High-thermal-conductivity and high-electrical-conductivity interconnection structure and preparation method thereof

Abstract

The invention relates to the technical field of electronic packaging interconnection, in particular to a high-thermal-conductivity and high-electrical-conductivity interconnection structure and a preparation method thereof, and the specific method comprises the steps: soaking a chip with copper bumps and a bonding pad with copper bumps in a steric hindrance agent-silver salt composite solution, taking out and drying, and sequentially carrying out inverted hot-pressing bonding and coating filling, so as to obtain the high-thermal-conductivity and high-electrical-conductivity interconnection structure. And curing to obtain the high-thermal-conductivity and high-electrical-conductivity interconnection structure. Or filling a coating on the surface of the bonding pad with the copper salient points to obtain the bonding pad with the filling coating on the surface of the non-copper salient points; and soaking the bonding pad with the filling coating reserved on the non-copper bump surface and the chip with the copper bump in a steric hindrance agent-silver salt composite solution, taking out and drying, and then carrying out flip thermocompression bonding to obtain the high-thermal-conductivity and high-conductivity interconnection structure. According to the high-thermal-conductivity and high-conductivity interconnection structure and the preparation method thereof, on the premise that the mechanical stability of the interconnection structure is improved, the electrical conductivity and the thermal conductivity are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic packaging interconnection, and in particular to a high thermal conductivity and high electrical conductivity interconnection structure and a preparation method thereof. Background Art

[0002] With continuous breakthroughs in cutting-edge fields such as 5G / 6G communications, artificial intelligence, and high-performance computing, the performance requirements for integrated circuit packaging are becoming increasingly stringent. To meet the demands of these fields for high-bandwidth data transmission, low-latency response, and large-scale data processing capabilities, integrated circuit packaging technology continues to accelerate towards high density, high performance, and high reliability. In integrated circuit packaging technology, the interconnection between the chip and the pad is a critical link, directly affecting the device's electrical performance, heat dissipation, and mechanical stability.

[0003] Traditional wire bonding technology is limited by parasitic effects and packaging density, making it difficult to meet the interconnection requirements of high bandwidth and low latency. However, flip-chip interconnection technology has emerged as the mainstream solution for modern advanced packaging due to its high-density interconnection, excellent electrothermal performance, and shorter signal transmission path. The core of flip-chip packaging technology is to first precisely make bumps on the chip and pads, then flip the chip with bumps on the pads with bumps upside down, and use the bumps on the pads and chip for alignment and bonding, thereby achieving electrical and mechanical connection between the chip and pads. The above connection method not only greatly improves the interconnection density and reduces the signal transmission path, but also significantly improves the electrothermal performance, providing a strong guarantee for the high-performance operation of the chip.

[0004] Traditional solder bumps have been widely used in flip-chip packaging. However, as chip feature sizes enter the sub-micron era, the limitations of solder bumps have gradually become apparent. Specifically, they are: (1) limited thermal conductivity. The thermal conductivity of solder is only about 50W / m·K. In high-power, high-heat-dissipation scenarios such as 5G / 6G RF devices, it is difficult to meet the heat dissipation requirements, which can easily lead to excessive chip temperatures, thus affecting its performance and lifespan; (2) there is a bottleneck in mechanical strength. The shear strength of solder bumps is generally less than 50MPa. In applications with high mechanical strength requirements such as 3D stacked packaging structures, they cannot provide sufficient support, which can easily lead to deformation and cracking of the packaging structure, reducing the reliability of the package.

[0005] Since copper bumps have a high conductivity (about 5.8×10 7S / m) and thermal conductivity (about 400W / (m·K)), and its mechanical strength is significantly better than that of traditional solder. In order to overcome the problems of traditional solder bumps, copper bump bonding technology has gradually become a research hotspot. There are two main bonding methods between copper bumps: (1) hot pressing bonding, which relies on the diffusion of copper atoms to achieve solid-phase connection, but has extremely high requirements for the cleanliness and flatness of the copper bump surface. If there are impurities, oxides or unevenness on the surface of the copper bump, it will hinder the diffusion of copper atoms, resulting in voids, weak bonding or local unbonded areas at the bonding interface, seriously affecting the electrical conductivity, thermal conductivity and mechanical stability of the interconnection structure (bonding of a pad with a copper bump to a chip with a copper bump); (2) solder bonding, which is achieved by melting tin-based solder (such as Sn-Ag, Sn-Cu) and reacting with the copper bump to form intermetallic compounds (such as Cu6Sn5 and Cu3Sn). However, this bonding method has strict requirements on the metal tin composition. If the tin content is too low, a sufficient metal interlayer cannot be formed, resulting in insufficient bonding strength at the bonding interface, making it impossible to achieve a high-strength mechanical and electrical connection, and affecting electrical conductivity, thermal conductivity, and mechanical stability. If the tin content is too high, a brittle intermetallic compound, Cu3Sn, is easily formed. This brittle compound is easily broken when subjected to external force or thermal stress, resulting in uneven distribution of solder at the bonding interface, forming voids or cracks, which also affects the electrical conductivity, thermal conductivity, and mechanical stability of the interconnect structure.

[0006] In summary, the interconnect structures in the prior art generally face problems such as insufficient electrical conductivity, thermal conductivity and mechanical stability. Summary of the Invention

[0007] The purpose of the present invention is to provide a high thermal conductivity and high electrical conductivity interconnect structure and a preparation method thereof, so as to achieve an improvement in electrical conductivity and thermal conductivity while improving the mechanical stability of the interconnect structure, so as to overcome the shortcomings of the prior art.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] A method for preparing a high thermal conductivity and high electrical conductivity interconnect structure comprises the following steps:

[0010] A. mixing the steric hindering agent solution and the silver salt solution to obtain a steric hindering agent-silver salt composite solution;

[0011] B. Immersing a chip having copper bumps and a pad having copper bumps in a steric hinderant-silver salt composite solution, removing and drying to obtain a first intermediate pad and a first intermediate chip, respectively, wherein the outer layers of the copper bumps of the first intermediate pad and the first intermediate chip are both deposited with a thorn-shaped silver plating layer; performing flip-chip thermocompression bonding on the first intermediate pad and the first intermediate chip to obtain a primary bonding component; filling a coating between the chip and the pad of the primary bonding component, which, after curing, forms a filling coating and obtains a high thermal conductivity and high electrical conductivity interconnect structure;

[0012] Alternatively, a coating is applied to the surface of a solder pad having a copper bump, and after curing, a solder pad having a filling coating is obtained; the filling coating on the surface of the copper bump in the solder pad is removed to obtain a solder pad with the filling coating retained on the surface of the non-copper bump; the solder pad with the filling coating retained on the surface of the non-copper bump and the chip having the copper bump are immersed in a steric inhibitor-silver salt composite solution, taken out and dried to obtain a second intermediate solder pad and a second intermediate chip, respectively, wherein the outer layers of the copper bumps of the second intermediate solder pad and the second intermediate chip are both deposited with a thorn-shaped silver plating layer; the second intermediate solder pad and the second intermediate chip are flip-chip hot-pressed to obtain a high thermal conductivity and high electrical conductivity interconnection structure;

[0013] The thickness of the filling coating is the sum of the height of the copper bump of the pad, the thickness of the thorn-shaped silver plating layer of the pad, the height of the copper bump of the chip and the thickness of the thorn-shaped silver plating layer of the chip;

[0014] The raw materials of the coating include resin, curing agent and organic solvent.

