JP6918452B2 - Substrate and module for light emitting element - Google Patents

Description

The present invention relates to a light emitting element substrate and a module.

In recent years, as an alternative to conventional CRT-type monitors, various types such as LCD TVs that use light-emitting elements such as LEDs as a backlight source can meet the demands for lower power consumption, larger and thinner devices. The spread of light-emitting display devices is rapidly advancing.

In order to mount a light emitting element as a light source in these display devices, various light emitting element substrates 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 the present specification, a laminate having such a configuration is referred to as a "module") is widely used as a light source for the above-mentioned various LED display devices. ing.

Conventionally, as a substrate for a light emitting element, a rigid substrate in which a light emitting element is mounted on a rigid substrate made of a hard glass epoxy plate or the like having no flexibility has been widely adopted. However, in recent years, as the size of LED display devices has increased and the form of display screens has diversified, so-called flexible circuit boards in which metal circuits are formed on flexible resin substrates have been developed (see Patent Document 1). Flexible circuit boards, which have flexibility, have a higher degree of freedom in design and higher productivity than rigid boards, and are expected to become more widespread in the future.

However, in a light emitting element substrate in which a light emitting element is mounted on this flexible circuit board, excellent light resistance to light from the light emitting element is required. 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 holes may be generated in some cases. In particular, when a blue light emitting element that emits blue light having a low wavelength is mounted, a substrate for the light emitting element is required to have particularly high light resistance.

In response to such a problem, Patent Document 2 discloses a substrate for a light emitting element, which includes a light shielding member that blocks light from the light emitting element in an adhesive layer for adhering a metal wiring portion. In the examples of Patent Document 2, an example is disclosed in which an adhesive contains 3 wt% of carbon black to form an adhesive layer with a thickness of 10 μm.

Japanese Unexamined Patent Publication No. 2012-59867 JP 2015-12206

When a light-shielding member is contained in the adhesive layer as in the substrate for a light emitting element disclosed in Patent Document 2, the thickness of the adhesive layer and the content of the light-shielding member are limited, so that the light-shielding is insufficient. Material deterioration cannot be effectively prevented. First, as is clear from the description of the above-mentioned examples, the thickness of the adhesive layer is limited to about 10 μm, and if the thickness is larger than this, the adhesive layer is coagulated and broken, and the adhesiveness is lowered. Resulting in. Further, since the content of the filler hinders the adhesive function, the amount of the light-shielding member that can be contained is also limited to several wt% as in the above embodiment, and if the amount is more than this, it adheres to the resin base material. The property is significantly reduced and peeling occurs at the interface between the adhesive layer and the resin base material.

As described above, the inclusion of the light-shielding member in the adhesive layer does not sufficiently block the light from the light emitting element, particularly the blue light, resulting in deterioration of the base material.

In view of the above problems, the present invention provides a substrate for a light emitting element having excellent light resistance to light from a light emitting element while maintaining the adhesive strength of the adhesive layer for adhering the metal wiring portion within a preferable range. The purpose.

As a result of diligent research, the present inventors have found that a substrate for a light emitting element having a reflective layer between a resin substrate and an adhesive layer can solve the above problems, and have completed the present invention. rice field.

(1) It has a flexible resin substrate and a metal wiring portion formed on at least one surface side of the resin substrate via an adhesive layer, and is between the resin substrate and the adhesive layer. A reflective layer is arranged therein, and the reflective layer contains a thermosetting resin and a light-reflecting filler, and the content of the light-reflective filler is 10% by mass or more 85. A substrate for a light emitting element having a mass% or less and a reflectance of 80% or more at a wavelength of 450 nm.

(2) The substrate for a light emitting element according to (1), wherein the thickness of the reflective layer is 5 μm or more and 250 μm or less.

(3) The light emitting element according to (1) or (2), wherein the adhesive layer does not contain a light-reflecting filler or has a content of the light-reflecting filler of 40% by mass or less. substrate.

(4) A module in which a light emitting element is mounted on the light emitting element substrate according to any one of (1) to (3).

(5) The module according to (4), wherein the light emitting element is a blue light emitting element.

(6) The module according to (4) or (5), wherein the peak of the emission wavelength of the light emitting element is 430 nm or more and 470 nm or less.

(7) The module according to any one of (4) to (6), wherein an underfill is arranged between the adhesive layer and the light emitting element.

(8) A sealing member for sealing the light emitting element is arranged on the resin substrate, and the sealing member is one or more materials selected from epoxy resin, modified epoxy resin, silicone resin, and modified silicone. The module according to any one of (4) to (7), comprising.

