Light source unit

Abstract

Provided is a light source unit that more uniformly cools a mounted light emitting element. The present invention is provided with: a substrate on which a plurality of LEDs are mounted on a first main surface; a first through-hole connecting the first main surface of the substrate and a second main surface on the opposite side of the first main surface, the center of the first through-hole being within a predetermined range from the center of gravity of the first main surface when viewed in a direction orthogonal to the first main surface of the substrate; a heat sink provided on the second main surface side of the substrate; and a first fixing screw that fixes the substrate and the heat sink by being inserted into the first through-hole of the substrate and screwed into a screw hole provided corresponding to the first through-hole.

Description

Technical Field

[0001] The present invention relates to a light source unit. Background Art

[0002] In the manufacturing process of semiconductors, various heat treatments such as film forming, oxidation diffusion, modification or annealing are performed on the processed object headed by the semiconductor wafer. Light is often used in the execution of these heat treatments. Thus, heating the processed object using light is called "light heating". In addition, the light used for heating is called "heating light".

[0003] As a device for heating a semiconductor wafer using light heating, a heating device is known that mounts LEDs, which are one of the light-emitting elements, on a substrate at a high density. It is known that the light-emitting efficiency of light-emitting elements such as LEDs and LDs decreases if the temperature of the element itself rises. Therefore, a heating device is proposed that includes a heat sink on the opposite side of the substrate from the mounting surface in order to cool the LEDs mounted as the light-emitting elements, as described in the following patent document 1.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2010-153734 Summary of the invention

[0007] Problems to be solved by the invention

[0008] Here, the present inventors checked the temperature distribution of the substrate on which the light-emitting element is mounted during the heat treatment in order to cool the light-emitting element more efficiently and uniformly, and noticed that there is a bias in the temperature distribution of the substrate in many cases.

[0009] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a light source unit that can cool a mounted light emitting element more uniformly.

[0010] Means used to solve problems

[0011] The light source unit of the present invention is characterized in that it comprises: a substrate having a plurality of LEDs mounted on a first main surface; a first through hole having a center located within a specified range from the center of gravity of the first main surface when viewed in a direction orthogonal to the first main surface of the substrate, connecting the first main surface of the substrate and the second main surface on the opposite side of the first main surface; a heat sink disposed on the second main surface side of the substrate; and a first fixing screw member, which is inserted into the first through hole of the substrate and screwed into a screw hole provided corresponding to the first through hole, thereby fixing the substrate and the heat sink.

[0012] In this specification, "center of gravity" is used to refer to a point on a specified surface that is equivalent to the geometric center. In addition, in this specification, "within a specified range from the center of gravity" means an area within 20% of the maximum diagonal distance of the first main surface from the center of gravity.

[0013] The present inventors have studied the cause of the non-uniform temperature distribution of the substrate during heat treatment and found that the temperature near the center of gravity (central portion) of the substrate on which the light-emitting element is mounted is higher than the temperature assumed in the design.

[0014] In a conventional light source unit, light emitting elements are densely arranged on the central portion side of the first main surface of a substrate, and a through hole for inserting a fixing screw is formed near the outer edge of the substrate.

[0015] Here, the first main surface side on which the light-emitting element is mounted becomes hot when emitting light and undergoes thermal expansion. In contrast, the second main surface side connecting the heat-conducting component and the heat sink is at a relatively low temperature and does not undergo thermal expansion to the same extent as the first main surface. Therefore, as described above, the center of gravity (central portion) of the substrate deforms in a manner that it moves away from the heat sink.

[0016] Furthermore, if the substrate fixed only at the outer edge by the fixing screws is deformed as described above, the contact between the substrate and the heat sink or the substrate and the heat conducting member can no longer be maintained near the center of gravity (central portion) of the second main surface, and heat cannot be fully discharged.

[0017] Therefore, with the above configuration, even when deformation occurs in the substrate of the light source unit, the vicinity of the center of gravity (central portion) of the second main surface of the substrate can maintain contact with the heat sink or the heat conducting member.

