JP2009038160A - Light emitting element storage package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive light emitting element storage package which is superior in mountability and prevents the cost for mounting from increasing, as a package for flip-chip mounting a light emitting element. <P>SOLUTION: The light emitting element storage package has a pair of planar ceramic bumps 14 and 14a which project from a top surface of a planar ceramic base 13 made of one or a plurality of junction bodies and are made of the same ceramic with the ceramic base 13, and electrode terminal pads 15 and 15a which are made of metal conductor films and are disposed so as to mounting the light emitting element 11 on top surfaces of the ceramic bumps 14 and 14a on a flip-chip basis in a straddling state, and also has an insulation space where the top surface of the ceramic base 13 is exposed between the electrode terminal pads 15 and 15a, wherein the top surfaces of the electrode terminal pads 15 and 15a are at nearly the same height from the top surface of the ceramic base 13. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light emitting element storage package for mounting and storing a semiconductor light emitting element such as a light emitting diode (hereinafter referred to as an LED) on a ceramic bump in a flip chip manner.

Conventionally, in order to accommodate light emitting elements such as LEDs, a light emitting element accommodating package made of resin or ceramic has been used. On the other hand, light-emitting elements that require high light output, such as general lighting, backlights for large-screen LCDs, and lamps for automobiles, consume more power and emit light without removing the heat generated by the light-emitting elements. There is a problem that a high light output cannot be obtained due to an increase in the temperature of the element and a decrease in luminous efficiency. When such a light-emitting element is housed in a resin-made light-emitting element housing package, since the thermal conductivity of the resin is low, the high heat generated when the light output is increased by increasing the input power to the light-emitting element is removed. In other words, the temperature of the light-emitting element rises and high light output cannot be obtained. In addition, since the resin package is further heated when the package is mounted with lead-free solder or the like, the resin package has a problem of heat resistance of the resin. Furthermore, since a resin package uses many light emitting elements including ultraviolet light as a light emitting element, it has a problem of resin light resistance (UV degradation). Therefore, recently, a package made of a ceramic made of alumina (Al ₂ O ₃ ), aluminum nitride (AlN), or the like that has high heat conductivity, heat resistance, light resistance, and excellent heat dissipation is used as the light emitting element storage package. Are increasingly being used.

  On the other hand, conventionally, several mounting methods have been considered in order to form electrical continuity of light emitting elements housed in a light emitting element housing package. For example, in this mounting method, after a light emitting element is bonded to a die bond pad provided in advance in a light emitting element storage package, an electrode pad provided on the upper surface of the light emitting element using a bonding wire made of Au wire, and a light emitting element storage There is a wire bond system in which wire bond pads of a package are connected. However, in this wire bonding method, a bonding wire exists on the upper surface side of the light emitting element, and acts to block light emission from the light emitting element, so that the light emission efficiency from the light emitting element is lowered. Therefore, in this mounting method, a brazing material such as Au—Sn is vapor-deposited in advance on the electrode pad provided on the lower surface of the light emitting element, and the light emitting element is directly applied to the electrode terminal pad of the light emitting element storage package through this brazing material. A flip-chip system that releases the upper surface side of the light-emitting element so as to be connected has been introduced. In this flip chip method, an Au bump is formed on the electrode pad provided on the lower surface of the light emitting element by an electrolytic plating method, a transfer bump method, a ball bonding method or the like, and the light emitting element storage package is provided via the Au bump. There is also a method of releasing the upper surface side of the light emitting element by directly connecting the light emitting element to the electrode terminal pad.

  In a conventional light emitting element storage package, a light emitting element having a pair of positive and negative electrodes on the same surface side is formed on the surface of an insulating substrate made of resin or the like through bumps previously attached to the light emitting element by a flip chip method. A package that is electrically connected to a wiring pattern is disclosed. The light emitting element storage package has no shadow electrode on the light emitting surface side of the light emitting element, increases the light emitting area, and reflects downward light from the light emitting layer to the reflective layer. As a whole, the light extraction efficiency can be improved (for example, see Patent Document 1).