The substrate for a light emitting element of the present invention is a substrate for a light emitting element which has excellent light resistance to light from the light emitting element while maintaining the adhesive strength of the adhesive layer for adhering the metal wiring portion within a preferable range.

It is a partial cross-sectional view of the module of this invention, and is the schematic diagram which provides for the explanation of the mounting mode of the light emitting element in the module of this invention. It is a perspective view which shows the outline of the layer structure of the image display device which comprises the module of this invention typically. It is a graph which showed the measurement result of the transmittance of Examples 1 and 2 and Comparative Example 1. It is a partial cross-sectional view of the module of another embodiment of this invention.

Hereinafter, embodiments of the light emitting element substrate, module, and display device of the present invention will be described. The present invention is not limited to the following embodiments, and can be carried out with appropriate modifications within the scope of the object of the present invention.

<Substrate for light emitting element>
The substrate for a light emitting element of the present invention will be described. In the light emitting element substrate 1 according to the present invention, as shown in FIG. 1, the reflective layer 18 is arranged on the surface of the flexible resin substrate 11. Then, on the surface of the reflective layer 18, a conductive metal wiring portion 13 made of a metal layer or the like is formed via the adhesive layer 12. Further, the light emitting element substrate 1 may be provided with a surface reflective material 16 on the outermost surface thereof in a manner of covering a portion other than a region where the light emitting element 2 is mounted.

[Reflective layer]
The reflective layer 18 is a resin layer containing a thermosetting resin and a light-reflecting filler and having light reflectivity. Specifically, the light reflectivity of the reflective layer 18 may be as long as the reflectance at a wavelength of 450 nm is 80% or more, preferably 85% or more. When the reflectance at a wavelength of 450 nm is 80% or more, preferably 85% or more, among the light from the light emitting element 2, blue light having a wavelength of about 450 nm, which has at least high energy and a high risk of damage to the resin substrate, is produced. Since it is possible to suppress the arrival at the resin substrate 11, the risk of damage such as holes in the resin substrate 11 due to the light from the light emitting element 2 can be sufficiently reduced. The reflectance at a wavelength of 450 nm is determined by, for example, an ultraviolet-visible spectrophotometer UV- 2550) can be used to determine the reflectance (%) of light when light is incident.

Further, the reflective layer 18 uses a thermosetting resin as a main resin, and contains a light-reflective filler such as various white pigments described below in a predetermined amount range. In order to make the reflectance of the reflective layer 18 at a wavelength of 450 nm 80% or more, preferably 85% or more, the content of the light-reflecting filler in the reflective layer 18 may be 10% by mass or more and 85% by mass or less. , 30% by mass or more and 85% by mass or less is more preferable. The light-reflecting filler contained in the reflective layer 18 is white such as titanium oxide, aluminum oxide, silicon oxide, titanium oxide, magnesium oxide, antimony oxide, aluminum hydroxide, barium sulfate, magnesium carbonate, barium carbonate and glass filler. At least one or more pigments selected from the pigments can be used. Further, among these, titanium oxide having a refractive index of about 2.5 can be most preferably used from the viewpoint that it is preferable that the difference in refractive index between the resin and the main resin is larger.

Examples of the thermosetting resin used for the reflective layer 18 include a mixture of a fluororesin and an acrylic resin, a silicone resin, an epoxy resin, and the like. The thermosetting resin having adhesiveness to the adhesive layer 12 preferably has a high glass transition temperature (TG).

Examples of the fluororesin used in the above-mentioned mixture of the fluororesin and the acrylic resin include a copolymer of tetrafluoroethylene and a hydroxyl group-containing vinyl ether, a copolymer of chlorotrifluoroethylene and a hydroxyl group-containing vinyl ether, and the like. Will be done. Among these, a copolymer of chlorotrifluoroethylene and a hydroxyl group-containing vinyl ether is preferably used. Examples of such resins include copolymers of chlorotrifluoroethylene, diethylene glycol monoallyl ether, and vinyl butyrate having a mass average molecular weight of 1,000 or more and 30,000 or less and a hydroxyl value of 5 mg / g or more and 200 mg / g or less.