[0015] Furthermore, in step A, the raw materials of the silver salt solution include silver salt and water, and the concentration of the silver salt in the silver salt solution is 0.1 to 20 mol / L.

[0016] Furthermore, in step A, the raw materials of the steric hindering agent solution include a steric hindering agent and water, and the concentration of the steric hindering agent in the steric hindering agent solution is 0.5 to 20 g / L.

[0017] Furthermore, in step A, the mixing ratio of the steric hinderant solution to the silver salt solution is 1:(8-10) calculated by mass ratio.

[0018] Furthermore, in step B, the mixing ratio of the resin, the curing agent and the organic solvent in the coating is (2-10):1:(15-20) calculated by mass ratio.

[0019] Furthermore, in step B, the flip-chip thermal compression bonding method is:

[0020] Fixing substrates on the bottom of the first middle pad and the first middle chip respectively to obtain a first substrate-pad assembly and a first substrate-chip assembly;

[0021] Substrate-chip assembly 1 is flipped upside down on substrate-pad assembly 1, and after the spike-shaped silver coating on substrate-chip assembly 1 is precisely aligned with the spike-shaped silver coating on substrate-pad assembly 1, pressure is applied to the bottom of substrate-chip assembly 1 to bond the spike-shaped silver coating on substrate-chip assembly 1 and substrate-pad assembly 1 at a bonding temperature until substrate-chip assembly 1 and substrate-pad assembly 1 are completely fixed.

[0022] Removing the substrates at the bottom of the substrate-chip assembly 1 and the substrate-pad assembly 1 to complete flip-chip thermocompression bonding;

[0023] Alternatively, substrates are fixed to the bottoms of the second intermediate pad and the second intermediate chip, respectively, to obtain a second substrate-pad assembly and a second substrate-chip assembly, respectively;

[0024] The second substrate-chip assembly is placed upside down on the second substrate-pad assembly, and the silver-plated spikes on the second substrate-chip assembly are precisely aligned with the silver-plated spikes on the second substrate-pad assembly. Pressure is then applied to the bottom of the second substrate-chip assembly to bond the silver-plated spikes on the second substrate-chip assembly to the silver-plated spikes on the second substrate-pad assembly at a bonding temperature until the second substrate-chip assembly is completely fixed to the second substrate-pad assembly.

[0025] The substrates at the bottom of the second substrate-chip assembly and the second substrate-pad assembly are removed to complete the flip-chip thermocompression bonding.

[0026] Furthermore, in step B, the bonding temperature of the flip-chip thermal compression bonding is 160-400° C., and the applied pressure is 0.5-50 MPa.

[0027] Furthermore, step C is further included between step A and step B, and step C is:

[0028] The pads with copper bumps and the chips with copper bumps are cleaned respectively.

[0029] Furthermore, the cleaning method is: using an acidic solution with a pH value of 5 to 6 and clean water in sequence to clean the pad with copper bumps and the chip with copper bumps respectively.

[0030] A high thermal conductivity and high electrical conductivity interconnection structure is prepared using the above-mentioned method for preparing a high thermal conductivity and high electrical conductivity interconnection structure.

[0031] The technical solution provided by the present invention can have the following beneficial effects:

[0032] 1. This technical solution, based on the properties of a steric hinderant-silver salt composite solution, utilizes a replacement reaction between the silver salt in the steric hinderant-silver salt composite solution and the copper atoms on the surface of the copper bumps on the pads, and between the silver salt in the steric hinderant-silver salt composite solution and the copper atoms on the surface of the copper bumps on the chip. This replaces the outer copper atoms of the copper bumps with silver atoms, in situ grows a thorn-like silver plating layer on the surface of the copper bumps, and forms a nanostructure with a high specific surface area. During the flip-chip hot-compression bonding process, even if the silver spikes with high specific surface area on the pads and the silver spikes with high specific surface area on the chip are not in full contact, the diffusion of silver atoms fills the gaps, achieving atomic-level mutual diffusion, promoting a metallurgical bond between the pads and the chip, and constructing a strong metal bond connection, thereby achieving a high-density and high-strength interconnect structure and effectively improving the mechanical stability of the interconnect structure.

[0033] 2. During the flip-chip hot-press bonding process, the thorn-shaped silver plating layers generated by the replacement reaction penetrate each other to form multiple conductive paths, reducing the contact resistance and thereby improving the conductivity of the interconnection structure. At the same time, the surface energy of the nanosilver particles in the thorn-shaped silver plating layer is high, and surface diffusion sintering will occur during the flip-chip hot-press bonding process, which increases the grain boundary density at the interface connection and the electron mobility is extremely high, which is also beneficial to improving the conductivity of the interconnection structure. In addition, the present technical solution completely avoids the formation of intermetallic compounds such as Sn / Cu, and adopts direct silver-silver bonding between the thorn-shaped silver plating layers and the thorn-shaped silver plating layers (the resistivity of silver is only 1.59μΩ·cm). The pure silver interface avoids resistance deterioration and reduces high-frequency signal transmission loss, which is also beneficial to improving the conductivity of the interconnection structure. In addition, due to the high interface bonding strength of the present technical solution, the interconnection interface reaches atomic-level tightness, eliminating microscopic voids, oxides and other insulating barriers, and electrons can directly pass through the interface, further reducing the contact resistance and improving the conductivity.

[0034] 3. Since the thermal conductivity of silver is about 429W / (m·K), which is higher than that of metals such as copper, the thorn-shaped silver plating layer has a higher thermal conductivity. At the same time, the heat conduction path of the thorn-shaped silver plating layer with a thorn-shaped structure is denser, which helps to dissipate heat quickly, so that the interconnection structure formed by the middle pad 1 and the middle chip 1 or the middle pad 2 and the middle chip 2 after flip-chip hot pressing bonding can quickly dissipate heat and have higher thermal conductivity. In addition, the high interface bonding strength of this technical solution not only makes the interface atomic vibration coupling more efficient and reduces the scattering of heat carriers when crossing the interface, but also ensures that heat can be quickly transferred from the chip to the heat dissipation pad, avoiding local temperature accumulation, thereby improving thermal conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the preparation method of Example 1 and Example 2 of a high thermal conductivity and high electrical conductivity interconnect structure of the present invention.