  In addition, the conventional light emitting element storage package has a mounting portion on which the light emitting element is mounted in the central portion of the upper main surface, and has an insulating ceramic or resin in which a wiring conductor led out from the mounting portion to the outside is formed. A base body made of a body, a frame body made of a metal attached to an outer peripheral portion of the upper main surface of the base body so as to surround the mounting portion, and an inner peripheral side having an inclined surface extending outward and upward; There is disclosed a package including a heat sink made of metal joined to a central portion of a lower main surface. The light-emitting element storage package reflects light emitted from the light-emitting element well on the inner peripheral side of the frame body and radiates the light uniformly and efficiently, and at the same time, the light intensity due to temperature change, the light emission angle, and the light A stable optical characteristic in which the intensity distribution does not change is obtained (for example, see Patent Document 2).

JP-A-11-168235 JP 2004-259958 A

However, the conventional light emitting element storage package as described above has the following problems.
(1) In a light emitting element storage package in which a light emitting element is mounted in a flip-chip system, a brazing material such as Au-Sn is vapor-deposited in advance on an electrode pad provided on the lower surface of the light emitting element, and the light emitting element is interposed through this brazing material The light emitting element is directly connected to the electrode terminal pad on the upper surface of the flat ceramic substrate of the storage package. In order to realize this, since the thickness of the brazing material of the electrode pad of the light emitting element formed by vapor deposition is thin (thickness of about 2 μm or less), the electrode terminal pad for direct bonding to the electrode terminal pad of the light emitting element storage package Excellent flatness (Rmax 1 μm or less) is required between the two electrode terminal pads including the area. However, in order to realize excellent flatness between the two electrode terminal pads on the upper surface of the flat ceramic substrate and the electrode terminal pads, the upper surface of the ceramic substrate is polished or further deposited, sputtered, etc. Therefore, it is necessary to form a metallized film by a thin film forming method using the above method, which causes an increase in cost for manufacturing a package for housing a light emitting element.
(2) In the light emitting element storage package in which the light emitting element is mounted by the flip chip method, an Au bump is formed on an electrode pad provided on the lower surface of the light emitting element, and a flat plate of the light emitting element storage package is formed through the Au bump. The light emitting element is directly connected to the electrode terminal pad on the upper surface of the ceramic substrate. In order to realize this, an expensive device, for example, an Au bump forming device in the ball bonding method, a leveling device for aligning the height, an ultrasonic device for bonding, and the like are required. This is causing an increase in cost.

  The present invention has been made in view of such circumstances, and as a package for mounting a light-emitting element in a flip-chip system, it is excellent in mountability and inexpensive light-emitting element storage that prevents an increase in cost for mounting. The purpose is to provide a package.

  The light-emitting element storage package according to the present invention that meets the above-described object is a pair of flat ceramics made of the same ceramic as the ceramic base, protruding from the upper surface of the flat ceramic base consisting of one or a plurality of joined bodies. Bumps and electrode terminal pads made of metal conductor films for mounting the light emitting elements on the upper surfaces of the respective ceramic bumps so as to be sandwiched in a flip chip manner, and the upper surface of the ceramic substrate between the respective electrode terminal pads And the height from the upper surface of the ceramic substrate to the upper surface of each electrode terminal pad is substantially the same.

  Here, it is preferable that the light emitting element storage package is provided by laminating ceramic bumps on a ceramic base and simultaneously firing the metal conductor film.

  Another light emitting element storage package according to the present invention that meets the above-mentioned object is bonded to the upper surface of a metal conductor pad made of a pair of metal conductor films on the upper surface of a flat ceramic substrate made of one or a plurality of bonded bodies. A pair of hemispherical metal bumps made of the same metal conductor as the protruding metal conductor film, and a flat surface for mounting the light emitting element on the top of each metal bump in a flip-chip manner, or It has a spherical surface and an insulating space in which the upper surface of the ceramic substrate is exposed between each metal conductor pad and metal bump, and further, from the upper surface of the ceramic substrate to the flat surface of each metal bump or the spherical surface. The height is substantially the same.

