The design method and type of flexible printed circuit board (PCB) are analyzed in detail

Flexible printed circuit board PCB Is a special type of circuit board , Can be bent to the desired application shape . Compared with ordinary rigid circuit board , This type of circuit board places conductive paths and electrical components on a flexible substrate . agile PCB Design is building modern compact electronic equipment （ Telephone 、 The camera 、 Hearing aids, etc ） There are many benefits . therefore , If you are a technician engaged in such projects , Here is an article about printed circuit boards PCB Design Method 、 Detailed analysis of type .

Rigidity and flexibility PCB

Although rigid and flexible PCB The purpose of is to connect electronic components in compact circuit design , But the two are different .

The main difference is the substrate material . flexible PCB It has a flexible substrate usually composed of polyimide film , The rigid type has a glass fiber substrate .

Due to bending , Manufacturers also use flexible rolled annealed copper instead of rigid electrodeposited copper to make conductive layers .

Flexible circuit board with white connector

When making these parts , flexible PCB The exposed circuit will be protected by covering process , The rigid type uses solder resist . The former is also more expensive , But the overall product cost may be cheaper , Because you can reduce the size of the equipment you plan to manufacture .

Rigid circuit board for computer

that , Which is better ？

It depends on the application . flexible PCB Ideal for compact electronic equipment and appliances , For example, telephone 、 Hearing aids and wearable devices . however , Rigid plate is more suitable for equipment with large space , For example, computers and television .

You can combine the two to form a rigid flexible combination plate , Half of the rigid plate design , The rest are in flexible circuits .

Rigid flexible combination plate

Make a combination of rigidity and softness PCB Methods

Basic rigidity PCB In the design phase, only Gerber File layer . However , Rigid flexible bonding plate 3D Design software before manufacturing 3D Create slab in space .

They have more sizes , The transition point from flexible to rigid needs to be precisely defined , therefore 3D Design is essential .

The base film on the flexible side is polyimide , It is covered with copper foil and holding film . however , Rigidity PCB With FR4 As substrate .

The first step is to apply accessible glue on the copper layer during assembly . after , You can use copper plating method or covering process for the next stage .

After completion , Drill holes on flexible substrates using accurate laser penetration methods .

Next , Use a through-hole plating process （ Synthetic copper electroplating ） Fill these holes with copper .

A kind of PCB Copper plating machine

source ： Wikishare resources   

The next steps include applying photosensitive engraving to the flexible surface , Then carve the copper film . After these two processes , The drawing object is expelled from the circuit board .

Next , Put the covering layer （ Usually polyimide ） Applied to the top and bottom layers of flexible substrates .

After that , The circuit board goes through the blanking process , Cut the substrate to the required size . The most commonly used blanking procedure is hydraulic punch or kick bucket group .

Last , The cut flexible blank is covered between the rigid layers . The last piece can be tested later , To make sure it works .

flexible PCB The advantages of

• Save space and weight .

Flexible printed circuit board . Notice how it takes up less space when folded or rolled up .

• Improve stability and reliability

• Connectors and harnesses are not required , And minimize wiring errors

• They can be stacked in various configurations

• High tensile strength and high radiation resistance 、 Chemicals and extreme temperatures

• durable （ Suitable for harsh environments ）

• Easy to install

• Provide strong signal quality

• Improve impedance control

flexible PCB The shortcomings of

• With rigidity in specific applications PCB comparison , It has a higher cost

• It uses a complex assembly process

• Difficult to repair or rework

• Appropriate storage conditions are required

• Improper handling is easy to damage

flexible PCB The type of

One side flexible

As the simplest type , Single sided flexible circuit in dielectric layer （ Polyimide or polymer film ） One side of the has a single conductive layer .

Double sided flexible

Double sided flexible PCB There is a conductive copper layer on each side of the dielectric material . Metallized through holes connect two copper edges .

Multilayer elasticity

This type includes a plurality of copper layers separated and encapsulated by a dielectric layer . Through hole , Connect each metal layer .

Rigid flexible combination circuit

As mentioned earlier , Combination of rigidity and softness PCB It is a multilayer circuit that combines rigid and flexible circuit boards , A hybrid design with high circuit density is formed .

