JP2009224536A - Led device and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problem: although a surface-mounted LED device is frequently used which has silver plating with high reflectivity on a wiring conductor portion surface irradiated with LED emitted light so as to have conductivity and reflection characteristics on a surface where an LED is mounted, the surface-mounted LED device does not have satisfactory stabilities of luminance and chromaticity due to discoloration of silver and does not have satisfactory longer life while a white LED device for lighting using an LED chip having a short wavelength and high luminance is desirable. <P>SOLUTION: A step of manufacturing an ordinary LED device includes a step of applying a SiO<SB>2</SB>coating liquid onto a base material and carrying out a heat treatment after an LED chip is mounted on the base material and wired. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an LED device on which an LED chip is surface-mounted.

  By developing LED chips that emit blue light or near ultraviolet light in the short wavelength range, LED devices that combine these LED chips with phosphors that absorb the light emission wavelength of LED chips and convert them into light in different wavelength ranges have been developed. Has been. Among them, a pseudo white LED device combining a blue LED chip and a YAG silver phosphor is widely used as an illumination light source or a liquid crystal display backlight source. Particularly, in general LED light sources for illumination, high brightness and long life are important problems.

  In general, as a substrate of an LED device on which an LED chip is surface-mounted, a molded body in which a lead frame material and a resin are integrally formed by injection molding, a flexible wiring substrate, a ceramic substrate having a wiring pattern, and the like are used. For LED chip mounting and wiring, wire bonding mounting or flip chip mounting is generally used depending on the chip type.

  FIG. 8 shows an example of a general LED device having a surface mounted LED chip.

  Reference numeral 1 denotes an insulating substrate, which is made of a highly heat-resistant insulating resin or ceramic. 2 is an LED chip. The LED chip 2 is electrically joined to the LED chip mounting wiring part 3. Reference numeral 4 denotes a wiring conductor portion. In FIG. 8, the LED chip 2 is mounted on the LED chip mounting wiring portion 3 with a die bond paste or silver paste made of epoxy resin, silicone resin, or the like, and also serves as a wiring conductor portion through a bonding wire 5 made of gold, aluminum, or the like. It is electrically joined to the chip mounting wiring part 3. When a copper-clad flexible substrate is used as a base material having the LED chip mounting wiring part 3 and the wiring conductor part 4, the wiring conductor part 4 is formed by patterning copper by chemical etching or the like. However, since copper is easily oxidized, an overcoat layer is generally provided. In FIG. 8, the copper of the conductor wiring portion 4 on the surface on which the LED chip 2 is disposed is covered with an insulating resist 6, and the LED chip mounting wiring portion 3 is nickel-plated on the copper, and the reflectance of the copper is mounted thereon. High silver plating. The wiring conductor 4 that is not covered with the insulating resist 6 except for the LED chip mounting wiring 3 is nickel-plated on copper and gold-plated or tin-plated on the copper for connection to an external electrode.

In the case of a white LED device that requires white light emission, it is particularly necessary to arrange a material that efficiently reflects light emitted from the LED chip around the LED chip.
Thus, as shown in FIG. 8, the surface of the LED chip mounting wiring part on which the LED is mounted is often subjected to silver plating having a high reflectivity so as to have both functions of the reflector and the wiring conductor part.

  However, silver is a thermally and chemically unstable substance, and its reflectance is reduced due to heat generation of LED chips or gas containing sulfur in the atmosphere, etc., so silver is used for LED chip mounting wiring parts. The LED device had problems with respect to stability of luminance and chromaticity and long life.

As one method of LED device structure with high brightness and long life, Patent Document 1 separates a light reflecting portion and a wiring conductor portion and provides a transparent inorganic oxide film layer on a reflecting plate by a vacuum thin film forming method. A wiring conductor portion is formed on the substrate.
Japanese Patent Laying-Open No. 2005-244152 (page 12, FIG. 3)

  However, in the case of the LED device as in the above-mentioned Patent Document 1, when all of the wiring conductor part, the inorganic oxide film layer, and the light reflection part are formed by the vacuum thin film forming method, It is difficult to form all the parts in one process, and there is a problem that the process becomes complicated.

