CN111641016A - Preparation method of surface electrode of ceramic filter - Google Patents

Abstract

The invention provides a preparation method of a ceramic filter surface electrode, which comprises the following steps of S1: cleaning the surface of the ceramic substrate to obtain a first ceramic substrate; s2: preparing a first copper plating layer on the first ceramic substrate by using a film coating process, wherein the thickness of the first copper plating layer is 100 nm-800 nm, and thus a second ceramic substrate is obtained; s3: and preparing a second tin plating layer coated on the surface of the copper by using the second ceramic substrate through a film coating process, wherein the thickness of the second tin plating layer is 50nm to 900 nm. The preparation method of the ceramic filter electrode provided by the invention does not need large-scale high-power high-vacuum equipment, has low cost, and greatly reduces the production cost by adopting copper to replace silver.

Description

Preparation method of surface electrode of ceramic filter

Technical Field

The invention relates to the field of filters, in particular to a preparation method of a surface electrode of a ceramic filter.

Background

The ceramic filter is generally made of lead zirconate titanate ceramic material, metal is coated on two ends of a sheet-shaped ceramic material to form electrodes, and the electrodes have a piezoelectric effect after direct-current high-voltage polarization. As a key component for frequency selection, the filter has the characteristics of stability and good anti-interference performance, and is widely applied to various electronic products such as televisions, video recorders, radios and the like as a frequency selection element. The filter has the advantages of stable performance, no need of adjustment, low price and the like, and replaces the traditional LC filter network. The preparation process of the electrode coating on the surface of the filter has critical influence on the performance of the filter, and the preparation of the electrode of the ceramic filter mainly comprises two methods: firstly, paste silver paste is printed on the surface of a ceramic wafer, and a uniform silver film is formed on the surface of the ceramic wafer through drying, high-temperature firing and other process conditions; and secondly, silver is sputtered or evaporated on the surface of the ceramic wafer to form an electrode by adopting high vacuum equipment under high vacuum degree. However, both of these methods have certain defects, for example, when paste-like silver paste is printed on the surface of the ceramic wafer and then sintered at high temperature, the problem of insufficient bonding adhesion between the silver electrode and the ceramic wafer interface often exists, and the yield is low. The evaporation and sputtering needs coating equipment capable of providing high vacuum and high power, and the preparation cost is high. In addition, silver itself is relatively expensive and costly. How to realize low cost and simple process, and the process controllability of the metal coating while ensuring the compactness and stable performance is the future trend of the process research and development of the metal electrode of the ceramic filter.

Disclosure of Invention

Aiming at the technical problems in the prior art, the invention provides the method for preparing the surface electrode of the ceramic filter, which is simple to operate, does not need large-scale high-power high-vacuum equipment, is low in cost, adopts copper to replace silver, greatly reduces the production cost, and simultaneously solves the problem that the copper electrode is easy to oxidize due to the introduction of the second metal plating layer tin, thereby prolonging the service life of the electrode. A method for preparing a surface electrode of a ceramic filter comprises the following steps: s1: cleaning the surface of the ceramic substrate to obtain a first ceramic substrate;

s2: preparing a first copper plating layer on the first ceramic substrate by using a film coating process, wherein the thickness of the first copper plating layer is 100 nm-800 nm, and thus a second ceramic substrate is obtained;

the thickness of the copper plating layer can influence the conductivity of the electrode, when the thickness of the copper plating layer is 100nm to 800nm, the square resistance of the electrode is 0.01 to 0.5 ohm, and the square resistance of the electrode can better ensure the electric conductivity of the electrode.

S3: and preparing a second tin plating layer coated on the surface of the copper by using the second ceramic substrate through a film coating process, wherein the thickness of the second tin plating layer is 50nm to 900 nm.

The thickness of the tin coating can influence the oxidation resistance of the electrode, the square resistance of the electrode is 0.1-1 ohm when the thickness of the tin coating is 50 nm-900 nm, and the oxidation of the metal copper electrode can be well protected under the thickness of the coating.

