Preparation method of high-reliability conductive adhesive

Abstract

The invention is applicable to the technical field of adhesive manufacturing, and particularly relates to a preparation method of a high-reliability conductive adhesive, which comprises the following steps of: stirring and blending acrylic resin and macromolecular polyfunctional group acrylic oligomer to form a high-viscosity prepolymer, adding other acrylic resin, a coupling agent, a dispersing agent and a defoaming agent, and uniformly stirring to obtain the high-reliability conductive adhesive. And adding an initiator, a curing agent and an accelerant, stirring and centrifuging, adding 60-85wt% of metal silver powder, stirring and centrifuging again, uniformly mixing and crushing, and vacuumizing to obtain the high-reliability conductive adhesive. According to the preparation method of the high-reliability conductive adhesive provided by the invention, a high-bonding-force and low-modulus resin system is combined with a specific silver powder system of a company, so that the effects of excellent high-temperature bonding force, low modulus and high reliability are realized, and the high-reliability conductive adhesive can be better applied to a conductive patch adhesive of a large chip (3-6mm) and can pass an MSL1 test more easily.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesive manufacturing, and in particular relates to a method for preparing a high-reliability conductive adhesive. Background Art

[0002] With the rapid development of miniaturization and micro-miniaturization of electronic components and high density and high integration of printed circuit boards, conductive adhesive, as a material that can replace lead-tin solder, has become the core basic material of the microelectronics industry, and its importance is becoming increasingly prominent. However, compared with metal solder, conductive adhesive also has some shortcomings in performance, such as high volume resistivity, poor thermal conductivity, insufficient bonding strength, unstable contact resistance, etc., especially after high temperature and high humidity aging experiments, it is easy to produce interface stratification, which leads to failure of bonding and electrical connection, and mechanical properties are reduced. These have become important constraints limiting the application of conductive adhesive in the field of microelectronics assembly. At present, the patch adhesive for large chips (3-6mm) used in domestic semiconductor packaging cannot provide sufficient adhesion and stress absorption in the high reliability test (ML1) after packaging, and the chip and frame and plastic packaging material are often delaminated. Summary of the invention

[0003] The purpose of the present invention is to provide a method for preparing a high-reliability conductive adhesive, aiming to solve the problem that the existing patch adhesive cannot provide sufficiently large adhesion and stress absorption in the high reliability test (ML1) after packaging, and the chip and frame and plastic packaging material are often delaminated.

[0004] The present invention is achieved by providing a method for preparing a high-reliability conductive adhesive, wherein the high-reliability conductive adhesive comprises 60-85wt% of metallic silver powder, 0.1-3wt% of an initiator, 3.0-30wt% of an acrylic prepolymer, 0.5-10wt% of an acrylic resin, 0.1-2wt% of a defoamer, 0.5-8wt% of a plasticizer, 0.2-3.5wt% of a curing agent, 0.1-2wt% of a coupling agent, 0.05-1.5wt% of an accelerator and 0.01-3wt% of a functional additive;

[0005] Acrylic resin and macromolecular multifunctional acrylic oligomer are stirred and blended to form a high-viscosity prepolymer, other acrylic resins, coupling agents, dispersants and defoaming agents are added, initiators, curing agents and accelerators are added, stirred and centrifuged, 60-85wt% of metallic silver powder is added, stirred and centrifuged again, the mixture is evenly crushed, and vacuum is drawn to obtain a high-reliability conductive adhesive.

[0006] Preferably, the coupling agent is KH560 and KH570.

[0007] Preferably, the stirring and blending is carried out at a temperature between 25°C and 70°C, and the duration is 1 to 24 hours.

[0008] Preferably, in the step of adding the initiator, the curing agent and the accelerator and performing stirring and centrifuging, the stirring and centrifuging speed is 1500 revolutions per minute and the duration is 180 seconds.

[0009] Preferably, in the step of stirring and centrifuging again, the stirring and centrifuging speed is 2000 revolutions per minute and the duration is 180 seconds.

