Nishihara Rikoh's non-discoloring-reflow "N-Sn PLATING"

We have developed the Sn plating (code name N-Sn) which has a lot of advantage by our original producing method, "prevent the absorption of the organic substance", "provide the antioxidant efficiency" of the Sn plating film itself.



  1. Non-discoloring-reflow
  2. Good Solder Wettability Condition
  3. Small Bias Error
  4. No Melt Condensation

Feature 1.Non-Discoloring-Reflow

Reflow discoloring mean is, the oxidation of the film surface when plating film melts by decomposition of the organic substance which absorbed in film. And thicker the oxidized film become, darker the color and more deteriorated the solder wettability as well. N-Sn plating which controls the organic substances in plating film in approx. 10th of usual bright Sn plating does not discolor under severe condition of 270℃x 30sec.x half dozen times and can keep the good reflow appearance (metal brightness). The film oxidation causes the generation of discoloring and if it becomes worse, the reflow deterioration caused from deteriorated wettability incurs the fatal defects at the end.

 Reflow Discoloring TestAES analysis
Red:Sn Blue:O
Thickness of Film
Dull Finish Sn
(without discoloring inhibitor)
Sn ReflowSn Reflow27nm
 Bright SnN-SnDull finish Sn
Amount of absorption of C in film0.050%0.004%0.007%
It is OK even after processing.

As N-Sn plating, unlike ordinary Sn plating's discoloring treatment, controls the discoloring with film itself, they can keep the no-oxidized good surface condition through reflow procedure even if they're affected by "deburred after molded", "replication after plated", "scratch existence on the surface" .


Feature 2.Goodness of Solder Wettability

Goodness of Solder Wettability

It can keep the good solder wettability even after severe heat resistance test, because of the thin oxidized film of plating film surface.


Feature 3.Uniformity of Plating Thickness


It is inevitable to avoid getting thick in center part and thin in edge part as Sn reflow plating undergoes melting process once which causes surface tension when they become fluid. This ununiformity causes bad solderability and bad measure (dimension error) as well.

SAMPLEEdge PartCenter Part
N-SnEdge PartCenter Part
Sn ReflowEdge PartCenter Part

Feature 4.No Melt Concentration

N-SnBright Sn
N-SnBright Sn

Despite the good solder wettability of N-Sn plating, there's no generation of melt concentration compared to bright Sn when reflowed, as it is controlling the content of organic substances as much as possible. In recent years' reduction in size and weight of electronic parts causes such as "parts moving", "not pasted solder" when incur the melt concentration.