What is Rigid Flex PCB?
Rigid Flex PCB board is a circuit board combination of flexible circuit boards and rigid circuit boards through lamination process. Rigid-flex board has both the durability of rigid PCB and the adaptability of flexible PCB. There are both flexible PCB areas and rigid PCB areas, it’s a great help to save the internal space of the product, reduce the volume of the finished product, and improve the performance of the product.
Types of Rigid Flex PCB
If it is classified according to the process, the bonding method of flexible boards and rigid boards can be divided into two categories: Rigid Flex composite board and Rigid Flex multi-layer combination board. The difference in the technology of Rigid PCB and flexible circuit board composite.
Rigid Flex PCB composite board
The FPC and rigid PCB are pasted together, there is no plated hole connection at the pasting place, and the number of layers is more than one. It’s just that the rigid board and the flex board are manufactured separately and then pressed into a single circuit board. There are signal connections but no through-hole design.
Rigid Flex multi-layer combination board
With plated-through holes, and more than two conductor layers. there are common blind hole and buried hole designs, so you can have higher density circuit design.
Rigid Flex PCB Products
Rigid Flex PCB Material
Rigid Flex PCB includes materials for rigid boards and flex boards. The base materials for rigid printed circuit boards are usually fiberglass and epoxy. And Flex PCB materials are Copper Foil, Adhesive, Polyimide.
Rigid Flex PCB Fiberglass
It is an inorganic non-metallic material with excellent performance. There are many kinds. Its advantages are good insulation, strong heat resistance, good corrosion resistance and high mechanical strength. The glassfiber is often used as reinforcing material for composite material, electrical insulation and heat insulation materials.
Rigid Flex PCB Expoxy
Epoxy resin is a high molecular polymer. Aldehyde epoxy resin can effectively improve the heat resistance of copper clad laminates, greatly enhance the corrosion resistance of copper clad laminates, Ensure the stability and durability of copper clad laminates in high temperature environments.
Rigid Flex PCB Copper Foil
Copper foil in rigid PCB has low surface oxygen characteristics, can be attached to various substrates, such as metals, insulating materials, etc., and has a wide temperature range. The copper of flexible circuit board is classified as Rolled & Annealed copper and Electro Deposited copper. The material of Rolled & Annealed copper is better flexible and foldability. So we usually ask customer to use Rolled & Annealed copper to make flex PCBs.
Rigid Flex PCB Fabrication Capabilities
| Item | Technical Parameters | Specification |
| Min Rigid Flex PCB Line Width/Space | 3/2.7 mil | Finished Copper Thickness H oz |
| Min Rigid Flex PCB Pad Ring of Via | 3 mil | Distance between hole edge to ring outskirt |
| Min Rigid Flex PCB Pad Ring of PTH | 5 mil | Distance between hole edge to ring outskirt |
| Min Rigid Flex PCB Via Size | 4 mil | Board Thickness < 1.2 mm |
| Min Rigid Flex PCB Thickness of Double sided | 0.2 mm | Final Board Thickness |
| Min Rigid Flex PCB Thickness of Multilayer | 0.4 mm | Final Board Thickness |
| Max Rigid Flex PCB Thickness | 8.0 mm | Final Board Thickness |
| Max Rigid Flex PCB Dimension | 609×609 mm | Single and Double Sided PCB |
| Space Between Line to Board Edge | 10 mil | Milling of Outline |
| Max Rigid Flex PCB Layers | 30 Layer | |
| Rigid FlexPCB Solder Mask Color | Green,Black,Blue,Red,white,Yellow, | |
| Rigid Flex PCB Silkscreen Color | White,black,yellow | |
| Rigid Flex PCB Surface Finishing | HASL,ENIG,ENEPIG,ImAg,ImTin,OSP, Hard Gold Plating | |
| Max Rigid Flex Finishing Copper Thickness | 6 oz | |
| Dielectric Thickness | 2.5 mil | |
| Rigid Flex PCB Material | FR-4,Aluminium substrate,Rogers4350C,Polyimide | |
| Rigid Flex Special Technology | HDI PCB, Via in Pad Rigid Flex PCB,Blind&Buried Rigid Flex PCB |
Advantages Of Rigid Flex PCB
Reduced Assembly Cost
Rigid flex PCB boards can reduce the labor of rigid PCB assembly along with the number of connectors is reduced. It also reduces the labor of the whole machine assembly after inserting the flex board into the connector. And the management and inventory cost are reduced since the rigid flex board BOM table is reduced.
