SiP Substrate Rerouting Fine Pitch Leads Under Die
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Solution Overview
Problem
Traditional lead frames are unable to provide a large number of fine-pitched leads due to space limitations, as reducing pitch spacing compromises their rigidity, making it difficult to efficiently utilize space in system-in-a-package (SiP) substrates for connecting multiple devices.
Innovation Solution
A system-in-package substrate with a conductive interconnect substrate that allows for electrical connections between fine-pitched and large-pitched leads by using a composite material to reroute trace pads underneath the die, bonding them to a premolded leadframe substrate, enabling a compact configuration with increased device density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the pitch spacing between leads is reduced to fit more leads within a given area, then the quantity of leads increases, but the rigidity of the leads becomes unacceptably reduced
Solution Approach 1:
The patent transitions from a two-dimensional planar lead frame structure to a three-dimensional substrate structure with vertical stacking. Multiple layers of conductive interconnects are arranged in different planes, allowing leads to be distributed across multiple dimensions rather than competing for space in a single plane. This dimensional transition enables higher lead density without compromising individual lead dimensions and rigidity.
Solution Approach 2:
The patent employs a composite substrate structure combining organic and inorganic materials with embedded conductive interconnects. The substrate provides mechanical support and structural integrity, while the embedded conductive paths provide electrical connections. This composite approach allows the leads to be supported by the rigid substrate rather than relying solely on their own structural strength, enabling finer pitch spacing without sacrificing lead rigidity.
2Area of stationary object
If traditional lead frames are used with fine pitch spacing, then space utilization improves, but the structural integrity and self-supporting characteristics are compromised
Solution Approach 1:
The patent introduces a substrate as an intermediary element between the conductive interconnects and the external environment. The substrate acts as a mediator that provides mechanical support to the fine-pitch conductive paths, allowing them to maintain their dimensions and electrical characteristics without requiring self-supporting rigidity. This intermediary structure enables high-density lead arrangements while preserving structural integrity through the substrate's mechanical properties.
3Productivity
If the number of devices in a package is increased, then the productivity and efficiency improve, but the complexity of electrical connections increases
Solution Approach 1:
The patent divides the electrical connection system into multiple segments organized in different layers and planes. Each layer contains specific conductive interconnects that handle particular signal routes, and vertical vias provide controlled inter-layer connections. This segmentation of the connection architecture allows multiple devices to be interconnected through organized, modular pathways rather than requiring complex point-to-point routing, thereby managing connection complexity while supporting high device density.
Data Source
AI summary
Disclosed in this specification is a system-in-a-package substrate that includes an interconnect substrate for permitting finely pitched connections to be made to an integrated circuit. The interconnect substrate includes a central region on its upper surface for receiving the integrated circuit. The interconnect substrate also has interconnections that electrically connect the finely pitched contacts on the upper surface to larger pitched contacts on the lower surface. The larger pitched contacts connect to a conductive trace frame. The resulting assembly is encased in a molding compound along with a plurality of other devices which are configured to interact with one other through the conductive trace.