Preferably, in S1, the ceramic substrate is selected from a lead zirconate titanate ceramic material or an aluminum-modified lead zirconate titanate ceramic material.

Preferably, the cleaning conditions of the surface of the ceramic substrate in S1 are as follows: and soaking the ceramic substrate in a strong acid or organic reagent for 30-90min at 30 ℃.

Preferably, the strong acid is selected from one of hydrochloric acid, nitric acid and sulfuric acid with a molar concentration of 15-30%, and the organic reagent is selected from one of ethanol, isopropanol, acetone and toluene.

Preferably, the coating process in S2 is electroless coating.

A method for preparing a surface electrode of a ceramic filter comprises the following chemical coating process: soaking the first ceramic substrate in a precursor solution containing copper ions, wherein the film plating time is 20-30min, the reaction temperature is 25 ℃, the precursor solution comprises target salt, a complexing agent, a PH buffering agent and formaldehyde, the concentration of the target salt is 5g/L-30g/L, the concentration of the complexing agent is 5g/L-15g/L, the concentration of the PH buffering agent is 10g/L-20g/L, and the concentration of the formaldehyde is 0.36% -0.72%.

In the chemical plating process, the complexing agent is beneficial to maintaining the stability of the target salt in the plating solution, so that long-time chemical plating is realized without decomposition, and good plating appearance is obtained. The PH buffering agent may act as an auxiliary complexing agent to further improve the stability of the plating solution and prevent the deleterious effects imparted to the plating solution by the impurity ions dissolved from the metal substrate. The temperature of the plating solution is 20-80 ℃, the stability of metal ions in the plating solution is not facilitated by excessively high temperature, the plating solution is turbid and decomposed, and the chemical plating rate is reduced by excessively low temperature.

Preferably, the target salt is selected from one or more of copper sulfate, copper chloride and copper nitrate; the complexing agent is one or more selected from sodium ethylene diamine tetracetate or ethylene diamine tetraacetic acid, sodium nitrilotriacetate, diethylenetriamine pentaacetic acid and polyethylene glycol; the pH buffering agent is one or more selected from sodium hydroxide, potassium dihydrogen phosphate, disodium hydrogen phosphate and boric acid.

Preferably, the coating process in S3 is electroless coating.

Preferably, the chemical plating process is as follows: and soaking the second ceramic substrate in a precursor solution containing tin ions, wherein the film plating time is 60-120min, the reaction temperature is 30-50 ℃, the precursor solution comprises target salt, a complexing agent, a PH buffering agent and a reducing agent, the concentration of the target salt is 10-20g/L, the concentration of the complexing agent is 45-60 g/L, the concentration of the PH buffering agent is 15-30 g/L, and the concentration of the reducing agent is 10-150 g/L.

Preferably, the target salt is selected from one of tin methane sulfonate, tin ethane sulfonate, tin 2-hydroxypropyl-1-sulfonate, tin p-phenolsulfonate, stannous chloride, stannous sulfate, stannous oxide, stannous fluoroborate and stannous sulfosuccinate; the complexing agent is selected from one or more of thiourea, diethyl thiourea, 1, 3-dimethyl thiourea, trimethyl thiourea, N-diisopropyl thiourea, allyl thiourea, acetyl thiourea, ethyl thiourea and 1, 3-diphenyl thiourea; the reducing agent is selected from one or more of hypophosphorous acid, phosphorous acid, pyrophosphoric acid, polyphosphoric acid and phosphate compounds of NH, Na, K and Ca; the pH buffering agent is one or more selected from EDTA, hydroxyethyl ethylene diamine triacetic acid, iminodiacetic acid, iminodipropionic acid, nitrotriacetic acid, diethylenetriamine pentaacetic acid, triethylenetetramine hexaacetic acid, ethylenediamine, hexamethylenetetramine, citric acid, tartaric acid, gluconic acid, succinic acid, malonic acid, glycol acid, glycine, tripolyphosphoric acid and 1-hydroxyethyl-1, 1-diphosphonic acid.

