KR100899830B1 - Resin-encapsulated light emitting diode and method for encapsulating light emitting diode - Google Patents

Abstract

The present invention provides a light emitting diode device in which the light emitting diode element is encapsulated with a material which is less sensitive to damage due to a sudden temperature change. The light emitting diode device is coated with addition-curable soft silicon and further encapsulated with dendritic addition-curable silicon. Soft silicones exhibit a curing hardness of 5-75 as measured by a Type E Durometer, (A) at least 1.8 alkenyl groups per molecule, organopolysiloxanes bonded to silicon atoms, (B) at least 4 per molecule Two hydrogen atoms are organohydrogenpolysiloxane (organohydrogenpolysiloxane) bonded to the silicon atom and (C) is characterized in that the curing product comprising a hydrosilylation catalyst.

Resin, Bag, Light Emitting Diode, Curing, Silicone

Description

RESIN-ENCAPSULATED LIGHT EMITTING DIODE AND METHOD FOR ENCAPSULATING LIGHT EMITTING DIODE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode device comprising an encapsulated light emitting diode element (hereinafter referred to as an LED element), which is a light emitting diode chip, a lead frame and a coupling connecting the chip and the frame. It is made of a bonding wire. The invention also relates to a method of encapsulating an LED device with silicon. More specifically, the present invention relates to an LED device including a LED device that emits blue to ultraviolet light as well as a method of encapsulating such LED device with silicon.

In general, the LED device is encapsulated with a transparent resin to make a light emitting device. Epoxy resins have been widely used as transparent encapsulating resins because of their high transparency, sufficient strength and rigidity, but they are used as materials for encapsulating LED devices emitting blue to ultraviolet light, or resins containing phosphors. Silicone resins are attracting attention in white light-emitting devices that encapsulate LED elements emitting blue to ultraviolet light. Epoxy resins are not suitable for encapsulation of LED devices that emit blue to ultraviolet light with high brightness and shorter wavelengths because they lack the heat and light resistance required for use in such LEDs. In particular, when the epoxy resin encapsulating the LED chip is exposed to ultraviolet light emitted from the chip, the bonds in the organic polymer are broken, resulting in a decrease in optical or chemical properties of the resin. As a result, the epoxy resin gradually yellows from the adjacent area of the LED chip. This causes coloring of the light and consequently limits the lifetime of the LED device. Silicone resins, on the other hand, are considered as suitable materials for encapsulating LED devices emitting blue to ultraviolet light because they exhibit high transparency and are less affected by degradation by ultraviolet rays.

For example, JP-A-6-314816 discloses the use of a siloxane compound as a resin for encapsulating an LED element. Since this siloxane compound contains an alkoxyl group which can react with a hydroxyl group on a compound semiconductor, a silicone resin can be produced through an addition reaction. In this case, the compound used is a high molecular compound having an organosiloxane unit. While hard silicone resins can enhance light resistance, the large expansion coefficients of silicone resins or the large differences in the expansion of silicone resins and the expansion of metal parts of LED devices can cause large distortions in LED devices when the LED devices are exposed to rapid temperature changes. Can cause. Because high energy LED devices can be heated to high temperatures when current is applied, they are susceptible to rapid temperature changes during the device's on / off operation, so cracking or other damage caused by distortion due to repeated temperature changes Easy to wear

Elastomers or gel-like silicones are also used to encapsulate LED devices. For example, Japanese Laid-Open Patent Publication No. 2002-314142 discloses the use of liquid silicon in which phosphors are dispersed in a bag of an LED element. According to Japanese Laid-Open Patent Publication No. 2002-314142, the silicone which forms the gel during heat-curing is compared with the silicone rubber, and it is concluded that the silicone rubber is preferable to the silicone gel in terms of protection of the LED device. . Nevertheless, when the elastic silicone elastomer is used to encapsulate the LED device, there may be a problem that the bonding wire of the LED device is easily deformed by mechanical force from the outside and the LED wire is cut according to the degree of deformation. In addition, the mechanical strength of the elastic body itself is not necessarily large enough.

Rather than encapsulating an LED element with a single hard resin or a single soft material such as an elastomer, it is proposed to coat the LED element with a soft material first and then encapsulate with a hard resin to form a double layer structure. For example, Japanese Patent Laid-Open No. 54-019660 discloses using elastic silicone for the inner layer and epoxy resin for the outer layer. The inner silicone has a rubber elasticity that is almost equal to that of the elastomer. Japanese Laid-Open Patent Publication No. 2004-140220 discloses a technique of first coating an LED element with gel or elastic silicone and then sealing it with a hard silicone resin.

