JP2015088657A - Composition for led lead frame coating film formation, method for forming led lead frame coating film, method for protecting lead frame, led lead frame, led package and manufacturing method thereof, and led and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a composition which enables the formation of a protective coating film of an LED lead frame which is superior in sulfur barrier property, transparency, heat resistance, resistance to light (especially resistance to UV) and adhesiveness, and has sufficient endurance; a method for forming a coating film by use of such a composition; and an LED arranged to achieve a higher luminance and to have a longer life.SOLUTION: An LED lead frame comprises a coating film of histidine formed on a lead frame including silver on its surface. The histidine coating film is formed by coating the lead frame with a liquid solution, which is prepared by dissolving the histidine in a solvent having a particular composition, and then removing the solvent. An LED and LED package each comprise a lead frame with the histidine coating film formed thereon.

Description

  The present invention relates to a lead frame coating composition for LED, a lead frame for LED, an LED package, an LED, a method for forming a lead frame coating for LED, a method for protecting a lead frame, a method for manufacturing an LED package, and a method for manufacturing an LED. About.

Metals are used as various members ranging from daily necessities to electronic parts due to their conductivity and gloss. For example, in an LED, an electrode that is silver-plated is used, and since it also functions as a reflector due to its high reflectance, the role of the silver-plated electrode for increasing the brightness and extending the life of the LED Is big.
However, when silver comes into contact with sulfur, the color changes and the reflectance decreases, so a method for suppressing deterioration due to sulfur or the like by forming a protective film on the electrode surface is also proposed for the silver-plated electrodes in LEDs. (See Patent Documents 1 to 3).

JP 2007-109915 A JP 2010-007013 A JP 2013-026427 A

  The present invention has been made in view of the above circumstances, and its purpose is excellent in sulfur barrier properties, transparency, heat resistance, light resistance (particularly UV resistance) and adhesiveness, and An object of the present invention is to provide a composition capable of forming a protective coating for LED lead frames having sufficient durability and a method for forming a coating using the composition. Another object of the present invention is to provide an LED with high brightness and long life.

  The present inventors have intensively studied to solve the above problems. As a result, by forming a histidine film on a lead frame containing silver on the surface, sulfur barrier properties, heat resistance and UV resistance are improved, and after applying a solution in which histidine is dissolved in a specific composition solvent It has been found that a histidine film having a high sulfur barrier property can be formed by removing the solvent, and the present invention has been completed.

  That is, the first gist of the present invention is a composition for forming a film on a lead frame for LED whose surface contains silver, and at least histidine is dissolved in a solvent containing a monovalent alcohol. It exists in the composition for LED lead frame film formation characterized by the above-mentioned. The second gist of the present invention resides in the composition for forming a lead frame film for LED according to the first gist, wherein the solvent is a mixed solvent of 1-butanol and water.

The third gist of the present invention is a method of forming a film on a lead frame for LED whose surface contains silver, and has at least the following three steps, and the three steps are performed in this order. The present invention resides in a method for forming an LED lead frame coating. Here, the first step is a step of preparing a histidine solution by dissolving histidine in a solvent containing a monohydric alcohol, and the second step is a step of preparing the histidine solution on the surface of the LED lead frame. The third step is a step of removing the solvent contained in the histidine solution.

  A fourth gist of the present invention resides in the method for forming a lead frame film for LED according to the third gist, wherein the solvent is a mixed solvent of 1-butanol and water. According to a fifth aspect of the present invention, there is provided an LED lead frame having a surface containing silver, wherein the histidine film is formed on the surface containing silver. Exist. The sixth aspect of the present invention resides in a method for protecting an LED lead frame containing silver on the surface, the method comprising forming a histidine film. According to a seventh aspect of the present invention, there is provided an LED package including the LED lead frame according to the fifth aspect. An eighth aspect of the present invention resides in the LED package according to the seventh aspect, which includes a silicone resin case. According to a ninth aspect of the present invention, there is provided an LED comprising the LED package according to the seventh or eighth aspect. A tenth aspect of the present invention resides in the LED according to the ninth aspect, which has a silicone resin sealing material.

