JP7778404B2 - Glass sheet manufacturing method and glass cap manufacturing method - Google Patents

Description

The present invention relates to a glass sheet and a method for manufacturing the glass sheet that enables improved productivity in the mass production of dome-shaped (hollow hemispherical) glass caps.

In recent years, dome-shaped glass caps have been installed on various devices (e.g., laser diodes, photodiodes, light-emitting diodes, MEMS mirrors, etc.). Generally, dome-shaped glass caps are attached to various devices using a sealing solder material (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2021-174852

However, dome-shaped glass caps are manufactured on a chip-by-chip basis using a molding method, making them unsuitable for mass production. Furthermore, the process of coating the glass cap with sealing solder material must also be carried out on a chip-by-chip basis. Furthermore, if the dimensions or shape of the glass cap are to be changed, a new mold must be created. Furthermore, when using a mold, there are limitations due to the difference in the expansion coefficients of the mold material and the glass material, limiting the size of glass caps that can be mass-produced (for example, glass caps with a diameter of 50 mm or more). For these reasons, there is a demand for improved productivity when mass-producing dome-shaped glass caps.

The objective of the present invention is to provide a glass sheet and a method for manufacturing the glass sheet that enables improved productivity when mass-producing dome-shaped glass caps.

According to the present invention, there is provided the following glass sheet that solves the above problems:
"A flat glass sheet having a plurality of dome-shaped protrusions, wherein the diameter of the protrusions is less than 50 mm when viewed in a direction perpendicular to the first surface of the glass sheet having the plurality of protrusions."

The plurality of protrusions protrude toward the first surface of the glass sheet, and preferably have at least one solder portion coated with a solder material on the second surface of the glass sheet opposite the first surface in a portion around the plurality of protrusions where the plurality of protrusions are not formed. It is preferable that the number of solder portions is the same as the number of the plurality of protrusions, and that a plurality of the solder portions are formed around each of the plurality of protrusions.

According to the present invention, there is also provided the following method for producing a glass sheet, which solves the above-mentioned problems:
"A method for manufacturing a flat glass sheet having a plurality of dome-shaped protrusions on a first surface,
a temporary bonding step of temporarily bonding a second surface of the glass sheet opposite to the first surface to a substrate having a plurality of circular recesses formed thereon;
a protrusion forming process in which the glass sheet and the substrate are heated to a temperature higher than the softening point of the glass sheet and the pressure around the glass sheet and the substrate is reduced, thereby causing portions of the glass sheet corresponding to the plurality of circular recesses to protrude in the dome shape toward the first surface of the glass sheet, thereby forming the plurality of protrusions on the glass sheet;
and a removal step of removing the substrate temporarily bonded to the glass sheet by grinding or polishing the substrate temporarily bonded to the glass sheet."

After the removal step, it is desirable to carry out a coating step in which a solder portion coated with a solder material is formed on the second surface of the glass sheet in the area surrounding the plurality of protrusions where the plurality of protrusions are not formed. The substrate may be made of glass or silicon.

The glass sheet and manufacturing method of the present invention enable improved productivity when mass-producing dome-shaped glass caps.

1 is a perspective view of a glass sheet according to the present invention; FIG. 2 is a cross-sectional view taken along line II-II in FIG. FIG. 2 is a schematic diagram illustrating a state in which the glass sheet shown in FIG. 1 is being divided. (a) Schematic diagram of a divided glass sheet, (b) Perspective view of a glass cap. FIG. FIG. 1 is a perspective view of a substrate on which a plurality of circular recesses are formed. Schematic diagram showing a joining process. Schematic diagram showing a protrusion forming step. Schematic diagram showing the fixing process. (a) Schematic diagram showing the removal step, (b) Schematic diagram of the glass sheet from which the substrate has been removed. FIG. 10A is a schematic diagram showing a first modified example of the removal step, and FIG. 10B is a schematic diagram showing a second modified example of the removal step.

Below, preferred embodiments of the glass sheet and glass sheet manufacturing method according to the present invention will be described with reference to the drawings.

