JP7435460B2 - Window materials, optical packages - Google Patents

Description

The present invention relates to window materials and optical packages.

Conventionally, after an optical element such as a light emitting diode is placed in a recess of a circuit board, the opening of the recess is sealed with a window material having a transparent resin base material, etc., and used as an optical package.

In this case, the window material was bonded to the circuit board using a resin adhesive or the like, but depending on the type of optical element, etc., there was a demand for improved airtight sealing performance. For this reason, it has been considered to bond the circuit board and the window material using a metal material instead of a resin adhesive.

For example, Patent Document 1 discloses a mounting board, an ultraviolet light emitting element mounted on the mounting board, a spacer disposed on the mounting board and having a through hole for exposing the ultraviolet light emitting element, and a cover disposed on the spacer so as to close the through hole, the ultraviolet light emitting element has an emission peak wavelength in the ultraviolet wavelength range, and the mounting board includes a support and a cover on the support. a supported first bonding metal layer; the spacer includes a spacer body formed of Si; and a supported first bonding metal layer of the mounting board on a side of the spacer body facing the mounting board. a second bonding metal layer facing the spacer layer and formed along the entire circumference of the outer periphery of the opposing surface, the through hole being formed in the spacer body, and the through hole being formed in the spacer body; The opening area gradually increases as the distance from the mounting board increases, the cover is formed of glass that transmits ultraviolet light emitted from the ultraviolet light emitting element, and the spacer and the cover are directly bonded. , the second bonding metal layer of the spacer and the first bonding metal layer of the mounting board are bonded by AuSn over the entire circumference of the second bonding metal layer. An apparatus is disclosed.

Japanese Patent No. 5877487

In the light emitting device disclosed in Patent Document 1, the cover and the spacer are said to be directly bonded by anodic bonding, but cracks may occur in the cover after bonding.

In view of the problems of the prior art described above, one aspect of the present invention aims to provide a window material that suppresses cracking when bonded to a circuit board.

In order to solve the above problems, one aspect of the present invention provides a window material for an optical package including an optical element, comprising:
a base of inorganic material;
a bonding layer disposed on one surface of the inorganic material base along the outer periphery of the inorganic material base;
The width of the bonding layer is 0.2 mm or more and 2 mm or less,
The thickness of the bonding layer is greater than 15 μm and less than 100 μm,
The bonding layer has a solder layer,
The solder contained in the solder layer is tin-germanium-nickel based solder,
Provided is a window material in which the difference between the coefficient of thermal expansion of the inorganic material base and the coefficient of thermal expansion of the solder at 20°C or more and 200°C or less is 30 ppm/°C or less .

According to one aspect of the present invention, it is possible to provide a window material that suppresses cracking when bonded to a circuit board.

FIG. 2 is an explanatory diagram of the configuration of the window material of the present embodiment. FIG. 2 is an explanatory diagram of a configuration example of a side surface of an inorganic material base. FIG. 2 is an explanatory diagram of the configuration of an optical package according to the present embodiment.

Hereinafter, modes for carrying out the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments, and the following embodiments may be implemented without departing from the scope of the present invention. Various modifications and substitutions can be made to .
[Window material]
The window material of this embodiment will be explained.

The window material of this embodiment is a window material for an optical package equipped with an optical element, and includes a base made of an inorganic material and arranged along the outer periphery of the base made of an inorganic material on one surface of the base made of an inorganic material. It is possible to have a bonding layer formed by the bonding layer. The width of the bonding layer can be 0.2 mm or more and 2 mm or less, and the thickness of the bonding layer can be greater than 15 μm and 100 μm or less.

An example of the structure of the window material of this embodiment will be specifically described below with reference to FIGS. 1(A) and 1(B). FIG. 1(A) schematically shows a cross-sectional view in a plane parallel to the lamination direction of the inorganic material base 11 and the bonding layer 12 of the window material 10 of this embodiment. Moreover, FIG. 1(B) shows the structure when the window material 10 shown in FIG. 1(A) is viewed along the block arrow A shown in FIG. 1(A). That is, it shows a bottom view of the window material 10 shown in FIG. 1(A).

The window material 10 of this embodiment has a base 11 made of an inorganic material and a bonding layer 12. The bonding layer 12 can be placed on one surface 11a of the base 11 made of an inorganic material.

Here, one surface 11a of the inorganic material base 11 corresponds to the surface to be bonded to a circuit board provided with an optical element when manufacturing an optical package to be described later. In other words, one surface 11a of the inorganic material base 11 can be said to be the surface facing the optical element.

The other surface 11b of the inorganic material base 11 opposite to the one surface 11a becomes the surface exposed to the outside when used as an optical package.

Each member will be explained below.
(Substrate of inorganic material)
The inorganic material base 11 is not particularly limited, and can be made of any material and have any shape.

However, when the inorganic material base 11 is used as an optical package, the light in the wavelength range that is particularly required to be transmitted among the light related to the optical elements included in the circuit board (hereinafter referred to as "light in the desired wavelength range") is used. It is preferable to select the material, its thickness, etc. so that the transmittance is sufficiently high. For example, for light in a desired wavelength range, the transmittance is preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, and particularly preferably 90% or more.

When the light in the desired wavelength region is in the infrared region, the transmittance of the inorganic material base 11 is preferably 50% or more, and 70% or more, for example, for light in the wavelength range of 0.7 μm or more and 1 mm or less. It is more preferably 80% or more, even more preferably 90% or more.

Further, when the light in the desired wavelength range is in the visible range (blue to green to red), the transmittance of the inorganic material base 11 is 50% or more for light in the wavelength range of 380 nm or more and 800 nm or less. It is preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more.

The inorganic material substrate 11 preferably has a transmittance of 50% or more, more preferably 70% or more, when the light in the desired wavelength region is in the ultraviolet region, for example, for light in the wavelength range of 200 nm or more and 380 nm or less. More preferably 80% or more, particularly preferably 90% or more.

When the light in the desired wavelength region is UV-A light in the ultraviolet region, for example, the transmittance of the inorganic material base 11 is preferably 50% or more, and 70% or more for light in the wavelength range of 315 nm or more and 380 nm or less. is more preferable, 80% or more is even more preferable, and 90% or more is particularly preferable.

When the light in the desired wavelength region is UV-B light in the ultraviolet region, for example, the transmittance of the inorganic material base 11 is preferably 50% or more, and 70% or more for light in the wavelength range of 280 nm or more and 315 nm or less. is more preferable, 80% or more is even more preferable, and 90% or more is particularly preferable.

When the light in the desired wavelength region is UV-C light in the ultraviolet region, for example, the transmittance of the inorganic material base 11 is preferably 50% or more, and 70% or more for light in the wavelength range of 200 nm or more and 280 nm or less. is more preferable, 80% or more is even more preferable, and 90% or more is particularly preferable.

Note that the transmittance of the inorganic material substrate 11 can be measured according to JIS K 7361-1 (1997).

The material of the inorganic base 11 can be arbitrarily selected as described above, and is not particularly limited, but from the viewpoint of particularly improving hermetic sealability and durability, for example, quartz, Glass or the like can be preferably used. Quartz includes quartz glass and those containing 90% by mass or more of SiO ₂ . Examples of the glass include soda lime glass, aluminosilicate glass, borosilicate glass, alkali-free glass, crystallized glass, and high refractive index glass (nd≧1.5). Note that the material for the inorganic substrate is not limited to one type, and two or more types of materials can be used in combination. Therefore, for example, the material of the inorganic substrate 11 is selected from quartz, soda lime glass, aluminosilicate glass, borosilicate glass, alkali-free glass, crystallized glass, and high refractive index glass (nd≧1.5). One or more types of materials can be preferably used.

When glass is used as the material for the inorganic material base 11, the inorganic material base 11 may be chemically strengthened.

The thickness of the inorganic material base 11 is also not particularly limited, but for example, it is preferably 0.03 mm or more, more preferably 0.05 mm or more, and even more preferably 0.1 mm or more. , 0.3 mm or more is particularly preferable.

By setting the thickness of the inorganic material base 11 to 0.03 mm or more, the strength required for the optical package is sufficiently exhibited, and moisture etc. can not penetrate the optical element through the surface of the inorganic material base 11 of the window material. It is particularly possible to prevent the light from penetrating to the side where it is placed. As described above, by setting the thickness of the inorganic material base 11 to 0.3 mm or more, the strength of the optical package can be particularly increased, which is preferable.

