A process for manufacturing flip-chip LED beads

Abstract

This invention discloses a flip-chip LED manufacturing process including steps such as preparing a cup-shaped base, pre-treating a metal substrate, assembling a support, die bonding, and encapsulation. By pre-treating the metal substrate, the mechanical strength and stability of the metal substrate and its adhesion to the base adhesive are enhanced, thereby improving the overall LED chip structure's resistance to breakage. The support assembly design reduces the risk of support separation or damage due to external stress. The die bonding process effectively disperses the external forces applied to the LED chip, reducing local stress concentration. The encapsulation process increases the overall flexibility of the LED chip structure and its ability to resist external impacts. Thus, multiple improvements in structure and process work together to significantly improve the LED chip's resistance to breakage.

Description

Technical Field

[0001] This invention relates to the field of LED packaging technology, specifically to a process for manufacturing flip-chip LEDs. Background Technology

[0002] With the development of LED technology, flip-chip LEDs have been widely used due to their high efficiency and high brightness. An LED chip consists of an LED chip and an LED chip support. The LED chip support is the base for the LED chip before encapsulation. The LED chip is fixed into the support, positive and negative electrodes are soldered on, and then encapsulated in one step with encapsulating adhesive to form the final LED chip product. However, existing flip-chip LEDs are prone to breakage and cracking during the encapsulation process due to thermal stress, external impact, or uneven adhesive layer, affecting their lifespan and reliability. Although there are various improvement methods in existing technologies, most focus on optimizing optical performance while neglecting improvements in structural strength. Summary of the Invention

[0003] To address the aforementioned challenges, this invention provides a process for manufacturing flip-chip LED chips, comprising the following steps:

[0004] Preparation of the bowl-shaped base: The bowl-shaped base is obtained through injection molding. It is made of epoxy resin or polyurethane resin. The bowl-shaped base has a first stepped groove and a second stepped groove arranged side-by-side along its length. A partition strip is provided between the first and second stepped grooves. This partition strip not only isolates electrical components, shares some external force, and disperses stress concentration points, but also restricts the relative movement of the L-shaped first substrate and the L-shaped second substrate, preventing the bracket from breaking due to vibration or impact, further improving the stability of the LED beads. The connection between the partition strip and the bowl-shaped base adopts a smooth transition design. This smooth transition design further reduces stress concentration points and better resists external impacts. The interior of the bowl-shaped base has the first and second stepped grooves... The stepped groove is surrounded by reinforcing ribs, which can effectively disperse external forces and reduce local stress concentration. The bowl-shaped base has a first positioning protrusion and a second positioning protrusion along the first stepped groove, and a third positioning protrusion and a fourth positioning protrusion along the second stepped groove. A layer of thermally conductive silicone pad is provided at the bottom of the bowl-shaped base. The addition of the thermally conductive silicone pad can improve the heat dissipation efficiency of the bracket and prevent local overheating from causing structural damage. On the other hand, it can provide a buffering effect when the bracket is subjected to external impact, reducing the direct impact force. Limiting protrusions are provided at both ends of the bottom of the bowl-shaped base. The surface of the internal cavity of the bowl-shaped base is silver-plated to form a reflective cup. The silver-plated reflective cup has both high reflectivity and surface smoothness, reducing stress concentration points caused by colloid filling defects.

[0005] Pre-treatment of metal substrates: The metal substrates are cut and polished to obtain L-shaped first substrates and L-shaped second substrates of the same shape. The metal substrates are made of any material, such as gold, silver, or copper. Using metals with high conductivity and certain toughness, such as gold, silver, or copper, to prepare the L-shaped first substrate and L-shaped second substrates helps the LED lamp bead bracket to provide sufficient mechanical strength while ensuring electrical performance. Both the L-shaped first substrate and L-shaped second substrate are provided with limiting through holes. The L-shaped first substrate is provided with a first step, a first positioning groove, and a second positioning groove. The L-shaped second substrate is provided with a second step, a third positioning groove, and a fourth positioning groove. The L-shaped first substrate and L-shaped second substrate are chemically nickel-plated to form a nickel-plated layer on their surfaces. The nickel-plated layer can improve the surface hardness and corrosion resistance of the metal substrate. Then, the L-shaped first substrate and L-shaped second substrate are sequentially cleaned, acid-washed, alkali-washed, and chemically activated to improve the adhesion of the primer and ensure a strong bond between the metal substrate and the primer, reducing the risk of delamination. The primer is then applied and heat-cured for later use.

