Mechanical Design

Peripheral Connector Placement

Peripheral designers should consider the impact of connector placement location. Carriers may have side-by-side port spacing as small as 2 mm (to support double-wide peripherals). Right-angle or edge-launch connectors placed along the sides of the peripheral could lead to interference with adjacently-mounted peripherals on the carrier. The best location for such connectors is along the board edge opposite the Samtec board-to-board connector. The use of vertical-launch connectors is also encouraged where feasible.

Peripheral Mechanical Support

Peripherals that are large in size or require substantial cabling may benefit from additional mechanical support. This support would be in addition to the board-to-board mounting hardware as described in the SYZYGY specification. Design of such support is beyond the scope of this guide, but may include, for example, a 3D-printed support bracket.

Peripheral Mounting Hardware

In many cases, the Samtec board-to-board connectors provide sufficient mechanical support between the carrier and peripheral. When a more robust mechanical connection is needed, for example when the peripheral is cabled to an external system, mounting holes provide the option for adding board-to-board standoffs.

The recommended hardware size is M3. Carriers and peripherals should be designed to accommodate this size.

The nominal SYZYGY board-to-board (carrier-to-peripheral) height is 5 mm. The mated height is determined by the Samtec connector placed on the peripheral. Other mated heights are possible. See the SYZYGY specification for more details.

There are many options available for non-custom mounting hardware. The table below lists two potential options.

DescriptionComponentPart Num
Male-to-female 5mm hex standoff with screw and nutMale-Female Threaded Hex Standoff, 5 mmMcMaster-Carr 93655A401
Phillips screw, 4 mmMcMaster-Carr 92000A113
NutMcMaster-Carr 91828A211
Male-to-female 5mm hex standoff with screw and thumb nutMale-Female Threaded Hex Standoff, 5 mmMcMaster-Carr 93655A401
Phillips screw, 3 mmMcMaster-Carr 92000A076
Thumb nutMcMaster-Carr 96445A330
Male-to-male hex standoff with nutsMale-male threaded hex standoff, 5 mmSamtec SO-0515-02-01-01-L

Cable Mounting Hardware

The nominal standoff height for SYZYGY cables is 0.125″ (3.18 mm). An option for standoff hardware is shown in the table below.

DescriptionComponentPart Num
Male-to-male 0.125″ threaded standoff with nutsMale-Female Threaded Hex Standoff, 0.125″McMaster-Carr 95316A100
NutMcMaster-Carr 91841A005

Status Indicators and PCB Labels

Carrier designers should consider including the following items for usability:

  • An LED indicator for each VIO rail to indicate when the rail is active
  • Silkscreen indicators for each port:
    • Port identifier (letter, number, reference designator, etc)
    • Port type (standard, TXR2, TXR4)
    • VIO group
    • Compatible voltage range

Example layouts for port silkscreen are shown below.