Flip LED packaging structure
By designing independently spaced pads, conductive adhesive layer, epoxy filler and sealing layer in the flip-up LED packaging structure, the problem of lifting or failure caused by stress pulling in the solder paste overflow soldering process is solved, and the product stability, compatibility and life is improved.
Patent Information
- Application Number
- CN202420786249.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-16
- Publication Date
- 2025-03-18
- Estimated Expiration
- 2034-04-16
AI Technical Summary
In the solder paste over-reflow soldering process, small size flip LED chips have small contact surfaces between the pad and the carrier plate due to the small chip size, which is easy to cause the chip to rise or failure due to stress pulling in the melted state of the solder paste during the over-reflow soldering process, which leads to the problem of lamp bead failure.
A flip LED packaging structure is designed, two independently spaced pads are provided on the carrier board, and a conductive adhesive layer is arranged above the pads and the positive and negative electrodes of the flip LED chip are connected. Epoxy filler is filled with around the chip and the bottom area, and a sealing layer is arranged above the chip.
It effectively avoids the problems of lifting or failure caused by stress pulling during overflow soldering of small-size flip LED chips, ensuring that the optical characteristics of the product are not affected, and at the same time, reducing the packaging cost and improving the stability, compatibility and life of the product.
Smart Images
Figure CN222639015U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of packaging, and in particular relates to a flip-chip LED packaging structure. Background Art
[0002] The existing LED flip-chip optical devices on the market are all packaged using the solder paste reflow process. For large-sized flip-chip chips (above 15*30mil in size), due to their large size and weight, the bonding of the chip bottom pad with the solder paste and the carrier board is not a problem during the subsequent terminal reflow application process, even if it is affected by the high-temperature thermal expansion stress of the surrounding packaging glue (silicone) and there will be no chip delamination abnormality.
[0003] The small-sized flip chip (less than 15*30mil) packaging also uses the solder paste reflow process. Due to the small size of the chip, the contact area between the bottom pad of the chip and the carrier (including PLCC / PCB / ceramic) is also small. During the terminal reflow application of the product, the solder paste is in a molten state and is affected by the high-temperature thermal expansion stress of the surrounding packaging glue (silicone) at the same time, resulting in a gap between the flip chip and the carrier, resulting in a lack of brightness or pressed brightness after cooling. Utility Model Content
[0004] The purpose of the utility model is to solve the defects and shortcomings in the prior art and to design a flip-chip LED packaging structure that can avoid the adverse risks of such flip-chip products in subsequent terminal use and will not affect the optical characteristics of the product.
[0005] To achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a flip-chip LED packaging structure, including a carrier board, the carrier board has two independently spaced solder pads, and conductive adhesive layers connected to the positive and negative electrodes of the flip-chip LED chip are respectively arranged above the two solder pads, and filling adhesive layers are arranged around and at the bottom area of the flip-chip LED chip, and a sealing glue layer is arranged above the flip-chip LED chip.
[0006] Preferably, the carrier board is a PCB / ceramic substrate.
[0007] Preferably, the carrier board is made of PLCC / EMC / SMC.
[0008] Preferably, the flip-chip LED chip is a small-sized flip-chip LED chip of less than 15*30 mil.
[0009] Preferably, the conductive adhesive layer is made of silver glue or solder paste and is attached to the pad by dispensing or printing.
[0010] Preferably, the filling adhesive layer is made of epoxy filling adhesive, and the color of the epoxy filling adhesive is transparent, white, gray or black.
[0011] Preferably, the height of the filling glue layer arranged around the flip-chip LED chip is not higher than the height of the flip-chip LED chip.
[0012] Preferably, a bottom area for arranging a filling glue layer is formed between the carrier board, the two solder pads, the two conductive glue layers and the flip-chip LED chip.
[0013] Preferably, the sealing layer is made of silicone or epoxy glue, and is sealed by dispensing or molding.
[0014] After adopting the above technical solution, the flip-chip LED packaging structure provided by the utility model has the following beneficial effects:
[0015] The utility model can solve the problem that in the prior art, small-sized flip-chip LED chips (size below 15*30mil) are packaged in the process of solder paste reflow soldering. Due to the small size of the chip, the contact area between the bottom pad of the chip and the carrier board is small, which leads to the abnormal chip warping and failure during the reflow soldering due to the melting of the solder paste and pulling the pads at both ends of the chip, thereby causing the lamp bead to fail. The utility model does not affect the optical characteristics of the product, makes the light source have better high temperature resistance, reduces the packaging process and packaging materials, greatly reduces the packaging cost of the light source, and has the advantages of more stable product quality, better compatibility, better effect, longer life, etc. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 This is a schematic diagram of the structure of the first embodiment of the utility model;
[0017] Figure 2 This is a schematic diagram of the structure of the second embodiment of the present utility model;
[0018] Figure 3 This is a process flow chart of Example 1 of the present utility model;
[0019] Figure 4 This is a process flow chart of Example 2 of the present utility model.
[0020] Among them: carrier board 1, solder pad 2, flip-chip LED chip 3, conductive adhesive layer 4, filling adhesive layer 5, sealing adhesive layer 6. DETAILED DESCRIPTION
[0021] The present invention is further described clearly and completely below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0022] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.
