Tamper-Resistant Keypad with Multi-Layer PCB and Security Circuit
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Solution Overview
Problem
Existing keypads lack effective resistance to tampering attempts, which can compromise sensitive information such as PINs or financial data, and often do not display visible signs of tampering, allowing unauthorized access.
Innovation Solution
A keypad design featuring a multi-layer printed circuit board with conductive pathways, a flexible security circuit, and a hardened steel collar to prevent access to connectors, along with a silicon-rubber keypad actuator and tamper-resistant materials, which detect and respond to tampering attempts by erasing information and limiting access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard keypad design is used, then ease of manufacture and basic functionality are maintained, but resistance to tampering and vandalism is insufficient
Solution Approach 1:
The keypad is divided into multiple functional layers including a front panel with keycaps, a multi-layer printed circuit board, a flexible security circuit, and a rear backer. This segmentation allows each layer to be optimized for specific functions (input, processing, security detection) while collectively providing enhanced tamper resistance without requiring complete redesign of the entire device.
Solution Approach 2:
The keypad employs composite construction combining rigid materials (housing, circuit board) with flexible security circuits and silicon-rubber actuators. The multi-layer printed circuit board integrates conductive pathways, security features, and connector terminals in a single composite structure, achieving both functionality and tamper resistance.
2Reliability
If connectors are exposed for easy connection, then ease of installation is improved, but access to connectors becomes vulnerable to tampering
Solution Approach 1:
The connectors are nested within the housing structure, with connector terminals integrated into the multi-layer printed circuit board and protected by the housing walls. The rear backer further encloses the connectors, creating a nested protective structure that requires disassembly of multiple components to access, thereby preventing easy tampering while maintaining proper electrical connectivity.
3Reliability
If sensitive data is stored in the keypad, then functionality is improved, but vulnerability to data theft through tampering increases
Solution Approach 1:
The flexible security circuit and multi-layer printed circuit board incorporate preliminary anti-tampering measures including conductive pathways designed to detect intrusion attempts, breakable security elements that trigger data erasure, and structural features that show visible signs of tampering. These preventive measures are built into the keypad structure before any tampering occurs, automatically counteracting potential data theft attempts.
4Reliability
If a simple housing structure is used, then ease of manufacture is improved, but resistance to vandalism and environmental factors deteriorates
Solution Approach 1:
The housing is segmented into a front panel, main housing body, and rear backer, allowing each component to be manufactured separately using standard processes and then assembled. This segmentation maintains ease of manufacture while enabling the incorporation of vandal-resistant features in each individual component and their interlocking assembly.
Solution Approach 2:
The housing structure combines multiple materials and layers including the front panel with openings, the multi-layer printed circuit board, flexible security circuit, and rear backer. This composite construction provides enhanced resistance to vandalism and environmental factors while being manufacturable using conventional techniques for each layer.
Data Source
AI summary
A tamper-resistant or tamper-evident keypad device for use in secure transactions. The keypad comprises multiple security mechanisms to prevent tampering to the device, and thus access to users' private information. The keypad is made of resilient materials and contains a tamper-resistant collar for housing the keypad's connector interface. The keypad comprises a multi-layered printed circuit board with at least two internal security-shield layers comprising switch trace protection, as well as additional security layers for tamper protection. The keypad comprises a silicon-rubber keypad actuator that engages tamper switches on the flexible security circuit. The keypad comprises an optional dome layer.