8.) Symptom: INCONSISTENT DOT SIZE
Cause a): Cartridge was not primed correctly and needs to be re-primed (filament inkers only).
Solution a): Re-prime cartridge per instructions on cartridge packaging and run a thousand dots on a test wafer. Cause b): Cartridge needle tip is damaged.
Solution b): Replace the damaged cartridge with a new one. Cause c): The cartridge needle is partially clogged with a debris particle (pneumatic inkers only).
Solution c): Replace the defective cartridge with a new one. Return the suspect cartridge to Xandex for testing and possible warranty replacement. Cause d): Air bubble (pneumatic inkers only). Small air bubbles are sometimes present during the first 1,000 dots after initial priming of the cartridge.
Solution d): Run 1,000 dots onto a test wafer. This should eliminate any bubbles that may have been present inside of the cartridge. Cause e): Ink has accumulated on the outside, metal portion of the needle (ink “balling”). This may occur due to excessive priming or if the inker is fired multiple times without depositing any ink (e.g. if the Z-height is too high during the initial adjustment). If using a pneumatic system, it may also occur due to a cartridge defect that causes leakage between the Teflon and metal portions of the needle.
Solution e): Carefully remove all the excess ink from the needle using a lint-free tissue or swab before continuing with inking operation. If ink continues to accumulate on the outside of the needle multiple times, the cartridge may be defective and should be returned to Xandex for testing and possible warranty replacement. Cause f): Prober Z stage equipment problem. The stage Z drive assembly photocells may be defective or contaminated with dust (if prober is so equipped). Z stage malfunction can cause the amount of stage travel in the z direction to be non-uniform, resulting in skipped dots.
Solution f): Refer to prober manufacturers recommended verification procedure to insure correct operation of the prober Z stage drive and clean, adjust or replace components as necessary. Cause g): Inker equipment problem (pneumatic inkers only). Pneumatic inker shuttle is clogged with dried ink or other debris, or has been used outside the recommended shuttle preventive maintenance period causing inconsistent shuttle motion.
Solution g): Perform recommended preventive maintenance on the shuttle using the appropriate shuttle maintenance kit (available from Xandex). Replacement of the shuttle may be required if shuttle has been damaged due to a lack of regular preventive maintenance. Cause h): Inker equipment problem (pneumatic inkers only). Pneumatic controller has not received regular preventive maintenance, resulting in inconsistent shuttle and/or cartridge actuator valve performance.
Solution h): Perform recommended preventive maintenance on the controller using the appropriate controller maintenance kit (available from Xandex). Cause i): Ink is being placed onto a surface that varies in surface energy. This can be due to variations in surface chemistry or topography.
Solution i): Take steps to make the surface more uniform. Gas plasma cleaning/surface activation and/or solvent cleaning may be helpful in some cases. Cause j): Cartridge filament length, filament diameter, or needle diameter is out of specification (filament systems only).
Solution j): Replace with a fresh cartridge. Return the suspect cartridge to Xandex for test confirmation and possible warranty replacement. Cause k): 6993 ink used in hot chuck applications only. Condensation of ink solvent vapors on the needle tip can lead to solvent build-up and periodic deposition on the wafer under certain conditions. This will only occur in low yield off-line applications where large numbers of ink dots are placed rapidly with a very close spacing.
Solution k): Xandex does not recommend the use of 69xx series inks with a hot chuck. 1) Reduce the inking speed and/or change the chuck temperature. 2) Wipe off the needle tip with a lint free cloth if any significant of accumulation of ink solvent is observed.
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