Solder clad lead frame for assembly of semiconductor devices and method

A lead frame comprising:

• a plurality of conductive leads, the near ends of each being arranged in a predetermined pattern defining a die mounting area for attaching a semiconductor die thereto, at least one of said plurality of conductive leads having an extended near end portion extending inwardly into the die mounting area, said extended near end portion being stepped down to a lower level than the remaining portion of its near end such that an under-formed excess area is provided, wherein said near ends of said plurality of leads include the remaining portion of said near end of said at least one of said plurality of conductive leads being solder clad, wherein said stepped down near end portion of said at least one of said plurality of leads is suited to receive solder paste thereon such that the semiconductor die is held in place prior to the final assembly of the semiconductor device.

A semiconductor lead frame comprising:

• a plurality of semiconductor device leads, the near ends of which being aligned in a predetermined pattern to form a die mounting area, a first connecting tie bar attached to first group of said plurality of device leads in proximity to said near ends thereof, a second tie bar attached to second group of said plurality of said device leads in proximity to said near ends thereof, said first and second tie bars holding said first and second groups of said plurality of device leads in alignment at substantially the same level, one of said second group of said plurality of device leads having an extended near end portion extending inwardly into said die mounting area, said extended near end portion being downward formed such that lies at a level below the level of said aligned near ends of said plurality of device leads;
• and
• a solder paste deposited in the extended near end portion for electrically contacting a semiconductor die.

A semiconductor lead frame comprising:

• a plurality of semiconductor device leads, the near ends of which being aligned in a predetermined pattern to form a die mounting area, a first connecting tie bar attached to first group of said plurality of device leads in proximity to said near ends thereof, a second tie bar attached to second group of said plurality of said device leads in proximity to said near ends thereof, said first and second tie bars holding said first and second groups of said plurality of device leads in alignment at substantially the same level, one of said second group of said plurality of device leads having an extended near end portion extending inwardly into said die mounting area, said extended near end portion being downward formed such that such that lies at a level below the level of said aligned near ends of said plurality of device leads, wherein at least two of said aligned near ends of said plurality of device leads is solder clad, wherein said aligned near ends of said plurality of device leads is solder clad, wherein said downward formed near end portion forms an under excess area acceptable to receive solder paste thereupon.