High-strength damp-heat-resistant adhesive suitable for adhering plated metal chip and preparation method of high-strength damp-heat-resistant adhesive

Abstract

The invention relates to an organic adhesive and a preparation method thereof, in particular to a high-strength damp-heat-resistant adhesive suitable for adhering a plated metal chip and a preparation method of the high-strength damp-heat-resistant adhesive. The problem that in the existing semiconductor field, the bonding reliability is poor under the high-humidity state and the high-humidity heat in the bonding process of an epoxy adhesive and precious metal such as a gold-plated base material is solved. The high-strength damp-heat-resistant adhesive is prepared from epoxy resin, chelated epoxy resin, polyimide precursor resin, a polyimide and chelated epoxy resin synergistic curing agent, a phthalate coupling agent, an inorganic filler and a solvent I; the preparation method comprises the following steps: 1, preparing polyimide precursor resin; 2, weighing; and 3, preparing the adhesive. The invention relates to a high-strength damp-heat-resistant adhesive suitable for bonding a plated metal chip and a preparation method thereof.

Description

Technical Field

[0001] The invention relates to an organic adhesive and a preparation method thereof. Background Art

[0002] With the rapid development of integrated circuit technology, the application scenarios of chips have gradually expanded from traditional consumer electronics to high-reliability fields such as automotive electronics, aerospace, marine equipment and industrial control. Complex working conditions have put forward higher requirements for chip packaging technology: on the one hand, the increase in chip size leads to a significant increase in thermal stress and mechanical stress inside the packaging structure; on the other hand, chips exposed to extreme conditions such as high temperature and high humidity (such as 85℃ / 85%RH) face severe challenges in the interface stability of the packaging material. For example, the penetration of water molecules in non-airtight packaging in a hot and humid environment will cause a mismatch in the material expansion coefficient, and the Cl in a salt spray environment will cause a mismatch in the material expansion coefficient. - Ions accelerate corrosion of metal leads, both of which can cause delamination failure between the chip and the substrate. Although existing packaging technologies have alleviated some of the mechanical stress issues through optimized structural designs (such as flip-chip soldering and 3D stacking), insufficient interfacial bonding between the chip surface metal coating and the adhesive material remains a core bottleneck leading to reduced reliability.

[0003] In order to improve electrical performance and corrosion resistance, precious metal processes such as gold (Au) and silver (Ag) plating are often used on chip surfaces. However, the chemical inertness of gold and silver coatings significantly reduces the interfacial bonding strength with organic adhesives. From the perspective of surface chemistry, the atomic d orbital electronic structure of precious metals makes their surface energy low (the surface energy of gold is about 1.5 J / m 2 , silver about 1.25J / m 2 ), it is difficult to form strong chemical bonds with polar groups in the adhesive (such as hydroxyl and amino groups in epoxy resin). In the actual bonding process, the interface bonding mainly relies on physical adsorption and mechanical interlocking, and its binding energy (usually less than 50kJ / mol) is much lower than that of covalent bonds (200-400kJ / mol). In a high humidity and heat environment, after water molecules diffuse through the adhesive layer to the interface, they will preferentially adsorb on the surface of the precious metal to form a water film, resulting in the attenuation of physical adsorption force (the interface bonding strength can drop by more than 40%); at the same time, water molecules react with uncured small molecules in the adhesive to hydrolyze, exacerbating interface debonding. Cl in salt spray environment - The ions will electrochemically corrode the silver coating (generating AgCl), destroying the integrity of the interface and forming microcrack expansion channels.

[0004] Currently, epoxy resin adhesives are commonly used for chip bonding. Their advantages lie in their good process compatibility and low cost, but their heat resistance and moisture-heat resistance make it difficult to meet the requirements of high-end applications. The glass transition temperature (Tg) of ordinary epoxy resins is usually below 150°C. At high temperatures (>175°C), chain segment relaxation occurs, resulting in a sharp drop in shear strength. After moisture-heat aging, the water absorption rate of the adhesive layer can reach 2% to 3%, causing volume expansion and generating internal stress. More critically, the interface between epoxy resin and precious metals is only bonded through van der Waals forces and hydrogen bonds, lacking a chemical bonding mechanism, and is prone to interfacial slip under thermal-mechanical coupling stress. To improve performance, researchers have proposed using polyimide (PI) to modify epoxy resins: by introducing PI's rigid aromatic heterocyclic structure, the Tg can be raised to above 200°C. At the same time, PI's low hygroscopicity (<1.5%) can effectively inhibit moisture-heat expansion. However, these modified materials still fail to address the fundamental bonding problem at precious metal interfaces. While the imide groups in the PI molecular chain improve bulk heat resistance, they remain chemically inactive with gold and silver surfaces. Experiments have shown that after aging the PI-modified epoxy for 500 hours at 85°C / 85% RH, the shear strength at the gold interface decreases by 30% to 40%, with typical interfacial delamination as the failure mode, demonstrating that the bonding still relies on weak physical interactions.

