JP2014207348A - Optical detection sensor and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical detection sensor which eliminates the need of flux and seals a cap without causing solder of structures mounted on the cap and a header to be melted by heat, and to provide a manufacturing method of the optical detection sensor.SOLUTION: An optical detection sensor includes: a sensor chip 32 which detects light; a thermo-module 32 which cools the sensor chip; a cap 34 to which a window 35 is attached; a header 31 on which the sensor chip and the thermo-module are mounted; and low melting point solder 33 which has a melting point lower than a melting point of a solder material used in the sensor chip and the thermo-module and joins the header to the cap thereby making a seal therebetween.

Description

  The present invention relates to a light detection sensor for detecting radiation such as X-rays and gamma rays, and a method for manufacturing the same.

  FIG. 5 is a detailed configuration diagram of a conventional light detection sensor, FIG. 5 (a) is a top view of the light detection sensor, and FIG. 5 (b) is a cross-sectional view of the light detection sensor. This light detection sensor includes a header 1, a cap 2, a substrate 7, a sensor chip 9, a collimator 10, a window fixing material 11, a window 12, a temperature sensor 13, a getter material 14, a JFET (junction field effect transistor) 15, a multistage thermostat. A module 17 is included.

  The multistage thermo module 17 operates the sensor chip 9 that detects light at a low temperature of −70 ° C. to −20 ° C. A getter material 14 is attached to the header 1, and the getter material 14 serves to keep the atmosphere inside the light detection sensor in a vacuum state. The multistage thermo module 17 is configured by fixing a Peltier stage 5 made of three alumina substrates and a plurality of Peltier elements 4 with a solder material 18. The multistage thermo module 17 is fixed to the header 1 made of Kovar with the solder material 3.

  A sensor chip 9, JFET 15, and temperature sensor 13 are fixed on the substrate 7 made of alumina. When the sensor chip 9 is an X-ray sensor, a hydrocarbon adhesive 8 is generally used as a method for fixing to the substrate 7 as a measure against impure wires. The JFET 15 is bonded by a high melting point solder material 20, and the temperature sensor 13 is attached by an adhesive 21. The substrate 7 is fixed by an adhesive 6 on the uppermost Peltier stage 5 of the multistage thermo module 17.

  When the sensor chip 9 is an X-ray sensor chip, a collimator 10 made of a multilayer metal is fixed on the sensor chip 9 with an adhesive 22. A window 12 is pasted on the cap 2 in advance by a window fixing material 11. The material of the window 12 differs depending on the type of the sensor chip 9. When the sensor chip 9 is an X-ray sensor, the window 12 is made of a thin beryllium foil having a thickness of 20 to 30 μm. In this case, a solder material such as Ag—Cu is used as the material of the window fixing material 11.

  The cap 2 and the header 1 are fixed and sealed in a vacuum environment. As a method for fixing the cap 2 and the header 1, there are a plurality of methods such as resistance welding, an adhesive, and a solder. When fixing and sealing are performed by resistance welding, some deformation is seen in the hermetic sealing portion 16. When using an adhesive or a solder material, the adhesive or solder material may protrude somewhat from the sealed portion.

  The light detection sensor uses various adhesive materials and solder materials. The adhesive is required to be less degassed after being cured in order to avoid an increase in pressure in the internal atmosphere.

  In such a light detection sensor, in order to operate the sensor chip 9 at a low temperature, the multistage thermo module 17 is mounted in a narrow space inside the element, and the sensor chip 9 is cooled by the multistage thermo module 17.

  However, since the multistage thermo module 17 has a low cooling capacity, it is necessary to insulate it in order to exhibit its performance. For this reason, it is necessary to make the atmosphere of the space in which the multistage thermo module 17 and the sensor chip 9 are mounted (inside the space separated by the cap and the header) in a vacuum state.

  In addition, as a prior art, there exists an example which uses the pressure reduction inert gas for the atmosphere in a cap in the example described in patent document 1, and an infrared sensor and some X-ray sensors (patent document 2). ). In addition, there is a method using an adhesive as a method of joining the cap and the header with less impact (Non-Patent Document 1).

