Locate the loads that need support
Show where connector mating, component handling, or fastener loading enters the flex. Decide whether the stiffener transfers that load into an enclosure or merely supports a local area. Hirose’s DF40 guideline addresses reverse-side FPC support for its connector series. Treat that as a prompt to consult the selected connector instructions, not a transferable dimension rule.
FR-4 support drawing details
| Feature | Define | Review |
|---|---|---|
| Support outline | Datums and functional coverage | Connector and component access |
| Thickness | Local reinforced section | Enclosure fit and handling |
| Attachment | Bond material and coverage | Thermal sequence and joint quality |
| Transition | Support end relative to flex span | Installed bending location |
Coordinate support and component access
Review the stiffener outline against solder joints, tooling, inspection access, and the installation path. A large support can interfere with folding or enclosure seating; an underspecified one may leave the interface’s load path unclear. Use the component-placement guide to coordinate the supported island and transition planning to locate the adjacent free span.
Specify the bonded assembly
Call out support material, thickness, bonding side, adhesive, and datum-based position. State whether attachment occurs before relevant thermal or assembly operations. Define the inspection surface and any flatness or fit requirement that matters to the product. Check prototypes using the actual connector or enclosure load rather than approving support from a flat visual inspection alone.
Before you release the design
- Identify the intended supported load.
- Show the bonding face.
- Check assembly-fixture and enclosure clearances.
- Inspect the support after representative connector operation.
Watch points
- A mechanical FR-4 stiffener does not provide electrical interconnection into a rigid region.
Practical questions
Should the stiffener match the component outline?
Determine coverage from the load and connector guidance. A copied component silhouette does not establish adequate support or assembly clearance.
Can one support carry several components?
Consider a common island if it fits assembly and enclosure needs. Review bending boundaries and load transfer across the entire supported area.
Technical references
References support the material or design context. Check the exact grade, part number, document revision and project conditions before release.Updated 27 September 2026 · Technical content policy · Engineering guidance supports project review; the agreed drawing defines the build.