient from the substrate has a relatively large value.

  The warpage of the board becomes a factor that causes a defect in the subsequent mounting process, the process of incorporating into the housing, or even after the process of incorporation. Further, the destruction of the adhesive sealing portion means that the moisture-proof structure has stopped functioning, and is directly connected to the characteristic deterioration of the internal CsI: Tl film or the like due to moisture permeation from the destruction portion. A metal such as aluminum has a certain rigidity even if it is thin and thin, for example, about 0.1 mm, and gives stress to the substrate. When an extremely thin foil, for example, 30 μm or less, is used to reduce the stress, the pinhole risk of the foil material increases, and the reliability of the moisture-proof cover is significantly lowered.

  The present invention has been made in view of these points, and an object of the present invention is to provide a radiation detector having high reliability against temperature changes.

  The present invention includes a substrate having a photoelectric conversion element, a scintillator layer that is formed on the photoelectric conversion element and converts radiation into fluorescence, covers the scintillator layer, and partially absorbs a difference in thermal expansion from the substrate. And a protective layer provided with a thermal expansion difference absorbing portion, and an adhesive layer that adheres and seals the substrate and the peripheral portion of the protective body.

  According to the present invention, the protective body that covers the scintillator layer and adheres and seals the peripheral portion to the substrate is provided with the thermal expansion difference absorbing portion that absorbs the thermal expansion difference from the substrate. Under the environment where the temperature changes repeatedly or under temperature, the stress on the substrate and the adhesive layer caused by the difference between the thermal expansion coefficient of the protector, the thermal expansion coefficient of the substrate and the thermal expansion coefficient of the adhesive layer is reduced. Breakage of the adhesive layer can be prevented.

The protection body of the X-ray detector which shows 1st Embodiment of the radiation detector of this invention is shown, (a) is a front view, (b) is a side view. It is sectional drawing of a X-ray detector same as the above. It is a perspective view of a X-ray detector same as the above. It is the graph which tested the curvature amount of the board | substrate with respect to heat-curing temperature using the protector shown in FIG. It is the graph which tested the curvature amount of the board | substrate with respect to heat-curing temperature using the protector shown in FIG. It is a front view of the protector used for the test shown in FIG. The protective body without embossing is shown, (a) is a perspective view before a thermal cycle test, (b) is a perspective view after a thermal cycle test. The protective body with an embossing same as the above is shown, (a) is a perspective view before a thermal cycle test, (b) is a perspective view after a thermal cycle test. It is a front view which shows the example which has arrange | positioned the embossing in the position removed from the diagonal of a protection body same as the above. It is a front view which shows the other example which shows the example which has arrange | positioned the embossing near the center of a protection body same as the above. It is a front view which shows the example which has arrange | positioned the embossing to the whole protector same as the above. It is a front view which shows the other example which has arrange | positioned the embossing to the whole protector same as the above. It is a table | surface which shows the result of having done the thermal cycle test in each example of a protection body same as the above. It is sectional drawing of the X-ray detector which shows 2nd Embodiment of the radiation detector of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 to 13 show a first embodiment.

  As shown in FIGS. 2 and 3, reference numeral 11 denotes an X-ray detector as a radiation detector. The X-ray detector 11 is an X-ray plane sensor that detects an X-ray image that is a radiation image. It is used for medical purposes. Then, the X-ray detector 11 converts the incident X-rays into fluorescence by providing an array substrate 12 that is a photoelectric conversion substrate as a substrate that converts fluorescence into an electrical signal, and a surface that is one main surface of the array substrate 12. A scintillator layer 13 which is an X-ray conversion unit for conversion, a reflection layer 14 provided on the scintillator layer 13 for reflecting the fluorescence from the scintillator layer 13 toward the array substrate 12, the scintillator layer 13 and the reflection layer 14 covering them. A hat-shaped protective body (or a moisture-proof body) 15 is provided as a moisture-proof structure that protects from the outside air and humidity.

  The array substrate 12 converts fluorescence converted from X-rays into visible light by the scintillator layer 13 into an electrical signal. The glass substrate 16 is provided on the glass substrate 16 and functions as an optical sensor. A plurality of photoelectric conversion portions 17 having a shape, a plurality of control lines (or gate lines) 18 arranged along the row direction, a plurality of data lines (or signal lines) 19 arranged along the column direction, A control circuit (not shown) to which the control line 18 is electrically connected and an amplification / conversion unit (not shown) to which each data line 19 is electrically connected are provided.

