Packaging process for high-stability LED

Abstract

The invention relates to the technical field of LED packaging, and provides a packaging process for a high-stability LED, which comprises the following steps: mounting an LED chip on a packaging carrier; forming an annular limiting glue layer in the circumferential direction of the LED chip in a dispensing manner; the limiting glue layer is subjected to pre-curing treatment, so that the limiting glue layer forms a cross-linking degree gradient in the radial direction, and the cross-linking degree of the area close to the outer side is higher than that of the area close to the inner side; when the inner side of the limiting glue layer is still in a wettable state, filling an area defined by the limiting glue layer with liquid fluorescent glue; after the fluorescent glue is filled, executing interface activation treatment on a contact interface of the limiting glue layer and the fluorescent glue; then the limiting glue layer and the fluorescent glue are jointly cured, so that the limiting glue layer and the fluorescent glue are fused at an interface, and a continuous fluorescent glue layer is formed; by means of the process, effective limiting is achieved in the fluorescent glue filling stage, meanwhile, it is avoided that a distinguishable limiting structure is reserved after packaging is completed, and the continuity and interface reliability of the packaging structure can be improved.

Description

Technical Field

[0001] This invention belongs to the field of LED packaging technology, and more specifically, relates to a packaging process for high-stability LEDs. Background Technology

[0002] In LED packaging technology, the morphological stability and interface reliability of the phosphor layer have a significant impact on luminous uniformity, luminous efficacy consistency, and long-term device reliability. In existing technologies, a phosphor layer is typically placed above or around the LED chip, allowing blue or ultraviolet light to be converted into the desired white or other colored light through fluorescence conversion.

[0003] In actual encapsulation processes, fluorescent adhesives are typically in a liquid or highly fluid state before curing, making them prone to spreading, collapsing, or accumulating during dispensing or curing, leading to uneven fluorescent layer thickness and positional misalignment. To address these issues, the following solutions are commonly used in existing technologies.

[0004] One approach involves using solid-state limiting structures, such as prefabricated dams, walls, or cavities, around the LED chip to restrict the flow range of the phosphor. While these structures can suppress the disordered diffusion of the phosphor to some extent, their permanent presence in the packaged product can create discontinuous interfaces within the encapsulation layer. This can lead to stress concentration during thermal cycling or long-term use and may also negatively impact the optical path.

[0005] Another approach involves pre-curing the fluorescent adhesive as a whole or using a semi-cured adhesive film to give it a certain degree of shape retention before dispensing, thereby reducing its flowability. However, this approach often struggles to balance shape stability and interfacial fusion requirements: when the pre-curing degree is high, the interfacial activity between the fluorescent adhesives decreases, which is not conducive to the full fusion of subsequent colloids; when the pre-curing degree is low, it is difficult to effectively limit the flow range of the fluorescent adhesive.

[0006] Furthermore, in encapsulation processes involving multiple dispensing or multilayer colloid structures, colloids in different curing states are often affected by surface tension, viscosity differences, and pre-crosslinking reactions at the contact interface, which can easily form a static interface boundary layer. This restricts the mutual penetration and fusion between colloids, thereby affecting the overall continuity of the encapsulation structure and the reliability of the interface.

[0007] Therefore, existing technologies still face the following problems in the LED packaging process: While effectively defining the fluorescent adhesive filling area, how to avoid the adverse effects of permanent limiting structures, and how to improve the sufficiency and stability of interfacial fusion between colloids in the presence of colloids in different curing states, still require further improvement. Summary of the Invention

[0008] This invention provides a packaging process for high-stability LEDs to overcome the aforementioned defects in the prior art.

[0009] The purpose and effectiveness of the packaging process for high-stability LEDs in this invention are achieved by the following specific technical means: A packaging process for high-stability LEDs includes the following steps: S1) Provide a packaging carrier and mount an LED chip on the packaging carrier; S2) A ring-shaped limiting adhesive layer is directly applied to the circumference of the LED chip; S3) The annular limiting adhesive layer is pre-cured to form a cross-linking gradient in the radial direction, wherein the cross-linking degree near the outer side is higher than that near the inner side. S4) While the inner side of the limiting adhesive layer is still in a wettable state, liquid fluorescent adhesive is filled into the area enclosed by the limiting adhesive layer. S5) After filling the liquid fluorescent adhesive, perform interface activation treatment on the contact interface between the limiting adhesive layer and the fluorescent adhesive. S6) Subsequently, the limiting adhesive layer and the fluorescent adhesive are co-cured, so that the limiting adhesive layer and the fluorescent adhesive fuse at the interface to form a continuous fluorescent adhesive layer. S7) A transparent encapsulation layer is formed on the outside of the fluorescent adhesive layer.