Light emitting diode devices having a double-layer structure solve some of the problems associated with light emitting diode devices encapsulated with either of the two materials, but the difference between the thermal expansion of the internal soft silicon and the thermal expansion of the metal part of the LED device is still large. Remains. In particular, the large linear expansion coefficient of the soft silicon used in the inner layer causes a significant difference in the thermal expansion rate between the lead frame and the resin, which causes distortion in the metal parts and adjacent silicon of the LED device when the LED device is exposed to rapid temperature changes. This is caused. This distortion can eventually cause peeling at the interface of the material as the LED device is repeatedly affected by rapid temperature changes.

As mentioned above, attempts to solve the problem of LED device encapsulation with a single silicon composition by employing a double layer encapsulation structure with a soft silicon inner layer and a hard silicon outer layer are not sufficient and are therefore optimal for use in inner layers. Silicone compositions were required. There is also a need for compositions of hard silicone outer layers that are optimally combined with soft silicone inner layers.

The object of the present invention arises when the LED device is exposed to rapid temperature changes while maintaining the transparency, light resistance and heat resistance of the silicon material, taking into account the above-mentioned problems associated with the conventional double layer structure, It is to provide a composition for LED device encapsulation significantly improved cracking caused by distortion. Still another object of the present invention is to provide a light emitting diode device sealed with the composition.

Studies to solve the above-mentioned problems have found that a combination of a specific composition's addition-curable soft silicone and a particular addition-curable silicone resin can provide a suitable encapsulation for an LED. LED devices manufactured using such encapsulation significantly reduce the cracking caused by rapid temperature changes and retain the inherent properties of the silicon material, including high light transmittance, high refractive index, high light resistance and high heat resistance. These silicon bags are also hard and less susceptible to breakage and do not shrink significantly during molding.

Accordingly, the present invention includes the following configurations:

A first aspect of the invention is a light emitting diode device wherein the light emitting diode device is coated with addition-curable soft silicone and further encapsulated with a resin-like addition-curable silicone resin, wherein the addition-curable soft silicone is a Type E Durometer. It is characterized by being the hardened | cured product of the composition measured by the cure hardness of 5-75 and containing the following components (A)-(C).

(A) organopolysiloxane with at least 1.8 alkenyl groups per molecule bonded to silicon atoms and having a viscosity of 10 mPa · s to 10,000 mPa · s measured at 25 ° C. and shearing rate 0.9 s ⁻¹ ),

(B) organohydrogenpolysiloxanes having at least four hydrogen atoms per molecule bonded to silicon atoms and having a viscosity of 10 mPa · s to 10,000 mPa · s measured at 25 ° C. and a shear rate of 0.9 s ⁻¹ (or Ganohydrogenpolysiloxane is provided in an amount such that for each alkenyl of component (A) there are 0.9 to 2 silicon atoms bonded to the hydrogen atom.); And

(C) catalytic amount of hydrosilylation catalyst to accelerate curing of the composition

According to a second aspect of the present invention, in the light emitting diode device according to the first aspect, the component (A) is an organopolysiloxane having an average of about 2 alkenyl groups bonded to a silicon atom per molecule, and the alkenyl group is formed of an organopolysiloxane molecule. It is a light emitting diode device located at the terminal.

A third aspect of the invention is a light emitting diode device according to the first and second aspects, wherein the addition-curable silicone resin is a cured product of a composition comprising the following (a) and (b).

(a) at least one organ comprising a hydrocarbon group having at least CC multiple bonds and at least one organopolysiloxane comprising a hydrogen atom or at least one organopolysiloxane comprising a hydrogen atom and at least one hydrocarbon group having at least CC multiple bonds One or more organopolysiloxanes represented by the following average compositional formula (I) comprising a mixture of organopolysiloxanes:

_{(R 3 SiO 1/2)} M · (R 2 SiO 2/2) D · (RSiO 3/2) T · (SiO 4/2) Q (I)

Where

Each R is the same or different and is selected from the group consisting of a substituted or unsubstituted hydrocarbon group, a substituted or unsubstituted hydrocarbon group including a C-C multiple bond, a hydroxyl group and a hydrogen atom;

M, D, T, and Q are each greater than or equal to 0 and less than 1, except that M + D + T + Q = 1 and Q + T> 0;

(b) an effective amount of hydrosilylation catalyst

It is the hardening product of the composition which consists of.

A fourth aspect of the invention is a method of encapsulating a light emitting diode element according to any one of the first to third aspects, comprising a component (A) to (C) and curing in a liquid composition of silicone to form soft silicone Immersing the light emitting diode device to apply the composition to the light emitting diode device; And then encapsulating the light emitting diode device by casting molding the silicone resin composition under a cured or uncured state of the liquid composition to form soft silicone after curing.

