CN115678015A - Modified organic silicon resin, conductive adhesive and preparation method thereof - Google Patents

Abstract

The application discloses a modified silicone resin, a conductive adhesive and a preparation method thereof. Wherein, the modified silicone resin is specifically an acryloxy-modified silicone resin containing multiple polar groups. By adding the acryloyloxy-modified silicone resin containing multiple polar groups to the conductive adhesive, the bonding strength of the conductive adhesive to the substrate can be improved, so as to achieve better crystal device resistance. Drop performance improves the mechanical reliability of crystal devices. In addition, by introducing nano-scale low-temperature sintered silver powder into the conductive adhesive, the nano-scale low-temperature sintered silver powder in the adhesive can be partially welded to the bonded metal substrate during high-temperature curing, thereby greatly improving the Improve the cohesion of the conductive adhesive itself and its bonding performance with the substrate to be bonded.

Description

Modified silicone resin, conductive adhesive and preparation method thereof

technical field

The present application relates to the technical field of adhesive preparation, in particular to a modified silicone resin for preparing conductive adhesive, conductive adhesive and a preparation method thereof.

Background technique

In the surface mount device (Surface Mounted Devices, SMD) assembly application, the conductive adhesive is used for bonding the SMD chip and the base for carrying the SMD chip, and at the same time provides electrical conductivity. For example, in FIG. 1A , the PCB 101 inside the terminal device 100 is provided with a base 102 for carrying an SMD chip, and the SMD chip 103 is fixed on the base 102 by conductive glue 104 .

Ordinary addition-type silicone conductive adhesive is a kind commonly used in SMD chips. It is generally prepared from vinyl silicone oil, vinyl MQ resin, hydrogen-containing silicone oil, conductive powder, platinum catalyst and inhibitor. However, ordinary addition-type silicone conductive adhesives are not ideal for bonding most materials, especially for gold-plated materials. Therefore, long-term or large vibrations will cause the chip to be separated from the base, and the drop resistance is poor. It cannot meet the demands of mobile phones and other products with high requirements for anti-drop capability.

For example, FIG. 1B to FIG. 1D show several situations in which the SMD chip 103 falls from the base 102 . Wherein, in FIG. 1B , due to poor adhesion of the conductive glue 104 to the SMD chip 103 , the SMD chip 103 falls from the base 102 , while the conductive glue 104 remains entirely on the base 102 . In FIG. 1C , due to poor adhesion of the conductive glue 104 to the base 102 , the SMD chip 103 falls from the base 102 , and the conductive glue 104 remains entirely on the SMD chip 103 . In FIG. 1D , due to the poor cohesion of the conductive glue 104 itself, the SMD chip 103 falls from the base 102 , while a part of the conductive glue 104 remains on the SMD chip 103 and another part remains on the base 102 .

Contents of the invention

This application provides a modified silicone resin for preparing conductive adhesives, conductive adhesives and preparation methods thereof, in order to solve the problem that ordinary addition-type silicone conductive adhesives have unsatisfactory bonding effects on most materials .

In the first aspect, the present application provides a modified silicone resin for preparing a silicone conductive adhesive, the structural formula of the modified silicone resin is:

or,

Wherein, Me is H or CH3, m is an integer of 100-10000, and n is an integer of 1-5.

In the first aspect, the modified silicone resin involved is specifically a series of acryloxy-modified silicone resins containing multiple polar groups. By adding the acryloyloxy-modified silicone resin containing multiple polar groups to the conductive adhesive, the bonding strength of the conductive adhesive to the substrate to be bonded can be improved, thereby achieving a better crystal The anti-drop performance of the device improves the mechanical reliability of the crystal device.

In the first aspect, the modified silicone resin has a characteristic absorption peak of a carbon-oxygen single bond within a wavelength of 8um ± 0.5um, a characteristic absorption peak of a carbon-oxygen double bond within a wavelength of 6um ± 0.5um, and a characteristic absorption peak of a carbon-oxygen double bond within a wavelength of 3um There are stretching vibration absorption peaks of carbon-hydrogen bonds in the range of ±0.5um. It shows that the modified silicone resin contains acryloxy groups.

In the second aspect, the embodiment of the present application provides a method for preparing a modified silicone resin, the method comprising;

Put the acrylic resin terminated with acryloyloxy group and hydrogen-containing silicone oil in the reaction solvent, and carry out the addition reaction under the action of the inhibitor and the catalyst;

The modified silicone resin is extracted from the reaction product.

