JP2011124333A - Led mounting board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LED (Light Emitting Diode) mounting board for achieving a compact LED circuit for lighting. <P>SOLUTION: The LED mounting board 10 includes: an LED mounting electrode pair comprising an anode electrode 11 and a cathode electrode 12, to which the anode and cathode of an LED 1 are connected respectively; a first terminal electrode 21 connected to the anode electrode 11; a second terminal electrode 22 connected to the cathode electrode 12; a third terminal electrode 23; a bypass layer 30 connected in parallel with the LED 1 and having a bypass element 31, which has a trigger voltage higher than a light emission voltage of the LED 1, formed; and a varistor layer 40 connected between the first terminal electrode 21 and third terminal electrode 23 and having a first varistor element 41, which has a varistor voltage higher than the trigger voltage and also has a faster response speed than the bypass element 31, formed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an LED mounting substrate, and more particularly to an LED mounting substrate for realizing an LED circuit for illumination.

  In recent years, LEDs (Light Emitting Diodes) have attracted attention as replacements for conventional light sources. LEDs have features such as longer life and lower power consumption than conventional light sources such as light bulbs and fluorescent lamps, and have come to be used for backlights of liquid crystal displays in addition to lighting fixtures in rooms. ing.

  By the way, the LED circuit for illumination is usually provided with an electrostatic breakdown countermeasure for protecting the LED from electrostatic breakdown. That is, a mechanism for preventing a large current generated by static electricity from flowing directly to the LED is provided, and in a typical example, a bypass circuit that conducts only when static electricity is applied is provided.

  Patent Document 1 discloses an example of a bypass circuit using a Zener diode. The LED circuit according to this example has a configuration in which a plurality of LED series circuits composed of a plurality of LEDs connected in series are connected in parallel. For each LED series circuit, a Zener diode having a polarity opposite to that of each LED is provided. Connected in parallel. The Zener voltage of the Zener diode is designed to be larger than the light emission voltage of the LED and smaller than the electrostatic voltage. Therefore, in a normal operation state, the Zener diode does not conduct, and the current flows through the LED series circuit side. On the other hand, when static electricity occurs, the Zener diode conducts and most of the current flows through the Zener diode side. .

  Patent Document 2 discloses an example of a bypass circuit using a varistor element, although it is an example of a single LED component instead of an LED circuit. In this LED component, an LED is mounted on a varistor element built-in substrate, and the varistor element is connected in parallel with the LED. The varistor voltage of the varistor element is also designed to be larger than the LED emission voltage and smaller than the electrostatic voltage. Therefore, in a normal operation state, the varistor element does not conduct, and current flows through the LED side. On the other hand, when static electricity occurs, the varistor element conducts and most of the current flows through the varistor element side.

  Further, in the LED circuit for illumination, an LED series circuit as described in Patent Document 1 is used. However, there is a problem in that when one LED is disconnected, other LEDs do not light up. . The LED circuit of Patent Document 1 solves this problem by connecting a Zener diode having a reverse polarity as a bypass circuit at the time of disconnection in parallel with each LED, separately from the Zener diode for countermeasures against electrostatic breakdown. Yes.

JP 2000-231363 A JP 2006-339559 A

  However, the LED circuit described in Patent Document 1 has a problem that it is not suitable for miniaturization. That is, since this LED circuit is configured by mounting lead parts on both sides of a printed wiring board, there is a limit to downsizing.

  Although the LED component described in Patent Document 2 uses a varistor element-embedded substrate, it does not contribute to miniaturization from the viewpoint of configuring an LED circuit for illumination. That is, since the LED component described in Patent Document 2 does not have the above-described bypass circuit at the time of disconnection, when trying to configure an LED circuit for illumination, the lead component is used in the same way as in Patent Document 1 to prevent disconnection. It is necessary to provide a bypass circuit, and the size cannot be reduced.

