Silver sintering paste composition

Abstract

The present invention relates to a silver sintering paste composition and, more specifically, to a silver sintering paste composition comprising silver powder, an acid additive, and at least one hydrophilic organic solvent. The silver sintering paste composition of the present invention can have excellent printability, reduced drying shrinkage, and increased working life in a printing process.

Description

Silver paste composition for sintering

[0001] The present invention relates to a silver paste composition for sintering bonding, and more particularly, to a silver paste composition for sintering bonding whose working life can be increased.

[0002] Recent advancements in the electronic component industry have led to weight reduction, higher capacity, and higher reliability in components. In particular, conductive materials used in semiconductor packaging are undergoing refinement in patterns and line widths. Consequently, the particle size of the filler material in the screen printing process for conductive materials is limited. Large particles used in the printing process, or particle agglomeration, can cause scratches on the surface of the printed material, potentially leading to product defects. Typically, binder-free conductive pastes containing nanomaterials experience partial cracking during the drying process due to cohesion between nanoparticles, and significant volumetric shrinkage (drying shrinkage) occurs during the drying process. Specifically, when only spherical metal powders are used, printability is excellent, but the particle shape results in a large surface area in contact with the solvent, resulting in significant drying shrinkage during the solvent evaporation process. If drying shrinkage is significant, the pressure may not be properly distributed to the dried body during pressure sintering after drying, which may prevent smooth sintering and may result in destruction of the printed body.

[0003] An alternative to reducing cracking and drying shrinkage in binder-free conductive pastes is to use micro-sized or flake-type metal powders in a high-filling ratio of at least 85 wt% of the total weight of the conductive paste. However, the use of micro-sized metal powders has limitations in printing fine patterns. Furthermore, the use of flake-type metal powders can lead to uneven particle distribution on the printing surface, which reduces printability. In addition, the low thixotropy of the paste can cause the paste to stretch due to its elongational rheological properties when the squeegee is raised after printing, which can cause it to smear on non-target areas or the printed pattern. If the paste has poor printability, the printed surface may not be flat and may exhibit tilt, pores, or crafting. These can lead to problems such as low bonding strength and low reliability of the applied product after the sintering process.

[0004] Therefore, there is a need to develop a conductive paste that can secure printability while reducing drying shrinkage by using spherical type metal powder as a metal filler.

[0005] Furthermore, in the printing process of applying conductive paste to a PCB, the conductive paste is repeatedly printed on a large number of PCBs, and the PCBs printed with the conductive paste are exposed to air until they enter the curing process. Therefore, the conductive paste must not dry out quickly due to solvent volatilization. Therefore, there is a need to increase the working life of the conductive paste in the printing process.

[0006] The present inventors have conducted research to increase the working life of a conductive paste that utilizes spherical silver powder as a metal filler and adds a specific acid additive to ensure printability and reduce drying shrinkage. As a result, the inventors have completed the present invention by discovering that the working life of a conductive paste can be increased when a specific hydrophilic organic solvent is added to a conductive paste composition that uses spherical silver powder and adds a specific acid additive.

[0007] The present invention aims to provide a silver paste composition for sintering bonding, which can increase the working life.

[0008] The purpose of the present invention is not limited to the aforementioned purposes, and other unmentioned purposes and advantages of the present invention can be understood through the following description and will be more clearly understood through the embodiments of the present invention. Furthermore, it will be readily apparent that the purposes and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0009] In order to achieve the above object, according to one aspect of the present invention, a silver paste composition for sintering bonding comprises silver powder and an organic solvent, wherein the organic solvent comprises an acid additive and at least one hydrophilic organic solvent, and the hydrophilic organic solvent is contained in an amount of 6 to 15 wt% based on the total composition, and can satisfy the following relationship (1):

[0010] Relationship (1): [ ( Vf - Vi ) / Vi ] × 100 (%) ≤ 22

[0011] The above Vi is the initial viscosity of the silver paste composition for sintering at room temperature, and Vf is the viscosity of the silver paste composition for sintering after being left at room temperature for 8 hours.

[0012] The silver paste composition for sintering bonding can additionally satisfy the following relationship (2):

[0013] Relationship (2): [ ( V800 - Vi ) / Vi ] × 100 (%) ≤ 5

[0014] The above Vi is the initial viscosity of the silver paste composition for sintering bonding at room temperature, and V800 means the viscosity of the silver paste composition for sintering bonding after 800 printings at room temperature.

[0015] The above organic solvent may further include at least one hydrophobic organic solvent.

[0016] The above organic solvent may contain carboxylic acid as an acid additive.

