Flexible Contact Cell for Precise Kelvin Testing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The shrinking size of IC packages has made it difficult for traditional Kelvin clips to establish precise production-level electrical connections for measuring performance, as they are sensitive to electrical configurations and peripheral resistance, limiting effective Kelvin testing.
Innovation Solution
The use of contact cells with flexible polyimide ties and conductive elements that include tips, bends, and bases, arranged on a printed circuit board to establish precise connections with leadless packages, allowing for independent movement and reduced contact force, enabling accurate Kelvin testing without damaging the components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional Kelvin clips are used to establish electrical connections, then four electrical connections can be made with the DUT, but the shrinking size of IC packages makes it difficult to establish precise production-level connections and increases sensitivity to peripheral resistance
Solution Approach 1:
The contact cell is segmented into multiple functional parts: a base portion for PCB mounting, a bend portion for mechanical flexibility, and a tip portion for contacting the DUT. This segmentation allows each part to be optimized independently - the tip can be precisely positioned while the bend provides compliance, resolving the contradiction between measurement precision and ease of operation with shrinking packages
Solution Approach 2:
The contact cell incorporates a bend portion that provides dynamic compliance through elastic deformation. This allows the rigid tip to maintain precise contact positioning while the flexible bend adapts to manufacturing tolerances and package variations, enabling precise connections on shrinking IC packages without increasing sensitivity to peripheral resistance
2Reliability
If contact force is increased to ensure reliable electrical connection, then connection reliability improves, but the risk of damage to IC packages and test fixtures increases
Solution Approach 1:
The bend portion acts as a compliant element that dynamically adjusts contact force through elastic deformation. It provides sufficient force for reliable electrical connection while inherently limiting the maximum force to prevent damage, thus resolving the contradiction between connection reliability and damage risk
Solution Approach 2:
The contact cell uses a flexible bend portion that functions as a compliant mechanical element. This flexibility allows the structure to absorb excess force through deformation, ensuring reliable contact while protecting fragile IC packages and test fixtures from damage
3Manufacturing precision
If rigid contact structures are used to maintain precise positioning, then connection precision is maintained, but the structure becomes more sensitive to manufacturing tolerances and package variations
Solution Approach 1:
The bend portion provides dynamic compliance that compensates for manufacturing tolerances and package variations. The elastic deformation allows the rigid tip to maintain precise positioning while adapting to variations, resolving the contradiction between manufacturing precision and adaptability
Solution Approach 2:
The flexible bend portion acts as a compliant mechanism that absorbs dimensional variations through elastic deformation. This allows the contact tip to maintain precise electrical connection despite manufacturing tolerances in both the contact cell and the IC package
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for precise and reliable electrical connections with minimal peripheral resistance, improving the accuracy of performance measurements while reducing the risk of damage to the IC packages and test fixtures, thus enhancing the lifespan and reducing costs.
Implementation Method 1
a flexible polyimide tie 125... The tie 125 maintains the first and second elements 115, 120 in the illustrated position
Implementation Method 2
conductive elements that include tips, bends, and bases... to establish precise connections with leadless packages
Data Source
AI summary
According to an example embodiment, a contact cell includes a first element that is flexible and electrically conductive, and that is structured to have at least one bend along an entire length of the first element. The contact cell further includes a second element that is flexible and electrically conductive, and that is structured to have at least one bend along an entire length of the second element. The contact cell further includes a tie that is electrically non-conductive, and that is affixed to the first element and affixed to the second element such that the first element and second element are physically and electrically separated from each other.