JP5286585B2 - Light emitting device - Google Patents

Description

  The present invention relates to a light emitting device including a substrate on which an electrode pattern is formed, a light emitting element mounted on the substrate and electrically connected to the electrode pattern, and a resin sealing body formed to cover the light emitting element. About.

  White light-emitting devices using semiconductor light-emitting elements are expected to be applied to the next-generation general lighting, bulbs such as liquid crystal backlights, fluorescent tubes and cold-cathode tubes. In recent years, with improvements in individual efficiency due to technological developments such as blue light emitting diodes and phosphors used in white light emitting devices, fluorescent lamps, cold cathode fluorescent lamps, and the like that have exceeded luminous efficiency are being commercialized. However, these white light emitting devices still have large color temperature variations compared to fluorescent lamps, cold cathode tubes, and the like, and therefore, it is required to reduce the color temperature variations just like fluorescent lamps and cold cathode tubes.

  In the actual manufacturing process of a light emitting device, one of the causes of this color temperature variation is the time elapsed from the application of the sealing resin in which the phosphor is dispersed on the blue light emitting diode until the resin is completely cured. Become. That is, even if the first half of the coating and the second half of the coating are the same in the coating state, if the elapsed time after coating is different, the degree of sedimentation of the phosphor into the resin is different. Variation in color temperature occurs (see, for example, Japanese Patent Laid-Open No. 2006-269757 (Patent Document 1)). Furthermore, since the viscosity of the resin is lower than that at room temperature at the curing temperature (100 to 150 ° C.) when the resin is cured, the phosphor is liable to settle, and the color temperature varies. It becomes a factor that occurs.

As one method of adjusting such color temperature variation, a transparent resin portion is formed on the upper layer portion of the sealing resin of the light emitting element, and the transparent resin is polished or applied to the surface to emit light. Adjusting the amount of blue light absorbed inside the resin by changing the effective distance that blue light from the diode reaches the phosphor, or changing the amount of blue light excited by the phosphor, or A method of adjusting the color temperature by the effect of adjusting the confinement space inside the resin of blue light has been proposed (see, for example, Japanese Patent Application Laid-Open No. 2004-186488 (Patent Document 2)). However, in such a method, when the color temperature variation at the time of completion is large, there is a problem that the grouping of the color temperature distribution for the polishing or resin coating process increases and the process becomes complicated. It is not a realistic improvement measure.
JP 2006-269757 A JP 2004-186488 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a light-emitting device capable of suppressing color temperature variations, particularly color temperature variations caused by phosphor settling. is there.

  A light emitting device of the present invention includes a substrate on which a wiring pattern is formed, a light emitting element mounted on the substrate and electrically connected to the wiring pattern, and a resin sealing body formed so as to cover the light emitting element. The resin sealing body includes a first resin sealing body formed so as to cover the light emitting element, and a second resin sealing body stacked on the first resin sealing body. 1 resin sealing body and 2nd resin sealing body are formed with the same kind of resin, and 2nd resin sealing body contains fluorescent substance with a density | concentration higher than 1st resin sealing body It is characterized by doing.

  In the light emitting device of the present invention, it is preferable that the substrate is an aluminum oxide substrate and the light emitting element is a blue light emitting diode.

  The light emitting device of the present invention may be realized such that the first resin sealing body does not include a phosphor and only the second resin sealing body includes a phosphor.

  The light emitting device of the present invention may also be realized so as to include a phosphor in both the first resin sealing body and the second resin sealing body. In this case, both the 1st resin sealing body and the 2nd resin sealing body contain 2 or more types of fluorescent substance, and the weight ratio of the various fluorescent substance contained in each resin sealing body becomes equal, respectively. The resin encapsulant contains two or more types of phosphors, and at least the first resin encapsulant has a lower sedimentation of the phosphor relative to the resin than other phosphors. You may be comprised so that a comparatively small fluorescent substance may be included.

  In the light-emitting device of the present invention, it is preferable that the first resin encapsulant includes fine particles serving as a light scattering material.

  In the light-emitting device of the present invention, it is preferable that at least one of the first resin sealing body and the second resin sealing body includes fine particles that prevent sedimentation of the phosphor. In this case, the fine particles are more preferably fine particles made of the same resin as the resin forming the resin sealing body.

  According to the present invention, it is possible to provide a light emitting device capable of reducing color temperature variation.

  FIG. 1 is a top view schematically showing a light emitting device 1 of a preferred first example of the present invention, and FIG. 2 is a diagram before forming the resin sealing bodies 5a and 5b of the light emitting device 1 shown in FIG. It is a top view which shows a state typically. FIG. 3 is a cross-sectional view of the light emitting device 1 shown in FIG. The light emitting device 1 of the present invention includes a substrate 2 on which a wiring pattern 4 is formed, and a light emitting element mounted on the substrate 2 and electrically connected to the wiring pattern 4 as in the examples shown in FIGS. 3 and the resin sealing body 5 formed so as to cover the light emitting element 3 are basically provided. In the light emitting device 1 of the present invention, in such a basic configuration, the resin sealing body 5 includes the first resin sealing body 5a formed so as to cover the light emitting element 3, and the second resin sealing body 5a stacked thereon. The first resin sealing body and the second resin sealing body are formed of the same type of resin, and the second resin sealing body is the first resin. It is characterized by containing a phosphor at a higher concentration than the sealing body.