[0005] In summary, the core contradiction of current chip bonding technology is that the low surface activity of the precious metal coating makes it impossible for the adhesive to form a chemical bond, while the optimization of the bulk properties of traditional and modified epoxy adhesives has failed to fundamentally enhance the interfacial bonding strength. Existing solutions such as plasma treatment or silane coupling agent coating can temporarily increase the surface energy, but the treatment effect is easily affected by environmental aging (such as silane hydrolysis caused by humidity and heat). Adhesives based on metal chelation / complexation introduce carboxylic acid, phosphate or catechol groups to form coordination bonds with titanium / steel surface oxides, significantly improving interfacial bonding strength. However, there are no functional groups that can produce more chemical grafting on the metal surface. In addition, the high water absorption rate of the epoxy bulk has limited strength and reliability. Therefore, there is an urgent need to develop a new adhesive system with high heat resistance and low moisture absorption rate for the bonding of precious metal coatings on chip to achieve precise matching with the chip micro-nano structure and improve long-term humidity and heat reliability. Summary of the Invention

[0006] The present invention aims to solve the problem of poor bonding reliability under high humidity and high heat in the bonding of existing epoxy adhesives to precious metals such as gold-plated substrates in the semiconductor field, and further provide a high-strength, moisture- and heat-resistant adhesive suitable for bonding metal-plated chips and a preparation method thereof.

[0007] A high-strength, moisture-resistant adhesive suitable for bonding metal-plated chips is prepared from 100 parts by mass of an epoxy resin, 10 to 50 parts by mass of a chelated epoxy resin, 5 to 30 parts by mass of a polyimide precursor resin, 3 to 30 parts by mass of a synergistic curing agent of polyimide and chelated epoxy resin, 0.1 to 5 parts by mass of a phthalate coupling agent, 0.1 to 10 parts by mass of an inorganic filler, and 100 to 200 parts by mass of a solvent I.

[0008] The polyimide precursor resin is prepared from a tertiary amine, an aliphatic diamine, an aromatic dianhydride, and a solvent II; the molar ratio of the aliphatic diamine to the aromatic dianhydride is 1:(0.9-1.2); the molar ratio of the aliphatic diamine to the tertiary amine is 1:(0.05-2); and the mass ratio of the aliphatic diamine to the solvent II is 1:(1-10);

[0009] The repeating unit of polyamic acid in the polyimide precursor resin is:

[0010]

[0011] The R1 is

[0012] A method for preparing a high-strength, heat-resistant adhesive suitable for bonding metal-plated chips is carried out according to the following steps:

[0013] 1. Preparation of polyimide precursor resin:

[0014] Under nitrogen atmosphere, temperature of 40 ℃ to 48 ℃ and stirring conditions, solvent II, aliphatic diamine and tertiary amine are reacted for 1 hour to 5 hours to obtain a reaction system, then under nitrogen atmosphere, the reaction system is heated to 50 ℃ to 60 ℃, aromatic dianhydride is added to the reaction system three times, under nitrogen atmosphere, temperature of 50 ℃ to 60 ℃ and stirring conditions, stirring reaction for 3 hours to 5 hours, then under nitrogen atmosphere, the temperature is lowered to 25 ℃ to 30 ℃, and under nitrogen atmosphere and temperature of 25 ℃ to 30 ℃ conditions, The mixture was stirred at -10°C to -5°C in a nitrogen atmosphere for 4 to 6 hours, and then the mixture was allowed to stand for 3 hours to 5 hours at a temperature of 20°C to 25°C. The mixture was then allowed to stand for 8 hours to 12 hours at a temperature of 20°C to 25°C, and finally filtered, washed and dried to obtain a polyimide precursor resin.

[0015] The molar ratio of the fatty diamine to the aromatic dianhydride is 1:(0.9-1.2); the molar ratio of the fatty diamine to the tertiary amine is 1:(0.05-2); the mass ratio of the fatty diamine to the solvent II is 1:(1-10);

[0016] The repeating unit of polyamic acid in the polyimide precursor resin is:

[0017]

[0018] The R1 is

[0019] 2. Weighing:

[0020] Weigh 100 parts of epoxy resin, 10 to 50 parts of chelated epoxy resin, 5 to 30 parts of polyimide precursor resin, 3 to 30 parts of polyimide and chelated epoxy resin synergistic curing agent, 0.1 to 5 parts of phthalate coupling agent, 0.1 to 10 parts of inorganic filler and 100 to 200 parts of solvent I according to mass parts;

[0021] 3. Preparation of adhesive:

[0022] At a temperature of 80°C to 120°C and in air, the weighed epoxy resin, chelated epoxy resin, polyimide precursor resin and polyimide and chelated epoxy resin synergistic curing agent are stirred and heated for 2h to 5h, then cooled to 20°C to 25°C, and the weighed phthalate coupling agent, inorganic filler and solvent I are added, and stirred for 10min to 30min at a temperature of 20°C to 25°C and in air to obtain a high-strength, moisture-heat-resistant adhesive suitable for bonding metal-plated chips.

