How do rigid flex boards reduce assembly errors?
rigid flex boards reduce assembly errors
Rigid flex PCBs are an excellent choice for applications that require the best combination of flexibility and structural integrity. They are commonly used in aircraft, automotive, and medical devices, as well as consumer electronics and wearables. However, they are not without their challenges. Poorly designed rigid flex PCBs may suffer from thermal issues, electrical performance problems, flexibility and mechanical failures, and reduced circuitry lifespan. The good news is that working with a reputable rigid flex board manufacturer can help reduce these issues, ensuring that your final product will function correctly in the field.
Insufficient spacing between drill holes and copper on rigid flex board can lead to short circuits, fluctuations in impedance, weaknesses in mechanical integrity, and challenges with assembly and soldering. To avoid these problems, you should use a design system that allows you to set a minimum hole size in both the rigid and flex areas of the board. The design should also be configured so that the plated through holes are in the rigid area, which is more easily drilled with mechanical tools.
A lack of rigidity can lead to stress concentrations that cause cracking in a flex circuit. To avoid this, consider incorporating stiffeners into the flex circuitry where needed. Stiffeners are typically made of aluminum or steel, and they can be anchored to the underlying substrate with adhesives or rivets.
How do rigid flex boards reduce assembly errors?
A mismatch between the material’s CTE expansion rates can cause bare circuit board production and assembly to be problematic, particularly in rigid flex PCBs with a mix of rigid and flexible sections. This problem can be resolved by using a no-flow prepreg when manufacturing the rigid section of the circuit. A low-flow prepreg should be used for the flex portion.
If you’re designing a rigid flex circuit with a flexible section, make sure that the circuits in the flexible part are routed around a dummy copper plane to increase their durability. In addition, you should avoid using solid copper for the flexible section of the circuit and opt instead for a cross-hatched pattern. This will allow the flexible part of the circuit to better withstand the stresses of bending and handling.
It’s also important to adhere to the minimum bend radius standards when creating a rigid flex circuit board. Adhering to these guidelines will produce high-quality rigid flex PCBs that can withstand sudden shocks and vibrations, as well as hundreds of thousands of flex cycles. The integration of rigid and flexible sections into a single board enhances mechanical stability and reduces the number of interconnects, leading to fewer points of potential failure.
The acrylic adhesives that are often used in the coverlayers and bondplies on rigid flex PCBs can compromise the dependability of vias in flexible sections by creating stress fractures. To prevent this from occurring, a technique called cut back coverlayer and bondply can be used to reduce the thickness of these materials. This will also allow the flex circuit to better resist CTE expansion rate changes.