Examples of the acrylic resin used in the mixture of the above fluororesin and the acrylic resin include hydroxyl groups such as -2-hydroxyethyl acrylate, -2-hydroxypropyl acrylate, and -2-hydroxy-3-phenoxypropyl acrylate. As acrylic acid or alkyl group, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group Examples thereof include those obtained by copolymerizing an alkyl acrylate-based monomer having a above-mentioned property and the like. Further, as the monomer used for copolymerization, acrylamide, N-alkylacrylamide, N, N-dialkylacrylamide (as the alkyl group, methyl group, ethyl group, n-propyl group, i-propyl group, n-Butyl group, i-butyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.), N-alkoxyacrylamide, N, N-dialkoxyacrylamide (alkoxy groups include methoxy group and ethoxy). Groups, butoxy groups, isobutoxy groups, etc.), amide group-containing monomers such as N-methylolacrylamide and N-phenylacrylamide, glycidyl group-containing monomers such as glycidyl acrylate and allyl glycidyl ether, styrene, α-methylstyrene, vinyl. Methyl ether, vinyl ethyl ether, maleic acid, alkyl maleic acid monoester, fumaric acid, alkyl fumarate monoester, itaconic acid, alkyl itaconic acid monoester, acrylonitrile, vinylidene chloride, ethylene, propylene, vinyl chloride, vinyl acetate, butadiene Various compounds having an ethylenically unsaturated bond such as, etc. may be used. Among these, a copolymer of methyl acrylate and 2-ethylhexyl acrylate, and a copolymer of methyl acrylate, 2-ethylhexyl acrylate and hydroxyethyl acrylate are preferably used. Moreover, a preferable mass average molecular weight of such a resin is 1000 or more and 300,000 or less.

The reflective layer 18 can be formed, for example, by applying a coating liquid containing these resins and a curing agent and drying the coating liquid. For example, it can be formed by reacting a resin compound having a plurality of crosslinkable substituents with a polyisocyanate compound having an NCO group and curing the compound.

The thickness of the reflective layer 18 is preferably 5 μm or more and 250 μm or less, more preferably 10 μm or more and 100 μm or less, and particularly preferably 20 μm or more and 50 μm or less. If the thickness of the reflective layer 18 is less than 5 μm, the reflective layer 18 may be peeled off or chipped because it cannot sufficiently follow the deformation of the flexible resin substrate 11, which is not preferable. On the other hand, if the thickness of the reflective layer exceeds 250 μm, it becomes difficult to maintain sufficient flexibility of the light emitting element substrate 1, and there is a possibility that the handleability may be lowered due to the increase in weight.

The reflective layer 18 described above has a reflectance of 80% or more at a wavelength of 450 nm. Therefore, the light emitting element substrate 1 provided with this is particularly useful as a substrate for a blue light emitting element.

[Resin substrate]
The resin substrate 11 is not particularly limited as long as it is in the form of a flexible film or sheet, but it is preferable to use a thermoplastic resin. As used herein, the term "flexible" means that the radius of curvature can be bent to a radius of curvature of usually 1 m, preferably 50 cm, more preferably 30 cm, still more preferably 10 cm, and particularly preferably 5 cm.

However, the material of the resin substrate 11 is required to have predetermined heat resistance and insulating properties according to the purpose of use. As such a resin, a polyimide resin (PI) having excellent heat resistance, dimensional stability during heating, mechanical strength, and durability, or polyethylene naphthalate (PEN) can be used. Among them, polyethylene naphthalate (PEN) whose heat resistance and dimensional stability are improved by subjecting it to a heat resistance improving treatment such as an annealing treatment can be preferably used. Further, polyethylene terephthalate (PET) whose flame retardancy is improved by adding a flame-retardant inorganic filler or the like can also be selected as the material resin of the resin substrate 11.

As the resin substrate 11, it is preferable to use one having a heat shrinkage start temperature of 100 ° C. or higher, or one having improved heat resistance so that the same temperature becomes 100 ° C. or higher by the above annealing treatment or the like. Normally, the heat generated from the light emitting element causes the temperature around the element to reach a temperature of about 90 ° C. From this point of view, it is preferable that the thermoplastic resin forming the substrate resin has heat resistance equal to or higher than the above temperature.

The "heat shrinkage start temperature" in the present specification means that a sample film made of a thermoplastic resin to be measured is set in a TMA device, a load of 1 g is applied, and the temperature rises to 120 ° C. at a heating rate of 2 ° C./min. Warm, measure the amount of shrinkage (% display) at that time, output this data and read the temperature away from the 0% baseline due to shrinkage from the graph that recorded the temperature and amount of shrinkage, and heat shrink that temperature It is the starting temperature. Further, the "thermosetting temperature" in the present specification is calculated by measuring and calculating the temperature at the rising position of the thermosetting reaction when the thermosetting resin to be measured is heated, and that temperature is taken as the thermosetting temperature. ..

