Method of treating photoresists using electrodeless UV lamps

Abstract

Methods for treating a photoresist by exposure to light from an electrodeless UV bulb are disclosed. The methods are applicable to both positive and negative photoresists. In the case of positive photoresists, use of electrodeless UV lamps significantly reduces the UV exposure time. Methods for making circuit boards and apparatus for making circuit boards are also disclosed.

What is claimed is:  
     
         1 . A method for treating a photoresist composition comprising exposing said composition to radiation from an electrodeless UV lamp in the 100 nm to 450 nm wavelength range at a dosage sufficient to effect said treating.  
     
     
         2 . The method of  claim 1 , wherein said radiation is in the 280 to 450 wavelength range.  
     
     
         3 . The method of  claim 1 , wherein said photoresist is a positive photoresist and treating results in increasing the solubility of the photoresist.  
     
     
         4 . The method of  claim 1 , wherein said photoresist is a negative photoresist and treating results in decreasing the solubility of the photoresist.  
     
     
         5 . The method of  claim 1 , wherein a mask is used over the photoresist to allow for radiation exposure in a predetermined pattern.  
     
     
         6 . The method of  claim 5 , wherein the mask is affixed to the photoresist within a print frame by vacuum means.  
     
     
         7 . The method of  claim 1 , wherein said dosage is effected by exposing said photoresist to radiation at an intensity of between 40 and 80 milliwatts per centimeter 2  for a period of between 5 and 10 seconds.  
     
     
         8 . The method of  claim 7 , wherein an intensity of 80 milliwatts per centimeter 2  is employed for 5 seconds.  
     
     
         9 . The method of  claim 7 , wherein an intensity of 50 milliwatts per centimeter 2  is employed for 8 seconds.  
     
     
         10 . The method of  claim 7 , wherein an intensity of 40 milliwatts per centimeter 2  is employed for 10 seconds.  
     
     
         11 . An apparatus for making a circuit board from a substrate on which a photoresist is deposited comprising: 
 an electrodeless UV lamp;    means for directing radiant energy from said lamp to said photoresist; and    means for affixing a mask to said photoresist.    
     
     
         12 . The apparatus of  claim 11 , further comprising: 
 support means to hold said substrate during exposure to said radiant energy.    
     
     
         13 . The apparatus of  claim 12 , wherein the support means, the electrodeless UV lamp, or both, are movable.  
     
     
         14 . The apparatus of  claim 13 , wherein the support means is stationary and the electrodeless UV lamp moves.  
     
     
         15 . The apparatus of  claim 13 , wherein the UV lamp is stationary and the support means moves.  
     
     
         16 . The apparatus of  claim 11 , wherein the affixing means is a vacuum means for affixing the mask to the photoresist within a print frame.  
     
     
         17 . The apparatus of  claim 11 , comprising a plurality of electrodeless UV lamps.  
     
     
         18 . The apparatus of  claim 17 , wherein at least one of said lamps is positioned above said substrate and at least one of said lamps is positioned below said substrate.  
     
     
         19 . The apparatus of  claim 11 , wherein said apparatus is fully automated.  
     
     
         20 . A method for making a circuit board comprising: 
 applying a photoresist to an electroconductive substrate;    applying a mask over the photoresist;    treating said photoresist with radiation from an electrodeless UV lamp at a dosage sufficient to effect said treating; and    developing the photoresist.    
     
     
         21 . The method of  claim 20 , wherein said photoresist is a positive photoresist.  
     
     
         22 . The method of  claim 21 , wherein said dosage is sufficient to achieve an SST clear value of 5 or less.  
     
     
         23 . The method of  claim 20 , wherein said photoresist is a negative photoresist.  
     
     
         24 . The method of  claim 23 , wherein said dosage is sufficient to achieve an SST solid value of greater than 8.