Flexible PCB Manufacturing Services

High precision, high difficulty FPC flexible circuit board production services.

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If you need a manufacturer who can manufacture flexible PCB for you, you should make it clear that this PCB Manufacturer should have a mature and current process flow for manufacturing flexible circuit board. Considering factors such as manufacturing cost, we suggest that you choose a Chinese PCB manufacturer. Because, at present, PCB Manufacturing industry is basically concentrated in China. It is not only because China’s manufacturing industry is very developed, but also because it has a very mature production process and can effectively reduce the cost of manufacturing products for you. To visit our factory, please click here.

What is Flexible PCB Circuit Board ?

Flexible PCB Definition, and For a new product to be better applied, we need to understand exactly what it means and everything about it.

Flexible PCB, also known as Flexible electronics, flexible circuit board, Flex PCB , flex circuits, is a technology for assembling electronic circuits by mounting electronic devices on flexible plastic substrates, such as polyimide, PEEK or transparent conductive polyester film. Additionally, flex circuits can be screen printed silver circuits on polyester. Flexible electronic assemblies may be manufactured using identical components used for rigid Printed Circuit Boards, allowing the board to conform to a desired shape, or to flex during its use. An alternative approach to flexible electronics suggests various etching techniques to thin down the traditional silicon substrate to few tens of micrometers to gain reasonable flexibility, referred to as flexible silicon (~ 5 mm bending radius). Our previous customer’s testimonies will be the best proof.

Flexible circuit boards are widely used in automobiles, medical, telecommunications, industry or commerce.

What are Advantages of Flexible PCB ?

Custom flexible PCBs are becoming more and more popular, we need to understand the benefits of using flexible PCBs.

Flexible PCB is essentially different from Rigid PCB . Although rigid PCB is currently the most produced PCB in the world, the use of flexible PCB has many advantages, including:

Save space and weight.

Flexible PCB design requires only about 10% of the space and weight of common PCB components to provide greater freedom of installation and packaging. The inherent flexibility also allows for more compact flexibility. Because of its lighter weight, it also reduces transportation costs.

Increased stability and reliability

A Flexible Printed Circuit Board requires fewer interconnects, which in turn requires fewer contact crimps, connectors and solder joints. Simply put, a flexible PCB Board does not contain as many potential sources for failure, which enhances their reliability.

Compatibility and performance

Flexible Printed Circuit boards can be compatible with almost any type of connectors or components, and can be used with ZIP connectors and other components, so the compatibility of flexible printed circuit boards is incomparable with other PCBs. They also perform well at extreme temperatures and exhibit excellent radiation and chemical resistance.

Effective Cost Control.

Cost-saving advantages of flexible PCB include reducing material and packaging requirements, reducing component replacement costs and possibly leading to assembly errors requiring maintenance.

And Other Features

  • Reduced wiring errors
  • Elimination of
  • mechanical connectors
  • Unparalleled design
  • flexibility
  • Higher circuit density
  • More robust operating
  • temperature range
  • Stronger signal quality
  • Improved reliability and impedance control

These benefits make flex PCBs ideally fit for a wide range of applications in industries such as Military, Transportation, Medical, Consumer Electronics, Automotive, Aerospace, Communications and Industrial.

Flexible PCB Applications

The application of flexible PCB is extensive; see if it is applied in your products and industry?

  • Flexible Circuits are usually used as connectors in various applications, because they have incomparable flexibility, save space and are easier to maintain than rigid circuit boards in the later period. Flexible circuits are commonly used in computer keyboards; most keyboards use flexible circuits as switching matrices.
  • Glass is used as a substrate in LCD manufacturing. If a thin flexible plastic or metal foil is used as the substrate, the whole system can be flexible, because the film deposited on the top of the substrate is usually very thin, about a few microns.
  • Organic light-emitting diodes (OLED) are usually used instead of backlights for flexible displays, thus making flexible organic light-emitting diode displays.
  • Most flexible circuits are passive wiring structures that are used to interconnect electronic components such as integrated circuits, resistors, capacitors and the like; however, some are used only for making interconnections between other electronic assemblies either directly or by means of connectors.
  • In the automotive field, flexible circuit boards are used for dashboards, under-hood control devices, circuits hidden in cab roofs, and ABS systems. In computer peripherals, a flexible PCB is used on the printer’s mobile print head and the signal is connected to the mobile arm carrying the read/write head of the disk drive. Consumer electronic devices use flexible circuits in cameras, personal entertainment devices, calculators or motion monitors.
  • Flexible circuits are found in industrial and medical devices where many interconnections are required in a compact package. Cellular telephones are another widespread example of flexible circuits.
  • Flexible solar cells have been developed for powering satellites. These cells are lightweight, can be rolled up for launch, and are easily deployable, making them a good match for the application. They can also be sewn into backpacks or outerwear.