  Although the board | substrate 2 used for the light-emitting device 1 of this invention is not restrict | limited in particular, It is preferable that it is formed with a material with a small thermal expansion coefficient, a high thermal conductivity, and a high light reflectance. As a material suitably used for forming such a substrate, for example, any one selected from aluminum oxide (alumina), aluminum nitride, boron nitride, silicon nitride, magnesium oxide, fortelite, steatite, and low-temperature sintered ceramics. Or a composite material thereof. Among the above, aluminum oxide has good heat dissipation with a thermal conductivity of about 20 W / m · K, high reflectivity characteristics of about 90% with respect to the wavelength of variable light, and is inexpensive and easy to process. A formed substrate is preferred. Of course, a so-called hollow substrate, a metal aluminum substrate, or the like obtained by coating a metal plate made of iron or the like having high mechanical strength and thermal conductivity with a ceramic derivative may be used as the substrate 2.

  Although the size and thickness of the substrate 2 are not particularly limited, the substrate 2 having a size of about 2 cm square and a thickness of about 1 to 3 mm is used in FIGS. 1 and 2 from the viewpoint of heat dissipation and mechanical strength. An example was shown. Moreover, as shown in FIGS. 1 and 2, it is preferable that an attachment hole 6 (for example, a diameter of about 3 mm) for fixing the light emitting device 1 to a lamp or a radiating fin with screws is formed.

  As the light emitting element 3 used in the light emitting device 1 of the present invention, a light emitting element usually used in this field can be used without particular limitation. Examples of such light-emitting elements include sapphire substrates, ZnO (zinc oxide) substrates, GaN substrates, Si substrates, SiC substrates, spinels, GaN (gallium nitride) -based compound semiconductors, and ZnO (zinc oxide). Examples thereof include semiconductor light emitting devices such as blue LED (light emitting diode) chips, InGaAlP compound semiconductor chips, and AlGaAs compound semiconductor LED chips on which materials such as compound compound semiconductors are grown. In particular, a single-sided two-electrode structure can be easily formed on an insulating substrate, and a nitride semiconductor with good crystallinity can be formed with high productivity. Therefore, a blue LED in which a gallium nitride compound semiconductor is grown on a sapphire substrate is used as a light emitting element. It is preferable to use it.

  2 shows an example in which a plurality of light emitting elements 3 are mounted so as to be arranged in a straight line along the wiring pattern 4 with a linear wiring pattern 4 formed on the substrate 2 interposed therebetween. The number of wiring patterns 4 in the light emitting device 1 of the present invention is not particularly limited. However, since one anode wiring pattern and one cathode wiring pattern are required, at least two wiring patterns are required. It is necessary and is appropriately selected depending on the series and parallel configurations of the light-emitting elements 3 (preferably GaN-based blue LEDs). In FIG. 2, 20 GaN-based blue LEDs having a light emission wavelength of 460 nm band formed on a sapphire substrate having a 240 μm × 480 μm square and a thickness of about 100 μm as light-emitting elements 3 are 50 μm thick gold-palladium alloy, 500 μm thick An example is shown in which three linear wiring patterns 4a, 4b, and 4c formed in a gold stacked structure are mounted in a straight line in two rows (10 in a row).

  2 and 3, a light emitting element 3 having a positive electrode portion and a negative electrode portion formed on one surface is used. Such a light emitting element 3 is a surface on which a positive electrode portion and a negative electrode portion are formed. As shown in FIG. 2, an example is shown in which a resin paste 7 (for example, a resin paste made of a silicone resin) is mounted between the wiring patterns 4 on the substrate 2 and electrically connected to the wiring patterns 4. Note that the electrical connection between the wiring pattern 4 and the light emitting element 3 is realized, for example, by bonding bonding wires W to the wiring pattern 4 at the plus electrode portion and the minus electrode portion of the light emitting element 3, respectively. In the example shown in FIG. 2 and FIG. 3, among the light emitting elements 3 mounted in two rows, wire bonding is performed by the negative electrode portion of the light emitting element 3 in one row, the wiring pattern 4a, and the bonding wire W. A minus electrode pad 4a1 for the light emitting device is provided at the terminal portion of the pattern 4a, and the plus electrode portion of the light emitting element 3 in the other row and the wiring pattern 4b are wire-bonded by a bonding wire W, and this wiring pattern 4b Is provided with a positive electrode pad 4b1 for a light emitting device. Further, a wiring pattern 4c is formed between the wiring pattern 4a and the wiring pattern 4b, and among the light emitting elements 3 mounted in two rows, the positive electrode portion of the light emitting element 3 in one column and the other The negative electrode portions of the light emitting elements 3 in this row are electrically connected to the wiring pattern 4c via bonding wires W.

  As the bonding wire W, a suitable fine metal wire used in this field can be used without particular limitation. Examples of such fine metal wires include gold wires, aluminum wires, copper wires, platinum wires, etc., among which there is little corrosion, moisture resistance, environmental resistance, adhesion, electrical conductivity, thermal conductivity, elongation. It is preferable to use a gold wire as the bonding wire W because the rate is good and the ball is easily formed. The bonding wire W having a diameter of several tens of μm can be preferably used.

