JP2009229507A - Sealing film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a durable sealing film of stable quality, enhancing easily a light taking-out efficiency at low cost. <P>SOLUTION: This sealing film comprises an optical film the glass transition temperature of which is 60°C or more, and an adhesive film the glass transition temperature of which is 130°C or less, and the refractive index of which is 1.42 or more, and is a transparent film, wherein (1) a refractive index distribution having unevenness with 0.1 μm or more of average groove depth or a refractive index change with 0.2 or more of refractive index difference exists on a face of the optical film in an opposite side of the adhesive film, or (2) refractive index distribution structure having a refractive index change with 0.015 or more of refractive index difference exists in an inside of the optical film, or (3) unevenness with 0.1 μm or more of average groove depth exists on an interface between the optical film and the adhesive film. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a transparent sealing film for improving the light extraction efficiency of a light-emitting element or controlling an emission angle.

  In recent years, research on applying light-emitting elements instead of fluorescent lamps and incandescent lamps such as white LEDs, organic ELs, and inorganic ELs to lighting has become active. Many of these light-emitting elements have a high refractive index, and light is reflected from the surface of the element, resulting in a problem of low luminous efficiency. Therefore, various attempts have been made to provide an antireflection structure on the surface in order to increase the luminous efficiency (see, for example, Patent Documents 1 to 4).

  However, these methods are methods for directly processing hard sapphire and semiconductor elements, and costly. In order to perform reflection prevention at low cost, application of the resin structure to reflection prevention can be considered. When resin is used for antireflection, two interfaces of resin and air and resin and light emitting surface are generated, and antireflection is performed for each.

Of these, many studies have been made on the antireflection of the interface between the resin and air (see, for example, Patent Documents 5 to 14).
Further, as a method for producing the antireflection structure on the resin surface, for example, a method of producing irregularities on the resin surface using a stamper when the adhesive is thermally cured and sealed is disclosed. (For example, refer to Patent Document 15).

As a means for preventing reflection at the interface between the resin and the light emitting surface, there is a method using a sealing film having a high refractive index.
However, it is difficult to make a general transparent resin have a high refractive index. One solution is to mix high refractive index ultrafine particles into the resin. (For example, refer to Patent Documents 16 to 19).
Patent Document 20 also proposes a method of providing a diffraction grating at the interface between the resin and the light emitting surface, and discloses a method of producing a diffraction grating by photolithography.

The sealing film used here requires not only adhesiveness but also high heat resistance and high transparency (see, for example, Patent Documents 21 and 22).
On the other hand, the uniformity of light extraction efficiency is important for general illumination. Since the film thickness of the soap bubbles is not uniform, a rainbow is generated. Similarly, the variation in the film thickness at the time of sealing leads to the variation in the brightness of the illumination and the quality of the hue.

JP 2003-86835 A JP 2006-49855 A JP 2006-286710 A JP 2006-294907 A JP 2004-311153 A JP 2004-335183 A, JP 2005-190931 A,

JP 2004-296429 A JP 2005-317228 A JP 2005-317254 A JP 2005-322489 A JP 2005-322490 A JP 2005-327522 A JP 2005-327535 A

JP 2005-294733 A JP 2006-140362 A JP 2004-238441 A JP 2004-139777 A JP 2005-301769 A JP 2006-156400 A JP 2004-266134 A JP 2006-316264 A

From the above points, the reflection on the surface of organic and inorganic high-refractive-index light-emitting elements is suppressed, it has adhesive properties so that it can be easily sealed, and it has heat resistance, high transmittance, and the surface of a sealing film. Therefore, it is desired to increase the light extraction efficiency by using a sealing film with less reflection.
An object of the present invention is to provide a sealing film having a stable quality and durability that can easily increase the light extraction efficiency at low cost.

  The inventor has made a method for producing an adhesive film having a high refractive index, a method for selecting an optical film having a refractive index distribution structure that increases the light extraction efficiency having a lower refractive index than that of the adhesive film, and a seal comprising the adhesive film and the optical film. The present inventors have completed the present invention by finding a film thickness and uneven shape design and manufacturing method for a stop film, and a sealing method for a light emitting element.

  The first essential point of the present invention is to reduce the reflectance of the surface of the sealing film and improve the light extraction efficiency by simply attaching the film to the concave-convex integrated sealing film. Compared with the method of producing irregularities at the time of sealing or after sealing, since the irregularities of the sealing film can be produced by roll transfer, the productivity can be significantly increased. Further, since the film thickness on the light emitting surface can be made constant, the light extraction efficiency is stabilized.

Furthermore, since it can seal in a lump, a process can be reduced. In general, the sealing film is sealed by heating, but in order to prevent deformation of the unevenness, the heat resistance of the optical film having unevenness is increased, and preferably a non-thermoplastic resin is used, and the light extraction efficiency is improved by sealing. It is necessary to select a material that does not decrease.
In addition, the warp was suppressed by reducing the difference in linear expansion coefficient between the optical film and the adhesive film. Thereby, wrinkles and peeling at the time of sealing can be suppressed.

  The second essential point of the present invention is that the film thickness can be made more constant by putting fine particles having a uniform particle diameter in the adhesive film. By thermocompression bonding or the like, fine particles as spacers are sandwiched between the light emitting surface and the optical film, and the film thickness can be defined by the particle size.

Moreover, by adjusting the refractive index difference between the refractive index of the particles and the light emitting surface, the reflectance at the interface between the light emitting element and the sealing film can be reduced, and the light extraction efficiency can be increased. Compared with the case where the diffraction grating is provided on the upper surface of the light emitting element by photolithography, the efficiency can be easily increased.
In order to achieve the above object, the present invention relates to the following matters.

  (1) It consists of an optical film and an adhesive film, the glass transition temperature of the optical film is 60 ° C or higher, the glass transition temperature of the adhesive film is 130 ° C or lower, and the refractive index of the adhesive film is 1.42 or higher, (1) The surface of the optical film opposite to the adhesive film has a refractive index distribution with unevenness with an average groove depth of 0.1 μm or more or a refractive index change with a refractive index difference of 0.2 or more, or (2) optical film There is a refractive index distribution structure having a refractive index change with a refractive index difference of 0.015 or more inside, or (3) a transparent seal having irregularities with an average groove depth of 0.1 μm or more at the interface between the optical film and the adhesive film the film.

  (2) The adhesive film includes an adhesive film B having a film thickness of 0.1 μm or more and 14 μm or less and a refractive index of 1.6 or more and an adhesive film A adjacent to the adhesive film B. The sealing film according to (1), wherein the difference in refractive index is 0.1 or more, and the film thickness of the adhesive film is 100 μm or more.

  (3) The adhesive film has a film thickness of 0.1 μm or more and 14 μm or less, a refractive index of 1.6 or more, a film thickness of a substrate portion of the optical film of 10 μm or less, and a refractive index of 1.6 or less. The sealing film as described in (1) or (2) above.

  (4) The adhesive film includes an adhesive film A and an adhesive film B adjacent to the adhesive film A, the adhesive film B includes a total of 10% or more of amide, imide resin, or silicone resin, and an average particle size of 10 μm or less. The inorganic filler is contained at 1% or more, the adhesive film A contains no amide or imide resin or contains 10% or less, and contains 20% or more of an epoxy resin. Sealing film.

  (5) The adhesive film includes an adhesive film A and an adhesive film B adjacent to the adhesive film A, and the adhesive films A and B have (a) an epoxy resin and (b) a weight average molecular weight including a functional group of 100,000. The adhesive composition comprising the above-described high molecular weight component and (c) an imidazole compound, the adhesive composition being compatible with the high molecular weight component before curing of the epoxy resin, After curing, the above-mentioned high molecular weight component is phase-separated to form a sea-island structure, and the average width of the sea and islands in the center of the adhesive film A when viewed in a cross section perpendicular to the film is 0.3 μm or less, Sealing film in any one of said (1)-(4) containing the adhesive film whose average of the width | variety of the sea and island of adhesive film B center part is each 0.3 micrometer or more.

  (6) The adhesive film includes an adhesive film A and an adhesive film B adjacent to the adhesive film A, and the adhesive film A has a weight average molecular weight including a crosslinkable functional group of 100,000 or more and a glass transition temperature Tg of −50. It contains 100 parts by weight of a resin containing 15 to 40% of a high molecular weight component of -50 ° C. and 60 to 85% of a thermosetting component mainly composed of an epoxy resin, and 20 to 200 parts by weight of an inorganic filler. Is a sealing film in any one of said (1)-(5) whose refractive index is 0.1 or more higher than adhesive film A.

(7) The sealing film according to any one of (1) to (6), wherein a difference in linear expansion coefficient between the optical film and the adhesive film in contact with the optical film is 0.5 × 10 ⁻⁴ or less.
(8) The sealing film according to any one of (1) to (7), wherein the optical film is made of a thermosetting resin.
(9) The sealing film according to any one of (1) to (8), wherein the optical film or the adhesive film contains a phosphorescent or fluorescent material.

  (10) The particles contained in the adhesive film have an average particle size in the range of 0.04 to 0.6 times the film thickness of the adhesive film, and the average particle size is 0.4 μm or more and 100 μm or less. And the sealing film in any one of said (1)-(9) in which the average particle diameter of the particle | grains which enter 10% by volume from a particle | grain with a large particle diameter is smaller than 1.5 times the whole particle | grains.

(11) The absolute value of the difference between the refractive index of the particle surface and the refractive index of the adherend surface contained in the adhesive film is 0.5 or less, and the Mohs hardness of the particles is 5 or less. (10) The sealing film according to any one of the above.
(12) The above-mentioned (1), wherein the particles contained in the adhesive film have a higher refractive index on the particle surface than on the particle surface, and the storage elastic modulus of the material inside the particle is 1 to 3000 MPa. )-(11) The sealing film in any one.

(13) The adhesive film includes particles having an absolute value of a difference from the refractive index of the light emitting surface of 0.5 or less, the adhesive surface of the adhesive film is polished, and the cross section of the particles is exposed on the surface ( The sealing film according to any one of 1) to (12).
(14) The above adhesive film (1) to (13), wherein the adhesive film contains particles having an absolute value of a difference from the refractive index of the light emitting surface of 0.5 or less, and the major axis of the particles is 1.5 times longer than the minor axis. ).

