Three Benefits of Grinding and Polishing Ceramic Substrates

Before metallization of ceramic substrates, most of them require surface grinding and polishing of the ceramic substrate, which can be done in either single or double sided ways. The main purpose is to remove attachments on its surface, improve flatness, and obtain a thinner metallized layer. So grinding and polishing are crucial for ceramic substrates, as they directly affect the effectiveness of ceramic metallization.

Due to the high hardness, brittleness, and susceptibility to cracking of ceramic substrates, surface processing is difficult, and it is difficult to ensure the quality and integrity of the surface and subsurface after processing. The surface processing of ceramics not only requires high dimensional and shape accuracy, low surface roughness, and good surface integrity, but also requires the surface of ceramic substrates to be defect free, damage free, and ultra smooth. Therefore, achieving super smooth and flat surface of ceramic substrates is the key and development trend of substrate material preparation technology.

Different grinding methods have a significant impact on the flatness, productivity, and yield of the substrate, and subsequent processes cannot improve the accuracy of the geometric shape of the substrate. During the grinding and polishing process, the selection of polishing method, equipment, and grinding fluid is crucial. Especially when encountering thin plate thickness requirements, grinding becomes a very difficult process to control. To ensure that the ceramic substrate does not shatter, and to meet the requirements of dimensional accuracy and surface roughness, it is a test of the maturity of the process.

Three major benefits of ceramic substrate grinding and polishing:

1、 Can obtain finer patterns

After fine grinding and polishing processes, the ceramic substrate can obtain finer lines in patterns, which is conducive to the ability to design more dense circuits and facilitate the design of circuits with fine spacing and high-density interconnections. Controlling the convexity and flatness of the substrate can greatly improve the transfer of mask patterns to the substrate surface, thereby obtaining finer lines and space. For thin film circuit applications with a wire thickness of 1mil (0.0254mm) and thick film circuits with a wire thickness of 5mil, substrates without precision polishing can basically meet the requirements. However, if finer lines are added to these substrates, poor pattern clarity will occur, which will affect current flow or reduce circuit performance.

2、 Better parallelism of the upper and lower surfaces can be obtained

Grinding and polishing the substrate can improve the parallelism (thickness tolerance) between the upper and lower surfaces. The advantage of doing so is that when the substrate is metallized and patterned, the capacitance and inductance of the substrate can be more strictly controlled. Due to the fact that capacitance and inductance are the main factors determining impedance, improving parallelism can improve the predictability and performance of RF and microwave circuits.

3、 Thinner metallization layer can be obtained

Polishing reduces the amplitude of peaks and valleys on the substrate surface, allowing for the use of very thin metallized layers. The thinner resistance layer increases the material's sheet resistance, allowing for higher resistance values when using thin film technology - especially when using serpentine patterns.