Acceptable standard for tin beads:
1.The diameter of tin beads shall not exceed 0.13mm
2.The number of tin beads with a diameter of 0.05mm to 0.13mm within the range of 600mm2 shall not exceed 5 (single side).
3.The number of tin beads with diameter less than 0.05 is not required
4.All tin beads must be covered by flux and cannot be moved (covered by flux to more than 1/2 of the height of tin beads is considered to be covered)
5.Tin beads do not reduce the electrical clearance of different network conductors to less than 0.13mm
Note: except for special control area
Rejection standard of tin beads:
Any non-conformity of the acceptance standard is judged as rejection.
Remark:
1.Special control area: no tin beads visible under 20x microscope are allowed to exist within 1mm around the capacitor solder pad on the golden finger differential signal line
2.The existence of tin beads itself represents the warning of the process.
3.PCBA appearance inspection standard is one of the most basic standards for acceptance of electronic products. According to different products and customer requirements, the acceptable requirements for tin beads will vary. Generally, the standards are determined on the basis of national standards and based on customer requirements.