Types of Flexible PCB Circuit Boards

There are a few basic constructions of flexible circuits but there is significant variation between the different types in terms of their construction. Following is a review of the most common types of flexible circuit constructions.

Whether you need single-sided flexible circuit boards or double-sided multilayer flexible PCB, or custom manufacturing services for rigid-flexible PCBs, as long as you send the Gerber file to sales@pcbjhy.com, we can do it. Please note that we are unique.

Single Sided Flexible PCB

Single sided Flexible PCB

Single-sided flexible circuits have a single conductor layer made of either a metal or conductive (metal filled) polymer on a flexible dielectric film. Component termination features are accessible only from one side. Holes may be formed in the base film to allow component leads to pass through for interconnection, normally by soldering. Single sided flex circuits can be fabricated with or without such protective coatings as cover layers or cover coats, however the use of a protective coating over circuits is the most common practice. The development of surface mounted devices on sputtered conductive films has enabled the production of transparent LED Films, which is used in LED Glass but also in flexible automotive lighting composites.

Multilayer Flexible PCB

Flex circuits having three or more layers of conductors are known as multilayer flex circuits. Commonly the layers are interconnected by means of plated through holes, though this is not a requirement of the definition for it is possible to provide openings to access lower circuit level features. The layers of the multilayer flex circuit may or may not be continuously laminated together throughout the construction with the obvious exception of the areas occupied by plated through-holes. The practice of discontinuous lamination is common in cases where maximum flexibility is required. This is accomplished by leaving unbonded the areas where flexing or bending is to occur.

Double access or back bared Flexible PCB

Double access or back bared Flexible PCB

Double access flex, also known as back bared flex, are flexible circuits having a single conductor layer but which is processed so as to allow access to selected features of the conductor pattern from both sides. While this type of circuit has certain benefits, the specialized processing requirements for accessing the features limits its use.

Polymer thick film flexible PCB

Polymer Thick Film Flexible PCB

Polymer thick film (PTF) flex circuits are true printed circuits in that the conductors are actually printed onto a polymer base film. They are typically single conductor layer structures, however two or more metal layers can be printed sequentially with insulating layers printed between printed conductor layers, or on both sides. While lower in conductor conductivity and thus not suitable for all applications, PTF circuits have successfully served in a wide range of low-power applications at slightly higher voltages. Keyboards are a common application, however, there are a wide range of potential applications for this cost-effective approach to flex circuit manufacture.

Sculptured Flexible PCB

Sculptured Flexible PCB

Sculptured flex circuits are a novel subset of normal flexible circuit structures. The manufacturing process involves a special flex circuit multi-step etching method which yields a flexible circuit having finished copper conductors wherein the thickness of the conductor differs at various places along their length. (i.e., the conductors are thin in flexible areas and thick at interconnection points.).

Rigid-flexible PCB

Rigid-flex PCB

Rigid-flex PCB circuits are a hybrid construction flex circuit consisting of rigid and flexible substrates which are laminated together into a single structure. Rigid-flex circuits should not be confused with rigidized flex constructions, which are simply flex circuits to which a stiffener is attached to support the weight of the electronic components locally. A rigidized or stiffened flex circuit can have one or more conductor layers. Thus while the two terms may sound similar, they represent products that are quite different.

The layers of a rigid flex are also normally electrically interconnected by means of plated through holes. Over the years, rigid-flex circuits have enjoyed tremendous popularity among military product designer, however the technology has found increased use in commercial products. While often considered a specialty product for low volume applications because of the challenges, an impressive effort to use the technology was made by Compaq computer in the production of boards for a laptop computer in the 1990s. While the computer's main rigid-flex PCBA did not flex during use, subsequent designs by Compaq utilized rigid-flex circuits for the hinged display cable, passing 10s of 1000s of flexures during testing. By 2013, the use of rigid-flex circuits in consumer laptop computers is now common.