  (15) An optical film comprising an optical film and an adhesive film, wherein the glass transition temperature of the sealed optical film is 60 ° C. or higher, the glass transition temperature of the adhesive film is 60 ° C. or higher, and the surface of the optical film opposite to the adhesive film Refractive index having an average groove depth of 0.1 μm or more or a refractive index distribution having a refractive index change of 0.2 or more or a refractive index change of 0.015 or more in the optical film. A transparent sealing film having a refractive index distribution structure or having irregularities with an average groove depth of 0.1 μm or more at the interface between the optical film and the adhesive film, and the refractive index of the adhesive film being 1.42 or more.

  (16) The absolute value of the difference between the refractive index of the light emitting surface and the adhesive film particles after sealing is 0.5 or less, and the average is in the range of 0.04 to 0.6 times the film thickness of the adhesive film. The average particle size of particles having a particle size of 0.4 μm or more and 100 μm or less and entering 10% by volume from a particle having a large particle size is 1. The sealing film according to (15), wherein the contact area of the adhesive film after sealing is smaller than 5 times and the contact area with the light emitting surface is 1.5 times or more larger than the contact area of the particles with the optical film.

According to the present invention, a sealing film having an antireflection function can be sealed in a large number of light emitting elements at a time.
Moreover, since mass production by roll transfer is possible, it can be manufactured at low cost.
Further, since variations in film thickness can be suppressed, a device with stable light extraction efficiency can be manufactured. As a result, the light extraction efficiency can be easily increased at low cost, and a durable sealing film with stable quality can be provided.

[First Embodiment]
The sealing film of the present invention according to item (1) comprises an optical film and an adhesive film, the glass transition temperature of the optical film is 60 ° C. or higher, the glass transition temperature of the adhesive film is 130 ° C. or lower, and the adhesive film The refractive index of the film is 1.42 or more, and (a) the surface of the optical film opposite to the adhesive film has irregularities with an average groove depth of 0.1 μm or more or a refractive index change with a refractive index difference of 0.2 or more. There is a refractive index distribution, or (b) there is a refractive index distribution structure having a refractive index difference of 0.015 or more within the optical film, or (c) an average groove depth at the interface between the optical film and the adhesive film. It is a transparent sealing film characterized by having irregularities of 0.1 μm or more.

The refractive index distribution means that light media having different refractive indexes are alternately arranged. If the light medium happens to be air, it will be uneven.
Moreover, an optical film is a transparent film which does not have adhesiveness or adhesiveness and has a refractive index distribution on the surface or inside. An adhesive film is a film having adhesiveness or tackiness. In the following, a case where the refractive index change is caused by unevenness will be described, but the same applies to a broader refractive index distribution.

  In FIG. 1, the average groove depth is an average value of the groove depths of the convex portions in a certain cross section. Cut the cross section to include the deepest groove. The unevenness of the surface is the direction in which the product of the number of grooves per unit length and the average groove depth is the maximum when the average of the depth of the unevenness when the cross section is cut is calculated for the cross section cuts in different directions. It is uneven.

  The sealing film can be attached to a light emitting element as shown in FIG. In the case of a white LED, the pasting surface is on a layer containing a phosphor that converts light into white or on a blue light emitting surface. In the case of organic EL, for example, it is on sealing glass.

  Unless the optical film has a glass transition temperature higher than the heat curing temperature required for sealing the sealing film, the optical film is deformed when the adhesive film is thermally cured, and the light extraction efficiency decreases or the light extraction efficiency varies. Since the thermosetting temperature is 60 ° C. or higher, the glass transition temperature is 60 ° C. or higher, preferably 100 ° C. or higher, more preferably 150 ° C. or higher, and most preferably 200 ° C. or higher.

  On the other hand, if the glass transition temperature of the adhesive film is not 130 ° C. or lower, the flexibility of the film may be low, and wrinkles are likely to occur because there is no step following ability to the light emitting element surface during thermosetting. The glass transition temperature is more preferably 100 ° C. or lower. The glass transition temperature is more preferably 50 ° C. or lower. The lower one can be cured at a lower temperature, and the damage to the light emitting element due to heat can be reduced.

  The surface of the optical film opposite to the adhesive film has irregularities with an average groove depth of 0.1 μm or more, or has a structure having a refractive index change with a refractive index difference of 0.015 or more, so that the exit surface The scattering of obliquely incident light with respect to the light can be helped, and the light extraction efficiency can be increased. This effect is a diffractive effect or a physico-optical effect due to a change in the incident angle with respect to the surface. The average groove depth of the unevenness is more preferably 0.8 μm or more. The depth at which the diffraction effect is sufficiently exhibited is determined by m · wavelength / (n−1), where m is a natural number and n is the refractive index of the optical film.

  [(Reference 1), Victor Soifer, Victor Kotlyar and Leonid Doscolovich: “Iterative Method for Deflective Optical Element Computation” Computation "" (USA), Taylor & Francis, 1997, p. 1-10, reference] When m is 1, wavelength is 400 nm, and refractive index is 1.5, the depth is 0.8 μm.

  The average groove width of the unevenness on the surface is preferably 1 μm or more, more preferably 10 μm or more, and further preferably 50 μm or more in order to increase heat resistance. In general, the glass transition temperature in the vicinity of the surface is lower than the bulk glass transition temperature.

  An AFM (Atomic Force Microscope) and SEM (Scanning Electron Microscope) are used to measure the unevenness. When the depth of the unevenness is 3 μm or more, or when the uneven slope is a steep slope of 45 degrees or more, the result of SEM is used. SEM cuts and observes the cross section of a film perpendicularly. Nanopics made by Seiko Instruments can be used as the AFM, and XL30 made by Philips can be used as the SEM.

For the measurement of the refractive index, a prism coupler can be used for the sealing film before curing. For example, a Metricon Model 2010 prism coupler can be used.
An interference microscope can be used for the cured sealing film. For example, a transmission type two-beam interference microscope manufactured by Mizojiri Optical Co., Ltd. can be used. A sample for measurement is cut out with a microtome or the like as necessary.

  In the first and second embodiments, the glass transition temperature of the optical and adhesive film is the glass transition temperature according to the average thickness of the layer for the optical film and the adhesive film for the optical film when the distribution is multilayered or inclined. Use the glass transition temperature of the lowest layer. On the other hand, when the phases are separated in the layer, the average glass transition temperature depending on the area in the layer is used.

  An example of a film having a refractive index difference of 0.015 or more inside the film is a volume phase hologram disclosed in JP-A-4-299303. The larger the refractive index difference, the higher the scattering efficiency. As a result, light obliquely incident on the optical film can be bent in the vertical direction to increase the light extraction efficiency.

  In the first and second embodiments, the refractive index of the optical and adhesive film is such that the refractive index of the highest layer is distributed when the distribution is multilayered or inclined, and the refractive index of the optical and adhesive film is within the layer when the layers are phase-separated. Use the average refractive index of.

  By being transparent, light extraction efficiency can be increased. The total light transmittance can be used as an index of transparency. The total light transmittance is calculated by a numerical value including Fresnel loss. When the surface is smooth and the film itself does not absorb, if the refractive index of the film is 1.5, the total light transmittance is 92%.

  As for the transparency of the optical film, the thickness is 10 μm, the total light transmittance is preferably 50% or more, and more preferably 80% or more. The higher the transmittance, the higher the luminance when sealed. The total light transmittance of the sealing film is preferably 50% or more, more preferably 70% or more, and further preferably 80% or more.

  A laser is used as a method for measuring the total light transmittance of the film. Using a He-Ne laser 632.8 nm light, measurement is performed with a power meter. In order to cancel the polarization dependence, measurement is performed under two conditions where the polarization of incident light is different by 90 °, and the average is used as a measurement value.

  Further, if necessary, the measurement is similarly performed with 442 nm light from a He—Cd laser or 514.5 nm light from an Ar laser. In the measurement of the sealing film, light is incident perpendicularly to the surface from the surface of the adhesive film opposite to the optical film. When the emitted light is diffused light without a clear diffraction pattern, an integrating sphere may be used for measuring the light amount.

  By setting the refractive index of the adhesive film to 1.42 or more, the refractive index difference between the light-emitting element having a high refractive index and the adhesive film can be reduced, and reflection can be suppressed. Moreover, by making it transparent, light absorption can be suppressed and light extraction efficiency can be increased. The refractive index of the adhesive film is preferably 1.6 or more, and more preferably 1.7 or more.

  There may be irregularities with an average groove depth of 0.1 μm or more at the interface between the optical film and the adhesive film. Thereby, reflection at the interface between the optical film and the adhesive film can be suppressed or the emission angle can be controlled. The average groove depth of the unevenness at the interface is more preferably 2 μm or more. The depth at which the diffraction effect is sufficiently exerted is determined by m · wavelength / | n1-n2 |, where m is a natural number, n1 is the refractive index of the optical film, and n2 is the refractive index of the adhesive film.

  When m is 1, wavelength 400 nm, n1 is 1.65, and n2 refractive index is 1.45, this depth is 2 μm. The average groove width of the unevenness at the interface is preferably 1 μm or more, more preferably 3 μm or more and 10 μm or less, and further preferably 5 μm or more and 7 μm or less in order to improve heat resistance.

  In display applications, if the period is too large, moire tends to occur due to interference with pixels. When the unevenness is periodic and the average groove width is 5 μm or less, it is preferable that the unevenness of the optical film surface on the side opposite to the adhesive film is not periodic. This is because the generation of rainbows due to spectroscopy can be suppressed.

  In addition, as described in JP-A-2005-316178, when the emission angle is controlled, the optical film preferably has a refractive index higher by 0.1 or more than the adhesive film, and is 0.2 or more. Higher is more preferable. By controlling the emission angle, for example, a car light can be illuminated only in a necessary range. Thereby, the vehicle of an oncoming lane can be made not dazzled.

