FPC is the abbreviation of Flexible Printed Circuit, also known as flexible circuit board flexible circuit board, flexible printed circuit board printed circuit board, flexible circuit board flexible circuit board, referred to as soft board or FPC, with high wiring density, light weight , FPC The thickness of the thin features, mainly used in mobile phones, laptops, PDA, digital cameras, LCM and many other products.
1. Can be free to bend, fold, winding, can be moved in three-dimensional space and telescopic.
2. Good heat dissipation, the use of F-PC to reduce the volume.
3. To achieve lightweight, small, thin, FPC so as to achieve the integration of component devices and wire connections.
FPC application areas: MP3, MP4 player, portable CD player, home VCD, DVD, digital camera, mobile phone and mobile phone battery, medical, automotive and aerospace field,
FPC placement process requirements and precautions
The process of mounting SMD on flexible printed circuit boards (FPCs) requires a small portion of the consumer's surface mount, where the SMDs are mounted on the FPC due to the assembly space Complete the assembly of the machine.FPC SMD surface mount SMT technology has become one of the development trend. FPC For the surface mount process requirements and attention points have the following points.
One .FPC conventional SMD placement
Features: placement accuracy is not high, the number of components, components, FPC resistance to the main varieties, or individual shaped components.
The key process: 1. Paste printing: FPC by positioning on the printing special pallets, the general use of small semi-automatic printing presses can also be used manual printing, but the manual printing quality is less than semi-automatic printing.
2. Placement: generally can be used manual placement, FPC location accuracy of some of the individual components can also be used manual placement machine placement.
3. Welding: generally use reflow process, special circumstances can also be used spot welding.
2. FPC high-precision placement
Features: FPC on the substrate positioning with MARK mark, FPC itself to be flat.FPC fixed difficult, mass production is more difficult to ensure consistency, high demand for equipment. In addition, printing paste and paste the process control more difficult.
Key process: 1.FPC fixed: from the printed patch to the reflow soldering process fixed on the pallet. The pallet required thermal expansion coefficient is small. FPC There are two fixed methods, the placement accuracy of QFP lead spacing 0.65MM or more with the method A; the placement accuracy is QFP lead spacing 0.65MM below when using method B.
Method A: The pallet is set on the positioning template.FPC is fixed on the pallet with a thin, high temperature resistant tape, and then the pallet is separated from the positioning template for printing. The high temperature resistant tape should be of moderate viscosity and must be easily peeled after reflow There is no residual glue on FPC.
Method B: The pallet is customized and its process requires minimal deformation after repeated thermal shock. There is a T-shaped pin on the pallet, the height of the pin is slightly higher than the FPC.
2. Paste printing: FPC because FPC, FPC positioning with high temperature tape, so that the height of the plane with the pallets are inconsistent, FPC so the printing must use the elastic scraper. Paste ingredients on the printing effect of a greater impact, you must use the appropriate solder paste. Also on the choice of B method of printing template to be special treatment.
3. Patching equipment: First, the solder paste printing presses, the printing press is best equipped with optical positioning system, otherwise the welding quality will have a greater impact.Second, FPC fixed on the pallet, but between the FPC and the total Will produce some small gap, FPC which is the biggest difference with the PCB substrate.Therefore, the setting of the equipment parameters on the printing effect, placement accuracy, welding effect will have a greater impact, so FPC placement on the process control requirements.