  In the array substrate 12, pixels 20 having the same structure are formed in a matrix, and photodiodes 21 as photoelectric conversion elements are disposed in the pixels 20, respectively. These photodiodes 21 are disposed below the scintillator layer 13.

  Each pixel 20 includes a thin film transistor (TFT) 22 as a switching element electrically connected to the photodiode 21, and a storage capacitor (not shown) as a charge storage unit for storing the signal charge converted by the photodiode 21. Yes. However, the storage capacitor may also serve as the capacitance of the photodiode 21, and is not necessarily required.

  Each thin film transistor 22 has a switching function for accumulating and discharging charges generated by the incidence of fluorescence on the photodiode 21. A semiconductor material such as amorphous silicon (a-Si) as an amorphous semiconductor that is a crystalline semiconductor material or polysilicon (P-Si) that is a polycrystalline semiconductor is at least partially configured. The thin film transistor 22 includes a gate electrode 23, a source electrode 24, and a drain electrode 25. The drain electrode 25 is electrically connected to the photodiode 21 and the storage capacitor. The storage capacitor is formed in a rectangular flat plate shape and is provided opposite to the lower part of each photodiode 21.

  The control line 18 is disposed between the pixels 20 along the row direction, and is electrically connected to the gate electrode 23 of the thin film transistor 22 of each pixel 20 in the same row.

  The data line (signal line) 19 is disposed between the pixels 20 along the column direction, and is electrically connected to the source electrode 24 of the thin film transistor 22 of each pixel 20 in the same column.

  The control circuit controls the operating state of each thin film transistor 22, that is, on and off, and is mounted on the side edge along the row direction on the surface of the glass substrate 16.

  The amplifying / converting unit includes, for example, a plurality of charge amplifiers arranged corresponding to each data line 19, a parallel / serial converter to which these charge amplifiers are electrically connected, and the parallel / serial converter is electrically connected And an analog-to-digital converter connected to the. An image transfer unit 26 that transfers an image is connected to the parallel / serial converter.

  A protective layer 27 made of resin is formed on the surface of the array substrate 12.

The scintillator layer 13 converts incident X-rays into visible light, that is, fluorescence, and is vacuumed by, for example, cesium iodide (CsI): thallium (Tl) or sodium iodide (NaI): thallium (Tl). A columnar structure formed by vapor deposition or gadolinium oxysulfide (Gd ₂ O ₂ S) phosphor particles mixed with a binder material, coated on the array substrate 12, fired and cured, diced by a dicer, etc. A groove portion is formed to form a quadrangular prism. Between these columns, air or an inert gas such as nitrogen (N 2) for preventing oxidation can be enclosed, or a vacuum state can be provided. In each of the following examples, a CsI: Tl vapor deposition film is used for the scintillator layer 13, the film thickness is about 600 μm, and the columnar structure crystal pillar (pillar) thickness is 8 to 8 on the outermost surface. About 12 μm is used.

  As shown in FIGS. 1 and 2, the protector 15 is formed with a cover portion 31 facing the surface of the scintillator layer 13, and has a depth including the scintillator layer 13 from the periphery of the cover portion 31. A side surface portion 32 is formed, and a flange portion 33 protruding from the front end side of the side surface portion 32 to the periphery is formed. The protector 15 is a substantially quadrangular shape having four corner portions and four side portions, and is formed into a hat shape by pressing a foil or a thin plate of a metal material such as aluminum or aluminum alloy, for example.

  The collar portion 33 is an annular shape protruding from the periphery of the protector 15, is formed in parallel with the surface of the array substrate 12, and is adhesively sealed to the array substrate 12 via an adhesive layer 34 using an adhesive. .

  The protector 15 may or may not be in contact with the reflective layer 14, but usually there is a gap 35 between the protector 15 and the reflective layer 14.

  As shown in FIG. 1, the cover portion 31 of the protector 15 is provided with a thermal expansion difference absorbing portion 37 for absorbing the thermal expansion difference between the protector 15 and the array substrate 12 or the adhesive layer 34. The thermal expansion difference absorbing portion 37 is formed on the outer surface side of the covering portion 31 with the one surface side opposite to the array substrate 12 being the outer surface of the covering portion 31 and the other surface facing the array substrate 12 being the inner surface of the covering portion 31. Or a concave structure on the inner surface side, or a concave structure on the outer surface side of the cover 31 and a convex structure on the inner surface side. Hereinafter, such an undulating structure is referred to as an emboss 38. The emboss 38 is formed, for example, by press working with a press stamping die having an uneven shape.

