CONTACT PLATING QUALITY CONTROL
Because it is a major determinant of the long-term reliability and performance
of the connection, contact plating, including MISER gold processing, requires a high level of plating technology, stringent
process control, and the detailed quality inspection procedures. SUN meets these requirements with a plating facility that
is specifically designed to process and inspect the wide variety of metals utilized in Backplane interconnection systems.
Each lot of plated contacts must pass a rigid quality inspection examination that
uses both x-ray fluorescence and beta ray back-scatter techniques to determine plating thickness. In addition, the inspection
procedure requires conformance to criteria which evaluate porosity, solderability, adhesion, plating defects, and surface
preparation. Scanning electron microscope inspection is available for special analyses. A record of inspection results is
provided by maintaining the lot sample, specimens, and data for a minimum of two years.
Porosity in Electro-gold plating is characterized by interstitial voids or discontinuities
whose magnitude depends upon such variables as surface roughness bath contamination and the deposition process and process
control. There are several porosity tests used to evaluate contact surface plating. Perhaps the best known and most generally
used is that specified by Western Electric. In this test, the sample contacts are placed in a desiccator and subjected to
fumes from concentrated nitric acid for one hour. The contacts are then baked in an oven at 105 degrees C for one-half hour.
Contacts are rejected if they show any evidence of blue-green corrosion (copper nitrite) or surface blisters when examined
under 20X magnification.