  The storage elastic modulus and tan δ of the adhesive film and the optical film were measured under the following conditions using a dynamic viscoelasticity measuring device (RVELOGY, DVE-V4, automatic static load). The sample size was 20 mm in length, 4 mm in width, and 80 μm in film thickness, the heating rate was 5 ° C./min, the measurement mode was the tension mode, and the frequency was 10 Hz. The glass transition temperature was calculated using the peak temperature of tan δ. For those whose glass transition temperature is not clear, a temperature at which the storage elastic modulus by dynamic viscoelasticity measurement is 100 MPa or less is substituted.

  Adhesive film adherends include optical film acrylic, lead frame copper, transparent electrode ITO, near ultraviolet white light conversion element SiC, GaN sapphire, organic EL sealing glass silica, etc. , Think variously.

  In any case, the strength is preferably 1 N / chip or more and more preferably 2 N / chip or more in the peel test after curing at 100 ° C. for 1 hour with respect to the adhesion target. However, the tip is 5 mm square. The adhesive film preferably has a solder heat resistance of 265 ° C.

In order to increase the adhesion between the optical film and the adhesive film and reduce warpage, the difference in linear expansion coefficient between the materials of the two films is preferably 0.5 × 10 ⁻⁴ / ° C. More preferably, it is 1 × 10 ⁻⁴ / ° C. or less. If there is a warp, it will be easy to wrinkle after heat-bonding, and the adhesive strength will decrease.

The adhesive properties, linear expansion coefficient and solder heat resistance of this sealing film were evaluated as follows.
(I) Peel strength against adherend: (Adhesive properties) On a hot plate at 100 ° C., a sealing film was laminated on the chip (5 mm square) of the adherend and cured at 100 ° C. for 1 hour. The peel strength of this sample was measured at 100 ° C.

  (II) Linear expansion coefficient: About each film of the sealing film heat-cured at 100 ° C. for 1 hour, the elongation of the sample was measured at a rate of temperature increase of 5 ° C. per minute using a thermomechanical analyzer. The average linear expansion coefficient was determined from the elongation at ° C.

  (III) Solder heat resistance: The light-emitting element sealed with the prepared sealing film was treated at 85 ° C. and 85% humidity for 48 hours, and then floated on a soldering iron at 265 ° C. for 1 minute to check for blistering and peeling. It was.

  The adhesive film of the present invention has a weight average molecular weight containing a crosslinkable functional group of 100,000 or more and a Tg of −50 to 50 ° C., a high molecular weight component of 15 to 40%, and a thermosetting component 60 mainly composed of an epoxy resin. It is preferably an adhesive film containing 100 parts by weight of resin containing ˜85% and 20 to 200 parts by weight of filler, and its constituent components are not particularly limited, but it has an appropriate tack strength and is handled as a film. Because of its good properties, it may contain a curing accelerator, a catalyst, an additive, a coupling agent and the like in addition to the high molecular weight component, the thermosetting component, and the filler.

  As the high molecular weight component, polyimide resin having a crosslinkable functional group such as epoxy group, alcoholic or phenolic hydroxyl group, carboxyl group, (meth) acrylic resin, silicone resin, urethane resin, polyphenylene ether resin, polyetherimide resin, Examples thereof include, but are not limited to, phenoxy resins and modified polyphenylene ether resins.

  When the high molecular weight component is contained in an amount of 15 to 40% of the resin, the adhesive film has good filling step of the light emitting element surface step, and the content of the high molecular weight component is preferably 20 to 37%, preferably 25 to 35. % Is more preferable.

  The high molecular weight component is preferably a high molecular weight component having a Tg (glass transition temperature) of −50 ° C. to 50 ° C. and a weight average molecular weight having a crosslinkable functional group of 100,000 or more.

  As the high molecular weight component, for example, an epoxy group-containing (meth) acrylic copolymer having a weight average molecular weight of 100,000 or more obtained by polymerizing a monomer containing a functional monomer such as glycidyl acrylate or glycidyl methacrylate is preferable. . As the epoxy group-containing (meth) acrylic copolymer, for example, (meth) acrylic acid ester copolymer, acrylic rubber and the like can be used, and acrylic rubber is more preferable.

  Acrylic rubber is a rubber mainly composed of an acrylate ester and mainly composed of a copolymer such as butyl acrylate and acrylonitrile, a copolymer such as ethyl acrylate and acrylonitrile, or the like. Further, the acrylate may contain sulfur in order to obtain a high refractive index.

  For example, 4,4′-bis (β-methacryloyloxyethylthio) diphenylsulfone, 4,4′-bis (β-hydroxyethylthio) diphenylsulfone = monoacrylate, sulfur cyclic structure, cyclic thiocarbonate structure, cyclic dithio Carbonate structure and cyclic trithiocarbonate structure. As an example thereof, a method for producing an acrylic adhesive containing sulfur as described in JP-A No. 2004-115713 is described.

  When the Tg of the high molecular weight component exceeds 50 ° C., the flexibility of the film may be lowered. When the Tg is less than −50 ° C., the flexibility of the film is too high, so that the film is difficult to cut during wafer dicing. In some cases, burrs are likely to occur.

  Further, the weight average molecular weight of the high molecular weight component is preferably 100,000 or more and 1,000,000 or less, and if the molecular weight is less than 100,000, the heat resistance of the film may be reduced. If the molecular weight exceeds 1,000,000, the film flow may be reduced. May decrease. In addition, a weight average molecular weight is a polystyrene conversion value using the calibration curve by a standard polystyrene by the gel permeation chromatography method (GPC).

  The measuring method of the weight average molecular weight by normal temperature GPC in the present invention is as follows. Measuring instrument: LC-6C manufactured by Shimadzu Corporation Column: shodex KF-802.5 + KF-804 + KF-806 Solvent: THF (tetrahydrofuran) Temperature: Room temperature (25 ° C.) Standard material: Polystyrene flow rate: 1.0 ml / min (sample concentration about 0) .2%) Injection volume: 200 μl.

  A high molecular weight component having a Tg of −20 ° C. to 40 ° C. and a weight average molecular weight of 100,000 to 900,000 is preferable in that the adhesive film is easily cut during wafer dicing, and resin waste is not easily generated. High molecular weight components having a Tg of −10 ° C. to 40 ° C. and a weight average molecular weight of 200,000 to 850,000 are more preferred.

  The thermosetting component used in the present invention is preferably an epoxy resin having heat resistance and moisture resistance required for sealing a semiconductor light emitting device. In the present invention, the “thermosetting component mainly composed of epoxy resin” includes an epoxy resin curing agent. The epoxy resin is not particularly limited as long as it is cured and has an adhesive action.

  As the epoxy resin, a bifunctional epoxy resin such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, novolac type epoxy resin such as phenol novolac type epoxy resin, cresol novolac type epoxy resin, etc. should be used. Can do. Moreover, what is generally known, such as a polyfunctional epoxy resin, a glycidylamine type epoxy resin, a heterocyclic ring-containing epoxy resin, or an alicyclic epoxy resin, can be applied.

In particular, the molecular weight of the epoxy resin is preferably 1000 or less, and more preferably 500 or less, in view of the high flexibility of the film in the cured B-stage state.
Further, 50 to 90 parts by weight of a bisphenol A type or bisphenol F type epoxy resin having a molecular weight of 500 or less excellent in flexibility and 10 to 50% of a polyfunctional epoxy resin having a molecular weight of 800 to 3000 excellent in heat resistance of the cured product. It is preferable to use together.

  As the epoxy resin curing agent, known curing agents that are usually used can be used. For example, amines, polyamides, acid anhydrides, polysulfides, boron trifluoride, bisphenol A, bisphenol F, and bisphenol S can be used. Examples thereof include bisphenols having two or more such phenolic hydroxyl groups in one molecule, phenol resins such as phenol novolac resins, bisphenol A novolac resins, and cresol novolac resins.

The adhesive film is preferably colorless and transparent after curing in order to eliminate coloring. CIE1976L ^* u ^* v ^{* In} the u'v 'chromaticity diagram of uniform color space, when using a white halogen lamp with chromaticity (u0', v0 '), the chromaticity of the transmitted light of the adhesive film and the halogen lamp The distance from the chromaticity is preferably 0.1 or less, more preferably 0.05 or less. Further, in order to prevent wrinkling when attached to the light emitting element, the elastic modulus should be low to some extent, and the storage elastic modulus at 100 ° C. is preferably 200 to 3000 MPa.

On the other hand, if the elastic modulus is too low, handling becomes difficult. The advantage due to the low elastic modulus is the step following ability when the adhesive film is pressed against the light emitting element. When the light emitting element is convex on the mounting substrate surface, it can be embedded.
Furthermore, the improvement of the total light transmittance can be expected by reducing the film thickness only on the light emitting element surface. At this time, the film thickness on the light emitting surface is preferably less than or equal to half the film thickness of the adhesive film before bonding.

  The material of the optical film can be a resin such as polycarbonate, acrylic, or silicone, but it is preferable to use an optical film characterized by containing a urethane acrylate resin. Urethane acrylate is a UV curable resin, has high total light transmittance and good curing characteristics. This resin may contain other copolymers.

  For example, acrylic copolymers include copolymers of acrylic esters such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methoxybutyl acrylate, ethoxyethyl acrylate, and methyl mercaptan, ethyl mercaptan. , Copolymers of (meth) acrylates such as thiophenol, and one or more of these acrylates, and (i) a carboxyl group as a functional group, which can be copolymerized therewith, acrylic acid, maleic acid , Methacrylic acid, (ii) vinyl glycidyl ether, allyl glycidyl ether, methacryl glycidyl ether, glycidyl acrylate, and (iii) hydroxymethyl acrylate, hydroxyethyl acrylate having a glycidyl group Monomers selected from the relations - and a copolymer of one or more.

  The material of the optical film is preferably a thermosetting acrylic resin. A polyisocyanate can be used as a curing agent in combination with a melamine resin, a urethane resin, or the like. Polyisocyanates include naphthalene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, etc. Polyisocyanate can be used.