In the second aspect, the properties of hydrogen-containing silicone oil are changed by grafting acryloxy-terminated acrylic resin into hydrogen-containing silicone. The obtained modified silicone resin contains multiple polar groups and has strong bonding strength. By adding the acryloxy-modified silicone resin containing multiple polar groups to the conductive adhesive, the bonding strength of the conductive adhesive to the substrate can be improved, so as to achieve better crystal device resistance. Drop performance improves the mechanical reliability of crystal devices. At the same time, the flexibility of the conductive adhesive can be maintained.

In an optional implementation manner of the second aspect, the reaction temperature of the addition reaction is 100°C-200°C.

In an optional implementation of the second aspect, extracting the modified silicone resin from the reaction product includes: low-pressure distillation of the reaction solvent and small molecule reactants from the reaction product; adding activated carbon to absorb the residual catalyst; filtering Activated carbon is removed to obtain a modified silicone resin liquid.

In an optional implementation manner of the second aspect, the molar ratio of the H groups in the hydrogen-containing silicone oil to the acryloxy groups in the acrylic resin terminated with acryloxy groups is 8:1-1:1. By controlling the molar ratio of the introduced acryloyloxy group and hydrogen group, the flexibility of the modified silicone resin system can be maintained while achieving the introduction of acryloyloxy group and polar functional groups to improve the bonding strength.

In an alternative implementation of the second aspect, the structural formula of the acrylic resin terminated with acryloyloxy group is:

Wherein, n is an integer of 1-5.

In an optional implementation of the second aspect, the structural formula of the hydrogen-containing silicone oil is:

Wherein, Me is H or CH3, and m is an integer of 100-10000.

In the third aspect, the present application also provides a conductive adhesive, including: 0.5-5 parts by weight of the modified silicone resin provided in the first aspect, 5-15 parts by weight of methyl vinyl MQ silicone resin, 0-90 parts by weight Parts of micron silver powder, 1-50 parts by weight of nano-sized low-temperature sintered silver powder, 0.1-1 part by weight of 3-(methacryloyloxy)propyl trimethoxysilane, 0.1-1 part by weight of borate coupling agent, 1-10 parts by weight solvent, 0.1-0.5 parts by weight inhibitor, 0.1-0.5 parts by weight platinum catalyst.

Wherein, the methyl vinyl MQ silicone resin is a network polysiloxane including vinyl, monofunctional siloxane chains R ₃ SiO _1/2 and tetrafunctional siloxane chains SiO _4/2 .

In the third aspect, on the one hand, by adding the acryloxy-modified silicone resin containing multiple polar groups to the conductive adhesive, the bonding strength of the conductive adhesive to the substrate can be improved, Therefore, better anti-drop performance of the crystal device is achieved, and the mechanical reliability of the crystal device is improved. At the same time, the flexibility of the conductive adhesive can be maintained. On the other hand, by introducing nano-scale low-temperature sintered silver powder into the conductive adhesive, the nano-scale low-temperature sintered silver powder in the adhesive can be partially welded to the bonded metal substrate during high-temperature curing, thereby Greatly improve the cohesion of the conductive adhesive itself and its bonding performance with the substrate to be bonded.

In an optional implementation of the third aspect, the inhibitor is selected from any one or more of diallyl maleate, diethyl fumarate, acetylenic alcohol, and 1-ethynyl-1-cyclohexanol kind.

In an optional implementation manner of the third aspect, the platinum catalyst is one or more of chloroplatinic acid catalysts and Castel platinum catalysts.

In a fourth aspect, the present application also provides a method for preparing a conductive adhesive, including:

Weigh 0.5-5 parts by weight of the modified silicone resin described in claim 1, 5-15 parts by weight of methyl vinyl MQ silicone resin, 0-90 parts by weight of micron silver powder, 1-50 parts by weight of nano-level low temperature Sintered silver powder, 0.1-1 parts by weight of 3-(methacryloxy)propyltrimethoxysilane, 0.1-1 parts by weight of borate coupling agent, 1-10 parts by weight of solvent, 0.1-0.5 parts by weight of inhibitor agent, 0.1-0.5 parts by weight platinum catalyst;

Add the weighed modified silicone resin, methyl vinyl MQ silicone resin, micron-sized silver powder, nano-sized low-temperature sintered silver powder, inhibitor and part of the solvent into the mixer in sequence, and stir for 2-4 hours;

Put the stirred material into a three-roll mill to grind and disperse to obtain a mixed material;

Dissolve the weighed platinum catalyst, 3-(methacryloyloxy)propyltrimethoxysilane and borate coupling agent in the remaining solvent, add them to the mixed material, and grind and disperse through the grinder After that, it is added to the mixer and stirred to obtain the mature material;

Adjust the viscosity of the mature material to the target value, filter, and vacuum defoam to obtain a conductive adhesive.