[0006] Bracket assembly: The cup-shaped base is placed on the metal substrate. The L-shaped first substrate is fixed by the first step and the first stepped groove. The L-shaped second substrate is fixed by the second step and the second stepped groove. The first positioning protrusion and the first positioning groove are engaged, the second positioning protrusion and the second positioning groove are engaged, the third positioning protrusion and the third positioning groove are engaged, the fourth positioning protrusion and the fourth positioning groove are engaged, and the limiting protrusion and the limiting through hole are engaged for fixation. In this way, the mechanical interlocking enhances the bonding force between the metal substrate and the base, so that the substrate can be firmly fixed on the cup-shaped base. Even when subjected to external impact, it is not easy to shift or fall off, which increases the stability and fracture resistance of the entire component.

[0007] Die bonding: A solder paste film is coated on the die bonding area of ​​the metal substrate, and flip-chip LEDs are applied with a flip-chip precision controlled within ±10μm. The chips are then bonded to the metal substrate by reflow soldering under a nitrogen protective atmosphere. After reflow soldering, the cooling rate is controlled to ≤3℃ / s. High-precision solder paste coating combined with nitrogen-protected reflow soldering ensures uniform soldering between the flip-chip and the metal substrate, reduces voids and cold solder joints, and improves the mechanical strength of the solder joints. Controlling the cooling rate avoids increased solder joint brittleness caused by rapid cooling and reduces the risk of microcracks in the support structure caused by thermal stress.

[0008] Sealing: Quantum dot adhesive is filled into the reflector cup and initially cured. After cooling to 20-40℃, silicone is filled and cured a second time to obtain the finished product. Using high-viscosity quantum dot adhesive ensures that the adhesive adheres tightly to the reflector cup during the initial curing, reducing interfacial gaps; the secondary filling with silicone forms a buffer layer to absorb external impact energy.

[0009] Preferably, during the pretreatment of the metal substrate, the L-shaped first substrate and the L-shaped second substrate are first ultrasonically cleaned with isopropanol for 10-15 minutes, then acid-washed with 3-7 wt% dilute hydrochloric acid for 5-10 minutes, followed by alkaline washing with 3-7 wt% sodium hydroxide solution for 10-15 minutes, then chemically activated with a mixed solution of sulfuric acid and hydrogen peroxide in a volume ratio of 2-4:1, and finally rinsed with deionized water to completely remove the activation solution.

[0010] Preferably, during the pretreatment of the metal substrate, epoxy resin or polyurethane resin is selected as the primer, and the primer coating thickness is 10-20 μm. The metal substrate coated with primer is placed in an oven for heat curing treatment at a temperature of 110-130°C for 20-40 minutes.

[0011] Preferably, the thickness of the solder paste film layer during the die bonding process is 80-100 μm, and the thickness error of the solder paste film layer is controlled within ±3 μm.

[0012] Preferably, the reflow soldering temperature during the die bonding process is 260–290°C and the time is 30–60 seconds.

[0013] Preferably, quantum dot adhesive with a viscosity of 4000–6000 mPa·s (25°C) is used to fill the reflective cup during the sealing process.

[0014] Preferably, the reflective cup is filled with silicone with a viscosity of 3000-5000 mPa·s (25℃) during the sealing process.

[0015] Preferably, the initial curing temperature during the sealing process is 50–100°C, with a stepped temperature increase from 50°C to 75–85°C and then to 100°C, holding each stage for 5–10 minutes. Using a stepped temperature increase during the initial curing process can gradually release the curing shrinkage stress of the quantum dot adhesive.