[0017] The carboxylic acid may be oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, 2,2-bis(hydroxymethyl)propionic acid, itaconic acid, diglycolic acid, boric acid, ethylenediaminetetraacetic acid, or a combination thereof.

[0018] The above silver powder may include spherical silver powder.

[0019] The average particle size of the above silver powder (D 50 ) can be from 200 nm to 900 nm.

[0020] The above silver paste composition for sintering bonding may have a drying shrinkage rate of 0.5% to 30% after drying.

[0021] When the silver paste composition for sintering bonding of the present invention is used, not only is printability excellent and drying shrinkage reduced, but the working life of the silver paste composition for sintering bonding can be increased in the printing process.

[0022] The effects of the present invention are not limited to those mentioned above, and other effects not mentioned will be readily apparent to those skilled in the art from the description of the claims. In addition to the effects described above, the effects of the present invention are further described below along with the description of the steps involved in implementing the invention.

[0023] Figure 1 shows the change in viscosity according to the number of printings of the silver paste composition.

[0024] The aforementioned purposes, features, and advantages are described in detail below with reference to the present specification, thereby enabling those skilled in the art to readily implement the technical concepts of the present invention. In describing the present invention, detailed descriptions of known technologies related to the present invention will be omitted if they are deemed to unnecessarily obscure the gist of the invention.

[0025] In describing this specification, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of this specification, the detailed description is omitted.

[0026] In this specification, when a component is described as “including,” “having,” “consisting of,” “arranged,” or “equipped,” other parts may be added, unless “only” is used. When a component is described as singular, the plural is also included unless otherwise explicitly stated.

[0027] When it is said in this specification that an element is positioned "on" another element, this includes not only cases where the element is in contact with the other element, but also cases where another element exists between the elements.

[0028] Hereinafter, the present invention will be described in more detail.

[0029] According to one aspect of the present invention, the present invention provides a silver paste composition for sintering bonding, which comprises silver powder and an organic solvent, wherein the organic solvent comprises an acid additive and at least one hydrophilic organic solvent, and the hydrophilic organic solvent is contained in an amount of 6 to 15 wt% based on the total composition, and satisfies the following relational expression (1).

[0030] Relationship (1): [ ( Vf - Vi ) / Vi ] × 100 (%) ≤ 22

[0031] The above Vi is the initial viscosity of the silver paste composition for sintering at room temperature, and Vf is the viscosity of the silver paste composition for sintering after being left at room temperature for 8 hours.

[0032] A silver paste composition for sintering according to one aspect of the present invention can additionally satisfy the following relationship (2).

[0033] Relationship (2): [ ( V800 - Vi ) / Vi ] × 100 (%) ≤ 5

[0034] The above Vi is the initial viscosity of the silver paste composition for sintering bonding at room temperature, and V800 means the viscosity of the silver paste composition for sintering bonding after 800 printings at room temperature.

[0035]

[0036] In this specification, the term 'sintering' refers to a phenomenon in which powders that have been pressurized into an appropriate shape are heated to firmly adhere to each other and solidify, and 'sintering bonding' refers to bonding using sintering. The most representative method for replacing the existing solder alloy as a chip bonding material for power semiconductor modules is the sintering technology using silver (Ag) and copper (Cu) paste. Silver sintering technology is a bonding method using nano- or micro-sized particles, and has excellent high-temperature stability, thermal / electrical conductivity, and long-term reliability. Sintering methods include normal sintering, pressure sintering, reaction sintering, and isostatic sintering, and in a specific embodiment of the present invention, the silver paste composition for sintering bonding of the present invention is used for pressure sintering, but is not limited thereto.

[0037] In this specification, the term 'silver paste' means a conductive paste in which silver powder is used as a filler.

[0038] In one embodiment of the present invention, the silver powder may include spherical silver powder. Unlike flake-type silver powder, which has low printability but low porosity, thus high reliability, and excellent thermal properties and bonding strength, spherical silver powder is known to have excellent printability but may cause cracks during the drying process and have high porosity after sintering, which may reduce reliability. The present inventors have found that by adding a specific acid additive to a conductive paste composition using spherical silver powder as a silver filler, a necking phenomenon is induced between some particles during the drying process, thereby reducing drying shrinkage, and exhibiting high sintering shrinkage and low porosity during the subsequent pressure sintering process.

[0039] In addition, the inventors of the present invention have found that the working life of a conductive paste composition in a printing process can be increased by using spherical silver powder as a filler and adding a specific hydrophilic organic solvent to the conductive paste composition to which a specific acid additive is added.

[0040] Therefore, the silver paste composition for sintering bonding of the present invention has excellent printability, is stable during the drying process, and has excellent physical properties after sintering, and can be used with high usability because its working life is increased in the printing process.

