CN117586741A - High Wen Qingsuan-resistant ester conductive adhesive and preparation method thereof - Google Patents

Abstract

In order to overcome the problem of weak conductivity of the traditional cyanate ester conductive adhesive, the invention provides a high Wen Qingsuan ester conductive adhesive and a preparation method thereof, wherein the high temperature resistant cyanate ester conductive adhesive comprises a cyanate ester mixture, a first catalyst and a metal filler, the cyanate ester mixture comprises bisphenol E cyanate ester and a modified cyanate ester prepolymer, and the modified cyanate ester prepolymer is an aminophenol triglycidyl ether modified phenolic cyanate ester prepolymer; according to the invention, the modified cyanate ester prepolymer is cured under the medium temperature condition and still has excellent conductive performance under the precondition of ensuring high temperature resistance, low moisture absorption, high adhesion and the like; meanwhile, the adhesive has low viscosity and good adhesion performance to substrates such as chips, metals and the like; the glass has high Tg and overcomes the problem of low-temperature crystallization; the modified coordination of the aminophenol triglycidyl ether and the phenolic cyanate is beneficial to maintaining the high-temperature resistance of bisphenol E cyanate and improving the conductivity.

Description

High Wen Qingsuan-resistant ester conductive adhesive and preparation method thereof

Technical Field

The invention relates to the technical field of microelectronic packaging, in particular to a high Wen Qingsuan ester resistant conductive adhesive and a preparation method thereof.

Background

With the development of communication technology and various terminal devices, the semiconductor integrated circuit packaging industry has been rapidly developed, and the chip requirements have been rapidly increased, and meanwhile, the requirements for chip packaging have been increasingly diversified and challenging.

The connection of the chip to the substrate sometimes requires both mechanical bonding and electrical communication. The conductive adhesive is an indispensable packaging adhesive material, and has the performance requirements of high adhesive strength, high electric conduction and heat conduction, low stress, low moisture absorption, high temperature resistance, high reliability and the like. And the requirements for the conductive adhesive are more severe under the extremely high-temperature environment (the temperature is more than 200 ℃).

The composite conductive polymer material is a composite material with certain conductive performance, which is prepared by taking an insulating organic polymer material as a matrix and uniformly dispersing, compounding, laminating, compounding or forming a surface conductive film with other conductive substances.

The conductivity of the polymer conductive composite does not simply increase with increasing conductive additive content. When the volume fraction of the conductive filler is smaller than the critical volume fraction, the conductivity of the composite material is the same as that of the matrix, and is not improved along with the increase of the content of the conductive filler; when the volume fraction is near the critical volume fraction, the conductivity of the composite material increases sharply with the increase of the filler volume fraction, and can be generally improved by about 10 orders of magnitude; when the volume fraction of the conductive filler is larger than the critical volume fraction, the conductivity slowly increases with the increase of the content and gradually tends to stabilize. The change of the conductivity of the composite material is characterized by a typical percolation (percolion) phenomenon, and the critical volume fraction Vc of the filler material is a percolation valve.

Too much addition of the conductive filler affects other properties such as adhesion properties, rheological properties, etc.

The curing process of the prepared conductive adhesive can influence the final conductivity, firstly the dielectric property of the polymer matrix; and secondly, the volume shrinkage is cured, and the shrinkage is beneficial to improving the content of the conductive filler, so that the conductivity is improved.

The current conductive fillers commonly used often employ cyanate esters containing two or more cyanate ester functional groups (-OCN), which possess low relative dielectric constants (g: 2.5-3.5), low dielectric losses (tan 8: 3.0x10) ³ ～8.0×10 ³ ) Low moisture absorption rate<1.5 percent of high decomposition temperature>400 ℃ and extremely low curing shrinkage, and the ultrahigh Tg and low moisture absorption rate make the chip packaging structure have the advantages of high temperature resistance and high reliability.

However, the cyanate ester conductive adhesive has low dielectric property and extremely low curing shrinkage, so that the conductive property of the conductive adhesive is weaker than that of the epoxy conductive adhesive with the same conductive filler, and the curing resistance value is extremely high at the recommended curing temperature, so that the application of the epoxy conductive adhesive is limited. In the current practical application, in order to improve the conductivity, the following measures can be taken: firstly, curing at an ultra-high temperature (such as 300 ℃) to achieve the purpose of volume shrinkage through high-temperature volatilization, wherein the ultra-high temperature curing has higher requirements on the temperature resistance of the bonded elements, so that the application is limited; secondly, the content of the conductive filler is further improved, but the adhesive property is sacrificed and the viscosity is increased; thirdly, the low-temperature curing conductive advantage of the epoxy resin conductive adhesive is exerted by compounding the epoxy resin, but Tg and temperature resistance are seriously reduced. Therefore, how to overcome the above-mentioned technical problems and drawbacks becomes an important problem to be solved.

