Photoresist is composed of the three main ingredients : the photosensitive resin, photosensitizer and solvent .Photosensitive resin after illumination, the exposure area can quickly produce light curing reaction, making the physical properties of the material, especially for obvious changes such as solubility, affinity.Obtained with the appropriate solvent, solvent to soluble part, get the required image.Photoresist is widely used for printed circuit and integrated circuit manufacturing and printing plate-making process.Photoresist technology is complex, more varieties.According to the principle of its chemical reaction mechanism and the development, can be divided into two categories, negative photoresist and positive photoresist.Light form the unsolvable matter is negative photoresist;On the other hand, for some solvent is not to be dissolved, light into soluble substances is the positive photoresist.Based on the chemical structure of photosensitive resin, photoresist can be divided into three types.Type (1) light polymerization, the alkene monomers, under the effect of light generates free radicals, free radical monomer polymerization by any further, the generated polymers, has the characteristics of the form as.(2) light decomposition model, using materials containing azide quinone compounds, light, can produce light decomposition reaction, from oil soluble into water soluble, can be made into positive photoresist.(3) light crosslinking type, using polyvinyl alcohol lauric acid ester as photosensitive material, such as under the action of light, a double bond in the molecule is opened, and between the chain and chain crosslinking, forming a mesh structure of insoluble, and corrosion resistant effect, it is a kind of typical negative photoresist. Ethyl Lactate is a good solvent during the production of photoresist. Because Ethyl Lactate is biodegrdable, environmentally, especially, it can replace traditionaly solvent , like PMA,PM, NMP. In the process of remove residual gum, Ethyl Lactate can make strong solvency ,easily dissolve the residual photoresist.
