Leadframe Interposer for 3D Stacked IC Footprint Reduction
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Solution Overview
Problem
Conventional integrated circuit packaging designs face challenges in reducing size and increasing performance, particularly in supporting high input/output devices and achieving compact stacked package designs with minimal footprint, which is critical for portable electronics where space is limited.
Innovation Solution
The method involves forming a substrate with a base integrated circuit and a leadframe interposer, including ball pads and bond fingers exposed from a molded package body, allowing for a component package to be formed with reduced vertical height and increased interconnects, enabling efficient stacking and reduced footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional packaging designs are used, then the package can support basic electrical interconnect, but the footprint on the mounting surface becomes too large for portable electronics
Solution Approach 1:
The patent transitions from two-dimensional planar packaging to three-dimensional stacked packaging by introducing vertical stacking of multiple die on a common substrate. This dimensional change allows increased I/O capacity and circuitry density without increasing the horizontal footprint, directly resolving the contradiction between compact area and adaptability for high I/O devices
Solution Approach 2:
The patent implements nested packaging by stacking multiple integrated circuit die vertically on a single substrate, with each die nested above the other in a layered configuration. This nesting approach maximizes the use of vertical space, enabling high I/O count devices to be supported within a compact footprint by efficiently utilizing the third dimension
2Productivity
If two or more die are stacked within a single package, then circuitry density increases, but sufficient overlap for electrical interconnect and large footprint top packages are required
Solution Approach 1:
The patent resolves the contradiction between increased circuitry density and reduced footprint by moving electrical interconnects to the vertical dimension through ball grid array technology. Solder balls are positioned at the bottom of the substrate, enabling vertical stacking without requiring large horizontal overlap areas, thus achieving high density within a compact footprint
Solution Approach 2:
The substrate acts as an intermediary element that enables vertical stacking of multiple die. It provides the ball grid array interconnect structure that mediates between the stacked die, allowing electrical connections to be made in the vertical dimension rather than requiring large horizontal overlap areas, thus resolving the contradiction between density and footprint
3Productivity
If feature size is reduced to increase circuit density, then transistor or capacitor density improves, but defect density control, optical system resolution limits, and availability of processing material and equipment become obstacles
Solution Approach 1:
The patent addresses the limitations of further feature size reduction by transitioning to three-dimensional stacking. Instead of continuing to shrink features in two dimensions (which encounters optical resolution limits and defect density issues), the solution moves to the vertical dimension, allowing continued density improvement through stacking multiple die rather than relying solely on smaller feature sizes
Solution Approach 2:
The patent segments the integrated circuit functionality into multiple separate die that are stacked vertically. Each die can be manufactured using existing fabrication processes with controlled defect densities, and the overall system achieves higher density through segmentation and stacking rather than requiring single die with excessively small features that would be difficult to manufacture reliably
Data Source
AI summary
A method of manufacture of an integrated circuit packaging system includes: forming a substrate; mounting a base integrated circuit on the substrate; forming a leadframe interposer, over the base integrated circuit, by: providing a metal sheet, mounting an integrated circuit die on the metal sheet, injecting a molded package body on the integrated circuit die and the metal sheet, and forming a ball pad, a bond finger, or a combination thereof from the metal sheet that is not protected by the molded package body; coupling a circuit package on the ball pad; and forming a component package on the substrate, the base integrated circuit, and the leadframe interposer.