Disclosure of Invention

Aiming at the problems that the cyanate ester conductive adhesive has low dielectric property and extremely low curing shrinkage and the conductive adhesive has weak conductive property, the invention provides the high Wen Qingsuan ester resistant conductive adhesive and the preparation method thereof.

The technical scheme adopted by the invention for solving the technical problems is as follows:

the invention provides a high Wen Qingsuan-resistant conductive adhesive, which comprises the following components in parts by weight: the phenolic cyanate modified phenolic cyanate ester comprises a cyanate ester mixture, a first catalyst and a metal filler, wherein the cyanate ester mixture comprises bisphenol E cyanate ester and a modified cyanate ester prepolymer, and the modified cyanate ester prepolymer is an aminophenol triglycidyl ether modified phenolic cyanate ester prepolymer.

Optionally, the cyanate ester mixture is 10-25 parts by weight, the first catalyst is 0.01-2 parts by weight, and the metal filler is 75-90 parts by weight.

Optionally, the first catalyst comprises one or more of an organotin compound, a metal acetylacetonate complex, a metal naphthenate complex, a metal isooctanoate complex, and phenol.

Optionally, the metal filler is silver powder.

Optionally, the cyanate ester mixture further comprises a thixotropic agent, wherein the thixotropic agent comprises one or more of fumed silica, precipitated silica, kaolin and organic bentonite, the bisphenol E cyanate ester is 50-90 parts by weight, the modified cyanate ester prepolymer is 10-50 parts by weight, and the thixotropic agent is 0-10 parts by weight.

Optionally, the structural formula of the bisphenol E cyanate is shown as formula I:

optionally, the modified cyanate ester prepolymer is obtained by reacting phenolic cyanate ester with aminophenol triglycidyl ether, wherein the phenolic cyanate ester is 30-70 parts by weight, and the aminophenol triglycidyl ether is 30-70 parts by weight;

wherein the chemical formula of the aminophenol triglycidyl ether is shown as formula II and/or formula III:

wherein, the structural formula of R is shown as formula IV:

optionally, the preparation method of the modified cyanate ester prepolymer comprises the following steps:

adding phenolic cyanate into a reaction container, and heating to 80-100 ℃ for dissolution;

adding aminophenol triglycidyl ether, stirring and mixing;

and (3) dropwise adding a second catalyst into the reaction container, stirring for 1-3 hours, heating the solution in the reaction container to 150-160 ℃, continuing to react for 3-5 hours, stopping the reaction when the viscosity reaches 1800-2500cps@80 ℃, and pouring the solution into the container after cooling.

Optionally, the second catalyst comprises styrenated phenol.

The invention also provides a preparation method of the high Wen Qingsuan ester resistant conductive adhesive, which comprises the following steps:

preparation of cyanate ester mixture:

adding bisphenol E cyanate and modified cyanate prepolymer into a reaction kettle, stirring and mixing for 1.5-2.5 hours at a high temperature of 90-110 ℃ under vacuum, cooling to room temperature, adding thixotropic agent, stirring and mixing for 0.5-2 hours under vacuum;

preparation of the catalyst solution:

adding a first catalyst and styrenated phenol into a reaction kettle, stirring and dissolving for 1.5-2.5 hours under the oil bath condition of 70-90 ℃, cooling to room temperature, filtering, sealing and storing;

preparation of conductive adhesive:

adding the cyanate ester mixture, the catalyst solution and the metal filler into a reaction kettle according to the mass ratio, controlling the temperature of the materials to be 15-25 ℃, defoaming, stirring and mixing for 0.5-2h under vacuum, filtering, and filling to obtain a finished product.

According to the high-temperature-resistant cyanate ester conductive adhesive and the preparation method thereof, the high-temperature-resistant cyanate ester conductive adhesive is cured under the recommended moderate-temperature (150-180 ℃) condition under the precondition of ensuring high temperature resistance, low moisture absorption, high adhesion and the like by modifying the related modified cyanate ester prepolymer structure and the dielectric property thereof; the modified cyanate ester prepolymer is used for partially replacing the traditional bisphenol E cyanate ester, so that the adhesive has low viscosity and good adhesion performance to substrates such as chips, metals and the like; meanwhile, the glass transition temperature (Tg) is high, and the problem of low-temperature crystallization is solved; the modified coordination of the aminophenol triglycidyl ether and the phenolic cyanate is beneficial to maintaining the high-temperature resistance of the bisphenol E cyanate and increasing the conductivity of the conductive composite material.