  In addition, the varistor element in the LED component described in Patent Document 2 does not serve as a countermeasure against electrostatic breakdown when constituting an LED circuit for illumination, and a bypass circuit for countermeasure against electrostatic breakdown Similar to Patent Document 1, it is necessary to use lead parts. That is, when the LED components described in Patent Document 2 are connected in series, the varistor elements are also connected in series, and the magnitude of the electrostatic voltage necessary for these series-connected varistor elements to conduct is as follows. Thus, the total varistor voltage of each varistor element is obtained. Since this value is a very large value, the varistor element is not practically used as a countermeasure against electrostatic breakdown. Therefore, it is necessary to provide a bypass circuit for countermeasures against electrostatic breakdown separately from the varistor element. Eventually, only the LED circuit that is larger than the LED circuit described in Patent Document 1 is realized because of the extra varistor element. It will not be possible.

  Accordingly, an object of the present invention is to provide an LED mounting substrate for realizing a miniaturized LED circuit for illumination.

  An LED mounting substrate according to the present invention for solving the above-described problems includes an LED mounting electrode pair comprising an anode electrode and a cathode electrode to which an anode and a cathode of an LED are connected, respectively, and a first electrode connected to the anode electrode. A bypass element comprising a terminal electrode, a second terminal electrode connected to the cathode electrode, and a third terminal electrode, connected in parallel with the LED and having a trigger voltage higher than the light emission voltage of the LED is formed. A first varistor element connected between the bypass layer, the first terminal electrode and the third terminal electrode, having a varistor voltage higher than the trigger voltage and having a faster response speed than the bypass element. The varistor layer in which is formed is laminated.

  According to the present invention, a bypass layer in which a bypass element that functions as a bypass circuit at the time of disconnection is formed on one LED mounting substrate, and a varistor element that functions as a bypass circuit for countermeasures against electrostatic breakdown are formed. Since the varistor layer is built in and the varistor element is connected between the first terminal electrode and the third terminal electrode instead of between the first terminal electrode and the second terminal electrode, the size is reduced. An LED circuit for illumination is realized.

  In the LED mounting substrate, the LED mounting electrode pair and the first terminal electrode are respectively formed above and below the varistor layer, penetrate at least the varistor layer, and pass through the anode electrode and the first electrode. A first through-hole electrode that connects to the first terminal electrode, and one end of the first varistor element may be connected to the first terminal electrode by the first through-hole electrode. Further, the third terminal electrode is formed on the lower surface of the varistor layer, further provided with a third through-hole electrode provided on the varistor layer and connected to the third terminal electrode on the lower surface of the varistor layer. The other end of the first varistor element may be connected to the third terminal electrode by the second through-hole electrode.

  The LED mounting substrate further includes a fourth terminal electrode, and the varistor layer is connected between the second terminal electrode and the fourth terminal electrode, and is higher than the trigger voltage. A second varistor element having a voltage and a response speed faster than the bypass element may be further formed. The LED mounting electrode pair and the second terminal electrode are respectively formed on the upper side and the lower side of the varistor layer, penetrate at least the varistor layer, and connect the cathode electrode and the second terminal electrode. A second through-hole electrode to be connected may be further provided, and one end of the second varistor element may be connected to the second terminal electrode by the second through-hole electrode. The fourth terminal electrode is further formed on a lower surface of the varistor layer, further provided with a fourth through-hole electrode provided on the varistor layer and connected to the fourth terminal electrode on the lower surface of the varistor layer. The other end of the second varistor element may be connected to the fourth terminal electrode by the fourth through-hole electrode.

