PCB Fabrication

Teach you some commonly used terms related to FPC flexible electronic circuit boards

by:A-TECH      2021-03-23
FPC is a flexible electronic circuit board. The flexible circuit board is a highly reliable and excellent flexible printed circuit board made of polyimide or polyester film as the base material. Referred to as soft board or FPC, it has the characteristics of high wiring density, light weight, and thin thickness. FPC is mainly used in many products such as mobile phones, notebook computers, PDAs, digital cameras, LCMs, etc. The following is an introduction to the common related terms of FPC. 1. AccessHole exposed holes (exposed holes, exposed bottom holes) often refer to the protective layer Coverlay (exposed holes that must be punched out first) on the surface of the soft board, which is used as a solder mask on the surface of the soft board. . However, it is necessary to deliberately expose the wall of the hole ring hole or the square welding pad required for welding to facilitate the welding of the parts. The original text of the so-called'AccessHole' means that the surface layer has exposed holes, so that the outside world can'close' to the surface solder joints under the surface protection layer. Some multilayer boards also have such exposed holes. 2. Acrylic is the common name of polyacrylic resin. Most of the soft boards use its film, which is used as the adhesive film. 3. Adhesive glue or adhesive can make the two interfaces complete the bonding material, such as resin or paint. 4. AnchoringSpurs force claws on the middle board or single board. In order to make the hole ring welding pad have a stronger adhesion property on the board surface, you can add a few finger claws on the extra space outside the hole ring. Make the ring more solid to reduce the possibility of floating from the board surface. As shown in the figure, it is a schematic diagram of the force claws faintly seen under the soft board's surface protection layer. 5. Bandability, bending ability is a characteristic of DynamicFlexBoard (DynamicFlexBoard), such as the soft board connected to the print head of a computer disk drive (PrintHeads), and its quality should reach one billion times of'bendability test' . 6. BondingLayer bonding layer, then layer often refers to the film layer of the multilayer board, or TAB tape, or the sheet of soft board, the adhesive layer between the copper skin and the polyimide (PI) substrate. 7. The outer circuit of Coverlay/CoverCoat surface protection layer and protective layer soft board is not easy to use the green paint used for hard board, because it may fall off when bending. It is necessary to use a kind of soft'acrylic' laminated on the board surface, which can be used as a solder mask and protect the outer circuit, and enhance the resistance and durability of the soft board. This kind of special' The'outer membrane' is specifically called the surface protective layer or protective layer. 8. DynamicFlex (FPC) dynamic soft board refers to a flexible circuit board that needs to be used for continuous movement, such as the soft board in the read-write head of a disk drive. In addition, there is also a 'Static FPC' (StaticFPC), which refers to a soft board that no longer moves after it is assembled properly. 9. FilmAdhesive adhesive film. Adhesive film refers to a dry-thinned adhesive layer, which can include a film with reinforcing fiber cloth, or a thin layer without reinforcing material and only adhesive materials, such as the adhesive layer of FPC. 10. FlexiblePrintedCircuit, FPC soft board is a special circuit board, which can be changed in three-dimensional space during downstream assembly. Its substrate is flexible polyimide (PI) or polyester (PE) . This kind of soft board is also like a hard board, which can be made with plated through holes or surface adhesive pads for through hole insertion or surface adhesive mounting. The board surface can also be attached with a soft cover layer (CoverLayer) for protection and solder protection, or printed with a soft solder mask green paint. 11. FlexuralFailure Flexural Failure The fracture or damage of the material (plate) caused by repeated bending and flexing actions is called FlexuralFailure. 12. Kapton polyimide soft material. This is the trade name of DuPont's product. It is a kind of 'polyimide' flake-shaped insulating soft material. It can be made after attaching rolled copper foil or electroplated copper foil. As the base material of soft board (FPC). 13. MembraneSwitch membrane switch uses a transparent polyester (Mylar) film as a carrier, and uses a screen printing method to print silver paste (SilverPastes or silver paste) on a thick film circuit, and then matches with hollowed-out gaskets and protruding The panel or PCB is combined to become a 'touch-type' switch or keyboard. This kind of small 'button' devices are often used in hand-held calculators, electronic dictionaries, and some home appliance remote controls, etc., and are called 'membrane switches'. 14. PolyesterFilms polyester sheet is referred to as PET sheet. The most common one is DuPont's product MylarFilms, which is a material with good electrical resistance. In the circuit board industry, the transparent protective layer on the surface of the imaging dry film and the coverlay on the surface of the soft board (FPC) are all PET films, and it can also be used as the substrate of the silver paste printed film circuit (Membrane Circuit). In the electronics industry, it can also be used as the insulating layer of cables, transformers, coils, or the tubular memory of multiple ICs. 15. Polyimide (PI) is an excellent resin co-polymerized by Bismaleimide and Aromaticdiamine. It was first known as the powdered resin product Kerimid601 launched by the French company 'Rhone-Poulenc'. DuPont made it into a sheet, called Kapton. This kind of PI board has excellent heat resistance and electrical resistance. It is an important raw material for flexible board (FPC) and tape automatic bonding (TAB), and it is also an important board for advanced military hard boards and supercomputer motherboards. This material The translated name in mainland China is'polyamide and polyamide'. 16. ReeltoReel reel (disc) interlocking operation of certain electronic components, which can be produced by reel (disc) retractable process, such as TAB, IC's metal tripod (LeadFrame), and some soft boards ( FPC), etc., can use the convenience of reeling and unwinding to complete its on-line automatic operation, so as to save the time and labor cost of single-piece operation.
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