Detailed Description

In order to make the technical problems, technical schemes and beneficial effects solved by the invention more clear, the invention is further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

The test methods used in the following examples are conventional methods unless otherwise specified; the materials, reagents and the like used, unless otherwise specified, are those commercially available.

In one embodiment, the invention provides a high Wen Qingsuan ester resistant conductive adhesive, which comprises the following components: the phenolic cyanate modified phenolic cyanate ester comprises a cyanate ester mixture, a first catalyst and a metal filler, wherein the cyanate ester mixture comprises bisphenol E cyanate ester and a modified cyanate ester prepolymer, and the modified cyanate ester prepolymer is an aminophenol triglycidyl ether modified phenolic cyanate ester prepolymer.

Specifically, cyanate esters have reactive cyanate groups (-O-C≡N) and form highly crosslinked three-dimensional network polymers of triazine ring and ether linkage structures in the presence of suitable catalysts (e.g., water, metal ions, etc.) and/or under heating. The following is shown:

wherein R1 is-CH ₂ -、

R2 is H, CH ₃ Etc.;

r3 is a general cyanate ester structure, and the structure is shown as formula V:

the bisphenol E cyanate is supercooled liquid at normal temperature, is easy to crystallize at low temperature, and has a structure shown in formula I:

the bisphenol E cyanate is available on the market under the trade mark such as Primaset LECy (Dragon sand), aroCy L-10 (Hensman), P-201 (Mitsubishi gas), C09MO (Tianqi of Yangzhou), etc.

The cyanate ester prepolymer is formed by polymerizing cyanate ester monomers, and has more excellent processing performance.

The invention ensures that the modified relative cyanate ester structure and the dielectric property thereof have excellent conductivity after being solidified under the recommended medium temperature (150-180 ℃) condition under the precondition of high temperature resistance, low moisture absorption, high adhesion and the like.

The modified cyanate ester prepolymer is used for partially replacing the traditional bisphenol E cyanate ester, so that the adhesive has low viscosity and good adhesion performance to substrates such as chips, metals and the like; meanwhile, the glass transition temperature (Tg) is high, and the problem of low-temperature crystallization is solved; the modified coordination of the aminophenol triglycidyl ether and the phenolic cyanate is beneficial to maintaining the high-temperature resistance of the bisphenol E cyanate and increasing the conductivity of the conductive composite material.

In one embodiment, the cyanate ester mixture is 10-25 parts by weight, the catalyst is 0.01-2 parts by weight, and the metal filler is 75-90 parts by weight.

In a preferred embodiment, the cyanate ester mixture is 15-20 parts.

Specifically, the cyanate ester mixture is 10 parts, 15 parts, 17 parts, 20 parts or 25 parts.

In a preferred embodiment, the catalyst is 0.02 to 0.8 parts.

Specifically, the catalyst is 0.01 part, 0.02 part, 0.4 part, 0.8 part, 1 part or 2 parts.

In a preferred embodiment, the metal filler is 80-85 parts.

Specifically, the metal filler is 75 parts, 80 parts, 83 parts, 85 parts, 88 parts or 90 parts.

Specifically, this patent is mainly through mixing preparation high temperature resistant cyanate ester conductive adhesive with cyanate ester mixture, first catalyst and metal filler, the quality of cyanate ester mixture, the quality of catalyst mixture with the mass ratio of metal filler is in above-mentioned within range, can promote high temperature resistant, low moisture absorption and the high adhesive property of high temperature resistant cyanate ester conductive adhesive.

In one embodiment, the first catalyst comprises one or more of an organotin compound, a metal acetylacetonate complex, a metal naphthenate complex, a metal isooctanoate complex, and phenol, the metal filler is silver powder, and the thixotropic agent comprises one or more of fumed silica, precipitated silica, kaolin, and organobentonite.

Specifically, the organotin compound includes one or more of stannous octoate and dibutyltin dilaurate;

specifically, the acetylacetonate metal complex comprises one or more of acetylacetonate cobalt, acetylacetonate copper, acetylacetonate manganese and acetylacetonate nickel;

specifically, the metal naphthenate complex comprises one or more of cobalt naphthenate, manganese naphthenate, copper naphthenate and zinc naphthenate;

specifically, the metal isooctanoate complex comprises one or more of cobalt isooctanoate, manganese isooctanoate, copper isooctanoate and zinc isooctanoate.

