A pressureless sintering silver copper compound adhesive suitable for copper-gold-silver heterogeneous interface sintering interconnection and a preparation method thereof

Abstract

The application discloses a pressureless sintering silver-copper compound adhesive suitable for copper-gold-silver heterogeneous interface sintering interconnection and a preparation method, and belongs to the technical field of adhesives. The pressureless sintering silver-copper compound adhesive comprises the following raw materials: fine silver particles, silver powder, nano copper particles, a sintering aid and a carrier; wherein the sintering aid comprises one or both of component D1 and component D2; the component D1 is selected from one of cobalt acetylacetonate, chromium acetylacetonate and chlorocyanohematin; and the component D2 is selected from one of cuprous iodide, neodecanoic acid and (diethylamino) difluorosulfonium tetrafluoroborate. The paste-like adhesive is obtained through three-roll grinding and vacuum defoaming during preparation. Low-temperature pressureless sintering can realize firm bonding of high-thermal-conductivity, high-reliability and large-area chips and copper / gold / silver substrates, and is suitable for packaging of third-generation semiconductors such as GaN.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of adhesives, and particularly relates to a pressureless sintering silver-copper compound adhesive suitable for copper-gold-silver heterogeneous interface sintering interconnection and a preparation method. BACKGROUND

[0002] Pressureless nano-sintering solder plays a key role in advanced semiconductor device packaging, has become the core supporting material for the third generation of semiconductor industrialization, and is widely used in important advanced technology fields such as new energy transportation supporting charging equipment represented by gallium nitride (GaN) and gallium oxide (GaO), 5G base station high-power radio frequency chip modules, ultra-high power radar detection chip modules and high-power lighting LED chip modules. As a core link to improve semiconductor performance, advanced packaging materials can effectively improve chip integration, reduce device size and reduce operating power consumption, and have become an important direction for the next stage of semiconductor technology development. With the popularization of 5G commercialization, the promotion of electric vehicles, and the rapid development of emerging fields such as artificial intelligence and VR / AR, the market demand for high-end semiconductor packaging materials continues to rise. Among them, pressureless sintering silver gradually replaces traditional conductive adhesive due to its excellent performance, showing broad development prospects in the field of semiconductor packaging, and its market demand continues to grow with the continuous upgrading of the semiconductor industry.

[0003] In semiconductor device packaging, materials used to bond semiconductor devices and electrical / electronic components (such as chip connection paste, heat dissipation member bonding materials, etc.) need to have high thermal conductivity, and need to withstand reflow soldering during product installation on the substrate, and meet the process requirements of large-area sintering. However, in the current market, the mainstream pressureless sintering silver products are mainly imported materials, and their application has obvious limitations: existing products can only adapt to 0.5x0.5mm² to 5x5mm² chip die bonding, and cannot meet the bonding requirements of large-size chips of 10x10mm² to 40x40mm² in advanced process packaging. More importantly, in the field of high-power GaN radio frequency chips, high aspect ratio chip designs such as 6x2mm² and 7x1mm² are widely used. Although the bonding area of this structure is equivalent to that of a square chip, the internal stress is significantly increased, which can easily cause bonding failure.

[0004] The above problems directly lead to the current no-pressure sintering silver product facing severe challenges in large-area or high aspect ratio application scenarios: due to the difference in the thermal expansion coefficient between the material and the substrate, there are generally problems such as low bonding rate, poor reliability, and easy delamination of the welding interface, which seriously hinders the power upgrade process of the GaN module. At the same time, the cost reduction demand of chip packaging is extremely urgent. If safe and reliable bonding of sintered silver and large-area pure copper substrate can be achieved, the packaging cost can be reduced by more than 20%, but the difference in the thermal expansion coefficient is still the main difficulty in this cost reduction path. In addition, the sintering solder needs to adapt to the heterogeneous interface at the same time - one end is bonded to the chip interface with a gold-plated, silver-plated or other noble metal plating layer, and the other end is bonded to the low-cost pure copper substrate interface. The difference in the thermal expansion coefficient of the heterogeneous materials leads to a significant increase in stress, further exacerbating the technical problem.

[0005] To break through the above bottleneck, the no-pressure sintering technology of compounded nano-copper powder and silver powder becomes an important direction. Its goal is to achieve metal densification sintering and high-quality bonding of gold-plated, silver-plated and pure copper substrates at a relatively low temperature of 200-250°C without pressure assistance. This demand is closely related to the characteristics of GaN chips. Since GaN chips are light, thin and hard and brittle, they cannot withstand the mechanical force of pressure equipment, so no-pressure process becomes an inevitable choice. However, the current industry's sintering solder using nano-copper powder as raw material has obvious shortcomings: its metal densification and penetration sintering with the substrate need to rely on pressure equipment assistance, which is difficult to adapt to no-pressure scenarios such as GaN chips, which requires nano-copper powder to have excellent sintering activity and oxidation resistance under no-pressure process. In practical applications, an oxide layer is easily formed on the surface of the copper substrate, directly leading to a decrease in the adhesion of the solder; especially for fine structure joints, higher adhesion is required, and the existence of heterogeneous interfaces further increases the difficulty of adaptation. Therefore, developing a material that can achieve full bonding strength in an inert atmosphere is crucial for reducing substrate oxidation and improving the adhesion performance of heterogeneous interfaces. SUMMARY

[0006] To solve the above technical problems, the present application provides a no-pressure sintering silver-copper compounded adhesive suitable for copper-gold-silver heterogeneous interface sintering interconnection and a preparation method.

