Flash Memory Shunt Bypass for Defective Controller Testing
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Solution Overview
Problem
Conventional multi-chip packages (MCPs) with NAND flash memory controllers face challenges in testing and defect identification due to the lack of direct connectivity between the flash memory chip and external interfaces, making it difficult to diagnose and repair defective chips during mass production.
Innovation Solution
A shunt structure is implemented in the flash memory controller, allowing a switch to be set in short-circuit mode via a shunt activation signal, enabling direct data saving, retrieving, or testing from an external control terminal through the external transmission interface, bypassing the need for complex internal logic and allowing for external processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If NAND flash memory is packaged in multi-chip package (MCP) with controller, then storage capacity and processing speed are improved, but testing and defect identification become difficult due to lack of direct connectivity
Solution Approach 1:
The patent introduces a shunt structure that segments the signal path by providing an alternative bypass route around the flash memory controller. This allows test signals to reach the flash memory chip directly without passing through the controller, enabling independent testing of the memory chip while maintaining the integrated MCP architecture for normal operation.
Solution Approach 2:
The shunt acts as an intermediary element that mediates between the external test interface and the flash memory chip. During testing, the shunt provides a direct conductive path that bypasses the controller, allowing external terminals to communicate with the memory chip without the controller's intervention, thus solving the connectivity issue.
2Device complexity
If flash memory controller is integrated with NAND flash memory in MCP, then device complexity is reduced, but ease of repair deteriorates when controller becomes defective
Solution Approach 1:
The shunt is pre-configured in the circuit design but remains inactive during normal operation. When a controller defect is detected, the shunt can be activated to bypass the defective controller, providing a preliminary prepared solution that restores functionality without requiring physical replacement of the entire MCP module.
Solution Approach 2:
The patent enables the system to discard the defective controller from the signal path by activating the shunt bypass. The functional flash memory chip is then recovered and made accessible through the external interface, allowing the memory storage function to be preserved even though the controller is non-functional.
3Ease of manufacture
If conventional MCP design is used, then manufacturing is simplified, but defect location cannot be easily identified when connection interface is damaged
Solution Approach 1:
The shunt structure creates distinct testable segments in the signal path. By enabling direct access to the flash memory chip through the shunt, the patent allows testers to isolate and test individual components (controller vs. memory chip) separately, thereby accurately locating defects to specific segments rather than treating the entire MCP as a single black box.
Data Source
AI summary
A shunt activation signal is transmitted by an external control terminal through an external transmission interface to switch a flash memory controller in a shunt mode. The shunt activation signal of the external transmission interface can set up a switch as shunt. When the flash memory controller is defective due to errors or damage, the shunt mode enables the external control terminal to directly process data saving/retrieving to the flash memory chip or testing through the external transmission interface. Thus, the user need not purchase a new flash memory to replace the defective flash memory with the damaged flash memory controller.