Specifically, phenol includes one or more of nonylphenol, dodecylphenol, styrenated phenol, and can help to dissolve the above metal complex at a certain temperature while acting as a catalyst.

Specifically, the structure of the nonylphenol is shown as a formula VI:

the dodecylphenol structure is shown in a formula VII:

the styrenated phenol has a structure shown in a formula VIII:

styrenated phenols are commercially available under the trade designations such as Kumanox-3110, kumanox-3111, kumanox-3112, kumanox-SP, and Kumanox-3120 (all Korean brocade lakes).

In one embodiment, the metal filler is silver powder.

Specifically, the silver powder is flake silver powder, and the surface treatment is carried out, wherein the preferable D50 particle size is 2-8 mu m, and the D100 particle size is less than 50 mu m.

Wherein the surface treating agent comprises one or more of saturated fatty acid, unsaturated fatty acid, silane coupling agent and titanate coupling agent.

Commercial brands on the market can be seen, for example: EA-0295, EA-0008, SA-0201 (Metaro); silver flag #80,silver flake#87 (Ames); TC-506, TC-505, TC-466 (De Li); FA-5-1, FA-D-2, FA-D-3 (Dowa).

In one embodiment, the cyanate ester mixture further comprises a thixotropic agent, wherein the bisphenol E cyanate ester is 50-90 parts by weight, the modified cyanate ester prepolymer is 10-50 parts by weight, and the thixotropic agent is 0-10 parts by weight.

In one embodiment, the thixotropic agent comprises one or more of fumed silica, precipitated silica, kaolin, and organobentonite.

Thixotropic agents are substances with a large specific surface area that can form hydrogen bonds with the polymer or some other structure; after the thixotropic agent is added into the adhesive, the adhesive is sheared when being stirred and coated, and the adhesive solution becomes thin; when the operation is finished, the mixture is thickened again and cannot flow.

Specifically, after the fumed silica is dispersed in the adhesive, hydrogen bonds are generated among different particles through silicon hydroxyl groups on the surfaces of the fumed silica, so that a silica aggregate network is formed, the fluidity of the system is limited, the viscosity is increased, and the thickening effect is achieved; under the action of shearing force, the silicon dioxide network is destroyed, so that the viscosity of the system is reduced, thixotropic effect is generated, and the construction is convenient.

The precipitated silica has very high electrical insulation and porosity; the precipitated silica has a large internal surface area and a large dispersion force in the adhesive.

The kaolin has good thixotropic property, storage stability and leveling property.

The use of the organic bentonite in the adhesive can improve the thixotropic property of the adhesive, thereby increasing the storage stability of the adhesive.

In a preferred embodiment, the bisphenol E cyanate is 65 to 100 parts.

Specifically, the bisphenol E cyanate is 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, 90 parts, 95 parts or 100 parts.

In a preferred embodiment, the modified cyanate ester prepolymer is 10-35 parts.

Specifically, the modified cyanate ester prepolymer is 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts or 50 parts.

In a preferred embodiment, the thixotropic agent is 1 to 5 parts.

Specifically, the thixotropic agent is 1 part, 2 parts, 5 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts.

The thixotropic agent can effectively improve the thixotropic properties of the cyanate ester mixture and the high-temperature-resistant cyanate ester conductive adhesive.

Specifically, the preparation method mainly comprises the steps of mixing bisphenol E cyanate, a modified cyanate ester prepolymer and a thixotropic agent to prepare a cyanate ester mixture, wherein the mass of bisphenol E cyanate ester, the mass of the modified cyanate ester prepolymer and the mass ratio of the thixotropic agent are in the above ranges, so that the bisphenol E cyanate ester, the modified cyanate ester prepolymer and the thixotropic agent can be cured under the conditions of medium temperature on the premise of ensuring high temperature resistance, low moisture absorption, high adhesion and the like, and still have excellent conductive performance; meanwhile, the adhesive has low viscosity and good adhesion performance to substrates such as chips, metals and the like; and has high Tg, and overcomes the problem of low-temperature crystallization.

In one embodiment, the bisphenol E cyanate has the structural formula shown in formula I:

in one embodiment, the modified cyanate ester prepolymer is obtained by reacting phenolic cyanate ester with aminophenol triglycidyl ether, wherein the phenolic cyanate ester is 30-70 parts by weight, and the aminophenol triglycidyl ether is 30-70 parts by weight;

in a preferred embodiment, the phenolic cyanate is 40-60 parts.

Specifically, the phenolic cyanate is 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts or 70 parts.

In a preferred embodiment, the aminophenol triglycidyl ether is 40-60 parts.

