A sintering method for silver-copper thick film conductor paste for ceramic substrate surfaces

Abstract

The application discloses a sintering method of silver-copper thick film conductor paste for ceramic substrate surface, which comprises the following steps: S1, applying silver-copper thick film conductor paste on the surface of a ceramic substrate and air-drying; S2, placing the air-dried ceramic substrate obtained in step S1 in an atmosphere at 400-500 DEG C for 1-2 hours to remove the organic carrier in the silver-copper thick film conductor paste; and S3, reducing the ceramic substrate obtained in step S2 in a reducing atmosphere at 820-860 DEG C for 1-2 hours to form a silver-copper thick film conductor layer on the surface of the ceramic substrate. The sintering method of silver-copper thick film conductor paste for ceramic substrate surface provided by the application realizes high-temperature sintering of silver-copper thick film conductor paste on a ceramic substrate, reduces the cost, is simple in sintering process, and has quite good performance of the sintered film.

Description

Technical Field

[0001] This invention belongs to the field of conductor paste technology, specifically relating to a sintering method for a silver-copper thick-film conductor paste for use on the surface of a ceramic substrate. Background Technology

[0002] Thick film slurries are classified into metal-ceramic thick film slurries requiring high-temperature treatment and polymer thick film slurries that cure at lower temperatures. Metal-ceramic thick film slurries form a sintered composite layer on a substrate after sintering. The main components of metal thick film slurries include active materials, glass powder, and an organic carrier. The active materials are finely ground powders with a typical particle size of a few micrometers, such as precious metals or metal alloys. The glass powder acts as a binder, holding the active particles together and adhering the film to the substrate. The organic carrier ensures the slurry has the correct viscosity for screen printing; it typically contains resins and surfactants dissolved in a solvent to ensure good dispersion of solid particles.

[0003] Existing silver thick-film conductor pastes are sintered at approximately 850°C in an oxygen atmosphere. Although the sintering process of silver thick-film conductor pastes is simple, silver itself is a precious metal, resulting in high costs. Copper thick-film conductors are sintered at approximately 900°C in a nitrogen atmosphere. The first part of the sintering process (up to 400°C) requires a certain amount of oxygen to maintain a good connection between the copper film and the alumina substrate. The copper thick film on the alumina substrate is also known as thick printed copper (TPC). The conductivity of copper thick-film conductor pastes is comparable to that of silver films, but the sintering process is more complicated, and controlling the oxygen content in the first part of sintering is not easy. Summary of the Invention

[0004] This invention provides a sintering method for silver-copper thick film conductor paste on the surface of a ceramic substrate. The method achieves high-temperature sintering of silver-copper thick film conductor paste on a ceramic substrate, which reduces costs, sintering process is simple, and the performance of the sintered film is comparable.

[0005] This invention provides a sintering method for a silver-copper thick-film conductor paste for use on a ceramic substrate, comprising the following steps:

[0006] S1. Apply the silver-copper thick film conductor paste to the surface of the ceramic substrate and let it dry.

[0007] S2. The dried ceramic substrate obtained in step S1 is placed at 400-500℃ in an atmospheric atmosphere and sintered for 1-2 hours to remove the organic carrier in the silver-copper thick film conductor paste.

[0008] S3. The ceramic substrate obtained in step S2 is reduced at 820-860°C in a reducing atmosphere for 1-2 hours to form a silver-copper thick film conductor layer on the surface of the ceramic substrate.

[0009] In one embodiment of the present invention, the silver-copper thick film conductor paste comprises the following raw materials in parts by weight: 80-90 parts of silver-coated copper powder, 1.5-3 parts of glass powder, and 9-12 parts of organic carrier.

[0010] In one embodiment of the present invention, the silver-coated copper powder contains 30 wt% silver and 70 wt% copper.

[0011] In one embodiment of the present invention, in step S1, drying involves placing the ceramic substrate coated with silver-copper thick film conductor paste in an oven at 150°C and drying it for 5 minutes.

[0012] In one embodiment of the present invention, in step S2, the dried ceramic substrate is placed at 400-500°C in an atmospheric atmosphere and sintered for 1.5 hours.

