Glass cap, glass cap manufacturing method, and method for manufacturing LED device including glass cap

Abstract

To solve a problem of cracks occurring in a glass cap when the glass cap is soldered to a package.SOLUTION: A glass cap 10A is bonded to a package, and includes at least a light-transmitting portion 12 formed from a glass material, and a connecting portion 13 that is bonded to the light-transmitting portion 12 and also to a package 20A, connecting the light-transmitting portion 12 and the package, and the connecting portion 13 is formed from a material that has a thermal expansion coefficient greater than that of the glass material that forms the light-transmitting portion 12 and a thermal expansion coefficient smaller than that of the material that forms the package.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a glass cap to be bonded to a package, a method for manufacturing the glass cap, and a method for manufacturing an LED device including the glass cap. [Background technology]

[0002] 2. Description of the Related Art Conventionally, LED devices have been known that are configured by bonding a glass cap to a package in which an LED chip, which is a light emitter, is mounted.

[0003] The size of the glass cap used in an LED device is, for example, on the order of several μm to several mm, and quartz glass is preferably used. Quartz glass has excellent light transmittance and a small thermal expansion coefficient. Therefore, even if there is a change in the external environment (temperature increase), its optical properties do not change and the desired performance can be maintained, making it a suitable material for the glass cap used in an LED device (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7344523 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventionally, when an LED device is constructed by joining a glass cap to a package in which an LED chip is mounted, a glass cap made of a glass material with high transmittance (for example, quartz glass) is soldered to a package made of a material such as ceramic. For example, the ceramics that form the package in which the LED chip is mounted are made of alumina or alumina nitride, and their thermal expansion coefficients (10 -6 / K) is 4.5 to 8.0, while the thermal expansion coefficient of the quartz glass that forms the glass cap is only 0.5, which is small. Therefore, when the glass cap and package are heated during soldering, a difference in thermal expansion occurs between the ceramic that forms the package and the glass material (quartz glass) that forms the glass cap, which results in a problem in that a load is applied to the glass cap, which may cause it to crack.

[0006] The present invention has been made in consideration of the above facts, and its main technical objective is to provide a glass cap that can solve the problem of cracks occurring in the glass cap when the glass cap is soldered to the package, a method for manufacturing the glass cap, and a method for manufacturing an LED device that includes the glass cap. [Means for solving the problem]

[0007] In order to solve the above-mentioned main technical problem, the present invention provides a glass cap to be bonded to a package, the glass cap including at least a light-transmitting portion formed of a glass material and a connecting portion that is bonded to the light-transmitting portion and to the package to connect the light-transmitting portion and the package, the connecting portion being formed of a material that has a thermal expansion coefficient larger than that of the glass material forming the light-transmitting portion and smaller than that of the material forming the package. Note that the glass cap of the present invention includes the glass cap in a state after being bonded to the package and the glass cap in a state before being bonded to the package.

[0008] It is preferable that the glass material forming the light-transmitting portion is quartz glass, the material forming the package is ceramic, and the material forming the connection portion is glass. It is also preferable that the light-transmitting portion has a flat, hemispherical, hemispherical shape with a flat rib connected to its outer periphery, or hollow dome shape with a flat rib connected to its outer periphery.

[0009] Furthermore, according to the present invention, there is provided a glass cap manufacturing method for manufacturing the above-mentioned glass cap, which includes a light-transmitting portion joining step for joining the light-transmitting portion and the connecting portion by room temperature joining or laser joining.

[0010] Furthermore, according to the present invention, there is provided a method for manufacturing an LED device including the above-mentioned glass cap, comprising: a light-transmitting portion joining step of joining the light-transmitting portion and the connecting portion by room temperature bonding or laser bonding; and a package connecting step of connecting the connecting portion to the package in which an LED chip is mounted by solder bonding. [Effects of the Invention]

[0011] The glass cap of the present invention includes at least a light-transmitting portion formed from a glass material, and a connecting portion that is bonded to the light-transmitting portion and also to the package, thereby connecting the light-transmitting portion and the package.The connecting portion is formed from a material that has a larger thermal expansion coefficient than the glass material that forms the light-transmitting portion and a smaller thermal expansion coefficient than the material that forms the package, thereby eliminating the problem of cracks occurring in the glass cap when the glass cap and package are joined by soldering.