Rigid flex PCB board are normally multilayer structures; however, two metal layer constructions are sometimes used.

Double Sided Flexible PCB

Double sided Flexible PCB

Double-sided flex circuits are flex circuits having two conductor layers. These flex circuits can be fabricated with or without plated through holes, though the plated through hole variation is much more common. When constructed without plated through holes and connection features are accessed from one side only, the circuit is defined as a "Type V (5)" according to military specifications. It is not a common practice but it is an option. Because of the plated through hole, terminations for electronic components are provided for on both sides of the circuit, thus allowing components to be placed on either side. Depending on design requirements, double-sided flex circuits can be fabricated with protective coverlayers on one, both or neither side of the completed circuit but are most commonly produced with the protective layer on both sides. One major advantage of this type of substrate is that it allows crossover connections to be made very easy. Many single sided circuits are built on a double sided substrate just because they have one of two crossover connections. An example of this use is the circuit connecting a mousepad to the motherboard of a laptop. All connections on that circuit are located on only one side of the substrate, except a very small crossover connection which uses the second side of the substrate.

Typical Flexible Circuit Board Structure Diagram

I hope that the schematic diagram of the flexible circuit board structure we have listed can help you with your flexible circuit design.

Single Sided Flex Circuit with Dual Access

Single Sided Flex Circuit with Dual Access

The basic stack-up of a double sided circuit with a PSA based stiffener

The Basic Stack-up of a Double-sided Circuit With a PSA Based Stiffener

Layering or stack-up of a single sided flex circuit

Layering or Stack-up of a Single-Sided Flex Circuit

double-sided flexible circuit board construction

Double-sided Flexible Circuit Board Construction

Example Stack-up of a 4 Layer Flex Circuit

Flex Circuit Overlay - A Special Process For Flexible PCB Fabrication

Flex circuit overlay, or coverlay, as it’s also known, is a lamination process used for encapsulating and protecting the external circuitry of a flex circuit. A flex circuit’s coverlay film is similar to a rigid PCB’s solder mask, with one big difference…the coverlay film is flexible! “The coverlay film is generally a polyimide film that is coated with a thermoset adhesive. Film thicknesses range from .0005” to .005” with .001” and .002” the most common.”

The polyimide and adhesive coverlay is laminated using pressure and heat, where the heat helps the adhesive to easily flow and fill in any gaps between traces and pads; this prevents the trapping of air between the layers. “The adhesive flowing is necessary as it helps assure complete surface contact and encapsulation. The adhesive will tend to ooze out slightly around the openings shown in the diagram below. This oozing is commonly referred to as ‘adhesive squeeze out’ and is actually a desired phenomenon.”

Once the coverlay lamination process is finished, any component and/or feature openings are made using drilling, routing, or laser cutting. Etching cannot be used.

Flex circuit with coverlay
Flex circuit coverlay adhesive squeeze out

Image and part of the quoted content courtesy of Allflexinc.com.

Flexible PCB materials - Materials for Flex PCB Fabrication

Each element of the flex circuit construction must be able to consistently meet the demands placed upon it for the life of the product. In addition, the material must work reliably in concert with the other elements of the flexible circuit construction to assure ease of manufacture and reliability. Following are brief descriptions of the basic elements of flex circuit construction and their functions.

Base material

The base material is the flexible polymer film which provides the foundation for the laminate. Under normal circumstances, the flex circuit base material provides most primary physical and electrical properties of the flexible circuit. In the case of adhesiveless circuit constructions, the base material provides all of the characteristic properties. While a wide range of thickness is possible, most flexible films are provided in a narrow range of relatively thin dimension from 12 µm to 125 µm (1/2 mil to 5 mils) but thinner and thicker material are possible. Thinner materials are of course more flexible and for most material, stiffness increase is proportional to the cube of thickness. Thus for example, means that if the thickness is doubled, the material becomes eight times stiffer and will only deflect 1/8 as much under the same load. There are a number of different materials used as base films including: polyester (PET), polyimide (PI), polyethylene naphthalate (PEN), polyetherimide (PEI), along with various fluropolymers (FEP) and copolymers. Polyimide films are most prevalent owing to their blend of advantageous electrical, mechanical, chemical and thermal properties.