[0010] Preferably, in the step of mixing and crushing uniformly, a three-roll mill is used for mixing and crushing, and the material passes through the three-roll mill three times.

[0011] Preferably, in the step of mixing and crushing uniformly, the gaps between the three crushings are 40-20 mm, 30-15 mm and 10-5 mm respectively.

[0012] The preparation method of the high-reliability conductive adhesive provided by the present invention combines a high-adhesion and low-modulus resin system with the company's unique silver powder system to achieve excellent high-temperature adhesion and low modulus, thereby achieving a high-reliability effect. It can be better applied to large chip (3-6mm) conductive patch adhesives, making it easier to pass the MSL1 test. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0014] As an embodiment of the present invention, a method for preparing a high-reliability conductive adhesive is provided, wherein the high-reliability conductive adhesive comprises 60-85wt% of metallic silver powder, 0.1-3wt% of an initiator, 3.0-30wt% of an acrylic prepolymer, 0.5-10wt% of an acrylic resin, 0.1-2wt% of a defoamer, 0.5-8wt% of a plasticizer, 0.2-3.5wt% of a curing agent, 0.1-2wt% of a coupling agent, 0.05-1.5wt% of an accelerator and 0.01-3wt% of a functional additive;

[0015] Acrylic resin and macromolecular multifunctional acrylic oligomer are stirred and blended to form a high-viscosity prepolymer, other acrylic resins, coupling agents, dispersants and defoaming agents are added, initiators, curing agents and accelerators are added, stirred and centrifuged, 60-85wt% of metallic silver powder is added, stirred and centrifuged again, the mixture is evenly crushed, and vacuum is drawn to obtain a high-reliability conductive adhesive.

[0016] In this embodiment, the high reliability conductive adhesive is prepared from the following raw materials based on the total weight of 100%: 60-85wt% of metallic silver powder, 0.1-3% of initiator, 3.0-30wt% of acrylic prepolymer, 0.5-10wt% of acrylic resin, 0.1-2% of defoamer, 0.5-8wt% of plasticizer, 0.2-3.5wt% of curing agent, 0.1-2wt% of coupling agent, 0.05-1.5wt% of accelerator and 0.01-3wt% of functional additive;

[0017] First, the acrylic resin monomer and the macromolecular multifunctional acrylic oligomer are stirred and blended for 1-24 hours (25-70°C) to form a high-viscosity prepolymer, and then other acrylic resins and KH560, KH570 and other dispersants and defoamers are added in a certain proportion, and then the initiator and curing agent accelerator are added, and the mixture is stirred and centrifuged (1500RPM 180S) to make it uniform. Finally, 60-85wt% of metallic silver powder is added, and the mixture is stirred and centrifuged again (2000RPM 180S), and the mixture is mixed and crushed evenly by three rollers for three times, with the first gap (40-20), the second gap (30-15), and the third gap: (10-5mm), and then centrifuged again (2000RPM 180S), vacuumed, and packaged for storage.

[0018] Formula 1, epoxy-modified acrylate oligomer EA1278 ratio 8.2%. Initiator: peroxide (lauroyl peroxide) 0.2%, toughening agent (DM588 double bond chemistry) 3%, acrylic resin monomer SR285 (12.8%), dispersant BYK-204 (0.5%), defoamer BYK-1790 (0.4%), anti-settling agent BYK7410 (0.2%), spherical silver powder 25% (self-made by Dico), flake powder 50%.

[0019] Formula 2: polyurethane acrylic resin RJ421 (9.1%), initiator azobisisobutyronitrile 0.3%, toughening agent HYSZ-51 (2.5%), acrylate monomer SR313A (12.4%), coupling agent KH560 (0.1%), defoaming agent BYK-1790 (0.4%), anti-settling agent BYK7410 (0.2%), spherical silver powder 25%, flake powder 50%.

[0020] Formula 3: Polyurethane acrylic resin oligomer 9.4%: initiator azobisisobutyronitrile 0.3%, toughening agent (styrene-butadiene rubber) 3%, acrylic resin monomer SR217 (11.7%), coupling agent KH560 (0.1%), dispersant BYK-204 (0.5%), spherical silver powder 20% (self-made by Dico), flake powder 55%.

