JP7366337B2 - Manufacturing method of light source device and light source device - Google Patents

Description

Embodiments of the present invention relate to a method of manufacturing a light source device and a light source device.

2. Description of the Related Art Semiconductor light emitting diodes (LEDs) are increasingly being used in industrial and automotive applications due to improvements in functionality and performance.

In actual applications, it is necessary to fully consider how to handle the heat generated as the brightness increases. It is being considered to provide a module board that also serves as a heat sink and mount an LED on this module board to achieve high heat dissipation performance.

When mounting LEDs on a module board, it is necessary to ensure the bonding strength by preventing the bonding material from being damaged or broken due to stress caused by the difference in linear expansion coefficient between the module board and the mounting board on which the LED is mounted. There is.

Japanese Patent Application Publication No. 2015-185685 Japanese Patent Application Publication No. 2010-135503

The embodiment provides a method for manufacturing a light source device and a light source device that improves the bonding strength between a light emitting element and a module substrate.

A method for manufacturing a light source device according to an embodiment includes a step of arranging a bump containing a first metal on a first substrate having thermal conductivity, and a step of arranging a bonding member containing an Au-Sn alloy on the bump. and a step of arranging a light emitting element on the bump and the bonding member, and a step of heating the first substrate on which the bump, the bonding member and the light emitting element are arranged.

A method for manufacturing a light source device according to an embodiment includes the steps of: arranging bumps containing a first metal on a first substrate having thermal conductivity; and disposing a second metal having a melting point lower than that of the first metal on the bumps. a step of arranging a light-emitting element on the bump and the bonding member; The method further includes a step of heating at a temperature below the melting point of the first metal.

A method for manufacturing a light source device according to an embodiment includes the steps of: arranging bumps containing a first metal on a first substrate having thermal conductivity; and arranging a bonding member containing a second metal on the bumps. , a step of arranging a light emitting element on the bump and the bonding member, and a step of heating the first substrate on which the bump, the bonding member and the light emitting element are arranged, and sintering the second metal. Be prepared.

A method for manufacturing a light source device according to an embodiment includes the steps of: arranging a bonding member containing a second metal on a first substrate having thermal conductivity; and placing a bonding member containing a second metal on the bonding member having a higher melting point than the second metal. a step of arranging a light emitting element provided with bumps including one metal; and a step of arranging the first substrate on which the bonding member and the light emitting element provided with the bumps are arranged at a temperature higher than the melting point of the second metal, and the melting point of the first metal. A step of heating at a temperature below.

The light source device of the embodiment includes a first substrate having thermal conductivity, a light emitting element, and a bonding layer provided between the first substrate and the light emitting element. The bonding layer includes a first portion containing Ag and a second portion containing an Au-Sn alloy.

The light source device of the embodiment includes a first substrate having thermal conductivity, a light emitting element, and a bonding layer provided between the first substrate and the light emitting element. The bonding layer is an alloy containing Ag, Au, and Sn, and has a portion where the concentration of Ag is higher than the concentration of Au or Sn, and a portion where the concentration of Ag is lower than the concentration of Au or Sn.

The light source device of the embodiment includes a first substrate having thermal conductivity, a light emitting element, and a bonding layer provided between the first substrate and the light emitting element. The bonding layer has a third portion containing a first metal and a fourth portion containing a sintered body of a second metal.

In this embodiment, a method for manufacturing a light source device and a light source device with improved bonding strength between a light emitting element and a module substrate are realized.

FIG. 1 is a schematic plan view illustrating a light source module according to a first embodiment. FIG. 1A is a schematic cross-sectional view taken along line IB-IB' in FIG. 1A. FIG. 3 is a schematic cross-sectional view illustrating a method of manufacturing the light source module of the first embodiment. FIG. 3 is a schematic cross-sectional view illustrating a method of manufacturing the light source module of the first embodiment. FIG. 3 is a schematic cross-sectional view illustrating a method of manufacturing the light source module of the first embodiment. FIG. 3 is a schematic cross-sectional view illustrating a method of manufacturing the light source module of the first embodiment. FIG. 7 is a schematic plan view illustrating a light emitting module according to a second embodiment. FIG. 3B is a schematic cross-sectional view taken along line IIIB-IIIB' in FIG. 3A. FIG. 7 is a schematic cross-sectional view illustrating a method for manufacturing a light emitting module according to a second embodiment. FIG. 7 is a schematic cross-sectional view illustrating a method for manufacturing a light emitting module according to a second embodiment. FIG. 7 is a schematic cross-sectional view illustrating a method for manufacturing a light emitting module according to a second embodiment. FIG. 7 is a schematic cross-sectional view illustrating a method for manufacturing a light emitting module according to a second embodiment. FIG. 7 is a schematic cross-sectional view illustrating a method for manufacturing a light emitting module according to a second embodiment. FIG. 7 is a schematic cross-sectional view illustrating a light source module according to a third embodiment. 5A is a schematic enlarged cross-sectional view illustrating a part of the light source module of FIG. 5A. FIG. FIG. 7 is a schematic cross-sectional view illustrating a method of forming a joining member in a third embodiment. FIG. 6A is a schematic cross-sectional view enlarging a part of FIG. 6A. FIG. 7 is a schematic cross-sectional view illustrating a method of forming a joining member in a third embodiment. FIG. 7A is a schematic cross-sectional view enlarging a part of FIG. 7A. FIG. 7 is a schematic cross-sectional view illustrating a method of forming a joining member in a third embodiment. FIG. 8A is a schematic cross-sectional view enlarging a part of FIG. 8A. FIG. 7 is a schematic cross-sectional view illustrating a method of forming a joining member in a third embodiment. FIG. 9A is a schematic cross-sectional view enlarging a part of FIG. 9A. FIG. 7 is a schematic cross-sectional view illustrating a light source module according to a fourth embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
Note that the drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be shown differently depending on the drawing.
Note that in the present specification and each figure, the same elements as those described above with respect to the existing figures are denoted by the same reference numerals, and detailed explanations are omitted as appropriate.