In the fourth aspect, by adding the acryloxy-modified silicone resin containing multiple polar groups to the conductive adhesive, the bonding strength and high resistance of the conductive adhesive to the substrate can be improved. , low-temperature performance, so as to achieve better anti-drop performance of crystal devices and improve the mechanical reliability of crystal devices. At the same time, the flexibility of the conductive adhesive can be maintained. On the other hand, by introducing nano-scale low-temperature sintered silver powder into the conductive adhesive, the nano-scale low-temperature sintered silver powder in the adhesive can be partially welded with the substrate to be bonded during high-temperature curing, thereby greatly Significantly improve the cohesion of the conductive adhesive itself and its bonding performance with the substrate.

Description of drawings

In order to illustrate the technical solution of the present application more clearly, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, for those of ordinary skill in the art, on the premise of not paying creative labor, Additional drawings can also be derived from these drawings.

FIG. 1A is a schematic diagram of a SMD bonding structure shown according to an exemplary embodiment of the present application;

FIG. 1B is a schematic diagram of a crystal device falling according to an exemplary embodiment of the present application;

FIG. 1C is a schematic diagram of a crystal device falling according to an exemplary embodiment of the present application;

FIG. 1D is a schematic diagram of a crystal device falling according to an exemplary embodiment of the present application;

Fig. 2 is a flowchart of a method for preparing a modified silicone resin according to an exemplary embodiment of the present application;

Fig. 3 is an infrared spectrogram of a modified silicone resin according to an exemplary embodiment of the present application;

Fig. 4 is a flowchart of a method for preparing a conductive adhesive according to an exemplary embodiment of the present application.

Detailed ways

In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described The embodiments are only some of the embodiments of the present application, but not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts shall fall within the scope of protection of this application.

As shown in FIG. 1A , the conductive adhesive 104 and the adherend (base 102 ) form an adhesive structure. In this bonding structure, there is an electric double layer at the interface between the adhesive and the adherend, and the electrostatic attraction of the electric double layer is the effect of the adhesive force. When the adhesive is peeled off from the surface of the adherend, a potential difference will be generated between the adhesive and the surface of the adherend. When the peeling distance increases to a certain limit value, there will be a discharge phenomenon between the adhesive and the adherend, and the instantaneous discharge energy at this time is equal to the bonding work of the bonded structure. Based on this, the bonding work can be calculated by calculating the instantaneous discharge energy, and the bonding work can represent the bonding force or the bonding strength. Among them, the bonding work can be calculated according to the following formula:

Among them, Wa represents the bonding work, Q represents the surface density of charges, ε represents the dielectric constant of the medium, and h represents the discharge distance.

From the above method of calculating the bonding work, it can be seen that under the condition of constant dielectric constant and discharge distance of the medium, the greater the surface density of the charge, the greater the instantaneous discharge energy, that is, the greater the bonding work. Since the stronger the polarity of the adhesive, the higher the surface density of the charge, the stronger the polarity of the adhesive, the greater the bonding work and the stronger the bonding strength.

The present application relates to a modified silicone resin, a preparation method of the modified silicone resin, a conductive adhesive containing the modified silicone resin and a preparation method of the conductive adhesive. Wherein, the modified silicone resin is specifically an acryloxy-modified silicone resin containing multiple polar groups. By adding the acryloxy-modified silicone resin containing multiple polar groups to the conductive adhesive, the bonding strength of the conductive adhesive to the substrate can be improved, so as to achieve better crystal device resistance. Drop performance improves the mechanical reliability of crystal devices.

In some embodiments, the structural formula of the above-mentioned modified silicone resin is:

or,

Wherein, Me is H or CH ₃ , m is an integer of 100-10000, and n is an integer of 1-5.

