Types of defects in reflow soldering points

Due to various reasons, there are various defects in SMT reflow soldering products. For beginners, they may not fully understand what these defects are. JEENOCE shares with you the definition and classification of SMT reflow soldering point defects.

1、 Virtual soldering: The minimum height of the solder joint at the end of SMT components is 75% of the width of the solderable end of the component or 75% of the width of the solder pad. The minimum height of the solder joint is 25% of the solder height plus the height of the solderable end. The solder joint on the welding surface should be soaked at least 270 degrees. Insufficient solder filling for pins or pads that need to be soldered.

2、 Bonding: Solder forms a bridge between adjacent different wires or components. Abnormal connection of solder between conductors.

3、 Cold soldering: The solder paste on SMT components does not reflow completely and does not completely melt.

4、 Excessive flux: There is residue on the circuit board that needs to be cleaned after reflow soldering.

5、 Multi adhesive: The solder pad and solder area of the circuit board have adhesive that reduces the welding width by 50% or does not form solder joints.

6、 Overwelding: The height of the solder joint can exceed the height of the solder pad and climb to the top of the metal layer, but it cannot touch the component body.

7、 Insufficient glue: There is too little red glue on the circuit board, which causes the components to fall off.

8、 Spilled solder: Spilled solder violates the minimum electrical gap.

9、 Tin balls: Tin balls with a diameter greater than 0.13mm adhered to the circuit board or solder balls adhered 0.13mm away from the wire. Solder balls violate the minimum electrical clearance. More than 5 solder balls within 600 square millimeters.

10、 Solder pad detachment: There is separation between the circuit board wire, solder pad, and substrate.

11、 Non wetting: Spherical or bead like material formed on the surface of SMT components and circuit board solder joints.

12、 Open soldering: The solder pad is not filled with solder, resulting in the component not being soldered to the solder pad.

13、 Direction deviation/misalignment: The side deviation is greater than the smaller of 50% of the weldable width of the component or 50% of the pad width. The end offset exceeds the pad. The side offset is greater than the smaller of 50% of the pin width or 0.5mm.

14、 Missing/missing parts: There are no components on the solder pads that should have components.

15、 Tombstone: The end of a chip component on a circuit board is raised.

16、 Side standing: The side of the chip component is raised.

17、 Flip: Flip the installation of chip components.

18、 Reverse: The polarity of SMT components with polarity is reversed.

19、 Bend: One or more pins of a component are deformed or twisted.

20、 Damage: There are indentations, nicks, and cracks on the surface of SMT components after reflow soldering.

21、 Peeling: The coating of SMT components after reflow soldering causes ceramic exposure.

22、 Peeling: Blistering on the PCB or Flex surface after reflow soldering.

23、 Multiple components: There are excess components on the PCB board.

24、 Corrosion: Rust spots or erosion on metal surfaces or mounting components.

25、 Tear: Cracks or tears appear on the rubbery printed board.

26、 Uneven: Welding defects caused by uneven component pins or plug probes.

27、 Stains: There are traces of solder, alloy, etc. on the gold-plated sheet.

28、 Wrong component: SMT component installation or installation error.