US-12628466-B2 - Encapsulation process method for wafer-level light-emitting diode dies

US12628466B2US 12628466 B2US12628466 B2US 12628466B2US-12628466-B2

Abstract

An encapsulation process method for wafer-level light-emitting diode dies is provided, in which a wafer structure having a plurality of light-emitting diode dies thereon is adhered to a temporary substrate, and by sequentially performing a laser cutting and a laser punch-through process, the light-emitting diode die turns to be conductive. Then, a transparent conductive film is sputtered thereon the die, and black matrix photoresist and quantum dot color filter are further disposed for performing a color conversion process. After that, the light-emitting diode dies are divided into package structures, and a glue removal process is used to separate the wafer structure from the temporary substrate, so that the wafer structure can be transferred to a target substrate. By employing the present invention, the conventional carrier board can be omitted, and the packaging yield of the vertical light emitting diode die packages is certainly optimized.

Inventors

Ai-Sen Liu
Hsiao-Lu CHEN
Yi-Chuan Huang
Hsiang-an Feng

Assignees

INGENTEC CORPORATION

Dates

Publication Date: 20260512
Application Date: 20230519
Priority Date: 20230308

Claims (20)

1 . An encapsulation process method for wafer-level light-emitting diode dies, comprising: providing a wafer structure, and disposing a plurality of light-emitting diode dies on the wafer structure; adhering the wafer structure having the plurality of light-emitting diode dies thereon to a temporary substrate, wherein each of the plurality of light-emitting diode dies includes a pad and a laser protectant is disposed on the pad; performing a laser cutting process such that a plurality of cutting lines is formed between the plurality of light-emitting diode dies, and the plurality of light-emitting diode dies are separated by a plurality of die areas through the plurality of cutting lines; performing a laser punch-through process according to each of the plurality of die areas such that one of the plurality of light-emitting diode dies in each of the plurality of die areas becomes an electrical conductor; removing the laser protectant, and providing a filler adhesive to fill the plurality of cutting lines, and sputtering a transparent conductive film on upper surfaces of the plurality of light-emitting diode dies; performing a color conversion process such that the plurality of light-emitting diode dies have different luminous color scales; performing a wheel cutting process to divide the plurality of light-emitting diode dies having different luminous color scales into a plurality of light-emitting diode packages; and separating the wafer structure having the plurality of light-emitting diode packages thereon from the temporary substrate, and transferring the wafer structure having the plurality of light-emitting diode packages thereon to a target substrate.
2 . The encapsulation process method for wafer-level light-emitting diode dies of claim 1 , wherein a water glue is used for adhering the wafer structure to the temporary substrate.
3 . The encapsulation process method for wafer-level light-emitting diode dies of claim 1 , wherein the wafer structure comprises a nickel-iron alloy layer and a copper layer which is disposed on an upper surface and a lower surface of the nickel-iron alloy layer.
4 . The encapsulation process method for wafer-level light-emitting diode dies of claim 1 , wherein the temporary substrate is a sapphire substrate.
5 . The encapsulation process method for wafer-level light-emitting diode dies of claim 1 , wherein the laser punch-through process is performed to make one of the plurality of light-emitting diode dies in each of the plurality of die areas having a same position form leakage such that the electrical conductor is formed.
6 . The encapsulation process method for wafer-level light-emitting diode dies of claim 1 , wherein the filler adhesive is made of epoxy resin or silicone.
7 . The encapsulation process method for wafer-level light-emitting diode dies of claim 1 , wherein the transparent conductive film is made of indium tin oxide.
8 . The encapsulation process method for wafer-level light-emitting diode dies of claim 1 , wherein in the step of performing the color conversion process further comprises: disposing a plurality of black matrix photoresist on the transparent conductive film on the plurality of light-emitting diode dies; and providing at least one quantum dot color filter between the plurality of black matrix photoresist such that the plurality of light-emitting diode dies have different luminous color scales.
9 . The encapsulation process method for wafer-level light-emitting diode dies of claim 1 , wherein the plurality of light-emitting diode dies have an original luminous color, such that the plurality of light-emitting diode dies are blue light-emitting diode dies.
10 . The encapsulation process method for wafer-level light-emitting diode dies of claim 1 , wherein after the color conversion process is performed, the plurality of light-emitting diode dies are turned into at least red light-emitting diode dies and green light-emitting diode dies.
11 . The encapsulation process method for wafer-level light-emitting diode dies of claim 1 , wherein when a water glue is used for adhering the wafer structure to the temporary substrate, a glue removal process is used to separate the wafer structure having the plurality of light-emitting diode packages thereon from the temporary substrate.
12 . The encapsulation process method for wafer-level light-emitting diode dies of claim 11 , wherein the glue removal process is performed in a deionized water.
13 . The encapsulation process method for wafer-level light-emitting diode dies of claim 12 , wherein a process temperature of the deionized water is controlled at 50° C.
14 . The encapsulation process method for wafer-level light-emitting diode dies of claim 11 , wherein the glue removal process comprises providing a glue removing film on the plurality of light-emitting diode packages, and disposing the wafer structure having the plurality of light-emitting diode packages and the glue removing film, the water glue and the temporary substrate in a deionized water such that the water glue is hydrolyzed and removed by the glue removal process and the wafer structure and the temporary substrate are separated.
15 . The encapsulation process method for wafer-level light-emitting diode dies of claim 14 , wherein before transferring to the target substrate, an UV unstickiness process is further used to make the glue removing film become nonadhesive.
16 . The encapsulation process method for wafer-level light-emitting diode dies of claim 15 , wherein after transferring to the target substrate, the glue removing film is peeled off.
17 . The encapsulation process method for wafer-level light-emitting diode dies of claim 11 , wherein the water glue is made of UV curable water glue.
18 . The encapsulation process method for wafer-level light-emitting diode dies of claim 1 , wherein the target substrate is a printed circuit board (PCB).
19 . The encapsulation process method for wafer-level light-emitting diode dies of claim 1 , wherein the plurality of light-emitting diode packages are package structures of vertical light emitting diode dies.
20 . The encapsulation process method for wafer-level light-emitting diode dies of claim 19 , wherein the vertical light emitting diode dies of the plurality of light-emitting diode packages are selected from a group consisting of a red light emitting diode die, a blue light emitting diode die and a green light emitting diode die.

