Method for enhancing interconnection of flip packaging electronic device

Abstract

The invention discloses a method for enhancing interconnection of flip-chip packaging electronic devices, which comprises the following steps of: (a) adopting braided nickel as a support piece of the flip-chip packaging electronic devices, soaking the surface of the braided nickel in a solution of 5% sulfuric acid and 95% ethanol for 10 seconds, performing ultrasonic treatment on the surface of the braided nickel in an ethanol solution for 10 seconds, and drying the surface of the braided nickel; (b) immersing the woven nickel into the soldering flux; (c) immersing the woven nickel into the molten low-temperature metal, so that pores in the woven nickel are fully filled with the molten low-temperature metal; and (d) carrying out ultrasonic-assisted thermocompression bonding on the treated woven nickel to enhance the interconnectivity of the flip-chip packaging electronic device.

Description

Technical Field

[0001] The invention relates to the field of flip-chip packaged electronic devices, and in particular to a method for enhancing interconnection of flip-chip packaged electronic devices. Background Art

[0002] Flip chip electronic devices are pinless electronic devices. The chip is directly flipped and mounted on the substrate, and low-temperature metal materials are used to achieve interconnection. Commonly used flip chip electronic devices, such as flip chip ball grid array packaging devices (FCBGA), first used C4 controlled collapse chip connection (Controlled Collapse Chip Connection) technology to achieve interconnection. Further development uses the surface tension of molten bumps to support the weight of the chip and control the height of the bumps to achieve flip chip interconnection. The I / O density is significantly improved, arranged in an array on the chip surface, and the area is reduced by 30%-60% compared to traditional packaging. The number of I / Os has increased to hundreds and thousands, and the performance of a single I / O interconnection bump also directly affects the service life of FCBGA. Summary of the invention

[0003] The invention aims to solve the problem in the prior art that the performance of a single I / O interconnection bump is not high and the interconnection of a flip chip is not strong due to the high I / O density.

[0004] The present invention adopts the following technical solution: a method for enhancing interconnection of flip-chip packaged electronic devices, comprising the following steps:

[0005] (a) Using braided nickel as a support for flip-chip packaged electronic devices, the surface of the braided nickel was first immersed in a solution of 5% sulfuric acid + 95% ethanol for 10 seconds, then ultrasonicated in the ethanol solution for 10 seconds and then dried;

[0006] (b) Immerse the braided nickel in flux for 10 seconds;

[0007] (c) immersing the braided nickel into molten low-temperature metal so that the molten low-temperature metal fully fills the pores in the braided nickel;

[0008] (d) Ultrasonic assisted thermocompression bonding is used on the treated braided nickel to enhance the interconnectivity of flip-chip packaged electronic devices.

[0009] Preferably, the soldering flux in step (b) is a plurality of rosin resin, stannous sulfonate, diethanolamine, succinic acid, polyethylene glycol, and mixed alcohols.

[0010] Preferably, the low-temperature metal in step (c) is Sn-58Bi.

[0011] Preferably, the thickness of the braided nickel is 0.03-0.05 mm.

[0012] Preferably, in the step (c), the braided nickel is immersed in molten Sn-58Bi at 200° C.-210° C. for 15 seconds, so that the molten Sn-58Bi fully fills the pores in the braided nickel.

[0013] Preferably, in step (d), the pressure is set to 0.02MPa-0.05MPa, the temperature is set to 200℃-210℃, the frequency is set to 1kHz-1.2kHz, and the power is set to 200W-250W to perform ultrasonic assisted hot pressing bonding for 5-15s to enhance the interconnectivity of flip-chip packaged electronic devices.

[0014] The present invention has the following beneficial effects: the method described in the present invention can significantly improve the shear strength of the structure by 60.5%, meeting the requirements of high-quality interconnection of flip-chip packaged electronic devices reinforced with braided nickel. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 A schematic diagram of nickel braiding and nickel infiltration into ultrasonic assisted hot pressing bonding of the present invention;

[0017] Figure 2 The braided nickel bonding structure organization of the present invention is subjected to ultrasonic assisted hot pressing for different times;

[0018] Figure 3 This is a schematic diagram of the interface distribution of the EBSD (electron backscatter diffraction technology) of the braided nickel bonding structure of the present invention;

[0019] Figure 4 This is a schematic diagram of the shear strength of the braided nickel bonding structure of the present invention;

[0020] Figure 5 Schematic diagram of different lattice structures of (Ni,Cu)6Sn5. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0022] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0023] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0024] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0026] Example

[0027] The following are only preferred implementations of the present invention. The protection scope of the present invention is not limited to the following embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention.