[0041] The silver powder used in the present invention is a sintered powder containing fine particles of 1 μm or less, and may be a sintered powder containing a metal in which some of the particles forming the fine particles are partially coated with a capping agent. The 'capping agent' can reduce the agglomeration of the metal particles and prevent an increase in the sintering temperature of the sintered powder.

[0042] In one embodiment of the present invention, the average particle size (D) of the silver powder described above 50) may be 10 nm to 1000 nm, and more specifically, 10 nm to 1000 nm, 10 nm to 800 nm, 10 nm to 600 nm, 10 nm to 400 nm, 10 nm to 300 nm, 10 nm to 280 nm, 50 nm to 1000 nm, 50 nm to 800 nm, 50 nm to 600 nm, 50 nm to 400 nm, 50 nm to 300 nm, 50 nm to 280 nm, 100 nm to 1000 nm, 100 nm to 800 nm, 100 nm to 600 nm, 100 nm to 400 nm, 100 nm to 300 nm, 100 nm to 280 nm, 150 nm to 1000 nm, 150 nm to 800 nm, 150 nm to 600 nm, 150 nm to 400 nm, 150 nm to 300 nm, 150 nm to 280 nm, 200 nm to 1000 nm, 200 nm to 900 nm, 200 nm to 800 nm, 200 nm to 700 nm, 200 nm to 600 nm, 200 nm to 500 nm, 200 nm to 400 nm, 200 nm to 300 nm, 200 nm to 280 nm, 250 nm to 1000 nm, 250 nm to 800 nm, 250 nm to 600 nm, 250 nm to 400 nm, 250 nm to 300 nm, 250 nm to 280 nm, 260 nm to 1000 nm, 260 nm to 800 nm, 260 nm to 600 nm, 260 nm to 400 nm, 260 nm to 300 nm, or 260 nm to 280 nm, more specifically 270 nm, but is not limited thereto.

[0043] In this specification, the term "organic solvent" refers to an organic solvent added to control the fluidity of the silver paste composition of the present invention, and generally refers to all organic solvents that can be used industrially. The viscosity of the paste composition can be significantly affected depending on the content of the organic solvent.

[0044] In one embodiment of the present invention, the organic solvent described above may be water, hydrocarbons, alcohols, ethers, esters, acetates, ketones, glycol solvents, or a mixed solvent thereof.

[0045] The organic solvent described above may be, but is not limited to, toluene, benzene, octanol, decanol, 2-methyl-1,3-propanediol, 1,3-butanediol, terpineol (α-terpineol, β-terpineol, γ-terpineol), terpineol acetate, dihydroterpineol, dihydroterpineol acetate, carbitol, butyl carbitol, cellosolve, butyl cellosolve, butyl carbitol acetate, cellosolve acetate, ethylene glycol, propylene glycol, ethylene glycol diacetate, propylene glycol diacetate, or a mixed solvent thereof.

[0046] In one embodiment of the present invention, the hydrophilic organic solvent described above may include, but is not limited to, 2-methyl-1,3-propanediol, 1,3-butanediol, or a combination thereof.

[0047] The content of the hydrophilic organic solvent described above may be 6 wt% to 15 wt% of the total composition. More specifically, the content of the hydrophilic organic solvent described above may be 6 wt% to 15 wt%, 6 wt% to 14 wt%, 6 wt% to 13 wt%, 7 wt% to 15 wt%, 7 wt% to 14 wt%, 7 wt% to 13 wt%, 8 wt% to 15 wt%, 8 wt% to 14 wt%, 8 wt% to 13 wt%, 9 wt% to 15 wt%, 9 wt% to 14 wt%, 9 wt% to 13 wt%, 10 wt% to 15 wt%, 10 wt% to 14 wt%, 10 wt% to 13 wt%, but is not limited thereto.

[0048] If the content of the hydrophilic organic solvent described above is less than 6 wt% of the total composition, there is a problem that the working life of the silver paste composition is short, about 8 hours. In addition, if the content of the hydrophilic organic solvent described above is more than 15 wt% of the total composition, the viscosity of the silver paste composition increases, making it difficult to derive viscosity and thixotropic index (TI) suitable for printability. In addition, due to the high volatilization temperature, sufficient drying is not achieved during the drying process, and there is a problem that the paste does not enter the initial sintering stage.

[0049] In one embodiment of the present invention, the silver paste composition for sintering bonding can have an increased working life in a printing process. More specifically, the silver paste composition for sintering bonding can have an increased working life in a printing process compared to a case where the composition does not include a specific hydrophilic organic solvent in a specific content ratio.

