Miniaturization in electronics means finer lines and smaller viasin substrate technology. Very fine lines on the substrate are difficultto produce by conventional means. Thick copper layers are difficult toetch and the accuracy of conventional dry film photoresist is notnecessarily sufficient. One very promising means of achieving fine linesis the etching of sputtered thin films on the substrate and growth ofthe copper with an additive method on the tiny lines. It has been shownthat use of dry film photoresist is unsuitable for very narrow lines.Spinning the photoresist is an alternative, but in the test, itsadhesion was not good enough. Most narrow resist lines were washed awayin the development stage. To meet requirements for accuracy, the bestmethod seemed to be the electrodeposited method, in which a very thin,even, homogenous photoresist layer can be generated. This fine layer isdeveloped easily, thus allowing the transfer of fine line images to thesubstrate. For good accuracy on the metal lines, the core materialbeneath the sputtered metal layer must be smooth; the best accuracy canbe achieved only with the smoothest surface. The differences between theoriginal and only slightly brushed surfaces are not very obvious
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