Flexible PCBs

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What is Protective flex technology?

Flex technology is the secrete behind flexible electronics. Flexible PCB prototype is diverse in their designs and application. The trend towards further expansion of their use is due to the great benefits that they create in the technology of interconnects. Now they have become a very attractive way to provide interconnects in manufacturing of modern electronic equipment.

There are many reasons for using flexible printed circuit boards as a means of interconnecting electronic devices. In some cases, when the resistance of flex circuit to dynamic loads is required, the use of flex circuits is obvious. At least in this they have no alternative. Much more than other areas of use of flexible circuits in which they help solve the problems of compaction of the hardware layout.

Flexible PCB use the thinnest dielectric base of all materials available today for interconnects. In some cases, PCB flexible having a total thickness of less than 50 μm, including a protective layer, can be made from these materials. For reference: rigid mounting substrates with the same functionality are twice as thick. Not only is the small thickness of PCB flexible attractive in itself, the ability to fold it due to flexibility also reduces the size and dimensions of electronic devices.

An additional advantage of the small thickness of flexible circuits are their low weight. By themselves, they are 75% lighter than similar finished rigid PCB. The small mass of interconnects sold to customer by flexible board proved to be so attractive in manufacturing of aerospace equipment due to its flexibility that this area of their use began to compete in production volumes with portable electronics.

Flexible PCB represent a simple and fast technology for creating interconnects for nodes and blocks of electronic equipment. An alternative to flex circuit - wire installation and flexible cables - is associated with the need to lay wire along the intended connection routes and fix them, stripping and soldering each wire separately. Wiring harness installation also requires additional labor for the designation of communication addresses. Flexible PCB prototype make it possible to use group methods of assembly and installation of products because of its felicity that is always in PCB prototype. In addition, their manufacture itself is much cheaper due to the use of group manufacturing and labeling technologies.

While wire installation is inevitably associated with the human factor - the source of errors, flex circuit do not have sources of errors of a human nature.

Flexible PCB prototype id designed as part of the interconnect system and then reproduced by machine methods that prevent the influence of the human factor. As a result, with the exception of unavoidable production errors, flexible PCB do not allow the creation of connections that do not correspond to the flex circuit design.

Reliability specialists are always looking for interconnect defects when searching for sources of electronic equipment failures. Academician Berg once declared: “The science of reliability is the science of contacts. The more of them, the less reliable the system.” Flexi PCB is ideal for reducing pins, space and weight. When properly designed and efficiently used in manufacturing an electronic layout, they contribute to increased reliability by reducing the number of interconnects within an electronic module or unit.

There is a rule among flex circuits specialists that flex PCB is cost-effective when you need to have more than 25 point-to-point interconnects. This number is somewhat arbitrary, but the basic concept is correct. To select a solution, you need to compare the cost of wire and printed flexible flexi installation, taking into account the volume and other factors of production. Some product designers find flex PCB packs more cost-effective as early as two or three links. Nevertheless, in some cases there is a justification for using wiring harness as opposed to flex PCB.

What is the flexible circuit boards application

If you are going to enter this field to develop, you must first understand the related terminology of this industry and the characteristics of the product, otherwise you may be unable to do so. The same is true for flexible circuit board products. The common terms in the flex PCB industry are as follows:

1. Flexible circuit board structure and related constituent material names

Flex PCB are a special PCB product designs that its application can make three-dimensional shape changes during downstream assembly of flexible boards use in consumer electronics. Its substrate is flexible polyimide (PI) or polyester (PE). The aforementioned soft board is also like a hardboard. this board can be obtained by plated through-holes or exterior adhesive fillings for through-hole inclusion or facade adhesion. The surface of the board can also be covered with a soft cover layer for protection and soldering purposes, or a soft solder-proof green paint can be printed on it.

2. FPC Flexural Failure

Due to the repeated bending and flexing action of flexible printed circuit boards during the use of electronic products, the material (plate) is broken or damaged. We call it Flexural Failure.

3. Polyurethane soft material

It is a kind of "polyurethane" sheet-like insulating soft material. It is attached with rolled copper foil or electroplated copper. After foiling, it can be made into the base material of flex PBC.

4. Membrane Switch

Using transparent polyester film as carrier, screen printing method will be used to print silver glue (Silver Pastes) on thick film circuit, and then with hollowing pads, combined with protruding panel or PCB flex circuits, become a "touch" switch or keyboard. This little "button" design is usually utilized in hand-held calculators, electronic glossaries, and remote controllers use in remarkable customer home devices.

5. Polyester Films Polyester Sheets

Polyester sheets are referred to as PET sheets, which is a material with good electrical resistance. In the circuit board industry, the transparent protective layer on the outside of the imaging dry film and the coverlay on the outside of the flex PCB films, which will be utlized for the silver paste printed film circuit as the substrate. In the electronics industry, you can as well in the insulation layer of cables, tubular containers of multiple ICs transformers or coils.

6, Access Hole (through-holes, open-bottom holes)

Often refers to the protective cover of the soft board (cover through holes that must be punched out first), used to fit on the surface of the flex circuit board as a solder mask use. However, it is necessary to deliberately expose the hole ring, hole wall or square welding pads requirements for welding to facilitate the welding of parts. The well-known Access Hole basically indicates that the surface layer has a through-hole so that the environment will be able to "close" to the solder connections on the covering of the board layout under the surface protection layer. Some multilayer circuits also have such exposed holes.

