JP2013201175A - Light reflector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a light reflector which has a high heat resistance, and a high reflectance to light of a visible light region, which is less prone to be reduced in reflectance in high-temperature thermal load and UV environments, and which can be used as a reflector adapted to LED mounting; and an LED package having the reflector used therein.SOLUTION: The light reflector is produced by molding a resin composition including a thermosetting silicone resin (A) and alumina (B) blended into the silicone resin. The sodium content in the alumina (B) is no less than 80 ppm below 300 ppm. The reflector achieves an average reflectance of 94% or more against light of a wavelength of 350-450 nm with a thickness of 0.4 mm.

Description

  The present invention relates to a light reflector having excellent heat resistance and high reflectance characteristics. In particular, it is suitable as a light reflector for light in the short-wavelength light region such as the ultraviolet region, and more specifically, (long-term) high-temperature heat negative such as a solder reflow process, and further severe conditions such as ultraviolet (UV) irradiation. The present invention also relates to a light reflector and the like suitable as a light reflector of an LED package on which a light emitting diode (Light Emitting Diode; hereinafter abbreviated as LED) or the like is mounted.

LEDs have features such as small size, light weight, and energy saving, and are widely used in electronic devices as backlight light sources for personal computers, televisions, mobile phones and the like and various display light sources such as numeric keypad lighting.
In LED, an LED element is an LED package composed of an electrode member, a light reflecting member, an LED element sealing resin member, and the like, and a form in which the LED element is mounted on a wiring board or the like is generally used. There are various LED package structures such as a shell type, surface mount type, COB type, and power LED type. Among them, the surface mount type package undergoes a solder reflow process in the same manner as a general semiconductor package. And is widely used because it can be mounted on printed circuit boards.

  In recent years, the amount of heat generated by the LED element itself has increased due to a significant improvement in LED brightness enhancement technology. Along with this, the thermal load applied to the periphery of the printed wiring board and the like increases, and the LED element peripheral temperature may exceed 100 ° C. in some cases. Further, in the LED package manufacturing process, the wiring substrate is exposed to a high temperature environment of about 200 to 300 ° C. in the thermosetting process in the LED element sealing resin and the solder reflow process in the case of using lead-free solder. In some cases.

  Under such a heat load environment, a light reflector made of a polyamide-based resin that has been conventionally used has low light resistance, so that the light reflector itself is yellowed, and the whiteness of the light source is reduced or the reflection efficiency is inferior. There was a problem to say. Further, there is a tendency that the whiteness decreases and the reflectance decreases, such as yellowing under light irradiation, particularly under ultraviolet irradiation, and there is still room for improvement as a reflector for mounting next-generation high-brightness LEDs.

  For such problems, a light reflector using ceramic has been studied. However, although this light reflector is excellent in terms of heat resistance, there is a limit to thinning because of its hard and brittle nature, and there is a problem that the end portion is likely to be cracked or chipped during the mounting process. In addition, the current manufacturing cost is high. As reflectors for future general lighting and display applications, development of heat-resistant thermoplastic resin-based reflectors that do not change color or reflectivity under high-temperature heat load or UV irradiation is required. It was. In addition, with the current whitening of LEDs, higher reflectivity in the ultraviolet region has been demanded.

  For these problems, for example, Patent Document 1 discloses that LED reflector molding includes 1 to 40 parts by mass of titanium oxide and 5 to 30 parts by mass of a reinforcing material with respect to 100 parts by mass of a specific polyamide resin. A polyamide resin composition has been proposed. Specifically, for example, a plate having a thickness of 1 mm, a width of 40 mm, and a length of 100 mm obtained by injection molding of the polyamide resin composition is disclosed.

  In Patent Document 1, the reflector made of this resin composition has a reflectance of more than 80% at a wavelength of 470 nm even under a heat load (3 hours at 180 ° C.), and maintains high whiteness. It is stated that even when heat is applied at 0 ° C. for 10 seconds, the molded specimen does not deform or swell and is excellent in solder reflow heat resistance.

  In Patent Document 2, the reflectance for light of each wavelength in the range of 250 nm to 750 nm is 70% or more, and the difference between the reflectance in the long wavelength region (750 nm) and the reflectance in the short wavelength region (300 nm) is 20%. A light-emitting element mounting ceramic sintered body comprising a sintered body having a light reflecting surface and having no layer peeled from the light reflecting surface, and having a light reflectivity ranging from the ultraviolet region to the visible light region. It describes a ceramic sintered body for mounting a high light emitting element. Specifically, a substrate manufactured to have a thickness of approximately 0.6 mm is disclosed. It is described that the substrate made of the ceramic sintered body has a reflectance of 90% or more at all wavelengths of 250 nm to 750 nm.