[0016] Preferably, the secondary curing temperature during the sealing process is 100–120°C, using a stepped temperature increase from 100°C to 105–115°C and then to 120°C, with each stage held for 5–10 minutes. This stepped temperature increase during secondary curing optimizes the silicone crosslinking density, forming a buffer layer that, together with the quantum dot adhesive layer, creates a rigidity-toughness gradient structure, effectively resisting bending and breakage.

[0017] The beneficial effect lies in the fact that this application significantly improves the fracture resistance of LED chips through the combined effect of the following aspects, including:

[0018] Metal substrate pretreatment: The L-shaped first and second substrates are electroless nickel-plated and then subjected to a series of cleaning, acid pickling, alkali washing, and chemical activation treatments. This not only enhances the corrosion resistance of the metal substrate surface but also improves the bonding strength with other materials (such as primer) in subsequent processes. In addition, applying primer and performing thermosetting treatment further enhances the mechanical strength and stability of the metal substrate, helping to improve the overall structure's resistance to breakage.

[0019] The bracket assembly design utilizes precisely designed first and second steps and stepped grooves, along with the fixing method of limiting protrusions and limiting through holes, to ensure a firm and stable connection between the cup-shaped base and the metal substrate. This design reduces the risk of bracket separation or damage due to external stress, thereby indirectly improving its fracture resistance.

[0020] Die bonding process control: During the die bonding process, the flip chip accuracy (within ±10μm) and the thickness and error of the solder paste film layer (80~100μm, with the error controlled within ±3μm) are strictly controlled to ensure good contact and soldering quality between the chip and the metal substrate, effectively disperse the external force applied to the LED beads, reduce local stress concentration, and thus improve the overall fracture resistance.

[0021] Sealing process: Quantum dot adhesive and silicone are used to fill the reflective cup in stages, and a stepped heating method is used for primary and secondary curing. This sealing method not only provides good optical performance, but also effectively protects the internal structure from the influence of the external environment, while providing an additional buffer protection layer for the chip, increasing the overall structural flexibility and resistance to external impacts. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0023] Figure 1 This is a schematic diagram of the structure from a first perspective of the present invention;

[0024] Figure 2 This is a schematic diagram of the second perspective structure of the present invention;

[0025] Figure 3 This is a schematic diagram of the exploded structure of the present invention;

[0026] In the picture:

[0027] 1. Bowl-shaped base; 11. First stepped groove; 12. Second stepped groove; 13. Partition strip; 14. Limiting protrusion; 15. First positioning protrusion; 16. Second positioning protrusion; 17. Third positioning protrusion; 18. Fourth positioning protrusion;

[0028] 2. Metal substrate; 21. L-shaped first substrate; 211. First step; 212. First positioning groove; 213. Second positioning groove; 22. L-shaped second substrate; 221. Second step; 222. Third positioning groove; 223. Fourth positioning groove; 23. Limiting through hole. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention.

[0030] The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. All other embodiments obtained by those skilled in the art based on the specific embodiments of the invention without inventive effort are within the protection scope of the invention.

[0031] In the embodiments of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; in the embodiments of the present invention, unless specifically specified, the technical means used are conventional means well known to those skilled in the art.

[0032] Example 1

[0033] like Figures 1 to 3 As shown, Figure 1 This is a first-view structural diagram of the present invention. Figure 2 This is a schematic diagram of the second perspective structure of the present invention. Figure 3 This is a schematic diagram of the exploded structure of the present invention. This embodiment provides a process for manufacturing flip-chip LED beads, including the following steps:

[0034] Preparation of the bowl-shaped base 1: The bowl-shaped base 1 is obtained by injection molding. The bowl-shaped base 1 is made of epoxy resin or polyurethane resin. The bowl-shaped base 1 has a first stepped groove 11 and a second stepped groove 12 arranged side by side along its length. A partition strip 13 is provided between the first stepped groove 11 and the second stepped groove 12. The connection between the partition strip 13 and the bowl-shaped base 1 adopts a smooth transition design. Reinforcing ribs are provided around the first stepped groove 11 and the second stepped groove 12 inside the bowl-shaped base 1. The bowl-shaped base 1 has a first positioning protrusion 15 and a second positioning protrusion 16 along the first stepped groove 11. The bowl-shaped base 1 has a third positioning protrusion 17 and a fourth positioning protrusion 18 along the second stepped groove 12. A layer of thermally conductive silicone pad is provided at the bottom of the bowl-shaped base 1. Limiting protrusions 14 are provided at both ends of the bottom of the bowl-shaped base 1. Silver is plated on the surface of the internal cavity of the bowl-shaped base 1 to form a reflective cup.

[0035] Pre-processing of metal substrates: The metal substrate 2 is cut and polished to obtain an L-shaped first substrate 21 and an L-shaped second substrate 22 of the same shape. The metal substrate 2 is made of any material, such as gold, silver, or copper. Both the L-shaped first substrate 21 and the L-shaped second substrate 22 are provided with limiting through holes 23. The L-shaped first substrate 21 is provided with a first step 211, a first positioning groove 212, and a second positioning groove 213. The L-shaped second substrate 22 is provided with a second step 221, a third positioning groove 222, and a fourth positioning groove 223. The L-shaped first substrate 21 and the L-shaped second substrate 22 are chemically plated with nickel to form a nickel plating layer on their surfaces. Then, the L-shaped first substrate 21 and the L-shaped second substrate 22 are sequentially processed. 22 undergoes cleaning, acid washing, alkali washing, and chemical activation treatment, followed by coating with a primer and heat curing for later use. Specifically: first, the L-shaped first substrate 21 and L-shaped second substrate 22 are ultrasonically cleaned with isopropanol for 10 minutes, then acid-washed with 3wt% dilute hydrochloric acid for 5 minutes, followed by alkali washing with 3wt% sodium hydroxide solution for 10 minutes, then chemically activated with a 2:1 volume ratio of sulfuric acid and hydrogen peroxide mixed solution, and finally rinsed with deionized water to completely remove the activation solution. The primer is made of epoxy resin or polyurethane resin, with a primer coating thickness of 10μm. The metal substrate 2 coated with the primer is placed in an oven for heat curing at 110℃ for 20 minutes.

[0036] Bracket assembly: Place the bowl-shaped base 1 on the metal substrate 2. The L-shaped first substrate 21 is fixed by engaging the first step 211 with the first stepped groove 11. The L-shaped second substrate 22 is fixed by engaging the second step 221 with the second stepped groove 12. The first positioning protrusion 15 engages with the first positioning groove 212. The second positioning protrusion 16 engages with the second positioning groove 213. The third positioning protrusion 17 engages with the third positioning groove 222. The fourth positioning protrusion 18 engages with the fourth positioning groove 223. The limiting protrusion 14 engages with the limiting through hole 23 for fixation.

[0037] Die bonding: A solder paste film layer is coated on the die bonding area of ​​the metal substrate 2. The thickness of the solder paste film layer is 80μm, and the thickness error of the solder paste film layer is controlled within ±3μm. The flip-chip is flipped with a precision controlled within ±10μm. The LED chip is then bonded to the metal substrate 2 by reflow soldering under a nitrogen protective atmosphere. The reflow soldering temperature is 260℃ and the time is 30s. After reflow soldering, the cooling rate is controlled to be ≤3℃ / s.

[0038] Sealing: Fill the reflective cup with quantum dot adhesive with a viscosity of 4000 mPa·s (25℃) and perform initial curing. The initial curing temperature is 50-100℃, using a step-by-step temperature increase from 50℃ to 75℃ and then to 100℃, holding each stage for 5 minutes. After cooling to 20℃, fill with silicone with a viscosity of 3000 mPa·s (25℃) and perform secondary curing. The secondary curing temperature is 100-120℃, using a step-by-step temperature increase from 100℃ to 105℃ and then to 120℃, holding each stage for 5 minutes to obtain the finished product.