[0012] Furthermore, the glass cap manufacturing method of the present invention includes a light-transmitting portion joining step in which the light-transmitting portion and the connecting portion are joined by room temperature bonding or laser bonding, and therefore the above-mentioned glass cap can be suitably manufactured.

[0013] Furthermore, the LED device manufacturing method of the present invention includes a light-transmitting portion joining process in which the light-transmitting portion and the connecting portion are joined by room temperature bonding or laser bonding, and a package connecting process in which the connecting portion is connected by solder bonding to the package in which the LED chip is mounted, so that the LED device including the above-mentioned glass cap can be suitably manufactured. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2(a) is an exploded perspective view of the glass cap of the first embodiment, and FIG. 2(b) is a central vertical cross-sectional view of the glass cap shown in FIG. [Figure 2] FIG. 1A is an exploded perspective view of an LED device according to a first embodiment, and FIG. 1B is a central longitudinal sectional view of the LED device shown in FIG. [Figure 3] 10A and 10B are exploded perspective views of a glass cap according to a second embodiment, and FIG. 10B is a central vertical cross-sectional view of the glass cap shown in FIG. [Figure 4] FIG. 10(a) is an exploded perspective view of an LED device according to a second embodiment, and FIG. 10(b) is a central longitudinal cross-sectional view of the LED device shown in FIG. [Figure 5] 10A and 10B are exploded perspective views of a glass cap according to a third embodiment, and FIG. 10B is a central vertical cross-sectional view of the glass cap shown in FIG. [Figure 6] FIG. 10(a) is an exploded perspective view of an LED device according to a third embodiment, and FIG. 10(b) is a central vertical cross-sectional view of the LED device shown in FIG. [Figure 7] 10(b) is an exploded perspective view of the glass cap of the fourth embodiment, and FIG. 10(a) is a central vertical cross-sectional view of the glass cap of FIG. [Figure 8] FIG. 10(a) is an exploded perspective view of an LED device according to a fourth embodiment, and FIG. 10(b) is a central longitudinal sectional view of the LED device shown in FIG. [Figure 9] 10A is a perspective view showing a modified example of the light transmitting portion, and FIG. 10B is a central vertical cross-sectional view of the light transmitting portion shown in FIG. [Figure 10] 10(a) is a perspective view showing yet another modified example of the light transmitting portion, and FIG. 10(b) is a central vertical cross-sectional view of the light transmitting portion shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a glass cap, a method for manufacturing a glass cap, and a method for manufacturing an LED device including a glass cap according to the present invention will be described in more detail with reference to the accompanying drawings.

[0016] (First Example) 1(a) and (b) show a glass cap 10A of the first embodiment. The glass cap 10A of the present embodiment includes a light-transmitting portion 12 and a connecting portion 13 joined to the light-transmitting portion 12. The connecting portion 13 is joined to a package 20A (see FIG. 2(a)) described below, and connects the light-transmitting portion 12 and the package 20A.

[0017] The light-transmitting portion 12 shown in FIG. 1(a) is formed of a glass material, and in this embodiment, is formed of quartz glass. The light-transmitting portion 12 is a so-called microlens having a hemispherical lens portion 121 and a flat rib 122 with the lens portion 121 formed in the center and connected to the outer periphery of the hemispherical lens portion 121. The connecting portion 13 employs a type of glass different from the glass material (quartz glass) forming the light-transmitting portion 12. The connecting portion 13 is formed of glass having a thermal expansion coefficient larger than that of the quartz glass forming the light-transmitting portion 12 (0.5) but smaller than that of the ceramic (e.g., alumina or alumina nitride) forming the package 20A (described later) (4.5 to 8.0), such as borosilicate glass (thermal expansion coefficient 3.2) or alkali-free glass (thermal expansion coefficient 3.17).

