How does flex PCB production support high-density interconnects?
flex PCB production support
As the PCB industry continues to shrink component packages, pin-pitches and signal trace routings, high-density interconnects are becoming more important than ever. To meet the requirements of such a high-density design, rigid flex is often used as it provides the combination of flexibility and space efficiency that these designs require. Rigid flex is also commonly used in military and aerospace applications like aircraft instrumentation, as well as medical equipment such as implants. Industrial machinery and automotive electronics also use this advanced manufacturing technology to great effect as well.
The main challenge to producing a high-density rigid flex board is ensuring that the copper layers of each flex section are properly designed. This involves generating the correct impedance values for each copper layer using flex pcb production design software, then etching and plating them to create the necessary conductor paths. This step is crucial to ensuring that the copper traces have enough thickness and impedance to support the circuit’s electrical function without causing excessive strain on the flexible section.
In order to reduce stress on the traces and prevent them from breaking under strain, it is a good idea to design them with a gradual transition between wide and narrow ends. Abrupt changes are more likely to break the traces due to the stress they will encounter during bending and soldering. A gradient transition helps to avoid this problem and can be achieved by adding a fillet to the end of the thick copper traces.
How does flex PCB production support high-density interconnects?
Another way to improve a flex circuit’s ability to bend is by adding a shielding film to certain areas of the board. This can be useful in reducing electromagnetic interference (EMI) and shielding against radio frequency radiation (RF). In addition to shielding, adding a layer of copper on the back side of the flex circuit can help improve its conductivity and mechanical strength.
After the conductive material has been etched and plated on each flex section, the final step in production is to add a coverlay to the top of the panel. This can be applied by a silkscreen printing process or, for simpler designs, by an adhesive-less polyimide film process. This layer acts as a solder mask and protects the copper from dirt, moisture and damage during assembly.
The flex circuit is then laminated with rigid sections into a finished rigid-flex panel, typically using a glass epoxy substrate. Plated through holes are drilled into the rigid sections and flex panels before being layed on top of each other. The plated through holes from the flex circuit are then connected to the final plated through holes on the rigid sections.
This layered structure is what makes a rigid-flex panel so versatile. Depending on your application, it may be the ideal solution for your product’s needs. If you are interested in learning more about how flex-rigid boards can be incorporated into your next design, talk to the experts at JLCPCB today! We offer a wide range of premium quality products at competitive prices.