Single layer capacitor is widely used in microwave communication, microwave power amplifier, microwave integrated circuit, etc., playing the role of RF bypass, filtering, tuning and so on. The existing preparation process of single layer capacitor is: ceramic powder batching→ ball milling→ isostatic pressing forming→ sintered ceramic ingot→ slicing→ printing silver paste with screen printing method→ drying→ silver sintering→ dicing. However, the use of silver electrodes and the use of screen printing method have the following problems:

First, the silver paste is easily contaminated in the screen printing and drying process, and the obtained silver electrode is easy to oxidize and yellowing, resulting in poor stability and reliability of the product;

Second, the process of preparing silver paste in the early stage and drying silver paste and sintering silver electrode in the later stage is cumbersome;

Third, the thickness of the silver electrode layer prepared by printing is much thick and the surface of the ceramic substrate is unevenly covered, which is easy to peel and burr during the dicing process, and the loss of silver paste material is large;

Fourth, the silver layer will recrystallize when sintered at high temperature, and the crystal form will change and the performance will change, resulting in a decrease in the electrical properties of the product;

Fifth, the gas emitted during the process of high temperature silver sintering causes pollution to the environment.

In order to solve the above problems, EXSENSE Electronics Technology Co., Ltd. introduced a high-reliability Ir-Cu-Au composite electrode single layer capacitor, which has the advantages of great stability, high reliability, not easy aging, and thermal shock resistance. The specific preparation method is as follows:

1) Prepare ceramic substrate

The ceramic powder is matched according to the ceramic formula of conventional single layer capacitor, then the ceramic powder is ball-milled, isostatic pressed, sintered and sliced to obtain a flake ceramic substrate.

2) Primary cleaning

The ceramic substrate is treated with cleaning solution, then cleaned by an ultrasonic machine with cleaning time of 5±1 minutes, then dried at 100±5℃ for 30±5 minutes.

3) Secondary cleaning

The ceramic substrate obtained by primary cleaning is put into the plasma cleaning machine for secondary cleaning, the cleaning time is 5±1 minutes, the drying temperature is 100±5℃, the drying time is 30±5 minutes, and the surface is activated at the same time.

4) Sputter the iridium layer

First vacuum the vacuum sputtering coating machine to the process range, then fill with argon gas as a working gas, with iridium as the target material, under the action of the electric field, Ar+ accelerates the bombardment of the target, sputters the target atoms onto the ceramic substrate, and sputters a layer of iridium on the two surfaces of the ceramic substrate, with a sputtering thickness of 0.01~2 microns.

5) Sputtering copper layer

First vacuum the vacuum sputtering coating machine to the process range, then fill with argon gas as a working gas, with copper as the target material, under the action of the electric field, Ar+ accelerates the bombardment of the target, sputters the target atoms onto the ceramic substrate, and sputters a layer of copper on the surface of the iridium layer on the surface of the ceramic substrate, with a sputtering thickness of 0.01~2 microns.

6) Sputter gold layer

First vacuum the vacuum sputtering coating machine to the process range, then fill argon gas as a working gas, with gold as the target material, under the action of the electric field, Ar+ accelerates the bombardment of the target, sputters the target atoms onto the ceramic substrate, and sputters a gold layer on the copper layer surface on the surface of the ceramic substrate, with a sputtering thickness of 0.01~1 micron.

7) Dice the ceramic substrate to obtain single layer capacitors.