(First embodiment)
FIG. 1A is a schematic plan view illustrating a light source module according to this embodiment.
FIG. 1B is a schematic cross-sectional view taken along line IB-IB in FIG. 1A.
As shown in FIGS. 1A and 1B, the light source module (light source device) 1 of this embodiment includes a module substrate 10, a bonding layer 20, and a light emitting module 50. Bonding layer 20 is provided between module substrate 10 and light emitting module 50. The light emitting module 50 includes a mounting board 30 and a light emitting element 40, and is bonded to the module substrate 10 by a bonding layer 20.

Bonding layer 20 includes bonding member 22 and bumps 24 . Bump 24 includes a first metal. The first metal is, for example, Ag. The joining member 22 includes a second metal. The second metal is, for example, an Au-Sn alloy. In the Au-Sn alloy, it is preferable that Au is 85% by weight or less and 70% by weight or more and Sn is 15% by weight or more and 30% by weight or less, and Au is preferably about 80% by weight and Sn is about 20% by weight. Particularly preferred. This is because by setting the Au--Sn alloy to a predetermined weight ratio, the melting point can be much lower than the melting point of the metal material (Ag, Cu, etc.) used for the bumps 24.

The bump (first portion) 24 is preferably arranged at the outer edge of the joining member 22 and at the center of the joining member 22, and more preferably at the corner of the joining member and the intersection of the diagonal line in plan view. preferable. Further, although FIG. 1A shows an example in which five bumps 24 are provided between the module board 10 and the mounting board 30, the bumps 24 may be provided at four locations or may be provided at six or more locations. Good too. Further, in a plan view, the area of the portion where the bumps 24 are provided is preferably 10% or less of the area of the mounting board 30. This is because it is possible to ensure bonding strength while keeping costs down.

The height of the bump 24 is set to an appropriate size depending on the thickness of the bonding layer 20. The bump 24 is preferably a ball bump having a ball shape. The bump is not limited to a ball bump, but may have another shape, such as a cylindrical shape. The height of the bump 24 is preferably 35 μm to 50 μm. The diameter of the bump 24 in plan view is about 70 μm.

The bump 24 is a member having a melting point sufficiently higher than the melting point of the joining member 22. The bumps 24 are preferably made of a material that is difficult to alloy when the molten joining member 22 is filled between the bumps 24 . The bump 24 contains, for example, Ag, as described above. The melting point of Ag is 962°C, which is higher than that of the Au-Sn alloy. Furthermore, any material other than Ag can be used as long as it has a higher melting point than the Au--Sn alloy, and metals are more preferred.

The bonding member (second portion) 22 fills the space between the module board 10 and the mounting board 30, fills the space between the module board 10 and the bumps 24, and fills the space between the bumps 24 and the mounting board 30. It is designed to be filled with. Therefore, the bonding layer 20 fills the space between the module board 10 and the mounting board 30 without any gaps.

The bonding member 22 is filled between the module board 10, the mounting board 30, and the bumps 24 without any gaps, thereby reducing the thermal resistance between the module board 10 and the mounting board 30, and improving the heat dissipation performance of the light source module 1. improve.

By filling the spaces between the module board 10, the mounting board 30, and the bumps 24 with the bonding member 22, cracks and the like are prevented from occurring in the bonding member 22 due to the application of thermal stress during use of the product.

The joining member 22 is a highly thermally conductive member having a melting point sufficiently higher than the operating temperature range and storage temperature range of the light source module 1. For example, a joining member containing an Au-Sn alloy such as Au-Sn eutectic solder is preferably used because it has high thermal conductivity and excellent thermal fatigue resistance.

When the bonding member 22 is made of an Au-Sn alloy, the thickness of the bonding layer 20 is preferably 35 μm or more. By setting the thickness of the bonding layer 20 to 35 μm or more, sufficient bonding strength can be ensured even under temperature cycle test conditions of −40° C. to +125° C., which are required in industrial applications, automotive applications, and the like.

The bonding layer 20 bonds the metal module substrate 10 and the insulating mounting substrate 30. Since the bonding layer 20 contains Au--Sn and has a sufficient thickness, the bonding can be maintained without causing cracks or the like due to stress caused by the difference in linear expansion coefficient between the two substrates.

The module board (first board) 10 is a plate-like member with high thermal conductivity. The area and thickness of the module substrate 10 are appropriately set depending on the heat generation of the light emitting module 50 to be mounted and the temperature of the environment in which the light source module 1 is used. The module substrate 10 is a metal plate material containing, for example, Cu or an alloy of Cu.

