LED chip electrode

Abstract

The invention discloses an LED chip electrode, and belongs to the technical field of semiconductor photoelectric devices. The LED chip comprises a chip body, an electrode bonding pad arranged on the periphery of the chip body and a finger gold wire electrode arranged on the surface of the chip body. The number of the electrode bonding pads is four or more, and the electrode bonding pads are symmetrically distributed along the periphery of the chip body at equal intervals. The finger gold wire electrodes are distributed at equal intervals, and the interval between every two adjacent finger gold wire electrodes is determined according to the following formula: Ls = n * sqrt (Rc / Rs), Ls is the interval between the finger gold wire electrodes, n is an electrode bonding pad factor, Rc is the contact resistance between the finger gold wire electrodes and the chip body, and Rs is the square resistance of the chip body. According to the invention, the electrode bonding pads are additionally arranged on the periphery of the chip, and the distance between the finger gold wire electrodes on the surface of the chip is improved, so that the lamp bead still has the index requirement of high luminous efficiency under the high-temperature condition of high current + 85 DEG C or above.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor optoelectronic device technology, and more specifically, relates to an LED chip electrode. Background Technology

[0002] With the rapid development of modern agriculture, plant supplemental lighting technology has become a key support for improving crop yield and quality. LED lighting fixtures, due to their low energy consumption and highly adjustable spectrum, are widely used in plant supplemental lighting. In plant supplemental lighting scenarios, the luminous efficacy of the lighting fixture directly determines the supplemental lighting efficiency, and the luminous efficacy performance of LED chips, as the core light-emitting element of the fixture, is a decisive factor in the overall lighting effect. At the same time, the industry has imposed stringent requirements on the obstruction area of ​​the lighting fixture, which also limits the light-emitting area of ​​LED chips from being too large.

[0003] To meet the aforementioned needs in plant supplemental lighting, the industry has set core performance requirements for LED chips: "high current + high luminous efficacy." Specifically, to achieve high light output within a limited luminous area, the operating current of the LED chips needs to be increased from the traditional 700mA to 2000mA. Theoretically, this can achieve high light output, but it places extremely high demands on the design of the gold-wire electrodes on the LED chip surface. Increased current leads to uneven current distribution within the LED chip. Traditional solutions address this by increasing the number of gold-wire electrodes or increasing the electrode linewidth. However, increasing the number or linewidth inevitably increases the proportion of electrode shading on the chip surface—the larger the area of ​​the chip's luminous region blocked by the electrodes, the smaller the effective area for light emission, directly resulting in a significant reduction in luminous efficacy. This contradicts the core requirement of high luminous efficacy for LED chips, making balancing these design specifications an insurmountable challenge.

[0004] Furthermore, considering the actual operating conditions of plant supplemental lighting fixtures, it is usually necessary to ensure that LED chips still maintain high luminous efficacy when used at high temperatures of 85℃ and above. Therefore, the industry urgently needs to solve these problems to achieve the requirement that LED chips maintain high luminous efficacy under high current and high temperature conditions of 85℃ and above. Summary of the Invention

[0005] To address the shortcomings mentioned in the background art, this invention provides an LED chip electrode. By adding electrode pads around the chip and improving the spacing of the gold wire electrodes on the chip surface, the high luminous efficacy requirement of the LED chip is effectively achieved even under high current and high temperature conditions of +85℃ and above.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides an LED chip electrode, comprising a chip body, electrode pads disposed around the chip body, and gold wire electrodes disposed on the surface of the chip body; wherein: The electrode pads are four or more, and are symmetrically and equally spaced along the periphery of the chip body; The gold wire electrodes on the fingers are evenly spaced, and the spacing between two adjacent gold wire electrodes is determined according to the following formula: L s =n*sqrt( R c / R s ) Among them, L s R represents the spacing between the gold wire electrodes, n is the electrode pad factor, specifically the number of electrode pads. c R represents the contact resistance between the gold wire electrode of the finger and the chip body. s This refers to the sheet resistance of the chip itself.

