#fpcway

The filler material is placed in the open areas during pre-stacking, serving the following functions: filling cavities to equalize bonding pressure; and preventing interlayer bonding of the flexible sheet.

A common rigid-flex PCB structure consists of one or more flexible PCBs sandwiched between two sets of rigid cover plates. The cover plate area remains wire-free and is eventually removed.

Polymer thick film printing step 2: Printing the dielectric layer (overlay coating); shaping, etc.

Subtractive fabrication is the most commonly used method in FPCB fabrication. It can produce circuits of a certain thickness, and terminals can be made from almost all known metals. It allows for localized repairs or rework without requiring special equipment.

The direct terminal exposure process used in single-sided flexible board manufacturing can also be extended to double-sided flexible board manufacturing, where terminals are directly exposed on the pads, allowing for assembly on both sides.

The disadvantages of vacuum chamber presses are as follows: limited maximum pressure; consumption of vacuum bags, manpower, and materials.

Vacuum-assisted lamination is not commonly used for single- or double-sided flexible boards, but is frequently used in multi-layer flexible boards and rigid-flexor composite structures. It is relatively susceptible to the formation of lamination voids due to volatiles.

When fabricating conductor circuits, the terminal area must be pre-windowed; this is the most obvious difference between flexible and rigid boards. Using insulating materials with the same composition as the substrate dielectric produces a symmetrical, consistent, and stable structure.