  As shown in FIG. 3, the light emitting device 1 of the present invention includes a resin sealing body 5 formed so as to cover the light emitting element 3, and the resin sealing body 5 includes a first light emitting element 3. The resin sealing body 5a and the second resin sealing body 5b. One feature of the first resin sealing body 5a and the second resin sealing body 5b in the present invention is that they are formed of the same type of resin. Thus, unlike the case where a two-layer resin sealing body is formed using different types of resins, it is possible to prevent a decrease in luminous efficiency due to interface reflection occurring at the two-layer resin interface. Reliability problems such as resin peeling due to the difference in the linear expansion coefficient of the resin of the layer can be prevented.

  The resin material for forming the first resin sealing body 5a and the second resin sealing body 5b in the present invention is not particularly limited as long as it is a material having translucency, and is widely used in this field. It can be formed using any appropriate material. Examples of such resin materials include translucent resin materials having excellent weather resistance such as silicone resins, epoxy resins, urea resins, etc., but from the viewpoint of weather resistance, silicone resins or epoxy resins are used. Is preferred.

  The light emitting device 1 of the present invention is also characterized in that the second resin sealing body 5b contains a phosphor at a higher concentration than the first resin sealing body 5a. In the light emitting device 1 of the present invention, the first resin encapsulant 5a and the second resin encapsulant 5a are scattered so that the light emitted from the light emitting element 3 (preferably a blue LED) is scattered by the second resin encapsulant 5b. The ratio of the phosphor concentration to the resin sealing body 5b is preferably set to about 0.15 or more.

  In the light emitting device of the present invention, as long as the second resin encapsulant contains a phosphor at a higher concentration than the first resin encapsulant, the first resin encapsulant as in the example shown in FIG. It may be realized that the stop body 5a does not include a phosphor and only the second resin sealing body 5b includes the phosphor 8 (example shown in FIG. 3). By realizing that the first resin sealing body 5a does not include a phosphor and only the second resin sealing body 5b includes the phosphor 8, radiation is emitted from the light emitting element 3 (preferably a blue LED). Since some of the emitted light propagates through the first resin sealing body, the efficiency is slightly reduced, but variation in chromaticity can be suppressed (the effect of sedimentation of the phosphor on the resin can be reduced most). There are significant advantages.

By providing the structure as described above, a light-emitting device with reduced color temperature variation is provided. Specifically, the inventors specifically prepared a sample of the light-emitting device 1 shown in FIGS. 1 to 3 and a resin encapsulant with a yellow phosphor (divalent europium is activated ( 100 pieces of the same comparative samples are prepared except that the silicone resin single layer in which only Sr, Ba, Ca) ₂ SiO ₄ ) is dispersed is used, and the color temperature is varied using a commonly used chromaticity meter. Of the sample was 5010K ± 70K, while that of the comparative sample was 5015K ± 300K. The average value of the total luminous flux of the sample was 170 lm, which was slightly lower than the average value of the total luminous flux of the comparative sample, 200 lm.

  The color temperature variation as seen in the comparative sample is considered to be caused by the sedimentation of the phosphor during resin application when producing the resin sealing body. In the light emitting device of the present invention, this phosphor sedimentation It is considered that variation in color temperature can be reduced by suppressing. Here, FIG. 4 shows three samples (1) to (3) in which the light emitting device of the present invention is specifically manufactured as described above, and a silicone resin single layer in which only the yellow phosphor is dispersed. The graph which shows the result of having measured the color temperature change with time after resin application in which fluorescent substance was dispersed about three similar comparative samples (1) to (3) except that a resin sealing body was formed The vertical axis represents the color temperature (K), and the horizontal axis represents the elapsed time (minutes) after resin application. In addition, about sample (1)-(3), the elapsed time after resin application represents the elapsed time after apply | coating resin which forms the 2nd resin sealing body. From FIG. 4, the color temperature of both the sample and the comparative sample changes with the lapse of time after the resin application, but the color temperature changes by about 600 K with respect to the initial value after 5 hours in the comparative sample. On the other hand, in the sample, it can be seen that the variation of the color temperature of about 100K with respect to the initial value can be suppressed.

  Here, FIG. 5A is a diagram schematically showing the sedimentation state of the phosphor in the vicinity of the light-emitting element 100 immediately after resin application in the comparative sample, and FIG. 5B is after resin application in the comparative sample. It is a figure which shows typically the sedimentation state of the fluorescent substance in the vicinity of the light emitting element 100 after progress for a fixed time. On the other hand, FIG. 6A is a diagram schematically showing the sedimentation state of the phosphor 8 in the vicinity of the light emitting element 3 immediately after the resin application with the sample, and FIG. 6B is the diagram after the resin application with the sample. It is a figure which shows typically the sedimentation state of the fluorescent substance 8 in the vicinity of the light emitting element 3 after progress for a fixed time. 6A and 6B, as in the example shown in FIG. 3, the first resin sealing body 5a does not contain a phosphor, and only the second resin sealing body 5b is included. In this example, the phosphor 8 is contained so that the second resin encapsulant 5b contains the phosphor at a higher concentration than the first resin encapsulant 5a. 5A, FIG. 5B, FIG. 6A, and FIG. 6B, a phosphor that can effectively absorb blue light (phosphor 101 in FIG. 5). In FIG. 6, the phosphor 8) is indicated by white circles, and the phosphor that cannot absorb blue light (phosphor 102 in FIG. 5) is indicated by hatching.

