Stacked leadframe implementation for DC/DC convertor power module incorporating a stacked controller and stacked leadframe construction methodology

A method of forming a power converter package, the method comprising,

• providing an array of first leadframes and an array of second leadframes and a plurality of LS FET's and a plurality of HS FET's;
• coupling the plurality of LS FET's with a plurality of first die attach sites, each first die attach site associated with a respective one of said plurality of first leadframes thereby enabling electrical connection between a LS FET gate of each LS FET and a gate pad of the respective first leadframe and enabling electrical connection between a LS FET source of each LS FET and the respective source pad of the first leadframe, thereby generating a first array;
• coupling the plurality of LS FET's with a plurality of second die attach sites, each second die attach site associated with a respective one of said plurality of second leadframes thereby enabling electrical connection between a HS FET gate of each HS FET and a gate pad of the respective second leadframe and enabling electrical connection between a HS FET source of each HS FET and the respective source pad of the first leadframe forming a second array;
• arranging the second array on the first array such that the plurality of HS FET sources are electrically connected with drains of the LS FET's through the plurality of second leadframes to form an array of stacked leadframes;
• mounting a plurality of controllers on at least one of,
• the array of first leadframes,
• the array of second leadframes,
• the array of stacked leadframes;
• wirebonding the plurality of controllers to establish electrical connections with appropriate LS and HS FET's;
• encapsulating the stacked leadframes;
• and
• singulating the encapsulated stacked leadframes to form a plurality of power converter packages.

A method of forming a multiple stacked leadframe integrated circuit (IC) package, the method comprising,

• mounting a first IC die on a die attachment site of a first leadframe to form a first arrangement;
• mounting a second IC die on a die attachment site of a second leadframe to form a second arrangement;
• mounting the first arrangement with the second arrangement such that they are arranged one over another in a stacked leadframe configuration;
• and
• encapsulating the stacked leadframe configuration to form the IC package having the first and second IC dies, wherein,
• a die mounting tool is provided, the tool comprising complementary alignment features suitable for aligning leadframes arranged on the tool and punch apertures suitable for enabling removal of portions of leadframes stacked on the tool;
• and
• wherein mounting the leadframes of the stacked leadframe further comprises,
• mounting the first arrangement on the tool using first alignment features of the first leadframe, such that the first alignment features are in registry with at least some of the complementary alignment features of the tool,
• mounting the second arrangement over the first arrangement using second alignment features of the second leadframe and at least some of the complementary alignment features of the tool to attain desired alignment between the first and second leadframes and align with the tool such that tie bars of the second leadframe are in registry with the punch apertures of the tool, and
• reflow processing to secure the first and second arrangements with each other;
• and
• further comprising, punching through the punch apertures of the tool to sever the tie bars of the second leadframe.