JPH03216582A - Multichannel ionization box type x-ray detector and electrode therefor - Google Patents

Abstract

PURPOSE:To prevent insulation inferiority by constituting an insulating layer of an insulating film composed of a synthetic resin having specific inductive capacity of 3.5 or less and an adhesive layer composed of a synthetic resin having specific inductive capacity of 3.5 or less for bonding a metal molybdenum plate and the insulating film. CONSTITUTION:An insulating layer 2 consists of an insulating film 20 and the second adhesive layer 22 bonding the insulating film 20 and a metal molybdenum plate 2. The insulating film 20, an adhesive layer 21 and the second adhesive layer 22 are respectively composed of a synthetic resin material having specific inductive capacity of 3.5 or less and glass transition temp. of 180 deg.C or higher. In this case, since there is the insulating film 20, even when conductive foreign matter is mixed with the adhesive layer 21 or the second adhesive layer 22 or a polymerization inferior part is formed therein during the bonding of the insulating film 20 and the metal molybdenum plate 1 or a copper foil 3, the insulation between the metal molybdenum plate 1 and the copper foil 3 is secured and high withstand voltage properties are kept.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a multi-channel ionization chamber type X-ray detector used in an X@CT device and the like, and an electrode plate for the multichannel ionization chamber type X-ray detector. be. More specifically, it concerns the improvement of the insulating layer between the base metal molybdenum plate and the conductor foil. [Prior Art] As shown in FIG. 2, a multi-channel ionization chamber type X-ray detector used in an X-ray CT system 1 includes an electrode plate 10 for signal detection and a bias in a container 4 filled with xenon gas. Electrode plates 11 for application are arranged alternately. These electrode plates 1
0. 11 are both made of X-ray shielding metals such as metallic molybdenum. Insulated \h poles for signal detection are formed on both sides of the electrode plate 10. As shown in the cross-sectional view of FIG. 4, the T4 electrode plate 10 has a metal molybdenum plate 1 as its base, and copper foil 3 is bonded to both sides of the plate with an insulating layer 24 interposed therebetween. If the dielectric constant of the insulating layer 24 is large, the response of the output signal of the X-ray detector to incident X-rays will be slow, so the insulating layer 24 is made of polyimide resin,
Synthetic resins with a dielectric constant of 3.5 or less, such as fluororesins and silicone resins, are used. By the way, the electrode plate 10 of such a multi-channel ionization chamber type X-ray detector is made by coating a semi-polymerized synthetic resin on a metal molybdenum plate 1 and a conductive foil 3, and pressing them together to polymerize the synthetic resin. By forming the insulating layer 24,
The metal molybdenum plate 1 and the conductor foil 3 are bonded together at the same time.

[The problem that the invention tries to solve! ! ] However, in the electrode plate 10 of the conventional multi-channel electric IW box-type XfIA detector, the insulating layer 24 is made by coating a semi-polymerized synthetic resin on the metal molybdenum base 1 and the conductive foil 3, and polymerizing the resultant mixture by heating and pressurizing them. Since the insulating layer 24 is formed by applying a coating or pressing method, foreign matter may be mixed into the insulating layer 24 during coating or pressing. Furthermore, the thickness of the insulating layer 24 may become uneven due to the flow of the synthetic resin. Additionally, during polymerization, the distribution of the solvent may become uneven, resulting in the formation of localized areas of poor polymerization. Problems such as contamination of foreign matter, non-uniform thickness, formation of defective polymerization points, etc. cause deterioration of electrical characteristics and poor insulation, resulting in defective channels in multi-channel ionization chamber type X-ray detectors. was there. The present invention has been made in view of the above, and its object is to provide an electrode plate for a multi-channel ionization chamber type X-ray detector in which insulation defects do not occur because the dielectric constant of the insulating layer is 3.5 or less. A further object of the present invention is to provide a multichannel ionization chamber type X-ray detector that does not generate defective channels due to poor insulation of electrode plates. [Means for solving the problems] Multi-channel ionization chamber type X of the present invention that solves the above problems
The electrode plate for a line detector is constructed by forming a conductive foil on at least one surface of a metal molybdenum plate with an insulating layer interposed therebetween, and the insulating layer has a dielectric constant of 3.5 or less and is made of glass. It is composed of an insulating film made of a synthetic resin with a transition temperature of 180°C or more, and an adhesive layer made of a synthetic resin with a dielectric constant of 3.5 or less and a glass transition temperature of 180°C or more, which bonds the metal molybdenum plate and the insulating film. It is characterized by: Moreover, the multi-channel ionization chamber type X-ray detector of the present invention that solves the above problems is equipped with a plurality of electrode plates,
The electrode plate is characterized by being an electrode plate for the multi-channel ionization chamber type X-ray detector described above. In addition, the insulating layer of these electrode plates has a dielectric constant of 3.5 or less and a glass transition temperature of 1 to bond the insulating film and conductive foil.
It is preferable that a second adhesive layer made of a synthetic resin having a temperature of 80° C. or higher is laminated.