  Further, Patent Document 3 includes (A) thermosetting organopolysiloxane, (B) white pigment, (C) inorganic filler (excluding white pigment), (D) curing catalyst, (E) release material, ( F) A white thermosetting silicone resin composition for forming an optical semiconductor case containing a silane coupling agent as an essential component, wherein the unit cell in which the white pigment of component (B) is surface-treated with alumina or silica and alumina is anatase It describes a white thermosetting silicone resin composition for forming an optical semiconductor case, which is a titanium dioxide having a mold structure and has a light reflectance of 80% or more at a wavelength of 350 to 400 nm.

  Specifically, a disk having a diameter of 50 mm and a thickness of 3 mm is disclosed. The reflector composed of the silicone resin composition has a reflectance of more than 90% at 400 nm, and further has no decrease in reflectance at 470 nm after heat treatment at 180 ° C. for 24 hours, and after 24 hours of UV irradiation. It is noted that there is no decrease in reflectance at 470 nm.

JP 2011-21128 A W02007 / 034955 JP 2011-54902 A

  However, in the light reflector described in Patent Document 1, the reflectance decrease at 470 nm after heat treatment at 180 ° C. for 3 hours was 9.5 to 28.2%, and the suppression thereof was still insufficient. In addition, the whiteness after heat treatment at 180 ° C. for 4 hours was also reduced by 9.5 to 28.2, and the heat resistance of reflectance and whiteness was insufficient.

  In addition, the ceramic sintered body for mounting a light emitting element described in Patent Document 2 cannot avoid a decrease in reflectance due to UV irradiation, and is also industrially applied to a reflector for mounting an LED from the viewpoint of hard and brittle properties and workability. Was difficult.

  Further, with respect to the silicone resin composition described in Patent Document 3, the disc proposed in Patent Document 3 is a thick molded product having a thickness of 3 mm, and thus may have high reflectivity. There is still a question as to whether the same reflectance can be realized when the thickness of the LED mounting substrate (specifically, for example, several hundred μm thick) is used.

INDUSTRIAL APPLICABILITY The present invention is a light reflector that can be used as a LED mounting reflector that has high heat resistance, high reflectance for light in the visible light region, and little reduction in reflectance under a high-temperature heat load environment and a UV environment. Is to provide.

  In order to further improve such problems, the present inventors pay particular attention to the constituent material of the silicone resin composition and its reflectance, and specifically, alumina (B) is added to the thermosetting silicone resin (A). A resin composition obtained by blending and a light reflector obtained by molding the resin composition were studied.

  As a result, in the relationship between the sodium content in alumina (B) and the light reflectance of the light reflector formed by molding this resin composition, the light reflectance is improved by reducing the sodium content. I found out. Surprisingly, it has been found that when the sodium content falls below a specific amount, the light reflectance decreases.

  And as a resin composition formed by blending alumina (B) with thermosetting silicone resin (A), a resin composition having a sodium content in alumina (B) within a specific range is molded, and the thickness is 0. The present inventors have completed the present invention by finding a light reflector capable of solving these problems, which has excellent reflection characteristics such that the average reflectance with respect to light having a wavelength of 350 nm to 450 nm is 94% or more even though the thickness is 4 mm.

That is, the gist of the present invention is the following (1) to (11).
(1): A light reflector obtained by molding a resin composition obtained by blending alumina (B) with thermosetting silicone resin (A), wherein the sodium content of alumina (B) is 80 ppm or more and 300 ppm. A light reflector having an average reflectance of 94% or more with respect to light having a wavelength of 350 nm to 450 nm at a thickness of 0.4 mm.

(2) The light reflector according to (1), wherein the thermosetting silicone resin has a methyl group bonded to a silicon atom.

(3) The light reflector according to (1) or (2), wherein the average particle diameter of alumina (B) is 0.1 μm or more and 1.5 μm or less.

(4): The ratio of alumina (B) to the total of thermosetting silicone resin (A) and alumina (B) is 30% by mass or more and 70% by mass or less (1) to (3) The light reflector according to any one of the above.

(5) The light reflector according to any one of (1) to (4), wherein the alumina (B) is substantially spherical.

