Publications - July 2016
Flexible and Rigid-Flexible PCBs – New Era in
The technology, which was out of reach all these years due to its cost and complexity, is now been affordable, convenient and less complicated – thanks to the rise in demand in wearable electronics. The cost is still little expensive than rigid PCBs but the time is not far when manufacturing cost of flexible PCBs would be at par with rigid PCBs.
Why flexible PCBs are getting popular?
The technology offers reduced volume and weight, increased electrical performance, larger design freedom and improved interconnect reliability. Increased use in handheld and mobile devices demand reduction in form factor, increased functional density and enlarged user comfort, which can only be achieved with flexible printed circuit board technology. Flexible circuit board is generally installed bent, folded or twisted. Flexible PCBs have not only replaced wiring and connectors but allowed designers to create configurations and complex geometries that were impracticable with rigid printed circuit boards.
Basics of Flexible Circuits
Two major varieties of flexible circuits can be manufactured
(1) Pure Flexible PCB
(2) Rigid-flexible PCB
Pure Flexible PCB
Flexible Printed Circuits Boards made their introduction into the electronics industry as substitutes for cable assemblies. It is a patterned arrangement of printed circuitry and components that utilizes flexible based material with or without flexible coverlay. Flexible PCB is nothing but a pattern of conductive traces bonded on a flexible substrate like polyimide (PI) – similar to FR-4 and CEM in rigid PCBs.
Rigid-Flexible circuit boards are made of rigid circuits (FR-4 PCB) and Flex circuits and circuitries. The rigid circuits (FR-4 PCB) are connected with single or multiple flex through PTH (via), inside or outside of Flex circuit layer, so it enjoys the advantage of both Rigid FR-4 PCB and Flex circuit.
Advantages of Flexible Circuits
The primary benefits of flexible PCB compared to traditional cabling and rigid boards include the following benefits:
- Reduced wiring errors
- Elimination of mechanical connectors
- Unparalleled design flexibility
- Higher circuit density
- More robust operating temperature range
- Stronger signal quality
- High vibration resistance
- Improved reliability and impedance control
- Size and weight reduction
Disadvantages of Flexible PCBs
- Higher material cost than rigid or rigid flex PCB
- Low temperature ability in flex circuits
- More difficult and complex assembly for contract manufacturer or independent assembler (please choose your PCB assembler/contract manufacturer carefully for your FPCB assembly requirements)
- Easily damaged through improper handling (easy to bend and dent)
- Sensitive to scratching
- Difficult or impossible to repair once damaged
Things to know and understand while ordering Flexible PCBs
In general, following are the final PCB thickness you should expect from QualiEco Circuits:
|No. of Layers||Final PCB thickness|
|1||>= 0.12mm and <= 0.2mm|
|2||>= 0.17mm and <= 0.3mm|
|4 & above||>= 0.25mm|
* Above figures are for general purposes only
Depending on the number of layers, following are the bend radius you should expect. Please confirm with our technical team, if you have any doubt.
|No. of Layers||Bend Radius|
|1||6-8 times PCB thickness|
|2||10-15 times PCB thickness|
|4 & above||>=12 times PCB thickness|
* Above figures are for general purposes only
Stiffeners are a less expensive alternative to rigid-flex PCBs. Some components (e.g. ZIF connectors) require rigidity in the PCB for better mounting. Stiffeners are materials added to a flexible circuit to fulfil this purpose.
3 types of material normally used as stiffener – Polyimide, Rigid FR-4 and Metal (e.g. stainless steel or aluminium)
QualiEco’s FPCB manufacturing capabilities
We can manufacture almost any type of flexible and rigid-flexible PCBs. Following are some of our capabilities:
- Single, double and multi-layer (up to 12 layers) flexible/rigid-flexible PCBs
- Base material stock in the range of 1-5mil (i.e. 0.025-0.127mm)
- Minimum 2mil (i.e. 0.05mm) track width and spacing
- Minimum 0.2mm finish hole size
- Polyimide, Rigid FR-4 and Metal – all 3 types of stiffeners
- Apart from yellow coverlay, other colours like blue, red, white and black are also possible (we already trialled different colours successfully)
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PCB Design Tips
When designing a PCB, try to limit the amount of draws you use. Draws use a lot of memory and slow the programming time. Use a flash for pads instead.
We have capability to manufacture and assemble Single Sided/Layer (SS), Double Sided/Layer (DS-NPTH & DS-PTH) and MultiLayer (up to 32 layers) PCBs with RoHS as an option.
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What our client says?
QualiEco Circuits Pty Ltd has the potential to be an excellent supplier to us! We appreciate the quality of service and support that we receive from QualiEco Circuits. Always deliver what is promised.Susan Chuard
Quality Assurance Supervisor