JP6572083B2 - Light emitting element substrate, module, and method for manufacturing light emitting element substrate - Google Patents

Description

  The present invention relates to a light emitting element substrate, a module, and a method for manufacturing a light emitting element substrate.

  In recent years, as an alternative to conventional cathode ray tube type monitors, various types of devices such as liquid crystal televisions using light-emitting elements such as LEDs as backlight sources can be used to meet the demands for lower power consumption, larger and thinner devices. The spread of LED display devices is rapidly progressing.

  In order to mount a light emitting element as a light source in these display devices, various types of light emitting element substrates each including a support substrate and a wiring portion are usually used. A laminate in which a light emitting element is mounted on these substrates (in this specification, a laminate having such a configuration is referred to as a “module”) is widely used as a light source for the various LED display devices described above. ing.

  Conventionally, a rigid substrate in which a light emitting element is mounted on a rigid substrate made of a glass epoxy plate or the like has been widely adopted as a substrate for a light emitting element. However, in recent years, LED display devices have become larger and display screens have become more diversified. In recent years, development of flexible substrates in which metal circuits are formed on flexible substrates such as resin sheets has been progressing (patents). Reference 1). A flexible substrate has higher design freedom and higher productivity than a rigid substrate, and is expected to be further spread in the future.

  However, light resistance is required for a light emitting element substrate on which the light emitting element is mounted. This is because in the case of a light emitting element substrate having low light resistance, the light emitting element substrate is deteriorated by receiving light from the light emitting element, and in some cases, a hole is generated in the light emitting element substrate. In particular, when a blue light emitting element capable of emitting blue light having a low wavelength is mounted, the influence on the light emitting element substrate is large.

  In order to solve such a problem, Patent Document 2 discloses a light-emitting element substrate that includes a light-blocking member that blocks light from the light-emitting element in an adhesive layer that bonds a metal wiring portion.

JP 2012-59867 A JP, 2015-12206, A

  However, when the adhesive layer that bonds the metal wiring portion is used as a reflective layer, the adhesive layer contains a pigment such as titanium oxide. However, when a certain amount or more of pigment is contained, the strength of the adhesive may be lowered. An object of the present invention is to provide a light-emitting element substrate having light resistance to light from a light-emitting element without reducing the strength of an adhesive layer that bonds a metal wiring part.

  As a result of intensive studies, the present inventors have found that the above problem can be solved if the surface roughness Rz of the translucent adhesive layer in the groove between the metal wiring parts is specified, The present invention has been completed.

  (1) A flexible substrate, a metal wiring portion formed on at least one surface side of the flexible substrate via a translucent adhesive layer, and a groove portion formed between the metal wiring portions A substrate for a light-emitting element, having a surface roughness Rz of the translucent adhesive layer in the groove portion of 10 μm or less.

  (2) A module in which a light-emitting element is mounted on the light-emitting element substrate according to (1).

  (3) The module according to (2), wherein the light emitting element mounted on the light emitting element substrate is a blue light emitting element.

  (4) The module according to (2) or (3), wherein the light emitting element has an emission wavelength peak at 430 nm or more and 470 nm or less.

  (5) The module according to any one of (2) to (4), wherein an underfill containing a light reflecting member is disposed between the translucent adhesive layer and the light emitting element.

  (6) Furthermore, a sealing member for sealing the light emitting element on the flexible substrate is disposed, and the sealing member is an epoxy resin, a modified epoxy resin, a silicone resin, or a modified silicone resin. The module according to any one of 2) to (5).

  (7) A step of laminating a metal layer on at least one surface side of the flexible substrate via a light-transmitting adhesive layer, and cleaning the metal layer after etching to provide a space between the metal wiring portion and the metal wiring portion. A step of forming the groove portion, and in the step of laminating the metal layer, the surface of the metal foil having a surface roughness Rz of 10 μm or less is laminated so as to face the translucent adhesive layer. A method for manufacturing a substrate for a light emitting device.

  The light-emitting element substrate of the present invention is a light-emitting element substrate that has light resistance to light from the light-emitting element without reducing the strength of the adhesive layer that bonds the metal wiring portion.