  The optical film or adhesive film may contain a phosphorescent or fluorescent material. When the light emission source 26 emits blue light in FIG. 2, a wavelength conversion material for making white may be added. By including a wavelength conversion material in the optical film 22 and integrating it with the adhesive film, the thickness of the adhesive layer and the optical film layer can be made constant, so that a sealing material containing a phosphorescent or fluorescent material can be directly applied. The brightness is stable compared to the case of sealing. Or the frequency | count of sealing can be reduced to once by making the adhesive film 24 contain a wavelength conversion material. As a result, it is possible to suppress variations in luminance among lots.

Further, as shown in FIG. 3, an optical film and an adhesive film may be sandwiched between a cover film and a base film. The cover film and the base film preferably have a glass transition temperature of 100 ° C. or higher, and more preferably 150 ° C. or higher.
There is no restriction | limiting in particular as a material of the said cover film or a base film, For example, there exist a polyester film, a polypropylene film, a polyethylene terephthalate film, a polyimide film, a polyetherimide film, a polyether naphthalate film, a methylpentene film etc.

  Further, as described in item (2), the sealing film of the present invention is adjacent to the adhesive film B and the adhesive film B having a film thickness of 0.1 μm to 14 μm and a refractive index of 1.6 or more. The adhesive film A to be included has a refractive index difference of 0.1 or more between the adhesive films A and B, and the film thickness of the entire adhesive film is 100 μm or more.

  By separating the adhesive films A and B as shown in Fig. 4, the B layer can have a high refractive index, and the A layer can have other properties necessary for other sealing films. The overall characteristics of the film can be improved. When the adhesive film B has a film thickness of 0.1 μm or more and 14 μm or less and a refractive index of 1.6 or more, the light extraction efficiency can be increased when the adhesive film B is adhered to the light emitting surface of the light emitting element. In general, the B layer having a high refractive index of the resin has a low transmittance, and if the film thickness is too large, the transmittance is lowered. Therefore, it is out of the design of the optimum light extraction efficiency. On the other hand, even if the thickness of the B layer is too thin, the difference in refractive index between the A layer and the light emitting surface cannot be relaxed, so that the design is not optimal for the light extraction efficiency.

  By increasing the refractive index of the adhesive film A by 0.1 or more than that of the adhesive film B, the magnitude relationship of the refractive index can be set to light emitting element> adhesive film B> adhesive film A, and the refractive index at each interface Since the change is relaxed, the reflectance can be reduced. When the film thickness of the adhesive film is 100 μm or more, the unevenness on the surface of the light emitting element can be embedded as shown in FIG.

  The A layer can be formed by spin coating or roll coating. Formation of the B layer can be performed by roll-coating the previously prepared A layer or by batch multi-layer lamination of the A layer and B layer by a roll. Conversely, the B layer may be coated first, and the A layer may be formed thereon.

  Further, as described in item (3), the sealing film of the present invention has an adhesive film with a film thickness of 0.1 μm to 14 μm and a refractive index of 1.6 or more. The thickness may be 10 μm or less and the refractive index may be 1.6 or less.

  In the design for taking out light from the opposite side of the electrode as disclosed in JP-A-2005-354020, sealing is performed from the back side of the electrode as shown in FIG. In the sealing film for such use, the light extraction ability is more important than the embedding property. At this time, the light extraction efficiency increases when the sealing film is thinner and the adhesive film has a higher refractive index.

  The film thickness of the adhesive film is preferably 14 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less. When the film thickness of the substrate portion of the optical film is a value obtained by subtracting the value of the average groove depth of the unevenness from the film thickness of the optical film, this film thickness is preferably 10 μm or less, and is 5 μm or less. Is more preferable, and it is further more preferable that it is 2 micrometers or less.

The thinner the base film portion of the optical film, the higher the transmittance.
In addition, the refractive index of the adhesive film is 1.6 or more, and the refractive index of the optical film is 1.6 or less, the magnitude relationship of the refractive index can be light emitting element> adhesive film> optical film, Since the change in refractive index at each interface is alleviated, the reflectance can be reduced.

  In the sealing film of the present invention, the adhesive film includes an adhesive film A and an adhesive film B adjacent to the adhesive film A, and the adhesive film B includes a total of 10% or more of amide, imide resin, or silicone resin, and an average particle size The adhesive film A contains 1% or more of an inorganic filler having a diameter of 10 μm or less, or does not contain a resin having an amide or imide or contains 10% or less, and contains 20% or more of an epoxy resin. The% used here is% by weight.

The refractive index of the adhesive film B is such that Nd is (Na · Ne) ^1/2 ± 0.2, where Na is the refractive index of the adhesive film A, Nb is the refractive index of the adhesive film B, and Ne is the refractive index of the light emitting surface. It is preferable to be in the range. Furthermore, it is preferable that Nb · db is in the vicinity of the wavelength λ · (1/4 + m / 2) where db is the thickness of the adhesive film B. Here, m is an integer of 0 or more.

  However, since the refractive index of the resin is as small as about 1.5, it is difficult to satisfy this condition. If the inorganic filler is dispersed, the refractive index can be increased while being transparent. However, there are problems such as 1) difficult dispersion of fine particles, 2) low transmittance, and 3) high haze value (turbidity).

  These problems are: 1) Use ultrafine particles with a particle size that is small enough not to scatter light except near the interface between the light emitting surface and the adhesive layer. 2) Prevent ultrafine particles from aggregating in the resin. This can be solved if the fine particles themselves do not absorb light. For this purpose, it is necessary to select appropriate ultrafine particles, resin, and dispersant. Thus, the key to the synthesis of a transparent adhesive having a high refractive index is to uniformly disperse the inorganic filler.

  One way to improve dispersion is to apply an appropriate coupling agent or dispersant to a material in which fine particles and a resin are kneaded. By using a coupling agent or a dispersant, a highly transparent sealing film without aggregation of fine particles can be obtained.

  It is preferable to use a coupling agent such as isocyanate silane, epoxy silane, anilino silane, methyl silane, phenyl silane, amino silane, ureido silane, vinyl silane, alkyl silane, mercapto silane, organic titanate, aluminum alcoholate from the viewpoint of improving dispersibility. .

  There is no restriction | limiting in particular about the usage method of these coupling agents, You may use it, after processing to an inorganic filler beforehand. Moreover, you may use by the integral blend method at the time of the mixing | blending of another raw material. Examples of the dispersing agent include Disperbyk-110, Disperbyk-111, Disperbyk-116 and the like of Big Chemie Japan.

  In order to produce a resin containing fine particles, there are two types: a case where a solid powder is mixed in a solution and a case where the solid powder is dispersed in the solution at the time when the particles are synthesized. When the fine particles are solid powder, the resin and the fine particles can be dispersed by kneading by a ball milling method using a planetary bead mill, a method of applying pressure and high temperature, a method of shearing, or the like.

  When the fine particles are dispersed in the solution, they can be dispersed by stirring with a stirrer or ultrasonic waves. Dispersibility can also be increased by using a resin, and dispersibility can be increased by using an amide or imide resin or a silicone resin which is a highly polar functional group.

  When the adhesive film B contains a total of 10% or more of amide, imide resin, or silicone resin, heat resistance can be imparted and the dispersibility of the inorganic filler can be increased. By containing 1% or more of inorganic filler having an average particle size of 10 μm or less, high heat resistance and high refractive index can be realized. The adhesive film A does not include a resin having an amide or imide, or includes 5% or less, and includes 20% or more of an epoxy resin, thereby improving the embedding property.

  Furthermore, it is preferable that the adhesive film after thermosetting contains 1% to 80% of filler in terms of improving dicing properties. The filler amount is more preferably 10 to 60%, and further preferably 20 to 40%.

  By adding a filler, the refractive index can be increased and the light extraction efficiency can be increased. On the other hand, if the filler content is too large, problems such as excessive increase in the storage elastic modulus of the adhesive film, decrease in adhesiveness, and decrease in electrical characteristics due to residual voids are likely to occur. preferable. If the filler content is small, resin burrs tend to occur during dicing.

  As a method of laminating the adhesive film on the base film, in addition to printing, there is a method of pressing and hot roll laminating a pre-made adhesive film on the base film, but it can be continuously manufactured and efficient. A hot roll laminating method is preferable in this respect.

  The optical film may be bonded onto the adhesive film after sealing the adhesive film. Details of the production method for the adhesive containing an imide resin are described in JP-A No. 2002-185687.

The details of the production method for the adhesive containing an amideimide resin are described in JP-A No. 2002-146321.
The details of the production method for the adhesive containing a silicone resin are described in JP-A-6-322349.

  Furthermore, the adhesive film of the present invention is also intended to improve the dicing property of the adhesive film in the B-stage state, improve the handleability of the adhesive film, improve the thermal conductivity, adjust the melt viscosity, and impart thixotropic properties. As a filler, preferably an inorganic filler.

  Examples of the inorganic filler include titania, zirconia, alumina, zinc oxide, crystalline silica, amorphous silica, boron nitride and the like. Alumina and boron nitride are preferred for improving thermal conductivity. For the purpose of adjusting the melt viscosity and imparting thixotropic properties, alumina, crystalline silica, amorphous silica and the like are preferable. In order to improve dicing properties, alumina and silica are preferable.

  For the inorganic filler in the A layer of the adhesive film or the inorganic filler when not separated into the A layer and the B layer, the average particle size of the filler is 0 for titania, zirconia, alumina, zinc oxide, crystalline silica, and amorphous silica. It is preferable that it is 2 micrometers or less. About titania, zirconia, and zinc oxide, it is preferable that it is 0.1 micrometer or less, It is more preferable that it is 0.05 micrometer or less, It is further more preferable that it is 0.002-0.03 micrometer. The smaller the particle size, the higher the transmittance.

  In the present invention, the average particle size of the filler was measured using a laser diffraction type particle size distribution measuring device (Nikkiso Microtrack). Specifically, 0.1 to 1.0 g of filler was weighed and dispersed by ultrasonic waves, then the particle size distribution was measured, and the particle diameter at which the cumulative weight in the distribution was 50% was taken as the average particle diameter.

