This is only a very small extract of our activities.
Optically Apparent Wetting Faults in the Soldering ProcessThe 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.
Hidden defects of solder jointsHidden 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.
- Separation along contact surface, standard-complying soldering (left)
- Separation along pad surface, dark pad places (right)
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
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).
- 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