TESTING & MEASUREMENT
content (% P ) or deposit density in the thickness calculation . This can introduce significant errors for deposits of > 20 microns if the % P varies from nominal .
Phosphorous content (% P )
% P is a function of the plating solution chemistry by design , and is influenced by day to day and longer-term chemistry , temperature , and pH changes .
Accurate thickness measurements can only be made if % P is also measured !
A FISCHERSCOPE ® X-RAY XDV ® -SDD XRF system can be used to accurately measure deposit thickness and % P , providing full verification of the deposit to specifications , such as IPC 4552 and 4556 for ENIG and ENEPIG in the PCB industry .
Hardness
Hardness and wear resistance can be specified and achieved by using the appropriate plating solution chemistry and plating parameters .
Conventional Vickers micro-hardness is determined in a destructive cross section of an ENP deposit of > 60 microns , but cross section preparation is a costly time-consuming process .
A FISCHERSCOPE ® HM2000 instrumented indentation hardness ( IIH ) system takes less than 60 seconds to test the hardness of ENP coatings perpendicular to the surface , even if the coating is only 2 microns thick , thanks to the low load range of 0 to 2000mN . Penetration of the coating is limited to 10 % of its thickness , which makes it a non-destructive test .
Simultaneous measurement of both thickness and % P removes the possibility of significant thickness errors that can occur when using a conventional fixed % P or density . This is particularly important for high phosphorous ENP where the deposit corrosion resistance is directly influenced by % P content .
It ’ s recommended that both thickness and % P of ENP deposits should be measured at incoming goods inspection ( IGI ), as this approach provides verification of the two key parameters that determine ENP performance .
Typical measurement performance of the FISCHERSCOPE ® X-RAY XDV ® -SDD is shown below :
NiP / Fe thickness and % P composition measurement
To learn more about coating thickness measurement , material analysis , nanoindentation solutions and material testing please contact your local FISCHER representative :
FISCHER INSTRUMENTATION ( GB ) LTD Telephone : 01386 577370 Visit : https :// fischerinstrumentation . co . uk /
58 OCTOBER 2021 twitter : @ surfaceworldmag