JP2011082420A - Light emitting diode and method of manufacturing the same - Google Patents

Abstract

To provide a light emitting diode capable of preventing the occurrence of thermal degradation of an LED chip without causing an increase in cost due to an increase in the number of parts and the number of processing steps.
An LED chip 6 is mounted at the tip of the lead wires 2 and 3 of a glass tube mount 4 having a hollow structure through which the upper ends of a pair of lead wires 2 and 3 are inserted, and a glass tube with the upper ends closed. A glass bulb 5 is formed by fusing the periphery of the lower surface opening and the lower surface opening of the glass tube mount 4, and the LED chip 6 and the glass tube mount 4 are hermetically sealed by the glass bulb 5. Thus, the light emitting diode 1 is configured.
[Selection] Figure 1

Description

  The present invention relates to a light emitting diode hermetically sealed by a glass bulb and a method for manufacturing the same.

  A light emitting diode (LED) is known in which an LED chip is hermetically sealed with a glass bulb for the purpose of ensuring high moisture resistance. The light emitting diode has an LED chip connected and fixed to the tip portion of the first lead wire for mounting the LED chip by die bonding (D / B), and is electrically connected to one electrode of the LED chip and the first lead wire. The other electrode of the LED chip and the tip of the second lead wire are electrically connected by a bonding wire (wire bonding (W / B)), and the LED chip is connected to the first and second lead wires. The upper end is hermetically sealed with a glass bulb.

  Such a light-emitting diode is manufactured by the following method.

  That is, after the LED chip is connected and fixed to the tip of the first lead wire by die bonding using Ag paste or the like, the tip of the second lead wire and the LED chip are connected by a bonding wire.

  Next, a glass bead is formed by adhering molten glass to the middle part of the first and second lead wires, and the LED chip and the glass first from the lower surface opening of the glass tube whose upper end forming a dome shape is closed. And the upper end part of a 2nd lead wire is inserted in a glass tube from below with a glass bead.

  Next, when a portion corresponding to the glass beads on the surface of the glass tube is heated and melted by a burner and the glass tube and the glass beads are fused, the lower surface opening of the glass tube is hermetically sealed, and the glass bulb is The LED chip and the upper ends of the first and second lead wires are sealed with a glass bulb. Finally, if a surplus portion other than the glass bulb of the glass tube is cut away, a desired light emitting diode can be obtained.

  By the way, the heat-resistant temperature of the LED chip is generally about 280 ° C. to 350 ° C., and if the LED chip is heated even at a short time at this heat-resistant temperature-filled temperature, there is a high possibility that the LED chip is thermally deteriorated. .

  Therefore, in the manufacturing method of the light emitting diode, the heating temperature when forming the glass bulb by fusing the glass tube and the glass beads is about 800 ° C. to 1000 ° C., and the heat at that time passes through the first lead wire. Depending on the heating time, the temperature of the LED chip rises to about 600 ° C. to 700 ° C., which is higher than the heat resistance temperature, and the LED chip may be thermally deteriorated.

  Therefore, Patent Document 1 proposes a light emitting diode as shown in FIG.

  That is, FIG. 11 is a schematic cross-sectional view of a light-emitting diode proposed in Patent Document 1, and the light-emitting diode 101 shown in FIG. The first and second lead wires 104 and 105 are inserted into a pair of holes 102a and 102b formed in the substrate 102, and the substrate of these first and second lead wires 104 and 105 is inserted. A configuration is adopted in which a tip portion protruding from 102 is bent at a substantially right angle, and the bent portion is connected to conductor patterns 106 and 107 formed on the substrate 102 by weighting and heating, respectively. The upper ends of the substrate 102, the LED chip 103, and the first and second lead wires 104 and 105 are hermetically sealed by a glass bulb 108.

  According to such a light emitting diode 101, conduction to the LED chip 103 of heat generated when the glass bulb 108 is formed by melting and sealing the opening of the glass tube in the manufacturing process is suppressed by the heat insulating effect by the substrate 102. Therefore, the occurrence of thermal degradation of the LED chip 103 is prevented.

JP 2005-108936 A

  However, in the light-emitting diode 101 shown in FIG. 11 proposed in Patent Document 1, the substrate 102 made of ceramic, glass, or the like, or conductor patterns 106 and 107 made of a conductive material such as gold are required, and the substrate 102 In addition, it is necessary to process the holes 102a and 102b through which the first and second lead wires 104 and 105 are passed, resulting in an increase in the number of parts and the number of processing steps, leading to a cost increase.