The beneficial effects of the invention at least comprise:

(1) the preparation method of the ceramic filter electrode provided by the invention does not need large-scale high-power high-vacuum equipment, has low cost, adopts copper to replace silver, and greatly reduces the production cost;

(2) the reaction concentration, the temperature, the PH and other experimental conditions in the coating experiment are regulated and controlled, so that the thickness of the coating can be well regulated;

(3) meanwhile, due to the introduction of the second metal plating tin, the problem that the copper electrode is easy to oxidize is solved, and the service life of the electrode is prolonged.

Drawings

FIG. 1 is a schematic view of a process for coating a surface of a ceramic substrate.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the scope of the present invention.

Example 1

This example provides a method for preparing a ceramic filter electrode, the experimental flow is shown in fig. 1.

1. And pre-cleaning the ceramic substrate.

And (3) cleaning the lead zirconate titanate ceramic by using 30% hydrochloric acid, then sequentially cleaning the lead zirconate titanate ceramic again by using acetone and isopropanol, and drying the lead zirconate titanate ceramic to obtain the pretreated ceramic substrate.

2. And preparing a first plating layer.

The pretreated ceramic substrate was immersed for 20min in a first solution containing cupric chloride and ethylenediaminetetraacetic acid (EDTA), NaoH, polyethylene glycol. The concentration of copper chloride is 10g/L, the concentration of EDTA is 15g/L, the concentration of NaOH is 20g/L, the concentration of polyethylene glycol is 1-8g/L, the concentration of formaldehyde is 0.36%, the reaction temperature is room temperature, and the ceramic substrate plated with the copper film is obtained, wherein the thickness of the copper film is 400 nm.

3. And preparing a second plating layer.

And soaking the copper-plated ceramic substrate in a second solution containing stannous oxide, thiourea, sodium citrate dihydrate, EDTA and polyphosphoric acid for about 1.5 hours. The concentration of stannous oxide is 18g/L, the concentration of EDTA is 2.5g/L, the concentration of sodium citrate dihydrate is 20g/L, the concentration of thiourea is 60g/L, the concentration of reducer polyphosphoric acid is 10g/L, the reaction temperature is 45 ℃, and the thickness of the tin film is 400nm, so that the ceramic substrate plated with the tin film and the copper film is obtained.

Example 2

This example provides a method for preparing a ceramic filter electrode, the experimental flow is shown in fig. 1.

1. And pre-cleaning the ceramic substrate.

And cleaning the lead zirconate titanate ceramic by using a mixed solution of hydrochloric acid and nitric acid, then cleaning the lead zirconate titanate ceramic again by using alcohol, and drying the lead zirconate titanate ceramic to obtain the pretreated ceramic substrate.

2. And preparing a first plating layer.

The pretreated ceramic substrate was immersed for 20min in a first solution containing copper sulfate and EDTA, NaoH, polyethylene glycol. The copper sulfate concentration is 20g/L, preferably, the EDTA concentration is 15g/L, the NaOH concentration is 10g/L, preferably, the polyethylene glycol concentration is 1-8g/L, the formaldehyde concentration is 0.4%, the reducing agent polyphosphoric acid concentration is 10g/L, the reaction temperature is room temperature, and the ceramic substrate plated with the copper film is obtained, and the thickness of the copper film is 700 nm.

3. And preparing a second plating layer.

And soaking the copper-plated ceramic substrate in a second solution containing tin ethanesulfonate, diethyl thiourea, sodium citrate dihydrate, EDTA and phosphorous acid for about 1.5 h. The concentration of ethane tin sulfonate is 18-20g/L, the concentration of EDTA is 2.5g/L, the concentration of sodium citrate dihydrate is 20g/L, the concentration of diethyl thiourea is 50-60g/L, the concentration of reducer polyphosphoric acid is 10g/L, the reaction temperature is 45 ℃, and the thickness of a tin film is 600nm, so that the ceramic substrate coated with the tin film and the copper film is obtained.