[0018] The glass cap 10A is manufactured, for example, by the glass cap manufacturing method described below. First, the light-transmitting portion 12 is prepared, and the connecting portion 13 to be joined to the light-transmitting portion 12 is also prepared. The light-transmitting portion 12 can be manufactured by a conventional method, such as the method described in Patent Document 1. As shown in FIG. 1(a), the connecting portion 13 is a cylindrical member with a square cross section, having an opening shaped along the outer edge of the rib 122 of the light-transmitting portion 12. Next, a light-transmitting portion joining step is performed to join the light-transmitting portion 12 and the connecting portion 13 together. The light-transmitting portion 12 and the connecting portion 13 can be joined together by, for example, room-temperature bonding. When joining by room-temperature bonding, at least the outer edge of the lower surface of the rib 122 of the light-transmitting portion 12 and the upper surface 13a of the connecting portion 13 are smoothed to activate the surfaces, and then the two are directly contacted (optically contacted) to be integrated. As a result, the glass cap 10A can be bonded at the bonding surface R1, as can be seen from the central vertical cross-sectional view of the glass cap 10A shown in Figure 1(b). In this first embodiment, an annealing process involving low-temperature heating at about 200°C is further performed to remove distortion from both components and further stabilize the bond at the bonding surface R1. In this way, the glass cap 10A is manufactured, and the glass cap manufacturing method in this embodiment is completed.

[0019] The glass cap manufacturing method of the present invention is not limited to the above-described embodiment. In particular, in the light-transmitting portion joining step of joining the light-transmitting portion 12 and the connecting portion 13 at the joining surface R1, instead of the room-temperature joining described above, a laser beam may be focused and irradiated onto the mating surface between the outer edge of the lower surface of the rib 122 of the light-transmitting portion 12 and the upper surface 13a of the connecting portion 13 to melt and integrate a portion of the mating surface. The laser beam to be irradiated in this step is preferably a laser beam having a wavelength that is highly transparent to the glass forming the light-transmitting portion 12 and the connecting portion 13, and a pulse laser having a pulse width on the order of femtoseconds. Furthermore, the laser beam is preferably irradiated from the lower surface 13b of the connecting portion 13 toward the mating surface between the light-transmitting portion 12 and the upper surface 13a of the connecting portion 13, with an output sufficient to melt the mating surface and form the joining surface R1.

[0020] Once the glass cap 10A has been manufactured using the glass cap manufacturing method described above, an LED device P1 (see FIG. 2) including the glass cap 10A can be manufactured using the LED device manufacturing method described below.

[0021] 2(a) shows the glass cap 10A and the package 20A to which the glass cap 10A is bonded. As shown in the figure, the package 20A is a box-shaped package including an outer periphery 21, a bottom 22 surrounded by the outer periphery 21, and an LED chip 23 as a light emitter mounted in the center of the bottom 22. The outer periphery 21 and the bottom 22 are made of ceramics, such as alumina or alumina nitride.

[0022] The glass cap 10A and the package 20A are joined by soldering. While the specific soldering method is not particularly limited, for example, in the package 20A shown in FIG. 2(a), paste solder 30 is applied to the upper surface 21a of the outer periphery 21 to which the glass cap 10A is joined. The lower surface 13b of the connection portion 13 of the glass cap 10A is then aligned with the upper surface 21a of the package 20A and placed in a reflow furnace for heating. This solders the connection portion 13 of the glass cap 10A to the package 20A, forming a connection portion R2 as can be seen from the central vertical cross-sectional view of the LED device P1 shown in FIG. 2(b) (package joining process). This completes the LED device P1 and the manufacturing method for the LED device of this example.

[0023] According to the first embodiment described above, the glass cap 10A includes at least the light-transmitting portion 12 and the connecting portion 13 that connects the light-transmitting portion 12 to the ceramic that forms the package 20A, and the connecting portion 13 is made of glass that has a thermal expansion coefficient larger than that of the glass material that forms the light-transmitting portion 12 and smaller than that of the ceramic that forms the package 20A. This avoids the problem of the glass cap 10A cracking due to the difference in thermal expansion when heated in the package connection step.

[0024] The present invention is not limited to the first embodiment described above, but includes various modifications. Other embodiments will be described below with reference to FIGS.