  The present invention has been made in view of the above circumstances, and a target process thereof is a light-emitting diode capable of preventing the occurrence of thermal deterioration of an LED chip without incurring a cost increase accompanying an increase in the number of parts and processing steps. And a manufacturing method thereof.

  In order to achieve the above object, a light emitting diode according to claim 1 is configured such that an LED chip is mounted on the tip of the lead wire of a glass tube mount having a hollow structure through which the top ends of a pair of lead wires are inserted, and the top ends are closed. A glass bulb is formed by fusing the periphery of the lower surface opening of the glass tube and the periphery of the lower surface opening of the glass tube mount, and the LED chip and the glass tube mount are hermetically sealed by the glass bulb. It is characterized by being configured.

  According to a second aspect of the present invention, in the first aspect of the present invention, the glass tube mount is constituted by a flare tube whose lower surface opening periphery extends radially outward.

  According to a third aspect of the present invention, in the first aspect of the present invention, the glass tube mount is constituted by straight tubes having the same diameter.

The method for producing a light emitting diode according to claim 4 comprises:
A step of melting and fixing a glass bead at the tip of a pair of lead wires, and fusing the upper end opening of a cylindrical first glass tube to the glass bead to obtain a glass tube mount having a hollow structure;
Mounting an LED chip on the tip of the lead wire of the glass tube mount;
The glass tube mount is inserted into the second glass tube together with the LED chip from the lower surface opening of the second glass tube whose upper end is closed, and the periphery of the lower surface opening of the glass tube mount is temporarily fixed to the second glass tube. And a process of
Forming a glass bulb by heating a portion of the second glass tube where the glass tube mount is temporarily fixed and fusing the second glass tube and the peripheral edge of the lower surface opening of the glass tube mount; ,
Cutting the glass bulb;
A light emitting diode is obtained through the process.

  The invention according to claim 5 is the invention according to claim 4, wherein the step of obtaining the glass tube mount having the hollow structure includes a pinch sealing step of pinching the upper end opening of the glass tube mount in a molten state. And

  According to the light emitting diode and the method for manufacturing the same according to the present invention, the glass bulb is formed in the process of forming the glass bulb by fusing the lower surface opening periphery of the glass tube whose upper end is closed and the lower surface opening periphery of the glass tube mount. The heat to be transmitted does not directly conduct to the lead wire, and the lead wire is inserted and held in the glass tube mount having low thermal conductivity, so that the heat to the LED chip mounted at the tip of the lead wire is The conduction is suppressed, and the LED chip is not heated above its heat-resistant temperature, and the occurrence of the thermal deterioration is surely prevented.

  In the light emitting diode according to the present invention, the glass tube mount and the glass bulb form a double tube structure. A vacuum layer with high heat insulating properties can be easily formed between the two. Moreover, since the heat transfer distance from the glass tube mount to the LED chip is also relatively long, heat conduction to the LED chip is suppressed, and the occurrence of thermal deterioration of the LED chip can be prevented more reliably.

  In addition, when an inert gas is sealed between the glass tube mount and the glass bulb so that the LED chip is not heated above the heat-resistant temperature as a double tube structure, heat generated when the LED chip is turned on is dissipated, and the LED The occurrence of thermal degradation of the chip can be suppressed. Furthermore, high moisture resistance is ensured, deterioration of the mold resin due to short wavelength light emitted by sunlight or LED chips can be suppressed, and a highly reliable light emitting diode can be obtained.

  In addition, the light emitting diode according to the present invention does not require a substrate or conductor pattern for mounting an LED chip, and does not require drilling or the like in the substrate, thereby reducing the number of parts and the number of processing steps. Cost reduction is achieved.