The upper limit of the thickness of the inorganic material base 11 is also not particularly limited, but is preferably, for example, 5 mm or less, more preferably 3 mm or less, and even more preferably 1 mm or less. This is because by setting the thickness of the inorganic material base 11 to 5 mm or less, the transmittance of light in a desired wavelength range can be made sufficiently high. It is more preferable to set the thickness of the base 11 made of an inorganic material to 1 mm or less, since this makes it possible to particularly reduce the height of the optical package.

Note that although FIG. 1A shows an example of a plate-like shape (flat plate shape) as the inorganic material base 11, it is not limited to this form. The shape of the inorganic material base 11 is not particularly limited, and the thickness does not need to be uniform. For this reason, when the thickness of the inorganic material base is not uniform, it is preferable that the thickness of at least a portion of the inorganic material base that is on the optical path of light related to an optical element when used as an optical package is within the above range, It is more preferable that the thickness of the inorganic material substrate is within the above range in any part.

The shape of the inorganic material base 11 is not particularly limited as described above. For example, it may have a plate-like shape or a shape in which a lens is integrated, that is, a shape including concave portions and convex portions derived from the lens. Specifically, for example, one surface 11a of the base 11 made of an inorganic material is a flat surface and the other surface 11b has a convex portion or a concave portion, or the shape of one surface 11a and the shape of the other surface 11b are different. Examples include a form that is the opposite of the form in which . Further, one surface 11a of the inorganic material base 11 may have a convex portion and the other surface 11b may have a concave portion, or the shape of one surface 11a and the shape of the other surface 11b may be reversed. There are several forms that can be mentioned. Another example is a configuration in which each of the one surface 11a and the other surface 11b of the base 11 made of an inorganic material has a convex portion or a concave portion.

Note that even if one surface 11a of the base 11 made of an inorganic material has a convex portion or a concave portion, the portion of the one surface 11a of the base 11 made of an inorganic material where the bonding layer 12 is arranged is, for example, It is preferable that the bonding layer 12 be flat in order to suppress variations in the shape of the bonding layer 12 between window materials when manufacturing a window material.

Depending on the form of the optical package, the size of the inorganic material substrate may be very small. Therefore, when cutting the uncut material of the inorganic material base into a desired size, it is preferable to employ a cutting method using laser light. When cutting is performed by such a method, as shown in FIG. 2, the side surface of the inorganic material base 11 has a linear pattern along the outer periphery of one surface 11a, corresponding to the focal position of the laser beam. 111.

Note that the method for cutting the inorganic material base 11 is not limited to the above-mentioned example, and may be cut by any method. When cutting is performed by a method other than the above-mentioned cutting method, the side surface, that is, the cut surface, of the inorganic material base 11 may have a different cross-sectional shape from the above-mentioned case. Other cutting methods include, for example, a dicing saw and a wire saw. These cutting methods are effective when the thickness of the inorganic material substrate before cutting is 1 mm or more.

An antireflection film may also be provided on the surface of the base 11 made of an inorganic material. By arranging the anti-reflection film, when used as an optical package, light from the optical element or the outside is suppressed from being reflected on the surface of the inorganic material base 11, and the light from the optical element or the outside is prevented from being reflected. It is preferable because it can increase transmittance. The antireflection film is not particularly limited, but for example, a multilayer film can be used, and the multilayer film may include alumina (aluminum oxide, Al ₂ O ₃ ), hafnium oxide (HfO ₂ ), titanium oxide (TiO ₂ ), etc., and a second layer, which is a layer of silica (silicon oxide, SiO ₂ ), can be alternately laminated. The number of layers constituting the multilayer film is not particularly limited, but for example, if the first layer and the second layer are one set, the multilayer film may include one set of the first layer and the second layer. It is preferable to have at least two sets, more preferably two or more sets. This is because the multilayer film having one or more sets of the first layer and the second layer can particularly suppress light from being reflected on the surface of the base 11 made of an inorganic material.

The upper limit of the number of layers constituting the multilayer film is not particularly limited either, but from the viewpoint of productivity, for example, it is preferable to have four or less pairs of the first layer and the second layer.

When an antireflection film is provided, the antireflection film is preferably disposed on at least one surface 11a of the inorganic material base 11, and more preferably on both the one surface 11a and the other surface 11b. When anti-reflective films are arranged on both surfaces 11a and 11b, the structures of both anti-reflective films may be different, but from the viewpoint of productivity etc., it is preferable to have anti-reflective films with the same structure. is preferred.

When using the above multilayer film as the antireflection film, it is preferable that the second layer of silica be located on the outermost surface. By positioning the second layer of silica on the outermost surface of the anti-reflective film, the surface of the anti-reflective film has a composition similar to the surface of the glass substrate, and has particularly high durability and adhesion with the bonding layer 12. This is because it is preferable.
(bonding layer)
The bonding layer 12 corresponds to a member for bonding the inorganic material base 11 and a circuit board provided with an optical element when forming an optical package.

Although the shape of the bonding layer 12 is not particularly limited, for example, as shown in FIG. The bonding layer 12 including the bonding layer 122 may be arranged along the outer periphery of the base 11 made of an inorganic material. That is, the bonding layer 12 can have a band-like shape arranged along the outer periphery of the base 11 made of an inorganic material, for example. The bonding layer 12 may have an opening in the center corresponding to the optical element of the circuit board, and the base 11 made of an inorganic material can be seen through the opening. In FIG. 1B, the base 11 made of an inorganic material is larger than the bonding layer 12 including the solder layer 122, but the present invention is not limited to this form. For example, the configuration may be such that the outer periphery of the base 11 made of an inorganic material and the outer periphery of the bonding layer 12 including the solder layer 122 coincide with each other.

Note that although FIG. 1B shows the solder layer 122 located at the outermost surface of the bonding layer 12, a surface perpendicular to the stacking direction of each layer of the bonding layer 12 (vertical direction in FIG. 1A) It is preferable that the cross-sectional shape of the bonding layer 12 is the same regardless of the layer.

According to studies by the inventors of the present invention, the width (line width) W of the bonding layer 12 should be 0.2 mm or more and 2 mm or less, and the thickness T of the bonding layer 12 should be greater than 15 μm and less than 100 μm. is preferred.

Note that the width W of the bonding layer 12 is the width of the bonding layer 12 which has a band-like shape when viewed from the top or bottom surface of the inorganic material base 11, as shown in FIG. 1(B). It means. That is, the width W of the bonding layer 12 means the distance between the outer circumferential side surface 12A and the inner circumferential side surface 12B, as measured along a line segment drawn perpendicularly to the inner circumferential side surface 12B of the bonding layer 12. Further, the thickness T of the bonding layer 12 means the thickness of the bonding layer 12 in the lamination direction of the inorganic material base 11 and the bonding layer 12 (vertical direction in FIG. 1A). For example, as shown in FIG. 1A, when the inorganic material base 11 has a plate-like shape, the thickness T is measured along a line segment perpendicular to one surface 11a of the inorganic material base 11. This means the thickness of the bonding layer 12.

It is preferable that the width W and the thickness T of the bonding layer 12 satisfy the above range when measured at an arbitrary position on the bonding layer 12. That is, it is preferable that the above range is satisfied no matter where the measurement is made on the bonding layer 12.

The bonding layer 12 can have a base metal layer 121 and a solder layer 122, as described later. For example, when forming the solder layer 122, the bonding layer 12 and the inorganic material base 11 are heated and cooled. There are cases where The inorganic material base 11 and the bonding layer 12 are made of different materials and have different degrees of expansion and contraction during heating and cooling. Therefore, when the bonding layer 12 is formed, residual stress may occur at the interface between the inorganic material base 11 and the bonding layer 12. According to the studies conducted by the inventors of the present invention, it is presumed that such residual stress is the cause of cracks occurring in the window material when the window material and a circuit board equipped with an optical element are bonded together. Ru.

Therefore, in the window material 10 of this embodiment, the width W and the thickness T of the bonding layer 12 are set within predetermined ranges as described above to suppress the generation of the residual stress.

