JP2012052965A - Radiation detector and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation detector which minimizes a substrate size and lengthwise and crosswise dimensions of a body with respect to a practical-use pixel area while ensuring excellent moistureproof performance.SOLUTION: A radiation detector comprises; an array substrate 12 which includes a pixel area where a plurality of photoelectric conversion elements are provided and an internal wiring layer 6 drawn from the pixel area; a scintillator layer 13 provided on the pixel area of the array substrate 12; a connecting part 5 connected with the internal wiring layer 6 around the array substrate 12 and also with an external wiring 9; a moistureproof layer 15 formed in a hat shape having a flange part 15a to cover the scintillator layer 13; and an adhesive layer 16 for bonding the flange part 15a and the array substrate 12. The adhesive layer 16 bonds at least a part of the flange part 15a and the array substrate 12 at the upper part of the connecting part 5.

Description

  The present invention relates to a radiation detector for detecting radiation and a method for manufacturing the same.

  A planar radiation detector using an active matrix has been developed as a new generation X-ray diagnostic detector. By detecting the X-rays applied to the radiation detector, an X-ray image or a real-time X-ray image is output as a digital signal.

  In general, a radiation detector uses a scintillator layer that converts X-rays into visible light, that is, fluorescence, and converts this fluorescence into signal charges using a photoelectric conversion element such as an amorphous silicon (a-Si) photodiode or a CCD (Charge Coupled Device). A photoelectric conversion unit for conversion and a moisture-proof structure that protects the scintillator layer and the like from the external atmosphere and suppresses deterioration of characteristics due to humidity or the like are provided.

  As the moisture-proof structure, there is a method using a CVD film of polyparaxylylene (hereinafter referred to as “parylene”) (for example, see Patent Document 1).

  However, in the case of a method using a parylene CVD film, the moisture permeability barrier property is often insufficient at least in a practical film thickness range (for example, 20 μm).

  On the other hand, there is a method of keeping moisture-proof performance by bonding and sealing a hat-shaped moisture-proof layer such as an AL foil with a substrate at the periphery (see, for example, Patent Document 2).

  In this method, a moisture-proof layer made of an AL alloy or the like is formed so as to cover the scintillator, and a collar portion is provided around the periphery, and the collar portion is bonded and sealed to the substrate. According to this method, a structure that covers most of the scintillator with a moisture-proof layer that can substantially ignore moisture permeation by selecting a moisture-proof layer material such as an aluminum alloy foil or an organic / inorganic laminated film and a hat-like shape. It becomes possible. In addition, by using the ridge portion of the hat-shaped moisture-proof layer as an adhesive portion, the adhesive layer and the substrate are thinly bonded (the moisture permeable cross-sectional area can be reduced), and the width of the adhesive layer is reduced. It is possible to secure a wide area up to the width of the portion. Moreover, since the hat-shaped moisture-proof layer itself does not need to be thicker than necessary, loss due to absorption of X-rays and radiation can be suppressed to a very small level. For example, an aluminum alloy or an inorganic / organic laminated moisture barrier layer has sufficient moisture resistance if it has a thickness that does not cause pinholes (approximately 30 μm or more). Therefore, it is possible to realize a radiation detector with a high detection capability that minimizes the moisture permeability from the adhesive layer and has a small X-ray loss.

  The moisture permeability of the entire moisture-proof structure can be expressed by the following equation (1).

Q (Total) = Q (Moisture-proof layer) + Q (Adhesive layer) (1)
Further, Q (adhesive layer) can be further expressed by the following formula (2).

Q (adhesive layer) = P (adhesive layer) · S (adhesive layer) / W (adhesive layer)
= P (adhesive layer), L (adhesive layer), T (adhesive layer) / W (adhesive layer)
... (2)
(Q: moisture permeability, P: moisture permeability coefficient, S: moisture permeability cross section, W: width, L: circumference, T: adhesive layer thickness)
As a technique for reducing the moisture permeability coefficient P of the adhesive layer material, an effective method is to add an inorganic filler material such as Al ₂ O ₃ or talc to the adhesive used for the adhesive layer. The filler restricts the moisture-permeable path in the adhesive layer, reduces the effective moisture-permeable cross-sectional area, and extends the moisture-permeable distance.

  Further, as can be seen from the equation (2), in order to suppress the moisture permeability from the adhesive layer, it is desirable to increase the value of the width W (adhesive layer) of the adhesive layer. Specifically, for example, it is necessary to provide a space between the scintillator layer area (practical active area) in the substrate, the wiring to the peripheral circuit, and the connection portion so that an adhesive layer width W (adhesive layer) of about 5 mm can be secured. There is. In practical use, it is necessary to secure an adhesive layer area that takes into account the positional deviation margin between the flange portion of the moisture-proof layer and the substrate and the protrusion of the adhesive material. About 3 mm (2 to 4 mm) needs to have a minimum margin. Further, the adhesive layer region is necessary on both the control line side and the signal line side, and there are many cases where the wiring and the connection portion thereof are provided on both sides of the substrate depending on the design. In that case, it is necessary to provide areas to be secured for the adhesive layer on both sides of the substrate.

  When these points are combined, for example, an area of about 11 mm on the top, bottom, left and right of the substrate is required for the adhesive layer and its margin. For this reason, the size of the substrate is increased correspondingly with respect to the practical pixel region, and it is necessary to ensure the vertical and horizontal dimensions of the housing by the size corresponding to the region of the adhesive layer.

