JP2014086520A - Light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device in which anti-settling, prevention of cracking, and prevention of peeling of phosphor in a sealing resin are achieved simultaneously.SOLUTION: A light-emitting device 10 is configured by mounting a light-emitting element 14 on the bottom of a recess 12A in a lead frame 12, and then sealing the light-emitting element 14 with a sealing resin 16. The sealing resin 16 contains a phosphor emitting secondary light by absorbing primary light irradiated from the light-emitting element 14, silica of micro-order and silica of nano-order. The content of silica of micro-order is set so that the weight ratio of the sealing resin 16 to a resin base compound is in the range of 10-15%.

Description

  The present invention relates to a light emitting device in which a phosphor is dispersed in a resin for sealing an LED chip.

  In recent years, light emitting devices using LEDs (Light Emitting Diodes) have been used as light sources for lighting devices and display devices. In such a light emitting device, a structure in which an LED chip is mounted on a lead frame and sealed with a transparent resin (sealing resin) is often used.

  In addition, such a light emitting device is also in great demand as a white light source. Such a white light source is usually manufactured by using a blue LED with high emission luminance and dispersing phosphors (red and green phosphors or yellow phosphors) in a sealing resin. The phosphor absorbs primary light (blue light) emitted from the LED and converts it into secondary light (red light and green light or yellow light). Thereby, the said light-emitting device can obtain white light as mixed light of primary light and secondary light.

  In the light emitting device having the above configuration, it is important to uniformly disperse the phosphor in the sealing resin in order to obtain uniform color development. For this reason, Patent Documents 1 and 2 describe that a diffusing agent is contained in the sealing resin to prevent the phosphor from settling. Patent Documents 1 and 2 describe using nano-order silica or the like as a diffusing agent.

  Furthermore, in the light emitting device having the above configuration, it is also important to prevent the occurrence of cracks in the cured sealing resin. For this reason, Patent Document 1 describes that a filler is included in the sealing resin to improve the thermal shock resistance. Patent Document 1 describes that micro-order silica or the like is used as a filler.

Japanese Patent No. 3428597 JP 2009-120437 A

  However, the sealing resin for the light emitting device is required to have various performances in addition to preventing the phosphor from settling and preventing the occurrence of cracks. For this reason, in sealing resin, there exists room for improving the performance more. The inventor of the present application has found that as one of further problems, if the amount of filler added is excessively increased in order to prevent cracking, the tackiness of the sealing resin is lowered and peeling occurs.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a light-emitting device that simultaneously realizes prevention of sedimentation of phosphors, prevention of crack generation, and prevention of peeling in a sealing resin.

  In order to solve the above problems, a light-emitting device of the present invention includes a lead frame, a light-emitting element mounted on the lead frame, and a sealing resin that seals the light-emitting element. The resin contains a phosphor that absorbs primary light emitted by the light emitting element and emits secondary light, micro-order silica, and nano-order silica, and contains the micro-order silica. The amount is characterized in that the weight ratio of the sealing resin to the resin main ingredient is in the range of 10 to 15%.

  In the light emitting device, the content of the nano-order silica is preferably such that the weight ratio of the sealing resin to the resin main component is in the range of 1.0 to 2.0%.

  In the light emitting device, the center particle diameter of the micro-order silica is preferably in the range of 0.1 to 12 μm.

  In the light emitting device, the center particle diameter of the micro-order silica is preferably in the range of 0.6 to 1.6 μm.

  In the light emitting device, the center particle diameter of the nano-order silica is preferably in the range of 5 to 15 nm.

  The light-emitting device of the present invention prevents cracking and phosphor settling simultaneously by containing two types of silica (micro-order silica and nano-order silica) having different particle sizes in the sealing resin. In addition, it is possible to prevent the sealing resin from peeling off by adjusting the content of silica.