[0018] The above-mentioned light source unit may also include: a second through hole, which is formed at a position where the distance from the above-mentioned first through hole is less than 55% of the maximum diagonal distance on the above-mentioned first main surface when observed in a direction orthogonal to the above-mentioned first main surface of the above-mentioned substrate, connecting the above-mentioned first main surface of the above-mentioned substrate with the above-mentioned second main surface; and a second fixing screw, which is inserted into the above-mentioned second through hole of the above-mentioned substrate and screwed into a screw hole provided corresponding to the above-mentioned second through hole, thereby fixing the above-mentioned substrate and the above-mentioned heat sink.

[0019] In this specification, the distance between the first through hole and the second through hole refers to the distance between the centers of the through holes when viewed in a direction perpendicular to the first main surface of the substrate.

[0020] The light source unit having the above structure can more reliably maintain the contact between the substrate and the heat sink or the heat conduction member at multiple points.

[0021] Effects of the Invention

[0022] According to the present invention, it is possible to realize a light source unit that can cool a mounted light emitting element more uniformly. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a cross-sectional view schematically showing the structure of one embodiment of the optical heating device.

[0024] Figure 2A Yes Figure 1 A cross-sectional view of the light source unit when viewed in the Y direction.

[0025] Figure 2B Yes Figure 1 A cross-sectional view of the light source unit when viewed in the X direction.

[0026] Figure 3 This is a schematic diagram when the light source unit is viewed from the -Z side.

[0027] Figure 4 This is a schematic diagram of a substrate removed from a light source unit when viewed from the -Z side.

[0028] Figure 5 This is a schematic diagram of a substrate removed from a light source unit when viewed from the -Z side.

[0029] Figure 6 It is a figure which shows the sample used for a verification experiment.

[0030] Figure 7 It is a figure which shows the sample used for a verification experiment.

[0031] Figure 8 It is a figure which shows the sample used for a verification experiment.

[0032] Fig. 9 It is a figure which shows the sample used for a verification experiment.

[0033] Fig.10 It is a figure which shows the sample used for a verification experiment.

[0034] Fig.11 It is a figure which shows the sample used for a verification experiment.

[0035] Fig.12 It is a figure which shows the sample used for a verification experiment.

[0036] Fig.13 It is a figure which shows the sample used for a verification experiment.

[0037] Fig.14 It is a figure which shows the sample used for a verification experiment.

[0038] Fig.15It is a figure which shows the sample used for a verification experiment.

[0039] Fig.16 It is a figure which shows the sample used for a verification experiment.

[0040] Description of symbols

[0041] 1: Light heating device

[0042] 10: Light source unit

[0043] 11: Light-emitting element

[0044] 12: Substrate

[0045] 12a: First main surface

[0046] 12b: Second main surface

[0047] 12p: First through hole

[0048] 12q: Second through hole

[0049] 14: Heat sink

[0050] 14a: Screw hole

[0051] 15: First fixing screw

[0052] 16: Second fixing screw

[0053] 20: Chamber

[0054] 21: Light-transmitting window

[0055] 22: Supporting parts

[0056] L1: Heating light

[0057] W1: processed substrate

[0058] W1a: Main side DETAILED DESCRIPTION

[0059] Hereinafter, the light source unit of the present invention will be described with reference to the accompanying drawings. In addition, each of the following drawings is schematically illustrated, and the number of units in the drawings does not necessarily correspond to the actual number of units.

[0060] Figure 1 is a cross-sectional view schematically showing the structure of an embodiment of the optical heating device 1. Figure 2A Yes Figure 1 A diagram of the light source unit 10 when viewed in the Y direction, Figure 2B Yes Figure 1 A cross-sectional view of the light source unit 10 when viewed in the X direction. Figure 3 This is a schematic diagram when the light source unit 10 is viewed from the −Z side.

