Die-cutting auxiliary materials commonly used in the FPC circuit board production process
Flexible PCB manufacturing process is complicated. From the drilling of the material to the packaging and shipping, there are more than 20 manufacturing processes in the middle.
In this long production process, various auxiliary materials will be used according to customer needs. The substrate of the 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 in the installation and adaptation of the environment. There are mainly the following:
1. FR4-hard texture, different thickness of 0.15-2.0mm, mainly used on the reverse side of FPC welding, as reinforcement, convenient and reliable welding;
FR-4 is a code name for a flame-resistant material grade. It means a material specification that the resin material must be self-extinguishing after being burned. It is not a material name, but a material grade, so the current general circuit There are many types of FR-4 grades used in the board, but most of them are made of so-called Tera-Function epoxy plus filler and fiberglass. Composite material.
2, PI tape – soft texture, can be bent, mainly used in the thickening of the gold finger area to strengthen, easy to plug;
PI tape, the full name is polyimide tape. The PI tape is based on a polyimide film, imported silicone pressure-sensitive adhesive, with high-temperature resistance, acid and alkali resistance, solvent resistance, electrical insulation (H grade), radiation protection and other properties. Applicable to electronic circuit board wave solder masking, protection of gold fingers and high-grade electrical insulation, motor insulation, and lithium battery positive and negative ear fixation.
3, steel sheet – hard texture, the same function as FR4, used for welding reinforcement, more beautiful than FR4, grounding, hardness is higher than FR4;
The steel sheet is made of imported stainless steel by heat treatment and has the characteristics of high precision, strong pulling force, good finish, toughness and not easy to break.
4, TPX resist film – a high-performance high-temperature resistant resin barrier release film, used in the circuit board pressing process, through special process design, can be used to block multiple layers of buried holes and blind vias after resin overflow In the pressing process, it has a good anti-blocking and plugging effect.
5, EIM electromagnetic film – attached to the surface of the FPC, used to shield signal interference;
The EIM electromagnetic film is a vacuum sputtering method that can coat shielding materials on different substrates (PET/PC/glass, etc.) to achieve EMI electromagnetic interference shielding with extremely low resistance.
6, conductive adhesive – used for the connection of steel sheet and FPC, conductive, can achieve the grounding function of the steel sheet;
A conductive paste is an adhesive that has a certain conductivity after curing or drying. It is mainly composed of a resin matrix, conductive particles, dispersing additives, additives, and the like. It can connect a variety of conductive materials together to form an electrical path between the materials being joined. In the electronics industry, conductive adhesives have become an indispensable new material.
7, 3M adhesive tape – mainly used for FR4 and FPC paste of 0.4mm and above thickness, and FPC and customer products are assembled and fixed;
The use of FPC auxiliary materials in the flexible PCB manufacturing process is ultimately determined by the customer’s environment and functional requirements.