It is a longitudinal cross-sectional view of the light emitting diode which concerns on Embodiment 1 of this invention. (A)-(d) is explanatory drawing which shows the process of obtaining a glass tube mount in the manufacturing method of the light emitting diode which concerns on Embodiment 1 of this invention. (A)-(d) is explanatory drawing which shows the process after obtaining the glass tube mount in the manufacturing method of the light emitting diode which concerns on Embodiment 1 of this invention. It is a longitudinal cross-sectional view of the light emitting diode which concerns on Embodiment 2 of this invention. (A)-(d) is explanatory drawing which shows the process of obtaining a glass tube mount in the manufacturing method of the light emitting diode which concerns on Embodiment 2 of this invention. (A)-(d) is explanatory drawing which shows the process after obtaining the glass tube mount in the manufacturing method of the light emitting diode which concerns on Embodiment 2 of this invention. It is a longitudinal cross-sectional view of the light emitting diode which concerns on Embodiment 3 of this invention. (A)-(e) is explanatory drawing which shows the process of obtaining a glass tube mount in the manufacturing method of the light emitting diode which concerns on Embodiment 3 of this invention. It is a longitudinal cross-sectional view of the light emitting diode which concerns on Embodiment 4 of this invention. (A)-(e) is explanatory drawing which shows the process of obtaining a glass tube mount in the manufacturing method of the light emitting diode which concerns on Embodiment 4 of this invention. It is a schematic sectional drawing of the light emitting diode proposed in patent document 1. FIG.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1>
FIG. 1 is a longitudinal sectional view of a light emitting diode according to Embodiment 1 of the present invention. The illustrated light emitting diode 1 includes a glass tube mount 4 having a hollow structure through which upper ends of a pair of lead wires 2 and 3 are inserted; The glass tube mount 4 is configured as a double tube structure with a glass bulb 5 that covers and seals the glass tube mount 4 from the outside.

  The glass tube mount 4 is configured such that a pair of the lead wires 2 and 3 are vertically passed through the thick upper end portion 4a from below, and a tip projecting upward from the upper end portion 4a of one lead wire 2 The part is bent at a substantially right angle. An LED chip 6 is mounted with an adhesive on a bent portion 2a of the lead wire 2 that is bent at a substantially right angle, and one LED electrode (not shown) of the LED chip 6, the lead wire 2 and the other not shown (not shown). These electrodes and the lead wire 3 are electrically connected to each other by bonding wires 7 and 8, respectively. The glass tube mount 4 has an upper end opening portion of a flare tube (first glass tube) 9 (see FIG. 2C) whose peripheral edge of the lower surface opening extends in a trumpet shape outward in the radial direction as will be described later. The glass beads 10 are welded to each other.

  On the other hand, the glass bulb 5 has a lower end opening portion of the flare tube 9 constituting the glass tube mount 4 and a peripheral edge of the lower surface opening portion of the glass tube 11 (see FIG. 3B) whose upper end is closed in a dome shape. The LED chip 6 and the glass tube mount 4 are hermetically sealed by the glass bulb 5. The inside of the glass bulb 5 is evacuated and kept in a vacuum state before sealing, or an inert gas is sealed after evacuation. .

  Thus, in the light emitting diode 1 configured as described above, when a voltage is applied to the LED chip 6 via the lead wires 2 and 3 and the bonding wires 7 and 8, the LED chip 6 emits light, Light passes through the glass bulb 5 and is emitted to the outside.

  Next, a method for manufacturing the light-emitting diode 1 having the above configuration will be described with reference to FIGS.

  FIGS. 2A to 2D are explanatory views showing a method for obtaining a glass tube mount in the order of the steps, and FIGS. 3A to 3D are explanations showing a manufacturing method after obtaining the glass tube mount in the order of the steps. FIG.

  In the method of the present invention, first, the glass tube mount 4 is manufactured through the steps shown in FIGS. That is, as shown in FIG. 2A, the leading end of one of the pair of lead wires 2 and 3 is bent at a substantially right angle to form a bent portion 2a (lead forming), and FIG. ), The glass beads 10 are passed through the leading ends of both the lead wires 2 and 3, and the glass beads 10 are heated from both sides by the two burners 12 to melt them, and the lead wires 2 and 3 are bound together. (With beads).

  Next, as shown in FIG. 2 (c), the flare tube 9 is passed through the glass bead 10, the glass bead 10 is fitted into the inner periphery of the upper end, and the outer periphery of the flare tube 9 is rotated while rotating the two burners 12. The glass tube mount 4 as shown in FIG. 2 (d) is obtained by heating from the side and fusing them together (attaching a flare tube).

  When the glass tube mount 4 is obtained through the above steps, the LED chip 6 (not shown in FIG. 3A) is attached to the lead wires 2 and 3 of the glass tube mount 4 as shown in FIG. After mounting, the glass tube mount 4 is inserted together with the LED chip 6 from the lower surface opening of the glass tube 11 whose upper end is closed in a dome shape as shown in FIG. Then, while heating an appropriate portion of the glass tube 11 with a burner, the disk-shaped squeezing cutter 13 is pressed to the portion to temporarily fix the glass tube mount 4 to the glass tube 11.