  Further, when a vacuum thin film forming method using a mask is used, the normal mask accuracy is about 100 microns. Therefore, an LED device in which films having different patterns as described in Patent Document 1 are stacked is a small LED device. It is thought that application to is difficult.

  Therefore, an object of the present invention is to provide a high-luminance and long-life LED device that can be reduced in size with fewer steps.

The LED device of the present invention is an LED device in which an LED chip is mounted on a substrate having an LED chip mounting wiring portion and a wiring conductor portion, and the LED chip mounting wiring portion has a SiO ₂ film. To do.

The LED device manufacturing method of the present invention is a method of manufacturing an LED device in which an LED chip is mounted on a substrate having an LED chip mounting wiring portion and a wiring conductor portion, and the LED chip is mounted on the substrate. It includes a step of mounting and wiring, a step of applying a SiO ₂ coating solution on a substrate on which an LED chip is mounted, and a step of heat-treating the substrate on which the SiO ₂ coating solution is applied. Is.

Furthermore, the SiO ₂ coating liquid used in the LED device manufacturing method of the present invention is a polysilazane solution that is a SiO ₂ precursor, and it is preferable to form a SiO ₂ film by performing a heat treatment after coating.

Incidentally, SiO ₂ coating solution used in the production method of the LED device of the present invention is preferably applied by a dispenser or an ink-jet method.

In the method of manufacturing the LED device of the present invention is preferably subjected to plasma cleaning or UV- ozone cleaning the substrate which is mounted an LED chip as a pretreatment for applying a SiO ₂ coating solution.

(Function)
In the LED device of the present invention, the silver surface is covered with a SiO ₂ coating film formed by applying a heat treatment after applying a polysilazane solution. It is thought that the discoloration of is suppressed.

The sol-gel method, which is generally known as a method for forming a SiO ₂ coating film by applying a heat treatment after coating, combines the sol-gel solution used with the reactions shown in (Formula 1) to (Formula 3). It is supposed to be _two films.
Si (OR) ₄ + xH ₂ O → Si (OH) _x (OR) _4-x +
ROH (Formula 1)
-Si-OR + HO-Si- → -Si-O-Si- + H 2 O ··· ( Equation 2)
-Si-OR + HO-Si- → -Si-O-Si- + ROH (Formula 3)

  However, the reaction mechanism of the sol-gel method is that it undergoes hydrolysis, dehydration reaction, and dealcoholization reaction, so that the film shrinkage accompanying the progress of the reaction by heat treatment is large, so the adhesion to the coated member is low, and cracks Etc. will occur.

On the other hand, the reaction of the polysilazane solution used in the present invention is represented by (Equation 4), and the weight yield associated with this reaction is 133%. Therefore, it is considered that a stable coating film without cracks or the like is formed.
_{-SiH 2 NH- + 2H 2 O →} SiO 2 + NH 3 + 2H 2 ··· ( Equation 4)

Furthermore, by applying a plasma cleaning process or a UV-ozone cleaning process to the coated part as a pretreatment for applying the polysilazane solution, an SiO ₂ film with high adhesion can be obtained by removing impurities on the outermost surface of the coated part. It is thought that

  According to the present invention, it is possible to provide an LED device having high luminance and long life characteristics by simple post-processing without greatly changing the manufacturing process of the conventional LED device.

  Furthermore, the LED device according to the present invention can use general materials and methods such as a base material to be used, an LED chip, a wiring material and a wiring system for electrically connecting the LED chip and the wiring conductor, and a wiring conductor. Therefore, it is possible to contribute to cost reduction and miniaturization of LED devices having high luminance and long life characteristics.

(First embodiment)
The LED device which is 1st embodiment of this invention is shown in FIG. 1, and the manufacturing method is demonstrated based on FIG.

