TW201726859A - Conductive silver adhesive and conductive silver layer - Google Patents

Abstract

Provided are conductive silver adhesive and conductive silver layer cured by thereof. The conductive silver adhesive includes silver powder, silver salt, aminophenol typed epoxy compound, and curing agent. By adding the silver salt and aminophenol typed epoxy compound, the present invention can prepare the conductive silver adhesive at a lower cost and ensure the conductive silver adhesive has good workability and high conductivity.

Description

Conductive silver paste and conductive silver layer

The present invention relates to a silver composition, in particular to a conductive silver layer formed by a conductive silver paste and a conductive silver paste.

Conductive silver adhesive consists of resin, silver particles and additives. It is widely used in electronic components such as printed circuit boards, liquid crystal displays, and light-emitting diodes because of its characteristics of conduction, heat conduction and adhesion. In the packaging process, it becomes a conductive adhesive that can replace traditional soldering.

In order to improve the conductivity of the conductive silver paste, the prior art usually incorporates a large amount of conductive silver particles into the conductive silver paste, so as to improve the characteristics of the conductive silver paste applied to the electronic product. However, excessive silver particles may cause the viscosity of the conductive silver paste to become high and workability to be deteriorated. At the same time, increasing the silver content will relatively reduce the content of organic components in the conductive silver paste, resulting in a decrease in the overall adhesion of the conductive silver paste. Instead, it reduces the reliability of electronic products.

In view of the above drawbacks, the prior art has in turn incorporated nanometer-sized conductive silver particles into the conductive silver paste, and these nano-scale silver particles can help fill the gap between the silver particles and utilize nano silver. The particles have a low melting point characteristic, so that the nano silver particles are expected to be sintered at a lower temperature to form a permanent conductive path.

In addition, the preparation of nano-scale conductive particles requires special dispersing treatment technology and dispersing equipment, so that the production cost of nano-silver particles cannot be lowered, and it is difficult to increase the conductive silver paste blended with nano-silver particles in the market. Competitiveness.

In view of this, the purpose of the creation is to improve the conductivity of the conductive silver paste under the premise of reducing the manufacturing cost of the conductive silver paste and ensuring the workability of the conductive silver paste.

To achieve the foregoing objects, the present invention provides a conductive silver paste comprising a silver powder, a silver salt, an aminophenol type epoxy compound, and a curing agent. According to the present invention, by combining the silver salt and the aminophenol type epoxy compound, the aminophenol type epoxy compound can be used as an organic component of the conductive silver paste and in-situ polymerization with the curing agent. In the curing reaction of the conductive silver paste, the silver salt is simultaneously reduced to silver powder. Accordingly, the present invention can improve the conductivity of the conductive silver paste while maintaining the viscosity and workability of the conductive silver paste; meanwhile, the conductive silver layer cured by the conductive silver paste can have a lower volume resistance. The rate and high thrust strength enhance the characteristics of conductive silver glue used in electronic products.

Preferably, the aminophenol type epoxy compound may be a p-aminophenol type epoxy compound, but is not limited thereto.

Specifically, the aforementioned aminophenol type epoxy compound has the structure shown below: Wherein R ¹ to R ³ are each independently hydrogen, methyl or epoxy, wherein at least one of R ¹ to R ³ is an epoxy group. More preferably, R ¹ and R ² are an epoxy group, and R ³ is hydrogen, a methyl group or an epoxy group.

Preferably, the silver salt may be silver nitrate, silver acetate, other fatty acid silver salts having a carbon number of 8 to 24, or a combination thereof.

Preferably, the silver powder may be a micron-sized silver powder, for example, a micron-sized flake silver powder or a micron-sized spherical silver powder. More preferably, the micron-sized flaky silver powder has a median diameter (D50) of between 0.3 micrometers (μm) and 10 μm, and a tap density (TD) of 0.5 g/cm 3 (g/cm ³ ). Between 6 g/cm ³ ; the micron-sized spherical silver powder may have a median particle diameter of between 0.1 μm and 5 μm and a tap density of from 1 g/cm ³ to 6 g/cm ³ . Accordingly, the present invention can achieve the purpose of improving conductivity by using micron-sized silver powder, thereby reducing the manufacturing cost of the conductive silver paste.

