吃瓜tv / Rigid-flex engineering
Air Gaps in Rigid-Flex PCBs: Drawing & Review
Specify intentionally unbonded regions clearly and review their mechanical and manufacturing consequences.
Bonded flex and separate flex leaves are different constructions
| Section across the free-flex region | Bonded construction | Unbonded-leaf concept |
|---|---|---|
| Upper leaf | Copper / flexible dielectric / copper | Copper / flexible dielectric / copper |
| Between leaves | Specified bonding layer | Intentional unbonded space; no bond across the defined free span |
| Lower leaf | Copper / flexible dielectric / copper | Copper / flexible dielectric / copper |
| At the rigid termination | All layers located by the approved transition | Leaves enter a defined bonded termination; the boundary is dimensioned |
Separating leaves lets them follow different arcs rather than forcing the complete thickness to bend as one bonded section. This also creates issues to resolve: clearance between leaves, rubbing, local buckling, routing references and assembly restraint. An intentional unbonded span must be distinguished from an unwanted bond failure.
Geometry example: for two neutral paths separated by 0.20 mm through a 90掳 bend, the arc-length difference is 胃 脳 螖r = (蟺/2) 脳 0.20 鈮� 0.314 mm. This only illustrates why equal-length leaves may not fit the same bend. It is not a cut-length allowance, fatigue prediction or approved bookbinder dimension.
| Good reason to evaluate the approach | Reason to reconsider it |
|---|---|
| Multiple flex leaves need independent motion or installed arc lengths | The enclosure cannot provide clearance or control rubbing. |
| A bonded section is mechanically unsuitable for the installation | A single or simpler flex section can solve the routing problem. |
| The assembly sequence can locate and protect each leaf | Handling or clamping would force the leaves into the wrong shape. |
Document leaf lengths and the bonded/unbonded boundaries in the regional layer drawing. Qualify the actual construction and motion duty before making reliability claims.
Construction reference
Gallery references illustrate board forms. They do not certify the construction, dimensional limits or operating life of your design.
Continue with the next engineering decision
Reference documentation
Use the documentation for your installed software version and the selected material grades. describes its region and bending workflow. These references support design communication; they are not manufacturing approval for a particular board.
Send a complete project brief
Include the flat outline and installed view, layer/region mapping, material grades, finished thicknesses, bend duty, copper artwork, drill information and quantities. Add the BOM, placement file and acceptance requirements when assembly is included.
Mark unresolved choices rather than guessing. Download tool results if they help describe your request. Contact does not automatically receive calculator inputs.