[0023] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values of the parts and steps described in these embodiments do not limit the scope of the utility model. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in one drawing, it does not need to be further discussed in subsequent drawings.
[0024] In the description of the present utility model, it needs to be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present utility model and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present utility model; the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.
[0025] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" may include both "above" and "below". The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.
[0026] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the utility model.
[0027] Embodiment 1
[0028] This embodiment provides a flip-chip LED packaging structure, such as Figure 1 As shown, it includes a carrier board 1, the carrier board 1 is selected from PCB / ceramic substrate, the carrier board 1 has two independently spaced pads 2, and conductive adhesive layers 4 connected to the positive and negative electrodes of the flip-chip LED chip 3 are respectively arranged above the two pads 2. The flip-chip LED chip 3 is a small-sized flip-chip LED chip of less than 15*30mil, and the conductive adhesive layer 4 is selected from silver glue or solder paste, and is attached to the pad 2 by dispensing or printing. A filling adhesive layer 5 is arranged around and at the bottom area of the flip-chip LED chip 3. The filling adhesive layer 5 is selected from epoxy filling adhesive, and the color of the epoxy filling adhesive is transparent, white, gray or black. Further, the height of the filling adhesive layer 5 arranged around the flip-chip LED chip 3 is not higher than the height of the flip-chip LED chip 3. A bottom area for setting the filling adhesive layer 5 is formed between the carrier board 1, the two pads 2, the two conductive adhesive layers 4 and the flip-chip LED chip 3. A sealing adhesive layer 6 is arranged above the flip-chip LED chip 3. The sealing adhesive layer 6 is selected from silicone or epoxy adhesive, and is sealed by dispensing or molding.
[0029] This embodiment provides a packaging method for a flip-chip LED packaging structure, such as Figure 3 As shown, the following steps are included:
[0030] S1. Apply conductive silver glue to the two pads on the carrier board by dispensing or printing.
[0031] S2, fix the small size flip-chip LED chip on the center position above the pad conductive glue, and then use an oven for high temperature curing;
[0032] S3, fill the epoxy filling glue around and at the bottom of the flip-chip LED chip, the height of the glue is flush with or slightly lower than the flip-chip LED chip, and then bake and cure;
[0033] S4, then use dispensing or molding to encapsulate the conventional sealing layer.
[0034] Embodiment 2
[0035] This embodiment provides a flip-chip LED packaging structure, such as Figure 2 As shown, its structure is basically the same as that of the first embodiment, except that the carrier board 1 in this embodiment is made of PLCC / EMC / SMC.
[0036] This embodiment provides a packaging method for a flip-chip LED packaging structure, such as Figure 4 As shown, the specific steps are the same as those in Example 1 and are not described in detail.
[0037] To sum up, the flip-chip LED packaging structure provided by the utility model is suitable for the packaging process of small-size flip-chip LED chips. It can avoid chip failure without affecting the optical properties of the product. It has the advantages of more stable quality, better compatibility, better effect, and longer life. It has great market value and deserves wide promotion and application.
[0038] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes within the technical scope disclosed by the present invention according to the technical scheme and the utility model concept of the present invention, which should be covered by the protection scope of the present invention.
Claims
1. A flip-chip LED packaging structure, comprising a carrier board (1), characterized in that: The carrier board (1) has two solder pads (2) arranged independently and at intervals, and conductive adhesive layers (4) connected to the positive and negative electrodes of the flip-chip LED chip (3) are arranged above the two solder pads (2), respectively; a filling adhesive layer (5) is arranged around and at the bottom of the flip-chip LED chip (3), and the height of the filling adhesive layer (5) arranged around the flip-chip LED chip (3) is not higher than the height of the flip-chip LED chip (3); and a sealing adhesive layer (6) is arranged above the flip-chip LED chip (3).
2. The flip-chip LED packaging structure according to claim 1, characterized in that: The carrier board (1) is a PCB / ceramic substrate.
3. The flip-chip LED packaging structure according to claim 1, characterized in that: The carrier board (1) is selected from PLCC / EMC / SMC.
4. The flip-chip LED packaging structure according to claim 1, characterized in that: The flip-chip LED chip (3) is a small-sized flip-chip LED chip with a size of less than 15*30 mil.
5. The flip-chip LED packaging structure according to claim 1, characterized in that: The conductive adhesive layer (4) is made of silver glue or solder paste and is attached to the pad (2) by dispensing or printing.
6. The flip-chip LED packaging structure according to claim 1, characterized in that: The filling adhesive layer (5) is made of epoxy filling adhesive, and the color of the epoxy filling adhesive is transparent, white, gray or black.
7. The flip-chip LED packaging structure according to claim 1, characterized in that: A bottom area for arranging a filling glue layer (5) is formed between the carrier board (1), the two solder pads (2), the two conductive glue layers (4) and the flip-chip LED chip (3).
8. The flip-chip LED packaging structure according to claim 1, characterized in that: The sealing glue layer (6) is made of silicone or epoxy glue, and is sealed by dispensing or molding.