Examples of Defects of Connectors/Printed Circuit

Au plating pore corrosion [Failure of connector]

Case of Au plating pit (SEM image) Case of Au plating pit
(SEM image)

Corrosion occurred on the Au plating surface of the connector terminal.

Au plating is generally thin and pin holes may be generated under some plating conditions.

This is a case where due to such a pin hole, a local battery is formed with Au as a cathode and Ni as an anode and the Galvanic corrosion occurred. Ni substrate has corroded and the corrosion product has covered the Au plating surface.

(a) Surface observation (a) Surface observation
(b) Cross section (observed with inclination of 45 degree) (b) Cross section (observed with inclination of 45 degree)
SIM image of Au plating pore corrosion

Through-hole and wiring failure [Failure of printed circuit board]

There are failure cases for the printed circuit board, such as:

  1. Cu wiring corrosion by etching residue,
  2. Peeling of Cu/epoxy substrate due to etching failure,
  3. Peeling due to insufficient removal of smear (cutting chips),
  4. Measling (peeling of glass cloth),
  5. Solder resist failure (poor curing, etc.), and
  6. Plating (Sn, Au/Ni) failure.

In some cases, this failure may trigger an open failure, short failure, mounting failure, etc.

Peeling or measling of the inner layer Cu foil may be detected from change in color to white or bulging after mounting.

Cross section of the printed circuit board
Cross section of the printed circuit board

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