Flexible PCB Test Fixture With Deformable Probes
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Solution Overview
Problem
The increasing complexity of printed circuit boards (PCBs) with higher density designs results in reduced space for electrical test points and incomplete electrical test access, making existing test fixtures costly and inefficient for limited production runs, especially when switching between multiple PCB types or performing different tests.
Innovation Solution
A system comprising a test fixture with a plurality of probes and probe plates, where the probes are removably attached to an interface fixture, allowing for flexible alignment and contact with test points on PCBs, and a method for designing these fixtures to accommodate various PCB patterns using deformable probes and lateral offset arrangements to ensure effective contact without requiring specialized rewiring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bed-of-nails style customized test system is used, then testing capability for specific PCB designs is achieved, but cost becomes prohibitively high for limited production runs
Solution Approach 1:
The test fixture is designed with a standardized interface that can accommodate multiple PCB designs through interchangeable probe cards or reconfigurable probe arrangements. The fixture includes a base structure with standardized contact pads and a mechanism to adapt the probe configuration, allowing one fixture to serve multiple testing purposes rather than requiring dedicated fixtures for each PCB design.
Solution Approach 2:
The test system is divided into modular components: a permanent standardized interface fixture and removable or reconfigurable probe cards. This segmentation allows the expensive customized elements (probe cards) to be swapped based on production needs, while the base fixture remains constant and can be reused across different PCB types, reducing overall cost for limited production runs.
2Adaptability or versatility
If a flying probe tester is used, then adaptability to any PCB design is achieved, but throughput decreases when switching between multiple PCB types
Solution Approach 1:
The probe cards or probe configurations are pre-configured for specific PCB designs before production runs. This preliminary preparation allows quick switching between different PCB types without requiring time-consuming repositioning or recalibration during production, maintaining high throughput while preserving adaptability to different designs.
Solution Approach 2:
The test fixture incorporates dynamic elements such as movable probe cards, adjustable probe positions, or spring-loaded contact mechanisms that can quickly adapt to different PCB configurations. This dynamic capability enables rapid reconfiguration between PCB types while maintaining testing speed and throughput.
3Quantity of substance
If PCBs are designed with higher density, then functional capability increases, but space for electrical test points decreases
Solution Approach 1:
The test fixture utilizes the vertical dimension by employing probe cards that extend downward from the PCB surface, allowing test points to be accessed from the bottom side of the board. This enables testing of high-density PCBs without requiring additional lateral space, as the probing mechanism operates in the vertical dimension rather than competing for surface area.
Solution Approach 2:
The test fixture introduces intermediary contact pads and trace routing layers that extend test access to interior or densely packed circuit regions. By using intermediate connection points and distributed test access mechanisms, the system can test high-density circuits without requiring direct access to every test point on the surface, effectively bypassing the space constraint.
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 enables efficient and cost-effective testing of multiple PCB types using a standardized measurement system, reducing the need for costly customized test fixtures and improving throughput by allowing the same test fixture to be used for various PCB designs and tests.
Implementation Method 1
The method can also include the step of adjusting an alignment of the first and the second maps to increase a first number of the locations in the first map within a unique one of the contact pads in the second map
Data Source
AI summary
A system for testing an electronic circuit board (ECB) having a plurality of test points in a pre-defined arrangement on a measurement device having a plurality of resources includes an interface fixture having a plurality of contact pads arranged in an array on a first surface. The contact pads can be electrically coupled to the plurality of resources of the measurement system according to a pre-defined pattern, where at least two of the contact pads are electrically coupled to one of the plurality of resources in a many-to-one relationship. The system also includes a test fixture removably attached to the first surface of the interface fixture. The test fixture includes an upper probe plate having a plurality of openings and a lower probe plate parallel to the upper probe plate. The lower probe plate includes a plurality of openings associated with the openings in the upper probe plate. The test fixture also includes a plurality of probes extending through the associated openings in the upper and the lower probe plates, contacting one of the contact pads, and guided to test points of the ECB by the associated openings.