Example 3

This example provides a method for preparing a ceramic filter electrode, the experimental flow is shown in fig. 1.

1. And pre-cleaning the ceramic substrate.

And (3) cleaning the lead zirconate titanate ceramic by using 30% hydrochloric acid, then sequentially cleaning the lead zirconate titanate ceramic again by using acetone and isopropanol, and drying the lead zirconate titanate ceramic to obtain the pretreated ceramic substrate.

2. And preparing a first plating layer.

The pretreated ceramic substrate was immersed in a first solution containing copper nitrate and EDTA, NaOH, polyethylene glycol for 30 min. The concentration of copper nitrate is 10-20g/L, preferably, the concentration of diethylenetriamine pentaacetic acid is 15g/L, the concentration of disodium hydrogen phosphate is 20g/L, the concentration of formaldehyde is 0.36%, preferably, the concentration of polyethylene glycol is 8g/L, and the reaction temperature is room temperature, so that the ceramic substrate plated with the copper film is obtained, and the thickness of the copper film is 600 nm.

3. And preparing a second plating layer.

And soaking the copper-plated ceramic substrate in a second solution containing stannous fluoroborate, 1, 3-diphenylthiourea, sodium citrate dihydrate and EDTA for about 1.5 hours. The concentration of stannous fluoroborate is 18-20g/L, the concentration of EDTA is 2.5g/L, the concentration of sodium citrate dihydrate is 20g/L, the concentration of 1, 3-diphenylthiourea is 50-60g/L, the concentration of polyphosphoric acid serving as a reducing agent is 10g/L, the reaction temperature is 45 ℃, and the thickness of a tin film is 800nm, so that the ceramic substrate plated with the tin film and the copper film is obtained.

Comparative example 1

1. And pre-cleaning the ceramic substrate.

And (3) cleaning the lead zirconate titanate ceramic by using 30% hydrochloric acid, then sequentially cleaning the lead zirconate titanate ceramic again by using acetone and isopropanol, and drying the lead zirconate titanate ceramic to obtain the pretreated ceramic substrate.

2. And preparing a first plating layer.

The pretreated ceramic substrate was immersed in a first solution containing cupric chloride and ethylenediaminetetraacetic acid (EDTA), NaoH, polyethylene glycol for 10 min. The concentration of copper chloride is 5g/L, the concentration of EDTA is 15g/L, the concentration of NaOH is 20g/L, the concentration of polyethylene glycol is 8g/L, the concentration of formaldehyde is 0.36%, and the reaction temperature is room temperature, so that the ceramic substrate plated with the copper film is obtained, and the thickness of the copper film is 50 nm.

3. And preparing a second plating layer.

And soaking the copper-plated ceramic substrate in a second solution containing stannous oxide, thiourea, sodium citrate dihydrate, EDTA and polyphosphoric acid for 1 h. The concentration of stannous oxide is 9g/L, the concentration of EDTA is 2.5g/L, the concentration of sodium citrate dihydrate is 20g/L, the concentration of thiourea is 60g/L, the concentration of reducer polyphosphoric acid is 10g/L, the reaction temperature is 45 ℃, and the thickness of the tin film is 20nm, so that the ceramic substrate plated with the tin film and the copper film is obtained.

Comparative example 2

1. And pre-cleaning the ceramic substrate.

And (3) cleaning the lead zirconate titanate ceramic by using 30% hydrochloric acid, then sequentially cleaning the lead zirconate titanate ceramic again by using acetone and isopropanol, and drying the lead zirconate titanate ceramic to obtain the pretreated ceramic substrate.

2. And preparing a first plating layer.

The pretreated ceramic substrate was immersed in a first solution containing cupric chloride and ethylenediaminetetraacetic acid (EDTA), NaoH, polyethylene glycol for 30 min. The concentration of palladium salt is 30g/L, the concentration of EDTA is 15g/L, the concentration of NaOH is 20g/L, the concentration of polyethylene glycol is 8g/L, the concentration of formaldehyde is 0.36%, and the reaction temperature is room temperature, so that the ceramic substrate plated with the copper film is obtained, and the thickness of the copper film is 2 μm.

