PCB Pad Pitch Compensation for Soldering Thermal Expansion
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Solution Overview
Problem
Thermal expansion during the soldering process causes misalignment between component pins and electrically conductive pads on printed circuit boards (PCBs), leading to unreliable soldering joints due to differences in the coefficients of thermal expansion (CTE) between materials.
Innovation Solution
A method is developed to determine a relative expansion value between the CTE of a component and a PCB, and based on this, calculate a new pitch value for the electrically conductive pads to ensure proper alignment during the soldering process by adjusting their pitch value relative to the component pins, considering the change in temperature caused by the soldering process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pitch value of electrically conductive pads is designed to match component pins at room temperature, then initial alignment is achieved, but thermal expansion during soldering causes misalignment between pads and pins
Solution Approach 1:
The patent applies preliminary action by pre-calculating and adjusting the pitch value of electrically conductive pads before the soldering process. The pitch value is modified based on predicted thermal expansion differences between the PCB and component, so that when thermal expansion occurs during soldering, the pads and pins remain aligned. This proactive adjustment prevents misalignment rather than correcting it after the fact.
Solution Approach 2:
The patent changes the physical parameter of the pad pitch value to compensate for thermal expansion. By calculating the relative expansion between PCB and component materials and adjusting the pitch accordingly, the design accounts for temperature-induced dimensional changes. This parameter modification ensures that the expanded dimensions at soldering temperature result in proper alignment rather than misalignment.
2Manufacturing precision
If the pitch value of electrically conductive pads is adjusted to compensate for thermal expansion, then alignment during soldering is improved, but the design and manufacturing complexity increases
Solution Approach 1:
The patent replaces complex physical alignment mechanisms with a calculated pitch adjustment approach. Instead of using mechanical alignment features, adjustable fixtures, or complex positioning systems, the solution uses a straightforward mathematical calculation based on thermal expansion coefficients to determine the optimal pitch value. This substitution of mechanical complexity with computational simplicity reduces overall design complexity while maintaining high precision.
3Reliability
If the pitch value is adjusted based on thermal expansion calculations, then soldering joint reliability is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent performs the pitch value adjustment during the design and manufacturing preparation phase, before actual production. By pre-calculating the optimal pitch value based on material properties and expected temperature ranges, the complexity is resolved upfront rather than requiring complex real-time adjustments during manufacturing. This preliminary determination simplifies the actual manufacturing process.
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 approach effectively compensates for thermal expansion, ensuring accurate alignment and reliability of soldering joints by adjusting the pitch value of the electrically conductive pads to match the expansion of the component pins, thereby enhancing the reliability of the electrical circuit.
Implementation Method 1
differences in the coefficients of thermal expansion (CTE) between materials
Data Source
AI summary
Systems and methods are disclosed that may include identifying a first coefficient of thermal expansion for a first component, the first component including component pins having a first pitch value; identifying a second coefficient of thermal expansion for a second component, the second component associated with electrically conductive pads; determining a relative expansion value based on the first coefficient of thermal expansion and the second coefficient of thermal expansion; determining a change in temperature value of the first component and the second component, the change in temperature value indicating a change in temperature caused by a soldering process; and determining a second pitch value for the electrically conductive pads based on a product of the relative expansion value, the first pitch value, and the change in temperature value, the second pitch value causing an alignment between the component pins and the electrically conductive pads during the soldering process.