A single-surface light-emitting white light CSP and a packaging method thereof

Abstract

The application relates to the technical field of semiconductor packaging, in particular to a single-surface light-emitting white light CSP and a packaging method thereof. The white light CSP comprises, in sequence, a light-emitting chip, an OCA adhesive film, a fluorescent adhesive film and a protective film, the light-emitting surface of the light-emitting chip is combined with the OCA adhesive film; the side wall surface of the light-emitting chip, the side wall surface of the OCA adhesive film and the side wall surface of the fluorescent adhesive film are all filled with a white wall adhesive film; the raw materials of the protective film include organic silicone glue and silicon powder, the content of the silicon powder in the protective film is 40-70 wt%, the light-emitting performance can be maintained, and the cold-heat impact resistance of the CSP can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor packaging technology, specifically to a single-sided white light CSP and its packaging method. Background Technology

[0002] With the rapid development of semiconductor technology, LED packaging technology has received widespread attention due to its advantages such as high efficiency, small size, energy saving, and environmental friendliness. Chip-scale packaging (CSP), as an emerging packaging form, has important applications in the field of high-voltage flip-chip LEDs. However, the packaging method of traditional single-sided light-emitting CSP has the following problems: Insufficient heat dissipation performance: Traditional processes usually use solid phosphor films or phosphor film particles with a thickness of at least 150μm, which require bonding the chip with transparent silicone, resulting in an extended heat dissipation path and difficulty in dissipating chip heat, limiting high-power applications; Limited light emission efficiency: Some existing technologies use a five-sided light-emitting design with full phosphor coverage, which improves luminous flux, but the uneven light emission from the sides leads to poor color uniformity; while single-sided light-emitting structures have uniform color, but the luminous efficiency loss is relatively large, and there is also the problem of low production efficiency.

[0003] Chinese utility model patent CN209963082U achieves single-sided light emission through a combination of a transparent adhesive layer and white adhesive, but its fluorescent adhesive layer still relies on a multi-layer structure, resulting in high encapsulation complexity. In contrast, while Chinese utility model patent CN217768415U uses a white adhesive layer to block stray light from the sides, the presence of the transparent adhesive layer still leads to a loss of light efficiency, further limiting the light transmittance. Furthermore, due to process limitations, only single-chip LEDs can be produced, resulting in low overall production efficiency. Summary of the Invention

[0004] The first aspect of the present invention provides a single-sided white light CSP, comprising a light-emitting chip, an OCA film, a fluorescent film and a protective film sequentially laminated together, wherein the light-emitting surface of the light-emitting chip is laminated with the OCA film; the sidewalls of the light-emitting chip, the sidewalls of the OCA film and the sidewalls of the fluorescent film are all filled with a white wall film.

[0005] The raw materials for preparing the white wall adhesive film include silicone water and titanium dioxide, and the content of titanium dioxide in the white wall adhesive film is 15-40 wt%.

[0006] Optionally, the content of titanium dioxide in the white wall film is 15-30 wt%.

[0007] The raw materials for preparing the protective film include silicone water and silica powder, and the silica powder content in the protective film is 40-70 wt%.

[0008] Optionally, the content of the silicon micropowder in the protective film is 40-60 wt%.

[0009] The silicon micropowder includes submicron spherical silicon micropowder.

[0010] Optionally, the submicron spherical silicon powder includes at least one of NQ1060H, NQ1065H and NQ1045G from Lianrui New Materials.

[0011] The thickness of the OCA film is 10-30 micrometers, and the thickness of the fluorescent film is 30-150 micrometers.

[0012] The thickness of the protective film is 50-200 micrometers.

[0013] The raw materials for preparing the fluorescent film include fluorescent powder and silicone water, and the content of fluorescent powder in the fluorescent film is 40-70 wt%.

[0014] Optionally, the phosphor content in the fluorescent film is 50-70 wt%.

[0015] The silicone water is selected from Huigu's PS-5123 silicone water.

[0016] This invention reveals that the raw materials for preparing the protective film include silicone water and silica powder. The silica powder content in the protective film is 40-70 wt%, which can effectively improve the thermal shock resistance of the CSP while maintaining its luminescence performance. The protective film uses silicone water as a matrix, which has good light transmittance, ensuring luminescence performance while providing a certain degree of flexibility. The added silica powder, as an inorganic filler, has a low linear expansion coefficient. When its content is 40-70 wt%, it can effectively reduce the overall linear expansion coefficient of the protective film, making it closer to the expansion coefficient of adjacent fluorescent layers, chips, and other materials. This reduces interfacial stress between layers during high and low temperature thermal shocks. This content range also avoids the problem of insufficient silica powder failing to effectively adjust the expansion coefficient or excessively affecting the flexibility and light transmittance of the silicone water. Thus, while maintaining luminescence performance, it significantly improves the thermal shock resistance of the CSP, ensuring that cracking does not occur after high and low temperature thermal shocks.

