PCB Blog - Talk about the advantages and disadvantages of rigid flex pcb

Disadvantages of rigid flex pcb

After the introduction of the supplier, it is generally understood that if only "flex board+circuit board+connector" is used to compare "rigid flex pcb", the biggest disadvantage is that the price of "rigid flex pcb" is relatively expensive, which may be nearly twice as much as the original price of "flex pcb+rigid pcb". However, if the price of connector or the cost of HotBar is deducted, the price may tend to be consistent, The detailed cost may have to be actuarial to get a clearer outline. Another disadvantage is that the carrier may need to be used to support the part of the soft plate during SMT beating and furnace passing, which virtually increases the assembly cost of SMT.

Advantages of rigid flex pcb

In addition to price, using rigid flex pcb has many advantages, as listed below:

1. It can effectively save the space on the PCB board and save the process of using connectors or HotBar

Because the rigid flex pcb have been combined, the space that originally needed to use connectors or HotBar manufacturing process can be saved. For some boards with high density requirements, the space of missing a connector is like finding a treasure. In this way, the cost of using connector parts or the cost of HotBar manufacturing process will be saved. In addition, the space between the two boards will also become more compact because connectors are omitted.

2. The signal transmission distance is shortened and the speed is increased, which can effectively improve the reliability

The traditional signal transmission through the connector is "circuit board → connector → flex pcb → connector → circuit board", while the signal transmission of the soft and hard composite board is reduced to "circuit board → flex board → circuit board". The signal transmission distance is shorter, and the problem of signal transmission attenuation between different media is also reduced. Generally, the circuit on the circuit board is made of copper, while the contact terminal of the connector is gold-plated, and the solder pin is fully tin-plated, In addition, solder paste is needed to be welded on the circuit board, and the signal transmission between different media will inevitably have some attenuation. If rigid flex pcb are used, these media will become less, and the signal transmission ability can also be relatively improved. For some products with high signal accuracy requirements, it will help to improve their reliability.

3. Simplify product assembly and save assembly time

The use of rigid flex pcb can reduce the working hours of SMT, because the number of connectors is reduced. It also reduces the assembly time of the whole machine, because the assembly action of inserting the flex pcb into the connector is omitted, or the manufacturing process of HotBar is omitted. It also reduces the cost of parts management and inventory. Because the BOM is reduced, the management becomes less.

The quality of BGA/CSP various internal and external ball pins after solder paste fusion and welding can not be checked by using the method of overhead magnification or microscopic, but the method of side light source and side view magnification can be used instead to check the surface quality of the internal and external solder joints of the belly bottom one by one. When the light source and lens only scan along the periphery, it is called Rigid Endoscope; If the light source and lens are shrunk together and put into a thin steel pipe, and the observer can reach into the abdominal bottom of the area combination device, it is also called Flexible Endoscope. For the solder joints that are difficult to access in the narrow space at the bottom of the abdomen, we can also get a glimpse of the truth, and find a powerful tool for BGA/CSP non-destructive inspection of solder joints. The endoscope used in the electronic industry can not only observe the ball pin quality of BGA/CSP and other area array elements, but also the J-shaped hook pin with the peripheral sequence of PLCC facing inward. The recently launched model can also observe the appearance of the tiny bumps inside the cladding package, which is really amazing! The next generation of soft Endoscope under development will be able to focus the embedded crystal bump under various depth of field. It can clearly see the range under its focusing condition. This observation is very important for the welding point in the deep depth. Its thin optical hardware should not only be very precise, but also be strong and durable. The supporting frame must not only facilitate the clear capture of image images, but also protect optical parts on rigid flex pcb.