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Application Of FPC In Membrane Switch



Application of FPC in Membrane Switch

Early FPC was mainly used in the area of connection between small or thin electronic products and rigid printed boards. The late 1970s

Is gradually applied to computers, digital cameras, inkjet printers, car stereos, optical disc drives, and hard disk drives, etc.

In the product. Open a 35mm camera with 9 to 14 different flex circuits inside. The only way to reduce the volume is to

Smaller, more precise lines, tighter pitches, and bendable objects. Pacemakers, medical equipment, video cameras, hearing aids

, laptops - there are flexible circuits in almost everything used today.

        Flexible circuits provide excellent electrical performance. Lower dielectric constant allows fast transmission of electrical signals; good thermal performance makes assembly easy

Cooling; higher glass transition temperature or melting point allows the module to perform well at higher temperatures. Flexible circuit can meet smaller size

Design requirements for higher-density mounting also help reduce assembly processes and increase reliability. It is to meet the miniaturization and migration of electronic products

The only solution to a move request.

        Introduction to Main Features of Flexible Circuit Board (FPC)

        1. Flexible Circuit Flexibility and Reliability FPC can flex freely, coil, fold, and withstand millions of dynamics

Bending without damaging the wire can be arbitrarily arranged according to the requirements of the space layout, and can be freely moved and retracted in the three-dimensional space so as to reach the yuan

The integration of device assembly and wire connection; FPC can greatly reduce the size and weight of electronic products for electronic products to high-density,

The need for miniaturization and high reliability in the direction of development. So in aerospace, military, mobile communications, laptops, computer peripherals, PDAs,

Digital cameras and other fields are widely used.

 Current flexible circuits include: single-sided, double-sided, multi-layer flexible boards, and rigid flexible boards.

 1 Single-sided flexible board is the lowest cost printed board when the electrical performance is not high. For single-sided wiring, single-sided flexing should be used

Sex board. It has a layer of a chemically etched conductive pattern, and the conductive pattern layer on the surface of the flexible insulating substrate is a rolled copper foil.

2 double-sided flexible board is a conductive pattern made by etching on both sides of the insulating base film. Metallized hole will be two sides of insulating material

The graphical connections form conductive pathways to meet flexural design and usage features. The cover film protects single and double conductors

Indicates where the component is placed.

  3 multi-layer flexible boards laminate three or more single-sided or double-sided flexible circuits together to form metal by drilling and electroplating

Holes form conductive paths between different layers. This eliminates the need for complex welding processes. Multilayer circuits are more reliable and better

There is a huge functional difference in thermal conductivity and more convenient assembly performance. When designing the layout, you should consider the size of the assembly,

Layers and flexibility interact.

  4 Conventional rigid-flex panels consist of rigid and flexible substrates that are selectively laminated together. Closely structured to metallized holes

Conductive connections are formed. If there is a component on the front and back of a printed board, a rigid flexible board is a good choice. But if all

If the components are all on one side, it is more economical to use a double-sided flexible board and laminate a layer of FR4 reinforcement on the back.

  5 The flexible circuit of the hybrid structure is a multilayer board, and the conductive layer is composed of different metals. One 8-layer board uses FR-4 as the inner layer

The medium, using polyimide as the outer layer medium, extends the leads from three different directions of the main board, each wire is made of different gold

Made of. Constantan alloys, copper and gold are separate leads. This hybrid structure is mostly used for electrical signal conversion and heat conversion

The only feasible solution is the relationship and low temperature conditions where the electrical performance is severe.

         2. Economics of flexible circuits

  If the circuit design is relatively simple, the total volume is small, and the space is suitable, the traditional internal connection methods are mostly much cheaper. Such as

If the circuit is complex, many signals are processed or there are special electrical or mechanical performance requirements, the flexible circuit is a good design choice.

When the size and performance of applications exceed the capabilities of rigid circuits, flexible assembly is the most economical. Can be made inside a film

A 12mil pad with 5 mil vias and a 3mil line and pitch flex circuit. Therefore, it is more reliable to mount the chip directly on the film. because

It is free of flame retardant that may be a source of ion drilling pollution. These films may be protective and cure at higher temperatures, giving better results

High glass transition temperature. The reason for the cost savings of flexible materials over rigid materials is to eliminate connectors.

The high cost of raw materials is the main reason for the high price of flexible circuits. The price of raw materials varies greatly, the lowest cost polyester

The cost of raw materials for flexible circuits is 1.5 times that of raw materials for rigid circuits; high-performance polyimide flex circuits are up to

4 times or more. At the same time, the flexibility of the material makes it difficult to perform automated processing in the manufacturing process, resulting in a decrease in output;

Defects can easily occur during the final assembly process. These defects include the removal of flexible attachments and broken lines. Caused by bending or forming

Under high stress, it is often necessary to choose reinforcing materials or reinforcing materials. Despite the high cost of raw materials, manufacturing trouble, but folding, bendable

The curved and multi-layer puzzle function will reduce the size of the overall assembly, reduce the amount of materials used, and reduce the overall assembly cost.

 The flexible circuit industry is in a small but rapid development. Polymer thick film method is an efficient, low-cost production process.

The process selectively screens conductive polymer inks on inexpensive flexible substrates. A representative flexible substrate is PET. polymer

Thick-film conductors include screen-printed or carbon fillers. The polymer thick film method itself is very clean, using lead-free SMT adhesives,

No need to etch. Because of its use of additive process and low substrate cost, the polymer thick film process circuit is 1/1 of the price of copper polyimide thin film circuits.

10; is 1/2 to 1/3 of the rigid board price. The polymer thick film method is particularly suitable for the control panel of the device. On mobile phones and

In other portable products, the polymer thick film method is suitable for converting elements, switches and lighting devices on a printed circuit board into polymers

Thick film method circuit. This will not only save costs but also reduce energy consumption.

 In general, since the soft PCB is designed and manufactured for special applications, the initial circuit design, wiring, and photography

The cost of the bottom plate is higher. Unless there is a special need to use a soft PCB, it is usually best not to use it when it is used in small quantities. Flexible electricity

The road is more expensive than the rigid circuit and the cost is higher. Once the soft PCB is made, it must be changed from the base diagram or the programmed flash program

Start, so it is not easy to change. The surface is covered with a protective film, which needs to be removed before the repair and restored after the repair. This is difficult

work. When the flexible board is manufactured, many parameters are out of tolerance. But also by the size of the production equipment, the product is not

Can do long and wide. The difficulty in making flexible circuits lies in the material's resistance.

 In the next few years, smaller, more complex, and more costly assembly of flexible circuits will require newer methods of assembly and increase

Add a hybrid flex circuit. The challenge for the flexible circuit industry is to take advantage of its technology to keep up with computers, telecommunications, and consumption

Demand and active market synchronization. In addition, flexible circuits will play an important role in the lead-free action. Membrane switch circuit layer mining

With FPC, the circuit becomes highly precise, the minimum wiring distance can be done 0.5MM, the resistance value is extremely low, can weld LED, resistance, optical fiber and other small elements

Parts, reliable performance and long life, comparable to non-general silver paste flexible membrane switches.


Address: No. 2. Dadi Road, Haining Agricultural External Development Zone 314408,

Zhejiang, China

Contact Person: May Wong

Telephone: 86-571-86830690     Fax: 86-571-86687367

Cell Phone: 86-15158112598

Email: May@hzkaike.cn