Fabrication of 6 layer rigid-flex PCBs involves several intricate steps, which must be executed with utmost care. A minute design or manufacturing flaw can lead to overall board failure.
Do’s and Don’ts
It is always better to prevent any design and manufacturing fault at the earliest before they escalate to major defects. By considering some standard rules you can minimize the number of defects during the fabrication of 6 layer rigid-flex PCB.
Follow the below listed do’s and Don’ts during the PCB fabrication.
- Keep your flex ‘flexible’ using the right type and amount of materials. For example, if an application demands for a 6 layer rigid-flex PCB that should bend during the assembly and then should remain in a fixed position, you must use the right kind of copper and adhesives that allow you to do so.
- It is suggested to keep circuits small. It is better to use a set of smaller circuits instead of a singular large circuit.
- It is not good practice to bend a flex circuit at the corners. However, some design situations demand bending at corners. In such cases, you can make a gentle curving, or use conical radius bends.
- Copper used in a 6 layer rigid-flex boards has a tendency to detach from the substrate. Hence, it is essential to provide support for the copper to prevent it from detaching. Even if you are using surface mount pads and non-plated-through pads, consider using it along with some extra measures like coverlay mask to anchor pads.
- It is imperative to strictly follow the recommended tolerances whenever possible.
- It is better to avoid laying traces over each copper layer in the same direction. It is recommended to stagger the traces to achieve even distribution of tension between copper layers.
- It is recommended to carry a power or ground plane on a flex circuit to enhance/retain the board’s flexibility. You can consider using either solid copper pours or hatched polygons for the purpose.
Attention to Detail
In order to produce reliable rigid-flex based products, you must be careful enough to provide attention to detail. Otherwise, the final assembly may fail to provide the expected functionality and durability. These troublesome situations can be prevented by following the above mentioned recommendations.