  Next, as shown in FIG. 3C, the posture of the glass tube 11 and the glass tube mount 4 temporarily fixed thereto is returned vertically, and the two burners 12 are rotated while the inside of the glass tube 11 is exhausted. The glass bulb 5 in which the lower surface opening is closed is formed by fusing the lower end opening periphery of the glass tube 11 and the lower surface opening periphery of the glass tube mount 4 by heating and melting the temporary fixing portion. The glass tube mount 4 and the LED chip 6 are hermetically sealed by the glass bulb 5.

  Finally, as shown in FIG. 3D, the glass bulb 5 is cut and cut out from the glass tube 11 to obtain the light emitting diode 1 shown in FIG.

  Thus, according to the light-emitting diode 1 obtained by the above method, the glass bulb 5 is fused by fusing the periphery of the lower surface opening of the glass tube 11 closed at the upper end with the periphery of the lower surface opening of the glass tube mount 4. The heat generated in the process of forming the lead wire 2 and 3 is not directly conducted to the lead wires 2 and 3, and the lead wires 2 and 3 are inserted and held in the glass tube mount 4 having low thermal conductivity. Heat conduction to the LED chip 6 mounted at the tip of the wires 2 and 3 is suppressed, and the LED chip 6 is not heated above its heat-resistant temperature, and the occurrence of the thermal deterioration is surely prevented. .

  In the light emitting diode 1 according to the present invention, the glass tube mount 4 and the glass bulb 5 constitute a double tube structure, and a vacuum layer with high heat insulation can be easily formed between them. It is. Further, since the heat transfer distance from the glass tube mount 4 to the LED chip 6 is also relatively long, heat conduction to the LED chip 6 is suppressed, and the occurrence of thermal deterioration of the LED chip 6 can be prevented more reliably.

  In addition, when an inert gas is sealed between the glass tube mount 4 and the glass bulb 5 so that the LED chip 6 is not heated to a temperature higher than the heat resistant temperature, the heat generated when the LED chip 6 is turned on is dissipated. Thus, the occurrence of thermal degradation of the LED chip 6 can be suppressed. Furthermore, high moisture resistance can be ensured, deterioration of the mold resin due to sunlight or short wavelength light emitted from the LED chip 6 can be suppressed, and the highly reliable light emitting diode 1 can be obtained.

  In addition, the light-emitting diode 1 according to the present invention does not require a substrate or a conductor pattern for mounting the LED chip 6, and does not require drilling or the like in the substrate, thereby reducing the number of parts and the number of processing steps. The cost is reduced. Thereby, possibility that thermal deterioration will arise in the adhesion | attachment means of LED chip 6, such as LED chip 6, die-bonding material, and a wire bonding material can be suppressed.

The glass tube 11 is a soft glass (outer diameter D = φ3.05 mm, thickness t = 0.3 mm, length L = 7.0 mm, thermal conductivity k = 1.0 (W / (m · K)). When using Nippon Electric Glass Co., Ltd., model number: PS-94), the cross-sectional area A is A = 2.59 mm ² , and the thermal resistance calculated by the following equation is
Thermal resistance = t / (A / k) = 2700.8 (K / W)
Thus, the temperature around the LED chip 6 was kept at 250 ° C. or lower while the temperature of the sealing portion (heated and melted portion) at the time of sealing with the glass bulb 5 was 600 ° C. to 700 ° C.

<Embodiment 2>
Next, a second embodiment of the present invention will be described.

  FIG. 4 is a longitudinal sectional view of a light emitting diode according to Embodiment 2 of the present invention. In this figure, the same elements as those shown in FIG. Description of is omitted.

  The light emitting diode 1 ′ according to the present embodiment is the same as the structure of the light emitting diode 1 according to the first embodiment except that the glass tube constituting the glass tube mount 4 is a straight tube 14 having the same diameter. In this light-emitting diode 1 ′, the glass bulb 5 includes a straight tube that constitutes the glass tube mount 4 and the peripheral edge of the lower surface opening of the glass tube 11 (see FIG. 6B) whose upper end is closed in a dome shape. The LED chip 6 and the glass tube mount 4 are hermetically sealed by the glass bulb 5.

  Next, a manufacturing method of the light-emitting diode 1 ′ having the above configuration is shown in FIGS. 5 and 6, and the manufacturing method of the light-emitting diode 1 ′ according to the present embodiment is the same as that of the light-emitting diode 1 according to the first embodiment. Since this is the same as the manufacturing method, description thereof will be omitted and only illustrated. 5A to 5D are explanatory views showing a method for obtaining a glass tube mount in the order of the steps, and FIGS. 6A to 6D are diagrams showing a manufacturing method after obtaining the glass tube mount in the order of the steps. It is explanatory drawing shown.