  The emboss 38 has a predetermined protrusion amount or a predetermined depth with respect to the cover portion 31 of the protector 15, and has an elongated shape having a short side direction and a long side direction, and its cross-sectional shape is, for example, an arc shape. .

  The emboss 38 is formed in the vicinity of the four corners of the protector 15 and in the vicinity of the four sides. In the vicinity of the corner portion of the protector 15, the emboss 38 is disposed along the diagonal of the protector 15, and the emboss 38 is disposed along the direction orthogonal to the diagonal of the protector 15. The emboss 38 is in the center. Crossed at the end, it becomes an embossed engraved mark. In the vicinity of the side portion of the protection body 15, an emboss 38 with a symbol “−” parallel to the side portion of the protection body 15 is arranged. The emboss 38 near the corner of the protector 15 is separated from the emboss 38 near the side.

  Examples of the present invention will be described below.

  In each example, since the array substrate 12 on which the original thin film transistor 22 and the photodiode 21 are arranged is very expensive, a dummy sample using only the glass substrate 16 instead of the array substrate 12 was prototyped and evaluated. Regarding the warp reduction effect as the X-ray detector 11 according to the present invention and the fracture reduction effect of the adhesive layer 34 in the thermal cycle test, which will be described later, the dummy sample using only the glass substrate 16 is sufficiently equivalent to the trial production. Is possible.

As the glass substrate 16, an AN100 glass substrate having a side of 400 mm and a thickness of 0.7 mm was used. As the scintillator layer 13, a CsI: Tl film having a film thickness of 600 μm was formed on a glass substrate 16 on a square area having a side of about 360 mm by vacuum deposition. The reflective layer 14 was formed by applying and drying a coating liquid obtained by mixing a TiO ₂ submicron powder, a binder resin, and a solvent on the scintillator layer 13.

  The protector 15 of this example was formed by pressing an aluminum alloy foil (A1N30-O material) having a thickness of 0.1 mm into a hat-like structure having a flange portion 33 having a width of 5 mm in the peripheral portion, and FIG. The shape and arrangement of the emboss 38 as shown in Fig. 1 were stamped by press molding so that the emboss height was about 0.5 mm.

  As a comparative example, the protector 15 having the same conditions as in the present example was used except that the emboss 38 was not provided.

  For the present example and the comparative example, an adhesive constituting the adhesive layer 34 was applied to the collar portion 33 by a dispenser, and bonded to a glass substrate on which the scintillator layer 13 and the reflective layer 14 were formed. Adhesives are generally epoxy adhesives that are commercially available, and were prototyped for both heat-curing and ultraviolet-curing types.

  FIG. 4 shows an adhesive between the protector 15 of the present embodiment with the emboss 38 having a height (depth) of 0.2 mm and 0.3 mm, and the protector 15 of the comparative example without the emboss. The result of having measured the curvature amount of the glass substrate 16 after this heat-hardening process is shown. The amount of warpage of the glass substrate 16 is shown by an average value of four locations measured by a gap gauge with respect to four corner portions of the glass substrate 16 after being cooled to room temperature after heating.

  As can be seen from FIG. 4, the amount of warpage of the glass substrate 16 is clearly reduced by the protector 15 of the present embodiment with embossing by the protector 15 of the comparative example without embossing, and the effect of reducing the amount of warpage It can be seen that this also depends on the height (depth) of the emboss 38.

  5 shows an example in which the position of the emboss 38 is positioned slightly inside the position of the emboss 38 shown in the protector 15 in FIG. 1 as in the protector 15 shown in FIG. The glass substrate 16 after the heat-curing step of the adhesive, with the protector 15 of the present example with embossing having a thickness (depth) of 0.3 mm and 0.5 mm and the protector 15 of the comparative example without embossing. The result of measuring the amount of warpage of is shown. The measurement method is the same as in FIG.

  As can be seen from FIG. 5, the warpage amount of the glass substrate 16 is clearly reduced by the protective body 15 of the present embodiment with embossing by the protective body 15 of the comparative example without embossing, and the effect of reducing the warpage amount. It can be seen that this also depends on the height (depth) of the emboss 38.

  Here, as a supplement, the cause of warping of the glass substrate 16 even when the protector 15 is heated from room temperature and returned to room temperature will be described. The cause of this phenomenon is that the glass substrate 16 is forcibly warped by an external force other than temperature, or the time for forcing the warp of the glass substrate 16 is compared between long and short. From these results, it is estimated as follows.

