JP2011138831A - Manufacturing method for light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a light-emitting device which easily controls and stabilizes the dispersion of a fluorescent material, improves a light extraction efficiency, and carries out two-stage sealing with a fine productivity to improve the adhesion by two-stage sealing. <P>SOLUTION: The manufacturing method includes: a first step of flip mounting an LED chip 2 on the upper face of a substrate 1; a second step of sticking a pre-setting silicone sheet 4 containing a fluorescent material made of a silicone 6 dispersed with a fluorescent material 5 closely to the upper face and side peripheral face of the LED chip 2 without air therebetween and setting the silicone sheet 4; and a third step of compressively molding a translucent, pre-setting silicone into a lens covering the silicone sheet 4 when the silicone sheet 4 becomes a half-set state in the second step and setting the silicone sheet 4 and the lens at the same time to join them. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a light emitting device using an LED chip and a phosphor.

  In the light emitting device using the LED chip and the phosphor that emits fluorescence when excited by the light emitted from the LED chip, the following various types of the phosphor are arranged in the vicinity of the LED chip. There is.

(1) As shown in FIG. 4 (a1), the LED chip 51 is sealed by compression molding of a sealing resin 53 containing a phosphor 52, and the sealing resin 53 is further compression molded of a transparent sealing resin 54. Two-stage sealing type (Patent Document 1). In this type, since it is necessary to perform compression molding twice, productivity is not good. In addition, two molds for two compression moldings are required. Further, since the outer shape of the sealing resin containing the phosphor is determined by the mold used for compression molding, when the size of the LED chip 51 is changed as shown in FIG. 4 (a2), the phosphor 52 is contained. The amount of the sealing resin 53 also changes, so that the emission color changes as it is. In order to obtain the same emission color, it is necessary to change the external shape of the sealing resin 53 by changing the concentration of the phosphor or changing the mold.

(2) A sedimentation type in which an LED chip is sealed by compression molding of a sealing resin containing a phosphor, and the phosphor in the sealing resin is sedimented and distributed in the vicinity of the LED chip (Patent Document 2). In this type, it is difficult to stably obtain the sediment distribution amount of the phosphor. The resin for compression molding (mostly silicone) has a higher viscosity than the resin for transfer potting, so the phosphor is difficult to settle, and the compression molding is short in the curing time of the resin, so before the phosphor settles This is because the resin hardens.

(3) As shown in FIG. 4B, the LED chip 61 is sealed by compression formation of a transparent sealing resin 62, and a resin sheet 64 containing a phosphor 63 is placed around the transparent sealing resin 62. Sheet covering type. In this type, a part of the light emitted from the LED chip 61 is reflected on the inner surface of the resin sheet 64 containing the phosphor 63 and returns to the inside to become a loss, resulting in a problem that the light extraction efficiency is lowered.

  Although not related to the phosphor, in Patent Document 3, the LED chip connected on the substrate is covered with a thermosetting film (epoxy resin composition), and the thermosetting film is thermoset and sealed. Technology to stop is proposed.

  Similarly, although not related to the phosphor, Patent Document 4 discloses an outermost resin layer (polycarbodiimide or the like), a light diffusion layer containing light diffusing particles (polycarbodiimide or the like), and a resin layer having a low refractive index. There has been proposed a technique in which a sealing sheet having (epoxy resin or the like) is laminated on a printed circuit board on which an optical semiconductor element is mounted with a vacuum laminator and pressure-molded with a stamper.

JP 2008-211205 A JP 2006-229054 A JP 2009-10109 A JP 2006-140362 A

  An object of the present invention is to easily control and stabilize the dispersion of the phosphor, and to improve the light extraction efficiency.

  A further object of the present invention is to implement two-stage sealing with high productivity and to improve the adhesion between the two-stage sealing.

The manufacturing method of the light emitting device of the present invention is as follows:
A first step of flip chip mounting the LED chip on the upper surface of the substrate;
A second step of curing the pre-curing phosphor-containing silicone sheet made of silicone containing the phosphor in a dispersed state, in close contact with the upper surface and side peripheral surface of the LED chip in a vacuum state; and
It is characterized by including.

  In the present invention, when the phosphor-containing silicone sheet is in a semi-cured state in the second step, the silicone having translucency before curing is compression-molded so as to cover the phosphor-containing silicone sheet. It is preferable to include a third step of forming a lens and simultaneously curing and bonding the phosphor-containing silicone sheet and the lens.

