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Science Classroom : Do you have machining problems? Do your workpieces always have pitting and orange peel? Do you want to know the application of nanotechnology? Here we have a series of industrial science tips to share with you! If you have any questions, please contact us directly and we will help you to solve your problems.

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Optimizing Stress Control During Wafer Grinding and Polishing: A Practical Guide to Improving Semiconductor Manufacturing Quality

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Stress issues in wafer grinding and polishing are critical to semiconductor manufacturing quality. Stresses originate from mechanical grinding, chemical mechanical polishing (CMP), and the properties of the wafer material, which can affect the surface flatness, roughness, and electrical properties of the wafer. To manage these stresses, improvements can be made by optimizing machining parameters, employing multi-step processes, local heating, and selecting the right supplier. Establishing standard operating procedures, regular training, and continuous improvement are all key strategies to improve production efficiency and product quality.

研磨-磨料介紹與代號
Science Classroom, A complete guide to grinding wheel technology

Grinding – Abrasives Introduction

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Essential Characteristics of Abrasives are: high hardness, toughness, chemical composition, thermal stability (strength), thermal stability (chemical stability), grain processing capability, mechanical strength, high grit size.
1. High Hardness: The hardness of the abrasive must be higher than the hardness of the workpiece.
2. Toughness: The ability to resist breaking under pressure or impact. Adequate toughness ensures that the micro-edges of the abrasive particles can perform cutting actions, and when dulled, they can create new cutting micro-edges.
3. Chemical Composition: The chemical composition of the abrasive reflects its quality and performance. The higher the purity, the better the properties. Aluminum oxide abrasives, for example, are categorized based on the content of aluminum oxide and impurities.
4. Thermal Stability (Strength): The abrasive must maintain its necessary physical and mechanical properties even at high temperatures, as the grinding zone temperature usually ranges from 400 to 1000°C.
5. Thermal Stability (Chemical Stability): The abrasive should be chemically stable, resistant to adhesion or diffusion reactions that could cause clogging or dulling of the tool.
6. Grain Processing Capability: The abrasive grains should be uniform, with a regular shape.
7. Mechanical Strength: Due to the repeated grinding forces, impact loads, and high grinding temperatures, the abrasive must have sufficient mechanical strength to withstand these effects.
8. High Grit Size: Abrasives should have a high grit size for effective material removal.

研磨拋光選用與表面粗糙度對照表
Product Applications, Science Classroom

Comparison Chart of Grinding Polishing and Surface Roughness

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In product manufacturing, surface quality is a critical factor. Surface roughness refers to the tiny irregularities on a surface that affect functionality and durability, while smoothness describes the degree of surface flatness and light reflection. Roughness impacts gloss; the rougher the surface, the lower the gloss. To improve gloss, polishing materials are often used to remove minor irregularities, achieving a smoother surface. Understanding these concepts and effectively controlling roughness and gloss is key to ensuring high product quality, enhancing both performance and appearance.

RA與SA的差異
Science Classroom

Differences Between RA and SA

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RA (Roughness Average) and SA (Surface Area) are two measurement indicators of surface roughness. RA is the most commonly used two-dimensional roughness parameter, evaluating surface smoothness by calculating the arithmetic mean of the absolute deviations of all points on the surface profile line from the reference line over the measured length. It is typically used for roughness detection on flat surfaces. On the other hand, SA is a three-dimensional surface roughness indicator that takes into account the height variations and other features of the surface profile. It is often used for more complex surface analyses, such as high-precision manufacturing or optical surface treatments. SA provides a more comprehensive view of surface roughness, making it suitable for applications that require detailed three-dimensional data.

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What is surface roughness?

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“Surface roughness” plays a crucial role in engineering and manufacturing. Surface roughness describes the smoothness of a surface, which affects various aspects of workpiece characteristics such as airtightness, mating performance, rigidity, and more. Unlike “surface flatness,” surface roughness measures the degree of surface irregularities, making it especially important for parts that require precise fitting or contact. Understanding the need to pursue “appropriate surface roughness” rather than extreme smoothness is essential to meet different application requirements.

鑽石砂輪與CBN砂輪怎麼選擇？
A complete guide to grinding wheel technology, Knowledge Column, Science Classroom

How to Choose Between Diamond Wheels and CBN Wheels?

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Grinding wheel abrasives can be categorized into general and super types, with diamond and CBN belonging to the super abrasives due to their extremely high hardness, making them suitable for grinding high-hardness materials. Diamond wheels should not be used on iron-containing workpieces, as they can catalyze the transformation of diamond into graphite, affecting performance and wearing down the wheel. When grinding temperatures exceed 600°C, diamonds are prone to melting or forming carbides, making them unsuitable for high-temperature processing. In contrast, CBN wheels are suitable for high-speed and iron-containing material processing, such as tool steel and mold steel, showcasing their unique advantages. With the advancements in technology raising precision requirements in manufacturing processes, selecting the most suitable grinding wheel is crucial. The most expensive option is not necessarily the best; rather, the most appropriate one is the optimal choice.

Cleavage introduction diagram
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Why is “cleavage” important in design?

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Cleavage refers to the property where a crystallized mineral breaks along weaker planes within the crystal structure under external force, forming smooth surfaces. In the gemstone industry, the cleavage characteristic is utilized by striking along the cleavage plane before cutting and polishing. Cleavage is classified into five grades based on the degree of perfection: perfect cleavage, good cleavage, fair cleavage, poor cleavage, and no cleavage. Cleavage is not only a critical factor in gemstone design but also serves as an important indicator in gemstone identification. Cleavage is an inherent property of gemstones, and even perfectly crystallized diamonds have cleavage planes.

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