It is a fragmentary sectional view of the module of the present invention, and is a mimetic diagram for explaining the mounting mode of the light emitting element in the module of the present invention. It is a perspective view which shows typically the outline of the layer structure of the image display apparatus which uses the module of this invention. It is the figure which represented typically that an etching residue remains on the surface of the translucent adhesive layer 12 because the surface roughness Rz of the surface of a translucent adhesive layer is over fixed. 3 is a SEM photograph showing a surface state of a light-transmitting adhesive layer in a groove portion of a light emitting element substrate of Example 1. FIG. 4 is a SEM photograph showing a surface state of a light-transmitting adhesive layer in a groove portion of a light emitting element substrate of Comparative Example 1. It is a fragmentary sectional view of the module of other embodiments of the present invention.

  Hereinafter, each embodiment of the board | substrate for light emitting elements of this invention and a module is demonstrated. The present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention.

<Light emitting element substrate>
An embodiment of a light emitting element substrate of the present invention will be described. As shown in FIG. 1, the light emitting element substrate of the present embodiment on which the light emitting element 2 can be mounted has a conductive metal wiring portion 13 made of a metal layer or the like on the surface of the flexible substrate 11. It is formed via the photoadhesive layer 12. The light emitting element 2 can be provided on the metal wiring. Further, as shown in FIG. 1, a surface reflection layer 16 may be laminated around the periphery. When the surface reflection layer 16 is provided, the surface reflection layer 16 may be laminated on the substrate via an adhesive layer or the like. The surface reflection layer 16 is not an essential constituent element of the present invention.

  When providing the surface reflective layer 16, it is preferable that the reflectance in wavelength 450nm is 80% or more. For example, a thermosetting resin containing 10% by mass or more and 80% by mass or less of a white pigment such as titanium oxide can be used. In addition, it is more preferable that a titanium oxide is 30 to 80 mass%. Titanium oxide is most preferable from the viewpoint of the difference in refractive index, but instead of or together with titanium oxide, aluminum oxide, silicon oxide, titanium oxide, magnesium oxide, antimony oxide, aluminum hydroxide, barium sulfate, You may use the at least 1 or more types of pigment chosen from magnesium carbonate, barium carbonate, and a glass filler.

  Examples of the thermosetting resin include a mixture of a fluororesin and an acrylic resin, a silicone resin, and an epoxy resin. From the viewpoint of adhesion to the translucent adhesive layer, a mixture of a fluororesin and an acrylic resin is preferable. The thermosetting resin is preferably hard.

[Flexible substrate]
The flexible substrate is not particularly limited, but a thermoplastic resin is preferably used. The material for the flexible substrate is required to have high heat resistance and insulation. As such a resin, polyimide resin (PI) or polyethylene naphthalate (PEN) which is excellent in heat resistance, dimensional stability during heating, mechanical strength, and durability can be used. Among them, polyethylene naphthalate (PEN) that has been improved in heat resistance and dimensional stability by performing heat resistance improvement treatment such as annealing treatment can be preferably used. In addition, polyethylene terephthalate (PET) whose flame retardancy is improved by adding a flame retardant inorganic filler or the like can also be selected as a material resin for the flexible substrate.

  It is preferable to use a flexible substrate having a thermal shrinkage start temperature of 100 ° C. or higher, or a substrate having improved heat resistance so that the temperature becomes 100 ° C. or higher by the above-described annealing treatment or the like. The peripheral portion of the element reaches a temperature of about 90 ° C. by heat generated from the normal light emitting element. From this viewpoint, it is preferable that the thermoplastic resin forming the substrate resin has heat resistance equal to or higher than the above temperature.

The light emitting element substrate is required to be a resin having an insulating property that can provide the insulating property required for the light emitting element substrate when the LED display device is integrated as a backlight or the like. In general, the substrate has a volume resistivity of preferably 10 ¹⁴ Ω · cm or more, and more preferably 10 ¹⁸ Ω · cm or more. The volume resistivity can be measured by using, for example, a digital ultra high resistance / microammeter 5450/5451 manufactured by ADC.

  The thickness of the flexible substrate is not particularly limited, but in the case of a flexible resin substrate, it is approximately 10 μm or more and 100 μm or less from the viewpoint of the balance between heat resistance and insulation and manufacturing cost. Preferably there is. Also, the thickness is preferably within the above-mentioned thickness range from the viewpoint of maintaining good productivity when manufacturing by the roll-to-roll method.