The mounting board (second board) 30 has a light emitting element 40 mounted on one surface, and together with the light emitting element 40 constitutes a light emitting module 50. A light emitting element 40 is fixed to the mounting board 30 via a bonding member (not shown), for example, an adhesive. The light emitting element 40 to be mounted is not limited and may include GaN, AlGaAs, GaAsP, InGaN, etc. There is no restriction on the color of the emitted light, and it can be visible light, infrared light, ultraviolet light, etc.

The mounting board 30 includes connection terminals 44a and 44b for the light emitting element 40 on the surface on which the light emitting element 40 is mounted. The mounting board 30 may include wiring for interconnecting the light emitting elements 40 and other circuit elements. The mounting board 30 has a shape and size that allows mounting the light emitting element 40 and providing connection terminals 44a and 44b on the anode side and cathode side for the light emitting element 40. In this example, the mounting board 30 is a plate-like member having a substantially rectangular shape including a space for mounting the rectangular parallelepiped light emitting element 40 and two rectangular connection terminals 44a and 44b. The dimensions of the mounting board 30 are set smaller than the module board 10.

The mounting board 30 is bonded to the module board 10 via the bonding layer 20 on the other surface. The mounting substrate 30 is, for example, a ceramic substrate, and includes AlN, Al ₂ O ₃ , mullite, or the like.

One end of the anode side connection wiring 34a is connected to the anode side connection terminal 44a of the mounting board 30, and the anode side external connection terminal 32a of the module board 10 is connected to the other end of the connection wiring 34a. . One end of the cathode side connection wiring 34b is connected to the cathode side connection terminal 44b of the mounting board 30, and the cathode side external connection terminal 32b of the module board 10 is connected to the other end of the connection wiring 34b. . The light source module 1 is supplied with power from the outside via the external connection terminals 32a and 32b, and the light emitting element 40 emits light.

The light source module 1 has a high heat dissipation performance because the light emitting module 50 is mounted on the module substrate 10 and the module substrate 10 is a member having high thermal conductivity.

Note that after the light source module 1 manufactured as described above is actually used and thermal stress is applied, alloying may progress between the bonding member 22 and the bumps 24 in the bonding layer 20. . For example, if the bump 24 is an Ag bump, Ag may diffuse into the bonding member 22, resulting in a shape different from the original shape. In other words, the bonding layer 20 is a layer having a portion where the concentration of Ag is higher than the concentration of Au or Sn, and a portion where the concentration of Ag is lower than the concentration of Au or Sn.

A method of manufacturing the light source module 1 of this embodiment will be described.
2A to 2D are schematic cross-sectional views illustrating the method for manufacturing the light source module of this embodiment.
As shown in FIG. 2A, bumps 24 are formed on the module substrate 10. Hereinafter, a manufacturing method will be described when the bumps 24 are formed at the four corners of the mounting board 30 and at the intersections of diagonal lines in a plan view. Note that the height of the bump 24 is preferably 35 μm to 50 μm when the bonding layer 20 is 35 μm or more.

The bump 24 has a melting point that is sufficiently higher than the melting point of the Au--Sn foil 22a, preferably 50° C. or more higher. Further, the bumps 24 are preferably made of metal because they need to have high thermal conductivity, but it is desirable that they are unlikely to form an alloy with the Au-Sn eutectic alloy when the Au-Sn foil 22a is melted. The melting point of Ag is about 962° C., and it is known that it is difficult to form an alloy with an Au-Sn eutectic alloy, so it is preferably included in the material of the bumps 24.

As shown in FIG. 2B, Au--Sn foil (joining member) 22a is placed on the five bumps 24. The shape and dimensions of the Au-Sn foil 22a in a plan view are set to be substantially the same as the shape and dimensions of the mounting board 30 in a plan view. The Au-Sn foil 22a is placed so that the four corners of the foil 22a are aligned with the bumps 24 arranged at the four corners of a rectangle in plan view.

The bumps 24 are arranged at positions such that when the Au-Sn foil 22a melts, the melt will not flow out from the outer edge of the mounting board 30. Not limited to the above-mentioned positions, for example, the bumps 24 may be arranged in any number at any position along the outer edge of the Au-Sn foil 22a having the same shape and dimensions as the mounting board 30 in plan view. may be done.

As shown in FIG. 2C, the light emitting module 50 on which the light emitting elements 40 are mounted is placed on the mounting board 30 so that the four corners of the mounting board 30 are aligned with the four corners of the Au-Sn foil 22a in plan view. While applying pressure F1 from above, the light emitting module 50 is heated as a whole to a temperature higher than the melting point of the Au--Sn foil 22a and sufficiently lower than the melting point of the bumps 24. The melting point of the Au--Sn foil 22a varies depending on the composition of the Au--Sn eutectic alloy of the Au--Sn foil 22a. For example, in the case of the bump 24 having an Au-Sn eutectic alloy composition of 20 wt % Sn and containing Ag with a melting point of 962° C., the heating setting temperature is preferably set to 280° C. or higher, for example, 350° C. or lower.

By being heated to a temperature higher than the melting point of the Au-Sn foil 22a, the Au-Sn foil 22a melts and fills the area around the bump 24 and the gap between the light emitting module 50 and the Au-Sn foil 22a. The pressure F1 is set to a value that melts the Au--Sn foil 22a and exhausts air around the bumps 24 and in the gaps created between the light-emitting module 50 and the Au--Sn foil 22a. By applying the pressure F1 during melting of the An-Sn foil 22a, generation of voids during solidification of the Au-Sn alloy is suppressed.