  FIG. 13 shows a specific dimension example of a radiation detector provided with a hat-shaped moisture-proof layer such as an AL foil.

  In this radiation detector 50, a scintillator layer 13 and a reflective film 14 are sequentially laminated on the surface of an array substrate 12 on which internal wiring layers 6 such as signal lines and control lines are formed, and are formed so as to cover them. The AL hat moisture-proof layer 15 is bonded to the array substrate 12 by the adhesive layer 16 at the flange portion 15a. A TAB pad 7 is formed at the tip of the internal wiring layer 6 provided on the surface of the array substrate 12 and is connected to the FPC wiring layer 9 through an anisotropic conductive film (ACF) layer 8. Yes.

  Here, in this radiation detector 50, the pixel area (active area) from which the X-ray image of the array substrate 12 can be acquired is about 440 mm in both the X direction and the Y direction, and the CsI vapor deposition area in which the scintillator layer 13 is formed. In addition, it is set to 446 mm □ in consideration of a positional deviation margin and wraparound at the time of vapor deposition.

  In addition, as an area of the adhesive layer 16 for bonding the AL hat collar 15a to the outside of the area where the scintillator layer 13 is deposited, the width of the collar 5 mm, and in addition to this, manufacture of the collar and the array substrate In consideration of the time misalignment margin and the adhesive protrusion protrusion margin, a margin of 2 mm on the inside and 4 mm on the outside is secured.

  These margins are a margin of positional deviation at the time of manufacturing the AL hat flange 15a and the array substrate 12, and a margin for protrusion of the adhesive. There are two reasons why the inner margin is smaller. The first point is that the protrusion of the adhesive on the outer side of the AL hat collar 15a is never allowed in the area of the TAB pad 7, but it can be allowed to ooze out slightly on the inner scintillator layer 13 side, The second point is that the AL hat itself of the moisture-proof layer 15 is acceptable even if it is slightly applied to the scintillator layer 13 (for example, the base of the CsI: Tl deposited film).

  Considering these necessary dimensions, the outer dimension of the moisture-proof area up to the inner edge of the TAB pad 7 is 468 mm □, and the 2 mm TAB pad 7 is arranged from the outer area in contact with the area.

  In this radiation detector 50, the outer side of the TAB pad 7 region is cut so that the end face of the array substrate 12 comes about 3 mm apart. As a result, the panel size is 478 mm □.

  The radiation detector 50 having such a structure is manufactured by the procedure shown in FIG.

  First, as shown in FIG. 14 (a), as a moisture-proof layer 15, an AL hat having a flange portion 15a of 5 mm around is used, and the AL hat is set upside down with a dedicated tray 31 and a 32 placed thereon. To do.

  Next, after cleaning the collar portion 15a with acetone, the thermosetting adhesive sealing material 33 is wound around the collar portion 15a by an amount of about 1 mg / mm as shown in FIG. Apply over. Here, the adhesive seal material 33 can be a high viscosity type having a viscosity of about 300 Pa · sec.

  The array substrate 12 on which the moisture-proof layer 15 is formed is prepared as follows.

  First, a CsI: Tl film is deposited as a scintillator layer 13 to a thickness of about 600 μm on an array substrate 12 having a predetermined internal wiring layer 6 and TAB pad 7 formed on the surface. At this time, the opening size of the vapor deposition mask is set to about 444 mm □ so that the pixel area (active area) is completely covered even if a positional deviation between the mask jig and the array substrate 12 during vapor deposition is expected. Actually, there is a wraparound of about 1 mm in the vertical, horizontal and horizontal directions with respect to the vapor deposition mask dimension, so that the design is designed to allow for a CsI: Tl film deposition area of about 446 mm □ as described above.

Next, a reflective film 14 of a type in which fine particles of TiO ₂ are mixed with a resin binder is formed on the scintillator layer 13 with a film thickness of about 100 μm. The characteristics of the reflective film 14 (fluorescence reflectance, the spread of fluorescence inside the reflective film, etc.) can be selected according to applications such as priority on luminance and resolution. Depending on the application, the reflective film 14 may be omitted, or a fluorescent absorption film may be formed instead of the reflective film 14 to obtain characteristics with good resolution even at the expense of luminance.

  Next, as shown in FIG. 14C, the array substrate 12 on which the scintillator layer 13 is formed (the reflective film 14 is not shown) is turned upside down using a jig 35 in the decompression chamber 34. Set facing the moisture-proof layer 15.

Further, as shown in FIG. 14 (d), the pressure plate 37 is used for adhesion by applying pressure by an air cylinder (not shown) and the pressure applied to the collar portion to be adhered is approximately 2 kgf / cm ² for adhesion. .

  Then, it heats for about 3 hours in a 60 degreeC heating oven in the state which applied a certain amount of weight.

  In this way, the collar portion 15a of the AL hat is accommodated in a state where it is adhered to the adhesive layer 16 area of the array substrate 12, as shown in FIG.

  After the above moisture-proof structure is formed, the connecting electrode portion of the FPC wiring layer 9 is thermocompression bonded to the TAB pad 7 through the anisotropic conductive film (ACF) layer 8 in the mounting process, and further incorporated into the housing and connected to the circuit board. And is in a state of operating.

US Pat. No. 6,262,422 JP 2009-128023 A

  However, in the radiation detector 50 having the above-described structure, for example, about 11 mm on the top, bottom, left, and right of the array substrate 12 are required for the adhesive layer 16 and an area for the margin. For this reason, the size of the substrate is increased correspondingly with respect to the practical pixel area, and the dimensions of the housing must be ensured to be large by the size corresponding to the area of the adhesive layer 16.

