About the Application for Flexible PCB
Flexible electronics, also known as flex circuits, is a technology for assembling electronic circuits by mounting electronic devices on flexible plastic substrates, such as polyimide, PEEK or transparent conductive polyester film. Additionally, flex circuits can be screen printed silver circuits on polyester. Flexible electronic assemblies may be manufactured using identical components used. Compare with the rigid PCB, it is soft and can be bend. Now ALLPCB also service such service for Flexcible PCB,except the full service for PCB prototype, PCBA, stencil and electronic componnets.
Following let us to check the application of Flexible PCB that ALLPCB customers used in.
Flexible PCB for Cell Phone
Modifications occurring to phones lead changes to happen to all PCBs (printed circuit boards) especially when multiple flexible PCBs are applied. First, light weight andthinness of cell phones drive rigid PCBs to be replaced by flexible circuit boards. The area ratio between rigid area and flexible area phones took advantage of is approximately 80:20 while that will be 20:80. Furthermore, rigid PCB used for cell phones is thin HDI (high density interconnect) PCB. Cell phones mainly depending on rigid PCBs are 27mm thin while those on flexible PCBs is only 16.8mm thin.
Flexible PCBs serving for different positions of a cell phone lead to different structures and demands:
Key Switch Board
Key switch board is a four-layer PCB with thickness less than 0.3mm. This flexible part is equipped with components such as LED and input/output connectors on the surface calling for none flexibility, so solder mask can be applied on the surface. The bending part of this 4-layer flexible board is single-layer conductor that can be bent in the shape of “S”.
LCM (liquid crystal display module)
LCM consists of primary LCD flexible board and subordinate LCD flexible board. The former is a double-sided board while the latter is single-sided board. Bare chip and additional resistance capacitors should be directly assembled on flexible board to drive LCD. The connection of bare chip IC generally depends on ACF (Anisotropic Conductive Film) and flexible circuit board needs to be heated and pressed. Therefore, single-side and double-side copper foil polyimide film without adhesive should be leveraged.
Flexible PCBs used for cell phones mainly come in polyimide board, calling for requirement of thinness, adhesive-free and halogen-free. Furthermore, flexibility resistance should be improved of copper plated, nickel plated and gold plated layers, which is beneficial to flexibility resistance improvement of the whole flexible PCB. It has many advantages that Rigid PCB chouldn’t reach. ALLPCB will try to supply many PCB kinds to reach the demands of customers.