Also, affect the current carrying capacity.They may cause the solder to flow from pad to another during the reflow process.Reduce the thermal conductivity of solder joints.Impose threat to the reliability of a solder joint.Impact of Solder Voids on Solder Joint Performance

PCB surface finish & Process Environment.

Pinhole Microvoids: 1 to 3 microns in diameter and located between the IMC layer and copper land.

Microvia Voids: Microvias associated to the BGA joint are responsible for Microvia voids.

Intermetallic Microvoids: They are sub-micron size voids, formed when the board is exposed to elevated temperatures (>100C) for more than 48 hours.

They can be seen in both BGA and through hole solder joints.

Shrinkage Voids: Elongated and rough voids starting from the surface of the solder joints.

Planar Microvoids: They are responsible for BGA failure (1 to 2 mils in dia.).

They are 4 to 12 mils in diameter and most likely to appear in SMT processes.

Macro Voids: Created due to the evolution of trapped gases of fluxes and solder paste.

Typically, a solder void contains air, but it may also consist of flux residue or cured resin when resin-containing solder paste is used during soldering.Īccording to IPC (IPC-A-610), solder voids are considered to be a defect when the overall calculated area of all voids in any given solder ball/joint is greater than 25% of the total solder ball area. When less than require solder is applied to a joint, it can result in empty spaces or holes inside the solder joint – these are known as Solder Voids.Ī Solder void is generated due to the insufficient availability of solder while creating the joint. If this is not done, bad solder joints will be created - cold joints and brittle joints. Applying appropriate amounts of solder paste to a pad is of paramount importance to ensure good quality solder joints.

Pcb reflow