In some embodiments, the above-mentioned silicone resin can be prepared by using an acryloxy-terminated acrylic resin and hydrogen-containing silicone oil as reactants, and through an addition reaction between the two. Among them, the acrylic resin terminated with acryloyloxy group can be acrylic resin terminated with monofunctional methacryloxy group, or acrylic resin terminated with difunctional methacryloxy group; and hydrogen-containing silicone oil with side group H.

In certain embodiments, an acrylic resin terminated with an acryloyloxy group has the structural formula:

Wherein, n is an integer of 1-5.

In some embodiments, the structural formula of hydrogen-containing silicone oil is:

Wherein, Me is H or CH ₃ , and m is an integer of 100-10000.

Fig. 2 is a flow chart of a preparation method of a modified silicone resin shown in some embodiments of the present application. As shown in Fig. 2, the method includes:

S201, placing the acrylic resin terminated with acryloyloxy groups and hydrogen-containing silicone oil in a reaction solvent, and performing an addition reaction at 100-200° C. under the action of an inhibitor and a catalyst.

Optionally, the molar ratio of the H groups in the hydrogen-containing silicone oil to the acryloxy groups in the acrylic resin terminated with acryloxy groups is 8:1-1:1. By controlling the molar ratio of the introduced acryloyloxy groups and hydrogen groups, it is possible to introduce acryloyloxy groups and polar functional groups to improve the bonding strength while maintaining the flexibility of the modified silicone resin system.

Optionally, the reaction solvent is toluene.

Optionally, the catalyst is a platinum catalyst, such as chloroplatinic acid or Castel platinum catalyst. The weight proportion of the catalyst in the whole reaction system is 0.1%-1%.

Optionally, the inhibitor is ethanol.

S202, extracting the modified silicone resin from the reaction product.

Specifically, the reaction solvent and the small molecule reactant are distilled out from the reaction product under low pressure; the residual catalyst is adsorbed by adding activated carbon; the activated carbon is removed by filtration to obtain a modified silicone resin liquid.

In some embodiments, the two terminal groups of the acrylic resin terminated with acryloyloxy group are respectively methacryloxyl group and acryloxyl group, and its structural formula is:

Wherein, n is an integer of 1-5.

The structural formula of hydrogen-containing silicone oil is:

Wherein, Me is H or CH ₃ , and m is an integer of 100-10000.

In some embodiments, during the above-mentioned addition reaction between the acrylic resin terminated with acryloyloxy group and hydrogen-containing silicone oil, the acryloyloxy group can be combined with the side group H, one or more side groups on the main chain of the hydrogen-containing silicone oil molecule A terminal H addition occurs. According to the position and quantity of H involved in the reaction of hydrogen-containing silicone oil, the reaction products are different. Specifically, the above-mentioned addition reaction formula of the acrylic resin terminated with acryloyloxy group and hydrogen-containing silicone oil is as follows reaction formulas (1)-(7).

Reaction formula (1):

As can be seen from the reaction formula (1), the C=C bonds of the methacryloxyl groups and the acrylyloxyl groups at both ends of the acrylic resin are opened, and are respectively grafted to the side group H of the hydrogen-containing silicone oil to form the above-mentioned structural formula ( 1) Modified silicone resin.

Reaction formula (2):

It can be seen from the reaction formula (2) that the C=C bond of the methacryloxy group at one end of the acrylic resin is opened and grafted to the side group H of the hydrogen-containing silicone oil, and the C of the acryloxyl group at the other end of the acrylic resin = The C bond is opened, grafted onto the terminal H of the hydrogen-containing silicone oil, and a modified silicone resin having the above structural formula (2) is generated.

Reaction formula (3):

It can be seen from the reaction formula (3) that the C=C bond of the methacryloxy group at one end of the acrylic resin is opened and grafted to the terminal H of the hydrogen-containing silicone oil, and the C of the acryloxyl group at the other end of the acrylic resin = The C bond is opened, grafted onto the side group H of the hydrogen-containing silicone oil, and the modified silicone resin with the above structural formula (3) is generated.

Reaction formula (4):

It can be seen from the reaction formula (4) that the C=C bonds of the methacryloyloxy group and the acryloyloxy group at both ends of the acrylic resin are opened, and are respectively grafted to the two terminal groups H of the hydrogen-containing silicone oil.