[0050]

[0051] In one embodiment of the present invention, the organic solvent described above may further include at least one hydrophobic organic solvent. The hydrophobic organic solvent described above may include, but is not limited to, α-terpineol, propylene glycol, or a combination thereof. Propylene glycol is a solvent with a low boiling point, which helps the silver paste composition to dry at a low drying temperature (e.g., 130°C). In addition, α-terpineol improves printability and helps the sintering of the silver powder. In a specific embodiment of the present invention, the hydrophobic organic solvent described above may be, but is not limited to, a combination of α-terpineol and propylene glycol.

[0052] The content of the hydrophobic organic solvent described above may be 5 wt% to 14 wt% based on the total composition. More specifically, the content of the hydrophobic organic solvent described above may be 5 wt% to 14 wt%, 5 wt% to 13 wt%, 5 wt% to 12 wt%, 5 wt% to 11 wt%, 5 wt% to 10 wt%, 5 wt% to 9 wt%, 5 wt% to 8 wt%, 5 wt% to 7 wt%, 6 wt% to 14 wt%, 7 wt% to 14 wt%, 8 wt% to 14 wt%, 9 wt% to 14 wt%, 10 wt% to 14 wt%, 11 wt% to 14 wt%, 12 wt% to 14 wt%, 5.5 wt% to 13 wt%, 6 wt% to 12 wt%, 6.5 wt% to 11 wt%, or 7 wt% to 10 wt%, but is not limited thereto.

[0053]

[0054] In one embodiment of the present invention, the organic solvent described above may include carboxylic acid as an acid additive.

[0055] The above-mentioned carboxylic acid is a carboxylic acid having an aliphatic chain of 1 to 26 carbon atoms, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, 2,2-bis(hydroxymethyl)propionic acid, itaconic acid, diglycolic acid, boric acid, ethylenediaminetetraacetic acid, oleic acid, stearic acid, sebacic acid, salicylic acid, citric acid, dodecanedioic acid, maleic acid, palmitic acid, suberic acid. acid) or a combination thereof, but is not limited thereto. Depending on the amount or type of the acid additive present, the viscosity of the paste composition or the thickness of the dried film may vary, and two or three or more types of carboxylic acids may be combined and added as an acid additive as needed.

[0056] In specific embodiments of the present invention, the carboxylic acid described above may be, but is not limited to, malonic acid, oxalic acid, succinic acid, or a combination of malonic acid and succinic acid.

[0057] In one embodiment of the present invention, the content of the above-described acid additive may be 0.01 wt% to 10 wt% relative to the entire composition. More specifically, the content of the above-described acid additive is 0.01 wt% to 10 wt%, 0.01 wt% to 7 wt%, 0.01 wt% to 5 wt%, 0.01 wt% to 3 wt%, 0.05 wt% to 10 wt%, 0.05 wt% to 7 wt%, 0.05 wt% to 5 wt%, 0.05 wt% to 3 wt%, 0.05 wt% to 1 wt%, 0.1 wt% to 10 wt%, 0.1 wt% to 7 wt%, 0.1 wt% to 5 wt%, 0.1 wt% to 3 wt%, 0.5 wt% to 10 wt%, 0.5 wt% to 7 wt%, 0.5 wt% to 5 wt%, 0.5 wt% to 3 wt%, 1 wt% to 10 wt%, It may be 1 wt% to 7 wt%, 1 wt% to 5 wt%, 1 wt% to 3 wt%, 1.5 wt% to 10 wt%, 1.5 wt% to 7 wt%, 1.5 wt% to 5 wt%, or 1.5 wt% to 3 wt%, but is not limited thereto. In a specific embodiment of the present invention, the organic solvent described above includes carboxylic acid in an amount of 0.05 wt% relative to the total composition, but is not limited thereto.

[0058] In one embodiment of the present invention, the organic solvent described above may include an additive. More specifically, the organic solvent described above may additionally include one or more additives selected from the group consisting of a surfactant, a coupling agent, an antioxidant, a curing accelerator, a leveling agent, an antifoaming agent, a fluidity regulator, and a dispersing agent.

[0059] In one embodiment of the present invention, the organic solvent described above may include a dispersant as an additive. The dispersant stabilizes the filler by ensuring that the solid particles in the paste composition are evenly distributed in the liquid medium, thereby improving long-term stability. The dispersant prevents particle agglomeration through various mechanisms, such as electrostatic effects and steric effects. Examples of dispersants that can be used include, but are not limited to, BYK-110, DIPSERBYK-180, or combinations thereof from BYK.

