Offered to manufacturers of PCB laminates to reduce voids in cured, resin-filled substrates.
Arizona — Isola Group S.à r.l. has announced that the company has launched a technology-licensing program to mitigate conductive anodic filamentation (CAF) problems in the fabrication of PCBs. This proprietary manufacturing technology, which is offered by ISOLA USA, reduces the number of voids in resin-impregnated dielectrics, which is a major source of CAF failures. The license is available to laminate and prepreg manufacturers and users worldwide and is protected by U.S. patent number 6,083,855, Taiwan patent number I230657, patents in several additional countries, and by know-how.
Advancements in laminate manufacturing procedures, as well as the resins and reinforcing materials used in the laminates, have resulted in laminate products that are manufactured quickly and efficiently with a high degree of strength and reliability. Laminates are prepared by impregnating a fibrous reinforcement material with a blend of liquid resin polymeric. The impregnated fabric is then heated and brought to a semi-cured, tack-free stage called prepreg. In the absence of an effective "void reduction" technology, prepregs typically include voids, such as small air pockets in the fiber bundles and in the interstitial spaces between the fiber bundles, which are a common source of CAF problems The next step in the manufacturing process of a copper-clad laminate is the lamination of the prepreg between thin layers of copper foil, by the application of an appropriate temperature and pressure profile. A majority of the voids in the prepreg get locked-up in this final, fully cured state.
Isola’s technology-licensing program provides a laminate impregnation process that is capable of producing high quality, resin-impregnated prepreg, substantially free of voids, which mitigates CAF failure. CAF is of constant concern to original equipment manufacturers and PCB designers, as they strive to improve the reliability and quality of their products. Smaller hole-pitch geometries make PCBs susceptible to CAF growth, a form of electromechanical migration within the board. CAF failures may occur for several reasons, including:
- The incompatibility of the silane finish with the resin or the glass.
- A weak interfacial bond between the resin and the glass.
- Hollow fibers (an artifact of the yarn manufacturing process).
- Poor drilling at the PCB fabricator, leading to crazing and debonding.
- Voids after the impregnation process. These voids are often referred to as interlaminar yarn voids (IYVs), striations and in some special cases, triple points.