Specifically, by setting the width W of the bonding layer 12 to 2 mm or less, the interface between the inorganic material base 11 and the bonding layer 12 can be reduced, the generation of residual stress can be suppressed, and the circuit equipped with an optical element can be It is possible to suppress the generation of cracks in the window material 10, specifically, in the inorganic material base 11 when bonded to the substrate. The width W of the bonding layer 12 is preferably 0.6 mm or less, more preferably 0.4 mm or less.

However, if the width W of the bonding layer 12 is made too thin, the bonding strength between the window material and the circuit board provided with the optical element may decrease, so the width W of the bonding layer 12 is set to 0.2 mm or more. It is preferably 0.25 mm or more, and more preferably 0.25 mm or more.

Further, by setting the thickness T of the bonding layer 12 to 100 μm or less, the amount of deformation of the bonding layer 12 during formation of the bonding layer 12 can be suppressed, and the force applied from the bonding layer 12 to the base 11 made of an inorganic material can be suppressed. Therefore, generation of residual stress at the interface between the inorganic material base 11 and the bonding layer can be suppressed, and when bonded to a circuit board equipped with an optical element, the window material 10, specifically the inorganic material base This is preferable because it can suppress the occurrence of cracks in 11. The thickness T of the bonding layer 12 is more preferably 50 μm or less, and even more preferably 30 μm or less.

However, if the thickness T of the bonding layer 12 is made too thin, it will not be possible to absorb the unevenness of the bonding surface of the circuit board when bonding it to a circuit board equipped with an optical element. There is a risk that the strength will decrease, or a gap will be created at the joint with the circuit board, resulting in a decrease in airtightness. Therefore, as described above, the thickness T of the bonding layer 12 is preferably thicker than 15 μm.

Further, the distance D between the outer circumferential side surface 11A of the inorganic material base 11 and the outer circumferential side surface 12A of the bonding layer 12 is not particularly limited, but the distance D is not particularly limited. Therefore, it is preferably 0.5 mm or less, more preferably 0.3 mm or less, and even more preferably 0.1 mm or less.

The lower limit of the distance D between the outer circumferential side surface 11A of the inorganic material base 11 and the outer circumferential side surface 12A of the bonding layer 12 is not particularly limited. As described above, the outer circumference of the inorganic material base 11 and the outer circumference of the bonding layer 12 including the solder layer 122 can be configured to coincide, so for example, the distance D can be 0 or more. .

Note that the distance D between the outer peripheral side surface 11A of the inorganic material base 11 and the outer peripheral side surface 12A of the bonding layer 12 is the distance D between the outer peripheral side surface 11A of the inorganic material base 11 and the outer peripheral side surface 12A of the inorganic material base 11 in the bottom view, for example, as shown in FIG. It means the distance between the outer circumferential side surface 11A and the outer circumferential side surface 12A of the bonding layer 12 disposed along the outer circumferential side surface 11A of the base 11 made of the inorganic material. That is, when a straight line is drawn perpendicular to the outer peripheral side surface 11A of the inorganic material base 11 in the bottom view as shown in FIG. 1(B), the outer peripheral surface of the inorganic material base 11 on the straight line and the bond It means the shortest distance between the layer 12 and the outer peripheral side surface 12A.

The distance D between the outer circumferential side surface 11A of the inorganic material base 11 and the outer circumferential side surface 12A of the bonding layer 12 is the distance D between the outer circumferential side surface 11A of the inorganic material base body 11 and the bonding layer 12 at the corresponding position. It is preferable that the above range is satisfied when measured at any position on the outer circumferential side surface 12A. That is, it is preferable that the outer peripheral side surface 11A of the base 11 made of an inorganic material and the outer peripheral side surface 12A of the bonding layer 12 at a corresponding position satisfy the above range no matter where the measurement is performed.

The bonding layer 12 may be any member as long as it can bond the inorganic material base 11 and the circuit board provided with the optical element, and the material constituting the bonding layer 12 is not particularly limited. However, for example, it is preferable to select the material and shape of the bonding layer so that the parameter Z calculated by the following formula (1) is 130 or less, and the material and shape of the bonding layer are selected so that the parameter Z is 100 or less. It is more preferable.

なお、上記式（１）中のｘ０、ｘ１、ｘ２、ｘ３、ｘ４、ｘ５はそれぞれ以下のパラメータを示している。
ｘ０：無機材料の基体のヤング率（ＭＰａ）
ｘ１：無機材料の基体の２０℃以上２００℃以下における熱膨張係数（ｐｐｍ／℃）
ｘ２：接合層のヤング率（ＭＰａ）
ｘ３：接合層の２０℃以上２００℃以下における熱膨張係数（ｐｐｍ／℃）
ｘ４：接合層の平均高さ（ｍｍ）
ｘ５：接合層の幅（ｍｍ）
なお、「ｘ４：接合層の平均高さ」とは、接合層について、任意の５箇所以上８箇所以下でその高さを測定した場合の高さの平均値を意味する。また、「ｘ５：接合層の幅」についても、窓材内で均一ではない場合には任意の４箇所以上１２箇所以下でその幅を測定した場合の平均値とすることができる。

Note that x0, x1, x2, x3, x4, and x5 in the above formula (1) respectively indicate the following parameters.
x0: Young's modulus of inorganic material substrate (MPa)
x1: Thermal expansion coefficient (ppm/°C) of the inorganic material base at 20°C or more and 200°C or less
x2: Young's modulus of bonding layer (MPa)
x3: Thermal expansion coefficient of bonding layer at 20°C or higher and 200°C or lower (ppm/°C)
x4: Average height of bonding layer (mm)
x5: Width of bonding layer (mm)
Note that "x4: average height of the bonding layer" means the average value of the heights of the bonding layer when the heights are measured at arbitrary 5 or more and 8 or less locations. Moreover, regarding "x5: Width of the bonding layer", if the width is not uniform within the window material, it can be taken as the average value when the width is measured at arbitrary 4 to 12 locations.

Young's modulus can be calculated from the results of tests based on JIS Z2241 (2011) "Tensile test method for metallic materials", JISR1602 (1995) "Elastic modulus test method for fine ceramics", etc. Further, the thermal expansion coefficient is calculated according to JIS Z2285 (2003) "Method for measuring linear expansion coefficient of metal materials", JISR 3102 (1995) "Testing method for average linear expansion coefficient of glass", etc.

It is preferable to set the above-mentioned parameter Z to 130 or less because it is possible to particularly suppress the occurrence of cracks in the window material 10, specifically, inorganic material base 11 when bonded to a circuit board. Note that the lower limit value of the parameter Z is not particularly limited, but is preferably 10 or more.

The bonding layer 12 may be any member that can bond the inorganic material base 11 and the circuit board provided with the optical element, and the specific layer configuration is not particularly limited. However, from the viewpoint of improving airtightness when used as an optical package, it is preferable that the bonding layer 12 is made of a metal material. For example, as shown in FIG. , and a solder layer 122.

Hereinafter, an example of the structure of each layer of the bonding layer 12 will be described.

First, the base metal layer 121 will be explained.

The base metal layer 121 can have a function of increasing the adhesion between the inorganic material base 11 and the solder layer 122. Although the structure of the base metal layer 121 is not particularly limited, it is preferably composed of a plurality of layers as shown in FIG. 1(A).

Although the structure of the base metal layer 121 is not particularly limited, it can be composed of two or three layers, for example. Specifically, for example, it can have a first base metal layer 121A and a second base metal layer 121B in order from the base 11 side of an inorganic material. Furthermore, a third base metal layer 121C may be further disposed between the second base metal layer 121B and the solder layer 122.

The first base metal layer 121A can have a function of increasing the adhesion between the inorganic material base 11 and other layers. The material for the first base metal layer 121A is preferably a material that can improve the adhesion between the inorganic material base 11 and other layers, and more preferably a material that can also improve airtightness. The first base metal layer 121A is preferably a layer containing one or more types selected from, for example, chromium (Cr), titanium (Ti), tungsten (W), and palladium (Pd). The first base metal layer 121A can also be a layer made of one or more materials selected from, for example, chromium (Cr), titanium (Ti), tungsten (W), and palladium (Pd). Note that even in this case, it is not excluded that the first base metal layer 121A contains unavoidable impurities.

The first base metal layer 121A is preferably a metal film or metal oxide film of one or more metals selected from chromium (Cr), titanium (Ti), tungsten (W), and palladium (Pd). preferable.

