CN114974656A

CN114974656A - Nano composite low-temperature slurry, preparation method and application thereof

Info

Publication number: CN114974656A
Application number: CN202210614171.8A
Authority: CN
Inventors: 葛大梁; 周训能; 胡军辉
Original assignee: Shenzhen Baroy New Material Technology Co ltd
Current assignee: Shenzhen Baroy New Material Technology Co ltd
Priority date: 2022-05-31
Filing date: 2022-05-31
Publication date: 2022-08-30

Abstract

The invention discloses a nano composite low-temperature slurry which comprises the following components in parts by weight: 1-80 parts of low-temperature alloy powder, 5-80 parts of high-temperature metal powder, 1-80 parts of simple substance nano powder, 2-10 parts of organic solvent, 0-5 parts of activating agent, 0-2 parts of corrosion inhibitor and 0.1-3 parts of thickening agent. The nano composite low-temperature slurry can meet the requirement of sintering at 220 ℃, does not generate remelting in reflow soldering at 260 ℃ after sintering is finished, and is suitable for being used in the field of low-temperature sintering high-temperature service.

Description

Nano composite low-temperature slurry, preparation method and application thereof

Technical Field

The invention belongs to the technical field of conductive paste, and particularly relates to nano composite low-temperature paste, a preparation method and application thereof.

Background

Electronic equipment seen in daily life can not leave a PCB circuit board, can be as small as an electronic watch, a calculator, a general computer, can be as large as a computer, communication electronic equipment and a military weapon system, and as long as electronic devices such as integrated circuits and the like exist, the PCB is used for electrical interconnection among the electronic devices, the PCB provides mechanical support for fixedly assembling various electronic devices such as the integrated circuits and the like, realizes wiring and electrical connection or electrical insulation among various electronic devices such as the integrated circuits and the like, and provides required electrical characteristics such as characteristic impedance and the like. Meanwhile, a solder resist pattern is provided for automatic soldering; and identification characters and graphs are provided for component insertion, inspection and maintenance.

In the technical development of printed circuit boards, with the technological progress of our country, a new generation of printed circuit board products, which are mainly made of the miniaturization of via holes, the refinement of leads, laminated multilayer boards and integrated component boards, has been gradually developed and matured. Meanwhile, a new generation of printed circuit board materials and products, represented by laser technology, plasma technology, nanotechnology, etc., have also emerged. Therefore, the new technologies and processes will promote the development of printed circuit board products in the direction of high density and integrated components. High density interconnect boards place higher demands on the vias between the boards, require higher thermal and electrical conductivity, and better reliability.

The copper paste serving as the through hole mainly plays the roles of electric conduction and heat conduction, and resin curing type copper paste is mainly adopted in the market at present, but the traditional curing type copper paste is not enough in electric conduction and heat conduction capability and cannot meet the requirements of a high-density interconnection plate.

High-density interconnection board is mostly high TgFR ₄ The plate is generally baked at a maximum temperature of about 220 ℃, and is approximately 260 ℃ when lead-free wave soldering is carried out. At present, copper particles and low-temperature alloy solder such as tin-bismuth alloy are mainly adopted at home and abroad, but the mixing of copper and tin-bismuth alloy is difficult to homogenize, and the eutectic point of the tin-bismuth alloy is 141 ℃, so that in the implementation process, the sintered alloy is easily remelted in the process of over-reflow soldering due to abundant tin-bismuth phases, and the metal in a hole is easily subjected to volume shrinkage to cause failure. In addition, the prior art also adopts nanometer silver thick liquid, on one hand because the price of silver is higher, simultaneously in the use, the electromigration phenomenon takes place easily for pure silver, causes the inefficacy easily.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides the nano composite low-temperature slurry which can meet the requirements of sintering at 220 ℃, does not generate remelting at 300 ℃ after sintering and can improve the density.

It is another object of the present invention to provide a method for preparing such nanocomposite cryogenic slurries.

