PCB Temperature Profiling Pads for Accurate Reflow Measurement
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Solution Overview
Problem
Current reflow profiling techniques for printed circuit boards (PCBs) using thermocouple wires to measure temperature during the reflow soldering process damage the PCB and provide inaccurate readings due to difficulty in ensuring contact with test points beneath electronic components.
Innovation Solution
A printed circuit board design with a predetermined temperature profiling location, typically a connection pad at the center of a grid, connected via traces to perimeter test pads, allowing a temperature measurement device to accurately measure temperatures without drilling holes, thus preserving the PCB for reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermocouple wires are threaded through drilled holes to reach test points beneath electronic components, then temperature data can be obtained from these test points, but the PCB is damaged and rendered unusable
Solution Approach 1:
The patent applies preliminary action by pre-configuring trace routes during PCB manufacturing that extend from central connection pads to perimeter test pads. This allows temperature measurement without subsequent drilling or modification, preserving the PCB while enabling accurate temperature data acquisition at locations that would otherwise require invasive access
Solution Approach 2:
The patent uses trace routes as an intermediary mechanism to transfer thermal measurement capability from inaccessible central test points to accessible perimeter locations. The traces act as conductive pathways that extend the measurement function without requiring physical access to the original test point location, thus avoiding PCB damage
2Measurement precision
If thermocouple wires are attached to test points to obtain temperature readings, then temperature profiling can be performed, but it is difficult to determine whether the wires have made contact with the test point, leading to inaccurate readings
Solution Approach 1:
The trace routes serve as visible intermediaries that provide a guaranteed conductive path from the temperature measurement device to the central connection pad. By routing through the PCB substrate, the traces make the electrical connection visible and verifiable, eliminating uncertainty about whether the thermocouple is properly contacted to the test point
Solution Approach 2:
The patent replaces the mechanical attachment method (threading wires through holes and making direct contact with test points) with an electrical trace-based system. This substitution provides a more reliable and verifiable connection method, as the trace routes can be visually inspected and electrically tested to confirm proper connectivity before temperature measurement begins
3Measurement precision
If holes are drilled into the PCB to access test points beneath electronic components, then temperature data can be obtained, but the PCB cannot be reused
Solution Approach 1:
The trace routes are incorporated into the PCB design during manufacturing, before the PCB is put into service. This preliminary configuration of measurement pathways eliminates the need for subsequent drilling or modification, allowing the PCB to be reused multiple times without damage while maintaining temperature measurement capability
Solution Approach 2:
The PCB design integrates dual functionality: the trace routes serve both as electrical connection paths for normal circuit operation and as temperature measurement pathways. This multi-functionality allows the same PCB structure to support both operational and measurement roles, enabling reuse without sacrificing measurement capability
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 accurate temperature readings during reflow soldering, reduces PCB damage, and allows for multiple uses of the PCB by avoiding the need for drilling holes, improving solder connectivity and reducing defects.
Implementation Method 1
A trace extends from an identified connection pad of the grid of connection pads to the test pad
Data Source
AI summary
A printed circuit board (PCB) includes an identified temperature profiling location. The identified temperature profiling location may be a connection pad from a grid of connection pads on the PCB. The connection pad may be located near a center of the grid of connection pads. The connection pad may be coupled to a no-connect pin of an electronic component that is surface mounted to the PCB. Traces extend from the connection pad to test pads provided near a perimeter of the grid of connection pads. A temperature measurement device may be coupled to the test pads, which enables the temperature measurement device to capture accurate temperature readings underneath the electronic component during a reflow profiling process.