In order to further improve the conductivity of the conductive silver paste, the silver powder is preferably a micron-sized flake silver powder.

Preferably, the curing agent may be a phenol resin, an amine compound or an acid anhydride compound. Specifically, phenol resins such as bisphenol F epoxy resin, allyl phenol resin, phenol novolac, and cresol novolac resin can be selected for the present invention. (cresol novolac resin), phenol resins modified naphthol (naphthol modified phenol resin), dicyclopentadiene modified phenol resin (dicyclopentadiene modified phenol resin) or p-xylene modified phenol resin (p -xylene modified phenol resin), However, it is not limited to this; amine compounds such as aliphatic polyamines, aromatic amines, modified polyamines, tertiary amine compounds, imidazole-based compounds, and melamines are optional for this creation. , dicyandiamide (DICY), but not limited to this; an acid anhydride compound such as: methyl tetra hydro-phthalic anhydride (MTHPA2), methyl hexahydrophthalic anhydride ( Methyl hexa hydro-phthalic anhydride), alkyl tetrahydrophthalic anhydride, hexahydro-phthalic anhydride , HHPA), methyl humic acid anhydride, alkenyl succinic anhydride, methyl nadie anhydride or glutaric anhydride, but not exclusively Limited to this.

Preferably, the conductive silver paste further comprises a coupling agent. Accordingly, the conductive silver paste can have better adhesion. In the conductive silver paste of the present invention, the coupling agent may be a decane coupling agent or a titanate coupling agent. Specifically, a decane coupling agent such as 3-glycidoxypropyl trimethoxysilane, mercaptopropyltrimethoxysilane, or 3-mercaptopropyltrimethoxysilane may be used in the present invention. 2-aminopropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, but not limited to this; titanate coupling agent optional for this creation For example: titanium triisostearate isopropoxide, isopropyl triacryl titanate, isopropyl tris(dioctylpyrophosphate) titanate ( Tri(dioctyl pyrophosphato) titanate), but not limited to this.

Preferably, the content of the silver powder may be 65 to 90% by weight based on the total amount of the total conductive silver paste, and the content of the silver salt may be 4.5 to 15% by weight, and the aminophenol type epoxy compound The content is from 5.3 weight percent to 30 weight percent, the curing agent content may be from 0.1 weight percent to 20 weight percent, and the coupler content is from 0.1 weight percent to 3 weight percent. More preferably, the content of the silver powder may be 65 to 75 weight percent based on the total amount of the total conductive silver paste, and the content of the silver salt may be 9 to 15 weight percent, and the aminophenol type epoxy compound The content is from 15.8 weight percent to 25 weight percent, the curing agent content may be from 0.1 weight percent to 10 weight percent, and the coupler content is from 0.1 weight percent to 0.2 weight percent.

Preferably, the sum of the content of the silver powder and the silver salt is from 70% by weight to 95% by weight based on the total of the total conductive silver paste.

In addition, the present invention further provides a conductive silver layer which is cured by a conductive silver paste as described above, and has a volume resistivity of less than 2×10 ⁻⁴ Ω-cm.

Preferably, the conductive silver layer has a volume resistivity of 1×10 ^-6 Ω-cm to 2×10 ⁻⁴ Ω-cm; further, the conductive silver layer has a volume resistivity of 1×10 ^{−5 .} Ω-cm to 2 × 10 ^-4 Ω-cm.

In summary, the present invention not only maintains the workability of the original conductive silver paste by mixing silver powder, silver salt, aminophenol type epoxy compound and curing agent, but also significantly improves the conductive silver paste and its curing. The electrical conductivity of the conductive silver layer is formed; in addition, the prior art can further improve the conductivity and reduce the manufacturing cost without limiting the use of nano-grade silver powder.

In order to verify the influence of the composition of the conductive silver paste on its viscosity, electrical conductivity and thrust strength, several conductive silver pastes with different compositions and their cured conductive silver layers are exemplified below to illustrate the implementation of the present invention; The skilled person can easily understand the advantages and effects of the present invention through the contents of the present specification, and implement various modifications and changes to implement or apply the contents of the present creation without departing from the spirit of the present invention.

