Inspection method for light-emitting diode packages

Abstract

To provide a method for inspecting an innovative package of a light emission diode.SOLUTION: The present invention relates to a method for inspecting a package 100 of a light emission diode. The method for inspection includes the step of providing a package 100 of a light emission diode. The package 100 of the light emission diode includes a light emission diode element 110, a frame 120, and a sealing material 130. The light emission diode element 110 is arranged on the frame 120. The frame 120 is higher than the light emission diode element 110. The sealing material 130 covers a part of the light emission diode element 110 and the frame 120. The method for inspection includes a step of removing a part of the sealing material 130 and exposing the upper surface of the light emission diode element 110.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for inspecting a light-emitting diode package, and more particularly to a method for inspecting a cross section of a light-emitting diode package. [Background technology]

[0002] Light-emitting diodes (LEDs) have advantages such as small size, long life, energy saving, and high efficiency, and are widely used in fields such as lighting and displays. Light-emitting diodes come in a variety of package structures. Common lamp-type LEDs include 3mm, 5mm, round, concave, oval, and square types, and are widely used in consumer products, home appliances, traffic lights, outdoor displays, industrial equipment, etc.

[0003] 1 shows a typical bullet-type light-emitting diode package. This type of bullet-type light-emitting diode package 1 basically includes a light-emitting diode element 10, a frame 20, and an encapsulant 30. The light-emitting diode element 10 is fixed on the frame 20. The frame 20 has two independent electrodes electrically connected to the anode and cathode of the light-emitting diode element 10, respectively. The encapsulant 30 covers the light-emitting diode element 10 and a portion of the frame 20.

[0004] To effectively manage the production quality of LED packages, package failure analysis is required. A typical analysis method is to use grinding and ion beam milling to cut the LED package down to the LED chip, exposing a cross section of the components inside the LED package. By analyzing the cross section, the defective state of the components inside the package and the cause can be identified, and a product improvement plan can be proposed.

[0005] However, after grinding the LED package, separation of components within the package often occurs. As shown in Figure 2, cracks occur between the encapsulant 30 and the frame 20, between the silver adhesive 40 and the frame 20, and between the silver adhesive 40 and the LED element 10. However, with current inspection methods, there is no way to determine whether the cracks are due to an abnormality in the manufacturing process of the LED package or in the grinding process. As a result, this adversely affects subsequent quality abnormality assessments.

[0006] To overcome the above-mentioned problems, it is an urgent task for the industry to develop an innovative inspection method that reduces unintentional cracks in packages caused by improper grinding, accurately identifies the cause of abnormalities in the package manufacturing process, and suppresses the negative impact of cracks caused by improper grinding on abnormality detection during the inspection process. Summary of the Invention

[0007] The main objective of the present invention is to provide an innovative method for inspecting LED packages. This method can reduce unintended cracks in the package due to improper grinding and suppress the adverse effects of cracks due to improper grinding on abnormality detection during the inspection process. As a result, the cause of abnormalities in the package manufacturing process can be accurately identified.

[0008] To achieve the above object, the present invention provides a method for inspecting a light-emitting diode package. The inspection method includes the step of providing a light-emitting diode package. The light-emitting diode package includes a light-emitting diode element, a frame, and an encapsulant. The light-emitting diode element is disposed on the frame. The height of the frame is greater than the height of the light-emitting diode element. The encapsulant covers the light-emitting diode element and a portion of the frame. Next, the inspection method includes the step of removing a portion of the encapsulant to expose an upper surface of the light-emitting diode element.

[0009] In an embodiment of the present invention, the method for inspecting a light-emitting diode package further includes removing a part of the encapsulant on a side surface of the light-emitting diode element.

[0010] In an embodiment of the present invention, the method for inspecting a light emitting diode package further includes ion-polishing the light emitting diode element with an ion beam to form a cross section of the light emitting diode package.

[0011] In an embodiment of the present invention, the step of removing a portion of the encapsulant to expose the top surface of the light-emitting diode element comprises removing a portion of the encapsulant from the top surface of the light-emitting diode element by grinding with a grinding wheel.

[0012] In an embodiment of the present invention, the step of removing a portion of the encapsulant on the side surface of the light-emitting diode element comprises removing a portion of the encapsulant from the side surface of the light-emitting diode element by grinding with a grinding wheel.