Below, the illustration or the preferable aspect of each element in the said means is demonstrated.
1. Substrate The substrate is not particularly limited, and may be a base substrate or a submount substrate, for example. Although it does not specifically limit as a material of a board | substrate, Ceramics, such as aluminum nitride (AlN), an alumina (Al2O3), boron nitride (BN), can be illustrated.

1. LED chip The LED chip is not particularly limited, but in the present invention, one having a peak wavelength in a blue region, a violet region or an ultraviolet region is preferred in order to excite the phosphor. Although it does not specifically limit as a semiconductor layer material of LED chip, A gallium nitride (GaN) type, a zinc oxide (ZnO) type, a zinc selenide (ZnSe) type, a silicon carbide (SiC) type etc. can be illustrated. The flip chip mounting method is not particularly limited, and examples thereof include a pressure welding method, a thermocompression bonding method, solder bonding, ultrasonic bonding, conductive paste bonding, and an ACF method.

2. 2. Phosphor-containing silicone sheet 2-1. The resin material of the resin sheet is silicone excellent in light resistance and heat resistance. Since the sheet that adheres to the LED chip is formed of silicone having a relatively large elastic coefficient, there is an advantage that stress concentration can be reduced as compared with the case where an epoxy resin having a relatively small elastic coefficient is used. Silicone includes silicone resin, silicone rubber and silicone elastomer.

2-2. Phosphor The material of the phosphor is not particularly limited, and can be appropriately selected according to the emission color of the LED chip and the emission color desired as the light emitting element.
(1) When the emission color desired as the light emitting element is white, for example, it can be selected as follows.
(A) When the emission color of the LED chip is blue, a yellow phosphor that emits fluorescence having a peak wavelength in the yellow region when excited by the blue light can be selected. This is because white is synthesized with blue and yellow. Although it does not specifically limit as yellow fluorescent substance, YAG (Yttrium Aluminum Garnet) fluorescent substance, silicate fluorescent substance, these mixtures, etc. can be illustrated.
(A) When the emission color of the LED chip is blue, a green phosphor that emits fluorescence having a peak wavelength in the green region when excited by the blue light, and a peak wavelength in the red region when similarly excited. It is possible to select a mixture of red phosphors that emit fluorescence. This is because white is synthesized by blue, green and red. Although it does not specifically limit as a green fluorescent substance, An orthosilicate type fluorescent substance can be illustrated. Although it does not specifically limit as a red fluorescent substance, A nitride type fluorescent substance can be illustrated.
(C) When the emission color of the LED chip is purple or ultraviolet, a blue phosphor that emits fluorescence having a peak wavelength in the blue region when excited by the purple light or ultraviolet light, and peaks in the green region when excited similarly. A green phosphor that emits fluorescence having a wavelength and a red phosphor that emits fluorescence having a peak wavelength in the red region when similarly excited can be selected to be mixed. This is because white is synthesized by blue, green and red. Although it does not specifically limit as a blue fluorescent substance, A halophosphate type fluorescent substance can be illustrated. Although it does not specifically limit as a green fluorescent substance, An orthosilicate type fluorescent substance can be illustrated. Although it does not specifically limit as a red fluorescent substance, A nitride type fluorescent substance can be illustrated.
(2) The phosphor material can be selected so that the non-white color is synthesized by the emission color of the LED chip and the fluorescent color of the phosphor even when the desired emission color of the light-emitting element is non-white. .

2-3. Dispersion state of phosphor The phosphor-containing silicone sheet has already been produced before entering the production method of the present invention, and therefore, the silicone mixed with the phosphor can be sufficiently kneaded. The phosphor is uniformly dispersed. The “phosphor-containing silicone sheet before curing” in the present invention has a high viscosity of silicone to such an extent that the phosphor does not settle.

2-3. Sheet thickness The thickness of the phosphor-containing silicone sheet (before adhesion processing) is not particularly limited, but is preferably 20 to 100 µm. If the thickness is less than 20 μm, the concentration of the phosphor needs to be very high, and if it exceeds 100 μm, the moldability tends to decrease.