[0023] The beneficial effects of the present invention are:

[0024] Through molecular design and process innovation, this invention has achieved breakthrough progress in interfacial chemical bonding construction and resin network strengthening. Its beneficial effects and mechanism of action are detailed as follows:

[0025] When traditional epoxy resins are bonded to precious metal coatings through physical adsorption, the bonding performance is limited due to the lack of chemical bonding at the inert interface. The present invention achieves interface strengthening through a two-step dynamic mechanism: first, in the uncured stage of the epoxy resin, the tertiary amine component released by the polyimide precursor during the imidization process migrates to the metal surface through osmotic pressure and capillary action. The alkaline environment of the tertiary amine induces controlled etching on the surface of the precious metal, significantly increasing the surface hydroxyl density and forming an interface rich in active groups; then, the functional groups such as thiol and phosphonic acid in the chelated epoxy resin are bonded to the newly formed hydroxyl groups through multidentate coordination bonds to form a stable [metal-ligand] chelate structure. The bond energy of this chemical bonding is much higher than that of physical adsorption, which fundamentally avoids the formation of a weak interface binding layer.

[0026] Unlike traditional static surface modification methods using plasma treatment, this method utilizes the dynamic nature of the polyimide ring-closure reaction to achieve continuous interfacial activation and bonding reactions. The tertiary amine components continuously released during the imidization process continuously renew the interfacial environment during the curing process. Their alkaline etching and the curing reaction of the chelated epoxy form a dynamic equilibrium: on the one hand, the active state of the metal surface hydroxyl groups is maintained, avoiding the surface passivation observed after traditional treatments; on the other hand, the immediate formation of chelate bonds converts the newly generated active sites into permanent chemical bonds. This in-situ treatment mechanism effectively blocks the path of corrosion from environmental factors such as water vapor.

[0027] Through molecular structural design, a polyimide-epoxy interpenetrating network (IPN) was constructed using a synergistic curing agent containing a diamino group. Its mechanism of action includes the following: ① Primary amine groups react with carboxylic acid groups generated by decarboxylation of the polyimide precursor to form amide bonds, forming a primary crosslinked network during the pre-cure stage; ② Secondary amine groups undergo a ring-opening reaction with epoxy groups during the high-temperature cure stage, forming a three-dimensional crosslinked structure. This gradient cure mechanism bridges the rigid aromatic ring structure of the polyimide with the flexible epoxy segments through chemical bonds, forming a rigid-flexible composite network that significantly reduces cure shrinkage stress. Simultaneously, the steric hindrance of the polyimide segments inhibits the diffusion and migration of water molecules within the resin matrix.

[0028] At the microscopic level, the synergistic effect of the chelated epoxy and semi-aliphatic polyimide induces the formation of a hierarchical ordered structure: the planar, semi-rigid units of the polyimide serve as a skeletal support, while the cross-linked network of the chelated epoxy fills the interstices, and chemical bonds between the imide aliphatic segments and the epoxy resin form a through-link. This structure not only stabilizes the metal interface through the strong bonding action of the chelated bonds, but also reduces the free volume of the material through the interpenetrating network, forming a densified barrier. This structure effectively inhibits the permeation path of water molecules along the interface or within the resin, achieving dual protection of the interface and the bulk. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Figure 1 is a diagram of the bonding interface of a gold-plated ceramic chip in shear failure at room temperature after 1000 hours at 85°C / 85% RH. a is Example 1, b is Example 2, c is Example 4, d is Comparative Example 1, e is Comparative Example 2, and f is Comparative Example 4.

[0030] Figure 2 This is an infrared test result diagram of the high-strength, moisture-heat-resistant adhesive suitable for bonding metal-plated chips prepared in Example 1 after curing. DETAILED DESCRIPTION

[0031] Specific embodiment 1: This embodiment is a high-strength, heat-resistant adhesive suitable for bonding metal-plated chips, which is prepared by weight from 100 parts of epoxy resin, 10 to 50 parts of chelated epoxy resin, 5 to 30 parts of polyimide precursor resin, 3 to 30 parts of polyimide and chelated epoxy resin synergistic curing agent, 0.1 to 5 parts of phthalate coupling agent, 0.1 to 10 parts of inorganic filler and 100 to 200 parts of solvent I;

[0032] The polyimide precursor resin is prepared from a tertiary amine, an aliphatic diamine, an aromatic dianhydride, and a solvent II; the molar ratio of the aliphatic diamine to the aromatic dianhydride is 1:(0.9-1.2); the molar ratio of the aliphatic diamine to the tertiary amine is 1:(0.05-2); and the mass ratio of the aliphatic diamine to the solvent II is 1:(1-10);

[0033] The repeating unit of polyamic acid in the polyimide precursor resin is:

[0034]

[0035] The R1 is

[0036] The chelated epoxy resin described in this embodiment is a chelate compound that forms a multidentate coordination with the epoxy resin by utilizing metal chelation, such as the special epoxy resin EP-4080E, EP-4000 or EP-49-10P2 produced by ADEKA Japan.