The second base metal layer 121B has a function of increasing the adhesion between the solder layer and other layers, and is made of, for example, nickel (Ni), copper (Cu), platinum (Pt), or silver (Ag). The layer preferably contains one or more metals. From the viewpoint of particularly suppressing costs, it is more preferable that the second base metal layer 121B is a layer containing one or more metals selected from nickel (Ni) and copper (Cu).

Note that the second base metal layer 121B can also be a layer made of one or more metals selected from, for example, nickel (Ni), copper (Cu), platinum (Pt), and silver (Ag). Also in this case, from the viewpoint of cost, the second base metal layer 121B is preferably a layer made of one or more metals selected from nickel (Ni) and copper (Cu). Note that in any of the above cases, it is not excluded that the second base metal layer 121B contains unavoidable impurities.

Further, when the third base metal layer 121C is further provided, the third base metal layer 121C is preferably a layer containing one or more types selected from, for example, nickel (Ni) and gold (Au). In particular, when the third base metal layer 121C is a layer containing nickel (Ni), a layer containing a nickel-boron alloy (Ni-B) or a layer made of Ni-B is used to improve solder wettability. It is preferable that By providing the third base metal layer 121C, for example, reaction between the base metal layer 121 and the solder layer 122 can be particularly suppressed. The third base metal layer can also be a layer made of one or more metals selected from nickel (Ni) and gold (Au). Even in this case, it is not excluded that the third base metal layer contains unavoidable impurities.

The thickness of each layer constituting the base metal layer 121 is not particularly limited and can be arbitrarily selected.

For example, the thickness of the first base metal layer 121A is preferably 0.03 μm or more from the viewpoint of particularly enhancing the adhesiveness with the base 11 of the inorganic material. The upper limit of the thickness of the first base metal layer 121A is also not particularly limited, but from the viewpoint of sufficiently reducing costs, it is preferably 0.2 μm or less.

The thickness of the second base metal layer 121B is preferably 0.1 μm or more from the viewpoint of particularly improving adhesiveness with the solder layer 122. The upper limit of the thickness of the second base metal layer 121B is also not particularly limited, but from the viewpoint of sufficiently reducing costs, it is preferably 2.0 μm or less.

When the third base metal layer 121C is also provided, its thickness is not particularly limited, but from the viewpoint of particularly suppressing the reaction between the base metal layer 121 and the solder layer 122, it is preferably 0.05 μm or more, for example. The upper limit of the thickness of the third base metal layer is also not particularly limited, but from the viewpoint of sufficiently reducing costs, it is preferably 1.0 μm or less.

Next, the solder layer 122 will be explained.

The solder layer 122 has a function of bonding the inorganic material base 11 and the circuit board provided with the optical element when manufacturing an optical package, and its configuration is not particularly limited. The solder layer 122 can contain solder as described below, but the solder here refers to solder that is melted by heating when bonding to a circuit board equipped with an optical element, and then melted by cooling. It means a metal material that can be solidified and bonded to the circuit board. Particularly from the viewpoint of strong bonding, solder is a material that forms an intermetallic compound with the material placed on the bonding surface of a circuit board equipped with an optical element when the solder is heated above its melting temperature. It is preferable that

The thickness of the solder layer 122 is not particularly limited, but is preferably 5 μm or more, more preferably 15 μm or more. As described later, the insulating base material of the circuit board can be made of, for example, a ceramic material, but when it is made of a ceramic material, it is usually cast, so the surface to be joined to the window material 10 cannot be made completely flat. Often difficult. Therefore, it is preferable that the thickness of the solder layer is 5 μm or more, so that the unevenness of the surface of the insulating base material to be bonded to the window material 10 can be absorbed.

In addition, the thickness of the solder layer 122 here means the thickness of the solder layer 122 at any position of the window material 10 of this embodiment. Therefore, it is preferable that the solder layer satisfies this thickness range even at its thinnest portion.

The upper limit of the thickness of the solder layer is not particularly limited, but may be, for example, 50 μm or less.

Further, the average thickness of the solder layer 122 is preferably 5 μm or more, more preferably 15 μm or more. By setting the average thickness of the solder layer 122 to 5 μm or more, for example, even if the bonding surface of the circuit board to be bonded with the bonding layer 12 contains irregularities, the concave portions are filled with the material of the solder layer. This is because, in particular, the hermetic sealing performance can be improved.

Note that the above average value means a value of a simple average (sometimes called an arithmetic average or an arithmetic average). Hereinafter, when the term "average" is simply used, it means a simple average.

The upper limit of the average thickness of the solder layer 122 is also not particularly limited, but is preferably 50 μm or less, more preferably 30 μm or less. This is because even if the average thickness of the solder layer 122 becomes excessively thick, exceeding 50 μm, there will be no significant change in the hermetic sealing effect.

Note that the average value of the thickness of the solder layer 122 can be calculated by measuring the thickness of the solder layer 122 at a plurality of arbitrary measurement points with a laser microscope (manufactured by Keyence Corporation, model VK-8510) and finding the average value. The number of measurement points at which the thickness of the solder layer 122 is measured in order to calculate the average value is not particularly limited, but is preferably 2 or more points, and more preferably 4 or more points. The upper limit of the number of measurement points is also not particularly limited, but from the viewpoint of efficiency it is preferably 10 or less, more preferably 8 or less.

The thickness deviation of the solder layer 122, that is, the deviation from the simple average thickness is preferably within ±20 μm, more preferably within ±10 μm.

By setting the thickness deviation of the solder layer 122 within ±20 μm, it is possible to particularly improve the airtightness between the window material and the circuit board on which the optical element is placed when manufacturing an optical package. This is because it is possible and preferable.

The deviation of the thickness of the solder layer 122 within ±20 μm means that the deviation is distributed in a range of −20 μm or more and +20 μm or less.

The deviation in the thickness of the solder layer 122 can be calculated from the average value of the thickness of the solder layer described above and the measured value used when calculating the average value.

The solder layer 122 can contain various solders (bonding compositions), and can also be composed of various solders.

The solder included in the solder layer 122 is not particularly limited, but for example, a material with a Young's modulus of 50 GPa or less is preferable, a material with a Young's modulus of 40 GPa or less is more preferable, and a material with a Young's modulus of 30 GPa or less is even more preferable.

After forming an optical package, a temperature change may occur in the solder layer when, for example, the optical element is turned on or off. By setting the Young's modulus of the solder contained in the solder layer to 50 GPa or less, even if a temperature change occurs in the solder layer and the solder layer expands or contracts, other members such as the inorganic material base 11 can be prevented from being destroyed. This is because it is preferable because it can particularly suppress the

In addition, when the Young's modulus of the solder is 50 GPa or less, when used as an optical package, the stress caused by the difference in thermal expansion between the inorganic material base 11 and the circuit board equipped with the optical element can be absorbed by the solder layer that joins both components. This is because it can be absorbed within 122 degrees, which is preferable.

The lower limit of the preferred range of the Young's modulus of the solder contained in the solder layer 122 is not particularly limited, but may be greater than 0, for example, and is preferably 10 GPa or more from the viewpoint of improving hermetic sealing performance.

Young's modulus of solder can be calculated from the results of a tensile test performed on solder.

Further, the melting point of the solder contained in the solder layer 122 is preferably 200°C or higher, more preferably 230°C or higher. This is because when the melting point of the solder is 200° C. or higher, the heat resistance when used as an optical package can be sufficiently increased. However, the melting point of the solder used for the solder layer 122 is preferably 280° C. or lower. This is because heat treatment is performed when manufacturing the optical package to melt at least a portion of the solder layer 122. However, if the melting point of the solder is 280°C or lower, the temperature of the heat treatment can be kept low, so the optical element This is because it is possible to particularly suppress damage caused to the like. In addition, by keeping the heat treatment temperature low, it is possible to reduce the difference in the degree of shrinkage caused by the difference in thermal expansion coefficient between the inorganic material of the base 11 and the insulating material of the circuit board.

The density of the solder contained in the solder layer 122 is preferably 6.0 g/cm ³ or more, more preferably 7.0 g/cm ³ or more. This is because by setting the density of the solder used in the solder layer 122 to 6.0 g/cm ³ or more, the hermetic sealing performance can be particularly improved. The upper limit of the density of the solder used in the solder layer 122 is not particularly limited, but is preferably 10 g/cm ³ or less, for example.

