Knowledge Column

In order to let more people know about polishing and grinding, Honway update the knowledge column from time to time.

優化晶圓研磨拋光過程中的應力控制

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

Science Classroom / By

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

Grinding – Abrasives Introduction

Science Classroom / By

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

Comparison Chart of Grinding Polishing and Surface Roughness

Product Applications, Science Classroom / By

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

Differences Between RA and SA

Science Classroom / By

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.

What is surface roughness?

Science Classroom / By

“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？

How to Choose Between Diamond Wheels and CBN Wheels?

Science Classroom / By

Grinding wheel abrasives can be divided into general and super types. Diamond and CBN (Cubic Boron Nitride) are considered super abrasives due to their extremely high hardness, making them suitable for grinding high-hardness materials. Diamond wheels are not recommended for use on iron-containing workpieces, as they can catalyze the conversion of diamond into graphite, which affects performance and leads to wheel wear. 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 ideal for high-speed processing and iron-containing materials such as tool steel and mold steel, where they demonstrate unique advantages. As technological advancements lead to higher precision requirements in manufacturing processes, selecting the most suitable grinding wheel becomes crucial. The most expensive option is not necessarily the best; rather, the most appropriate one is the optimal choice.

石榴石

Garnet—A Gemstone and High-Tech Material?

Gemstones / By

Garnet is a versatile and colorful gemstone. Its name comes from the Latin word for pomegranate, due to its color and shape resembling pomegranate seeds. Garnet is a group of silicate minerals that have been used as gemstones and abrasives since the Bronze Age. There are many types of garnet, including pyrope, spessartine, and almandine each with unique chemical compositions and color characteristics. In addition to its use as a precious gemstone, garnet has extensive industrial applications, such as in water jet cutting, mechanical polishing, and optical equipment. In summary, garnet’s diverse uses and unique physical properties make it valuable in various fields with promising application potential.

青金石

Lapis Lazuli – A gemstone of higher status than gold

Gemstones / By

Lapis Lazuli is a rock contains a variety of minerals, mainly composed of lapis lazuli, sodalite, etc., the white part is calcite, and the golden part is pyrite. The range of its colors includes teal, blue, indigo and blue-violet, the ones with more sky blue stone display brightly azure color. Lapis Lazuli has a long-standing history as a symbol of imperial power and wealth, and its status was valued in ancient Egypt, Babylon and other cultures. Ancient China called it “Emperor blue”, and the West called it “Ultramarine”, which is the emblem of nobility and majesty. Lapis Lazuli is often used in jewelry, pigments and medicines, and has high commercial value, the less white and golden part the better when buying.

天河石

A gemstone with mysterious river-colored — Amazonite

Gemstones / By

Amazonite is a blue-green or green-blue variety of microcline feldspar, first discovered in the Amazon River basin. Its name comes from the Japanese “Tengaishi,” which means “river in the sky.” The distinct characteristic of Amazonite is its grid-like structure of blue-green and white squares caused by its twinning structure. High-quality Amazonite can be used as gemstones, while lower-quality stones are used for carving. Common imitations include copper-containing blue-green quartzite from China, known as “Guizhou Jade,” which differs from Amazonite in its higher hardness, lack of cleavage, and absence of the grid structure. When selecting Amazonite, look for pure color, transparency with few inclusions, and evenly distributed or inconspicuous grids. It is essential to avoid impact to prevent cracking. Some sellers use acid treatments to remove impurities, which may increase transparency but damage the structure. Methods to identify Amazonite include weight comparison and observing the stone’s pattern.

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