[0010] In a further technical solution, the pre-curing treatment is carried out by a combination of irradiation and masking. The mask is a ring-shaped structure covering the annular limiting adhesive layer, and the mask has different energy transmission characteristics along the radial direction to form the crosslinking degree gradient in the limiting adhesive layer.

[0011] In a further technical solution, the energy transmittance of the shield gradually decreases radially from the outside to the inside, causing the outer side of the limiting adhesive layer to cure preferentially, while the inner side maintains a low crosslinking state.

[0012] In a further technical solution, the pre-curing treatment is achieved by applying different irradiation intensities or irradiation times to different radial regions of the limiting adhesive layer to form the crosslinking degree gradient.

[0013] A further technical solution is that, after the pre-curing process is completed, the inner side of the limiting adhesive layer remains in a flowable, wettable, or swellable state to allow the subsequent filling of fluorescent adhesive to enter its inner area.

[0014] A further technical solution is that the interface activation process includes performing at least one vacuum decompression cycle on the encapsulation structure, so that the liquid fluorescent adhesive enters the low cross-linking region inside the limiting adhesive layer under the action of pressure difference.

[0015] A further technical solution is that the interface activation process includes applying vibration, ultrasound, or micro-mechanical disturbance to the encapsulation structure to break the static interface boundary layer formed between the limiting adhesive layer and the fluorescent adhesive.

[0016] In a further technical solution, the interface activation process is performed within a time window before the limiting adhesive layer has fully cured and the fluorescent adhesive has entered the rapid crosslinking stage.

[0017] In a further technical solution, the limiting adhesive layer and the fluorescent adhesive use the same or compatible matrix material, and their curing reactions overlap at least partially in time.

[0018] A further technical solution is that, after co-curing, the limiting adhesive layer and the fluorescent adhesive form a continuous colloidal structure at the interface, and there is no distinguishable limiting adhesive layer interface in the encapsulation structure.

[0019] Compared with the prior art, the present invention has the following beneficial effects: This invention achieves both effective containment during the fluorescent adhesive filling process and subsequent structural continuity by preferentially preparing a containment adhesive layer with a radial cross-linking gradient. Instead of employing a permanent solid containment structure, this invention pre-cures the annular containment adhesive layer to create a radial cross-linking gradient, effectively limiting its flow range during the fluorescent adhesive filling stage. During subsequent co-curing, the containment adhesive layer fuses with the fluorescent adhesive, preventing permanent containment structures from remaining in the finished encapsulation and improving the overall continuity of the encapsulation structure.

[0020] This invention provides favorable interface conditions for the fusion of inner and outer colloids by controlling the radial curing gradient. By preferentially curing the outer region of the limiting adhesive layer and maintaining a low cross-linking state in the inner region, the limiting adhesive layer has structural stability while its inner side still has high interfacial activity and wettability. This creates conditions for the subsequent filling fluorescent adhesive to enter the inner region of the limiting adhesive layer and undergo interfacial fusion, reducing the risk of the formation of an isolation layer at the interface due to premature curing.

[0021] This invention effectively overcomes the interfacial barrier between semi-cured colloid and liquid colloid through interface activation treatment. After the fluorescent adhesive is filled, interface activation methods such as vacuum decompression cycle, vibration, ultrasound or micro-mechanical disturbance are introduced to break the static boundary layer formed at the interface between the limiting adhesive layer and the fluorescent adhesive, promote the fluorescent adhesive to enter the low cross-linking region inside the limiting adhesive layer, thereby improving the contact sufficiency and fusion reliability between the inner and outer colloids.

[0022] This invention improves the stability and repeatability of the fusion process by controlling the interface activation time window. The interface activation process is limited to a time window before the limiting adhesive layer is fully cured and the phosphor has entered the rapid cross-linking stage. This ensures that both the inner and outer colloids are in a state of high interfacial activity, which is conducive to cross-linking or network interpenetration at the interface, thereby improving the stability and consistency of the encapsulation process. After co-curing, the limiting adhesive layer and phosphor form a continuous colloidal structure at the interface. The finished encapsulated product no longer has a distinguishable limiting adhesive layer interface, thus avoiding stress concentration or structural discontinuity problems that may be caused by permanent limiting structures, which is beneficial to improving the long-term reliability of LED packaging. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the packaging process for high-stability LEDs according to the present invention. Detailed Implementation

[0024] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0025] This invention provides a packaging process for high-stability LEDs, Example 1. A packaging process for high-stability LEDs includes the following steps: S1. First, a packaging carrier is provided, which can be a ceramic substrate, a metal substrate, or a composite substrate. An electrode structure is formed on the packaging carrier. Subsequently, an LED chip is mounted on the packaging carrier, so that the LED chip and the electrode structure are electrically connected.