Further, the light emitting element substrate 1 is required to be a resin having an insulating property capable of imparting the insulating property required for the light emitting element substrate when integrated as a backlight of an LED display device or the like, for example. Be done. In general, the volume resistivity of the substrate is ^{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 / micro ammeter 5450/5451 manufactured by ADC.

The thickness of the resin substrate is not particularly limited, but in the case of a flexible resin substrate, it should be about 10 μm or more and 100 μm or less from the viewpoint of the balance between heat resistance and insulation and manufacturing cost. Is preferable. Further, from the viewpoint of maintaining good productivity in the case of manufacturing by the roll-to-roll method, the above thickness range is preferable.

[Adhesive layer]
The formation of the metal wiring portion 13 on the surface of the reflective layer 18 is preferably performed by a dry laminating method via the adhesive layer 12. When the adhesive layer 12 does not contain a light-reflecting filler or contains a light-reflecting filler, the content thereof is preferably 40% by mass or less. Further, the adhesive layer 12 is preferably a light-transmitting thin film layer that transmits 85% or more of all visible light. As an adhesive for forming such an adhesive layer 12, a known resin-based adhesive can be appropriately used. Among these resin-based adhesives, urethane-based adhesives, polycarbonate-based adhesives, epoxy-based adhesives, and the like can be particularly preferably used.

From the viewpoint of adhesive strength, the adhesive layer 12 preferably does not contain a light-reflecting filler, but may contain a light-reflective filler within the above range. As a result, it is possible to reduce the arrival of light on the resin substrate 11 while maintaining the adhesive strength of the adhesive layer 12 within a required range. As the light-reflecting filler that can be contained in the adhesive layer 12, various white pigments such as titanium oxide similar to those that can be contained in the reflective layer 18 can be used.

[Metal wiring part]
The metal wiring portion 13 is a wiring pattern formed by a conductive base material such as a metal layer. As shown in FIG. 1, the metal wiring portion 13 is formed in a shape so that the light emitting element 2 can be mounted between one portion thereof and another portion formed apart from the one portion. Will be done. In such a light emitting element substrate 1, there is a portion on the surface of the resin substrate 11 where the metal wiring portion 13 is not formed in the region where the light emitting element 2 is expected to be mounted. The horizontal region in which the metal wiring portion 13 does not exist within the region where the light emitting element 2 is expected to be mounted is referred to as the metal wiring portion non-existing region 17 in the light emitting element substrate 1. It is essential for the light emitting element substrate 1 that the reflective layer 18 is formed at least in the region 17 where the metal wiring portion does not exist.

The arrangement of the metal wiring portion 13 is not limited to a specific arrangement or the like as long as the arrangement can mount the light emitting element 2. However, in the light emitting element substrate 1, it is preferable that at least 80% or more, preferably 90%, more preferably 95% or more of one surface of the substrate is covered with the metal wiring portion 13. This can contribute to the improvement of heat dissipation required in the light emitting element substrate 1 in which the metal wiring portion 13 is formed.

The thermal conductivity λ of the metal constituting the metal wiring portion 13 is preferably 200 W / (m · K) or more, and more preferably 300 W / (m · K) or more. The electrical resistivity R of the metal constituting the metal wiring portion 13 ^{is preferably 3.00 × 10-8} Ω · m or less, and more preferably 2.50 × ^10-8 Ω · m or less. Here, for the measurement of the thermal conductivity λ, for example, a thermal conductivity meter QTM-500 manufactured by Kyoto Denshi Kogyo Co., Ltd. can be used, and for the measurement of the electrical resistivity R, for example, a 6517B type electrometer manufactured by Caseley Co., Ltd. can be used. 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. As a result, both heat dissipation and electrical conductivity can be achieved at the same time. More specifically, since the heat dissipation from the light emitting element 2 is stable and the increase in electrical resistance can be prevented, the light emission variation between the light emitting elements is reduced, and stable light emission of the light emitting element becomes possible. Life is also 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 500 Ω / □ or less, more preferably 300 Ω / □ or less, further preferably 100 Ω / □ or less, and particularly preferably 50 Ω / □ or less. The lower limit is about 0.005Ω / □.