As shown in FIG. 2D, the module substrate 10, the bonding member 22, the bumps 24, and the light emitting module 50 are cooled to form a bonding layer 20, and the module substrate 10 and the light emitting module 50 are connected.

The module board 10 and the mounting board 30 may be bonded first, and the light emitting element 40 may be connected onto the bonded mounting board 30. At this time, when using a thermosetting adhesive to bond the mounting board 30 and the light emitting element 40, since the bonding layer 20 contains an Au-Sn alloy, the adhesive is cured at a temperature sufficiently lower than the melting point of the Au-Sn alloy. An adhesive having a temperature, such as an epoxy adhesive, is used.

The light source module 1 of this embodiment uses a bonding layer 20 containing an Au-Sn alloy to bond the module substrate 10 and the light emitting module 50. The module substrate 10 is made of a metal plate in order to improve the heat dissipation performance of the light source module 1, and in the case of Cu material, the linear expansion coefficient is 16.8×10 ⁻⁶ [K ⁻¹ ] That's about it. On the other hand, the mounting board uses an insulating member such as AlN for forming wiring and connection terminals, and in the case of AlN, the linear expansion coefficient is about 5×10 ⁻⁶ [K ⁻¹ ]. In other words, the linear expansion coefficients of the module substrate 10 and the mounting substrate 30 differ by a factor of three or more, and a large stress is applied to the bonding layer 20 when thermal stress is applied such as in a temperature cycle test. The bonding layer 20 needs to have sufficient bonding strength to prevent breakage such as cracks even in applications of industrial equipment having a wide operating temperature range and environmental temperature range from low to high temperatures.

Since the light source module 1 of this embodiment provides the bumps 24 between the module substrate 10 and the light emitting module 50, the bonding layer 20 can be made sufficiently thick. Therefore, thermal stress between the module substrate 10 and the light emitting module 50 can be absorbed, and the bonding strength between the module substrate 10 and the light emitting module 50 can be made sufficiently high.

In the method for manufacturing the light source module 1 of this embodiment, the bumps 24 are formed in advance at the positions where the Au-Sn foil 22a is placed. Therefore, the Au-Sn foil 22a and the light emitting module 50 can be arranged with high precision.

The bumps 24 are made of a metal material having a melting point sufficiently higher than that of the Au--Sn foil 22a, for example, a metal material containing Ag. Therefore, when the Au-Sn foil 22a melts, the molten material of the Au-Sn eutectic alloy may flow out from the placement position of the bumps 24 due to the solder wettability of the bumps 24 and the mutual frictional holding force with the bumps. can be prevented. Therefore, the thickness of the bonding layer 20 is maintained equal to or greater than the height of the bump, and by appropriately setting the height of the bump 24, the bonding layer 20 can be made to have a desired thickness.

By using the bumps 24 as Ag bumps and setting the height to 35 μm to 50 μm, the thickness of the bonding layer 20 can be 35 μm or more. By setting the thickness of the bonding layer 20 to 35 μm or more, it can withstand 3000 cycles or more in a temperature cycle test from −40° C. to +125° C. The temperature cycle test is performed in accordance with, for example, standards such as JEDEC (Joint Electron Device Engineering Council), IEC (International Electrotechnical Commission), and AEC (Automotive Electronics Council).

In the method for manufacturing the light source module 1 of this embodiment, the bumps 24 are provided not only at the four corners of the Au--Sn foil 22a but also at the intersections of diagonal lines of the Au--Sn foil 22a. Therefore, even if one of the five bumps has an abnormal height, the light emitting module 50 can be placed without the top surface of the light emitting module 50 tilting significantly with respect to the bottom surface of the module substrate 10. can.

In the above, it has been described that the Au-Sn foil 22a containing the Au-Sn eutectic alloy is used as the bonding member 22 when the light source module is used in the temperature range required for industrial equipment, automotive equipment, etc. Depending on specifications such as the operating temperature range of the light source module, the joining member may have a different thickness or may be made of a different material. For example, when the light source module is used in a narrower temperature range, the thickness of the Au--Sn foil may be made thinner, and the height of the bump may also be reduced depending on the thickness of the Au--Sn foil. When the light source module is used in an even narrower temperature range, an alloy having a melting point lower than that of the Au--Sn eutectic alloy may be used, and a bump containing a metal having a melting point sufficiently higher than that alloy may be used.

(Second embodiment)
In the embodiment described below, the light emitting module can be further miniaturized by placing the light emitting element directly on a metal bump and a bonding member containing metal and mounting it on a mounting board with high mounting accuracy. .
FIG. 3A is a schematic plan view illustrating the light emitting module according to this embodiment.
FIG. 3B is a schematic cross-sectional view taken along line IIIB-IIIB' in FIG. 3A.
As shown in FIGS. 3A and 3B, the light emitting module (light source device) 250 includes a mounting substrate 230, a bonding layer 220, and a plurality of light emitting elements 240. The bonding layer 220 is provided between the mounting substrate 230 and the plurality of light emitting elements 240, and bonds the mounting substrate 230 and the plurality of light emitting elements 240, respectively.