[0013] In an embodiment of the present invention, the light emitting diode package further comprises a conductive adhesive for fixing the light emitting diode element to the frame.

[0014] In an embodiment of the present invention, the light emitting diode device is a horizontal type light emitting diode device or a vertical type light emitting diode device.

[0015] Those skilled in the art can understand other objects of the present invention, as well as the technical means and embodiments of the present invention, by referring to the drawings and the embodiments described below. [Brief explanation of the drawings]

[0016] [Figure 1] Schematic diagram showing the package structure of a conventional bullet-type light-emitting diode [Figure 2] SEM photograph showing the cross section of a conventional bullet-type LED package after grinding [Figure 3]FIG. 1 is a schematic diagram showing a part of a bullet-type light-emitting diode package to be inspected in an inspection method according to an embodiment of the present invention; [Figure 4] 1 is a partial top view showing a bullet-type LED package in an inspection method according to an embodiment of the present invention; FIG. [Figure 5] SEM photograph showing a cross section of a package after cutting in an inspection method according to an embodiment of the present invention DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described below through examples. Note that the examples of the present invention are merely examples of embodiments and are not intended to limit the present invention to the environments, applications, or specific aspects described in the examples. Therefore, the explanation of the examples is intended to explain the present invention, but does not limit the present invention. Note that components not directly related to the present invention are omitted and not shown in the embodiments and drawings. The dimensional relationships between the components in the drawings are intended to facilitate understanding and do not limit the actual dimensions.

[0018] FIG. 3 is a schematic diagram showing a portion of a bullet-type light-emitting diode package to be inspected using an inspection method according to an embodiment of the present invention. The bullet-type light-emitting diode package 100 shown in the figure has the same structure as a conventional light-emitting diode package and basically includes a light-emitting diode element 110, a frame 120, an encapsulant 130, and a conductive adhesive 140. The light-emitting diode element 110 is a typical horizontal-type light-emitting diode element or a vertical-type light-emitting diode. In this embodiment of the present invention, the light-emitting diode element 110 has a vertical structure. The frame 120 also has two independent electrodes, namely, an anode electrode 122 and a cathode electrode 124. The upper half of the cathode electrode 124 has a concave cup structure that is wide at the top and narrow at the bottom. The heights of the anode electrode 122 and the cathode electrode 124 of the frame 120 are both higher than the height of the light-emitting diode element 110, so the light-emitting diode element 110 can be accommodated therein. The light-emitting diode element 110 is adhered to an end surface of the cathode electrode 124 by a conductive adhesive 140 such as a silver adhesive, and is electrically connected. Specifically, the anode electrode 122 of the frame 120 is electrically connected to an upper electrode of the light-emitting diode element 110. The cathode electrode 124 of the frame 120 is electrically connected to a lower electrode on the back surface of the light-emitting diode element 110. The encapsulant 130 covers the entire light-emitting diode element 110, the conductive adhesive 140, and a portion of the frame 120. The encapsulant 130 may be an epoxy resin.

[0019] This invention uses finite element analysis to investigate the stress distribution between the LED chip, conductive adhesive, frame, and encapsulant in a conventional LED package structure. It was found that the bottom of the LED chip is the location where the greatest stress is applied. When grinding using a cross-section polisher, as in conventional inspection methods, stress is improperly transmitted to the package structure, causing the encapsulant to expand so that the LED chip lifts up, resulting in unexpected separation between the encapsulant and frame, the conductive adhesive and frame, and the conductive adhesive and chip. In light of the above, this invention proposes an innovative inspection method that can reduce unexpected cracks caused by improper stress transmission during grinding.

[0020] As shown in FIG. 3, the inspection method of the present invention performs grinding in stages to reduce inappropriate transfer of stress to the interior of the package structure during grinding. Specifically, first, a portion of the encapsulant 130 on the upper half of the LED package 100 is removed by grinding with a grinding wheel from the top of the LED package 100. For example, a portion of the encapsulant is removed from the top surface of the LED element 110 until the top surface of the LED element 110 is exposed. As shown in FIG. 3, line segment A-A' is the top grinding end line of the first grinding stage. After grinding, no encapsulant remains on the top surface of the LED element 110. In a preferred embodiment, the first grinding stage can be further divided into two stages. First, a portion of the encapsulant 130 is removed from the top of the LED package 100 to the outside of the frame 120 by grinding with a coarse grinding wheel. Next, a portion of the encapsulant 130 between the frame 120 and the LED element 110 is removed by grinding with a fine grinding wheel until the top surface of the LED element 110 is exposed.