The average particle size of the inorganic filler in the B layer of the adhesive film is preferably 0.1 μm or more and 10 μm or less, more preferably 1 μm or less, and 0.8 μm or less for titania, zirconia, alumina, and zinc oxide. More preferably, it is most preferable that it is 0.1-0.3 micrometer. By optimizing the particle size, light can be scattered and light extraction efficiency can be increased.
Moreover, it is preferable that the refractive index difference of the refractive index of particle | grains with the light emission surface is 0.5 or less.

  Furthermore, in this invention, when an adhesive film contains a filler, an adhesive film can be favorably cut in a short time, polishing a rotary blade, without leaving resin to a rotary blade at the time of film cutting.

  Therefore, from the viewpoint of the polishing effect of the rotary blade and the adhesive film cutting property, the adhesive film preferably contains a hard filler, more preferably contains a filler having a hardness in the range of Mohs hardness (10 stages) 3-8. Preferably, it contains a filler having a Mohs hardness of 6 to 7.

  At this time, when the Mohs hardness (10 steps) of the filler is less than 3, the polishing effect of the rotary blade is small, and when the Mohs hardness exceeds 8, the life of the rotary blade for dicing tends to be shortened. As fillers having a high refractive index and a Mohs hardness of 3 to 8, there are titania, zirconia and zinc oxide whose crystal system is anatase or rutile.

  The sealing film of the present invention includes an adhesive film A and an adhesive film B adjacent to the adhesive film A. The adhesive films A and B have (1) an epoxy resin and (2) a weight average molecular weight including a functional group of 100,000. It consists of an adhesive composition comprising the above high molecular weight component and (3) an imidazole compound, and the adhesive composition is compatible with the high molecular weight component before curing of the epoxy resin, and the epoxy resin. After curing, a sea island structure is formed by phase separation from the high molecular weight component, and the average width of the sea and island in the center of the adhesive film A when viewed in a cross section perpendicular to the film is 0.3 μm or less, respectively. The average of the width of the sea and the island in the center of the adhesive film B is 0.3 μm or more.

  The combination of (1) epoxy resin and (2) high molecular weight component having a functional group-containing weight average molecular weight of 100,000 or more used in the present invention is preferably a low molecular weight glycidyl epoxy resin as an epoxy resin. Then, an epoxy resin having an aliphatic glycidyl ether group and an epoxy resin having an aromatic glycidyl ether group are preferable.

  The high molecular weight component having a functional group-containing weight average molecular weight of 100,000 or more is preferably a high molecular weight component such as a thermoplastic, a cross-linked reaction rubber, or a thermoplastic elastomer having a functional group having a polarity close to that of an epoxy resin.

  This is because compatibilization depends on the difference in the molecular weight of the resin to be mixed and the polarity of each mixture, and phase separation is formed by the increase in the molecular weight of the epoxy resin due to curing. This is because such a phase separation structure tends to be formed by increasing the compatibility between the epoxy resin and the high molecular weight component and slowing the thermodynamic phase separation rate.

  More specific resins selected in this way include epoxy resins having a molecular weight of less than 400 and epoxy group-containing acrylic polymers, epoxy resins having a molecular weight of 400 or less and epoxy group-containing polyethylene, and epoxy resins having a molecular weight of 400 or less and containing epoxy groups. Examples thereof include a thermoplastic mixture, and among them, a low molecular weight bisphenol A type epoxy resin and an epoxy group-containing acrylic copolymer are preferable in terms of molecular weight, polarity and curing. Details of the resin synthesis method used are described in JP-A-2006-183020.

  Further, when viewed in a cross section perpendicular to the film, the average width of the sea and the island at the center of the adhesive film A is each 0.3 μm or less, and the average width of the sea and the island at the central portion of the adhesive film B is 0 respectively. A sealing film including an adhesive film having a thickness of 3 μm or more is preferable. When the average width of the sea and the island is 0.3 μm or less, a sealing film having high transmittance and high light extraction efficiency can be realized. More preferably, it is 0.2 μm or less.

  On the other hand, by providing a sea or island portion having a high refractive index in the vicinity of the surface of the light emitting element, total reflection on the surface of the light emitting element can be prevented and light extraction efficiency can be increased. At this time, the refractive index difference between the sea and the island is preferably 1/3 or more, more preferably 1/2 or more, of the refractive index difference between the surface of the light emitting element and the adhesive film B. Moreover, it is more preferable that the average width of the sea and the island is 1 μm or more.

  The sealing film of the present invention includes an adhesive film A and an adhesive film B adjacent to the adhesive film A, the adhesive film A has a weight average molecular weight of 100,000 or more and a glass transition temperature Tg of −50. It contains 100 parts by weight of a resin containing 15 to 40% of a high molecular weight component of -50 ° C. and 60 to 85% of a thermosetting component mainly composed of an epoxy resin, and 20 to 200 parts by weight of an inorganic filler. The adhesive film B preferably has a transparent adhesive film having a refractive index higher than that of the adhesive film A by 0.1 or more.

  By separating the adhesive films A and B, the B layer can have a high refractive index and the A layer can be embedded. If a resin contains a large amount of fine particles in order to obtain a high refractive index, the transparency is deteriorated and the embedding property is also deteriorated. The problem can be avoided.

  Since the adhesive film B has a refractive index higher than that of the adhesive film A by 0.1 or more, the light emitting element> the adhesive film B> the adhesive film A can be obtained, and the change in the refractive index at each interface is alleviated. The rate can be reduced. It is more preferable that the adhesive film B has a refractive index higher than the adhesive film A by 0.2 or more.

  When the Tg of the high molecular weight component exceeds 50 ° C., the flexibility of the film may be lowered. When the Tg is less than −50 ° C., the flexibility of the film is too high, so that the film is difficult to cut during wafer dicing. In some cases, burrs are likely to occur.

  Further, the weight average molecular weight of the high molecular weight component is preferably 100,000 or more and 1,000,000 or less, and if the molecular weight is less than 100,000, the heat resistance of the film may be reduced. If the molecular weight exceeds 1,000,000, the film flow may be reduced. May decrease. Here, the weight average molecular weight is a value measured by normal temperature GPC.

  A high molecular weight component having a Tg of −20 ° C. to 40 ° C. and a weight average molecular weight of 100,000 to 900,000 is preferable in that the adhesive film is easily cut during wafer dicing, and resin waste is not easily generated. High molecular weight components having a Tg of −10 ° C. to 40 ° C. and a weight average molecular weight of 200,000 to 850,000 are more preferred.

[Second Embodiment]
In the present invention, the pressure-sensitive adhesive film containing particles having a uniform particle size as shown in FIG. 7 is pressed between the optical film and the light emitting surface at the time of pressure bonding, and the thickness is made to be about the same as the particle size. Can be constant.
Furthermore, the light extraction efficiency can be increased by making the particle surface have a high refractive index. For this purpose, the particle size and composition of the particles of the first embodiment are as follows.

  The particles contained in the adhesive film have an average particle size in the range of 0.04 to 0.6 times the film thickness of the adhesive film, and the average particle size is 0.4 μm or more and 100 μm or less. It is preferable that the average particle diameter of the particles entering 10% by volume from the large diameter particles is smaller than 1.5 times the average particle diameter of the whole particles. The average particle size is a volume average particle size. The particle size can be measured by SEM or TEM (transmission electron microscope).

  Particles in which the particle size of the adhesive film is 0.04 to 0.6 times the film thickness, the average particle size is 0.4 μm or more and 100 μm or less, and the particles enter 10% by volume from the particles having a large particle size By making the average particle size of the particles smaller than 1.5 times the average particle size of the whole particles, it becomes an appropriate particle size with uniform size as shown in FIG. 7, and the film thickness after bonding can be made uniform. Therefore, the variation in the light extraction efficiency between lots can be reduced.

The absolute value of the difference between the refractive index of the particle surface contained in the adhesive film and the refractive index of the adherend surface is preferably 0.5 or less, and the Mohs hardness of the particles is preferably 5 or less.
By applying pressure to the sealing film as shown in FIG. 8 and curing, the surface of the particles is brought into contact with the light emitting surface to prevent total reflection of light incident on the light emitting surface, and the extraction efficiency can be increased.

  Moreover, the light extraction efficiency can be further increased by setting the absolute value of the difference between the refractive index of the particle surface contained in the adhesive film and the refractive index of the adherend surface to 0.5 or less. Since the contact area between the light emitting surface and the particles can be increased by using soft particles having a Mohs hardness of 5 or less, the light extraction efficiency can be increased.

  It is preferable that the particles contained in the adhesive film have a higher refractive index on the particle surface than on the particle surface, and the storage modulus of the material inside the particle is 1 to 3000 MPa.

In addition to the optical design in which the adhesive film B has an average high refractive index, an optical design in which high refractive index particles are attached to the high refractive index light-emitting surface is also possible. In this case, the average particle size is preferably 0.4 μm or more and 3 μm or less.
Moreover, it is preferable that 30% or more of the adhesive film B is particles having a high refractive index.
Further, the difference between the refractive index of the particles and the refractive index of the light emitting surface is preferably 0.5 or less.

  The particles in the adhesive film may have a high refractive index on the outside. The height of the refractive index here is determined by the absolute value of the complex refractive index. For example, silver has a refractive index of 0.17-3.4i, but its absolute value is 3.404. By making the outer side have a high refractive index, it becomes possible to use a flexible low refractive index material on the inner side, and heating can increase the contact interface between the light emitting surface and the high refractive index material.

The light extraction efficiency can be increased by increasing the contact area between the high refractive index material and the light emitting surface.
As the low refractive index material, acrylic, epoxy, or silicone resin can be used.
Further, as the high refractive index material, titania, silver, ITO, zirconia, or the like can be used. In this case, the average particle size is preferably 0.4 μm or more and 3 μm or less.

Since the surface of the particles has a high absolute value of the refractive index, the light extraction efficiency can be increased by scattering the light emitted from the light emitting surface to be adhered and preventing total reflection.
Moreover, since the storage elastic modulus of the material inside the particles is 1 to 3000 MPa, the contact area after thermocompression bonding can be increased as shown in FIG. 9, and the total reflection of light incident on the light emitting surface can be prevented, and light extraction can be performed. Efficiency can be increased.