Specifically, the aminophenol triglycidyl ether is 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts or 70 parts.

Specifically, the modified cyanate prepolymer is prepared by modifying phenolic cyanate through the aminophenol triglycidyl ether, and the mass ratio of the aminophenol triglycidyl ether to the phenolic cyanate is in the range, so that the high-temperature resistance of bisphenol E cyanate can be maintained, and the conductivity can be improved.

Wherein the chemical formula of the aminophenol triglycidyl ether is shown as formula II and/or formula III:

wherein, the structural formula of R is shown as formula IV:

can be found in commercial brands on the market, such as one or more of MY0500, MY0510 (Hensman), SW-0510 (Seerve), AFG-90H (Hua Yi); and can be found in market brands such as one or more of ELM-100H (alumni).

In one embodiment, the method for preparing the modified cyanate ester prepolymer comprises the following steps:

adding phenolic cyanate into a reaction container, and heating to 80-100 ℃ for dissolution;

adding aminophenol triglycidyl ether, stirring and mixing;

and (3) dropwise adding a second catalyst into the reaction container, stirring for 1-3 hours, heating the solution in the reaction container to 150-160 ℃, continuing to react for 3-5 hours, stopping the reaction when the viscosity reaches 1800-2500cps@80 ℃, and pouring the solution into the container after cooling.

Specifically, 100 parts of phenolic cyanate is added into a reaction vessel, heated to 80-100 ℃ for dissolution, 75 parts of aminophenol triglycidyl ether is added, stirred and mixed under nitrogen atmosphere, 0.01-1 part of catalyst is slowly added dropwise, stirred for 1-3 hours, then slowly heated to 150-160 ℃, continuously reacted for 3-5 hours, after the viscosity reaches 1800-2500cps@80 ℃, the reaction is stopped, cooled to 80 ℃ and poured into the vessel.

In one embodiment, the second catalyst is styrenated phenol, and the structure of the second catalyst is shown in formula viii:

styrenated phenols are commercially available under the trade designations such as Kumanox-3110, kumanox-3111, kumanox-3112, kumanox-SP, and Kumanox-3120 (all Korean brocade lakes).

Wherein the phenolic cyanate is solid at normal temperature, and has a structure shown in formula IX:

phenolic cyanate esters are found in commercial brands such as one or more of Primaset PT-30 (Dragon sand), C05CO100 (Tianqi, yangzhou).

The modified cyanate prepolymer is self-made, and the phenol formaldehyde cyanate is modified by using aminophenol triglycidyl ether under the condition of a catalyst and a certain temperature to form a prepolymer with a certain viscosity. The modified coordination of the aminophenol triglycidyl ether with low viscosity and high Tg and the phenolic cyanate can help to maintain the high temperature resistance of the original bisphenol E cyanate and increase the conductivity of the conductive composite material.

In an embodiment, the invention provides a preparation method of a high Wen Qingsuan ester resistant conductive adhesive, which comprises the following steps:

preparation of cyanate ester mixture:

adding bisphenol E cyanate and modified cyanate prepolymer into a reaction kettle, stirring and mixing for 1.5-2.5 hours at a high temperature of 90-110 ℃ under vacuum, cooling to room temperature, adding thixotropic agent, stirring and mixing for 0.5-2 hours under vacuum;

preparation of the catalyst solution:

adding a first catalyst and styrenated phenol into a reaction kettle, stirring and dissolving for 1.5-2.5 hours under the oil bath condition of 70-90 ℃, cooling to room temperature, filtering, sealing and storing;

preparation of conductive adhesive:

adding the cyanate ester mixture, the catalyst solution and the metal filler into a reaction kettle according to the mass ratio, controlling the temperature of the materials to be 15-25 ℃, defoaming, stirring and mixing for 0.5-2h under vacuum, filtering, and filling to obtain a finished product.

In a preferred embodiment, bisphenol E cyanate and modified cyanate ester prepolymer are added into a reaction kettle, stirred and mixed for 2 hours at a high temperature of 100 ℃ under vacuum, cooled to room temperature, and then thixotropic agent is added, stirred and mixed for 1 hour under vacuum.

In a preferred embodiment, adding acetylacetone metal complex and aminophenol triglycidyl ether into a reaction kettle, stirring and dissolving for 2 hours under the oil bath condition of 80 ℃, cooling to room temperature, filtering by a 325-mesh filter screen, sealing a finished product, and storing at 0-5 ℃;

in a preferred embodiment, the cyanate ester mixture, the catalyst solution and the metal filler are added into a reaction kettle, the temperature of the materials is controlled to be 15-25 ℃, the materials are defoamed, stirred and mixed for 1h under vacuum, a 50-mesh filter screen is used for filtering, and the finished product is obtained after filling.