[0039] Example 2

[0040] like Figures 1 to 3 As shown, Figure 1 This is a first-view structural diagram of the present invention. Figure 2 This is a schematic diagram of the second perspective structure of the present invention. Figure 3 This is a schematic diagram of the exploded structure of the present invention. This embodiment provides a process for manufacturing flip-chip LED beads, including the following steps:

[0041] Preparation of the bowl-shaped base 1: The bowl-shaped base 1 is obtained by injection molding. The bowl-shaped base 1 is made of epoxy resin or polyurethane resin. The bowl-shaped base 1 has a first stepped groove 11 and a second stepped groove 12 arranged side by side along its length. A partition strip 13 is provided between the first stepped groove 11 and the second stepped groove 12. The connection between the partition strip 13 and the bowl-shaped base 1 adopts a smooth transition design. Reinforcing ribs are provided around the first stepped groove 11 and the second stepped groove 12 inside the bowl-shaped base 1. The bowl-shaped base 1 has a first positioning protrusion 15 and a second positioning protrusion 16 along the first stepped groove 11. The bowl-shaped base 1 has a third positioning protrusion 17 and a fourth positioning protrusion 18 along the second stepped groove 12. A layer of thermally conductive silicone pad is provided at the bottom of the bowl-shaped base 1. Limiting protrusions 14 are provided at both ends of the bottom of the bowl-shaped base 1. Silver is plated on the surface of the internal cavity of the bowl-shaped base 1 to form a reflective cup.

[0042] Pre-processing of metal substrates: Metal substrate 2 is cut and polished to obtain L-shaped first substrate 21 and L-shaped second substrate 22 with the same shape. Metal substrate 2 is made of any material selected from gold, silver, and copper. Both L-shaped first substrate 21 and L-shaped second substrate 22 are provided with limiting through holes 23. The L-shaped first substrate is provided with a first step 211, a first positioning groove 212, and a second positioning groove 213. The L-shaped second substrate is provided with a second step 221, a third positioning groove 222, and a fourth positioning groove 223. The L-shaped first substrate 21 and L-shaped second substrate 22 are chemically plated with nickel to form a nickel plating layer on their surfaces. Then, the L-shaped first substrate 21 and L-shaped second substrate 22 are sequentially processed. The substrate undergoes cleaning, acid washing, alkali washing, and chemical activation treatment, followed by coating with a primer and heat curing. Specifically: First, the L-shaped first substrate 21 and L-shaped second substrate 22 are ultrasonically cleaned with isopropanol for 12 minutes. Then, they are acid-washed with 5wt% dilute hydrochloric acid for 7 minutes, followed by alkali washing with 5wt% sodium hydroxide solution for 13 minutes. Next, they are chemically activated with a 3:1 volume ratio of sulfuric acid and hydrogen peroxide mixture, and then rinsed with deionized water to completely remove the activation solution. The primer is made of epoxy resin or polyurethane resin, with a primer coating thickness of 15μm. The primer-coated metal substrate 2 is then placed in an oven for heat curing at 120℃ for 30 minutes.

[0043] Bracket assembly: Place the bowl-shaped base 1 on the metal substrate 2. The L-shaped first substrate 21 is fixed by engaging the first step 211 with the first stepped groove 11. The L-shaped second substrate 22 is fixed by engaging the second step 221 with the second stepped groove 12. The first positioning protrusion 15 engages with the first positioning groove 212. The second positioning protrusion 16 engages with the second positioning groove 213. The third positioning protrusion 17 engages with the third positioning groove 222. The fourth positioning protrusion 18 engages with the fourth positioning groove 223. The limiting protrusion 14 engages with the limiting through hole 23 for fixation.