  As described above, the thermal expansion coefficient of aluminum or aluminum alloy near room temperature is about 24 ppm / deg, whereas the thermal expansion coefficient of a glass substrate 16 such as AN100 used as the array substrate 12 is about 4 ppm. / Deg, there is a difference in thermal expansion coefficient of about 20 ppm / deg. In the heated state, since the thermal expansion of the protective body 15 is large with respect to the glass substrate 16, the protective body 15 exerts an external stress on the glass substrate 16 through the adhesive layer 34, and as a result, the glass substrate 16 A convex warp is produced in which the surface on the protector 15 side protrudes. When actually observed in a heated state, the glass substrate 16 is warped in accordance with the heating temperature. On the other hand, an elastic force is exerted on the glass substrate 16 to return from the convex warpage state. As a result, in the adhesive layer 34 between the flange portion 33 of the protector 15 and the glass substrate 16, a stress that tends to shift the adhesion position toward the outside of the glass substrate 16 acts. Accordingly, when this stress is maintained for a certain period of time, the adhesion position shifts toward the outside of the glass substrate 16 due to the creep phenomenon of the adhesive of the adhesive layer 34. The bonding position gradually shifts with the holding time in that state. Since the adhesive is a resin-based material, it is considered that a creep phenomenon occurs even if it is cured.

  When the thermal expansion is restored after cooling to room temperature in such a state where the bonding position is shifted, the bonding position is slightly shifted outward from the initial bonding position (before heating). In this state, the protective body 15 generates a stress that pulls the glass substrate 16 inward via the adhesive layer 34. Therefore, the glass substrate 16 itself exhibits a concave warp in which the surface of the glass substrate 16 on the protective body 15 side is recessed. The amount of concave warpage of this glass substrate 16 is about a fraction of the absolute value compared to the amount of convex warpage in the heated state, and the force to return the bonding position to the inside by this concave warpage is It is sufficiently small compared to the stress to be shifted outward. For this reason, the concave warpage of the glass substrate 16 in the state where the temperature is returned to room temperature almost maintains that state. Alternatively, even if asymptotic to the original flat state, a considerable time is required.

  When the glass substrate 16 is cooled to the low temperature side, a phenomenon occurs in a direction substantially opposite to that when the glass substrate 16 is heated to the high temperature side. Also in this case, when the glass substrate 16 is actually cooled to −20 ° C., a large concave warp is generated in the glass substrate 16, and when the temperature is returned to room temperature, a slight convex warp may remain in the glass substrate 16. It turns out.

  Next, as a reliability evaluation of the adhesive sealing by the adhesive layer 34 between the protector 15 and the glass substrate 16, the results of the cold cycle test will be described.

  The conditions of the thermal cycle test were -20 ° C. × 1 h, room temperature × 30 minutes, 50 ° C. × 1 h, and room temperature × 30, and 50 cycles were performed.

  FIG. 7 shows a protective body 15 of a comparative example without embossing, where (a) is a perspective view before a thermal cycle test, and (b) is a perspective view after the thermal cycle test. As can be seen from FIG. 7, noticeable wrinkles are generated particularly at the corners of the protector 15. It is considered that due to the repetition of the concave warp and the convex warp between the protector 15 and the glass substrate 16, the aluminum foil near the corner portion where stress is particularly concentrated cannot be endured and deformed, and wrinkles are generated. These wrinkles tend to easily generate wrinkles in a direction where stress tends to concentrate in a direction and in a direction where the expansion and contraction of the aluminum foil due to temperature change is large. However, the size and position of the ridge, the direction and height (depth) of the irregularities are disordered. Among these, it is presumed that stress is given to the reflective layer 14 and the scintillator layer 13 inside the protector 15 at a particularly large portion of the wrinkles.

  FIG. 8 shows the protector 15 of the present embodiment with embossing, in which (a) is a perspective view before the thermal cycle test, and (b) is a perspective view after the thermal cycle test. As can be seen from FIG. 8, generation of wrinkles is seen on the extended line of the pattern of the emboss 38 (x mark and − mark), but no wrinkles are generated other than that. This is presumably because the embossed portion 38 absorbed the expansion and contraction due to thermal expansion and did not generate extra stress in the other portions. Further, the direction of the wrinkles generated on the extended line of the emboss 38 is generated as the same concave or convex wrinkles as the longitudinal direction of the emboss 38. Since wrinkles occur in the shape of the emboss 38 or its expanded shape, it does not cause disordered wrinkles in the absence of the emboss 38, and local to the reflective layer 14 and scintillator layer 13 inside the protector 15. Damage can be prevented.

