COB packaging structure
By adding a thin filler layer and phosphor deposition process to the COB packaging structure, the problem of bubble residue was solved, the product appearance and reliability were improved, and a highly efficient COB packaging structure design was achieved.
Patent Information
- Application Number
- CN202520182236.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-05
- Publication Date
- 2026-02-13
- Estimated Expiration
- 2035-02-05
AI Technical Summary
In existing COB packaging structures, due to the thick encapsulating adhesive layer and the presence of cavities, residual bubbles can affect the appearance and reliability of the finished product. Furthermore, long-term use may adversely affect the reliability of the product.
A thin filler layer is added to the substrate to fill the gap under the LED chip, and phosphor is deposited on the surface of the circuit pads through a centrifugal process. Combined with the design of transparent or white colloid and encapsulation adhesive layer, it promotes the rise of gas during baking and ensures the uniformity of adhesive layer thickness.
It effectively removes air from gaps, reduces residual air bubbles, improves the appearance of finished products, enhances product reliability and brightness, and ensures stability during long-term use.
Smart Images
Figure CN223912816U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of LED packaging technology, and in particular to COB packaging structure. Background Technology
[0002] LEDs, as a new type of solid-state semiconductor device, have advantages such as small size, light weight, high luminous efficiency, energy saving and environmental protection, and are now widely used in various industries. With the continuous development of the market, the demand for high-power LED light sources is also increasing. COB (Chip-on-Board) technology has emerged with its outstanding advantages of high luminous efficiency, high performance and low cost, and has also become the direction that many companies have been striving to develop.
[0003] like Figure 1 As shown, the existing COB light source process typically involves using die-bonding solder paste on a substrate 1 coated with a top layer of tar 13 to fix the LED chip 2 onto the intermediate layer 12 of the circuit pads, followed by damming and encapsulation. The substrate 1 is usually designed with a three-layer structure: an aluminum substrate bottom layer 11, an intermediate layer 12 of the circuit pads, and a top layer of tar 13. In actual use, to prevent the top layer of tar 13 from lifting the LED chip 2 during die bonding and causing poor soldering, tar is usually not sprayed between the positive and negative pads of the intermediate layer 12 of the circuit pads. This design results in a cavity (gap 121) under the LED chip. During the baking process after encapsulation, the air in the cavity will expand due to heat and escape into the encapsulation layer 4. However, the encapsulation layer in the COB encapsulation structure is relatively thick, causing the air in the encapsulation layer to be unable to quickly rise to the surface and remain in the encapsulation layer, resulting in a large number of air bubbles in the finished product. This not only affects the appearance of the finished product, but also, during long-term use, due to the thermal expansion and contraction of the encapsulation layer, the air bubbles may also have an adverse effect on the reliability of the product. Utility Model Content
[0004] The technical problem solved by this utility model is to provide a COB packaging structure with high reliability.
[0005] In order to solve the above technical problems, the utility model adopts the technical scheme: a COB packaging structure, including substrate, LED wafer, filling glue layer, encapsulation glue layer and dam glue, the dam glue is located on the substrate, the substrate includes base layer, circuit pad middle layer and pitch top layer which are sequentially stacked, the circuit pad middle layer has positive pole pad and negative pole pad, the positive pole pad and negative pole pad have gap, the pitch top layer covers other area of the circuit pad middle layer except the positive pole pad and negative pole pad, the LED wafer is fixed on the base layer and is located in the hollow area of the dam glue, the LED wafer is set corresponding to the gap and is electrically connected with the positive pole pad and negative pole pad respectively, the filling glue layer fills the bottom of the hollow area of the dam glue and the gap is filled by the filling glue layer, the top of the LED wafer is protruded relative to the filling glue layer, the encapsulation glue layer fills the upper part of the hollow area of the dam glue.
[0006] In an embodiment, the top surface of the filling glue layer is 10±3 microns lower than the top surface of the LED wafer.
[0007] In an embodiment, the filling glue layer is a transparent glue or a white glue.
[0008] In an embodiment, the filling glue layer is a mixed glue formed by mixing phosphor and encapsulation glue.
[0009] In an embodiment, the phosphor in the filling glue layer is deposited at the bottom of the filling glue layer through a centrifugal precipitation process.
[0010] In an embodiment, the material of the encapsulation glue layer is silicone, silicone resin or epoxy resin.
[0011] In an embodiment, the top surface of the encapsulation glue layer is flush with the top surface of the dam glue.
[0012] In an embodiment, the base layer is an aluminum substrate bottom layer.
[0013] The utility model has the advantages that: the COB packaging structure is novel, a relatively thin filling glue layer is additionally arranged, which can not only fill the gap below the LED wafer and effectively discharge air in the gap, but also help air in the glue float to the surface and be released during the baking process, thus effectively solving the problem of air bubble remaining after baking, significantly improving the appearance of the product and ensuring the reliability of the product during long-term use; the outermost encapsulation glue layer can ensure the accuracy of the product parameters.
[0014] In addition, when the fluorescent powder is doped in the filling adhesive layer, the fluorescent powder in the filling layer can be deposited on the surface of the exposed circuit pad through a centrifugal process, which changes the color of the circuit pad, reduces the absorption of light, and improves the brightness of the final product. BRIEF DESCRIPTION OF DRAWINGS
[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or the prior art description. Obviously, the drawings described below are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained according to the structures shown in the drawings without creative labor.
[0016] Figure 1 is a sectional view of the prior art COB packaging structure;
[0017] Figure 2 is a sectional view of the COB packaging structure of the first embodiment of the present application.