  And the 11th summary of this invention is a manufacturing method of the LED package which has a lead frame by which the film is formed in the surface, Comprising: It has at least the following 3 processes and performs the said 3 processes in this order. The feature resides in a method of manufacturing an LED package. Here, the first step is a step of applying a solution in which histidine is dissolved in a solvent containing a monohydric alcohol to a lead frame containing silver on the surface, and the second step is A step of forming a histidine film on the lead frame by removing a solvent contained in the solution, and a third step is a step of forming a silicone resin case on the histidine film. is there.

  A twelfth aspect of the present invention is a method for manufacturing an LED package having a lead frame having a coating film formed on the surface thereof, comprising at least the following three steps, wherein the three steps are performed in this order: The present invention resides in an LED package manufacturing method. Here, in the first step, histidine is dissolved in a solvent containing a monohydric alcohol inside the case of the lead frame in which the surface contains silver and a silicone resin case is formed on the top. The second step is a step of forming a histidine film on the lead frame by removing the solvent contained in the solution, and the second step is a step of applying the prepared solution. In this step, the histidine coating is sealed with a silicone resin sealing material.

  A thirteenth aspect of the present invention is a method for manufacturing an LED having a lead frame having a coating film formed on the surface thereof, wherein the method includes at least the following three steps, and the three steps are performed in this order. It exists in the manufacturing method of LED. Here, the first step is a step of installing a light emitting semiconductor chip on a lead frame whose surface contains silver, and the second step is that the light emitting semiconductor chip is installed on the top. A step in which a solution in which histidine is dissolved in a solvent containing a monohydric alcohol is applied to the surface of the lead frame and the surface of the light emitting semiconductor chip, and the second step is to remove the solvent contained in the solution. This is a step of forming a histidine film on the lead frame.

According to the present invention, a film excellent in sulfur barrier property, transparency, heat resistance and light resistance (particularly UV resistance) can be formed on a metal surface on an LED lead frame by an inexpensive and simple method. . And by forming this film, it is possible to obtain an LED having high luminance and excellent durability. Moreover, the effect which improves joining strength is also anticipated by forming the film which concerns on this invention in LED. In particular, it is expected to obtain a lead frame excellent in adhesion to the case and the sealing material.

It is an example of sectional drawing of the LED package of this invention. It is an example of sectional drawing of LED of this invention.

1. Composition for forming leadframe film for LED The composition for forming a leadframe film for LED of the present invention has at least histidine dissolved in a solvent containing a monovalent alcohol. And this histidine coat | covers the surface containing the silver of a lead frame, and can form the film excellent in sulfur barrier property, transparency, heat resistance, light resistance (especially UV resistance), and adhesiveness. Histidine includes optical isomers of L-form and D-form, and either histidine according to the present invention may be used.

  The concentration of histidine in the composition for forming a lead frame coating for LED of the present invention is preferably a high concentration in that it is difficult to produce a portion where no coating is formed, but is low in terms of easily obtaining a uniform film. Is preferred. Therefore, specifically, it is preferably 0.00001% by weight or more, more preferably 0.0001% by weight or more, and on the other hand, preferably 0.02% by weight or less, More preferably, it is 0.01 weight% or less.

In the composition for forming a lead frame film for LED of the present invention, histidine is dissolved in a solvent containing a monovalent alcohol (hereinafter sometimes referred to as “monovalent alcohol according to the present invention”). As the solvent in which histidine is dissolved, a solvent that does not corrode silver and can dissolve histidine is used.
The solvent in which histidine is dissolved may be only the monohydric alcohol according to the present invention or may contain other solvents. Further, the monovalent alcohol according to the present invention may be only one type or two or more types. However, it is preferable that the solvent has the following physical properties as a whole. Moreover, it is preferable that each solvent also has the following physical properties.

