How closely can the deposit thickness be controlled?
Screen printing can achieve deposits with total thickness variation less than 10%, which is well within the requirements for membrane-type or solid oxide fuel cells. Deposits can also be positioned accurately in the x-y plane, to within ±20 micron, and complex shapes can be created if desired. This is difficult to achieve with vapour deposition, for example. Moreover, the very high process control and repeatability of the process virtually eliminate instances of voids or pin holes, which can induce catastrophic failure of a membrane-type fuel cell. In addition, DEK is developing verification systems to detect the presence of any such defects and to verify uniform thickness. Screen printing will only produce voids or pin-holes if the process is allowed to drift beyond limits, through inadequate process control or poor maintenance.
