Method and apparatus for welding a cover on a circuit enclosure

In the fabrication of a semiconductor chip having a package of fusible material consisting of a case having a bottom, a cover and a side wall, welding apparatus for attaching the cover at its periphery to said wall, presenting a hermetically sealed joint, said apparatus comprising:

• a pair of aligned electrodes reciprocable toward and away from each other for supplying a welding current of controlled amplitude and duration;
• an electrically conductive carrier separate and apart from the electrodes for supporting the package between the electrodes;
• first power means for reciprocating one of the electrodes into and out of engagement with the cover adjacent said periphery;
• and
• second power means for reciprocating the other electrode into and out of engagement with the carrier whereby current flow through the cover and the carrier is localized to a direct line across said wall between said cover and said bottom.

The method of resistance welding a package of fusible material having a case and a cover to provide a hermetically sealed joint between the case and the cover, the cover having a marginal edge, said method comprising the steps of:

• placing the package on an electrically conductive carrier;
• maintaining the carrier functionally separate from the electrodes;
• successively shifting a pair of aligned electrodes capable of supplying a direct welding current until one of the electrodes presses against the cover at its marginal edge and the other electrode presses against the carrier;
• effecting a weld cycle of controlled amplitude and duration during each such pressing engagement of the electrodes until a seam weld is established;
• releasing said pressing engagements of the electrodes at the completion of each weld interval;
• and
• indexing the carrier to relocate the package for the next succeeding weld cycle.

In the fabrication of a semiconductor chip having a package of fusible material consisting of a case having a bottom, a cover having a marginal edge and a side wall, a method of resistance welding for attaching the cover at its periphery to said wall by application of heat and pressure, presenting a hermetically sealed joint, said method including the steps of:

• supporting the package on an electrically conductive carrier between a pair of aligned, shiftable electrodes;
• maintaining the carrier functionally separate from the electrodes;
• shifting one of the electrodes into engagement with the cover adjacent said periphery and said wall;
• shifting the other electrode into engagement with the carrier;
• and
• supplying the electrodes with an intermittent welding current.