东莞市新盟自动设备有限公司
国内专业自动化设备制造商
自动化流水线/全自动点胶机/喷胶机/焊锡机/打镙丝机
7*24小时服务热线：
18664126708
FPC Soft Board发表时间：2024-01-11 17:04 Flexible Printed Circuit (FPC for short) is based onPolyimideorPolyester filmMade of a base material with high reliability and excellent flexibilityA printed circuit board. It has the characteristics of high wiring density, light weight, thin thickness and good bendability. Related star charts
Table of contentsFlexible Printed Circuit (FPC), also known asFlexible circuit board、flexible circuit board, which is popular for its excellent features such as light weight, thin thickness, and freedom of bending and folding... However, domestic quality inspection of FPC mainly relies on manual visual inspection, which is costly and inefficient. With the rapid development of the electronics industry, circuit board design is becoming more and more high-precision and high-density. Traditional manual inspection methods can no longer meet production needs, and automated FPC defect detection has become an inevitable trend in industry development. [1] Flexible circuit (FPC) is a technology developed in the United States in the 1970s to develop aerospace rocket technology.polyester filmorPolyimideA printed circuit with high reliability and excellent flexibility made of a base material. By embedding circuit design on a flexible and thin plastic sheet, a large number of precision components can be stacked in a narrow and limited space, thus Form a bendable flexible circuit. This kind of circuit can be bent and folded at will, is light in weight, small in size, has good heat dissipation, and is easy to install, breaking through the traditional interconnection technology. In the structure of flexible circuits, the materials are insulating films, conductors and adhesives. [2] 1. Insulating film The insulating film forms the base layer of the circuit, and the adhesive bonds the copper foil to the insulating layer. In a multi-layer design, it is bonded to the inner layer. They are also used as protective coverings to insulate circuits from dust and moisture and to reduce stress during flexing. The copper foil forms the conductive layer. In some flexible circuits, rigid components made of aluminum or stainless steel are used to provide dimensional stability, physical support for the placement of components and wires, and stress relief. Adhesives bond rigid components and flexible circuits together. There is another material that is sometimes used in flexible circuits, which is the adhesive layer, which is formed by coating both sides of the insulating film with adhesive. Bonding plies provide environmental protection and electrical insulation, as well as the ability to eliminate one layer of film and the ability to bond multiple layers with fewer bonding layers. insulationThin film materialThere are many types, but the most commonly used materials are polyimide and polyester. Used by nearly 80% of all flexible circuit manufacturers in the United Statespolyimide filmmaterials, another about 20% are usedPolyester filmMaterial. Polyimide material is non-flammable, geometrically stable, has high tear strength, and has the ability to withstand welding temperatures. Polyester, also known as polyethyleneterephthalate (abbreviated as PET) ), its physical properties are similar to polyimide, has a lower dielectric constant, absorbs very little moisture, but is not resistant to high temperatures. Polyesters have a melting point of 250°C and a glass transition temperature (Tg) of 80°C, which limits their use in applications requiring extensive end welding. In low-temperature applications, they exhibit rigidity. Nonetheless, they are suitable for use in products such as phones and other products that do not require exposure to harsh environments. Polyimide insulation films are usually combined with polyimide or acrylic adhesives, and polyester insulation materials are usually combined with polyester adhesives. The advantage of combining materials with the same properties is that they provide dimensional stability after dry welding or multiple lamination cycles. Other important properties in adhesives are low dielectric constant, high insulation resistance, high glass transition temperature and low moisture absorption. 2. Conductor Copper foil is suitable for use in flexible circuits. It can be made by electrodeposition (ED) or plating. One side of the electrodeposited copper foil has a shiny surface, while the processed surface on the other side is dull. It is a flexible material that can be made into many thicknesses and widths. The matte side of ED copper foil is often specially treated to improve its bonding ability. In addition to its flexibility, forged copper foil also has the characteristics of hardness and smoothness. It is suitable for applications requiring dynamic deflection. 