In this embodiment, the light emitting element 240 is placed on the mounting board 230 provided with the bumps 224 and bonded by the bumps 224 and the bonding member 222. Therefore, the positional shift of the light emitting element 240 after mounting is reduced by the mutual frictional holding force between the light emitting element 240 and the bumps 224, and the like. Therefore, the mounting accuracy of the light emitting elements 240 on the mounting board 230 is improved, and a plurality of light emitting elements 240 can be mounted on the mounting board 230 at a narrower pitch. Further, in a plan view, the area of the portion where the bumps 224 are provided is preferably 5% or less of the area of the light emitting element 240. This is because it is possible to ensure bonding strength while keeping costs down.

The light emitting element 240 is mounted in the mounting area 232 of the mounting board 230. The mounting area 232 has a shape that is a projection of the light emitting element 240 to be placed when the light emitting element 240 is placed on the mounting substrate 230. In this example, since the four light emitting elements 240 are arranged in a line, it has a rectangular shape corresponding to the four light emitting elements 240. The mounting area 232 is provided with lands corresponding to the anode terminal and cathode terminal of the light emitting element 240. The anode terminal and cathode terminal of the light emitting element 240 are electrically connected to other electric circuits via lands. In this example, along the direction in which the four light emitting elements 240 are arranged, they are arranged like a land corresponding to an anode terminal and a land corresponding to a cathode terminal. Each land is interconnected according to the connection of each light emitting element 240 and the connection with other circuits.

The bonding layer 220 is formed according to the shape of the anode terminal of the light emitting element 240 and the shape of the land corresponding to this anode terminal. Similarly, the bonding layer 220 is formed according to the shape of the cathode terminal of the light emitting element 240 and the shape of the land corresponding to this cathode terminal. In this example, since the four light emitting elements 240 are connected in series, the bonding layer formed on the cathode terminal and the corresponding land of the light emitting element 240 is formed on the anode terminal and the corresponding land of the adjacent light emitting element 240. It is continuous with the attached bonding layer and is also electrically connected to it.

It is preferable that the bumps 224 are arranged at the outer edges of each of the plurality of light emitting elements 240. As in this example, it is more preferable to arrange the light emitting elements 240 at the corners of each light emitting element 240 in plan view. If the light emitting element 240 has a large dimension in plan view, bumps 224 may be provided at the intersections of diagonal lines of the light emitting element, as in the other embodiments described above. By arranging a large number of bumps under the light emitting element, it is possible to absorb the inclination when the light emitting element is mounted due to dimensional errors of the bumps, etc., and it is possible to ensure sufficient mounting accuracy. As in the case of the other embodiments described above, the bumps 224 are formed of a metal material having a melting point sufficiently higher than the melting point of the bonding member 222 constituting the bonding layer 220, and include, for example, Ag.

A light emitting element 240 is provided on the mounting board 230 with a bonding layer 220 interposed therebetween. The light emitting element 240 is directly bonded to the mounting substrate 230 by the bonding layer 220.

Bonding layer 220 includes a bonding member 222 and bumps 224. The bonding member 222 is provided to fill the space between the mounting board 230 and the light emitting element 240, the space between the mounting board 230 and the bump 224, and the space between the bump 224 and the light emitting element 240. ing. Therefore, the bonding layer 220 fills the spaces between the mounting substrate 230, the bumps 224, and the light emitting elements 240 without any gaps. By filling the bonding layer 220 without any gaps, the thermal resistance of the light emitting module 250 can be reduced, and cracks in the bonding layer 220 due to thermal stress can be prevented.

The joining member 222 is a highly thermally conductive member having a melting point sufficiently higher than the operating temperature range and storage temperature range of the light emitting module 250, and is a joining member containing, for example, an Au-Sn eutectic alloy.

When the bonding member 222 is an Au-Sn eutectic alloy, the thickness of the bonding layer 220 is preferably 35 μm or more. By setting the thickness of the bonding layer 220 to 35 μm or more, sufficient bonding strength can be ensured even under temperature cycle test conditions of −40° C. to +125° C., which are required in industrial applications, automotive applications, and the like.

The bonding layer 220 serves to bond the mounting substrate 230 and the light emitting element 240, and has stress resistance due to the difference in linear expansion coefficient between the two members. By having a sufficient thickness of the bonding layer 220 containing Au--Sn, bonding strength can be ensured without causing cracks or the like due to stress due to the difference in coefficient of linear expansion of the two members.

A method for manufacturing the light emitting module 250 of this embodiment will be described.
4A to 4E are schematic cross-sectional views illustrating the method for manufacturing the light emitting module of this embodiment.
As shown in FIG. 4A, bumps 224 are formed on the mounting board 230. Hereinafter, a manufacturing method will be described in which the bumps 224 are Ag bumps and are formed at four corner positions of each light emitting element 240 in a plan view.

As shown in FIG. 4B, Au--Sn foil 222a is placed so as to cover all bumps 224. The Au-Sn foil 222a is placed so that the four corners of the Au-Sn foil 222a are aligned with the bumps 224 arranged at the four corners of the mounting area 232. The Au-Su foil 222a has a rectangular shape that is almost the same as the mounting area of the light emitting element 240 in plan view.

Further, as shown in FIG. 4C, an Au--Sn foil 222a having a rectangular shape substantially the same as the mounting area may be placed on the mounting board 230. In this case, the bumps are formed in advance on the light emitting element side.