  The present invention has been made in view of these points, and while ensuring excellent moisture-proof performance, a radiation detector in which the substrate size and the vertical and horizontal dimensions of the housing are minimized with respect to the practical pixel region, and its manufacture It aims to provide a method.

  In order to achieve the above-mentioned object, a radiation detector of the present invention comprises a substrate comprising a pixel area provided with a plurality of photoelectric conversion elements for converting fluorescence into an electrical signal, and an internal wiring layer drawn from the pixel area; A scintillator layer provided on the pixel area of the substrate for converting incident radiation into fluorescence, a connection portion connected to the internal wiring layer and connected to an external wiring around the substrate, and covering the scintillator layer In the radiation detector comprising: a moisture-proof layer that is formed in a hat shape having a flange portion to protect the scintillator layer from external moisture; and an adhesive layer that bonds the flange portion of the moisture-proof layer and the substrate. Is characterized in that at least a part of the flange is bonded to the substrate above the connecting portion.

  In order to achieve the above-mentioned object, the method for manufacturing a radiation detector according to the present invention includes a step of forming a moisture-proof layer in a hat shape having a collar portion, and a step of applying an adhesive to at least a part of the collar portion. And a substrate comprising a pixel area provided with a plurality of photoelectric conversion elements and an internal wiring layer drawn from the pixel area, and a scintillator layer is provided on the pixel area of the substrate, and around the substrate. A step of connecting an external wiring at a connection portion connected to the internal wiring layer, and a step of bonding at least a part of the flange portion and the substrate above the connection portion via the adhesive in a reduced pressure atmosphere And.

  According to the present invention, the radiation detector has excellent moisture proof performance, and has both moisture proof reliability and lightweight compactness by minimizing the vertical and horizontal dimensions of the housing by minimizing the size of the substrate with respect to the effective pixel area. Can be provided.

The perspective view which shows one Embodiment of the radiation detector which concerns on this invention. Sectional drawing of the radiation detector. The schematic cross section of the radiation detector. It is sectional drawing which shows the manufacturing method of the radiation detector, (a) is the state which prepared the moisture-proof layer formed in the hat shape upside down, (b) is the state which apply | coated the sealing material to the collar part of the moisture-proof layer, ( c) A state in which an array substrate having a predetermined layer formed in a decompression chamber and a moisture-proof layer are set, and (d) a state in which the array substrate and the moisture-proof layer are pressurized by an air cylinder. The schematic cross section which shows other embodiment of the radiation detector which concerns on this invention. The graph which shows the change of moisture-proof performance at the time of performing a 60 degreeC-90% RH heating humidification test in Example 1. FIG. The graph which shows the change of moisture-proof performance at the time of changing the addition rate of a filler material (talc) in Example 2, and performing the heating humidification test of 60 degreeC-90% RH * 500h. The bar graph which compared the moisture-proof performance after the heating and humidification test of 60 degreeC-90% RH * 500h by the presence or absence of a spacer material in Example 3. FIG. The graph which shows the change of the moisture permeability coefficient at the time of changing the volume filling rate of a filler material (talc) in Example 4. FIG. The graph which shows the change of moisture proof performance at the time of changing T / W of an adhesive layer in Example 5. FIG. The bar graph which compared the moisture-proof performance at the time of changing the material of a reflective layer in Example 6. FIG. The oscilloscope image which investigated the influence which the difference in a manufacturing method has in Example 7 on microphonic, and the dark image of the detector whole surface, (a) is the case of bonding at atmospheric pressure, (b) is under reduced pressure For pasting. The schematic cross section of the conventional radiation detector. It is sectional drawing which shows the manufacturing method of the conventional radiation detector, (a) is the state which prepared the moisture-proof layer formed in the hat shape upside down, (b) is the state which apply | coated the sealing material to the collar part of the moisture-proof layer, (C) is a state in which an array substrate having a predetermined layer formed in a decompression chamber and a moisture-proof layer are set, and (d) is a state in which the array substrate and the moisture-proof layer are pressurized by an air cylinder.

  Hereinafter, a radiation detector according to an embodiment of the present invention will be described with reference to the drawings.

(Overall structure of radiation detector)
FIG. 1 is a perspective view of a radiation detector according to the present embodiment, and FIG. 2 is a sectional view of the radiation detector.

  The radiation detector 10 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.

  As shown in FIGS. 1 and 2, the radiation detector 10 is provided on an array substrate 12 as a photoelectric conversion substrate that converts fluorescence into an electrical signal, and is incident on a surface that is one main surface of the array substrate 12. A scintillator layer 13 which is an X-ray conversion unit for converting X-rays into fluorescence, a reflection film 14 provided on the scintillator layer 13 and reflecting the fluorescence from the scintillator layer 13 toward the array substrate 12, the scintillator layer 13 and the reflection film 14 There are provided a moisture-proof layer 15 provided on the top and protecting from the outside air and humidity, and an adhesive layer 16 that bonds the moisture-proof layer 15 and the array substrate 12 together.

(Array substrate 12)
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 10, pixels 17 formed in a matrix on the glass substrate 10, and in the row direction A plurality of control lines (or gate lines) 18 arranged along, a plurality of signal lines (or signal lines) 19 arranged along the column direction, and each control line 18 are electrically connected (not shown) A control circuit and an amplification / conversion unit (not shown) to which each signal line 19 is electrically connected are provided.