  As shown in FIGS. 5A and 5B, in the comparative sample, the concentration of the phosphor in the vicinity of the light emitting element (blue LED) 100, particularly in the vicinity of the light emitting region 100a of the light emitting element, is decreased by sedimentation as time passes after the resin application. Will be lower. As a result, the number of effective phosphors 101 that can absorb the blue light 103 emitted from the light emitting element 100 is reduced. From the experimental results, the change in the color temperature in FIG. 4 is shifted to a higher color temperature as time passes (white is obtained by mixing the yellow light emitting part of the phosphor and the light emitting color of the light emitting diode). Therefore, if there is a lot of blue light outside, the color temperature will shift to the higher side.) Due to such a mechanism, in the comparative sample, the phosphor settles, and it is considered that the color temperature variation with time of the entire light emitting device occurs.

  On the other hand, in the sample in which the light-emitting device of the present invention is specifically manufactured, as shown in FIGS. 6A and 6B, the sedimentation of the phosphor 8 in the second resin encapsulant 5b occurs. Regardless, the effective number of phosphors for the blue light 9 emitted from the light emitting element (blue LED) is unlikely to change. As a result, the color temperature variation with time is suppressed, so that it is understood that a light emitting device with reduced color temperature variation can be realized.

  In the light emitting device 1 of the present invention, the thickness of the first resin sealing body 5a is not particularly limited as long as it can cover the periphery of the light emitting element 3, but is preferably in the range of 150 to 250 μm. When the thickness of the 1st resin sealing body 5a is less than 150 micrometers, the thickness of the 1st resin sealing body 5a will become thinner than the thickness of the light emitting element 3 (preferably blue LED) generally used. This is because the effect of the present invention tends to be reduced, and when it exceeds 250 μm, the entire thickness of the first and second resin sealing bodies is increased, and the temperature change of the light emitting device 1 is increased. This is because the resin tends to easily peel off. FIG. 3 shows an example in which the thickness of the first resin sealing body 5a is 200 μm.

  Moreover, in the light-emitting device 1 of this invention, although it does not restrict | limit especially also about the thickness of the 2nd resin sealing body 5b, The inside of the range of 200-350 micrometers is preferable. This is because when the thickness of the second resin sealing body 5b is less than 200 μm, it tends to be difficult to uniformly apply the first resin sealing body 5a on the first resin sealing body 5a. This is because if it exceeds, the second resin sealing body 5b may be peeled off. In addition, from the viewpoint of preventing peeling of the entire resin sealing body 5, it is preferable that the total thickness of the first resin sealing body 5a and the second resin sealing body 5b is 0.6 μm or less.

Examples of the phosphor 8 used in the light emitting device 1 of the present invention include Ce: YAG (cerium activated yttrium, aluminum, garnet) phosphor, Eu: BOSE (europium activated barium, strontium, orthosilicate) phosphor, Eu: SOSE. (Europium-activated strontium / barium / orthosilicate) phosphors, europium-activated α-sialon phosphors and the like can be preferably used, but are not limited thereto. Further, if the amount (concentration) of the phosphor 8 is contained so that the second resin sealing body 5b is larger than the first resin sealing body 5a, it corresponds to a desired color temperature. Can be selected as appropriate. For example, when the phosphor 8 is contained only in the second resin sealing body 5b as in the example shown in FIG. 3, Eu: SOSE (europium activated strontium barium. Orthosilicate) phosphor (divalent europium activated (Sr, Ba, Ca) ₂ SiO ₄ phosphor) is selected when the content is selected so that the color temperature of the light emitting device is 5000K. .

  FIG. 7 is a cross-sectional view schematically showing a light emitting device 21 of a preferred second example of the present invention. The light emitting device 21 of the example shown in FIG. 7 is a diagram except that the phosphor 22 is contained in the second resin sealing body 5b and the phosphor 23 is also contained in the first resin sealing body 5a. 3 are the same as those of the light emitting device 1 of the example shown in FIG. 3, and parts having the same configuration are denoted by the same reference numerals and description thereof is omitted. If the 2nd resin sealing body is comprised so that the 2nd resin sealing body may contain fluorescent substance with a density | concentration higher than a 1st resin sealing body, it will be like the example shown in FIG. The phosphors 23 and 22 may be contained in both the first resin sealing body 5a and the second resin sealing body 5b.

Thus, when it implement | achieves so that a 1st resin sealing body and a 2nd resin sealing body may contain a fluorescent substance in both, fluorescent substance of the same kind as fluorescent substance 23,22 (for example, bivalent europium, for example) For example, about 20% of the content of the (Sr, Ba, Ca) ₂ SiO ₄ phosphor activated by (1) is a desired color temperature, and the first resin encapsulant 5a is 80 The amount of the phosphor 22 contained in the second resin encapsulant 5b is contained in the first resin encapsulant 5a so that about 2% is contained in the second resin encapsulant 5b. It should be more than 23. By doing so, the light emitting device 21 adjusted to a desired color temperature while containing the phosphors 22, 2323, 22 in both the first resin sealing body 5 a and the second resin sealing body 5 b. Can be realized.

