Adjustable Test Socket for Device Tolerance Compensation
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Solution Overview
Problem
The increasing variance in chip package size and pad pitch density makes it difficult to guarantee contact between spring probes and device pads in test sockets, leading to errors and rejection of otherwise good devices as defective.
Innovation Solution
The development of two- and four-wall adjustable test sockets, which feature adjustable side walls and cam mechanisms to center devices within a pocket, compensating for device tolerances and ensuring accurate contact between spring probes and pads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed test sockets are used, then manufacturing simplicity is maintained, but contact reliability deteriorates due to device tolerance variance
Solution Approach 1:
The test socket employs adjustable side walls that can be dynamically repositioned to accommodate variations in device package size and pad pitch. The side walls are movable along guide rails and can be locked at different positions, transforming the static socket structure into a dynamic one that adapts to different device specifications, thereby maintaining contact reliability despite device tolerance variance.
Solution Approach 2:
The socket structure allows for parameter changes in the form of adjustable side wall positions. By changing the position parameters of the side walls, the effective pocket dimensions are adjusted to match the specific device being tested, compensating for tolerance variations and ensuring reliable probe-to-pad contact across different device specifications.
2Adaptability or versatility
If adjustable side walls are added, then adaptability to device variations improves, but manufacturing complexity increases
Solution Approach 1:
The test socket is segmented into fixed portions and adjustable side wall portions. This segmentation allows the majority of the socket structure to remain simple and easy to manufacture, while only the critical side wall sections incorporate adjustment mechanisms. The segmented design minimizes the overall manufacturing complexity while providing the necessary adaptability.
Solution Approach 2:
The adjustable side walls serve multiple functions: they define the device pocket boundaries, provide adjustment for tolerance compensation, and guide device insertion. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in manufacturing complexity while achieving high adaptability.
3Measurement precision
If device pocket size is reduced, then measurement precision improves, but device centering becomes more difficult
Solution Approach 1:
Guide rails and guide surfaces are introduced as intermediary elements between the device and the adjustable side walls. These intermediaries facilitate smooth device insertion and automatic centering within the adjusted pocket, eliminating the difficulty of manual centering while maintaining the reduced pocket size necessary for precise pad contact.
Solution Approach 2:
The side walls are pre-adjusted to the correct position before device insertion. This preliminary action sets the optimal pocket dimensions and alignment, so that when the device is inserted, it automatically centers itself within the pre-configured boundaries, achieving both precise measurement and ease of operation.
Data Source
AI summary
An adjustable test socket for aligning an electronic device with spring probes in a test fixture is provided having two adjustable walls or four adjustable walls.