[0021] Next, a description will be given with reference to FIG. 4. FIG. 4 is a partial top view showing the light-emitting diode element 110, the frame 120, and the encapsulant 130 in the light-emitting diode package 100. Note that the outlines and dimensional ratios of the components shown in FIG. 4 are for illustrative purposes only and do not represent the actual outlines and dimensional ratios of the package. In a preferred embodiment, after removing a portion of the encapsulant 130 on the top of the light-emitting diode package 100, the side surfaces of the light-emitting diode package 100 are ground with a grinding wheel device to remove a portion of the encapsulant from the side surfaces of the light-emitting diode element 100. As shown in FIG. 4, line B-B' is the end line of the side surface grinding in the second grinding stage. Note that in this grinding stage, the portion outside the side surface of the light-emitting diode element 110 is ground, but the side surfaces of the light-emitting diode element 110 are not exposed.

[0022] Next, a third grinding step is performed. In this grinding step, the LED package 100 is polished with an ion beam using a cross-section grinding device. As shown in FIG. 4, the package 100 is polished with an ion beam from line B-B' to line C-C' until a cross-section of the LED package is formed. FIG. 5 is a SEM (scanning electron microscope) photograph showing a cross-section of the LED package after using the LED package inspection method according to the present invention.

[0023] As shown in FIG. 5, the cross-section grinding process is divided into multiple distinct grinding stages. This effectively releases the stress generated during the grinding process in stages without transmitting it to the components inside the package, significantly reducing the adverse effects of the stress on the LED chip and other components. In particular, since the encapsulant between the top of the package and the surface of the chip is almost completely removed in the first stage, the grinding-induced stress does not substantially affect the durability of the components inside the package during the subsequent grinding process. Therefore, the LED chip 110, frame 120, encapsulant 130, and conductive adhesive 140 in the LED package 100 maintain good structural integrity, preventing unexpected separation phenomena such as cracks from occurring between the components. This allows for more accurate analysis and determination of product defects, enabling more accurate inspections.

[0024] The above examples are intended to explain embodiments of the present invention and to explain the characteristic configurations of the present invention. The present invention is not limited to the above examples. Modifications or equivalent arrangements that can be easily made by those skilled in the art are also within the scope of the present invention. The scope of protection of the rights of the present invention is based on the claims. [Explanation of symbols]

[0025] 1. Light-emitting diode package 10 Light-emitting diode element 20 frames 30 Encapsulating material 40 Conductive adhesive 100 Light Emitting Diode Packages 110 Light-emitting diode element 120 frames 122 Anode electrode 124 cathode electrode 130 Encapsulating material 140 Conductive adhesive

Claims

1. 1. A method for inspecting a light emitting diode package, comprising: the light-emitting diode package includes a light-emitting diode element, a frame, and an encapsulant, the light-emitting diode element is disposed on the frame, the height of the frame is greater than the height of the light-emitting diode element, and the encapsulant covers the light-emitting diode element and a portion of the frame; The inspection method includes: providing a package for the light emitting diode; removing a portion of the encapsulant to expose an upper surface of the light-emitting diode element; removing a part of the encapsulant on a side surface of the light-emitting diode element; and polishing the light-emitting diode element with an ion beam to form a cross section of the light-emitting diode package.

2. 2. The method for inspecting a light-emitting diode package according to claim 1, wherein the step of removing a portion of the encapsulant to expose the top surface of the light-emitting diode element comprises removing the portion of the encapsulant from the top surface of the light-emitting diode element by grinding with a grinding wheel.

3. 2. The method for inspecting a light-emitting diode package according to claim 1, wherein the step of removing a portion of the encapsulant from the side surface of the light-emitting diode element comprises removing a portion of the encapsulant from the side surface of the light-emitting diode element by grinding with a grinding wheel.

4. 2. The method of claim 1, wherein the light emitting diode package further comprises a conductive adhesive for fixing the light emitting diode element to the frame.

5. 2. The method of claim 1, wherein the light emitting diode element is a horizontal type light emitting diode element or a vertical type light emitting diode element.

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