  Each of the LED mounting substrates includes a plurality of the LED mounting electrode pairs, and the first terminal electrode includes at least one of a plurality of anode electrodes constituting the plurality of LED mounting electrode pairs. The second terminal electrode is connected to at least one of a plurality of cathode electrodes constituting the plurality of LED mounting electrode pairs, and the bypass layer is connected to the bypass for each of the LED mounting electrode pairs. Each of the bypass elements may be connected between an anode electrode and a cathode electrode of the corresponding LED mounting electrode pair. Further, the plurality of LED mounting electrode pairs are arranged in a matrix of m rows and n columns, and the cathode electrodes of the LED mounting electrode pairs in the k-th column (1 <k <n) of each row are in the same row. It is connected to the anode electrode of the LED mounting electrode pair in the (k + 1) th row, each anode electrode included in each LED mounting electrode pair in the first row is connected to the first terminal electrode, and nth Each cathode electrode included in each LED mounting electrode pair in a row may be connected to the second terminal electrode.

  According to the present invention, a miniaturized LED circuit for illumination is realized.

It is a top view of the board | substrate for LED mounting by the 1st Embodiment of this invention. (A) is the sectional view along the A-A 'line of FIG. 1, and (b) is the sectional view along the B-B' line of FIG. It is an equivalent circuit schematic of the board | substrate for LED mounting by the 1st Embodiment of this invention. It is a circuit diagram of the circuit for LED illumination comprised using the board | substrate for LED mounting by the 1st Embodiment of this invention. It is a top view of the board | substrate for LED mounting by the 2nd Embodiment of this invention. 5A is a cross-sectional view taken along line C-C ′ in FIG. 5, and FIG. 5B is a cross-sectional view taken along line D-D ′ in FIG. 5. It is a circuit diagram of the circuit for LED illumination comprised using the board | substrate for LED mounting by the 2nd Embodiment of this invention. It is a top view of the board | substrate for LED mounting by the 3rd Embodiment of this invention. (A) is the E-E 'sectional view taken on the line of FIG. 8, (b) is the F-F' sectional view taken on the line of FIG. It is a circuit diagram of the circuit for LED illumination comprised using the board | substrate for LED mounting by the 3rd Embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a top view of an LED mounting substrate 10 according to the first embodiment of the present invention. In the figure, the configuration indicated by a broken line transparently shows a part of the configuration existing inside or on the lower surface of the substrate. 2A is a cross-sectional view taken along line A-A ′ in FIG. 1, and FIG. 2B is a cross-sectional view taken along line B-B ′ in FIG. 1. FIG. 3 is an equivalent circuit diagram of the LED mounting substrate 10. In these drawings, the LED 1 mounted on the upper surface of the LED mounting substrate 10 is also drawn.

  As shown in FIGS. 1 to 3, the LED mounting substrate 10 according to the present embodiment is a substrate on which one LED 1 is mounted. As shown in FIG. 1, an anode electrode 11 to which the anode of the LED 1 is connected and a cathode electrode 12 to which the cathode of the LED 1 is connected are formed on the upper surface of the LED mounting substrate 10 one by one. Constitutes an LED mounting electrode pair. The LED 1 and the anode electrode 11 and the cathode electrode 12 are connected by bonding wires 2 and 3 as shown in FIG.

  As shown in FIGS. 2A and 2B, the LED mounting substrate 10 has a laminated structure including a bypass layer 30 and a varistor layer 40 formed below the bypass layer 30. The bypass layer 30 has a structure in which a bypass element 31 is formed inside the insulator, and the varistor layer 40 has a structure in which a varistor element 41 (first varistor element) is formed inside the insulator. Details of these elements will be described later.

  First to third terminal electrodes 21 to 23 are formed on the lower surface of the LED mounting substrate 10. Further, first to third through-hole electrodes 25 to 27 are provided inside the LED mounting substrate 10. The first and second through-hole electrodes 25 and 26 are provided through the bypass layer 30 and the varistor layer 40, and the third through-hole electrode 27 is provided in the varistor layer 40. As shown in FIG. 2A, the first through-hole electrode 25 is connected to the anode electrode 11 on the upper surface of the LED mounting substrate 10 and is connected to the first terminal electrode 21 on the lower surface. Similarly, the second through-hole electrode 26 is connected to the cathode electrode 12 on the upper surface of the LED mounting substrate 10 and is connected to the second terminal electrode 22 on the lower surface. The third through-hole electrode 27 is connected to the third terminal electrode 23 on the lower surface of the LED mounting substrate 10.

