JP2006049443A - Light emitting device and its mounting structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device and its mounting structure wherein the number of parts is reduced, a mounting area is minimized substantially and reliability is ensured. <P>SOLUTION: The light emitting device is provided with an LED flash light 5 with a white LED 4; a circuit 11 which is electrically connected with the white LED 4 and constitutes at least one of a driving circuit; and an interposer board 12 wherein the LED flash light 5 is provided on its surface, the circuit 11 is provided on its rear surface, and the electrical connection between the white LED 4 and the circuit 11 is established by an internal wiring. Thus, due to such a module that the LED flash light 5 and the circuit 11 are respectively arranged on the front and rear surfaces of the interposer board 12 in a three-dimensional manner, the required mounting area can be reduced substantially. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light emitting device using a white LED (light emitting diode) or the like mounted on a mobile phone with a camera function and the like, and a mounting structure thereof.

In recent years, mobile phones with camera functions have become widespread, and LED flashlights using white LEDs as an auxiliary light source have been installed. The white LED used in this LED flashlight has a large forward voltage drop Vf of 3.6 V on average and a maximum of 4 V, and is directly driven, for example, in a mobile phone powered by a single cell lithium ion battery. I can't. For this reason, the LED flashlight is mainly composed of an LED section and a booster circuit section that drives the LED section.
The boosting circuit unit is a dedicated circuit for boosting the battery voltage to the LED forward voltage drop Vf or more in order to drive the LED. As the boosting method, a coil boosting type using a coil and a charge pump using a capacitor are used. There are two main types: type.

  For example, as shown in FIG. 7, a coil boosting type boosting circuit unit 1 includes a coil 2 that is connected to a battery (not shown) of a DC power source and to which a battery voltage (power supply voltage) Vin is applied, and boosts the battery voltage. This is mainly composed of a driver IC 3, a capacitor Cin, Cout, a Schottky diode SBD, and the like for stabilization, and is connected to an LED flashlight section 5 on which a four-element type white LED 4 is mounted.

Conventionally, since component parts such as an LED unit and a booster circuit unit are mounted on a mother board, each component area becomes a mounting area and takes up space. In addition, the number of parts is increased, which increases the number of mounting processes, resulting in poor work efficiency.
On the other hand, as a technique capable of realizing miniaturization, for example, Patent Document 1 discloses a technique in which a light-emitting diode and a constant current circuit are molded in a transparent resin to simplify an external circuit. Further, Patent Document 2 discloses a driver built-in issue diode that is miniaturized by enclosing a driver IC chip and a light emitting diode chip on a metal frame in a package in a package.

JP-A-5-21850 (Claims, FIG. 1) Japanese Utility Model Publication No. 5-93058 (Utility Model Registration Request, FIG. 1)

In portable electronic devices such as mobile phones that will evolve to become more multifunctional in the future, the number of component parts such as LED parts and booster circuit parts will be reduced, the mounting area of each part will be further reduced, and the parts will be thinner There is a demand for it. In the technique disclosed in the conventional patent document 1, the light emitting diode and the constant current circuit are simply resin-molded together, and the number of parts is reduced, but there is a limit to downsizing, and the mounting area is reduced. There is little reduction effect. On the other hand, in the technique disclosed in Patent Document 2, the mounting area is reduced to some extent because the driver IC chip and the light emitting diode chip are integrated in a laminated state, but the space for arranging other circuit components is reduced. There is no need to mount it separately. Further, when there are a plurality of light emitting diode mounting chips, it is necessary to use a driver IC chip having a large area, and depending on the number of light emitting diode mounting chips, it is difficult to directly stack on the driver IC chip. In addition, since the light emitting diode is directly bonded onto the driver IC chip, a large thermal stress is generated due to a difference in thermal expansion coefficient due to heat generation, and a decrease in reliability is inevitable.

  The present invention has been made in view of the above-described problems, and provides a light emitting device and a mounting structure thereof capable of reducing the number of parts, greatly reducing the mounting area, and maintaining reliability. The purpose is to do.