  Reference numeral 1 denotes an insulating base material having an LED chip mounting wiring portion 3 and a wiring conductor portion 4. As the insulating substrate 1, a high heat-resistant glass epoxy resin, BT resin (bismaleimide triazine), PBT resin (polybutylene terephthalate), hard silicone resin, ceramics, or the like is used.

  2 is an LED chip. A typical LED chip is an InGaN-based LED chip, and emits near-ultraviolet light, blue light, and green light depending on the composition ratio.

  As a mounting method of the LED chip 2, when an n-type electrode pad and a p-type electrode pad are provided on the upper surface of the LED chip 2, a die bond paste made of epoxy resin, silicone resin or the like on the LED chip mounting wiring portion 3. Then, the LED chip 2 is mounted using silver paste, and then both the electrode pads and the LED chip mounting wiring part 3 are bonded and mounted with a bonding wire such as gold or aluminum. In the case of the LED chip 2 provided with an n-type electrode pad and a p-type electrode pad on the upper and lower surfaces, respectively, the upper electrode pad is mounted with a bonding wire, and the lower electrode pad is mounted with a conductive paste such as silver paste. The When the n-type electrode pad and the p-type electrode pad are arranged on the lower surface of the LED chip 2, the LED chip 2 is mounted by flip chip mounting or the like. In the first embodiment, an example in which both electrode pads are provided on the upper surface of the LED chip 2 is shown.

When a copper-clad flexible substrate using epoxy resin or BT resin is used as the insulating substrate 1 having the LED chip mounting wiring portion 3 and the wiring conductor portion 4, the wiring conductor portion 4 is formed by patterning copper by chemical etching or the like. However, since copper is easily oxidized, an overcoat layer made of metal or resin is generally provided. Most of the insulating resist 6 used as the overcoat layer is a liquid photo solder resist composed of an epoxy acrylate resin and a filler, and a desired pattern can be formed by coating, baking, developing and curing.

In the first embodiment, a copper-coated glass epoxy substrate is used, and the LED chip mounting wiring section 3 has nickel plating on copper, silver plating thereon, and further a SiO ₂ film on the silver plating surface. . Nickel plating functions as a copper overcoat layer. The silver plating not only has a function as a wiring conductor, but also has a function of a reflecting plate that reflects light in all directions emitted from the LED chip.

The wiring conductor 4 that is not covered with the insulating resist 6 except for the LED chip mounting wiring 3 is nickel-plated on copper and gold-plated or tin-plated on the copper for connection to an external electrode.
The reflection frame 12 has a shape and a reflection characteristic that gives directivity to light in all directions emitted from the LED chip, and includes a metal, ceramic, or a hard silicone resin mixed with a white filler, a heat resistant resin such as a liquid crystal polymer, Those having a surface plated with metal are used.

  The sealing resin 13 is made of a transparent silicone resin, epoxy resin, or the like. One of the roles of the sealing resin 13 is to protect the mounted LED chip 2 from mechanical shock. Moreover, the uniformity of the light emitted from the LED chip 2 can be improved by dispersing a transparent scattering material in the sealing resin 13. Further, by dispersing phosphors that absorb light emitted from the LED chip 2 and emit light of different wavelengths in the sealing resin 13, it is possible to obtain light in which the emission wavelengths from the LED chip 2 and the phosphor are mixed. . A pseudo white LED device using a blue LED as the LED chip 2 and a YAG silver phosphor that absorbs blue light and emits yellow light as a phosphor is widely known.

Next, a method for manufacturing the LED device of FIG. 1 will be described with reference to FIG.
FIG. 2A shows a state in which the LED chip 2 is mounted on the LED chip mounting wiring section 3. FIG. 2B shows a state in which the SiO ₂ coating liquid 10 is dropped on the LED chip mounting wiring part 3 after plasma cleaning of the mounting substrate of the LED chip 2. The application of the SiO ₂ coating solution 10 can be performed using a dispenser or an ink jet device. FIG. 2C shows a shape in which the SiO ₂ film 11 is formed on the silver plating surface by applying a heat treatment after applying the SiO ₂ coating solution 10 and the LED chip 2 is surrounded on the insulating resist 6 of the substrate. This shows a state in which the reflection frame 12 is arranged. FIG. 2D shows the LED device according to the first embodiment of the present invention in which the reflective resin 12 is filled with the sealing resin 13 so as to cover the LED chip 2.

