Patent EP-0574893-A2 (EP)
Inventor: DUFFY THOMAS PATRICK
IPC: H01L21/677
Filed: 1993-06-16
Abstract: Disclosed is a method of manufacturing a printed circuit panel. The method is carried out without a cleanroom, but in a clean room environment. The first step is to place a thin, non-rigid panel in a suitable fixture system, for example, for transfer and also for processing. The system includes a peripheral frame fixture for surrounding and supporting the in-process circuit panel layer, and a a loading chuck for mounting the in-process circuit panel layer in the peripheral frame fixture. The peripheral frame fixture includes a bottom plate (175) having a central opening to expose the circuit panel layer, a top frame (179) having a corresponding central opening to expose the opposite surface of the circuit panel layer, and compressive means, as screws, bolts, or the like, for applying a z-axis compressive force to the bottom plate, the top frame, and a panel layer therebetween. The loading chuck includes a peripheral edge for receiving the bottom plate of the peripheral frame fixture. 
A vacuum table is within the area bounded by the peripheral edge of the loading chuck and the peripheral frame of the peripheral frame fixture, and is coplanar with them. The vacuum table includes slidable bearing surfaces (131), with vacuum apertures (133) for drawing a vacuum to hold the panel in place, and slide actuators for moving the slidable bearing surfaces to apply x-y-axis tension to a panel on the bearing surfaces. 
The fixtured panel is then placed in an air tight transfer container, which has a substantially contaminant free atmosphere. The walls of the transfer container are fabricated out of substantially particulate free, unfilled polymers, such as polycarbonate. One of the end walls is an access wall. The access wall has an opening surrounded by a ferromagnetic gasket. This gasketed opening is adapted to receive a ferromagnetic door panel. The transfer container has a sealed door at one end. The transfer container is then brought into a sealable, substantially airtight interlock with a process enclosure. This process enclosure also has a substantially contaminant free atmosphere, and a sealed door at one end. An airtight seal is formed between the transfer container and the process enclosure, and also between the surfaces of the two doors. This is to avoid introducing surface contaminants into the process enclosure and transfer container atmospheres. Next, the two doors are opened simultaneously. This is to allow the transfer of at least one panel and its fixture from the transfer container into the process enclosure. Inside the process enclosure the panel is transferred to a process station for a manufacturing process. Finally, the panel and its fixture are transferred from the process enclosure into the transfer container. This may be the same container or a different container. The doors of the process enclosure and the transfer container are then closed and sealed. Also disclosed is a manufacturing system having isolated islands of "clean room" environment connected by inter-process transfer containers for transfering in-process workpieces. The system has airlock transfer ports between the process enclosures and the inter-process transfer containers. The make and break airlock transfer ports have facing sealable doors in the process enclosure and the transfer container. These doors are in air sealable facing recesses of the process enclosure and the transfer container. At least one peripheral gasket surrounds the recesses and the pair of doors. This provides a substantially clean room environment in the airlock. The sealable door in the interprocess transfer container is fabricated of a ferromagnetic material and is seated on a ferromagnetic gasket, while the sealable door in the process enclosure has a controllable electromagnetic clamp.