Do you know the die-cutting auxiliary materials commonly used in the production of FPC circuit boards?

FPC circuit board is also called flexible circuit board, referred to as "soft board", commonly known as FPC in the industry, is a flexible insulating substrate The printed circuit board (mainly polyimide or polyester film) has many advantages that rigid printed circuit boards do not have. For example, it can be bent, rolled and folded freely, and the use of FPC can greatly reduce the volume of electronic products , It is suitable for the needs of electronic products to develop in the direction of high density, miniaturization and high reliability. Therefore, FPC has been widely used in aerospace, military, mobile communications, laptop computers, computer peripherals, PDA, digital cameras and other fields or products. .

The production process of FPC is complicated. From cutting and drilling to packaging and shipping, there are more than 20 processes required in the middle. In this long production process, a variety of auxiliary materials will be used according to customer needs. The base material of FPC is generally double-sided or single-sided copper foil, which is the basis of the entire FPC, and the electrical properties of the FPC are determined by it. Other auxiliary materials are only used to assist installation and adapt to the use environment. There are mainly the following types:

1. FR4- has a hard texture, with different thicknesses of 0.15-2.0mm, mainly used on the reverse side of FPC welding, As a reinforcement, it is convenient for welding to be stable and reliable;
FR-4 is the code name of a fire-resistant material grade, which means that the resin material must be able to extinguish itself after burning. It is not a material name, but a material grade. Therefore, there are many types of FR-4 grade materials used in general circuit boards, but most of them are based on the so-called four-function (Tera -Function) epoxy resin plus filler (Filler) and a composite material made of glass fiber.

2. PI tape - soft texture, bendable, mainly used for thickening and strengthening the golden finger area, easy to plug and unplug ;
PI tape, the full name is polyimide tape. PI tape is based on polyimide film and adopts imported silicone pressure-sensitive adhesive, which has the properties of high and low temperature resistance, acid and alkali resistance, solvent resistance, electrical insulation (class H), and radiation protection. It is suitable for wave solder shielding of electronic circuit boards, protection of golden fingers and high-grade electrical insulation, motor insulation, and fixing of positive and negative terminals of lithium batteries.

3. Steel sheet - hard texture, the same function as FR4, used for welding reinforcement, more beautiful than FR4, can be grounded , the hardness is higher than FR4;

Steel sheet, made of imported stainless steel by heat treatment and fine grinding, with high precision, strong tensile strength and smooth finish Good, tough and not easy to break.

4. TPX adhesive film - a high-performance high temperature resistant resin barrier release film for circuit board lamination The process, through special process design, can be used for multiple lamination processes of buried holes and blind vias after resin overflow, and has good glue blocking and hole plugging effects.

5. EIM electromagnetic film - attached to the surface of FPC to shield signal interference;

EIM electromagnetic film is a method of vacuum sputtering, which can be used on different substrates (PET/PC/glass, etc. ) Shielding material is plated on the substrate to achieve EMI electromagnetic interference shielding with extremely low resistance.

6. Conductive adhesive - used for the connection and pressing of the steel sheet and the FPC, conductive, and can realize the grounding function of the steel sheet;< /span>
Conductive adhesive is an adhesive that has some electrical conductivity after curing or drying. It is mainly composed of resin matrix, conductive particles, dispersing additives, auxiliaries, etc. It can connect a variety of conductive materials together to form an electrical path between the connected materials. In the electronics industry, conductive adhesive has become an indispensable new material.

7. 3M tape - mainly used for FR4 and FPC with thickness of 0.4mm and above, as well as FPC and customer products Assemble and fix;
The use of FPC auxiliary materials is ultimately determined according to the customer's use environment and functional requirements.