RAYPCB / Flexible circuits
2 Layer Flex PCB Stackup & Connector Design
Work through the bend region and connector region as two separate thickness checks.
Share your drawings, quantities and mechanical requirements for an engineering-reviewed quote. You can contact us directly without completing the optional tools.
2 Layer Flex PCB Stackup & Connector Design — design decisions
This guide is for a designer preparing a two-layer flex drawing. For purchasing and fabrication scope, use the double-sided flexible PCB manufacturing page. The example below is arithmetic, not a recommended production stackup.
| Example bend-region contribution | Illustrative total |
|---|---|
| Two copper layers, 18 µm each | 36 µm |
| Polyimide core | 25 µm |
| All internal bonding adhesive | 25 µm |
| Both coverlay films combined | 25 µm |
| Both coverlay adhesives combined | 25 µm |
| Example finished bend-region sum | 136 µm = 0.136 mm |
At a user-selected ratio of 10, the comparison radius is 1.36 mm. This does not prove that 1.36 mm is a safe operating radius. Replace the totals and ratio with the agreed construction and application requirements.
Carry tolerances through the connector-thickness calculation
The earlier 0.136 mm section is an arithmetic example, not a production tolerance. If a selected connector requires 0.30 ± 0.03 mm insertion thickness, the acceptable interval is 0.27–0.33 mm. A nominal 0.136 mm tail is not ready to insert merely because it has the correct outline.
| Hypothetical tolerance calculation | Value |
|---|---|
| Unreinforced tail | 0.136 ± 0.015 mm |
| Added stiffener and adhesive | 0.160 ± 0.015 mm |
| Nominal local total | 0.296 mm |
| Worst-case interval by addition | 0.266–0.326 mm |
| Comparison with the example connector | Low end is below 0.270 mm: nominal fit alone is insufficient |
These assumed tolerances illustrate worst-case addition, not RAYPCB capability. Obtain the actual laminate, adhesive, stiffener and connector tolerances, and agree the measurement method. The reinforced contact area and the free bend section need separate thickness definitions.
Relevant construction examples
Work the connector dimension independently
Using the illustrative 0.136 mm flex, a 0.100 mm local stiffener and 0.025 mm stiffener adhesive gives 0.261 mm nominal local thickness. A 0.300 ± 0.030 mm connector requirement spans 0.270–0.330 mm, so this example is outside that nominal interval.
Do not solve a connector mismatch by silently adding its stiffener thickness to the bend calculation. The two checks describe different zones. Consult the actual connector drawing, assembly tolerances and compression effects, then update the released fabrication drawing.
Material selection starts with the actual laminate, copper and coverlay grades. Refer to DuPont’s laminate portfolio and the supplier drawing for each selected grade. Kapton and Pyralux are not interchangeable names for every flexible circuit material.
Flex design & project planning
Check bend-region thickness and the local connector stack separately. Enter the actual supplier values; do not count stiffeners as part of a flexible bend.
Flexible PCB Design Workbench
For pricing a two-layer fabrication job, continue to double-sided flex manufacturing and budget.
Prepare the next engineering review
Send the available files even if some decisions remain open. Mark the points where you need advice.
- Gerber or agreed fabrication data, outline drawing and drill data where applicable.
- Layer stackup, material grades, finished thickness and tolerances.
- Bend zones, installed radius, motion duty, coverlay openings and reinforcement drawing.
- Connector requirements, order quantities and requested delivery.
Download calculator results if you want to include them. Contact inputs are not automatically filled from these tools.
Practical questions
Does a correct nominal thickness guarantee connector fit?
No. Include tolerances, adhesive, stiffener and the connector specification. Check the full thickness interval and measurement method.
Does the bend calculator predict fatigue life?
No. It checks geometry against an entered planning ratio. The complete construction and motion conditions require engineering review and, where needed, qualification.
Where do I request manufacturing pricing?
Use the double-sided flex manufacturing page to review the procurement scope, or send the available files directly through Contact.