Flip LED chip packaging method

Abstract

The invention provides a flip LED chip packaging method, and the method comprises the steps: S1, dispensing high-temperature solder paste into a packaging support through a dipping point, so as to form a tin point; s2, dipping and dispensing target adhesive glue in the middle of the tin point; s3, the flip LED chip is correspondingly fixed at the tin points, the flip LED chip and the packaging support are welded through high-temperature solder paste and target adhesive glue, and the adhesive glue is solidified; s4, the bottom of the LED support is filled with white glue to form an arc-shaped light guide structure; s5, a cavity defined by the arc-shaped light guide structure and the LED support is filled with fluorescent glue, and a flip LED chip packaging finished product is obtained.The flip LED chip packaging method can solve the problem of secondary backflow in the chip mounting process of a flip product, and can improve the brightness of emergent light.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of semiconductor packaging, and particularly relates to a flip LED chip packaging method. BACKGROUND

[0002] With the maturity of technology, LED (light emitting diode) is widely used in lighting, backlight and other fields due to its unique photoelectric characteristics and super long service life. The core parameter of LED is reliability. The components of the packaged product of the vertical LED include a support, a chip, glue, phosphor and the like, and the product process is completed through die bonding, wire bonding, dispensing and testing. The vertical chip product needs to be electrically interconnected through wire bonding, but the wire is disconnected due to the temperature difference in the use process. Therefore, the flip product becomes a research hotspot. However, the flip product needs to be welded on the PCB of the lamp through high-temperature reflow soldering in the process of loading into the lamp, and the temperature of the secondary reflow greatly affects the welding of the solder paste at the bottom of the flip chip in the packaged LED. In a serious case, the open circuit dead lamp problem occurs, which affects the light brightness of the packaged product. SUMMARY

[0003] In order to solve the above technical problems, the present application provides a flip LED chip packaging method to solve the problems in the background art.

[0004] The embodiment of the present application provides the following technical scheme, a flip LED chip packaging method, comprising: S1, providing a packaging support, dipping high-temperature solder paste into the packaging support to form a plurality of solder points with equal intervals on the packaging support; S2, dipping target adhesive in the middle of the solder points; S3, providing a flip LED chip with a flattened tin at the bottom corresponding to the solder points, fixing the flip LED chip corresponding to the solder points, welding the flip LED chip and the packaging support through the high-temperature solder paste and the target adhesive, and curing the adhesive; S4, filling white glue at the bottom of the LED support to form an arc-shaped light guide structure concave in the middle around the flip LED chip; S5, filling fluorescent glue in the cavity surrounded by the arc-shaped light guide structure and the LED support to obtain a flip LED chip packaging finished product.

[0005] Compared with the prior art, the application has the beneficial effects that the target adhesive provided by the application has an expansion coefficient of 76.47 um / (m-C) and a viscosity of 8000 mPa's, and the target adhesive is filled in the bottom of the flip chip LED, so that the flip chip LED is pulled by the target adhesive due to the small expansion coefficient and the high viscosity, and the flip chip LED is prevented from being affected by the high-temperature expansion of reflow soldering to form a cavity or even an open circuit during the reflow process, and the white glue with affinity to the target adhesive is selected to form intermolecular forces and improve the anti-peeling capacity, and the white glue with thixotropy forms a middle concave arc light guide structure at the edge of the bracket to guide light and improve the brightness of the flip chip product.

[0006] Preferably, in step S1, the high-temperature tin paste is specifically high-temperature tin paste SC07, and in the high-temperature tin paste SC07, the proportion of the flux is 18%-22%, and the rest is a tin-copper alloy.

[0007] Preferably, in step S1, in the tin-copper alloy of the high-temperature tin paste, the proportion of the Sn component is 99.3%, and the proportion of Cu is 0.7%.

[0008] Preferably, the size of the solder joint is 280 um±30 um, and the height of the solder joint is 40 um-60 um.

[0009] Preferably, the preparation process of the target adhesive is as follows: The first monomer [CH2=CH(CH3)2SiO], the second monomer [(CH3)Si(OH)] n , the third monomer H-Si(CH3)2CH=CH2 and water are mixed and reacted to obtain the target product [CH2=CH(CH3)2SiO][(CH3)2SiO] n Si(CH3)2CH=CH2: [CH2=CH(CH3)2SiO]-CH3+H2O+[(CH3)Si(OH)] n +H-Si(CH3)2CH=CH2→[CH2=CH(CH3)2SiO][(CH3)2SiO] n Si(CH3)2CH=CH2+CH3OH; The reaction condition is 80℃ / 5h. The target product is purified and mixed with an adhesion promoter to obtain the target adhesive.

[0010] Preferably, the height of the target adhesive point after being arranged in the middle of the tin point is 30 um-40 um.

[0011] Preferably, the target adhesive has an expansion coefficient of 76.47um / (m-C) and a viscosity of 8000mPa's.