[Translucent adhesive layer]
The surface roughness Rz (meaning the ten-point average roughness defined by JIS B0601) of the translucent adhesive layer 12 in the groove portion 17 in the present embodiment is 10 μm or less. As shown in FIG. 1, the groove portion 17 is a surface where the metal wiring portion 13 is not laminated and the translucent adhesive layer is exposed, and refers to the surface of the translucent adhesive layer. When manufacturing the metal wiring part 13, it is common to manufacture by forming a pattern by etching the metal layer manufactured through the translucent adhesive layer between the flexible substrate and the metal layer. . The substrate for a light-emitting element of the present invention is characterized in that light resistance to blue light mainly from a blue light-emitting element is improved by setting the surface roughness Rz of the light-transmitting adhesive layer in the groove to 10 μm or less. . The blue light emitting element means a light emitting element capable of emitting blue light having a wavelength of 430 nm to 500 nm. In addition, it is more preferable that the surface roughness Rz of the translucent adhesive layer 12 in the groove portion 17 constituting the light emitting element substrate is 5 μm or less, particularly 1 μm or less. The smaller the surface roughness Rz, in other words, the smaller the surface roughness, the more light-emitting element substrate can be provided.

  The reason why the light resistance of the flexible substrate 11 is lowered due to the surface roughness Rz of the surface of the translucent adhesive layer 12 exceeding a certain value, and the reason why the flexible substrate 11 has a hole is not necessarily clear. However, when the surface roughness Rz of the translucent adhesive layer 12 exceeds a certain level, the area of the surface of the translucent adhesive layer 12 increases, and the etching residue 18 generated during the etching becomes the translucent adhesive layer 12. It tends to remain in a recess or the like on the surface. The amount of light absorbed from the light emitting element in the translucent adhesive layer 12 is increased by the etching residue 18. And the energy of the light absorbed by the translucent adhesive layer 12 is converted into thermal energy, and the translucent adhesive layer 12 generates heat. It is presumed that when the light-transmitting adhesive layer 12 generates heat, a hole is formed in the light-transmitting adhesive layer 12 and a hole is also formed in the flexible substrate 11 that is laminated in layers (see FIG. 3).

  In addition, it is preferable that the surface roughness Rz of the translucent adhesive layer in the groove part regarding this embodiment is 0.1 μm or more. When the surface roughness Rz of the light-transmitting adhesive layer is 0.1 μm or more, the adhesive strength at the interface between the metal wiring portion 13 and the light-transmitting adhesive layer can be improved.

  The shape of the surface of the translucent adhesive layer 12, that is, the surface roughness of the translucent adhesive layer 12, is opposite to the translucent adhesive layer 12 of a metal foil of a metal layer laminated on the surface of the translucent adhesive layer 12, for example. It depends on the shape of the surface on the side. That is, in the step of laminating the metal layer at the time of etching, the surface of the metal foil having a predetermined surface roughness Rz is laminated so as to face the translucent adhesive layer 12, thereby translucent the groove 17. The surface roughness Rz of the adhesive layer 12 can be controlled.

  As the adhesive forming the light-transmitting adhesive layer 12, a known resin adhesive can be used as appropriate. Of these resin adhesives, urethane-based, polycarbonate-based, or epoxy-based adhesives can be particularly preferably used. The translucent adhesive layer means an adhesive layer that transmits 85% or more of the total visible light. The translucent adhesive layer 12 can also contain a light reflecting member in the translucent resin. Thereby, the arrival of light to the flexible substrate can be reduced. Examples of the light reflecting member include white pigments such as titanium oxide. Moreover, you may contain various inorganic fillers.

[Metal wiring section]
The metal wiring part 13 is a wiring pattern formed on the surface of the light emitting element substrate 1 by a conductive base material such as a metal layer.

  The arrangement of the metal wiring part 13 is not limited to a specific arrangement as long as the light emitting element can be mounted. However, in the light emitting element substrate, it is preferable that at least 80% or more, preferably 90% or more preferably 95% or more of one surface of the substrate is covered with the metal wiring portion 13. Thereby, it can contribute to the improvement of the heat dissipation calculated | required in the module using the metal wiring part 13 and the board | substrate for light emitting elements.