  Here, the light emitting element storage package is preferably provided by applying metal bumps to the upper surface of the metal conductor pads with a dispenser and simultaneously firing the ceramic base.

  The light emitting element storage package according to claim 1 or claim 2 dependent thereon is a pair of ceramics that is the same as the ceramic base and protrudes from the upper surface of a flat ceramic base made of one or a plurality of joined bodies. Plate-like ceramic bumps, and electrode terminal pads made of a metal conductor film for mounting the light emitting element on the upper surface of each ceramic bump so as to be sandwiched in a flip chip manner, and between the electrode terminal pads In addition, there is an insulating space in which the upper surface of the ceramic substrate is exposed, and the height from the upper surface of the ceramic substrate to the upper surface of each electrode terminal pad is substantially the same, so a thin brazing material is applied to the electrode pad. Ceramic that protrudes from the upper surface of the ceramic substrate without affecting the flatness of the ceramic substrate by bridging the light emitting element The upper surface of the electrode on the terminal pad of the amplifier is placed on the electrode pads of the light emitting element can be mounted, easy mounting, can be provided at low cost package for housing a light-emitting element capable of preventing an increase in cost for implementation.

  In particular, in the light emitting element storage package according to claim 2, since the ceramic bumps are laminated on the ceramic base and fired simultaneously with the metal conductor film, the pair of ceramic bumps partially protrude from the ceramic base. It is a turret-like shape, and the metal conductor film on the top surface can be made flat with less influence from warping and waviness of the ceramic base, making it easy to mount light-emitting elements and preventing cost increase for mounting An element storage package can be provided at low cost.

  The light emitting element storage package according to claim 3 or claim 4 dependent thereon is a metal conductor pad comprising a pair of metal conductor films on the upper surface of a flat ceramic substrate comprising one or a plurality of joined bodies. A pair of hemispherical metal bumps made of the same metal conductor as the metal conductor film protruding and bonded to the upper surface, and a flat surface for mounting the light emitting element on top of each metal bump in a flip-chip manner And an insulating space in which the upper surface of the ceramic substrate is exposed between the metal conductor pads and the metal bumps, and the flat surfaces or spheres of the metal bumps from the upper surface of the ceramic substrate. Since the height to the surface is almost the same, the light emitting element with a thin brazing material applied to the electrode pad is bridged and affected by the flatness of the ceramic substrate. The electrode pad of the light emitting element can be mounted by mounting it on the flat surface of the upper surface of the metal bump protruding from the upper surface of the metal conductor pad or on the spherical surface, and it is excellent in mountability and prevents an increase in cost for mounting. It is possible to provide a light emitting element storage package that can be manufactured at low cost.

  In particular, in the light emitting element storage package according to claim 4, since the metal bumps are provided on the upper surface of the metal conductor pad by a dispenser and fired simultaneously with the ceramic base, the pair of metal bumps are provided on the ceramic base. Each flat surface pressed from the upper surface of the metal conductor film is pressed, or a spherical surface with the upper surface remaining in a shape applied with a dispenser, and a flat surface or sphere that is less affected by warping or waviness of the ceramic substrate. Thus, a light emitting element storage package that can be formed on the surface, has excellent mountability of the light emitting element, and can prevent an increase in cost for mounting can be provided at low cost.

Subsequently, the best mode for carrying out the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention.
1A and 1B are a plan view, a longitudinal sectional view taken along line AA ′, and FIGS. 2A and 2B, respectively, of the light emitting element storage package according to the embodiment of the present invention. These are the top view of the modification of the package for the said light emitting element accommodation, and a BB 'line longitudinal cross-sectional view, respectively.