[0037] The polyimide and chelated epoxy resin synergistic curing agent described in this specific embodiment is a diamino-containing curing agent that can simultaneously cure the epoxy resin and form a condensation bond with the polyimide.

[0038] The polyimide precursor resin described in this embodiment is prepared from aliphatic diamine, aromatic dianhydride and tertiary amine.

[0039] The beneficial effects of this specific embodiment are:

[0040] This specific embodiment has achieved breakthrough progress in interfacial chemical bonding construction and resin network strengthening through molecular design and process innovation. Its beneficial effects and mechanism of action are detailed as follows:

[0041] When traditional epoxy resins are bonded to precious metal coatings through physical adsorption, the bonding performance is limited due to the lack of chemical bonding at the inert interface. This specific embodiment achieves interface strengthening through a two-step dynamic mechanism: First, in the uncured stage of the epoxy resin, the tertiary amine component released by the polyimide precursor during the imidization process migrates to the metal surface through osmotic pressure and capillary action. The alkaline environment of the tertiary amine induces controlled etching of the precious metal surface, significantly increasing the surface hydroxyl density and forming an interface rich in active groups; subsequently, the functional groups such as thiol and phosphonic acid in the chelated epoxy resin are bonded to the newly formed hydroxyl groups through multidentate coordination bonds to form a stable [metal-ligand] chelate structure. The bond energy of this chemical bonding is much higher than that of physical adsorption, which fundamentally avoids the formation of a weak bonding layer at the interface.

[0042] Unlike traditional static surface modification methods using plasma treatment, this specific embodiment utilizes the dynamic nature of the polyimide ring-closure reaction to achieve continuous interfacial activation and bonding reactions. The tertiary amine components continuously released during the imidization process continuously renew the interfacial environment during the curing process. Their alkaline etching and the chelated epoxy curing reaction form a dynamic equilibrium: on the one hand, the active state of the metal surface hydroxyl groups is maintained, avoiding the surface passivation observed after traditional treatments; on the other hand, the immediate formation of chelate bonds converts the newly generated active sites into permanent chemical bonds. This in-situ treatment mechanism effectively blocks the path of interface erosion by environmental factors such as water vapor.

[0043] Through molecular structural design, a polyimide-epoxy interpenetrating network (IPN) was constructed using a synergistic curing agent containing a diamino group. Its mechanism of action includes the following: ① Primary amine groups react with carboxylic acid groups generated by decarboxylation of the polyimide precursor to form amide bonds, forming a primary crosslinked network during the pre-cure stage; ② Secondary amine groups undergo a ring-opening reaction with epoxy groups during the high-temperature cure stage, forming a three-dimensional crosslinked structure. This gradient cure mechanism bridges the rigid aromatic ring structure of the polyimide with the flexible epoxy segments through chemical bonds, forming a rigid-flexible composite network that significantly reduces cure shrinkage stress. Simultaneously, the steric hindrance of the polyimide segments inhibits the diffusion and migration of water molecules within the resin matrix.

[0044] At the microscopic level, the synergistic effect of the chelated epoxy and semi-aliphatic polyimide induces the formation of a hierarchical ordered structure: the planar, semi-rigid units of the polyimide serve as a skeletal support, while the cross-linked network of the chelated epoxy fills the interstices, and chemical bonds between the imide aliphatic segments and the epoxy resin form a through-link. This structure not only stabilizes the metal interface through the strong bonding action of the chelated bonds, but also reduces the free volume of the material through the interpenetrating network, forming a densified barrier. This structure effectively inhibits the permeation path of water molecules along the interface or within the resin, achieving dual protection of the interface and the bulk.

[0045] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the epoxy resin is bisphenol F epoxy resin, bisphenol A epoxy resin, bisphenol E epoxy resin, or naphthalene epoxy resin; and the chelated epoxy resin is one or a combination of EP-4080E epoxy resin, EP-4000 epoxy resin, and EP-49-10P2 epoxy resin. Other aspects are the same as specific embodiment 1.

[0046] Specific embodiment three: This embodiment differs from either specific embodiment one or two in that the polyimide and chelated epoxy resin synergistic curing agent is one or a combination of 4,4-diaminodiphenyl sulfone, 4,4-diaminodiphenylmethane, 4,4-diaminobenzophenone, 3,4-diaminodiphenyl sulfone, 3,4-diaminodiphenylmethane, and 3,3-diaminodiphenyl sulfone; and the phthalate coupling agent is one or a combination of isopropyl trioleyl titanate, isopropoxy tris(dodecylbenzenesulfonyloxy) titanate, and diisopropyl di(acetylacetonato) titanate. Other aspects are the same as specific embodiments one or two.

[0047] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the inorganic filler is one or a combination of aluminum oxide, silicon oxide and aluminum nitride. Other aspects are the same as specific embodiments 1 to 3.

[0048] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the tertiary amine is triethanolamine, picoline, quinoline or isoquinoline. Other aspects are the same as specific embodiments 1 to 4.