[0021] Formula 4 resin: epoxy modified acrylate oligomer EA1278 (8.3%), initiator: cyclohexanone peroxide 0.2%, toughening agent (polyamide) 4%, acrylic resin monomer SR335-Sartomer (11.2%), coupling agent KH560 (0.1%), coupling agent KH570 (0.1%), dispersant BYK-104 (0.5%), defoaming agent BYK-1790 (0.4%), anti-settling agent BYK7410 (0.2%), spherical silver powder 25% (self-made by Dico), flake powder 50%.

[0022] Formula 5 Resin: polyurethane modified acrylic prepolymer (9.1%), initiator: cyclohexanone peroxide (0.3%), toughening agent (HYSZ-51 (4.2%)), acrylic resin monomer (SR313 (11.9%) dispersant BYK-9076 (0.2%), anti-settling agent BYK7410 (0.3%), spherical silver powder 25% (self-made by Dico), flake powder 49%.

[0023] The experimental data are shown in the following table:

[0024]

[0025]

[0026] High temperature bonding force ≥4kg (2*2mm chip) + Ag, Cu, PPF frame at 260℃ (20S) after testing equipment (dispensing machine dispenses glue and sticks 2*2 chips, after baking, 260℃ (20S) after testing the special thrust machine for patch adhesive bonding force);

[0027] High temperature modulus 100-1000Mpa (260℃) (modulus test of fixed specimens in tension mode of dynamic mechanical analyzer, taking the modulus value at 260℃);

[0028] The modulus at room temperature is 1000-4000Mpa (modulus test of fixed specimens in tension mode of dynamic mechanical analyzer, taking the modulus value at 25°C).

[0029] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a high-reliability conductive adhesive, characterized in that: The high reliability conductive adhesive comprises 60-85wt% of metallic silver powder, 0.1-3wt% of initiator, 3.0-30wt% of acrylic prepolymer, 0.5-10wt% of acrylic resin, 0.1-2wt% of defoamer, 0.5-8wt% of plasticizer, 0.2-3.5wt% of curing agent, 0.1-2wt% of coupling agent, 0.05-1.5wt% of accelerator and 0.01-3wt% of functional additive; Acrylic resin and macromolecular multifunctional acrylic oligomer are stirred and blended to form a high-viscosity prepolymer, other acrylic resins, coupling agents, dispersants and defoaming agents are added, initiators, curing agents and accelerators are added, stirred and centrifuged, 60-85wt% of metallic silver powder is added, stirred and centrifuged again, the mixture is evenly crushed, and vacuum is drawn to obtain a high-reliability conductive adhesive.

2. The method for preparing a high-reliability conductive adhesive according to claim 1, characterized in that: The coupling agents are KH560 and KH570.

3. The method for preparing a high-reliability conductive adhesive according to claim 1, characterized in that: The stirring and blending is carried out at a temperature between 25°C and 70°C, and the duration is 1 to 24 hours.

4. The method for preparing a high-reliability conductive adhesive according to claim 1, characterized in that: In the step of adding the initiator, the curing agent and the accelerator and performing stirring and centrifuging, the stirring and centrifuging speed is 1500 revolutions per minute and the duration is 180 seconds.

5. The method for preparing a high-reliability conductive adhesive according to claim 1, characterized in that: In the step of stirring and centrifuging again, the stirring and centrifuging speed is 2000 rpm and the duration is 180 seconds.

6. The method for preparing a high-reliability conductive adhesive according to claim 1, characterized in that: In the step of mixing and crushing uniformly, a three-roll mill is used for mixing and crushing, and the material passes through the three-roll mill three times.

7. The method for preparing a high-reliability conductive adhesive according to claim 6, characterized in that: In the step of mixing and crushing evenly, the gaps between the three crushings are 40-20mm, 30-15mm and 10-5mm respectively.

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