  The boiling point of the solvent in which histidine is dissolved is preferably low in terms of easy removal of the solvent, but it is easy to obtain and store a composition having a uniform composition without volatilization of the solvent even in a high temperature environment. High temperature is preferred. In addition, when the LED lead frame coating composition of the present invention is applied to a metal surface using a dispenser or the like, the solvent is difficult to volatilize even if the pressure in the syringe is reduced so as not to spill from the needle tip. Also, it is preferable that the temperature is high. Specifically, the boiling point of the solvent is preferably 60 ° C. or higher, more preferably 100 ° C. or higher. On the other hand, it is preferably 250 ° C. or lower, and 190 ° C. or lower. Further preferred. Moreover, since the solvent which melt | dissolved histidine is easy to apply | coat uniformly on the metal surface, it is preferable that surface energy is low.

The solvent in which histidine is dissolved is preferably a solvent having a polarity close to that of histidine in view of the high solubility of histidine, including the monohydric alcohol according to the present invention. That is, a highly polar solvent is preferable.
The solvent in which histidine is dissolved preferably contains water from the viewpoint of easily increasing the solubility of histidine. Therefore, a solvent that is a protic solvent having high compatibility with water and that increases the solubility of histidine when mixed with water is particularly preferable.

Specific examples of the solvent for dissolving histidine include monovalent alcohols having 1 to 6 carbon atoms, amine solvents, ketone solvents, and organic solvents such as dimethyl sulfoxide. Among these, since it has a high boiling point and high compatibility with water and low reactivity with histidine, it is highly polar and protic such as 1-butanol and 1-pentanol, and has 1 to 6 carbon atoms. Monohydric alcohol is preferred, and 1-butanol is particularly preferred. That is, it is most preferable to use a mixed solvent of 1-butanol and water. The boiling point at 1 atmosphere is 117 ° C. for 1-butanol and 138 ° C. for 1-pentanol. The solubility of water in 1-butanol is 5.6% by weight.

In the case of using a mixed solvent of an organic solvent and water, the ratio of the organic solvent to water is preferably a large amount of water in that the solubility of histidine is likely to be high, but a high boiling point organic solvent is likely to be difficult to volatilize. It is preferable.
In the composition for forming a lead frame film for LED of the present invention, a component other than histidine and a solvent (hereinafter may be referred to as “other components”) unless the excellent effect of the present invention is significantly hindered. May be included. However, since it is easy to obtain a uniform film, the other components are preferably less than the amount of histidine, more preferably 70 parts by weight or less, and more preferably 50 parts by weight or less with respect to 100 parts by weight of histidine. It is particularly preferably 10 parts by weight or less, and most preferably 1 part by weight or less.

The composition for forming a lead frame film for LED of the present invention can be prepared by dissolving histidine in a solvent. When preparing the composition for forming a lead frame film for LED of the present invention, stirring or ultrasonic irradiation may be appropriately performed so that a uniform solution is easily obtained.
The coating with histidine is not limited to a solvent containing 1-butanol, but can be formed by any solvent that does not corrode silver and can dissolve histidine. That is, it is considered that a histidine LED lead frame film can be formed using a solution in which histidine is dissolved in the above-mentioned preferred physical property solvent.

2. Method for forming LED lead frame coating The LED lead frame coating forming method of the present invention is a method for forming a coating on an LED lead frame whose surface contains silver, and has at least the following three steps. Then, these three steps are performed in this order. The first step is a step of preparing a histidine solution by dissolving histidine in a solvent containing a monohydric alcohol. The second step is a step of applying this histidine solution to the surface of the LED lead frame. And the 3rd process is a process of removing a histidine solvent.
Here, the histidine solution corresponds to the above-described composition for forming a lead frame film for LED of the present invention, and the step of preparing the first histidine solution is the above-described composition for forming a lead frame film for LED of the present invention. Corresponds to the preparation of the product.

  The step of applying the second histidine solution to the surface of the LED lead frame can be performed, for example, by potting or dipping. The amount of application depends on the depth of the case in the case of potting. In the case of dipping, it can be controlled by the temperature of the liquid, the immersion time, and the like.