It is sectional drawing which shows the structural example of the light-emitting device to which this invention is applied. It is sectional drawing which shows the light-emitting device which sedimentation of fluorescent substance produced using only the silica of a micro order as an additive to sealing resin. It is sectional drawing which shows the light-emitting device in which only the nano-order silica was used as an additive to sealing resin, and the sealing resin cracked. It is sectional drawing which shows the light-emitting device from which peeling generate | occur | produced in sealing resin.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a configuration example of a light emitting device 10 to which the present invention is applied. The light emitting device 10 generally includes a lead frame 12, a light emitting element 14, and a sealing resin 16. The lead frame 12 has a recess 12A whose upper surface is opened, and the light emitting element 14 is mounted on the bottom surface of the recess 12A. The light emitting element 14 is die-bonded or wire-bonded to connection wiring formed on the bottom surface of the recess 12A of the lead frame 12 (FIG. 1 shows an example of wire bonding). The sealing resin 16 fills the inside of the recess 12A of the lead frame 12 after the light emitting element 14 is mounted, and seals the light emitting element 14 and the connection wiring.

  In the light emitting device 10, as a configuration for irradiating white light, the light emitting element 14 is a blue LED, and the sealing resin 16 contains a phosphor 18. For example, the sealing resin 16 is obtained by dispersing a green phosphor 18G and a red phosphor 18R in a silicone resin that is a resin main component. These phosphors absorb blue light (primary light) emitted from the light emitting element 14 and emit fluorescence (secondary light). In this way, the light emitting device 10 is configured to emit white light by mixing primary light and secondary light.

  Note that a plurality of light emitting devices 10 are simultaneously manufactured on the same lead frame, and individual light emitting devices 10 are obtained by dividing them by dicing.

  Furthermore, the sealing resin 16 according to the present embodiment is characterized in that it contains two types of silica 20 having different particle sizes as additives for preventing the generation of cracks and the sedimentation of the phosphor 18. Specifically, micro-order silica (filler) 20A is used as a filler for preventing the occurrence of cracks, and nano-order silica 20B is used as a thickening agent for preventing sedimentation of the phosphor.

  Furthermore, the inventors of the present application have found that by adjusting the content of silica, which is an additive of the sealing resin, not only the generation of cracks and sedimentation of the phosphor can be prevented, but also the peeling of the sealing resin can be prevented. It was. This will be described in detail below.

  In the present embodiment, the content of silica, which is an additive of the sealing resin, was varied, and the occurrence of cracks, the precipitation of the phosphor, and the presence or absence of peeling of the sealing resin were examined.

  First, when silica F, which is micro-order silica, is used as an additive in the sealing resin (silica F content is 12.5%, 22.5% in two ways), an additive in the sealing resin As compared with the case where silica D which is nano-order silica is used (two types of content of silica D are 2.0% and 3.0%). In either case, the green phosphor has a content of 5.35% with respect to the silicone resin, and the red phosphor has a content of 0.53% with respect to the silicone resin. Moreover, the presence or absence of sedimentation of the phosphor after 120 minutes of standing after filling with the sealing resin was examined. The comparison results are shown in Table 1 below.

  As is apparent from Table 1, the phosphor was precipitated under the conditions using silica F as an additive (see FIG. 2). This is presumably because the particle size of silica F was as large as about 1 μm, so the number of particles was small and the thickening effect on the sealing resin was insufficient. The precipitation of the phosphor occurs regardless of the amount of silica F added, and it seems that the precipitation of the phosphor cannot be prevented even if the amount of silica F added is further increased.

  On the other hand, under the conditions using silica D as an additive, the phosphor did not settle. This is presumably because silica F has a small particle size of about 7 nm and the number of particles increases, so that the viscosity of the sealing resin itself is increased and the phosphor is dispersed without settling. However, when the content of silica D is set to 3.0%, the viscosity of the sealing resin becomes too high, and the workability in the resin coating process and the like decreases, so the content of silica D is 2.0%. It is preferable to make it below, and it is more preferable to set it as 1.0 to 20% of range.

  Further, under the conditions using silica D as an additive, the phosphor did not settle, but cracks occurred at the interface between the lead frame and the sealing resin (see FIG. 3). For this reason, when silica F, which is micro-order silica, is further added as an additive in the sealing resin (the content of silica F is 7.5%, 12.5%, and 17.5% in three ways) The occurrence of cracking and peeling of the sealing resin was examined. The results are shown in Table 2 below. Table 2 shows the occurrence of cracks and peeling after curing of the sealing resin, after dicing, and after standing at −40 ° C. (15 hours and 30 hours). Further, under the conditions in Table 2, the contents of the silicone resin and the phosphor are the same as those in Table 1, and the content of silica D is 2.0%. Furthermore, the number of experimental samples under each condition is 220.