(6): Any one of (1) to (5), wherein an average reflectance with respect to light having a wavelength of 350 nm to 450 nm at a thickness of 0.4 mm after heat treatment at 200 ° C. for 185 hours is 94% or more The light reflector as described in.

(7): Any one of (1) to (6), wherein an average reflectance with respect to light having a wavelength of 350 nm to 450 nm at a thickness of 0.4 mm after heat treatment at 300 ° C. for 5 minutes is 94% or more The light reflector as described in.

(8): The average reflectance with respect to light having a wavelength of 350 nm to 450 nm at a thickness of 0.4 mm after UV irradiation for 48 hours is 94% or more, (1) to (7) Light reflector.

(9): The storage elastic modulus (E ′) at a vibration frequency of 10 Hz and a temperature of 20 ° C. in the dynamic viscoelasticity measurement is 1 MPa or more and 1000 MPa or less, according to any one of (1) to (8) Light reflector.

(10): A light reflector for an LED package substrate using the light reflector according to any one of (1) to (9) above.

(11): An LED package substrate including the light reflector according to any one of (1) to (10) above.

  The light reflector of the present invention has excellent heat resistance, high reflectivity in the ultraviolet region (350 nm to 450 nm), and low reduction in reflectivity due to discoloration under high temperature heat load environment and UV irradiation. There is a light reflector. In other words, light reflection characteristics can be suppressed even in high-temperature environments or for long-term use, and as a light reflector for LED packages, as backlights for various lighting fixtures, personal computers, televisions, mobile phones, etc. Can be widely used.

Hereinafter, although embodiment of this invention is described, the scope of the present invention is not limited to this embodiment.

[Silicone resin (A)]
As the thermosetting silicone resin (hereinafter, simply referred to as “silicone resin”) (A) used in the present invention, any conventionally known silicone resin can be used. For example, a resin obtained by crosslinking a compound having a siloxane skeleton represented by the formula (1), specifically, for example, a carbon-carbon unsaturated bond (particularly a vinyl group), a silicon-hydrogen bond, and oxetanyl in the molecule. And polyorganosiloxane having a group.

R in the above formula (1) represents an alkyl group such as a methyl group or an ethyl group; a vinyl group; a hydrocarbon group such as a phenyl group; or a halogen-substituted hydrocarbon group such as a fluoroalkyl group. Specifically, for example, R in the above formula (1) is a polydimethylsiloxane in which all methyl groups, or a part of the methyl group of the polydimethylsiloxane is the above hydrocarbon group or the above halogen-substituted hydrocarbon group. Examples include various polyorganosiloxanes substituted by one or more species. Among them, in the present invention, from the viewpoint of weather resistance and the like, in the above formula, part or all of R is preferably an alkyl group, and in particular, it is a methyl group from the viewpoint of shortening the curing time and light reflection characteristics. preferable.
In addition, the silicone resin (A) used for this invention may be used individually by 1 type, or may use 2 or more types of mixtures and copolymers which consist of arbitrary ratios.

  Moreover, the silicone resin (A) used for this invention may be bridge | crosslinked. The crosslinking group and crosslinking method are not particularly limited, and any conventionally known crosslinking group or crosslinking method can be used. For example, as a crosslinking group, a method of crosslinking a methyl group or vinyl group of a polyorganosiloxane by a radical reaction, a method of crosslinking by a condensation reaction of a silanol-terminated polyorganosiloxane and a silane compound having a hydrolyzable functional group, Or the method of bridge | crosslinking by the addition reaction of the hydrosilyl group to a vinyl group is mentioned. Among these, it is particularly preferable to crosslink by an addition reaction that does not generate a by-product during curing.

  Specific examples of the method for crosslinking the silicone resin (A) include a method in which a curing catalyst is added and heated at a high temperature. Examples of the curing catalyst include aminosilane, nickel salt, and ammonium salt catalysts, octylates such as aluminum, iron, cobalt, manganese, and zinc, metal soaps such as naphthenates, and platinum catalysts. Moreover, as the reaction conditions, specifically, for example, when the catalyst is added, it is cured by heating at 100 ° C. to 180 ° C. for about 1 second to 30 minutes to obtain the silicone resin (A).

  Moreover, as a silicone resin (A) used for this invention, you may use the silicone which modified some methyl groups and a phenyl group. Specific examples of the modified silicone include various silicone resins such as alkyl modification, aralkyl modification, fluoroalkyl modification, polyether modification, amino modification, acrylic modification, and epoxy modification.

