Patent Application
20080169480
1. Field of the Invention
The invention relates to a semiconductor device, and in particular to an optoelectronic device package and a packaging method thereof.
2. Description of the Related Art
Currently, packaging of surface mount devices of light-emission diodes (SMD LED) is mainly divided into circuit and leadframe types. The leadframe SMD LED uses a metallic leadframe as substrate and injection molding for plastic grooves or compression molding, followed by cutting into SMD LED, as shown in
SMD LED produced by both methods exhibit insufficient heat resistance, especially when SMD components connected with board circuits pass through high temperature furnace (at about 250˜300° C.), the packaging resin for SMD LED lacks sufficient heat resistance. Since the packaging resin has a Tg temperature of only about 120° C. and a different coefficient of thermal expansion from that of the substrates or the leadframe, unusual defects often occur.
Another shortcoming is poor heat dissipation, due to poor thermal conductance of the packaging resins and substrates. Since the LED itself is a small heat-generating object, temperature increase affects emission efficiency and quality. Also encountered is reduction of emission intensity from miniaturization without groove reflector by more than one-fold (compared at an emission angle of 30°), due to difficulty in employing conventional process to make groove reflectors for SMD LED. Poor heat resistance and heat dissipation and difficulty in minimizing groove reflectors continue to present problems in conventional SMD LED fabrication.
The invention provides an optoelectronic device package comprising a substrate, a reflector formed on a first plane of the substrate, a cover bonded to the reflector to form a closed space, a plurality of microlenses formed on a first plane of the cover, a phosphor film formed on a second plane of the cover within the closed space, a thermal-conductive film formed on a second plane of the substrate, an electrode formed on the sidewall and the second plane of the substrate uncovered by the thermal-conductive film, and an optoelectronic device formed on the first plane of the substrate within the closed space.
The invention also provides a method of packaging an optoelectronic device, in which substrate is provided. A reflector is formed on a first plane of the substrate. An electrode is formed on the sidewall and a portion of a second plane of the substrate. A thermal-conductive film is formed on the second plane of the substrate uncovered by the electrode. An optoelectronic device is formed on the first plane of the substrate. A cover is provided. A plurality of microlenses are formed on a first plane of the cover. A phosphor film is formed on a second plane of the cover. The cover is bonded to the reflector to form a closed space containing the phosphor film and the optoelectronic device.
A detailed description is given in the following embodiments with reference to the accompanying drawings.
The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawing, wherein:
The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.
An optoelectronic device package of the invention is shown in
The reflector 14 is formed on a first plane 28 of the substrate 12. The cover 16 is bonded to the reflector 14 to form a closed space 30. The microlenses 18 are formed on a first plane 32 of the cover 16. The phosphor film 20 is formed on a second plane 34 of the cover 16 within the closed space 30. The thermal-conductive film 22 is formed on a second plane 36 of the substrate 12. The electrode 24 is formed on the sidewall 38 and the second plane 36 of the substrate 12 uncovered by the thermal-conductive film 22. The optoelectronic device 26 is formed on the first plane 28 of the substrate 12 within the closed space 30. The anode and cathode (not shown) of the optoelectronic device 26 are respectively electrically connected to the electrode 24.
The substrate 12 and the reflector 14 may comprise silicon. The cover 16 is transparent and may comprise glass or plastic such as high-temperature resistant plastic. The closed space 30 may be a vacuum or filled with a transparent colloid such as epoxy or air. The thermal-conductive film 22 may comprise various thermal-conductive materials, preferably a diamond film. The optoelectronic device 26 may be a semiconductor light source such as light-emission diode (LED) light source, laser light source, and organic light-emission diode (OLED) light source.
The optoelectronic device package 10 may further comprise electrostatic discharge (ESD) protection (not shown) formed on the substrate 12. The reflector 14 may further comprise a high-reflective metal film (not shown) formed thereon to improve the reflection thereof. Additionally, an isolation layer 40 is formed on the surface of the substrate 12. A conductive layer 42 is formed between the reflector 14 and the optoelectronic device 26 and the substrate 12. The optoelectronic device package 10 is a wafer level package (WLP).
Advantageously, the microlenses 18 and the phosphor film 20 are integrated on the cover 16. The thermal-conductive film 22, the electrode 24, and the electrostatic discharge (ESD) protection (not shown) are integrated on the substrate 12. The microlenses 18 formed on the cover 16 improve transmission and uniformity of light and the groove reflector 14 increases emission intensity. An optimal reliability of the optoelectronic device package 10 is achieved during fabrication due to use of high-temperature package materials such as glass and materials of similar coefficients of thermal expansion (CTE) of the reflector 14 and the cover 16, providing sufficient heat resistance. The thermal-conductive film 22 provides a superior thermal dissipation than silicon. The optoelectronic device 26 is electrically connected to the electrode 24 formed on the sidewall 38 and bottom 36 of the substrate 12 through the conductive layer 42 without formation of through holes in the substrate, significantly reducing cost. Additionally, mass production is achieved due to reduced package size.
A method of packaging an optoelectronic device of the invention is disclosed in
Referring to
Next, a substrate (not shown) is bonded on the first plane 28 of the substrate 12 and etched to form a reflector 14, as shown in
The substrate 12 is then ground from the second plane 36 to reduce the thickness thereof, as shown in
Next, the substrate 12 is etched from the second plane 36 to expose a portion of the conductive layer 42, forming a notch 44, as shown in
Referring to
Next, an electrode 24 is formed on the sidewall 38 and a portion of the second plane 36 of the substrate 12, as shown in
Referring to
Next, an optoelectronic device 26 is formed on the first plane 28 of the substrate 12, as shown in
Referring to
Next, referring to
A cover 16 with a plurality of microlenses 18 and a phosphor film 20 formed thereon is bonded to the reflector 14 to form a closed space 30 filled with the transparent colloid 48, as shown in
Finally, the structure as shown in
While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