[0012] Preferably, the soldering and adhering of the flip LED chip to the packaging support by the high-temperature tin paste and the target adhesive is performed as follows: Reflowing the tin points and the flip LED chip with the ground tin to fuse the tin points and the ground tin and form effective soldering, and then baking the target adhesive at 80℃ / 1h+170℃ / 2h.

[0013] Preferably, the concave height of the concave in the middle of the arc-shaped light guide structure is 40um-80um.

[0014] Preferably, the white glue is a white glue having affinity with the target adhesive. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0016] Figure 1 The flow chart of the flip LED chip packaging method provided by the first embodiment of the present application is shown in the figure. Figure 2 The structure diagram of the flip LED chip packaging finished product prepared by the flip LED chip packaging method provided by the first embodiment of the present application is shown in the figure.

[0017] Explanation of reference signs:

[0018] The embodiments of the present application will be further described below in combination with the drawings. DETAILED DESCRIPTION

[0019] The embodiments of the present application will be described in detail below, and the examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the embodiments of the present application, and cannot be understood as a limitation of the present application.

[0020] In the description of the embodiments of the present invention, it should be understood that the terms "length", "width", "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 the embodiments of the present 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 the present invention.

[0021] 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 embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0022] In the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "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 the embodiments of the present invention according to the specific circumstances.

[0023] Example 1 like Figure 1 As shown, the first embodiment of the present invention provides a flip-chip LED chip packaging method, the method comprising: S1. Provide a packaging bracket 1, and apply high-temperature solder paste 3 into the packaging bracket 1 by dipping to form a plurality of equally spaced solder dots on the packaging bracket 1. Specifically, in this application, four solder points are provided, which are distributed in a rectangular shape at equal intervals. High-temperature solder paste 3 is applied to the packaging bracket 1 by dipping, and the solder points here correspond one-to-one with the polished solder on the bottom of the flip-chip LED chip 4.

[0024] Specifically, high-temperature solder paste 3 is high-temperature solder paste 3SC07. In high-temperature solder paste 3SC07, the flux accounts for 18%-22%, and the remainder is tin-copper alloy. The flux here includes film-forming agents, activators, solvents, additives, etc. The film-forming agent can be rosin derivatives or synthetic resins, the activator can be organic acids, halides, or amine compounds, the solvent can be a high-boiling-point solvent such as diethylene glycol butyl ether, and the additive can be benzotriazole or hydrogenated castor oil.

[0025] In the tin copper alloy of the high-temperature tin paste 3, the proportion of Sn component is 99.3%, and the proportion of Cu is 0.7%.

[0026] The size diameter of the solder joint is 280um±30um, and the height of the solder joint is 40um-60um.

[0027] S2, dip the target adhesive 2 in the middle of the tin point; Specifically, the preparation process of the target adhesive 2 is: The first monomer [CH2=CH(CH3)2SiO], the second monomer [(CH3)Si(OH)] n , the third monomer H-Si(CH3)2CH=CH2 and water are mixed and reacted to obtain the target product [CH2=CH(CH3)2SiO][(CH3)2SiO] n Si(CH3)2CH=CH2: [CH2=CH(CH3)2SiO]-CH3+H2O+[(CH3)Si(OH)] n +H-Si(CH3)2CH=CH2→[CH2=CH(CH3)2SiO][(CH3)2SiO] n Si(CH3)2CH=CH2+CH3OH; The reaction condition is 80℃ / 5h; The target product is purified and mixed with an adhesion promoter to obtain the target adhesive 2; Specifically, by adhering the target adhesive between the four tin points, the adhesion ability is improved, and secondary reflow is avoided.

[0028] The height of the target adhesive 2 after being dotted in the middle of the tin point is 30um-40um.

[0029] The expansion coefficient of the target adhesive 2 is 76.47um / (m-C), and the viscosity is 8000mPa's.

[0030] S3, provide a flip LED chip 4 with a flat tin corresponding to the tin point on the bottom, fix the flip LED chip 4 corresponding to the tin point, and weld the flip LED chip 4 and the packaging support 1 through the high-temperature tin paste 3 and the target adhesive 2 and solidify the adhesive. The flip LED chip 4 is fixed on four tin points in a 4-point-to-point manner, is bonded through high-temperature tin paste 3, then is reflowed, effective welding is formed by tin paste fusion, and the cavity rate is less than 10%; then the target adhesive 2 is baked and solidified at 80 DEG C / 1h+170 DEG C / 2h, the bottom of the flip LED chip 4 is pre-installed with the flat tin, and the IMC interface of the chip welding layer has been formed; the stability of the tin point on the bracket is poor, the size of the tin point is 280+30um in diameter, the pre-installed flat tin can keep the uniformity of the welding layer tin amount, and the effectiveness of welding is improved.

