Fabrication method of a mixed alloy lead frame for packaging power semiconductor devices

A method of using mixed alloy lead frame for packaging power semiconductor devices comprises the following steps:

• Step 1. Fabricate a lead frame assembly welding plate (3,3′,3″), set a plurality sets of upper and lower grooves (31,31′,31″) at an upper part and a lower part of the lead frame assembly welding plate (3,3′,3″) respectively, set a plurality of heat sink positioning columns (311,311′,311″) in each groove (31,31′,31″), and set a plurality of pin positioning columns (32,32′,32″) at a center of the lead frame assembly welding plate (3,3′,3″) between the upper and lower grooves;
• Step 2. Fabricate a plurality of heat sinks (1,1′,1″), set a positioning hole (13,13′,13″) and a heat sink welding zone (12,12′,12″) on each heat sink (1,1′,1″);
• Step 3. Fabricate a pin array (2,2′,2″), branch out a plurality of multiple-pin sets of pin terminals (21,21′,21″) respectively from an upper end and a lower end of the pin array (2,2′,2″), set a pin welding zone (211,211′,211″) corresponding to the heat sink welding zones (12,12′,12″) on a pin terminal of each set of pin terminals (21,21′,21″), and set a plurality of pin positioning holes (22,22′,22″) between two sets of pin terminals (21,21′,21″);
• Step 4. Position the heat sinks (1,1′,1″) in the grooves (31,31′,31″) of the lead frame assembly welding plate (3,3′,3″) with the heat sink positioning columns (311,311′,311″) of the lead frame assembly welding plate (3,3′,3″) going through the heat sink positioning holes (13,13′,13″);
• Step 5. Position the pin array (2,2′,2″) in the area between the upper and lower grooves on the lead frame assembly welding plate (3,3′,3″) with the pin positioning columns (32,32′,32″) (22,22′,22″) of the lead frame assembly welding plate (3,3′,3″) going through the pin positioning hole;
• and
• Step 6. Connect the heat sinks (1,1″,1″) and the pins (2,2′,2″) by joining each pin welding zone to a corresponding heat sink welding zones therefore forming a lead frame array.