Metallography of Microelectronic Components

ICs, silicon wafers, and PCBs are key building blocks in modern electronic devices, and metallography plays an important role in the design, development, and failure analysis of these electronic components.

However, ICs, silicon wafers, and PCBs can be challenging to prepare for metallographic analysis. ICs are tiny, with complex geometries, and often include several different materials, such as metal, glass, or ceramics. This makes controlled material removal time-consuming, requiring patience and skill to grind and polish to a specific target inside a component.

MICROELECTRONIC SAMPLE PREPARATION CHALLENGES

There are three main challenges when performing controlled material removal and target preparation of microelectronic samples.

• The miniature dimensions require specialized equipment and accessories suitable for handling small samples. Steps such as cutting and grinding require greater accuracy than normal due to the dimensions, which are usually in the μm range.
• Complex material compositions are common in microelectronics, where soft metals, ceramics, and composites are often closely packed. This makes the choice of preparation methods and parameters a compromise, carefully selected to meet the specific requirements.
• Controlled material removal and accurate preparation are needed when small targets are the subject of the examination. A metallographic sample inspection often includes looking at a particular area inside a package of interconnected chips. This can be time-consuming, as it typically involves a manually controlled material removal process known as ‘grind-and-look’ (i.e. repeatedly grinding and then checking until the target appears and is ready to be polished).

Read more about the challenges of the metallographic preparation here:

In research or failure analysis, missing the target during a grind-and-look process can mean losing a unique and/or costly sample. Therefore, automated or optimized solutions are increasingly used due to their high mechanical precision, optical measuring units, and mechanical stops.

Common difficulties during the preparation of microelectronic samples include:

• Cutting: Chipping and cracking of silicon wafers, glass, or ceramics
• Mounting: Mechanical deformation and thermal damage
• Grinding: Fracture of brittle constituents such as glass fibers or ceramics
• Polishing: Smearing of soft metal layers; relief due to the difference in hardness of different materials; silicon carbide and diamond particles remaining in solder

There are special tools (AccuStop) that simplify the manual and semi-automatic controlled material removal process. For fully automatic target preparation, the Struers TargetSystem offers fast and precise grinding and polishing.

To avoid relief between hard and soft layers and materials, we recommend grinding with diamond on rigid discs and diamond polishing on hard cloths.

For more information, visit our website about microelectronics at https://www.struers.com/en/Knowledge/Materials/Microelectronics

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