  In each pixel 17, a photodiode 21 is disposed as a photoelectric conversion element. These photodiodes 21 are disposed below the scintillator layer 13.

  Further, each pixel 17 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 that stores the signal charge converted by the photodiode 21. is doing. However, the storage capacitor may also serve as the capacitance of the photodiode 21 and is not always necessary.

  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 or polysilicon (P-Si) as a polycrystalline semiconductor.

  The thin film transistor 22 includes a gate electrode 23, a source electrode 24, and a drain electrode 25, as shown in FIG. The drain electrode 25 is electrically connected to the photoelectric conversion element (photodiode) 21 and the storage capacitor.

  The storage capacitor is formed in a rectangular flat plate shape, and is provided facing the lower part of each photodiode 21.

  The control line 18 shown in FIG. 1 is disposed between the pixels 17 along the row direction, and is electrically connected to the gate electrode 23 of the thin film transistor 22 of each pixel in the same row as shown in FIG. .

  A signal line (signal line) 19 shown in FIG. 1 is arranged along the column direction between the pixels 17 and is electrically connected to the source electrode 24 of the thin film transistor 22 of each pixel in the same column as shown in FIG. It is connected.

  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 10.

  The amplification / conversion unit includes, for example, a plurality of charge amplifiers arranged corresponding to each signal 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.

  As shown in FIG. 2, a protective film 26 is formed on the uppermost portion of the array substrate 12 to protect the photoelectric conversion element (photodiode) 21, the thin film transistor 22, and the like. This protective film 26 is generally formed of an inorganic film and an organic film.

(Scintillator layer 13)
The scintillator layer 13 converts incident X-rays into visible light, that is, fluorescence. For example, cesium iodide (CsI): thallium (Tl) or sodium iodide (NaI): thallium (Tl) or the like is used as a vacuum deposition method. The groove portion is formed by, for example, forming a columnar structure or gadolinium oxysulfide (Gd ₂ O ₂ S) phosphor particles with a binder material, applying the mixture on the array substrate 12, firing and curing, and dicing with a dicer. Some of them are formed into a square shape.

Between these columns, it is possible to enclose air or an inert gas such as nitrogen (N ₂ ) for preventing oxidation, or to make a vacuum state.

  For example, a vapor deposition film of CsI: Tl is used for the scintillator layer 13, the film thickness is about 600 μm, and the columnar structure crystal pillar (pillar) thickness of CsI: Tl is about 8 to 12 μm at the outermost surface. it can.

(Reflection film 14)
The reflective film 14 formed on the scintillator layer 13 reflects the fluorescence emitted on the side opposite to the photodiode, and increases the amount of fluorescence that reaches the photodiode.

As the reflection film 14, a metal having a high fluorescence reflectance such as silver alloy or aluminum is formed on the scintillator layer 13, a reflection plate having a metal surface such as aluminum is adhered to the scintillator layer 13, TiO ₂ or the like. And a reflective layer having a diffuse reflection property made of a light scattering material and a binder resin.

  The reflective film 14 is not necessarily required due to characteristics such as resolution and luminance required for the radiation detector 11.

(Dampproof layer 15)
The moisture-proof layer 15 is for protecting the scintillator layer 13 and the reflective film 14 from the external atmosphere and suppressing characteristic deterioration due to humidity or the like.

  The moisture-proof layer 15 is formed in a hat shape, for example, by press-molding an AL alloy foil (A1N30-O material) having a thickness of 0.1 mm to a structure having a flange portion 15a having a width of 5 mm in the peripheral portion.

(Adhesive layer 16)
The adhesive layer 16 is formed by applying an adhesive containing an additive to the collar portion 15a. As will be described later, it is preferable to use an epoxy-based and cationic polymerization type ultraviolet (UV) curing adhesive as the adhesive.

  As an additive, in order to suppress moisture permeability of the adhesive layer, it is preferable to use an inorganic filler as described later.

(Detailed dimensions of radiation detector)
FIG. 3 shows an example of specific dimensions of details of the radiation detector according to the present embodiment.

  In this radiation detector 10, the internal wiring layer 6 such as the pixel 17, the control line 18, and the signal line 19 in FIG. 1 is formed on the surface of the array substrate 12, and further, a scintillator layer 13 and a reflective film 14 are sequentially formed thereon. A moisture-proof layer 15 of an AL hat that is laminated and formed so as to cover these is bonded to the array substrate 12 by an adhesive layer 16 at the flange portion 15a. Further, a TAB pad 7 is formed at the tip of the internal wiring layer 6 provided on the surface of the array substrate 12 and constitutes a connecting portion 5 together with an anisotropic conductive film (ACF) layer 8 to form an FPC wiring layer. 9 is connected.

  In the present embodiment, the adhesive layer 16 is bonded to the entire surface of the flange portion 15 a above the connection portion 5.

  Here, in the present radiation detector 10, similarly to the conventional radiation detector 50, pixel areas (active areas) from which an X-ray image of the array substrate 12 can be acquired are about 440 mm in both the X direction and the Y direction. The CsI vapor deposition area for forming the scintillator layer 13 is also 446 mm □ in consideration of a positional deviation margin and wraparound during vapor deposition.