  Also in the light emitting device 21 as shown in FIG. 7, as described above, the variation in the color temperature due to the settling of the phosphor can be suppressed. Further, in the light emitting device 21 as shown in FIG. 7, blue light emitted from the light emitting element 3 (blue LED) is converted into yellow light by a small amount of phosphor 23 contained in the first resin sealing body 5a. Or scattered as blue light. The scattered blue light is converted into yellow light by the phosphor 22 contained in the second resin sealing body 5b or exits from the light emitting device as blue light. The light converted into yellow by the phosphor 23 in the first resin sealing body 5a is also scattered by the other phosphors 23 included in the first resin sealing body, and the second resin sealing body 5b Transmits and exits the light emitting device 21. Therefore, it is possible to prevent the blue light propagating through the first resin sealing body 5a from being directly emitted to the outside as it is from the end of the light emitting device. Moreover, as shown in FIG. 7, it is set as the structure which contains the fluorescent substance 23,22 in both the 1st resin sealing body 5a and the 2nd resin sealing body 5b, and is the example shown in FIG. While the total luminous flux of the light emitting device 1 is about 170 lm, for example, the light emitting device 21 with the total luminous flux of about 200 lm can be realized.

  FIG. 8 is a cross-sectional view schematically showing a light emitting device 31 of a preferred third example of the present invention. The light emitting device 31 of the example shown in FIG. 8 includes two types of phosphors 32 and 33 in the second resin encapsulant 5b, and two types of phosphors 34 and 33 in the first resin encapsulant 5a. 3 is the same as the light-emitting device 1 of the example shown in FIG. 3 except that 35 is contained, and the same reference numerals are given to portions having the same configuration and the description thereof is omitted. With the combination of the blue LED, which is a light emitting element as described above, and one kind of phosphor, it is difficult to increase the color rendering properties of the light emitting device or to obtain light emission colors of various shades such as a light bulb color, In order to realize such a light emitting device, it is necessary to combine a blue LED and two or more kinds of phosphors. When two or more kinds of phosphors are used in this way, both the first resin sealing body and the second resin sealing body include two or more kinds of phosphors, and various kinds of resins included in each resin sealing body, respectively. It is preferable that the weight ratio between the phosphors be equal.

As an example of the combination of phosphors, for example, yellow phosphors emitting yellow light having a peak wavelength of 560 nm (for example, bivalent europium activated (Sr, Ba, Ca) ₂ SiO ₄ phosphors) 32 and 34, and peak wavelengths Red phosphor emitting 640 nm red (for example, (M2 _1-b Eu _b ) M3SiN ₃ phosphor activated with divalent europium (wherein M2 is at least one selected from Mg, Ca, Sr and Ba) M3 represents at least one element selected from Al, Ga, In, Sc, Y, La, Gd and Lu, and b is a number satisfying 0.001 ≦ b ≦ 0.05. )) A combination with 33 and 35 is mentioned, but it is of course not limited thereto. Under the present circumstances, the weight ratio of the yellow fluorescent substance 34 contained in the 1st resin sealing body 5a and the yellow fluorescent substance 32 contained in the 2nd resin sealing body 5b is the 1st resin sealing body 5a. The red phosphor 35 contained in the second resin sealing body 5b and the red phosphor 33 contained in the second resin sealing body 5b are configured to have the same weight ratio (for example, contained in the first resin sealing body 5a). The weight ratio of each phosphor is about 30% of the amount of each phosphor necessary to obtain a desired color temperature, and the weight ratio of each phosphor contained in the second resin sealing body 5b is desired. About 70% of the amount of each phosphor necessary to obtain the desired color temperature). That is, the weight ratio between the two types of phosphors is kept constant for each of the first resin sealing body 5a and the second resin sealing body 5b, and the second resin sealing body 5b It adjusts so that various fluorescent substance may be contained in the density | concentration higher than the 1st resin sealing body 5a.

  With the configuration shown in FIG. 8, for example, it is possible to realize a light bulb 31 that has a color rendering property of 85, a color temperature variation of 3010K ± 80K, and a total luminous flux of 120 lm. Note that the total luminous flux is lower than that of the light emitting device 21 in the example shown in FIG. 7, but this is because the Stokes loss generated between the light emitting element and each phosphor (the emission wavelength of the light emitting element is reduced). When the peak wavelength of the phosphor is 650 nm at 460 nm, energy loss that occurs when one photon of the light-emitting element is converted into one electron after being converted into one electron by the phosphor, and is 1-460 / This loss corresponds to 650. This loss is considered to be caused by the fact that the wavelength interval of the light emitting element is large, for example, when a phosphor such as red is used.