First, we will explain the glass sheet according to the present invention. As shown in Figures 1 and 2, the glass sheet 2 is a planar sheet having multiple dome-shaped protrusions 4. The multiple protrusions 4 protrude toward the first surface 2a of the glass sheet 2. The diameter of each protrusion 4 is less than 50 mm when viewed in a direction perpendicular to the first surface 2a of the glass sheet 2 on which the multiple protrusions 4 are formed. In this embodiment, the protrusions 4 are arranged in a 6 x 6 array (36 in total), but the number of protrusions 4 formed on the glass sheet 2 is arbitrary. As shown in Figure 2, the second surface 2b, opposite the first surface 2a of the glass sheet 2, has at least one solder portion 6 coated with a solder material in the area surrounding the multiple protrusions 4 where no multiple protrusions 4 are formed. In this embodiment, the number of solder portions 6 is the same as the number of multiple protrusions 4, and multiple solder portions 6 are formed around each of the multiple protrusions 4. The cross section of Figure 2 is a plane passing through the apexes of the multiple protrusions 4 and perpendicular to the glass sheet 2. In this embodiment, the glass sheet 2 has a rectangular shape (e.g., 100 mm x 100 mm), but it may have other shapes such as a circle.

By dividing such a glass sheet 2 into individual dome-shaped protrusions 4, dome-shaped glass caps can be manufactured. The glass sheet 2 can be divided using, for example, a dicing device 8 shown in Figure 3. The dicing device 8 includes a chuck table 10 that holds the workpiece by suction, and a cutting blade 12 that cuts the workpiece held on the chuck table 10.

To separate the glass sheet 2, first place the glass sheet 2 on the top surface of the chuck table 10 with the protruding portions 4 facing upward. Next, a suction device (not shown) connected to the chuck table 10 is activated to generate suction on the top surface of the chuck table 10, thereby suction-holding the second surface 2b of the glass sheet 2. Next, the cutting blade 12 is rotated in the direction indicated by arrow R1 in Figure 3. The cutting edge of the cutting blade 12 is then inserted between the protruding portions 4 of the glass sheet 2, and the chuck table 10, which is holding the glass sheet 2 by suction, is moved along the X-axis perpendicular to the plane of the drawing, thereby cutting the glass sheet 2. This cutting process and the indexing of the cutting blade 12 along the Y-axis are repeated, and the chuck table 10 is then rotated 90 degrees, after which the cutting process and indexing are repeated. As a result, the glass sheet 2 can be separated at each protruding portion 4, producing dome-shaped glass caps 14, as shown in Figures 4(a) and 4(b). Therefore, a glass sheet 2 having multiple protrusions 4 that protrude in a dome shape can improve productivity when mass-producing dome-shaped glass caps 14.

Next, we will explain a method for manufacturing a planar glass sheet 2 having multiple dome-shaped protrusions 4 on the first surface 2a.

(Substrate preparation process)
In this embodiment, first, a substrate preparation step is performed to prepare a substrate 16 as shown in FIG. 4 . The shape of the substrate 16 shown in FIG. 4 is rectangular, similar to the shape of the glass sheet 2, but it does not have to be the same shape as the glass sheet 2. The dimensions of the substrate 16 in a plan view are preferably equal to or greater than the dimensions of the glass sheet 2 (e.g., 100 mm × 100 mm). The thickness of the substrate 16 may be the same as or different from the thickness of the glass sheet 2. The substrate 16 is preferably made of a material (e.g., glass or silicon (Si)) having a linear expansion coefficient close to that of the glass sheet 2, and more preferably is made of the same material as the glass sheet 2.

(Circular recess forming process)
After the substrate preparation step, a circular recess formation step is performed to form a plurality of circular recesses in the substrate 16. In the circular recess formation step, a required pattern is first formed on the first surface 16a of the substrate 16 by photolithography. Next, the first surface 16a of the substrate 16 on which the pattern has been formed is subjected to sandblasting, CNC (Computer Numerical Control) processing, or etching (wet etching or dry etching). As a result, a plurality of circular recesses 18 can be formed on the first surface 16a of the substrate 16, as shown in FIG. 6 .