Rigid Flex PCB Shape Flexible
The flexible part of Rigid Flex PCB can be flexibly bent, and the components installed on rigid flex board can be presented in various spatial angles, which is more flexible than traditional electronic integration methods, just like an extra dimension, so it is called “4D “integrated, it’s suitable for wearable devices, smart home, etc.
Rigid Flex PCB Save Space
Rigid flex board combined flex printed circuit and rigid PCB, saving space and realizing more functions in small devices. It’s light in weight, and can be flexibly bent to meet the application of complex space structures. They are widely used in modern electronic equipment and become an ideal choice for mobile communication products.
Rigid Flex PCB Fabrication
The manufacturing process of the rigid flex PCB board combined the manufacturing process of the rigid PCB and flexible circuit board. Below we will mention some special processes that are different from flex printed circuit and rigid PCB boards.
Material Shearing
Rigid flex board and flexible PCB board with single-sided, and it is not allowed to cut single-sided sheet directly. They need to be etched into single-sided sheet from 2 layer flex PCB to ensure the bonding force between layers and avoid delamination.
Inner Layer Circuit
Check FlexPCB is flat without discounts, wrinkles, and no glue stains on the board surface, etc.
All flex board PCB must be attached to the pallet for development and etching, and one pallet is attached to one flex PCB to prevent the flex PCB from being folded and wrinkled due to etching transmission problems.
All boards must pass through AOI, and flex printed circuit does not allow supplementary lines.
Rigid Flex PCB Lamination
Rigid flex PCB board lamination must use a special program, the lamination program can not be mixed with other boards
When the flex PCB is browned, it must be attached with a pallet. After browning, the flexible circuit board with wrinkles will be discarded. Before riveting, the flexible PCB board must be browned OK.
After riveting FR-4, flex PCB and No-Flow PP, first check whether there is less or more PP, and then use X-Ray to check whether there is layer deviation.
NC Drilling
Rigid Flex PCB drilling is a process of PCB manufacturing, and it is also a very important step.
The inspection process focuses on checking whether there are any residual glue burrs on the flexible circuit board at the T position of the rigid and flex PCB joint. If there is any abnormality, notify the process in time for follow-up processing.
Plating Through Hole
The program for desmearing the rigid flex board is a special program, please pay attention to the switching of the desmearing program before copper plating.
After removing the slag, the rigid flexible printed circuit board is copper-precipitated according to the 2 layer PCB procedure after the PI is adjusted. The PI potion is prepared according to the volume concentration of 40%. The working temperature of the potion is 40°C, and the adjustment time is 4~8MIN.
Rigid Flex PCB Board Opening Technology
The rigid flex board is not an ordinary circuit board, but is composed of a rigid circuit board and a flex circuit board. The flexible area of the rigid flex PCB board is formed by removing the rigid layer in the area, leaving only the flexible layer, and removing the rigid layer. The whole process called opening technology.
There are three ways to opening the rigid flexible board: laser opening, gong machine-controlled deep opening and V-CUT opening.
Rigid Flex PCB Circuit Open-Short Circut Test
The electrical performance of the rigid flex PCB is usually achieved through the PCB open-short circuit test. There are two test methods of PCB open-short circuit test. One is fixture test, and the other is flying probe test.
Fixture testing is based on the test points on the circuit board to make a fixture with a bed of needles and many thin needles on it. Each needle corresponds to a test point and is pressed to make contact. Then conduct a continuity test or a functional test.
Flying probe test is a rapid movement of several probes at these test points, contact with these test points, and then the instrument measures the results.
Inspection of Rigid Flex PCB Board
Dimension measurement: measure whether the actual dimension of the PCB matches the customer’s original rigid flex circuit design file.