[0049] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that the aliphatic diamine is 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine or 1,9-nonanediamine. Other aspects are the same as specific embodiments 1 to 5.

[0050] Specific embodiment 7: This embodiment differs from Specific embodiments 1 to 6 in that the aromatic dianhydride is bisphenol A diether dianhydride. Other aspects are the same as Specific embodiments 1 to 6.

[0051] Specific embodiment 8: This embodiment differs from Specific embodiments 1 to 7 in that: Solvent I is N,N-dimethylformamide; Solvent II is a mixture of N,N-dimethylacetamide and water, with the mass ratio of N,N-dimethylacetamide to water being 10:(0.5-1). Other aspects are the same as Specific embodiments 1 to 7.

[0052] Specific embodiment 9: This embodiment is a method for preparing a high-strength, heat-resistant adhesive suitable for bonding metal-plated chips, which is carried out according to the following steps:

[0053] 1. Preparation of polyimide precursor resin:

[0054] Under nitrogen atmosphere, temperature of 40 ℃ to 48 ℃ and stirring conditions, solvent II, aliphatic diamine and tertiary amine are reacted for 1 hour to 5 hours to obtain a reaction system, then under nitrogen atmosphere, the reaction system is heated to 50 ℃ to 60 ℃, aromatic dianhydride is added to the reaction system three times, under nitrogen atmosphere, temperature of 50 ℃ to 60 ℃ and stirring conditions, stirring reaction for 3 hours to 5 hours, then under nitrogen atmosphere, the temperature is lowered to 25 ℃ to 30 ℃, and under nitrogen atmosphere and temperature of 25 ℃ to 30 ℃ conditions, The mixture was stirred at -10°C to -5°C in a nitrogen atmosphere for 4 to 6 hours, and then the mixture was allowed to stand for 3 hours to 5 hours at a temperature of 20°C to 25°C. The mixture was then allowed to stand for 8 hours to 12 hours at a temperature of 20°C to 25°C, and finally filtered, washed and dried to obtain a polyimide precursor resin.

[0055] The molar ratio of the fatty diamine to the aromatic dianhydride is 1:(0.9-1.2); the molar ratio of the fatty diamine to the tertiary amine is 1:(0.05-2); the mass ratio of the fatty diamine to the solvent II is 1:(1-10);

[0056] The repeating unit of polyamic acid in the polyimide precursor resin is:

[0057]

[0058] The R1 is

[0059] 2. Weighing:

[0060] Weigh 100 parts of epoxy resin, 10 to 50 parts of chelated epoxy resin, 5 to 30 parts of polyimide precursor resin, 3 to 30 parts of polyimide and chelated epoxy resin synergistic curing agent, 0.1 to 5 parts of phthalate coupling agent, 0.1 to 10 parts of inorganic filler and 100 to 200 parts of solvent I according to mass parts;

[0061] 3. Preparation of adhesive:

[0062] At a temperature of 80°C to 120°C and in air, the weighed epoxy resin, chelated epoxy resin, polyimide precursor resin and polyimide and chelated epoxy resin synergistic curing agent are stirred and heated for 2h to 5h, then cooled to 20°C to 25°C, and the weighed phthalate coupling agent, inorganic filler and solvent I are added, and stirred for 10min to 30min at a temperature of 20°C to 25°C and in air to obtain a high-strength, moisture-heat-resistant adhesive suitable for bonding metal-plated chips.

[0063] Specific embodiment 10: This embodiment differs from specific embodiment 9 in that: the stirring speed in step 1 is 200 rpm to 500 rpm; the volume ratio of the lower layer solution to ethanol in step 1 is 1:(2-4); the drying in step 1 is specifically carried out at a temperature of 105°C to 125°C for 24 hours to 48 hours; and the stirring speed in step 3 is 50 rpm to 150 rpm. Other aspects are the same as specific embodiment 9.

[0064] The following examples are used to verify the beneficial effects of the present invention:

[0065] Example 1:

[0066] A high-strength, heat-resistant adhesive suitable for bonding metal-plated chips, comprising, by weight, 100 parts of epoxy resin, 30 parts of chelated epoxy resin, 20 parts of polyimide precursor resin, 15 parts of a synergistic curing agent of polyimide and chelated epoxy resin, 1 part of a phthalate coupling agent, 5 parts of an inorganic filler, and 150 parts of solvent I.

[0067] The polyimide precursor resin is prepared from a tertiary amine, an aliphatic diamine, an aromatic dianhydride, and a solvent II; the molar ratio of the aliphatic diamine to the aromatic dianhydride is 1:1.05; the molar ratio of the aliphatic diamine to the tertiary amine is 1:0.5; and the mass ratio of the aliphatic diamine to the solvent II is 1:10;

[0068] The repeating unit of polyamic acid in the polyimide precursor resin is:

[0069]

[0070] The R1 is

[0071] The epoxy resin is bisphenol A epoxy resin E51; the chelated epoxy resin is EP-49-10P2 epoxy resin;

[0072] The polyimide and chelated epoxy resin synergistic curing agent is 4,4-diaminodiphenyl sulfone; and the phthalate coupling agent is isopropyl trioleate acyloxy titanate.

