Board Preheating Control Using Thermal Imaging Feedback
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Solution Overview
Problem
Existing soldering machines struggle with temperature deviations due to bulb or fan deterioration, leading to hot and cold spots, board warpage, thermal damage, and inefficient flux activation, which are often undetected by single-point temperature measurement.
Innovation Solution
A method using thermal imaging cameras to obtain a temperature profile of the board, adjusting electrical power to heating units to optimize heat distribution, and monitoring trends for maintenance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-point temperature measurement is used, then device complexity is reduced, but temperature distribution uniformity deteriorates due to undetected hot and cold spots
Solution Approach 1:
The patent transitions from single-point temperature measurement to two-dimensional thermal imaging measurement. The thermal imaging camera captures temperature distribution across the entire board surface simultaneously, adding spatial dimensionality to the measurement process. This enables detection of hot and cold spots that would be invisible to single-point probes, thereby improving temperature distribution uniformity without significantly increasing system complexity.
Solution Approach 2:
The patent replaces mechanical contact-based temperature probes with optical-based thermal imaging cameras. This substitution eliminates the need for physical contact with the board, allowing non-intrusive full-surface temperature mapping. The optical measurement system captures thermal radiation patterns, providing comprehensive temperature distribution data without the limitations of point-by-point mechanical measurement.
2Stability of the object's composition
If multiple temperature gauges are used to measure multiple locations, then temperature distribution uniformity improves, but device complexity and cost increase
Solution Approach 1:
The patent merges multiple temperature measurement functions into a single thermal imaging camera system. Instead of deploying numerous independent temperature gauges across the board, one thermal imaging device captures the entire temperature distribution map simultaneously. This consolidation achieves comprehensive multi-point monitoring while reducing the number of separate measurement devices, cables, and data processing channels required.
Solution Approach 2:
The thermal imaging camera serves multiple measurement locations and functions simultaneously. A single device can monitor the entire board surface, track temperature changes over time, identify hot and cold spots, and provide real-time feedback for heating control. This multi-functional capability replaces what would otherwise require multiple specialized temperature probes positioned at different locations.
3Temperature
If heating unit power is increased to compensate for bulb deterioration, then temperature adequacy improves, but overheating and thermal damage worsen
Solution Approach 1:
The patent implements real-time feedback control using thermal imaging cameras to monitor board temperature distribution during the heating process. The system continuously captures temperature maps, analyzes hot and cold spot patterns, and adjusts heating unit power accordingly. This closed-loop feedback enables dynamic compensation for bulb deterioration by selectively increasing power to specific heating zones rather than uniformly increasing total power, thereby preventing overheating in already-warm areas while ensuring adequate heating in cold spots.
Solution Approach 2:
The patent applies localized heating control based on spatial temperature distribution patterns. Instead of uniformly adjusting the entire heating unit's power output, the system selectively modulates power to individual heating zones or bulbs based on real-time thermal imaging data. This local quality approach allows targeted compensation for deteriorating bulbs in specific areas without subjecting the entire board to excessive heat, thereby preventing thermal damage while maintaining temperature adequacy.
4Temperature
If preheating time is extended to ensure thorough heating, then temperature adequacy improves, but productivity deteriorates due to slower processing
Solution Approach 1:
The patent implements dynamic preheating control where heating parameters are continuously adjusted based on real-time thermal imaging feedback. The system transitions from static, fixed-duration preheating cycles to dynamic, adaptive heating processes. The preheating time and power levels are automatically optimized for each board based on its actual temperature distribution, allowing shorter processing times for boards that heat quickly while ensuring adequate heating for boards requiring more time, thereby maintaining productivity while ensuring temperature adequacy.
Solution Approach 2:
The patent uses thermal imaging cameras to perform preliminary assessment of board thermal characteristics before and during preheating. By monitoring temperature distribution in real-time, the system can predict heating requirements and adjust preheating parameters proactively. This preliminary action enables the system to optimize preheating duration for each board, avoiding unnecessary extension of preheating time for boards that are already adequately heated, thereby maintaining high processing speed while ensuring temperature adequacy.
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
Ensures even preheating, prevents overheating, reduces warpage, and maintains flux effectiveness by adjusting heat distribution and predicting component failures.
Implementation Method 1
obtain a profile of heat output from the heating unit and/or a temperature profile of the board
Implementation Method 2
The heating unit may comprise an infra-red (IR) heating unit which comprises strips of IR bulbs. Heat emission from the IR bulbs is controlled by controlling the voltage supplied to the IR bulbs.
Implementation Method 3
The heating unit may comprise a forced convection preheating unit. In forced convection preheating, at least one electrical heater is situated between at least one fan and the electronics board. The heater/s emit heat, and the fan/s create air flow to transport the heat to the board.
Data Source
Figure 1~2
Figure 3~5
Figure 4A~4H
AI summary
The present application relates to a method of controlling a preheating process for preheating a board (2) in preparation for processing of the board (2) in a soldering machine involves: providing a heating unit (11) configured to heat a surface of the board (2), for example a calibration board or an electronics board; providing the board (2) to the heating unit (11); providing electrical power to the heating unit (11) such that the heating unit emits heat; obtaining a profile of heat output from the heating unit (11) and/or a temperature profile of the board (11); and adjusting the electrical power provided to the heating unit (11) to adjust the heat output from the heating unit (11) to the board (11). The present application relates also to a method of maintaining a preheating system and to a preheating apparatus