[0036] Figure 2 Schematic diagram of the preparation method of Example 3 and Example 4 of a high thermal conductivity and high electrical conductivity interconnect structure of the present invention. DETAILED DESCRIPTION

[0037] This technical solution provides a method for preparing a high thermal conductivity and high electrical conductivity interconnect structure, comprising the following steps:

[0038] A. mixing the steric hindering agent solution and the silver salt solution to obtain a steric hindering agent-silver salt composite solution;

[0039] B. Immersing a chip having copper bumps and a pad having copper bumps in a steric hinderant-silver salt composite solution, removing and drying to obtain a first intermediate pad and a first intermediate chip, respectively, wherein the outer layers of the copper bumps of the first intermediate pad and the first intermediate chip are both deposited with a thorn-shaped silver plating layer; performing flip-chip thermocompression bonding on the first intermediate pad and the first intermediate chip to obtain a primary bonding component; filling a coating between the chip and the pad of the primary bonding component, which, after curing, forms a filling coating and obtains a high thermal conductivity and high electrical conductivity interconnect structure;

[0040] Alternatively, a coating is applied to the surface of a solder pad having a copper bump, and after curing, a solder pad having a filling coating is obtained; the filling coating on the surface of the copper bump in the solder pad is removed to obtain a solder pad with the filling coating retained on the surface of the non-copper bump; the solder pad with the filling coating retained on the surface of the non-copper bump and the chip having the copper bump are immersed in a steric inhibitor-silver salt composite solution, taken out and dried to obtain a second intermediate solder pad and a second intermediate chip, respectively, wherein the outer layers of the copper bumps of the second intermediate solder pad and the second intermediate chip are both deposited with a thorn-shaped silver plating layer; the second intermediate solder pad and the second intermediate chip are flip-chip hot-pressed to obtain a high thermal conductivity and high electrical conductivity interconnection structure;

[0041] The thickness of the filling coating is the sum of the height of the copper bump of the pad, the thickness of the thorn-shaped silver plating layer of the pad, the height of the copper bump of the chip and the thickness of the thorn-shaped silver plating layer of the chip;

[0042] The raw materials of the coating include resin, curing agent and organic solvent.

[0043] To overcome the problems commonly faced by existing interconnect fabrication methods, such as insufficient electrical conductivity, poor thermal conductivity, and poor mechanical stability, this technical solution proposes a method for fabricating a high-thermal-conductivity interconnect structure. The method includes three steps: preparing a steric hinderer-silver salt composite solution, flip-chip hot-press bonding, and coating filling. By optimizing the fabrication method and raw materials, the electrical and thermal conductivity are improved while ensuring the interconnect structure has high mechanical stability, thus meeting practical application requirements. Furthermore, the interconnection method of this technical solution is simple, and the resulting interconnect structure has high interconnect reliability, which is conducive to large-scale promotion and application.

[0044] This technical solution, based on the properties of a steric hinderant-silver salt composite solution, utilizes a replacement reaction between the silver salt in the steric hinderant-silver salt composite solution and the copper atoms on the copper bumps on the pads, and between the silver salt in the steric hinderant-silver salt composite solution and the copper atoms on the surface of the copper bumps on the chip. This replaces the outer copper atoms of the copper bumps with silver atoms, in situ growing a thorn-like silver plating layer on the surface of the copper bumps, and forming a nanostructure with a high specific surface area. During the flip-chip hot-compression bonding process, even if the silver spikes with high specific surface area on the pads and the silver spikes with high specific surface area on the chip are not in full contact, the diffusion of silver atoms fills the gaps, achieving atomic-level mutual diffusion, promoting a metallurgical bond between the pads and the chip, and building a strong metal bond connection, thereby achieving a high-density and high-strength interconnect structure and effectively improving the mechanical stability of the interconnect structure.

[0045] At the same time, the silver salt in the steric hinderant-silver salt composite solution can be hydrolyzed, making the steric hinderant-silver salt composite solution weakly acidic. + It preferentially reacts with the copper oxide on the surface of the copper bump, dissolving the copper oxide layer and exposing the underlying pure copper. At this point, the replacement reaction rate between the exposed copper atoms and the silver ions is much higher than the reoxidation rate of copper. The resulting silver immediately coats the copper surface, preventing contact between copper and ambient oxygen and inhibiting the formation of a new copper oxide layer. In other words, this technical solution achieves self-cleaning and self-protection of the copper bump surface through the synergistic effect of acidic dissolution of copper oxide and in-situ silver plating via replacement reaction, ensuring a tight bond between the thorn-like silver plating layer and the copper bump, facilitating the construction of a high-strength interconnect structure.

[0046] Furthermore, the thorn-like silver coating (i.e., thorn-like silver nanostructures) grown in situ on the copper bumps of the pad and the chip through a replacement reaction has a high specific surface area and a porous morphology. Even if there are microscopic unevenness on the surface, the thorn-like silver nanostructures can still interpenetrate and form a barb effect during the flip-chip hot-press bonding process. This barb effect not only effectively suppresses interfacial slip but also compensates for surface roughness, thereby enhancing the bond strength and significantly improving the mechanical strength between the pad and the chip.

[0047] In addition, a filling coating is obtained by filling the paint, and the thickness of the filling coating is designed to be the sum of the pad copper bump height, the pad thorny silver plating thickness, the chip copper bump height and the chip thorny silver plating thickness, so that the filling coating completely covers the gap between the chip and the pad. This not only improves the mechanical stability, but also the filling coating can serve as a stress buffer layer. The stress buffer layer can effectively absorb thermomechanical stress, reduce interface delamination or cracking caused by thermal expansion coefficient mismatch, and further enhance the mechanical stability of the interconnect structure.

[0048] Furthermore, the technical solution immerses the chip and the pad in a steric hinderant-silver salt composite solution, and then performs a drying process after taking it out to remove any moisture or solvent that may remain on the surface of the silver spikes on the pad and the chip, thereby preventing bubbles or unevenness in the bonding interface layer during the subsequent flip-chip hot pressing bonding process, thereby enhancing the bonding strength between the silver spike coating on the pad and the silver spike coating on the chip, and improving the mechanical strength between the pad and the chip.

[0049] In summary, this technical solution improves the mechanical stability of the interconnected structure through the synergistic effects of thorny silver nanostructures and coating filling.

[0050] Secondly, during the flip-chip hot-press bonding process, the thorn-shaped silver plating layers generated by the replacement reaction penetrate each other to form multiple conductive paths, reducing the contact resistance and thereby improving the conductivity of the interconnection structure. At the same time, the nanosilver particles in the thorn-shaped silver plating layer have high surface energy, and surface diffusion sintering will occur during the flip-chip hot-press bonding process, which increases the grain boundary density at the interface connection and the electron mobility is extremely high, which is also beneficial to improving the conductivity of the interconnection structure. In addition, the present technical solution completely avoids the formation of intermetallic compounds such as Sn / Cu, and adopts direct silver-silver bonding between the thorn-shaped silver plating layers (the resistivity of silver is only 1.59μΩ·cm). The pure silver interface avoids resistance deterioration and reduces high-frequency signal transmission loss, which is also beneficial to improving the conductivity of the interconnection structure. In addition, due to the high interface bonding strength of the present technical solution, the interconnection interface reaches atomic-level tightness, eliminating microscopic voids, oxides and other insulating barriers, and electrons can directly pass through the interface, further reducing the contact resistance and improving the conductivity. That is, this technical solution achieves high conductivity through the mutual cooperation of multiple effects such as the three-dimensional interconnection of silver spines, pure silver interface and high bonding strength.

