Increasing Demand for Reliability

PCBs in an electric product for automotive or industrial equipment are exposed to harsh working environments with significant temperature differences and in some cases, SAC305 solder alloy cannot provide sufficient reliability.
Temperature cycling causes stress in the solder joint due to the components and PCB expansion and contraction, and the stress causes cracking in the solder joint.

Therefore, a solder alloy which withstands thermal-cycle stress is required.

Alloy Strengthening by In and Bi addition (Solid Solution Strengthening)

Dislocations (irregularities in the crystal structure) occur in metals including Tin (Sn), the bulk material of the solder. Dislocations eventually cause plastic deformation and cracking in the solder joint. Bi and In do not form compounds with Sn but replace the Sn atoms in their lattice positions (form a solid solution). As the atomic radius of Bi and In are significantly larger than Sn, they form distortions within the matrix which prevent propagation and accumulation of dislocations. In addition, this alloy has a lower melting point than SAC305 and reduces the thermal stress to the components during reflow.

Prevents cracking from thermal-cycle stress

Solid solution strengthening offers high thermal-fatigue resistance as it does not fail even in a harsh temperature condition, such as -40˚C ~+150˚C.

Thermal-fatigue resistance contributes to an extension of product life of automotive electronics, failure of which may result in safety issues and for industrial equipment the product is expected to be longer-lasting.

Compatible with ENIG Finish Soldering Pads

Sn-Ni based IMC layer grows in the ENIG finish pad (Au plating layer of the soldering pad) and forms a Phosphorus (P)-dense layer which makes the solder joint interface brittle.

SB6NX solder alloy contains Cu, which is highly compatible with Ni, and forms a barrier layer to prevent Ni diffusion. As a result, the combination of SB6NX solder and the ENIG finish pad can obtain equivalent joint reliability as the OSP finish pad..

Superior Solder Wire Properties and Solderability

The flux in SB6NX-72M prevents insufficient solder fill and increased solder bridging at a faster process speed due to good flux performance.

It can also prevent cracked flux residue.