Abstract

A new method of preparation will be shown which allows traditional fixturing such as test heads and probe stations to be utilized in a normal test mode. No inverted boards cabled to a tester are needed since the die remains in its original package and is polished and rebonded to a new package carrier with the polished side facing upward. A simple pin reassignment is all that is needed to correct the reverse wire sequence after wire to wire bonding or wire to frame bonding in the new package frame. The resulting orientation eliminates many of the problems of backside microscopy since the resulting package orientation is now frontside. The low profile as a result of this technique allows short working distance objectives such as immersion lenses to be used across the die surface. Test equipment can be used in conjunction with analytical tools such as the emission microscope or focused ion beam due to the upright orientation of the polished backside silicon. The relationship between silicon thickness and transmission for various wavelengths of light will be shown. This preparation technique is applicable to advanced packaging methods and has the potential to become part of future assembly processes.

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