The invention is further illustrated by the following examples.

Table 1 design of parameters for examples and comparative examples of high Wen Qingsuan ester resistant conductive adhesives

Raw materials and brands in Table 1

Bisphenol E cyanate: c09MO (viscosity at 25 ℃ C.: 200-450 cps);

bisphenol a cyanate ester prepolymer: TA-100 (Mitsubishi gas, viscosity at 80 ℃ C.: 600-800 cps);

bisphenol E cyanate prepolymer: c09PO (Yangzhou Tianqi, 50 ℃ C. Viscosity: 300-800 cps)

Phenolic cyanate: c05CO100 (Tianqi in Yangzhou, viscosity at 80 ℃ C.: 300-700 cps)

Aminophenol triglycidyl ether: ELM-100H (Sumitomo, viscosity at 25 ℃ C.: 500-1000 cps)

Acetylacetonate metal complex: cobalt acetylacetonate (ala Ding Shenghua technology, cobalt II, 97 parts purity) phenol is styrenated phenol: kumanox-3111 (viscosity at 25 ℃ C. 300-600 cps)

Thixotropic agent: CAB-O-SIL TS720 (cabot, fumed silica)

Silver powder: SA-0201 (Metalir, D50=2.6 μm, D100 21 μm)

Example 1:

the embodiment is used for explaining the preparation method of the high-temperature-resistant cyanate ester conductive adhesive disclosed by the invention, and comprises the following operation steps:

(1) Synthesizing and preparing a modified cyanate ester prepolymer:

adding 100 parts of phenolic cyanate into a reaction vessel, heating to 80-100 ℃ for dissolution, adding 75 parts of aminophenol triglycidyl ether, stirring and mixing under nitrogen atmosphere, slowly dripping 0.01-1 part of catalyst styrenated phenol, stirring for 1-3 hours, slowly heating to 150-160 ℃, continuing to react for 3-5 hours, stopping the reaction when the viscosity reaches 1800-2500cps@80 ℃, cooling to 80 ℃, and pouring into the vessel.

Preparation of a cyanate ester mixture:

adding 14 parts of bisphenol E cyanate and 5 parts of modified cyanate prepolymer into a reaction kettle, stirring and mixing for 2 hours at a high temperature of 100 ℃ under vacuum, cooling to room temperature, adding 0.5 part of thixotropic agent, and stirring and mixing for 1 hour under vacuum.

3 preparation steps of the catalyst:

the reaction kettle is internally provided with the following components according to the proportion of 1:9, adding acetylacetone metal complex and styrenated phenol according to a mass ratio, stirring and dissolving for 2 hours under the oil bath condition of 80 ℃, cooling to room temperature, filtering by a 325-mesh filter screen, sealing a finished product, and storing at 0-5 ℃.

4 preparation step of conductive adhesive

Adding the cyanate ester mixture, the first catalyst and the metal filler into a reaction kettle according to the mass ratio of 19.5:0.5:80, controlling the material temperature to be 15-25 ℃, defoaming, stirring and mixing for 1h under vacuum, filtering by a 50-mesh filter screen, and filling to obtain the finished product.

Example 2

Example 2 is used for illustrating the preparation method of the high temperature resistant cyanate ester conductive adhesive disclosed in the invention, which comprises most of the operation steps in example 1, and the difference is that: the proportions in the synthetic preparation of the modified cyanate ester prepolymer are different.

(1) Synthesizing and preparing a modified cyanate ester prepolymer:

adding 75 parts of phenolic cyanate into a reaction vessel, heating to 80-100 ℃ for dissolution, adding 100 parts of aminophenol triglycidyl ether, stirring and mixing under nitrogen atmosphere, slowly dripping 0.01-1 part of catalyst styrenated phenol, stirring for 1-3 hours, slowly heating to 150-160 ℃, continuing to react for 3-5 hours, stopping the reaction when the viscosity reaches 1800-2500cps@80 ℃, cooling to 80 ℃, and pouring into the vessel.

The mass percentages of the materials used in example 2 are shown in Table 1.

Example 3

Example 3 is used for illustrating the preparation method of the high temperature resistant cyanate ester conductive adhesive disclosed in the invention, which comprises most of the operation steps in example 1, and the difference is that: the modified cyanate ester prepolymer has different added mass portions.

The mass percentages of the materials used in example 3 are shown in Table 1.

