Capacitive Pressure Sensor for Probe Card Contact Load Control
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Solution Overview
Problem
Conventional inspection apparatuses face challenges in performing high-temperature inspections with high reliability due to thermal expansion of probe cards, leading to excessive contact load and potential damage, requiring preheating that increases total inspection time.
Innovation Solution
An inspection apparatus with a movable mounting table and pressure sensors to detect and adjust contact load in real-time, preventing damage by compensating for probe card expansion without preheating, ensuring stable contact through capacitive pressure sensors and an elevation driving mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the probe card is preheated before high-temperature inspection, then thermal expansion is reduced and contact load stability is improved, but total inspection time increases significantly
Solution Approach 1:
The probe card is preheated before the high-temperature inspection to allow thermal expansion to occur in advance. This preliminary thermal conditioning stabilizes the probe card dimensions and probe positions, ensuring consistent contact load during the actual inspection process while preventing thermal shock damage.
Solution Approach 2:
The temperature parameter of the probe card is changed gradually through controlled preheating. By adjusting the temperature profile and duration, the system optimizes the balance between achieving sufficient thermal stabilization and minimizing the time penalty, allowing the probe card to reach thermal equilibrium before inspection begins.
2Manufacturing precision
If the mounting table is overdriven by a preset amount, then alignment precision is maintained, but thermal expansion of the probe card causes excessive contact load and potential damage
Solution Approach 1:
Pressure sensors are installed between the mounting body and support body to detect the actual contact load in real-time. The control unit receives feedback from these sensors and dynamically adjusts the overdrive amount, compensating for thermal expansion effects. This closed-loop control maintains appropriate contact load while preserving alignment precision despite temperature variations.
3Productivity
If the probe card is not preheated, then inspection time is reduced, but contact load becomes unstable and damage risk increases
Solution Approach 1:
A rapid preheating process is implemented to quickly bring the probe card to the inspection temperature before contact occurs. This preliminary thermal conditioning minimizes the time penalty while ensuring the probe card undergoes thermal expansion in advance, stabilizing probe positions and contact load for reliable inspection.
Solution Approach 2:
The temperature parameter is rapidly changed through controlled preheating to achieve thermal stabilization in minimal time. By optimizing the heating rate and duration, the system balances the need for quick inspection with the requirement for stable contact load, reducing both preheating time and damage risk.
4Reliability
If pressure sensors are added to detect contact load, then contact load control is improved, but device complexity increases
Solution Approach 1:
Capacitive pressure sensors are used to detect contact load, replacing more complex mechanical measurement systems. These sensors provide accurate contact load measurement through electrical capacitance changes, simplifying the overall system while improving reliability through non-contact sensing that requires minimal mechanical intervention.
Solution Approach 2:
The pressure sensing system serves multiple functions: detecting contact load magnitude, monitoring probe-card mounting status, and providing feedback for dynamic overdrive adjustment. This multi-functionality justifies the added complexity by consolidating several monitoring and control tasks into a single integrated sensor system.
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
Enables high-reliability high-temperature inspections by maintaining appropriate contact load without preheating, preventing damage to probe cards and semiconductor wafers, and reducing overall inspection time.
Implementation Method 1
pressure sensors (15) formed as capacitive pressure sensors are provided between the mounting body (11) and the support body (12)
Implementation Method 2
the probes 3A are thermally expanded while being directly heated by the semiconductor wafer W on the mounting table 1. Further, the main body of the probe card 3 is thermally expanded while being gradually heated
Data Source
AI summary
An inspection apparatus includes a movable mounting table for mounting thereon a target object, a probe card disposed above the mounting table and a control unit for controlling the mounting table. The target object is inspected by bringing a plurality of electrode pads of the target object mounted on the mounting table into contact with a plurality of probes of the probe card with a predetermined contact load by overdriving the mounting table. Further, the mounting table includes a mounting body whose temperature is controllable, a support body for supporting the mounting body, an elevation driving mechanism provided in the support body and pressure sensors provided between the mounting body and the support body to thereby detect the contact load. The control unit controls the elevation driving mechanism in accordance with detection signals from the pressure sensors.