PCB Tech - Processing of FPC Soft Board Reinforced Board

The processing of FPC soft board reinforced board, FPC soft board reinforced board is unique to flexible circuit boards, and its shape and materials used are also various

Adhesives are generally film-like, and the two sides are protected by a release film. The adhesive film with one side of the release film is attached to the reinforcement board, and then the shape and the hole are processed, and then the flexible circuit board is laminated with the hot roll lamination method. The material used is different, the dimensional accuracy of the shape is also different. The rigid board of epoxy glass cloth laminate and paper-based phenolic laminate can be processed by CNC drilling and milling machines or molds. Polyester and polyimide films can also be processed with a knife mold for simple shape processing. Generally, the film-like reinforcing plate does not need to be processed with fine holes, and can be processed by CNC drilling and molds. If it can be processed or automated in a relatively short period of time, it will reduce manufacturing costs.

Aligning and positioning the reinforcement board on the flexible printed circuit board with the processed shape and holes, this process is difficult to automate, and it accounts for a large proportion of the processing cost, because this operation has to be carried out manually, if A flexible printed board requires multiple reinforced boards of different materials, which increases the cost. On the contrary, if the design is simple or the easy-to-operate jig is used, the production efficiency will be significantly improved, thereby reducing the cost. All factories are working hard to improve this process, but still need personnel with certain production skills to operate.

There are pressure-sensitive (PSA) and thermosetting types for the bonding of reinforced boards, and the labor required for processing is also very different. Using the pressure-sensitive type is very simple, tear off the release film on the pressure-sensitive type, and after 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, a simple press can be applied for a few seconds or through a hot press roll.

The use of thermosetting adhesive is not so simple. Generally, a pressure of 3～5MPa (30～50kg/cm.) and a high temperature of 160～180 degree Celsius are required, and it must be pressed for 30～60min. In order to prevent the flexible printed board from being affected by stress, the pressure on the reinforced board must be uniform. If the reinforced board is simply pressurized, the end of the reinforced board may be broken due to the stress.

In addition, the double-sided adhesive film with release film on both sides can be used to bond flexible printed boards, flexible printed boards, or flexible printed boards with rigid printed boards, which is equivalent to half of rigid printed boards. The solid sheet, its processing and curing process is the same as the laminating process of the reinforced board.