Bonding adhesive

Adhesives are used as the bonding medium for creating a laminate. When it comes to temperature resistance, the adhesive is typically the performance limiting element of a laminate especially when polyimide is the base material. Because of the earlier difficulties associated with polyimide adhesives, many polyimide flex circuits presently employ adhesive systems of different polymer families. However some newer thermoplastic polyimide adhesives are making important in-roads. As with the base films, adhesives come in different thickness. Thickness selection is typically a function of the application. For example, different adhesive thickness is commonly used in the creation of cover layers in order to meet the fill demands of different copper foil thickness which may be encountered.

Metal foil

A metal foil is most commonly used as the conductive element of a flexible laminate. The metal foil is the material from which the circuit paths are normally etched. A wide variety of metal foils of varying thickness are available from which to choose and create a flex circuit, however copper foils, serve the vast majority of all flexible circuit applications. Copper's excellent balance of cost and physical and electrical performance attributes make it an excellent choice. There are actually many different types of copper foil. The IPC identifies eight different types of copper foil for printed circuits divided into two much broader categories, electrodeposited and wrought, each having four sub-types.) As a result, there are a number of different types of copper foil available for flex circuit applications to serve the varied purposes of different end products. With most copper foil, a thin surface treatment is commonly applied to one side of the foil to improve its adhesion to the base film. Copper foils are of two basic types: wrought (rolled) and electrodeposited and their properties are quite different. Rolled and annealed foils are the most common choice, however thinner films which are electroplated are becoming increasingly popular.

In certain non standard cases, the circuit manufacturer may be called upon to create a specialty laminate by using a specified alternative metal foil, such as a special copper alloy or other metal foil in the construction. This is accomplished by laminating the foil to a base film with or without an adhesive depending on the nature and properties of the base film.

Learn more PCB materials.

JHYPCB: A Leading Flexible PCB Manufacturer from China

At JHYPCB, we specialize in the fabrication and assembly of flexible PCB products for use in the manufacturing of medical devices and various types of telecommunication and industrial equipment. Our Custom PCB manufacturing capabilities allow us to develop and produce a top-performing flex PCB that meets your unique requirements. We can also work with you to build a custom flex PCB Prototype that will significantly improve your prospects of a successful project outcome. Our previous customer’s testimonies will be the best proof.

For our full flexible PCB fabrication capabilities, please click here.

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FAQ

Most frequent questions and answers

Yes, we make single, double, and multi-layer Flex and Rigid-Flex PCBs.

We make different types of Flex and Rigid-Flex PCBs, depending on the structure, base material, adhesive, appearance, insulation base film, and metal conductor foil. Please consult our technical team for details suitable for your application.

Yes, we provide black PI stiffeners, yellow PI cover films, transparent polyimide films, white overlay, and brown PI copper clad laminates.

Yes. We have four manufacturing methods for adhesive-free copper foil base materials. We use spray plating, curtain coating, electroless deposition/electrolytic plating, and laminating.

Minimum thickness is 2 µm and the maximum is 200 µm. We ensure high chemical durability and processing compatibility for flexible printed circuits and do not sacrifice its original electrical property, heat-resistant property, and mechanical property.

IPC Standards for Rigid and Flexible PCBs

The list of IPC standards below applies to rigid PCBs and flex circuits. Take note that this list is not exhaustive, and additional IPC standards may need to be considered. You should consult the ipc.org website for a full list of available IPC standards.

  • IPC-2221A, Generic Standard on Printed Board Design
  • IPC-2223, Sectional Design Standard for Flexible Printed Boards
  • IPC-4101, Specification for Base Materials for Rigid and Multilayer Printed Boards
  • IPC-4202, Flexible Base Dielectrics for Use in Flexible Printed Circuitry
  • IPC-4203, Adhesive Coated Dielectric Films for Use as Cover Sheets for Flexible Printed Circuitry and Flexible Adhesive Bonding Films
  • IPC-4204, Flexible Metal-Clad Dielectrics for Use in Fabrication of Flexible Printed CircuitryIPC-6013, Qualification and Performance Specification for Flexible Printed Wiring
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