FPC flexible electronic circuit board related terms

Infineon / Mitsubishi / Fuji / Semikron / Eupec / IXYS

FPC flexible electronic circuit board related terms

Posted Date: 2024-01-12

FPC is mainly used in many products such as mobile phones, laptops, PDAs, digital cameras, LCMs, etc. The following is an introduction to commonly used terms related to FPC.

1. Access Hole (exposed hole, exposed bottom hole)

It often refers to the protective layer Coverlay on the surface of the soft board (the penetration hole must be punched out first), which is used as a solder mask on the surface of the soft board circuit. However, the hole wall of the annular ring or the square pad required for welding must be deliberately exposed to facilitate the welding of the parts. The so-called "Access Hole" originally refers to the fact that the surface layer has a penetration hole, allowing the outside world to "access" the solder joints on the board surface under the surface protective layer. Some multi-layer boards also have such exposed holes.

2. Acrylic

It is the common name of polyacrylic resin. Most of the flexible boards use its film as the adhesive film.

3. Adhesive glue or adhesive

A substance that can bond two interfaces, such as resin or paint.

4. Anchoring Spurs

On a mid-board or single panel, in order to make the annular ring welding pad have stronger adhesion properties on the board surface, a few additional finger claws can be attached to the extra open space outside the annular ring to make the annular ring more secure. Consolidate to reduce the possibility of floating away from the board.

5. Bandability bendability, bending ability

It is a characteristic of Dynamic Flex Board (Dynamic Flex Board). For example, the quality of the flexible board connected to the Print Heads of computer disk drives should reach one billion times of "bending test".

6. Bonding Layer combination layer, then layer

It often refers to the film layer of a multi-layer board, or TAB tape, or the adhesive layer between the copper sheet and the polyimide (PI) base material of the soft board.

7. Coverlay/Cover Coat surface protection layer and protective layer

It is not easy to use the green paint used for hard boards for the solder mask on the outer circuits of soft boards, because it may fall off when bent. It is necessary to use a soft "acrylic" layer 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 special "acrylic" layer The "outer membrane" is specifically called the surface protective layer or protective layer.

8. Dynamic Flex (FPC) dynamic soft board

Refers to a flexible circuit board that requires continuous movement, such as the flexible board in the read-write head of a disk drive. In addition, there is also "Static FPC", which refers to soft boards that no longer move after being properly assembled.

9. Film Adhesive, adhesive film

It refers to the dry laminated adhesive layer, which can contain a film of reinforcing fiber cloth, or a thin layer without reinforcing material and only with adhesive material, such as the adhesive layer of FPC.

10. Flexible Printed Circuit, FPC soft board

It is a special circuit board that can change its shape in three dimensions during downstream assembly. Its base material is flexible polyimide (PI) or polyester (PE). Like hard boards, this soft board can be made with plated through holes or surface mount pads for through-hole insertion or surface mount mounting. The board surface can also be attached with a soft cover layer for protection and soldering resistance, or printed with soft soldering green paint.

11. Flexural Failure Flexural damage

The breakage or damage of the material (plate) due to 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 "polyamide" flake-shaped insulating soft material. After being attached with rolled copper foil or electroplated copper foil, it can be made into the base material of a flexible circuit board (FPC). .

13. Membrane Switch Membrane Switch

Using a transparent polyester (Mylar) film as a carrier, the silver paste (Silver Pastes or silver paste) is printed on the thick film circuit using the screen printing method, and then combined with the hollowed-out gasket, combined with the protruding panel or PCB , becoming a "touch-sensitive" switch or keyboard. This kind of small "button" device is often used in hand-held calculators, electronic dictionaries, and some home appliance remote controls, and is called a "membrane switch."

14. Polyester Films

PET flakes are commonly referred to as Mylar Films, a product of DuPont Company, 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 they can also be used as the substrate for silver paste printed film circuits (MembraneCircuit). Others are In the electronics industry, it can also be used as the insulation layer of cables, transformers, coils, or tubular storage devices for multiple ICs.

15. Polyimide (PI) polyimide

It is an excellent resin polymerized by Bismaleimide and Aromaticdiamine. It was first known as Kerimid 601, a powdered resin product 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 boards (FPC) and tape automatic bonding (TAB). It is also an important board for military hard boards and supercomputer motherboards. This material is from mainland China. The translated name is "polyamine".

16. Reel to Reel reel (disc) linked operation

Some electronic parts and components can be produced using a reel (disc) retractable process, such as TAB, IC lead frame, some flexible boards (FPC), etc., which can be retracted and retracted using tape. Conveniently, it can complete its online automatic operation to save the time and labor cost of single-piece operations.

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