Standard of the tin bead on PCBA board

The acceptable standard for the size of the tin bead on PCBA board surface.

1.The diameter of the tin ball doesn’t exceed 0.13mm.

2.The number of tin beads with a diameter of 0.05mm-0.13mm within the range of 600mm doesn’t more than 5 (single side).

3. The number of tin beads with a diameter of less than 0.05mm is not required.

4. All tin beads must be wrapped by the flux and cannot be moved (the flux encapsulated to more than 1/2 of the height of the tin beads is the wrapped).

5. The tin beads didn’t reduce the electrical clearance of different network conductors to below 0.13mm.

Note: Except for special control areas.

The rejection criteria for tin beads:

Any non-compliance of the acceptance criteria is judged to be rejected.

Remarks:

1. Special control area: tin beads visible under a 20x microscope are not allowed within 1mm around the capacitor pad on the golden finger end of differential signal line.
2. Tin beads represents a warning for the manufacturing process. So the SMT chip manufacturers should continuously improve the process to minimize the occurrence of tin bead.
3. The PCBA appearance inspection standard is one of the most basic standards for the acceptance of electronic products. According to different products and customer requirements, the acceptable requirements for tin beads will also different. Generally, the standard is determined based on the national standard and combined with the requirements of customers.

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