[0060] In one embodiment of the present invention, the organic solvent described above may contain a dispersant as an additive in an amount of 0.05 wt% to 2 wt% based on the total silver paste composition. More specifically, the organic solvent described above may contain a dispersant as an additive in an amount of 0.05 wt% to 2 wt%, 0.05 wt% to 1 wt%, 0.05 wt% to 0.5 wt%, 0.05 wt% to 0.3 wt%, 0.1 wt% to 2 wt%, 0.1 wt% to 1 wt%, 0.1 wt% to 0.5 wt%, or 0.1 wt% to 0.3 wt% based on the total silver paste composition, but is not limited thereto. In a specific embodiment of the present invention, the organic solvent described above may contain a dispersant in an amount of 0.2 wt% based on the total composition, but is not limited thereto.

[0061] In one embodiment of the present invention, the organic solvent described above may include a fluidity regulator as an additive. The fluidity regulator is a substance added to control the viscosity of the paste, and depending on the amount or type of the fluidity regulator present, the viscosity of the paste, the thickness of the coating film after printing and drying using the paste, and the presence or absence of sedimentation may vary. The fluidity regulator may be a modified urea-based, amine-amide-based, amine-based, urea / acrylate-based, or modified ester-based agent, and examples thereof include, but are not limited to, RHEOBYK-425, RHEOBYK-T 1000VF, RHEOBYK-L 1400 VF, RHEOBYK-H 3300 VF from BYK, H1335, HY124 from Spectrum, or a combination thereof.

[0062] In one embodiment of the present invention, the weight ratio of the above-described silver powder and organic solvent may be 1:1 to 9:1. When the weight ratio of the organic solvent is less than 10 wt%, the filling of the silver powder may not be smooth, making it difficult to manufacture the silver paste composition. On the other hand, when the weight ratio of the organic solvent exceeds 50 wt%, the viscosity may be low, causing the silver paste composition to spread when the metal mask is separated, and the drying time may be long, drying shrinkage may be large, and the thickness may become thin or cracks may occur after drying.

[0063] More specifically, the weight ratio of the silver powder and the organic solvent is 1:1 to 9:1, 1:1 to 85:15, 1:1 to 82.5:17.5, 1:1 to 81:19, 65:35 to 9:1, 65:35 to 85:15, 65:35 to 82.5:17.5, 65:35 to 81:19, 75:15 to 9:1, 75:15 to 85:15, 75:15 to 82.5:17.5, 75:15 to 81:19, 77.5:22.5 to 9:1, 77.5:22.5 to 85:15, 77.5:22.5 to 82.5:17.5, or It may be, but is not limited to, 77.5:22.5 to 81:19, or 80:20.

[0064] In one embodiment of the present invention, the silver paste composition for sintering bonding of the present invention may be binder-free.

[0065] In this specification, the term 'binder-free' means that the silver paste composition does not contain a binder.

[0066] In this specification, the term 'binder' refers to a substance in which a polymer resin is dissolved in a solvent at a certain ratio to improve the fluidity of the paste composition or to allow the paste composition to adhere to a substrate and to control physical properties such as strength and durability. In the case of a typical silver paste composition, one or more types of thermosetting resins or thermoplastic resins such as epoxy resin, phenol resin, saturated polyester resin, unsaturated polyester resin, polyimide resin, polyamide resin, and acrylic resin have been mixed and used as a binder. However, if the binder is well mixed with the metal powder, it may interfere with the contact between the metal particles, thereby reducing the conductivity, and the porosity may increase during sintering, reducing the adhesive strength and thus lowering the reliability of the applied product. In addition, the binder may be decomposed by heat during the sintering process, generating fumes that may contaminate the substrate.

[0067] In one embodiment of the present invention, the silver paste composition for sintering bonding of the present invention can have reduced drying shrinkage. More specifically, the silver paste composition for sintering bonding can have reduced drying shrinkage compared to a case where an acid additive including a carboxylic acid is not added.

[0068] In this specification, the term "drying shrinkage" refers to a phenomenon that commonly occurs when solvents are removed from solid materials such as metal particles, concrete, and ceramics. Drying shrinkage can be influenced by factors such as particle shape, size, and surface area.

[0069] The silver paste composition for sintering bonding of the present invention has the effect of reducing drying shrinkage by including carboxylic acid as an acid additive. This effect is due to the fact that during the drying process of the conductive paste, the decomposition of the acid additive induces a weak necking phenomenon between metal particles, thereby reducing the contact area between the metal particles.

[0070] In one embodiment of the present invention, the drying shrinkage rate of the silver paste composition for sintering bonding of the present invention after drying may be 0.5% to 30%, and more specifically, 0.5% to 30%, 0.5% to 27%, 0.5% to 25%, 0.5% to 20%, 0.5% to 18%, 1% to 30%, 1% to 27%, 1% to 25%, 1% to 20%, 1% to 18%, 5% to 30%, 5% to 27%, 5% to 25%, 5% to 20%, 5% to 18%, 10% to 30%, 10% to 27%, 10% to 25%, 10% to 20%, 10% to 18%, 15% to It may be, but is not limited to, 30%, 15% to 27%, 15% to 25%, 15% to 20%, 15% to 18%, 17% to 30%, 17% to 27%, 17% to 25%, 17% to 20%, or 17% to 18%.