In order to ensure the experimental significance, the conductive silver pastes of the following examples and comparative examples all use 4-methyl-2-phenylimidazole as a curing agent, and fix the content of the curing agent in the conductive silver paste of each of the examples and the comparative examples. In order to analyze the influence of the characteristics of the conductive silver paste on the presence or absence of the blended silver salt, the type of the epoxy compound, the type of the silver powder, the content of the silver, and the presence or absence of the blending coupler. The following exemplary examples use the same materials as the binder, curing agent and coupling agent for the purpose of highlighting the experimental significance of other variables, and it is not intended that those skilled in the art can only use the following exemplary examples. The raw material of the present invention is made of conductive silver glue.

Raw materials: 1. Micron-sized flake silver powder: The product model is SG-00A3, purchased from Koyo Applied Materials Co., Ltd.; D50 is about 4 μm, TD is about 3.5 g/cm ³ , and the particle size is between 1.5 μm and 10 μm. The specific surface area is between 0.5 m ² /g and 1.2 m ² /g. 2. Micron-sized spherical silver powder: The product model is SP-03, purchased from Koyo Applied Materials Co., Ltd.; D50 is about 2 μm, tap density is about 5.0 g/cm ³ , and particle size is between 0.5 μm and 10 μm. The specific surface area is between 0.1 m ² /g and 1.2 m ² /g. 3. Silver nitrate (AgNO ₃ ): The product model is xx, purchased from Koyo Applied Materials Co., Ltd. 4. aminophenol type epoxy compound (p -aminophenol epoxy compound): Product Model JER630, available from Mitsubishi Chemical Corporation; epoxy equivalent weight of about 97 g / eq. 5. (3-glycidoxypropyl trimethoxysilane): The product model is KBM403. 6. Bisphenol-A type epoxy resin: The product model number is YL980, which is purchased from Mitsubishi Chemical Corporation. 7. 4-methyl-2-phenylimidazole (4-methyl-2-phenyl-1H-imidazole, 2P4MZ): The product model was 2P4MZ, which was purchased from Shikoku Chemical Industry Co., Ltd.

Example 1 : Conductive silver glue

According to the ratio shown in Table 1 below, weigh an appropriate amount of micron-sized silver flakes, silver nitrate, p-aminophenol epoxy compound, 4-methyl-2-phenylimidazole (curing agent), and mix the raw materials evenly. After that, the mixture is dispersed and mixed by a three-roller, and then defoamed by a public-rotation defoaming machine to obtain a finished product of the final conductive silver paste.

It can be calculated from the ratio shown in Table 1 below: based on the weight of the conductive silver paste of the whole embodiment 1, the content of the micron-sized flake silver powder is about 70.6 wt%, the content of silver nitrate is about 11.8 wt%, p-aminophenol. The content of the epoxy compound is about 17.1% by weight, and the content of 4-methyl-2-phenylimidazole is about 0.6% by weight.

Example 2 : Conductive silver glue

As shown in Table 1 below, the conductive silver paste of Example 2 was prepared substantially as described in Example 1, except that the conductive silver paste of Example 2 was additionally blended (3- Glycidoxypropyl)trimethoxydecane (coupling agent); in the process, micron-sized silver flakes, silver nitrate, p-aminophenol epoxy compounds, 4-methyl-2-phenylimidazole and After (3-glycidoxypropyl)trimethoxydecane was uniformly stirred, it was dispersed and mixed by a three-roller, and then defoamed by a public-rotation defoaming machine to obtain a finished product of the final conductive silver paste.

It can be calculated from the ratio shown in Table 1 below: based on the weight of the conductive silver paste of the whole embodiment 2, the content of the micron-sized flake silver powder is about 70.5 wt%, the content of silver nitrate is about 11.7 wt%, p-aminophenol. The content of the epoxy compound is about 17.0 wt%, the content of 4-methyl-2-phenylimidazole is about 0.6 wt%, and the content of (3-glycidoxypropyl)trimethoxydecane is about 0.2 wt%.

Example 3 : Conductive silver glue

As shown in Table 1 below, the conductive silver paste of Example 3 was prepared substantially by the method as described in Example 1, except that Example 3 was replaced with micron-sized spherical silver powder instead of Example 1. The micron-sized flake silver powder is obtained through the same method to obtain a finished conductive silver paste.

