JP4255015B2 - Optical semiconductor package - Google Patents

Description

  The present invention relates to an optical semiconductor package for connecting semiconductor chips by a flip-chip method, and more particularly, to an optical semiconductor package having a structure for reducing light loss due to light leakage when an optical semiconductor chip such as an LED is mounted. The present invention relates to a semiconductor package.

  In recent years, due to the downsizing and higher functionality of electronic devices, it has been required to improve the mounting density of electronic components on a printed wiring board. In particular, the mounting form of semiconductor chips has changed from surface mounting components to bare chip mounting in which semiconductor chips are mounted directly on a substrate, and among them, flip chip mounting (FC mounting) that can achieve the highest improvement in mounting density. Has been attracting attention. This FC mounting is a method in which chip electrodes and substrate electrodes are opposed to each other through protrusions called bumps, and face-down is used to collectively connect them. After mounting, an underfill (sealing agent) is poured between the semiconductor chip and the substrate. To do.

FIG. 8 shows a cross-sectional structure of a conventional optical semiconductor package 2 for mounting an optical semiconductor chip (LED 3) in FC. A resin such as polyimide, glass epoxy, or BT resin is used for the base substrate 4 used in the FC mounting method, and a pair of LEDs corresponding to the chip electrode portion 5 (the anode electrode and the cathode electrode) of the LED 3 is formed on the surface thereof. The substrate electrode portion 6 is patterned. The LEDs 3 are connected via bumps 7 so as to straddle the exposed surface (gap 8) of the base substrate 4 which is a space for insulating the pair of substrate electrode portions 6.
JP 2002-261119 A

  However, in the optical semiconductor package 2 having the above structure, since the gap 8 immediately below where the LED 3 is mounted is an exposed resin surface such as polyimide, light emitted from below the LED 3 is absorbed by the gap 8. There is a problem such as. Since there is light absorbed in the base substrate 4, about 10 to 20% of the amount of light emitted from the LED 3 in all directions is lost, causing a reduction in the overall light emission luminance.

  Accordingly, an object of the present invention is to provide an optical semiconductor package capable of suppressing light emission loss by preventing the light emitted from the LED from being absorbed into the base substrate and improving the overall luminance. is there.

  In order to solve the above problems, an optical semiconductor package of the present invention includes a base substrate and a substrate electrode portion provided on the base substrate and on which a chip electrode portion of the optical semiconductor chip is disposed. The base substrate is provided with a hole extending from a portion immediately below the arranged optical semiconductor chip to the back surface of the base substrate, and light emitted from the lower surface of the optical semiconductor chip on the back surface side of the base substrate corresponding to the hole portion. It is characterized in that a light reflecting portion for reflecting the light is provided.

  According to the present invention, when an optical semiconductor chip such as an LED is mounted on a base substrate, light emitted from the back surface side of the optical semiconductor chip is reflected by the light reflecting portion through the hole portion. Can be effectively prevented and returned to the upper surface of the base substrate. Therefore, by using the optical semiconductor package of the present invention, it is possible to form a high-luminance light-emitting optical device without optical loss.

  The light reflecting portion can be formed by etching a copper foil film formed on the base substrate surface into a predetermined shape in the same manner as the substrate electrode portion. Further, a higher light reflection effect can be obtained by forming a plated layer of gold or silver on the copper foil film exposed from the hole formed in the base substrate or on the inner surface of the copper foil film and the hole. be able to.

  The hole is formed to have substantially the same shape and width as the back surface (mounting surface) of the optical semiconductor chip, so that light emitted from the back surface side of the optical semiconductor chip is effectively reflected toward the top surface of the base substrate. be able to.

  A high-luminance light-emitting optical device can be formed by mounting an optical semiconductor chip such as an LED on the optical semiconductor package having the above-described configuration and sealing it with a transparent resin. In addition, a light emitting device having directivity can be formed by providing a reflective cup around the optical semiconductor chip.

  By forming the optical semiconductor chip with gallium nitride, blue light can be emitted. In addition, by including at least one of a fluorescent agent and a light diffusing agent in the resin material for sealing the optical semiconductor chip, it is possible to realize a blue light emitting device with high luminance and no uneven light emission.

  According to the optical semiconductor package of the present invention, when an optical semiconductor chip such as an LED is directly flip-chip connected to the base substrate, the amount of light leaking into the base substrate is suppressed, and conversely reflected toward the surface of the base substrate. The amount of light increases. Therefore, the optical semiconductor package is suitable for forming a high-luminance light-emitting optical device with little light emission loss.

  Embodiments of an optical semiconductor package according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a perspective view of an optical semiconductor package according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the optical semiconductor package.