It is a further object of the present invention to provide the use of such nanocomposite cryogenic slurries.

In order to achieve the above purpose, the invention adopts the following technical scheme:

the nano composite low-temperature slurry comprises the following components in parts by weight:

1-80 parts of low-temperature alloy powder, preferably 35-55 parts;

5-80 parts of high-temperature metal powder, preferably 20-45 parts;

1-80 parts of simple substance nano powder, preferably 5-25 parts;

2-10 parts of organic solvent, preferably 3-5 parts;

0-5 parts of activating agent, preferably 0.5-1 part;

0-2 parts of corrosion inhibitor, preferably 0.3-1 part;

0.1 to 3 parts of thickening agent, preferably 0.5 to 1 part.

In a specific embodiment, the low-temperature alloy powder is any one of tin alloy, bismuth alloy, indium alloy and gallium alloy powder with a melting point within 220 ℃, preferably tin alloy powder, and the tin alloy powder is preferably at least any one of tin bismuth alloy, tin zinc bismuth, tin indium alloy and tin bismuth silver alloy; more preferably, the average size of the low-temperature alloy powder is micron-sized or submicron-sized, and is preferably 1-15 μm.

In a specific embodiment, the high-temperature metal powder is copper powder or at least any one of copper alloy, silver alloy, tin alloy and nickel alloy powder with the melting point of more than 300 ℃; the high-temperature powder is preferably selected from one or more of pure copper powder, copper-nickel alloy, copper-silver alloy and copper-zinc alloy; more preferably, the average size of the high-temperature metal powder is micron-sized or submicron-sized, and is preferably 0.6-5 μm.

In a specific embodiment, the elementary substance nano powder is selected from one or more of nano copper, nano silver, nano nickel, nano zinc, nano antimony and nano cerium, and preferably from one or two of nano silver and nano copper; preferably, the average particle size of the nano powder is 5nm-200nm, preferably 30-80 nm.

In a specific embodiment, the organic solvent is an ether solvent, preferably selected from any one or more of ethylene glycol butyl ether, propylene glycol methyl ether, diethylene glycol butyl ether, and propylene glycol ethyl ether.

In a specific embodiment, the activator is an organic acid, preferably any one or more of L-malic acid, glutaric acid, adipic acid, itaconic acid.

In a specific embodiment, the corrosion inhibitor is an organic corrosion inhibitor, preferably any one of the heterocyclic compounds containing nitrogen-oxygen compounds, such as phosphonic acid (salt), phosphonic carboxylic acid, sulfenyl benzothiazole, benzotriazole, methyl benzotriazole sulfonated lignin, and the like.

In a specific embodiment, the thickener is a hydroxyl-containing high molecular compound, preferably any one or more of polyethylene glycol, polyvinyl butyral and polyvinyl pyrrolidone.

In another aspect, a method for preparing the nanocomposite low-temperature slurry comprises the following steps:

A. uniformly mixing an organic solvent, an activating agent, a corrosion inhibitor and a thickening agent, and heating until the organic solvent, the activating agent, the corrosion inhibitor and the thickening agent are completely dissolved to prepare a mixture a;

B. putting part of the mixture a and high-temperature metal powder into a planetary mixer according to a certain proportion, uniformly stirring, and dispersing by a three-roll grinder to obtain a mixture b;

C. mixing the residual mixture a with the simple substance nano powder and the low-temperature alloy powder according to a ratio, and performing ultrasonic dispersion to form a uniformly dispersed mixture c;

D. and putting the mixture b and the mixture c into a planetary stirrer to be uniformly stirred to form the final nano composite low-temperature slurry.

On the other hand, the application of the nano-composite low-temperature paste or the nano-composite low-temperature paste prepared by the preparation method in printed circuit boards, preferably conductive paste.