[0061] Light heating device 1 Figure 1 As shown, a light source unit 10 and a chamber 20 for accommodating a substrate W1 to be processed are provided. The substrate W1 to be processed may be a semiconductor wafer, a display panel, a glass substrate, etc. The semiconductor wafer is not particularly limited to a Si substrate, and may also be a SiC substrate, etc.

[0062] In the following description, Figure 1 As shown in FIG. 1 , the direction in which the light source unit 10 and the chamber 20 are opposed to each other is defined as the Z direction, and the plane perpendicular to the Z direction, that is, the plane parallel to the first main surface 12a of the substrate 12 is defined as the XY plane. In addition, in this embodiment, although the X direction and the Y direction perpendicular to each other forming the XY plane are not distinguished, Figure 1 to Figure 2B , the direction in which the first fixing screws 15 are arranged is set as the X direction, and the direction in which the second fixing screws 16 are arranged is set as the Y direction. Figure 3 to Figure 16 Although there is no designation of the direction based on the fixing screws (15, 16), arbitrary directions orthogonal to each other on a plane orthogonal to the Z direction are tentatively illustrated as the X direction and the Y direction.

[0063] When expressing a direction, when distinguishing between positive and negative directions, positive and negative signs are given and recorded, such as "+Z direction" and "-Z direction". When expressing a direction without distinguishing between positive and negative directions, it is simply recorded as "Z direction".

[0064] The light source unit 10 is as follows Figure 1 to Figure 2B As shown, a plurality of light emitting elements 11 , a plurality of substrates 12 on which the light emitting elements 11 are mounted, a heat sink 14 , a plurality of first fixing screws 15 , and a plurality of second fixing screws 16 are provided.

[0065] The light source unit 10 of the present embodiment has a structure in which a plurality of substrates 12 are fixed to one heat sink 14 by the first fixing screws 15 , but may also have a structure in which only one substrate 12 is mounted to one heat sink 14 .

[0066] In addition, the light source unit 10 may also be Figure 1 to Figure 2B As shown, one substrate 12 is fixed to the heat sink 14 divided into a plurality of parts by the first fixing screw 15 and the second fixing screw 16. Alternatively, the light source unit 10 may be fixed by only the first fixing screw 15 without the second fixing screw 16.

[0067] The chamber 20 of this embodiment is as follows Figure 1As shown, there is a light-transmitting window 21 for taking in the heating light L1 emitted from the light source unit 10 and a supporting member 22 for supporting the substrate W1 to be processed on the inside. That is, the substrate W1 to be processed supported by the supporting member 22 is irradiated with the heating light L1 emitted from the light source unit 10 and taken in from the light-transmitting window 21 on the main surface W1a, thereby performing a heating treatment.

[0068] The light emitting element 11 of this embodiment is an LED having a wavelength of 395 nm showing an intensity peak in the emission spectrum. In addition, the light emitting element 11 is not limited to LEDs having this characteristic, and the wavelength showing an intensity peak and the type of element can be arbitrarily selected according to the heating object. Specifically, the light emitting element 11 can also be an LED element having a wavelength showing an intensity peak in the emission spectrum belonging to the visible light region or the infrared light region. Furthermore, the light source unit 10 can also be equipped with multiple LDs or other light emitting elements instead of or together with multiple LEDs.

[0069] The first main surface 12a of the substrate 12 is the mounting surface of the light emitting element 11, and the second main surface 12b on the opposite side (+Z side) of the first main surface 12a is connected to the heat sink 14 via grease (not shown) for improving thermal conductivity. In addition, the substrate 12 and the heat sink 14 may be connected without grease.

[0070] The substrate 12 is a ceramic substrate having a pair of electrodes and a wiring pattern formed on the first main surface 12a, but these are omitted for convenience. In addition, a plurality of light-emitting elements 11 are mounted on the first main surface 12a of the substrate 12, and each light-emitting element 11 is lit by supplying power between the electrodes. Figure 3 to Figure 5 The arrangement pattern of the light emitting elements 11 shown is only an example.