[0073] The inorganic filler is aluminum oxide.

[0074] The tertiary amine is picoline.

[0075] The fatty diamine is 1,6-hexanediamine.

[0076] The aromatic dianhydride is bisphenol A diether dianhydride.

[0077] The solvent I is N,N-dimethylformamide; the solvent II is a mixture of N,N-dimethylacetamide and water, and the mass ratio of N,N-dimethylacetamide to water is 10:1.

[0078] The method for preparing the high-strength, heat-resistant adhesive suitable for bonding metal-plated chips is carried out according to the following steps:

[0079] 1. Preparation of polyimide precursor resin:

[0080] Under a nitrogen atmosphere and a temperature of 45° C. with stirring, solvent II, aliphatic diamine and tertiary amine are reacted for 2 hours to obtain a reaction system, and then under a nitrogen atmosphere, the reaction system is heated to 55° C., aromatic dianhydride is added to the reaction system in three equal portions, and the reaction is stirred for 3 hours under a nitrogen atmosphere and a temperature of 55° C., and then the temperature is lowered to 25° C. under a nitrogen atmosphere, and the mixture is allowed to stand for 5 hours under a nitrogen atmosphere and a temperature of 25° C. After standing, the temperature is lowered to -10° C. under a nitrogen atmosphere, and the mixture is stirred for 4 hours under a nitrogen atmosphere and a temperature of -10° C. with stirring, and then the mixture is allowed to stand and the supernatant is removed, and the lower solution is added dropwise to ethanol, and the mixture is stirred for 3 hours under a temperature of 25° C. with stirring, and then the mixture is allowed to stand for 12 hours under a temperature of 25° C., and finally filtered, washed and dried at a temperature of 105° C. for 48 hours to obtain a polyimide precursor resin;

[0081] The volume ratio of the lower layer solution to ethanol is 1:2;

[0082] 2. Weighing:

[0083] Weigh 100 parts of epoxy resin, 30 parts of chelated epoxy resin, 20 parts of polyimide precursor resin, 15 parts of polyimide and chelated epoxy resin synergistic curing agent, 1 part of phthalate coupling agent, 5 parts of inorganic filler and 150 parts of solvent I according to mass parts;

[0084] 3. Preparation of adhesive:

[0085] At a temperature of 80°C, stirring and in the presence of air, the weighed epoxy resin, chelated epoxy resin, polyimide precursor resin, polyimide and chelated epoxy resin synergistic curing agent were stirred and heated for 5 hours, then cooled to 25°C, and the weighed phthalate coupling agent, inorganic filler and solvent I were added, and stirred at a temperature of 25°C, stirring and in the presence of air for 30 minutes to obtain a high-strength, moisture-heat-resistant adhesive suitable for bonding metal-plated chips.

[0086] The stirring speed in step 1 is 500 rpm; the stirring speed in step 3 is 150 rpm.

[0087] Embodiment 2: present embodiment is different from embodiment 1 in that: the umber of chelated epoxy resin is 20 parts.Other is identical with embodiment 1.

[0088] Example 3: This example differs from Example 1 in that the aliphatic diamine is 1,7-heptanediamine; and the repeating unit of the polyamic acid in the polyimide precursor resin is:

[0089]

[0090] The R1 is The rest is the same as Example 1.

[0091] Example 4: This example differs from Example 1 in that the tertiary amine is isoquinoline. Other aspects are the same as Example 1.

[0092] Example 5: This example differs from Example 1 in that the amount of the polyimide precursor resin is 10 parts. Other aspects are the same as Example 1.

[0093] Example 6: This example differs from Example 1 in that the amount of the polyimide precursor resin is 30 parts. Other aspects are the same as Example 1.

[0094] Example 7: This example differs from Example 1 in that the molar ratio of the fatty diamine to the tertiary amine is 1:0.2. Other aspects are the same as Example 1.

[0095] Comparative Example 1: This comparative example differs from Example 1 in that the chelated epoxy resin is omitted. Other aspects are the same as those of Example 1.

[0096] Comparative Example 2: This comparative example differs from Example 1 in that the polyimide precursor resin is omitted. Other aspects are the same as Example 1.

[0097] Comparative Example 3: This comparative example differs from Example 1 in that the synergistic curing agent for the polyimide and chelated epoxy resin is phenylimidazole. Other aspects are the same as Example 1.

[0098] Comparative Example 4: This comparative example differs from Example 1 in that the amount of the chelated epoxy resin is 5 parts and the amount of the polyimide precursor resin is 3 parts. Other aspects are the same as Example 1.

[0099] Table 1 Comparison of process parameters of Examples 1 to 7 and Comparative Examples 1 to 4

[0100]

[0101]

[0102] The adhesives prepared in Examples 1 to 7 and Comparative Examples 1 to 4 were tested for water absorption and boiling water absorption as follows:

[0103] 1. Water absorption rate: Evenly fill the adhesive into a silicone rubber mold with an inner dimension of 10 cm in length and width and 2 cm in depth. The thickness of the adhesive layer should be more than 3 mm. After heating at a temperature of 180℃±5℃ for 3 hours, take out the cured resin block and trim it according to the plate size specified in GB / T1034-2008 Plastics. Determination of water absorption. Determine the water absorption rate according to the provisions of the standard.