[0025] (Second Example) A second embodiment of the present invention will be described with reference to FIGS. 3 and 4. FIGS. 3(a) and 3(b) show a glass cap 10B constructed according to the present invention. The glass cap 10B of this embodiment is configured to be bonded to a flat package 20B shown in FIG. 4(a) and includes a light-transmitting portion 12 and a connecting portion 14 bonded to the outer edge of the light-transmitting portion 12. The light-transmitting portion 12 has the same configuration as the light-transmitting portion 12 of the first embodiment, and a detailed description thereof will be omitted. The connecting portion 14 is bonded to the package 20B to connect the light-transmitting portion 12 and the package 20B. The connecting portion 14 has the same configuration as the connecting portion 13, except that it has a larger height than the connecting portion 13, so that it can be bonded to the flat package 20B. That is, the light-transmitting portion 12 shown in FIG. 3(a) includes a lens portion 121 and a rib 122 with the lens portion 121 formed in the center, and is a so-called microlens integrally formed from a glass material (quartz glass). The connecting portion 14 is cylindrical with a substantially rectangular cross section, has an upper surface 14a and a lower surface 14b, and employs glass having a thermal expansion coefficient greater than that of the glass material forming the light transmitting portion 12 and smaller than that (4.5 to 8.0) of the ceramic (e.g., alumina or alumina nitride) forming the package 20B (described later). The connecting portion 14 is formed from, for example, borosilicate glass (thermal expansion coefficient 3.2) or alkali-free glass (thermal expansion coefficient 3.17).

[0026] In carrying out the glass cap manufacturing method according to this embodiment, first, the light-transmitting portion 12 shown in FIG. 3(a) is prepared, and the connecting portion 14 to be bonded to the light-transmitting portion 12 is prepared. Next, a light-transmitting portion bonding step is carried out in which the light-transmitting portion 12 and the connecting portion 14 are bonded together to form an integrated unit. The light-transmitting portion 12 and the connecting portion 14 are bonded, for example, by room-temperature bonding or laser bonding as described in the first embodiment above (detailed description will be omitted). As a result, as shown in FIG. 3(a), the light-transmitting portion 12 is bonded to the upper surface 14a of the connecting portion 14, and a bonding surface R1 is formed, as can be seen from FIG. 3(b), which shows a central vertical cross-sectional view of the glass cap 10B. Thus, the glass cap 10B is manufactured, and the glass cap manufacturing method according to the second embodiment is completed.

[0027] Once the glass cap 10B has been manufactured by the above-described glass cap manufacturing method, the LED device P2 shown in FIG. 4 can be manufactured by the LED device manufacturing method described below.

[0028] 4(a) shows a package 20B which, together with the glass cap 10B, constitutes the LED device P2. As shown, the package 20B includes a flat substrate 24 and an LED chip 23 as a light emitter mounted in the center of the substrate 24. The substrate 24 is made of, for example, ceramics, more specifically, alumina or alumina nitride.

[0029] The glass cap 10B and the package 20B are joined by soldering. The specific soldering method can be performed using procedures similar to those of the package joining process described above in the first embodiment. Specifically, in the package 20B shown in FIG. 4(a), paste solder 30 is applied to the outer periphery of the substrate 24 to which the glass cap 10B is to be joined. Next, the underside 14b of the connection portion 14 of the glass cap 10B is positioned on the outer periphery of the substrate 24 to which the paste solder 30 has been applied, and the package is placed in a reflow furnace for heating. As can be seen from FIG. 4(b), which shows a central vertical cross-sectional view of the LED device P2, the mating surfaces of the glass cap 10B and the package 20B are solder-joined and integrated at the joint R2, completing the LED device P2 and the manufacturing method for the LED device of this embodiment.

[0030] In the second embodiment described above, the connection portion 14 is also formed from glass having a thermal expansion coefficient greater than that of the glass material forming the light-transmitting portion 12 and less than that of the ceramic forming the substrate 24, thereby avoiding the problem of the glass cap 10B cracking due to the difference in thermal expansion during heating when the package connection process is carried out to manufacture the LED device P2.

[0031] (Third Example) A third embodiment of the present invention will be described with reference to FIGS. 5 and 6. FIGS. 5(a) and 5(b) show a glass cap 10C according to this embodiment. The illustrated glass cap 10C, like the one employed in the first embodiment, is bonded to a box-shaped package 20A shown in FIG. 6(a) and includes a light-transmitting portion 15 and a connecting portion 16 bonded to the outer edge of the light-transmitting portion 15. As shown in FIG. 5(a), the light-transmitting portion 15 is formed solely from a hemispherical lens and is made of a glass material (quartz glass). The connecting portion 16 is a plate-like member having a front surface 16a and a back surface 16b, and has an opening 16c formed in the center to which the underside of the illustrated light-transmitting portion 15 is bonded.

