Wafer Probe Elastomer Support for Non-Planar Contact
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Solution Overview
Problem
Rigid wafer probes face challenges in establishing reliable electrical contact with non-planar microcircuits due to deflection under load, leading to gaps between probes and solder bumps, which affects the accuracy of wafer testing.
Innovation Solution
Incorporating an elastomer support between the test interconnect and interposer to minimize deflection and ensure proper alignment, allowing the rigid probes to maintain contact with the microcircuit's tilted surface by using a pre-compressed elastomer that provides initial compression support and rigid stability under load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid wafer probes are used to establish electrical contact with microcircuits, then structural stability and load-bearing capacity are improved, but deflection under load increases causing gaps between probes and solder bumps
Solution Approach 1:
An elastomer layer is introduced as an intermediary between the rigid interposer and the microcircuit. This elastomer layer has complementary elasticity that allows it to deform and fill gaps, ensuring continuous electrical contact between the rigid probe structure and the solder bumps even when the microcircuit surface is non-planar. The elastomer mediates between the rigid structure and the variable surface topology.
Solution Approach 2:
The patent utilizes the elastic properties of the elastomer material to change the mechanical parameters of the contact interface. The elastomer's ability to deform elastically under load and recover allows it to accommodate surface variations while maintaining contact force, transforming the rigid contact into a compliant yet stable connection.
2Manufacturing precision
If rigid probes are used for wafer testing, then manufacturing precision and structural stability are improved, but adaptability to non-planar microcircuit surfaces deteriorates
Solution Approach 1:
The elastomer layer serves as a mediator that bridges the rigid, precisely manufactured probe structure and the non-planar microcircuit surface. It allows the rigid probes to maintain their manufacturing precision while adapting to surface variations through the elastomer's deformability.
Solution Approach 2:
The elastomer layer functions as a flexible thin film that conforms to the non-planar surface of the microcircuit. This flexible layer allows the rigid probe structure to adapt to surface topology variations without compromising the precision of the probe alignment or the structural stability of the testing apparatus.
3Reliability
If pre-compressed elastomer support is added to reduce deflection, then contact consistency is improved, but device complexity increases
Solution Approach 1:
The elastomer layer is a simple intermediary component that provides pre-compression support between the interposer and the microcircuit. This single-layer solution improves contact consistency without requiring complex multi-component support structures, mechanisms, or adjustment devices.
Solution Approach 2:
The pre-compression of the elastomer is achieved by simple dimensional design of the elastomer layer thickness and positioning, rather than through complex mechanisms. The elastomer's inherent elastic properties are utilized to provide the necessary support force, avoiding the need for additional actuators, springs, or adjustment mechanisms.
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
The elastomer support structure effectively reduces deflection, ensuring consistent contact between rigid probes and solder bumps, enhancing the reliability and accuracy of wafer testing by accommodating non-planar microcircuit topologies.
Implementation Method 1
An elastomer between the test interconnect and the interposer reduces deflection of the test interconnect during a process of connecting the test interconnect to the microcircuit
Data Source
AI summary
A wafer test device includes a test interconnect to interface with a microcircuit of the wafer at a first side and an interposer to interface with the test interconnect at a second side of the test interconnect, opposite the first side. The interposer connects the test interconnect, via a printed circuit board (PCB), to a test apparatus that determines and controls test patterns that are applied to the microcircuit via the test interconnect. A support structure supports the test interconnect and the interposer. The support structure includes an inner bearing to tilt the test interconnect to match a tilt of a surface of the microcircuit. An elastomer between the test interconnect and the interposer reduces deflection of the test interconnect during a process of connecting the test interconnect to the microcircuit.