Movable Pyrometric Sensor for PCB Thermal Testing
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Solution Overview
Problem
Existing pyrometric scanning technologies for printed circuit boards face limitations in resolution and depth of field, particularly when dealing with uneven surfaces, as the fixed observation distance leads to inadequate resolution for large areas or small-scale structures, and varying resolutions due to surface topography.
Innovation Solution
A movable pyrometric sensor apparatus that adjusts its distance and position in three dimensions (X, Y, and Z directions) relative to the printed circuit board, allowing for flexible resolution and improved depth of field, enabling high-resolution scanning of arbitrary surfaces, including those with complex topographies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed observation distance is used for pyrometric scanning, then the apparatus structure is simple, but the resolution is invariable and insufficient for both large areas and small-scale structures
Solution Approach 1:
The patent applies the dynamics principle by making the observation distance adjustable rather than fixed. The sensor can dynamically change its distance from the printed circuit board surface, allowing optimization of resolution for different measurement scenarios. This transforms a static measurement system into a dynamic one that can adapt to varying requirements.
Solution Approach 2:
The patent introduces an additional degree of freedom by allowing the sensor to move not only in the scanning plane (X-Y directions) but also in the depth direction (Z-axis). This dimensional extension enables independent control of observation distance, separating it from the scanning motion and thereby achieving variable resolution without complicating the basic scanning mechanism.
2Reliability
If a fixed observation distance is used, then the scanning system is simple, but the depth of field varies with surface topography causing measurement errors on uneven surfaces
Solution Approach 1:
The system dynamically adjusts the observation distance in response to surface topography variations. When scanning uneven surfaces, the sensor can change its Z-position to maintain a constant distance from the surface, ensuring consistent depth of field and resolution across different heights. This dynamic compensation eliminates measurement errors caused by surface irregularities.
Solution Approach 2:
The patent implements feedback control where the system monitors the distance to the surface (potentially using focus detection or auxiliary sensors) and adjusts the sensor position accordingly. This closed-loop control ensures that the observation distance remains optimal regardless of surface variations, maintaining measurement reliability.
3Productivity
If the observation distance is increased to cover large areas, then the scanning speed improves, but the resolution becomes too coarse to detect small-scale defects
Solution Approach 1:
The system dynamically adapts the observation distance based on the required measurement precision. For large-area scanning where speed is critical, the sensor can operate at a greater distance. When small-scale defects need detection, the sensor automatically moves closer to the surface, increasing resolution without permanently sacrificing scanning efficiency.
Solution Approach 2:
The patent changes the observation distance parameter dynamically during operation. By adjusting this critical parameter, the system can optimize the balance between scanning speed and resolution for different measurement tasks, effectively resolving the contradiction between productivity and measurement precision.
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 allows for efficient and accurate temperature measurement across varying surface structures, ensuring sufficient resolution and maintaining a usable depth of field, thereby enhancing the ability to detect temperature deviations and defects on printed circuit boards.
Implementation Method 1
the pyrometric measurement principle, that is to say the principle of measuring a surface temperature from a distance
Data Source
AI summary
An apparatus for thermal testing of a printed circuit board being electrically energized and being unpopulated or populated with electrical or electronic components is disclosed. The apparatus includes a device for pyrometrical scanning of surface temperatures, wherein the scanning device comprises a pyrometric sensor being movable for the purpose of scanning and being adjustable with respect to its distance from the printed circuit board. A method for operating such an apparatus is disclosed. The method includes adjusting the distance between the sensor and the printed circuit board during scanning.