JP-A-1-236675 JP-A-4-173130 Japanese Patent Laid-Open No. 10-308555

Uber die Diffusion von Wasser durch Epoxyharz, J. barde leben, Kunstoffe, bd. 53, pp. 162-163, 1963

  However, in Patent Document 2, when the detection target of the sensor is low-energy X-rays, the low-energy X-rays are absorbed by nitrogen, argon, or xenon, which are reduced-pressure inert gases, and the amount of X-rays reaching the sensor is reduced. End up. In addition, when the X-ray incident on the sensor has sufficient energy to excite the inert gas, the fluorescent X-ray from the inert gas is input to the sensor and measured as an impure line. End up. In Non-Patent Document 1, it is difficult to keep the space inside the sensor element in a vacuum state for a long time because the adhesive allows moisture to pass through due to a diffusion phenomenon. Therefore, brazing is generally used as a method for joining the cap and the header.

  However, since soldering is performed by raising the temperature of the cap or header to a temperature at which the solder (wax) is melted, the solder of the structure mounted on the cap or header may be melted by heat before sealing the cap. there were. In general, soldering is performed using a flux.

  An object of the present invention is to provide a photodetection sensor that can seal a cap without the need for flux and can seal the cap without melting the solder of the structure mounted on the cap or header by heat, and a method for manufacturing the same.

  In order to solve the above problems, a light detection sensor according to the present invention includes a sensor chip for detecting light, a thermo module for cooling the sensor chip, a cap to which a window is attached, the sensor chip, and the thermo module. And a low melting point solder that has a melting point lower than the melting point of the solder material used for each of the sensor chip and the thermo module and that is sealed by joining the header and the cap. Features.

  A method of manufacturing a photodetection sensor according to the present invention includes a sensor chip that detects light, a thermo module that cools the sensor chip, a cap to which a window is attached, and a header that mounts the sensor chip and the thermo module. A method of manufacturing a photodetection sensor comprising: a low melting point solder having a melting point lower than a melting point of a solder material used for each of the sensor chip and the thermo module and sealed by joining the header and the cap. The surface of the low melting point material is etched and cleaned in a draft chamber, the low melting point material is dried in a glove box, and vacuum baking is performed in a vacuum sealing machine so that the low melting point solder has a temperature higher than the melting point in a vacuum atmosphere. To melt the joint with the cap and the cap And butterflies.

  According to the light detection sensor and the manufacturing method thereof of the present invention, the low melting point solder having a melting point lower than the melting point of the solder material used for each of the sensor chip and the thermo module and sealed by joining the header and the cap is provided. Since it is used, it is possible to provide a photodetection sensor that can seal the cap without using flux and that can seal the cap without melting the solder of the structure mounted on the cap or header by heat, and a method for manufacturing the same.

It is a figure which shows the method of joining the cap and header of the photon detection sensor of Example 1 with a low melting-point solder. It is a figure which shows melting | fusing point of various solder materials. It is a figure which shows the manufacturing method of the optical detection sensor of Example 1, and the manufacturing apparatus of an optical detection sensor. It is a figure which shows the method of joining the cap and header of the photon detection sensor of Example 2 with a low melting point solder. It is a detailed block diagram of the conventional photodetection sensor.

  Embodiments of a light detection sensor and a method for manufacturing the same according to the present invention will be described below in detail with reference to the drawings.

  The light detection sensor of the first embodiment uses a low melting point solder that can be bonded without putting the internal structure in a high temperature state when the cap and the header are sealed. Although there are a plurality of types of low melting point solders, joining is difficult as compared with Sn-Pb. FIG. 2 shows melting points of various solder materials. For example, indium-based solder (In, In—Sn, In—Ag), which is a general low melting point solder, is easily oxidized, and even if the temperature is higher than the melting point, the surface oxide film interferes with bonding and is difficult to join.

  In general, it is possible to remove the oxide film on the surface layer by using flux together with low melting point solder, but in the case of a light detection sensor that needs to keep the inside vacuum, using flux increases the internal pressure, Unsuitable.