As shown in FIG. 4D, the light emitting element 240 is placed on the Au--Sn foil 222a in plan view. For example, the light emitting elements 240 are sequentially placed starting from the light emitting elements 240 at the ends. When the light emitting element 240 is placed, it is placed so as to match the position of the bump 224. While applying pressure F2 from above the light emitting element 240, the entire light emitting element 240 is heated to a high temperature. The heating temperature is set based on the composition of the Au-Sn eutectic alloy of the Au-Sn foil 222a and the melting point of the bumps 224, as in the first embodiment. For example, when the composition of the Au-Sn eutectic alloy is 20 wt% Sn, the set temperature is preferably 280° C. or more and 350° C. or less.

At a temperature equal to or higher than the melting point of the Au-Sn foil 222a, the Au-Sn foil 222a melts so as to fill the periphery of the bump 224 and the gap between the light emitting element 240 and the Au-Sn foil 222a. The pressure F2 melts the Au--Sn foil 222a and exhausts air around the bump 224 and in the gap between the light-emitting element 240 and the Au--Sn foil 222a, thereby suppressing the generation of voids.

As shown in FIG. 4E, when melted, the Au-Sn foil 222a bonds the anode terminal of each light emitting element 240 to the land on the mounting area 232 corresponding to the anode terminal due to its solder wettability. Similarly, the Au-Sn foil 222a bonds the cathode terminal of the light emitting element 240 to the land on the mounting area 232 corresponding to the cathode terminal.

The mounting board 230, the bonding member 222, the bumps 224, and the light emitting element 240 are cooled, and the melted bonding portion forms the bonding layer 220 and connects the mounting board 230 and the light emitting element 240.

In the light emitting module 250 of this embodiment, the bumps 224 are provided between the mounting substrate 230 and the light emitting elements 240, so the bonding layer 220 can be made sufficiently thick. Therefore, the bonding strength between the mounting board 230 and the light emitting element 240 can be made sufficiently high.

In this embodiment, since the light emitting elements 240 are connected to the mounting board 230 by the bumps 224 and the bonding members 222, it is possible to improve the mounting accuracy, and it is possible to mount the light emitting elements 240 at a narrower pitch. become.

(Third embodiment)
FIG. 5A is a schematic cross-sectional view illustrating the light source module according to this embodiment.
FIG. 5B is a schematic enlarged cross-sectional view illustrating a part of the light source module of FIG. 5A.
As shown in FIGS. 5A and 5B, the light source module 301 of this embodiment includes a module substrate 10, a bonding layer 320, and a light emitting module 50. In the light source module 301 of this embodiment, the structure of the bonding layer 320 is different from that of the other embodiments described above. Hereinafter, the same components will be denoted by the same reference numerals, and detailed explanations will be omitted as appropriate.

In the light emitting module 50, a light emitting element 40 is provided on a mounting board 30. The bonding layer 320 is provided between the module board 10 and the mounting board 30.

Bonding layer 320 includes bonding member 322 and bumps 24 . The bump (third portion) 24 contains the first metal. The first metal includes, for example, one or more metals selected from the group consisting of Au, Ag, and Cu.

The joining member (fourth portion) 322 includes a metal portion 322a and a resin portion 322b. The metal portion 322a is formed by combining a plurality of metal powders 322a1. The metal portion 322a contains metal, for example, is made of pure metal. The metal portion 322a includes, for example, one or more metals selected from the group consisting of Au, Ag, and Cu. It may be made of the same metal as the bump 24 or may be made of a different metal.

The resin portion 322b includes a resin material. A part of the resin portion 322b is arranged between the metal powders 322a1. The resin material is a thermosetting resin, such as an epoxy resin, as will be described later.

Within the joining member 322, there may be a portion where the resin portion 322b is not necessarily provided. An air gap may be formed where the resin portion 322b is not provided between the metal powders 322a1.

The bonding member 322b is made by heat-treating a so-called Ag paste in which Ag particles are dispersed in a resin binder, for example. In this case, the bumps 24 may contain Ag, for example.

A method for forming the joining member 322 in this embodiment will be explained.
FIG. 6A is a schematic cross-sectional view illustrating a method of forming a joining member in this embodiment.
FIG. 6B is a schematic cross-sectional view enlarging a portion of FIG. 6A.
FIG. 7A is a schematic cross-sectional view illustrating a method of forming a joining member in this embodiment.
FIG. 7B is a schematic cross-sectional view enlarging a part of FIG. 7A.
FIG. 8A is a schematic cross-sectional view illustrating a method of forming a joining member in this embodiment.
FIG. 8B is a schematic cross-sectional view enlarging a part of FIG. 8A.
FIG. 9A is a schematic cross-sectional view illustrating a method of forming a joining member in this embodiment.
FIG. 9B is a schematic cross-sectional view enlarging a part of FIG. 9A.

As shown in FIGS. 6A and 6B, a paste (joining member) 322c in which metal powder 322a1 is dispersed in a resin liquid 322b1 is prepared, and the paste 322c is applied onto the module substrate 10 on which the bumps are arranged. As already explained in FIG. 2A, the module substrate 10 on which bumps are arranged is prepared. The arrangement positions of the bumps and the heights of the bumps are the same as in the other embodiments described above.

The paste 322c may be applied to the mounting board 30 side instead of being applied to the module board 10 side, or may be applied to both the module board 10 and the mounting board 30. The paste 322c is, for example, a so-called Ag paste in which Ag particles are dispersed in a resin binder.