[0071] In this specification, the term 'drying shrinkage' means the shrinkage when the printed paste dries, and is calculated as follows.

[0072] Drying shrinkage rate (%) = [1-(thickness of silver paste composition after drying (㎛) / thickness of printing mask (㎛))] x 100

[0073] Therefore, the smaller the drying shrinkage rate, the less drying shrinkage occurs, and accordingly, the sintering shrinkage rate in the subsequent sintering bonding can increase, thereby increasing the reliability of the applied product.

[0074] In one embodiment of the present invention, the silver paste composition for sintering bonding of the present invention may have a sintering shrinkage rate of 55% to 75% after pressure sintering, and more specifically, 55% to 75%, 55% to 72%, 55% to 69%, 55% to 67%, 55% to 66%, 55% to 65%, 55% to 64%, 58% to 75%, 58% to 72%, 58% to 69%, 58% to 67%, 58% to 66%, 58% to 65%, 58% to 64%, 61% to 75%, 61% to 72%, 61% to 69%, 61% to 67%, 61% to 66%, 61% to It may be, but is not limited to, 65%, 61% to 64%, 63% to 75%, 63% to 72%, 63% to 69%, 63% to 67%, 63% to 66%, 63% to 65%, or 63% to 64%.

[0075] In this specification, the term 'sintering shrinkage' means the shrinkage when the dried paste is sintered, and is calculated as follows.

[0076] Sintering shrinkage (%) = [1-(thickness after sintering of silver paste composition (㎛) / dry thickness of silver paste composition (㎛)] x 100

[0077] If the sintering shrinkage of the conductive paste is low, the chip may be destroyed or dense bonding may not be achieved, which may result in a decrease in the conductivity or reliability of the applied product.

[0078] In one embodiment of the present invention, the above-described pressure sintering can be performed at a temperature of 150°C to 350°C. More specifically, the above-described pressure sintering may be performed at a temperature of 150°C to 350°C, 150°C to 300°C, 150°C to 280°C, 150°C to 260°C, 200°C to 350°C, 200°C to 300°C, 200°C to 280°C, 200°C to 260°C, 220°C to 350°C, 220°C to 300°C, 220°C to 280°C, 220°C to 260°C, 240°C to 350°C, 240°C to 300°C, 240°C to 280°C, or 240°C to 260°C, and most specifically, may be 250°C, but is not limited thereto.

[0079] In one embodiment of the present invention, the above-described pressure sintering may be performed at a pressure of 0.1 MPa to 20 MPa. More specifically, the above-described pressure sintering may be 0.1 MPa to 20 MPa, 0.1 MPa to 15 MPa, 0.1 MPa to 12 MPa, 0.1 MPa to 10 MPa, 0.2 MPa to 20 MPa, 0.2 MPa to 15 MPa, 0.2 MPa to 12 MPa, 0.2 MPa to 10 MPa, 0.3 MPa to 20 MPa, 0.3 MPa to 15 MPa, 0.3 MPa to 12 MPa, or 0.3 MPa to 10 MPa, and more specifically, may be 0.4 MPa, but is not limited thereto.

[0080] In one embodiment of the present invention, the silver paste composition for sintering bonding of the present invention had a good printing state and no cracks on the surface after printing.

[0081] In one embodiment of the present invention, the silver paste composition for sintering bonding of the present invention, when dried at 130°C for 30 minutes after printing, had a large dry thickness, so that stability was maintained when pressure was applied during the bonding process, and a decrease in reliability due to an increase in internal porosity was prevented.

[0082] In one embodiment of the present invention, the silver paste composition for sintering bonding of the present invention was dried at 130°C for 30 minutes after printing, and then subjected to pressure sintering at 250°C for 180 seconds without a heating section at a pressure of 0.4 MPa, and the sintering shrinkage ratio was 60% or more, thereby preventing chip breakage and improving reliability.

[0083] Therefore, the silver paste composition for sintering bonding of the present invention can be usefully used for bonding in the production of electronic products such as automobile electrical components, IT devices, and home appliances, and specifically, can be applied in the production of electronic control devices (power modules, thermoelectric modules), chip components, piezoelectric components of electronic ceramics, membranes of flexible circuits, RFID tags, touch screens, and the like.