[0028] Reference Manual Attached Figure 1 A method for enhancing interconnection of flip-chip packaged electronic devices comprises the following steps: (a) using a braided nickel with a thickness of 0.03-0.05 mm as a support for the flip-chip packaged electronic device, immersing the surface of the braided nickel in a solution of 5% sulfuric acid + 95% ethanol for 10 seconds, and then drying it after ultrasonic treatment of the ethanol solution for 10 seconds; (b) immersing the braided nickel in a soldering flux, wherein the soldering flux is a rosin resin; (c) immersing the braided nickel in molten Sn-58Bi at 200°C-210°C for 15 seconds, so that the molten Sn-58Bi fully fills the pores in the braided nickel; (d) performing ultrasonic assisted hot pressing bonding on the treated braided nickel at a pressure of 0.02MPa-0.05MPa, a temperature of 200°C-210°C, a frequency of 1kHz-1.2kHz, and a power of 200W-250W for 5-15 seconds to enhance the interconnection of the flip-chip packaged electronic device.

[0029] Specific reference is made to the following embodiments:

[0030] Example 1: Select 0.03-0.05mm thick braided nickel, soak it in 5% sulfuric acid + 95% ethanol for 10s, ultrasonically treat ethanol for 10s, and dry it. First, soak the braided nickel in the brazing agent for 10s, then select Sn-58Bi low-temperature metal material and set the temperature to 200°C in a molten state, soak the braided nickel for 15s and take it out for use, set the parameters to 0.02MPa, 200°C, 1kHz frequency and 200W power ultrasonic assisted hot pressing bonding to heat press bond the braided nickel for 5s, and enhance the interconnectivity of flip-chip packaged electronic devices using the braided nickel.

[0031] Example 2: Select 0.03-0.05mm thick braided nickel, soak it in 5% sulfuric acid + 95% ethanol for 10s, ultrasonically treat ethanol for 10s, and dry it. First, soak the braided nickel in the brazing agent for 10s, then select Sn-58Bi low-temperature metal material and set the temperature to 200°C in a molten state, soak the braided nickel for 15s and take it out for use, set the parameters to 0.02MPa, 200°C, 1kHz and 200W of ultrasonic assisted hot pressing bonding to heat press bond the braided nickel for 15s, and enhance the interconnectivity of flip-chip packaged electronic devices using the braided nickel.

[0032] Example 3: Select 0.03-0.05mm thick braided nickel, soak it in 5% sulfuric acid + 95% ethanol for 10s, ultrasonically treat ethanol for 10s, and dry it. First, soak the braided nickel in the brazing agent for 10s, then select Sn-58Bi low-temperature metal material and set the temperature to 200°C in a molten state, soak the braided nickel for 15s and take it out for use, set the parameters to 0.02MPa, 200°C, 1kHz frequency and 200W power ultrasonic assisted hot pressing bonding to heat press bond the braided nickel for 30s, and enhance the interconnectivity of flip-chip packaged electronic devices using the braided nickel.

[0033] Reference Manual Attached Figure 2 , are the braided nickel bonding structures of different ultrasonic assisted hot pressing times in Examples 1-3; it can be found that the structures are not much different in the ultrasonic assisted hot pressing bonding time period of 5s-30s. Figure 3 , Schematic diagram of the interface distribution of the woven nickel bonding structure EBSD (electron backscatter diffraction technology) of the present invention, with the addition of ultrasound compared to without the addition of ultrasound, the woven nickel interface structure changes from a discontinuous structure to a continuous structure, in the matrix near the nickel mesh, β-Sn and Bi grains show a preferred orientation, <001> direction parallel to the bonding direction.

[0034] Example 4: Select 0.03-0.05mm thick braided nickel, soak it in 5% sulfuric acid + 95% ethanol for 10s, ultrasonically treat ethanol for 10s, and dry it. First, soak the braided nickel in the brazing agent for 10s, then select Sn-58Bi low-temperature metal material and set the temperature to 210°C in a molten state, soak the braided nickel for 15s and take it out for use, set the parameters to 0.02MPa, 200°C, 1kHz and 200W of ultrasonic assisted hot pressing bonding to heat press bond the braided nickel for 5s, and enhance the interconnectivity of flip-chip packaged electronic devices using the braided nickel.

[0035] Example 5: Select 0.03-0.05mm thick braided nickel, soak it in 5% sulfuric acid + 95% ethanol for 10s, ultrasonically treat ethanol for 10s, and dry it. First, soak the braided nickel in the brazing agent for 10s, then select Sn-58Bi low-temperature metal material and set the temperature to 200°C in a molten state, soak the braided nickel for 15s and take it out for use, set the parameters to 0.05MPa, 200°C, 1kHz and 200W of ultrasonic assisted hot pressing bonding to heat press bond the braided nickel for 5s, and enhance the interconnectivity of flip-chip packaged electronic devices using the braided nickel.

