(19) TZZ_98Z__T (11) EP 1 980 591 B1 (12) EUROPEAN PATENT SPECIFICATION (45) Date of publication and mention (51) Int Cl.: of the grant of the patent: C08L 83/04 (2006.01) H01L 31/00 (2006.01) 31.10.2012 Bulletin 2012/44 H01L 33/00 (2010.01) C08K 3/08 (2006.01) (21) Application number: 08251377.1 (22) Date of filing: 09.04.2008 (54) Sheet prepared by molding a phosphor-containing adhesive silicone composition, method of producing a light emitting device using the sheet and light emitting device obtainable by the method. Schicht hergestelltdurch Formen einerphosphorhaltigen Silikonklebstoffzusammensetzung, Verfahren zur Herstellung einer lichtemittierenden Vorrichtung unter Verwendung der Schicht und lichtemittierende Vorrichtung herstellbar mit dem Verfahren. Feuille formée d’une composition de silicone adhésive contenant du phosphore, procédé pour la fabrication d’un dispositif luminescent utilisant la feuille et dispositiv lunminescant obtenue grâce à ce procédé. (84) Designated Contracting States: • Shiobara, Toshio DE Tokyo (JP) (30) Priority: 10.04.2007 JP 2007103236 (74) Representative: Hallybone, Huw George et al 06.03.2008 JP 2008056897 Carpmaels & Ransford One Southampton Row (43) Date of publication of application: London 15.10.2008 Bulletin 2008/42 WC1B 5HA (GB) (73) Proprietor: Shin-Etsu Chemical Co., Ltd. (56) References cited: Tokyo (JP) EP-A- 1 780 235 EP-A- 1 780 242 EP-A- 1 873 211 US-A1- 2005 280 017 (72) Inventors: • Kashiwagi, Tsutomu Annaka-shi Gunma-ken (JP) Note: Within nine months of the publication of the mention of the grant of the European patent in the European Patent Bulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with the Implementing Regulations. Notice of opposition shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). EP 1 980 591 B1 Printed by Jouve, 75001 PARIS (FR) EP 1 980 591 B1 Description BACKGROUND OF THE INVENTION 5 1. Field of the Invention [0001] Disclosed herein is an addition curable phosphor- containing adhesive silicone composition, which in an uncured state (namely, prior to heat treatment) at room temperature is either a solid or a semisolid, and which by positioning on, and bonding to, the surface of an LED chip, is capable of converting the blue light or ultraviolet light of the LED. The 10 present invention relates to a sheet formed of the composition, a sheet-like cured product obtained by heat-curing the sheet, a method of producing a light emitting device that uses the silicone composition sheet, and a light emitting device. 2. Description of the Prior Art 15 [0002] In the field of light emitting diodes (LED), the use of phosphors for wavelength conversion is well known (see patent reference 1). Because silicone resins exhibit excellent light resistance, they are attracting considerable attention as coating materials for encapsulating and protecting LED chips (see patent reference 2). [0003] In white LEDs, a method is generally used in which a silicone resin or epoxy resin with a phosphor dispersed therein is used to coat the LED chip, thereby dispersing the phosphor in a position close to the chip and enabling the 20 blue light from the LED to be converted to a pseudo white light, However, if the dispersion of the phosphor within the resin lacks uniformity or is biased, then color shift becomes more likely, meaning that the phosphor must be dispersed uniformly within the coating resin layer in order to generate a uniform white light. In order to achieve such uniform dispersion, screen printing methods and phosphor precipitation methods are under investigation, but these methods suffer from other problems, including a more complex production process and inadequate stability. Accordingly, a simple 25 technique that enables a phosphor to be dispersed uniformly across a chip surface has been keenly sought. [0004] Furthermore, in LEDs and the like, the resin layer used to coat the LED chip requires high levels of heat resistance and ultraviolet light resistance. Moreover, a resin layer that can be produced using conventional production apparatus would be ideal. 