Description

This application claims priority for TW patent application no. 112108395 filed on 8 Mar. 2023, the content of which is incorporated by reference in its entirely. BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an encapsulation process method for vertical light emitting diode (LED) die package structures. More particularly, the present invention is related to an encapsulation process method for wafer-level light-emitting diode dies without using the conventional carrier board. Description of the Prior Art In general, as known, a Light Emitting Diode (LED) is a certain kind of light source which is fabricated using the semiconductor technology and formed by III-V group compound semiconductors. The LEDs normally operate based on a fact that electrons are combined with holes in a semiconductor to produce photons. The LEDs are different from the conventional light bulbs which must work at a high temperature of thousands of degrees. The LEDs are also different from fluorescent lamps which must be using a high voltage to excite an electron beam. Just like a general electronic element, an LED simply requires a voltage of 2˜4 V to operate and thus being able to work at a normal temperature environment. While compared with the traditional tungsten light bulbs, it is believed that the LED elements are certainly advantageous of having longer lifetime, higher luminous efficiency, lower failure rate, saving more power, and giving much more stable light. Also, the LED elements are highly compatible with various types of lamp devices. As a result, it is believed that the luminous life of the LED elements is certainly to be much longer than that of the traditional light sources, thereby making the LED elements has successfully become a mainstream commodity in the market nowadays. Normally, the LED die structures overall, mainly comprise a horizontal-type structure and a vertical-type structure. Regarding a vertical-type structure LED, when compared with the horizontal-type structure LED, it is believed that the vertical-type structure LED is able to provide better reliability in terms of structural strength, photoelectric parameters, thermal characteristics, light decay and cost, etc. And therefore, the vertical-type structure LED has been widely used in the industry nowadays. And in these years, along with the improvements of the current sciences and technologies, these vertical-type structure LED dies are gradually being mass transferred onto a variety of electronic devices and their substrates thereof. So far, there have been a few conventional techniques, which have been disclosed in the prior arts regarding transferring the dies to the substrate, including: SMT (Surface Mount Technology), wafer-to-wafer transfer technology, electrostatic transfer technology, and so on. However, among these mass transfer technologies, it draws our attention that, the great number of vertical-type structure LED dies configured on the wafer must be cut and divided first. And after that, each die can be individually transferred one by one to the carrier board (usually a printed circuit board) before performing the subsequent encapsulation process of the dies on the carrier board. As such, when the mass transfer process of the dies needs to be carried out in field industries, issues such as redundant process steps, expensive process cost, and poor process efficiency (too slow) often occur in these existing technologies. As a result, these current technologies have been known as being applied limitedly and thus still not being applicable enough until nowadays. And moreover, when the die structure is transferred onto the carrier board, the die alignment is quite difficult to control and thus can not be accurate even if it was performed by a well-trained human operation or sophisticated transfer technology. And an inaccurate die alignment affects the difficulty and increases the complexity to fix the die in the right position subsequently and may even increase the cost and time for rework. In addition, when most of the industries in recent years need to perform packaging and encapsulation process of the die structure of the LED elements, the die size is getting miniaturized nowadays. Therefore, due to such a tiny die size, it also makes the subsequent wire bonding process become extremely difficult. And therefore, it not only makes the packaging process of the LED elements much more challenging than before, but also reduces and affects the yield of its encapsulation process. It is believed that a main solution to this issue is: “how to find an effective replacement of the existing external wire bonding process under the circumstance of miniaturization of the LED die size”. Such a technical solution is eager to be found and proposed. As a result, it is believed that a major target regarding the prior arts relies on how to continuously improve the existing external wire bonding process, and at the same time to