[0044] Die bonding: A solder paste film layer is coated in the die bonding area of ​​the metal substrate 2. The thickness of the solder paste film layer is 90μm, and the thickness error of the solder paste film layer is controlled within ±3μm. The flip-chip is flipped with a precision controlled within ±10μm. The flip-chip is then bonded to the metal substrate 2 by reflow soldering under a nitrogen protective atmosphere. The reflow soldering temperature is 275℃ and the time is 45s. After reflow soldering, the cooling rate is controlled to be ≤3℃ / s.

[0045] Sealing: Fill the reflective cup with quantum dot adhesive with a viscosity of 5000 mPa·s (25℃) and perform initial curing. The initial curing temperature is 50-100℃, using a step-by-step temperature increase from 50℃ to 80℃ and then to 100℃, holding each stage for 7 minutes. After cooling to 30℃, fill with silicone with a viscosity of 3000 mPa·s (25℃) and perform secondary curing. The secondary curing temperature is 100-120℃, using a step-by-step temperature increase from 100℃ to 110℃ and then to 120℃, holding each stage for 7 minutes to obtain the finished product.

[0046] Example 3

[0047] like Figures 1 to 3 As shown, Figure 1 This is a first-view structural diagram of the present invention. Figure 2 This is a schematic diagram of the second perspective structure of the present invention. Figure 3 This is a schematic diagram of the exploded structure of the present invention. This embodiment provides a process for manufacturing flip-chip LED beads, including the following steps:

[0048] Preparation of the bowl-shaped base 1: The bowl-shaped base 1 is obtained by injection molding. The bowl-shaped base 1 is made of epoxy resin or polyurethane resin. The bowl-shaped base 1 has a first stepped groove 11 and a second stepped groove 12 arranged side by side along its length. A partition strip 13 is provided between the first stepped groove 11 and the second stepped groove 12. The connection between the partition strip 13 and the bowl-shaped base 1 adopts a smooth transition design. Reinforcing ribs are provided around the first stepped groove 11 and the second stepped groove 12 inside the bowl-shaped base 1. The bowl-shaped base 1 has a first positioning protrusion 15 and a second positioning protrusion 16 along the first stepped groove 11. The bowl-shaped base 1 has a third positioning protrusion 17 and a fourth positioning protrusion 18 along the second stepped groove 12. A layer of thermally conductive silicone pad is provided at the bottom of the bowl-shaped base 1. Limiting protrusions 14 are provided at both ends of the bottom of the bowl-shaped base 1. Silver is plated on the surface of the internal cavity of the bowl-shaped base 1 to form a reflective cup.

[0049] Pre-processing of metal substrates: Metal substrate 2 is cut and polished to obtain L-shaped first substrate 21 and L-shaped second substrate 22 with the same shape. Metal substrate 2 is made of any material selected from gold, silver, and copper. Both L-shaped first substrate 21 and L-shaped second substrate 22 are provided with limiting through holes 23. The L-shaped first substrate is provided with a first step 211, a first positioning groove 212, and a second positioning groove 213. The L-shaped second substrate is provided with a second step 221, a third positioning groove 222, and a fourth positioning groove 223. The L-shaped first substrate 21 and L-shaped second substrate 22 are chemically plated with nickel to form a nickel plating layer on their surfaces. Then, the L-shaped first substrate 21 and L-shaped second substrate 22 are sequentially processed. The substrate undergoes cleaning, acid washing, alkali washing, and chemical activation treatment, followed by coating with a primer and heat curing. Specifically: First, the L-shaped first substrate 21 and L-shaped second substrate 22 are ultrasonically cleaned with isopropanol for 15 minutes. Then, they are acid-washed with 7wt% dilute hydrochloric acid for 15 minutes, followed by alkali washing with 7wt% sodium hydroxide solution for 15 minutes. Next, they are chemically activated with a 4:1 volume ratio mixture of sulfuric acid and hydrogen peroxide, and then rinsed with deionized water to completely remove the activation solution. The primer is made of epoxy resin or polyurethane resin, with a primer coating thickness of 20μm. The primer-coated metal substrate 2 is then placed in an oven for heat curing at 130℃ for 40 minutes.