[0007] To achieve the above purpose, the present application provides the following technical solutions:

[0008] One of the purposes of the present application is to provide a no-pressure sintering silver-copper compounded adhesive (paste composition) suitable for copper-gold-silver heterogeneous interface sintering interconnection, which comprises the following raw materials: fine silver particles, silver powder, nano-copper particles, sintering additives and carriers;

[0009] Among them, the sintering additive includes one or both of component D1 and component D2;

[0010] The component D1 is selected from one of cobalt acetylacetonate, chromium acetylacetonate and hematin chloride;

[0011] The component D2 is selected from one of cuprous iodide, neodecanoic acid and (diethylamino) difluorosulfonium tetrafluoroborate.

[0012] The silver (fine silver particles, silver powder) selected by the present application is used as a leading conductive phase, the high conductivity and chemical stability of silver are used to provide a basic metal bonding network for the heterogeneous interface (copper-gold-silver), the nano-copper particles improve the pressureless sintering activity through high surface energy (the surface diffusion coefficient of nano-particles is high, and it is easy to form a sintering neck at low temperature), and the homogeneity of the metal copper thermal expansion coefficient and the adhesive interface material is relied on, which can not only reduce the amount of noble metal, but also improve the reliability of the interface bonding performance; the sintering aid promotes particle diffusion / oxidation layer removal through catalysis or interface regulation; the carrier ensures the dispersibility of the raw materials and the process adaptability. The D1 (such as cobalt acetylacetonate) selected by the present application is a metal organic compound, which can be used as a “diffusion catalyst”, decomposed at the sintering temperature, and the released metal ions (Co 2+ , Cr 3+ ) are adsorbed on the surface of the metal particles, which reduces the surface diffusion activation energy and promotes the growth of the neck; at the same time, it can reduce the copper surface oxide layer (CuO→Cu), and enhance the interface bonding. D2 (such as cuprous iodide) is a sintering aid, which can reduce the sintering temperature of silver / copper, or inhibit copper oxidation (I - can be preferentially adsorbed on the surface of copper to block O2 contact). The complex sintering aid (D1+D2) defined in the present application can produce a synergistic effect, optimize diffusion and oxidation resistance, improve pressureless sintering activity, and inhibit copper oxidation.

[0013] Further, the sintering aid is 0.01-1 parts, and the carrier is 0.5-10 parts, based on 100 parts of the total mass of the fine silver particles, silver powder and nano-copper particles.

[0014] Further, the mass ratio of the fine silver particles, silver powder and nano-copper particles is 60:10:30.

[0015] The present application limits the raw material ratio range to ensure the sintering activity and stress balance of the “silver-copper” complex system under pressureless conditions (too high / low silver-copper ratio will lead to insufficient densification or excessive stress). The present application lays the foundation for pressureless sintering, realizes the densification interconnection of the copper-gold-silver heterogeneous interface at a low temperature of 200-250℃, and solves the problem of insufficient pressureless sintering activity in the prior art.

[0016] Further, the fine silver particles are mixed by components A1 and A2 in a mass ratio of 35:25;

[0017] The component A1 is a spherical silver particle with an average particle size of 300-500 nm;

[0018] The component A2 is a plate-shaped silver microparticle with an average particle size of 50-300 nm and a thickness of 10-200 nm.

[0019] The spherical particle (A1) selected by the application has good flowability, can fill the gaps between the plate-shaped particles, and optimizes the bulk density; the plate-shaped particle (A2) has a large specific surface area and a high edge activity, and a "lapped-diffusion" network is easily formed between the plate-shaped particles during sintering; the compounding of particles with different morphologies can reduce the packing defects caused by a single morphology and promote the improvement of the density of the sintered body. The limitation of parameters can improve the sintering densification degree of fine silver particles, reduce the porosity of the sintered body, and enhance the electrical conductivity and shear strength.

[0020] Further, the cumulative distribution of the nano-copper microparticles is 90% of the particle size of 50-300 nm.

[0021] The nano-copper with a particle size of 50-300 nm selected by the application has high surface energy (high proportion of surface atoms) and can realize densification through surface diffusion under no pressure; if the particle size is too small (<50 nm), the nano-copper is easily oxidized and agglomerated, and if the particle size is too large (>300 nm), the surface energy is insufficient and the nano-copper is difficult to diffuse and sinter under no pressure; the control of the 90% particle size ensures the uniform dispersion of the nano-copper and avoids sintering defects caused by local agglomeration. The limitation can balance the sintering activity and oxidation resistance of the nano-copper under no pressure, promote the diffusion and bonding of the silver-copper interface, and reduce the packaging cost (copper replaces part of silver).

[0022] Further, the silver powder is flaky silver powder with an average particle size of 1-10 μm.

[0023] The flaky structure limited by the application has a "bridging effect", and the flaky silver powder can act as a skeleton support to connect the nano-sized fine silver particles and nano-copper during the sintering process, thereby reducing the sintering shrinkage stress (avoiding the fracture of GaN chips due to stress) and relieving the volume shrinkage caused by excessive sintering of nano-particles; the particle size of 1-10 μm is larger than that of the fine silver particles, which can relieve the volume shrinkage caused by excessive sintering of nano-particles, and the high aspect ratio of the flaky morphology promotes the continuity of the metal bonding network. The limitation of the parameters can enhance the structural stability of the sintered body, reduce the thermal stress, and improve the adaptability to high aspect ratio chips.