  As shown in FIG. 2A, the bypass element 31 provided in the bypass layer 30 has a structure in which a thin film insulator 34 is sandwiched between an upper electrode pattern 32 and a lower electrode pattern 33. As shown, the LED 1 is connected in parallel.

  The specific structure will be described with reference to FIG. 2A. The lower electrode pattern 33 is formed on the upper surface of the varistor layer 40 and is connected to the second through-hole electrode 26. On the other hand, the upper electrode pattern 32 is formed on the upper surface of the varistor layer 40 and is connected to the first through-hole electrode 25 through a conductor pattern 35 connected to the first through-hole electrode 25. Accordingly, the bypass element 31 is connected in parallel with the LED 1 between the anode electrode 11 and the cathode electrode 12.

  The bypass element 31 has the same function as a so-called antifuse element, and functions as a bypass circuit when the LEDs 1 connected in parallel are disconnected. That is, the bypass element 31 has a trigger voltage higher than the light emission voltage of the LED 1, and is usually in a high resistance state of several MΩ while the potential difference between the upper electrode pattern 32 and the lower electrode pattern 33 is lower than this trigger voltage. To maintain. On the other hand, when the potential difference between the upper electrode pattern 32 and the lower electrode pattern 33 exceeds the trigger voltage, the bypass element 31 enters a low resistance state. This is because the thin film insulator 34 is broken down.

  Here, the response speed of the bypass element 31 is several milliseconds to several tens of milliseconds. That is, the bypass element 31 enters the low resistance state only when the state in which the potential difference between the upper electrode pattern 32 and the lower electrode pattern 33 exceeds the trigger voltage continues for several milliseconds to several tens of milliseconds.

  The varistor element 41 provided in the varistor layer 40 includes an insulator in which a plurality of upper electrode patterns 42 and a plurality of lower electrode patterns 43 constitute a varistor layer 40 as shown in FIGS. As shown also in FIG. 3, it is connected between the first terminal electrode 21 and the third terminal electrode 23.

  A specific structure will be described with reference to FIGS. 2A and 2B. The upper electrode pattern 42 is connected to the first through-hole electrode 25 in the varistor layer 40. On the other hand, the lower electrode pattern 43 is connected to the third through-hole electrode 27 in the varistor layer 40. Therefore, the varistor element 41 is connected between the first terminal electrode 21 and the third terminal electrode 23.

  A varistor voltage is set in the varistor element 41. The varistor element 41 is conductive only when the potential difference between the upper electrode pattern 42 and the lower electrode pattern 43 is higher than the varistor voltage, and is otherwise non-conductive.

  Since the varistor element 41 is provided for countermeasures against electrostatic breakdown, it is necessary that the varistor element 41 is quickly turned on when static electricity is input so that a large current does not flow through the LED 1 or the bypass element 31. Therefore, the response speed of the varistor element 41 is set to several nanoseconds to several tens of nanoseconds faster than the response speed of the bypass element 31. The varistor voltage of the varistor element 41 is set to a value higher than the trigger voltage of the bypass element 31.

  Hereinafter, the operation of the LED mounting substrate 10 according to the present embodiment will be described with reference to a specific example of an LED illumination circuit.

  FIG. 4 is a circuit diagram of an LED illumination circuit configured using the LED mounting substrate 10. The LED illumination circuit shown in the figure is an LED series circuit in which a plurality of LEDs 1 each arranged on an LED mounting substrate 10 are arranged in series. Although there are actually switches, etc., they are omitted here.