  Here, the inside of the particle is preferably a resin such as polystyrene, epoxy, acrylic, polyimide, or polycarbonate, and the particle surface is preferably an inorganic material such as titania, zirconia, or silver.

  Organic fine particles having a uniform particle diameter can be produced by an emulsion polymerization method. [(Literature 2), Shunchao Gu, Shouji Inukai, Mikio Konno: “Soap-Free Synthesis of Monodisperse Micronized Sized Particles in Aquamedia” “Soapfree Synthesis of Monodisperse”, “Micron-Sized Polystyrene Particulates in Aquaea”, Journal of Chemical Engineering, Japan, 36. Journal of Chemical Engineering, Japan, 36. Journal of Chemical Engineering, Japan. 1231-1235] and [(Ref. 3), Yoshio Kobayashi, Shunchao Gu, Tomohiro Kondo, Eichi Mine, Eiicho Mine, Nagao, Mikio Konno: “Fabrication of Sub-Micron Sized Titania Hollow Spheres”, Journal of Chemical Engineering of Japan. ), 2004, Vol. 7, No. 7, p. 912-914 or JP-A-07-141912].

Commercially available organic fine particles may be obtained.
Also, the surface coating with an inorganic material can be performed by adding a reactive titanium compound to emulsion-polymerized polystyrene. , Daisuke Nagao, Yoshio Kobayashi, Mikio Konno: “Synthesis of Submicrometer-sized Titania Sphere Particles with a sol gel method and zeal (Synthesis of submicrometer-sized titania special particles wi h a sol-gel method and their application to colloidal photonic crystals), Journal of colloid and interface science (Journal of Colloid and Interface Science), 2005 years, 291 Vol., No. 1, p. 162-168]. For the surface treatment of the resin particles, for example, sulfonation with concentrated sulfuric acid can be used.

Preferably, the adhesive film includes particles having an absolute value of a difference from the refractive index of the light emitting surface of 0.5 or less, the adhesive surface of the adhesive film is polished, and a cross section of the particles is exposed on the surface.
The light extraction efficiency can be improved by including particles having an absolute value of a difference from the refractive index of the light emitting surface of 0.5 or less.

  In addition, by exposing the cross section of the particles to the surface, the contact area with the light emitting surface can be increased when adhered to the light emitting surface. As a result, the light extraction efficiency can be improved. As the abrasive, CMP slurry “HS-T” manufactured by Hitachi Chemical Co., Ltd. can be used.

The adhesive film includes particles having an absolute value of a difference from the refractive index of the light emitting surface of 0.5 or less, and the major axis of the particles is 1.5 times longer than the minor axis, so that the major axis of the particles after sealing Can be in contact with the light emitting surface, and the contact area between the particles and the light emitting surface can be increased.
Titanium oxide rutile tends to form needle crystals and can be used.

[Third Embodiment]
In addition, the sealing film of the item (15) of the present invention comprises an optical film and an adhesive film after sealing, and the glass transition temperature of the optical film is 60 ° C. or higher, and the glass transition temperature of the adhesive film is 60 ° C. There is a refractive index distribution having an irregularity with an average groove depth of 0.1 μm or more or a refractive index change with a refractive index difference of 0.2 or more on the surface of the optical film opposite to the adhesive film, or inside the optical film. There is a refractive index distribution structure having a refractive index change with a refractive index difference of 0.015 or more, or there are irregularities with an average groove depth of 0.1 μm or more at the interface between the optical film and the adhesive film, and the refractive index of the adhesive film is 1. It is a transparent sealing film which is 42 or more.

  Unless the optical film has a glass transition temperature higher than the thermosetting temperature required for sealing the sealing film, the optical film is deformed during the thermosetting of the adhesive film, and the light extraction efficiency is lowered. Since the thermosetting temperature is 60 ° C. or higher, the glass transition temperature is preferably 60 ° C. or higher, more preferably 100 ° C. or higher, even more preferably 150 ° C. or higher, and 200 ° C. or higher. Most preferably. It is because it is preferable that the heating temperature of the thermosetting of an adhesive film is 60-240 degreeC, and it is more preferable that it is 100-180 degreeC.

  If the adhesive film does not have heat resistance after sealing, the adhesive film peels off or discolors due to heat emitted from the light emitting element. The glass transition temperature is more preferably 100 ° C. or higher, further preferably 150 ° C. or higher, and most preferably 200 ° C. or higher. This is because the heat emitted from the light emitting element can be lowered to 80 ° C. if a radiator made of graphite or aluminum is attached, but it becomes 200 ° C. or more without a radiator.

By setting the refractive index of the adhesive film to 1.42 or more, the refractive index difference between the light-emitting element having a high refractive index and the adhesive film can be reduced, and reflection can be suppressed.
Moreover, by making it transparent, light absorption can be suppressed and light extraction efficiency can be increased.

  The refractive index of the adhesive film is more preferably 1.55 or more, and more preferably 1.65 or more. There may be irregularities with an average groove depth of 0.1 μm or more at the interface between the optical film and the adhesive film. Thereby, reflection at the interface between the optical film and the adhesive film may be suppressed.

  Even if the reflection at the interface is not suppressed, the unevenness of the reflection on the emission surface of the optical film is periodic and the average groove width is 0.4 μm or more and 5 μm or less by bending light perpendicular to the emission surface. In some cases, it is preferable that the unevenness of the optical film surface opposite to the adhesive film is not periodic. By not being periodic, the generation of rainbows due to spectroscopy can be suppressed. The average groove depth is preferably 0.4 μm or more, more preferably 0.8 μm or more.

  In 3rd Embodiment, the glass transition temperature of an optical and an adhesive film is a value after sealing, and when distribution is multilayered or inclined, regarding an optical film, the glass transition temperature by the thickness average of a layer is used. For the adhesive film, use the highest layer glass transition temperature. On the other hand, when the phases are separated in the layer, the average glass transition temperature depending on the area in the layer is used.

  In addition, the refractive index of the optical and adhesive film is a value after sealing. When the distribution is multilayered or inclined, the refractive index of the highest layer is obtained. Use the average refractive index of the area of.

  The adhesive film particle has an absolute value of a difference from the refractive index of the light emitting surface of 0.5 or less, has an average particle diameter in the range of 0.04 to 0.6 times the film thickness of the adhesive film, and average The particle diameter is 0.4 μm or more and 100 μm or less, and the average particle diameter of the particles entering 10% by volume from the large particle diameter is smaller than 1.5 times the average particle diameter of the whole particle, and sealing It is preferable that the contact area of the subsequent adhesive film with the light emitting surface is 1.5 times or more larger than the contact area of the particles with the optical film.

  As shown in FIG. 10, the light extraction efficiency can be improved because the contact area between the particles of the adhesive film after sealing is 1.5 times or more larger than the contact area between the particles and the optical film. . More preferably, it is 3 times or more larger. The sealing film is prepared in order from the adhesive layer, and after coating the adhesive layer, the surface opposite to the optical film surface is left facing down, so that the surface having a large particle area can be faced down.

Hereinafter, although the film for sealing of the present invention will be specifically described with reference to examples, the present invention is not limited thereto.
Example 1
2,2-bis [4- (4-aminophenoxy) phenyl] propane in a 0.5 liter four-necked flask equipped with a thermometer, stirrer, nitrogen inlet tube, and cooling tube with an oil / water separator under a nitrogen stream 45.92 g (112 mmol) was added and dissolved by adding 50 g of N-methyl-2-pyrrolidone.

  Next, 23.576 g (112 mmol) of trimellitic anhydride chloride was added while cooling so as not to exceed 20 ° C. After stirring at room temperature for 1 hour, 13.5744 g (134.4 mmol) of triethylamine was added while cooling so as not to exceed 20 ° C., and the mixture was reacted at room temperature for 3 hours to produce a polyamic acid varnish.

  The obtained polyamic acid varnish was further subjected to a dehydration reaction at 190 ° C. for 6 hours to produce a polyamideimide resin varnish. A precipitate obtained by pouring the varnish of the polyamideimide resin into water was separated, pulverized and dried to obtain a polyamideimide resin powder (PAI-1) soluble in a polar solvent at room temperature.

  30 parts by weight of PAI-1 as polyamideimide resin powder, 86 parts by weight of bisphenol A type epoxy resin (epoxy equivalent 175, manufactured by Tohto Kasei Co., Ltd., trade name YD-8125) as epoxy resin, 1- as imidazole compound Glycidyl acrylate or glycidyl as a high molecular weight component having a weight average molecular weight of 100,000 or more containing 14 parts by weight of cyanoethyl-2-phenylimidazole (manufactured by Shikoku Kasei Kogyo Co., Ltd., trade name, Curesol 2PZ-CN, molecular weight 197) and functional group Add cyclohexanone to a composition comprising 230 parts by weight of acrylic rubber (trade name, HTR-860P-3, weight average molecular weight 800,000 manufactured by Nagase ChemteX Corporation) containing 2 to 6% by weight of methacrylate, and stir and mix. Vacuum evacuation gave an adhesive varnish. This adhesive varnish is used as a binder resin.

An epoxy resin containing the above amideimide resin is used as the binder resin. Silica filler [manufactured by Admafine Co., Ltd., S0-C2 (specific gravity: 2.2 g / cm ³ , Mohs hardness 7, average particle size 0.5 μm, specific surface area 6.0 m ² / g)] was mixed 20%. The material was heat-cured and attached to a prism sheet diamond art made by Mitsubishi Rayon having an average groove width of 30 μm.

  The refractive index of the adhesive film is 1.55, and the refractive index of the optical film is 1.49. The film thickness of the adhesive film is 10 μm, and the substrate thickness of the optical film is 100 μm. The total light transmittance of this sealing film was measured. The total light transmittance was 70% at a wavelength of 632.8 nm. The film was transparent.

Example 2
Silica filler [manufactured by Admafine, S0-C2 (specific gravity: 2.2 g / cm ³ , Mohs hardness 7, average particle size 0.5 μm) to a binder using an epoxy resin not containing amide, imide resin and silicone resin , Using a specific surface area of 6.0 m ² / g)] was heat cured and affixed to Mitsubishi Rayon prism sheet diamond art having an average groove width of 30 μm.