200 W / (m · K) or more is preferable, and 300 W / (m · K) or more is more preferable as the thermal conductivity λ of the metal constituting the metal wiring portion 13. The metal resistivity R constituting the metal wiring part 13 is preferably 3.00 × 10 ⁻⁸ Ω · m or less, more preferably 2.50 × 10 ⁻⁸ Ω · m or less. Here, the measurement of the thermal conductivity λ can use, for example, a thermal conductivity meter QTM-500 manufactured by Kyoto Electronics Industry Co., Ltd., and the measurement of the electrical resistivity R can be performed, for example, a 6517B type electrometer manufactured by Keithley. Can be used. According to this, for example, in the case of copper, the thermal conductivity λ is 403 W / (m · K), and the electrical resistivity R is 1.55 × 10 ⁻⁸ Ω · m. Thereby, both heat dissipation and electrical conductivity can be achieved. More specifically, since the heat dissipation from the light emitting element 2 is stabilized and an increase in electrical resistance can be prevented, the variation in light emission between the light emitting elements is reduced, and the light emitting elements can stably emit light. Life is extended. Further, since deterioration of peripheral members such as a substrate due to heat can be prevented, the product life of the image display device itself incorporating the light emitting element substrate 1 as a backlight can be extended.

  The surface resistance value of the metal wiring portion 13 is preferably 500Ω / □ or less, more preferably 300Ω / □ or less, further preferably 100Ω / □ or less, and particularly preferably 50Ω / □ or less. The lower limit is about 0.005Ω / □.

  As a metal used as a material of the metal wiring part 13, metal layers, such as aluminum, gold | metal | money, silver, copper, and those alloy layers can be illustrated. The thickness of the metal wiring portion 13 may be set as appropriate according to the magnitude of the current resistance required for the light emitting element substrate, and is not particularly limited. Examples thereof include a thickness of 10 μm to 50 μm. From the viewpoint of improving heat dissipation, the thickness of the metal wiring portion 13 is preferably 10 μm or more. Further, if the metal layer thickness is less than the lower limit, the influence of thermal contraction of the substrate is large, and the warp after the treatment is likely to increase during the solder reflow process. From this viewpoint, the thickness of the metal wiring portion 13 is 10 μm. The above is preferable. When the thickness is 50 μm or less, sufficient flexibility can be maintained, and a decrease in handling property due to an increase in weight can be prevented.

[Solder layer]
In the light emitting element substrate, the metal wiring part 13 and the light emitting element 2 are preferably bonded via the solder layer 14. This joining by soldering can be performed by, for example, a reflow method or a laser method.

[Insulating protective film]
The insulating protective film 15 is not an essential constituent element in the present invention. However, when the insulating protective film is provided, as described above, the metal wiring portion is made of thermosetting ink, UV curable ink, or coverlay film. 13 and other portions excluding a portion that requires electrical bonding on the surface of the light emitting element substrate, mainly for improving the migration resistance of the light emitting element substrate.

  As the thermosetting ink, a known ink can be suitably used as long as the thermosetting temperature is about 100 ° C. or less. Specifically, as a representative example of an ink that can preferably use an insulating ink having a polyester resin, an epoxy resin, an epoxy resin and a phenol resin, an epoxy acrylate resin, a silicone resin, or the like as a base resin, respectively. Can be mentioned. Of these, polyester-based thermosetting insulating ink is particularly preferable as a material for forming the insulating protective film 15 of the light emitting element substrate 1 because of its excellent flexibility.

  The thermosetting ink for forming the insulating protective film 15 may be a white ink further containing an inorganic white pigment such as titanium dioxide. By whitening the insulating protective film 15, it is possible to improve the reflectance and design of the light emitting device.

  The formation of the insulating protective film 15 using the above insulating thermosetting ink can be performed by a known method such as screen printing.

  When using a coverlay film, it can be formed by applying an adhesive to a highly heat-resistant resin film such as a polyimide resin and affixing on the flexible substrate 11.