Examples of the metal used as the material of the metal wiring portion 13 include metal layers such as aluminum, gold, silver, and copper. The thickness of the metal wiring portion 13 may be appropriately set according to the magnitude of the withstand current required for the light emitting element substrate and the like, and is not particularly limited, but an example thereof is a thickness of 10 μm or more and 50 μm or less. From the viewpoint of improving heat dissipation, the thickness of the metal wiring portion 13 is preferably 10 μm or more. Further, if the thickness of the metal layer does not reach the above lower limit value, the influence of heat shrinkage of the substrate is large, and the warp after the treatment tends to be large during the solder reflow processing. Therefore, from this viewpoint as well, the thickness of the metal wiring portion 13 is 10 μm. The above is preferable. When the same thickness is 50 μm or less, sufficient flexibility can be maintained, and deterioration of handleability due to weight increase can be prevented.

[Solder layer]
In the light emitting element substrate, it is preferable that the metal wiring portion 13 and the light emitting element 2 are joined via the solder layer 14. This soldering can be performed by, for example, a reflow method or a laser method.

[Insulation protective film]
The insulating protective film 15 is not an indispensable constituent requirement in the present invention, but when the insulating protective film is provided, as described above, the metal wiring is made by using a thermosetting ink, a UV curable ink or a coverlay film. It is formed mainly in order to improve the migration resistance of the light emitting element substrate, except for a part that requires electrical bonding between the portion 13 and the surface of the light emitting element substrate.

As the thermosetting ink, known inks can be appropriately and preferably used as long as the thermosetting temperature is about 100 ° C. or lower. 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, a phenol resin, an epoxy acrylate resin, a silicone resin, or the like as a base resin. Can be mentioned. Among these, the 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 from the viewpoint of excellent flexibility.

The thermosetting ink or UV curable ink that forms the insulating protective film 15 may be, for example, a white ink that further contains an inorganic white pigment such as titanium dioxide. By whitening the insulating protective film 15, it is possible to improve the reflectivity and the design.

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

When a coverlay film is used, it can be formed by applying an adhesive to a resin film having high heat resistance such as a polyimide resin and sticking it on the resin substrate 11.

[Surface reflector]
As shown in FIG. 1, the light emitting element substrate 1 may further include a surface reflector 16. The surface reflector 16 mounts the light emitting element 2 on the outermost surface of the light emitting element substrate 1 on the light emitting surface side for the purpose of improving the light emitting ability in the module 10 described in detail below, if necessary. It is laminated except for the part. The material 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. It can be appropriately used according to the required specifications and the like.

[Light emitting element]
The light emitting element 2 is arranged on the light emitting element substrate 1. The light emitting element 2 has a pair of electrodes on one surface, and is electrically connected to the metal wiring portion 13 via the pair of electrodes. The shape, size, and the like of the light emitting element 2 used here are not particularly limited. As the emission color of the light emitting element 2, an arbitrary wavelength can be selected depending on the intended use, 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, it is preferable to use a blue light emitting element having a peak of an emission wavelength of 430 nm or more and 470 nm or less. As the light emitting element 2, a GaN system or an InGaN system can be used. As the InGaN system, In _X Al _Y Ga _1-XY N (0 ≦ X ≦ 1, 0 ≦ Y ≦ 1, X + Y <1) or the like can be used.

[Underfill]
FIG. 4 is a partial cross-sectional view of the module of another embodiment of the present invention. The underfill 21 can also be arranged between the 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 adhesive layer 12. The underfill 21 is preferably a thermosetting resin such as an epoxy resin or a silicone resin. Further, the underfill 21 is preferably made of a material that enhances the bonding strength with the adhesive layer 12, and the underfill 21 and the adhesive layer 12 are preferably made of the same type of material, but may be different materials.

[Sealing member]
It is preferable that a sealing member 19 for sealing the light emitting element 2 is arranged on the resin substrate 11. This is because the light emitting element 2 can be protected from dust and moisture. The sealing member 19 is preferably an epoxy resin, a modified epoxy resin, a silicone resin, or a modified silicone resin.

[Fluorescent material]
The fluorescent substance 20 may be contained in the sealing member 19. The phosphor 20 absorbs light from the light emitting element 2 and emits light having different wavelengths, and emits light such as green, yellow, and red. As the phosphor 20, oxide phosphors such as YAG and silicate, nitride phosphors such as CASN and SCASN, and fluoride phosphors such as KSF can be used.

<Manufacturing method of substrate for light emitting element>
The method for manufacturing the light emitting element substrate 1 is not particularly limited. As appropriate, it can be produced by a conventionally known method for producing an electronic substrate. The light emitting element substrate 1 can be manufactured, for example, by undergoing the etching steps described below. Further, depending on the material resin to be selected, it is preferable that the resin is previously subjected to a heat resistance improving treatment by an annealing treatment.