30 [Patent Reference 1] US 2004/0094757 A1 [Patent Reference 2] US 2004/0214966 A1 SUMMARY OF THE INVENTION 35 [0005] Disclosed hereinis the provisionof an addition curableadhesive silicone composition, which contains a phosphor dispersed uniformly therein, the dispersive state of which remains stable over time, and which in an uncured state at room temperature is either a solid or a semisolid, and is therefore easy to handle, and an object of the present invention is to provide an adhesive silicone composition sheet that is formed of the composition and is able to formed easily on the surface of an LED chip using a conventional assembly apparatus. Furthermore, another object of the present invention 40 is to provide a method of producing an LED light emitting device, which uses the above sheet to coat the surface of an LED chip with a phosphor-containing cured silicone resin layer. [0006] Disclosed herein is the provision of an addition curable adhesive silicone resin composition that is a solid or semisolid at room temperature, comprising: 45 1 2 3 4 (A) an organopolysiloxane having a resin structure composed of R SiO1.5 units, R 2SiO units and R aR bSiO(4-a-b)/2 units (wherein, R1, R2 and R3 each represent, independently, a hydroxyl group, methyl group, ethyl group, propyl group, cyclohexyl group or phenyl group, each R 4 represents, independently, a vinyl group or allyl group, a represents 2 0, 1 or 2, and b represents 1 or 2, provided that a+b is 2 or 3), in which at least a portion of the R2SiO units are connected in a continuous repeating sequence, and the number of units in the repeating sequence is within a range 50 from 5 to 50, 1 2 (B) an organohydrogenpolysiloxane having a resin structure composed ofSiO R 1.5 units, R2SiO units and 3 1 2 3 R cHdSiO(4-c-d)/2 units (wherein, R , R and R are as defined above, c represents 0, 1 or 2, and d represents 1 or 2 2, provided that c+d is 2 or 3), in which at least a portion of the R 2SiO units are connected in a continuous repeating sequence, and the number of units in the repeating sequence is within a range from 5 to 50, the organohydrogen- 55 polysiloxane provided in sufficient quantity that the molar ratio of hydrogen atoms bonded to silicon atoms within the component (B) relative to a combined total of vinyl groups and allyl groups within the component (A) is within a range from 0.1 to 4.0, (C) an effective curing quantity of a platinum group metal- based catalyst, and 2 EP 1 980 591 B1 (D) a phosphor. [0007] In the above adhesive silicone composition, compositions in which either one of, or both, the component (A) and the component (B) contain a silanol group exhibit more favorable adhesion for the composition, and are consequently 5 preferred. [0008] A first aspect of the present invention provides an adhesive silicone composition sheet prepared by molding the above addition curable silicone composition into a sheet- like form. [0009] A sheet-like cured product obtained by curing the silicone composition is a hard resin, and yet still exhibits excellent flexibility and minimal surface tack, and is also able to be readily molded with conventional molding apparatus. 10 [0010] The layer-like cured product exhibits significant advantages including a high degree of transparency, uniform dispersion of the phosphor within the cured product, and a high level of stability of the dispersive state of the phosphor, and is therefore useful as an encapsulating body or coating formed on the surface of an LED chip. [0011] A second aspect of the present invention provides a method of producing a light emitting device having a coated LED chip, the method comprising: positioning the above adhesive s ilicone composition sheet on the surface of an LED 15 chip, and heat-curing the composition sheet, thereby coating the surface of the LED chip with a phosphor-containing cured silicone resin layer. [0012] In this aspect of the invention, the composition sheet is positioned on the surface of the LED chip, so that at least the surface of the LED chip is covered with a cured silicone resin layer. The composition sheet may also be positioned so as to cover not only the surface of the semiconductor chip, but the entire surface of the LED element 20 device containing the semiconductor chip, so that the entire device is covered with the cured resin layer. [0013] A third aspect of the present invention provides a light emitting device having a coated LED chip that is obtained using the above production method. [0014] An adhesive silicone composition disclosed herein and a composition sheet formed therefrom are solid or semisolid in an uncured state at room temperature, and are therefore easy to handle and exhibit favorable workability. 25 As a result, the composition sheet can be easily positioned on, and bonded to, the surface of an LED chip. Furthermore, because the composition or composition sheet is a solid or semisolid in an uncured state, the phosphor contained therein does not suffer from separation or precipitation during storage of the composition or composition sheet. Moreover, the silicone composition sheet can be easily positioned on, and bonded to, the surface of an LED chip using a typical mounting device such as a die- bond mounter. By subsequently curing the bonded composition sheet, a cured resin layer 30 with the phosphor dispersed uniformly therein can be formed efficiently and stably at a uniform layer thickness.