  The present invention employs the following configuration in order to solve the above problems. That is, the light emitting device of the present invention includes a light emitting portion having a light emitting element, a circuit component portion constituting at least a part of a drive circuit electrically connected to the light emitting element, and a light emitting portion disposed on the surface. A circuit component portion is disposed on the back surface, and a double-sided substrate is provided that electrically connects the light emitting element and the circuit component portion with internal wiring.

  In other words, in this light emitting device, the light emitting portion and the circuit component portion are separately arranged on the front and back surfaces of the double-sided substrate and arranged in a three-dimensional manner, so that the mounting area required for each can be greatly reduced. . In addition, since the electrical connection process between the light emitting element and the circuit component portion is performed by wiring inside the substrate, external wiring can be simplified, the wiring area on the surface is greatly reduced, and further miniaturization is possible. In addition, the light emitting part and the circuit component part are not directly bonded, but are integrated with the double-sided board sandwiched therebetween, so the intermediate double-sided board relaxes the mutual thermal expansion difference and suppresses the generation of thermal stress. It can be maintained well. Further, by integrating the light emitting element and at least a part of the drive circuit, the conventionally required Zener diodes can be reduced, and electrostatic resistance can be improved.

  In addition, the light emitting device of the present invention includes a resin sealing portion in which a circuit component portion is sealed with a resin on the back surface of a double-sided board. That is, in this light emitting device, since the circuit component part is resin-molded and protected by the resin sealing part, the circuit parts such as the driver IC chip do not directly contact the mother board at the time of mounting, and the impact resistance is improved. At the same time, environmental characteristics such as moisture resistance are greatly improved. Further, as compared with the case where resin sealing is performed integrally with the light emitting element, a high degree of freedom is obtained in the resin material and the sealing shape, and a resin suitable for the circuit component portion can be selected and sealed.

Furthermore, the light emitting device of the present invention is characterized in that the resin sealing portion is formed as a convex portion on the back surface of the double-sided substrate.
That is, in this light emitting device, since the resin sealing portion is formed as a convex portion, when the light emitting device is mounted on a mounting substrate such as a motherboard, the concave portion into which the convex resin sealing portion can be inserted into the mounting substrate. Or the whole thickness can be made thin in a mounting state by providing a hole part and inserting and inserting a resin sealing part in this recessed part or hole part. Moreover, it is also possible to perform positioning at the time of mounting by inserting and mounting the resin sealing part which is a convex part in a recessed part or a hole.

  In the light emitting device of the present invention, the side end surfaces of the light emitting unit, the double-sided substrate, and the resin sealing unit are arranged flush with each other so that the whole has a cubic shape or a rectangular parallelepiped shape. An external connection terminal for connection is provided, and the external connection terminal extends to the side end surface of the resin sealing portion. That is, in this light emitting device, since the whole is in a cubic shape or a rectangular parallelepiped shape, that is, in a block shape, it is easy to surface-mount on the plane of the mounting substrate, and at the outside end up to the side end surface of the resin sealing portion that directly contacts the mounting substrate Since the connection terminals are formed to extend, it is possible to easily connect and fix the connection pads on the mounting substrate with solder or the like during mounting.

In the light-emitting device of the present invention, the double-sided substrate is a multilayer substrate, and a metal core is disposed on any layer of the multilayer substrate. In other words, in this light emitting device, a so-called metal core substrate, which is a printed wiring board with an excellent heat dissipation characteristic with a metal core incorporated in the inner layer, is adopted for the double-sided substrate. The reliability can be improved.

  In the light-emitting device of the present invention, the light-emitting element is a blue light-emitting diode element that emits white light by mixing a YAG phosphor in the covering member, and the circuit component portion includes at least a booster circuit IC chip and a coil of the light-emitting element. Or a capacitor. That is, in this light emitting device, either the booster circuit IC chip and the coil or the capacitor, which are the main components used in the booster circuit of the white LED, are included in the circuit component part and modularized, so the coil booster type or the charge pump type As a result, the mounting area can be greatly reduced.