  In FIG. 4, the first terminal electrode 21 of the LED mounting board 10 located on the leftmost side is connected to the positive electrode side of the DC power supply 50, and the second terminal electrode 22 of the LED mounting board 10 located on the rightmost side is DC. Connected to the negative side of the power supply 50. In addition, the first terminal electrode 21 of the LED mounting substrate 10 other than the LED mounting substrate 10 positioned on the leftmost side is connected to the second terminal electrode 22 of the LED mounting substrate 10 positioned on the left side thereof. The third terminal electrode 23 of each LED mounting substrate 10 is connected to the negative electrode side of the DC power supply 50.

  The voltage of the DC power supply 50 is set to a value exceeding the total light emission voltage of each LED 1. Therefore, in a state where all the LEDs 1 are not disconnected, a voltage exceeding the light emission voltage is applied between the anode and the cathode of each LED 1 and each LED 1 is lit.

  When a certain LED 1 is disconnected, a voltage higher than the light emission voltage of the LED 1 is applied to the bypass element 31 connected in parallel with the LED 1. The trigger voltage of the bypass element 31 is set to a value lower than the voltage applied to the bypass element 31 at this time. Therefore, the bypass element 31 is changed to a low resistance state by the applied voltage, and the current flows through the bypass element 31, so that the lighting state of the other LEDs 1 is maintained even if one LED 1 is disconnected. .

  When static electricity is input to the circuit, one of the varistor elements 41 becomes conductive and bypasses the current. In addition, since each varistor element 41 is connected in parallel with each other, the magnitude of the electrostatic voltage necessary for any varistor element 41 to conduct is equal to the varistor voltage of each varistor element 41, and It is not the total value of the varistor voltage of the element. Therefore, in the LED illumination circuit of FIG. 4, appropriately protecting each LED 1 from electrostatic breakdown is realized.

  The possibility that the static electricity is actually input is a state before the LED lighting circuit shown in FIG. 4 is assembled after the LED 1 is mounted on the LED mounting substrate 10 (hereinafter referred to as “one-chip state”). The highest. In the present embodiment, since the varistor element 41 is provided for each LED mounting substrate 10, the LED 1 can be effectively protected from electrostatic breakdown in a one-chip state.

  As described above, in the LED mounting substrate 10 according to the present embodiment, the bypass layer 30 in which the bypass element 31 functioning as a bypass circuit at the time of disconnection is formed on one LED mounting substrate 10, and electrostatic The varistor layer 40 in which the varistor element 41 that functions as a bypass circuit for countermeasures against breakdown is formed is built-in. Since they are connected in between, a miniaturized LED circuit for illumination is realized.

  FIG. 5 is a top view of the LED mounting substrate 10 according to the second embodiment of the present invention. In the figure, the configuration indicated by a broken line transparently shows a part of the configuration existing inside or on the lower surface of the substrate. 6A is a cross-sectional view taken along line C-C ′ in FIG. 5, and FIG. 6B is a cross-sectional view taken along line D-D ′ in FIG. 5. In these drawings, the LED 1 mounted on the upper surface of the LED mounting substrate 10 is also drawn. FIG. 7 is a circuit diagram of an LED illumination circuit configured using the LED mounting substrate 10 according to the present embodiment.

  As shown in FIGS. 5 to 7, a plurality of LEDs 1 are mounted on the LED mounting substrate 10 according to the present embodiment. In order to mount a plurality of LEDs 1, the LED mounting substrate 10 has a plurality of LED mounting electrode pairs 13 each composed of an anode electrode 11 and a cathode electrode 12. Each LED 1 is connected to the LED mounting electrode pair 13 one by one by wire bonding.

  The first terminal electrode 21 formed on the lower surface of the LED mounting substrate 10 is connected to at least one of the plurality of anode electrodes 11 constituting the plurality of LED mounting electrode pairs 13. Similarly, the second terminal electrode 22 formed on the lower surface of the LED mounting substrate 10 is connected to at least one of the plurality of cathode electrodes 12 constituting the plurality of LED mounting electrode pairs 13. The bypass layer 30 includes a bypass element 31 for each LED mounting electrode pair 13, and each bypass element 31 is connected between the anode electrode 11 and the cathode electrode 12 of the corresponding LED mounting electrode pair 13. The

  More specifically, each LED mounting electrode pair 13 is arranged in a matrix of m rows and n columns as shown in FIG. Although m = n = 5 in FIG. 5, the values of m and n are not limited to this.