[0017] A second aspect of the present invention provides a packaging method for a single-sided white light CSP, comprising the following steps:

[0018] S1. Fix the light-emitting chips on the substrate and encapsulate them with white adhesive film. Then remove the white adhesive film from the light-emitting side of the light-emitting chip to expose the light-emitting side, making the white adhesive film flush with the light-emitting chip.

[0019] S2, composite the OCA film and the fluorescent film, and then laminate the OCA film onto the light-emitting surface of the light-emitting chip through vacuum bonding;

[0020] S3 involves cutting the semi-finished product obtained in S2, applying adhesive, sealing with a protective film, and cutting again to obtain a single-sided white light CSP.

[0021] The temperature at which the OCA film and the fluorescent film are laminated is 70-90℃.

[0022] The encapsulation in S1 is performed using a vacuum press, with a pressing temperature of 90-120℃ and a pressing time of 5-15 minutes.

[0023] The process parameters for the encapsulation protective film include: vacuum degree of 90-98 kPa, pressing temperature of 90-120℃, and pressing time of 5-15 min.

[0024] The process parameters for laminating the OCA film onto the light-emitting chip include: a lamination temperature of 80-110℃ and a lamination pressure of 5-10kN.

[0025] The substrate is made of glass.

[0026] Beneficial effects

[0027] 1. The raw materials for preparing the protective film include silicone water and silica powder. The silica powder content in the protective film is 40-70 wt%, which can effectively improve the resistance of CSP to thermal shock while maintaining luminescence performance.

[0028] 2. By limiting the lamination temperature of OCA film and fluorescent film to 70-90℃, the lamination performance can be effectively improved, maintaining production efficiency while increasing yield.

[0029] 3. The CSP preparation method of the present invention can be used for mass production of LED beads.

[0030] 4. This invention utilizes a specific fluorescent film to achieve excellent color temperature uniformity in the prepared CSP.

[0031] 5. The CSP prepared by this invention has good resistance to yellowing. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of step S1 in Example 1.

[0033] Figure 2 This is a schematic diagram of step S2 in Example 1.

[0034] Figure 3 This is a schematic diagram of step S3 in Example 1.

[0035] Figure 4 This is a schematic diagram of step S5 in Example 1.

[0036] Figure 5This is a schematic diagram of step S6 in Example 1.

[0037] Figure 6 This is a schematic diagram of step S7 in Example 1.

[0038] Figure 7 This is a schematic diagram of step S8 in Example 1.

[0039] Figure 8 This is a schematic diagram of the single-sided white light CSP prepared in Example 1.

[0040] Figure 9 The morphology of the sample after the CSP thermal shock test in Example 1.

[0041] Figure 10 The morphology of the sample after the CSP thermal shock test is shown in Comparative Example 1.

[0042] Figure 11 The surface morphology of the OCA composite film in Example 1 is shown.

[0043] Figure 12 The surface morphology of the OCA composite film is shown in Comparative Example 2.

[0044] Figure 13 The results are the color temperature consistency test results of the fluorescent film in Example 1, where the control group hot melt adhesive solution corresponds to the fluorescent film in Example 1 of patent CN202310827680.3.

[0045] Figure 14 The yellowing resistance of the fluorescent film in Example 1 is shown, and the control group hot melt adhesive scheme corresponds to the fluorescent film in Example 1 of patent CN202310827680.3.

[0046] The components include: 1. Glass plate; 2. Light-emitting chip; 3. Double-sided tape; 4. White wall film; 5. Fluorescent film; 6. OCA film; and 7. Protective film. Detailed Implementation

[0047] Example 1

[0048] A type of single-sided white light CSP, such as Figure 8 As shown, it consists of a light-emitting chip, an OCA film, a fluorescent film, and a protective film, which are sequentially laminated. The light-emitting surface of the light-emitting chip is laminated with the OCA film. The sidewalls of the light-emitting chip, the sidewalls of the OCA film, and the sidewalls of the fluorescent film are all filled with white wall film.

[0049] The raw materials for preparing the protective film are: silicone water (Huigu, PS-5123) and silicon micro powder (Lianrui New Materials, NQ1060H), and the content of silicon micro powder in the protective film is 60wt%.

[0050] The raw materials for preparing the white wall adhesive film are: silicone water (Huigu, PS-5123) and titanium dioxide (BASF 0022A), and the content of titanium dioxide in the white wall adhesive film is 25wt%.