[0032] The connecting portion 16 is bonded to the package 20A to connect the light transmitting portion 15 and the package 20A. The connecting portion 16 is made of glass having a thermal expansion coefficient larger than that of the glass material forming the light transmitting portion 15 and smaller than that of the ceramic (e.g., alumina or alumina nitride) of the package 20A shown in Fig. 6(a), and is formed from, for example, borosilicate glass (thermal expansion coefficient 3.2) or non-alkali glass (thermal expansion coefficient 3.17).

[0033] When manufacturing the glass cap 10C, first, the light-transmitting portion 15 and the connecting portion 16 to be bonded to the light-transmitting portion 15 are prepared. As shown in FIG. 5(a), the opening 16c of the connecting portion 16 is smaller than the circular shape of the hemispherical lower surface 15a of the light-transmitting portion 15 and has an edge that is sized to fit along the outer edge of the lower surface 15a of the light-transmitting portion 15. Next, a light-transmitting portion bonding process is performed to bond the light-transmitting portion 15 and the connecting portion 16 together. The light-transmitting portion 15 and the connecting portion 16 can be bonded together, for example, by room-temperature bonding. When bonding by room-temperature bonding, at least the outer edge of the lower surface 15a of the light-transmitting portion 15 and the edge of the opening 16c of the connecting portion 16 are smoothed to activate the surfaces, thereby bringing them into direct contact (optical contact). As a result, a bonding surface R1 is formed, as can be seen from FIG. 5(b), which shows a central vertical cross-sectional view of the glass cap 10C. In this third embodiment, too, the bonding strength at the bonding surface R1 can be further stabilized by performing an annealing treatment involving low-temperature heating at about 200°C. Thus, the glass cap 10C is manufactured, completing the glass cap manufacturing method of this embodiment. Note that the bonding surface R1 in this embodiment may be bonded by laser bonding, as in the first and second embodiments (detailed explanation will be omitted).

[0034] Once the glass cap 10C has been manufactured using the glass cap manufacturing method described above, an LED device P3 (see FIG. 6) including the glass cap 10C can be manufactured using the LED device manufacturing method described below.

[0035] 6(a) shows a package 20A that, together with the glass cap 10C, constitutes the LED device P3. The package 20A has the same configuration as the package 20A shown in FIG. 2, and is a box-shaped package that includes an outer periphery 21, a bottom 22, and an LED chip 23 as a light emitter mounted in the center of the bottom 22. The outer periphery 21 and bottom 22 are made of ceramics, such as alumina or alumina nitride.

[0036] The glass cap 10C and the package 20A are joined by soldering. The soldering can be performed using procedures similar to those described in the first and second embodiments. More specifically, in the package 20C shown in FIG. 6(a), paste solder 30 is applied to the upper surface 21a of the outer periphery 21 to which the glass cap 10C is joined. Next, the connection portion 16 of the glass cap 10C is positioned and placed on the upper surface 21a of the outer periphery 21 to which the paste solder 30 has been applied, and the package is heated in a reflow furnace. As can be seen from FIG. 6(b), which shows a central vertical cross-sectional view of the LED device P3, the connection portion 16 of the glass cap 10C is connected to the package 20A, forming a joint R2 (package joining process). This completes the LED device P3, completing the manufacturing method for the LED device of this embodiment.

[0037] In the third embodiment described above, the connection portion 16 is also made of glass having a thermal expansion coefficient greater than that of the glass material forming the light transmitting portion 15 and smaller than that of the ceramic forming the outer peripheral portion 21 of the package 20A. This avoids the problem of the glass cap 10C cracking due to the difference in thermal expansion during heating in the package connection step.

[0038] (Fourth Example) A fourth embodiment of the present invention will be described with reference to FIGS. 7 and 8. FIGS. 7(a) and 7(b) show a glass cap 10D of this embodiment. The illustrated glass cap 10D is to be joined to the plate-shaped package 20B shown in FIG. 8(a) and includes a light-transmitting portion 15 and a connecting portion 17 joined to the outer edge of the light-transmitting portion 15. The light-transmitting portion 15, like the light-transmitting portion 15 of the third embodiment, is formed solely of a hemispherical lens body and is made of glass (quartz glass). The connecting portion 17 is a substantially box-shaped member having an upper surface 17a and an outer peripheral portion 17b, and is open downward by a lower end 17c of the outer peripheral portion 17b. A circular opening 17d is formed in the center of the upper surface 17a, to which the outer edge of the lower surface 15a of the light-transmitting portion 15 is joined.

