Constant Pressure Gradient Chemical Process Tank
Original Publication Date: 1987-Sep-01
Included in the Prior Art Database: 2005-Feb-02
In the manufacture of printed circuit boards, it is often necessary to pass chemical solutions through the board's drilled holes. As the boards become thicker and larger with smaller, higher aspect ratio drilled holes, cleaning becomes more difficult. Hole cleaning is typically accomplished by agitation in a wet process tank. The flow of fluid around the edges of the board reduces pressure, and the full pressure gradient is reached only near the center of the board which is inadequate for the high aspect ratio holes. A process which passes chemical solutions through the holes, in a uniform manner, is described in the following.