[0024] Further, the carrier is a complex of butyl carbitol acetate, triethylene glycol, and (methyl) isobornyl acrylate or hydrogenated bisphenol F epoxy resin.

[0025] The second object of the application is to provide a preparation method of a pressureless sintering silver-copper compounding adhesive suitable for copper-gold-silver heterogeneous interface sintering interconnection, which comprises the following steps:

[0026] The fine silver particles, silver powder, nano-copper microparticles, sintering aids, and carrier are mixed to obtain a premix, which is ground to obtain an adhesive; and the adhesive is vacuum degassed to obtain the pressureless sintering silver-copper compounding adhesive.

[0027] The mixing step of the present application can ensure uniform contact of raw materials, laying a foundation for uniform diffusion of subsequent sintering; the role of grinding is to break up particle agglomerates (especially hard agglomeration of nano-copper and fine silver particles), and promote the dispersion of raw materials; vacuum debubbling can remove bubbles introduced during mixing (bubbles can cause voids in the sintered body, reducing strength). The limitation of the carrier of the present application can ensure uniform and bubble-free adhesive composition, providing a prerequisite for densification of subsequent sintering.

[0028] Further, the specific operation steps of the grinding include: using three-roll grinding dispersion, the initial over-roller gap is 60 μm, the over-roller gap is reduced after each grinding, and the grinding gap is 60 μm, 40 μm, 20 μm, 10 μm in turn, and each group of gap is dispersed for 2 times.

[0029] The present application realizes "step-by-step refinement" by gradually reducing the gap, breaks up large agglomerates at the initial 60 μm, and gradually disperses small agglomerates at 40 μm, 20 μm, and 10 μm, avoiding damage to the particle morphology caused by one-time high pressure; dispersing for 2 times for each group of gap ensures sufficient dispersion, so that fine silver particles, silver powder, and nano-copper are uniformly distributed in the carrier. This operation can improve the uniformity of raw material dispersion and reduce local defects of the sintered body.

[0030] Further, the specific operation steps of the vacuum debubbling include: debubbling for 1.5 minutes under the condition of a rotation speed of 1000 rpm and a pressure of 0.5 kPa.

[0031] The centrifugal force generated by the rotation speed of 1000 rpm of the present application, combined with the low pressure of 0.5 kPa, can efficiently expel bubbles in the glue (bubbles are the main source of voids after sintering, which will reduce the thermal / electrical conductivity); the debubbling time of 1.5 minutes is to balance efficiency and process stability (too short time and bubbles are not completely removed, too long time may cause carrier evaporation). Through this operation, bubbles in the glue can be completely removed, the porosity of the sintered body can be reduced, and the interface bonding reliability can be improved.

[0032] The third object of the present application is to provide an application of a pressureless sintering silver-copper compound adhesive suitable for copper-gold-silver heterogeneous interface sintering interconnection in semiconductor device bonding, which uses the pressureless sintering silver-copper compound adhesive suitable for copper-gold-silver heterogeneous interface sintering interconnection to bond semiconductor elements and element support components by pressureless sintering.

[0033] The present application is aimed at the "light, thin, hard and brittle" characteristics of GaN chips (unable to withstand pressure), and adopts a pressure-free process to avoid mechanical damage; the heterogeneous interface (chip end plated gold / silver, support component end pure copper) is adapted, and the stress and oxidation problems of the heterogeneous interface are solved through formula optimization. The pressure-free reliable interconnection of sensitive devices such as GaN in the copper-gold-silver heterogeneous interface is realized, and the application is expanded to the packaging scene of high-power semiconductors such as 5G base stations and new energy vehicles.

[0034] Compared with the prior art, the present application has the following advantages and technical effects:

[0035] 1. The present application realizes high-reliability sintering interconnection of large-size chips under pressure-free conditions for the first time through silver-copper complex and sintering aid cooperation.

[0036] 2. The present application can directly bond plated gold chips and pure copper substrates without pressure, and is expected to reduce packaging cost by more than 20%, providing key material support for the mass production of GaN radio frequency modules, high-power LEDs and other third-generation semiconductor devices. DETAILED DESCRIPTION

[0037] The various exemplary embodiments of the present application will now be described in detail, which should not be considered as limiting the present application, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present application.

[0038] It should be understood that the terms described in the present application are only for describing the specific embodiments, and are not used to limit the present application. In addition, for the numerical range in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or intermediate value within the range and any other stated value or intermediate value within the range is also included in the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application pertains. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of any conflict between the content of this specification and any incorporated document, the content of this specification shall prevail.

[0040] Various modifications and changes can be made to the specific implementation of the present application described in the specification without departing from the scope or spirit of the application, which will be apparent to those skilled in the art. Other implementations derived from the specification of the present application will be apparent to those skilled in the art. The specification and examples of the present application are only exemplary.

[0041] As used herein, the terms "comprise", "include", "have", "contain", and the like are open-ended terms, i.e., meaning "including but not limited to".

[0042] The present application provides a pressureless sintering silver-copper compound adhesive (paste composition) suitable for copper-gold-silver heterogeneous interface sintering interconnection, comprising the following raw materials: fine silver particles, silver powder, nano-copper particles, sintering aids and carriers.