  In the step of removing the third solvent, when the boiling point of the solvent is low, the solvent may be naturally dried at room temperature. Further, the volatilization of the solvent may be promoted by reducing the pressure, heating, using an air stream, or the like. However, it is preferable to take care that the solvent is not removed unevenly due to the rapid solvent removal, and the formed film is not uneven. Specifically, when using an air current, it is preferable to gradually and uniformly heat the heating so that the air current does not contact a specific portion. In particular, in a high humidity environment, it is preferable to remove so as not to cause condensation. When removing the solvent in an environment where condensation is likely to occur, after replacing at least a part of the solvent according to the present invention with a solvent having a higher boiling point, the substituted solvent may be removed.

In the case of heating in the step of removing the solvent, a non-contact type radiation heater can be used. Heating may be performed at an appropriate temperature according to the boiling point of the solvent used. The heating temperature and time are preferably a high temperature and a short time from the viewpoint of work efficiency, but it is easy to obtain a uniform histidine film without causing deterioration of histidine, etc. preferable. Therefore, specifically, the heating temperature is preferably 50 ° C. or higher, more preferably 100 ° C. or higher. On the other hand, the heating temperature is preferably less than 282 ° C. (decomposition temperature of histidine at 1 atm), more preferably 230 ° C. or lower. Preferably, 170 ° C. or lower is particularly preferable, and 120 ° C. or lower is most preferable. In addition, the heating time is preferably long from the viewpoint that the amount of residual solvent tends to decrease, specifically, 30 minutes or more is preferable, and 1 hour or more is more preferable.

Industrially, the method for forming a lead frame coating for LED of the present invention can be performed as potting or screen printing on a metal surface in a case. Moreover, it can apply with a roll-to-roll system with respect to the lead frame supplied with a roll.
Note that the LED lead frame coating with histidine is not limited to the case of forming the LED lead frame coating composition of the present invention as long as a histidine coating capable of protecting the lead frame is formed. That is, for example, a histidine film may be formed by placing histidine powder on an LED lead frame containing silver on the surface and then drying by heating.

3. LED Lead Frame The LED lead frame of the present invention contains silver on the surface, and a histidine film is formed on the surface. And it is preferable to form the lead frame for LED of this invention by the formation method of the lead frame film for LED of this invention using the composition for LED lead frame film formation of the above-mentioned this invention. The LED lead frame of the present invention has a coating excellent in sulfur barrier property, transparency, heat resistance, light resistance (particularly UV resistance) and adhesiveness by covering and protecting the LED lead frame with histidine. Can be formed.

  In addition, the LED lead frame of the present invention has a silver plating layer provided on the surface of a ceramic substrate or a metal core substrate used for, for example, an LED using a ceramic package or a chip-on-board (COB) type LED. By covering the circuit pattern with histidine, sulfur barrier properties can be imparted and firmly bonded to the sealing material. Further, it is possible to impart sulfur barrier properties to the silver plating layer formed as the reflective film and improve the bonding strength with the sealing material.

As shown in the examples below, the histidine coating works effectively on silver. The effect of histidine coating on silver is manifested by the ability of histidine to form complexes of nitrogen atoms and amino acids, reduction of electron density related to reaction with sulfur by hydrogen bonding, inhibition of sulfur access by coating, and suppression of sulfur penetration rate It is thought that it is done. Therefore, the surface of the LED lead frame of the present invention is not limited to pure silver, and any metal containing a large amount of silver can exhibit a covering effect by histidine, and is a conventionally known silver alloy used as an LED lead frame. It can also be applied. And in the case of a silver alloy, when there is much content of silver, the coating effect by the histidine of this invention will appear notably.
This covering effect by histidine is not limited to LED lead frames containing silver on the surface, but is considered to be manifested in LED lead frames containing metal corroded by sulfur.