  Under the condition where the content of silica F was 7.5%, there was a sample in which peeling occurred after curing of the sealing resin, after dicing, and after standing at −40 ° C. Further, after leaving at −40 ° C., there were samples with cracks. This is because the internal stress of the sealing resin can be relieved by containing silica F, but the stress was not sufficiently relaxed because the content was small, and peeling and cracking of the sealing resin could not be prevented completely it is conceivable that.

  Moreover, under the condition where the content of silica F is 12.5%, there is no sample with peeling or cracking after curing of the sealing resin, after dicing, and after standing at −40 ° C. It was.

  Furthermore, under the condition where the content of silica F is 17.5%, there is a sample in which peeling (see FIG. 4) occurs after curing of the sealing resin, after dicing, and after standing at −40 ° C. (However, there were no cracked samples). Although the internal stress of the encapsulating resin was eased by containing silica F and the generation of cracks could be prevented, the tackiness of the encapsulating resin was lowered due to the excessive content, and the lead frame and It is thought that peeling at the interface with the sealing resin was caused.

  From the above consideration, in the light emitting device according to the present embodiment, it is possible to simultaneously prevent generation of cracks and sedimentation of the phosphor by incorporating two types of silica having different particle sizes into the sealing resin. Met. Specifically, it is preferable to add micro-order silica in order to prevent the occurrence of cracks, and it is preferable to add nano-order silica to prevent sedimentation of the phosphor.

  Furthermore, it was possible to prevent the sealing resin from peeling by adjusting the silica content (particularly, the micro-order silica content). From the results shown in Table 2, when the content of silica F was 12.5%, cracking and peeling of the sealing resin could be prevented at the same time. However, in the actual manufacturing process of the light emitting device, it was confirmed that it was necessary to further adjust the content of silica F due to differences in production environment and the like. For this reason, in the light-emitting device of this invention, it is preferable to adjust the content of the silica of a micro order so that it may become the optimal content within the range of 10 to 15%.

  In addition, as a technique for improving adhesion between the lead frame and the sealing resin to prevent peeling, a technique of performing plasma cleaning on the lead frame before resin filling is known, but the experiment shown in the present embodiment As a result, none of the plasma cleaning was performed. However, it is of course possible to combine the present invention with plasma cleaning. In this case, cracking and peeling of the sealing resin can be prevented even under more severe conditions.

  The center particle size of the micro-order silica (silica F) used in the above description was 1 μm, but the present invention is not limited to this, and the center particle size of the micro-order silica is 0. It is preferable to use a material having a thickness of 1 to 12 μm, and more preferably a material having a thickness of 0.6 to 1.6 μm. Similarly, the nano-order silica (silica D) used in the above description has a center particle size of 7 nm, but the present invention is not limited to this, and the nano-order silica has a center particle size of It is preferable to use a 5-15 nm thing.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Light-emitting device 12 Lead frame 14 Light-emitting element 16 Sealing resin 18G Green fluorescent substance 18R Red fluorescent substance 20A Micro order silica 20B Nano order silica

Claims (5)

A lead frame;
A light emitting device mounted on the lead frame;
A sealing resin for sealing the light emitting element,
The sealing resin contains a phosphor that absorbs primary light emitted from the light emitting element and emits secondary light, micro-order silica, and nano-order silica,
The light emitting device is characterized in that the content of the micro-order silica is such that the weight ratio of the sealing resin to the resin main component is in the range of 10 to 15%. The light-emitting device according to claim 1,
The content of the nano-order silica is such that the weight ratio of the sealing resin to the resin main agent is in the range of 1.0 to 2.0%. The light-emitting device according to claim 1 or 2,
The center particle size of the micro-order silica is in the range of 0.1 to 12 μm. The light-emitting device according to claim 3,
The center particle size of the micro-order silica is in the range of 0.6 to 1.6 μm. The light-emitting device according to any one of claims 1 to 4,
The nano-order silica has a center particle diameter in a range of 5 to 15 nm.

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