[0007] It should be noted that one of the core determinants of LED luminous efficacy is the performance of the LED chip. Under extreme operating conditions of 2000mA high current and temperatures above 85℃, the design of the gold-plated electrodes on the chip surface becomes a key bottleneck restricting the maintenance of high luminous efficacy in lamps. Under these conditions, extremely high requirements are placed on the electrode's current carrying capacity, heat dissipation performance, current spread uniformity, and resistance to high-temperature aging. Existing electrode designs are no longer suitable. Current design solutions mainly suffer from the following contradictions: First, under high-current design, there is a contradiction between the high current conduction requirement and the uniformity of current distribution. In order to carry a high current of 2000mA, increasing the number of finger gold wire electrodes or increasing the electrode linewidth will obviously lead to a significant increase in the proportion of electrodes blocking the chip's light-emitting area. At the same time, it is easy to cause the current to concentrate in the area near the electrodes, while the current distribution in the light-emitting area at the edge of the chip is sparse, resulting in the phenomenon of "overcurrent at the origin and undercurrent at the edge". This not only reduces the luminous efficiency, but also aggravates the local heat generation of the chip due to uneven current distribution, further deteriorating the luminous efficiency stability under high-temperature conditions.

[0008] Secondly, temperatures above 85℃ accelerate the aging of the contact interface between the gold wire electrode and the chip, leading to increased contact resistance and generating additional Joule heat, forming localized hot spots. Traditional gold wire-chip bonding structures are prone to thermal fatigue at high temperatures, resulting in decreased bonding strength, poor conductivity, and a sharp drop in LED luminous efficacy or even LED failure. Furthermore, existing electrode designs lack heat dissipation paths for these localized hot spots, making it difficult to guarantee long-term high luminous efficacy output from the LED.

[0009] Third, existing solutions attempt to use highly conductive alloy gold wires or complex multilayer electrode structures, which can improve high current carrying capacity and high temperature resistance. However, such solutions significantly increase the cost of electrode materials and the difficulty of manufacturing processes, which contradicts the cost control requirements for the large-scale application of plant supplementary lighting fixtures. If traditional low-cost gold wire electrodes are used, the high luminous efficiency requirements under high current and high temperature conditions cannot be met.

[0010] Therefore, under the operating conditions of 2000mA high current and above 85℃ for plant supplemental LED lamps, how to optimize the design of the gold wire electrodes on the chip surface to balance high current conduction, uniform current expansion, efficient heat dissipation, and high-temperature aging resistance, thereby maintaining stable high luminous efficacy while controlling chip manufacturing costs, has become a core technical challenge that this invention urgently needs to solve. To this end, this invention creatively proposes to add electrode pads around the chip and optimize the distribution of the electrode pads. At the same time, it improves the calculation formula for the spacing of the gold wire electrodes on the chip surface and further introduces an additional electrode pad factor, that is, the number of electrode pads, to optimize the spacing of the gold wire electrodes. This effectively solves the problem of LED chip electrode design under the operating conditions of 2000mA high current and above 85℃, significantly improves the luminous efficacy of LED chip electrodes, and effectively accelerates the research and development and industrialization process of high-performance plant supplemental LED lamps.

[0011] In one possible embodiment of the present invention, the number of electrode pads is 4 or 6. Traditional chip electrodes typically use single or dual electrode pads. The present invention increases the number of electrode pads to 4 or 6. However, simply increasing the number of electrode pads also increases the chip's occlusion area. Therefore, the spacing of the finger gold wires is further optimized. Using the modified formula of the present invention, Ls=n*sqrt(Rc / Rs), the spacing of the finger gold wires is recalculated, successfully reducing the occlusion area of ​​the finger gold wire electrodes to below 50%. Calculations show that, compared to traditional single or dual electrode pads, using the 4 or 6 electrode pads of the present invention can increase the chip's luminous flux by 4.3% or more.