  Moreover, FIG. 9 is sectional drawing which shows typically the light-emitting device 41 of the preferable 4th example of this invention. The light emitting device 41 of the example shown in FIG. 9 is the same as the light emitting device 1 of the example shown in FIG. 3 except for a part, and parts having the same configuration are denoted by the same reference numerals and described. Omitted. In the light emitting device of the present invention, when both the first resin sealing body and the second resin sealing body contain a phosphor, the resin sealing body contains two or more kinds of phosphors (see FIG. 9). In the example shown, the first resin encapsulant 5a contains one type of phosphor 44 and the second resin encapsulant 5b contains two types of phosphors 42 and 43), and at least the first resin encapsulant is In addition, the precipitation of the phosphor relative to the resin may be realized so as to include a relatively small phosphor as compared with other phosphors.

When realizing the light-emitting device having such a configuration, first, the degree of sedimentation of all phosphors used in the light-emitting device with respect to the sealing resin is individually confirmed. As a method for confirming the degree of sedimentation, phosphors are individually dispersed in a sealing resin, the resin is cured after an appropriate time, and the concentration distribution of the phosphor in the cross section of the resin after curing is observed. Can be determined. Using such a technique, for example, the above-described yellow phosphor (Sr, Ba, Ca) ₂ SiO ₄ and red phosphor (M2 _1-b Eu _b ) M3SiN ₃ were tested. It was found that Sr, Ba, Ca) ₂ SiO ₄ was more likely to settle against the sealing resin used. The degree of sedimentation of the phosphor into the resin (sedimentation rate) is determined by the density and particle diameter of the phosphor. However, the density of the phosphor is generally determined by the phosphor base material, and it is generally difficult to arbitrarily set the particle diameter depending on the light emission efficiency.

The light emitting device 41 in the example shown in FIG. 9 requires, for example, (M2 _1-b Eu _b ) M3SiN ₃ phosphor as the red phosphor 44 based on the test results described above. Only about 20% of the total amount of red phosphor required for a certain color temperature is dispersed. Also with the configuration of the first resin sealing body 5a, it is possible to prevent the emission of blue light from the side surface portion of the light emitting device to the outside, and thus it is possible to suppress a decrease in light emission efficiency. Furthermore, since only the phosphor that does not easily settle with respect to the resin is used, variations in color temperature due to the first resin sealing body 5a hardly occur. The second resin encapsulant 5b includes (Sr, Ba, Ca) ₂ SiO ₄ as yellow phosphors 43, and red phosphors 42 as (M2 _{1− b} Eu _b ) Disperse the M3SiN ₃ phosphor about 80% of the total amount of red phosphor needed for the required color temperature. Even with such a configuration, the influence of sedimentation of the phosphor on the resin in the vicinity of the light-emitting element 3 can be reduced. it can.

  FIG. 10 is a cross-sectional view schematically showing a light emitting device 51 of a preferred fifth example of the present invention. The light emitting device 51 of the example shown in FIG. 10 is the same as the light emitting device 1 of the example shown in FIG. 3 except for a part, and parts having the same configuration are denoted by the same reference numerals and described. Omitted. In the light emitting device 51 of the example of the present invention shown in FIG. 10, both the first resin sealing body 5a and the second resin sealing body 5b contain phosphors 53 and 52, and further the first resin sealing The body 5a contains fine particles 54 that serve as a light scattering material. With such a configuration, variation in color temperature due to sedimentation of the phosphor with respect to the resin can be suppressed, and the side surface portion of the light-emitting device is formed by the first resin sealing body 5a including the fine particles 54 serving as a light scattering material. The emission of blue light from can be prevented, and a decrease in luminous efficiency can be suppressed.

For example, yellow phosphors (Sr, Ba, Ca) ₂ SiO ₄ are used as the phosphors 53 and 52, and 10% of the amount that makes the color temperature a desired value in the first resin sealing body 5 a. Illustrated is a case where the phosphor 53 of the degree is contained, and about 90% of the amount of the phosphor 52 contained in the second resin sealing body 5b is set to a desired value. It is not limited. For example, this is a case where only the second resin encapsulant contains a phosphor, and the first resin encapsulant contains only fine particles serving as a light diffusing material (no phosphor). However, the same effect can be obtained.

  The fine particles 54 used as the light scattering material are not particularly limited, and fine particles such as barium titanate, barium sulfate, titanium oxide, aluminum oxide, silicon oxide, and light calcium carbonate can be used. The particle diameter of the fine particles 54 is preferably in the range of 0.1 to 1.0 μm. By using the fine particles 54 having the particle diameter, the blue light from the light emitting element and the first resin encapsulant 5a can be obtained. The yellow light from the phosphor 53 contained in can be diffusely reflected well. The content of the fine particles 54 serving as the light scattering material is not particularly limited. However, if the light scattering function is exhibited and the light scattering material is excessively added, the viscosity becomes high, and the resin sealing body having a uniform thickness can be obtained. From the viewpoint of difficulty in obtaining, it is preferably in the range of 20 to 50% by weight.