[0050] Bracket assembly: Place the bowl-shaped base 1 on the metal substrate 2. The L-shaped first substrate 21 is fixed by engaging the first step 211 with the first stepped groove 11. The L-shaped second substrate 22 is fixed by engaging the second step 221 with the second stepped groove 12. The first positioning protrusion 15 engages with the first positioning groove 212. The second positioning protrusion 16 engages with the second positioning groove 213. The third positioning protrusion 17 engages with the third positioning groove 222. The fourth positioning protrusion 18 engages with the fourth positioning groove 223. The limiting protrusion 14 engages with the limiting through hole 23 for fixation.

[0051] Die bonding: A solder paste film layer is coated in the die bonding area of ​​the metal substrate 2. The thickness of the solder paste film layer is 100μm and the thickness error is controlled within ±3μm. The flip-chip is flipped with a precision controlled within ±10μm. The flip-chip is then bonded to the metal substrate 2 by reflow soldering under a nitrogen protective atmosphere. The reflow soldering temperature is 290℃ and the time is 60s. After reflow soldering, the cooling rate is controlled to be ≤3℃ / s.

[0052] Sealing: Fill the reflective cup with quantum dot adhesive with a viscosity of 6000 mPa·s (25℃) and perform initial curing. The initial curing temperature is 100℃, and the temperature is increased stepwise from 50℃ to 85℃ and then to 100℃, with each stage held for 10 minutes. After cooling to 40℃, fill with silicone with a viscosity of 5000 mPa·s (25℃) and perform secondary curing. The secondary curing temperature is 120℃, and the temperature is increased stepwise from 100℃ to 115℃ and then to 120℃, with each stage held for 10 minutes to obtain the finished product.

[0053] Test method:

[0054] Ten flip-chip LEDs prepared in various embodiments of this application were randomly selected and tested using a three-point bending test method. The test temperature was 25±2℃ and the humidity was 50±5% RH. Ten existing flip-chip LEDs (all colors, purchased from Suzhou Xinjingding Electronics Co., Ltd.) were used as a control group. The test results are shown in Table 1.

[0055] Table 1. Test Results of Various Performance Aspects of LED Chips

[0056]

[0057]

[0058] Note: The letter 'a' indicates a highly significant difference (P<0.01), and the letter 'b' indicates a non-significant difference (P>0.05).

[0059] The above results show that the performance indicators of the flip-chip LEDs prepared in Examples 1-3 are significantly better than those of existing flip-chip LEDs, with the maximum load increasing by more than 40%. This is likely due to the enhanced deformation resistance of the metal substrate surface by the nickel plating layer, and the precise design of the fit between the first step, the second step, and the stepped groove, as well as the fixing method of the limiting protrusion and the limiting through hole, which ensures a firm and stable connection between the cup-shaped base and the metal substrate. This reduces the risk of bracket separation or damage due to external stress, improves the bracket's fracture resistance, and allows the LED to withstand higher external impacts. The fracture deflection increases by 75%, and the bending... The bending strength increased by over 50%, and the fracture energy increased by over 80%. This may be because the strict control of flip-chip precision and solder paste film thickness and its error during the die bonding process ensures good contact and welding quality between the chip and the substrate, effectively dispersing the external force applied to the LED beads, reducing local stress concentration, and thus improving the overall fracture resistance. Secondly, the buffer layer of the silicone secondary encapsulation can also absorb deformation energy. The stepped curing process reduces the stress in the colloid and delays crack propagation. The synergistic encapsulation of quantum dot adhesive and silicone forms a gradient mechanical structure, which significantly enhances the overall fatigue resistance of the LED beads, exhibits higher toughness when bent, and avoids brittle fracture.

[0060] In summary, this application significantly improves the breakage resistance of LED chips through improvements in multiple aspects, including metal substrate pretreatment, bracket assembly design, die bonding process control, and encapsulation treatment.

