Introduction to Rigid-Flex PCB and Trend Forecasting

The designers of Rigid Flex PCB can use a single component to replace the composite PRINTED circuit board made of multiple connectors, multiple cables and ribbon cables, with stronger performance and higher stability. Meanwhile, the design scope is limited to a single component, and the available space can be optimized by bending and folding lines like paper swan.

Rigid Flex PCB is a kind of multilayer printed circuit board with both Rigid layer and flexible layer. The typical 4 layer Rigid-Flex Printed Circuit Board has a polyimide core, and the top and bottom sides of it are covered with copper foil. The external rigid layer consists of a single side OF FR4, which is laminated into two sides of the flexible core and assembled into multiple layers of PCB.

Rigid flexible PCB is widely used, but due to the mixed use of a variety of materials and multiple production steps, the processing time of rigid joint plate is longer and the production cost is higher. The processing technology of the flexible layer is completely different from that of the external FR4 layer when the multi-layer rigid joint plate is made. Layers made of different materials must be laminated together and then drilled and electroplated. Therefore, the production time of a typical 4 Layer Rigid Flex PCB may be 5 to 7 times longer than that of a standard 4-layer Rigid PCB.

Rigid Flex PCB’s application range mainly includes: aerospace, such as high-end aircraft mounted weapon navigation system, advanced medical equipment, digital camera, portable camera and high-quality MP3 player. Rigid Flex PCBS are most commonly used in the manufacture of military aircraft and medical equipment. Rigid Flex PCB has brought great benefits to the design of military aircraft, because it not only improves the connection reliability but also reduces the weight. Of course, the benefit brought by the reduction of the overall volume cannot be ignored

The cost of Rigid Flex PCB is higher than that of traditional Rigid board, but it provides the ideal solution for the project. Leveraging the interconnections of flexible substrates, rather than multiple PCBS, is the key to reducing footprint and weight, which is what many designs require.

Rigid Flex PCB has the characteristics of flexible, foldable, thus could be used to make custom circuit, to maximize the use of indoor space available to take advantage of this, reduce the occupied space, the entire system it Rigid Flex PCB overall cost will be on the high side, but as the industry matures and development, overall cost will decrease, thus will be more cost-effective and competitive.

In recent years, a large number of high-performance, multi-functional equipment emerge in PCB industry endless stream, the market development is particularly rapid to dazzle the consumer. However, a tight design process is needed to bring these products to the electronic design market, which usually involves a high density of electronic circuits, as well as reducing manufacturing time and cost. Designers are faced with more and more complex designs, such as a series of peripherals connected via IO. Moreover, today’s designs increasingly seek to make products smaller, cheaper and faster, especially in the mobile device market. This is a changing era. In addition to creativity and design ability, designers face many limitations.

One solution to help designers and design teams meet these challenges is to use rigid and flex design techniques known as Rigid-Flex printed circuits board. It’s not the latest technology, but it’s the most pervasive and cost effective.

From the traditional rigid PCB connected by cable, developed to today’s rigid-flex board technology. Considering from the aspect of cost, it is feasible for short-term design to connect two rigid pcb with flexible cable. But that requires installing connectors on every board, and connectors need to be assembled into circuit boards and cables — all of which add to the cost. In addition, the rigid PCB connected with the cable is prone to the problem of virtual welding, which will lead to the occurrence of faults. Rigid-flex PCBs can eliminate these virtual solder joints, making the PCB more reliable and providing higher overall product quality.

Let’s take a closer look at the total cost, and the chart below compares the simulation manufacturing costs of a rigid PCB using a traditional cable connection and a rigid-flex PCB design. The traditional design consists of rigid boards that use flexible cables and connectors, while the combination design is embedded in the rigid-flex board with two layers of built-in soft layers in the middle, and the overall structure is a set of four-layer printed circuit boards.