Component (A) of the present invention is the main component of the silicone composition which forms a soft inner layer after curing. Component (A) is an alkenyl containing organopolysiloxane having at least an average of 1.8 alkenyl groups per molecule bonded to silicon atoms. Other organic groups bonded to the silicon atom are substituted or unsubstituted C1 to C20 monovalent hydrocarbon groups each containing no carbon-carbon double bond or carbon-carbon triple bond. The organopolysiloxane has a viscosity of 10 mPa · s to 10,000 mPa · s measured at 25 ° C. and a shear rate of 0.9 s ⁻¹ .

Examples of alkenyl groups included in component (A) include C2 to C8 alkenyl groups such as vinyl, allyl, 1-butenyl and 1-hexenyl groups. Double vinyl and allyl groups are preferred, and vinyl groups are particularly preferred. Such alkenyl groups must react with component (B) (to be described later) to form a network structure and at least 1.8 alkenyl groups on each molecule of component (A), preferably on each molecule of component (A) 1.6-10 alkenyl groups may be present. Alkenyl groups may be bonded to silicon atoms located within or at the end of the molecular chain. In consideration of the curing rate and properties, the alkenyl-containing organopolysiloxane preferably contains an average of two alkenyl groups per molecule, and the alkenyl group is bonded only to silicon atoms located at the ends of the molecular chain.

Preferably, the organic group which is not an alkyl group bonded to the silicon atom in component (A) is a substituted or unsubstituted C1-C12 monovalent hydrocarbon group that does not contain a carbon-carbon double bond or a carbon-carbon triple bond, respectively. Specific examples thereof include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, neopentyl, hexyl, 2-ethylhexyl, heptyl, octyl, nonyl and dodecyl groups; Cycloalkyl groups such as cyclopentyl, cyclohexyl and cycloheptyl groups; Aryl groups such as phenyl, tolyl, xylyl, biphenyl and naphthyl groups; Aralkyl groups such as benzyl, phenylethyl, phenylpropyl and methylbenzyl; And some or all of the hydrogen atoms of the hydrocarbon group are halogen atom, cyano group or chloromethyl, 2-bromoethyl, 3,3,3-trifluoropropyl, 3-chloropropyl, chlorophenyl, dibromofetyl, And substituted hydrocarbons substituted with other substituents including tetrachlorophenyl, difluorophenyl, β-cyanoethyl, γ-cyanopropyl, and β-cyanopropyl groups. Particular preference is given to double methyl and phenyl groups. In general, the refractive index of silicon varies with the type of organic group bonded to the siloxane unit: Silicones having aromatic groups, such as phenyl groups bonded to the siloxane unit, tend to exhibit higher refractive index than those having a methyl group. For this reason, when the outer dendritic silicon layer for encapsulating the LED device of the present invention contains a considerable amount of aromatic groups, the ratio of the phenyl groups of the soft inner silicon layer is correspondingly increased so that the refractive index of the soft inner silicon layer is equal to that of the outer layer. It is desirable to have the same level.

The alkenyl-containing organopolysiloxanes of component (A) can be linear or branched molecules and can be provided as a mixture of such molecules. Branched polysiloxane units act as self-crosslinking and may be trifunctional siloxane (T-structure) or tetrafunctional siloxane (Q-structure) when the hardness of the cured internal silicone layer is given within the specified range according to the present invention. . The compositions of the present invention that cure to form soft silicone must have adequate fluidity to ensure feasibility in the coating step of the LED device. From this point of view, the viscosity of component (A) measured at 25 ° C. and shear rate 0.9 s ⁻¹ is preferably in the range of 10 mPa · s to 10,000 mPa · s, more preferably 100 mPa · s to 5,000 mPa · s. Range, still more preferably 200 mPa · s to 3,000 mPa · s. Such alkenyl-containing organopolysiloxanes can be prepared by techniques known to those skilled in the art.

Component (B) of the present invention acts as a crosslinking agent of component (A) and is an organohydrogen in which at least an average of four hydrogen atoms in a molecule are bonded to silicon atoms and from 3 to 30 hydrogen atoms in each molecule are bonded to silicon atoms Polysiloxanes. Organic groups other than hydrogen bonded to silicon atoms are substituted or unsubstituted C1 to C20 monovalent hydrocarbon groups that do not contain carbon-carbon double bonds or carbon-carbon triple bonds. The organopolysiloxane (B) has a viscosity of 10 mPa · s to 10,000 mPa · s measured at 25 ° C. and a shear rate of 0.9 s ⁻¹ .

The organic groups in component (B) other than hydrogen are the same as those of component (A) above except for alkenyl groups, and are preferably methyl or phenyl groups. In view of the refractive index, the component (B) preferably contains a phenyl group for the same reason that the methyl and phenyl groups are selected in the component (A).

