PCB News - Related terms for flexible circuit boards

Related terms for flexible circuit boards

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. Access Hole (exposed hole, exposed bottom hole) often refers to the maintenance layer Coverlay on the surface of the soft board (the exposed hole must be punched out first), which is used as a solder mask on the surface of the soft board. usefulness. However, it is necessary to deliberately expose the wall of the ring hole or the square pad required for welding to facilitate the welding of the parts. The so-called "Access Hole" in the original text means that there are exposed holes on the surface, so that the outside world can "close" to the solder joints on the board 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 joints completely bonded, such as resin or paint.

4. Anchoring Spurs is on the middle board or single board. In order to make the hole ring pad have stronger adhesion properties on the board surface, you can add a few more fingers on the remaining space outside the hole ring., To make the orifice ring more stable to reduce the possibility of floating from the board surface.

5. Bandability, tortuous, can be a characteristic of Dynamic Flex Board (Dynamic Flex Board), for example, the quality of the flexible board connected to the print head of a computer disk drive (Print Heads) should reach a billion times Sex test".

6. Bonding Layer The bonding layer and then the layer usually refers to the film layer of the multilayer board, or the TAB tape, or the sheet of the soft board, the adhesive layer between the copper skin and the polyimide (PI) substrate.

7. For the outer circuit of Coverlay/Cover Coat surface protection layer and maintenance layer soft board, it is not easy to choose the green paint used for hard board, because it may appear to fall off when bending. It is necessary to use a kind of soft "acryl" laminated on the board surface, which can be used as a solder mask and maintain the outer circuit, and enhance the resistance and durability of the soft board. This kind of special" "Outer membrane" is specifically called the surface protective layer or maintenance layer.

8. Dynamic Flex (FPC) dynamic soft board refers to the flexible circuit board that needs to be used for continuous movement, such as the soft board in the read-write head of the disk drive. In addition, there is also a "Static FPC" (Static FPC), which refers to the type of FPC that no longer operates after being assembled properly.

9. Film Adhesive 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. Flexible Printed Circuit, 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 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 for maintenance and solder protection, or printed with a soft solder mask green paint.

11. Flexural Failure Flexural Failure The cracking or damage of data (sheets) caused by repeated bending and flexing actions is called Flexural Failure.

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. The Membrane Switch membrane switch uses transparent polyester (Mylar) film as the carrier, and uses the screen printing method to print silver paste (SilverPastes or silver paste) on the thick film circuit, and then deploys hollow gaskets, and convex The resulting panel or PCB is combined to become a "touch-type" switch or keyboard. This kind of small "key" equipment is often used in hand-held calculators, electronic dictionaries, and some home appliance remote controls, etc., all called "membrane switches".

14. Polyester Films is abbreviated as PET film. The most common one is MylarFilms, a product of DuPont, which is a material with excellent electrical resistance. In the circuit board industry, the transparent maintenance layer on the surface of the imaging dry film, and the coverlay of the soft board (FPC) surface for the solder mask 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 polymerized by Bismaleimide and Aromaticdiamine. It was first known as the powdered resin product Kerimid 601 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 material for flexible board (FPC) and tape active bonding (TAB). It is also an important board for high-end military hard boards and supercomputer motherboards. This information The translated name in mainland China is "polyamide".
16. Reel to Reel reel (disc) interlocking operation of certain electronic components can be produced by the reel (disc) retractable process, such as TAB, IC's metal tripod (Lead Frame), some Flexible board(FPC), etc., can be retracted and unloaded with tape to complete its online active operation, so as to save the time and labor cost of single-piece operation.