JP2011141158A - Infrared detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To acquire a highly reliable and high-performance infrared detector capable of acquiring a highly reliable joint surface at a joint section between an infrared window and a can made of metal by controlling the flow of a jointing material and preventing the occurrence of malfunctions which occur due to the inflow of the jointing material and the occurrence of reductions in sensitivity characteristics of a thermal infrared sensor. <P>SOLUTION: It is possible to control the flow of the jointing material, stabilize a jointed state, and acquire a highly reliable joint surface by providing a window (hole) of the can made of metal with a recession-type groove structure and forming an infrared window section in which a metallized film is deposited smaller in size than the most external dimension and larger than the minimum dimension of a recession-type groove structure section of the can made of metal. It is possible to prevent the inflow of the jointing material to the inside of a package when the can made of metal is jointed to the infrared window by depositing a metallized film formed in an outer edge section of the infrared window to an outside area having the same size as or more than the window (hole) of the can made of metal. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an infrared detector having an improved structure related to a metal can and an infrared window in a package structure of a thermal infrared detector that particularly requires vacuum hermetic sealing.

  The thermal infrared detector captures the weak thermal change energy of infrared rays emitted from the measurement object, and converts the temperature change of electrical characteristics such as current value, voltage value, resistance value into electrical signals, It is a detector that outputs.

Since the thermal infrared detector reduces the loss due to thermal diffusion of the infrared energy incident on the infrared light receiving element, it is important to increase the thermal insulation. In order to obtain high resolution, that is, to obtain high thermal insulation, the thermal conductivity is suppressed by making the infrared light receiving element structure, the infrared light receiving element a heat insulating structure, or by making the atmosphere in the package housing the element a vacuum. . It is generally known that the inside of the detector package is set to a low pressure and the degree of vacuum is about 10 ⁻² Pa or less.

Furthermore, after vacuum sealing the package, the reactive gas from the inside of the package member (N _2, 0 _2, etc.), hydrogen, moisture, outgas such as hydrocarbons is generated and thereby the degree of vacuum in the package is reduced It is known. Therefore, in order to maintain the vacuum state inside the package for a long time, a gas adsorbent called a getter is generally used. In order to absorb this outgas, a getter is mounted in a package together with a thermal infrared light receiving element. It is known that gas is efficiently adsorbed by heating to 350 to 900 ° C. in a vacuum or in an inert gas atmosphere at the time of getter mounting and performing activation.

Further, as described above, in order to make the inside of the package vacuum (about 10 ⁻² Pa or less), a metal can comprising the package, a metal base including an electrical connection terminal hermetically sealed with glass, It is known that each joint portion of the infrared transmission window is required to have high reliability.

  As a conventional infrared detector, a thermal infrared light receiving element 2 and a sheet-like getter 4 for gas adsorption are mounted on a metal base 1 having an electrical connection terminal hermetically sealed with glass. A metal can 5 having a window (hole) 13 is welded to a metal base 1 on which the sensor element 2 and the sheet-like getter 4 are mounted, and then a metallized film 11 is formed on the outer edge and an infrared transmission film 12 is formed on the center. A structure having a structure as shown in FIG. 1 in which the inside of the package is evacuated by joining the filmed infrared transmission window 6 to the joining material 7 in a vacuum is already known. (Patent Document 1)

Japanese Patent Application No. 2008-198075

  As shown in FIG. 2, the conventional infrared detector has an infrared window 6 (the opposite surface is a front infrared transmission film 12) and a window (hole) on which the metallized film 11 is formed on the outer edge of the joint surface and the infrared transmission film 12 is formed in the center. ) The plated metal can 5 having 13 is joined by a joining material 7 such as a low melting point solder. The infrared window 6 is bonded to the upper surface of the metal can by sandwiching a bonding material 7 and applying pressure and heating. The upper surface of the metal can 5 to which the infrared window 6 is joined has only a window (hole) 13 and is a flat surface. Since the infrared window 6 is bonded to the upper surface of the metal can, the state of the bonded portion and the flow shape of the bonding material 7 vary depending on the jig overlapping state, pressure / temperature conditions, and workpiece variations, and control of the bonded state There has been a problem that has become difficult.

  Further, as shown in the metal can-infrared window joint sectional view of FIG. 3, the metallized area of the metallized film 11 of the infrared window 6 is formed smaller (inward) than the size of the window (hole) 13 of the metal can. It was. For this reason, during bonding, the bonding material may flow into the package, and a solder pool may be formed inside the package. Due to this solder accumulation, there are problems such as malfunction due to short-circuiting of the internal wire (FIG. 4), blocking the visual field of the thermal infrared element (FIG. 5), and reducing the sensitivity characteristics of the thermal infrared sensor.