Compared with the prior art, the invention has the following beneficial effects:

the nano composite low-temperature slurry can realize low-temperature sintering within 220 ℃, and the current PCB industry process does not need to be additionally changed. In the sintering process, the solvent is gradually volatilized, the low-temperature alloy powder is melted, the formed melt gradually wets and wraps the high-temperature copper alloy powder around, part of the high-temperature powder wrapped by the tin alloy melt is dissolved in the tin alloy liquid, and part of the high-temperature powder and the tin alloy liquid form metal compounds, as shown in figure 1, at the moment, under the action of the low-temperature alloy melt, a net structure is gradually formed, the skeleton is the high-temperature powder, and different skeletons are bonded together by the low-temperature alloy melt to form a whole. The most important point is that the low-temperature alloy powder can not be dispersed completely and uniformly, or the low-temperature alloy powder and the high-temperature powder form a metal compound with a lower melting point, or the low-temperature alloy powder is excessive, so that the sintered PCB can be subjected to tempering temperature of 260 ℃ to cause the low-temperature alloy to be melted, thereby causing the metal in the hole to shrink, and causing large cracks to cause product failure. The problem can be well solved by adding the nano-powder, because the grain diameter of the nano-powder is very small, the sintering temperature of the nano-composite low-temperature slurry is generally lower than the block melting point of the nano-powder due to the size effect of the nano-powder, and the sintering phenomenon can also occur within 220 ℃; on the other hand, because of the extremely large specific surface area, the low-temperature alloy powder can be quickly dissolved into the low-temperature alloy melt to form a high-melting-point metal compound in the melting process of the low-temperature alloy powder, so that the part of the alloy melt which is remelted can be reacted to generate a high-melting-point alloy, and the slurry remelting problem in high-temperature reflow soldering is avoided.

The nano composite low-temperature slurry can form a metal compound with better comprehensive performance with low-temperature powder through proper selection of the nano powder, and further improves the comprehensive performance of the slurry. Because, after the normal slurry is sintered at 220 ℃, it is tightly combined with the copper surfaces at the periphery of the hole and the upper and lower substrates to form Cu ₆ Sn ₅ Working at high temperatures in the late phase, Cu ₆ Sn ₅ The IMC layer becomes brittle and cracks appear due to further growth; on the one hand, the invention can inhibit the Cu in the later period by adding the trace elements through the addition of the nano powder ₆ Sn ₅ Further growth of (2). On the other hand, the proper nano powder can form good metallurgical bonding with the copper substrate after being sintered, for example, the copper nano powder is sintered, and the comprehensive performance is extremely high.

Drawings

FIG. 1 is a schematic view of the microstructure of the nanocomposite cryogenic slurry of the present invention.

FIG. 2 is a micrograph of nanocomposite low temperature slurry nozzle-slice of examples 1-4 of the present invention wherein (a) example 1, (b) example 2, (c) example 3, and (d) example 4.

FIG. 3 is a micrograph of a nanocomposite cryopaste via-fill slice of comparative examples 1-4 of the present invention, wherein (a) comparative example 1, (b) comparative example 2, (c) comparative example 3, and (d) comparative example 4.

FIG. 4 is a thermal expansion coefficient curve of the nanocomposite cryogenic slurry of example 1 of the present invention.

FIG. 5 is a thermal expansion coefficient curve of the nanocomposite cryogenic slurry of example 4 of the present invention.

FIG. 6 is a thermal expansion coefficient curve of the nanocomposite cryogenic slurry of comparative example 1 of the present invention.

FIG. 7 is a thermal expansion coefficient curve of the nanocomposite cryogenic slurry of comparative example 4 of the present invention.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting.