[Annealing process]
Although not essential in the present invention, conventionally known heat treatment means can be used when performing the annealing treatment. 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, 160 ° C. to 260 ° C., more preferably 180 ° C. to 230 ° C. The annealing treatment time can be exemplified by about 10 seconds to 5 minutes. According to such heat treatment conditions, the heat shrinkage start temperature of PEN, which is generally about 80 ° C., can be improved to about 100 ° C.

[Etching process]
A laminated body used as a material for a light emitting element substrate can be obtained by laminating a metal wiring part 13 of a metal layer used as a material for a metal wiring part on the surface of a resin substrate that has undergone an annealing treatment. Examples of the laminating method include a method of adhering a metal layer to the surface of a resin substrate with an adhesive. From the viewpoint of cost and productivity, the method of adhering the metal layer to the surface of the resin substrate with a urethane-based adhesive is advantageous.

Next, an etching mask patterned in the shape of the metal wiring portion 13 is formed on the surface of the metal layer of the laminated body. The etching mask is provided so that the wiring pattern forming portion of the metal layer, which will be the metal wiring portion 13 in the future, is prevented from being corroded by the etching solution. The method for forming the etching mask is not particularly limited. For example, when a photoresist or a dry film is used, the etching mask may be formed on the surface of the laminated sheet by exposing it to light through the photomask and then developing it. An etching mask may be formed on the surface of the laminated sheet by a printing technique such as an inkjet printer.

Next, the metal layer in the portion not covered by the etching mask is removed by the immersion liquid. As a result, the portion of the metal layer other than the portion that becomes the metal wiring portion 13 is removed.

Finally, an alkaline stripper is used to remove the etching mask. As a result, the etching mask is removed from the surface of the metal wiring portion 13.

[Insulating protective film and surface reflector forming process]
After forming the metal wiring portion, the insulating protective film 15 and the surface reflective material 16 are further laminated as needed. These laminations can be carried out by a known method. Depending on the material used, a printing method such as screen printing or various laminating methods such as a dry lamination method and a thermal lamination method can be used.

<Module>
The module 10 can be obtained by mounting the light emitting element 2 on the above-mentioned light emitting element substrate 1.

A method of manufacturing the module 10 using the light emitting element substrate 1 will be described. The light emitting element 2 can be preferably bonded to the metal wiring portion 13 by soldering. The soldering 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 portion 13 via solder, and then the substrate for the light emitting element is conveyed into the reflow furnace, and hot air at a predetermined temperature is blown to the metal wiring portion 13 in the reflow furnace. This is a method of melting the solder paste and soldering the light emitting element 2 to the metal wiring portion 13. The laser method is a method in which the solder is locally heated by a laser and the light emitting element 2 is soldered to the metal wiring portion 13. The solder material may be Sn-Bi-based, Sn-Cu-based, Sn-Ag-Cu-based or the like, depending on the heat resistance of the resin substrate 11.

When soldering the light emitting element 2 to the metal wiring portion 13, it is preferable to use a method of reflowing the solder by irradiating a laser from the back surface side of the light emitting element substrate 1. This makes it possible to more reliably suppress the ignition of the organic component of the solder due to heating and the resulting damage to the base material.

<Display device>
FIG. 2 is a perspective view schematically showing an outline of the layer structure of the display device 100 using the module 10. The display device 100 displays information (images) such as characters and images on the monitor 3 by driving (light emitting) light emitting elements 2 such as a plurality of LED elements arranged in a matrix at predetermined intervals. The light emitting element 2 is mounted on the metal wiring portion 13 of the light emitting element substrate 1. Further, it is more preferable that the heat radiating structure 4 for more efficiently radiating the heat radiated from the module 10 to the outside is installed on the back surface side of the resin base material. By using the module 10 of the present invention, it is possible to manufacture a large display device having a screen size (diagonal length) of 65 inches or more at a lower cost than before and with improved quality stability.

<Effects of the light emitting element substrate>
A resin substrate made of a resin base material is likely to be deteriorated by light from a light emitting element, particularly blue light having a short wavelength and high energy. On the other hand, the light emitting element substrate 1 has a configuration in which a resin substrate 11, a reflective layer 18 having a high reflectance at a wavelength of 450 nm of 80% or more, and an adhesive layer 12 are laminated in this order. As a result, it has an excellent effect that the blue light from the light emitting element 2 can be effectively shielded while maintaining the adhesive strength of the adhesive layer 12. In addition, the following effects are also achieved.