It can be calculated from the ratio shown in Table 1 below: based on the weight of the conductive silver paste of the whole embodiment 3, the content of the micron-sized spherical silver powder is about 70.6 wt%, and the content of silver nitrate is about 11.8 wt%, p-aminophenol. The content of the epoxy compound is about 17.1% by weight, and the content of 4-methyl-2-phenylimidazole is about 0.6% by weight. Table 1: The ratio (unit: g) of the conductive silver paste in Examples 1 to 3 and the test results thereof.

Comparative example 1 , 2 and 5 : Conductive silver glue

The conductive silver pastes of Comparative Examples 1, 2 and 5 were prepared substantially as described in Example 1, except that the conductive silver used in the preparation of the comparative examples was as shown in Table 2 below. The raw material of the glue does not contain silver salt, that is, micron-sized sheet or spherical silver powder, p-aminophenol type epoxy compound, 4-methyl-2-phenylimidazole and (3-epoxypropoxy group) in the process. After the propyl)trimethoxydecane is uniformly stirred, it is dispersed and mixed by a three-roller, and then defoamed by a public-rotation defoaming machine to obtain a finished product of the final conductive silver paste.

The main difference between the conductive silver pastes of Comparative Example 1 and Comparative Example 5 was that the addition amount of the micron-sized flaky silver powder of Comparative Example 5 was increased to 44 g. It can be calculated from the ratio shown in Table 2 below: based on the weight of the conductive silver paste of the overall comparative example 1 or 2, the content of the micron-sized sheet or spherical silver powder is about 80.0 wt%, p-aminophenol type epoxy The content of the compound is about 19.3 wt%, and the content of 4-methyl-2-phenylimidazole is about 0.7 wt%; based on the weight of the conductive silver paste of the overall comparative example 5, the content of the micron-sized flake silver powder is about 88.0 wt%. The content of the p-aminophenol type epoxy compound is about 11.6 wt%, and the content of 4-methyl-2-phenylimidazole is about 0.4 wt%.

Comparative example 3 : Conductive silver glue

The conductive silver paste of Comparative Example 3 was also roughly prepared by the method as described in Example 1, except that the ratio shown in Table 2 below was used, and the comparative example was a bisphenol A type epoxy. The resin was substituted for the p-aminophenol type epoxy compound of Example 1.

Specifically, micron-sized flake silver powder, silver nitrate, bisphenol A type epoxy resin, 4-methyl-2-phenylimidazole, and (3-glycidoxypropyl)trimethoxy group are used in the process. After the decane is uniformly stirred, it is dispersed and mixed by a three-roller, and then defoamed by a public-rotation defoaming machine to obtain a finished product of the final conductive silver paste.

It can be calculated from the ratio shown in Table 2 below: based on the weight of the conductive silver paste of the overall comparative example 3, the content of the micron-sized flaky silver powder is about 70.6 wt%, and the content of silver nitrate is about 11.8 wt%, bisphenol A. The type of epoxy resin is about 17.1% by weight, and the content of 4-methyl-2-phenylimidazole is about 0.6% by weight.

Comparative example 4 : Conductive silver glue

The conductive silver paste of Comparative Example 4 was also prepared by the method as described in Example 1, except that the ratio shown in Table 2 below was used to prepare the conductive silver paste of Comparative Example 4. The raw material did not contain silver salt, and the addition amount of the micron-sized flaky silver powder was increased to 26.6 g.

It can be calculated from the ratio shown in Table 2 below: based on the weight of the conductive silver paste of the overall comparative example 4, the content of the micron-sized flaky silver powder is about 81.6 wt%, and the content of the p-aminophenol type epoxy compound is about 17.8. The wt%, 4-methyl-2-phenylimidazole content is about 0.6 wt%.

Comparative example 6 : Conductive silver glue

The conductive silver paste of Comparative Example 6 was also substantially prepared by the method as described in Example 1, except that the ratio of the micron-sized flaky silver powder was reduced to 22.5 as shown in Table 2 below. Gram, but the amount of silver nitrate added was increased to 5.5 grams.