  As a result of actual disassembling investigation, in the protective body 15 of the comparative example without embossing, cracks in the reflective layer 14 and cracks in the scintillator layer 13 were observed in a part of the part where wrinkles occurred. On the other hand, in the protector 15 of this example with embossing, which was subjected to the thermal shock test under the same conditions, no cracks were found in the reflective layer 14 and the scintillator layer 13.

  In addition, as a result of observing in detail the adhesive sealing portion of the adhesive layer 34, in the sample manufactured using the protector 15 of the comparative example without embossing, the adhesive sealing portion is divided into seven samples among ten prototype samples. It was found that the destruction of This was investigated by the red check method. It was found that there was a portion where the red check solution dripped from the outside of the adhesive sealing portion soaked into the adhesive sealing portion.

  On the other hand, in the samples that were prototyped using the protector 15 of the present example with embossing, the adhesive seal portion was not particularly broken in all the 10 prototype samples. The reason why the adhesive seal portion was not broken in the protector 15 of the present embodiment with embossing is considered to be a result of the stress applied to the adhesive layer 34 being relaxed by the emboss 38 during the thermal cycle. From this result, it was found that when the protector 15 of this example with embossing was used, the reliability related to the temperature cycle was greatly improved.

  Here, the difference in the effect regarding the formation position of the emboss 38 will be described. In the protector 15 of FIG. 1, the difference in expansion and contraction due to the difference in thermal expansion between the protector 15 and the glass substrate 16 tends to absorb the stress direction near the diagonal corner. An emboss 38 with an X mark was arranged, and in the vicinity of a side where a difference in thermal expansion is likely to affect the adhesive layer 34, an inscription with a-mark was arranged to absorb the difference in thermal expansion. In order to compare with this, a sample of the protector 15 in which the position of the emboss 38 shown in FIGS.

  In the example of the protector 15 shown in FIG. 9, the emboss 38 of the same design and depth is used for the protector 15 of the present embodiment shown in FIG. 1, the distance from each corner is the same, and the position of the emboss 38 Was removed from the diagonal extension. In this example, it is superior to the protective body 15 of the comparative example without embossing, but the warpage amount of the glass substrate 16 after heating described above is large, and the fracture probability of the adhesive layer 34 after the thermal cycle is also high. The result was slightly high.

  In the example of the protector 15 shown in FIG. 10, the emboss 38 having the same design and depth is used with respect to the protector 15 of the present embodiment shown in FIG. In addition, the imprint of the “−” mark was also arranged closer to the center away from the vicinity of the side. In this example, it is superior to the protective body 15 of the comparative example without embossing, but the warpage amount of the glass substrate 16 after heating is large, and the fracture rate of the adhesive layer 34 after the cooling and heating cycle is slightly high. there were.

  In the example of the protector 15 shown in FIG. 11 or FIG. 12, the emboss 38 having the same design and the same height (depth) as the protector 15 of the present embodiment shown in FIG. It was arranged on almost the entire surface. In these cases, similarly to the protector 15 of this embodiment shown in FIG. 1, the warp of the glass substrate 16 that occurs during heating and cooling is reduced, and the amorphous wrinkles and adhesive layer of the protector 15 that are generated by the thermal cycle test. The destruction of 34 is reduced. Furthermore, compared with the example in which the shape of the same emboss 38 is formed only in the vicinity of the corner portion and the side portion, the effect of suppressing warpage is great.

  FIG. 13 shows a table summarizing the above results.

  As an example other than those described so far, the shape and position of the emboss 38 on the protector 15 are not limited to the X mark or the-mark as illustrated in the present embodiment, but may be a ◯ shape (dimple) or other shapes. . Even in the case of other shapes, it is desirable to have a design that does not have an extreme bent portion or thin portion that easily causes cracks.

  Further, although the arrangement of the emboss 38 is arbitrary, it is more effective to arrange the emboss 38 at a position where the expansion and contraction due to the difference in thermal expansion between the protector 15 and the array substrate 12 can be efficiently absorbed. Furthermore, it is desirable to take care to avoid the local arrangement with respect to the entire protector 15 and to make the arrangement as objective as possible.

  In the above description, an example in which an aluminum alloy foil (A1N30H material) having a thickness of 0.1 mm is used as the protector 15 has been described. Depending on the size of the protector 15 and the array substrate 12, the type of aluminum or aluminum alloy material, the difference in the tempering of the H or O material, and the thickness of the material, the warp reduction value of the array substrate 12 described above and the effect on the thermal cycle The degree of is different. However, it was confirmed in several different examples that the relative relationship of the effects was established in comparison with no embossing and comparison between examples.