Reaction formula (5):

It can be seen from the reaction formula (5) that the methacryloxy group at one end of the acrylic resin is grafted to the terminal group H on the main chain of the hydrogen-containing silicone oil molecule, and the acryloxyl group at the other end of the acrylic resin is grafted to the same hydrogen-containing silicone oil. On the side group H on the main chain of the hydrogen silicone oil molecule, a modified silicone resin having the above structural formula (5) is generated.

Reaction formula (6):

It can be seen from the reaction formula (6) that the methacryloyloxy group at one end of the acrylic resin is grafted to the side group H on the main chain of the hydrogen-containing silicone oil molecule, and the acryloyloxy group at the other end of the acrylic resin is grafted to the same hydrogen-containing silicone oil. On the terminal group H on the main chain of the hydrogen silicone oil molecule, a modified silicone resin having the above structural formula (6) is generated.

Reaction formula (7):

It can be seen from the reaction formula (7) that the methacryloxyl and acryloxyl groups at both ends of the acrylic resin are grafted to the side group H and the terminal group H on the main chain of the same hydrogen-containing silicone oil molecule, forming a product with the above structural formula (7) Modified silicone resin.

Fig. 3 is the infrared spectrogram of the modified silicone resin provided by the embodiment of the present application. As shown in Fig. 3, the characteristic absorption peak of the carbon-oxygen single bond appears at the wavelength (8um ± 0.5um), and the wavelength (6um ± 0.5um) ) appeared the characteristic absorption peak of the carbon-oxygen double bond, and the stretching vibration absorption peak of the carbon-hydrogen bond appeared at the wavelength (3um±0.5um), indicating that the modified silicone resin introduced acryloyloxy groups.

As mentioned above, on the one hand, by adding the acryloxy-modified silicone resin containing multiple polar groups to the conductive adhesive, the bonding strength of the conductive adhesive to the substrate can be improved, thereby Achieve better anti-drop performance of the crystal device, and improve the mechanical reliability of the crystal device. At the same time, the flexibility of the conductive adhesive can be maintained.

In some embodiments, the conductive adhesive specifically includes: 0.5-5 parts by weight of the above-mentioned modified silicone resin, 5-15 parts by weight of methyl vinyl MQ silicone resin, 0-90 parts by weight of micron silver powder, 1- 50 parts by weight of nanoscale low-temperature sintered silver powder, 0.1-1 parts by weight of 3-(methacryloyloxy)propyltrimethoxysilane, 0.1-1 parts by weight of borate coupling agent, 1-10 parts by weight of solvent, 0.1-0.5 parts by weight inhibitor, 0.1-0.5 parts by weight platinum catalyst.

Wherein, the methyl vinyl MQ silicone resin is a network polysiloxane including vinyl, monofunctional siloxane chains R ₃ SiO _1/2 and tetrafunctional siloxane chains SiO _4/2 .

It should be noted that by introducing nano-scale low-temperature sintered silver powder into the conductive adhesive, when it is cured above 250°C, the nano-scale low-temperature sintered silver powder in the adhesive can be partially welded to the bonded metal substrate. In this way, the cohesion of the conductive adhesive itself and its bonding performance with the substrate are greatly improved.

In some embodiments, the inhibitor is selected from any one or more of diallyl maleate, diethyl fumarate, acetylenic alcohol, and 1-ethynyl-1-cyclohexanol.

In some embodiments, the platinum catalyst is one or more of chloroplatinic acid catalysts and Castel platinum catalysts.

In some embodiments, the solvent is selected from any one or more of alkane solvents, No. 200 solvent naphtha, No. 150 solvent naphtha, and No. D200 solvent naphtha.

Fig. 4 is a flow chart of a preparation method of a modified silicone resin shown in some embodiments of the present application. As shown in Fig. 4, the method includes:

S401, weigh 0.5-5 parts by weight of modified silicone resin, 5-15 parts by weight of methyl vinyl MQ silicone resin, 0-90 parts by weight of micron-sized silver powder, 1-50 parts by weight of nano-sized low-temperature sintered silver powder, 0.1 -1 part by weight of 3-(methacryloyloxy)propyltrimethoxysilane, 0.1-1 part by weight of borate coupling agent, 1-10 parts by weight of solvent, 0.1-0.5 parts by weight of inhibitor, 0.1-0.5 parts by weight parts by weight platinum catalyst.

S402, adding the weighed modified silicone resin, methyl vinyl MQ silicone resin, micron-sized silver powder, nano-sized low-temperature sintered silver powder, inhibitor and part of the solvent into the mixer in sequence, and stirred for 2-4 hours.