Further, it is preferable that the coefficient of thermal expansion of the solder included in the solder layer 122 has a predetermined relationship with the coefficient of thermal expansion of the base 11 made of an inorganic material. Specifically, it is preferable that the difference between the thermal expansion coefficient of the inorganic material base and the thermal expansion coefficient of the solder included in the solder layer is small. More specifically, it is preferable that the difference between the thermal expansion coefficient of the inorganic material base 11 and the thermal expansion coefficient of the solder included in the solder layer 122 at 20° C. or higher and 200° C. or lower is 30 ppm/° C. or lower, and 10 ppm/° C. or lower. /°C or less is more preferable.

This suppresses the residual stress generated between the inorganic material base 11 and the bonding layer 12 when the difference between the thermal expansion coefficient of the inorganic material base 11 and the solder included in the solder layer is small. This is because cracks can be particularly suppressed when bonded to a circuit board. Note that the difference between the thermal expansion coefficient of the inorganic material base and the thermal expansion coefficient of the solder included in the solder layer can be 0 or more.

The coefficient of thermal expansion of the solder contained in the solder layer 122 is not particularly limited, but the coefficient of thermal expansion is preferably 30 ppm/°C or less, more preferably 25 ppm/°C or less. This is because if the coefficient of thermal expansion of the solder is 30 ppm/℃ or less, it can be used as an optical package, and the change in shape due to heat generated when the optical element emits light is suppressed, and damage to the optical package can be more reliably prevented. It is. The lower limit of the coefficient of thermal expansion of the solder included in the solder layer 122 is not particularly limited, but is preferably 0.5 ppm/° C. or more, for example.

The solder that can be suitably used for the solder layer 122 is not particularly limited, and for example, tin (Sn)-germanium (Ge)-nickel (Ni)-based solder, tin (Sn)-antimony ( Examples include one or more types selected from Sb) based solder, gold (Au)-tin (Sn) based solder, tin (Sn)-silver (Ag)-copper (Cu) based solder, and the like.

Note that, for example, in the case of tin-germanium-nickel solder, tin can be contained as a main component. Containing tin as a main component means, for example, that it is the most abundant component in the solder, and it is preferable that the solder contains tin in an amount of 60% by mass or more. The tin content of the solder is, for example, more preferably 85.9% by mass or more, further preferably 87.0% by mass or more, and particularly preferably 88.0% by mass or more.

This is because when the tin content in the solder is 85.9% by mass or more, it is particularly effective in alleviating the difference in thermal expansion between the solder and the components to be joined, and lowering the melting temperature of the solder. .

The upper limit of the tin content in the solder is not particularly limited, but is preferably 99.9% by mass or less, more preferably 99.5% by mass or less, and even more preferably 99.3% by mass or less. Further, the tin-germanium-nickel solder may further contain one or more components selected from iridium, zinc, etc. in addition to tin, germanium, and nickel.

Although the content of each component of the tin-antimony solder is not particularly limited, it is preferable that the content of antimony is 1% by mass or more, for example. This is because antimony has a function of increasing the solidus temperature in tin-antimony solder, and it is preferable to set the antimony content to 1% by mass or more, as this effect can be especially exhibited.

The upper limit of the antimony content is not particularly limited, but is preferably 40% by mass or less, for example. This is because by setting the antimony content to 40% by mass or less, the solidus temperature can be prevented from becoming excessively high, and the solder can be made suitable for mounting electronic components.

The tin-antimony based solder can contain tin. Tin can reduce the difference in thermal expansion between solder and a member to be joined, such as a circuit board or a base metal layer. Furthermore, by containing tin as a main component of the solder, the melting point temperature of the solder can be set to about 230° C., which is the melting point temperature of tin.

The tin-antimony solder can also be composed of antimony and tin, and in this case, the remainder excluding antimony can be composed of tin.

The tin-antimony solder can contain any additional components other than antimony and tin, such as one or more selected from silver (Ag), copper (Cu), and the like. Silver and copper, like antimony, have the function of increasing the solidus temperature of solder. In this case, the remainder other than antimony and optional additive components can be composed of tin.

Although a configuration example of the solder that can be suitably used for the solder layer 122 has been described, as described above, the solder used for the solder layer 122 is not limited to such solder.

In the window material 10 of this embodiment, the residual stress at the interface between the inorganic material base 11 and the bonding layer 12 is preferably 100 MPa or less, more preferably 50 MPa or less.

By setting the residual stress at the interface between the inorganic material base 11 and the bonding layer 12 to 100 MPa or less, the residual stress occurring between the inorganic material base 11 and the bonding layer 12 is sufficiently reduced. This is because cracks and the like can be particularly prevented from occurring when bonded to a circuit board.

Since it is preferable that the residual stress at the interface between the inorganic material base 11 and the bonding layer 12 be small, its lower limit can be set to 0, for example. However, since it is difficult to completely reduce the residual stress at the interface between the inorganic material base 11 and the bonding layer 12 to zero, the residual stress is preferably 10 MPa or more.

The window material of this embodiment has been described above, and in the window material of this embodiment, the bonding layer has a predetermined size. Therefore, residual stress at the interface between the inorganic material base and the bonding layer can be suppressed, and cracks can be suppressed in the window material, specifically, the inorganic material base, when bonded to the circuit board.

The method for manufacturing the window material of this embodiment is not particularly limited, but may include, for example, the following steps.

Substrate preparation process to prepare a substrate of inorganic material.
A bonding layer forming step in which a bonding layer is formed on one surface of an inorganic material base.
The specific operation of the substrate preparation step is not particularly limited, but for example, the inorganic material substrate may be cut to a desired size, or the inorganic material substrate may be processed to have a desired shape. . Note that when an antireflection film is disposed on the surface of an inorganic material substrate, the antireflection film can also be formed in this step. The method of forming the anti-reflection film is not particularly limited, and for example, it can be formed by a dry method or a wet method, and in the case of a dry method, vapor deposition method, sputtering method, ion plating method, etc. The film can be formed by one or more methods selected from the following. In the case of a wet method, the film can be formed by one or more methods selected from a dipping method, a spray coating method, and the like.

The bonding layer forming step can include, for example, a base metal layer forming step of forming a base metal layer and a solder layer forming step.

In the base metal layer forming step, a base metal layer can be formed on one surface of the base of an inorganic material. The method for forming the base metal layer is not particularly limited, and can be arbitrarily selected depending on the type of base metal layer to be formed. For example, the film can be formed by a dry method or a wet method, and in the case of a dry method, the film can be formed by one or more methods selected from vapor deposition, sputtering, ion plating, etc. . In the case of a wet method, the film can be formed by one or more methods selected from electrolytic plating, electroless plating, printing, and the like.

Note that, as described above, the base metal layer can be composed of a plurality of layers, and each layer can be formed by an arbitrary method.

In the solder layer forming step, a solder layer can be formed on one surface of the inorganic material substrate or on the base metal layer. The method of forming the solder layer is not particularly limited, and examples include one or more methods selected from the dipping method, the coating method using a dispenser, the printing method, the laser metal deposition method, the method using a solder wire, etc. .

In the dipping method, solder, which is the raw material for the solder layer, is melted in a solder melting tank, and the part of the member that will form the solder layer, such as the part of the inorganic material base on which the underlying metal layer is placed, is soldered. This method forms a solder layer by dipping it into molten solder in a melting tank.

In the coating method using a dispenser, for example, molten solder is supplied from a dispenser connected to a syringe to a part of an inorganic material base on which a base metal layer is to be formed, on which a solder layer is to be formed. This is a method of forming a solder layer.

The printing method is a method in which a solder layer is formed by printing paste-like solder on a member on which a solder layer is to be formed, such as a portion of an inorganic material base on which a base metal layer is disposed, on which a solder layer is to be formed. Note that heat treatment can be performed after printing if necessary.

In the laser metal deposition method, powdered solder is supplied to the part on which the solder layer will be formed, for example, an inorganic material base on which a base metal layer is placed, and the solder is melted with a laser. This method forms a solder layer by cooling.

The method using a solder wire uses wire-shaped solder, that is, solder processed into a linear shape, and is used, for example, by an automatic soldering robot, to attach a solder layer to a member forming a solder layer, such as an inorganic material base on which a base metal layer is arranged. In this method, molten solder is supplied to the part where the solder is to be formed to form a solder layer.