4). LED Package The LED package of the present invention has the above-described LED lead frame of the present invention.
A typical SMD type L shown in FIG.
A cross-sectional view of the structure of the ED package will be described as an example. In FIG. 1, an SMD type LED package 10 has a lead frame 11 having a silver plating layer on the surface and a case 12.
Here, the LED package of the present invention forms a histidine film on the surface of the lead frame 11 by applying a solution in which histidine is dissolved on the surface of the silver plating layer of the lead frame 11 and then removing the solvent. Yes. And it can manufacture by forming the case 12 on this histidine film.

Further, the LED package of the present invention has a histidine on the lead frame 11 by applying a solution in which histidine is dissolved to the inside of the case of the lead frame 11 having a case 12 formed on the upper portion thereof, and then removing the solvent. It is also possible to manufacture by coating the histidine film with a sealant.
In the LED package of the present invention, the case 12 is preferably made of a silicone resin that is particularly desired to have an improved sulfur barrier property compared to an epoxy resin or the like. In addition, the case 12 is preferably a silicone resin from the viewpoint of improving the adhesion of the case 12 integrated with the lead frame 11 by insert molding to the lead frame 11. The raw material of the silicone resin case 12 is usually a curable silicone composition obtained by adding an inorganic filler to an addition-curable or condensation-curable silicone binder. In addition, about the raw material of case 12, Unexamined-Japanese-Patent No. 2012-238767 etc. can also be referred.

5. LED
The LED of the present invention has the above-described LED package of the present invention.
The structure of the LED of the present invention and the manufacturing method thereof will be described with reference to a cross-sectional view of the structure of a typical SMD type LED in FIG. In FIG. 2, an SMD type LED 100 includes an SMD type LED package 10 including a lead frame 11 having a silver plating layer on the surface and a case 12, a light emitting semiconductor chip 20 mounted on the lead frame 11, and a light emitting semiconductor chip. 20 and an Au wire 30 that connects the lead frame 11 and a sealing material 40 that protects the light emitting semiconductor chip 20.

  Here, in the LED of the present invention, after the light emitting semiconductor chip 20 is installed on the lead frame 11 having the silver plating layer on the surface, both the lead frame 11 and the light emitting semiconductor chip 20 where the light emitting semiconductor chip 20 is not installed. After applying a solution in which histidine is dissolved on the surface of the lead frame 11, the solvent can be removed to form a histidine film on the surface of the lead frame 11. Furthermore, the LED having the cross-sectional structure of FIG. 2 can be manufactured by sealing the histidine film on the sealing material 40.

  In the LED of the present invention, the sealing material 40 is preferably a silicone-based resin since an improvement in sulfur barrier properties is desired as compared with an epoxy resin or the like. Further, the sealing material 40 is preferably a silicone-based resin from the viewpoint of improving the adhesion to the lead frame 11. The raw material of the silicone resin sealing material 40 is usually a curable silicone composition obtained by adding an inorganic filler or the like to an addition-curable or condensation-curable silicone oil as required. In addition, about the raw material of the sealing material 40, Unexamined-Japanese-Patent No. 2012-116991 etc. can also be referred.

The formation of the histidine film on the surface of the lead frame 11 is preferably performed before the light emitting semiconductor chip 20 is formed on the package 10 because the bondability of the lead frame 11 to the Au wire 30 is unlikely to be impaired. That is, the Au wire 30 can be bonded to the surface of the lead frame 11 on which the histidine film is formed using a normal wire bonding apparatus. Similarly, the formation of the histidine film on the surface of the lead frame 11 is unlikely to impair the solder wettability of the lead frame 11. Therefore, when the light emitting semiconductor chip 20 is formed on the package 10 in the flip chip format, the lead frame 11 is formed. A histidine coating can be formed on the lead frame 11 before the light emitting semiconductor chip 20 is joined by solder.