  As shown in FIGS. 1 and 2, the optical semiconductor package 12 of the present invention is formed for mounting a light emitting device (LED 13) having a cathode electrode and an anode electrode, such as polyimide, glass epoxy, or BT resin. An insulating base substrate 14 made of resin, a pair of substrate electrode portions 16 formed from the front surface to the back surface of the base substrate 14, and a light reflecting portion formed on the surface opposite to the mounting surface of the LED 13 20 and a hole 19 in which an insulating portion 18 facing the pair of substrate electrode portions 16 is opened in the thickness direction of the base substrate 14, and gold or gold formed on the surface of the light reflecting portion 20 exposed from the hole 19. And a plated layer 21 made of silver.

  The substrate electrode portion 16 is divided into right and left at the center portion of the surface of the base substrate 14, one is a cathode electrode portion to which the cathode electrode of the LED 13 is connected, and the other is an anode electrode portion to which the anode electrode of the LED 13 is connected. It has become. The electrode provided on the back surface of the base substrate 14 and electrically connected to the substrate electrode portion 16 is a connection electrode portion 22 mounted on a device substrate such as a mother board (not shown).

  The substrate electrode part 16, the connection electrode part 22 and the light reflecting part 20 are formed by etching a copper foil film formed on both the front and back surfaces of the base substrate 14 into a predetermined pattern.

  As shown in FIGS. 1 and 2, a substrate electrode portion 16 is formed on the surface of the central portion of the base substrate 14 so as to face the insulating portion 18. As described above, the light reflecting portion 20 provided at the center of the back surface of the base substrate 14 is formed of the same copper foil film as the substrate electrode portion 16 and reflects light by closing the opened hole portion 19. Has an effect. By providing the light reflecting portion 20, it is possible to prevent light leakage and to suppress a decrease in luminance by reflection upward. Further, by forming a gold or silver plating 21 layer having a high light reflectivity in a portion exposed from the hole portion 19, a greater light reflection effect can be obtained.

  The hole portion 19 is formed by cutting the insulating portion 18 in contact with the back surface of the LED 13 in the thickness direction of the base substrate 14, and has a depth reaching the light reflecting portion 20. As shown in FIG. 3, the hole portion 19 is opened in the region of the insulating portion 18 where the back surface of the mounted LED 13 is hidden. By providing such a hole portion 19, the light reflecting portion 20 formed on the back surface of the base substrate 14 appears, and light emitted from below the LED 13 can be reflected upward. Further, the depth of the hole portion 19 varies depending on the thickness of the base substrate 14, but is provided so that the surface of the light reflecting portion 20 is completely exposed. When opening the holes 19, since the pitch width of the substrate electrode portion 16 and the base substrate 14 itself are thin, high-precision fine processing is required. For this reason, it is preferable to process the hole 19 by irradiating a laser beam. According to such a laser beam, a complicated insulating portion can be cut accurately and cleanly.

  The hole portion 19 and the light reflecting portion 20 are not limited to the shapes as shown in FIG. 3, and are formed according to the position of the chip electrode portion provided in the optical semiconductor chip to be mounted and the shape and size of the optical semiconductor chip. However, the reflection effect can be maximized by forming so as to cover the entire insulating portion 18 in contact with the back surface of the optical semiconductor chip.

  The LED 13 mounted on the optical semiconductor package 12 of this embodiment has a pair of chip electrode portions 15 (cathode electrode, anode electrode) on the lower surface, and a bump 17 is formed on each of them. Then, after the bumps 17 are placed on the substrate electrode portion 16, a conductive connection is achieved by performing a reflow process.

  4 and 5 show the structure of the optical semiconductor package of the second embodiment. As shown in FIG. 5, the substrate electrode portion of the optical semiconductor package 32 is composed of a cathode electrode 36a and an anode electrode 36b which are divided into right and left at a substantially central portion, and the cathode electrode 36a and the anode electrode 36b are Protruding portions 31 a and 31 b to which the LEDs 33 are connected via bumps 37 are formed at the opposite central portions. In order to avoid the protrusions 31a and 31b on which the chip electrode part of the LED 33 is placed, the hole 39 opened in the optical semiconductor package 32 of this embodiment is substantially as shown in the figure in order to make it as wide as possible. S-shaped. The hole 39 and the light reflecting portion 40 are not limited to the above shapes, but are formed according to the position of the chip electrode portion, the shape or size of the optical semiconductor chip provided in the optical semiconductor chip to be mounted. By setting the insulating part 18 hidden behind the semiconductor chip as wide as possible, the reflection effect can be maximized. In addition to the exposed surface of the light reflecting portion 40, the reflection effect can be further enhanced by forming the plated layer 41 of gold or silver on the inner peripheral surface of the hole 39.