The method for manufacturing a window material according to the present embodiment can further include an arbitrary step as necessary.

The bonding layer can be formed in a desired shape on one surface 11a of the base 11 made of an inorganic material, as described using FIGS. 1(A) and 1(B).

For this reason, in the method for manufacturing a window material of the present embodiment, a bonding layer is formed by, for example, a base metal layer forming step and a solder layer forming step, and then the bonding layer is patterned into a desired shape. It may also include a conversion step. In the patterning step, for example, a resist corresponding to the pattern to be formed is placed on the exposed surface of the solder layer, and the portions of the solder layer and underlying metal layer that are not covered with the resist are removed by etching or the like. Can be patterned. A resist removal step may also be performed to remove the resist after the patterning step.

In addition, in the case where the base metal layer includes multiple layers, a patterning step is performed after forming a part of the layer included in the base metal layer, and a part of the layer included in the formed base metal layer is formed. can also be patterned. After the patterning step, a resist removal step for removing the resist may be performed, and then the remaining base metal layer may be further formed on the patterned base metal layer.

Further, for example, in the method for manufacturing a window material of the present embodiment, before performing the base metal layer forming step and the solder layer forming step, a resist arrangement is performed in which a resist is placed on a portion where the base metal layer and the solder layer are not formed. It can also have steps. By forming the base metal layer and the solder layer after forming the resist, the base metal layer and the solder layer can be formed only in the portion corresponding to the pattern to be formed. In this case, a resist removing step for removing the resist may be included after the solder layer forming step.

In addition, in order to manufacture multiple window materials at the same time, if multiple bonding layers corresponding to each window material are formed on an inorganic material base (material before cutting) with the size of multiple window materials, it is possible to manufacture multiple window materials at the same time. It is also possible to include a cutting step of cutting the substrate. The cutting method is not particularly limited, and a cutting method suitable for the inorganic material substrate can be employed, such as the cutting method using laser light as described above. Note that if the bonding layers are formed continuously in adjacent window materials, that is, if the bonding layers are arranged on the cutting line, the bonding layers can also be cut in the cutting process.

Note that, after forming the optical package, the inorganic material base and the like can be cut together with the circuit board to separate the optical package into individual pieces.
[Optical package]
Next, a configuration example of the optical package of this embodiment will be described.

The optical package of this embodiment can include the window material described above and a circuit board provided with an optical element.

A configuration example of the optical package of this embodiment will be described using FIG. 3.

FIG. 3 schematically shows a cross-sectional view in a plane parallel to the stacking direction of the window material of the optical package of this embodiment and the circuit board provided with the optical element. Although the window material 10 and the circuit board 31 are shown separately in FIG. 3 so as to be distinguishable from each other, in the optical package 30, both members are joined and integrated.

As described above, the optical package 30 of this embodiment includes the window material 10 described above and the circuit board 31 provided with the optical element 32.

Since the window material 10 has already been explained, the same number as in the case of FIG. 1 is given and the explanation is omitted.

The circuit board 31 is not particularly limited, and various circuit boards including an insulating base material 311 and wiring (not shown) that supplies power to the optical element 32 can be used.

However, in order to improve the airtightness of the space surrounded by the window material 10 and the circuit board 31 when the window material 10 is bonded, the circuit board 31 should have an insulating base material 311 made of ceramics. is preferred.

Here, the ceramic material used for the insulating base material 311 of the circuit board 31 is not particularly limited, but includes, for example, alumina (aluminum oxide, Al ₂ O ₃ ), aluminum nitride (AlN), and LTCC (Low Temperature Co-fired Ceramics). ), and the like.

Although the shape of the insulating base material 311 of the circuit board 31 is not particularly limited, in the case of an optical package 30, the optical element 32 is arranged between the inorganic material base 11, the insulating base material 311, and a joint portion to be described later. It is preferable that the structure is such that a closed space can be formed in the portion where the For this reason, it is preferable that the insulating base material 311 has an opening in the center of its upper surface 311a, and a recess 311A that is a non-through hole including the opening. Note that the upper surface of the insulating base material 311 is a surface that faces the window material 10 when used as an optical package, and can also be said to be a surface that is bonded to the window material 10.

The wall portion 311B surrounding the recessed portion 311A supports both the bonding layer 12 of the window material 10 and a base metal layer for a circuit board, which will be described later, when used as an optical package. It can have a shape corresponding to the underlying metal layer.

Furthermore, the circuit board 31 can have a circuit board base metal layer 312 on the upper surface 311a of the insulating base material 311 and on the upper surface of the wall portion 311B.

The circuit board base metal layer 312 can have the function of increasing the adhesion between the insulating base material 311 of the circuit board 31 and the window material 10. Although the specific structure of the circuit board base metal layer 312 is not particularly limited, for example, from the insulating base material 311 side of the circuit board 31, the first circuit board base metal layer 312A, the second circuit board base metal layer 312B , the third circuit board base metal layer 312C may be laminated in this order. Although an example is shown here in which the circuit board base metal layer 312 is composed of three layers, it is not limited to this form, and may be composed of one layer, two layers, or four or more layers.

When the circuit board base metal layer 312 is composed of three layers as described above, for example, the first circuit board base metal layer 312A is made of the same metal as the metal used to form the wiring (circuit) in the circuit board 31. It is preferable to configure. For example, the first circuit board base metal layer 312A can be a layer containing one or more metals selected from copper (Cu), silver (Ag), and tungsten (W). The first circuit board base metal layer 312A can also be a layer made of one or more metals selected from copper (Cu), silver (Ag), and tungsten (W). Note that even in this case, it is not excluded that the first circuit board base metal layer 312A contains unavoidable impurities.

The second circuit board base metal layer 312B can be a layer that prevents the third circuit board base metal layer 312C and the first circuit board base metal layer 312A, which will be described later, from being alloyed, for example, nickel. (Ni). The second circuit board base metal layer 312B can also be a layer made of nickel (Ni). Note that even in this case, it is not excluded that the second circuit board base metal layer 312B contains unavoidable impurities.

The third circuit board base metal layer 312C can be a layer for preventing the second circuit board base metal layer 312B from oxidizing, and can be a layer containing gold (Au), for example. The third circuit board base metal layer 312C can also be a layer made of gold (Au). Note that even in this case, it is not excluded that the third circuit board base metal layer 312C contains unavoidable impurities.

The thickness of each layer constituting the circuit board base metal layer 312 is not particularly limited and can be arbitrarily selected.

The thickness of the first circuit board base metal layer 312A is preferably 1 μm or more, for example. The upper limit of the thickness of the first circuit board base metal layer 312A is also not particularly limited, but from the viewpoint of sufficiently reducing costs, it is preferably 20 μm or less.

The thickness of the second circuit board base metal layer 312B is preferably 1 μm or more from the viewpoint of particularly suppressing alloying between the first circuit board base metal layer 312A and the third circuit board base metal layer 312C. The upper limit of the thickness of the second circuit board base metal layer 312B is also not particularly limited, but from the viewpoint of sufficiently reducing costs, it is preferably 20 μm or less.

The thickness of the third circuit board base metal layer 312C is preferably 0.03 μm or more from the viewpoint of particularly preventing oxidation of other circuit board base metal layers. The upper limit of the thickness of the third circuit board base metal layer 312C is also not particularly limited, but from the viewpoint of sufficiently reducing costs, it is preferably 2.0 μm or less, and more preferably 0.5 μm or less.

The shape of the circuit board base metal layer 312 is not particularly limited either, but in the case of an optical package 30, it forms a bonding part 33, which will be described later, together with the bonding layer 12 of the window material 10. Preferably, it has a corresponding shape. Specifically, the bonding layer 12 of the window material 10 and the circuit board base metal layer 312 have a cross-sectional shape in a plane perpendicular to the stacking direction (vertical direction in FIG. 3) of both members when forming an optical package. Preferably, they have the same shape.

The method for forming the circuit board base metal layer 312 is not particularly limited, and can be arbitrarily selected depending on, for example, the type of the circuit board base metal layer 312 to be formed. For example, the film can be formed by a dry method or a wet method, and in the case of a dry method, the film can be formed by one or more methods selected from vapor deposition, sputtering, ion plating, etc. . In the case of a wet method, the film can be formed by one or more methods selected from electrolytic plating, electroless plating, printing, and the like.