[0043] Among them, taking the total mass of fine silver particles, silver powder and nano-copper particles as 100 parts, the sintering aid is 0.01-1 parts, and the carrier is 0.5-10 parts; as an example, in the following preferred embodiments of the present application, when the total mass of fine silver particles, silver powder and nano-copper particles is 100 parts, the sintering aid is 1 part, and the carrier is 10 parts.

[0044] In the following preferred embodiments of the present application, the mass ratio of the fine silver particles, silver powder and nano-copper particles is 60:10:30.

[0045] In the following preferred embodiments of the present application, the mass ratio of component A1 and component A2 is 35:25; wherein the component A1 is spherical silver particles with an average particle size of 300-500nm (such as 350nm); the component A2 is plate-shaped silver particles with an average particle size of 50-300nm (such as 150nm) and a thickness of 10-200nm (such as 50nm).

[0046] In some optional embodiments of the present application, the silver powder is flaky silver powder with an average particle size of 1-10μm (such as 2μm).

[0047] In some optional embodiments of the present application, the cumulative distribution 90% particle size of the nano-copper particles is 50-300nm.

[0048] In some optional embodiments of the present application, the sintering aid comprises one or both of component D1 and component D2; wherein the component D1 is one of cobalt (II) acetylacetonate, chromium acetylacetonate and chlorinated hematin; and the component D2 is one of cuprous iodide, neodecanoic acid and (diethylamino)difluorosulfonium tetrafluoroborate. As an example, in the following preferred embodiments of the present application, the component D1 is cobalt (II) acetylacetonate, chromium acetylacetonate or chlorinated hematin, and the component D2 is cuprous iodide, neodecanoic acid or (diethylamino)difluorosulfonium tetrafluoroborate; and the sintering aid is one of cobalt (II) acetylacetonate and cuprous iodide, chromium acetylacetonate and cuprous iodide, chlorinated hematin and (diethylamino)difluorosulfonium tetrafluoroborate, cobalt (II) acetylacetonate and neodecanoic acid, cobalt (II) acetylacetonate, chromium acetylacetonate, chlorinated hematin, neodecanoic acid, cuprous iodide and (diethylamino)difluorosulfonium tetrafluoroborate.

[0049] In some optional embodiments of the present application, the carrier is a complex of butyl carbitol acetate, triethylene glycol and isobornyl (meth)acrylate or hydrogenated bisphenol F epoxy resin; wherein when the resin is used as the carrier, an initiator and an accelerator need to be added, the initiator is dicumyl peroxide, and the accelerator is 1-hydroethyl-2-ethyl-4-methyl imidazole. As an example, in the following preferred embodiments of the present application, the carrier is a complex of isobornyl (meth)acrylate, butyl carbitol acetate and triethylene glycol, or a complex of hydrogenated bisphenol F epoxy resin, butyl carbitol acetate and triethylene glycol (i.e. a complex of the three).

[0050] The embodiments of the present application also provide a preparation method of a pressureless sintering silver-copper complex adhesive suitable for sintering interconnection of copper-gold-silver heterogeneous interfaces, comprising the following steps:

[0051] The fine silver particles, silver powder, nano-copper particles, sintering aid and carrier are mixed to obtain a premix, which is ground to obtain a glue; and the glue is vacuum defoamed to obtain the pressureless sintering silver-copper complex adhesive.

[0052] In some optional embodiments of the present application, the specific operation steps of the grinding include: three-roll grinding dispersion is adopted, the pass roller gap is initially 60 μm, the pass roller gap is reduced after each grinding, and the grinding gaps are 60 μm, 40 μm, 20 μm and 10 μm in sequence, and each group of gaps is dispersed for 2 times.

[0053] In some optional embodiments of the present application, the specific operation steps of the vacuum defoaming include: defoaming for 1.5 minutes under the condition that the rotation speed is 1000 rpm and the pressure is 0.5 kPa.

[0054] The application of the pressureless sintering silver-copper compound adhesive suitable for copper-gold-silver heterogeneous interface sintering interconnection in semiconductor device bonding is specifically: adopting the pressureless sintering silver-copper compound adhesive suitable for copper-gold-silver heterogeneous interface sintering interconnection to bond semiconductor elements and element support components through a pressureless sintering mode.

[0055] The "room temperature" in the present application refers to 20-30 DEG C, unless otherwise specified.

[0056] The "parts" in the present application refer to mass parts, unless otherwise specified.

[0057] The raw materials used in the following examples of the present application are all obtained by purchase in the market, and the specific details are as follows:

[0058] 1) fine silver particles: spherical silver microparticles (Hachisui Co., Ltd., trade name: N315, average particle size: 350 nm); plate-shaped silver microparticles (Tokuriki Co., Ltd., trade name: KM120, average particle size: 150 nm, thickness: 50 nm);

[0059] 2) silver powder: flaky silver powder (Tokuriki Co., Ltd., trade name: M13, average particle size: 2 μm);

[0060] 3) nanometer copper microparticles: spherical copper microparticles (Youyan Micro-nano New Material Co., Ltd., trade name: Cu-ND100, average particle size: 100 nm);