[0012] In one possible implementation of the present invention, all electrode pads are axially symmetrically distributed along the periphery of the chip body. This distribution, combined with the bracket pads distributed on both sides, can minimize the resistance difference between the gold wires and the bracket vias.

[0013] As one possible implementation of the present invention, all electrode pads are symmetrically distributed around the periphery of the chip body. This distribution method brings the greatest advantage to the uniformity of current. Asymmetrical and non-uniform electrode pad distribution can also improve the light efficiency, but the improvement in light efficiency is not optimal.

[0014] It should be noted that the chip with symmetrical and equally spaced electrode pads has the highest improvement in luminous efficacy, which can theoretically reach 8.5%. In actual tests of various electrode pad distributions, the symmetrical and equally spaced distribution of electrode pads at the origin point has the highest improvement in luminous efficacy, specifically 7.5%; other distribution modes have achieved an improvement in luminous efficacy of 4% to 6%.

[0015] As one possible implementation of the present invention, the area of ​​the gold wire electrode shielding the chip body is less than 50% of the area of ​​the light-emitting area, which can effectively maximize the luminous efficiency of the lamp under extreme working conditions of 2000mA high current + 85℃ or higher temperature.

[0016] As a possible implementation of the present invention, by optimizing the distribution of electrode pads and the spacing of finger gold wire electrodes, it is possible to effectively ensure that the ratio of the maximum current to the minimum current on the finger gold wire electrodes is ≤1:1.15, thereby significantly improving the uniformity of current expansion of the chip electrodes, avoiding current concentration in the vicinity of the electrodes, and preventing the current distribution in the chip edge light-emitting area from being sparse, resulting in the phenomenon of "overcurrent at the origin and undercurrent at the edge", thus improving luminous efficiency. At the same time, it also avoids the problem of local chip heating caused by uneven current distribution.

[0017] LED beads are obtained by packaging the LED chip electrodes described above in this invention. For example, by using a 4-electrode pad chip to package the LED bead, the light radiant flux was successfully increased by 3.2% compared to a 2-electrode pad chip (the chip design is exactly the same except for the electrode pads). The ratio of the maximum to minimum current on the finger gold wire electrode was reduced from 1:1.4 to 1:1.15, thereby reducing the forward voltage of the LED bead by about 4.2%.

[0018] Under high current conditions of 2000mA and above, and high temperature conditions of 85℃ and above, the light radiation flux is increased by ≥3.2% compared with LED chips of the same specifications using dual electrode pads.

[0019] The chip adopts a multi-electrode pad solution, and the current is injected from four electrode pads instead of two. This can significantly reduce the local impact of high current on the chip. In the dual 85 reliability test with a high current of 2.4A, the failure time is ≥1800h, and the reliability test level of the LED bead has been improved from qualified to excellent.

[0020] Furthermore, it is worth noting that, using the 4-electrode pads of this invention, the connection reliability between the chip and the bracket is improved by 1 time compared to the 2-electrode pads when the same process is used to package the LED beads. Actual thermal shock test results also support the above conclusions, achieving the same excellent level, and the number of shock cycles for the 4-electrode pad chip-packaged LED beads is doubled.

[0021] The present invention also provides an LED lighting lamp, including the above-mentioned LED beads, lamp housing and driving circuit, wherein the driving circuit is used to provide the LED beads with an operating current of 2000mA or more.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The LED chip electrode designed in this invention effectively achieves the distributed injection of large current by setting four or more symmetrical and equally spaced electrode pads around the LED chip. Compared with the traditional single / double electrode pad solution, it significantly reduces the local impact of large current on the chip. At the same time, it can reduce the ratio of the maximum current to the minimum current on the finger gold wire electrode from 1:1.4 to 1:1.15, effectively improving the uniformity of current spread and avoiding performance degradation caused by local overcurrent of the chip.