Example 1

a preparation method of nano composite low-temperature slurry comprises the following steps:

A. uniformly mixing the propylene glycol ethyl ether, glutaric acid, benzotriazole and polyvinyl butyral in parts by weight, and heating until the mixture is completely dissolved to prepare a mixture a;

B. putting 50% of the mixture a and 4 mu mCu powder with the average particle size into a planetary mixer, uniformly stirring, and dispersing by a three-roll grinder to obtain a mixture b;

C. mixing the rest of the mixture a with nanometer Ag powder with average particle diameter of 64nm and Sn with average particle diameter of 5 μm ₅₈ Bi ₄₂ Mixing the alloy powder, and performing ultrasonic dispersion to form a uniformly dispersed mixture c;

D. and putting the mixture b and the mixture c into a planetary stirrer to be uniformly stirred to form the final product of the nano composite low-temperature slurry.

The prepared slurry is printed in PCB prefabricated holes through a screen printer, precuring is carried out at about 100 ℃, the solvent in the carrier is partially volatilized at the temperature, meanwhile, the resin is cured, the slurry can shrink and begin to be preliminarily shaped, and the particles can be closer under the action of shrinkage.

And (3) putting the pre-fixed PCB into vacuum pressure sintering equipment, and performing pressure sintering for 1h at 190 ℃. Measuring the resistivity of the sintered sample by using a conductivity measuring instrument; slice tissue compactness during observation period by using a microscope; and testing the expansion coefficient data by using a thermal expansion instrument, and judging the re-melting point of the material according to a thermal expansion curve. The measurement data are shown in Table 1.

Example 2

A. uniformly mixing propylene glycol butyl ether, itaconic acid, benzotriazole and polyvinyl butyral according to the proportion, and heating until the mixture is completely dissolved to prepare a mixture a;

B. mixing 45% of mixture a with an average particle size of 0.8 mu mTAg _0.1 Putting the powder into a planetary stirrer, uniformly stirring, and dispersing by a three-roller grinder to obtain a mixture b;

C. mixing the rest of the mixture a with Cu powder with an average particle size of 50 nm and SnBi with an average particle size of 4 μm ₄₂ Ag ₂ Mixing the alloy powder, and performing ultrasonic dispersion to form a uniformly dispersed mixture c;

And (3) putting the pre-fixed PCB into vacuum pressure sintering equipment, and performing pressure sintering for 1h at 220 ℃. The sintered samples were tested for properties and the data are shown in table 1.

Example 3

A. uniformly mixing the ethylene glycol monobutyl ether, adipic acid, sulfenyl benzothiazole and polyethylene glycol in parts by weight, and heating until the ethylene glycol monobutyl ether, the adipic acid, the sulfenyl benzothiazole and the polyethylene glycol are completely dissolved to prepare a mixture a;

B. putting 20% of the mixture a and TNi2.4-0.6-0.5 powder with the average particle size of 0.8 mu m into a planetary mixer, uniformly stirring, and dispersing by a three-roll grinder to obtain a mixture b;

C. mixing the rest of the mixture a with Ni powder with an average particle size of 35 nm and SnBi with an average particle size of 12 μm ₅₆ Zn ₄ Mixing the alloy powder, and performing ultrasonic dispersion to form a uniformly dispersed mixture c;

Example 4

A. uniformly mixing the ethylene glycol monobutyl ether, adipic acid, methyl benzotriazole and polyvinylpyrrolidone in parts by weight, and heating until the mixture is completely dissolved to prepare a mixture a;

B. mixing 50% of the mixture a with 4 mu m CuZn with average particle size ₄ Putting the alloy powder into a planetary stirrer to be uniformly stirred, and dispersing the alloy powder by a three-roller grinder to prepare a mixture b;

C. will remain behindThe mixture a of (A) with Zn powder having an average particle size of 120 nm and SnIn having an average particle size of 7 μm _59.1 Mixing the alloy powder, and performing ultrasonic dispersion to form a uniformly dispersed mixture c;

And (3) putting the pre-fixed PCB into vacuum pressure sintering equipment, and performing pressure sintering for 1h at 190 ℃. The performance of the sintered sample is tested, and the measured data are shown in table 1.

