Probe Card Locking With Balance Adjustment for Wafer Alignment
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Solution Overview
Problem
The existing probe card systems experience significant load and instability when contacting wafers, leading to misalignment and potential errors in device testing due to uneven load distribution.
Innovation Solution
An apparatus and method that includes a test head, base unit, balance adjustment assemblies, sensors, and a controller to maintain equilibrium and stabilize the probe card-wafer connection by adjusting the length of balance adjustment assemblies based on displacement values measured by sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the probe card is in contact with the wafer to transmit test signals, then testing function is achieved, but significant large load (200 kg or more) is generated causing instability
Solution Approach 1:
The probe card system is divided into multiple independent probe cards, each supporting a portion of the total load. This segmentation distributes the 200 kg or more load across multiple cards, reducing the burden on each individual card and improving overall system stability while maintaining the testing function.
Solution Approach 2:
The patent introduces a new dimensional parameter - the number of probe cards in the array - to solve the load problem. Instead of increasing the strength of a single card, the system adds more cards in parallel, transforming a single-point load issue into a distributed multi-point load solution.
2Productivity
If the probe card is repeatedly in contact with the wafer, then testing is performed, but the contact state becomes unstable causing misalignment
Solution Approach 1:
The patent introduces balance adjustment assemblies that act as counterbalancing mechanisms. These assemblies include adjustable weights or spring mechanisms that counteract the downward force and imbalance caused by repeated contact, maintaining the probe card in a balanced state and preventing misalignment during continuous testing operations.
Solution Approach 2:
The system incorporates dynamic adjustment capabilities through balance adjustment assemblies that can adapt to changing load conditions during repeated testing. The assemblies allow real-time adjustment of balance parameters to compensate for wear, thermal expansion, or other dynamic factors that affect alignment precision over time.
3Stability of the object's composition
If the probe card is inclined due to load concentration, then contact is maintained, but load is concentrated on specific area causing test errors
Solution Approach 1:
By dividing the load across multiple probe cards arranged in an array, the system segments the concentrated load into distributed loads. Each probe card handles a specific portion of the total load, preventing load concentration on any single area and ensuring uniform contact pressure across all contact points, thereby maintaining test accuracy.
Data Source
AI summary
There is provided an apparatus for locking a probe card. The apparatus may comprise a test head including one or more test boards, a probe card. a base unit disposed between the test head and the probe card and coupled to each of the test head and the probe card, including a plurality of balance adjustment assemblies and a plurality of sensors measuring a plurality of displacement values of a plurality of points of the probe card and a controller determining whether the probe card is in an equilibrium state, based on the plurality of displacement values measured from the plurality of sensors, and controlling the probe card to be in an equilibrium state by adjusting a length of at least one of the plurality of balance adjustment assemblies when it is determined that the probe card is out of the equilibrium state.