  The form of the silicone resin (A) used in the present invention is arbitrary, and may be appropriately selected and determined. Specific examples include rubbers, millables, varnishes, resins, elastomers, gels and the like, but are not particularly limited. Alternatively, the silicone resin may be dissolved in a solvent and used as a solution type. Solvents include hydrocarbons such as toluene and xylene, ketones such as acetone and methyl ethyl ketone, ethers such as diethyl ether and tetrahydrofuran, and esters such as propylene glycol monomethyl ether acetate and ethyl acetate. It is not limited.

  Specific examples of the silicone resin (A) used in the present invention include, for example, trade names “KEG-2000 series”, “KEG-2001 series”, “KE-1950 series” manufactured by Shin-Etsu Chemical Co., Ltd. -Product names "LSR-2670", "LSR-7070", "XE13-0810" manufactured by Performance Materials, etc., and product names "JCR6101UP" manufactured by Toray Dow Corning, etc. may be mentioned.

(alumina)
The alumina (B) used in the present invention has a sodium content of 80 ppm or more and less than 300 ppm. When the content of Na in the alumina particles used in the present invention is too high, the absorption of incident light by Na is too great, and the light reflectance is significantly reduced. Conversely, if the Na content is too low, the dispersibility of the alumina particles is significantly reduced, and the alumina particles are excessively aggregated, so that the specific surface area is reduced and the light reflector rate is reduced. Therefore, among these, the sodium content of alumina (B) is more preferably 90 ppm to 250 ppm, and particularly preferably 90 ppm to 200 ppm.

In the present invention, the sodium content of alumina (B) is a value measured by the following method. The measurement method of the sodium content of alumina (B) is the following (i) to (Vii).
(I) About 0.2 g of powdered alumina is weighed.
(Ii) Put the alumina in a glass bottle. To this is added 5 cc of 35% hydrochloric acid.
(Iii) Leave as it is at room temperature for 3 hours to obtain an alumina hydrochloric acid solution.
(IV) About 5 cc of pure water is put into a 25 ml volumetric flask, the alumina hydrochloric acid solution obtained in (iii) is added, and then pure water is added so that the total amount becomes 25 ml.
(V) The 25 ml aqueous solution of alumina hydrochloric acid obtained in (iV) is filtered using a filter paper.
(Vi) After filtration, ICP measurement is performed to quantify the amount of sodium. Sodium quantification is carried out using a wavelength of 589.592 nm and comparing with a standard solution having a sodium content of 100 ppm.
(Vii) Ratio of sodium content determined by ICP to alumina content; sodium content is calculated from (sodium content determined by ICP / alumina content).

  The alumina (B) used in the present invention satisfies the above-mentioned characteristics and is an average of light having a wavelength of 350 nm to 450 nm at a thickness of 0.4 mm as a characteristic of a light reflector formed by molding the obtained silicone resin composition. If the reflectance is 94% or more, the type and form are particularly arbitrary, and may be appropriately selected and determined. Among them, crystalline alumina such as α-alumina and γ-alumina is preferable as the form, among them because of chemical stability, high melting point, high mechanical strength, high hardness, high electrical insulation resistance, etc. α-alumina is particularly preferred.

  The shape of alumina is also arbitrary, and any shape can be used. Among them, it is preferable to use spherical alumina having a higher sphericity than amorphous alumina, preferably substantially spherical alumina, since wear on a kneader or a mold during kneading with a silicone resin can be reduced. Furthermore, it is preferable to use this substantially spherical alumina because it is easy to increase the content in the silicone resin (high filling), and the reflectance of the light reflector of the present invention can be improved.

  The average particle diameter of alumina (B) used in the present invention is generally 0.1 to 5 μm. If the average particle size is too large, the light reflectance may decrease due to a decrease in the specific surface area. Conversely, if the average particle size is too small, the aggregation may be remarkable and the dispersibility may decrease, and the light reflectance may also decrease. is there. Therefore, the average particle diameter is preferably 0.1 to 3 μm, more preferably 0.1 to 3 μm, more preferably 0.1 to 1.5 μm, and particularly preferably 0.5 to 1.5 μm.

  In the resin composition obtained by blending alumina (B) with thermosetting silicone resin (A) for use in the present invention, the content of alumina (B) is arbitrary, so long as the effect of the present invention is not impaired. For example, it may be selected and determined in consideration of various characteristics required for the light reflector.

  If the content of alumina in the resin composition used in the present invention is too small, the reflectivity of the light reflector of the present invention may not be sufficiently obtained. In addition, the viscosity of the silicone resin composition may become too high and moldability may decrease, and wear of a molding machine or the like may occur.

