insulator having thin conducting films deposited on both sides the films may be electrically connected by vias which pass through the insulator and are either filled or coated with a conducting material while layers 220 230 240 and 250 have been described as discrete layers it will be recognized that the invention also includes embodiments where one of more layers are combined into fewer layers or separated into more layers the combining of layers 240 and 250 into a single layer has previously been discussed additionally the die locator ring 232 shown in layer 230 can also be incorporated into either layer 220 240 or 250 that is locator ring 232 can be an integral part of the locator ring 224 or the locator ring 244 or the circuit layers 250 other similar variations and modifications will be apparent to those skilled in the art and are included within the scope of the present invention the layers 220 230 240 and 250 are assembled as shown in fig8 and sealed into a unitary structure by fusing the glass portions of the individual layers together using conventional semiconductor glass ceramic sealing techniques one apparatus for performing this type of sealing is known in the art as an sst.