As shown in FIGS. 1A and 1B, a light emitting element storage package 10 according to an embodiment of the present invention has a rectangular shape, a polygonal shape, a circular shape, or the like in plan view. In the center portion, a cavity portion 12 made of a rectangle, a polygon, a circle or the like is provided in plan view for mounting the light emitting element 11 such as an LED. The light emitting element storage package 10 includes a flat ceramic substrate made of a bonded body in which one piece or a plurality of pieces such as alumina (Al ₂ O ₃ ), aluminum nitride (AlN), and low-temperature fired ceramic are joined. 13 is used. The light emitting element storage package 10 includes a pair of flat ceramic bumps 14 and 14a that protrude from the upper surface of the ceramic base 13 and are made of the same ceramic as the ceramic base 13 or a pair of plural ceramic bumps. . The upper surface of each of the ceramic bumps 14 and 14a is made of a metal conductor film for mounting the light emitting element 11 so as to straddle the flip chip method, and each of the electrode terminal pads 15 is a pair of positive and negative electrodes. , 15a. In the light emitting element storage package 10, the electrode terminal pads 15 and 15 a are electrically connected to the upper and lower layers of the ceramic bumps 14 and 14 a, and the upper and lower layers of the ceramic substrate 13 are electrically connected to each other. For this purpose, the external connection terminal pad 18 provided on the lower surface of the ceramic base 13 is formed in an electrically conductive state via the vias 16 and the conductor wiring patterns 17 between the layers of the ceramic base 13.

  In addition, the light emitting element storage package 10 is formed on the upper surfaces of the ceramic bumps 14 and 14a, respectively, and forms a pair of positive and negative electrodes, for example, a positive electrode terminal pad 15 and a negative electrode terminal pad 15a. There is an insulating space between which the upper surface of the ceramic substrate 13 is exposed. This insulation space prevents a short circuit between the electrode terminal pad 15 and the electrode terminal pad 15a. Further, the light emitting element storage package 10 has substantially the same height from the upper surface of the ceramic substrate 13 to the upper surfaces of the metal conductor films of the respective electrode terminal pads 15 and 15a. Accordingly, the light emitting element 11 can be accurately mounted in parallel with the ceramic base 13 between the electrode terminal pad 15 and the electrode terminal pad 15a, and the light emitted from the light emitting element 11 can be accurately emitted forward. become.

  In the light emitting element storage package 10, the cavity 12 for storing the light emitting element 11 usually reflects the ceramic base 13 for mounting the light emitting element 11 and the light from the light emitting element 11 joined thereto. It is formed with the reflector 19 for making it. The reflector 19 is made of metal, ceramic, resin, or the like. The material of the reflector 19 is not particularly limited, but a material having a high reflectance of light emission from the light emitting element 11 is preferable. Moreover, it is preferable that the reflector 19 has a tapered shape in which the opening wall surface of the cavity portion 12 widens the opening forward in order to condense light emitted from the light emitting element 11 forward. It should be noted that the reflector 19 and the ceramic base 13 can be bonded using a bonding material such as resin, glass, or brazing material. Further, when the reflector 19 is made of ceramic, it can be laminated on the ceramic substrate 13 and formed integrally.

In the light emitting element storage package 10 described above, the ceramic bumps 14 and 14a are ceramic green sheets constituting the ceramic green sheet constituting the ceramic base 13 after screen printing using a conductor paste constituting the metal conductor film on the ceramic green sheet. The laminated body laminated on the sheet may be provided by, for example, simultaneously firing the ceramic and the conductor metal at a high temperature of about 1550 ° C. (when the ceramic is Al ₂ O ₃ ) in a reducing atmosphere.

In this light emitting element storage package 10, a relatively inexpensive Au—Sn brazing material is deposited on the electrode pad of the light emitting element 11, even for a large light emitting element 11 having a size of ^□ 0.9 mm or more. Therefore, since it can be easily mounted on the electrode terminal pads 15 and 15a on the upper surfaces of the ceramic bumps 14 and 14a, it can be used as an inexpensive package on which the large light emitting element 11 can be mounted.