3. Adhesion of phosphor-containing silicone sheet Adhesion of the phosphor-containing silicone sheet before curing to the upper surface and side peripheral surface of the LED chip in a vacuum state, and a vacuum state to the upper surface of the substrate around the LED chip It may be adhered with.
Although it does not specifically limit as a method of sticking the fluorescent substance containing silicone sheet before hardening to the upper surface and side peripheral surface of a LED chip in a vacuum state, The following method can be illustrated.
(A) A method in which a phosphor-containing silicone sheet is pressed against the upper surface and side peripheral surface of an LED chip with a pressing member such as a stamper or roll in a vacuum atmosphere.
(A) A suction hole is formed in the substrate in the vicinity of the LED chip, and the upper side of the substrate is vacuum-sucked from the lower side of the substrate through the suction hole, whereby the phosphor-containing silicone sheet is vacuum formed on the upper surface and side peripheral surface of the LED chip. how to.

4). The resin material of the translucent silicone lens is silicone having excellent light resistance and heat resistance. “Translucent” includes not only a material that transmits light because it is transparent, but also a material that is translucent or opaque and transmits light. Silicone includes silicone resin, silicone rubber and silicone elastomer.

  According to the first aspect of the invention, the dispersion of the phosphor can be controlled only by the phosphor-containing silicone sheet and can be stabilized, and the light emitted from the LED chip is in the immediate vicinity of the LED chip. Since the color conversion is performed and the passing / reflection distance is short, the light extraction efficiency is improved.

  According to the invention of claim 2, in addition to the above effect, two-stage sealing can be performed with high productivity by a combination of adhesion of the phosphor-containing silicone sheet and compression molding of the translucent silicone, Adhesion at the interface between the phosphor-containing silicone sheet and the translucent silicone is improved.

The manufacturing method of the light-emitting device of an Example is shown, (a) is sectional drawing which shows a 1st step, (b) (c) (d) is sectional drawing which shows a 2nd step. (E) is a cross-sectional view showing the second step following FIG. 1, (f) is a cross-sectional view of the completed light-emitting device, and (g) is a cross-sectional view of the light-emitting device with the LED chip size changed. (A) (b) It is sectional drawing which shows the example of a change of a 2nd step. A conventional example is shown, (a1) and (a2) are sectional views of a two-stage sealing type, and (b) are sectional views of a sheet covering type.

A first step of flip chip mounting the LED chip on the upper surface of the substrate;
A second step of curing the pre-curing phosphor-containing silicone sheet made of silicone containing the phosphor in a dispersed state, in close contact with the upper surface and side peripheral surface of the LED chip in a vacuum state; and
When the phosphor-containing silicone sheet is in a semi-cured state in the second step, a lens is formed by compression-molding translucent silicone before curing so as to cover the phosphor-containing silicone sheet, It is a manufacturing method of the light-emitting device including the third step of simultaneously curing and bonding the phosphor-containing silicone sheet and the lens.

Hereinafter, a method for manufacturing a light emitting device according to an embodiment of the present invention will be described in order of steps.
1. First Step As shown in FIG. 1A, the LED chip 2 is flip-chip mounted on the upper surface of the substrate 1 with bumps 3. The substrate 1 is made of, for example, AlN (illustration of a wiring pattern formed on the substrate 1 is omitted). As the LED chip 2, for example, one having a peak wavelength in a blue region is used (details of semiconductor layers, electrodes, etc. of the LED chip 2 are omitted). For the bump 3, for example, an Au—Sn alloy is used. By adopting flip chip mounting, a bonding wire that is bulky in the height direction is unnecessary, and therefore, the work of bringing the next phosphor-containing silicone sheet into close contact with the upper surface of the LED chip 2 can be performed uniformly.

2. Second Step As shown in FIGS. 1B and 1C, the uncured phosphor-containing silicone sheet 4 made of silicone 6 containing the phosphor 5 in a dispersed state is placed on the upper surface and side peripheral surface of the LED chip 2. The space is brought into close contact in a vacuum state, and the space is brought into close contact with the upper surface of the substrate 1 around the LED chip 2 in a vacuum state to be cured. As the phosphor 5, for example, a YAG phosphor that emits fluorescence having a peak wavelength in a yellow region when excited by the blue light of the LED chip 2 is used. This adhesion processing is performed by placing the phosphor-containing silicone sheet 4 on the upper surface and side peripheral surface of the LED chip 2 by a pressing member 8 such as a stamper or a roll under a vacuum atmosphere 7 schematically shown by a two-dot chain line in FIG. Pressurize. The pressure member 8 is formed with a recess 9 that is one turn larger than the LED chip, and the phosphor-containing silicone sheet 4 easily enters the side peripheral surface of the LED chip 2 by entering the recess 9. By pressurizing in a vacuum atmosphere 7 (so-called vacuum pressurization), no air remains between the phosphor-containing silicone sheet 4 and the LED chip 2, and the two adhere in a vacuum state. FIG. 1D shows a state where the pressure member 8 is removed.