[0036] Example 6: Select 0.03-0.05mm thick braided nickel, soak it in 5% sulfuric acid + 95% ethanol for 10s, ultrasonically treat ethanol for 10s, and dry it. First, soak the braided nickel in the brazing agent for 10s, then select Sn-58Bi low-temperature metal material and set the temperature to 200°C in a molten state, soak the braided nickel for 15s and take it out for use, set the parameters to 0.05MPa, 200°C, 1.2kHz, and 200W of ultrasonic assisted hot pressing bonding to heat press bond the braided nickel for 5s, and enhance the interconnectivity of flip-chip packaged electronic devices using the braided nickel.

[0037] Example 7: Select 0.03-0.05mm thick braided nickel, soak it in 5% sulfuric acid + 95% ethanol for 10s, ultrasonically treat ethanol for 10s, and dry it. First, soak the braided nickel in the brazing agent for 10s, then select Sn-58Bi low-temperature metal material and set the temperature to 200°C in a molten state, soak the braided nickel for 15s and take it out for use, set the parameters to 0.05MPa, 200°C, 1.2kHz, and 250W of ultrasonic assisted hot pressing bonding to heat press bond the braided nickel for 5s, and enhance the interconnectivity of flip-chip packaged electronic devices using the braided nickel.

[0038] Reference Manual Attached Figure 4 , is a schematic diagram of the shear strength of the braided nickel bonding structure of the present invention. The shear strength is greater than 50MPa within 30s of ultrasound. The shear strength of braided nickel in the range of 200-250W ultrasonic power is much greater than the shear strength of the chip without braided nickel as a support.

[0039] The present invention achieves high-quality interconnection enhancement of flip-chip packaged electronic devices by braiding nickel through matching appropriate braided nickel and ultrasonic-assisted hot pressing bonding. For the interconnection of flip-chip packaged electronic devices, such as Cu / Sn-Bi / Cu bumps, hard and brittle intermetallic compounds are formed in the interface area of ​​the chip metal layer during the reflow soldering process, and obvious voids will appear in the interface area. In addition, due to the mismatch in linear expansion coefficients between low-melting-point metals, intermetallic compounds, metal layers, chips and substrates, the interconnection area becomes a stress concentration area, which is difficult to withstand the gradually accumulated residual stress, exhibits lower strength, and leads to early failure. The braided nickel has two functions: (1) The braided nickel is immersed in the molten low-temperature metal material to form a bump with a Ni skeleton. During the ultrasonic-assisted hot pressing bonding process of the flip chip, the braided nickel does not melt and can directly support the chip; (2) Refer to the attached manual Figure 5 The presence of the braided nickel (skeleton) induces the diffusion of Ni elements and the reaction with the Sn elements in the matrix and the Cu elements in the metal plating to form a (Ni,Cu)6Sn5 phase in the structure, which strengthens the bonding and interconnection between the braided nickel skeleton and the matrix, greatly improves the interconnection strength of the flip-chip electronic devices, and ensures the service life during service.

[0040] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for enhancing interconnection of flip-chip packaged electronic devices, characterized in that: The steps include: (a) Using braided nickel as a support for flip-chip packaged electronic devices, the surface of the braided nickel was first immersed in a solution of 5% sulfuric acid + 95% ethanol for 10 seconds, then ultrasonicated in the ethanol solution for 10 seconds and then dried; (b) Immerse the braided nickel in flux for 10 seconds; (c) immersing the braided nickel into molten low-temperature metal so that the molten low-temperature metal fully fills the pores in the braided nickel; (d) Ultrasonic assisted thermocompression bonding is used on the treated braided nickel to enhance the interconnectivity of flip-chip packaged electronic devices.

2. The method for enhancing interconnection of flip-chip packaged electronic devices according to claim 1, characterized in that: The soldering flux in step (b) is a plurality of rosin resin, stannous sulfonate, diethanolamine, succinic acid, polyethylene glycol, and mixed alcohols.

3. The method for enhancing interconnection of flip-chip packaged electronic devices according to claim 1, characterized in that: The low temperature metal in step (c) is Sn-58Bi.

4. The method for enhancing interconnection of flip-chip packaged electronic devices according to claim 1, characterized in that: The thickness of the braided nickel is 0.03-0.05 mm.

5. The method for enhancing interconnection of flip-chip packaged electronic devices according to claim 3, characterized in that: In the step (c), the braided nickel is immersed in molten Sn-58Bi at 200° C.-210° C. for 15 seconds, so that the molten Sn-58Bi fully fills the pores in the braided nickel.

6. The method for enhancing interconnection of flip-chip packaged electronic devices according to claim 1, characterized in that: In the step (d), the pressure is set to 0.02MPa-0.05MPa, the temperature is set to 200°C-210°C, the frequency is set to 1kHz-1.2kHz, and the power is set to 200W-250W to perform ultrasonic assisted hot pressing bonding for 5-15s to enhance the interconnectivity of flip-chip packaged electronic devices.

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