Offset Interposer Layout for POP Pad Spacing Mismatch
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Solution Overview
Problem
Existing package-on-package (POP) structures face challenges in interfacing logic devices and memory devices during the packaging process, particularly due to mismatched pad spacings and orientations, which can lead to inefficiencies and compatibility issues.
Innovation Solution
The use of offset interposers that translate POP-side pads to align with land-side pads, allowing for a decoupling of interfacing challenges by matching pad spacings and orientations, and enabling direct contact via vias or traces, thus facilitating efficient assembly and integration of logic and memory devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional POP structures are used to interface logic devices and memory devices, then device integration is achieved, but pad spacing and orientation mismatches cause interfacing challenges and compatibility issues
Solution Approach 1:
An offset interposer is introduced as an intermediary component between the logic device and memory device. The interposer includes a first surface with first pads having first spacing and orientation, and a second surface with second pads having second spacing and orientation. The offset interposer translates the pad array from one spacing and orientation to another, enabling compatibility between devices with mismatched pad configurations while maintaining reliable electrical connections through conductive vias and traces.
2Productivity
If pad arrays are directly connected between logic and memory devices, then electrical connections are established, but mismatched pad spacings and orientations lead to assembly inefficiencies
Solution Approach 1:
The offset interposer serves as a mediator that handles the complexity of pad configuration translation. By incorporating the interposer, the assembly process benefits from standardized interfaces on both the logic device and memory device sides, while the interposer itself absorbs the complexity of transforming between different pad spacings and orientations. This enables more efficient assembly operations without requiring custom alignment procedures for each device pair.
Solution Approach 2:
The offset interposer implements parameter changes by transforming pad array characteristics between its two surfaces. The first pads are configured with specific spacing and orientation parameters, while the second pads have different spacing and orientation parameters. The interposer's internal conductive structures (vias and traces) enable the transformation of these geometric parameters, allowing devices with different pad configurations to be interconnected using standardized assembly processes.
3Area of stationary object
If keep-out zones are minimized to maximize device density, then area utilization improves, but underfill material may compromise electrical connections
Solution Approach 1:
The offset interposer acts as a protective intermediary that shields electrical connections from underfill material. By positioning the interposer between the logic device and memory device, it creates a physical barrier that prevents underfill from directly contacting and compromising the electrical connections. This allows for adequate keep-out zones to be maintained while still achieving high device density through the offset configuration that enables more efficient space utilization.
Data Source
AI summary
An offset interposer includes a land side including land-side ball-grid array (BGA) and a package-on-package (POP) side including a POP-side BGA. The land-side BGA includes two adjacent, spaced-apart land-side pads, and the POP-side BGA includes two adjacent, spaced-apart POP-side pads that are coupled to the respective two land-side BGA pads through the offset interposer. The land-side BGA is configured to interface with a first-level interconnect. The POP-side BGA is configured to interface with a POP substrate. Each of the two land-side pads has a different footprint than the respective two POP-side pads.