(Temporary joining process)
After the circular recess forming step, as shown in FIG. 7 , a bonding step is performed in which the second surface 2b of the glass sheet 2, opposite the first surface 2a, is bonded to the substrate 16 having the plurality of circular recesses 18 formed thereon. The glass sheet 2 to be temporarily bonded in the temporary bonding step is a flat sheet without the plurality of protrusions 4 formed thereon. In the temporary bonding step, the substrate 16 and the glass sheet 2 can be temporarily bonded by optical contact, for example. Furthermore, after forming a bonded body 20 by temporarily bonding the substrate 16 and the glass sheet 2, the bonded body 20 can be heated to enhance adhesion between the substrate 16 and the glass sheet 2. A nitrogen atmosphere furnace can be used to heat the bonded body 20. The heating temperature of the bonded body 20 can be just below the softening point of the glass sheet 2.

(Protrusion formation process)
After the joining step, a protrusion forming step is performed to form multiple protrusions 4 on the glass sheet 2. The protrusion forming step can be performed using, for example, a vacuum atmosphere furnace (not shown). In the protrusion forming step, the joined body 20 is placed in the vacuum atmosphere furnace and heated to a temperature above the softening point of the glass sheet 2. Next, the vacuum atmosphere furnace is depressurized. This reduces the pressure around the joined body 20, creating a pressure difference between the pressure around the joined body 20 and the pressure inside the circular recesses 18. As a result, portions of the glass sheet 2 corresponding to the multiple circular recesses 18 protrude in a dome shape toward the first surface 2a. In this manner, multiple protrusions 4 are formed on the glass sheet 2. The protrusion height of the protrusions 4 can be adjusted by controlling the temperature and pressure inside the vacuum atmosphere furnace.

(Fixed process)
After the protrusion forming step, a fixing step is performed in which the plurality of protrusions 4 of the glass sheet 2 are accommodated in a plurality of accommodation holes of a jig having a plurality of accommodation holes, and the glass sheet 2 is fixed to the jig. The jig may have any shape as long as it can accommodate the plurality of protrusions 4 of the glass sheet 2 and fix the glass sheet 2 to the jig.

In the fixing process, for example, a jig 22 shown in Figure 9 can be used. The jig 22 has multiple accommodation holes 24 that accommodate multiple protrusions 4. The dimensions of the accommodation holes 24 in a plan view are larger than the diameter of the protrusions 4, and the depth of the accommodation holes 24 is larger than the protrusion height of the protrusions 4. Therefore, when the protrusions 4 are accommodated in the accommodation holes 24, the protrusions 4 do not come into contact with the bottom surface 24a or side surfaces 24b of the accommodation holes 24. The accommodation holes 24 can be any shape, such as circular or rectangular.

It is preferable that the jig 22 has a number of accommodating holes 24 formed that corresponds to the number of protrusions 4. In this case, one accommodating hole 24 accommodates one protrusion 4. However, one accommodating hole 24 may accommodate two or more protrusions 4. Furthermore, the jig 22 may have one accommodating hole 24 that accommodates all of the protrusions 4.

The jig 22 can be manufactured, for example, using the same procedure as the circular recess formation process described above. That is, the jig 22 can be manufactured by forming the required pattern using photolithography on a plate material that does not have a receiving hole 24, and then performing sandblasting, CNC machining, or etching. The jig 22 can be made from any of a variety of materials, such as carbon, silicon, glass, or ceramics. Such a jig 22 can be manufactured at lower cost and in a shorter period of time than molds used to manufacture glass caps using conventional molding methods.

In the fixing process, as shown in Figure 9, the multiple protrusions 4 are placed in the receiving holes 24 of the jig 22, and the glass sheet 2 and the jig 22 are fixed together. An appropriate adhesive can be used to fix the glass sheet 2 and the jig 22 together.

(Removal process)
After the fixing step, a removal step is carried out in which the substrate 16 temporarily bonded to the glass sheet 2 is removed by grinding or polishing the substrate 16. The removal step can be carried out using, for example, a grinding device 26 shown in Fig. 10(a) . The grinding device 26 includes a chuck table 28 that holds the workpiece and a grinding wheel 30 that grinds the workpiece held on the chuck table 28.

In the removal process, first, the second surface 16b of the substrate 16 is faced upward, and the flat surface 22a of the jig 22 (the surface without the accommodation hole 24) is suction-held on the upper surface of the chuck table 28. Next, the grinding wheel 30 is rotated in the direction indicated by arrow R2 in Figure 10(a) and lowered until it contacts the second surface 16b of the substrate 16. The grinding wheel 30 is then moved appropriately in the XY plane and lowered at an appropriate grinding feed rate. As a result, the substrate 16 can be ground and removed from the bonded body 20, as shown in Figure 10(b).