  Therefore, generally, the content of alumina in the resin composition used in the present invention is 30 to 80% by mass. Especially, it is preferable that it is 30-70 mass%, Furthermore, when it is 35-65 mass%, especially 40-60 mass%, the light reflector of this invention has a favorable reflective characteristic, Moreover, the thickness Good reflection characteristics can be obtained even when the thickness is reduced.

(Reflectance)
One feature of the light reflector of the present invention is that the average reflectance at a wavelength of 350 nm to 450 nm at a thickness of 0.4 mm is 94% or more. In the present invention, the average reflectance at a wavelength of 350 nm to 450 nm at a thickness of 0.4 mm is the reflectance when the reflectance of the alumina white plate is set to 100% for a light reflector sample having a thickness of 0.4 mm. It is the average value of the light reflectance obtained by measuring at intervals of 0.5 nm over a range of 300 nm to 800 nm. The average reflectance of the light reflector of the present invention is 94% or more. Specifically, for example, it is possible to increase the brightness by efficiently reflecting the short wavelength region with the whitening of the LED.

  The average reflectance at a wavelength of 350 nm to 450 nm with a thickness of 0.4 mm of the light reflector of the present invention is preferably 95% or more, particularly 96% or more from the viewpoint of increasing the brightness. In addition, in this invention, in the light reflector obtained by shape | molding the resin composition formed by mix | blending an alumina (B) with a thermosetting silicone resin (A), the average with respect to the light of wavelength 350nm-450nm in thickness 0.4mm. The reflectance of 94% or more means that the average reflectance in a measurement sample that is not subjected to heat treatment or UV irradiation unnecessary for molding the light reflector on the light reflector obtained by molding this resin composition. Indicates.

  Moreover, as alumina (B) used in the present invention, in order to improve dispersibility in the silicone resin (A), inorganic compounds such as siloxane compounds and silane coupling agents, and organic compounds such as polyols and polyethylene glycols are used. It may be used for surface treatment.

  In the present invention, in addition to alumina (B), it may contain an inorganic filler with little absorption of short-wavelength light, specifically, for example, zinc oxide, barium titanate, boehmite, magnesium oxide, etc. You may use 2 or more types together by 1 type or arbitrary ratios.

  Furthermore, in this invention, as components other than the said silicone resin (A) and an alumina (B), in the range which does not impair the effect of this invention, resin other than a silicone resin (A), other than an alumina (B) Various additives such as a heat stabilizer, an ultraviolet absorber, a light stabilizer, a colorant, a lubricant, a flame retardant and the like may be blended.

  The light reflector of the present invention may be a resin molded body having an extremely thin or thin portion, such as a light reflector in an LED package, specifically, in a thin portion having a thickness of 0.4 mm. The average reflectance for light having a wavelength of 350 to 450 nm has an extremely excellent characteristic of 94% or more.

  Furthermore, the light reflector of the present invention has long-term heat resistance. Specifically, the average reflectance at a wavelength of 350 nm to 450 nm is 94% even after heat treatment at 200 ° C. for 185 hours (after the heating test). It is the above and has the outstanding characteristic. Thus, the light reflector of the present invention is preferable because it has excellent characteristics for maintaining sufficient reflection characteristics as a reflector even under a long-term high-temperature heat load environment. In addition, as such a heat processing method, the method of heating for 185 hours with the circulation type dryer set to 200 degreeC, for example is mentioned.

  The light reflector of the present invention has an average reflectance of 94% or more with respect to light having a wavelength of 350 to 450 nm even after heat treatment at 300 ° C. for 5 minutes (after a heating test). The reflectance after the heat treatment heating test is preferably 95% or more, and particularly preferably 97% or more.

  By maintaining such a high reflectivity after the heating test, the reflective performance of the light reflector does not deteriorate even when exposed to a high temperature environment due to a solder reflow process or heat generation during use. Since it becomes a light reflector which can be used for a long time, it is preferable. In addition, specifically as such a heat processing method, the method of heating for 5 minutes with the circulation type dryer set to 300 degreeC etc. is mentioned, for example.

  Furthermore, the light reflector of the present invention has an excellent reflectivity of 94% or more with respect to light having a wavelength of 350 to 450 nm at a thickness of 0.4 mm after UV irradiation for 48 hours. In particular, the reflectivity after UV irradiation is preferably 94% or more, more preferably 95% or more, and particularly preferably 96% or more. If the reflectance after ultraviolet irradiation is 94% or more, even when a near-ultraviolet LED is used, the reflection performance of the light reflector does not deteriorate, and long-term use becomes possible.