  The light emitting device mounting structure of the present invention includes any one of the above-described light emitting devices of the present invention, a mounting region on which the light emitting device is mounted, and a substrate side circuit unit that is connected to the circuit component unit and constitutes a drive circuit. And a substrate. That is, in the mounting structure of the light emitting device, since the light emitting device of the present invention is mounted and the circuit component unit and the board side circuit are connected to constitute the drive circuit, the components of the drive circuit to be mounted on the mounting substrate The number of points can be reduced, the mounting area can be greatly reduced, and the mounting operation can be simplified.

  In the mounting structure of the light emitting device of the present invention, a resin sealing portion in which the circuit component portion is sealed with resin is provided on the back surface of the double-sided substrate, and the mounting substrate has a resin sealing portion in the mounting region. A recess or hole to be inserted is formed. That is, in this mounting structure of the light emitting device, since the resin sealing portion is inserted into the recess or hole of the mounting substrate for mounting, the resin sealing portion is housed in the mounting substrate. Can be made thinner.

  Furthermore, the mounting structure of the light emitting device of the present invention is formed such that an external connection terminal for connecting to an external circuit is provided on the side end portion of the double-sided board, and a resin sealing portion exposes the periphery of the external connection terminal. The electrode pad corresponding to the external connection terminal is provided on the surface of the mounting substrate in a state where the resin sealing portion is inserted into the recess or the hole. That is, in this light emitting device mounting structure, when the resin sealing portion is inserted into the recess or the hole, the external connection terminal and the electrode pad correspond to each other, thereby positioning and connecting the external connection terminal and the electrode pad. Can be easily performed.

The present invention has the following effects.
That is, according to the light emitting device and the mounting structure thereof according to the present invention, the light emitting portion is disposed on the front surface of the double-sided substrate, and the circuit portion is disposed on the back surface so Since the wiring is performed, the mounting area can be greatly reduced and the mounting work can be simplified by reducing the number of components and simplifying the external wiring, and the reliability can be maintained well. Furthermore, by making the light emitting element / driving circuit integrated structure, an effect of improving electrostatic resistance is also achieved. Therefore, the present invention is suitable for an auxiliary light source of a mobile phone and the like, for which multifunctionalization has progressed and the number of components and the mounting area are particularly demanded.

  Hereinafter, a first embodiment of a light emitting device and a mounting structure thereof according to the present invention will be described with reference to FIGS.

As shown in FIGS. 1 to 3, the light emitting device 10 of the present embodiment is a flash light used as an auxiliary light source of a mobile phone with a camera function, and an LED flash light unit (light emitting unit) having a white LED 4. 5, a circuit component unit 11 constituting at least a part of a drive circuit electrically connected to the white LED 4, an LED flashlight unit 5 is disposed on the front surface, and a circuit component unit 11 is disposed on the rear surface. An interposer substrate (double-sided substrate) 12 that performs electrical connection between the white LED 4 and the circuit component unit 11 by an internal wiring, and a resin sealing unit 13 that seals the circuit component unit 11 on the back surface of the interposer substrate 12 with resin It is equipped with.

  The LED flashlight unit 5 includes a four-element type white LED 4 bonded to the surface of the interposer substrate 12 and a reflective surface 14a that reflects the white light of the white LED 4 forward as a radially inclined surface around the white LED 4. And the reflector 14. The reflector 14 is made of resin, but the reflecting surface 14a is subjected to a surface treatment such as coating for increasing the reflectance. The white LED 4 is composed of four blue light-emitting diode elements (light-emitting elements: not shown) that are nitride semiconductor elements, and a covering member that covers these and is mixed with a YAG phosphor. That is, the white LED 4 includes a blue light emitting diode element that emits white light by mixing a YAG phosphor into the covering member. In addition, these blue light emitting diode elements are used with a forward voltage drop Vf of 3.6V.

As shown in FIGS. 2 and 3, the circuit component unit 11 is a component used for a coil boosting type boosting circuit (driving circuit) of the white LED 4, and includes a driver IC chip (IC chip for boosting circuit) 3 and a coil. 2 and a Schottky diode SBD.
Each of the driver IC chip 3 and the coil 2 has one electrode connected to the external connection terminal 15 and the other electrode connected to the Schottky diode SBD. The Schottky diode SBD has one electrode connected to the driver IC chip 3 and the coil 2, and the other electrode connected to the white LED 4 and the external connection terminal 15.

