Examples

Microscopical examination
solder fault analysis
optical inspection
failure analysis
Here you will find an overview of our multiple in-house analytic investigations.

This is only a very small extract of our activities.

Optically Apparent Wetting Faults in the Soldering Process

The optical inspection was carried out with the naked eye and at a stereo microscope with varying light settings
  • Stereo microscopes and video microscopes are technically comparable.
  • Filters (for interference contrast, polarization contrast) enhance inspection results.
  • Wetting faults reflow soldering
  • Disturbed wetting of pads
  • Dark pad surface due to dewetting
  • Wetting defect after wave soldering (solder fillet)
  • Non-wetting on gold layer

Hidden defects of solder joints

Hidden defects only become recognizable in a metallographic preparation or after mechanical load.
  • The pull test delivers a better result than the shear test, because the force is applied as a peel force on the surface of the pads in Z direction.
  • The shear test also yields good force values for heavily affected assemblies because there is a lateral clamping in the case of copper-defined pads and because the solder adheres well in the etching gaps.
Pull-Test
Typical test set-up
  • Pliers
  • Hook
  • Separation along contact surface, standard-complying soldering (left)
  • Separation along pad surface, dark pad places (right)
“Black Pad“ is often and commonly used to describe an unspecific adhesion deficiency of the solder fillet on the NiP-layer. “Black Pad“ is therefore some sort of a general term for phenomena which lead to optically standard-infringing or mechanically instable solder joints on NiAu surfaces.
The discoloration of the NiPsurface which accounts for the name of this phenomenon can but must not forcibly occur. Since there are also other phenomena causing adhesion deficiencies, it es better not to talk of “Black-Pad” right away in order to avoid premature judgement.

Dye and Pry Test of BGAs

  • BGA after applying dye (left)
  • View of PCB side after lifting off BGA (right)
  • Detail: Separation areas (partially) covered with colorant indicating the presence of cracks or non-wetting
  • Attention: Dye must be cured. Otherwise there is the danger of misinterpretation.

Inspection of Microsections

  • Extraordinary gold bath corrosion, formation of uninterrupted intermetallic compound after solder contact, phosphor enrichment at boundary with bulk material (left)
  • partial separation, scar formation (v-shaped etch grooves) and normal compound formation (right).
  • Extraordinary gold bath corrosion of unsoldered PCB
  • Evaluation criteria: depth of etch grooves

X-ray inspection

  • BGA: Overview + details corner pins
  • Inclined x-ray of BGA balls with good wetting (left)
  • BGA ball separated from pad (right)
Rules and regulations pertaining to X-ray inspections
  • IEC 61191-6: Printed board assemblies – Part 6: Evaluation criteria for voids in soldered joints of BGA and LGA Verfahrensbeschreibung, Algorithmen
  • IPC-TM-650 - Test Methods Manual - Method 2.6.10 X-Ray (Radiography), Multilayer Printed Wiring
  • IPC-7095 Design and Assembly Process Implementation for BGAs
  • MIL-STD-1580-B-Test method standard-Destructive physical analysis for electronic,electromagnetic and electromechanical parts