  Further, in this radiation detector 10, the margin of about 1 mm is observed on both sides in the X-axis direction and the Y-axis direction with respect to the vapor deposition area of the scintillator layer 13, and the TAB pad 7 is removed from the outer region in contact with the 448 mm □ area. Arranged. The TAB pad 7 is an electrode portion disposed on the peripheral portion of the array substrate 12 in order to connect the flexible printed circuit (FPC) wiring layer 9 and the array substrate 12 for passing electrical signals.

  Considering these necessary dimensions, the outer dimension of the moisture-proof area up to the inner end of the TAB pad 7 is 448 mm □, and a 2 mm TAB pad portion is arranged from the outer area in contact with the area.

  In the present radiation detector 10, similarly to the conventional radiation detector 50, the outside of the TAB pad 7 region is cut between about 3 mm so that the end face of the substrate comes. As a result, the size of the panel substrate of the present embodiment is 458 mm □, and the vertical and horizontal panel dimensions are reduced by 20 mm, respectively, compared to the conventional radiation detector 50 having a panel size of 478 mm □.

(Average thickness T and average width W in the adhesive layer 16)
As is clear from the above equation (2), the value of T / W, which is the ratio of the thickness and width of the adhesive layer 16, directly affects the moisture permeability. As is clear from the results of Examples described later, when the size of medical and practical X-ray detector (about 9 inches to 17 inches □) satisfies the relationship of T << W, T / W is particularly high. In the case of 0.1 or less, the moisture permeation effect from the adhesive layer 16 can be sufficiently suppressed.

  With a practical X-ray detector size, moisture permeability from the moisture-proof layer is negligible, and moisture permeability from the adhesive layer is dominant. That is, when T / W is the same, the amount of moisture permeation from the adhesive layer 16 increases in proportion to the size of the detector side, whereas the area of the scintillator layer 13 is approximately the square of the side size. This is because the humidity load per unit area of the scintillator layer 13 becomes smaller as the area becomes larger because it increases in proportion.

  Further, in the present radiation detector 10, when a certain amount of the adhesive seal material is applied, the adhesive seal material is less crushed in the portion where the FPC wiring layer 9 and the ACF layer 8 are not present, and as a result, the value of T / W is large. As a result, the moisture permeability is increased.

  For example, in the region where the FPC wiring layer 9 and the ACF layer 8 are provided with the same coating amount (1 mg / mm in the present embodiment), the collapse width of the adhesive layer is 5 mm, and in the region where the FPC wiring layer 9 and the ACF layer 8 are not present. A simple comparison is made assuming that the crushing width is 3 mm.

Since the coating amount per unit length of the adhesive is the same, the thickness of the adhesive layer in the portion where the FPC wiring layer 9 and the ACF layer 8 are not present is approximately 5/3 times the thickness of the adhesive layer in the portion where they are present. ing. The portion without the FPC wiring layer 9 and the ACF layer 8 has a moisture permeable cross-sectional area per unit length that is 5/3 times larger than the portion with the FPC wiring layer 9 and the ACF layer 8, and the moisture permeable length. Will be as short as 3/5. Accordingly, in combination, the moisture permeability increases by (5/3) ² ≈2.8 times.

  In order to avoid this, it is conceivable to add a filler material to the adhesive layer 16. If the moisture permeability coefficient of the material itself of the adhesive layer 16 is suppressed by adding a filler material, the deterioration of the moisture permeability due to the dimension of the adhesive layer 16 can be suppressed, so that the contribution to the entire moisture-proof structure is large, and the radiation detection of the conventional example The effect is more important than the vessel.

  In addition, a method in which a large amount of adhesive is applied to the portion where the FPC wiring layer 9 and the ACF layer 8 are not provided to increase the value of W, or a spacer material corresponding to the thickness of the FPC wiring layer 9 and the ACF layer 8 is applied to this portion. A method of increasing the crushing of the adhesive seal material by sandwiching it and effectively suppressing the value of T / W, or the AL hat of the moisture-proof layer is additionally partially pressurized only in the portions where the FPC wiring layer 9 and the ACF layer 8 are not present. Possible methods.

As the spacer material, it is necessary to select an inorganic material such as TiO ₂ or SiO ₂ or a material having a low moisture permeability coefficient such as a filler-added resin film. Further, a process is required in which the spacer portion is bonded to the array substrate 12 side in advance and bonded to the AL hat moisture-proof layer 15 so that both surfaces of the spacer material are bonded.

(Influence of the reflective film 14)
In the radiation detector 10 of the present embodiment, after the CsI: Tl film is deposited as the scintillator layer 13 until the moisture-proof structure is formed, the FPC wiring layer 9 is attached to the TAB pad 7 of the array substrate 12 via the ACF layer 8. The mounting process for thermocompression bonding enters first. For this reason, as compared with the radiation detector 50 of the conventional example, the time during which the CsI: Tl film as the scintillator layer 13 is exposed to the process environment becomes long, and a certain degree of humidity deterioration is likely to occur before the moisture-proof structure.

As a countermeasure, a step of forming the reflective film 14 after the CsI: Tl film deposition is performed, and a material containing a high content of fine particles of an inorganic material such as TiO ₂ is coated as the reflective film 14 in a short time. It is possible to ensure a moisture-proof performance to a degree that suppresses the humidity degradation during the period. As a phenomenon, fine particles such as submicron diameter TiO ₂ enter between pillars, and these fillers suppress resolution deterioration due to fusion reaction between CsI: Tl film pillars. In addition, since the moisture permeability coefficient of the reflective film 14 itself can be suppressed by the addition of the filler, moisture itself reaching the CsI: Tl film can also be suppressed.