[0051] Furthermore, since the thermal conductivity of silver is about 429W / (m·K), its thermal conductivity is higher than that of metals such as copper, which gives the thorn-shaped silver plating a higher thermal conductivity. At the same time, the heat conduction path of the thorn-shaped silver plating with a thorn-shaped structure is denser, which helps to dissipate heat quickly, so that the interconnection structure formed by the middle pad 1 and the middle chip 1 or the middle pad 2 and the middle chip 2 after flip-chip hot pressing bonding can quickly conduct heat and have high thermal conductivity. In addition, the high interface bonding strength of the present technical solution not only makes the interface atomic vibration coupling more efficient and reduces the scattering of heat carriers when crossing the interface, but also ensures that heat can be quickly transferred from the chip to the heat dissipation pad, avoiding local temperature accumulation, thereby improving thermal conductivity. That is, the present technical solution achieves high thermal conductivity through the mutual cooperation of multiple aspects such as the high thermal conductivity of the thorn-shaped silver plating and the high bonding strength.

[0052] In summary, this technical solution solves the problems of traditional hot compression bonding's stringent requirements for surface flatness and solder bonding's proneness to producing brittle intermetallic compounds through the coordinated design of spiky silver nanostructures and filler coating stress buffering, achieving highly reliable heterogeneous integrated interconnection and giving the interconnect structure high electrical conductivity, high thermal conductivity, and mechanical stability.

[0053] It should be noted that conventional techniques use nanometal paste to connect the copper bumps of the chip and the copper bumps of the pads through hot pressing and sintering, thereby creating an interconnect structure. However, because the nanometal paste is in a semi-solid state, it easily flows between the copper bumps of the chip and the pad, causing short circuits, thus limiting the further reduction of the connection pitch. Furthermore, conventional hybrid bonding technology uses polishing techniques to achieve direct connection by smoothing the copper bumps of the chip and the pad to nanometer-level flatness. However, this process requires extremely high polishing precision and is complex.

[0054] This technical solution abandons nano-metal paste and instead uses an immersion process to deposit a nano-scale thorny silver plating layer on the surface between the copper bumps of the chip and the copper bumps of the pad. The thorny silver plating layer achieves a reliable connection between the copper bumps of the chip and the copper bumps of the pad. This method not only effectively avoids the risk of short circuit caused by the flow of nano-metal paste, but also provides a better solution for high-density and fine-pitch microelectronic interconnection. In addition, it does not require high-precision polishing during the connection process, which greatly reduces the technical requirements for the surface roughness of the copper bumps of the chip and the copper bumps of the pad, and achieves more efficient and low-cost reliable interconnection.

[0055] Finally, this technical solution mixes a steric inhibitor solution with a silver salt solution before performing flip-chip hot-compression bonding and filling coating. The steric hindrance of the steric inhibitor in the steric inhibitor solution reduces the diffusion rate of the silver salt in the silver salt solution, thereby promoting the replacement reaction between the silver ions in the silver salt and the copper atoms outside the copper bump, forming a thorn-like silver coating.

[0056] It should be noted that this technical solution must have a filling coating for the following reasons: (1) Without the filling coating, the chip and pad are connected solely by the thorny silver plating, which is prone to stress concentration and insufficient bonding strength, resulting in easy detachment or breakage under external force or vibration. (2) The filling coating has insulating properties and can form an insulating-conductive area between the filling coating and the copper bump with the thorny silver plating. While improving the bonding strength of the interconnect structure, it can achieve effective electrical isolation and avoid short circuits in the interconnect structure caused by the lack of the filling coating.

[0057] It should be further explained that the filling coating on the surface of the copper bump in the pad can be removed by laser removal, and the specific removal method is not limited here. In addition, the organic solvent can be anhydrous ethanol, ethylene glycol, polyethylene glycol, terpineol, propylene glycol, and the specific type is not limited here.

[0058] Preferably, the resin includes at least one of phenolic resin, urea-formaldehyde resin and polyimide resin;

[0059] The curing agent includes at least one of T31 phenalkamine, ethylenediamine and diethylenetriamine.

[0060] Phenolic resin, urea-formaldehyde resin and polyimide resin all have good insulation, heat resistance and adhesion strength, and are suitable for encapsulation curing. T31 phenolic amine, ethylenediamine and diethylenetriamine are used as curing agents to accelerate the curing speed and improve the degree of curing. Therefore, the present technical solution limits the resin to include at least one of phenolic resin, urea-formaldehyde resin and polyimide resin. The curing agent is limited to include at least one of T31 phenolic amine, ethylenediamine and diethylenetriamine, which is conducive to ensuring that a coating with a high degree of curing is obtained and the performance of the coating is ensured. In addition, the present technical solution also makes it possible to select a suitable curing agent according to the type of resin by optimizing the types of resin and curing agent, thereby improving the flexibility of the solution.

[0061] Further, in step A, the raw materials of the silver salt solution include silver salt and water, and the concentration of the silver salt in the silver salt solution is 0.1 to 20 mol / L.

[0062] By limiting the concentration of silver salt in the silver salt solution, the reduction rate of silver ions in the silver salt can be effectively controlled within the concentration range, ensuring that the obtained thorn-shaped silver coating is uniform and dense, thereby ensuring the performance of the product.

[0063] Preferably, the concentration of the silver salt in the silver salt solution is 1 to 10 mol / L.

[0064] Preferably, the silver salt is silver nitrate.

[0065] Since silver nitrate is cheap, has high solubility at room temperature, and has high stability after dissolution and is not easy to decompose, the present technical solution limits the silver salt to silver nitrate, which is beneficial to avoid the particle precipitation caused by low-solubility silver salts (such as Ag3PO4) while reducing costs, thereby ensuring the uniformity of the thorn-shaped silver coating. In addition, silver nitrate is not only easy to combine with steric inhibitors to guide the directional growth of the thorn-shaped silver coating, but also the anion nitrate in silver nitrate is inert and will not participate in the reaction, thereby ensuring the purity of the thorn-shaped silver coating. In addition, the silver nitrate solution is weakly acidic, which can gently dissolve copper oxides without excessively corroding copper bumps.

[0066] Further, in step A, the raw materials of the steric hindering agent solution include a steric hindering agent and water, and the concentration of the steric hindering agent in the steric hindering agent solution is 0.5 to 20 g / L.

[0067] By limiting the concentration of the steric hinderant in the steric hinderant solution, the reduction rate of silver ions in the silver salt can be effectively controlled within the concentration range, ensuring that the obtained thorn-shaped silver coating is uniform and dense, thereby ensuring the performance of the product.

[0068] Preferably, the concentration of the steric hinderant in the steric hinderant solution is 3 to 12 g / L.

[0069] Preferably, the steric hindering agent includes any one of gelatin and polyethylene glycol.

[0070] Gelatin and polyethylene glycol have good water solubility, easily forming homogeneous solutions and ensuring a good steric hindrance effect. Furthermore, gelatin and polyethylene glycol are economical to produce on a large scale. By limiting the type of steric hindrance agent to either gelatin or polyethylene glycol, the steric hindrance agent in this technical solution meets the material safety and environmental requirements of modern electronic packaging.