  FIG. 6 shows a light emitting diode 11 in which an LED 13 is flip-chip mounted on the optical semiconductor package 12 and a resin sealing body 23 having translucency is formed thereon. In the optical semiconductor package 12 of this embodiment, the plating layer 21 is provided on both the exposed surface of the light reflecting portion 20 and the inner peripheral surface of the hole portion 19 in order to increase the reflection efficiency. 7 is arranged on the optical semiconductor package 12 so as to surround the LED 13, and a reflective cup 52 that controls the directivity of light emitted from the LED 13. A frame 53 is provided on the back side of the reflection cup 52 to support the reflection cup 52. The reflective cup 52 disposed so as to surround the LED 13 includes a film body held in a cup shape and a metal film formed on the surface of the film body. The resin sealing body 54 for sealing the LED 13 covers only the upper part of the LED 13 in the reflection cup 52. The resin sealing body 54 is formed in a convex lens shape. Therefore, since the light emitted from the LED 13 is collected in the same direction as the direction by the reflection cup 52, reflected light having a narrower directivity can be obtained. In the light emitting diode 51 having such a configuration, the light emitted from the LED 13 is given upward directivity by the reflection cup 52, but light scattering on the surface of the reflection cup 52 can be suppressed. Therefore, it becomes easy to control the directivity set in advance. In addition, when the resin sealing bodies 23 and 54 contain a fluorescent agent or a light diffusing agent, light emission with high brightness without unevenness can be obtained. When the light emitting diodes 11 and 51 are formed, the resin sealing bodies 23 and 54 are filled in the holes 19 provided in the base substrate 14. However, since they have translucency, the reflection efficiency is high. There is no decline.

  In the light emitting diodes 11 and 51 having the above configuration, the light emitted from the upper surface and the side surface of the mounted LED 13 goes straight through the resin sealing bodies 23 and 54 and is emitted to the outside, and emitted from the lower surface of the LED 13. The reflected light is reflected by the substrate electrode part 16 or the light leaking from the hole part 19 is reflected toward the back surface of the LED 13 by the light reflecting part 20 and the plating layer 21 such as gold or silver having high reflection efficiency. be able to. As a result, since the loss of light absorbed by the surface of the base substrate 14 out of the light emitted from the LED 13 can be suppressed as in the conventional case, the effect of improving the overall light emission luminance can be achieved. Further, since the substrate electrode portion 16 on which the LED 13 is mounted, the connection electrode portion 22 and the light reflecting portion 20 can efficiently dissipate the heat generated in the LED 13 to an external substrate such as a motherboard (not shown) or a housing, the thermal resistance value Can be kept low. As a result, there is little deterioration due to temperature change, and the life can be extended.

  In addition, when the said light emitting diodes 11 and 51 are made to light-emit blue, it becomes possible by employ | adopting a gallium nitride (GaN) type semiconductor element for LED13 to mount. Further, by mixing a fluorescent material or a light diffusing agent into the resin material for sealing the LED 13, high-luminance blue light emission without unevenness can be obtained.

1 is a perspective view of an optical semiconductor package according to a first embodiment of the present invention. It is sectional drawing when the optical semiconductor package of the said 1st Embodiment is cut | disconnected by the AA line. It is a principal part top view of the optical semiconductor package of the said 1st Embodiment. It is a perspective view of the optical semiconductor package of 2nd Embodiment which concerns on this invention. It is a principal part top view of the optical semiconductor package of the said 2nd Embodiment. It is sectional drawing which shows one Embodiment of the light emitting diode formed using the said optical semiconductor package. It is sectional drawing which shows one Embodiment of the light emitting diode with a reflective cup formed using the said optical semiconductor package. It is sectional drawing of the conventional optical semiconductor package.

Explanation of symbols

12 Optical semiconductor package 13 LED (Optical semiconductor chip)
14 Base substrate 15 Chip electrode portion 16 Substrate electrode portion 17 Bump 18 Insulating portion 19 Hole portion 20 Light reflecting portion 21 Plating layer

Claims (7)

In an optical semiconductor package having a base substrate and a substrate electrode portion provided on the base substrate and provided with a chip electrode portion of the optical semiconductor chip,
The base substrate is provided with a hole extending from a portion directly below the arranged optical semiconductor chip to the back surface of the base substrate, and light emitted from the bottom surface of the optical semiconductor chip on the back surface side of the base substrate corresponding to the hole portion. An optical semiconductor package comprising a light reflecting portion for reflecting light. The optical semiconductor package according to claim 1, wherein the light reflecting portion and the substrate electrode portion are formed by etching a copper foil film formed on a base substrate surface. 3. The optical semiconductor package according to claim 1, wherein a plated layer made of gold or silver is formed on a surface of the light reflecting portion exposed at a bottom portion of the hole portion, a surface of the light reflecting portion, and an inner peripheral surface of the hole portion. 4. The optical semiconductor package according to claim 1, wherein the hole is formed to have substantially the same width as the back surface of the optical semiconductor chip excluding the substrate electrode portion on which the chip electrode portion is disposed. 5. The optical semiconductor package according to claim 1, wherein a light emitting device is formed by flip-chip mounting an optical semiconductor chip on the base substrate and sealing the optical semiconductor chip with a transparent resin material. The optical semiconductor package according to claim 1, wherein a light emitting device including a reflective cup surrounding the optical semiconductor chip is formed on the base substrate. The optical semiconductor package according to claim 1, wherein the optical semiconductor chip is formed of gallium nitride and the resin material includes at least one of a fluorescent agent and a light diffusing agent.

Images