FIG. 11 is a cross-sectional view schematically showing a light emitting device 61 of a sixth preferred example of the present invention. The light emitting device 61 of the example shown in FIG. 11 is the same as the light emitting device 1 of the example shown in FIG. 3 except for a part, and parts having the same configuration are denoted by the same reference numerals and described. Omitted. The light emitting device 61 of the example shown in FIG. 11 contains only fine particles 54 (for example, silica particles) that are light scattering materials similar to the light emitting device 51 of the example shown in FIG. 10 in the first resin sealing body 5a. (The phosphor is not contained), and the second resin sealing body 5b includes a phosphor 62 (for example, an amount of yellow phosphor (Sr, Ba, Ca) ₂ SiO ₄ ) and fine particles 63 acting as an anti-settling material for preventing the phosphor from settling. As described above, at least one of the first resin encapsulant and the second resin encapsulant includes fine particles that prevent sedimentation of the phosphor, so that the phosphor settles in the resin and the light emitting element Variations in color temperature caused by changes in the absorption state of the emitted blue light can be further suppressed.

  As the fine particles 63 acting as an anti-settling material, organic compound fine particles such as polyethylene oxide, polyethylene oxide amide, fatty acid amide, polyether ester type surfactant, sulfate ester type anionic surfactant are used. Is possible. In addition, in the case of a light emitting device with a large calorific value higher than the sub-W class, the above-mentioned organic chemicals are uneasy in terms of heat resistance and light resistance. Fine particles are used. Although it is theoretically possible to suppress the sedimentation of the phosphor only with such an anti-settling material, in order to realize a sufficient anti-settling effect, a large amount of anti-settling material is put in the resin. There must be. However, such an anti-settling material is poorly soluble, so that it is difficult to disperse uniformly in the resin, and furthermore, since the translucency is not so good, the total luminous flux is reduced. For this reason, when using the microparticles | fine-particles which act as such a sedimentation prevention material, auxiliary use is preferable.

  In the light emitting device of the present invention, it is preferable to use fine particles made of the same resin as the resin forming the resin sealing body as the fine particles 63 that act as the anti-settling material. By using fine particles made of the same resin as the resin forming the resin sealing body, it is the same resin as the sealing resin, together with a function as an anti-settling material that can suppress the sedimentation of the phosphor in the resin. The transparency is not impaired regardless of the amount of dispersion, and the total luminous flux is not lowered.

  Fine particles made of the same resin as the resin forming the resin sealing body can be prepared by pulverizing a resin lump to be used with the sealing resin using a pulverizer such as a rod mill, a ball mill, a jet mill, or a cutter mill. it can. Furthermore, sealing resins with good weather resistance and high-temperature characteristics generally have very low hardness, but even in such resins, by cooling the resin at a liquid nitrogen temperature and grinding (embrittlement point) Cooling to the following makes use of the property that it is extremely fragile against impacts and facilitates pulverization), and has a smaller particle size than that when pulverized at room temperature, and is suitable as an anti-settling material. be able to. For example, by performing low-temperature pulverization at a liquid nitrogen temperature, in the case of a silicone resin, fine particles having a particle diameter of d90 of about 100 μm can be obtained. In addition, as a relatively easy method for producing fine particles made of the same resin as the resin forming such a resin sealing body, there is one method by pulverization as described above. It is also possible to produce by using a method such as a so-called spray drying method in which a synthetic method, a resin raw material is injected into a high-temperature air from a nozzle and thermally cured when dropped.

  The content of the fine particles 63 acting as an anti-settling material is not particularly limited, but the viscosity is improved by increasing the content. Therefore, in order to maintain the uniformity of the film thickness of the resin encapsulant, 5 to 20 is required. It is preferable to be in the range of% by weight. FIG. 11 shows the case where the fine particles 63 that act as an anti-settling material are contained only in the second resin encapsulant 5b, but the phosphor and the sediment are only contained in the first resin encapsulant. Fine particles that act as a preventive material may be included, and both the first resin encapsulant and the second resin encapsulant contain a phosphor and fine particles that act as an anti-settling material. Also good.

  In the light-emitting device of the present invention having the various structures described above, the electrode structure, wiring pattern, light-emitting element layout, number, series-parallel, and the like are not limited to the above-described examples, and can take various forms. be able to. In addition, as a light emitting element, a conductive substrate such as GaN or Si may be used, and a positive electrode and a negative electrode provided on the element back surface and the element surface may of course be used. In this case, it is possible to adopt a form of mounting on the wiring pattern using a conductive paste such as an Ag paste. Further, the wavelength of the light emitting element is not limited to blue, and a light emitting element having a wavelength in the near-ultraviolet region of the 400 nm band can also be used. In addition, the phosphor used can also emit other colors of phosphors, such as red and green monochromatic ones, as long as they can absorb the light emitted from the light emitting element. is there.

  Moreover, the manufacturing method of the light emitting device of the present invention is not particularly limited, and can be manufactured by appropriately combining conventionally known methods widely known in the field. In addition, it is preferable to produce the 1st resin sealing body and 2nd resin sealing body which are the characteristic structures in the light-emitting device of this invention as follows, for example.

  First, a wiring pattern is formed, and a resin sealing body is formed on a substrate (for example, an alumina substrate) on which a light emitting element (for example, a blue LED) electrically connected to the wiring pattern is mounted so as to cover the light emitting element. A fluororesin (for example, PTFE) sheet provided with a hole having a resin shape to be applied is attached to the portion to be applied using an adhesive sheet or the like. Next, an amount of resin (for example, a silicone-based resin) is applied to the hole by a dispenser device so as to have a desired thickness (for example, 0.2 mm). If necessary, the resin is appropriately dispersed with phosphors, fine particles serving as a light scattering material, fine particles serving as an anti-settling material, and the like. And after resin application | coating, after resin adapts substantially uniformly inside a sheet | seat, it preliminarily cures at 100 degreeC for 1 hour, and main curing is performed at 150 degreeC for about 4 hours. This cured resin becomes the first resin sealing body.