[0061] 4) sintering aids: cobalt (II) acetylacetonate (Shanghai Aladdin Bio-Chem Technology Co., Ltd., trade name: cobalt (II) acetylacetonate); chromium acetylacetonate (Shanghai Aladdin Bio-Chem Technology Co., Ltd., trade name: chromium acetylacetonate); chlorohemin (Shanghai Aladdin Bio-Chem Technology Co., Ltd., trade name: chlorohemin); neodecanoic acid, isomer mixture (Shanghai Aladdin Bio-Chem Technology Co., Ltd., trade name: neodecanoic acid, isomer mixture); cuprous iodide (Shanghai Aladdin Bio-Chem Technology Co., Ltd., trade name: cuprous iodide); (diethylamino) difluorosulfonium tetrafluoroborate (Shanghai Aladdin Bio-Chem Technology Co., Ltd., trade name: (diethylamino) difluorosulfonium tetrafluoroborate);

[0062] 5) Carrier: isobornyl (meth) acrylate (Shanghai Maikelin Biochemical Technology Co., Ltd., trade name: isobornyl (meth) acrylate); hydrogenated bisphenol F epoxy resin (Daiso Corporation, trade name: EPICLON® EXA-7020); butyl carbitol acetate (Shanghai Maikelin Biochemical Technology Co., Ltd., trade name: butyl carbitol acetate); triethylene glycol (Shanghai Maikelin Biochemical Technology Co., Ltd., trade name: triethylene glycol); thermosetting free radical polymerization initiator used in conjunction with the resin carrier: dicumyl peroxide (manufactured by Nippon Oil & Fats Corporation, trade name: Permil D; decomposition temperature: 126°C); thermosetting curing accelerator used in conjunction with the resin carrier: 1-hydroethyl-2-ethyl-4-methylimidazole (Shikoku Chemicals Corporation, trade name: 2E4MZ-CN).

[0063] The technical solutions of the present application are further illustrated by the following examples.

[0064] Example 1

[0065] A pressureless sintering silver-copper compounded adhesive (paste composition) comprises the following raw materials: 60 parts of fine silver particles (of which, N315 is 35 parts and KM120 is 25 parts), 10 parts of silver powder (M13), 30 parts of nano-copper particles (Cu-ND100), 1 part of sintering aid (of which, cobalt acetylacetonate is 0.5 part and cuprous iodide is 0.5 part), and 10 parts of carrier (of which, isobornyl (meth) acrylate is 5 parts, butyl carbitol acetate is 2.5 parts, and triethylene glycol is 2.5 parts), and 0.05 parts of initiator (Permil D).

[0066] A pressureless sintering silver-copper compounded adhesive preparation method, the steps are as follows:

[0067] 1) Preparation of carrier: mix isobornyl (meth) acrylate, butyl carbitol acetate, triethylene glycol, and initiator Permil D to obtain the carrier;

[0068] 2) Mix fine silver particles, silver powder, nano-copper particles, sintering aid, and carrier to obtain a premix, and disperse by three-roll grinding, with the initial roll gap being 60μm, and reducing the roll gap after each grinding, with the grinding gaps being 60μm, 40μm, 20μm, and 10μm, respectively, and dispersing for 2 passes for each group of gaps to obtain the adhesive;

[0069] 3) Defoam the adhesive under the conditions of a rotation speed of 1000rpm and a pressure of 0.5kPa for 1.5 minutes to obtain the pressureless sintering silver-copper compounded adhesive.

[0070] Example 2

[0071] A pressureless sintering silver copper compound adhesive, comprising the following raw materials: 60 parts of fine silver particles (of which, N315 is 35 parts, KM120 is 25 parts), 10 parts of silver powder (M13), 30 parts of nano copper particles (Cu-ND100), 1 part of sintering aid (of which, acetylacetone chromium 0.5 parts, cuprous iodide 0.5 parts) and 10 parts of carrier (of which, (methyl) isobornyl acrylate 5 parts, butyl carbitol acetate 2.5 parts, triethylene glycol 2.5 parts), 0.05 parts of initiator (Permil D).

[0072] A pressureless sintering silver copper compound adhesive preparation method, same as example 1.

[0073] Example 3

[0074] A pressureless sintering silver copper compound adhesive, comprising the following raw materials: 60 parts of fine silver particles (of which, N315 is 35 parts, KM120 is 25 parts), 10 parts of silver powder (M13), 30 parts of nano copper particles (Cu-ND100), 1 part of sintering aid (of which, chlorinated hematin 0.5 parts, (diethylamino) difluoro sulfonium tetrafluoroborate 0.5 parts) and 10 parts of carrier (of which, (methyl) isobornyl acrylate 5 parts, butyl carbitol acetate 2.5 parts, triethylene glycol 2.5 parts), 0.05 parts of initiator (Permil D).

[0075] A pressureless sintering silver copper compound adhesive preparation method, same as example 1.

[0076] Example 4

[0077] A pressureless sintering silver copper compound adhesive, comprising the following raw materials: 60 parts of fine silver particles (of which, N315 is 35 parts, KM120 is 25 parts), 10 parts of silver powder (M13), 30 parts of nano copper particles (Cu-ND100), 1 part of sintering aid (of which, acetylacetone cobalt 0.5 parts, neodecanoic acid 0.5 parts) and 10 parts of carrier (of which, (methyl) isobornyl acrylate 5 parts, butyl carbitol acetate 2.5 parts, triethylene glycol 2.5 parts), 0.05 parts of initiator (Permil D).

[0078] A pressureless sintering silver copper compound adhesive preparation method, same as example 1.

