Waferbumping & Balling

Solder balling of wafers and substrates can be done by two different technologies: Preformed discrete solder balls are usually applied to WL-CSP devices. The available infrastructure is able to handle wafers up to 300mm in diameter. If required, a solderable under bump metallization can be applied by electroless NiAu deposition. Solderballs with a diameter as small as 200µm can be placed in a pitch of 400µm with very high yield. The process has been proven to be reliable for TAIKOTM wafers with a remaining thickness of 30µm.

Smaller Pitches can be realized by solder paste printing which is reliable on an industrial scale down to a pitch of 250µm.


Placement of discrete solder balls or printed solder paste on thinned wafers with up to 300mm diameter.

Process Steps - Balling:

  • Step 1: Flux printing
  • Step 2: Placement of discrete solder balls
  • Step 3: Soldering
  • Step 4: Cleaning

Process Steps – Bumping:

  • Step 1: Solder paste printing
  • Step 2: Reflow
  • Step 3: Cleaning


  • Wafer-level chip-size packaging (WL-CSP)
  • Flip-chip