page_title: Photoresist
section_title: Printed circuit boards
hierarchical_section_title: Photoresist / Applications / Printed circuit boards
caption_attribution_description: English: SEG DVD 430 - Printed circuit board
context_page_description: A photoresist is a light-sensitive material used in several processes, such as photolithography and photoengraving, to form a patterned coating on a surface. This process is crucial in the electronic industry.
  The process begins by coating a substrate with a light-sensitive organic material. A patterned mask is then applied to the surface to block light, so that only unmasked regions of the material will be exposed to light. A solvent, called a developer, is then applied to the surface.
  In the case of a positive photoresist, the photo-sensitive material is degraded by light and the developer will dissolve away the regions that were exposed to light, leaving behind a coating where the mask was placed.
  In the case of a negative photoresist, the photosensitive material is strengthened by light, and the developer will dissolve away only the regions that were not exposed to light, leaving behind a coating in areas where the mask was not placed.
  A BARC coating may be applied before the photoresist is applied, to avoid reflections from occurring under the photoresist and to improve the photoresist's performance at smaller semiconductor nodes.
context_section_description: The manufacture of printed circuit boards is one of the most important uses of photoresist. Photolithography allows the complex wiring of an electronic system to be rapidly, economically, and accurately reproduced as if run off a printing press. The general process is applying photoresist, exposing image to ultraviolet rays, and then etching to remove the copper-clad substrate.
caption: A printed circuit board-4276
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