It can be calculated from the ratio shown in Table 2 below: based on the weight of the conductive silver paste of the overall comparative example 6, the content of the micron-sized flaky silver powder is about 66.2 wt%, and the content of silver nitrate is about 16.2 wt%, p-aminophenol. The content of the epoxy compound is about 17.1% by weight, and the content of 4-methyl-2-phenylimidazole is about 0.6% by weight. Table 2: The ratio (unit: g) of the conductive silver paste in Comparative Examples 1 to 6 and the test results thereof.

Test case 1 : Viscosity

In this test example, the conductive silver pastes of Examples 1 to 3 and Comparative Examples 1 to 6 were used as samples to be tested, and the rotational speed was set to 5 rpm using a cone-type viscometer (BROOKFIELD DV-2) and a rotor of CPA-51Z. Each 1.5 g sample to be tested was continuously measured for 3 minutes to obtain a viscosity value of each sample to be tested. The test results are shown in Tables 1 and 2 above.

In order to adapt to the working condition of the conductive silver glue in different use conditions, the viscosity of the conductive silver glue should be adjusted accordingly; for example, the conductive silver glue for general dispensing purposes generally has a viscosity requirement of less than 20000 cps; Silver glue, its viscosity demand is generally below 100000 cps. As shown in the results of Tables 1 and 2 above, the viscosity of the conductive silver paste of Examples 1 to 3 is not more than 20,000 cps by controlling the composition of the conductive silver paste, so that the workability of the conductive silver paste can be ensured. In contrast, in Comparative Example 5, since the content of the micron-sized flaky silver powder in the conductive silver paste of Comparative Example 5 was as high as 88 wt%, the viscosity of the conductive silver paste of Comparative Example 5 exceeded 100,000 cps, and the operation of the conductive silver paste was deteriorated. Sex. In particular, when the content of the silver salt in the conductive silver paste of Comparative Example 6 is as high as 16.2 wt%, the viscosity thereof is increased in a short time, and the test piece cannot be produced in the subsequent thrust and conductivity test; Excess silver salt can significantly affect the workability of conductive silver paste.

Test case 2 : Conductivity

In this test example, a plurality of alumina substrates were prepared, and silver palladium electrodes were respectively formed on both ends of each alumina ceramic substrate; then, a screen printing machine (Newlong DP-320) was used to deposit a silver-palladium electrode on the alumina substrate. A layer of silver paste is printed to form a conductive path; finally, after continuously curing at a curing temperature of 150 ° C for 90 minutes, a conductive silver layer is formed between the silver palladium electrodes.

Thereafter, the resistance value (R, in units of mΩ) between the silver electrode and the palladium electrode is measured in ohms (Hioki KY-90); the thickness (h) of the conductive silver layer formed by curing each conductive silver paste is The measurement was carried out by a film thickness meter (NSK Toyko RM-3544) in units of micrometers (μm). Accordingly, the volume resistivity (ρ) of each of the conductive silver layers can be calculated from ρ (Ω-cm) = R × h × 10 ^-7 , and the measurement results are also shown in Tables 1 and 2 above.

The results of Table 1 and Table 2 above show that by controlling the composition of the conductive silver paste, it is ensured that the conductive silver layer cured by the conductive silver paste of Examples 1 to 3 has a volume resistivity of less than 4.5 × 10 ^-4 W. Below -cm, the conductive silver layer formed by curing the conductive silver paste of Examples 1 to 3 has better conductivity. In contrast, the conductive silver paste of Comparative Examples 1, 2 and 4, since the conductive silver paste of the comparative examples does not contain any silver salt, the conductive silver layer cured by the conductive silver paste of Comparative Examples 1, 2 and 4 The volume resistivity is as high as 5×10 ^-4 W.cm or more, and the volume resistivity of the conductive silver layer cured by the conductive silver paste of Examples 1 to 3 is about 10 to 100 times higher, which shows that The conductive silver paste of the comparative example is inferior in electrical conductivity. In Comparative Example 2, the micron-sized spherical silver powder is used, and since the contact electric conduction effect between the micron-sized spherical silver powder is not as excellent as the micron-sized flake silver powder, it is difficult to form a stable conductive path under the same silver powder content rate. The volume resistivity of the conductive silver layer cured by the conductive silver paste of Comparative Example 2 could not be measured.

