10 Common Mistakes Made with Flex Circuits
| 1. | Placing vias outside the stiffener area or where the flex bend which can cause via cracking. |
| 2. | Not providing proper stiffener information. It is important that you show the x & y dimensions of the stiffener, show location of the stiffener, and dictate the type of stiffener material - FR-4, Kapton, Ceramic, etc. |
| 3. | Failing to state a tolerance on the overall thickness of the stiffener area. The tolerance specified should not be less than +/- 10% of the overall thickness in this area. |
| 4. | Bending a flex circuit tigher than is recommended. See "Minimum Bend Radii for Flex Circuits" chart for guidelines. |
| 5. | Not showing the material stackup. (Should indicate base material, copper thickness, cover layer thickness, as well as stiffener material and thickness.) |
| 6. | Traces routed on top of each other on adjacent layers. Traces should be staggered on the adjacent layers to avoid "I-beam" effect which could cause trace fracture. |
| 7. | Having silkscreen nomenclature less than .007" which can cause illegibility or placing silkscreen too close to exposed pad areas. Silkscreen should be no closer than .010". |
| 8. | Designing without correct pad geometries. Teardrops and tie downs are important to add to pad geometries to avoid stress fractures and assembly issues. |
| 9. | Placing edge of feature closer than .010" to edge of board. |
| 10. | Making hole size on stiffener too small. Should be +.020" over finished hole size. |
Note:Please contact Advanced Circuits flex experts to help you select the right material, review your design for reliability and manufacturability, help you with proper fabrication notes and stackup, and recommend cost reduction ideas.