  Furthermore, in the case of the reflective film 14 having a high filler addition rate and a gap between the fillers, the diffusion of fluorescence between pillars can be suppressed, so that the initial resolution itself is high and higher performance can be secured.

(Production method of radiation detector)
The radiation detector 10 having the above structure is manufactured by a procedure as shown in FIG.

  First, as shown in FIG. 4 (a), as the moisture-proof layer 15, an AL hat having a flange portion 15a of 5 mm around is used, and the AL hat is set upside down with the dedicated tray 31 and the 32 placed thereon. To do.

  The material of the moisture-proof layer 15 is not limited to AL or AL alloy, but is composed of a light element oxide film such as Si or Al, an inorganic film such as a nitride film or an oxynitride film, or a light metal thin film such as aluminum or aluminum alloy and a resin material. Even if a film material or the like having excellent moisture-proof performance made of a laminated film is processed, it can be used in the same manner.

  Next, after cleaning the collar part 15a with acetone, the thermosetting adhesive sealing material 33 is wound around the collar part 15a by an amount of about 1 mg / mm as shown in FIG. Apply over. Here, the adhesive sealing material 33 is a high viscosity type having a viscosity of about 300 Pa · sec.

  The array substrate 12 on which the moisture-proof layer 15 is formed is prepared as follows.

  First, a CsI: Tl film is deposited as a scintillator layer 13 to a thickness of about 600 μm on an array substrate 12 having a predetermined internal wiring layer 6 and TAB pad 7 formed on the surface. At this time, the opening size of the vapor deposition mask is set to about 444 mm □ so that the pixel area (active area) is completely covered even if a positional deviation between the mask jig and the array substrate 12 during vapor deposition is expected. Actually, there are wraparounds of about 1 mm in the vertical and horizontal directions with respect to the dimensions of the vapor deposition mask, so as described above, the design is designed to allow for a CsI: Tl film vapor deposition area of about 446 mm □.

Next, a reflective film 14 of a type in which fine particles of TiO ₂ are mixed with a resin binder is formed on the scintillator layer 13 with a film thickness of about 100 μm. The characteristics of the reflective film 14 (fluorescence reflectance, the spread of fluorescence inside the reflective film, etc.) can be selected according to applications such as priority on luminance and resolution. Depending on the application, the reflective film 14 may be omitted, or a fluorescent absorption film may be formed instead of the reflective film 14 to obtain characteristics with good resolution even at the expense of luminance. Furthermore, as described above, a certain amount of moisture-proof performance can be provided by adding a filler material.

  Thereafter, before forming the moisture-proof structure, the connection electrode portion of the FPC wiring layer 9 is thermocompression bonded to the TAB pad 7 of the array substrate 12 after the formation of the reflective film 14 via the ACF (anisotropic conductive film) layer 8. Is done. Electrical connection is established by thermocompression bonding of the FPC wiring layer 9 and the TAB pad 7 of the panel substrate with the ACF layer 8 interposed therebetween. The thickness including the FPC wiring layer 9 and the ACF layer 8 after thermocompression bonding is about 60 to 100 μm.

  After this mounting process, as shown in FIG. 4C, the array substrate 12 (the reflective film 14 is not shown) on which the scintillator layer 13 is formed is turned upside down using a jig 35 in the decompression chamber 34. In the state, set facing the moisture-proof layer 15.

Further, as shown in FIG. 4 (d), the pressure plate 37 is used for adhesion by applying pressure by an air cylinder (not shown) and the pressure applied to the collar portion to be adhered is approximately 2 kgf / cm ² for adhesion. .

  Then, it heats for about 3 hours in a 60 degreeC heating oven in the state which applied a certain amount of weight.

  In this way, the moisture-proof layer 15 coated with the adhesive in the decompression chamber 34 and the array substrate 12 are combined in a state where the pressure is reduced to, for example, about 0.1 atm, and the adhesion portion is pressurized and further bonded. can do. In this case, since the inside of the moisture-proof structure is sealed in a reduced pressure state, the moisture-proof layer 15 such as an AL hat is completed in close contact with the lower reflective film 14 / scintillator layer 13.

  The adhesive sealing material 33 has different crushing levels depending on whether the FPC wiring layer 9 and the ACF layer 8 are present or not. In the portion where the FPC wiring layer 9 and the ACF layer 8 are present, the spread of the adhesive seal material due to the crushing is large, and the adhesive seal material spreads over the entire collar of the 5 mm AL hat.

  On the other hand, since the portion where the FPC wiring layer 9 and the ACF layer 8 are not crushed is small due to the difference in level between the portion and the portion where the FPC wiring layer 9 is present, the width of the adhesive sealing material 33 is small, about 3 mm.

  In this way, the collar portion 15a of the AL hat is accommodated in a state of being adhered to the adhesive layer 16 area of the array substrate 12, as shown in FIG.

  After the above moisture-proof structure was formed, it was assembled in a housing and connected to a circuit board to operate.

  When the X-ray image is taken in a vibration state after being mounted in a housing, the detector created in a reduced pressure state is microphonic (when a certain impact is applied to the product, as is apparent from the results of Examples described later). Image disturbance caused by fluctuations in capacitance between each pixel or wiring of the substrate and the moisture-proof layer, which is called “dark image fluctuation”.