The manufacturing costs for both designs are based on the PCB manufacturer’s quote, including assembly costs (XPCB LIMITED, www.x-pcb.com). In addition, the cost of two separate four-layer circuit boards, connectors, and cables in traditional design factors is added.

As can be seen from the chart, when more than 100 sets are produced, Rigid-Flex PCB design will save more time and increase efficiency compared with the traditional cable design. The main reason is that the Rigid-Flex PCB does not contain any connector components/cables and does not require connector assembly. Not only that, their performance is reliable, sophisticated. And that’s just the tip of the iceberg.

With the technology of Rigid-Flex printed circuits board, designers can interconnect multiple PCBS in a single package without using connectors, wires, and cables. Since the boards do not require cabling, this reduces overall assembly costs and test complexity, both of which help reduce costs. In addition, fewer components need to be purchased, which reduces the bill of materials, thereby reducing supply chain risks and costs. Rigid-Flex PCB makes the maintenance of the product more convenient and saves the cost in the whole product life cycle.

The biggest defect of Rigid PCB is that the price is expensive, which may be nearly double the price of “Flex PCB + Rigid PCB”. However, if the connector price or Hot Bar cost is deducted, the price may tend to be the same, and the detailed cost may be determined by actuarial calculation.

Another disadvantage is that batching and stoking may require the use of carrier to support parts of the soft plate, which will increase the assembly cost of SMT virtually.

But Rigid Flex Board has many advantages as follows:

1. It saves space on the circuit board and eliminates the need to use connectors or hot bars. Because the FPCB’s have been fused together, the space that would otherwise be required to use the connector or Hot Bar process can be eliminated, making the loss of a connector a treasure to some high-density PCB’s. This, in turn, eliminates the cost of connector parts or Hot Bar processes. In addition, the space between the two boards can be tighter by eliminating the need for connectors.
2. The signal transmission range is shortened and the speed is increased, which can effectively improve the reliability Tradition through the connector signal transmission as “circuit board – connector – soft board – – circuit board”, and the hard and soft composite board of signal transmission is reduced to a “circuit board to soft board, circuit board, signal transmission distance is shorter, signal transmission attenuation problem between different media also reduced, generally the circuit above is copper is qualitative, and the contact terminal connector is gold-plated, is fully plated tin solder pin, and the need to use solder paste welded on the circuit board, signal transfer between different media will inevitably some attenuation, if switch to combine hard and soft board, these media will become less. The ability of signal transmission can also be improved relatively. Some products with high demand for signal accuracy can improve their reliability.
3. Simplify product assembly and save assembly time. The use of a hard and soft connector reduces the number of SMT connector hours. It also reduces the time required to assemble the machine by eliminating the need to insert the soft plate into the connector or the Hot Bar process. It also reduces the cost of parts management and inventory, because there are fewer BOM, so there is less management.

Why us?

• PCB factory passed UL, ISO90001: 2008 and ISO/TS16949: 2009 certification, which is the strong confidence for quality.
• The PCB products can be fully RoHS compliant, and 100% guaranteed to meet IPC II standards.
• Strong process capability:

Max Layer Count: 36L Max Final Board Thickness: 7.0mm

Max PTH Aspect Ratio: 10:1 Max Finished Copper Thickness: 20 OZ

Max Panel Size: 622*610mm Min Line Width/ Space: 0.075/ 0.075mm

Minimum Mechanical Hole/ Pad: 0.15/ 0.4mm Drilling Accuracy: +/ -0.05mm

PTH Bore Diameter Tolerance: +/ -0.05mm Min Solder Mask Dam: 0.1mm

Surface Treatment: OSP, HASL, ENIG, Hard Gold, Immersion Tin, Sterling, NiPdAu

• Our Values: Integrity-based, Focus on Profession, Commitment to Excellence
• Focus on profession: Specializing in Rigid Flex PCB R&D and manufacturing, the core team made up by the best field experts with 15+ years’ experience.