  The refractive index of the adhesive film is 1.50, and the refractive index of the optical film is 1.49. The film thickness of the adhesive film is 10 μm, and the substrate thickness of the optical film is 100 μm. The total light transmittance of this sealing film was measured. The total light transmittance was 60% at a wavelength of 632.8 nm. The film was cloudy.

Example 3
A prism sheet with an average groove width of 30 μm was transferred from a mold to a PET film Cosmo Shine A4300 manufactured by Toyobo Co., Ltd., using a UV curable resin Hitaroid 7975 manufactured by Hitachi Chemical Co., Ltd. This was an optical film. The refractive index of the optical film is 1.5. A die bond film HS-230 manufactured by Hitachi Chemical Co., Ltd. having a refractive index of 1.45 was attached to this optical film. The film thickness of the adhesive film is 10 μm, and the substrate thickness of the optical film is 100 μm.

  Next, a large number of light emitting surfaces of the semiconductor light emitting elements were arranged and laminated at 60 ° C., and then cured at 100 ° C. for 1 hour to cure the adhesive film. There was no change in the uneven shape of the optical film.

Example 4
Hereinafter, a resin synthesis method and a film lamination method for a film layer having a layer structure as shown in FIG. 3 will be described.
The adhesive film of the present invention is prepared by mixing and kneading the high molecular weight component, a thermosetting component mainly composed of an epoxy resin, a filler and other components in an organic solvent, and then preparing a varnish on the base film. After the varnish layer is formed and dried by heating, the substrate can be removed.

  The above mixing and kneading can be carried out by appropriately combining dispersers such as a normal stirrer, a raking machine, a triple roll, and a ball mill. The heating and drying conditions are not particularly limited as long as the solvent used is sufficiently volatilized, but it is usually performed by heating at 60 to 200 ° C. for 0.1 to 90 minutes.

  An epoxy resin is used for the adhesive film A. A method for synthesizing this epoxy resin is described in JP-A-2006-183020. An imide resin is used for the resin of the adhesive film B. This refractive index is 1.5. A method for synthesizing this imide resin is disclosed in JP-A No. 2002-185687.

  The adhesive film B was obtained by kneading 40 nm-diameter zirconium oxide nanoparticles made by Sumitomo Osaka Cement into the imide resin in a mortar so as to be 20% with respect to the resin. The refractive index was 1.72.

  As shown in FIG. 12, the adhesive film B is roll-coated on the base film. A polyethylene terephthalate film having a release treatment of 50 μm in thickness was used as the base film. After coating, the film was dried by heating at 90 ° C. for 10 minutes and at 120 ° C. for 5 minutes.

The adhesive film A was roll-coated on the adhesive film B and then heat-dried in the same manner. The above-mentioned hitaloid 7975 is used as the resin for the optical film.
The roll mold is made by cutting a copper mold with a fine shape with a bite and plating it for corrosion protection. Here, striped grooves having an average groove depth of 0.8 μm and a period of 2 μm were produced.

  Next, as shown in FIG. 13, the unevenness of the optical film is transferred onto the adhesive film A from the roll mold. At this time, UV curing is performed. Furthermore, a cover film is laminated. As a cover film, Toyobo Viro Coat was used.

  E1S40-1W0C6-01 from Toyoda Gosei was used as the white LED. In Examples 4, 5, and 6 and the comparative example, this LED was polished with a sandpaper, a certain amount of the fluorescent layer was left and the surface layer portion was removed, and the white LED was used.

Ten of these were arranged on a lead frame as an interposer, sealed together, and then separated with a dicer. In the batch sealing, the sealing film was thermocompression bonded at 60 ° C. and a molding pressure of 1 kg · f / cm ² for 120 seconds and then heated at 100 ° C. for 1 hour.

  When the luminance of each LED before and after application of the sealing film of the present invention was compared, the luminance was improved by 20 ± 10%. The film thickness of the adhesive layer between the optical film and the light emitting surface was 10 ± 2 μm. The power source was Regulated DC Power supply PMC-0.5A manufactured by KIKUSUI, and the current value was 20 mA.

Moreover, the transmittance | permeability of 80% or more was able to be maintained in the heat resistance test of 100 degreeC and 5000 hours.
Furthermore, the transmittance of 80% was maintained in the light resistance test of 3,800 cd / m ² and 5000 hours.
A commercially available luminance meter is used to measure the luminance, and the emission angle is measured in steps of 5 degrees from -80 degrees to +80 degrees. The angle with the highest brightness ± 4 degrees is measured in increments of 1 degree.

When the sealing film has anisotropy, it rotates as appropriate. Measurement is performed under the same conditions as the sealing film to be compared, and a relative comparison is performed. A luminance meter such as TOPCON BM-5 can be used.
The measurement conditions of luminance were such that the distance from the sealing film to the condenser lens of the luminance meter was 20 cm, the field of view was 0.2 °, and the luminance was measured in a continuous mode.

Example 5
Similar sealing was performed using the thermosetting acrylic resin shown in Example 2 of JP-A No. 2005-154688 instead of the hytaloid 7975 used in Example 4 above. The film thickness of the adhesive layer between the optical film and the light emitting surface was 10 ± 3 μm. Equivalent luminance characteristics and durability were obtained.

Example 6
In this study example, in Example 4 described above, the coating procedure was changed to produce irregularities at the interface between the optical film and the adhesive film.
As shown in FIG. 13, the unevenness of the optical film is transferred from the roll mold onto the base film. As the resin for the optical film, a transparent conductive coating material DNT conductive UV curing type (EI-3) made by Dainippon Paint is used. As the substrate film, a polyethylene terephthalate film having a thickness of 50 μm and subjected to a release treatment was used.

  The adhesive film A is roll-coated on the uneven surface of the optical film. After coating, it was dried by heating at 90 ° C. for 10 minutes and at 120 ° C. for 5 minutes. The adhesive film B was roll-coated on the adhesive film A and then heat-dried in the same manner. Further, a cover film is laminated on the adhesive film B.

  The refractive indexes are 1.7 for the optical film 1.7, the substrate film 1.57, the adhesive film A, and the adhesive film B, respectively. The film thickness of the adhesive layer between the optical film and the light emitting surface was 10 ± 3 μm. When the change in luminance of each LED was examined, a luminance increase of 15% ± 5% was observed.

Example 7
In this examination example, among the sealing film of Example 4, the particles of the adhesive film were changed. As the particles, commercially available polystyrene fine particles having a particle diameter of 8 μm were used. The particles were mixed with the adhesive film B.

  The refractive index is 1.7 for the optical film 1.7, 1.5 for the adhesive film A, and 1.6 for the adhesive film B. The refractive index of the polystyrene fine particles is 1.59. The film thickness of the adhesive layer after curing was 9 ± 2 μm. When the change in luminance of each LED was examined, a luminance increase of 20% ± 10% was observed.

Example 8
In this examination example, among the sealing film of Example 4, the particles of the adhesive film were changed. As the particles, commercially available polystyrene fine particles having a particle diameter of 8 μm were used. The particles are heat treated in concentrated sulfuric acid for 1 day. Thereafter, tetrabutyl orthotitanate was reacted with the surface of the particles to obtain particles coated with titania. The above (refer literature 4). The particles were mixed with the adhesive film B.

  The refractive index is 1.7 for the optical film 1.7, 1.5 for the adhesive film A, and 1.7 for the adhesive film B. The refractive index of the polystyrene fine particles is 1.59. The film thickness of the adhesive layer after curing was 9 ± 2 μm. When the change in luminance of each LED was examined, a luminance increase of 25% ± 10% was observed.

Comparative Example 1
E1S40-1W0C6-01 from Toyoda Gosei was used as the white LED. Ten of these were arranged on a lead frame as an interposer. A mold having striped grooves with an average groove depth of 0.8 μm and a period of 2 μm was used.

Using the sealing material described in Example 2 of JP-A-11-343395, the molds were pressed together at a temperature of 100 ° C., a molding pressure of 200 kg · f / cm ² , and a molding time of 120 seconds. The refractive index is 1.5 and the thickness of the adhesive layer is 20 ± 10 μm. When the change in luminance of each LED was examined, a luminance increase of 15% ± 15% was observed.
Thus, the variation in brightness was larger than that of the sealing film with unevenness.

Comparative Example 2
E1S40-1W0C6-01 from Toyoda Gosei was used as the white LED. Ten of these were arranged on a lead frame as an interposer. A mold having striped grooves with an average groove depth of 0.8 μm and a period of 2 μm was used.

The mold was pressed at a temperature of 30 ° C. and a molding pressure of 200 kg · f / cm ² using an atom composite HCS manufactured by Atomics Co., Ltd., which is a two-component solvent-free room temperature curing acrylic hybrid resin. The molding time took 6 hours. The refractive index is 1.5, and the thickness of the adhesive layer is 20 ± 8 μm. When the change in luminance of each LED was examined, a luminance increase of 15% ± 12% was observed.
Thus, sealing time became long compared with the sealing film with an unevenness | corrugation. Also, the luminance variation was large.

Example 9
As shown in FIG. 11, the adhesive film was pressed against the high refractive index glass with a pressure 48, and the light extraction efficiency of the oblique incident light 56 from the transparent glass 54 was measured at room temperature. The pressure bonding condition is 1 kg · f / cm ² in pressure, and no heat is applied. The incident light 58 is a He—Ne laser and has a wavelength of 632.8 nm. A digital power meter 64 made by Advantest was used to detect the emitted light 62.

  The polarization of incident light was measured for two types that differ by 90 degrees and averaged. The adhesive film 52 was attached to the transparent optical film 50 using a double-sided adhesive tape. The surface of the adhesive film in contact with the transparent glass 54 was polished in the order of alumina having a particle size of 0.5 μm and alumina having a particle size of 0.03 μm as an abrasive. The surface of the transparent glass 54 having a refractive index of 2 was mirror-polished, and light was incident thereon.