[0071] The heat sink 14 is a component that dissipates heat generated in the substrate 12 directly or via grease. Figure 1 to Figure 2B As shown, a screw hole 14 a into which the first fixing screw 15 is screwed is provided, which corresponds to the first through hole 12 p of the base plate 12 .

[0072] In addition, the fixing screws (15, 16) can be fixed by being screwed into a predetermined screw hole, and the size and shape are not limited. For example, they can be bolts screwed into a screw hole formed on a nut. In addition, the screw hole 14a does not need to be formed on the heat sink 14, and can also be a screw hole provided by the nut. That is, the substrate 12 and the heat sink 14 can also be fixed by inserting a bolt through the through hole (12p, 12q) and screwing the bolt into the screw hole of the nut arranged on the +Z side of the heat sink 14.

[0073] Figure 4 and Figure 51 is a schematic diagram of a substrate 12 removed from the light source unit 10 and viewed from the -Z side. Figure 4 and Figure 5 As shown, a first through hole 12p for inserting the first fixing screw 15 and a plurality of second through holes 12q for inserting the second fixing screw 16 are formed.

[0074] Here, refer to Figure 4 and Figure 5 The positional relationship between the first through hole 12 p and the second through hole 12 q on the first main surface 12 a of the substrate 12 will be described.

[0075] The first through hole 12p is formed so that, when the substrate 12 is viewed in the Z direction, the center thereof is located within a predetermined range (A1, A2) from the center of gravity (G1, G2) on the first main surface 12a. The predetermined range A1 is a range within 25% of the maximum diagonal distance (C1, C2) of the first main surface 12a from the center of gravity (G1, G2). Figure 4 and Figure 5 The area in the middle is enclosed by a single dot-dashed line.

[0076] Here, the center of gravity on the first main surface 12a is a point corresponding to the geometric center of the first main surface 12a as described above. The center of gravity of the first main surface 12a can be determined by, for example, a center of gravity deriving function such as that provided in CAD software.

[0077] In addition, regarding the present embodiment Figure 4 and Figure 5 The substrate 12 of the structure shown has a maximum diagonal distance C1 of 113.4 mm and a maximum diagonal distance C2 of 80.61 mm.

[0078] The second through hole 12q is formed at a position where the distance d1 from the center of the first through hole 12p is less than 55% of the maximum diagonal distance C1 when the substrate 12 is viewed in the Z direction. Figure 4 and Figure 5 The substrates 12 of the structure shown have a separation distance d1 of 27.68 mm and a separation distance d2 of 35.598 mm.

[0079] When the light emitting element 11 is turned on, the first main surface 12a of the substrate 12 expands due to the heat generated by the light emitting element 11. Figure 2A In contrast, the second main surface 12b of the substrate 12 does not expand as much as the first main surface 12a because the heat is successively discharged by the heat sink 14. Therefore, with respect to the stress f1 acting on the first main surface 12a side, the stress f1 acting on the second main surface 12b is relatively Figure 2ASuch stress f2 is indicated by a double-dashed arrow.

[0080] Due to these stresses (f1, f2), the substrate 12 is deformed in a manner that the vicinity of the center of gravity (near the first fixing screw 15) is separated from the heat sink 14, that is, in a manner that is convex toward the -Z side. In addition, the substrate 12 may also deform in accordance with material properties, aging, etc. in addition to the above-mentioned phenomenon. Furthermore, it is also conceivable that the substrate 12 is in a slightly warped state during manufacturing.

[0081] Such deformation of the substrate 12 causes the second main surface 12b of the substrate 12 to separate from the heat sink 14 near the center of gravity (central portion) of the substrate 12, partially causing a decrease in heat dissipation characteristics. In this case, the entire substrate 12 is not uniformly cooled.

[0082] However, the light source unit 10 of the above structure has the second main surface 12b of the substrate 12 fixed by the first fixing screw 15 near the center so that the second main surface 12b is substantially reliably in contact with the heat sink 14. Therefore, the heat dissipation characteristics of the entire substrate 12 are maintained.