[material]
The materials used for preparing the composition for forming a lead frame film for LED of the present invention and the composition for a comparative example thereof are shown below.
L-histidine (purity 98% by weight) manufactured by Kishida Chemical Co., Ltd.
1,2,3-benzotriazole (purity 99% by weight) manufactured by Kishida Chemical Co., Ltd.
Water (water purified using ion exchange resin).
1-butanol (purity 99% by weight) manufactured by Mitsubishi Chemical Corporation.
1-propanol manufactured by Kishida Chemical Company.

Moreover, each member used for LED manufacture is shown below.
Lead frame with silver plating on copper plate.
SMD type LED package made by Enomoto (open frame. FLASH LED 6PIN BASE 8ROW, silver plated electrode, reflector made of polyphthalamide, case depth 0.6mm)

[Example 1]
After 0.2 g of L-histidine was added to 2850 ml of 1-butanol and dissolved by stirring, it was filtered under pressure using a filter having a pore size of 1 μm to obtain a composition for forming a lead frame film for LED. It was.
By applying 10 microliters of the LED lead frame coating composition to the SMD type LED package with a variable dispenser, and then drying for 1 hour using a dryer with forced ventilation set to 100 ° C., A transparent histidine film was formed on the lead frame.
10 microliters of silicone resin was applied to the SMD type LED package with a histidine coating formed on the lead frame using a variable dispenser, and then dried for 1 hour using a dryer with forced ventilation set at 100 ° C. Furthermore, the set temperature of the dryer with forced ventilation was raised to 150 ° C. and dried for 3 hours to form a sealing layer.

[Example 2]
Except that 1-pentanol was used instead of 1-butanol, a transparent histidine film was formed on the lead frame of the SMD type LED package in the same manner as in Example 1, and a sealing layer was formed thereon I let you.

[Comparative Examples 1-3]
Example 1 except that 1-hydroxybenzotriazole (Comparative Example 1), 1,2,3-benzotriazole (Comparative Example 2) or trimethyltriazole (Comparative Example 3) was used instead of L-histidine, respectively. In the same manner as described above, a histidine film was formed on the lead frame of the SMD type LED package, and a sealing layer was formed thereon.

[Examples 3 to 7]
Instead of adding and stirring 0.2 g of L-histidine only to 2850 ml of 1-butanol, a solution prepared by adding water to 0.2 g of L-histidine was added to 2850 ml of 1-butanol and stirred. Except for the above, a transparent histidine film was formed on the lead frame of the SMD type LED package in the same manner as in Example 1, and a sealing layer was formed thereon. The amount of water added was 15 g (Example 3), 30 g (Example 4), 60 g (Example 5), 75 g (Example 6) or 150 g (Example 7), respectively.

[Example 8]
A transparent histidine film was formed by placing 0.01 g of L-histidine powder on an SMD type LED package and heating for 10 hours using a dryer with forced ventilation set to 100 ° C. After removing the histidine powder by air blow, a sealing layer was formed in the same manner as in Example 1.

[Comparative Example 4]
A silicone resin sealing layer was formed on the SMD type LED package in the same manner as in Example 1 except that the histidine film was not formed on the lead frame.
[Evaluation method]
The sulfur barrier properties of the LED packages of Examples 1 to 8 and Comparative Examples 1 to 4 were evaluated by conducting the following sulfur atmosphere exposure test.

<Sulfur atmosphere exposure test>
The lead frame side of each LED package was attached to a slide glass having a width of 5 cm and a length of 8 cm using a double-sided tape. And this slide glass was affixed on the lid | cover of the petri dish using the cellophane tape. 1 g of sulfur powder was uniformly spread on a petri dish (diameter 12 cm, depth 1.5 cm). Then, the petri dish was covered with a lid on which a glass slide pasted with the previous LED package was affixed (the sealing material side of the LED package was opposed to the sulfur powder), and the side of the petri dish was sealed with vinyl tape. The petri dish was placed in a large petri dish (diameter 15 cm, depth 4.5 cm), covered with an upper lid of the petri dish, and its side surface was sealed with vinyl tape. After this petri dish was stored in a dryer with forced ventilation set at 90 ° C. for 30 minutes, the discolored state of the taken out LED package was visually observed.