  Further, the protector 15 is not limited to the hat-like structure, but has a flat-plate structure as shown in FIG. 14, and a ring-shaped frame member 41 is arranged around the protector 15 so that the array substrate 12 Various variations such as a structure in which the frame member 41 and the protector 15 are bonded and sealed with the adhesive layer 34 are possible.

  However, in the case of the hat-shaped protector 15, the height including the reflective layer 14 and the scintillator layer 13 inside can be earned near the bonded portion without increasing the thickness of the moisture-proof material. Therefore, in the case of the hat-shaped protector 15, the ring-shaped frame member 41 is not required and can be directly bonded to the array substrate 12, and an extra member (ring-shaped frame member 41) or process ( The effect is great in that the reliability of the adhesive sealing portion can be improved by reducing the number of two steps of bonding the upper and lower portions of the frame member 41).

  Further, the material of the protector 15 is not limited to aluminum or an aluminum alloy, and the same applies when other metal materials, a laminated film of an inorganic film and a resin material, or the like is used. However, in the case of aluminum or aluminum alloy foil material, since the X-ray absorption coefficient is small as a metal material, there is a great merit in that X-ray absorption loss in the protector 15 can be suppressed. Further, when the protector 15 is processed into a hat shape or when the emboss 38 is stamped, the processability is excellent.

  Further, the embossing method for the foil material or thin plate material of the protector 15 is appropriately selected depending on the material, thickness, shape of the emboss 38, etc., but press working using a stamping die as described in this embodiment. However, it is suitable as a production method with stable quality and small variations.

  As described above, according to the present embodiment, the thermal expansion difference absorbing portion that absorbs the thermal expansion difference from the array substrate 12 to the protector 15 that covers the scintillator layer 13 and adheres and seals the peripheral portion to the array substrate 12. Since the emboss 38 is provided as 37, the thermal expansion coefficient of the protector 15, the thermal expansion coefficient of the array substrate 12, and the thermal expansion coefficient of the adhesive layer 34 in a high temperature environment, a low temperature environment, or an environment where temperature changes are repeated. It is possible to reduce stress on the array substrate 12 and the adhesive layer 34 caused by the difference between them and prevent warping of the array substrate 12 and destruction of the adhesive layer 34. As a result, it is possible to prevent problems that occur in the mounting process and the housing in the subsequent process due to warping of the array substrate 12. Further, even when the temperature change is repeated, the thermal stress on the adhesive layer 34 can be reduced, and the adhesive layer 34 can be hardly broken. With these effects, a highly reliable X-ray detector 11 can be realized.

11 X-ray detectors as radiation detectors
12 Array substrate as substrate
13 Scintillator layer
15 Protective body
21 Photodiodes as photoelectric conversion elements
33 Buttocks
34 Adhesive layer
37 Thermal expansion difference absorption part

Claims (8)

A substrate having a photoelectric conversion element;
A scintillator layer formed on the photoelectric conversion element for converting radiation into fluorescence;
A protective body that covers this scintillator layer and is provided with a thermal expansion difference absorbing part that partially absorbs the thermal expansion difference from the substrate,
A radiation detector, comprising: an adhesive layer that adheres and seals the substrate and a peripheral portion of the protector. The radiation detector according to claim 1, wherein the thermal expansion difference absorbing portion is formed in a undulating structure in which one surface of the protector is convex and the other surface is concave. The radiation detector according to claim 1, wherein the protective body is a quadrangle, and the thermal expansion difference absorbing portion is formed on at least one of a diagonal line and a vicinity of the diagonal line. The radiation detector according to claim 1, wherein the protective body is a quadrangle, and the thermal expansion difference absorbing portion is formed in the vicinity of each corner portion and in the vicinity of each side portion. The radiation detector according to claim 1, wherein the thermal expansion difference absorbing portion is formed on an entire area of the protective body. The radiation detector according to any one of claims 1 to 5, wherein the protector is made of any one of aluminum and an aluminum alloy, and is made of any one of a foil and a thin plate. The protective body has a depth including the scintillator layer, and is formed in a shape having a flange portion that is bonded and sealed to the substrate by the adhesive layer in a peripheral portion. The radiation detector in any one of 6 thru | or 6. The radiation detector according to any one of claims 1 to 7, wherein the thermal expansion difference absorbing portion of the protector is formed by press working.

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