[0071] Further, in step A, the mixing ratio of the steric hinderant solution to the silver salt solution is 1:(8-10) calculated by mass ratio.

[0072] This technical solution limits the mixing ratio of the steric hindering agent solution to the silver salt solution, and achieves the following multiple technical advantages while reducing the amount of steric hindering agent used and reducing production costs: (1) This ratio design not only ensures sufficient silver ion supply, promotes the efficient completion of the replacement reaction, and avoids discontinuous coating, but also accurately controls the directional growth of silver nanoparticles, forming a thorn-like structure with a high specific surface area rather than an agglomerated morphology. (2) This ratio design not only avoids the inhibition of reaction activity caused by excessive steric hindering agent, but also ensures the density and mechanical interlocking characteristics of the silver coating, ultimately making the bonding interface have excellent electrical conductivity, thermal conductivity and mechanical strength.

[0073] Further, in step B, the mixing ratio of the resin, curing agent and organic solvent in the coating is (2-10):1:(15-20) calculated by mass ratio.

[0074] This technical solution limits the mixing ratio of resin, curing agent, and organic solvent. Using a higher proportion of resin ensures that the coating has sufficient mechanical strength and adhesion. Using an appropriate amount of curing agent not only ensures sufficient cross-linking and curing, but also avoids increased brittleness caused by excessive amounts. Using a larger proportion of organic solvent can adjust the viscosity of the system, giving the coating excellent fluidity and spreadability, facilitating uniform coating and penetration into microstructures. Therefore, by adjusting the mixing ratio of resin, curing agent, and organic solvent in this technical solution, it is beneficial to balance process operability while ensuring the mechanical properties and curing effect of the coating, ultimately forming a dense, strong, and stress-buffering filling layer, significantly improving the reliability of the interconnect structure.

[0075] Further explanation, in step B, the flip-chip thermal compression bonding method is:

[0076] Fixing substrates on the bottom of the first middle pad and the first middle chip respectively to obtain a first substrate-pad assembly and a first substrate-chip assembly;

[0077] Substrate-chip assembly 1 is flipped upside down on substrate-pad assembly 1, and after the spike-shaped silver coating on substrate-chip assembly 1 is precisely aligned with the spike-shaped silver coating on substrate-pad assembly 1, pressure is applied to the bottom of substrate-chip assembly 1 to bond the spike-shaped silver coating on substrate-chip assembly 1 and substrate-pad assembly 1 at a bonding temperature until substrate-chip assembly 1 and substrate-pad assembly 1 are completely fixed.

[0078] Removing the substrates at the bottom of the substrate-chip assembly 1 and the substrate-pad assembly 1 to complete flip-chip thermocompression bonding;

[0079] Alternatively, substrates are fixed to the bottoms of the second intermediate pad and the second intermediate chip, respectively, to obtain a second substrate-pad assembly and a second substrate-chip assembly, respectively;

[0080] The second substrate-chip assembly is placed upside down on the second substrate-pad assembly, and the silver-plated spikes on the second substrate-chip assembly are precisely aligned with the silver-plated spikes on the second substrate-pad assembly. Pressure is then applied to the bottom of the second substrate-chip assembly to bond the silver-plated spikes on the second substrate-chip assembly to the silver-plated spikes on the second substrate-pad assembly at a bonding temperature until the second substrate-chip assembly is completely fixed to the second substrate-pad assembly.

[0081] The substrates at the bottom of the second substrate-chip assembly and the second substrate-pad assembly are removed to complete the flip-chip thermocompression bonding.

[0082] The present technical solution optimizes the flip-chip thermocompression bonding method and detachably fixes the substrate at the bottom of the pads with the thorny silver plating and the chip with the thorny silver plating, thereby preventing damage to the pads with the thorny silver plating and the chip with the thorny silver plating during the flip-chip thermocompression bonding process, thereby ensuring the integrity of the resulting interconnection structure.

[0083] Further description, in step B, the bonding temperature of the flip-chip thermal compression bonding is 160-400° C., and the applied pressure is 0.5-50 MPa.

[0084] If the flip-chip thermocompression bonding temperature is too high, the silver spikes can easily oxidize, deform, or decompose; if the flip-chip thermocompression bonding temperature is too low, the bond between the silver spikes is weak; if the flip-chip thermocompression bonding pressure is too high, the chip structure can be damaged; if the flip-chip thermocompression bonding pressure is too low, the bonding interface can be inadequate, reducing the bond strength. Therefore, this technical solution limits the temperature and pressure of flip-chip thermocompression bonding, which helps ensure the performance of the resulting product.

[0085] Preferably, in step B, the temperature of the flip-chip thermal compression bonding is 200-300° C., and the pressure is 5-30 MPa.

[0086] Further explanation, step C is included between step A and step B, and step C is:

[0087] The pads with copper bumps and the chips with copper bumps are cleaned respectively.

[0088] This technical solution cleans both the solder pad with copper bumps and the chip with copper bumps, so that before flip-chip hot-press bonding and filling with paint, the oxide layer and contaminants on the surface of the solder pad and the copper bumps in the chip can be effectively removed, ensuring the cleanliness of the surface of the solder pad and the chip, thereby improving the adhesion and uniformity of the thorn-shaped silver plating and ensuring the quality of the thorn-shaped silver plating.

[0089] To further illustrate, the cleaning method is: using an acidic solution with a pH value of 5 to 6 and clean water in sequence to clean the pad with copper bumps and the chip with copper bumps respectively.

[0090] This technical solution is beneficial to improving the cleaning effect by optimizing the specific cleaning method, thereby further ensuring the quality of the thorn-shaped silver plating layer.

[0091] It should be noted that the acidic solution may be a hydrochloric acid solution or a sulfuric acid solution, and the specific type is not limited here.

[0092] A high thermal conductivity and high electrical conductivity interconnection structure is prepared using the above-mentioned method for preparing a high thermal conductivity and high electrical conductivity interconnection structure.

[0093] This technical solution also proposes a method for preparing a high thermal conductivity and high electrical conductivity interconnection structure to prepare a high thermal conductivity and high electrical conductivity interconnection structure. The obtained interconnection structure achieves high electrical conductivity and high thermal conductivity while improving mechanical stability to meet actual usage needs.

[0094] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0095] Performance testing:

[0096] Conductivity: Wire cutting is used to remove the top and bottom portions of the interconnect structure, leaving only the copper bump, the silver plating spikes, and the filler coating (i.e., the test area). Using a four-point probe method, the volume resistivity of the conductive area (comprising the copper bump and the silver plating spikes) is measured at the four corners and the center of the test area. The average of the five measurements is taken as the volume resistivity. A volume resistivity of ≤1.8 μΩ·cm is considered acceptable.

[0097] Thermal Conductivity: Wire cutting is used to remove the top and bottom portions of the interconnect structure, leaving only the copper bump, the silver plating spikes, and the filler coating (i.e., the test area). A laser flash thermal conductivity meter is used to measure the thermal conductivity of the test area (comprising the copper bump and the silver plating spikes) at the four corners and the center. The average of the five measurements is used as the thermal conductivity test. A value of ≥500 W / (m·K) is considered acceptable.