[0083] Here, in order to evaluate the contact condition between the substrate 12 and the heat sink 14, a transparent acrylic plate erected on the substrate 12 is fixed to a fixing plate erected on the heat sink 14 via grease, and a simple verification experiment is performed to observe the close contact condition between the acrylic plate and the fixing plate near the center (near the center of gravity on the main surface of the acrylic plate), so the content of the experiment is briefly explained.

[0084] Figure 6 to Figure 16 The following is a diagram showing the various samples used in the verification experiment. Figure 4 and Figure 5 The shape of the test specimens and Figure 6 to Figure 16 The total number of samples shown is 13. Figures 4 to 11 The samples shown are respectively set as Examples 1 to 8. Figure 12 to Figure 16 The samples shown are referred to as Comparative Examples 1 to 5, respectively.

[0085] The center of gravity (G1, G2, Gn) and the maximum diagonal distance (C1, C2, Cn) of each sample are as shown in the figures, and the length A of the maximum diagonal distance (C1, C2, Cn), the distance B between the center of gravity (G1, G2, Gn) and the first through hole 12p, and the ratio of the distance B to the length A are as shown in the following Table 1. In addition, in this experiment, the first through hole 12p is used as a representative through hole closest to the center of gravity (G1, G2, Gn).

[0086] [Table 1]

[0087] Sample Length A(mm) Standoff distance B(mm) B / A×100(%) Example 1 113.40 2.70 2.38 Example 2 80.61 10.02 12.43 Example 3 72.38 1.70 2.35 Example 4 132.20 11.69 8.84 Example 5 146.37 12.40 8.47 Example 6 93.65 1.20 1.28 Example 7 100.40 3.20 3.19 Example 8 82.44 15.62 18.95 Comparative Example 1 125.72 38.79 30.85 Comparative Example 2 121.62 37.85 31.12 Comparative Example 3 125.87 28.87 22.94 Comparative Example 4 100.40 21.74 21.65 Comparative Example 5 55.35 21.27 38.43

[0088] In the structures of Examples 1 to 8, when observed through the acrylic plate, there were no pores in the grease, or if there were pores, they were small enough to be ignored, and particularly good results were obtained for Examples 1 to 7. In the structures of Comparative Examples 1 to 5, pores of an unacceptable degree were confirmed in the grease observed through the acrylic plate.

[0089] Based on the above, the distance between the position of the first through hole 12p and the center of gravity is preferably within 20% of the maximum diagonal distance of the first main surface 12a, and more preferably within 15%.

[0090] Therefore, even when the substrate 12 is deformed as described above, the light source unit 10 mounted in the optical heating device 1 can maintain the heat dissipation characteristics near the center of gravity (central portion) and can uniformly cool the entire substrate 12 .

[0091] The configurations of the optical heating device 1 and the light source unit 10 described above are merely examples, and the present invention is not limited to the configurations shown in the drawings.

Claims

1. A light source unit, characterized in that: have: A substrate having a plurality of LEDs mounted on a first main surface; A first through hole, the center of which is located within a predetermined range from the center of gravity of the first main surface when viewed in a direction perpendicular to the first main surface of the substrate, and connects the first main surface of the substrate to a second main surface on the opposite side of the first main surface; a heat sink disposed on the second main surface side of the substrate; and The first fixing screw is inserted into the first through hole of the substrate and screwed into a screw hole provided corresponding to the first through hole, thereby fixing the substrate and the heat sink.

2. The light source unit according to claim 1, wherein: have: A second through hole is formed at a position where the distance from the first through hole is less than 55% of the maximum diagonal distance on the first main surface when viewed in a direction perpendicular to the first main surface of the substrate, connecting the first main surface of the substrate with the second main surface; and The second fixing screw is inserted into the second through hole of the substrate and screwed into a screw hole provided corresponding to the second through hole, thereby fixing the substrate and the heat sink.

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