[0079] Example 5

[0080] A pressureless sintering silver copper compound adhesive, comprising the following raw materials: 60 parts of fine silver particles (of which, N315 is 35 parts, KM120 is 25 parts), 10 parts of silver powder (M13), 30 parts of nano copper particles (Cu-ND100), 1 part of sintering aid (of which, cobalt acetylacetone is 0.5 part, cuprous iodide is 0.5 part) and 10 parts of carrier (of which, EXA-7020 is 5 parts, butyl carbitol acetate is 2.5 parts, triethylene glycol is 2.5 parts), 0.05 parts of curing accelerator (2E4MZ-CN).

[0081] A pressureless sintering silver copper compound adhesive preparation method, the steps are as follows:

[0082] 1) Preparation of carrier: mix EXA-7020, butyl carbitol acetate, triethylene glycol, curing accelerator (2E4MZ-CN) uniformly to obtain the carrier;

[0083] 2) Same as example 1.

[0084] Example 6

[0085] A pressureless sintering silver copper compound adhesive, comprising the following raw materials: 60 parts of fine silver particles (of which, N315 is 35 parts, KM120 is 25 parts), 10 parts of silver powder (M13), 30 parts of nano copper particles (Cu-ND100), 1 part of sintering aid (of which, cobalt acetylacetone is 1 part) and 10 parts of carrier (of which, (methyl) isobornyl acrylate is 5 parts, butyl carbitol acetate is 2.5 parts, triethylene glycol is 2.5 parts), 0.05 parts of initiator (Permil D).

[0086] A pressureless sintering silver copper compound adhesive preparation method, same as example 1.

[0087] Example 7

[0088] A pressureless sintering silver copper compound adhesive, comprising the following raw materials: 60 parts of fine silver particles (of which, N315 is 35 parts, KM120 is 25 parts), 10 parts of silver powder (M13), 30 parts of nano copper particles (Cu-ND100), 1 part of sintering aid (of which, cobalt acetylacetone is 1 part) and 10 parts of carrier (of which, (methyl) isobornyl acrylate is 5 parts, butyl carbitol acetate is 2.5 parts, triethylene glycol is 2.5 parts), 0.05 parts of initiator (Permil D).

[0089] A pressureless sintering silver copper compound adhesive preparation method, same as example 1.

[0090] Example 8

[0091] A pressureless sintering silver copper compound adhesive comprises the following raw materials: 60 parts of fine silver particles (of which, N315 is 35 parts, KM120 is 25 parts), 10 parts of silver powder (M13), 30 parts of nano copper particles (Cu-ND100), 1 part of sintering aid (of which, chlorinated hematin is 1 part) and 10 parts of carrier (of which, isobornyl (meth) acrylate is 5 parts, butyl carbitol acetate is 2.5 parts, triethylene glycol is 2.5 parts), 0.05 parts of initiator (Permil D).

[0092] A pressureless sintering silver copper compound adhesive preparation method, same as example 1.

[0093] Example 9

[0094] A pressureless sintering silver copper compound adhesive comprises the following raw materials: 60 parts of fine silver particles (of which, N315 is 35 parts, KM120 is 25 parts), 10 parts of silver powder (M13), 30 parts of nano copper particles (Cu-ND100), 1 part of sintering aid (of which, neodecanoic acid is 1 part) and 10 parts of carrier (of which, isobornyl (meth) acrylate is 5 parts, butyl carbitol acetate is 2.5 parts, triethylene glycol is 2.5 parts), 0.05 parts of initiator (Permil D).

[0095] A pressureless sintering silver copper compound adhesive preparation method, same as example 1.

[0096] Example 10

[0097] A pressureless sintering silver copper compound adhesive comprises the following raw materials: 60 parts of fine silver particles (of which, N315 is 35 parts, KM120 is 25 parts), 10 parts of silver powder (M13), 30 parts of nano copper particles (Cu-ND100), 1 part of sintering aid (of which, cuprous iodide is 1 part) and 10 parts of carrier (of which, isobornyl (meth) acrylate is 5 parts, butyl carbitol acetate is 2.5 parts, triethylene glycol is 2.5 parts), 0.05 parts of initiator (Permil D).

[0098] A pressureless sintering silver copper compound adhesive preparation method, same as example 1.

[0099] Example 11

[0100] A pressureless sintering silver copper compound adhesive comprises the following raw materials: 60 parts of fine silver particles (of which, N315 is 35 parts, KM120 is 25 parts), 10 parts of silver powder (M13), 30 parts of nano copper particles (Cu-ND100), 1 part of sintering aid (of which, (diethylamino) difluoro sulfonium tetrafluoroborate is 1 part) and 10 parts of carrier (of which, isobornyl (meth) acrylate is 5 parts, butyl carbitol acetate is 2.5 parts, triethylene glycol is 2.5 parts), 0.05 parts of initiator (Permil D).

[0101] A pressureless sintering silver copper compound adhesive preparation method, same as example 1.

[0102] Example 12

[0103] A pressureless sintering silver copper compound adhesive, comprising the following raw materials: 60 parts of fine silver particles (of which, N315 is 35 parts, KM120 is 25 parts), 10 parts of silver powder (M13), 30 parts of nano copper particles (Cu-ND100), 1 part of sintering aid (of which, cobalt acetylacetone is 1 part) and 10 parts of carrier (of which, EXA-7020 is 5 parts, butyl carbitol acetate 2.5 parts, triethylene glycol 2.5 parts), 0.05 parts of curing accelerator (2E4MZ-CN).

[0104] A pressureless sintering silver copper compound adhesive preparation method, the steps are as follows:

[0105] 1) Preparation of carrier: mix (methyl) isobornyl acrylate, butyl carbitol acetate, triethylene glycol, curing accelerator (2E4MZ-CN) uniformly to obtain the carrier;

[0106] 2) Same as example 1.