[0031] S4, the white glue 5 is filled in the bottom of the LED bracket to form the intermediate concave arc-shaped light guide structure around the flip LED chip 4; Specifically, the white glue 5 herein has affinity with the target adhesive 2 to form intermolecular forces and improve the anti-peeling capacity, and the white glue 5 with thixotropy forms the intermediate concave arc-shaped light guide structure at the edge of the bracket to guide light and improve the brightness of the flip product.

[0032] The concave height of the intermediate concave arc-shaped light guide structure is 40um-80um.

[0033] S5, the fluorescent glue 6 is filled in the cavity surrounded by the arc-shaped light guide structure and the LED bracket to obtain a flip LED chip packaging finished product.

[0034] Specifically, after the fluorescent glue 6 is filled, the flip LED chip packaging finished product can be obtained, so that the problem of secondary reflow in the patching process of the flip product can be solved, and the brightness is improved by 2%-4%.

[0035] Meanwhile, the flip LED chip packaging finished product obtained through the above steps has a structure as shown in Figure 2 which can effectively improve the light brightness.

[0036] In summary, the target adhesive 2 provided by the application has an expansion coefficient of 76.47um / (m-C) and a viscosity of 8000mPa's, and the target adhesive 2 is filled in the bottom of the flip LED chip 4; due to the small expansion coefficient and the high viscosity, the flip LED chip 4 is pulled, the flip LED chip 4 is prevented from being affected by the high-temperature expansion in the reflow soldering process to form a cavity or even an open circuit, the white glue 5 with affinity with the target adhesive 2 is selected to form intermolecular forces and improve the anti-peeling capacity, and the white glue 5 with thixotropy forms the intermediate concave arc-shaped light guide structure at the edge of the bracket to guide light and improve the brightness of the flip product.

[0037] The above merely describes preferred embodiments of the present application, and is not used to limit the present application, any modification, equivalent replacement and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A flip LED chip packaging method, characterized in that, The method includes: S1. A packaging bracket is provided, and high-temperature solder paste is applied into the packaging bracket by dipping to form a plurality of equally spaced solder dots on the packaging bracket. S2. Apply the target adhesive to the center of the solder spot; S3. Provide a flip-chip with a flattened solder pad on the bottom corresponding to the solder point, fix the flip-chip at the solder point, and weld the flip-chip to the package bracket and cure the adhesive using the high-temperature solder paste and the target adhesive. S4. Fill the bottom of the LED bracket with white glue to form a concave arc-shaped light guide structure around the flip LED chip; S5. Fill the cavity formed by the arc-shaped light guide structure and the LED bracket with fluorescent adhesive to obtain the flip-chip packaged product.

2. The flip LED chip packaging method of claim 1, wherein, In step S1, the high-temperature solder paste is specifically high-temperature solder paste SC07. In high-temperature solder paste SC07, the flux accounts for 18%-22%, and the remainder is tin-copper alloy.

3. The flip LED chip packaging method of claim 2, wherein, In step S1, in the tin-copper alloy of the high-temperature solder paste, the Sn component accounts for 99.3% and the Cu component accounts for 0.7%.

4. The flip LED chip packaging method of claim 1, wherein, The diameter of the solder joint is 280um ± 30um, and the height of the solder joint is 40um-60um.

5. The flip-chip LED packaging method of claim 1, wherein, The preparation process of the target adhesive is as follows: a first monomer [CH2=CH(CH3)2SiO], a second monomer [(CH3)Si(OH)] n , a third monomer H-Si(CH3)2CH=CH2, and water are mixed and reacted to obtain a target product [CH2=CH(CH3)2SiO][(CH3)2SiO] n Si(CH3)2CH=CH2: [CH2=CH(CH3)2SiO]-CH3+ H2O + [(CH3)Si(OH)] n + H-Si(CH3)2CH=CH2→ [CH2=CH(CH3)2SiO][(CH3)2SiO] n Si(CH3)2CH=CH2+ CH3OH; The reaction conditions were 80℃ / 5h; The target product is purified and mixed with a tackifier to obtain the target adhesive.

6. The flip-chip LED packaging method of claim 1, wherein, The height of the target adhesive in the middle of the solder point is 30um-40um.

7. The flip-chip LED packaging method of claim 1, wherein, The target adhesive has a coefficient of thermal expansion of 76.47 μm / (mC) and a viscosity of 8000 mPa's.

8. The flip-chip LED packaging method of claim 1, wherein, The steps of soldering the flip-chip LED chip to the package bracket using the high-temperature solder paste and the target adhesive, and then curing the adhesive, are as follows: The solder joint and the flip-chip with the bottom having smoothed solder are reflowed to fuse the solder joint and the smoothed solder to form an effective solder joint. Then, the target adhesive is baked at 80℃ / 1h + 170℃ / 2h to cure.

9. The flip-chip LED packaging method of claim 1, wherein, The recessed height of the middle part of the arc-shaped light guide structure is 40um-80um.

10. The flip-chip LED packaging method of claim 1, wherein, The white glue is a white glue that has an affinity for the target adhesive.

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