[0061] The above are merely embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A process for manufacturing flip-chip LED beads, characterized in that, Includes the following steps: Preparation of bowl-shaped base: The bowl-shaped base is obtained by injection molding. The bowl-shaped base has a first stepped groove and a second stepped groove arranged side by side along its length. A partition strip is provided between the first stepped groove and the second stepped groove. Limiting protrusions are provided at both ends of the bottom of the bowl-shaped base. Silver is plated on the surface of the inner cavity of the bowl-shaped base to form a reflective cup. Pre-treatment of metal substrates: The metal substrates are cut and polished to obtain L-shaped first substrates and L-shaped second substrates of the same shape. Both L-shaped first substrates and L-shaped second substrates are provided with limiting through holes. The L-shaped first substrate is provided with a first step and the L-shaped second substrate is provided with a second step. The L-shaped first substrates and L-shaped second substrates are chemically nickel-plated to form a nickel-plated layer on their surfaces. Then, the L-shaped first substrates and L-shaped second substrates are sequentially cleaned, acid-washed, alkali-washed and chemically activated. A primer is applied and heat-cured for later use. Bracket assembly: The bowl-shaped base is placed on the metal substrate. The L-shaped first substrate is fixed by the first step and the first stepped groove. The L-shaped second substrate is fixed by the second step and the second stepped groove. The limiting protrusion is fixed by the limiting through hole. Die bonding: A solder paste film is coated on the die bonding area of ​​the metal substrate, and a flip-chip LED is flipped with a flip-chip accuracy controlled within ±10μm. The LED chip is then bonded to the metal substrate by reflow soldering under a nitrogen protective atmosphere. After reflow soldering, the cooling rate is controlled to be ≤3℃ / s. Sealing: Quantum dot adhesive is filled into the reflective cup and initially cured. After cooling to 20-40°C, silicone is filled and cured a second time to obtain the finished product.

2. The flip-chip LED manufacturing process according to claim 1, characterized in that, In the pretreatment process of the metal substrate, the L-shaped first substrate and the L-shaped second substrate are first ultrasonically cleaned with isopropanol for 10-15 minutes, then acid-washed with 3-7 wt% dilute hydrochloric acid for 5-10 minutes, then alkaline-washed with 3-7 wt% sodium hydroxide solution for 10-15 minutes, then chemically activated with a mixed solution of sulfuric acid and hydrogen peroxide in a volume ratio of 2-4:1, and finally rinsed with deionized water to completely remove the activation solution.

3. The flip-chip LED manufacturing process according to claim 1, characterized in that, During the pretreatment of the metal substrate, the primer is selected from epoxy resin or polyurethane resin, and the primer coating thickness is 10-20 μm. The metal substrate coated with primer is placed in an oven for heat curing treatment at a temperature of 110-130°C for 20-40 minutes.

4. The flip-chip LED manufacturing process according to claim 1, characterized in that, During the die bonding process, the thickness of the solder paste film layer is 80-100 μm, and the thickness error of the solder paste film layer is controlled within ±3 μm.

5. The flip-chip LED manufacturing process according to claim 1, characterized in that, The reflow soldering temperature during the die bonding process is 260–290°C, and the time is 30–60 seconds.

6. The flip-chip LED manufacturing process according to claim 1, characterized in that, The reflective cup is filled with quantum dot adhesive with a viscosity of 4000-6000 mPa·s (25°C) during the sealing process.

7. The flip-chip LED manufacturing process according to claim 1, characterized in that, During the sealing process, silicone with a viscosity of 3000–5000 mPa·s (25°C) is used to fill the reflective cup.

8. The flip-chip LED manufacturing process according to claim 1, characterized in that, The initial curing temperature during the sealing process is 50-100℃, and the temperature is increased in stages from 50℃ to 75-85℃ and then to 100℃, with each stage held for 5-10 minutes.

9. The flip-chip LED manufacturing process according to claim 1, characterized in that, The secondary curing temperature during the sealing process is 100-120℃, and the temperature is increased in stages from 100℃ to 105-115℃ and then to 120℃, with each stage being held for 5-10 minutes.

Images