[0098] Mechanical stability: Use a thrust tester to apply shear force to the surface of the interconnect at a speed of 50 μm / s until the bond fails. Record the maximum shear force at which the bond fails. Calculate the shear strength based on the maximum shear force and the cross-sectional area of ​​the interconnect. A shear strength of 15 MPa or higher is considered acceptable.

[0099] Example 1

[0100] A. Figure 1 As shown, the gelatin solution and the silver salt solution are uniformly mixed to obtain a gelatin-silver nitrate composite solution 1; wherein, calculated by mass ratio, the mixing ratio of the gelatin solution to the silver nitrate solution is 1:8; the raw materials of the silver salt solution include silver nitrate and water, and the concentration of silver nitrate in the silver nitrate solution is 0.5 mol / L; the raw materials of the gelatin solution include gelatin and water, and the concentration of gelatin in the gelatin solution is 3 g / L;

[0101] C. Sequentially cleaning the pad with copper bumps and the chip with copper bumps using a sulfuric acid solution with a pH value of 5 and clean water, respectively, to obtain a cleaned pad 2 and a cleaned chip 3, respectively;

[0102] B. Immersing the cleaned pad 2 and chip 3 in a steric inhibitor-silver salt composite solution 1, removing and drying them to obtain an intermediate pad 4 and an intermediate chip 5, respectively. The outer layers of the copper bumps of the intermediate pad 4 and the intermediate chip 5 are both deposited with a thorn-like silver plating layer.

[0103] A substrate 6 is fixed to the bottom of the middle pad 4 and the middle chip 5, respectively, to obtain a substrate-pad assembly 7 and a substrate-chip assembly 8, respectively. The substrate-chip assembly 8 is flipped onto the substrate-pad assembly 7, and the thorn-shaped silver plating on the substrate-chip assembly 8 is precisely aligned with the thorn-shaped silver plating on the substrate-pad assembly 7. Then, a pressure of 6 MPa is applied to the bottom of the substrate-chip assembly 8 to bond the thorn-shaped silver plating on the substrate-chip assembly 8 to the thorn-shaped silver plating on the substrate-pad assembly 7 at a temperature of 200° C. until the substrate-chip assembly 1 and the substrate-pad assembly 1 are completely fixed. The substrates at the bottom of the substrate-chip assembly 8 and the substrate-pad assembly 7 are removed to complete flip-chip thermocompression bonding, thereby obtaining a primary bonding component 9. A coating is filled between the chip and the pad of the primary bonding component 9, which, after curing, forms a filling coating 10, thereby obtaining a high thermal conductivity and high electrical conductivity interconnect structure 100.

[0104] Among them, the thickness of the filling coating 10 is the sum of the height of the copper bump of the pad, the thickness of the thorny silver plating of the pad, the height of the copper bump of the chip and the thickness of the thorny silver plating of the chip; the raw materials of the coating include urea-formaldehyde resin, phenalkamine and ethylene glycol, and calculated by mass ratio, the mixing ratio of urea-formaldehyde resin, phenalkamine and ethylene glycol in the coating is 3:1:15.

[0105] Example 2

[0106] A. Figure 1 As shown, the polyethylene glycol solution and the silver nitrate solution are evenly mixed to obtain a polyethylene glycol-silver nitrate composite solution 1; wherein, calculated by mass ratio, the mixing ratio of the polyethylene glycol solution to the silver nitrate solution is 1:9; the raw materials of the polyethylene glycol solution include silver nitrate and water, and the concentration of silver nitrate in the silver nitrate solution is 4 mol / L; the raw materials of the polyethylene glycol solution include polyethylene glycol and water, and the concentration of polyethylene glycol in the polyethylene glycol solution is 5 g / L;

[0107] C. using a hydrochloric acid solution with a pH value of 6 and clean water to clean the pad with copper bumps and the chip with copper bumps, respectively, to obtain a cleaned pad 2 and a cleaned chip 3, respectively;

[0108] B. Immersing the cleaned pad 2 and chip 3 in a steric inhibitor-silver salt composite solution 1, removing and drying them to obtain an intermediate pad 4 and an intermediate chip 5, respectively. The outer layers of the copper bumps of the intermediate pad 4 and the intermediate chip 5 are both deposited with a thorn-like silver plating layer.

[0109] A substrate 6 is fixed to the bottom of the middle pad 4 and the middle chip 5, respectively, to obtain a substrate-pad assembly 7 and a substrate-chip assembly 8, respectively. The substrate-chip assembly 8 is flipped onto the substrate-pad assembly 7, and the thorn-shaped silver plating on the substrate-chip assembly 8 is precisely aligned with the thorn-shaped silver plating on the substrate-pad assembly 7. Then, a pressure of 10 MPa is applied to the bottom of the substrate-chip assembly 8 to bond the thorn-shaped silver plating on the substrate-chip assembly 8 to the thorn-shaped silver plating on the substrate-pad assembly 7 at a temperature of 300° C. until the substrate-chip assembly 1 and the substrate-pad assembly 1 are completely fixed. The substrates at the bottom of the substrate-chip assembly 8 and the substrate-pad assembly 7 are removed to complete flip-chip thermocompression bonding, thereby obtaining a primary bonding component 9. A coating is filled between the chip and the pad of the primary bonding component 9, and after curing, a filling coating 10 is formed, thereby obtaining a high thermal conductivity and high electrical conductivity interconnect structure 100.

[0110] The thickness of the filling coating 10 is the sum of the height of the copper bump of the pad, the thickness of the thorny silver plating of the pad, the height of the copper bump of the chip, and the thickness of the thorny silver plating of the chip; the raw materials of the coating include phenolic resin, ethylenediamine and anhydrous ethanol, and calculated by mass ratio, the mixing ratio of phenolic resin, ethylenediamine and anhydrous ethanol in the coating is 4:1:16.

[0111] Example 3

[0112] A. Figure 2 As shown, the polyethylene glycol solution and the silver nitrate solution are uniformly mixed to obtain a polyethylene glycol-silver nitrate composite solution 1; wherein, calculated by mass ratio, the mixing ratio of the polyethylene glycol solution to the silver nitrate solution is 1:8; the raw materials of the polyethylene glycol solution include silver nitrate and water, and the concentration of silver nitrate in the silver nitrate solution is 0.50 mol / L; the raw materials of the polyethylene glycol solution include polyethylene glycol and water, and the concentration of polyethylene glycol in the polyethylene glycol solution is 0.8 g / L;

[0113] C. Sequentially cleaning the pad with copper bumps and the chip with copper bumps using a sulfuric acid solution with a pH value of 5 and clean water, respectively, to obtain a cleaned pad 2 and a cleaned chip 3, respectively;

[0114] B. Coating the surface of the cleaned pad 2 with a coating, and curing the coating to obtain a pad 4 having a filling coating 100; removing the filling coating 100 on the surface of the copper bump in the pad 4 using a laser, to obtain a pad 5 having the filling coating 100 retained on the surface of the non-copper bump; immersing the pad 5 having the filling coating 100 retained on the surface of the non-copper bump and the cleaned chip 3 in a steric inhibitor-silver salt composite solution 1, removing and drying them, respectively, to obtain an intermediate pad 6 and an intermediate chip 7, wherein the outer layers of the copper bumps of the intermediate pad 6 and the intermediate chip 7 are both deposited with a thorn-like silver plating layer;

