PCB Substrate Tear Initiation for Tamper-Responsive Security
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Solution Overview
Problem
Printed circuit boards (PCBs) face unauthorized access and tampering, with malicious actors attempting to obtain data, disable functions, or gain network access by overcoming component enclosures.
Innovation Solution
Incorporating tear initiation sites and delamination mechanisms in PCBs, using weakened bonding or trench structures, to ensure that upon tampering, the security circuits are severed, disabling the component and preventing further access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tamper enclosures are adhesively bonded to protected components and PCB surfaces, then security protection is improved, but ease of manufacture deteriorates due to complex bonding processes and quality control requirements
Solution Approach 1:
The patent creates tear initiation sites during PCB manufacturing before tamper enclosures are installed. These pre-formed weaknesses in the substrate or adhesive layers enable controlled delamination when tampering occurs, eliminating the need for complex bonding processes while maintaining security. The tear initiation sites are prepared in advance through methods like creating trenches, reducing layer sizes, or applying weakened bonding in specific regions.
Solution Approach 2:
The PCB structure is segmented into regions with different bonding characteristics. The patent creates distinct zones including strong bonding areas for component attachment and weak bonding areas (tear initiation sites) for controlled failure. This segmentation allows the PCB to maintain structural integrity where needed while providing predictable failure modes for security purposes, simplifying the overall manufacturing process.
2Reliability
If tear initiation sites are added to enable controlled delamination upon tampering, then security response capability is improved, but device complexity increases due to additional structural features
Solution Approach 1:
The patent applies local quality changes by creating tear initiation sites only in specific regions of the PCB where controlled delamination is desired. These local modifications involve changing material properties or structural characteristics in targeted areas (such as reducing dielectric layer size or creating adhesive-free zones) while leaving the rest of the PCB structure unchanged, thus maintaining overall simplicity.
Solution Approach 2:
The patent modifies physical parameters of the PCB structure at tear initiation sites, such as reducing dielectric layer thickness, changing adhesive bonding strength, or creating geometric features like trenches. These parameter changes create predictable failure points without requiring complex additional components or mechanisms, maintaining device simplicity while enhancing security response capability.
3Reliability
If internal layers are reduced in size to form inserted steps, then delamination control is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent incorporates size-reduced internal layers during the PCB lamination process itself, rather than adding them as post-manufacturing features. These pre-formed inserted steps create controlled delamination paths when tampering occurs. By integrating this feature into the standard manufacturing process, the precision requirements are managed through established fabrication capabilities rather than requiring additional precision operations.
Data Source
AI summary
A structure of a circuitry substrate for securing an area from tampering is disclosed. The structure includes a circuitry substrate with at least one of a top tamper enclosure and a bottom tamper enclosure covering a component in a protected area of the circuitry substrate. The top and bottom tamper enclosures are adhesively bonded to a surface of the circuitry substrate, and a tear initiation site is added to a side of the perimeter of circuitry substrate bordering the protected area that includes at least one tamper enclosure, such that the tear initiation site is located and configured to enable propagation of a delamination of at least one internal layer of the circuitry substrate and a severing of a security circuit when a removal force is applied to the at least one of the top tamper enclosure and the bottom tamper enclosure.