In the case of the LED device according to the first embodiment of the present invention, the step of applying the SiO ₂ coating solution 10 may be performed after the reflective frame 12 is arranged on the substrate on which the LED chip 2 is mounted.

  The LED device according to the first embodiment of the present invention shown in FIGS. 1 and 2 is an example in which the reflecting frame 12 is filled with the sealing resin 13, but LED devices of other shapes are also present. Included in embodiments of the invention.

In the LED device according to the first embodiment of the present invention shown in FIG. 3, the sealing resin 13 is arranged so as to cover the LED chip on the LED mounting wiring portion 3, and the sealing resin 13 and the reflection frame 12 do not contact each other. LED device of the form. In the LED device of such a form, there is a high risk that the LED chip mounting wiring part 3 not covered with the sealing resin 13 is directly exposed to the atmosphere and contaminated. However, the LED device of the present invention can solve these problems by having the SiO ₂ film 11 on the LED chip mounting wiring portion 3.

The LED device according to the first embodiment of the present invention shown in FIG. 4 is an LED device without the reflection frame 12. As described above, there is a purpose to protect the LED chip 2 mounted as one of the functions of the sealing resin 13 from mechanical shock. However, the wiring breakage due to the ambient temperature or the temperature change between lighting and non-lighting. Therefore, the sealing resin 13 often uses a relatively soft rubber-like resin. Since soft resin inevitably has high gas permeability, in the case of an LED device whose side is not surrounded by a reflection frame made of hard resin, metal, ceramics, or the like, contamination by gas becomes a problem. However, the LED device of the present invention has the SiO ₂ film 11 on the LED chip mounting wiring part 3 and can solve these problems while using a conventional sealing resin.

Next, FIG. 5 shows an example of a test substrate for examining the heat resistance of the silver surface and the resistance to hydrogen sulfide gas (sulfurization resistance) by the coating type SiO ₂ film. 5A is a plan view, and FIG. 5B is a cross-sectional view when the test substrate is cut along AA ′. A copper plating layer and a nickel plating layer were formed on the copper-bonded glass epoxy substrate 7, and the portions other than the evaluation portion 8 were covered with an insulating resist 9. The evaluation unit 8 formed a silver plating layer on the nickel plating layer. The area of the evaluation unit 8 is 49 mm ² (7 mm × 7 mm), which is a model of the LED chip mounting wiring unit in the LED device of the embodiment of the present invention.

Example 1
Plasma cleaning of the test substrate was performed with a plasma cleaning apparatus PC-300 (manufactured by Samco Corporation). The treatment conditions were RIE mode (reactive ion etching) using argon gas, and the treatment time was 4 minutes.

  After washing the substrate, 0.3 μL of NP110 (manufactured by AZ Electronic Materials Co., Ltd.), which is a polysilazane solution, was dropped on the evaluation unit 8 with a volumetric dispenser, and heat-treated for 1 hour at a constant temperature bath at 150 ° C.

The obtained test substrate on which the SiO ₂ film was applied and the untreated test substrate were left in 100 ppm-hydrogen sulfide gas at 25 ° C. for 5 hours to conduct a sulfurization test.

FIG. 6 shows the change in reflectance at 450 nm in the evaluation part before and after the sulfidation test with and without the SiO ₂ film. Here, the reason why 450 nm was selected as the measurement wavelength in the reflectance measurement is that silver has a particularly low reflectance in the short wavelength region due to discoloration.
From the results of FIG. 6, it can be seen that the initial reflectance of the evaluation part of the test substrate on which the SiO ₂ film is applied is lower than that of the evaluation part of the untreated test substrate, but no discoloration due to hydrogen sulfide gas occurs. .

