Workpiece description: The surface of this fingerprint identification chip is covered with black, white, dark gold, and bright gold hardened ink, and the ink is EMC. There are exposed gold fingers on the other side of the IC chip, and green solder resist ink on the same side as the gold fingers. The purpose of this cleaning test is to remove black, white, dark gold, and bright gold hardened inks, but the green solder resist ink on the same side as the gold finger cannot be damaged, and try not to cause discoloration.
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This batch of fingerprint recognition chips can use ACHM01-K hardening ink cleaner to remove the hardening ink covered on the surface, but the EMC under the ink will fall off, and the green solder resist ink on the same side as the gold finger will also be damaged.
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Adjust the formula and develop: hardening ink cleaning agent ACHM01-L. Place the IC chip in 140°C hardening ink cleaning agent ACHM01-L and soak for 10 minutes.
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After soaking for about 10 minutes, it was found that the white ink had peeled off. Slightly shaken in the potion to provide physical flushing power to assist ink release.
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Take it out and rinse with water. After cleaning, it was found that ACHM01-L can peel off the white hardened ink, and has less damage to the green solder resist ink on the gold finger surface, and the color of the green solder resist ink has not changed.
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Repeat the test, stripping the dark gold ink from the wafer. After soaking for 10 minutes, it was found that ACHM01-L could also peel off the dark gold ink on the wafer, but not completely.
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Extend soak time to 15 minutes. Hold the wafer with tweezers and shake it in the medicine. It was found that the ink could be peeled off via shaking.
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According to the above steps, peel off the black and bright gold ink on the wafer in sequence.
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It was found that all four inks could be peeled off with hardened ink cleaner ACHM01-L.
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conclusion and discussion:
9.1 Use the hardening ink cleaning agent ACHM01-L to heat to 140°C and soak for about 15 minutes, although the four inks on the wafer can be peeled off. However, if it is combined with brushing or high-pressure flushing with chemicals, the soaking time may be shortened, so that the green solder resist ink on the gold finger surface will be less damaged.