The interposer substrate 12 is a multilayer wiring substrate having wirings in the inner layers and via holes and through holes for connecting the wirings between the respective layers or between the front and back surfaces. The interposer substrate 12 has a driver IC chip 3 and a Schottky diode SBD bonded and fixed on the back surface thereof, and is provided so as to protrude to the back surface side in a state where the coil 2 is embedded. The interposer substrate 12 is provided with a plurality of external connection terminals 15 for electrical connection with an external circuit at a pair of opposing side end portions. The external connection terminals 15, the white LEDs 4, and the circuit component unit 11 are provided. That is, the driver IC chip 3, the coil 2, and the Schottky diode SBD are electrically connected to each other through wiring provided on the front and back surfaces of the interposer substrate 12 and inside.
The resin sealing portion 13 is formed as a convex portion on the back surface of the interposer substrate 12 by exposing the periphery of the external connection terminal 15. The resin sealing portion 13 is made of an epoxy resin having excellent moisture resistance.

Next, the mounting structure of the light emitting device 10 of this embodiment will be described with reference to FIGS. 4 and 5.
As shown in FIG. 5, the mounting structure of the light emitting device 10 includes a substrate side circuit unit that is connected to the light emitting device 10, a mounting region 16 a on which the light emitting device 10 is mounted, and a circuit component unit 11 to form a drive circuit. And a mother board (mounting substrate) 16 having 17.

The motherboard 16 has a hole 16b into which the resin sealing portion 13 is inserted in the mounting region 16a, and corresponds to the external connection terminal 15 with the resin sealing portion 13 inserted into the hole 16b. An electrode pad 16c is provided on the surface. That is, when the resin sealing portion 13 is inserted into the hole 16b, the external connection terminal 15 of the interposer substrate 12 is set so as to correspond to the position of the electrode pad 16c. The hole 16b is formed with a predetermined clearance slightly larger than the resin sealing portion 13 within an allowable range of positioning accuracy. Moreover, you may provide the recessed part which can insert the resin sealing part 13 of a convex part instead of the hole 16b.

  As shown in FIG. 3, the substrate-side circuit unit 17 is a circuit component as a part of the booster circuit of the white LED 4, with one electrode connected to the ground and the other electrode connected to the power supply voltage Vin and the external connection terminal 15. The first capacitor Cin connected to the part 11 (the coil 2 and the driver IC chip 3), and one electrode is connected to the circuit component part 11 (white LED 4 and Schottky diode SBD) via the external connection terminal 15 A second capacitor Cout whose electrode is connected to the ground, and a resistor R whose one electrode is connected to the circuit component part 11 (white LED 4) via the external connection terminal 15 and whose other electrode is connected to the ground. It is implemented and configured.

  In order to mount the light emitting device 10 on the motherboard 16, first, the resin sealing portion 13 is inserted into the hole 16 b of the motherboard 16 and temporarily fixed. At this time, since the external connection terminal 15 and the electrode pad 16c correspond, the electrode pad 16c and the external connection terminal 15 are connected and fixed by the solder 16d in this state. Thus, the light emitting device 10 is mounted on the mother board 16 and the circuit component unit 11 and the board side circuit unit 17 are connected and wired to form a drive circuit for boosting the white LED 4 as a whole.

  As described above, in the light emitting device 10 according to the present embodiment, the LED flashlight unit 5 and the circuit component unit 11 are separately arranged on the front and back surfaces of the interposer substrate 12 and arranged three-dimensionally, which is necessary for each. The mounting area can be greatly reduced. In addition, since the electrical connection processing between the white LED 4 and the circuit component unit 11 is performed by wiring inside the interposer substrate 12, external wiring can be simplified, wiring area on the surface can be greatly reduced, and further miniaturization is possible. become. Furthermore, since the LED flashlight unit 5 and the circuit component unit 11 are not directly bonded and are integrated with the interposer substrate 12 interposed therebetween, the intermediate interposer substrate 12 relaxes the mutual thermal expansion difference and generates thermal stress. Suppressing and maintaining good reliability. In addition, by integrating the LED flashlight unit 5 and the circuit component unit 11, it is possible to reduce conventionally required Zener diodes and improve electrostatic resistance.