Note that, as described above, the base metal layer for a circuit board can be composed of a plurality of layers, and each layer can be formed by an arbitrary method.

The optical element 32 disposed on the circuit board 31 is not particularly limited, and for example, a light emitting element such as a light emitting diode, a light receiving element, etc. can be used.

Note that when the optical element 32 is a light emitting element, the wavelength range of light emitted by the light emitting element is not particularly limited. For this reason, a light emitting element that emits light in an arbitrary wavelength range selected from, for example, the range from ultraviolet light to infrared light, that is, for example, light in an arbitrary wavelength range selected from the wavelength range of 200 nm or more and 1 mm or less, is used. Can be used.

However, according to the optical package of this embodiment, the base of the window material, which is a member that transmits light from the light emitting element, is not a transparent resin base but the base 11 of an inorganic material. Therefore, compared to the case where a transparent resin base is used as the base of the window material, the hermetic sealability can be improved, and furthermore, the deterioration of the window material due to light from the light emitting element can be suppressed. Therefore, when the optical element is a light-emitting element, the optical package of this embodiment is particularly effective when using a light-emitting element that particularly requires airtightness or a light-emitting element that emits light whose resin easily deteriorates. It is preferable to be able to demonstrate the following. Examples of light-emitting elements that particularly require airtightness include light-emitting elements that emit UV-C, which is light in a wavelength range of 200 nm or more and 280 nm or less. Examples of light-emitting elements that emit light that can easily cause resin deterioration include light-emitting elements that emit high-output light such as lasers. Therefore, when the optical element 32 is a light emitting element, a light emitting element that emits UV-C, a laser, or the like can be preferably used from the viewpoint of exhibiting particularly high effects.

Then, the inorganic material base 11 of the window material 10 and the insulating base material 311 of the circuit board 31 can be joined by the joint portion 33. As shown in FIG. 3, the bonding portion 33 can include the bonding layer 12 of the window material 10 and the circuit board base metal layer 312 of the circuit board 31. Note that the bonding portion 33 can also be configured from the bonding layer 12 and the circuit board base metal layer 312.

According to the optical package of this embodiment described above, since the window material described above is used, when the window material and the circuit board provided with the optical element are bonded, the window material, specifically, It is possible to suppress the occurrence of cracks in the inorganic material base. Therefore, it is possible to obtain an optical package that can be produced with high yield.

The method for manufacturing the optical package of this embodiment is not particularly limited, and can be manufactured by any method.

The method for manufacturing an optical package of this embodiment can include, for example, the following steps.

A circuit board preparation process for preparing a circuit board with optical elements.

A bonding process in which the window material is placed on the circuit board and the window material and the circuit board are bonded together.

In the circuit board preparation step, an optical element can be placed on a circuit board manufactured by a conventional method to prepare a circuit board provided with an optical element. In addition, when dividing into pieces after the completion of the bonding process, in the circuit board preparation process, it is possible to prepare a circuit board in which a plurality of circuit boards are integrated before cutting.

Then, in the bonding step, the window material can be placed on the circuit board, and the window material and the circuit board can be bonded. Although the specific method of bonding is not particularly limited, for example, first, in the optical package 30 shown in FIG. They can be stacked so that they touch each other. For example, the solder layer 122 is heated while being pressed from the other surface 11b of the inorganic material base 11 of the window material 10 toward the circuit board 31 side, that is, along the block arrow B in the figure. The window material 10 and the circuit board 31 can be joined by melting at least a portion of the window material 10 and then cooling it.

In the bonding process, the oxide film present on the surface of the lower surface 12a of the bonding layer 12 melts into the solder layer 122 melted by heating, and the melted solder layer 122 is applied to the upper surface 312a of the circuit board base metal layer 312. It is preferable to be thin enough so that the two can come in contact with each other. Although the specific thickness of the oxide film is not limited, the thickness of the oxide film is preferably 10 nm or less, more preferably 5 nm or less.

Note that the method of pressing the inorganic material base 11 is not particularly limited, and for example, a method using a pressing means having a pressing member in contact with the inorganic material base 11 and an elastic body such as a spring that applies pressure to the pressing member, Examples include a method using a weight.

In the optical package obtained after the bonding process, if a predetermined atmosphere is to be maintained in the area sealed between the window material 10 and the circuit board 31, the atmosphere during heat treatment may be set to the predetermined atmosphere. preferable. For example, the atmosphere may be selected from an air atmosphere, a vacuum atmosphere, an inert atmosphere, and the like. The inert atmosphere can be an atmosphere containing one or more gases selected from nitrogen, helium, argon, and the like.

In the bonding step, the conditions for heat treatment are not particularly limited, and for example, it is preferable to heat to a temperature higher than the melting temperature of the solder in the solder layer. However, if heating is performed rapidly, thermal stress is applied to the inorganic material base, which may cause cracks, etc., so first heat the substrate to a first heat treatment temperature of 50°C or higher, which is below the melting point of the solder in the solder layer. , it is preferable to hold the first heat treatment temperature for a certain period of time. The holding time at the first heat treatment temperature is not particularly limited, but is preferably 30 seconds or more, and more preferably 60 seconds or more, for example. However, from the viewpoint of productivity, the holding time at the first heat treatment temperature is preferably 600 seconds or less.

After holding the first heat treatment temperature for a certain period of time, the temperature is preferably further increased to a second heat treatment temperature that is higher than the melting point of the solder in the solder layer. In addition, the second heat treatment temperature is preferably 20° C. or higher than the melting point of the solder in order to sufficiently bond the window material 10 and the circuit board 31, and if the second heat treatment temperature is too high, Since the heated optical element may be damaged by heat, the second heat treatment temperature is preferably 300° C. or lower, for example. The time for holding at the second heat treatment temperature is not particularly limited, but is preferably 20 seconds or more in order to sufficiently bond the window material 10 and the circuit board 31. However, in order to more reliably suppress the adverse effects of heat on the optical element, the time for holding at the second heat treatment temperature is preferably 1 minute or less.

After the heat treatment at the second heat treatment temperature, the bonding process can be completed by cooling to room temperature, for example, 23°C.

The optical package manufacturing method of this embodiment can include any steps as necessary. For example, in the case where a circuit board that is made up of a plurality of integrated circuit boards and is not separated into pieces is subjected to a bonding process, a cutting process may be included. The cutting method used in the cutting step is not particularly limited, and any arbitrary method can be used. The circuit board and the window material can also be cut into individual pieces by cutting the circuit board and the window material at the same time using the cutting method using laser light, which has already been described in the explanation regarding the window material. It is also possible to combine multiple cutting methods.

The present invention will be specifically explained below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples, and the embodiments can be modified as appropriate as long as the effects of the present invention are achieved. .

First, a method for evaluating optical packages produced in the following Examples and Comparative Examples will be described.
<Evaluation method>
[Crack evaluation]
The optical packages produced in the following Examples and Comparative Examples were examined using an optical microscope (SMZ900 manufactured by Nikon) at a magnification of 10 times to examine the connection between the inorganic material base 11 and the joint portion 33 through the inorganic material base 11. The interface was observed under magnification, the state of the inorganic material base 11 was confirmed, and cracking was evaluated under the following conditions.

○: There are no breaks or cracks in the contact area between the inorganic material and the base body.

×: There are cracks or cracks on the contact surface between the inorganic material base and the joint.

〇 was considered a pass.
[Airtightness evaluation]
A helium leak test was conducted using a bombing method under the conditions described in JIS Z 2331 (2006) for the optical packages produced in the following Examples and Comparative Examples, and the airtightness was evaluated under the following conditions.

O: Helium leak rate is 4.9×10 ⁻⁹ Pa·m ³ /sec or less ×: Helium leak rate is greater than 4.9×10 ⁻⁹ Pa·m ³ /sec.
[Example 1]
A window material and an optical package having the structure shown in FIG. 3 were manufactured, and the above-mentioned crack evaluation and airtightness evaluation were performed.

A quartz plate (manufactured by AGC, AQ, length 8.5 mm x width 8.5 mm x thickness 0.5 mm) was prepared as the inorganic material base 11 (substrate preparation step). Note that the quartz plate prepared as the inorganic material base 11 had a coefficient of thermal expansion of 0.6 ppm/°C between 20°C and 200°C.