Further, it is preferable that these TTI plates have conductor foil formed on both sides with an insulating layer interposed therebetween. In addition, the insulating film and adhesive layer that constitute the insulating layer of these electrode plates are
It is preferably made of one or more of polyimide resin, fluorine resin, and silicone resin. [Function] According to the present invention, the thickness of the insulating layer of the electrode plate is uniform, and the dielectric constant remains low, and the high insulation properties of the conductor foil are maintained.

[Example] An example of the present invention will be explained. The outline of the multi-channel ionization chamber type X-ray detector is similar to the conventional one shown in FIG. 2, but the structure of the electrode plate 10 is different. The electrode plate is shown in cross section in Figure 1 and explained. 1 is a metal molybdenum plate serving as a base, 2 is an insulating layer, and 3 is a copper foil. The insulating layer 2 includes an insulating film 20, an adhesive layer 21 for bonding the insulating film 20 and the metal molybdenum plate 1, and an insulating film 2.
0 and a second adhesive layer 22 that adheres the copper foil 3. The insulating film 20, adhesive layer 21, and second adhesive layer 22 are each made of a synthetic resin material with a dielectric constant of 3.5 or less and a glass transition temperature of 180° C. or higher. Since there is an insulating film 20, the insulating film 2
0 and the metal molybdenum plate 1 or the insulating film 20 and the copper foil 3, conductive foreign matter may be mixed into the adhesive layer 21 or the second adhesive layer 22, or poor polymerization points may be formed. Also, the insulation between the metal molybdenum plate 1 and the copper foil 3 is ensured, and a high withstand voltage can be maintained. Furthermore, insulating film 2
0, the adhesive layer 21. Since the flow of the synthetic resin during heat-sealing of No. 22 can be minimized, the uniformity of the thickness is greatly improved. In addition, since the dielectric constant of the insulating layer 2 is 3.5 or less, dielectric absorption is small, charging time and discharging time are shortened, and the incident X
It is advantageous that the output signal of the X-ray detector has a quick response to the radiation. When the dielectric constant exceeds 3.5, the signal response becomes slow. Furthermore, the glass transition temperature of the insulating film 20 is higher than that of the adhesive layer 2.
Since the glass transition temperature of 1.22 is also high, the insulating film 20 does not melt or change its physical properties during heat-sealing. Furthermore, if the glass transition temperature is lower than 180° C., the insulating layer 2 may be distorted when heat is applied during soldering, etc., and the adhesion to the metal molybdenum plate 1 may become weak or the substrate may warp. Insulating materials that meet these conditions and have excellent adhesion to metal molybdenum, voltage resistance, radiation resistance, and environmental resistance include polyimide resins, such as polyimide resins, such as polyamic acid condensed from citric acid. Fully aromatic polyimide, polyamino bismaleide, borigetone imide, polyimide-modified epoxy resin, phenolic resin, etc. formed by reaction are suitable, followed by fluorine resins, such as polytetrafluoroethylene, polyvinylidene fluoride, etc. , tetrafluoroethylene hexafluoropropylene copolymer, etc. are suitable, and silicone resin polymers etc. can also be used. Insulating film 20 of insulating layer 2, adhesive layer 2
The first and second adhesive layers 22 may be made of not only one of the above materials but also different materials. Such adhesive layer 21 and metal molybdenum plate 1
In order to increase the reliability of adhesion to the metal molybdenum plate 1, it is recommended to perform mechanical surface treatment such as sandblasting or chemical surface treatment on the surface of the metal molybdenum plate 1 to increase the surface area or activate the surface. ．． The second adhesive layer 22 may be omitted. In this case, the layer of copper foil 3 provided on the insulating layer 2 may be formed by plating copper or the like onto the insulating sheet 20. Then, an appropriate pattern can be formed by a subtractive method or an additive method. Copper is commonly used as the material for the conductor layer, but it is not limited to this. In addition, since the copper foil 3 is formed on both sides of the electrode plate 10 with the insulating layer 2 interposed, both sides of the electrode plate 10 can be made into independent channels, which improves X-ray utilization efficiency and resolution. I can contribute. If the copper foil 3 is formed only on one side of the electrode plate, these advantages are not available.

Furthermore, the difference in dielectric absorption due to the difference in permittivity is graphically shown in the fA3 diagram. The horizontal axis of the graph shows time. The vertical axis shows the voltage appearing on the electrode plate, the value of which is normalized by the initial value of charging. The curve in the graph shows the transition of the voltage that appears between the electrodes as a constant charge is discharged between the counter electrode and the ionized ions absorbed by the electrode plate are released. The subsequent electrode plate voltage should be zero due to the discharge, but a voltage is generated due to the outflow of ionized ions absorbed in the dielectric. Such a voltage is as shown by curve a in an electrode plate using an epoxy resin with a dielectric constant of 4.0 for the insulating layer, whereas in the case of the electrode plate using a polyimide resin with a dielectric constant of 3.1 for the insulating layer, the voltage is as shown in curve a. The electrode plate in the actual repair example decreases significantly as shown by curve b. In addition, in the multi-channel ionization chamber type X-ray detector of this example,
Electrode plates 11 for bias application without insulating layer 2 and copper foil 3 are installed alternately with electrode plates 10, but all electrode plates are of one type with insulating layer 2 and copper foil 3 on both sides. It may be composed of In this case, the bias can be applied by using the metal molybdenum plate 1 and the copper foil 3 on both sides in common to apply the bias.In this way, 2Pl can be applied at the manufacturing stage! There is no need to handle similar electrode plates, and the manufacturing procedure is simplified.

