This batch of IC chips can use ACHM01 hardening ink cleaning agent to remove the black, silver, white, and gold hardening inks on the surface, but the green solder resist ink on the same side as the gold finger will turn yellow and discolored.

Adjust the formula and develop: hardening ink cleaning agent ACHM01-k. Place the IC chip in 130°C, hardened ink cleaning agent ACHM01-k, soak for 1 minute. Shake the agent continuously during the soaking process to provide physical flushing force and assist the ink to fall off.

Take it out and rinse with water. After cleaning, it was found that ACHM01-k can quickly dissolve the black hardening ink, and it will not harm the green solder resist ink, and the color of the green solder resist ink has not changed. (The wafer on the left of the photo is not stripped of ink)

Repeat the test of black hardening ink 2 times, the results are consistent. The wafer on the left of the photo below is before ink stripping, and the wafer on the right is after ink stripping.

Repeat the test. Place the white hardened ink IC wafer at 130°C in the hardened ink cleaning agent ACHM01-k and soak for 2 minutes. Shake the agent continuously during the soaking process to provide physical flushing force and assist the ink to fall off. It was found that it can also be effectively removed. The wafer on the left of the photo below is before ink stripping, and the wafer on the right is after ink stripping.

Repeat the test. Place the silver hardened ink IC wafer at 130°C in the hardened ink cleaning agent ACHM01-k and soak for 1 minute. Shake the agent continuously during the soaking process to provide physical flushing force and assist the ink to fall off. The wafer on the left of the photo below is before ink stripping, and the wafer on the right is after ink stripping. It is found that although the ink can fall off, it is not complete, and the surface still looks white.

Repeat soaking in the medicine for 1 minute, take it out and do not rinse it with clean water, and wipe it with a test lens paper, and it is found that it can be removed relatively cleanly.

Put it on a white paper to take pictures, you can take a clearer picture. In the two photos below, the silver ink chip on the left is before the ink is stripped, and the chip on the right is after the ink is stripped.

Repeat the test. Put the golden hardened ink IC wafer at 130°C in the hardened ink cleaning agent ACHM01-k, and soak for 1 minute. Shake the agent continuously during the soaking process to provide physical flushing force and assist the ink to fall off.
It was found that after washing for 1 minute, the golden hardened ink could not be removed.

Put the gold hardened ink IC wafer at 130°C in the hardened ink cleaning agent ACHM01-k, soak for 3 minutes.
It was found that after washing for 3 minutes, although the golden hardened ink was slightly lightened, it still could not be completely removed.

Put the golden hardened ink IC wafer at 130°C in the hardened ink cleaning agent ACHM01-k, and soak for 8 minutes.
It was found that after 8 minutes of washing, the gold hardened ink was completely removed. The color of the green solder resist ink turns slightly yellow.

Shot on a black background:

discuss：

11.1 If the hardened ink cleaning agent ACHM01-k is used together, the yellowed ink will be restored to some green by using a peroxidation reducing agent. Perhaps gold ink would close the case.
11.2 If you want to process a large number of wafers and peel off hardened inks of various colors, it is recommended to use mechanical equipment such as ultrasonic waves, roller brushes, and high-pressure washing to assist in removing inks. It can shorten the soaking time and reduce the color yellowing of the green solder resist ink.