  Moreover, since the circuit component part 11 is resin-molded and protected by the resin sealing part 13, the driver IC chip 3 and the coil 2 are not directly brought into contact with the mother board 16 during mounting, and the impact resistance is improved. Environmental characteristics such as moisture resistance are greatly improved. Further, as compared with the case of resin molding integrally with the white LED 4, a high degree of freedom is obtained in the resin material and the sealing shape, and a suitable resin can be selected and sealed in the circuit component portion 11.

Furthermore, in the mounting structure of the light emitting device 10 according to the present embodiment, since the light emitting device 10 is mounted and the circuit component unit 11 and the board side circuit unit 17 are connected to form a drive circuit, the drive mounted on the mother board 16 is provided. The number of circuit components can be reduced, the mounting area can be greatly reduced, and the mounting operation can be simplified.
Moreover, since the resin sealing part 13 is inserted and mounted in the hole 16b of the motherboard 16, the resin sealing part 13 is accommodated in the mother board 16, so that the entire thickness can be reduced in the mounted state. Further, by inserting the resin sealing portion 13 which is a convex portion into the corresponding hole portion 16b, positioning and connection between the external connection terminal 15 and the corresponding electrode pad 16c during mounting can be easily performed. .

Next, a second embodiment according to the present invention will be described with reference to FIG.
In the following description, the same constituent elements described in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The difference between the second embodiment and the first embodiment is that, in the first embodiment, the periphery of the external connection terminal 15 is exposed on the back surface of the interposer substrate 12 to form the resin sealing portion 13 as a convex portion. On the other hand, in the light emitting device 20 of the second embodiment, as shown in FIG. 6, the side end surfaces of the LED flashlight unit 5, the interposer substrate (double-sided substrate) 22, and the resin sealing unit 23 are flush with each other. The entire structure is a cubic shape or a rectangular parallelepiped shape, and the external connection terminal 25 extends to the side end face of the resin sealing portion 23.

Further, in the first embodiment, the resin sealing portion 13 of the convex portion is mounted by being inserted into the hole 16b of the mother board 16, whereas in the second embodiment, the surface of the mother board 26 (mounting substrate) is flat. This is different in that the light emitting device 20 is mounted on the part.
Further, in the first embodiment, the interposer substrate 12 which is a multilayer wiring substrate having a plurality of wiring resin layers is used, whereas in the second embodiment, a metal core 22a such as Cu (copper) is formed in any layer. This is different in that a multi-layer substrate 22 is used. In the multilayer substrate 22 as well, the wiring is provided inside and the components are electrically connected as in the first embodiment.
In the second embodiment, the entire light emitting device 20 has a cubic shape, but may have a rectangular parallelepiped shape.

In the second embodiment, since the entire light emitting device 20 has a cubic shape, that is, a block shape, it is easy to surface-mount on the plane of the mother board 26 and to the side end face of the resin sealing portion 23 that is in direct contact with the mother board 26. Since the external connection terminal 25 is formed to extend, it can be easily connected and fixed to the connection pad 16b on the mother board 26 with the solder 16d at the time of mounting.
In addition, since a so-called metal core substrate, which is a printed wiring board having a built-in metal core 22a and excellent heat dissipation characteristics, is adopted as the multilayer substrate 22, heat dissipation is taken into consideration in consideration of heat generation of the LED flashlight unit 5 and the circuit component unit 11. The reliability can be improved.

  The technical scope of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In the present invention, the LED flashlight unit 5 uses the white LED 4 that transmits the light emitted from the blue LED to the covering member mixed with the phosphor to emit white light, but other light emitting elements may be used. For example, an LED including three LEDs of red, green, and blue, a single color LED (infrared, red, green, blue, ultraviolet, etc.), an LD (semiconductor laser), or an organic EL element may be used. . It is particularly suitable for a device that requires a drive circuit such as a booster circuit for a light emitting element.