3. Adhesive In addition to being used to bond insulating films to conductive materials, adhesives can also be used as cover layers, as protective coatings, and as cover coatings. The main difference between the two is the application method used, where the overlay is bonded to cover the insulating film in order to form a circuit in a laminated structure. Screen printing technology used for cover coating of adhesive. Not all laminate structures include adhesives, and laminates without adhesives create thinner circuits and greater flexibility. It has better thermal conductivity than adhesive-based laminate structures. Due to the thin structural characteristics of the adhesive-free flexible circuit and the elimination of the thermal resistance of the adhesive, thereby improving the thermal conductivity, it can be used in working environments where flexible circuits based on adhesive laminate structures cannot be used. . During the production process, in order to prevent too many short circuits that may cause low yield or reduce the scrapping and replenishment of FPC boards caused by rough process problems such as drilling, rolling, and cutting, and evaluate how to select materials to meet customer needs. of the best resultsFlexible circuit board, prenatal pretreatment is particularly important. There are three aspects that need to be dealt with in pre-production pre-treatment, and these three aspects are all completed by engineers. The first is the FPC board engineering evaluation, mainly to evaluate the customer'sFPC boardWhether it can be produced, and whether the company's production capacity can meet the customer's board making requirements and unit cost; if the project evaluation passes, then materials need to be prepared immediately to meet the supply of raw materials for each production link. Finally, the engineer will review: the customer's CAD structure drawing , gerber line data and other engineering documents are processed to suit the production environment and production specifications of the production equipment, and then the production drawings and MI (engineering process card) and other data are delegated to the production department and various departments such as document control and purchasing to enter regular production process. Cutting → Drilling → PTH → Electroplating → Pre-processing → Apply dry film → Alignment → Exposure → Development → Graphic plating → Release → Pre-processing → Apply dry film → Alignment exposure → Development → Etch → Release → Surface treatment → Apply covering film → Press → Curing → Nickel gold → Print characters → Cut → Electrical test → Die cutting → Final inspection → Packaging → Shipment Cutting → Drilling → Apply dry film → Alignment → Exposure → Develop → Etch → Release → Surface treatment → Apply cover film → Press → Curing → Surface treatment → Immersed nickel gold → Print characters → Cut → Electrical measurement → Punching Cut → Final inspection → Packaging → Shipping 1. Short: short assembly time All lines are configured, eliminating the need to connect redundant cables. 2. Small: smaller than PCB Can effectively reduce product volume and increase portability convenience 3. Light: lighter than PCB (hard board) Can reduce the weight of the final product 4. Thin: Thinner than PCB It can improve the softness and strengthen the three-dimensional assembly in a limited space. Copper foil substrate (Copper Film) Copper foil: basically divided into two types: electrolytic copper and rolled copper. The common thicknesses are 1oz 1/2oz and 1/3 oz Substrate film: Common thicknesses are 1mil and 1/2mil. Glue (adhesive): thickness is determined according to customer requirements. Cover Film Covering film protective film: used for surface insulation. Common thicknesses are 1mil and 1/2mil. Glue (adhesive): thickness is determined according to customer requirements. Release paper: prevent the adhesive from adhering to foreign matter before pressing; facilitates operation. Reinforcement board(PI Stiffener Film) Reinforcement board: Reinforces the mechanical strength of FPC to facilitate surface mounting operations. Common thicknesses range from 3mil to 9mil. Glue (adhesive): thickness is determined according to customer requirements. Release paper: prevent the adhesive from getting stuck on foreign matter before pressing. EMI: electromagnetic shielding film, which protects the circuits inside the circuit board from interference from the outside world (strong electromagnetic areas or areas susceptible to interference). Flexible printed circuit boards are printed circuits made of flexible insulating substrates and have many advantages that rigid printed circuit boards do not have: (1) It can be bent, rolled and folded freely, can be arranged arbitrarily according to the spatial layout requirements, and can be moved and stretched in three-dimensional space to achieve the integration of component assembly and wire connection; (2) The use of FPC can greatly reduce the size and weight of electronic products, which is suitable for the development of electronic products 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, PDAs, digital cameras and other fields or products; (3) FPC also has the advantages of good heat dissipation and weldability, easy assembly and low overall cost. The design of soft and hard combination also makes up for the slight lack of component load-bearing capacity of the flexible base material to a certain extent. (1) High one-time initial cost: Since flexible PCB is designed and manufactured for special applications, the initial costs for circuit design, wiring and photographic plates are relatively high. Unless there is a special need to use soft PCB, it is usually best not to use it in small quantities; (2) It is difficult to change and repair the flexible PCB: Once the flexible PCB is made, changes must start from the base map or the prepared light drawing program, so it is not easy to change. Its surface is covered with a protective film, which needs to be removed before repair and restored after repair. This is a relatively difficult task; (3) Restricted size: When soft PCB is not yet common, it is usually manufactured using the intermittent process. Therefore, it is limited by the size of the production equipment and cannot be made very long or wide; (4) Improper operation and easy damage: Improper operation by the assembly personnel can easily cause damage to the soft circuit, and its soldering and rework require trained personnel. [3] |
