TL;DR
Board alignment failures are typically a dirty fiducial, a worn conveyor stopper, or an incorrect fiducial reference in the job file. Clean the fiducials and verify the job file first.
What you might see
- alignment fail alarm at board entry
- fiducial search returning no match
- inspection results shifted consistently in one direction
- intermittent alignment errors on some board lots
Likely causes
Fiducial mark obscured by solder paste, flux, or PCB substrate discoloration
Incorrect fiducial location or size programmed in the job file
Worn or misadjusted conveyor stopper causing board to stop in the wrong position
Board warpage exceeding the alignment correction range
Required tools
- IPA wipes
- Job file editor
- PCB Gerber data or assembly drawing
- Ruler or calipers for stopper position check
Safety first
- Keep hands away from the conveyor while the machine is in automatic mode. Inhibit conveyor motion before adjusting the stopper position.
Procedure
- 1
Review the alignment camera image on the controller screen. Confirm whether the fiducial marks are visible or obscured.
- 2
Inspect the PCB fiducial marks for solder paste, flux, or oxidation. Clean with an IPA wipe if contamination is present.
- 3
Open the job file and verify that the fiducial coordinates and size match the PCB Gerber data.[1]
- 4
Measure the actual fiducial locations on the PCB with the inspection camera using the manual locate tool. Update the job file if the coordinates are off.[1]
- 5
Check the conveyor stopper position. Verify the board stops squarely and the leading edge is at the programmed board-stop position.
- 6
If the board is warped, check whether the warp is within the machine acceptance tolerance. Use a PCB support jig if the board is marginally warped.
- 7
Run 5 boards after any correction and confirm alignment passes consistently.
Sources
Koh Young Koh Young Zenith Alpha / Aurora AOI / X-Ray Inspection general technical documentation, Koh Young
Koh Young AOI system general fiducial alignment and job setup procedures (general)
More guides for Koh Young Koh Young Zenith Alpha / Aurora
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Rising false calls are usually a library threshold that needs re-tuning, an illumination change, or a conveyor vibration issue. Audit the top false-call component families first.
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