It can be seen that by incorporating the silver salt and the aminophenol type epoxy compound into the conductive silver paste, the present invention can use the micron-sized silver powder to greatly reduce the curing of the conductive silver paste of Examples 1 to 3. The volume resistivity of the conductive silver layer is thus achieved for the purpose of improving conductivity before low production cost.

Test case 3 :thrust

Before the thrust test, the test piece was prepared by first preparing an alumina substrate, and using the conductive silver pastes of Examples 1 to 3 and Comparative Examples 1 to 6, respectively, a tantalum wafer having a size of 1 mm × 1 mm was fixed to each alumina. On the substrate, after further curing at a curing temperature of 150 ° C for 90 minutes, a conductive silver layer was obtained.

After that, the horizontal thrust of the conductive silver layer cured by each conductive silver paste was tested by a push-pull machine (Dage 4000). When the measured horizontal thrust is greater than 5 kg (kgf), the adhesion of the conductive silver layer is good, indicated by "○" in Tables 1 and 2 above; when the measured horizontal thrust is less than When 4 kgf, the adhesion of the conductive silver layer is poor, and it is represented by "Í" in Tables 1 and 2 above.

The results of Table 1 and Table 2 above show that the conductive silver layer cured by the conductive silver paste of Examples 1 to 3 can have sufficient thrust strength to control the conductive silver layer by controlling the composition of the conductive silver paste. The closeness. In contrast, in Comparative Example 5, since the content of the micron-sized flaky silver powder in the conductive silver paste of Comparative Example 5 was as high as 88 wt%, the thrust strength of the conductive silver layer which was cured by the conductive silver paste of Comparative Example 5 was drastically lowered.

Discussion of experimental results

The experimental results of the above Test Examples 1 to 3 show that when the conductive silver paste contains both silver powder, silver salt, aminophenol type epoxy compound and curing agent, the aminophenol type epoxy compound can simultaneously act as a binder and a reducing agent. The role of the conductive silver paste of Examples 1 to 3 not only has a low viscosity, but also has good workability, and the conductive silver layer which is cured can also obtain high conductivity and thrust strength. Further comparing the results of Example 1 and Example 2, it can be seen that the inclusion of the coupling agent in the conductive silver paste enables the conductive silver paste of Example 2 to have a lower viscosity and further enhance the cured silver. The conductivity of the layer. Comparing the results of Example 1 and Example 3, it can be seen that the micron-sized spherical silver powder is not as easy to contact as the micron-sized silver powder, but the conductive silver paste of the third embodiment also contains an appropriate amount of silver salt and aminophenol ring. Oxygen compound and curing agent, so the volume resistivity of the conductive silver paste of Example 3 can still be controlled below 4.5×10 ^-4 W-cm, that is, the conductive silver layer cured by the conductive silver paste can have good electrical conductivity. Sex.

Further, from the comparison results of the first embodiment and the comparative example 1, it is understood that the conductive silver paste of the first embodiment is further added to the conductive silver paste of the comparative example 1 to form the conductive silver paste of the first embodiment, and the volume resistivity of the conductive silver layer can be specifically determined. From 1.12 × 10 ^-3 W-cm (Comparative Example 1), it was lowered to 8.67 × 10 ^-5 W-cm (Example 1); from the results of Comparative Example 3 and Comparative Example 2, it was found that the conductivity of Comparative Example 2 was obtained. The silver paste does not contain any silver salt, so the volume resistivity of the conductive silver layer formed by the conductive silver paste cannot be stably measured; in contrast, if the silver salt is further added to the conductive silver paste of Comparative Example 2 The conductive silver paste of the third embodiment can smoothly improve the conductivity of the conductive silver paste, and reduce the volume resistivity of the conductive silver paste containing the micron-sized spherical silver powder (Example 3) to a level of 10 ^-4 W-cm. .

From the results of Comparative Examples 1, 4 and 5, it was found that the content of the micron-sized flaky silver powder in the conductive silver paste was increased from 80 wt% (Comparative Example 1) to 81.6 wt% (Comparative Example 4), or even 88 wt%. (Comparative Example 5), although it helps to improve the conductivity of the conductive silver paste, its viscosity is remarkably increased to more than 100,000 cps, which makes the workability of the conductive silver paste greatly reduced, and the use of Comparative Example 5 is utilized. The conductive silver layer cured by the conductive silver glue has the disadvantage of greatly reducing the thrust, and has not met the characteristics of the conductive silver glue at the application end. In contrast, as is clear from the results of Example 1, if the conductive silver paste contains both a silver salt and an aminophenol-type epoxy compound, the conductivity can be improved at a lower silver powder amount, and at the same time The workability of the conductive silver paste and the thrust strength of the conductive silver layer.