[0084]

[0085] Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are merely illustrative of the present invention, and the scope of the present invention is not limited to the following examples.

[0086]

[0087] [Example]

[0088] Example 1

[0089] A silver paste composition was prepared by mixing a silver filler, a hydrophilic organic solvent, a hydrophobic organic solvent, an acid additive, and a dispersant.

[0090] The average particle size (D) of silver filler is 270 nm. 50) was used as a spherical type silver powder (Metalor Technologies, product name: P620-7), and the silver filler was used at a weight ratio of 80 wt% relative to the total silver paste composition.

[0091] The composition of the organic solvent used is shown in Table 1 below. As shown in Table 1, 12.75 wt% of 2-methyl-1,3-propanedeol was used as a hydrophilic organic solvent relative to the entire silver paste composition. In addition, 3 wt% of propylene glycol relative to the entire silver paste composition and 4 wt% of α-terpineol relative to the entire silver paste composition were used as hydrophobic organic solvents.

[0092] As a acid additive, 0.05 wt% of malonic acid was used relative to the entire silver paste composition. As a dispersant, 0.2 wt% of DIPSERBYK-180 relative to the entire silver paste composition was used.

[0093] [Table 1]

[0094]

[0095] First, a hydrophilic organic solvent, a hydrophobic organic solvent, an acid additive, and a dispersant were mixed, and then the mixture was heated in a heating mantle at 80°C for 40 minutes. Specifically, the mixture was heated in a heating mantle at 80°C at 100 rpm for 10 minutes, at 400 rpm for 30 minutes, and then cooled for 1 hour.

[0096] Then, after mixing the organic solvent and silver filler, the mixture was stirred at 1,000 rpm for 2 minutes with a paste mixer, and three roll milling was repeated three times to improve dispersibility, thereby performing a kneading operation. Then, after degassing for 10 minutes, it was stirred again at 1,000 rpm for 1 minute with a paste mixer, thereby producing a silver paste composition for sintering.

[0097]

[0098] Example 2

[0099] A silver paste composition for sintering bonding was prepared in the same manner as in Example 1, except that 10.45 wt% of 2-methyl-1,3-propanedeol was used as a hydrophilic organic solvent relative to the entire silver paste composition, and 2 wt% of propylene glycol relative to the entire silver paste composition and 7.3 wt% of α-terpineol relative to the entire silver paste composition were used as hydrophobic organic solvents.

[0100]

[0101] Comparative example

[0102] A silver paste composition for sintering bonding was prepared in the same manner as in Example 1, except that 5.18 wt% of 2-methyl-1,3-propanedeol was used as a hydrophilic organic solvent relative to the entire silver paste composition, and 4.52 wt% of propylene glycol relative to the entire silver paste composition and 10.05 wt% of α-terpineol relative to the entire silver paste composition were used as hydrophobic organic solvents.

[0103]

[0104] [Experimental Example]

[0105] -Work life evaluation

[0106] In order to evaluate the working life, the silver paste compositions for sintering according to Examples 1, 2 and Comparative Examples were left at room temperature, and then the viscosity (unit: cPs) and thixotropic index (TI) of 0.5 ml of the silver paste compositions for sintering according to Examples 1, 2 and Comparative Examples were measured at 0.5 rpm for 1 minute and 5 rpm for 1 minute using a viscometer (Brookfield Viscometer) at intervals of 4 hours or 2 hours. The results are shown in Tables 2 to 4 below. Since the thixotropic index had a value greater than 6, it was found that the printability would be excellent.

[0107] [Table 2]

[0108]

[0109] [Table 3]

[0110]

[0111] [Table 4]

[0112]

[0113] The working life was determined as the time at which the viscosity of the silver paste composition for sintering bonding increased by less than 25% compared to the initial viscosity, using the viscosity measured at 5 rpm. This is because if the viscosity of the silver paste composition for sintering bonding increased by more than 25% compared to the initial viscosity, a problem of poor printability occurred in which the composition did not completely fill the printing mask holes.

[0114] In the case of Example 1, the viscosity measured after 18 hours increased by approximately 15.8% compared to the initial viscosity, and the viscosity measured after 20 hours increased by approximately 28.1% compared to the initial viscosity. Therefore, the working life of Example 1 was determined to be 18 hours.

[0115] In the case of Example 2, the viscosity measured after 16 hours increased by approximately 21.6% compared to the initial viscosity, and the viscosity measured after 18 hours increased by 37.2% compared to the initial viscosity. Therefore, the working life of Example 2 was determined to be 16 hours.

[0116] In the comparative example, the viscosity measured after 8 hours increased by approximately 22.2% compared to the initial viscosity, and the viscosity measured after 12 hours increased by 50% compared to the initial viscosity. Therefore, the working life of the comparative example was determined to be 18 hours.