[0104] 2. Boiling water absorption rate: Evenly fill the adhesive into a silicone rubber mold with an inner dimension of 10 cm in length and width and 2 cm in depth, with a thickness of more than 3 mm. Heat it at 180℃±5℃ for 3 hours, remove the cured resin block, trim it according to the board size specified in GB / T 1034-2008 Plastics - Determination of water absorption, boil it in boiling water for 8 hours, quickly remove it and allow it to dry on the surface, and measure the water absorption rate according to the provisions of the standard.

[0105] The adhesives prepared in Examples 1 to 7 and Comparative Examples 1 to 4 were placed between chips for bonding. The chips were gold-plated ceramic (alumina), silver-plated ceramic (alumina), gold-plated silicon wafers, or gold-plated copper. The chips were bonded together using the same material. The curing process was as follows: first, the chip on one side after dispensing was dried at 80° C. for 2 hours. Then, the chip on the other side was placed on top of the adhesive and heated at 180° C. and 0.2 MPa for 3 hours to obtain bonded chips. Various performance tests were performed on the chips. The test conditions were in accordance with the following standards (methods):

[0106] 1. Shear strength: The shear strength of bonded chips is measured according to GJB548C-2021. The room temperature shear strength after damp heat aging is as follows: 85°C / 85% RH is to test the test body under the conditions of the environment set to 85°C and 85% humidity, and the aging time is 168h, 500h, and 1000h respectively; 71°C / 95% RH500h is to test the room temperature shear strength after aging for 500h at the set temperature of 71°C and 95% humidity.

[0107] 2. The bonding effect of the bonding chip is visually inspected to observe the damaged or detached surface. No residual glue indicates interface debonding, while residual glue indicates adhesive layer damage. Adhesive failure indicates detachment.

[0108] Table 2

[0109]

[0110]

[0111] Figure 1 Figure 3 is a diagram of the bonding interface of the gold-plated ceramic room temperature chip in shear failure state after 1000h at 85℃ / 85%RH, a is Example 1, b is Example 2, c is Example 4, d is Comparative Example 1, e is Comparative Example 2, and f is Comparative Example 4; it can be seen from the figure that the bonding interface of the embodiment is the bond layer destruction, and the bonding interface of the comparative example is the interface debonding.

[0112] The high-strength, heat-resistant adhesive suitable for bonding metal-plated chips prepared in Example 1 was cured. Specifically, the adhesive was evenly filled into a silicone rubber mold with an inner dimension of 10 cm in length and width and a depth of 2 cm. The adhesive layer thickness was greater than 3 mm. The mold was heated at a temperature of 180°C ± 5°C for 3 hours. The cured resin block was taken out and the surface of the resin block was polished smooth using 600-1000 mesh sandpaper before infrared testing. The test method was in accordance with GB / T6040-2019 General Rules for Infrared Spectroscopy Analysis Methods, and the test mode was ATR mode. Figure 2 This is the infrared test result of the high-strength, heat-resistant adhesive suitable for bonding metal-plated chips prepared in Example 1 after curing; as can be seen from the figure, 1173cm -1 There is a strong aliphatic ether bond COC stretching vibration absorption peak at 1493cm -1 and 1597cm -1 There are strong symmetrical stretching absorption peaks of C=C double bonds at two positions, 1704 cm -1 and 1771cm -1 The two positions are the symmetrical stretching and asymmetrical stretching absorption peaks of the C=O double bond, 3490 cm -1There is a broad and obvious OH stretching vibration absorption peak. In summary, it is proved that Example 1 contains polyimide resin and epoxy resin and is completely cured.

Claims

1. A high-strength, heat-resistant adhesive suitable for bonding metal-plated chips, characterized in that The invention is prepared from 100 parts of epoxy resin, 10 to 50 parts of chelated epoxy resin, 5 to 30 parts of polyimide precursor resin, 3 to 30 parts of polyimide and chelated epoxy resin synergistic curing agent, 0.1 to 5 parts of phthalate coupling agent, 0.1 to 10 parts of inorganic filler and 100 to 200 parts of solvent I in parts by mass. The polyimide precursor resin is prepared from a tertiary amine, an aliphatic diamine, an aromatic dianhydride, and a solvent II; the molar ratio of the aliphatic diamine to the aromatic dianhydride is 1:(0.9-1.2); the molar ratio of the aliphatic diamine to the tertiary amine is 1:(0.05-2); and the mass ratio of the aliphatic diamine to the solvent II is 1:(1-10); The repeating unit of polyamic acid in the polyimide precursor resin is: The R1 is 2. A high-strength, heat-resistant adhesive suitable for bonding metal-plated chips according to claim 1, characterized in that The epoxy resin is bisphenol F epoxy resin, bisphenol A epoxy resin, bisphenol E epoxy resin or naphthalene ring epoxy resin; the chelated epoxy resin is one of epoxy resin EP-4080E epoxy resin, EP-4000 epoxy resin and EP-49-10P2 epoxy resin or a combination of several thereof.