  In addition, the light reflector of the present invention preferably has a storage elastic modulus (E ′) at a vibration frequency of 10 Hz and a temperature of 20 ° C. in dynamic viscoelasticity measurement of 1 to 1000 MPa, more preferably 5 to 500 MPa, It is preferably 5 to 100 MPa, particularly 5 to 30 MPa. As long as the storage elastic modulus of the light reflector is within the range, it can follow the load applied during molding or use, and also has sufficient rigidity to suppress excessive deformation. can do.

[Use of light reflector]
Since the light reflector of the present invention has excellent reflection characteristics, heat resistance, and light resistance, the deterioration of the reflection characteristics is suppressed even in a high temperature environment or for a long period of use, and various shapes (for example, films) , Plates, molded products, etc.), as LED package light reflectors, various lighting fixtures, backlights for personal computers, televisions, mobile phones, etc., and LED mounting substrates with light reflection performance Can be widely used for etc.

[Production method]
Although the manufacturing method of the light reflector of the present invention is not particularly limited, for example, the silicone resin (A), alumina (B), and other additives as necessary are planetary mixers, dissolvers, roll mills, various kneaders. After mixing uniformly by using any conventionally known mixing / stirring machine such as the above, using an arbitrary conventionally known molding machine, considering the silicone resin composition, viscosity, etc., the optimum molding machine It can be selected and molded into the optimal shape for various applications. Specific examples of the molding method include an injection molding method such as a liquid injection mold (LIM) molding method, a casting molding method, a compression molding method, a transfer molding method, and an extrusion molding method. Among these, it is particularly preferable to employ the LIM molding method from the viewpoint that the degree of freedom of the shape of the molded body is high and continuous molding is possible.

  The light reflector molded by the above method is heated at 100 to 200 ° C., more preferably 120 to 190 ° C., and still more preferably 140 to 180 ° C., for 1 second to 30 minutes, more preferably 3 seconds to A cured product having excellent heat resistance can be obtained by holding for about 10 minutes, more preferably for about 5 seconds to 2 minutes. It does not matter whether it is heated and cured in the mold or heated and cured after taking out from the mold, but it is cured in the mold in consideration of the dimensional stability and productivity of the molded product. Is preferred.

  In the present invention, in order to obtain a light reflector having a reflectance of 94% or more with respect to light having a wavelength of 350 to 450 nm at a thickness of 0.4 mm, the components (A) and (B) described above are in the preferred range. It can be obtained by selecting and combining.

(Light reflector thickness)
The thickness of the light reflector for the LED package substrate of the present invention may be selected and determined as appropriate, but is generally 5 to 1000 μm, preferably 300 to 700 μm. If this thickness is too thin, the performance as a reflector necessary for the high-intensity LED may not be exhibited. Conversely, if it is too thick, the handleability during processing may be reduced.

  The LED package substrate of the present invention includes the above-described light reflector and the LED package substrate light reflector using the light reflector. Since this substrate uses the light reflector of the present invention, it is an industrial high-intensity white LED package substrate that emits light in the ultraviolet region, and is excellent in heat resistance and UV resistance as well as light reflection characteristics. It becomes an effective LED package substrate.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

  The light reflector of the present invention was evaluated by the following method using the following raw materials.

[Thermosetting silicone resin (A)]
(A) -1: Addition-type thermosetting methyl silicone resin (hardness D40)
(A) -2: Addition type thermosetting methyl silicone resin (hardness D70)

[Alumina (B)]
The following alumina (B) -1 to (B) -8 were used. The sodium content of alumina (B) was determined by the following methods (i) to (Vii).

(I) About 0.2 g of each powdery alumina sample was weighed.
(Ii) The alumina was placed in a glass bottle, and 5 cc of 35% hydrochloric acid was added thereto.
(Iii) The mixture was allowed to stand at room temperature for 3 hours to obtain an alumina hydrochloric acid solution.
(IV) About 5 cc of pure water was placed in a 25 ml volumetric flask, the alumina hydrochloric acid solution obtained in (iii) was added, and then pure water was added so that the total amount was 25 ml.
(V) 25 ml of the aqueous alumina hydrochloric acid solution obtained in (iV) was filtered using a filter paper.
(Vi) After filtration, ICP measurement was performed to quantify the amount of sodium. Sodium was quantified using a wavelength of 589.592 nm and compared with a standard solution having a sodium content of 100 ppm.
(Vii) The sodium content was calculated from the ratio of sodium content and alumina content determined by ICP; (sodium content determined by ICP / alumina content).