[0051] The raw materials for preparing the fluorescent film are: fluorescent powder (Intermay, YAG04) and silicone water (Huigu, PS-5123), and the content of the fluorescent powder in the fluorescent film is 60wt%.

[0052] The OCA film has a thickness of 17 micrometers, the fluorescent film has a thickness of 100 micrometers, and the protective film has a thickness of 100 micrometers.

[0053] A packaging method for a single-sided white light CSP includes the following steps:

[0054] S1. Arrange the light-emitting chips 2 on the double-sided adhesive tape 3: as follows: Figure 1 As shown, a layer of double-sided tape 3 (Kehongjian's DTH778A-B) is attached to a glass plate 1 (100×100mm). Flip-chip 2 (Sanan Optoelectronics, S-32ABFUD) with a thickness of 32×32mil and 150 micrometers is arranged on the glass substrate (size is 100×100mm) with a spacing of 1.48×1.48mm. The number of die bonded chips is 1000.

[0055] S2. Encapsulate the chip with white wall adhesive film 4: such as Figure 2 As shown, the raw materials for preparing the white wall adhesive film 4 were mixed and stirred for 30 minutes using a dispersion disc at 600 rpm. Then, the mixture was stirred for 3 minutes under a vacuum of 98 kPa and 1000 rpm to remove air bubbles from the adhesive. A white wall film of 74×74×0.16 mm was prepared by coating. The white wall film was then placed on the chip surface, and the dimensions were controlled using a 74×74×0.16 mm square pad. The film was then pressed for 360 seconds in a vacuum press at 110°C.

[0056] S3. Residual white glue on the surface of the light-emitting chip 2 after grinding: such as Figure 3 As shown, by controlling the depth of the grinding machine, the white wall residue on the chip surface is removed, exposing the sapphire on the light-emitting surface of the light-emitting chip 2 for later use;

[0057] S4. Fabrication of OCA Composite Film: Mix the raw materials for preparing fluorescent adhesive film 5, stir with a dispersion disc at 600 rpm for 20 min, and then stir at a vacuum of 98 kPa and 1000 rpm for 3 min to remove air bubbles in the adhesive; then prepare fluorescent adhesive film 5 with a thickness of 100 micrometers by coating, and cure at 150℃; at 70℃, composite OCA adhesive film 6 (Taijia Keke, K120E) with fluorescent adhesive film 5 to form OCA composite film;

[0058] S5. Attach the OCA composite film to the surface of the light-emitting chip 2: (e.g.) Figure 4 As shown, the OCA composite film was placed on the white wall substrate in S3. Under the conditions of 90°C, 6.4kN pressure and 98kPa vacuum, the OCA composite film was placed on the white wall film in S3.

[0059] S6. Cutting of semi-finished LED beads: such as... Figure 5 As shown, a 400-micron cutting blade is used to cut the S5-bonded encapsulation layer into 1.08×1.08mm CSP LED beads.

[0060] S7. Fill in white walls: such as Figure 6 As shown, clean all residual material from the cut seams in S6, and use a self-adhesive device to apply the white wall adhesive prepared in S2 into the seams; the cut seams are filled by the self-leveling of the adhesive, and cured at 150℃ for 4 hours.

[0061] S8, Protective film 7 for encapsulating fluorescent adhesive film 5: such as Figure 7 As shown, the raw materials for preparing the protective film 7 are mixed evenly; a film of 74×74×0.1mm is prepared by coating; the pressing parameters are set, including a temperature of 110℃, a vacuum of 98kPa, and a pressing time of 6min.

[0062] S9. Finished Product Cutting: Using an 80-micron-thick cutting blade, the lamp board in S8 is cut into 1.4×1.4mm individual LED beads, resulting in... Figure 8 The white CSP shown is a single-sided light-emitting device.

[0063] Example 2

[0064] The specific implementation method is the same as in Example 1; the difference is that the content of silicon micropowder in the protective film in Example 2 is 40 wt%.

[0065] Example 3

[0066] The specific implementation method is the same as in Example 1; the difference is that in Example 3, OCA film 6 (Taikeke, K120E) and fluorescent film 5 are combined at 90°C to form an OCA composite film.

[0067] Comparative Example 1

[0068] The specific implementation method is the same as in Example 1; the difference is that the content of silicon micropowder in the protective film in Comparative Example 1 is 20wt%.

[0069] Comparative Example 2

[0070] The specific implementation method is the same as in Example 1; the difference is that in Comparative Example 2, OCA film 6 (Taijia, K120E) and fluorescent film 5 are combined at 30°C to form an OCA composite film.

[0071] Comparative Example 3

[0072] The specific implementation method is the same as in Example 1; the difference is that the raw material for preparing the protective film in Comparative Example 3 is silicone water (Huigu, PS-5123).