Example 5

B. 15% of the mixture a was mixed with SnCu having an average particle size of 0.6. mu.m ₄₀ Putting the powder into a planetary stirrer, uniformly stirring, and dispersing by a three-roller grinder to obtain a mixture b;

C. mixing the rest of the mixture a with Ag powder having an average particle size of 80nm and Sn having an average particle size of 2 μm ₅₈ Bi ₄₂ Mixing the alloy powder, and performing ultrasonic dispersion to form a uniformly dispersed mixture c;

And (3) putting the pre-fixed PCB into vacuum pressure sintering equipment, and performing pressure sintering for 1h at 190 ℃. The sintered sample was subjected to the performance test, and the measurement data thereof are shown in table 1.

Example 6

A. uniformly mixing the diethylene glycol butyl ether, the adipic acid, the thiobenzothiazole and the polyvinyl butyral in parts by weight, and heating until the components are completely dissolved to prepare a mixture a;

B. putting the 35% mixture a and copper powder with the average particle size of 4 mu m into a planetary stirrer, uniformly stirring, and dispersing by a three-roll grinder to obtain a mixture b;

C. mixing the rest of mixture a with Cu powder with average particle diameter of 32nm and GaCu powder with average particle diameter of 5 μm ₄ Mixing the alloy powder, and performing ultrasonic dispersion to form a uniformly dispersed mixture c;

Example 7

A. uniformly mixing the propylene glycol methyl ether, glutaric acid, benzotriazole and polyethylene glycol in parts by weight, and heating until the mixture is completely dissolved to prepare a mixture a;

B. 30% of the mixture a was mixed with 4. mu. mAgCu of the average particle size ₄₂ Putting Zn into a planetary stirrer to be uniformly stirred, and dispersing by a three-roller grinder to prepare a mixture b;

C. mixing the rest of mixture a with Cu powder with average particle diameter of 36nm and BiSn with average particle diameter of 3 μm ₄₀ Cu _0.5 Mixing the alloy powder, and performing ultrasonic dispersion to form a uniformly dispersed mixture c;

Example 8

A nano composite low-temperature slurry comprises the following components in parts by weight:

A. uniformly mixing the ethylene glycol monobutyl ether, the L-malic acid, the phosphonocarboxylic acid and the polyethylene glycol in parts by weight, and heating until the materials are completely dissolved to prepare a mixture a;

B. putting 80% of the mixture a and 0.8 mu mCu powder with the average particle size into a planetary stirrer to be uniformly stirred, and dispersing by a three-roll grinder to prepare a mixture b;

C. mixing the rest of the mixture a with Ag powder with an average particle size of 42nm and InCu powder with an average particle size of 1 μm _1.6 Mixing the alloy powder, and performing ultrasonic dispersion to form a uniformly dispersed mixture c;

And (3) putting the pre-fixed PCB into vacuum pressure sintering equipment, and performing pressure sintering for 1h at 190 ℃.

The sintered sample was subjected to the performance test, and the measurement data thereof are shown in table 1.

Comparative example 1

Compared with the example 1, the nano Ag powder is replaced by copper powder with equal weight parts, and other conditions are completely consistent. The sintered sample was subjected to the performance test, and the measurement data thereof are shown in table 1.

Comparative example 2

Compared with the example 2, the nano Cu powder is replaced by TAg with equal weight part _0.1 Powder, other conditions were completely consistent. The sintered sample was subjected to the performance test, and the measurement data thereof are shown in table 1.

Comparative example 3

Compared with the embodiment 3, the nano Ni powder is replaced by TNi2.4-0.6-0.5 powder, and other conditions are completely consistent. The sintered sample was subjected to the performance test, and the measurement data thereof are shown in table 1.

Comparative example 4

Compared with the embodiment 4, the nano Zn powder is replaced by CuZn ₄ Alloy powder and other conditions are completely consistent. The sintered sample was subjected to the performance test, and the measurement data thereof are shown in table 1.

TABLE 1 Performance parameters of the different components

As can be seen from the above table, the nanocomposite low-temperature slurry prepared by the invention has low resistivity, excellent tissue compactness and higher remelting temperature after being cured.