S403, putting the stirred material into a three-roll mill for grinding and dispersing to obtain a mixed material.

In a more specific implementation, in S403, first put the material stirred in S402 into a three-roll mill for grinding and dispersing to obtain the mixed material A; then continue to grind and disperse the mixed material A through the three-roll mill for 3 - 5 times, keeping the distance between the rollers at 15-25um, to obtain the mixed material B.

S404, dissolve the platinum catalyst, 3-(methacryloyloxy)propyltrimethoxysilane and borate coupling agent in the remaining solvent, and add to the mixed material obtained in S403, and grind After being ground and dispersed by a machine, it is added to the mixer and stirred to obtain the mature material.

S405, adjusting the viscosity of the matured material to a target value, filtering, and vacuum defoaming to obtain a conductive adhesive.

The modified silicone resin and its preparation method provided by the present application, the conductive adhesive and its preparation method are described below through specific examples, and performance tests are performed on the samples of the conductive adhesive prepared in the examples.

Example 1

S101, according to the ratio of the molar ratio of the H group in the hydrogen-containing silicone oil to the acryloxyl group in the acrylic resin is 8:1, combine the acrylic resin end-capped with difunctional acryloxyl group and the acrylic resin containing end group H and side group H Hydrogen silicone oil is placed in toluene, under the action of ethanol (inhibitor) and Castel platinum catalyst (catalyst), the temperature is raised to 150°C, and the addition reaction is carried out at 150°C.

S102, distilling the reaction solvent and small molecule reactants from the reaction product under low pressure; adding activated carbon to absorb the residual catalyst; filtering and removing the activated carbon to obtain a translucent modified silicone resin liquid.

Example 2

The difference between Example 2 and Example 1 is that the molar ratio of the H groups in the hydrogen-containing silicone oil to the acryloyloxy groups in the acrylic resin is 4:1.

Example 3

S1, take by weighing 2 parts by weight of the modified silicone resin prepared in Example 1, 10 parts by weight of methyl vinyl MQ silicone resin, 40 parts by weight of micron silver powder, 8 parts by weight of nanoscale low-temperature sintered silver powder, 1 weight part 3-(methacryloyloxy)propyltrimethoxysilane, 1 part by weight of borate coupling agent, 4 parts by weight of solvent, 0.1 part by weight of inhibitor, and 0.1-0.5 part by weight of platinum catalyst.

More specifically, the product model of the methyl vinyl MQ silicone resin used in this example is Ningbo Runhe S0826H, the product model of the micron-sized silver powder used is TC-505 silver powder produced by Japan Deli, and the nano-sized low-temperature The product model of the sintered silver powder is LS0305 produced by Okada Precious Metals in Japan, the solvent used is D150 mineral spirits, and the inhibitor used is acetylenic alcohol.

S2, add the weighed modified silicone resin, methyl vinyl MQ silicone resin, micron-sized silver powder, nano-sized low-temperature sintered silver powder, inhibitor and 70% solvent into the mixer in sequence, and stir the reaction 2-4 Hour.

S3, put the stirred material into a three-roll mill for grinding and dispersing, keep the distance between the rollers at 10um, and obtain the mixed material A; continue to grind and disperse the mixed material A through the three-roll mill for 5 times, keep the distance between the rollers at 25um, and obtain Mixture B.

S4, dissolve the weighed platinum catalyst, 3-(methacryloyloxy)propyltrimethoxysilane and borate coupling agent in the remaining 30% solvent, and add them to the mixture B, pass through the grinder After grinding and dispersing, add it into the mixer and stir to obtain the mature material.

S5, adjusting the viscosity of the mature material to a target value of 10000-30000 mPa·s, filtering, and vacuum defoaming to obtain a conductive adhesive.

Example 4

The difference between Example 4 and Example 3 is that the raw materials are weighed according to the following parts by weight: 2 parts by weight of the modified silicone resin prepared in Example 1, 10 parts by weight of methyl vinyl MQ silicone resin , 24 parts by weight of micron-sized silver powder, 24 parts by weight of nano-sized low-temperature sintered silver powder, 1 part by weight of 3-(methacryloyloxy)propyltrimethoxysilane, 1 part by weight of borate coupling agent, 4 parts by weight Part solvent, 0.1 part by weight inhibitor, 0.1-0.5 part by weight platinum catalyst.