[Surface reflection layer]
The surface reflective layer 16 is not an essential constituent element in the present invention. However, in the case where the surface reflective layer 16 is provided, in the present embodiment, the light emission capability is improved in the module 10 for the purpose of improving the light emission capability. It is laminated on the outermost surface on the light emitting surface side of the element substrate except for the mounting portion of the light emitting element 2. It is not particularly limited as long as it is a member having a reflecting surface for reflecting the light emitted from the light emitting element and guiding it in a predetermined direction, but white polyester foam type white polyester, white polyethylene resin, silver deposited polyester, etc. And can be used as appropriate according to the required specifications.

[Light emitting element]
The light emitting element 2 is disposed on the light emitting element substrate. The light emitting element 2 has a pair of electrodes on one surface, and is electrically connected to the metal wiring portion 13 through the pair of electrodes. The light emitting element 2 used here is not particularly limited in shape or size. A light emitting color of the light emitting element 2 can be selected depending on the application, but a light emitting element that emits blue light can be used. The blue light emitting element means a light emitting element capable of emitting light having a wavelength of 430 nm or more and 500 nm or less. For example, a blue light emitting element having an emission peak at 430 nm to 470 nm is preferably used. As the light emitting element 2, a GaN system or an InGaN system can be used. The _{InGaN-based, In X Al Y Ga 1-} X-Y N (0 ≦ X ≦ 1,0 ≦ Y ≦ 1, X + Y <1) , or the like can be used.

[Underfill]
FIG. 6 is a partial cross-sectional view of a module according to another embodiment of the present invention. An underfill 21 may be disposed between the light-transmitting adhesive layer 12 and the light emitting element 2 as in the module of the embodiment of FIG. The underfill 21 can increase the bonding strength between the light emitting element 2 and the translucent adhesive layer 12. The underfill 21 is preferably a thermosetting resin such as an epoxy resin or a silicone resin. The underfill 21 is preferably made of a material that enhances the bonding strength with the translucent adhesive layer 12, and the underfill 21 and the translucent adhesive layer 12 are preferably made of the same material, but are different materials. Also good.

  The underfill 21 preferably contains an adsorbent 22 that adsorbs iron and / or copper. Thereby, the penetration | invasion of the iron and / or copper to the translucent adhesive layer 12 can be prevented. The underfill 21 preferably contains a light reflecting member made of a white pigment such as titanium oxide. Thereby, the light from the light emitting element 2 can be efficiently emitted to the outside. In particular, the surface of the adsorbent 22 is preferably coated with titanium oxide. This is because the light emitted from the light emitting element 2 can be prevented from being absorbed by the adsorbent 22 and can have a high light reflectance. The light reflecting member is preferably titanium oxide, but instead of or together with titanium oxide, aluminum oxide, silicon oxide, titanium oxide, magnesium oxide, antimony oxide, aluminum hydroxide, barium sulfate, magnesium carbonate, carbonic acid At least one pigment selected from barium and glass filler may be used.

  The particle size of the light reflecting member contained in the underfill 21 is preferably 5 μm or less, particularly preferably 1 μm or less, and more preferably 0.5 μm or less. Accordingly, it is possible to suppress the light reflecting member from entering the concave portion on the surface of the light-transmitting adhesive layer and reaching the light from the light emitting element to the flexible substrate.

[Sealing member]
A sealing member 19 that seals the light emitting element 2 is preferably disposed on the flexible substrate 11. This is because the light emitting element 2 can be protected from dust and moisture. The sealing member 19 is preferably one of an epoxy resin, a modified epoxy resin, a silicone resin, and a modified silicone resin.

[Phosphor]
The sealing member 19 may contain the phosphor 20. The phosphor 20 absorbs light from the light emitting element 2 and emits light of different wavelengths, and emits light of green, yellow, red, and the like. As the phosphor 20, an oxide phosphor such as YAG or silicate, a nitride phosphor such as CASN or SCASN, a fluoride phosphor such as KSF, or the like can be used.

<Method for manufacturing substrate for light emitting element>
The substrate for a light emitting element is not particularly limited, and can be manufactured by a conventionally known method for manufacturing an electronic substrate. For example, it can be manufactured through the etching process described below. Further, it is preferable to subject the resin in advance to a heat resistance improving process by annealing according to the material resin to be selected.

