Preface: Recently, many friends have asked us about the knowledge of flexible circuit boards. Here, we will once again introduce it to everyone

FPCbrief introduction

FPC: Full English spellingFlexible Printed CircuitIts Chinese meaning is flexible printed circuit board, abbreviated as flexible board. It is made by using optical imaging pattern transfer and etching processes on a flexible substrate surface to create conductor circuit patterns. The surface and inner layers of double-sided and multi-layer circuit boards are electrically connected through metalized holes, and the surface of the circuit pattern isPIProtect and insulate with adhesive layer.

Mainly divided intoSingle panelTheDouble sided boardTheMulti-layer boardTheSoft hard combination board.

Characteristics of flexible circuit boards

⒈Short: Short assembly time

All lines have been configured, eliminating the need for extra wiring connections;

⒉Small: Volume ratioPCB(Hardboard) Small size can effectively reduce product volume and increase portability;

⒊Light: Weight ratioPCBLightweight (hard board) can reduce the weight of the final product;

4. Thin: thickness ratioPCBThin (hard board) can improve flexibility and strengthen the assembly of three-dimensional space within a limited space.

 

Advantages of flexible circuit boards

Flexible printed circuit board is a printed circuit made of flexible insulating substrate, which has many advantages that hard printed circuit boards do not have:

1. It can be freely bent, wound, and folded, arranged according to spatial layout requirements, and can move and expand freely in three-dimensional space, thus achieving the integration of component assembly and wire connection;

2. utilizeFPCIt can greatly reduce the volume and weight of electronic products, meeting the needs of electronic product development towards high density, miniaturization, and high reliability. Therefore,FPCIn aerospace, military, mobile communications, laptops, computer peripheralsPDAIt has been widely used in fields or products such as digital cameras;

3. FPCIt also has good heat dissipation and weldability, as well as advantages such as easy installation and low overall cost. The soft hard combination design also partially compensates for the slight deficiency of flexible substrates in component load-bearing capacity

FPCMain raw materials

Its main raw materials are:1, substrate,2Cover film, 3Strengthening, 4Other auxiliary materials.

1base material            

1.1 Adhesive substrate

1.2 The adhesive substrate mainly consists of three parts: copper foil, adhesive, andPIThere are two types of substrates: single-sided substrates and double-sided substrates. Materials with only one copper foil are single-sided substrates, while materials with two copper foils are double-sided substrates.

1.2 Adhesiveless FCCL

Non adhesive substrate refers to a substrate without an adhesive layer. Compared to ordinary adhesive substrates, it lacks an intermediate adhesive layer and only has copper foil andPIComposed of two parts, it has the advantages of thinner, better dimensional stability, higher heat resistance, higher bending resistance, and better chemical resistance compared to adhesive substrates, and is now widely used.

Copper foil: Currently, commonly used copper foil thicknesses have the following specifications:,1OZThe1/2OZThe1/3OZNow launched1/4OZThinner copper foil with thicker thickness, but this material is currently being used in China to make ultra-fine roads (with a line width and spacing of)0.05MMAnd below) products. With the increasing demands of customers, this specification of material will be widely used in the future.

2. Cover film

It mainly consists of three parts: release paper, adhesive, andPIUltimately, only glue, andPITwo parts, the release paper will be torn off during the production process and will no longer be used (its function is to protect foreign objects on the adhesive).

3. Strengthening

byFPCSpecific materials are used in a specific part of the product to increase support strength and make up for itFPCrelatively“soft”The characteristics.

There are currently several commonly used reinforcement materials:

1）FR4Reinforcement: The main components are glass fiber cloth and epoxy resin adhesivePCBUsedFR4Same material;

2）Steel sheet reinforcement: composed of steel, with strong hardness and support strength;

3）PIReinforcement: Same as the covering film, there arePIIt consists of three parts: adhesive release paper, butPIThicker layers, from2MILreach9MILBoth can be produced in proportion. 

4. Other auxiliary materials

1）Pure adhesive: This adhesive film is a thermosetting acrylic adhesive film with protective paper/A release film and a layer of adhesive are mainly used for laminated boards, soft hard bonding boards, andFR-4/Steel sheet reinforcement plate plays a bonding role.

2）Electromagnetic protective film: pasted on the board surface to provide shielding effect.

3）Pure copper foil: composed only of copper foil, mainly used in the production of hollow boards.

5. FPCtechnological process