Example 4

Example 4 is used for illustrating the preparation method of the high temperature resistant cyanate ester conductive adhesive disclosed in the invention, which comprises most of the operation steps in example 2, and the difference is that: the modified cyanate ester prepolymer has different added mass portions.

The mass percentages of the materials used in example 4 are shown in Table 1.

Comparative examples 1 to 9

Comparative examples 1-9 are used for comparative illustration of the preparation method of the high temperature resistant cyanate ester conductive adhesive disclosed in the present invention, comprising most of the operation steps in example 1, which are different in that:

comparative example 1 is a simple direct blend of two resins of the modified cyanate ester prepolymer of example 1;

comparative example 2 is a simple direct blend of the two resins of the modified cyanate ester prepolymer of example 2;

the cyanate ester prepolymer in comparative example 3 is bisphenol A cyanate ester prepolymer TA-100;

the cyanate ester prepolymer in comparative example 4 was bisphenol E cyanate ester prepolymer C09PO;

the cyanate ester prepolymer in comparative example 5 is phenolic cyanate ester C05CO100;

comparative example 6 is an epoxy resin (aminophenol triglycidyl ether) ELM-100H comparative;

comparative example 7 is a pure bisphenol E cyanate ester comparison;

comparative example 8 is a comparison of silver powder with multi-additive metal conductive powder;

comparative example 9 is a pure modified cyanate ester prepolymer comparative.

The mass percentages of the respective substances used in comparative examples 1 to 9 are shown in Table 1.

Performance testing

The high-temperature-resistant cyanate ester conductive adhesive prepared by the method is subjected to the following performance test:

(1) Viscosity test

Test instrument: a Brookfield CAP2000+, rotor No. 1, rotational speed 5rpm;

test temperature: 25 ℃;

the testing method comprises the following steps: taking 0.24-0.26g of each of the conductive adhesives in examples 1-4 and comparative examples 1-9, and measuring the viscosity value of each sample by a cone-plate viscometer;

(2) Tg test

Test instrument: a thermo-mechanical analyzer (TMA) resistance TMA 402F3;

test temperature: the temperature is increased by 2K/min at 25-350 ℃;

the testing method comprises the following steps: the conductive adhesives in examples 1-4 and comparative examples 1-9 were cured in a cylindrical mold and polished to a specimen with a diameter of 9.4-9.7mm and a height of 20-25mm, the test frequency was 1Hz, the test mode was temperature rise thermal expansion, the second repeated measurement data was taken, and the inflection point was taken as the Tg point.

(3) DSC peak test

Test instrument: differential Scanning Calorimeter (DSC) resistant DSC 214;

test temperature: the temperature rise rate is 10K/min at 35-350 ℃;

the testing method comprises the following steps: and taking the peak value (DEG C) of the exothermic curve, and primarily reacting the curing temperature of the conductive adhesive.

(4) Adhesive strength test

Test instrument: nordson DAGE4000

Bonding a substrate: silicon wafer/aluminum, bonding area 2 x 2mm;

test temperature: room temperature;

the testing method comprises the following steps: the thickness of the adhesive layer is 50 mu m, and the curing temperature is uniformly 300 ℃ and kept for 20min. And (5) testing shearing force. 5 samples were tested and the average of the middle 3 samples was taken.

(5) Resistance value test

Test instrument: agilent KEYSIGHT 34461A;

test temperature: room temperature;

the testing method comprises the following steps: four-wire method for testing resistance value, test distance was 30mm, and the glue sample was coated on a glass slide, with dimensions of about 75×12.5×0.050mm, curing time was 60min, and curing temperature was as shown in table 2.

(1) The test results obtained in examples 1 to 4 and comparative examples 1 to 9 are filled in Table 2.

TABLE 2

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Note that: resistance value exceeding the range, > 1000 omega

As shown in the above table, examples 1-4 with the modified cyanate ester prepolymer added all have better processability (viscosity < 8000 cps), higher Tg (> 240 ℃), excellent shear strength (> 10 kg) and medium and low temperature curing conductivity (conductivity can be achieved by curing at 150 ℃); meanwhile, compared with comparative examples 1 and 2, the prepolymerization reaction of the modified cyanate ester prepolymer is obviously better than the simple blending of two materials.

Examples 3 and 4 illustrate that too little addition of the modified cyanate ester prepolymer inhibits low temperature crystallization of bisphenol E cyanate ester; comparative examples 3, 4 and 5 demonstrate that cyanate ester prepolymers are effective in inhibiting low temperature crystallization of bisphenol E cyanate esters, but fail to provide conductive properties for medium and low temperature curing.