[Annealing treatment]
Although not essential in the present invention, conventionally known heat treatment means can be used when annealing is performed. As an example of the annealing treatment temperature, when the resin substrate is PEN, it is in the range of the glass transition temperature to the melting point, more specifically in the range of 160 ° C. to 260 ° C., more preferably 180 ° C. to 230 ° C. An example of the annealing time is about 10 seconds to 5 minutes. According to such heat treatment conditions, the thermal contraction start temperature of PEN, which is generally about 80 ° C., can be improved to about 100 ° C.

[Etching process]
By stacking the metal wiring part 13 of the metal layer used as the material of the metal wiring part on the surface of the resin substrate that has undergone the annealing treatment, a laminated body that uses the material of the light emitting element substrate can be obtained. As a lamination method, a metal layer is laminated on at least one surface side of a flexible substrate via a light-transmitting adhesive layer, or a plating method or a vapor deposition method is directly applied to the surface of the flexible substrate. Examples thereof include a method of depositing the metal wiring portion 13 by sputtering, ion plating, electron beam deposition, vacuum deposition, chemical vapor deposition, or the like. From the viewpoint of cost and productivity, a method of bonding the metal layer to the surface of the flexible substrate with a urethane adhesive is advantageous.

  When a metal layer is laminated on at least one surface side of the flexible substrate via a translucent adhesive layer, a surface having a surface roughness Rz of 10 μm or less of the metal foil as the metal layer is disposed on the translucent adhesive layer 12. It is preferable to laminate so as to face each other. By setting the surface roughness Rz of the metal foil, which is a metal layer, to 10 μm or less, the surface roughness Rz of the translucent adhesive layer in the groove portion 17 according to this embodiment can be set to 10 μm or less. Therefore, it is possible to easily manufacture a light emitting element substrate in which the surface roughness Rz of the translucent adhesive layer in the groove portion of this embodiment is 10 μm or less. When the surface roughness Rz of the translucent adhesive layer in the groove is 10 μm or less, the amount of light absorbed from the light emitting element can be reduced. In addition, it is more preferable to laminate | stack so that the surface roughness Rz of the metal foil which is a metal layer may be 1 micrometer or less so that the translucent adhesive layer 12 may be opposed. The translucent adhesive layer 12 may contain various inorganic fillers.

  The method for producing the metal foil includes a rotating drum anode that is partially immersed in an electrolytic bath, and an arcuate cathode that is spaced from the rotating drum anode and faces the rotating drum anode. A metal foil can be produced by a method of making a metal foil by electrodepositing a metal and finally peeling the metal foil having a predetermined thickness from the drum. The copper foil produced by this method has a glossy surface (hereinafter referred to as a mirror surface) whose surface roughness is very close to the rotating drum at the time of foil production, and the opposite surface is relatively It becomes a roughened surface (hereinafter referred to as a matte surface) having a large surface roughness. Therefore, for example, if the side surface close to the rotating drum side is laminated so as to face the translucent adhesive layer 12, the surface roughness Rz of the translucent adhesive layer in the groove portion according to the present embodiment is 10 μm. It can be as follows.

  Here, an example in which the groove portion between the metal wiring portions 13 is formed from the above laminate will be described. An etching mask patterned in the shape of the metal wiring portion 13 is formed on the surface of the metal layer of the laminate. In the future, the etching mask is provided so that the wiring pattern forming portion of the metal layer to be the metal wiring portion 13 is free from corrosion by the etching solution. The method for forming the etching mask is not particularly limited. For example, the etching mask may be formed on the surface of the laminated sheet by exposing the photoresist or dry film through the photomask and then developing the ink mask. An etching mask may be formed on the surface of the laminated sheet by this printing technique.

  Next, the metal layer in a portion that is not covered with the etching mask is removed with an immersion liquid. Thereby, a metal wiring part and the groove part 17 between metal wiring parts can be formed. Finally, the etching mask is removed using an alkaline stripping solution. As a result, the etching mask is removed from the surface of the metal wiring portion 13.

  In addition, when the etching residue 18 at the time of etching is soaked into the translucent adhesive layer by a certain amount or more, the translucent adhesive layer turns yellow and absorbs blue light, so that the translucent adhesive layer generates heat, There may be holes in the translucent adhesive layer and the flexible substrate. Therefore, the amount of chlorine and / or the amount of iron or copper measured by scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX) from the surface side of the translucent adhesive layer 12 in the groove portion 17 is 1% by mass. It is preferable to perform etching and cleaning so as to be less than 0.7, more preferably less than 0.7% by mass.