3. And preparing a second plating layer.

And soaking the copper-plated ceramic substrate in a second solution containing stannous oxide, thiourea, sodium citrate dihydrate, EDTA and polyphosphoric acid for 1 h. The concentration of stannous oxide is 20g/L, the concentration of EDTA is 2.5g/L, the concentration of sodium citrate dihydrate is 20g/L, the concentration of thiourea is 60g/L, the concentration of reducer polyphosphoric acid is 10g/L, the reaction temperature is 45 ℃, and the thickness of the tin film is 1 μm, thus obtaining the ceramic substrate plated with the tin film and the copper film.

Comparative example 3

1. And pre-cleaning the ceramic substrate.

And (3) cleaning the lead zirconate titanate ceramic by using 30% hydrochloric acid, then sequentially cleaning the lead zirconate titanate ceramic again by using acetone and isopropanol, and drying the lead zirconate titanate ceramic to obtain the pretreated ceramic substrate.

2. And preparing a first plating layer.

The pretreated ceramic substrate was immersed for 20min in a first solution containing cupric chloride and ethylenediaminetetraacetic acid (EDTA), NaoH, polyethylene glycol. The concentration of copper chloride is 10g/L, the concentration of EDTA is 15g/L, the concentration of NaOH is 20g/L, the concentration of polyethylene glycol is 1-8g/L, the concentration of formaldehyde is 0.36%, the reaction temperature is room temperature, and the ceramic substrate plated with the copper film is obtained, wherein the thickness of the copper film is 400 nm.

3. Preparation of the second coating

Electroplating nickel on the surface of copper, wherein the formula of the electroplated nickel is 100-200 g/L nickel sulfate; 10-30g/L of nickel chloride; boric acid 10-30g/L, and the thickness of the nickel layer is 2 μm.

4. Preparation of the third coating

And soaking the copper-plated ceramic substrate in a second solution containing stannous oxide, thiourea, sodium citrate dihydrate, EDTA and polyphosphoric acid for about 1.5 hours. The concentration of stannous oxide is 18g/L, the concentration of EDTA is 2.5g/L, the concentration of sodium citrate dihydrate is 20g/L, the concentration of thiourea is 60g/L, the concentration of polyphosphoric acid is 10g/L, the reaction temperature is 45 ℃, and the thickness of the tin film is 400nm, so that the ceramic substrate plated with the tin film, the nickel layer and the copper film is obtained.

Table 1 comparative example performance comparative table

Serial number

Thickness of copper layer

Thickness of tin layer

Thickness of nickel layer

Bonding performance

Loss of insertion

Resonant frequency

Example 1

400nm

400nm

-

Good effect

4.4dB

6.5M±60KC

Example 2

700nm

600nm

-

Good effect

4.2dB

6.5M±30KC

Example 3

600nm

800nm

-

Good effect

4.3dB

6.8M±30KC

Comparative example 1

50nm

20nm

-

In general

5.3dB

4.1M±40KC

Comparative example 2

2μm

1μm

-

In general

5.0dB

3.2M±50KC

Comparative example 3

400nm

400nm

2μm

Good effect

4.8dB

5.5M±60KC

Finally, it is noted that the above-mentioned preferred embodiments illustrate rather than limit the invention, and that, although the invention has been described in detail with reference to the above-mentioned preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention as defined by the appended claims.

Claims (10)

1. A method for preparing a surface electrode of a ceramic filter is characterized by comprising the following steps:

s1: cleaning the surface of the ceramic substrate to obtain a first ceramic substrate;

s2: preparing a first copper plating layer on the first ceramic substrate by using a film coating process, wherein the thickness of the first copper plating layer is 100 nm-800 nm, and thus a second ceramic substrate is obtained;

s3: and preparing a second tin plating layer coated on the surface of the copper by using the second ceramic substrate through a film coating process, wherein the thickness of the second tin plating layer is 50nm to 900 nm.