Component (B) for acting as a crosslinking agent may be straight or branched chain molecules and may be provided as a mixture of such molecules. Such organohydrogenpolysiloxanes can be prepared by techniques known to those skilled in the art. Component (B) must provide adequate fluidity, such as when the viscosity of component (A) is defined as described above. From this point of view, the viscosity of component (B) measured at 25 ° C. and shear rate 0.9 s ⁻¹ is preferably in the range of 10 mPa · s to 10,000 mPa · s, more preferably 50 mPa · s to 5,000 mPa · s Range, still more preferably 100 mPa · s to 2,000 mPa · s.

Component (B) according to the present invention is such that component (A) is crosslinked to achieve the required hardness such that 0.9 to 2 hydrogen atoms bonded to the silicon atoms are present for each alkenyl group of component (A) Is added. Generally component (B) is added in an amount of 5 to 80 parts by weight based on 100 parts by weight of component (A).

Component (C) of the present invention is a catalyst comprising a metal and / or a metal compound which accelerates the addition reaction between the Si—H group and the carbon-carbon multiple bond of the organopolysiloxane and is mainly used for hydrosilylation. Examples of such metals include platinum, rhodium, palladium, ruthenium and iridium. If desired, this metal is fixed to the particulate carrier material (eg activated carbon, aluminum oxide and silicon oxide). Preferred hydrosilylation catalysts are platinum and platinum compounds. Examples of platinum compounds include halogenated platinum compounds (eg, PtCl ₄ , H ₂ PtCl ₄ · 6H ₂ O and Na ₂ PtCl ₄ · 4H ₂ O), platinum-olefin complexes, platinum-alcohol complexes, platinum-alcoholate complexes, platinum Ether complexes, platinum-aldehyde complexes, platinum-ketone complexes, platinum-vinyl siloxane complexes (e.g., platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complexes, bis- (γ- Picoline) -platinum dichloride, trimethylenedipyridine-platinum dichloride, dicyclopentadiene-platinum dichloride, cyclooctadiene-platinum dichloride and cyclopentadiene-platinum dichloride), bis (alkynyl) bis ( Triphenylphosphine) platinum complex and bis (alkynyl) (cyclooctadiene) platinum complex. Hydrosilylation catalysts can be used in the form of microcapsules. In microcapsules, one example of solid particulates that may include a catalyst and is insoluble in organopolysiloxane is a resin (eg, a polyester resin and a silicone resin). The hydrosilylation catalyst may be provided in the form of a clathrate compound, for example cyclodextrin. The hydrosilylation catalyst is added in catalytic amounts. For example, the platinum catalyst is preferably added in an amount in the range of 0.1 to 500 ppm, particularly preferably in an amount in the range of 1 to 200 ppm, as measured by the amount of platinum in the composition comprising components (A) and (B). do.

Compositions of the present invention comprising components (A)-(C) have a curing hardness in the range of 5-75, preferably 5-60, by a hardness test of type E Durometer on 10 mm-thick sample pieces according to JIS K6253. Curing hardness in the range must be indicated. Compositions with a curing hardness of less than 5 can be greatly deformed during the encapsulation step with the silicone resin, whereas compositions with a curing hardness of greater than 75 do not have sufficient capacity to absorb the stresses required for the soft layer. The desired hardness can be achieved not only by adjusting the amount and the degree of polymerization of the Si-H bonds of the component (B), but also by adjusting the alkenyl group and the branched structure forming the crosslinking degree of the polymerization of the component (A).

The light emitting diode device according to the present invention coats the LED device with the above-mentioned composition consisting of the components (A) to (C), and further encapsulates the LED device coated with the addition-curable silicone resin composition which is cured to form a dendritic material. Is prepared. Addition-curable silicone resin (a) the average formula _{(R 3 SiO 1/2)} M · (R 2 SiO 2/2) D · (RSiO 3/2) T · (SiO 4/2) Q ( wherein R Are each selected from the group consisting of an organic group, a hydroxyl group and a hydrogen atom; M, D, T and Q are each greater than or equal to 0 and less than 1; and Q + T> 0. Organopolysiloxane comprising a hydrocarbon group and / or a hydrogen atom having a multiple bond or a mixture thereof; And (b) an effective amount of a catalyst for the addition reaction. Component (a) has an average composition of the mixture within the T- unit (RSiO _3/2) and / or Q- units (RSiO _4/2) 3-dimensional network of highly branched structure, including conducting a cross-linking or other reaction of It is a polymer capable of forming a structure. Therefore, Q + T> 0 must be maintained in each average composition formula.