[0073] Performance testing methods

[0074] 1. The protective films prepared in Examples 1-2 and Comparative Examples 1-3 were subjected to linear expansion coefficient test (CTE): (1) The adhesive samples were made into small samples with a diameter of 0.8 cm and a thickness of 0.4 cm; (2) The test temperature range of the thermomechanical analyzer (TMA) was set to 30-130℃; (3) The linear expansion coefficient of the material was measured in the range of 60-90℃, and the values ​​are listed in Table 1.

[0075] 2. The single-sided white LED CSPs prepared in Examples 1-2 and Comparative Examples 1-3 were subjected to thermal shock tests: The CSPs were placed in a thermal shock test chamber; the low temperature of the thermal shock test chamber was set to -40℃ and the high temperature to 105℃, the storage time at each temperature was 15 minutes, and each cycle was 30 minutes. After 300 consecutive cycles, the LEDs were removed and observed for cracking, as shown in Table 1.

[0076] 3. Observe whether there are bubbles on the surface of the OCA composite membrane prepared in the examples and comparative examples, as listed in Table 1.

[0077] The "-" indicates that no test was performed.

[0078] Performance test data

[0079] Table 1

[0080] linear expansion coefficient thermal shock performance Film performance Example 1 144 No abnormalities No abnormalities Example 2 153 No abnormalities No abnormalities Example 3 - - No abnormalities Comparative Example 1 186 cracking No abnormalities Comparative Example 2 - - There are bubbles Comparative Example 3 228 cracking No abnormalities

[0081] Referring to Table 1, Figure 9 The sample prepared in Example 1 showed no abnormalities on the surface of the package after thermal shock aging. Figure 10The sample prepared using Comparative Example 1 showed cracks on the surface of the encapsulation after thermal shock aging, indicating that the linear expansion coefficients of the protective layer and the fluorescent layer on the surface of the encapsulation are closer. Figure 11 The composite film prepared using the film application method of Example 1 showed no abnormalities on its surface. Figure 12 Comparative Example 2, using film lamination, produced composite films with air bubbles on their surface. For example... Figure 13 , 14 As shown, the prepared CSP exhibits excellent color temperature uniformity and resistance to yellowing through a specific fluorescent film.

Claims

1. A packaging method for a single-sided white light CSP, characterized in that, Includes the following steps: S1, fix the light-emitting chips on the substrate and encapsulate them with white adhesive film, then remove the white adhesive film from the light-emitting surface of the light-emitting chips to expose the light-emitting surface, so that the white adhesive film is flush with the light-emitting chips. S2, composite the OCA film and the fluorescent film, and then composite the OCA film surface onto the light-emitting surface of the light-emitting chip; S3, the semi-finished product obtained in S2 is cut once, glued, sealed with a protective film, and cut again to obtain a white CSP with single-sided light emission; The temperature at which the OCA film and the fluorescent film are laminated is 70-90℃; The encapsulation in S1 is performed using a vacuum press, with a pressing temperature of 90-120℃ and a pressing time of 5-15 minutes. The process parameters of the encapsulation protective film include: vacuum degree of 90-98 kPa, pressing temperature of 90-120℃, and pressing time of 5-15 min; The process parameters for laminating the OCA film onto the light-emitting chip include: a lamination temperature of 80-110℃ and a lamination pressure of 5-10kN.

2. A white light CSP with single-sided light emission prepared according to the method of claim 1, characterized in that, The device comprises a light-emitting chip, an OCA film, a fluorescent film, and a protective film, which are sequentially laminated together. The light-emitting surface of the light-emitting chip is laminated with the OCA film. The sidewalls of the light-emitting chip, the OCA film, and the fluorescent film are all filled with a white wall adhesive film. The protective film is prepared from silicone water and silica powder, with the silica powder content in the protective film being 40-70 wt%.

3. The single-sided white light CSP according to claim 2, characterized in that, The content of the silicon micropowder in the protective film is 40-60 wt%.

4. The single-sided white light CSP according to claim 2, characterized in that, The raw materials for preparing the white wall adhesive film include silicone water and titanium dioxide, and the content of titanium dioxide in the white wall adhesive film is 15-40 wt%.

5. The single-sided white light CSP according to claim 2, characterized in that, The raw materials for preparing the fluorescent film include fluorescent powder and silicone water, and the content of fluorescent powder in the fluorescent film is 40-70 wt%.

6. The single-sided white light CSP according to claim 2, characterized in that, The OCA film has a thickness of 10-30 micrometers, the fluorescent film has a thickness of 30-150 micrometers, and the protective film has a thickness of 50-200 micrometers.

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