[0013] In one embodiment of the present invention, in step S3, the ceramic substrate obtained in step S2 is reduced at 850°C in a reducing atmosphere for 1.5 hours.

[0014] In one embodiment of the present invention, the reducing atmosphere in step S3 is a mixture of hydrogen and argon.

[0015] In one embodiment of the present invention, the volume fraction of hydrogen in the mixed gas is 5%.

[0016] In one embodiment of the present invention, the ceramic substrate is an alumina ceramic substrate.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] 1. The sintering method for silver-copper thick film conductor paste on the surface of ceramic substrate provided in the embodiments of the present invention realizes high-temperature sintering of silver-copper thick film conductor paste on a ceramic substrate, which reduces costs, sintering process is simple, and the performance of sintered film is comparable.

[0019] 2. In the sintering method of silver-copper thick film conductor paste for ceramic substrate surface provided in the embodiments of the present invention, atmospheric atmosphere sintering and reducing atmosphere sintering are completely separated and carried out in two steps. The first step ensures that the organic carrier combines with oxygen in the atmosphere and volatilizes completely. The second step ensures that the oxidized copper oxide is completely reduced, and finally a high-performance silver-copper thick film is obtained by sintering. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the sintering method for silver-copper thick film conductor paste used on the surface of ceramic substrates in this invention.

[0021] Figure 2 This is a loss curve of organic carrier V-3180 in step S1 of Example 1;

[0022] Figure 3 This is a loss curve of organic carrier V-3183 in step S1 in Example 2;

[0023] Figure 4 This is a loss curve of organic carrier V-822 in step S1 in Example 2;

[0024] Figure 5 This is an SEM image of the conductor layer obtained on the ceramic substrate after step S2 in Example 1. Detailed Implementation

[0025] In this document, the range expressed as "from one value to another" is a concise way of representing a range to avoid listing all the values ​​in that range in the specification. Therefore, the description of a particular range of values ​​covers any value within that range as well as the smaller range of values ​​defined by that value, just as if the arbitrary value and the smaller range of values ​​were explicitly stated in the specification.

[0026] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Improvements and adjustments made by those skilled in the art based on the present invention in practical applications still fall within the scope of protection of the present invention.

[0027] Example 1:

[0028] This embodiment provides a sintering method for a silver-copper thick-film conductor paste for use on the surface of a ceramic substrate, including the following steps:

[0029] S1. Apply silver-copper thick film conductor paste to the surface of a ceramic substrate and let it dry; wherein, drying means placing the ceramic substrate coated with silver-copper thick film conductor paste in an oven at 150°C and drying it for 5 minutes.

[0030] S2. The dried ceramic substrate obtained in step S1 is placed at 400-500℃ in an atmospheric atmosphere and sintered for 1.5 hours to remove the organic carrier in the silver-copper thick film conductor paste.

[0031] S3. The ceramic substrate obtained in step S2 is reduced at 850°C in a reducing atmosphere for 1.5 hours to form a silver-copper thick film conductor layer on the surface of the ceramic substrate.

[0032] In step S2, the copper is burned in an atmospheric atmosphere, and some of the copper is oxidized. The organic carrier is completely volatilized, but the metallization process is not yet completely finished. The further step S3 is to carry out the metallization process in a reducing atmosphere, which can reduce costs and achieve the same performance.

[0033] The silver-copper thick-film conductor paste in this embodiment includes the following raw materials: silver-coated copper powder, glass powder, and organic carrier. The silver-coated copper powder comprises 87.02 wt%, the glass powder comprises 2.16 wt%, the organic carrier comprises 10.83 wt%, and the remainder is a diluent used for viscosity adjustment.

[0034] After sintering, the silver-copper thick film conductor layer contained 97.58 wt% silver-coated copper powder and 2.42 wt% glass powder.

[0035] In this embodiment, the reducing atmosphere in step S3 is a mixture of hydrogen and argon, and the volume fraction of hydrogen in the mixture is 5%.

[0036] The ceramic substrate described in this embodiment is an alumina ceramic substrate.