Organopolysiloxanes, also referred to as silicone resins, may be solid or liquid before curing. However, the liquid composition is easily molded and therefore more suitable for the encapsulation of LEDs, which is the object of the present invention. The organopolysiloxane provided as component (a) can be any organopolysiloxane prepared using techniques known to those skilled in the art: can be obtained by organosilanes or hydrolysis of organosiloxanes.

R of component (a) is each independently selected and may be the same or different. Component (a) may be the same as the structural unit _{(R 2 SiO 2/2)} D I R may be different from each other it includes a methyl, phenyl, and hydrogen atom at the same time, since it is defined by the average formula. Such structural units may be linked by other unit structures.

Examples of R include straight or branched chain C1-C20 alkyl or alkenyl groups and their halogenated forms; Hydrocarbon containing an acetylene group or an acetylene group; C5 to C25 cycloalkyl or cycloalkenyl groups and their halogenated forms; And aralkyl or aryl groups of C6 to C25 and their halogenated forms. In particular such hydrocarbons may be those given as examples of alkenyl groups or other organic groups in component (A) above. The term "R with a multiple bond" means a hydrocarbon group comprising a carbon-carbon double bond or a carbon-carbon triple bond, including alkenyl or acetylene groups. Vinyl groups are most preferred hydrocarbon groups with multiple bonds.

Alternatively R is a group consisting of hydrogen, hydroxyl, alkoxyl, acyloxy, ketiminoxy, alkenyloxy, acid anhydride, carbonyl, sugar, cyano, oxazoline and isocyanate groups and their hydrocarbon-substituted forms Can be selected from. Specific examples include methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, t-butoxy, hexyloxy, isohexyloxy, 2-hexyloxy, octyloxy, isooctyloxy, 2 Octyloxy, acetoxy, dimethylketoxime, methylethylketoxime, glycidyl, ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol Cooxy, methoxyethylene glycol, ethoxyethylene glycol, methoxydiethylene glycol, ethoxydiethylene glycol, methoxypropylene glycol, methoxydipropylene glycol, and ethoxydipropylene glycol The season can be mentioned. Of these, methyl, ethyl, propyl, phenyl and vinyl groups and hydrogen atoms are particularly preferred.

Component (a) may be of any combination. For example, component (a) comprises (i) an organopolysiloxane comprising a hydrocarbon group bonded to a silicon atom having a multiple bond and a hydrogen atom bonded to a silicon atom in one molecule, or a mixture thereof, or (ii) one An organopolysiloxane comprising a hydrocarbon group bonded to a silicon atom having multiple bonds in a molecule, but not including a hydrogen atom bonded to a silicon atom, and a hydrocarbon comprising a hydrogen atom bonded to a silicon atom in one molecule, but having a multiple bond A mixture of organopolysiloxanes containing no groups or (iii) organopolysiloxanes of (iii) comprising hydrocarbon groups bonded to silicon atoms having multiple bonds and hydrogen atoms bonded to silicon atoms in one molecule Any hydrogen bonded to a silicon atom, including a hydrocarbon group bonded to a silicon atom having multiple bonds to a molecule of Organopolysiloxanes not containing atoms and / or organopolysiloxanes containing hydrogen atoms bonded to silicon atoms but not including any hydrocarbon groups having multiple bonds.

In summary, when component (a) is provided as a mixture, such a mixture comprises hydrocarbon groups and Si—H groups bonded to silicon atoms having multiple bonds and in amounts such that the mixture forms a dendritic material after curing, and / or Or Q-units.

Hydrocarbon groups bonded to silicon atoms and hydrocarbon groups bonded to silicon atoms having multiple bonds which are essential elements of the polysiloxane for acting as component (a) are present in two or one unit selected from the general formula of component (a) It is preferable. According to the present invention bonded hydrogen atoms in a hydrocarbon group and silicon having a multiple bond bonded to the silicon with a hydrocarbon group is most preferably present in the (R ₂ SiO _2/2) structural units.

The organopolysiloxane for acting as component (a) of the present invention preferably comprises an aromatic group to ensure the heat resistance, light resistance and refractive index required for the encapsulating material of the LED element as R of the average composition formula. Such aromatic groups include aralkyl or aryl, but phenyl is most preferred. The aromatic group preferably accounts for 5 to 90 mol%, more preferably 10 to 60 mol% with respect to the total R groups in the whole unit. If the amount of aromatic groups is too small, the heat resistance, light resistance and refractive index may not be improved as desired, while if the amount of aromatic groups is too large, the product will not be cost effective. The aromatic group (SiO _4/2) can also be introduced to anything other than the unit, but (R ₂ SiO _2/2) and into the (RSiO _3/2) preferably is introduced into the unit, and (RSiO _3/2) units Introduction is most preferred.