The color of the least discolored part was evaluated. Evaluation was set to 10 when there was no discoloration at all, to 0 when discolored to the same extent as in Comparative Example 4, and to a larger number as the discoloration decreased. Moreover, the unevenness of discoloration was also evaluated. The evaluation was 3 when there was no unevenness, 0 when there was large unevenness, and a larger number as there was less unevenness.
The above evaluation results are summarized in Tables 1-3.
Moreover, the heat resistance and UV resistance of the LED packages of Examples 1 and 2 were evaluated by performing the following tests, respectively.

<Heat resistance test>
Each LED package was placed in a petri dish (diameter 2 cm, depth 1.5 cm), heated for 200 hours in a dryer set at 200 ° C., and then the discolored state of the taken out LED package was visually evaluated. In the evaluation of the discoloration state, 5 was given when there was no discoloration, 0 was given when discolored to yellow, and the smaller the discoloration, the larger the number.

<UV resistance test>
UV light was irradiated to the sealing material side of each LED package using a UV irradiation device “Icure ANUP5204” manufactured by Matsushita Electric Works & Vision. Irradiation was performed for 30 hours by blocking light with a wavelength of 350 nm or less using a light shielding filter, and setting the distance from the LED package to the optical fiber of the UV irradiation device to 2 mm including the thickness of the light shielding filter. Visual observation evaluated the discoloration state of the LED package by UV irradiation. In the evaluation of the discoloration state, 5 was given when there was no discoloration, 0 was given when discolored to yellow, and the smaller the discoloration, the larger the number.
The above evaluation results are summarized in Tables 1-3.

  From Table 1, L-histidine (Examples 1 and 2) is from 1-hydroxybenzotriazole (Comparative Example 1), 1,2,3-benzotriazole (Comparative Example 2) or trimethyltriazole (Comparative Example 3). It turned out that it becomes a film excellent in sulfur barrier property, heat resistance, and UV resistance. Also, from Table 2, the mixed solvent with water is a film having better sulfur barrier properties, heat resistance and UV resistance than 1-butanol alone, and the higher the water mixing ratio, the higher the sulfur barrier properties and heat resistance. It was also found that the coating film was excellent in UV resistance. From Table 3, it was found that a histidine film can be formed by placing histidine powder on an LED lead frame, followed by heating and drying.

[Example 9]
A thermosetting silicone was placed in a square shape with a side of 1 cm and a height of 1 mm on a silver-plated copper plate, and this was thermoset to produce a dam. 1 ml of 1-butanol aqueous solution of L-histidine prepared in the same manner as in Example 7 was applied to the inside of this dam using a variable dispenser, and then 1 using a dryer with forced ventilation set at 100 ° C. By drying for a period of time, a transparent histidine film was formed. A silicone resin was applied to the silver-plated copper plate on which the histidine film was formed, and then heat-dried to form a sealing layer.

[Comparative Example 5]
A silicone resin was applied to a silver-plated copper plate, and then heat-dried to form a sealing layer.

<Adhesion test>
After removing the square dam of Example 9, the end of the silicone resin encapsulant was picked with tweezers for stamps and pulled up in the vertical direction. Similarly, the end portion of the silicone resin sealing material of Comparative Example 5 was pinched with stamp tweezers and pulled up in the vertical direction. As a result, in Comparative Example 5, the sealing layer was peeled off at the interface, whereas in Example 9, the sealing layer was broken. Therefore, it was found that Example 9 had stronger adhesive force than Comparative Example 5. .

[Example 10]
After installing the light emitting semiconductor chip in the SMD type LED package, a transparent histidine film was formed in the same manner as in Example 7 and a sealing layer was formed thereon to produce an LED.

[Comparative Example 6]
An LED was manufactured by installing a light emitting semiconductor chip in an SMD type LED package and then forming a sealing layer thereon, in the same manner as in Example 7 except that the histidine film was not formed.