A bonding layer 12 was formed on one surface 11a of the base 11 made of an inorganic material by the following procedure (bonding layer forming step).

A chromium (Cr) layer was formed as the first base metal layer 121A, and a copper (Cu) layer was formed as the second base metal layer 121B (base metal layer forming step).

Next, a resist is applied to the entire surface of the second base metal layer 121B opposite to the surface facing the first base metal layer 121A, that is, the exposed surface, and then the resist is exposed to ultraviolet light, By further developing, a patterned resist was placed. The patterned resist had a square shape in a cross section taken along a plane parallel to one surface 11a of the base 11 made of an inorganic material, and had a square opening in the center.

Then, the portions of the first base metal layer 121A and the second base metal layer 121B that were not covered with the resist were etched with an etching solution to perform patterning (patterning step). Thereafter, the resist was removed (resist removal step).

Next, a nickel (Ni) layer was formed as a third base metal layer 121C by electroless Ni plating on the patterned first base metal layer 121A and second base metal layer 121B. As a result, a patterned base metal layer 121 including the first base metal layer 121A, the second base metal layer 121B, and the third base metal layer 121C was formed. The thickness of the first metal base layer 121A was 0.2 μm, the thickness of the second metal base layer 121B was 0.6 μm, and the thickness of the third metal base layer 121C was 0.8 μm.

Next, a solder layer 122 was formed on the base metal layer 121 (solder layer forming step). The solder used for the solder layer 122 was manufactured in advance according to the following procedure.

The components contained in the solder are weighed and mixed so that Sn is 97% by mass, Ge is 2% by mass, and Ni is 1% by mass, and melted to temporarily create a raw material alloy. After melting this raw material alloy, it was poured into a mold to produce solder.

The Young's modulus of the obtained solder was calculated from the tensile test results and was confirmed to be 20 GPa. Regarding the tensile test, a test piece of JIS No. 14A was tested at a tensile speed of 3 mm/min using a tensile tester (Autograph AGX-100kN manufactured by Shimadzu Corporation).

Note that the difference between the thermal expansion coefficient of the inorganic material base 11 and the thermal expansion coefficient of the solder used in the solder layer at 20° C. or higher and 200° C. or lower was 7.0 ppm/° C.

The solder, which is the raw material for the solder layer 122, is melted in a solder melting tank, and the portion of the inorganic material base 11 on which the base metal layer 121 described above is disposed, which will form the solder layer 122, is melted in the solder melting tank. The solder layer 122 was formed by dipping it in the solder and cooling it (solder layer forming step). Note that, as shown in FIG. 3, the solder layer 122 was formed on the surface of the third base metal layer 121C opposite to the surface facing the second base metal layer 121B.

The solder layer 122 was formed so that the thickness T of the bonding layer 12 was 30 μm. Furthermore, the width W of the bonding layer 12 obtained as described above was 0.3 mm.

Next, a circuit board was prepared according to the following procedure. (Circuit board preparation process)
Further, as the insulating base material 311 of the circuit board 31, an alumina (Al ₂ O ₃ ) base (8.5 mm long x 8.5 mm wide x 0.8 mm thick) was prepared.

The upper surface 311a of the insulating base material 311 has a rectangular opening in the center thereof, and has a recess 311A that is a non-through hole including the opening. The size of the recess 311A was 2.5 mm long x 2.5 mm wide x 0.4 mm deep. Although the optical element 32 can be placed in the recess 311A, since the optical element is not required in the evaluation of this example, the package was manufactured without installing the optical element. However, it has been confirmed that similar evaluation results can be obtained even when optical elements such as light emitting diodes are arranged.

Then, the circuit board 31 has a circuit board base metal layer 312 on the upper surface 311a of the insulating base material 311 so as to surround the opening of the recess 311A and along the outer periphery of the upper surface 311a of the insulating base material 311. have.

As the circuit board base metal layer 312, the first circuit board base metal layer 312A, the second circuit board base metal layer 312B, and the third circuit board base metal layer 312C are laminated in this order from the insulating base material 311 side. It has a layered structure.

The first circuit board base metal layer 312A is a copper (Cu) layer with a thickness of 1.0 μm, the second circuit board base metal layer 312B is a nickel (Ni) layer with a thickness of 2 μm, and the third circuit board A gold (Au) layer having a thickness of 0.3 μm was formed as the base metal layer 312C.

The circuit board base metal layer 312 had a shape corresponding to the base metal layer 121 provided on the base 11 of an inorganic material. Specifically, the cross-sectional shape in a plane perpendicular to the lamination direction (vertical direction in FIG. 3) of the bonding layer 12 provided on the inorganic material base 11 and the circuit board base metal layer 312 is such that the bonding layer 12 and It was configured to have the same shape as the circuit board base metal layer 312. (Joining process)
The circuit board 31 and the window material 10 were stacked so that the lower surface of the solder layer 122 of the bonding layer 12 provided on the inorganic material base 11 was in direct contact with the upper surface of the circuit board base metal layer 312. Then, a weight is placed on the other surface 11b of the base 11 made of an inorganic material, a load of 90 gf is applied, and while pressing along the block arrow B in FIG. At least a portion of the layer 122 was melted and then cooled to join (joining step).

Through the above steps, the window material and the circuit board 31 were bonded to produce an optical package.

The above-mentioned evaluation was performed on the optical package which was the obtained joined body. The results are shown in Table 1.
[Example 2 to Example 5, Comparative Example 1 to Comparative Example 4]
In the bonding layer forming step, an experiment was conducted in the same manner as in Example 1, except that the width W and thickness T of the bonding layer 12 were set to the values shown in Table 1. The evaluation results are shown in Table 1.

表１に示した結果によると、接合層の幅が０．２ｍｍ以上２ｍｍ以下であり、厚さが１５μｍより厚く１００μｍ以下である実施例１～実施例５の窓材を用いた光学パッケージにおいては、割れ評価、及び気密性評価の結果が〇となっていることが確認できた。すなわち、カバーに割れが生じることを抑制した窓材、光学パッケージになっていることを確認できた。

According to the results shown in Table 1, in optical packages using the window materials of Examples 1 to 5, in which the width of the bonding layer is 0.2 mm or more and 2 mm or less, and the thickness is more than 15 μm and 100 μm or less, It was confirmed that the results of , crack evaluation, and airtightness evaluation were ○. In other words, we were able to confirm that the window material and optical package suppressed the occurrence of cracks in the cover.

On the other hand, in Comparative Examples 1 to 4 in which the width and thickness of the bonding layer did not satisfy the above requirements, it was confirmed that cracks occurred and the airtightness was not sufficient.

Although the window material and the optical package have been described in the embodiments and the like above, the present invention is not limited to the above embodiments and the like. Various modifications and changes are possible within the scope of the gist of the invention as set forth in the claims.

This application claims priority based on Japanese Patent Application No. 2018-190370 filed with the Japan Patent Office on October 5, 2018, and the entire contents of Japanese Patent Application No. 2018-190370 are included in this international application. I will use it.

10 window material 11 base of inorganic material 12 bonding layer 122 solder layer 30 optical package 31 circuit board 311 insulating base material 32 optical element

Claims (5)

A window material for an optical package equipped with an optical element,
a base of inorganic material;
a bonding layer disposed on one surface of the inorganic material base along the outer periphery of the inorganic material base;
The width of the bonding layer is 0.2 mm or more and 2 mm or less,
The thickness of the bonding layer is greater than 15 μm and less than 100 μm,
The bonding layer has a solder layer,
The solder contained in the solder layer is tin-germanium-nickel based solder,
A window material in which the difference between the coefficient of thermal expansion of the base of the inorganic material and the coefficient of thermal expansion of the solder at a temperature of 20°C or more and 200°C or less is 30 ppm/°C or less . The window material according to claim 1, wherein the solder included in the solder layer has a Young 's modulus E of 50 GPa or less. The window material according to claim 1 or 2, wherein the residual stress at the interface between the inorganic material base and the bonding layer is 100 MPa or less. An optical package comprising the window material according to any one of claims 1 to 3 and a circuit board provided with an optical element. 5. The optical package according to claim 4 , wherein the circuit board has an insulating base material made of ceramic.

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