[0018] Explanation of reference numerals:
[0019] 1, substrate; 11, base layer; 12, circuit pad middle layer; 121, gap; 13, asphalt top layer;
[0020] 2, LED wafer;
[0021] 3, filling adhesive layer;
[0022] 4, packaging adhesive layer;
[0023] 5, dam adhesive. DETAILED DESCRIPTION
[0024] The purposes, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings.
[0025] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.
[0026] It should be noted that if the embodiments of the present application involve directional indications such as up, down, left, right, front, back, etc., the directional indications are only used to explain the relative position relationship, movement condition, etc. between the components in a certain specific posture such as shown in the drawings. If the specific posture changes, the directional indications will also change accordingly.
[0027] In addition, if the description of "first", "second" and the like is involved in the embodiments of the present application, the description of "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can be explicitly or implicitly included at least one of the features.
[0028] In addition, the meaning of "and / or" appearing throughout the text is that it includes three parallel schemes. Taking "and / or" as an example, it includes scheme, or scheme, or and simultaneously satisfied scheme. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of the ordinary skilled in the art, when the combination of technical solutions appears contradictory or cannot be realized, it should be considered that the combination of technical solutions does not exist, nor in the protection scope required by the present application.
[0029] In the present application, unless otherwise expressly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium; it can be the communication between two elements or the interaction relationship between two elements. For the ordinary skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0030] Embodiment one
[0031] Please refer to Figure 2The utility model discloses an embodiment one for: a COB packaging structure, including substrate 1, LED wafer 2, filling adhesive layer 3, encapsulation adhesive layer 4 and dam adhesive 5, the dam adhesive 5 is located substrate 1, substrate 1 includes the base layer 11, circuit pad middle layer 12 and pitch top layer 13 that are sequentially stacked, the base layer 11 can be aluminum substrate 1 bottom layer, circuit pad middle layer 12 has positive pole pad and negative pole pad, the positive pole pad and negative pole pad between have gap 121, pitch top layer 13 covers the other area of circuit pad middle layer 12 except positive pole pad and negative pole pad, LED wafer 2 is fixed on base layer 11 and is located in the hollow region of dam adhesive 5, LED wafer 2 corresponds to gap 121 setting and is electrically connected with positive pole pad and negative pole pad respectively, filling adhesive layer 3 fills the bottom of the hollow region of dam adhesive 5 and gap 121 is filled by filling adhesive layer 3, that is, filling adhesive layer 3 can cover pitch top layer 13, the exposed area of circuit pad middle layer 12 and the exposed area of base layer 11 top surface, LED wafer 2 top portion is protruding relative to filling adhesive layer 3, which means that the overall thickness of filling adhesive layer 3 is thin, and it is beneficial to air discharge, encapsulation adhesive layer 4 fills the upper portion of the hollow region of dam adhesive 5.
[0032] The top surface of the filling adhesive layer 3 is 10±3 μm lower than the top surface of the LED wafer 2.
[0033] In one or more embodiments, the filling adhesive layer 3 is a transparent or white gel. In this embodiment, the filling adhesive layer 3 is a mixed gel of phosphor and encapsulation adhesive, and the phosphor in the filling adhesive layer 3 is deposited at the bottom of the filling adhesive layer 3 by a centrifugal precipitation process.
[0034] The material of the encapsulation adhesive layer 4 is silicone, silicone resin, epoxy resin or other silicon-based high refractive index materials; the top surface of the encapsulation adhesive layer 4 is flush with the top surface of the dam adhesive 5.
[0035] Next, the processing process of the COB packaging structure is briefly described as follows:
[0036] First, the LED wafer 2 is fixed on the substrate 1 by special tin paste for die bonding, then a bowl cup is formed on the substrate 1 by damming, a thin filling adhesive layer 3 is sprayed in the bowl cup after the dam adhesive 5 is cured, the filling adhesive layer 3 is a mixed gel of phosphor and encapsulation adhesive, and the top surface of the filling adhesive layer 3 is 10±3 μm lower than the top surface of the LED wafer 2, then a centrifugal process is performed and baked to form, the filling adhesive layer 3 is cured, and finally the encapsulation adhesive layer 4 is coated on the surface of the filling adhesive layer 3 to ensure the accuracy of the product parameters.
[0037] The above are only optional embodiments of the present application, and do not limit the patent scope of the present application, and any equivalent structural transformation made by using the content of the present application specification and drawings, or direct / indirect application in other related technical fields are included in the patent protection scope of the present application.
Claims
1. A COB packaging structure, characterized in that: The LED chip is fixed on the substrate layer and located in the hollow area of the dam glue, the LED chip is arranged corresponding to the gap and electrically connected with the positive electrode pad and the negative electrode pad respectively, the filling glue layer fills the bottom of the hollow area of the dam glue and the gap is filled by the filling glue layer, and the top of the LED chip is protruded relative to the filling glue layer; and the encapsulation glue layer fills the upper part of the hollow area of the dam glue.
2. The COB packaging structure of claim 1, wherein: The top surface of the filling glue layer is 10±3 μm lower than the top surface of the LED chip.
3. The COB packaging structure of claim 1, wherein: The filling glue layer is transparent glue or white glue.
4. The COB package structure of claim 1, wherein: The filling glue layer is mixed glue formed by mixing phosphor and encapsulation glue.
5. The COB package structure of claim 4, wherein: The phosphor in the filling glue layer is deposited in the bottom of the filling glue layer through centrifugal precipitation process.
6. The COB package structure of claim 1, wherein: The material of the encapsulation glue layer is silica gel, silicone or epoxy resin.
7. The COB package structure of claim 1, wherein: The top surface of the encapsulation glue layer is flush with the top surface of the dam glue.
8. The COB package structure of claim 1, wherein: The substrate layer is aluminum substrate layer.