Various difficulties counter the versatility as well as flexibility that allow you to develop three-dimensional designs and items. Standard rigid-flex PCB styles allowed you to install parts, adapters, and also the chassis for your item to the literally more powerful rigid part of the setting up. Once more, in terms of typical layouts, the flexible circuit just acted as an adjoin while lowering the mass and also improving the resistance to vibration.
New product makes coupled with enhanced flex circuit technologies have presented brand-new design guidelines for rigid-flex PCBs. Your design team now has the liberty to position elements on the flexible circuit area. Incorporating this flexibility with a multilayer approach to rigid-flex design enables you as well as your team to construct even more wiring into the design. Nevertheless, acquiring this liberty includes a few challenges in regards to directing as well as openings.
Flexible circuits constantly have bend lines that influence directing. As a result of the possibility for product stress and anxiety, you can not put elements or vias close to the bend line.
Rendering demonstrating the basic idea of a bend line for a rigid-flex PCB.
As well as even when parts are properly located, bending flex circuits puts repeated mechanical stress and anxieties on surface-mount pads and through openings. Your group can lower those stresses by utilizing through-hole plating and by strengthening pad assistance with added coverlay to anchor the pads.2.
As you design your trace routing, comply with methods that decrease stress and anxiety on your circuits. Use hatched polygons to keep versatility when bring a power or ground aircraft on your flex circuit. You need to make use of rounded traces as opposed to 90 ° or 45 ° angles and use teardrop patterns to alter trace widths.3.
Drop patterns as utilized for trace-to-trace links.
These methods lower tension factors as well as vulnerable points. An additional best method distributes stress across traces by staggering the top as well as lower traces for double-sided flex circuits. Offsetting the traces avoids the traces from laying over each various other parallel and also enhances the PCB.
You should also route traces perpendicular to the bend line to reduce stress and anxiety. When relocating from rigid to flex and back to rigid, the variety of layers from one medium to the various other might differ. You can use trace routing to include tightness to the flex circuit by balancing out the transmitting for nearby layers.1,2,5,6.
Electromechanical Elements Impact Design.
When you design rigid-flex PCBs, think in terms of electromechanical factors that influence both the flex circuit and also the rigid board. As you build your design, concentrate on the ratio of bend radius to density. With flex circuits, limited bends or an enhanced thickness at the bend location enhance the opportunities for failing. Producers suggest maintaining the bend distance at a minimum of 10 times the thickness of the flex-circuit product and developing a "paper doll" of the circuit to determine where flexes happen.3,6.
You need to avoid stretching the flex circuit along its outer bend or compressing it along the inner bend. Enhancing the bend angle beyond 90 ° rises extending at one factor as well as compression at another point on the flex circuit.
An additional crucial problem in rigid-flex reliability is the thickness and kind of conductor discovered in the bend area. You can decrease thickness and also mechanical stress and anxiety by decreasing the amount of plating on the conductors as well as making use of pads-only plating. The use of hefty copper, gold, or nickel plating lowers versatility at the bend and also allows mechanical stress and anxiety and also fracturing to happen.
Rigid-Flex PCB Design Requires Team Effort.
New PCB design tools give your design team the ability to manage numerous layer heaps, visualize 3D electromechanical designs, check design policies, and also mimic the procedure of flex circuits. Despite these tools in hand, the effective design of a rigid-flex PCB depends upon synergy between your team and also fabricators.