HDI flexible PCB

High density interconnection (HDI) The circuit is an efficient and reliable circuit board with multiple electronic components . Due to the use of thin non-conductive substrate material , They provide better electrical performance in a smaller package size .

Carved flexible circuit

The engraved flexible circuit has circuit traces with different thickness in the whole circuit design . therefore , They may have different copper thicknesses in some areas . 

Polymer thick film flexibility PCB

Polymer thick film is a kind of reliable film produced by screen printing using template FPCB A simple and cost-effective way . You can find this in low voltage applications PCB, Because their function is not enough to deal with high voltage .

Two channels / Backplane flexible PCB

This is a special one-sided PCB, Its conductive track can be accessed from either side of the circuit board .

Two things make this possible . First , The metal layer is applied with a pre perforated dielectric film . secondly , The conductor layer is etched on the flexible film （ Dielectric ） Access point on （ Opening ） Proceed below .

agile PCB Design ： Typical schematics and laminations

flexible PCB It's made up of layers , But the number varies by type . These structural diagrams and laminations can help you build a .

Single layer flexible PCB

monolayer FPCB There is a simple stack , Including a flexible base course （ Usually polyimide ）, Then there is the adhesive layer , Then copper . A protective layer consisting of adhesive and polyimide （ overburden ） Covering metal . However , Conductive parts must not be exposed .

Two channels / Backplane FPCB

Like a single-layer circuit , This circuit has five layers , But there's a difference . The polyamide outer layer on the base has a laser opening , Access to copper circuits .

Double layer flexible board

The PCB Flexible laminates are used as the substrate , Separate the conductive layer . Each metal layer has a protective circuit covering layer and copper plated through holes on both sides of the connection .

Multi layer flexible PCB

Multilayer flexible circuit combines single-sided and double-sided flexible circuit design . In the internal , The middle part has a double-sided flexible circuit , The surface has a single-sided conductive design covered with a protective film .

Materials used in flexible circuits

The four main layers in the flexible plate can have the following materials .

conductor ：

The metal used in this layer is usually copper , Because it has excellent electrical performance and low cost . Heat dissipation is also a key factor to consider , Copper can do this quickly .

Flexible with copper conductive layer PCB

Other suitable conductor materials include stainless steel 、 Beryllium copper and white copper .

adhesive

The adhesive layer containing acrylic acid or epoxy resin is located between copper and insulating film （ polyimide ） Between . Acrylic adhesive material provides better heat resistance , But it has poor electrical properties and low adhesive strength .

On the other hand , The heat resistance of epoxy resin is not the best , But it has better electrical properties and viscosity .

Epoxy adhesive

source ： Wikishare resources   

Insulator

Insulators are also called substrates or dielectrics , It is a flexible material that gives the circuit board bending properties . Polyimide is the most commonly used material , But some plates have polyester 、 Polyetherimide 、 Various copolymers or fluoropolymers .

Finish

If the electrical conductor contacts the path , Exposed copper circuits may be electrocuted or shorted . The covering film usually composed of polyimide film keeps the copper sealed and protected .

With orange / Flexibility of gold polyimide film finish PCB

application

• High speed digital /RF/ Microwave connector

• Industrial sensor

• Instrument consumables

• Medical equipment - Wearable device

• automobile

• satellite

• Avionics

• consumer electronics

Flexible circuit board manufacturing IPC standard

 

 

Be smart and make ： Leading flexibility PCB Manufacturer

Quick wit is PCB Manufacturer , We have the ability to build any type of PCB The expertise required , Including flexibility PCB. We focus on multi-layer flexible and rigid flexible manufacturing , And provide... For these circuit boards SMT Assembly of components .

We assure you of the quality 、 Reliability and durability , This means that you can work at high temperatures 、 Worry free use of our products in high-density applications .

Besides , Our price is reasonable , Our flexibility is combined with rigidity and flexibility PCB The delivery times of are 5 - 6 Days and 3 - 14 God . Build times vary by design .

Generalization

All in all , flexible PCB Because of its bending characteristics, it is an ideal choice for building compact packaging and equipment . If your project needs this type of circuit , please Contact us For more details about flexible circuit boards , And get a free quotation for your design .