  In the present invention, the amount of chlorine and / or the amount of iron or copper is measured from the surface side of the translucent adhesive layer in the groove by scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX). The measurement method is based on quantitative conditions unique to the SEM-EDX analyzer (for example, JEM SEM “JSM-6700F” and Oxford Instruments EDX “XMAX80” acceleration voltage 15 kV, focal length 15 mm, sample tilt 0 degree). In addition, a characteristic X-ray spectrum is acquired by adjusting the irradiation current and measurement time in a timely manner so that the target element can be sufficiently detected, and the concentration of each element is determined by the ZAF correction method (atomic number correction Z and absorption correction for the relative intensity of each element The amount of chlorine and / or the amount of iron or copper can be determined by A, a method of applying fluorescence correction F to determine the content of each element). It is also possible to determine the chlorine content, iron content, and copper content from the cross-sectional side.

[Insulating protective film and surface reflection layer forming step]
After the formation of the metal wiring portion, an insulating protective film 15 and a surface reflection layer 16 are further laminated as necessary. These laminations can be performed by a known method. Depending on the material to be employed, various laminating methods such as screen printing, dry lamination, thermal lamination, and the like can be used.

<Module>
The module 10 can be obtained by mounting a light emitting element on the light emitting element substrate 1 described above. The module 10 can be used as a backlight of the LED image display device 100 as shown in FIG.

  A method for manufacturing the module 10 using the light emitting element substrate 1 will be described. Bonding of the light emitting element 2 to the metal wiring portion 13 can be preferably performed by soldering. This solder bonding can be performed by a reflow method or a laser method. In the reflow method, the light emitting element 2 is mounted on the metal wiring part 13 via solder, and then the light emitting element substrate is transported into the reflow furnace, and hot air of a predetermined temperature is blown to the metal wiring part 13 in the reflow furnace. In this method, the solder paste is melted to attach the light emitting element 2 to the metal wiring portion 13. The laser method is a technique in which solder is locally heated by a laser to solder the light emitting element 2 to the metal wiring portion 13. The solder material may be Sn-Bi-based, Sn-Cu-based, Sn-Ag-Cu-based solder or the like in accordance with the heat resistance of the flexible substrate.

  When performing solder bonding of the light emitting element 2 to the metal wiring part 13, it is preferable to use a method of performing solder reflow by laser irradiation from the back side of the light emitting element substrate. As a result, it is possible to more reliably suppress the ignition of the organic components of the solder due to heating and the accompanying damage to the flexible substrate.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

<Creation of light emitting element substrate>
Example 1
As an example of the LED display device of the present invention, a transparent support layer is applied to a copper plate (thickness 35 μm) having a surface roughness Rz of 0.5 μm on a copper mirror surface on the surface of a film-like support substrate having a size of 400 mm × 500 mm. A metal wiring portion made of an electrolytic copper layer (“KTEP”, manufactured by Rock Paint Co., Ltd.) was subjected to an etching process (laminated with the electrolytic copper layer mirror surface facing the flexible substrate side), and a light emitting device substrate A test sample was prepared.
As the flexible substrate, 75 μm thick polyethylene naphthalate (PEN) was used.
When the amount of chlorine and the amount of iron were measured by scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX) from the surface side of the translucent adhesive layer in the groove, the amount of chlorine was 0.3% by mass. The iron content was 0.3% by mass. The thickness of the translucent adhesive layer was 10 μm.

(Example 2)
In the above etching process, a copper plate having a copper mat surface with a surface roughness Rz of 6 μm was used, a light-transmitting adhesive layer was laminated on the copper mat surface, and the metal wiring part was etched. A sample for testing a substrate for a light emitting device was manufactured.

(Comparative Example 1)
In the above etching process, a copper plate having a copper mat surface with a surface roughness Rz of 13 μm was used, a translucent adhesive layer was laminated on the copper mat surface, and the metal wiring part was etched, as in Example 1 above. A sample for testing a substrate for a light emitting device was manufactured.