  The anode electrodes 11 included in each LED mounting electrode pair 13 in the first column (the leftmost column in FIG. 5) are integrated to form one electrode pattern 14. The cathode electrodes 12 included in each LED mounting electrode pair 13 in the n-th column (the rightmost column in FIG. 5) are integrated to form one electrode pattern 15. The electrode patterns 14 and 15 are formed on the lower surface of the LED mounting substrate 10 by first and second through-hole electrodes 25 and 26 similar to those described in the first embodiment, respectively. 2 terminal electrodes 21 and 22.

  The cathode electrode 12 of the LED mounting electrode pair 13 in the kth column (1 ≦ k <n) of each row is integrated with the anode electrode 11 of the LED mounting electrode pair 13 in the (k + 1) th column of the same row. The electrode pattern 16 shown in FIG. In other words, the electrode pattern 16 serves as both the cathode electrode 12 of the LED mounting electrode pair 13 located on the left side and the anode electrode 11 of the LED mounting electrode pair 13 located on the right side.

  Each electrode pattern 16 is connected to the upper end of the through-hole electrode 36 provided in the bypass layer 30. The through-hole electrode 36 is provided for arranging the bypass element 31 for each LED mounting electrode pair 13. A bypass element 31 is provided between the through-hole electrode 36 and another adjacent through-hole electrode 36 (or the first through-hole electrode 25 or the second through-hole electrode 26) adjacent in the row direction. The specific structure and function of each bypass element 31 are the same as the structure of the bypass element 31 described with reference to FIG.

  A varistor element 41 is provided in the varistor layer 40. The structure and function of the varistor element 41 are the same as those of the varistor element 41 described with reference to FIG.

  As shown in the circuit of FIG. 7, the first terminal electrode 21 is connected to the positive electrode side of the DC power supply 50, and the second terminal electrode 22 is connected to the negative electrode side of the DC power supply 50. The third terminal electrode 23 is grounded. With this configuration, similarly to the LED illumination circuit described with reference to FIG. 4, each unconnected LED 1 is turned on, and the bypass element 31 connected in parallel with the disconnected LED 1 changes to a low resistance state.

  Unlike the LED illumination circuit of FIG. 4, only one varistor element 41 is provided in the entire circuit. However, since the LED mounting substrate 10 according to the present embodiment has 25 LEDs 1 arranged in 5 rows and 5 columns all formed on one chip, one varistor element 41 is used for the entire circuit. Even in this case, each LED 1 can be effectively protected from electrostatic breakdown in the above-described one-chip state.

  As described above, in the LED mounting substrate 10 according to the present embodiment, the bypass element 31 that functions as a bypass circuit at the time of disconnection is provided for each LED 1 on the single LED mounting substrate 10 on which the plurality of LEDs 1 are mounted. The formed bypass layer 30 and the varistor layer 40 in which the varistor element 41 functioning as a bypass circuit for countermeasures against electrostatic breakdown is formed are incorporated. Moreover, the varistor element 41 is connected not between the terminal electrode 21 and the terminal electrode 22 but between the terminal electrode 21 and the terminal electrode 23. Therefore, a miniaturized LED circuit for illumination is realized.

  FIG. 8 is a top view of the LED mounting substrate 10 according to the third embodiment of the present invention. In the figure, the configuration indicated by a broken line transparently shows a part of the configuration existing inside or on the lower surface of the substrate. FIG. 9A is a cross-sectional view taken along line E-E ′ of FIG. 8, and FIG. 9B is a cross-sectional view taken along line F-F ′ of FIG. 5. In these drawings, the LED 1 mounted on the upper surface of the LED mounting substrate 10 is also drawn. FIG. 10 is a circuit diagram of an LED illumination circuit configured using the LED mounting substrate 10 according to the present embodiment.