[0107] Comparative example 1

[0108] A pressureless sintering silver copper compound adhesive, comprising the following raw materials: 60 parts of fine silver particles (of which, N315 is 35 parts, KM120 is 25 parts), 10 parts of silver powder (M13), 30 parts of nano copper particles (Cu-ND100) and 10 parts of carrier (of which, (methyl) isobornyl acrylate 5 parts, butyl carbitol acetate 2.5 parts, triethylene glycol 2.5 parts), 0.05 parts of initiator (Permil D).

[0109] A pressureless sintering silver copper compound adhesive preparation method, same as example 1.

[0110] Comparative example 2

[0111] A pressureless sintering silver copper compound adhesive, comprising the following raw materials: 30 parts of fine silver particles (of which, N315 is 15 parts, KM120 is 15 parts), 40 parts of silver powder (M13), 30 parts of nano copper particles (Cu-ND100), 1 part of sintering aid (of which, cobalt acetylacetone is 0.5 part, cuprous iodide is 0.5 part) and 10 parts of carrier (of which, (methyl) isobornyl acrylate 5 parts, butyl carbitol acetate 2.5 parts, triethylene glycol 2.5 parts), 0.05 parts of initiator (Permil D).

[0112] A pressureless sintering silver copper compound adhesive preparation method, same as example 1.

[0113] Comparative Example 3

[0114] A pressureless sintering silver-copper compounded adhesive comprises the following raw materials: 70 parts of fine silver particles (of which, N315 is 40 parts, KM120 is 30 parts), 30 parts of silver powder (M13), 1 part of sintering aid (of which, cobalt acetylacetonate is 0.5 part, cuprous iodide is 0.5 part) and 10 parts of carrier (of which, isobornyl (meth)acrylate is 5 parts, butyl carbitol acetate is 2.5 parts, triethylene glycol is 2.5 parts), 0.05 part of initiator (Permil D).

[0115] A pressureless sintering silver-copper compounded adhesive preparation method, same as Example 1.

[0116] Comparative Example 4

[0117] A pressureless sintering silver-copper compounded adhesive comprises the following raw materials: 30 parts of fine silver particles (of which, N315 is 15 parts, KM120 is 15 parts), 10 parts of silver powder (M13), 60 parts of nano-copper particles (Cu-ND100), 1 part of sintering aid (of which, cobalt acetylacetonate is 0.5 part, cuprous iodide is 0.5 part) and 10 parts of carrier (of which, isobornyl (meth)acrylate is 5 parts, butyl carbitol acetate is 2.5 parts, triethylene glycol is 2.5 parts), 0.05 part of initiator (Permil D).

[0118] A pressureless sintering silver-copper compounded adhesive preparation method, same as Example 1.

[0119] Comparative Example 5

[0120] A pressureless sintering silver-copper compounded adhesive comprises the following raw materials: 60 parts of fine silver particles (of which, N315 is 60 parts), 10 parts of silver powder (M13), 30 parts of nano-copper particles (Cu-ND100), 1 part of sintering aid (of which, cobalt acetylacetonate is 0.5 part, cuprous iodide is 0.5 part) and 10 parts of carrier (of which, isobornyl (meth)acrylate is 5 parts, butyl carbitol acetate is 2.5 parts, triethylene glycol is 2.5 parts), 0.05 part of initiator (Permil D).

[0121] A pressureless sintering silver-copper compounded adhesive preparation method, same as Example 1.

[0122] The performance of the pressureless sintering silver-copper compounded adhesive (paste composition) prepared in Examples 1-12 and Comparative Examples 1-5 is tested, and the testing method is as follows:

[0123] 1. Viscosity: The testing standard uses a Brookfield viscometer, rotor #51, rotation speed 5 rpm, temperature 25℃.

[0124] 2. Pot life: The number of days until the viscosity increases to 1.5 times or more the initial viscosity is measured when the paste composition is left in a constant temperature chamber at 25°C.

[0125] 3. Shear strength: A gold-plated 6 mm x 6 mm simulated die bonding surface is used, and a gold-backed die is mounted on a solid pure copper frame using the paste composition. After the test piece is sintered, the shear force is measured using a vertical electronic push-pull force tester at an ambient temperature of 25°C to obtain the shear strength.

[0126] 4. Thermal conductivity: The thermal conductivity of the sintered paste composition can be measured by the JIS R1611:1997 laser flash method. The paste composition is uniformly filled into a cylindrical mold with a diameter of 8 mm and a thickness of 0.5-1 mm, and sintered into a dense metal-like disc by a stepwise heating method. The heating and sintering conditions are: 25-80°C, 45 minutes, a heating rate of 7°C / minute; 80-140°C, 30 minutes, a heating rate of 7°C / minute; 140-250°C, 150 minutes, a heating rate of 7°C / minute.

[0127] 5. Volume resistivity: The conductive paste composition is applied to a glass substrate (thickness 1 mm) in a thickness of 200 μm by screen printing, and cured at 200°C for 60 minutes to obtain a test piece. The resistance of the cured paste composition is measured by the four-probe method.

