2.5D & 3D Packaging

2.5D & 3D Packaging

Indium Corporation is a world leader in the design, formulation, manufacture and supply of semiconductor-grade fluxes and associated materials, enabling 2.5 and 3D assembly processes, as well as more standard flip-chip assembly.
We continue to work with leading customers and equipment partners to develop and optimize materials and associated assembly processes in this rapidly expanding area of technology.

Our offerings include:

  • Bump fusion (wafer) fluxes for copper pillar / microbump formation
  • 2.5D/3D fluxes for thermocompression bonding (TCB) assembly:
    • Memory-stacking (memory cube)
    • Memory on logic (3D)
    • Logic and memory on interposer (2.5D)
  • Standard flip-chip fluxes
2.5D & 3D Packaging


We have process-proven materials that enable applications from high-end servers to popular mobile devices. These products are used globally in applications in both 2.5D (chip-on-interposer or chip-on-coreless substrate) and 3D (chip-on-chip TSV-bonding) assembly, and are manufactured under precisely-controlled conditions to ensure semiconductor-grade quality.

Typical Product Attributes:

  • Halogen-free (no intentionally added halogens)
  • Water-soluble or ultra-low/near zero residue no-clean

Wafer Fluxes

Wafer fluxes are low-viscosity rheologically-optimized, semiconductor-grade liquid fluxes that are applied to the surface of the wafer and reflowed after:

  • Solder deposition (usually plating)
  • Solder bump deformation or coining, after known good die (KGD) probe testing

Recommended products:

Wafer flux WS-3543

  • Application: spin-on and reflow
  • Attributes: shiny, co-planar symmetrical solder microbumps

Flip-Chip Fluxes

Flip-chip fluxes are moderate viscosity liquid fluxes or rheologically plastic materials used to solder a bumped or copper-column flip-chip to a substrate in the direct chip-attach process. The substrate pads may be metallized/OSP-bearing, pre-bumped with solder or printed with substrate paste.

Recommended products:

Flip-Chip Flux WS-641

  • Application: dip, place die, or TCB (reflow)
  • Attributes: reliable solder interconnects

Flip-Chip Flux WS-3555

  • Application: spray, place die, or TCB (reflow)
  • Attributes: shiny, co-planar symmetrical solder microbumps

Copper-Pillar Flip-Chip Fluxes

Copper-pillar flip-chip fluxes are designed for use in thermocompression bonding applications. Their rheology and chemical design enable their use with dipping depths down to 10 microns or less, and film thicknesses (spray fluxes) down to 5 microns or less.

Recommended products:

Cu-Pillar Flip-Chip Flux WS-641

  • Application: thermocompression bonding flip-chip copper pillar applications
  • Attributes: enables dipping depths down to 10 mincons or less

2.5D & 3D Packaging Products