When required, there are a number of viable options for protectively coating flex PCB circuits. Which method to use depends on a number of factors including application and cost, among others. It can be difficult at times to make the decision, but it is helpful to have choices.

Coverlayer lamination may seem straightforward, but lamination of machined adhesive-backed coverlayer is one of the more important process steps to be mastered in flex PCB manufacture. There are a number of different steps in the process and a variety of materials that make them possible.
A clean working environment is an important prerequisite to coverlayer lamination. Dust and dirt particles typically carry a small charge can easily be attracted to the work due to large electrostatic charges created when separating the coverlayer from the film that protects the adhesive surface of the coverlayer. A clean area, fitted with anti-static devices, similar to the environment provided for imaging, is recommended. There are also specially developed tools which are designed to remove dust using specially developed tacky rollers.

ALIGNMENT OF ACCESS HOLES

Maintaining the alignment of access holes with flex PCB circuit features is critical to the creation of reliable interconnection and test features. Flex circuit manufactures have developed a number of methods to facilitate this end. One method is to use tooling holes internal to the panel and parts. Another commonly used technique is to heat-tack the coverlayer to the flex PCB circuit panel during the lay-up process. This has proven to be very effective and allows the technician to compensate for some of the dimensional instability associated with these unreinforced films.

There are a number of viable options for protectively coating flex PCB circuits when required. Coverlayer lamination may seem straightforward, but lamination of machined adhesive-backed coverlayer is one of the more important process steps to be mastered in flex PCB manufacture. Another commonly used technique is to heat-tack the coverlayer to the flex PCB circuit panel during the lay-up process.