QBoard – advanced sample holder system

The QBoard – Sample holder for low-temperature electronic devices with proven design

QBoard is a modular, PCB-based cryogenic sample holder system for low-temperature electronic devices, such as spin-qubit chips and superconducting circuits. It has 48 DC/low-frequency channels and 16 high-frequency channels (GHz) and offers excel­lent thermalization down to millikelvin.

QBoard is based on a multi-board design for multiqubit devices1) which is used for example at the University of Sydney and the University of Copenhagen (Center for Quantum Devices). It consists of a motherboard, a daughterboard, an interposer, a mounting bracket, plus all necessary cables for connecting the QBoard to the cold finger of a typical dilution refrigerator (or to the inside of cryostat’s measurement insert).

The sample is mounted and wire bonded to a daughterboard. It serves as a chip carrier, offering a high degree of flexibility. It has a 0.5 mm deep gold plated cavity into which the sample chip can be glued.

With this optimized, tested, and well-documented system you do not need to spend valuable research hours on designing and manufacturing chip carriers and connectors for contacting your quantum chip.

The main features of the QBoard sample holder

  • Motherboard with two 51-pin nano-D connectors wired in parallel, facilitating sample check-in bot­tom-loader cryostats or grounding during connection.
  • Made of non-magnetic materials.
  • Daughterboards for sample mounting via wire bond­ing. Daughterboards are inexpensive – no more need to unbound good samples!
  • Daughterboards are prepared for mounting of resona­tor circuits for reflectometry.
  • 48 RC-filtered low-frequency lines.
  • 16 RF lines with two 8-pin mini-coax connectors.
  • 16 bias tees on the motherboard for all RF lines.
  • Mounting bracket for inserts of popular dilution refrig­erators. QDevil supplies CAD files for customers who need to make their own brackets.

The High Frequency Daughterboard

The QDevil High-Frequency Daughterboard  extends the frequency range of the system to at least 12 GHz with four on-board mini-SMP connectors.

​​​​​Application examples:​​

  • Readout of superconducting resonators. 
  • Sub-nanosecond gate-voltage pulses. 
  • High-bandwidth frequency sweeps.

Grounding Plate

A Grounding Plate has been developed for grounding and ESD protecting samples while mounting, wire bonding, and transferring these in the QBoard daughterboards. The Grounding Plate is used with the QBoard Interposer to ground all lines from the daughterboard while mounting and wire bonding chips. A short cable is provided to connect securely to the ground, both in the wire bonder and while the daughterboard is transferred to the QBoard motherboard.

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QBoard with a mounted daughterboard. The 51 pin nano-D connectors are seen on the top side. The 16 mini-coax connectors are located in two rows on the bottom side.
Standard daughter boards (6.3x6.8 mm ² and 10.5x10.5mm² sample space) prepared for mounting of reflectometry components.
Standard daughterboards (6.3×6.8 mm ² and 10.5×10.5mm² sample space) prepared for mounting of reflectometry components.
High Frequency daughterboard with 4 high frequency lines (6.3×10.5 mm² sample space).
Grounding Plate for ESD protecting daughterboard in wire bonders etc., using fuzz button interposer to ground all lines.