7. Acrylic is a popular name for polyacrylic resin. Most of the flexible board use its film as the next film.

8. Adhesive glue such as resin or coating, can make the two interfaces to finished adhesion.

9. Anchoring Spurs on the middle plate or single panel of the force claw. In order to make the hole ring welding pad have stronger adhesion on the surface of the plate, you can add a few more fingers on the extra space outside the hole ring. To make the ring more solid to reduce the possibility of floating away from the plate surface.

10. Bandability.

Bending ability is a feature of the changing flex board (for instance, the print caps of computer disk drives), and its status should strike one billion times of "bend."

11. Bonding layer

Bonding layer, normally taken as the film layer of the multi-layer board, or the strip of flex circuit board, the adherent layer within the polyurethane (PI) and copper skin substrate.

12. Coverlay/Cover Coat Surface protection layer, protective layer

Coverlay is the outer layer of the soft board. Coverlay is always hard to be fused with the green paint applied for the hardboard, due to the fact that it may drop off while bending. It is necessary to make use of soft "acrylic" laminated on the exterior of the flex circuits. this can also be used as a solder mask and can preserve the outer layer of the flex circuits, and improve the resistance and strength of the flexible board. The "outer membrane" is referred to as the surface protective layer or protective layer.

13. Reel to Reel (disc) linkage type

As some electronic parts and components, it can be produced by the reel (disc) retractable process, such as TAB, IC metal frame (Lead Frame), a Some flex circuit board (FPC), etc., can take the benefits of the convenience of tape reeling to complete their online automatic operations to save time and labor costs for one-piece operations.

14. Dynamic Flex

It refers to a flexible circuit board that needs to be used for continuous motion, such as the flexible board in the read-write head of a disk drive. In addition, there is a "Static FPC", which refers to soft boards that have no action after being assembled properly.

15. Adhesive Film

Adhesive film refers to the dry thin film adhesive layer, which can contain reinforced fiber cloth film, or a thin layer without reinforcing material and only adhesive material, such as the adhesive layer of FPC.

16. Polyimide (PI) polyimide

It is a kind of excellent resin polymerized by Bismaleimide and AromaTIcdiamine. Initially, it was called the powdered resin product Kerimid 601 originated from Rhone-Poulenc, a French company. This PI sheet has great thermal resistance and an electrical shield. It is necessary for the manufacturing of automatic tape and flex circuit board. On the other hand, it is essential in the manufacturing of supercomputer motherboards and advanced military hard boards.

polyester or polyimide film with lightweight, high reliability, high wiring density, are usually used in making flex circuits. Flex circuit soft board can be said to be an excellent flexible printed circuit board. Flex circuit design has such superior benefits, so it will be more and more widely used in consumer electronic products, such as mobile phones, notebook computers, PDA, digital camera, LCD display and many other products. As professionals in the flex circuit industry, while mastering the processing methods and meanings of flexible circuit boards, they also need to understand the terminology of FPC flex boards and keep them in mind. Even in the work will be handy, no mistakes. The content of the article is reproduced on the Internet. If you have a better opinion or valuable opinion, please leave a message in our email

Why choose PCBONLINE Flexible PCB

PCBONLINE is a flexible PCB inc in China, whose service range is very different from other flex circuit manufacturers.

1. High quality imported flexible PCB raw materials, ensuring the quality from the source.

  • Material: TaiFlex, Dupont
  • Cover film: TaiFlex, APLUS,RCCT
  • PI reinforce: UBE, TaiFlex, SKC
  • Electromagnetic membrane: Sankei, Fang Bang, Toyo

2. As the professional flexible PCB supplier, we have many production types: flexible PCB led strip, CTP, LCM, MOBILE&TABLET, CCM, BIOLOGICAL RECOGNITION, AUTOMOTIVE, OPTICAL PICKUP UNIT, MEDICA
3. Professional R&D, production and quality management team with rich experience in flexible PCB fabrication.
4. From conceptual flexible PCB design to mass production, we provide you with 24-hour technical support.
5. Provide you with the best flexible PCB cost solution from the selection of design materials, the evaluation of manufacturability and the product design principles.
6. Full set of imported automatic production lines: Mitsubishi laser drilling machine, screen AOI, automatic exposure machine, automatic FPC black hole line
7. Strong technological capability.

Material Polyimide: Taiflex
Layer count 1-10
Final board thickness 0.05-0.6mm
Aspect Ratio 3:1
Copper thickness 1/3~3oz
Impedance Control Single Ended
+/- 10%
+/- 10%
Line/Space Inner Layer
External Layer
Min Drill Bit size 6mil
Hole size tolerance PTH
Hole Position Tolerance +/-2mil
Coverlayer Line to PAD
Profile Tolerance Puching
Laser Cutting
Surface Finish ENIG
Immersion Tin
Immersion Silver
Hard Gold Plating
Au 1-5u", Ni 80-200u"
Au 1-50u", Ni 80-200u"
8. Strictly follow IPC standards to ensure the quality of shipments, and implement quality PDCA cycle process to continuously improve product performance.
9. Fast delivery time wins you the market advantage: samples can be delivered within 3 days, and the first batch of mass production can be delivered within 5 days.
10. PCBONLINE has its own SMT factory, you can also do the flex circuit assembly here after you finish the flexible pcb. To experience the best one-stop flexible PCB service here.

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