As the filler, rutile spherical titania TiO ₂ having an average particle diameter of 0.25 μm is used, and the filler amount is 50% by volume. As the resin, the binder resin used in Example 1 was used. The film thickness of the adhesive film is 250 μm. A pressure 48 was applied to the optical film 50 against the surface of the high refractive index glass 54. A prism sheet diamond art made by Mitsubishi Rayon having an average groove width of 30 μm was used for the optical film. The amount of light emitted with and without an adhesive film was measured with a power meter.

  The amount of decrease in the amount of emitted light when the adhesive film was present compared with the amount of emitted light without the adhesive film was defined as the light amount reduction rate. When the incident angle θ exceeds the critical angle and the adhesive film 52 is not present, the incident light 56 is totally reflected on the surface of the high refractive index glass 54 adhesive film.

  However, when the adhesive film 52 greatly changes the refractive index distribution on the surface of the high refractive index glass, a part of the incident light 56 leaks outside without being totally reflected. As a result, the amount of emitted light is reduced. The amount of light extracted through the adhesive film 52 can be qualitatively known from the light amount reduction rate indirectly. Here, θ was set to 72 °. The evaluation results of the light extraction efficiency are as shown in Table 1.

Example 10
As the filler, spherical alumina Al ₂ O ₃ having an average particle diameter of 3 μm was used, and an adhesive film was produced in the same manner as in Example 9. The evaluation results of the light extraction efficiency are as shown in Table 1.

Example 11
As the filler, a plate-like alumina Al ₂ O ₃ having an average particle diameter of 10 μm was used, and an adhesive film was produced in the same manner as in Example 9. The evaluation results of the light extraction efficiency are as shown in Table 1.

Example 12
The resin was evaluated in the same manner as in Example 9 on an adhesive film in which no filler was added to the binder resin used in Example 1. The evaluation results of the light extraction efficiency are as shown in Table 1.

It is sectional drawing which shows one embodiment of a sealing film. It is sectional drawing which shows one embodiment of the sealing film bonded together to the light emitting element 26 of this invention. It is sectional drawing which shows one embodiment of the sealing film which attached the cover film 18 and the base film. It is sectional drawing which shows one embodiment of a sealing film. It is the schematic which shows one embodiment of the process at the time of adhere | attaching the sealing film of this invention to the light emitting element 30 by which wire bonding was carried out. 4 is a schematic view showing an embodiment of a process when the sealing film of the present invention is bonded to the back surface of the electrode of the light emitting element 36. FIG. It is the schematic which shows one embodiment of the sealing film which uses the adhesive film containing the particle | grains 40 with uniform particle size as a component.

It is the schematic which shows one embodiment of the sealing film which uses the adhesive film containing the particle | grains 40 whose outer side is a high refractive index as a component. It is the schematic which shows one embodiment when the sealing film which uses the adhesive film 42 containing the particle | grains 44 with the high refractive index as the outer component is thermocompression bonded to the light emitting surface. These are the schematic diagrams which show one embodiment when the sealing film which uses the adhesive film 38 containing the particle | grains 40 of the high refractive index as a component is thermocompression-bonded to the light emission surface. It is the schematic which shows one embodiment of light extraction efficiency evaluation. It is sectional drawing which shows one embodiment of adhesive film preparation by a roll. It is sectional drawing which shows one embodiment of optical film production by a roll, and bonding with an adhesive film.

Explanation of symbols

10 optical film 12 adhesive film 14 adhesive film A
16 Adhesive film B
18 Cover film 20 Base film 22 Optical film 24 Adhesive film 26 Light emitting element 28 Wire bonding wire 30 Light emitting element 32 Conductive paste 34 Interposer 36 The light emitting element 38 whose electrode is opposite to the light emitting surface The outer side is made of particles having a high refractive index. Including adhesive layer

40 High Refractive Index Particles 42 Adhesive Layer 44 Containing High Refractive Index Particles After Thermocompression Bonding Outer High Refractive Index Particles 48 Pressure 50 Optical Film 52 Adhesive Film 54 Transparent Glass 56 Incident Light 58 Incident Light 60 Laser Transmitter 62 Outgoing light

104 Resin tank 106 Pressure control device 108 Supply head 110 Resin before curing 112 Doctor blade 114 Transparent film 116 Film sheet 118 Metering roll 120 Nip roll 122 Mold roll 124 Mold release roll 126 Manufacturing apparatus 128 Ultraviolet irradiation apparatus 130 Concavity and convexity mold Roll 132 Transparent film 134 including adhesive film Film sheet 136 Resin before UV curing

Claims (16)

  It consists of an optical film and an adhesive film, the glass transition temperature of the optical film is 60 ° C. or higher, the glass transition temperature of the adhesive film is 130 ° C. or lower, and the refractive index of the adhesive film is 1.42 or higher, (1) There is a refractive index distribution on the surface of the optical film opposite to the adhesive film that has irregularities with an average groove depth of 0.1 μm or more or a refractive index change with a refractive index difference of 0.2 or more, or (2) refraction inside the optical film. A transparent sealing film having a refractive index distribution structure having a refractive index change of 0.015 or more, or (3) an unevenness having an average groove depth of 0.1 μm or more at the interface between the optical film and the adhesive film.   The adhesive film includes an adhesive film B having a film thickness of 0.1 μm or more and 14 μm or less and a refractive index of 1.6 or more, and an adhesive film A adjacent to the adhesive film B, and the refractive index of the adhesive films A and B is The sealing film according to claim 1, wherein the difference is 0.1 or more, and the film thickness of the adhesive film is 100 μm or more.   Sealing in which the adhesive film has a film thickness of 0.1 μm or more and 14 μm or less, a refractive index of 1.6 or more, a film thickness of the substrate portion of the optical film of 10 μm or less, and a refractive index of 1.6 or less the film.   The adhesive film includes an adhesive film A and an adhesive film B adjacent to the adhesive film A, the adhesive film B includes a total of 10% or more of amide, imide resin, or silicone resin, and 1 inorganic filler having an average particle size of 10 μm or less The sealing film according to claim 1, wherein the adhesive film A contains no amide or imide resin or contains 10% or less and the epoxy resin contains 20% or more.   The adhesive film includes an adhesive film A and an adhesive film B adjacent to the adhesive film A, and the adhesive films A and B are (1) an epoxy resin and (2) a weight average molecular weight including a functional group is 100,000 or more. It consists of an adhesive composition comprising a molecular weight component and (3) an imidazole compound, and the adhesive composition is compatible with the high molecular weight component before curing of the epoxy resin and after curing of the epoxy resin. A sea-island structure is formed by phase separation from the high molecular weight component, and the average width of the sea and island in the center of the adhesive film A when viewed in a cross section perpendicular to the film is 0.3 μm or less, respectively. The sealing film in any one of Claims 1-4 containing the adhesive film whose average of the width of the sea and island of a part is each 0.3 micrometer or more.   The adhesive film includes an adhesive film A and an adhesive film B adjacent to the adhesive film A, and the adhesive film A has a weight average molecular weight including a crosslinkable functional group of 100,000 or more and a glass transition temperature Tg of −50 to 50 ° C. It contains 100 parts by weight of a resin containing 15 to 40% of a high molecular weight component and 60 to 85% of a thermosetting component mainly composed of an epoxy resin, and 20 to 200 parts by weight of an inorganic filler, and has a thickness of 100 to 10,000 μm. The sealing film according to claim 1, wherein the adhesive film B has a refractive index higher than that of the adhesive film A by 0.1 or more. The sealing film according to any one of claims 1 to 6, wherein a difference in linear expansion coefficient between the optical film and the adhesive film in contact with the optical film is 0.5 x ^10-4 or less.   The sealing film according to claim 1, wherein the optical film is made of a thermosetting resin.   The sealing film according to claim 1, wherein the optical film or the adhesive film contains a phosphorescent or fluorescent material.   The particles contained in the adhesive film have an average particle size in the range of 0.04 to 0.6 times the film thickness of the adhesive film, and the average particle size is 0.4 μm or more and 100 μm or less. The sealing film according to any one of claims 1 to 9, wherein an average particle diameter of particles entering a volume of 10% from particles having a large diameter is smaller than 1.5 times of the whole particles.   The absolute value of the difference between the refractive index of the particle surface and the refractive index of the adherend surface contained in the adhesive film is 0.5 or less, and the Mohs hardness of the particles is 5 or less. The sealing film as described.   The particle contained in the adhesive film has a higher refractive index on the particle surface than on the particle surface, and the storage elastic modulus of the material inside the particle is 1 to 3000 MPa. The sealing film of crab.   The adhesive film contains particles having an absolute value of a difference from the refractive index of the light emitting surface of 0.5 or less, the adhesive surface of the adhesive film is polished, and the cross section of the particles is exposed on the surface. The sealing film in any one.   The adhesive film according to claim 1, wherein the absolute value of the difference from the refractive index of the light emitting surface is 0.5 or less, and the major axis of the particle is 1.5 times or more longer than the minor axis. The sealing film in any one.   It consists of an optical film and an adhesive film, the glass transition temperature of the optical film after sealing is 60 ° C. or higher, the glass transition temperature of the adhesive film is 60 ° C. or higher, and the average groove on the surface of the optical film opposite to the adhesive film Refractive index distribution structure having unevenness with a depth of 0.1 μm or more, or a refractive index distribution having a refractive index change of 0.2 or more, or having a refractive index change of 0.015 or more inside the optical film Or a transparent sealing film in which there are irregularities having an average groove depth of 0.1 μm or more at the interface between the optical film and the adhesive film, and the refractive index of the adhesive film is 1.42 or more.   The adhesive film particles after sealing have an absolute value of a difference from the refractive index of the light emitting surface of 0.5 or less, and an average particle size in the range of 0.04 to 0.6 times the film thickness in the adhesive film. And the average particle size of the particles is 0.4 μm or more and 100 μm or less, and the average particle size of particles having a volume of 10% by volume is larger than 1.5 times the average particle size of all particles. The sealing film according to claim 15, wherein the contact area of the adhesive film after sealing is smaller than the contact area of the particles with the optical film by 1.5 times or more than the contact area of the particles with the optical film.

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