Next, another light emitting element housing package 10a according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIGS. 2A and 2B, the light emitting element storage package 10a has a rectangular shape, a polygonal shape, a circular shape, or the like in a plan view in the same manner as the light emitting element storage package 10. In the center portion, a cavity portion 12 made of a rectangle, a polygon, a circle or the like is provided in plan view for mounting the light emitting element 11 such as an LED. The light-emitting element storage package 10a uses a flat ceramic substrate 13 made of a bonded body in which one piece or a plurality of pieces such as alumina, aluminum nitride, and low-temperature fired ceramic are joined. The light emitting element storage package 10a is the same as the metal conductor film protruding from the upper surface of the metal conductor pads 20 and 20a made of a pair of metal conductor films or a pair of upper surfaces of the ceramic base 13 or a plurality of pairs. Each of the metal conductors includes a pair of positive and negative electrodes, or a pair of hemispherical metal bumps 21 and 21a. And on each metal bump 21 and 21a, it has the flat surface or spherical surface for mounting the light emitting element 11 so that it may straddle by a flip-chip system. The metal conductor pads 20 and 20a and the metal bumps 21 and 21a are ceramic via vias 16 for electrically connecting the upper and lower layers of the ceramic substrate 13 and the conductor wiring pattern 17 between the layers of the ceramic substrate 13. The external connection terminal pad 18 provided on the lower surface of the base 13 is in electrical conduction. In the light emitting element storage package 10 a, as in the light emitting element storage package 10, a cavity portion 12 for storing the light emitting element 11 is usually formed of a ceramic base 13 and a reflector 19. The reflector 19 is not particularly limited in material as in the case of the light emitting element storage package 10, but preferably has a high reflectance of light emitted from the light emitting element 11. In order to condense light emitted from the front, it is preferable that the opening wall surface of the cavity portion 12 has a tapered shape that widens the opening forward.

  The light emitting element storage package 10a has an insulating space in which the upper surface of the ceramic substrate 13 is exposed between the metal conductor pads 20, 20a and the metal bumps 21, 21a. By this insulating space, the metal conductor pad 20 and the metal bump 21 and the metal conductor pad 20a and the metal bump 21a are prevented from being short-circuited. Furthermore, the light emitting element storage package 10a has substantially the same height from the upper surface of the ceramic substrate 13 to the flat surfaces or spherical surfaces of the respective metal bumps 21 and 21a. Thus, the light emitting element 11 can be accurately mounted in parallel with the ceramic base 13 between the metal bump 21 and the metal bump 21a, and the light emitted from the light emitting element 11 can be accurately emitted forward. .

  In the light emitting element storage package 10a, the metal bump 21 is applied to the upper surface of the metal conductor pad 20, the metal bump 21a is applied to the upper surface of the metal conductor pad 20a, and the conductive metal paste constituting the metal bumps 21 and 21a is applied by a dispenser. It is preferable that the ceramic green sheet constituting the ceramic base 13 and the ceramic and the conductor metal are simultaneously fired at a high temperature of about 1550 ° C. in a reducing atmosphere.

In this light emitting element storage package 10a, a relatively inexpensive Au—Sn brazing material is deposited on the electrode pad of the light emitting element 11 even for a small light emitting element 11 having a size of ^□ 0.5 mm or less. Thus, the metal bumps 21 and 21a can be easily mounted on the flat surface or the spherical surface of the metal bumps 21 and 21a, so that it can be used as an inexpensive package on which the small light emitting element 11 can be mounted.
The medium-sized light-emitting element 11 having a size of about ^□ 0.5 mm to 0.9 mm can be mounted on any of the light-emitting element storage packages 10 and 10a, and can be provided as an inexpensive package. .

  In the light emitting element storage package 10, 10 a, after the light emitting element 11 is mounted in the cavity portion 12, the cavity portion 12 is filled with a resin containing a phosphor, and a lens is resinated on the opening peripheral portion of the reflector 19. They are joined using an adhesive or the like.