[0039] The connecting portion 17 is bonded to the package 20B to connect the light transmitting portion 15 and the package 20B. The connecting portion 17 is made of glass having a thermal expansion coefficient larger than that of the glass material forming the light transmitting portion 15 and smaller than that of the ceramic (e.g., alumina or alumina nitride) forming the package 20B shown in Fig. 8(a), and is formed from, for example, borosilicate glass (thermal expansion coefficient 3.2) or non-alkali glass (thermal expansion coefficient 3.17).

[0040] When manufacturing the glass cap 10D, first, the light transmitting portion 15 is prepared, and the connecting portion 17 to be bonded to the light transmitting portion 15 is also prepared. As shown in FIG. 7( a), the opening 17d formed in the upper surface 17a of the connecting portion 17 is smaller than the circular shape constituting the lower surface 15a of the hemispherical light transmitting portion 15 and has an edge that is sized to fit along the outer edge of the lower surface 15a of the light transmitting portion 15. Next, a light transmitting portion bonding step is performed to bond the light transmitting portion 15 and the connecting portion 17 together. The light transmitting portion 15 and the connecting portion 17 can be bonded together by room temperature bonding, as in the other embodiments described above. When bonding by room temperature bonding, at least the outer edge of the lower surface 15a of the light transmitting portion 15 and the edge of the opening 17d of the connecting portion 17 are smoothed to activate the surfaces, and the two are brought into direct contact (optical contact). This allows bonding at the bonding surface R1, as can be seen from FIG. 7(b), which shows a central vertical cross-sectional view of the LED device P4. In this fourth embodiment, too, annealing, which involves low-temperature heating at about 200°C, can be performed to further stabilize the bonding strength at the bonding surface R1. The glass cap 10D is thus formed, completing the glass cap manufacturing method of this embodiment. Note that the bonding surface R1 in this embodiment may be laser-bonded, as in the first and second embodiments (detailed explanations will be omitted).

[0041] Once the glass cap 10D has been manufactured by carrying out the glass cap manufacturing method described above, an LED device P4 including the glass cap 10D can be manufactured by the LED device manufacturing method described below.

[0042] 8(a) shows the glass cap 10D and the package 20B to which the glass cap 10D is bonded to form the LED device P4. The package 20B has the same configuration as that of the second embodiment, and includes a substrate 24 and an LED chip 23 as a light emitter mounted in the center of the substrate 24. The substrate 24 is made of, for example, alumina or alumina nitride.

[0043] The glass cap 10D and the package 20B are joined by soldering. The soldering can be performed using procedures similar to those described in the package connection steps described above. More specifically, in the package 20B shown in FIG. 8(a), solder paste 30 is applied to the outer edge of the top surface of the substrate 24 to which the glass cap 10D is to be joined. Next, the connection portion 17 of the glass cap 10D is positioned and placed on the outer edge of the substrate 24 to which the solder paste 30 has been applied, and the package is then heated in a reflow furnace. As can be seen from the central vertical cross-sectional view of the LED device P4 shown in FIG. 8(b), the connection portion 17 of the glass cap 10D is connected to the package 20B, forming a joint R2 (package connection step). This completes the LED device P4, completing the manufacturing method for the LED device of this embodiment.

[0044] In the fourth embodiment described above, the connection portion 17 connecting the light-transmitting portion 15 and the substrate 24 forming the package 20B is also formed from glass having a thermal expansion coefficient greater than that of the quartz glass forming the light-transmitting portion 15 and a thermal expansion coefficient less than that of the ceramic forming the substrate 24. This avoids the problem of the glass cap 10D cracking due to the difference in thermal expansion during heating when the package connection process is carried out to manufacture the LED device P4.

[0045] The present invention is not limited to the above-described embodiment and includes various modifications. For example, the light-transmitting portion 12 constituting the glass cap 10A of the first embodiment can be replaced with a flat light-transmitting portion 18 shown in FIG. 9(a). As can be seen from the central longitudinal cross-sectional views of the light-transmitting portion 18 shown in FIGS. 9(a) and 9(b), the light-transmitting portion 18 does not include a lens portion 121 and is instead made of a plate-shaped glass material of uniform thickness, such as quartz glass. By joining such a light-transmitting portion 18 to the connecting portion 13 shown in FIG. 1 using the glass cap manufacturing method described in the first embodiment, a glass cap that solves the problems to be solved by the present invention can be manufactured. Furthermore, once a glass cap including the light-transmitting portion 18 is manufactured, an LED device that achieves the effects of the present invention can be manufactured using the same LED device manufacturing method as in the first embodiment.