(B) -1: Spherical alumina (Na content = 92.9 ppm, average particle size 0.6 μm)
(B) -2: Spherical alumina (Na content = 93.5 ppm, average particle size 0.3 μm)
(B) -3: Amorphous alumina (Na content = 161 ppm, average particle size 1.1 μm)
(B) -4: Spherical alumina (Na content = 79.6 ppm, average particle size 0.6 μm)
(B) -5: Amorphous alumina (Na content = 300 ppm, average particle size 0.5 μm)
(B) -6: Amorphous alumina (Na content = 343 ppm, average particle size 0.7 μm)
(B) -7: Amorphous alumina (Na content = 825 ppm, average particle size 0.7 μm)
(B) -8: Amorphous alumina (Na content = 225 ppm, average particle size 4.1 μm)

Example 1
Using a laboratory plastic mill 20C200 manufactured by Toyo Seiki Co., Ltd., (A) -1 and (B) -1 were kneaded at a mixing mass ratio of 45:55 at a temperature of about 20 ° C. Next, the obtained mixture was held for 3 minutes under the conditions of a temperature of 150 ° C. and a pressure of 20 MPa using a heated press IMC-18DA manufactured by Imoto Seisakusho Co., Ltd., to produce a molded body having a thickness of 0.4 mm. The obtained samples were evaluated for reflectivity, heat resistance, UV resistance and rigidity. The results are shown in Table 1.

(Example 2)
A light reflector sample was prepared and evaluated in the same manner as in Example 1 except that (A) -1 and (B) -2 were mixed at a mixing mass ratio of 45:55. The results are shown in Table 1.

(Example 3)
A light reflector sample was prepared and evaluated in the same manner as in Example 1 except that (A) -1 and (B) -3 were mixed at a mixing mass ratio of 45:55. The results are shown in Table 1.

Example 4
A light reflector sample was prepared and evaluated in the same manner as in Example 1 except that (A) -2 and (B) -3 were mixed at a mixing mass ratio of 45:55. The results are shown in Table 1.

(Comparative Example 1)
A light reflector sample was prepared and evaluated in the same manner as in Example 1 except that (A) -1 and (B) -4 were mixed at a mixing mass ratio of 45:55. The results are shown in Table 1.

(Comparative Example 2)
A light reflector sample was prepared and evaluated in the same manner as in Example 1 except that (A) -1 and (B) -5 were mixed at a mixing mass ratio of 45:55. The results are shown in Table 1.

(Comparative Example 3)
A light reflector sample was prepared and evaluated in the same manner as in Example 1 except that (A) -1 and (B) -6 were mixed at a mixing mass ratio of 45:55. The results are shown in Table 1.

(Comparative Example 4)
A light reflector sample was prepared and evaluated in the same manner as in Example 1 except that (A) -1 and (B) -7 were mixed at a mixing mass ratio of 45:55. The results are shown in Table 1.

(Comparative Example 5)
A light reflector sample was prepared and evaluated in the same manner as in Example 1 except that (A) -1 and (B) -8 were mixed at a mixing mass ratio of 45:55. The results are shown in Table 1.

(Comparative Example 6)
A light reflector sample was prepared and evaluated in the same manner as in Example 1 except that (A) -1 and (B) -3 were mixed at a mixing mass ratio of 80:20. The results are shown in Table 1.

(Comparative Example 7)
Example 1 except that (A) -1 and rutile-type titanium oxide (average particle size: 0.2 μm, hereinafter abbreviated as (N) -1) were mixed at a mixing mass ratio of 50:50. A light reflector sample was prepared and evaluated in the same manner. The results are shown in Table 1.

(Comparative Example 8)
Aromatic polyamide resin (containing titanium oxide and glass fiber, melting point: 305 ° C., hereinafter abbreviated as (M) -1) was heated using a heated press IMC-18DA manufactured by Imoto Seisakusho Co., Ltd. at a temperature of 350 ° C. and a pressure of 20 MPa. The molded body having a thickness of 0.4 mm was produced by maintaining the condition for 3 minutes. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

<Evaluation method>
(Reflectance)
A light reflector sample having a thickness of 0.4 mm is attached to a spectrophotometer U-4000 manufactured by Hitachi, Ltd., and the reflectance when the reflectance of the alumina white plate is 100% is set to 0. 0 over a wavelength range of 300 nm to 800 nm. The measurement was performed at intervals of 5 nm, and the average reflectance of wavelengths from 350 nm to 450 nm was 94% or more, which was regarded as acceptable.

