Polyimide Film Production Process Technology
The preparation of the polyimide film is divided into a dipping method, a casting method, and a casting stretching method depending on the process. The dipping method is one of the most conventional methods in which a polyamic acid solution is impregnated on an aluminum foil substrate and baked to form a polyamic acid film. The substrate and the film are placed in a high-temperature baking furnace for dehydration imidization reaction, and then peeled, trimmed, wound, pickled, washed with water, and dried to obtain a polyimide film. The production process and operation of the method are the simplest, but the film thickness uniformity and mechanical strength are poor, and it is difficult to achieve the quality requirements of the high performance film.
In the casting method, a polyamic acid solution is cast through a casting nozzle onto a stainless steel belt running below, and dried by a drying tunnel to form a self-supporting gel-like film. The gel-like film was peeled off from the tape to be subjected to high-temperature imidization and winding to obtain a polyimide film, and the film uniformity and mechanical properties obtained by the method were remarkably improved.
The difference between the casting stretch method and the casting method is that a biaxial stretching process is added before the winding, which not only greatly improves the physical properties of the film, but also greatly improves the electrical properties and thermal stability. Analysis of the development trend of polyimide film market, microelectronics field will become one of the most potential application areas, its lightweight, refined requirements will inevitably lead to large-scale production of electronic engineering (electronic grade) polyimide film, In order to achieve high quality requirements, the casting method and the casting stretching method will become a common preparation method in the industry and further improved in practice.