Patent Application
20180190627
The disclosure relates in general to a light-emitting device, and more particularly to a light-emitting device with high process yield and high device reliability.
Since light emitting diode (LED) advantageously possesses the features of small volume, high brightness, short response time and long operating life, the light-emitting device formed of LEDs has been widely used in various fields such as illumination and sign board or used as the backlight source of display.
The current manufacturing process of light-emitting device mainly includes following steps. Firstly, the LEDs are packaged. Then, the packaged LEDs are soldered on the printed circuit board (PCB) using the surface mount technology (SMT) to form an electrical path and obtain a light-emitting device.
According to the most commonly used method of the surface mount technology, the LEDs are electrically connected to the PCB using solder. However, the method has its problem. That is, during the bonding or lamination process, the solder may easily overflow, and elements may contact each other through the melted solder and become short-circuited, and further make the light-emitting device fail.
Therefore, it has become a prominent issue for related technical staffs in the field to develop a light-emitting device capable of overcoming the above disadvantages and at the same time increasing the process yield and the device reliability.
The invention is directed towards a light-emitting device.
The light-emitting device of the invention includes a light-emitting unit, an electrode unit, and an insulating unit.
The light-emitting unit includes an illuminator and a packaging sealant. The illuminator generates an optical energy by way of electroluminescence, and the packaging sealant is formed on a part of a surface of the illuminator.
The electrode unit includes a first electrode and a second electrode respectively formed on the surface of the illuminator on which no packaging sealant is formed.
The insulating unit is formed on the surface of the light-emitting unit and includes a first insulating layer protruded between the first electrode and the second electrode.
When the light-emitting device of the invention is electrically connected to an external circuit board using solder, the insulating unit effectively separates the elements to avoid the elements being short-circuited by the solder overflowing. The invention not only increases process yield and device reliability but also reducing production cost.
The above and other aspects of the invention will become better understood with regard to the following detailed description of the preferred but non-limiting embodiment (s). The following description is made with reference to the accompanying drawings.
It should be noted that in the embodiments of the invention disclosed below, similar or identical elements are designated by the same reference numeral. Relevant technical contents, features and effects of the invention are disclosed in following descriptions.
Refer to
The light-emitting unit 2 includes an illuminator 21, a packaging sealant 22, and a transparent substrate 23. The illuminator 21 generates an optical energy by way of electroluminescence, and has a first surface 211, a second surface 212 opposite to the first surface 211, and a circumferential surface 213 connecting the first surface 211 and the second surface 212. The packaging sealant 22 is formed on the circumferential surface 213 and the first surface 211, and has a third surface 221 and a fourth surface 222 opposite to the third surface 221. The illuminator 21 is disposed towards the third surface 221 from the fourth surface 222 and covered by the packaging sealant 22. The transparent substrate 23 is correspondingly formed above the first surface 211 and connected to the third surface 221 of the packaging sealant 22.
The electrode unit 3 includes a first electrode 31 and a second electrode 32 respectively formed on the second surface 212 of the illuminator 21.
It should be noted that the light-emitting unit 2 has a light output surface 24, and a bottom surface 25 opposite to the light output surface 24. The bottom surface 25 is composed of the second surface 212 of the illuminator 21 and the fourth surface 222 of the packaging sealant 22. The illuminator 21 has an N-type semiconductor (not illustrated) and a P-type semiconductor (not illustrated), and the first electrode 31 and the second electrode 32 electrically are connected to the N-type semiconductor and the P-type semiconductor, respectively. To put it in greater details, the illuminator 21 has an N-type semiconductor layer, a light-emitting layer formed on the N-type semiconductor layer, and a P-type semiconductor layer formed on the light-emitting layer. The first electrode 31 and the second electrode 32 are formed on the surface of the N-type semiconductor layer and the surface of the P-type semiconductor layer respectively.
In the first embodiment, detailed descriptions for the structure and material selection of the light-emitting unit 2 and the electrode unit 3 are omitted because these descriptions are generally known to any person ordinarily skilled in the technology field of the invention and are not the main technical features of the invention.
The insulating unit 4 is formed on the bottom surface 25, and includes a first insulating layer 41 protruded between the first electrode 31 and the second electrode 32. The first insulating layer 41 is formed of an insulating material, and can be formed between the first electrode 31 and the second electrode 32 by way of screen printing, UV curing, exposure and development, or 3D printing. In the first embodiment of the invention, the insulating unit 4 is disposed for the purpose of isolating the solder coated on the first electrode 31 from the solder coated on the second electrode 32 during the soldering process. Therefore, the insulating material used in the insulating unit 4 can resist high temperature during the manufacturing process. Exemplarily but not restrictively, the first insulating layer 41 is formed of a material selected from epoxy resin, photoresist, plastic, silicon dioxide (SiO2), silicone, or a combination thereof. These materials all possess excellent chemical resistance, heat resistance and mechanical properties.
It should be noted that the first insulating layer 41 can be protruded between the first electrode 31 and the second electrode 32 as indicated in
It should be noted that apart from being formed between the first electrode 31 and the second electrode 32 without contacting the first electrode 31 or the second electrode 32 as indicated in
Refer to
Refer to
It should be noted that the edges of the first insulating layer 41 and the second insulating layer 42 can be aligned with that of the illuminator 21 (as indicated in
It should be noted that in the third embodiment of the invention, the second insulating layer 42 further divides the first electrode 31 and the second electrode 32, which are separated by the first insulating layer 41, into two first electrode regions 311 and two second electrode regions 321, respectively. When the light-emitting device is electrically connected to an external circuit board in subsequent process, the first electrode regions 311 and the second electrode regions 321 can achieve alignment function and make the light-emitting device connected to the external circuit board more accurately.
Refer to
In the fourth embodiment of the invention, when the light-emitting device is electrically connected to an external circuit board by using solder, the recesses 44 not only provide alignment function but further limit the solder such that the solder will not overflow and make the elements become short-circuited or current leakage.
It should be noted that the first insulating layer 41 and the third insulating layer 43 can be protruded between the light-emitting unit 2 and the electrode unit 3, or as indicated in
Refer to
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Refer to
According to the light-emitting device illustrated in the first embodiment to the fifth embodiment of the invention, the first electrode 31 and the second electrode 32 are isolated by the insulating unit 4 to avoid the elements being short-circuited by the solder overflowing, not only effectively increasing process yield and device reliability, but further reducing production cost. On the other hand, in the light-emitting device of the invention, through the disposition of the first insulating layer 41 and the second insulating layer 42, the quantities of the first electrode regions 311 and the second electrode regions 321 can be flexibly adjusted to meet the requirements of product types or alignment assembly in subsequent process.
To summarize, when the light-emitting device of the invention is electrically connected to the external circuit board 5, the insulating unit 4 not only avoids the elements contacting each other and being short-circuited by the solder overflowing, but also advantageously increases process yield and device reliability and reduces production cost. Therefore, the light-emitting device of the invention really can achieve the objects of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.
This application is a continuation application of co-pending application Ser. No. 15/045,454, filed on Feb. 17, 2016, which claims the benefit of U.S. application Ser. No. 62/116,923, filed Feb. 17, 2015, the subject matter of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62116923 | Feb 2015 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15045454 | Feb 2016 | US |
| Child | 15896116 | US |
