Improving Dry film Lamination Yields

摘要

The dry film lamination process is designed to enhance uniform contact between the dry film resist and the surface of the PCB laminate material. The viscosity of the resist is lowered by the addition of heat transmitted through the rolls. The resist can then flow to conform to the surface topography of the substrate. By applying a pressure differential across the rolls, adhesion is enhanced, and the pressure may be transmitted to the lamination rolls pneumatically, hydraulically, mechanically or by a combination of these means.rnInsufficient pressure and/or non-uniform pressure can lead to lamination defects such as dry film resist wrinkles or poor resist conformation (that can lead to opens in the print and etch process) caused by insufficient nip pressure.1'9 These yield detractors can be minimized by the addition of a measuring device to monitor nip pressure magnitude and uniformity. Specialized films10 that are pressure sensitive are available to measure the actual force profile at the interface of the roller set. The pressure indicating film is placed between the two rolls before closing the nip, and after applying pressure, an image is captured on the pressure indicating film, revealing both the pressure distribution and the magnitude, commonly called the "footprint" of the rollers.