Example 5

The difference between Example 5 and Example 3 is that each raw material is weighed according to the following parts by weight: 2 parts by weight of the modified silicone resin prepared in Example 1, 10 parts by weight of methyl vinyl MQ silicone resin , 48 parts by weight of nanoscale low-temperature sintered silver powder , 1 part by weight of 3-(methacryloyloxy)propyltrimethoxysilane, 1 part by weight of borate coupling agent, 4 parts by weight of solvent, 0.1 part by weight of inhibitor , 0.1-0.5 parts by weight platinum catalyst.

Example 6

The difference between Example 6 and Example 3 is that the raw materials are weighed according to the following parts by weight: 2 parts by weight of the modified silicone resin prepared in Example 2 , 10 parts by weight of methyl vinyl MQ silicone resin , 40 parts by weight of micron-sized silver powder, 8 parts by weight of nano-sized low-temperature sintered silver powder , 1 part by weight of 3-(methacryloyloxy)propyltrimethoxysilane, 1 part by weight of borate coupling agent, 4 parts by weight solvent, 0.1 parts by weight inhibitor, 0.1-0.5 parts by weight platinum catalyst.

Example 7

The difference between Example 7 and Example 3 is that the raw materials are weighed according to the following parts by weight: 2 parts by weight of the modified silicone resin prepared in Example 2, 10 parts by weight of methyl vinyl MQ silicone resin , 24 parts by weight of micron-sized silver powder, 24 parts by weight of nano-sized low-temperature sintered silver powder, 1 part by weight of 3-(methacryloyloxy)propyl trimethoxysilane, 1 part by weight of borate coupling agent, 4 parts by weight Part solvent, 0.1 part by weight inhibitor, 0.1-0.5 part by weight platinum catalyst.

Example 8

The difference between Example 8 and Example 3 is that the raw materials are weighed according to the following parts by weight: 2 parts by weight of the modified silicone resin prepared in Example 2, 10 parts by weight of methyl vinyl MQ silicone resin , 48 parts by weight of nano-scale low-temperature sintering type silver powder , 1 part by weight of 3-(methacryloxy) propyl trimethoxysilane, 1 part by weight of borate coupling agent, 4 parts by weight of solvent, 0.1 part by weight of inhibitor , 0.1-0.5 parts by weight platinum catalyst.

The conductive adhesives prepared in the above-mentioned Examples 3-8 are sequentially recorded as samples 1-6. Take the commercially available addition-type silicone conductive adhesive with the brand name 3303G produced by a Japanese company as comparative example 1; take the commercially available addition-type silicone conductive adhesive with the brand name XA-5940 produced by a Japanese company as comparative example 2. According to the national standard GB/T 35494, the performance of samples 1-6 and comparative examples 1-2 were tested. The test items included curing conditions, volume resistance, hardness, elongation, ceramic/glass shear strength, gold-plated bracket and plated Table 1 shows the test results of the tensile force of the silver chip and the number of times the drop resistance was dropped from a height of 1 meter.

Table 1

It can be seen from Table 1 that compared with Comparative Example 1 and Comparative Example 2, Samples 1, 2, 4, and 5 have excellent adhesive strength, electrical conductivity, flexibility, and drop resistance. In addition, different resin synthesis methods, the selection of different types of silver powder, and the selection of different acrylate-modified silicone resins will all have an impact on the performance of the conductive adhesive.

It can be seen from the above examples that by adding the acryloxy-modified silicone resin containing multiple polar groups to the conductive adhesive, the bonding strength of the conductive adhesive to the substrate can be improved, thereby achieving a higher Good anti-drop performance of crystal devices improves the mechanical reliability of crystal devices. At the same time, the flexibility of the conductive adhesive can be maintained. On the other hand, by introducing nano-scale low-temperature sintered silver powder into the conductive adhesive, the nano-scale low-temperature sintered silver powder in the adhesive can be partially welded to the bonded metal substrate during high-temperature curing, thereby Greatly improve the cohesion of the conductive adhesive itself and its bonding performance with the substrate to be bonded.

The series of embodiments listed above are only specific implementation descriptions for the feasible implementation of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent implementations or changes that do not depart from the process of the present invention All should be included within the protection scope of the present invention.

For the same and similar parts among the various embodiments in this specification, refer to each other. The embodiments of the present invention described above are not intended to limit the protection scope of the present invention.