[Effects of the Invention] As described above, the multichannel ionization chamber type X-ray detector and the electrode plate for the multichannel ionization chamber type It is constructed by forming a conductive foil, and the insulating layer is
An insulating film made of a synthetic resin with a dielectric constant of 3.5 or less and a glass transition temperature of 180°C or more, and an insulating film with a dielectric constant of 3.5 or less and a glass transition temperature of 180°C for bonding the metal molybdenum plate and the insulating film. Since the adhesive layer is made of the above-mentioned synthetic resin, the thickness of the insulating layer is uniform, the heat resistance is high, and insulation failure does not occur.

Moreover, the multi-channel ionization chamber type X-ray detector is equipped with a plurality of electrode plates, and the electrode plate is the multi-channel t
a box type X&! Since this is an electrode plate for a detector, signals can be reliably detected in each channel without the occurrence of defective channels due to poor electrode insulation. Also, the response to incident X-rays is fast.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a configuration diagram showing an embodiment of the present invention and a conventional example, and FIG. 3 is a graph showing the influence of dielectric absorption. Figure 4 is a cross-sectional view of the conventional example. 1... Metal molybdenum plate, 10... Electrode plate, 2.2
4... Insulating layer, 20... Insulating film, 21...
Adhesive layer, 22... Second adhesive layer, 3... Copper foil.

Claims (8)

[Claims] (1) In a multi-channel ionization chamber type X-ray detector equipped with a plurality of electrode plates formed by forming conductive foil on at least one surface of a metal molybdenum plate with an insulating layer interposed therebetween, the insulating layer of the electrode plate is an insulating film made of a synthetic resin with a dielectric constant of 3.5 or less and a glass transition temperature of 180°C or more, and a metal molybdenum plate and an insulating film with a dielectric constant of 3.
．． A multi-channel ionization chamber type X-ray detector comprising an adhesive layer made of a synthetic resin having a glass transition temperature of 5° C. or lower and a glass transition temperature of 180° C. or higher. (2) In the multi-channel ionization chamber type X-ray detector according to claim (1), the insulating layer of the electrode plate further has a dielectric constant of 3.5 or less for bonding the insulating film and the conductive foil, and a glass transition temperature. A multi-channel ionization chamber type X-ray detector, characterized in that it is constructed by laminating a second adhesive layer made of a synthetic resin with a temperature of 180° C. or higher. (3) The multi-channel ionization chamber type X-ray according to claim (1) or (2), wherein the electrode plate is one in which conductor foil is formed on both sides of a metal molybdenum plate with an insulating layer interposed therebetween. Detector. (4) Claim (1) characterized in that the insulating film and adhesive layer constituting the insulating layer of the electrode plate are made of one or more of polyimide resin, fluorine resin, and silicone resin. ), (2) or (3) multichannel ionization chamber type X-ray detector. (5) In an electrode plate for a multi-channel ionization chamber type X-ray detector in which a conductive foil is provided on at least one surface of a metal molybdenum plate via an insulating layer, the insulating layer has a relative permittivity of 3.
．． An insulating film made of a synthetic resin with a dielectric constant of 5 or less and a glass transition temperature of 180°C or more, and an adhesive made of a synthetic resin with a dielectric constant of 3.5 or less and a glass transition temperature of 180°C or more, which bonds the insulating film and a metal molybdenum plate. An electrode plate for a multi-channel ionization chamber type X-ray detector, characterized by comprising a layer. (6) In the electrode plate for a multi-channel ionization chamber type X-ray detector according to claim (5), the insulating layer further has a relative dielectric constant of 3.5 or less for bonding the insulating film and the conductive foil, and a glass transition temperature. An electrode plate for a multi-channel ionization chamber type X-ray detector, characterized in that it is constructed by laminating a second adhesive layer made of a synthetic resin at a temperature of 180° C. or higher. (7) Claim (5) characterized in that the conductor foil is formed on both sides of a metal molybdenum plate with an insulating layer interposed therebetween.
) or the electrode plate for a multichannel ionization chamber type X-ray detector according to (6). (8) The insulating film and adhesive layer constituting the insulating layer are made of one or more of polyimide resin, fluorine resin, and silicone resin. 6) or the electrode plate for a multichannel ionization chamber type X-ray detector described in (7).