[0026] S2, an annular limiting adhesive layer is directly formed around the LED chip by dotting. The limiting adhesive layer is set around the LED chip and is used to define the filling area of ​​the phosphor adhesive in subsequent processes.

[0027] S3. After forming the annular limiting adhesive layer, the limiting adhesive layer is pre-cured to make it enter a semi-cured state and form a cross-linking degree gradient in the radial direction, wherein the cross-linking degree of the region near the outer side is higher than that of the region near the inner side.

[0028] S4. While the inner side of the limiting adhesive layer is still wettable, liquid fluorescent adhesive is filled into the area enclosed by the limiting adhesive layer so that the fluorescent adhesive covers the light-emitting area of ​​the LED chip.

[0029] S5. After the fluorescent adhesive is filled, an interface activation treatment is performed on the contact interface between the limiting adhesive layer and the fluorescent adhesive. It should be noted that the interface activation treatment refers to the process of physically breaking the static boundary layer at the contact interface of the adhesive to promote the mutual penetration and fusion of the adhesives.

[0030] S6, the limiting adhesive layer and the fluorescent adhesive are co-cured, so that the two fuse at the interface to form a continuous fluorescent adhesive layer.

[0031] S7, a transparent encapsulation layer is formed on the outside of the phosphor layer to complete the LED encapsulation.

[0032] Example 2: In this example, a pre-curing process is provided, which is carried out by a combination of irradiation and masking.

[0033] Specifically, after the annular limiting adhesive layer is formed, an annular shield is placed on top of it, covering the annular limiting adhesive layer. The shield has different energy transmission characteristics along the radial direction, thereby causing the energy received by the limiting adhesive layer during irradiation to be unevenly distributed radially.

[0034] In this way, the outer region of the limiting adhesive layer receives more irradiation energy and preferentially undergoes cross-linking and curing, while the inner region receives less irradiation energy, thus maintaining a lower cross-linking state and forming a radial cross-linking gradient from the outside to the inside.

[0035] In one embodiment, the shield is a one-piece ring structure with light-transmitting regions of varying transmittance along its radial direction. For example, the outer region of the shield is a high-transmittance region, gradually transitioning to a medium-transmittance region and then a low-transmittance region towards the center, thereby causing the irradiation energy to gradually attenuate in the radial direction. This structural design allows for a radial curing gradient of the limiting adhesive layer without altering the parameters of the irradiation source.

[0036] In another embodiment, the shield includes concentric annular opening regions with different opening densities in different annular regions to create radially varying energy transmission characteristics.

[0037] Example 3: This example provides a radial crosslinking gradient formation method that does not rely on a masking structure. This is achieved by applying different irradiation intensities or durations to different radial regions of the limiting adhesive layer. Specifically, a zoned irradiation method can be used, irradiating the outer region of the limiting adhesive layer first, followed by the inner region. Alternatively, different irradiation intensities can be set for different regions, thereby creating a radial cross-linking gradient in the limiting adhesive layer.

[0038] Example 4 provides engineering criteria for the semi-cured state. After the pre-curing process is completed, the inner area of ​​the limiting adhesive layer remains in a flowable, wettable, or swellable state.

[0039] In this state, the limiting adhesive layer can maintain the overall annular structure without collapse during the fluorescent adhesive filling process, while its inner region allows the liquid fluorescent adhesive to enter and contact with it in subsequent processes, thus creating conditions for interface fusion.

[0040] Example 5: Implementation of interface-activated vacuum decompression cycle After the fluorescent adhesive is filled, the encapsulation structure is placed in a vacuum environment for vacuuming, and then restored to atmospheric pressure or positive pressure is applied. Through at least one vacuum-decompression cycle, the fluorescent adhesive is allowed to enter the low cross-linked region inside the limiting adhesive layer under the action of pressure difference, thereby breaking the static boundary layer at the interface.

[0041] Example 6: Interface-activated mechanical disturbance method Interface activation is achieved by applying vibration, ultrasound, or micro-mechanical disturbance to the encapsulation structure.

[0042] Specifically, after the fluorescent adhesive is filled, a low-amplitude, high-frequency vibration can be applied to the encapsulation carrier, or a dispensing head can be used to perform micro-amplitude reciprocating motion in the interface area to break the static interface boundary layer formed between the limiting adhesive layer and the fluorescent adhesive, thereby promoting the contact and fusion of the two.

