Memory Test PCB Design for Accurate Defect Detection
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Solution Overview
Problem
Conventional memory test devices often misjudge the functionality of actual memory devices due to internal defects, leading to low detection accuracy of defects in test sockets, as the input test signals are not accurately measured during testing.
Innovation Solution
A method for designing a printed circuit board with calculated package capacitance, inductance, and chip capacitance, determining signal line and ground line lengths, and incorporating stitch capacitors to match the operation characteristics of actual memory devices, allowing for accurate detection of internal defects in memory test devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional memory test devices are used with standard test sockets, then the testing process is simple and fast, but the detection accuracy of internal defects is low due to inability to accurately measure input test signals
Solution Approach 1:
A test board is introduced as an intermediary component between the memory device under test and the test socket. The test board includes a measurement section with signal lines that extend from the socket contact to the memory device contact, enabling accurate measurement of input test signals. This intermediary structure allows the test device to detect internal defects by measuring signals at multiple points without fundamentally changing the overall testing workflow.
Solution Approach 2:
The test board is divided into distinct functional sections: a socket contact section that interfaces with the test socket, a measurement section with signal lines for measuring input signals, and a memory device contact section that interfaces with the memory device. This segmentation allows each section to be optimized for its specific function while working together to improve overall detection accuracy.
2Measurement precision
If signal line length in the test board is not properly controlled, then the manufacturing process is simpler, but the operation characteristics differ from the actual memory device reducing measurement accuracy
Solution Approach 1:
The signal lines in the measurement section are designed with specific length parameters that match the operation characteristics of the actual memory device. By controlling the length parameter of the signal lines, the test board replicates the electrical characteristics of the memory device package, enabling accurate measurement of input signals and defect detection.
Data Source
AI summary
In a method of designing a printed circuit board, a package capacitance, a package inductance, and a chip capacitance of an actual memory device are calculated. A signal line capacitance and a signal line inductance per unit length of a signal line are calculated based on characteristics of the printed circuit board. A length of the signal line for each pin is determined based on the package capacitance and the signal line capacitance.