ALLPCB
Overview
Demand for flexible printed circuits (FPCs) has grown sharply with the rise of wearable devices, flexible displays, and smart devices. Under industry trends toward thinner, lighter, and more compact electronics, ultra-thin and stretchable FPCs offer significant opportunities and drive related equipment development.
An FPC is typically made from a polyimide or polyester film substrate and provides high reliability and excellent flexibility. FPCs offer high routing density, light weight, low thickness, and good bendability. Using FPCs can significantly reduce product size, meeting the needs of higher density, miniaturization, and higher reliability. FPCs are widely used in aerospace, mobile communications, laptop computers, computer peripherals, PDAs, and digital cameras.
FPC production involves many processes. From material cutting and drilling to final packaging, there are more than 20 steps, and various auxiliary materials are used depending on customer requirements. The FPC base material is generally single- or double-sided copper foil, which determines the electrical properties of the FPC. Other auxiliary materials are used to assist assembly and to adapt to operating environments. Common non-metal die-cutting auxiliary materials include the following.
Common non-metal die-cutting auxiliary materials
FR-4 grade materials
FR-4 grade materials are available in thicknesses from 0.15 to 2.0 mm and in various compositions. They are mainly used on the reverse side of FPC soldering areas to reinforce board toughness and to facilitate soldering. FR-4 denotes a flame retardant material grade: the resin formulation must be self-extinguishing under burning conditions.
Polyimide (PI) tape
Polyimide tape is a soft, flexible tape primarily used to reinforce and thicken gold finger regions to ease insertion and removal. PI tape is made from polyimide film with a silicone pressure-sensitive adhesive. It offers high and low temperature resistance, acid and alkali resistance, solvent resistance, electrical insulation up to class H, and radiation resistance. Typical applications include wave solder masking for electronic circuit boards, protection of gold fingers, high-grade electrical insulation, motor insulation, and fixation of positive and negative tabs on lithium batteries.
TPX resist film
TPX resist film is a high-performance, high-temperature resistant release film used in board lamination. With specialized process design, it is used to block resin overflow during lamination and to prevent resin from filling plated through holes and blind vias during multiple lamination steps, providing effective resist and via-filling control.
EMI shielding film
EMI shielding film is produced by vacuum sputtering shielding materials onto various substrates such as PET, PC, or glass. It is typically applied to the FPC surface to provide electromagnetic interference shielding with very low electrical resistance.
Conductive adhesive
Conductive adhesive is commonly used to bond and laminate steel plates to FPCs and to provide grounding. It is an adhesive that becomes electrically conductive after curing or drying, typically composed of a resin matrix, conductive particles, dispersants, and additives. Conductive adhesives form electrical pathways between joined conductive materials and are widely used in electronics manufacturing.