[0043] Example 7: Time window control for interface activation In this embodiment, the interface activation process is performed within the time window when the limiting adhesive layer has not yet fully cured and the fluorescent adhesive has not yet entered the rapid crosslinking stage.

[0044] By controlling the pre-curing time, fluorescent adhesive filling time, and subsequent curing start time, the interface activation step is made to occur when both the inner and outer colloids have high interfacial activity, thereby improving the fusion effect.

[0045] Example 8: Material compatibility and curing window overlap In this embodiment, the limiting adhesive layer and the fluorescent adhesive use the same or compatible matrix material, such as both being silicone or resin systems.

[0046] Meanwhile, by controlling the curing conditions of both, the curing reactions of the limiting adhesive layer and the fluorescent adhesive overlap at least partially in time, thereby achieving cross-linking or network interpenetration at the interface during the co-curing process.

[0047] Example 9: Structural representation of the fusion result After co-curing, the limiting adhesive layer and the fluorescent adhesive form a continuous colloidal structure at the interface, and there is no longer a distinguishable interface between the limiting adhesive layer and the finished product.

[0048] In this way, the adhesive layer originally used for limiting only exists temporarily during the encapsulation process and does not constitute an independent structure after encapsulation is completed, thereby avoiding stress concentration or adverse optical effects that may be caused by permanent limiting structures.

[0049] The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. A packaging process for high-stability LEDs, characterized in that, Includes the following steps: S1) Provide a packaging carrier and mount an LED chip on the packaging carrier; S2) A ring-shaped limiting adhesive layer is directly applied to the circumference of the LED chip; S3) The annular limiting adhesive layer is pre-cured to form a cross-linking gradient in the radial direction, wherein the cross-linking degree near the outer side is higher than that near the inner side. S4) While the inner side of the limiting adhesive layer is still in a wettable state, liquid fluorescent adhesive is filled into the area enclosed by the limiting adhesive layer. S5) After filling the liquid fluorescent adhesive, perform interface activation treatment on the contact interface between the limiting adhesive layer and the fluorescent adhesive. S6) Subsequently, the limiting adhesive layer and the fluorescent adhesive are co-cured, so that the limiting adhesive layer and the fluorescent adhesive fuse at the interface to form a continuous fluorescent adhesive layer. S7) A transparent encapsulation layer is formed on the outside of the fluorescent adhesive layer.

2. The packaging process for high-stability LEDs as described in claim 1, characterized in that, The pre-curing process is carried out by a combination of irradiation and masking. The mask is a ring-shaped structure covering the annular limiting adhesive layer, and the mask has different energy transmission characteristics in the radial direction to form the crosslinking gradient in the limiting adhesive layer.

3. The packaging process for high-stability LEDs as described in claim 2, characterized in that, The energy transmittance of the shield gradually decreases radially from the outside to the inside, causing the outer side of the limiting adhesive layer to cure preferentially, while the inner side maintains a low cross-linking state.

4. The packaging process for high-stability LEDs as described in claim 1, characterized in that, The pre-curing process is achieved by applying different irradiation intensities or irradiation times to different radial regions of the limiting adhesive layer to form the crosslinking gradient.

5. The packaging process for high-stability LEDs as described in claim 1, characterized in that, After the pre-curing process is completed, the inner side of the limiting adhesive layer remains in a flowable, wettable, or swellable state to allow the subsequent filling of fluorescent adhesive to enter its inner region.

6. The packaging process for high-stability LEDs as described in claim 1, characterized in that, The interface activation process includes performing at least one vacuum decompression cycle on the encapsulation structure, allowing the liquid fluorescent adhesive to enter the low cross-linking region inside the limiting adhesive layer under pressure differential.

7. The packaging process for high-stability LEDs as described in claim 1, characterized in that, The interface activation process includes applying vibration, ultrasound, or micro-mechanical disturbance to the encapsulation structure to break the static interface boundary layer formed between the limiting adhesive layer and the fluorescent adhesive.

8. The packaging process for high-stability LEDs as described in claim 1, characterized in that, The interface activation process is performed within a time window before the limiting adhesive layer has fully cured and the fluorescent adhesive has entered the rapid cross-linking stage.

9. The packaging process for high-stability LEDs as described in claim 1, characterized in that, The limiting adhesive layer and the fluorescent adhesive use the same or compatible matrix material, and their curing reactions overlap at least partially in time.

10. The packaging process for high-stability LEDs as described in claim 1, characterized in that, After co-curing, the limiting adhesive layer and the fluorescent adhesive form a continuous colloidal structure at the interface, and there is no distinguishable limiting adhesive layer interface in the encapsulation structure.

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