<SEM observation>
SEM photographs were taken at a magnification of 2000 times for the surface of the translucent adhesive layer in the groove of the light emitting element substrate of Example 1 and Comparative Example 1. SEM photographs are shown in FIGS. According to the SEM photograph, the surface of the light-transmitting adhesive layer in the groove portion of the light-emitting element substrate of Example 1 has smaller irregularities than the surface of the light-transmitting adhesive layer in the groove portion of the light-emitting element substrate of Comparative Example 1. I understand that.

<Light resistance test>
For the light-emitting element substrates of Examples and Comparative Examples, as an accelerated test of the light resistance test, a blue laser (a laser diode manufactured by Nichia Chemical Co., Ltd., wavelength 450 nm, output 0.5 W) was irradiated from above the translucent adhesive layer in the groove. The time when the film was perforated was measured. The measurement results are shown in Table 1 below.

<Wiring adhesion test>
About each light emitting element substrate of an Example and a comparative example, the adhesive strength in the following test conditions was measured and metal adhesiveness was evaluated.
In the measurement, the metal wiring portion in close contact with the flexible substrate in the light emitting element substrate is subjected to a vertical peeling (50 mm / min) test using a peeling tester (Tensilon universal testing machine RTF-1150-H). Table 1 shows the measurement results.

(In Table 1, the transmittance means the transmittance of light having a wavelength of 380 nm or more and 780 nm or less.)

  From Table 1, the substrates for light emitting devices of Examples 1 and 2 in which the surface roughness Rz of the translucent adhesive layer is 10 μm or less are compared with Comparative Example 1 in which the surface roughness Rz of the translucent adhesive layer is more than 10 μm. And the time required to perforate is longer. In particular, in the light emitting element substrate of Example 1 in which the surface roughness Rz of the light-transmitting adhesive layer is 1 μm or less, the time required for perforation is 3 hours or more, and the time required for perforation is significantly increased. Yes. This is presumably because the surface roughness Rz of the translucent adhesive layer in the groove portion decreased, and the amount of light absorbed from the light emitting element in the translucent adhesive layer decreased. For this reason, it turns out that the board | substrate for light emitting elements of this invention whose surface roughness Rz of a translucent adhesive layer is 10 micrometers or less is a light emitting element substrate which has the light resistance with respect to the light from a light emitting element.

DESCRIPTION OF SYMBOLS 1 Substrate for light emitting elements 11 Flexible substrate 12 Translucent adhesive layer 13 Metal wiring part 14 Solder layer 15 Insulating protective film 16 Surface reflective layer 17 Groove part 18 Etching residue 10 Module 2 Light emitting element 3 Display screen 4 Heat radiation part 19 Sealing Stop member 20 Phosphor 21 Underfill 22 Adsorbent 100 LED image display device

Claims (7)

A flexible substrate; a metal wiring portion formed on at least one surface of the flexible substrate via a light-transmitting adhesive layer; and a groove portion formed between the metal wiring portions. And
The light emitting element use substrate whose surface roughness Rz of the said translucent adhesive layer in the said groove part exceeds 5.0 micrometers, and is 10 micrometers or less.   A module in which a light emitting element is mounted on the light emitting element substrate according to claim 1.   The module of Claim 2 whose light emitting element mounted in the said board | substrate for light emitting elements is a blue light emitting element.   4. The module according to claim 2, wherein the light emitting element has a light emission wavelength peak at 430 nm or more and 470 nm or less.   The module as described in any one of Claims 2 thru | or 4 by which the underfill containing a light reflection member is arrange | positioned between the said translucent adhesive layer and the said light emitting element. Furthermore, a sealing member for sealing the light emitting element on the flexible substrate is disposed,
The module according to any one of claims 2 to 5, wherein the sealing member is an epoxy resin, a modified epoxy resin, a silicone resin, or a modified silicone resin. Laminating a metal layer on at least one surface side of the flexible substrate with a translucent adhesive layer interposed therebetween;
Cleaning the metal layer after etching to form a metal wiring part and a groove part between the metal wiring parts, and
In the step of laminating the metal layer , the surface of the metal layer having a surface roughness Rz of more than 5.0 μm and 10 μm or less is laminated so as to face the translucent adhesive layer. Method.