Comparative example 5 illustrates that phenolic cyanate esters can help to increase Tg; comparative example 6 illustrates that the introduction of an epoxy resin (aminophenol triglycidyl ether) has a large effect on the gain in conductivity, but greatly loses Tg; the combined application of the two has therefore inspired the invention.

Comparative examples 7 and 8 reflect the low temperature crystallization phenomenon of bisphenol E cyanate ester even though a large amount of other substances are added; comparative example 8 illustrates that adding too much metal conductive powder reduces the adhesive shear properties; comparative example 9 illustrates that the modified cyanate ester prepolymer has a relatively high viscosity, but can be used in combination with bisphenol E cyanate ester having a low viscosity.

The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.

Claims (10)

1. A high Wen Qingsuan-resistant ester conductive adhesive is characterized in that: the high-temperature-resistant cyanate ester conductive adhesive consists of the following components: the phenolic cyanate modified phenolic cyanate ester comprises a cyanate ester mixture, a first catalyst and a metal filler, wherein the cyanate ester mixture comprises bisphenol E cyanate ester and a modified cyanate ester prepolymer, and the modified cyanate ester prepolymer is an aminophenol triglycidyl ether modified phenolic cyanate ester prepolymer.

2. The high temperature resistant cyanate ester conductive adhesive of claim 1, wherein: 10-25 parts of cyanate ester mixture, 0.01-2 parts of first catalyst and 75-90 parts of metal filler.

3. The high temperature resistant cyanate ester conductive adhesive of claim 1, wherein: the first catalyst includes one or more of an organotin compound, a metal acetylacetonate complex, a metal naphthenate complex, a metal isooctanoate complex, and phenol.

4. The high temperature resistant cyanate ester conductive adhesive of claim 1, wherein: the metal filler is silver powder.

5. The high temperature resistant cyanate ester conductive adhesive of claim 1, wherein: the cyanate ester mixture further comprises a thixotropic agent, wherein the thixotropic agent comprises one or more of fumed silica, precipitated silica, kaolin and organic bentonite, the bisphenol E cyanate ester is 50-90 parts by weight, the modified cyanate ester prepolymer is 10-50 parts by weight, and the thixotropic agent is 0-10 parts by weight.

6. The high temperature resistant cyanate ester conductive adhesive of claim 1, wherein: the structural formula of the bisphenol E cyanate is shown as formula I:

7. the high temperature resistant cyanate ester conductive adhesive of claim 1, wherein: the modified cyanate prepolymer is prepared by reacting 30-70 parts by weight of phenolic cyanate and 30-70 parts by weight of aminophenol triglycidyl ether;

wherein the chemical formula of the aminophenol triglycidyl ether is shown as formula II and/or formula III:

wherein, the structural formula of R is shown as formula IV:

8. the high temperature resistant cyanate ester conductive adhesive of claim 1, wherein: the preparation method of the modified cyanate ester prepolymer comprises the following steps:

adding phenolic cyanate into a reaction container, and heating to 80-100 ℃ for dissolution;

adding aminophenol triglycidyl ether, stirring and mixing;

and (3) dropwise adding a second catalyst into the reaction container, stirring for 1-3 hours, heating the solution in the reaction container to 150-160 ℃, continuing to react for 3-5 hours, stopping the reaction when the viscosity reaches 1800-2500cps@80 ℃, and pouring the solution into the container after cooling.

9. The high temperature resistant cyanate ester conductive adhesive of claim 8, wherein: the second catalyst comprises styrenated phenol.

10. The method for preparing the high-temperature-resistant cyanate ester conductive adhesive according to any one of claims 1 to 9, wherein the method comprises the following steps: the method comprises the following steps:

preparation of cyanate ester mixture:

adding bisphenol E cyanate and modified cyanate prepolymer into a reaction kettle, stirring and mixing for 1.5-2.5 hours at a high temperature of 90-110 ℃ under vacuum, cooling to room temperature, adding thixotropic agent, stirring and mixing for 0.5-2 hours under vacuum;

preparation of the catalyst solution:

adding a first catalyst and styrenated phenol into a reaction kettle, stirring and dissolving for 1.5-2.5 hours under the oil bath condition of 70-90 ℃, cooling to room temperature, filtering, sealing and storing;

preparation of conductive adhesive:

adding the cyanate ester mixture, the catalyst solution and the metal filler into a reaction kettle according to the mass ratio, controlling the temperature of the materials to be 15-25 ℃, defoaming, stirring and mixing for 0.5-2h under vacuum, filtering, and filling to obtain a finished product.