In each of the above embodiments, the driver IC chip 3 and the coil 2 are included in the circuit component unit 11 as a part of the drive circuit. However, either one may be used, and another component (resistor or capacitor) if space is allowed. Etc.) may be included. Further, the coil boost type is adopted as the drive circuit, but other boost circuits such as a charge pump type using a capacitor may be adopted.
Moreover, although each said embodiment is used for the auxiliary light source of the mobile telephone with a camera function, you may employ | adopt for another electronic device. For example, you may employ | adopt for the backlight for liquid crystal displays, etc. of an auxiliary light source of other electronic devices with camera functions (PDA, digital video camera, etc.) and portable electronic devices (mobile phones, PDAs, etc.).

It is the top view and side view which show the light-emitting device of 1st Embodiment concerning this invention. It is an AA line arrow directional view of FIG. In the light-emitting device of 1st Embodiment, it is a reverse view which shows connection relationship collectively. In the mounting structure of the light-emitting device of 1st Embodiment, it is a top view which shows the connection relationship collectively. It is sectional drawing which shows the mounting structure of the light-emitting device of 1st Embodiment. It is sectional drawing which shows the mounting structure of the light-emitting device of 2nd Embodiment which concerns on this invention. In the conventional light emitting device according to the present invention and its mounting structure. It is a top view which shows connection relation collectively.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Coil, 3 ... Driver IC chip (IC chip | tip for booster circuits), 4 ... White LED, 5 ... LED flash light part (light emission part) 10, 20 ... Light-emitting device, 11 ... Circuit component part, 12, 22 ... Interposer substrate (double-sided substrate), 13, 23 ... Resin sealing portion, 15, 25 ... External connection terminal, 16, 26 ... Mother board (mounting substrate), 16b ... Hole, 16c ... Electrode pad, 22 ... Multilayer substrate, 22a ... Metal core

Claims (9)

A light emitting unit having a light emitting element;
A circuit component portion constituting at least a part of a drive circuit electrically connected to the light emitting element;
A double-sided board having the light emitting portion disposed on the front surface and the circuit component portion disposed on the back surface, wherein the light emitting element and the circuit component portion are electrically connected by internal wiring. A light emitting device characterized.   The light emitting device according to claim 1, further comprising a resin sealing portion that seals the circuit component portion with a resin on a back surface of the double-sided substrate.   The light emitting device according to claim 2, wherein the resin sealing portion is formed as a convex portion on the back surface of the double-sided substrate. The side end surfaces of the light emitting part, the double-sided substrate, and the resin sealing part are arranged flush with each other, and the whole is a cubic shape or a rectangular parallelepiped shape,
An external connection terminal for connecting to an external circuit is provided on the side end surface of the double-sided board,
The light emitting device according to claim 2, wherein the external connection terminal is formed to extend to a side end surface of the resin sealing portion.   5. The light-emitting device according to claim 1, wherein the double-sided substrate is a multilayer substrate, and a metal core is disposed in any layer of the multilayer substrate. The light-emitting element is a blue light-emitting diode element that emits white light by mixing a YAG phosphor into a covering member,
6. The light emitting device according to claim 1, wherein the circuit component unit includes at least one of a booster circuit IC chip and a coil or a capacitor of the light emitting element. The light emitting device according to any one of claims 1 to 6,
A mounting structure for a light emitting device, comprising: a mounting substrate having a mounting region for mounting the light emitting device and a substrate side circuit portion connected to the circuit component portion and constituting the driving circuit. On the back surface of the double-sided board, a resin sealing portion is provided by sealing the circuit component portion with a resin.
The mounting structure of the light emitting device according to claim 7, wherein the mounting substrate has a recess or a hole into which the resin sealing portion is inserted in the mounting region. An external connection terminal for connecting to an external circuit is provided at a side end of the double-sided board,
The resin sealing portion is formed by exposing the periphery of the external connection terminal,
The light emitting device according to claim 8, wherein an electrode pad corresponding to the external connection terminal is provided on a surface of the mounting substrate in a state where the resin sealing portion is inserted into the concave portion or the hole portion. Implementation structure.

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