Holes: Check for missing holes, multiple holes, blocked holes, and hole size if matches rigid flex PCB design file.
Circuit: No short circuit, open circuit, exposed copper in the conductor, floating copper foil, repair wire, etc.
Silkscreen Printing: The silk screen printing of characters and symbols on the surface of the rigid flex PCB must be clear, and obvious, and the color meets the requirements, without repeated printing, missing printing, multiple printing, position deviation, and misprinting.
Rigid flex PCB warp and twist inspection: According to the IPC-6012 standard, the warp and twist of the rigid flex circuits should be within 0.75%.
Solderability Test: Take part of the rigid flex PCB for actual soldering to check whether the parts can be easily soldered.
Packaging: colorless air bag vacuum packaging, with desiccant inside, tightly packed.
Why Rigid Flex PCB Design?
Rigid Flex PCB is Reliability
The combination of rigid PCB and flexible circuit board can solve the problem of flex PCB assembly. The flex printed circuit is connected through a connector, which brings flexible PCB cost, inconvenient assembly and reliability problems. Flexible PCB assembly is easy short circuit, falling off and other problems. Rigid flex board can solve these problems.
Rigid Flex PCB Comprehensive Cost
Although the unit price of rigid flex board has increased, it saves the cost of the connector, reduces the rigid and flex PCB assembly time, reduces the rework rate and improves flex PCB manufacturing ability and reliability finally. When used in batch products, it is often effective to reduce whole product costs.
Effectively Improve The Signal Quality
Rigid Flex PCB is better trace continuity and signal integrity since connections are not made through connectors. Traditional IPC uses flexible PCB board and main control rigid PCB to connect. Since rigid flex PCB is in application. It solves many problems and also meets the structural design requirements of small size.
Application of Rigid Flex PCB Board
Industrial Application
Industrial applications include rigid flex PCB boards for industrial, military, and medical purposes. Most industrial parts require precision, safety, and non-destructive properties of the soil. Therefore, the requirements for rigid flex PCB boards are high reliability, high precision, low impedance loss, complete signal transmission quality, and durability.
Consumer Electronics
In consumer products, The rigid flex PCB board can connect different rigid PCB board and components three-dimensionally, so the total usable area of the PCB can be increased under the same circuit density. Increased its circuit carrying capacity, and reduce the limit of signal transmission capacity and the assembly error rate of contacts. On the other hand, since the rigid flex PCB board is light and thin, it can be flexibly matchedline, so it is of substantial help to reduce the size and weight.
Automotive Field
In the use of rigid flex PCB boards in cars, there are often buttons connected to the motherboard on the steering wheel, The connection between the car video system screen and the control panel, and the sound on the side door operation connection of loudspeaker or function keys, reversing radar imaging system, Sensor (Sensor, including air quality, temperature, and humidity, special gas adjustment, etc.), vehicle communication system, satellite navigation, rear seat control panel, and front-end controller connection board, external detection system, etc.
Why choose us?
King Sun PCB is one of top quality rigid flex PCB manufacturers. Quality assurance is our core value.
Low rigid flex PCB cost is our goal. We have been optimizing production to reduce the manufacturing cost of rigid flex board.
We pay attention to fast turn rigid flex PCB manufacturing, So that customers’ new products can be launched quickly. below is our lead time of PCB rigid flex.
| Layer Count | Standard Lead Time | Quick Turn Around |
| 1-2 Layer | 4-5 DAYS | 24 Hours |
| 4 Layer | 8-9 DAYS | 5-6 DAYS |
| 6 Layer | 9-10 DAYS | 6-7 DAYS |
| 8 Layer | 10-12 DAYS | 8-9 DAYS |
| 10 Layer | 12-14 DAYS | 10 DAYS |
Complex PCB Technologies
We make very complex and special Rigid Flex PCBs like below:
- Via in Pad rigid flexible printed circuit board
- Embedded Copper Coin rigid flex board
- Backdrill rigid flex circuits
- Depth Slot rigid flex PCB
- Countersink Hole rigid and flexible PCB
- Blind and buried vias rigid flex PCB prototype