  Further, the difference in the panel dimensions is directly reflected in the housing design, and the housing of the radiation detector 50 of the conventional example has a size of about 520 mm □, whereas in the radiation detector 10 of the present embodiment, The vertical and horizontal dimensions of the case are about 500mm □.

  Therefore, the radiation detector 10 of the present embodiment can be made approximately 20 mm in length and width in comparison with the conventional radiation detector 50.

(Effect of the radiation detector 10)
The radiation detector 10 of the present embodiment described above is a large size as an X-ray detector for medical use, but even when the imaging area is small, the radiation detector 10 is approximately compared with the panel dimensions and housing dimensions of the conventional example. It can be reduced by about 20 mm. Further, since the area of the housing is reduced by about 10%, the weight of the whole radiation detector can be reduced to about 18 kg as compared with the conventional about 20 kg. Furthermore, in the product having a small vertical and horizontal dimension of the effective area, the improvement rate is further increased in the dimension ratio and the weight ratio.

  Moreover, in the radiation detector 10 of this Embodiment, it is possible to suppress one item of Formula (1) which shows the moisture permeability from the moisture-proof layer which occupies most of a moisture-proof structure in area to substantially zero level. The two items can be suppressed to an extremely low value. That is, in the expression (2) in which the two items of the expression (1) are written down, as described above, the wrinkle portion can be effectively used to increase the value of W, and the flat ridge portion of the moisture-proof layer 15 Since the adhesive layer 16 is formed between 15a and the array substrate 12, the thickness T of the adhesive layer 16 can be kept small. Therefore, the value of T (adhesive layer) / W (adhesive layer) can be suppressed to an extremely low value.

(Other embodiments)
FIG. 5 shows an example of specific dimensions of details of a radiation detector according to another embodiment.

  In this radiation detector 30, the arrangement of the TAB pad 7 and the ACF layer 8 on the array substrate 12 is set outward from the arrangement of the radiation detector 10, and only a part of the flange portion 15 a of the moisture-proof layer 15 is covered with the adhesive layer 16. Except for being fixed, it is formed in the same manner as the radiation detector 10.

  Also in the radiation detector 30 of this embodiment, the same effect as the radiation detector 10 can be produced.

  Note that the materials and dimensions of the scintillator layer 13, the reflective film 14, the moisture-proof layer 15, and the adhesive layer 16 described in the above embodiment are merely examples, and are not limited to these materials and dimensions. Even when there is no reflective film 14 or when a fluorescent absorption layer or a buffer layer is inserted in place of the reflective film 14, the effect of reducing the external dimensions and weight compared to the conventional radiation detector is not. It is clear that the same can be obtained.

[Example 1]
(Comparison of moisture resistance)
The moisture-proof performance of the radiation detector 10 according to the embodiment of the present invention shown in FIG. 3 and the conventional radiation detector 50 shown in FIG. 13 were compared. In addition, as a thermosetting type adhesive material used for the adhesive layer 16, an inorganic filler material such as talc is added for the purpose of improving moisture-proof performance (decreasing water vapor transmission rate).

  As an index of the moisture-proof performance, since the resolution is remarkably lowered due to the humidity deterioration of the CsI: Tl film formed as the scintillator layer 13, the change (reduction rate) of the resolution before and after the heating and humidifying test is used.

  Further, as a comparative example, a sample in which a CsI: Tl film as a scintillator film was formed to a thickness of 600 μm on a glass substrate and a parylene CVD film was formed as a moisture-proof film was also measured in the same manner.

  For the measurement, an X-ray chart image was taken, and a CTF (Contrast Transfer Function) value of a resolution chart of 2 Lp / mm was used.

  The heating and humidification conditions were 60 ° C.-90% RH × 500H. If the CTF (2Lp / mm) maintenance rate after this warming and humidification test is 80% or more, it is considered that it has a practical level high temperature and high humidity resistance. In addition, the state of deterioration with the passage of time was graphed by measuring appropriately at intermediate time steps.

  FIG. 6 shows the results obtained. From this result, it can be seen that in the radiation detector formed with the parylene CVD film, the resolution deterioration has already become apparent after 24 hours of heating and humidification, and the resolution has deteriorated significantly after 100 hours.

  On the other hand, in the radiation detector 10 of this embodiment and the radiation detector 50 of the conventional example shown in FIG. 13, the maintenance rate of CTF (2 Lp / mm) is 95% or more even after 500 hours, which is sufficient. Is considered to have a practical level of moisture-proof performance.

[Example 2]
(Relationship between filler material addition rate and moisture-proof performance)
The adhesive sealing material used for the adhesive layer 16 was examined.

  In the radiation detector 10 having the structure shown in FIG. 3, a trial production was performed by varying the addition rate of the filler material (talc) based on the epoxy adhesive, and the same 60 ° C.-90% RH as in Example 1. The CTF (2Lp / mm) maintenance rate after the heating and humidification test of x500h was compared. The average thickness of the adhesive layer 16 in the portion including the FPC wiring layer 9 and the ACF layer 8 is about 100 μm, and the width of the adhesive layer 16 is 3 to 5 mm.

  FIG. 7 shows the results obtained. From this result, it was found that the moisture-proof performance was remarkably improved as the filler material addition rate was increased.

[Example 3]
(Relationship between presence of spacer material and moisture-proof performance)
In the radiation detector 10 having the structure shown in FIG. 3, a prototype using a SiO ₂ filler-added epoxy film as a spacer material was prototyped, and the characteristics were compared with those using no spacer material. The characteristics were compared with the CTF (2 Lp / mm) maintenance rate after the heating and humidification test of 60 ° C.-90% RH × 500 h, as in Example 1.