Further, the ratio of the conductive silver paste of the first embodiment and the comparative example 4 was compared. According to the silver content of the silver nitrate of 63.5%, the silver content of the conductive silver paste of the first embodiment was substantially the same as that of the conductive silver paste of the comparative example 4. The amount of silver. Accordingly, from the results of Example 1 and Comparative Example 4, it was found that the conductive silver paste containing silver powder and silver salt (Example 1) was superior to the conductive silver paste containing only silver powder at the same silver content (Comparative Example 4). The volume of resistivity of the cured conductive silver layer is low, and it is confirmed again that the conductive silver paste contains an appropriate amount of silver powder and silver salt to help improve the conductivity of the conductive silver paste.

In addition, it can be seen from the results of Comparative Example 6 that if the content of the silver salt in the conductive silver paste is increased and the content of the micron-sized flaky silver powder is decreased, the viscosity of the conductive silver paste is suddenly increased in a short time; If the content of silver salt is too high, it will improperly affect the workability of the conductive silver paste.

Comparing the results of Example 1 and Comparative Example 3, it can be seen that the use of an aminophenol type epoxy compound in place of the bisphenol A type epoxy resin can maintain the viscosity of the conductive silver paste and the thrust strength of the cured conductive silver layer. The volume resistivity of the conductive silver layer is significantly reduced, so that the conductive silver layer has better conductivity. It can be seen that when the conductive silver paste contains both the silver salt and the aminophenol type epoxy compound, the aminophenol type epoxy compound and the silver salt can complement each other, thereby specifically improving the conductive silver paste and curing thereof. The conductivity of the conductive silver layer.

In summary, this creation does not require the use of nano-scale silver particles, by mixing silver powder, silver salt, aminophenol-type epoxy compound and curing agent, etc., can maintain its original workability and thrust strength. Under the premise, the conductivity of the conductive silver glue is significantly improved, thereby solving the problem that the high-conductivity silver glue of the prior art is too expensive to manufacture.

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Claims (12)

A conductive silver paste comprising a silver powder, a silver salt, an aminophenol type epoxy compound, and a curing agent. The conductive silver paste according to claim 1, wherein the content of the aminophenol-type epoxy compound is from 5 to 35 weight percent based on the total amount of the total conductive silver paste. The conductive silver paste according to claim 1, wherein the aminophenol type epoxy compound has a structure as shown below: Wherein R ¹ to R ³ are each independently hydrogen, methyl or epoxy, and at least one of R ¹ to R ³ is an epoxy group. The conductive silver paste according to claim 3, wherein R ¹ and R ² are an epoxy group, and R ³ is hydrogen, a methyl group or an epoxy group. The conductive silver paste of claim 1, wherein the silver powder is micron-sized silver powder. The conductive silver paste according to claim 5, wherein the micron-sized silver powder is micron-sized flake silver powder or micron-sized spherical silver powder. The conductive silver paste according to claim 1, wherein the content of the silver powder and the silver salt is from 70% by weight to 95% by weight based on the total of the total conductive silver paste. The conductive silver paste according to claim 1, wherein the content of the silver powder is from 65 to 90% by weight based on the total amount of the total conductive silver paste, and the content of the silver salt is from 5 to 15% by weight. The conductive silver paste of claim 1, wherein the silver salt is silver nitrate, silver acetate or a combination thereof. The conductive silver paste according to claim 1, wherein the curing agent is contained in an amount of 0.1% by weight to 20% by weight based on the total of the total conductive silver paste. The conductive silver paste according to claim 1, wherein the conductive silver paste further comprises a coupling agent, and the coupling agent is contained in an amount of 0.01% by weight to 3% by weight based on the total of the total conductive silver paste. A conductive silver layer obtained by curing the conductive silver paste according to any one of claims 1 to 11, wherein the conductive silver layer has a volume resistivity of less than 2 × 10 ^-4 Ω-cm.