Fig. 2 and fig. 3 show microscope diagrams of the nanocomposite low-temperature slurry plug holes of examples 1 to 4 and comparative examples 1 to 4, respectively, and it can also be clearly seen that the compactness of the nanocomposite low-temperature slurry plug holes prepared by the example of the invention is better.

Fig. 4 to 7 show thermal expansion curves of the nanocomposite low temperature pastes of example 1 and example 4 of the present invention and comparative example 1 and comparative example 4, respectively, and it can be seen that the nanocomposite low temperature paste of the example of the present invention has a higher re-melting temperature.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. The nano composite low-temperature slurry is characterized by comprising the following components in parts by weight:

1-80 parts of low-temperature alloy powder, preferably 35-55 parts;

5-80 parts of high-temperature metal powder, preferably 20-45 parts;

1-80 parts of simple substance nano powder, preferably 5-25 parts;

2-10 parts of organic solvent, preferably 3-5 parts;

0 to 5 parts of activator, preferably 0.5 to 1 part,

0-2 parts of corrosion inhibitor, preferably 0.3-1 part;

0.1 to 3 parts of thickening agent, preferably 0.5 to 1 part.

2. The nano composite low-temperature slurry according to claim 1, wherein the low-temperature alloy powder is at least one of tin alloy, bismuth alloy, indium alloy and gallium alloy powder with a melting point within 220 ℃, preferably tin alloy powder, and the tin alloy powder is preferably at least one of tin bismuth alloy, tin zinc bismuth, tin indium alloy and tin bismuth silver alloy; more preferably, the average size of the low-temperature alloy powder is micron-sized or submicron-sized, and is preferably 1-15 μm.

3. The nanocomposite cryogenic slurry of claim 1, wherein the high temperature metal powder is at least one of copper powder or copper alloy, silver alloy, tin alloy, and nickel alloy powder having a melting point of 300 ℃ or higher; preferably, the high-temperature powder is selected from one or more of pure copper powder, copper-nickel alloy, copper-silver alloy and copper-zinc alloy; more preferably, the average size of the high-temperature metal powder is micron-sized or submicron-sized, and is preferably 0.6-5 μm.

4. The nano-composite low-temperature slurry as claimed in claim 1, wherein the elemental nano-powder is selected from one or more of nano-copper, nano-silver, nano-nickel, nano-zinc, nano-antimony and nano-cerium, and preferably from one or two of nano-silver and nano-copper; preferably, the average particle size of the nano powder is 5nm-200nm, preferably 30-80 nm.

5. The nanocomposite cryogenic slurry of claim 1, wherein the organic solvent is an ether solvent, preferably selected from one or more of ethylene glycol butyl ether, propylene glycol methyl ether, diethylene glycol butyl ether, and propylene glycol ethyl ether.

6. The nanocomposite cryogenic slurry of claim 1, wherein the activator is an organic acid, preferably any one or more of L-malic acid, glutaric acid, adipic acid, and itaconic acid.

7. The nanocomposite cryogenic slurry of claim 1, wherein the corrosion inhibitor is an organic corrosion inhibitor, preferably any one of heterocyclic compounds containing nitrogen-oxygen compounds, such as phosphonic acid (salt), phosphonic carboxylic acid, thiobenzothiazole, benzotriazole, and methylbenzotriazole sulfonated lignin.

8. The thickening agent is a hydroxyl-containing high molecular compound, preferably any one or more of polyethylene glycol, polyvinyl butyral and polyvinylpyrrolidone.

9. The preparation method of the nanocomposite cryogenic slurry of any one of claims 1 to 8, characterized by comprising the following steps:

10. Use of the nanocomposite cryogenic slurry of any one of claims 1 to 8 or the nanocomposite cryogenic slurry prepared by the preparation method of claim 9 in printed circuit boards, preferably conductive pastes.