[0023] 2. This invention creatively introduces an electrode pad factor n, i.e., the number of electrode pads, to correct and optimize the calculation formula for the spacing of the finger gold wire electrodes. This can reduce the shading area of ​​the finger gold wire electrodes to below 50%, which not only increases the luminous flux of the lamp beads by 4.3%, but also increases the light radiation flux by ≥3.2% compared to the traditional dual electrode pad scheme. In particular, when there are 4 electrode pads, symmetrically distributed at the origin and with equal spacing, the luminous efficacy can be improved by up to 7.5%, which significantly enhances the efficiency of plant supplemental lighting.

[0024] 3. By optimizing the electrode structure and current distribution, the forward voltage of LED chips using the electrode structure of this invention can be reduced by about 4.2% after being packaged into lamp beads. While ensuring high luminous efficiency output, energy loss is reduced, which meets the energy-saving requirements of large-scale plant supplemental lighting applications.

[0025] 4. The results of the double 85 test show that the failure time of the lamp beads using the electrode structure of the present invention is improved from 1300h to 1800h under a high current of 2.4A, and the reliability level is improved from qualified to excellent. At the same time, the number of impacts in the thermal shock test is doubled, and the connection reliability between the chip and the packaging bracket is improved by more than double, which effectively extends the service life of the lamp beads and subsequent lighting lamps and reduces the operation and maintenance costs.

[0026] 5. The LED chips packaged using the present invention can be directly applied to LED lighting for plant supplemental lighting under high current and high temperature conditions, meeting the supplemental lighting requirements of 2000mA and above working current and high temperature environment above 85℃, without the need for additional optimization of the lamp body structure, requiring minimal modification to existing lamp manufacturing production lines, and with relatively low manufacturing costs. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of an LED chip electrode according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the structure of an LED chip electrode according to Embodiment 2 of the present invention; Figure 3 This is a schematic diagram of the structure of an LED chip electrode according to Embodiment 3 of the present invention; Figure 4 This is a schematic diagram of the structure of an LED chip electrode according to Embodiment 4 of the present invention; The attached figures are labeled as follows: 1. Chip body; 2. Electrode pads; 3. Finger gold wire electrodes. Detailed Implementation

[0028] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0029] Example 1 like Figure 1As shown, in this embodiment, an LED chip electrode has a chip body 1 with a size of 70mil*70mil. It uses 4 electrode pads 2, which are symmetrically distributed on both sides of the chip body 1. Two electrode pads 2 are equally spaced on each side. All finger gold wire electrodes 3 are equally distributed. The calculated spacing of the finger gold wire electrodes 3 is 90um. During packaging, the bracket pads are distributed on both sides to minimize the resistance difference between the gold wire and the bracket via. This method is used to package the LED chip. A control group was set up. The difference between the control group and Example 1 is that the control group uses two electrode pads. Under the same packaging process, chip forward voltage, and chip luminous flux conditions, the number of times the chip was packaged with the LED chip in the control group with two electrode pads was compared. The luminous efficacy increased from 3.67umol / J@85℃@1800mA to 3.946umol / J@85℃@1800mA; the LED chip luminous efficacy improved by 7.5%, of which the decrease in the LED chip VF value contributed 4.6%, and the LED chip luminous flux increased by 2.9%.

[0030] Example 2 like Figure 2 As shown, in this embodiment, an LED chip electrode has a chip body 1 with a size of 70mil*70mil and uses 6 electrode pads 2. Among them, 4 electrode pads 2 are symmetrically distributed at the origin on both sides of the chip body 1, and 2 electrode pads 2 are located at the origin on the other two sides of the chip body 1. Finger gold wire electrodes 3 are connected between these two electrode pads 2. All finger gold wire electrodes 3 are equidistantly distributed. The calculated spacing of the finger gold wire electrodes 3 is 109um. During packaging, the bracket pads are distributed on all four sides. Compared with the control group in Example 1, under the same packaging process, chip forward voltage, and chip luminous flux, the luminous efficacy of the LED chip packaged with this scheme increased from 3.67 μmol / J@85℃@1800mA to 3.93 μmol / J@85℃@1800mA. The luminous efficacy of the LED chip increased by 7.1%, of which the decrease in the VF value of the LED chip contributed 4.5%, and the luminous flux of the LED chip increased by 2.6%.