  The present invention has been made in order to solve the above-described problems, and at the time of joining the metal can 5 and the infrared window 6, the flow of the joining material 7 is controlled and the joining state is stabilized. The window (hole) has a concave groove structure, and the size of the infrared window portion on which the metallized film is formed is smaller than the outermost dimension of the groove portion of the concave groove structure portion of the metal can, and the concave groove portion of the can It is characterized by being larger than the minimum dimension.

  Further, in order to prevent the bonding material from flowing into the package when the metal can 5 and the infrared window 6 are joined, the metallized film 11 formed on the outer edge of the infrared window 6 is attached to the window (hole) of the metal can 5. ) It is characterized in that the film is formed in an area outside the same size with respect to 13 sizes.

  The infrared detector according to the present invention includes a metal can window (hole) 13 for controlling the flow of a bonding material on a metal can upper surface portion, and a concave groove structure in the metal can window (hole) 13. The size of the window part is smaller than the outermost dimension of the groove part of the concave groove structure part of the metal can, and larger than the minimum dimension of the concave groove part of the can, so that when joining the metal can and the infrared window, It becomes possible to control the flow and to stabilize the joining state. Compared to the conventional metal can and infrared window bonding surface, a more reliable bonding surface can be obtained.

  In addition, since the metallized film formed for joining the infrared window of the present invention is formed in an area outside the same size as the window (hole) 13 size of the metal can 5, There is no flow of bonding material or solder accumulation. As a result, it is possible to solve the problem that the operation failure due to the short circuit and the sensitivity characteristics of the thermal infrared sensor are deteriorated due to partially blocking the visual field of the thermal infrared element.

  As described above, the upper surface of the metal can has a concave groove structure that makes it possible to control the bonding material, and the size of the infrared window portion on which the metallized film is formed is the size of the concave groove structure portion of the metal can. It is smaller than the outermost dimension of the groove part and larger than the minimum dimension of the concave groove part of the can, and the metallized film is formed in an area outside the same size as the window (hole) 13 size of the metal can 5 This makes it possible to obtain a highly reliable and high performance infrared detector.

Cross-sectional view of the internal structure of a conventional infrared detector Infrared window shape and conventional metal can shape Cross section of conventional metal can-infrared window joint Cross section of internal structure when malfunction occurs due to short of internal wire Cross section of the internal structure of the thermal infrared device Cross-sectional view of the internal structure of an infrared detector according to the present invention Infrared window shape and metal can shape in the present invention The figure which shows the infrared window size concerning this invention Diagram showing metallized area deposited on infrared window for this study Enlarged view showing difference in cross section of joint due to difference in size of infrared transmission window The enlarged view which shows the difference of the junction cross section by the difference in the film-forming area of the metallization film | membrane 11 formed into an infrared rays transmission window

Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG.
FIG. 6 is a sectional view of the internal structure of the infrared detector according to the present invention.

6, 1 is a metal base having an electrical connection terminal hermetically sealed with glass, 2 is a thermal infrared light receiving element, 3 is a die bonding material, 4 is a sheet-like getter, 5 is a metal can, 6 is an infrared transmission window, 7 is a bonding material, 8 is an electrical connection terminal for mounting a getter, 9 is an electrical connection terminal, 10 is a concave groove structure for controlling the bonding material, and 11 is a metallized film. The 12 infrared transmission films are not shown.
A thermal infrared detection element 2 is mounted on a metal base 1 having an electrical connection terminal hermetically sealed with glass via a die bonding material 3. The thermal detection element 2 is electrically connected to the electrical connection terminal 9 by wire bonding using gold or aluminum. Further, the metal base 1 includes an electrical connection terminal 8 for mounting the sheet-like getter 5 and an electrical connection terminal 8 for mounting the getter.

  Here, the thermal infrared detecting element 2 is, for example, a thermistor bolometer element in which elements having a bridge structure are arranged on an element substrate in a two-dimensional array. Each element arranged in a two-dimensional array has a bridge structure, so that a certain distance is provided between the element and the substrate, thereby obtaining thermal insulation. As an example, a thermistor bolometer is used, but a thermopile element in which thermal insulation is important may be used. The die bonding material 3 uses a die bonding material with less outgas in order to prevent a decrease in the degree of vacuum after mounting.

  The sheet-like getter is mounted by welding both ends to the upper end of the getter mounting electrical connection terminal 8 of the metal base 1. This sheet-like getter 5 is formed by sintering titanium, zirconium or the like on a nichrome sheet, and is heated to 350 to 900 ° C. by energizing the nichrome sheet via the getter mounting electrical connection terminal. When the surface is activated, it is a non-evaporable getter that adsorbs a gas released from the material in the vacuum package and prevents deterioration of the vacuum in the vacuum package.