The resin liquid 322b1 of the paste 322c contains a resin material, an organic solvent, and the like. The metal powder 322a1 contains a metal, for example, a pure metal, and contains, for example, one or more metals selected from the group consisting of Au, Ag, and Cu. The particle size of the metal powder 322a1 is, for example, 1 μm or less, preferably 500 nm or less, and more preferably 100 nm or less. By reducing the particle size, it becomes easier to sinter the metal particles. In the applied paste 322c, the metal powder 322a1 is almost uniformly dispersed in the resin liquid 322b1.

As shown in FIGS. 7A, 7B, 8A, and 8B, the organic solvent in the paste 322c is evaporated, and the resin material in the paste 322c is hardened. For example, a structure consisting of the module board 10 and the mounting board 30 coated with the paste 322c is heated to a temperature of 200° C. or lower while applying pressure F3 from the mounting board 30 side. The organic solvent is removed from the resin liquid 322b1 by pressure and heating, the metal powders 322a1 come into contact with each other, and the resin material in the resin liquid 322b1 is hardened to form a solid resin portion 322b. At the same time, metal diffuses between the metal powders 322a1 via the contact points between the metal powders 322a1.

As shown in FIGS. 9A and 9B, metal powder 322a1 is sintered. For example, while applying pressure F3 from the side of the mounting board 30, the structure consisting of the metal powder 322a1, the resin portion 322b, the module board 10, and the mounting board 30 is heated to a temperature lower than the melting point of the metal powder 322a1, for example, 180° C. or higher and 250° C. Heat to a temperature below °C. As a result, the metal powders 322a1 are sintered together to form the metal portion 322a. At this time, a part of the resin portion 322b remains between the metal powders 322a1. In this way, the joining member 322 is formed, and the module board 10 and the mounting board 30 are joined.

The steps in FIGS. 7A to 9B can be performed continuously as a series of steps. For example, the bonding member 322 can be formed by gradually increasing the ambient temperature while maintaining a constant pressure applied from the mounting board 30 side.

In the light source module 301 of this embodiment, the paste 322c containing the metal powder 322a1 contains a resin and an organic solvent. Therefore, it can be easily applied to the members to be joined, and a temporary connection between the members to be joined can be ensured, so that the manufacturing process can be made simpler.

In this embodiment, the bonding layer 320 can be formed at a lower temperature than when Au--Sn foil is used as the bonding member. Therefore, thermal stress exerted on the light emitting element 40 and the like during manufacturing can be reduced.

In the light source module 301 of this embodiment, the metal portion 322a, which is a dense sintered body of metal powder, can be formed by sintering the metal powder 322a1, so that low thermal resistance can be achieved.

In the metal portion 322a of the light source module 301 of this embodiment, the resin portion 322b and the void exist between the metal powders 322a1 included in the metal portion 322a, so stress due to temperature stress etc. can be absorbed. Therefore, environmental resistance due to temperature stress and the like can be improved.

(Fourth embodiment)
The joining member described in the third embodiment can also be applied to the second embodiment.
FIG. 10 is a schematic cross-sectional view illustrating the light source module according to this embodiment.
As shown in FIG. 10, the light emitting module (light source device) 450 includes a mounting board 230, a bonding layer 420, and a plurality of light emitting elements 240. The bonding layer 420 is provided between the mounting substrate 230 and the plurality of light emitting elements 240, and bonds the mounting substrate 230 and the plurality of light emitting elements 240, respectively.

In this embodiment, the bonding layer 420 is substantially the same as the bonding layer 420 in the third embodiment. Bonding layer 420 includes bonding member 322 and bumps 224. As already described in FIG. 5B, the joining member 322 includes a metal portion 322a and a resin portion 322b. The configuration of the joining member 322 is thus similar to that of the third embodiment. Further, the components other than the joining member 322 are the same as in the second embodiment. That is, in this embodiment, the light emitting element 240 can be bonded to the mounting substrate 230 via the bonding layer 420.

Bonding layer 420 can be formed in the same manner as in the third embodiment.

According to the embodiments described above, it is possible to realize a method for manufacturing a light source device and a light source device in which the bonding strength between the light emitting element and the module substrate is improved.

Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention, as well as within the scope of the claimed invention and its equivalents. Further, each of the embodiments described above can be implemented in combination with each other.

1,301 Light source module, 10 Module board, 20,220,320,420 Bonding layer, 22,222,322 Bonding member, 22a, 222a Au-Sn foil, 24,224 Bump, 30,230 Mounting board, 32a, 32b External connection terminal, 34a, 34b connection wiring, 40, 240 light emitting element, 44a, 44b connection terminal, 50, 250, 450 light emitting module, 322a metal part, 322a1 metal powder, 322b resin part, 322b1 resin liquid, 322c paste