The device for removing the substrate 16 is not limited to the grinding device 26 described above. For example, as shown in FIG. 11(a), a grinding device 26' having a grinding wheel 32 larger than the substrate 16 can be used. Alternatively, as shown in FIG. 11(b), a grinding device 26" having a grinding wheel 34 whose axis extends horizontally can be used. Furthermore, the substrate 16 can be removed from the bonded body 20 by polishing the substrate 16 with a polishing device (not shown) having a polishing pad.

(Coating process)
After the removing step, a coating step is performed to form solder portions 6 coated with a solder material on the portions of the second surface 2b of the glass sheet 2 surrounding the plurality of protrusions 4 where the plurality of protrusions 4 are not formed. In the coating step, at least one solder portion 6 is formed. In the coating step of this embodiment, the same number of solder portions 6 as the number of protrusions 4 are formed, and multiple solder portions 6 are formed around each of the plurality of protrusions 4. The solder portions 6 can be formed on the second surface 2b of the glass sheet 2 by vapor deposition or plating. The coating step may be performed before or after the glass sheet 2 is removed from the jig 22.

In this embodiment, the solder portions 6 are formed on the glass sheet 2 before it is divided into glass caps 14. As a result, the manufacturing method of this embodiment has better productivity than conventional processing methods in which the solder portions 6 are formed on a chip-by-chip basis.

In this manner, a glass sheet 2 (see Figures 1 and 2) having multiple dome-shaped protrusions 4 is manufactured. Then, by dividing the glass sheet 2 into individual dome-shaped protrusions 4, dome-shaped glass caps 14 can be manufactured. This allows for improved productivity when mass-producing glass caps 14.

Unlike conventional molding methods, this embodiment does not require a mold to manufacture the glass cap 14, making it easy to change the shape and dimensions of the glass cap 14. Furthermore, with conventional molding methods, the minimum size of a glass cap that could be manufactured was approximately 50 mm square due to the difference in the linear expansion coefficient between the mold material and the glass cap material. In this regard, if the substrate 16 of this embodiment is made of a material (e.g., glass or silicon (Si)) with a linear expansion coefficient close to that of the glass sheet 2, it is possible to make the glass cap 14 smaller than with conventional molding methods.

Furthermore, in this embodiment, the protrusion height of the protrusion 4 on the glass sheet 2 (i.e., the height of the glass cap 14) can be adjusted by controlling the temperature and pressure during the protrusion formation process. This makes it possible to form an anti-reflection film on the glass cap 14, thereby improving light extraction efficiency.

2: Glass sheet, 2a: First surface of glass sheet, 2b: Second surface of glass sheet, 4: Protrusion, 6: Solder material, 14: Glass cap, 16: Substrate, 16a: First surface of substrate, 16b: Second surface of substrate, 18: Circular recess, 22: Jig, 24: Receiving hole

Claims (4)

A method for manufacturing a flat glass sheet having a plurality of dome-shaped protrusions on a first surface, comprising:
a temporary bonding step of temporarily bonding a second surface of the glass sheet opposite the first surface to a substrate having a plurality of circular recesses formed thereon by optical contact ;
a protrusion forming process in which the glass sheet and the substrate are heated to a temperature higher than the softening point of the glass sheet and the pressure around the glass sheet and the substrate is reduced, thereby causing portions of the glass sheet corresponding to the plurality of circular recesses to protrude in the dome shape toward the first surface of the glass sheet, thereby forming the plurality of protrusions on the glass sheet;
a removing step of removing the substrate temporarily bonded to the glass sheet by grinding or polishing the substrate temporarily bonded to the glass sheet. 2. The method for manufacturing a glass sheet according to claim 1, wherein after the removal process, a coating process is carried out in which a solder portion having a surface made of a solder material is formed on the second surface of the glass sheet in a portion around the plurality of protrusions where the plurality of protrusions are not formed. The method for manufacturing a glass sheet according to claim 1 or 2 , wherein the substrate is made of glass or silicon. A method for manufacturing a glass cap, comprising: performing the covering step in the method for manufacturing a glass sheet according to claim 2; and dividing the glass sheet into individual protrusions before soldering with the solder portion, thereby manufacturing a dome-shaped glass cap.