Abstract: An apparatus and method for temporarily sealing holes in printed circuit boards are disclosed. The apparatus comprises two major assemblies: a heater block assembly and a vacuum table assembly. The heater block assembly employs a temperature controlled, insulated heater block having a surrounding, movable vacuum collar. A flexible, thermally conductive vacuum skin is mounted on the movable vacuum collar and forms a vacuum chamber in cooperation with a movable vacuum table having a flat, thermally conductive porous plate whose upper surface is parallel to the vacuum table surface. A cooling block in contact with the thermally conductive porous plate cools the porous plate. A sandwich comprising a porous release sheet, the printed circuit board, a thermodeformable material and a thermally conductive cover sheet are positioned on the cooled porous plate. The vacuum table and sandwich are moved together so that the table forms a sealing relation with the flexible, thermally conductive vacuum skin.

Abstract: A method for temporarily sealing holes in a printed circuit board laminate during processing is disclosed. A sheet of deformable material is placed on one side of the PCB and then deformed so that the material extends into each hole to form a protectively sealing plug therein. Thereafter, the other side of the PCB is coated with a suitable resist for subsequent processing. The resist can be either photo-imagable or non-photo-imagable, such as silk screening inks, lacquers and varnishes. After conventional processing of the resist coated PCB, the deformed sheet material that forms the protectively sealing plugs is removed from the PCB. In the preferred embodiment, deformation of the sheet material is accomplished by thermally deforming a thermodeformable sheet material with a pressure differential applied across the thickness of the sheet material.

Abstract: An apparatus and method for temporarily sealing holes in printed circuit boards are disclosed. The apparatus comprises two major assemblies: a heater block assembly and a vacuum table assembly. The heater block assembly employs a temperature controlled, insulated heater block having a surrounding, movable vacuum collar. A flexible thermally conductive vacuum skin is mounted on the movable vacuum collar and forms a vacuum chamber in cooperation with a movable vacuum table having a flat, porous plate whose upper surface is parallel to the vacuum table surface. A sandwich comprising a porous release sheet, the printed circuit board, a thermodeformable material and a thermally conductive cover sheet is positioned on the vacuum table flat, porous plate. Thereafter, the vacuum table and sandwich are moved together so that the table forms a sealing relation with the flexible, thermally conductive vacuum skin.