Instant Masking is a new high-speed selective electroplating technique similar in some ways to through-mask plating. Through-mask plating works as follows:

• The substrate is cleaned
  
• Photoresist is applied and baked
  
• The resist is exposed to radiation through a mask
  
• The resist is developed (and sometimes plasma-ashed), resulting in a pattern of apertures.
  
• Metal is electroplated through through the apertures onto the substrate.
  
• The resist is stripped from the substrate.
  

Unfortunately, this process involves a total of up to ten separate steps, multiple pieces of equipment, and multiple liquids. It is very time-consuming and difficult to automate, and thus not suitable for automatically building 3-D microdevices having hundreds of layers or more.

Instant Masking, the enabling technology for EFAB, works much more like printing, in which a pre-fabricated plate transfers ink onto paper; however, Instant Masking deposits materials such as metals.