In addition, the silicon atom directly bonded to the hydrogen atom in the component (a) of the present invention is preferably 1 to 4 mol%, more preferably 3 to 30 mol% of the total silicon atoms, most preferably 5 to 20 Constitute mole%. If this amount is too high, the product tends to be brittle despite increasing hardness, whereas if the amount is too small, the hardness does not increase sufficiently. In addition, when component (a) includes both a hydrocarbon-bonded silicon-bonded hydrocarbon and a hydrogen-bonded hydrogen atom, the silicon atom directly bonded to the hydrogen atom is preferably 1 to 40 mol%, more preferably Is 3 to 30 mol%. More than 40 mol% tends to be more brittle despite increasing hardness of the cured product, while less than 1 mol% does not yield a cured product having a satisfactory hardness.

M, D, T and Q are numbers representing the relative proportions of each unit and range from 0 (inclusive) to 1 (not included). The preferred range is 0 to 0.6 for M, 0.1 to 0.8 for D, 0.1 to 0.7 for T and 0 to 0.3 for Q. Ideally, M is 0.1 to 0.4, D is 0.1 to 0.6, and T is 0.3. -0.6 and Q are zero. The value of T + Q is preferably in the range of 0.3 to 0.9.

A value of (2D + 3T + 4Q) / (D + T + Q) (where 2D is 2 times D, 3T is 3 times T, 4Q is 4 times Q) is a branching degree, and is preferable. Preferably 3.0> (2D + 3T + 4Q) / (D + T + Q)> 2.0, more preferably 2.8> (2D + 3T + 4Q) / (D + T + Q)> 2.2.

The same hydrosilylation catalyst as the component (B) of the dendritic addition-curable silicone of the present invention can be used. The catalyst may be one commonly used to accelerate the addition reaction between the Si—H groups of the organopolysiloxane and the multiple bonds of the Si-bonded hydrocarbons. The catalyst for the addition reaction is used in an effective amount (or catalyst amount) and is generally in the range of 1 to 1000 ppm with respect to component (a), preferably in the range of 2 to 500 ppm.

The encapsulation composition of the invention comprising components (a) and (b) must be converted to a dendritic state after crosslinking by addition reaction. As used herein, "resin phase" means that the composition has a hardness in the range of 30 to 90, preferably in the range of 40 to 90, by a test of Durometer D hardness using a 6 mm-thick sample piece in accordance with JIS K6253. It means having a hardness. Cured products having a hardness within a certain range can be obtained by adjusting the (2D + 3T + 4Q) / (D + T + Q) values to a predetermined range.

Examples of LED devices that can be used in the present invention include recently developed high brightness, short wavelength LED devices as well as GaP, GaAs and GaN based red, green and yellow LED devices.

Although the compositions of the present invention can be used to encapsulate conventional LED devices, they are used to encapsulate recently developed high brightness, short wavelength LED devices, including high brightness blue LED devices, white LED devices and LED devices in the blue to near ultraviolet spectrum. Is the most effective. The peak wavelength of the light emitted for this LED device is in the range of 490-530 nm. Encapsulation materials used in this kind of LED devices require not only good light resistance for the blue to ultraviolet wavelengths, but also good light resistance and heat resistance when exposed to higher brightness, higher energy light emitted from the LED device. The encapsulation composition of the present invention provides better light resistance and heat resistance than that provided by conventional epoxy-based encapsulants, which means that the lifetime of light emitting diode devices can be significantly increased. Specific examples of such high-brightness blue, white, blue to near ultraviolet spectrum LED devices include AlGaInN yellow LED devices, InGaN blue and green LED devices, and white light emitting diode devices combining InGaN and fluorescent materials. .

Specific examples of encapsulated light emitting diodes include lamp-type devices, large scale package devices, and surface mounted devices. These various forms of LED devices are disclosed, for example, in the "Flat Panel Display Dictionary" (pp. 897-906) published by Kogyo Chosakai Publishing Co., Ltd. on December 25, 2001.

The composition of the present invention consisting of components (A) to (C) and cured to form soft silicone can be applied to the LED device using any suitable technique. For example, the entire LED device can be immersed in the liquid composition, or droplets of the liquid composition can be dropped onto the LED device. This technique is particularly suitable because the LED element can be coated relatively uniformly by the immersion technique. The composition may be applied at any suitable thickness, but is generally applied at a thickness of about 0.01-2 mm. After applying the liquid composition, the composition may or may not be cured prior to the encapsulation step. However, it is desirable to cure the composition prior to the encapsulation step. The composition can be easily cured by passing the coated LED device through a furnace adjusted to a temperature suitable for curing. The curing step is generally carried out for 1 to 120 minutes in the temperature range of 50 to 180 ℃.