  Next, after the resin is cured, the light emitting device taken out from the oven is cooled to about room temperature, and then the same type of resin (for example, a silicone resin) used for forming the first resin sealing body is used. 1 is applied on the resin sealing body. In this resin, a phosphor is dispersed, and if necessary, fine particles that serve as an anti-settling material are dispersed. When applying the resin, it is preferable to apply the resin with a dispenser device while stirring the resin so that the phosphor does not easily settle. After the resin application, the applied resin is cured under the same curing conditions as those for forming the first resin encapsulant to obtain a second resin encapsulant. After curing, the laminated structure of the first resin sealing body and the second resin sealing body can be realized by peeling the fluororesin sheet from the substrate so that the resin does not peel off.

  As shown in FIGS. 7 to 10, when both the first resin sealing body and the second resin sealing body contain a phosphor, the first resin is used for each light emitting device. After applying and curing the resin for forming the sealing body, the color temperature is measured, and the second resin sealing is performed according to the amount of deviation of the first resin sealing body from the desired color temperature setting value. It is preferable to finely adjust the dispersion amount of the phosphor with respect to the resin for forming the body. By doing in this way, since the influence of the color temperature of the 1st resin sealing body which is easy to produce color temperature shift | offset | difference can be correct | amended, the center value correction | amendment with respect to the setting value of desired color temperature can be performed.

It is a top view which shows typically the light-emitting device 1 of a preferable example of this invention. It is a top view which shows typically the state before forming the resin sealing bodies 5a and 5b of the light-emitting device 1 shown in FIG. It is sectional drawing seen from the cutting surface line III-III of the light-emitting device 1 shown in FIG. Three samples (1) to (3) that specifically produced the light-emitting device of the present invention, and three samples that were the same except that the resin sealing body was a silicone-based resin single layer in which only a yellow phosphor was dispersed. Is a graph showing the results of measuring the change in color temperature over time after application of the resin in which the phosphor is dispersed, with respect to Comparative Samples (1) to (3), in which the vertical axis represents the color temperature (K) and the horizontal axis Is the elapsed time (minutes) after resin application. FIG. 5A is a diagram schematically showing the sedimentation state of the phosphor in the vicinity of the light emitting element 100 immediately after resin application in the comparative sample, and FIG. 5B is a lapse of a certain time after resin application in the comparative sample. It is a figure which shows typically the sedimentation state of the fluorescent substance in the vicinity of the light emitting element 100 after. FIG. 6A is a diagram schematically showing the sedimentation state of the phosphor 8 in the vicinity of the light emitting element 3 immediately after resin application on the sample, and FIG. 6B is a diagram after a certain time has elapsed after resin application on the sample. It is a figure which shows typically the sedimentation state of the fluorescent substance 8 in the vicinity of the light emitting element 3 in FIG. It is sectional drawing which shows typically the light-emitting device 21 of the preferable 2nd example of this invention. It is sectional drawing which shows typically the light-emitting device 31 of the preferable 3rd example of this invention. It is sectional drawing which shows typically the light-emitting device 41 of the preferable 4th example of this invention. It is sectional drawing which shows typically the light-emitting device 51 of the preferable 5th example of this invention. It is sectional drawing which shows typically the light-emitting device 61 of the preferable 6th example of this invention.

Explanation of symbols

  1, 21, 31, 41, 51, 61 Light emitting device, 2 substrate, 3 light emitting element, 4 wiring pattern, 5 resin sealing body, 5a first resin sealing body, 5b second resin sealing body, 8 , 22, 23, 32, 33, 34, 35, 42, 43, 44, 52, 53 phosphor.

Claims (6)

A substrate on which a wiring pattern is formed;
A light emitting element mounted on a substrate and electrically connected to a wiring pattern;
A light emitting device including a resin sealing body formed so as to cover the light emitting element,
The resin sealing body contains two or more types of phosphors, and includes a first resin sealing body containing a phosphor formed so as to cover the light emitting element, and a phosphor laminated thereon. A second resin sealing body,
The first resin sealing body and the second resin sealing body are formed of the same type of resin,
The second resin encapsulant contains a phosphor at a higher concentration than the first resin encapsulant,
The light emitting device, wherein at least the first resin sealing body includes a phosphor in which precipitation of the phosphor with respect to the resin is relatively small as compared with other phosphors.   The light emitting device according to claim 1, wherein the substrate is an aluminum oxide substrate, and the light emitting element is a blue light emitting diode. First resin sealing body comprises fine particles of a light scattering material, light-emitting device according to claim 1 or 2. At least one of the first resin sealing body and a second resin sealing body, comprising microparticles to prevent sedimentation of the phosphor, the light emitting device according to any one of claims 1-3. The light emitting device according to claim 4 , wherein the fine particles are fine particles made of the same resin as that forming a resin sealing body. The resin forming the resin sealing body is a silicone resin or epoxy resin, the light emitting device according to any one of claims 1-5.

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