Flip Chip Die Bumping

Precision Gold Stud Bumping & Flip Chip Interconnect Solutions

Flip chip technology enables high-density, low-inductance interconnections by eliminating the need for traditional wire bonds. At Reltronix, our UK facility provides specialised Gold (Au) stud bumping and flip-chip assembly services engineered for high-frequency, RF, and miniaturised high-reliability (Hi-Rel) semiconductor applications.

By placing precision gold bumps directly onto individual die pads, we enable direct face-down mounting onto substrates or packages. This process delivers superior electrical performance, reduced parasitic inductance, and optimised thermal management for demanding microelectronic designs.

Core Flip Chip Capabilities

• Precision Gold (Au) Stud Bumping
  High-speed placement of uniform gold bumps directly on wafer-level or individual single-die bond pads using modified wire bonding equipment.
• Prototyping & Single-Die Bumping
  Ideal for low-to-medium volumes, custom ASICs, and R&D projects where full wafer-level redistribution layers (RDL) or electroplating are not cost-effective.
• Flip Chip Attach & Reflow/Thermosonic Bonding
  High-precision placement and bonding of bumped die onto ceramic packages, custom substrates, or printed circuit boards.
• Underfill & Encapsulation
  Precise dispense of capillary underfill materials to redistribute thermal stress, protect bump joints, and ensure long-term mechanical reliability under temperature cycling.

Key Advantages of Reltronix Flip Chip Services

• • Enhanced High-Frequency Performance
    Minimises signal path length and parasitic inductance, making it ideal for RF, microwave, and millimeter-wave devices.
  • Compact Footprint
    Enables ultra-compact packaging designs by utilising the entire die surface area for interconnections rather than just the perimeter.
  • No Wafer-Level RDL Required
    Gold stud bumping allows individual bare die to be bumped and flip-chip mounted without expensive wafer-level plating processes.
  • In-House Qualification with Stud Pull Tests
    Evaluation of stud bump adhesion is carried out with stud pull tests using our XYZtec micro-tester equipment. During a stud pull test a glue is used that is signifiantly stronger than the bond to be tested. All tests can be carried out in accordance with:
    MIL-STD-883 method 2011.9 bond strength (destructive bond pull test)
    MIL-STD-883 method 2031-1 flip-chip pull-off test
    JEDEC JESD22-B109
    Read more about our pull testing and equipment used.