Rigid - flexible multi-layer PCB
Rigid - flexible multi-layer PCB
This type is usually one or two rigid PCB, containing the essential composition of the overall soft PCB. Flexible PCB layer is laminated in rigid multi-layer PCB, and that is to have special electrical requirements or to be extended to rigid circuit outside the dynasty with the Z-plane circuit installed capacity. That the compression of these products in weight and volume as the key, and to ensure high reliability, high density assembly and excellent electrical characteristics of electronic devices has been widely used.
Rigid - flexible multi-layer PCB can also put a lot of soft-sided or double-sided PCB end of the bonded together into a rigid part of the repression, but not bonded into the soft middle part of the rigid part of the Z-face interaction with the metal hole even. Flexible circuits can be laminated to the multilayer rigid inside. Such PCB increasingly used in packaging that require ultra-high density, excellent electrical properties, high reliability and strict limits the volume of applications.
Already has a series of hybrid multi-layer flexible PCB components designed for military avionics, in these applications, weight and volume is essential. In order to meet the required weight and size limits, the internal packing density must be high. In addition to high density circuit outside, in order to minimize crosstalk and noise, all signal transmission lines must be shielded. To use the shield wire separation is virtually impossible to economically packaged into the system. Thus, the multi-storey mixed use
Flexible PCB to achieve their interconnection. This component will shield the signal lines included in the flat ribbon cable flexible PCB, rigid PCB which in turn is a necessary component. Relatively high level in the occasion of the operation, manufacturing is completed, PCB to form a 90 ° S-shaped bend, which provides a way to interconnect the z-plane, and x, y and z-plane vibration stress, tin solder joints in eliminate the stress - strain.
2. Advantages of rigid rigid zone area
2.1 Flexible
Application of soft PCB, a significant advantage is that it can more easily take the line in three-dimensional space and equipment company, can also be curled or folded up and use. As long as allowed within a radius of curvature curly, can withstand a few thousand to tens of thousands of times to use without damage.
2.2 reduce the size of
Even in the component installed, compared with the use of lead wire, thin and flexible flat conductor cross-section of PCB, reducing the wire size, and shape along the chassis to make the device more compact structure, reasonable, and even reduced loading volume. Compared with the rigid PCB space savings of 60 to 90%.
2.3 weight
In the same volume, soft PCB and wire cable than in the same carrying capacity, its weight can reduce about 70%, compared with the rigid PCB, weight about 90%.
2.4 installed with the consistency of
Even with the soft PCB assembly, eliminating the use of wire cable wiring errors. As long as the process by drawing through the proof, all produced after the round of the circuit are the same. Loading does not occur when the wrong cable connected.
2.5 increase the reliability
When using soft PCB assembly even when, as in the X, Y, Z three plane wiring, reducing the switching interconnect, so that the entire system reliability increases, and for the failure of the inspection, providing convenient.
2.6 Design control of electrical parameters
According to requirements, the designer during the soft PCB design, controlled capacitance, inductance, characteristic impedance, delay and attenuation. Can be designed to have a transmission line characteristics. Because these parameters and the wire width, thickness, spacing, insulation thickness, dielectric constant, loss tangent and so on, which is difficult when using wire cables to accomplish.
2.7 Soldering terminal may be a whole
The same as the rigid PCB and flexible PCB, with the terminal pad, eliminates wire stripping head and keep out of tin, thus saving costs. Terminal pad and the element, device, plug, dip soldering or wave soldering can be used to replace each wire by hand soldering.
2.8 optional use of materials
Flexible PCB according to different requirements, different substrate materials used to manufacture. For example, the required equipment with low-cost applications, use polyester film. In demanding applications, the need to have excellent performance, you can use polyimide Asian film.
2.9 low
Even with the flexible PCB assembly, the total cost can be reduced. This is because:
1) Due to the PCB wire soft consistency of the various parameters; implementation of the overall termination, eliminating cable wires fitted with frequently occurring errors and rework, and more convenient replacement of soft PCB.
2) The application of flexible PCB design simplification, it can be directly on the adhesion to the components, reducing the clamp and the fixed parts.
3) the need for shielded wire, flexible PCB with low prices.
Continuity of processing 2.10
As the soft cover foil plates into a continuous roll supply, thus enabling the continuous production of flexible PCB. This also helps reduce costs.
3. Shortcoming
3.1 off the high initial costAs the soft PCB is designed for special applications, manufacturing, and so began the circuit design, wiring and high cost of photographic negatives. Unless there are special needs of the application soft PCB, the usually small amount of application, it is best not used.
3.2 Flexible PCB changes and more difficult to repair
Soft PCB, once made, the change must be prepared from the base map or Gerber proceedings began, so easy to change. Its surface covered with a layer of protective film, remove before patching, patching later on to recover, this is a more difficult task.
3.3 Size restrictions
Flexible PCB's in general not the case, usually Batch process, so by the equipment size limitations, can not do very long, very wide.
3.4 easily damaged by improper operation
Improper installation can lead even the personnel to operate the soft circuit damage, the soldering and rework needs trained personnel to operate.