[0115] A substrate 8 is fixed to the bottom of the second intermediate pad 6 and the second intermediate chip 7, respectively, to obtain a second substrate-pad assembly 9 and a second substrate-chip assembly 10, respectively. The second substrate-chip assembly 10 is flipped onto the second substrate-pad assembly 9, and the thorn-shaped silver plating on the second substrate-chip assembly 10 is precisely aligned with the thorn-shaped silver plating on the second substrate-pad assembly 9. Then, a pressure of 20 MPa is applied to the bottom of the second substrate-chip assembly 10, so that the thorn-shaped silver plating on the second substrate-chip assembly 10 and the thorn-shaped silver plating on the second substrate-pad assembly 9 are bonded at a temperature of 350° C. until the second substrate-chip assembly 10 is completely fixed to the second substrate-pad assembly 9. The substrate 8 is removed from the bottom of the second substrate-chip assembly 10 and the second substrate-pad assembly 9, completing the flip-chip thermocompression bonding to obtain a high thermal conductivity and high electrical conductivity interconnect structure 200.

[0116] The thickness of the filling coating 100 is the sum of the height of the copper bump of the pad, the thickness of the thorny silver plating of the pad, the height of the copper bump of the chip, and the thickness of the thorny silver plating of the chip; the raw materials of the coating include polyimide resin, diethylenetriamine and propylene glycol, and calculated by mass ratio, the mixing ratio of polyimide resin, diethylenetriamine and propylene glycol in the coating is 5:1:18.

[0117] Example 4

[0118] A. Figure 2 As shown, a gelatin solution and a silver salt solution are uniformly mixed to obtain a gelatin-silver nitrate composite solution 1; wherein, calculated by mass ratio, the mixing ratio of the gelatin solution to the silver nitrate solution is 1:(8-10); the raw materials of the silver salt solution include silver nitrate and water, and the concentration of silver nitrate in the silver nitrate solution is 15 mol / L; the raw materials of the gelatin solution include gelatin and water, and the concentration of gelatin in the gelatin solution is 8 g / L;

[0119] C. Sequentially cleaning the pad with copper bumps and the chip with copper bumps using a sulfuric acid solution with a pH value of 6 and clean water, respectively, to obtain a cleaned pad 2 and a cleaned chip 3, respectively;

[0120] B. Coating the surface of the cleaned pad 2 with a coating, and curing the coating to obtain a pad 4 having a filling coating 100; removing the filling coating 100 on the surface of the copper bump in the pad 4 using a laser, to obtain a pad 5 having the filling coating 100 retained on the surface of the non-copper bump; immersing the pad 5 having the filling coating 100 retained on the surface of the non-copper bump and the cleaned chip 3 in a steric inhibitor-silver salt composite solution 1, removing and drying them, respectively, to obtain an intermediate pad 6 and an intermediate chip 7, wherein the outer layers of the copper bumps of the intermediate pad 6 and the intermediate chip 7 are both deposited with a thorn-like silver plating layer;

[0121] A substrate 8 is fixed to the bottom of the second intermediate pad 6 and the second intermediate chip 7, respectively, to obtain a second substrate-pad assembly 9 and a second substrate-chip assembly 10, respectively. The second substrate-chip assembly 10 is flipped onto the second substrate-pad assembly 9, and the thorn-shaped silver plating on the second substrate-chip assembly 10 is precisely aligned with the thorn-shaped silver plating on the second substrate-pad assembly 9. Then, a pressure of 30 MPa is applied to the bottom of the second substrate-chip assembly 10 to bond the thorn-shaped silver plating on the second substrate-chip assembly 10 to the thorn-shaped silver plating on the second substrate-pad assembly 9 at a temperature of 400° C. until the second substrate-chip assembly 10 is completely fixed to the second substrate-pad assembly 9. The substrate 8 is removed from the bottom of the second substrate-chip assembly 10 and the second substrate-pad assembly 9, completing the flip-chip thermocompression bonding to obtain a high thermal conductivity and high electrical conductivity interconnect structure 200.

[0122] The thickness of the filling coating 100 is the sum of the height of the copper bump of the pad, the thickness of the thorny silver plating of the pad, the height of the copper bump of the chip, and the thickness of the thorny silver plating of the chip; the raw materials of the coating include phenolic resin, ethylenediamine and propylene glycol, and calculated by mass ratio, the mixing ratio of phenolic resin, ethylenediamine and propylene glycol in the coating is 6:1:20.

[0123] Comparative Example 1

[0124] Comparative Example 1 uses the existing hot-press bonding technology to prepare an interconnection structure. That is, the method and raw materials of Comparative Example 1 are the same as those of Example 1, except that the filling coating and the thorn-shaped silver plating layer are not provided in Comparative Example 1. The specific method is as follows:

[0125] A. using a sulfuric acid solution with a pH value of 5 and clean water to clean the pad with copper bumps and the chip with copper bumps, respectively, to obtain a cleaned pad and a cleaned chip, respectively;

[0126] B. Fixing substrates on the bottom of the cleaned pad and the cleaned chip, respectively, to obtain a substrate-pad assembly and a substrate-chip assembly, respectively; placing the substrate-chip assembly upside down on the substrate-pad assembly, accurately aligning the copper bumps on the substrate-chip assembly with the copper bumps on the substrate-pad assembly, applying a pressure of 6 MPa to the bottom of the substrate-chip assembly, bonding the copper bumps on the substrate-chip assembly with the copper bumps on the substrate-pad assembly at a temperature of 200°C until the substrate-chip assembly and the substrate-pad assembly are completely fixed; removing the substrates at the bottom of the substrate-chip assembly and the substrate-pad assembly, completing flip-chip thermocompression bonding, and obtaining a high thermal conductivity and high electrical conductivity interconnect structure 100.

[0127] Comparative Example 2

[0128] Comparative Example 2 uses existing solder bonding technology to prepare an interconnection structure. That is, the method and raw materials of Comparative Example 2 are the same as those of Example 1. The difference is that Comparative Example 2 does not provide a filling coating, and uses Sn-Ag-Cu series tin-based solder produced by Shenzhen Fuyingda Industrial Technology Co., Ltd. to coat the surface of the copper bump for connection. The specific method is as follows:

[0129] A. using a sulfuric acid solution with a pH value of 5 and clean water to clean the pad with copper bumps and the chip with copper bumps, respectively, to obtain a cleaned pad and a cleaned chip, respectively;

[0130] B. coating tin-based solder on the copper bumps of the cleaned pad and the copper bumps of the cleaned chip, respectively, to obtain a third intermediate pad and a third intermediate chip, wherein the outer layers of the copper bumps of the third intermediate pad and the third intermediate chip are both deposited with tin-based solder;

[0131] Fix substrates at the bottom of middle pad three and middle chip three, respectively, to obtain substrate-pad assembly three and substrate-chip assembly three, respectively; place substrate-chip assembly three upside down on substrate-pad assembly three, so that the tin-based solder on substrate-chip assembly three and the tin-based solder on substrate-pad assembly three are precisely aligned, and then apply a pressure of 6 MPa to the bottom of substrate-chip assembly three, so that the tin-based solder on substrate-chip assembly three and the tin-based solder on substrate-pad assembly three are bonded at a temperature of 200°C until substrate-chip assembly three and substrate-pad assembly three are completely fixed; remove the substrates at the bottom of substrate-chip assembly three and substrate-pad assembly three, complete flip-chip hot pressing bonding, and obtain a high thermal conductivity and high electrical conductivity interconnection structure.