  Further, a vacuum package is formed by welding a metal can 5 to the metal base 1 and hermetically joining the infrared window 6 in a vacuum. The infrared window 6 is hermetically bonded to the metal can 5 via a bonding agent 7 such as a low melting point solder.

FIG. 7 shows an infrared window shape diagram and a metal can shape shape according to the present invention. The metal can 5 has a window (hole) 13 on the upper surface of the metal can 5 to which the infrared window 6 is joined. Further, a concave groove structure 10 is provided on the outer periphery of the window (hole) 13.
By adopting such a structure, it is possible to control the flow of the bonding material 7 at the time of secret bonding in a vacuum, the bonding state is stabilized, and a highly reliable bonding surface can be obtained.

  The infrared transmitting window 6 is made of an infrared transmitting material such as silicon. The front and back surfaces of the infrared transmission window are coated with an antireflection film or an infrared transmission film 12 that transmits a wavelength band such as 8-14 μm that transmits infrared rays of a desired wavelength. The infrared transmission window 6 may be made of a material such as chalcogenide glass, germanium, zinc sulfide, or zinc selenide.

  As shown in FIG. 8, the size of the infrared transmitting window 6 is smaller than the outermost dimension of the groove portion of the concave groove structure portion 10 of the metal can 5 and larger than the minimum dimension of the concave groove portion of the can. By setting it as such a size, it becomes possible to increase and stabilize the quantity of the joining material 7 of the metal can 5-infrared window 6 joint surface, and to obtain a highly reliable joint surface.

  Further, a metallized film 11 is formed on the outer edge of the infrared transmission window 6 on the side of the joint surface with the metal can 5 so that the joint material 7 can be joined. As shown in FIG. 9, the metallized film in this research is formed in an outer area of the same size or larger with respect to the metal (window) area of the metal can. As a result, the bonding material does not flow into the package and solder pool does not occur. As a result, it is possible to solve the problem that the operation failure due to the short circuit and the sensitivity characteristics of the thermal infrared sensor are deteriorated due to partially blocking the visual field of the thermal infrared element.

Here, an experimental example of the effect of 1) the size of the infrared window 6 of the present invention and 2) the film formation area of the metallized film 11 formed on the infrared transmission window 6 will be described.
1) Size of the infrared window 6 FIG. 10 is an enlarged view showing a difference in the cross section of the joint due to the difference in the size of the infrared transmission window. In the case of the window size of this research, the bonding material is in a good state, and the bonding material does not flow inside the package, and no solder pool is formed inside the package. However, when the size of the infrared window 6 is smaller than the minimum dimension of the concave groove of the can, the bonding material flows into the inside of the package, and a solder pool is formed inside the package.
2) Film formation area of metallized film 11 formed on infrared transmission window 6 FIG. 11 is an enlarged view showing a difference in cross section of the joint due to a difference in film formation area of metallization film 11 formed on the infrared transmission window. . If the metallized area is formed in the same size or larger area than the window (hole) size of the metal can, the bonding material does not flow into the package and solder pool does not occur. . However, when the metallized area was formed in the inner area smaller than the window (hole) area size of the metal can, the bonding material flowed into the inside of the package, and a solder pool was formed.

  According to the embodiment described above, the flow of the bonding material can be controlled, the bonding state can be stabilized, and a highly reliable bonding surface can be obtained. It is possible to prevent the deterioration of the sensitivity characteristics of the thermal infrared sensor due to partially blocking the field of view of the element, and a highly reliable and high performance infrared detector can be obtained.

DESCRIPTION OF SYMBOLS 1 Metal base provided with the electrical connection terminal sealed airtight with glass 2 Thermal type thermal infrared sensor element 3 Die bonding material 4 Sheet-like getter 5 Metal can 6 Infrared transmission window 7 Joining material 8 For getter mounting Electrical connection terminal 9 Electrical connection terminal 10 Groove structure 11 for bonding material control Metallized film 12 Infrared transmitting film 13 Window (hole)

Claims (2)

  The window (hole) of the metal can has a concave groove structure, and the size of the infrared window portion on which the metallized film is formed is smaller than the outermost dimension of the groove portion of the concave groove structure portion of the metal can. A thermal infrared detector comprising a vacuum hermetically sealed package characterized in that it is larger than the minimum dimension of the concave groove.   2. A thermal infrared detector comprising a vacuum hermetically sealed package according to claim 1, wherein the metallized area formed on the infrared window is outside the same size or larger than the window (hole) size of the metal can. A thermal infrared detector comprising a vacuum hermetically sealed package characterized in that a film is formed in the area.

Images