(Example 2)
A heat resistance test at 160 ° C. in the atmosphere was performed using the test substrate on which the SiO ₂ film prepared in Example 1 was applied and an untreated test substrate.

FIG. 7 shows the 450 nm reflectivity change in the evaluation part before and after the heat resistance test with and without the SiO ₂ film.
From the results of FIG. 7, it can be seen that although the initial reflectance of the evaluation part of the test substrate on which the SiO ₂ film was applied is lower than that of the evaluation part of the untreated test substrate, no discoloration due to heat has occurred.

It is known that silver grows and discolors due to heat and light. However, silver is oxidized not only by grain growth of silver alone but also by reaction with atmospheric gas and impurities in plating, and these reactions occur. It is said that discoloration due to silver particles generated when an object is re-reduced to silver by heat or light can occur.
The SiO ₂ film of the LED device of the present invention is considered to suppress not only the growth of silver particles themselves but also the re-reduction reaction from silver reactants to silver.

In addition, when conducting a heat resistance test of the test substrate with the SiO ₂ film, the presence or absence of the pretreatment plasma cleaning was examined, and cracks occurred in the SiO ₂ film in the test substrate not subjected to the plasma treatment. There were some samples that had been partially peeled off, but the test substrate that had been subjected to plasma treatment had almost no such occurrence. From this result, it can be seen that it is preferable to provide a cleaning step for cleaning the silver surface and improving adhesion as a pretreatment for forming the SiO ₂ film.

As described above, the LED device and the LED device manufacturing method of the present invention can be manufactured without greatly changing the manufacturing process of the conventional LED device by providing a SiO ₂ film on the silver surface by a simple method. In addition, the present invention provides a high-brightness, long-life LED device that does not cause a decrease in reflectance of the silver surface over time, and a method for manufacturing the LED device.

It is sectional drawing of the LED device of 1st embodiment of this invention. It is sectional drawing which shows the manufacturing process of the LED device of 1st embodiment of this invention. It is sectional drawing of the LED device of 1st embodiment of this invention. It is sectional drawing of the LED device of 1st embodiment of this invention. It is a figure of the test board | substrate in the Example of this invention. It is a figure which shows the result of the sulfide test in Example 1 of this invention. It is a figure which shows the result of the heat test in Example 2 of this invention. It is sectional drawing of a common LED device.

Explanation of symbols

1 insulating substrate 2 LED chip 3 LED chip mounting wiring portion 4 wiring conductor portion 5 bonding wire 6 insulating resist 7 copper-clad glass epoxy substrate 8 evaluation unit 9 insulating resist 10 SiO ₂ coating solution 11 SiO ₂ film 12 reflecting frame 13 Sealing resin

Claims (5)

An LED device in which an LED chip is mounted on a substrate having an LED chip mounting wiring portion and a wiring conductor portion, and the LED chip mounting wiring portion has an SiO ₂ film. An LED device manufacturing method in which an LED chip is mounted on a base material having an LED chip mounting wiring portion and a wiring conductor portion, the step of mounting and wiring the LED chip on the base material, and the LED A method for manufacturing an LED device, comprising: applying a SiO ₂ coating liquid on a substrate on which a chip is mounted; and heat treating the substrate on which the SiO ₂ coating liquid is applied. _{3. The} method of manufacturing an LED device according to claim 2, wherein the SiO ₂ coating liquid is a polysilazane solution that is a SiO ₂ precursor, and a SiO ₂ film is formed by performing a heat treatment after coating. The method for manufacturing an LED device according to claim 2 or 3, wherein the SiO ₂ coating solution is applied by a dispenser or an ink jet method.
The plasma cleaning or the UV-ozone cleaning is performed on the base material on which the LED chip is mounted as a pretreatment for applying the SiO ₂ coating liquid. LED device manufacturing method.

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