Claims (13)

1. A modified silicone resin for preparing conductive adhesive, characterized in that, the structural formula of the modified silicone resin is:

or,

Wherein, Me is H or CH ₃ , m is an integer of 100-10000, and n is an integer of 1-5. 2. The modified silicone resin according to claim 1, characterized in that, the modified silicone resin has a characteristic absorption peak of a carbon-oxygen single bond within a wavelength of 8um ± 0.5um, and a wavelength of 6um ± 0.5um There are characteristic absorption peaks of carbon-oxygen double bonds within the range, and stretching vibration absorption peaks of carbon-hydrogen bonds within the wavelength range of 3um±0.5um. 3. A preparation method of modified silicone resin, characterized in that, the method comprises: Put the acrylic resin terminated with acryloyloxy group and hydrogen-containing silicone oil in the reaction solvent, and carry out the addition reaction under the action of the inhibitor and the catalyst; The modified silicone resin is extracted from the reaction product. 4. method according to claim 3, is characterized in that, described extracting modified silicone resin from reaction product, comprises: Distill the reaction solvent and small molecule reactants from the reaction product under low pressure; add activated carbon to absorb the residual catalyst; Activated carbon was removed by filtration to obtain a modified silicone resin liquid. 5. The method according to claim 3, characterized in that, the molar ratio of the H group in the hydrogen-containing silicone oil to the acryloxy group in the acrylic resin terminated with acryloxy group is 8:1-1:1. 6. The method according to claim 3, characterized in that, the structural formula of the acrylic resin terminated with acryloyloxy group is:

Wherein, n is an integer of 1-5. 7. method according to claim 3, is characterized in that, the structural formula of described hydrogen-containing silicone oil is:

Wherein, Me is H or CH ₃ , and m is an integer of 100-10000. 8. The method according to claim 3, characterized in that the reaction temperature of the addition reaction is 100°C-200°C. 9. A conductive adhesive, characterized in that, comprising: 0.5-5 parts by weight of the modified silicone resin described in claim 1, 5-15 parts by weight of methyl vinyl MQ silicone resin, 0-90 parts by weight of micron silver powder, and 1-50 parts by weight of nano-level low-temperature sintered type Silver powder, 0.1-1 parts by weight of 3-(methacryloxy)propyltrimethoxysilane, 0.1-1 parts by weight of borate coupling agent, 1-10 parts by weight of solvent, 0.1-0.5 parts by weight of inhibitor, 0.1-0.5 parts by weight platinum catalyst. 10. The conductive adhesive according to claim 9, wherein the methyl vinyl MQ silicone resin comprises vinyl, monofunctional siloxane chains R ₃ SiO _1/2 and tetrafunctional Network polysiloxane of siloxane chains SiO _4/2 . 11. The conductive adhesive according to claim 9, wherein the inhibitor is selected from the group consisting of diallyl maleate, diethyl fumarate, acetylene alcohol, 1-ethynyl-1-ring Any one or more of hexanols. 12. The conductive adhesive according to claim 9, wherein the platinum catalyst is one or more of chloroplatinic acid catalysts and Castel platinum catalysts. 13. A preparation method of conductive adhesive, characterized in that, comprising: Weigh 0.5-5 parts by weight of the modified silicone resin described in claim 1, 5-15 parts by weight of methyl vinyl MQ silicone resin, 0-90 parts by weight of micron silver powder, 1-50 parts by weight of nano-level low temperature Sintered silver powder, 0.1-1 parts by weight of 3-(methacryloxy)propyltrimethoxysilane, 0.1-1 parts by weight of borate coupling agent, 1-10 parts by weight of solvent, 0.1-0.5 parts by weight of inhibitor agent, 0.1-0.5 parts by weight platinum catalyst; Add the weighed modified silicone resin, methyl vinyl MQ silicone resin, micron-sized silver powder, nano-sized low-temperature sintered silver powder, inhibitor and part of the solvent into the mixer in sequence, and stir for 2-4 hours; Put the stirred material into a three-roll mill to grind and disperse to obtain a mixed material; Dissolve the weighed platinum catalyst, 3-(methacryloyloxy)propyltrimethoxysilane and borate coupling agent in the remaining solvent, add them to the mixed material, and grind and disperse through the grinder After that, it is added to the mixer and stirred to obtain the mature material; Adjust the viscosity of the mature material to the target value, filter, and vacuum defoam to obtain a conductive adhesive.

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