(Long-term heat resistance)
Using a baking test apparatus DKS-5S manufactured by Daiei Scientific Instruments Co., Ltd., a light reflector sample having a thickness of 0.4 mm was left in the apparatus, and the reflectance after heating at 200 ° C. for 185 hours was measured. A sample having an average reflectance of 94% or more at a wavelength of 350 nm to 450 nm after the heating test was regarded as acceptable.

(Solder reflow heat resistance)
Using a baking test apparatus DKS-5S manufactured by Daiei Kagaku Seisakusho Co., Ltd., a light reflector sample having a thickness of 0.4 mm was left in the apparatus, and the reflectance after heating at 300 ° C. for 5 minutes was measured. A sample having an average reflectance of 94% or more at a wavelength of 350 nm to 450 nm after the heating test was regarded as acceptable.

(UV resistance)
Using a fade meter, Isuperki UV Tester SUV-W151 manufactured by Iwasaki Electric Co., Ltd., a light reflector sample having a thickness of 0.4 μm was left in the apparatus, and the reflectance after irradiation with ultraviolet rays for 50 hours was measured. A sample having an average reflectance of 94% or more at a wavelength of 350 nm to 450 nm after ultraviolet irradiation was regarded as acceptable.

(rigidity)
Using a dynamic viscoelasticity measuring machine (product name: viscoelastic spectrometer DVA-200, manufactured by IT Measurement Co., Ltd.), with a vibration frequency of 1 Hz, a temperature rising rate of 3 ° C./min, and a strain of 0.1%, The storage elastic modulus (E ′) was measured from −100 ° C. to 200 ° C., and the storage elastic modulus (E ′) at 20 ° C. was read from the obtained data. A storage elastic modulus (E ′) at 20 ° C. of 1 MPa or more and 1000 MPa or less was accepted.

  The light reflector of the present invention uses specific alumina and has an average reflectance of 94% or more for light with a wavelength of 350 nm to 450 nm at a thickness of 0.4 mm, which is excellent in light reflectance in the ultraviolet region, as well as heat treatment and UV. It can be seen that the reduction is suppressed even after irradiation.

  Furthermore, it turns out that the light reflector of this invention also has sufficient intensity | strength as a reflector. Moreover, in the comparative example (comparative example 8) using the conventional material, the reflectance fall in an ultraviolet region, and the reflectance fall by discoloration etc. are suppressed under high temperature thermal environment and UV irradiation. I understand.

Claims (11)

  A light reflector obtained by molding a resin composition obtained by blending alumina (B) with thermosetting silicone resin (A), wherein the sodium content of alumina (B) is 80 ppm or more and less than 300 ppm, A light reflector having an average reflectance of 94% or more with respect to light having a wavelength of 350 nm to 450 nm at a thickness of 0.4 mm. The light reflector according to claim 1, wherein the thermosetting silicone resin has a methyl group bonded to a silicon atom. The light reflector according to claim 1 or 2, wherein the average particle diameter of the alumina (B) is 0.1 µm or more and 1.5 µm or less. The ratio of alumina (B) to the total of thermosetting silicone resin (A) and alumina (B) is 30% by mass or more and 70% by mass or less. Light reflector. The light reflector according to any one of claims 1 to 4, wherein the alumina (B) is substantially spherical. The light reflector according to any one of claims 1 to 5, wherein an average reflectance with respect to light having a wavelength of 350 nm to 450 nm at a thickness of 0.4 mm after heat treatment at 200 ° C for 185 hours is 94% or more. . The light reflector according to any one of claims 1 to 5, wherein an average reflectance with respect to light having a wavelength of 350 nm to 450 nm at a thickness of 0.4 mm after heat treatment at 300 ° C for 5 minutes is 94% or more. . The light reflector according to any one of claims 1 to 7, wherein an average reflectance with respect to light having a wavelength of 350 nm to 450 nm at a thickness of 0.4 mm after UV irradiation for 48 hours is 94% or more. 9. The light reflector according to claim 1, wherein a storage elastic modulus (E ′) at a vibration frequency of 10 Hz and a temperature of 20 ° C. in dynamic viscoelasticity measurement is 1 MPa or more and 1000 MPa or less. A light reflector for an LED package substrate, comprising the light reflector according to claim 1. An LED package substrate comprising the light reflector according to claim 1.