  There is also a method of removing the surface oxide film by heating while reducing the indium-based solder. However, hydrogen with high thermal conductivity enters the solder material, and hydrogen gradually increases in the atmosphere inside the cap after vacuum sealing. This is unsuitable because there is a high possibility that hydrogen exceeding the adsorption capability of the hydrogen getter material in the cap is contained in the cap. Furthermore, in order to suppress an increase in the internal atmosphere before sealing the cap, it is necessary to bake the cap, the solder material, and the mounted header material in a vacuum atmosphere before sealing the cap. Vacuum baking is performed in order to degas from the inside of various components, and ideally, it is desirable to perform at high temperature for a long time.

  However, vacuum baking cannot be performed at a temperature higher than the melting point of solder (solder) used for various parts. Moreover, in order to avoid the influence of high temperature deterioration in the Peltier element of the internal structure (the solder material of the Peltier element constituting the multistage thermo module deteriorates due to the diffusion phenomenon due to heat), the temperature is generally 140 ° C. to 150 ° C. Processing is performed.

  From the above, In-based materials (In and In-Ag) are appropriate as the brazing material, but it is necessary to solve the problem of the oxide film at the time of bonding.

  Therefore, in the light detection sensor of the first embodiment, brazing with a low melting point solder is performed when the cap on which the mounted header and the window are fixed is hermetically sealed. The low melting point solder uses a metal material that melts at a low temperature of 140 ° C. to 160 ° C. Also, the low melting point solder becomes difficult to join due to surface oxidation. For this reason, in Example 1, the following joining method is adopted.

(1) First, the solder material is etched and washed, then dried in an inert gas such as dry nitrogen, and put in a vacuum chamber without being exposed to the air as it is. In addition, when a low melting point solder is attached to the cap by a vacuum deposition method or the like, an operation such as etching becomes unnecessary. The cap with the low melting point solder is moved to the vacuum chamber without being exposed to the atmosphere.

(2) Next, in a work space in a vacuum atmosphere, the low melting point solder is melted to join the cap and the header.

  Next, a method of joining the cap and the header of the light detection sensor of Example 1 with low melting point solder will be described with reference to FIGS. 1 and 3. FIG. 3 is a flowchart illustrating a method for manufacturing the light detection sensor according to the first embodiment and a diagram illustrating a device for manufacturing the light detection sensor.

  First, as the low melting point solder 33, indium (melting point: 156.4 ° C.) or indium-based melting point solder (In-Ag: melting point: 143 ° C.) is used. The low melting point solder 33 has a melting point lower than the melting point of the solder material used for each of the sensor chip 9, the multistage thermo module 17, and other internal components.

  For example, the low melting point material is formed into an annular shape, and the surface of the formed annular low melting point material is chemically etched in the draft chamber 51 (step S101). Thereafter, the substrate is washed (washed with water) in an environment that is not exposed to air (for example, a nitrogen atmosphere) (step S102).

  Next, in the glove box 52, the formed annular low melting point material is dried (step S103).

  Further, the formed annular low-melting point material is moved to a vacuum sealing machine 53 for joining. And as shown in FIG. 1, the cyclic | annular low melting-point solder 33 is fixed to the header 31 after the completion | finish of mounting in which the internal component 32 was set | placed. Further, vacuum baking is performed to degas (step S104).

  Further, the low melting point solder 33 is melted at a temperature higher than the melting point in a vacuum atmosphere (step S105). Thereafter, the cap 34 after the window 35 is fixed is sealed by being joined to the header 31 while applying pressure from the upper part so as not to destroy the window 35 (step S106).

  In addition, as a method of heating in order to melt the annular low melting point solder 33, a heater is brought into close contact with the back side of the header 31 to raise the temperature.

  As described above, according to the light detection sensor and the manufacturing method thereof according to the first embodiment, the flux is not necessary in the low melting point solder which conventionally required the flux for removing the oxide film. This eliminates the problem of occurrence of nations and can be used as a vacuum sealing material.