  As is clear from comparison of FIG. 10 with FIG. 7, the LED mounting substrate 10 according to the present embodiment is provided with the LED mounting according to the second embodiment in that a varistor element 44 (second varistor element) is provided. This is different from the substrate 10 for use. Hereinafter, this difference will be mainly described.

  8 and 9A, a fourth terminal electrode 24 is formed on the lower surface of the LED mounting substrate 10 according to the present embodiment in addition to the first to third terminal electrodes 21 to 23. Is done. A fourth through hole electrode 28 is provided in the varistor layer 40. The fourth through-hole electrode 28 is connected to the fourth terminal electrode 24 on the lower surface of the LED mounting substrate 10.

  In the varistor element 44, a plurality of upper electrode patterns 45 and a plurality of lower electrode patterns 46 are alternately arranged so as to sandwich an insulator constituting the varistor layer 40 as shown in FIGS. 9 (a) and 9 (b). 10 and is connected between the second terminal electrode 22 and the fourth terminal electrode 24 as shown in FIG.

  A specific structure will be described with reference to FIGS. 9A and 9B. The upper electrode pattern 45 is connected to the second through-hole electrode 26 in the varistor layer 40. On the other hand, the lower electrode pattern 46 is connected to the fourth through-hole electrode 28 in the varistor layer 40. Therefore, the varistor element 44 is connected between the second terminal electrode 22 and the fourth terminal electrode 24.

  A varistor voltage is also set for the varistor element 44. The varistor element 44 is conductive only when the potential difference between the upper electrode pattern 42 and the lower electrode pattern 43 is higher than the varistor voltage, and is otherwise non-conductive.

  Similarly to the varistor element 41, the varistor element 44 is also provided for countermeasures against electrostatic breakdown. Therefore, the varistor element 44 is quickly turned on when static electricity is input so that a large current does not flow through the LED 1 or the bypass element 31. There is a need to. Therefore, the response speed of the varistor element 44 is also set to several nanoseconds to several tens of nanoseconds, which is faster than the response speed of the bypass element 31. The varistor voltage of the varistor element 44 is set to a value higher than the trigger voltage of the bypass element 31. The specific configuration of the varistor element 44 may be the same as the configuration of the varistor element 41 described above.

  Since the varistor element 44 is provided, the area where the varistor element 41 is formed is halved compared to the second embodiment. The area where the varistor element 44 is formed is also half that of the second embodiment.

  When static electricity is input to the circuit, one or both of the varistor elements 41 and 44 are turned on to bypass the current. Therefore, the LED mounting substrate 10 according to the present embodiment can more effectively protect each LED 1 from electrostatic breakdown than the LED mounting substrate 10 according to the second embodiment. .

  As described above, in the LED mounting substrate 10 according to the present embodiment, the bypass element 31 that functions as a bypass circuit at the time of disconnection is provided for each LED 1 on the single LED mounting substrate 10 on which the plurality of LEDs 1 are mounted. The formed bypass layer 30 and the varistor layer 40 in which the varistor elements 41 and 44 functioning as a bypass circuit for countermeasures against electrostatic breakdown are formed are incorporated. Moreover, the varistor elements 41 and 44 are not connected between the terminal electrode 21 and the terminal electrode 22, but are connected between the terminal electrode 21 and the terminal electrode 23, and between the terminal electrode 22 and the terminal electrode 24, respectively. . Therefore, a miniaturized LED circuit for illumination is realized.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to such embodiment at all, and this invention can be implemented in various aspects in the range which does not deviate from the summary. Of course.

  For example, the varistor element 44 described in the third embodiment may be incorporated in the LED mounting substrate 10 according to the first embodiment. By doing so, it becomes possible to more effectively protect the LED 1 from electrostatic breakdown.