3. Third Step When the phosphor-containing silicone sheet 4 is in a semi-cured state in the second step, as shown in FIG. 2 (e), the translucency before curing so as to cover the phosphor-containing silicone sheet 4 The lens 10 is compression-molded to form the lens 11, and the phosphor-containing silicone sheet 4 and the lens 11 are simultaneously cured and bonded. This compression molding is performed using a mold 12 in which a lens-shaped recess 13 is formed. FIG. 2 (f) shows a light-emitting device completed by removing the mold 12 after curing both.

According to the method for manufacturing the light emitting device of this embodiment, the following operational effects can be obtained.
(A) The dispersion of the phosphor 5 can be controlled only by the sheet 4 and can be stabilized. That is, as described above, the phosphor 5 is uniformly dispersed in the silicone 6 of the phosphor-containing silicone sheet 4, and this uniform dispersion state hardly changes in the second step and the third step. In the second step, the phosphor-containing silicone sheet 4 is slightly stretched, but the phosphor 5 is only slightly moved along with it, and there is no change in the uniform dispersion state. Further, as shown in FIG. 2 (g), even when the size of the LED chip 2 is changed, the same phosphor-containing silicone sheet 4 is used when it is not particularly necessary to change the amount of the phosphor. When it is necessary to change the amount of the phosphor, the phosphor-containing silicone sheet 4 having a changed sheet thickness or phosphor concentration may be used, and in any case, the mold needs to be changed as in the conventional case. No, it can be easily handled with only the sheet.

(A) The blue light emitted from the LED chip 2 and the yellow fluorescent light emitted by the phosphor 5 being excited by the blue light are synthesized, and white light emission is observed. In the present embodiment, the light emitted from the LED chip 2 is color-converted in the vicinity of being in close contact with the LED chip 2, and the light passing / reflecting distance is short, so that the light extraction efficiency is improved.

(C) Compared with the compression molding of the sealing material, the step of bringing the phosphor-containing silicone sheet 4 into close contact with the upper surface and side peripheral surface of the LED chip 2 in a vacuum state can be performed in a short time. For this reason, compared with the conventional type in which the two-stage sealing is performed by two compression moldings, the two-stage sealing is performed by a combination of the adhesion of the phosphor-containing silicone sheet 4 and the compression molding of the translucent silicone 10. Can be carried out with high productivity.

(D) Since the lens 11 is compression-molded when the phosphor-containing silicone sheet 4 is in a semi-cured state and the both 4 and 11 are cured at the same time, the adhesiveness between the both 4 and 11 is improved and firmly bonded.

In addition, this invention is not limited to the said Example, In the range which does not deviate from the meaning of invention, it can change suitably and can be actualized.
(1) As a second step, the method shown in FIGS. 3A and 3B is performed instead of the method shown in FIGS. That is, a suction hole 21 is formed in a portion adjacent to the bump 3 of the substrate 1 in the vicinity of the LED chip 2, and the upper side of the substrate 1 is vacuum-sucked from the lower side of the substrate 1 through the suction hole 21, whereby the phosphor-containing silicone sheet 4 is vacuum-formed on the upper surface and side peripheral surface of the LED chip 1. By providing a suction hole 21 in a portion adjacent to the bump 3 and performing vacuum suction, air does not remain between the corners of the side surface of the LED chip 2 and the substrate 1, so that the phosphor is contained in a vacuum state. The silicone sheet 4 can be adhered to the LED chip 2 and the substrate 1.

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 LED chip 3 Bump 4 Phosphor containing resin sheet 5 Phosphor 6 Silicone 7 Vacuum atmosphere 8 Pressurizing member 9 Recess 10 Silicone 11 Lens 12 Type 13 Recess 21 Suction hole

Claims (2)

A first step of flip chip mounting the LED chip on the upper surface of the substrate;
A second step of curing the pre-curing phosphor-containing silicone sheet made of silicone containing the phosphor in a dispersed state, in close contact with the upper surface and side peripheral surface of the LED chip in a vacuum state; and
A method for manufacturing a light-emitting device including:   When the phosphor-containing silicone sheet is in a semi-cured state in the second step, a lens is formed by compression-molding translucent silicone before curing so as to cover the phosphor-containing silicone sheet, The method for manufacturing a light-emitting device according to claim 1, further comprising a third step of simultaneously curing and bonding the phosphor-containing silicone sheet and the lens.

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