  Further, the multi-stage thermo module 17 or the window 35 is fixed by using the low melting point solder 33 having a melting point lower than the melting point of the solder material used for each of the sensor chip 9, the multi-stage thermo module 17, and other internal components. The solder material for melting does not remelt.

  Furthermore, by using the low melting point solder 33, there is no impact when performing resistance welding or the like. Further, the influence of high temperature deterioration of the Peltier element 4 used in the multistage thermo module 17 is reduced.

  FIG. 4 is a diagram illustrating a method of joining the cap 34 and the header 31 of the light detection sensor according to the second embodiment with the low melting point solder 37. In the method for joining the cap 34 and the header 31 of the light detection sensor of the second embodiment, as shown in FIG. 4, an annular low-melting-point solder 37 is applied to the end of the cap 34 by a method such as vacuum deposition. Adhere thick. Also in this case, the annular low-melting-point solder 37 is moved in an inert gas such as nitrogen gas without being exposed to the air when the cap 34 is taken out from the vacuum vapor deposition machine.

  As a method for joining the cap 34 and the header 31, the cap 34 is heated at a temperature higher than the melting point of the low melting point solder 37 and lower than the melting point of other solder materials while applying pressure from the upper part of the cap 34 so as not to break the window 35. 34 and the header 31 are joined.

  As a heating method, there are a method of heating with a hot plate and a method of heating the cap 34 using radiant heat from a lamp. In this case, since it is not exposed to air, it is not necessary to remove the oxide film.

  Thus, also in the light detection sensor of Example 2, the same effect as the effect of the light detection sensor of Example 1 is acquired.

  The light detection sensor and the manufacturing method thereof according to the present invention can be used for an infrared detection sensor, a light emitting element, and other general sensors.

DESCRIPTION OF SYMBOLS 1,31 Header 2,34 Cap 3,18,20 Solder material 4 Peltier element 5 Peltier stage 6, 8, 21, 22, Adhesive 7 Substrate 9 Sensor chip 10 Collimator 11 Window fixing material 12, 35 Window 13 Temperature sensor 14 Getter Material 15 JFET
16 hermetically sealed portion 17 multistage thermo module 32 built-in component 33 annular low melting point solder 37 low melting point solder 51 draft chamber 52 probe box 53 vacuum sealing machine

Claims (10)

A sensor chip for detecting light;
A thermo module for cooling the sensor chip,
A cap with a window attached;
A header on which the sensor chip and the thermo module are mounted;
A low-melting-point solder having a melting point lower than the melting point of the solder material used for each of the sensor chip and the thermo-module, and sealed by joining the header and the cap;
A photodetection sensor comprising:   The light detection sensor according to claim 1, wherein the light detection sensor is an X-ray detection sensor.   The light detection sensor according to claim 1, wherein the low melting point solder is indium or an indium low melting point solder having a melting point of 160 ° C. or less.   The light detection sensor according to claim 3, wherein the low melting point solder is an annular solder material.   The light detection sensor according to claim 1, wherein the low melting point solder is attached in advance to a joint portion of the cap with the header. Used for each of the sensor chip for detecting light, a thermo module for cooling the sensor chip, a cap to which a window is attached, a header for mounting the sensor chip and the thermo module, and the sensor chip and the thermo module. A melting point lower than the melting point of the solder material to be obtained, and a method for manufacturing a light detection sensor comprising a low melting point solder that is sealed by joining the header and the cap,
The surface of the low melting point material is etched and cleaned in a draft chamber, the low melting point material is dried in a glove box, and vacuum baking is performed in a vacuum sealing machine. A method for producing a photodetection sensor, wherein the header and the cap are joined together by melting in a step.   The method of manufacturing a light detection sensor according to claim 6, wherein the light detection sensor is an X-ray detection sensor.   8. The method of manufacturing a light detection sensor according to claim 6, wherein the low melting point solder is indium or an indium low melting point solder having a melting point of 160 [deg.] C. or less.   9. The method of manufacturing a light detection sensor according to claim 8, wherein the low melting point solder is an annular solder material.   10. The method of manufacturing a photodetection sensor according to claim 6, wherein the low melting point solder is attached in advance to a joint portion of the cap with the header. 11.

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