Claims (19)

arranging bumps containing a first metal on a first substrate having thermal conductivity;
arranging a bonding member containing a second metal having a melting point lower than the melting point of the first metal on the bump;
arranging a light emitting element on the bump and the bonding member;
heating the first substrate on which the bump, the bonding member, and the light emitting element are arranged at a temperature below the melting point of the first metal;
Equipped with
the first metal is Ag,
A method for manufacturing a light source device, wherein the height of the bump is 35 μm or more and 50 μm or less. arranging a bonding member containing a second metal on a first substrate having thermal conductivity;
arranging, on the bonding member, a light emitting element provided with a bump containing a first metal having a melting point higher than the melting point of the second metal;
heating the first substrate on which the bonding member and the light emitting element provided with the bumps are arranged at a temperature below the melting point of the first metal;
Equipped with
the first metal is Ag,
A method for manufacturing a light source device, wherein the height of the bump is 35 μm or more and 50 μm or less. 3. The method of manufacturing a light source device according to claim 1 , wherein the bump is arranged at least at an outer edge of the joining member and at a center of the joining member. The joining member has a rectangular shape in plan view,
4. The method for manufacturing a light source device according to claim 1 , wherein the bump is arranged at an intersection between a corner of the joining member and a diagonal line. arranging bumps containing a first metal on a first substrate having thermal conductivity;
arranging a bonding member containing an Au-Sn alloy on the bump;
arranging a light emitting element on the bump and the bonding member;
heating the first substrate on which the bump, the bonding member, and the light emitting element are arranged;
connecting the light emitting element to an insulating second substrate;
Equipped with
The method for manufacturing a light source device, wherein the light emitting element is arranged on the bump and the bonding member via the second substrate. arranging bumps containing a first metal on a first substrate having thermal conductivity;
arranging a bonding member containing a second metal having a melting point lower than the melting point of the first metal on the bump;
arranging a light emitting element on the bump and the bonding member;
heating the first substrate on which the bump, the bonding member, and the light emitting element are arranged at a temperature below the melting point of the first metal;
connecting the light emitting element to an insulating second substrate;
Equipped with
The method for manufacturing a light source device, wherein the light emitting element is arranged on the bump and the bonding member via the second substrate. arranging a bonding member containing a second metal on a first substrate having thermal conductivity;
arranging, on the bonding member, a light emitting element provided with a bump containing a first metal having a melting point higher than the melting point of the second metal;
heating the first substrate on which the bonding member and the light emitting element provided with the bumps are arranged at a temperature below the melting point of the first metal;
connecting the light emitting element to an insulating second substrate;
Equipped with
The method for manufacturing a light source device, wherein the light emitting element is arranged on the bump and the bonding member via the second substrate. 5. The method for manufacturing a light source device according to claim 1 , wherein the light emitting element is placed directly on the bump and the bonding member. arranging bumps containing a first metal on a first substrate having thermal conductivity;
arranging a bonding member containing a second metal on the bump;
arranging a light emitting element on the bump and the bonding member;
heating the first substrate on which the bump, the bonding member, and the light emitting element are arranged, and sintering the second metal;
Equipped with
the first metal is Ag,
A method for manufacturing a light source device, wherein the height of the bump is 35 μm or more and 50 μm or less. a first substrate having thermal conductivity;
A light emitting element,
a bonding layer provided between the first substrate and the light emitting element;
Equipped with
The bonding layer is
a bump that is a first portion containing Ag;
a second portion including an Au-Sn alloy;
including;
the bump is surrounded by the second portion;
In the light source device, the thickness of the bonding layer is 35 μm or more. The light source device according to claim 10 , wherein the first portion is arranged at least at an outer edge portion of the bonding layer and a center portion of the bonding layer in plan view. The bonding layer has a rectangular shape in plan view,
The light source device according to claim 11 , wherein the first portion is arranged at least at an intersection of a corner of the bonding layer and a diagonal line. a first substrate having thermal conductivity;
A light emitting element,
a bonding layer provided between the first substrate and the light emitting element;
Equipped with
The bonding layer is
A light source device that is an alloy containing Ag, Au, and Sn, and has a portion where the concentration of Ag is higher than the concentration of Au or Sn, and a portion where the concentration of Ag is lower than the concentration of Au or Sn. a first substrate having thermal conductivity;
A light emitting element,
a bonding layer provided between the first substrate and the light emitting element;
Equipped with
The bonding layer has a bump that is a third portion that includes a first metal, and a fourth portion that includes a sintered body of a second metal,
the first metal is Ag,
In the light source device, the thickness of the bonding layer is 35 μm or more. a first substrate having thermal conductivity;
A light emitting element,
a bonding layer provided between the first substrate and the light emitting element;
Equipped with
The bonding layer is
a first portion containing Ag;
a second portion including an Au-Sn alloy;
including;
A light source device further comprising an insulating second substrate provided between the light emitting element and the bonding layer. a first substrate having thermal conductivity;
A light emitting element,
a bonding layer provided between the first substrate and the light emitting element;
Equipped with
The bonding layer is
An alloy containing Ag, Au and Sn, having a portion where the concentration of Ag is higher than the concentration of Au or Sn, and a portion where the concentration of Ag is lower than the concentration of Au or Sn,
A light source device further comprising an insulating second substrate provided between the light emitting element and the bonding layer. a first substrate having thermal conductivity;
A light emitting element,
a bonding layer provided between the first substrate and the light emitting element;
Equipped with
The bonding layer has a third portion containing a first metal and a fourth portion containing a sintered body of a second metal,
A light source device further comprising an insulating second substrate provided between the light emitting element and the bonding layer. The light source device according to claim 10 , wherein the light emitting element is directly bonded to the bonding layer . The light source device according to claim 10 , wherein the first portion has a spherical shape or a cylindrical shape.

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