1 LED
2, 3 Bonding wires 10 LED mounting substrate 11 Anode electrode 12 Cathode electrode 13 LED mounting electrode pairs 14 to 16 Electrode patterns 21 to 24 First to fourth terminal electrodes 25 to 28 First to fourth through-hole electrodes 30 Bypass layer 31 Bypass elements 32, 42, 45 Upper electrode pattern 33, 43, 46 Lower electrode pattern 34 Thin film insulator 35 Conductor pattern 36 Through-hole electrode 40 Varistor layer 41, 44 Varistor element 50 DC power supply

Claims (8)

LED mounting electrode pairs each consisting of an anode electrode and a cathode electrode to which the anode and cathode of the LED are connected;
A first terminal electrode connected to the anode electrode;
A second terminal electrode connected to the cathode electrode;
A third terminal electrode;
A bypass layer connected in parallel with the LED and having a bypass element having a trigger voltage higher than a light emission voltage of the LED;
A varistor layer connected between the first terminal electrode and the third terminal electrode and having a varistor voltage higher than the trigger voltage and having a faster response speed than the bypass element. And a substrate for LED mounting, characterized by having a structure in which and are laminated. The LED mounting electrode pair and the first terminal electrode are formed above and below the varistor layer, respectively.
A first through-hole electrode that penetrates at least the varistor layer and connects the anode electrode and the first terminal electrode;
2. The LED mounting substrate according to claim 1, wherein one end of the first varistor element is connected to the first terminal electrode by the first through-hole electrode. The third terminal electrode is formed on a lower surface of the varistor layer;
A third through-hole electrode provided on the varistor layer and connected to the third terminal electrode on a lower surface of the varistor layer;
3. The LED mounting substrate according to claim 2, wherein the other end of the first varistor element is connected to the third terminal electrode by the third through-hole electrode. A fourth terminal electrode;
The varistor layer is connected between the second terminal electrode and the fourth terminal electrode, has a varistor voltage higher than the trigger voltage, and has a faster response speed than the bypass element. The LED mounting substrate according to any one of claims 1 to 3, wherein is further formed. The LED mounting electrode pair and the second terminal electrode are formed above and below the varistor layer, respectively.
A second through-hole electrode that penetrates at least the varistor layer and connects the cathode electrode and the second terminal electrode;
5. The LED mounting substrate according to claim 4, wherein one end of the second varistor element is connected to the second terminal electrode by the second through-hole electrode. The fourth terminal electrode is formed on a lower surface of the varistor layer;
A fourth through-hole electrode provided on the varistor layer and connected to the fourth terminal electrode on a lower surface of the varistor layer;
6. The LED mounting substrate according to claim 5, wherein the other end of the second varistor element is connected to the fourth terminal electrode by the fourth through-hole electrode. A plurality of LED mounting electrode pairs;
The first terminal electrode is connected to at least one of a plurality of anode electrodes constituting the plurality of LED mounting electrode pairs,
The second terminal electrode is connected to at least one of a plurality of cathode electrodes constituting the plurality of LED mounting electrode pairs;
The bypass layer includes the bypass element for each LED mounting electrode pair, and each bypass element is connected between an anode electrode and a cathode electrode of the corresponding LED mounting electrode pair. The board | substrate for LED mounting as described in any one of Claim 1 thru | or 6. The plurality of LED mounting electrode pairs are arranged in a matrix of m rows and n columns,
The cathode electrode of the LED mounting electrode pair in the k-th column (1 <k <n) of each row is connected to the anode electrode of the LED mounting electrode pair in the (k + 1) -th column of the same row,
Each anode electrode included in each LED mounting electrode pair in the first row is connected to the first terminal electrode;
The LED mounting substrate according to claim 7, wherein each cathode electrode included in each LED mounting electrode pair in the n-th column is connected to the second terminal electrode.

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