[0117] It was found that Examples 1 and 2 showed less change in viscosity over time compared to the comparative example, and that the working life of Examples 1 and 2 increased by more than twice compared to the comparative example.

[0118]

[0119] - Evaluation of viscosity changes according to the number of prints

[0120] 80 g of the silver paste composition for sintering bonding according to Examples 1, 2, and Comparative Examples was repeatedly printed on a printed body using a squeegee at intervals of 30 cm, and the viscosity (unit: cP) and thixotropic index (TI) were measured every 100 times using a viscometer (Brookfield Viscometer) at 0.5 rpm for 1 minute and 5 rpm for 1 minute. The results are shown in Table 5 and Fig. 1 below.

[0121] [Table 5]

[0122]

[0123] As shown in Table 5 and Fig. 1, in the comparative example, the viscosity change rate after 800 printings was approximately 12.7%. However, in the case of Example 1, the viscosity change rate after 800 printings was approximately 2.4%, and in the case of Example 2, the viscosity change rate after 800 printings was approximately 3.2%.

[0124] It was found that the viscosity change rate according to the increase in the number of printings in Examples 1 and 2 was significantly lower than that in the comparative example.

[0125]

[0126] - Room temperature and high temperature adhesion evaluation

[0127] (1) Adhesion test specimen manufacturing process

[0128] (a) Silver paste patterns (area: 4 x 4 mm) were formed by printing a silver paste composition for sintering bonding on a DBC (direct bonded copper) substrate. 2 , thickness: 200 μm) were formed. (b) The formed silver paste patterns were dried in an oven at 130°C for 30 minutes. (c) A silver-coated (Ag coated) copper block (Cu block) was placed on the dried silver paste patterns and pressure-sintered using a hot press at 250°C, 180 s, and 2 MPa.

[0129] (2) Adhesion evaluation

[0130] The adhesion of silver paste patterns was evaluated at room temperature and high temperature (250°C) using die shear test equipment under the conditions of a test speed of 500 μm / s and a shear height of 150 μm.

[0131] [Table 6]

[0132]

[0133] As shown in Table 6, Examples 1 and 2 had significantly superior room temperature and high temperature adhesive strengths compared to the comparative examples.

[0134] Although the present invention has been described in more detail with reference to the embodiments of this specification, this specification is not necessarily limited to these embodiments, and various modifications may be implemented without departing from the technical spirit of this specification. Therefore, the embodiments disclosed in this specification are not intended to limit the technical spirit of this specification, but to explain it, and the scope of the technical spirit of this specification is not limited by these embodiments. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The scope of protection of this specification should be interpreted by the claims, and all technical ideas within a scope equivalent thereto should be interpreted as being included in the scope of rights of this specification.

Claims

1. A silver paste composition for sintering bonding comprising silver powder and an organic solvent, The organic solvent comprises an acid additive and at least one hydrophilic organic solvent, The above hydrophilic organic solvent is contained in an amount of 6 to 15 wt% relative to the total composition, A silver paste composition for sintering bonding, which satisfies the following relational expression (1): Relationship (1): [ ( Vf - Vi ) / Vi ] × 100 (%) ≤ 22 The above Vi is the initial viscosity of the silver paste composition for sintering at room temperature, and Vf is the viscosity of the silver paste composition for sintering after leaving it at room temperature for 8 hours.

2. In the first paragraph, a silver paste composition for sintering bonding that additionally satisfies the following relational expression (2): Relationship (2): [ ( V800 - Vi ) / Vi ] × 100 (%) ≤ 5 The above Vi is the initial viscosity of the silver paste composition for sintering bonding at room temperature, and V800 means the viscosity of the silver paste composition for sintering bonding after 800 printings at room temperature.

3. A silver paste composition for sintering bonding, wherein the organic solvent in claim 1 further includes at least one hydrophobic organic solvent.

4. A silver paste composition for sintering bonding, wherein the organic solvent in claim 1 contains carboxylic acid as an acid additive.

5. In the fourth paragraph, the carboxylic acid is oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, 2,2-bis(hydroxymethyl)propionic acid, itaconic acid, diglycolic acid, boric acid, ethylenediaminetetraacetic acid or a combination thereof, a silver paste composition for sintering bonding.

6. A silver paste composition for sintering bonding, wherein the silver powder in the first paragraph includes spherical silver powder.

7. In the first paragraph, the average particle size (D) of the silver powder 50 ) is 200 nm to 900 nm, a silver paste composition for sintering bonding.

8. In the first paragraph, the silver paste composition for sintering bonding has a drying shrinkage rate of 0.5% to 30% after drying.

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