[0037] In this embodiment, the silver-coated copper powder is Heraeus's PM-509 silver-coated copper powder, the glass powder is Heraeus's F-550 glass powder, the organic carrier includes three types: Heraeus's V-3180 organic carrier, Heraeus's V-3183 organic carrier, and Heraeus's V-822 organic carrier, and the diluent is Heraeus's RV-636 diluent.

[0038] Depend on Figures 2-4 As shown, the loss of V-3180 began to stabilize at 441.96℃, at 96.95% (400℃), 98.52% (455℃), and 99.88% (840℃); the loss of V-3183 began to stabilize at 532.31℃, at 97.73% (400℃), 99.41% (460℃), and 99.53% (840℃); and the loss of V-822 began to stabilize at 595.31℃, at 78.45% (420℃), 88.19% (460℃), and 100.0% (840℃). During the sintering process, the percentage of V-3180 and V-3183 escaping at 400℃ and 460℃ was similar, and the complete escaping temperature was lower than that of V-822. The phased escaping of the three resins was more beneficial to the performance of the sintered product.

[0039] In step S2, sintering in an atmospheric atmosphere can be carried out in a tunnel furnace or a muffle furnace, as long as the organic carrier is completely volatilized by combining with oxygen. In step S3, sintering in a reducing atmosphere is carried out in a tube furnace. The sintering in step S3 is not limited to being carried out in a tube furnace, as long as the copper oxide is completely reduced under a reducing atmosphere.

[0040] The above description discloses only preferred embodiments of the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to make good use of the invention. The present invention is limited only by the claims and their full scope and equivalents.

[0041] Under the guidance of the present invention and the above embodiments, those skilled in the art will readily foresee that all the raw materials or their equivalents, processing methods or their equivalents listed or exemplified in the present invention can achieve the present invention, and that the upper and lower limits and range values ​​of the parameters of each raw material and processing method can also achieve the present invention. Examples are not listed one by one here.

Claims

1. A sintering method for a silver-copper thick-film conductor paste for use on the surface of a ceramic substrate, characterized in that, Includes the following steps: S1. Apply the silver-copper thick film conductor paste to the surface of the ceramic substrate and let it dry. S2. The dried ceramic substrate obtained in step S1 is placed at 400-500℃ in an atmospheric atmosphere and sintered for 1-2 hours to remove the organic carrier in the silver-copper thick film conductor paste. S3. The ceramic substrate obtained in step S2 is reduced at 820-860°C in a reducing atmosphere for 1-2 hours to form a silver-copper thick film conductor layer on the surface of the ceramic substrate. The silver-copper thick film conductor paste comprises the following raw materials in parts by weight: 80-90 parts silver-coated copper powder, 1.5-3 parts glass powder, and 9-12 parts organic carrier; The silver-coated copper powder contains 30 wt% silver and 70 wt% copper.

2. The sintering method for silver-copper thick-film conductor paste on the surface of a ceramic substrate according to claim 1, characterized in that, In step S1, drying involves placing the ceramic substrate coated with silver-copper thick-film conductor paste in an oven at 150°C and drying it for 5 minutes.

3. The sintering method for silver-copper thick-film conductor paste on the surface of a ceramic substrate according to claim 1, characterized in that, In step S2, the dried ceramic substrate is placed at 400-500°C in an atmospheric atmosphere and sintered for 1.5 hours.

4. The sintering method for silver-copper thick-film conductor paste on the surface of a ceramic substrate according to claim 1, characterized in that, In step S3, the ceramic substrate obtained in step S2 is reduced at 850°C in a reducing atmosphere for 1.5 hours.

5. The sintering method for silver-copper thick-film conductor paste on the surface of a ceramic substrate according to claim 4, characterized in that, The reducing atmosphere in step S3 is a mixture of hydrogen and argon.

6. The sintering method for silver-copper thick-film conductor paste on the surface of a ceramic substrate according to claim 5, characterized in that, The volume fraction of hydrogen in the mixture is 5%.

7. The sintering method for silver-copper thick-film conductor paste on the surface of a ceramic substrate according to claim 1, characterized in that, The ceramic substrate is an alumina ceramic substrate.

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