[0132] The interconnect structures were prepared using the methods of the above embodiment and comparative example, and the electrical conductivity, thermal conductivity and mechanical stability of the prepared interconnect structures were tested. The test results are shown in Table 1 below.

[0133] Table 1 Related performance test results of interconnection structure

[0134]

[0135]

[0136] The test results above demonstrate that the interconnect structure produced by this technical solution exhibits improved electrical conductivity, thermal conductivity, and mechanical stability compared to the interconnect structure produced by the prior art. Therefore, the interconnect structure produced by this technical solution is advantageous in achieving improved electrical and thermal conductivity while also enhancing mechanical stability, thus meeting practical application requirements.

[0137] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are intended solely to illustrate the principles of the present invention and are not to be construed in any way as limiting the scope of protection of the present invention. Based on the explanations herein, those skilled in the art will readily conceive of other specific embodiments of the present invention without inventive effort, and such embodiments will fall within the scope of protection of the present invention.

Claims

1. A method for preparing a high thermal conductivity and high electrical conductivity interconnect structure, characterized in that: The following steps are involved: A. mixing the steric hindering agent solution and the silver salt solution to obtain a steric hindering agent-silver salt composite solution; B. Immersing a chip having copper bumps and a pad having copper bumps in a steric hinderant-silver salt composite solution, removing and drying to obtain a first intermediate pad and a first intermediate chip, respectively, wherein the outer layers of the copper bumps of the first intermediate pad and the first intermediate chip are both deposited with a thorn-shaped silver plating layer; performing flip-chip thermocompression bonding on the first intermediate pad and the first intermediate chip to obtain a primary bonding component; filling a coating between the chip and the pad of the primary bonding component, which, after curing, forms a filling coating and obtains a high thermal conductivity and high electrical conductivity interconnect structure; Alternatively, a coating is applied to the surface of a solder pad having a copper bump, and after curing, a solder pad having a filling coating is obtained; the filling coating on the surface of the copper bump in the solder pad is removed to obtain a solder pad with the filling coating retained on the surface of the non-copper bump; the solder pad with the filling coating retained on the surface of the non-copper bump and the chip having the copper bump are immersed in a steric inhibitor-silver salt composite solution, taken out and dried to obtain a second intermediate solder pad and a second intermediate chip, respectively, wherein the outer layers of the copper bumps of the second intermediate solder pad and the second intermediate chip are both deposited with a thorn-shaped silver plating layer; the second intermediate solder pad and the second intermediate chip are flip-chip hot-pressed to obtain a high thermal conductivity and high electrical conductivity interconnection structure; The thickness of the filling coating is the sum of the height of the copper bump of the pad, the thickness of the thorn-shaped silver plating layer of the pad, the height of the copper bump of the chip and the thickness of the thorn-shaped silver plating layer of the chip; The raw materials of the coating include resin, curing agent and organic solvent.

2. The method for preparing a high thermal conductivity and high electrical conductivity interconnect structure according to claim 1, wherein: In step A, the raw materials of the silver salt solution include silver salt and water, and the concentration of the silver salt in the silver salt solution is 0.1 to 20 mol / L.

3. The method for preparing a high thermal conductivity and high electrical conductivity interconnect structure according to claim 1, wherein: In step A, the raw materials of the steric hindering agent solution include a steric hindering agent and water, and the concentration of the steric hindering agent in the steric hindering agent solution is 0.5 to 20 g / L.

4. The method for preparing a high thermal conductivity and high electrical conductivity interconnect structure according to claim 1, wherein: In step A, the mixing ratio of the steric hindering agent solution to the silver salt solution is 1:(8-10) calculated by mass ratio.

5. The method for preparing a high thermal conductivity and high electrical conductivity interconnect structure according to claim 1, wherein: In step B, the mixing ratio of the resin, the curing agent and the organic solvent in the coating is (2-10):1:(15-20) calculated by mass ratio.

6. The method for preparing a high thermal conductivity and high electrical conductivity interconnect structure according to claim 1, wherein: In step B, the flip-chip thermal compression bonding method is: Fixing substrates on the bottom of the first middle pad and the first middle chip respectively to obtain a first substrate-pad assembly and a first substrate-chip assembly; Substrate-chip assembly 1 is flipped upside down on substrate-pad assembly 1, and after the spike-shaped silver coating on substrate-chip assembly 1 is precisely aligned with the spike-shaped silver coating on substrate-pad assembly 1, pressure is applied to the bottom of substrate-chip assembly 1 to bond the spike-shaped silver coating on substrate-chip assembly 1 and substrate-pad assembly 1 at a bonding temperature until substrate-chip assembly 1 and substrate-pad assembly 1 are completely fixed. Removing the substrates at the bottom of the substrate-chip assembly 1 and the substrate-pad assembly 1 to complete flip-chip thermocompression bonding; Alternatively, substrates are fixed to the bottoms of the second intermediate pad and the second intermediate chip, respectively, to obtain a second substrate-pad assembly and a second substrate-chip assembly, respectively; The second substrate-chip assembly is placed upside down on the second substrate-pad assembly, and the silver-plated spikes on the second substrate-chip assembly are precisely aligned with the silver-plated spikes on the second substrate-pad assembly. Pressure is then applied to the bottom of the second substrate-chip assembly to bond the silver-plated spikes on the second substrate-chip assembly to the silver-plated spikes on the second substrate-pad assembly at a bonding temperature until the second substrate-chip assembly is completely fixed to the second substrate-pad assembly. The substrates at the bottom of the second substrate-chip assembly and the second substrate-pad assembly are removed to complete the flip-chip thermocompression bonding.

7. The method for preparing a high thermal conductivity and high electrical conductivity interconnect structure according to claim 6, characterized in that: In step B, the bonding temperature of the flip-chip thermal compression bonding is 160-400° C., and the applied pressure is 0.5-50 MPa.

8. The method for preparing a high thermal conductivity and high electrical conductivity interconnect structure according to claim 1, wherein: Step C is also included between step A and step B, and step C is: The pads with copper bumps and the chips with copper bumps are cleaned respectively.

9. The method for preparing a high thermal conductivity and high electrical conductivity interconnect structure according to claim 8, characterized in that: The cleaning method comprises the following steps: using an acidic solution with a pH value of 5 to 6 and clean water in sequence to clean the pad with the copper bumps and the chip with the copper bumps respectively.

10. A high thermal conductivity and high electrical conductivity interconnect structure, characterized in that: It is prepared using the method for preparing a high thermal conductivity and high electrical conductivity interconnect structure according to any one of claims 1 to 9.

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