3. The high-strength, heat-resistant adhesive suitable for bonding metal-plated chips according to claim 1, characterized in that The polyimide and chelated epoxy resin synergistic curing agent is one of 4,4-diaminodiphenyl sulfone, 4,4-diaminodiphenylmethane, 4,4-diaminobenzophenone, 3,4-diaminodiphenyl sulfone, 3,4-diaminodiphenylmethane and 3,3-diaminodiphenyl sulfone, or a combination of several thereof; the phthalate coupling agent is one of isopropyl trioleyloxy titanate, isopropoxy tris(dodecylbenzenesulfonyloxy) titanate and diisopropyl di(acetylacetonate) titanate, or a combination of several thereof.

4. The high-strength, heat-resistant adhesive suitable for bonding metal-plated chips according to claim 1, characterized in that The inorganic filler is one of aluminum oxide, silicon oxide and aluminum nitride or a combination of several of them.

5. The high-strength, heat-resistant adhesive suitable for bonding metal-plated chips according to claim 1, characterized in that The tertiary amine is triethanolamine, picoline, quinoline or isoquinoline.

6. The high-strength, heat-resistant adhesive suitable for bonding metal-plated chips according to claim 1, characterized in that The fatty diamine is 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine or 1,9-nonanediamine.

7. The high-strength, heat-resistant adhesive suitable for bonding metal-plated chips according to claim 1, characterized in that The aromatic dianhydride is bisphenol A diether dianhydride.

8. The high-strength, heat-resistant adhesive suitable for bonding metal-plated chips according to claim 1, characterized in that The solvent I is N,N-dimethylformamide; the solvent II is a mixture of N,N-dimethylacetamide and water, and the mass ratio of N,N-dimethylacetamide to water is 10:(0.5-1).

9. The method for preparing a high-strength, heat-resistant adhesive suitable for bonding metal-plated chips according to claim 1, characterized in that It is carried out in the following steps:

1. Preparation of polyimide precursor resin: Under nitrogen atmosphere, temperature of 40 ℃ to 48 ℃ and stirring conditions, solvent II, aliphatic diamine and tertiary amine are reacted for 1 hour to 5 hours to obtain a reaction system, then under nitrogen atmosphere, the reaction system is heated to 50 ℃ to 60 ℃, aromatic dianhydride is added to the reaction system three times, under nitrogen atmosphere, temperature of 50 ℃ to 60 ℃ and stirring conditions, stirring reaction for 3 hours to 5 hours, then under nitrogen atmosphere, the temperature is lowered to 25 ℃ to 30 ℃, and under nitrogen atmosphere and temperature of 25 ℃ to 30 ℃ conditions, The mixture was stirred at -10°C to -5°C in a nitrogen atmosphere for 4 to 6 hours, and then the mixture was allowed to stand for 3 hours to 5 hours at a temperature of 20°C to 25°C. The mixture was then allowed to stand for 8 hours to 12 hours at a temperature of 20°C to 25°C, and finally filtered, washed and dried to obtain a polyimide precursor resin. The molar ratio of the fatty diamine to the aromatic dianhydride is 1:(0.9-1.2); the molar ratio of the fatty diamine to the tertiary amine is 1:(0.05-2); the mass ratio of the fatty diamine to the solvent II is 1:(1-10); The repeating unit of polyamic acid in the polyimide precursor resin is: The R1 is 2. Weighing: Weigh 100 parts of epoxy resin, 10 to 50 parts of chelated epoxy resin, 5 to 30 parts of polyimide precursor resin, 3 to 30 parts of polyimide and chelated epoxy resin synergistic curing agent, 0.1 to 5 parts of phthalate coupling agent, 0.1 to 10 parts of inorganic filler and 100 to 200 parts of solvent I according to mass parts; 3. Preparation of adhesive: At a temperature of 80°C to 120°C and in air, the weighed epoxy resin, chelated epoxy resin, polyimide precursor resin and polyimide and chelated epoxy resin synergistic curing agent are stirred and heated for 2h to 5h, then cooled to 20°C to 25°C, and the weighed phthalate coupling agent, inorganic filler and solvent I are added, and stirred for 10min to 30min at a temperature of 20°C to 25°C and in air to obtain a high-strength, moisture-heat-resistant adhesive suitable for bonding metal-plated chips.

10. The method for preparing a high-strength, heat-resistant adhesive suitable for bonding metal-plated chips according to claim 9, characterized in that The stirring speed described in step one is 200rpm~500rpm; the volume ratio of the lower layer solution to ethanol described in step one is 1:(2~4); the drying described in step one is specifically at a temperature of 105℃~125℃ for 24h~48h; the stirring speed described in step three is 50rpm~150rpm.

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