Home > News
What are the main aspects of SMT patch soldering PCBA appearance inspection standards?
1. tin beads: solder balls violate the minimum electrical clearance. The solder balls are not fixed in the residue that is not removed or covered under conformal coating.The diameter of the solder ball is ≤0.13mm, which can be accepted. Otherwise, it is rejected.
2. false welding: The overlap between the solderable end of the component and the PAD (J) is clearly visible. (Acceptable)Insufficient overlap between the end of the component and the PAD (rejected)
3. side stand:width (W) to height (H) ratio does not exceed two to one (allowable) width (W) to height (H) ratio exceeds two to one (see left). • The solderable end of the component is not completely wetted with the PAD surface.The component is larger than the 1206 class. (rejected)
4. tombstone:the end of the chip component tilted (tombstone) (rejected)
5. flat, L-shaped and wing-shaped pin offset:Maximum side offset (A) is not greater than 50% of the lead width (W) or 0.5mm (0.02 inches) (acceptable) Maximum side offset ( A) 50% or 0.5mm (0.02 inch) greater than the lead width (W) (rejected)
6. cylindrical end cap weldable side offset:side offset (A) ≤ component diameter width (W) or PAD width (P) 25% (acceptable)side offset (A) is larger than the component diameter 25% of width (W) or PAD width (P) (rejected)
7. chip component - rectangular or square solderable end element side offset: side offset (A) ≤ 50% of the component solderable end width (W) or 50% of the PAD width (P). (Acceptable) Side offset (A) is greater than 50% of the solderable end width (W) of the component or 50% of the PAD width (P) (rejected)
8. J-shaped side offset:Side offset (A) is less than or equal to 50% of the lead width (W). (Acceptance)Side offset (A) exceeds 50% of the lead width (W) (rejected)
Lianxi:The component leads and the PAD are soldered neatly, without the phenomenon of offset short circuit. (Acceptable) Solder wire should not be connected. (rejected) Solder bridges between adjacent wires or components (rejected)
PCBA visual inspection standard
9. reverse: The polarity point on the component (white silk screen) is consistent with the PCB diode screen printing direction (acceptable)The polarity point (white silk screen) on the component is inconsistent with the silk screen of the diode on the PCB. (rejected)
10. too much tin:The maximum height of the solder joint (E) can exceed the PAD or extend to the top of the end cap metal coating of the solderable end, but can not extend to the component body (acceptance) The solder has extended to the top of the component body. (rejected)
11. reverse white: There are exposed chip components of electrical materials to place the material face away from the printed surface Chip parts only allow one component of ≤0402 to reverse white per Pcs board. (Acceptable)If the exposed electrical material is exposed, the chip component will place the material surface toward the printing surface (rejected).Chip parts do not allow two or more components of ≤0402 to be reversed per Pcs board.
12. empty welding:The solder joint between the component pin and the PAD is well wet and full, and the component leads are not lifted (acceptable). The component pins are not arranged neatly (coplanar), which hinders the formation of acceptable solder. (rejected)
13. cold welding:Reflow process solder paste is fully extended, the solder on the solder joints is completely wet and the surface is shiny. (Acceptable)The solder paste on the solder ball is not completely reflowed.The appearance of tin is dark and irregular, and the solder paste has tin powder that is not completely melted. (rejected)
14. a small number: BOM list requires a patch bit to be placed components but not mounted components (rejected) Multiple pieces:BOM list requires a patch bit number does not require mounting components but has been placed Components; Excess parts appear where they should not be. (rejected)
15. loss parts: Any edge peeling is less than 25% of the component width (W) or component thickness (T) The top metal plating is missing at the top 50% (each end) (acceptable) Any crack or gap that is exposed ; cracks, nicks or any damage on the body of the glass element. Any gap in the resistance material. Any cracks or indentations. (rejected)
16. foaming, layering:The area of foaming and delamination does not exceed 25% of the distance between the plated through holes or the internal wires. (Acceptable) The area of foaming and delamination exceeds 25% of the distance between the plated through holes or the internal wires. • Foamed and layered areas reduce the spacing of conductive patterns to violate minimum electrical clearance. (rejected)
Cause Analysis and Improvement Measures of Defects in Bad Solder Joints.
Recent years, AOI automatic optical detectors have become the fastest growing device in surface mount equipment. AOI inspection equipment is best suited for measuring simple, structured and repetitive scenarios. The device's sensors are best at a variety of tasks such as synchronous repeatability and multipoint detection, as well as uninterrupted data analysis and continuous visual feedback. As China's labor costs increase year by year, a SMT production line equipped with 3-10 people using visual inspection products will inevitably increase the operating cost of the production line. In the future, electronic manufacturing enterprises will accelerate due to the demand for product quality and cost control. The AOI detection device replaces the manual process.
Phone: /Wechat/WhatsApp:+86 136 8490 4990
Add: Shenzhen, China 518103