  Here, a manufacturing method in the case where alumina which is an example of ceramic is used for the ceramic base 13 used in the light emitting element storage packages 10 and 10a will be described. For this preparation, first, a powder obtained by adding an appropriate amount of a sintering aid such as magnesia, silica, calcia to alumina powder, a plasticizer such as dioctyl phthalate, a binder such as acrylic resin, and toluene, xylene, alcohol A solvent such as the like is added and sufficiently kneaded, and then defoamed to produce a slurry having a viscosity of 2000 to 40000 cps. Next, the slurry is formed into a roll-like sheet having a thickness of, for example, 0.25 mm by a doctor blade method or the like, and cut into an appropriate size to produce a ceramic green sheet.

  The ceramic green sheet is provided with a through hole for the via 16 for forming conduction between the upper layer and the lower layer at a predetermined position using a punching die, a punching machine, or the like. Next, the ceramic green sheet is filled with a through hole for the via 16 by screen printing using a metal conductor paste made of a refractory metal such as tungsten or molybdenum, or is electrically connected to the light emitting element 11. Therefore, printed conductor patterns for the conductor wiring pattern 17, the electrode terminal pads 15 and 15 a, the external connection terminal pad 18, and the metal conductor pad 20 are formed on the surface. A plurality of ceramic green sheets on which printing has been completed are stacked to form a laminate. A ceramic green sheet for the ceramic bump 14 is also laminated for the light emitting element storage package 10. In addition, for the light emitting element storage package 10a, the conductive metal paste for the metal bumps 21 and 21a is respectively applied to the upper surface of the conductive printed pattern for the metal conductive pad 20 with a dispenser. Next, the ceramic substrate 13 is manufactured by simultaneously firing the refractory metal and the ceramic green sheet in a firing furnace in a reducing atmosphere.

  The light-emitting element storage package of the present invention can be used for lighting, a display, or the like having a light-emitting efficiency by mounting a light-emitting element such as an LED.

(A), (B) is a top view of the light emitting element storage package which concerns on one embodiment of this invention, respectively, and an A-A 'line longitudinal cross-sectional view. (A), (B) is the top view of the modification of the package for the said light emitting element accommodation, respectively, and the B-B 'line longitudinal cross-sectional view.

Explanation of symbols

  10, 10a: Light-emitting element storage package, 11: Light-emitting element, 12: Cavity, 13: Ceramic base, 14, 14a: Ceramic bump, 15, 15a: Electrode terminal pad, 16: Via, 17: Conductor wiring pattern, 18: External connection terminal pad, 19: Reflector, 20, 20a: Metal conductor pad, 21, 21a: Metal bump

Claims (4)

  A pair of flat ceramic bumps made of the same ceramic as the ceramic base projecting from the top surface of the flat ceramic base made of one or a plurality of joined bodies, and a light emitting element on the top surface of each ceramic bump It has an electrode terminal pad made of a metal conductor film for mounting so as to be straddled by a flip chip method, and has an insulating space in which the upper surface of the ceramic substrate is exposed between the electrode terminal pads, The light emitting element storage package, wherein the height from the upper surface of the ceramic substrate to the upper surface of each electrode terminal pad is substantially the same.   2. The light emitting element storage package according to claim 1, wherein the ceramic bumps are provided on the ceramic substrate and are fired simultaneously with the metal conductor film.   A pair of metal conductors made of the same metal conductor as the metal conductor film projecting bonded to the upper surface of a metal conductor pad made of a pair of metal conductor films on the upper surface of a flat ceramic substrate made of one or more joined bodies A hemispherical metal bump, and a flat surface or a spherical surface for mounting the light emitting element so as to straddle the flip-chip method on each metal bump, and each of the metal conductor pad and the metal An insulating space in which the upper surface of the ceramic substrate is exposed between the bumps, and the height from the upper surface of the ceramic substrate to the flat surface or spherical surface of each of the metal bumps is substantially the same. A package for storing light emitting elements.   4. The light emitting element storage package according to claim 3, wherein the metal bumps are provided on a top surface of the metal conductor pad by a dispenser and fired simultaneously with the ceramic substrate. .

Images