First, by forming the layer structure on the resin substrate 11 with a two-layer structure of the reflective layer 18 and the adhesive layer 12, reflection occurs not only in the reflective layer 18 but also in the adhesive layer 12 having a predetermined refractive index. , The reflectance can be improved by forming multiple layers. From this point of view, the resin constituting the adhesive layer includes a polycarbonate resin (n = 1.59) and a polycarbonate resin (n = 1.59) as compared with the urethane resin (n = 1.43) from the viewpoint of high refractive index (that is, high reflectance). An epoxy resin (n = 1.55 or more and 1.612 or less) is preferably used, whereby the reflectance can be further improved.

If there is a difference in heat shrinkage between the reflective layer 18 and the adhesive layer 12, the heat generated during solder bonding for mounting the light emitting element 2 (for example, about 150 ° C. when the resin substrate 11 is PET) causes , Wrinkles and the like will occur, so the difference in heat shrinkage (JIS K7133, 150 ° C. x 30 minutes) between the reflective layer 18 and the adhesive layer 12 is preferably 10% or less.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

<Preparation of test sample>
Using each of the following materials, a test sample for confirming the effect of the light emitting device substrate of the present invention was prepared.

[Resin substrate]
The following two types of resin films were prepared as resin substrates for preparing the samples of Examples and Comparative Examples, and were used properly for each sample as shown in Table 1 below.
Resin film A: Polyethylene naphthalate resin film (“QF grade” manufactured by Teijin Limited) 50 μm. This resin film A is a special grade PEN film that has been particularly treated to improve flame retardancy.
Resin film B: Polyethylene naphthalate resin film (“Theonex” manufactured by Teijin Limited) 50 μm. This resin film B is a general-grade PEN film with high transparency that is used for general purposes.

[Reflective layer]
The following three types of coating liquids were prepared as coating liquids for forming the reflective layer, and each of them was used properly for each sample as shown in Table 1 below.
Coating liquid A: A fluororesin having a plurality of crosslinkable substituents (Zeffle: manufactured by Daikin Co., Ltd., product name: GK-570) and an acrylic resin having a plurality of crosslinkable substituents (mass average molecular weight 50,000, Tg 40 ° C.) , Titanium oxide (manufactured by Sakai Chemical Industry Co., Ltd., product name R-5N: average particle size 0.25 μm, alumina treatment) as a light-reflecting filler in a mixed resin with a hydroxyl value of 8.9 mg / g). , 30 parts by mass with respect to 100 parts by mass of the resin, that is, the content of the light-reflecting filler in the cured reflective layer was 23.1% by mass. Moreover, a mixed solution of ethyl acetate: butyl acetate = 1: 1 was used as a solvent. The resin main agent was adjusted at a ratio of fluororesin: acrylic resin = 1: 3. The solid content concentration of the main agent was 43% by mass or more and 45% by mass or less. The mixture was stirred for 60 minutes using a paint shaker. Hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) were adjusted to an NCO / OH ratio of 1.0, and this was used as a curing agent in each coating liquid. These main agent and curing agent were mixed immediately before use (coating) to prepare a coating liquid A. This was applied to each of the above resin films to prepare a cured film, thereby forming a reflective layer for each sample. Regarding the film thickness of the reflective layer for each sample, the coating amount was adjusted so as to have the film thickness as shown in Table 1.
Coating liquid B: Polyphenylsiloxane resin (trade name XE14-C2508: Momentive Performance Materials) and polydimethylsiloxane resin (trade name IVSM4500: Momentive Performance Materials) were used. Anatase-type titanium oxide (trade name A-950: manufactured by Sakai Chemical Industry Co., Ltd.), rutile-type titanium oxide (trade name GTR-100; manufactured by Sakai Chemical Industry Co., Ltd.) and aluminum oxide (trade name AES12: manufactured by Sumitomo Chemical Co., Ltd.) ) Was added in an amount of 200 parts by mass with respect to 100 parts by mass of the resin, that is, the content of the light-reflecting filler in the cured reflective layer was 80.0% by mass, and the coating liquid B and the coating liquid B were added. did. A reflective layer was formed by applying this to each of the above resin films to prepare a cured film. Regarding the film thickness of the reflective layer for each example, the coating amount was adjusted so as to have the film thickness as shown in Table 1.
Coating liquid C: A coating liquid C was prepared using the same material as the coating liquid A. In the coating liquid C, the amount of the above-mentioned titanium oxide added as a white pigment is 7 parts by mass with respect to 100 parts by mass of the resin, that is, the content of the light-reflecting filler in the reflective layer after curing is 6. It was added so as to be 5% by mass, and the other formulations were the same as those of the coating liquid 1.