2. The method according to claim 1, wherein in S1, the ceramic substrate is selected from a lead zirconate titanate ceramic material or an aluminum-modified lead zirconate titanate ceramic material.

3. The method for preparing a surface electrode of a ceramic filter according to claim 1, wherein the cleaning conditions of the surface of the ceramic substrate in S1 are as follows: and soaking the ceramic substrate in a strong acid or organic reagent for 30-90min at 30 ℃.

4. The method according to claim 3, wherein the strong acid is selected from hydrochloric acid, nitric acid, and sulfuric acid with a molar concentration of 15-30%, and the organic reagent is selected from ethanol, isopropanol, acetone, and toluene.

5. The method according to claim 1, wherein the coating process in S2 is electroless plating.

6. The method for preparing the surface electrode of the ceramic filter according to claim 5, wherein the electroless plating process comprises: soaking the first ceramic substrate in a precursor solution containing copper ions, wherein the film plating time is 20-30min, the reaction temperature is 25 ℃, the precursor solution comprises target salt, a complexing agent, a PH buffering agent and formaldehyde, the concentration of the target salt is 5g/L-30g/L, the concentration of the complexing agent is 5g/L-15g/L, the concentration of the PH buffering agent is 10g/L-20g/L, and the concentration of the formaldehyde is 0.36% -0.72%.

7. The method for preparing a surface electrode of a ceramic filter according to claim 6, wherein the target salt is selected from one or more of copper sulfate, copper chloride and copper nitrate; the complexing agent is one or more selected from sodium ethylene diamine tetracetate or ethylene diamine tetraacetic acid, sodium nitrilotriacetate, diethylenetriamine pentaacetic acid and polyethylene glycol; the pH buffering agent is one or more selected from sodium hydroxide, potassium dihydrogen phosphate, disodium hydrogen phosphate and boric acid.

8. The method according to claim 1, wherein the coating process in S3 is electroless plating.

9. The method for preparing the surface electrode of the ceramic filter according to claim 8, wherein the electroless plating process comprises: and soaking the second ceramic substrate in a precursor solution containing tin ions, wherein the film plating time is 60-120min, the reaction temperature is 30-50 ℃, the precursor solution comprises target salt, a complexing agent, a PH buffering agent and a reducing agent, the concentration of the target salt is 10-20g/L, the concentration of the complexing agent is 45-60 g/L, the concentration of the PH buffering agent is 15-30 g/L, and the concentration of the reducing agent is 10-150 g/L.

10. The method according to claim 9, wherein the target salt is selected from the group consisting of tin methane sulfonate, tin ethane sulfonate, tin 2-hydroxypropyl-1-sulfonate, tin p-phenolsulfonate, stannous chloride, stannous sulfate, stannous oxide, stannous fluoroborate, and stannous sulfosuccinate; the complexing agent is selected from one or more of thiourea, diethyl thiourea, 1, 3-dimethyl thiourea, trimethyl thiourea, N-diisopropyl thiourea, allyl thiourea, acetyl thiourea, ethyl thiourea and 1, 3-diphenyl thiourea; the reducing agent is selected from one or more of hypophosphorous acid, phosphorous acid, pyrophosphoric acid, polyphosphoric acid and phosphate compounds of Na, K and Ca; the pH buffering agent is one or more selected from EDTA, hydroxyethyl ethylene diamine triacetic acid, iminodiacetic acid, iminodipropionic acid, nitrotriacetic acid, diethylenetriamine pentaacetic acid, triethylenetetramine hexaacetic acid, ethylenediamine, hexamethylenetetramine, citric acid, tartaric acid, gluconic acid, succinic acid, malonic acid, glycol acid, glycine, tripolyphosphoric acid and 1-hydroxyethyl-1, 1-diphosphonic acid.

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