FPC soft board reinforced board processing, FPC soft board reinforced board is unique to flexible circuit board, and its shape and materials are also diverse
The adhesive is generally film-shaped, and the two sides are protected by release film. The adhesive film with one side of release film torn off is pasted on the reinforcing plate, and then the shape and hole are processed, and then it is laminated with the flexible circuit board by hot roll lamination. The dimensional accuracy of the shape is also different with different materials. The rigid plates of epoxy glass cloth laminate and paper-based phenolic laminate can be machined with CNC drilling and milling machine or die. Polyester and polyimide films can also be processed with a knife mold. Generally, the thin-film reinforcing plate does not need to process micro holes, but can be processed with NC drilling and mold. If it can be processed or automated in a short time, the manufacturing cost will be reduced. It is difficult to automate this process by aligning and pasting the reinforcing plate on the flexible printed board with processed shape and holes, and it accounts for a large proportion of the processing cost. Because this operation has to be carried out manually, if multiple reinforcing plates of different materials are required on a flexible printed board, the cost will increase. On the contrary, if the design is simple or easy to operate fixtures are used, the production efficiency will be significantly improved, Thus reducing costs. All factories have made efforts to improve this process, but still need personnel with certain production skills to operate.
The bonding of reinforcing plate includes pressure-sensitive (PSA) and thermosetting, and the labor required for its processing is also very different. Using the pressure-sensitive type is very simple. After tearing off the release film on the pressure-sensitive type and aligning with the position on the flexible printed board, it can be pressurized in a short time, even as long as it is pressed by hand. When a certain bonding strength is required, it is OK to apply pressure for several seconds with a simple press or through a hot pressing roller.
Using thermosetting adhesive is not so simple. Generally, 3 ~ 5MPa (30 ~ 50kg / cm) is required The pressure and high temperature of 160 ~ 180 ℃ must be pressed for 30 ~ 60min. In order to prevent the flexible printed board from being affected by stress, the pressure at the reinforcing board must be uniform. If the reinforcing board is simply pressurized, the end of the reinforcing board may be broken due to stress. The usual practice is shown in the figure below.
In addition, the double-sided adhesive film with release film on both sides can be used to bond the flexible printed board with the flexible printed board or the flexible printed board with the rigid printed board. It is equivalent to the semi-solid sheet used for the rigid printed board, and its processing and curing process is the same as the lamination process of the reinforced board.