After coating with silicone to cure and soften, the LED device is also encapsulated with a cured, dendritic composition consisting of components (a) and (b). Encapsulation can be carried out using any suitable technique. For example, encapsulation may be performed by pouring the silicone composition of the present invention into a resin mold, immersing the LED element in the composition, and then heat curing the composition. Encapsulation may also be carried out by transfer molding. One advantage of the encapsulation using the silicone resin of the present invention is that not only resin molds but also metal molds which were not possible with conventional epoxy-based encapsulating materials can be used.

Various additives can be added to the composition of this invention within the range which does not lose the effect. Examples of possible additives include white light emission, such as addition reaction modifiers that enhance curability and pot life, reactive or non-reactive straight or cyclic low molecular organopolysiloxanes for controlling the hardness and viscosity of the composition. Fluorescent fillers such as YAG, inorganic fillers or pigments such as particulate silica, titanium oxide and the like, organic fillers, flame retardants, heat resistant agents, antioxidants and the like.

The light emitting diode device of the invention, in particular the light emitting diode device of the invention comprising an LED element emitting blue to ultraviolet light, is less susceptible to cracking of the bag when exposed to rapid temperature changes. Encapsulation of the LED device is advantageous because the strength and hardness of the silicon-based material is in harmony while maintaining transparency, light resistance and heat resistance.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited to the following Examples. In the embodiment of the present invention, the following silicone composition was used:

(A-1) Dimethylpolysiloxane blocked at both ends with dimethylvinylsilyl and having a viscosity of 900 mPa · s at 25 ° C

(B-1) Methylhydrogenpolysiloxane blocked at both ends with a trimethylsilyl group and having a viscosity of 300 mPa · s at 25 ° C. and containing 14 methylhydrogensiloxane units in the main chain

(C, b) siloxane-platinum complexes containing vinyl derived from chloroplatinic acid (hydroxylation catalysts)

_{(a) (Me 3 SiO 1} /2) 0.17 · (MeHSiO 2/2) 0.20 · (MeViSiO 2/2) 0.25 · (PhSiO 3/2) has an average composition of _0.38 at 25 ℃ having a 900 mPa · s viscosity Organopolysiloxanes (where Me, Vi and Ph represent methyl, vinyl and phenyl groups, respectively)

In each example a 10 mm- or 6 mm-thick cured product sheet was used to measure hardness using a Durometer. Thermal shock tests were performed to evaluate the crack resistance of the sheet. Using a small heat-shock tester (TSE-11-A) manufactured by ESPEC Co., Ltd., the circulation test was carried out under the condition of maintaining the temperature at -40 ° C and 110 ° C for 30 minutes. The temperature of the tester was changed within 3 minutes from -40 ° C to 110 ° C and from 110 ° C to -40 ° C.

(Example 1)

90 parts by weight of dimethylpolysiloxane (A-1), 10 parts by weight of methylhydrogenpolysiloxane (B-1) and 0.05 parts by weight of the platinum complex (C) were weighed and mixed until uniform. An aspirator was used to remove air from the mixture under reduced pressure. This addition-curable silicone mixture was determined to have a viscosity of 700 mPa · s. The silver-plated metal lead frame (for 5 mm lamp type) was then immersed in the mixture for 2 minutes and withdrawn from the mixture and held in air for 3 minutes to remove the extra addition-curable silicone mixture. The lead frame was then heated at 100 ° C. for 15 minutes to cure the silicone mixture. A microscopic observation of a lead frame coated with soft addition-curable silicone had a thickness of about 50-200 microns. The 10 mm-thick sheet obtained by heating the addition-curable mixture at 100 ° C. for 15 minutes exhibited a hardness of 50 when measured with a type-E Durometer.

Then, 100 parts by weight of the organopolysiloxane of (a) and 0.02 parts by weight of the platinum complex of (b) were mixed until uniform. Air was removed from this mixture under reduced pressure using an inhaler to obtain an addition-curable silicone resin mixture having a viscosity of 800 mPa · s. The obtained addition-curable silicone resin mixture was poured into a resin casting case (5 mm lamp-type) and a lead frame coated with a soft addition-curable silicone obtained in advance was inserted into the casting case. The resin casting case was then heated at 150 ° C. for 3 hours for curing. The 6 mm-thick sheet obtained by heating the addition-curable silicone resin at 150 ° C. for 3 hours was transparent and exhibited a hardness of 60 when measured with a type-D Durometer.

The light emitting diode device having the obtained double layer structure encapsulation was tested in a heat-impact tester. No cracks were observed in the LED device after 300 cycles.