[Adhesive layer]
For the sample of Example 4, an adhesive layer was further formed on the reflective layer. As the adhesive, a urethane-based adhesive was used and applied so that the thickness of the same layer was 10 μm.

<Reflectance measurement test>
For each Example and Comparative Example, the reflectance of the reflective layer in each wavelength range was measured. However, regarding the reflectance of Example 4, the reflectance of the surface of the laminate including the adhesive layer was measured by irradiating light from above the adhesive layer. Further, for Comparative Example 1, the reflectance of the surface of the resin film itself was measured as a reference value. An ultraviolet-visible spectrophotometer (UV-2550 manufactured by Shimadzu Corporation) was used for the measurement. Table 1 shows the measurement results of the reflectance of each Example and Comparative Example at a wavelength of 450 nm, and FIG. 3 shows the measurement results of Examples 1 and 2 and Comparative Example 1 in the wavelength range of 375 nm to 500 nm.

<Light resistance test>
As a light resistance test for a blue light emitting element, a blue laser (Nichia) was used as a light resistance test for Examples 1 to 3 and Comparative Example 2 from the reflective layer, Example 4 from the adhesive layer, and Comparative Example 1 from the resin film. A laser diode manufactured by Nichia Corporation, wavelength 450 nm, output 0.5 W) was irradiated, and the time for which a hole was formed in the film was measured. The test results are shown in Table 1 below.

From Table 1, it was confirmed that the resin substrate on which the reflective layer having a reflectance of 90% or more at a wavelength of 450 nm was formed had a sufficiently long time required for drilling. Further, from the comparison of the results of Examples 1 and 3 and 4, the result of the reflectance of the reflective layer itself and the effect of preventing perforation is different depending on the type of resin substrate on which the light reflectance of the surface is presumed to be different. It can be seen that there is virtually no fluctuation. Further, the influence of the presence or absence of the adhesive layer on the above effect is almost the same as the above. In addition to this, by taking into account the results of Comparative Example 2, the substrate for a light emitting element of the present invention on which a reflective layer having a reflectance of 80% or more at a wavelength of 450 nm is arranged has light resistance to light from the light emitting element. It can be seen that it is a substrate for a light emitting element having.

1 Substrate for light emitting element 2 Light emitting element 3 Monitor 4 Heat dissipation structure 11 Resin substrate 12 Adhesive layer 13 Metal wiring part 14 Solder layer 15 Insulating protective film 16 Surface reflective material 17 Metal wiring part non-existent area 18 Reflective layer 19 Sealing member 20 Phosphor 21 Underfill 10 Module 100 Display

Claims (8)

It has a flexible resin substrate and a metal wiring portion formed on at least one surface side of the resin substrate via an adhesive layer.
A reflective layer is arranged between the resin substrate and the adhesive layer.
The reflective layer contains a thermosetting resin and a light-reflecting filler, and the content of the light-reflecting filler is 10% by mass or more and 85% by mass or less at a wavelength of 450 nm. The reflectance is 80% or more,
The metal wiring portion covers a range of 80% or more of one surface of the resin substrate.
The adhesive layer does not contain a light-reflecting filler, or the content of the light-reflective filler is 40% by mass or less, and is between the metal wiring portions on the surface of the resin substrate. It also exists in the area where the metal wiring part does not exist, which is a separated part.
Substrate for light emitting element. The substrate for a light emitting element according to claim 1, wherein the thickness of the reflective layer is 5 μm or more and 250 μm or less. The substrate for a light emitting element according to claim 1 or 2, wherein the difference in heat shrinkage (JIS K7133, 150 ° C. × 30 minutes) between the reflective layer and the adhesive layer is 10% or less. A module in which a light emitting element is mounted on the light emitting element substrate according to any one of claims 1 to 3.
The light emitting element substrate is provided with a region in which the metal wiring portion does not exist between one portion of the metal wiring portion and another portion formed apart from the one portion.
A module in which the light emitting element straddles a region in which the metal wiring portion does not exist and is mounted on one portion of the metal wiring portion and the other portion. The module according to claim 4, wherein the light emitting element is a blue light emitting element. The module according to claim 4 or 5, wherein the peak of the emission wavelength of the light emitting element is 430 nm or more and 470 nm or less. The module according to any one of claims 4 to 6, wherein an underfill is arranged between the adhesive layer and the light emitting element. A sealing member for sealing the light emitting element is arranged on the resin substrate.
The module according to any one of claims 4 to 7, wherein the sealing member comprises one or more materials selected from an epoxy resin, a modified epoxy resin, a silicone resin, and a modified silicone.

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