[0031] Example 3 like Figure 3 As shown, in this embodiment, an LED chip electrode has a chip body 1 with a size of 70mil*70mil. It uses 4 electrode pads 2, which are symmetrically distributed at the origin on both sides of the chip body 1. Two electrode pads 2 are equally spaced on each side. All finger gold wire electrodes 3 are equally distributed. The calculated spacing of the finger gold wire electrodes 3 is 90um. During packaging, the bracket pads are distributed on both sides. Using this method to package the LED, compared with the control group in Example 1, under the same packaging process, chip forward voltage, and chip light radiant flux, the luminous efficacy increased from 3.66 μmol / J@85℃@1800mA to 3.872 μmol / J@85℃@1800mA; the LED luminous efficacy increased by 5.8%, of which the decrease in the LED VF value contributed 3.2%, and the LED light radiant flux increased by 2.6%.

[0032] Example 4 like Figure 4 As shown, in this embodiment, an LED chip electrode has a chip body 1 with dimensions of 65mil*75mil and employs six electrode pads 2. These six electrode pads 2 are symmetrically distributed around the origin on both sides of the chip body 1, with three equally spaced electrode pads on each side. All finger-shaped gold wire electrodes 3 are equally spaced, and the calculated spacing between the finger-shaped gold wire electrodes 3 is 109µm.

[0033] During packaging, the bracket pads are distributed on both sides. Compared with the control group in Example 1, under the same packaging process, chip forward voltage, and chip luminous flux, the luminous efficacy of the LED chip packaged with this scheme increased from 3.66 μmol / J@85℃@1800mA to 3.92 μmol / J@85℃@1800mA. The luminous efficacy of the LED chip increased by 7.1%, of which the decrease in the VF value of the LED chip contributed 4%, and the luminous flux of the LED chip increased by 3.1%.

[0034] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. An LED chip electrode, characterized in that, Includes a chip body (1), electrode pads (2) disposed around the chip body (1), and finger gold wire electrodes (3) disposed on the surface of the chip body (1); wherein: The electrode pads (2) are four or more, and are symmetrically and equally spaced along the periphery of the chip body (1); The finger gold wire electrodes (3) are evenly spaced, and the spacing between two adjacent finger gold wire electrodes (3) is determined according to the following formula: L s =n*sqrt( R c / R s ) Among them, L s The spacing of the gold wire electrodes (3) is n, where n is the number of electrode pads (2), and R is the distance between the electrodes. c R is the contact resistance between the gold wire electrode (3) of the finger and the chip body (1). s The sheet resistance of the chip body (1) is denoted as .

2. The LED chip electrode according to claim 1, characterized in that: The number of electrode pads (2) is 4 or 6.

3. An LED chip electrode according to claim 2, characterized in that: All electrode pads (2) are axially symmetrically distributed around the periphery of the chip body (1).

4. An LED chip electrode according to claim 2, characterized in that: All electrode pads (2) are symmetrically distributed around the chip body (1) at the origin.

5. An LED chip electrode according to any one of claims 1-4, characterized in that: The area blocked by the gold wire electrode (3) of the finger is less than 50% of the area of ​​the light-emitting area of ​​the chip body (1).

6. An LED chip electrode according to any one of claims 1-4, characterized in that: The ratio of the maximum current to the minimum current on the gold wire electrode (3) of the finger is ≤1:1.

15.

7. An LED chip electrode according to any one of claims 1-4, characterized in that: Under high current conditions of 2000mA and above, and high temperature conditions of 85℃ and above, the light radiation flux is increased by ≥3.2% compared with LED chips of the same specifications using dual electrode pads.

8. An LED chip electrode according to any one of claims 1-4, characterized in that: In the dual 85 reliability test with a high current of 2.4A, the failure time is ≥1800h.

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