  In addition, in order to make it easy to understand the influence on the characteristic deterioration due to moisture permeability, an epoxy-based adhesive without filler addition was used as an adhesive for bonding the AL hat moisture-proof layer 15.

FIG. 8 shows the results obtained. From this result, the CTF (2 Lp / mm) retention rate after 60 ° C.-90% RH × 500 h was remarkably improved by adding SiO ₂ filler as a spacer material, and a clear improvement in moisture-proof performance was observed. .

[Example 4]
(Relationship between volume filling rate of filler material and moisture-proof performance)
In the radiation detector 10 having the structure shown in FIG. 3, trial manufacture was performed by varying the addition rate of the filler material (talc) based on the epoxy adhesive, and the moisture permeability coefficient was compared.

  FIG. 9 shows the results obtained. From this result, it has been found that the value of the moisture-proof coefficient is remarkably lowered as the addition rate of the filler material is increased.

[Example 5]
(Relationship between T / W value of adhesive layer 16 and moisture-proof performance)
In the radiation detector 10 having the structure shown in FIG. 3, a trial production was carried out by changing the T / W value of the adhesive layer 16, and after the heating and humidification test of 60 ° C.-90% RH × 500 h as in Example 1. The CTF (2 Lp / mm) maintenance rate was compared.

  FIG. 10 shows the results obtained. From this result, it was found that the moisture permeation effect from the adhesive layer 16 can be sufficiently suppressed when the relationship of T << W is satisfied, particularly when T / W is 0.1 or less.

[Example 6]
(Influence of the material of the reflective film 14)
As a reflective film 14 of the radiation detector 10 having the structure shown in FIG. 3, a reflective film 14 with a submicron TiO ₂ filler added and a metal reflective such as an APC (Au—Pt—Cu) alloy or an AL sputtered film. Samples were made as membranes, and the CTF (2 Lp / mm) maintenance rate after a warming and humidification test in a general environment of 24 ° C.-50% RH × 12 h was compared.

FIG. 11 shows the results obtained. From this result, it was found that when the reflective film was formed by adding a submicron TiO ₂ filler, the deterioration of CTF was remarkably suppressed as compared with the metal reflective film.

[Example 7]
(Effects of manufacturing methods on microphonics)
When manufacturing the radiation detector 10 according to the procedure shown in FIG. 4, the pressure inside the decompression chamber 34 is reduced to 0.1 atm, and the moisture-proof layer 15 and the array substrate 12 are bonded together, and the bonding is performed at atmospheric pressure. In this case, a detector was prepared, and then incorporated in a housing, and X-ray images were taken in a vibrating state. The results are shown in FIG.

  FIG. 12A shows a case where bonding is performed at atmospheric pressure, and FIG. 12B shows a case where bonding is performed under reduced pressure, and the image on the right side is a dark image of the entire detector surface at a certain time when vibration is applied. It is. In addition, the dark output value of the area surrounded by the horizontally long line is the left oscilloscope image.

  From this result, microphonic (fluctuation of dark image when a certain impact is applied to the product) when bonding is performed at a reduced pressure (0.1 atm) compared to when bonding is performed at atmospheric pressure. Has been improved to about 1/5 or less, and it has been found that the microphonic converges quickly (the time during which the microphonic is generated is short).

  5: connection part, 6: internal wiring layer, 7: TAB pad, 8: anisotropic conductive film layer, 9: FPC wiring layer (external wiring), 10, 30, 50: radiation detector, 12: array substrate, 13: scintillator layer, 14: reflective film, 15: moisture-proof layer, 15a: buttock, 16: adhesive layer

Claims (6)

A substrate comprising a pixel area provided with a plurality of photoelectric conversion elements for converting fluorescence into an electrical signal and an internal wiring layer drawn from the pixel area, and incident radiation provided on the pixel area of the substrate as fluorescence A scintillator layer to be converted, a connection portion connected to the internal wiring layer around the substrate and connected to the external wiring, and a hat shape having a flange to cover the scintillator layer, the scintillator layer being externally connected In a radiation detector comprising a moisture-proof layer that protects against moisture, and an adhesive layer that bonds the flange portion and the substrate of the moisture-proof layer,
The radiation detector is characterized in that the adhesive layer adheres at least a part of the flange and the substrate above the connection part.   The radiation detector according to claim 1, wherein the adhesive layer adheres the entire surface of the flange and the substrate above the connection portion.   The radiation detector according to claim 1, wherein the adhesive layer is formed by including an inorganic filler material in a resin material.   4. The adhesive layer according to claim 1, wherein the adhesive layer is formed so as to satisfy a condition that T / W, which is a ratio of thickness T to width W, is 0.1 or less. 5. The radiation detector described.   The radiation detector according to claim 1, wherein a TAB pad is formed in the connection portion. Forming a moisture-proof layer in a hat shape having a collar portion;
Applying an adhesive material to at least a part of the collar,
A substrate having a pixel area provided with a plurality of photoelectric conversion elements and an internal wiring layer drawn out from the pixel area is prepared, and a scintillator layer is provided on the pixel area of the substrate, and the internal area around the substrate Connecting the external wiring at the connection portion connected to the wiring layer;
Pasting at least a part of the flange and the substrate above the connection portion via the adhesive in a reduced pressure atmosphere;
A method for manufacturing a radiation detector.