[0128] 6. High-temperature baking resistance test: A gold-plated 6 mm x 6 mm simulated die bonding surface is used, and a gold-backed die is mounted on a solid pure copper frame using the paste composition. After the test piece is sintered, the shear force is measured using a vertical electronic push-pull force tester at an ambient temperature of 25°C to obtain the shear strength, by heat treatment at 250°C for 100 hours and 1000 hours.

[0129] 7. Cold-heat shock resistance test: A gold-plated 6 mm x 6 mm simulated die bonding surface is used, and a gold-backed die is mounted on a solid pure copper frame using the paste composition. After the test piece is sintered, it is pretreated, and then subjected to a cold-heat shock cycle test, and after completion, the number of internal cracks generated in the test piece is evaluated by observation with an ultrasonic microscope, with 10 pieces per group.

[0130] Pretreatment conditions: hygroscopic treatment at 85°C, 85% relative humidity for 168 hours; then reflow soldering treatment (260°C, 10 seconds, 3 times).

[0131] Cold-heat cycle conditions: one cycle is an operation of raising the temperature from -55°C to 150°C and then cooling to -55°C. 1000 cycles are performed.

[0132] 8. Internal defect detection: A back-gold chip having a 6 mm x 6 mm simulated chip bonding surface with gold plating deposition was mounted on a solid pure copper frame using the paste composition. After the test sample was completed sintering, the sample was observed for voids using a micro-focus X-ray inspection device (SMX-1000). A void ratio of 8% or more was evaluated as "not suitable". The solder bonding portion was observed from a direction perpendicular to the bonding surface using an X-ray transmission device, the void area and bonding area were calculated, and the void ratio was calculated according to the following formula.

[0133] Void ratio (%) = void area / (void area + bonding area) x 100%.

[0134] The test results are shown in Tables 1-3.

[0135] Table 1: Performance test results of the pressureless sintered silver-copper composite adhesive prepared in Examples 1-12 and Comparative Examples 1-5

[0136] Table 2: Performance test results of the pressureless sintered silver-copper composite adhesive prepared in Examples 1-12 and Comparative Examples 1-5

[0137]

[0138] Table 3: Performance test results of the pressureless sintered silver-copper composite adhesive prepared in Examples 1-12 and Comparative Examples 1-5

[0139]

[0140] The above, only for the preferred specific embodiments of the present application, but the scope of protection of the present application is not limited to this, any skilled in the art of the technical personnel in the technical range disclosed in the present application, can easily think of changes or replacement, should be covered in the scope of protection of the present application. Therefore, the scope of protection of the present application should be subject to the scope of protection of the claims.

Claims

1. A pressureless sintering silver-copper composite adhesive suitable for sintering and interconnecting copper-gold-silver heterojunction interfaces, characterized in that, The raw materials include: fine silver particles, silver powder, nano-copper particles, sintering aids, and carriers; The sintering aid includes one or both of component D1 and component D2; The component D1 is selected from one of cobalt acetylacetone, chromium acetylacetone, and heme chloride; The component D2 is selected from one of cuprous iodide, neodecanoic acid, and (diethylamino)difluorosulfonium tetrafluoroborate; The cumulative distribution of the copper nanoparticles has a particle size of 50-300 nm in 90% of cases; The mass ratio of the fine silver particles, silver powder and nano-copper particles is 60:10:30; The fine silver particles are composed of component A1 and component A2 mixed in a mass ratio of 35:25; wherein, component A1 is spherical silver microparticles with an average particle size of 300-500 nm; and component A2 is plate-shaped silver microparticles with an average particle size of 50-300 nm and a thickness of 10-200 nm. The silver powder is flake-shaped silver powder with an average particle size of 1-10 μm.

2. The pressureless sintering silver-copper composite adhesive for copper-gold-silver heterojunction interface sintering and interconnection according to claim 1, characterized in that, The carrier is butyl carbitol acetate, tetraethylene glycol trioxide and isobornyl (meth)acrylate or A composite of hydrogenated bisphenol F epoxy resin.

3. A method for preparing a pressureless sintering silver-copper composite adhesive as described in any one of claims 1-2, suitable for sintering and interconnecting copper-gold-silver heterojunction interfaces, characterized in that, Includes the following steps: Fine silver particles, silver powder, nano-copper particles, sintering aids and carriers are mixed to obtain a premix, which is then ground to obtain an adhesive; the adhesive is then degassed under vacuum to obtain a pressureless sintered silver-copper composite adhesive.

4. The method for preparing the pressureless sintering silver-copper composite adhesive suitable for copper-gold-silver heterojunction interface sintering and interconnection according to claim 3, characterized in that, The specific grinding operation steps include: using a three-roll mill for dispersion, with the roller gap starting at an initial 60μm, and reducing the roller gap after each round of grinding. The grinding gaps are successively 60μm, 40μm, 20μm, and 10μm, and each set of gaps is dispersed twice.

5. The method for preparing the pressureless sintering silver-copper composite adhesive suitable for copper-gold-silver heterojunction interface sintering and interconnection according to claim 3, characterized in that, The specific operation steps of the vacuum degassing include: degassing for 1.5 minutes at a rotation speed of 1000 rpm and a pressure of 0.5 kPa.

6. The application of a pressureless sintering silver-copper composite adhesive as described in any one of claims 1-2, suitable for copper-gold-silver heterojunction sintering interconnection, in semiconductor device bonding, characterized in that... The aforementioned pressureless sintering silver-copper composite adhesive, suitable for copper-gold-silver heterojunction interface sintering interconnection, is used to bond semiconductor devices and device support components through pressureless sintering.

Images