  Thus, the light-emitting diode 1 ′ according to the present embodiment can achieve the same effect as that of the first embodiment, and the heat of the LED chip 6 can be obtained without increasing the cost due to the increase in the number of parts and the number of processing steps. The occurrence of deterioration can be prevented.

<Embodiment 3>
Next, a third embodiment of the present invention will be described.

  FIG. 7 is a longitudinal sectional view of a light emitting diode according to Embodiment 3 of the present invention. In this figure, the same elements as those shown in FIG. Description of is omitted.

  The manufacturing method of the light emitting diode 1 according to the present embodiment is obtained by adding a pinch seal process in order to improve the sealing performance between the lead wires 2 and 3 and the glass mount 4 in the first embodiment. That is, as shown in FIG. 8C, the upper end opening of the flare tube 9 is heated by the burner 12 to be in a molten state, and the upper portion of the flare tube 9 is formed by the pinch mold 15 as shown in FIG. Is formed into a pinch roll shape by applying pressure from both sides, and then cooled to obtain a glass tube mount 4 as shown in FIG. Thereafter, the light emitting diode 1 is manufactured through the steps shown in FIGS.

<Embodiment 4>
Next, a fourth embodiment of the present invention will be described.

  FIG. 9 is a longitudinal sectional view of a light-emitting diode according to Embodiment 4 of the present invention. In FIG. 9, the same elements as those shown in FIG. 1 are denoted by the same reference numerals. Description of is omitted.

  The manufacturing method of the light emitting diode 1 ′ according to the present embodiment is obtained by adding a pinch sealing process in order to improve the sealing performance between the lead wires 2 and 3 and the glass mount 4 in the second embodiment. That is, as shown in FIG. 10C, the upper end opening of the straight tube 14 is heated by the burner 12 to be in a molten state, and the upper portion of the straight tube 14 is formed by the pinch mold 15 as shown in FIG. Is formed into a pinch roll shape by applying pressure from both sides, and then cooled to obtain a glass tube mount 4 as shown in FIG. Thereafter, the light emitting diode 1 'is manufactured through the steps shown in FIGS.

DESCRIPTION OF SYMBOLS 1,1 'Light emitting diode 2,3 Lead wire 2a Lead wire bending part 4 Glass tube mount 4a Upper end part of glass tube mount 5 Glass bulb 6 LED chip 7, 8 Bonding wire 9 Flare tube (1st glass tube)
10 Glass beads 11 Glass tube (second glass tube)
12 Burner 13 Drawing cutter 14 Straight tube (first glass tube)
15 Pinch mold

Claims (5)

  An LED chip is mounted on the tip of the lead wire of a glass tube mount having a hollow structure through which the upper ends of a pair of lead wires are inserted, and the lower end opening of the glass tube with the upper end closed and the lower surface opening of the glass tube mount A light emitting diode comprising: a glass bulb formed by fusing a peripheral edge of a portion; and the LED chip and the glass tube mount are hermetically sealed by the glass bulb.   2. The light emitting diode according to claim 1, wherein the glass tube mount is constituted by a flare tube whose periphery of the lower surface opening extends radially outward.   2. The light emitting diode according to claim 1, wherein the glass tube mount is constituted by straight tubes having the same diameter. A step of melting and fixing a glass bead at the tip of a pair of lead wires, and fusing the upper end opening of a cylindrical first glass tube to the glass bead to obtain a glass tube mount having a hollow structure;
Mounting an LED chip on the tip of the lead wire of the glass tube mount;
The glass tube mount is inserted into the second glass tube together with the LED chip from the lower surface opening of the second glass tube whose upper end is closed, and the periphery of the lower surface opening of the glass tube mount is temporarily fixed to the second glass tube. And a process of
Forming a glass bulb by heating a portion of the second glass tube where the glass tube mount is temporarily fixed and fusing the second glass tube and the peripheral edge of the lower surface opening of the glass tube mount; ,
Cutting the glass bulb;
A method of manufacturing a light emitting diode, characterized in that a light emitting diode is obtained through 5. The method of manufacturing a light emitting diode according to claim 4, wherein the step of obtaining the glass tube mount having a hollow structure includes a pinch sealing step of pinching the upper end opening of the glass tube mount in a molten state.

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