[0046] Furthermore, for example, a light-transmitting portion 19 as shown in FIG. 10(a) can be used instead of the light-transmitting portion 12 constituting the glass cap 10A of the first embodiment. The light-transmitting portion 19 is formed of a glass material such as quartz glass. As can be seen from FIG. 10(a) and FIG. 10(b), which shows a central longitudinal cross-sectional view of the light-transmitting portion 19, the light-transmitting portion 19 includes a hollow dome-shaped dome portion 19a and a flat rib 19b with the dome portion 19a formed in its center. By joining such a light-transmitting portion 19 to the connecting portion 13 shown in FIG. 1 using the glass cap manufacturing method described in the first embodiment, a glass cap that can solve the problems to be solved by the present invention can be manufactured. Furthermore, once a glass cap including the light-transmitting portion 19 is manufactured, an LED device that achieves the effects of the present invention can be manufactured by carrying out an LED device manufacturing method similar to that of the first embodiment.

[0047] In the above-described embodiments, the LED device has been described as having a rectangular shape in a plan view, but the present invention is not limited to this. An LED device constructed according to the present invention may have, for example, a circular shape in a plan view. In this case, for example, the rib 122 and the connection portion 13 of the light-transmitting portion 12 constituting the glass cap 10A described with reference to FIG. 1 may be configured to have a circular shape in a plan view, and the shape of the package 20A described with reference to FIG. 2 may be formed to have a circular shape in a plan view.

[0048] In the above-described embodiments, examples have been described in which the packages 20A and 20B are formed from ceramics, but the present invention is not limited to this. For example, a PCB substrate having a base material such as Kovar alloy (thermal expansion coefficient 4.5 to 5.1), phenolic resin, epoxy resin, polyimide resin, or fluororesin (thermal expansion coefficient 65 to 85) may also be used, and the same effects as those of the above-described embodiments can be achieved. [Explanation of symbols]

[0049] 10A, 10B, 10C, 10D: glass cap, 12: light-transmitting portion, 121: lens portion, 122: rib, 13: connecting portion, 13a: upper surface, 13b: lower surface, 14: connecting portion, 14a: upper surface, 14b: lower surface, 15: light-transmitting portion, lower surface portion: 15a, 16: connecting portion, 16c: opening, 17: connecting portion, 17a: upper surface, 17b: outer periphery, 17c: lower end, 18: light-transmitting portion, 19: light-transmitting portion, 19a: dome portion, 19b: rib, 20A, 20B: package, 21: outer periphery, 21a: upper surface, 22: bottom, 23: LED chip, 24: substrate, 30: solder paste, P1, P2, P3, P4: LED device, R1, R2: bonding surface

Claims

1. A glass cap bonded to a package, the glass cap includes at least a light-transmitting portion formed of a glass material, and a connecting portion bonded to the light-transmitting portion and to the package, thereby connecting the light-transmitting portion and the package; The connecting portion is a glass cap formed from a material having a thermal expansion coefficient greater than that of the glass material forming the light-transmitting portion and smaller than that of the material forming the package.

2. the glass material forming the light-transmitting portion is quartz glass, the material forming the package is ceramic; 2. The glass cap according to claim 1, wherein the material forming the connection portion is a glass material.

3. 2. The glass cap according to claim 1, wherein the light-transmitting portion is flat, hemispherical, hemispherical with a flat rib connected to its outer periphery, or hollow dome-shaped with a flat rib connected to its outer periphery.

4. A method for manufacturing the glass cap according to any one of claims 1 to 3, comprising the steps of: The glass cap manufacturing method includes a light transmitting portion bonding step of bonding the light transmitting portion and the connecting portion by room temperature bonding or laser bonding.

5. A method for manufacturing an LED device including the glass cap according to any one of claims 1 to 3, comprising: a light transmitting portion joining step of joining the light transmitting portion and the connection portion by room temperature joining or laser joining; and a package connection step of connecting the connection portion to the package in which the LED chip is mounted by soldering.

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