<Long-term lighting test>
The LED manufactured in Example 10 or Comparative Example 6 was continuously supplied with a current of 350 mA in each atmosphere of 55% RH at 25 ° C., 90% RH at 85 ° C. or 90% RH at 60 ° C. It was made to light continuously. The output retention rate (compared to the initial lighting) after 300 hours of continuous lighting was measured using an Ocean Optics 4 inch integrating sphere spectroscopy system (spectrometer: USB4000). As a result, Example 10 showed an output retention rate equivalent to that of Comparative Example 6, and it was found that there was no decrease in the output retention rate due to the formation of the histidine film.

<Sulfur atmosphere exposure test>
The LED manufactured in Example 10 and Comparative Example 6 was the same as the above sulfur atmosphere exposure test except that the LED was directly attached to a petri dish lid (diameter 12.5 cm, depth 1.5 cm) using a double-sided tape. Then, the sulfur atmosphere exposure test was performed, and the output maintenance rate of the extracted LED was measured using a 4-inch integrating sphere spectroscopic system (spectrometer: USB4000) manufactured by Ocean Optics. As a result, the output maintenance ratio was higher in Example 10 than in Comparative Example 6, and it was found that the luminance reduction due to sulfidation was reduced by the histidine coating, and the life of the LED could be extended even in a sulfur atmosphere.

10 SMD type LED package 11 Lead frame 12 Case 20 Light emitting semiconductor chip 20
30 Au wire 40 Sealing material 100 SMD type LED

Claims (13)

  A composition for forming a coating on a lead frame for LED, the surface of which contains silver, wherein at least histidine is dissolved in a solvent containing a monohydric alcohol. Film-forming composition.   The composition for forming a lead frame film for an LED according to claim 1, wherein the solvent is a mixed solvent of 1-butanol and water. A method for forming a film on a lead frame for LED containing silver on the surface, comprising at least the following three steps, wherein the three steps are performed in this order: Forming method.
Preparing a histidine solution by dissolving histidine in a solvent containing a monohydric alcohol;
Applying the histidine solution to the surface of the LED lead frame;
Removing the solvent contained in the histidine solution   The method for forming a lead frame film for an LED according to claim 3, wherein the solvent is a mixed solvent of 1-butanol and water.   An LED lead frame comprising silver on the surface, wherein a histidine film is formed on the silver-containing surface.   A method for protecting a lead frame for LEDs, the surface of which contains silver, comprising forming a histidine film.   An LED package comprising the LED lead frame according to claim 5.   The LED package according to claim 7, further comprising a silicone resin case.   An LED comprising the LED package according to claim 7 or 8.   The LED according to claim 9, further comprising a silicone resin sealing material. A method of manufacturing an LED package having a lead frame having a film formed on a surface thereof, comprising at least the following three steps, wherein the three steps are performed in this order.
Applying a solution in which histidine is dissolved in a solvent containing monovalent alcohol to a lead frame containing silver on the surface;
Forming a histidine film on the lead frame by removing the solvent contained in the solution;
Forming a silicone resin case on the histidine coating A manufacturing method of an LED package having a lead frame having a film formed on a surface thereof, comprising at least the following three steps, wherein the three steps are performed in this order.
A step of applying a solution in which histidine is dissolved in a solvent containing a monovalent alcohol to the inside of the case of the lead frame, the surface of which includes silver and a silicone resin case is formed on the top;
Forming a histidine film on the lead frame by removing the solvent contained in the solution;
Sealing the histidine coating with a silicone resin sealant A method for manufacturing an LED having a lead frame having a film formed on a surface thereof, comprising at least the following three steps, wherein the three steps are performed in this order.
Installing a light emitting semiconductor chip on a lead frame containing silver on the surface;
Applying a solution in which histidine is dissolved in a solvent containing monovalent alcohol to the surface of the lead frame on which the light emitting semiconductor chip is not placed and the surface of the light emitting semiconductor chip;
Forming a histidine film on the lead frame by removing the solvent contained in the solution;

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