Лако-красочные материалы — производство

The majority of base materials for circuit boards are combinations of a copper foil with a laminate, where the laminate itself consists of a carrier material and a resin. Thus proper­ties of the base material such as mechanical strength, dimensional stability, and processi — bility are determined primarily by the carrier material. On the other hand, the resin materials are responsible for the thermomechanical and electrical properties as well as for its resistance against chemicals and moisture. Frequently used carrier materials are based on glass and carbon fibers, papers, and polyamide, whereas the majority of the laminating resins are thermosets such as epoxies, phenolics, cyanates, bismaleimide triazine (BT) resins, maleimides, and various combinations of these [13].

Furthermore, the overall properties of the base materials for circuit boards are determined essentially by the joint between the copper foil and the laminate. This joint can be realized by both an added adhesive and by the laminating resin itself, which additionally, acts as adhesive. An additional adhesive is needed in the manufacture of flexible circuit boards (e. g., polyimide/copper) or of paper-based rigid circuit boards. During this process the adhesive is deposited on the bottom side of the copper foil after it is joined to the laminate by heating under pressure. The primary requirements for such adhesives are:

1. Adjustable processing behavior

2. Systems without or with low organic solvent contents

3. Sufficient bonding strength at elevated temperatures (250 to 320° C for short times)

4. Dielectrical stability, low dielectric constant

5. Resistance against etching and galvanic processes

For the production of base materials for circuit boards with higher performance (e. g., glass/epoxy or graphite/cyanate ester combinations) and of multilayer boards, the laminating resin acts as adhesive or special bonding prepregs must be used. The require­ments for the resins, which act as adhesive, depend on both the processing conditions and the desired properties of the final circuit board and are similar to those described above.