(Comparative Example 1)

As in Example 1, 100 parts by weight of the organopolysiloxane of (a) and 0.02 part by weight of the hydrosilylation catalyst of (b) were weighed and mixed until uniform. After removing the air under reduced pressure the viscosity of this mixture was 800 mPa · s. The obtained silicone resin mixture was poured into a resin casting case (5 mm lamp-type) and a silver-plated metal lead frame not coated with soft silicone was inserted into the casting case. The resin casting case was then heated at 150 ° C. for 3 hours for curing. The light emitting diode device having the obtained single layer encapsulation was tested in a heat-impact tester. Cracks formed in all samples after 10 cycles.

Effects of the Invention

The LED device encapsulated in accordance with the present invention significantly reduces the cracking caused by sudden temperature changes and retains the inherent properties of the silicon material, including high light transmittance, high refractive index, high light resistance and high heat resistance, which silicon encapsulation also It is hard and less susceptible to breakage and does not shrink significantly during molding.

Claims (4)

A light emitting diode device in which a light emitting diode device is coated with addition-curable soft silicone and further encapsulated with a resin-like addition-curable silicone resin, wherein the addition-curable soft silicone has a curing hardness of 5 with a Type E Durometer. It is -75 and it is a hardening product of the composition containing the following components (A)-(C): (A) organopolysiloxane with at least 1.8 alkenyl groups per molecule bonded to silicon atoms and having a viscosity of 10 mPa · s to 10,000 mPa · s measured at 25 ° C. and shearing rate 0.9 s ⁻¹ ); (B) organohydrogenpolysiloxanes having at least four hydrogen atoms per molecule bonded to silicon atoms and having a viscosity of 10 mPa · s to 10,000 mPa · s measured at 25 ° C. and a shear rate of 0.9 s ⁻¹ , wherein Organohydrogenpolysiloxane is provided in an amount such that for each alkenyl of component (A) there are 0.9 to 2 silicon atoms bonded to a hydrogen atom; And (C) hydrosilylation catalysts. The light emitting diode device of claim 1, wherein component (A) is an organopolysiloxane in which an average of two alkenyl groups per molecule are bonded to a silicon atom, and the alkenyl group is located at the end of the organopolysiloxane molecule. The light emitting diode device according to claim 1 or 2, wherein the addition-curable silicone resin is a cured product of a composition comprising the following (a) and (b): (a) a mixture of one or more organopolysiloxanes represented by the following average compositional formula (I), comprising at least one organopolysiloxane comprising a hydrogen atom and at least one organopolysiloxane comprising a hydrocarbon group having at least CC multiple bonds; Or an organopolysiloxane comprising at least one organopolysiloxane comprising a hydrogen group and a hydrocarbon group having at least CC multiple bonds: (R ₃ SiO _1/2 ) _M (R ₂ SiO _2/2 ) _D (RSiO _3/2 ) _T (SiO _4/2 ) _Q (I) [Wherein, Each R is the same or different and is selected from the group consisting of a substituted or unsubstituted hydrocarbon group, a substituted or unsubstituted hydrocarbon group including a C-C multiple bond, a hydroxyl group and a hydrogen atom; M, D, T, Q are each greater than or equal to 0 and less than 1, provided that M + D + T + Q = 1 and Q + T> 0; (b) hydrosilylation catalysts. A method of encapsulating a light emitting diode device coated with an addition-curable soft silicone and further encapsulated with a resin-like addition-curable silicone resin, The addition-curable soft silicone is characterized in that the curing hardness of the composition comprising the following components (A) to (C) having a curing hardness of 5 to 75, measured by Type E Durometer, (A) organopolysiloxane with at least 1.8 alkenyl groups per molecule bonded to silicon atoms and having a viscosity of 10 mPa · s to 10,000 mPa · s measured at 25 ° C. and shearing rate 0.9 s ⁻¹ ); (B) organohydrogenpolysiloxanes having at least four hydrogen atoms per molecule bonded to silicon atoms and having a viscosity of 10 mPa · s to 10,000 mPa · s measured at 25 ° C. and a shear rate of 0.9 s ⁻¹ , wherein Organohydrogenpolysiloxane is provided in an amount such that for each alkenyl of component (A) there are 0.9 to 2 silicon atoms bonded to a hydrogen atom; And (C) hydrosilylation catalyst Immersing the light emitting diode device in a soft silicone liquid composition comprising components (A) to (C) to apply the composition to the light emitting diode device; And Encapsulating the light emitting diode device by subsequently cast molding the silicone resin composition under a cured or uncured state of the liquid composition which forms the soft silicone after curing. Method for encapsulating a light emitting diode device comprising a.