Rigid Flex PCB boards are one of the most widely used printed circuit boards in industrial applications. Their versatility is one of the main reasons behind their popularity. They consist of hybridization of hardboard and flexible circuits, implying the manufacturing similar to hardboards with layers of flexible circuitry passing throughout the circuits. Their main purpose is to act as a hardboard while also conforming to the product’s specifications allowing it to fit on the board. A well-designed Rigid-Flex board can withstand thousands of flex cycles without fault. This property of Rigid-Flex PCBs makes them a suitable fit for flexing applications, also known as dynamic flex. However, because of being so versatile and having an intricate design, the boards are a tad expensive. Mentioned below are some of the ways to reduce Rigid Flex PCB costs.
Ways to reduce Rigid Flex PCB costs
- Simplify the design
One way to reduce Rigid Flex PCB costs is by simplifying complex designs and removing unnecessary materials. Minimize the number of circuit layers by cramming circuits onto a single layer. Do not go overboard on the number of layers if you can avoid it. Reduce the thickness of the materials you want to mount on your board. Using thicker materials leads to the application of more substances, adding more to the overall cost. Tailor the design to your needs by removing unwanted elements from the board. It would mean a more efficient and simple circuit, which would be easier to use, reducing the expenses at the same time.
- Choose your material carefully.
The raw material used to manufacture Rigid Flex PCB boards is a little costly compared to traditional PCBs. Rigid Flex PCB boards have some modifications and variations in their fabrication process, which result in them being expensive. Factors that impact material include mechanical properties, heat performance, signal performance, thermal reliability, and thermal reliability.
Mechanical Properties: The variations in the flexural strength, bending strength, shear strength, and thickness of the board play an important role in deriving the overall cost of the board. Use materials according to what is desired by your board. If you want a more rigid board, use stronger materials. However, if you need a more flexible, boards having lower strength would be a cheaper yet better alternative.
Heat Transfer: Without good heat transfer, the Rigid Flex PCB boards will affect functionality; however, if your design does not require the best thermal conductivity, choose a decent, less expensive heat transfer system. Do not spend all on the system that would not even give you any practical advantage in your project, and only swallow bucks. High temperature affects heat temperature. Yet the materials used to construct Rigid-Flex PCBs can withstand high temperatures. It is why Rigid Flex PCB boards are essential in applications that require high temperatures.
Signal Performance: The signal performance of Rigid Flex PCB boards gets adverse effects from the various properties of materials from which they are produced. Infrared radiation, coupling, and Raman scattering are some properties that affect signal performance. Choose appropriate materials that cater to your design, and fulfill the requirements instead of choosing fancy equipment.
Thermal Reliability: Varying temperature is another leading factor that affects Rigid Flex PCB boards. A decent board should have the ability to withstand temperature variations. The usual range that a typical Rigid Flex PCB board should be able to sustain is between -40 degrees C to +140 degrees C. However, if your design does not require such a wide spectrum, you can customize it to a lower range to reduce the total costs.
Temperature Reliability: Using the correct material can ensure the PCB board can handle temperature variation according to the board’s requirements. Choosing a suitable option that allows your device to function according to your board’s dimensions and your budget is necessary while choosing your board’s design.
Thus, choosing the suitable material for your PCB is significant if you desire to create a more efficient design that yields greater output or are searching for ways to reduce Rigid Flex PCB costs.
Spending too much on materials that will not bring any significant benefit to your board is not a wise move. Instead, use conventional material that will suffice according to the needs of your assignment.
Adjust Assembly according to your requirements
Soldered components on an electric circuit board make up a PCBA (Printed Circuit Board Assembly) or PCB assembly. Once you assemble the required equipment, you can begin the assembly process of the PCB. One of these methods is wave soldering and hand soldering.
Wave soldering is a PCB assembly process in which solder in the form of a solder bar is put in a high-temperature bath. It stays in the bath in molten and generates a wave at a high temperature whose range depends on the solder’s type. Tin\lead (Sn\Pb) solder has a lower melting point than lead-free solder. The assembly process includes the insertion of electric components, flux application, preheating, and wave soldering, followed by cleaning and testing. On detection of any fault (Pin Hole or Blow Hole Wave Soldering), it is sent for rework which the manufacturers generally do by hand. Hand Soldering is done in repair shops or shops with less workload.
You can minimize the cost of the assembly process by taking the following steps:
- Reducing the layers result in fewer plies of pre-plug needed to keep the board together.
- Flexible laminate is way more expensive than rigid ones as they are constructed sparsely from the final rigid-flex board. So, limiting their number results in the reduction of the overall cost.
- For specific thicknesses, use rigid board laminates instead of additional plies or flexible laminates.
- Model and test only those impedance values that constitute an essential part of the design.
- All the flexible arms can be terminated to get the lowest possible cost.
- The configuration of PCB can be simplified, optimizing the design, size, shape, etc. Additional plated slots reduce the yield.
- It is always a good practice to include a fabricator in the product design to produce an optimized PCB, reducing the need for redesigns.
- Employ the Vias that are not blinded or buried. Round holes and relaxed tolerances are economical options.
- Surface mounting (SMD) is advised. Plated-through-hole components need to be trimmed or formed before mounting. Manufacturers do this manually or by machines. Bringing SMD reduces the process involved as it uses pick-and-place machines.
All the above-mentioned techniques help reduce Rigid Flex PCB costs but vary according to the application. Sometimes, the money saved in splitting circuitry or the layers of a keyboard can translate to higher assembly costs. Every situation is unique and should be dealt with accordingly.
Increase Manufacturing Yield while lowering the overall costs
Manufacturing technologies differ from each other. The technology now involves glass fiber epoxy (FR4) applied as an external rigid board, and a solder mask is applied to protect the circuit pattern. Size tolerance accumulation affects the circuit pattern. So, this can be reduced by using embedded technology. They are printed by embedding flexible circuit units into internal rigid boards and pass through the Building up Process. A flexible circuit is embedded into the rigid board and then layered up. Rigid-flex PCBs are more compact and thus require less material. It increases revenue. So, you can reduce the overall manufacturing cost of the final product with rigid-flex PCB.
A few challenges are faced during manufacturing. Flexible parts of the PCB may bend slightly. It means that you should consider the mechanical stresses on the material. Treat the bend lines or bend areas carefully to prevent premature failure. Avoid vias and pads in the flex area, as mechanical stress can weaken the pads. Conductor tracks must also be routed perpendicular to the bend line to ensure stability. You can add the Dummy traces to strengthen the bend area with the existing traces. Instead of a solid copper plane, the flex area should have a hatched polygon for the ground plane. It is easily done using OrCAD PCB Designer, optimized for flex-rigid designs.
By taking all the mentioned steps into account, you can reduce the Rigid-Flex PCB costs of the entire project while increasing manufacturing yield at the same time.
Rigid Flex PCB boards have a very broad usage inside the industry due to their versatility and ability to cater to different applications. However, all those glitters are not gold, as they are expensive to build. Yet you can employ several ways to reduce the overall costs, including simplifying the design by eliminating extra elements, choosing suitable material that caters to the design requirements, and choosing sufficient assembly procedures which are cost-friendly. Not going overboard by investing in unnecessary high-end technology not supported by the design is one of the key steps in ensuring the developed Rigid Flex PCB boards fall within your budget. Consult this article to inform yourself on how to reduce Rigid Flex PCB costs and not spend extra modifying your design by adding fancy and unnecessary materials.