Leaded IC Stacking on Flex Circuit for Memory Card Reliability
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Solution Overview
Problem
Current techniques for stacking memory devices are not optimized for leaded packages, which are still widely used in the industry, limiting the leverage of testing and reliability advantages of TSOP packaged flash memory in memory cards.
Innovation Solution
A system and method for electrically and thermally coupling leaded packaged integrated circuit devices using a flex circuit structure, where leads of the IC packages are configured to contact the lower surface of the flex circuit, allowing for the creation of stacked modules in a memory card format.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If CSP stacking techniques are used for leaded packages, then miniaturization is achieved, but stacking efficiency and reliability are compromised
Solution Approach 1:
The invention segments the stacking process into distinct phases: lead configuration, lower surface contact establishment, and flex circuit positioning. This segmentation allows each aspect to be optimized independently, ensuring reliable electrical connections while achieving miniaturization.
Solution Approach 2:
The flex circuit acts as an intermediary element between the leaded IC packages. It provides a flexible substrate that accommodates the lead configurations and enables reliable electrical coupling while maintaining the compact stacked structure.
2Reliability
If TSOP packaged flash memory is used, then testing and reliability advantages are leveraged, but integration into memory card format is limited
Solution Approach 1:
The invention transitions from planar integration to three-dimensional stacking. By arranging TSOP packaged ICs in vertical stacks with leads extending to contact lower surfaces, it accommodates the specific form factor requirements of memory cards while preserving the reliability advantages of TSOP packaging.
Solution Approach 2:
The invention changes the spatial parameters of IC arrangement by configuring leads to extend from lateral sides and contact lower surfaces. This parameter change enables TSOP packages to be integrated in stacked configurations that comply with memory card dimensional requirements.
3Reliability
If leads are configured to contact lower surfaces, then electrical coupling is improved, but manufacturing complexity increases
Solution Approach 1:
The lead configuration is performed as a preliminary action before final IC placement. Leads are pre-positioned and configured to extend toward the lower surface contact points, simplifying the subsequent assembly process and improving electrical coupling reliability.
Data Source
AI summary
The present invention provides a system and method for employing leaded packaged memory devices in memory cards. Leaded packaged ICs are disposed on one or both sides of a flex circuitry structure to create an IC-populated structure. In a preferred embodiment, leads of constituent leaded IC packages are configured to allow the lower surface of the leaded IC packages to contact respective surfaces of the flex circuitry structure. Contacts for typical embodiments are supported by a rigid portion of the flex circuitry structure and the IC-populated structure is disposed in a casing to provide card structure for the module.