Introduction to Microelectronics

Day 7

Introduction to Microelectronics

It is the seventh day of this attachment, and my first day following Dr Ong to learn more about microelectronics and failure analysis.For today, Dr Ong gave me a brief introduction to the things I will learn about (transistors, and other electronics stuff), as well as common failure in electronics and what causes them.

Next, he showed me some machines commonly used for failure analysis, such as the SHIMADZU Micro Focus X-ray TV system 2000 (SMX) to see on a larger scale if any defects are present, and the Sesame 1000 (a laser) to cut open the package to reveal the main component inside a chip, so that further analysis can be done.

Fire Drill

At 2pm, the Fire alarm went off!  Fire safety is of utmost importance in NTU, as incidents of fire has really happened in NTU before, so NTU will conduct a fire drill at least once a year to ensure that all students and staff knows what to do and where to gather in events of emergencies.

When we have all gathered at the assembly point, the fire manager gave a few reminders of safety and reinforced the procedures to take in case of a real fire. The entire event lasted around half an hour, where at the end we went back to the lab.

Acid Treatment

Next, Dr Ong showed me how to do an acid treatment of a package.

First, fuming nitric acid would be poured into a beaker, and the package dropped into it. After swirling the content in the beaker for awhile, it is left to stand for the reaction to take place.

When the colour of the nitric acid changes too much (due to reaction with the package), it is poured away and replaced. This process is repeated until only the die (a component inside the package) is left.



The original package



For today, every time the nitric acid was replaced, we would place the package under an optical microscope to see certain features of it before the acid completely dissolves them.

   



Dissolving the package using nitric acid



First (few) treatments



During treatment (notice the fumes - very faint on camera)

A closer look (under the microscope)

Few more treatments later (notice the black areas reduced?)

showing connection between die and metal legs

connecting pad (after gold wire is removed)

After package is mostly dissolved (green deposites are copper being desolved)

One sample which is dissolving copper, the other still at the package

The final product - the die

   SAFETY!
Wait! Before the above procedure could even be started,  some safety precautions have to be in place. First, a lab coat must be worn - To prevent chemical spillage from directly coming into contact with skin or clothes.

Then nitrile gloves (2/3 layers) must be worn - To prevent direct contact of chemicals with hands

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A mask must be worn - To prevent breathing in fumes from chemicals (like the fuming nitric acid).

A safety goggle must be worn (supposedly? ><) - To prevent chemicals from coming into contact with eyes.

That concludes day 7, do leave your comments at the chat box beside!