Segmented Solder Pads for Electronic Device Assembly
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Solution Overview
Problem
In electronic devices using surface mounted technology, the traditional through hole technology leads to large solder points and uneven solder paste application, causing tombstoning issues, increased stress, and deformation risks due to miniaturization demands and lack of rigid support in Fan-Out Wafer Level Package assemblies.
Innovation Solution
The electronic device features a circuit board with spaced solder pads and reduced solder material application, allowing precise bonding and stress distribution across multiple pads, reducing the risk of tombstoning and deformation during high-temperature reflow processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder paste is applied in large amounts to ensure proper bonding, then bonding reliability is improved, but the electronic element may tilt or offset during reflow causing tombstoning
Solution Approach 1:
The solder pad is divided into multiple sub-pads (first solder pad and second solder pad) with a gap between them. This segmentation allows the solder material to be distributed more evenly across multiple smaller bonding areas, preventing excessive solder accumulation at any single location that would cause tombstoning, while still providing sufficient total bonding area for reliable connection.
2Area of moving object
If solder pad size is reduced to meet miniaturization requirements, then device compactness is improved, but the amount of solder material is reduced leading to insufficient bonding
Solution Approach 1:
Instead of using a single large solder pad, the invention uses multiple smaller solder pads (first and second solder pads) arranged in sequence. The total bonding area is maintained by distributing the connection across multiple pads, ensuring sufficient solder material for reliable bonding while keeping the overall footprint compact to meet miniaturization requirements.
Solution Approach 2:
The solder pads are arranged in a linear sequence along the length of the electrode terminal rather than spreading out laterally. This dimensional arrangement allows the bonding area to be extended in one direction (length) while maintaining compactness in other directions (width), effectively increasing bonding capacity without increasing overall device area.
3Strength
If high temperature reflow process is used to ensure proper solder bonding, then bonding strength is improved, but heat-induced deformation of circuit layer increases
Solution Approach 1:
The segmented solder pad configuration distributes the heat absorption and thermal stress across multiple smaller bonding areas. This prevents excessive heat concentration at any single location, reducing the risk of localized overheating and heat-induced deformation of the circuit layer while still achieving sufficient bonding strength through the cumulative effect of multiple solder joints.
4Stress or pressure
If electrode terminal area is increased to reduce stress, then stress distribution is improved, but the risk of delamination during assembly increases
Solution Approach 1:
The electrode terminal's bonding area is segmented into multiple smaller solder pads rather than using a single large continuous pad. This segmentation reduces the stress concentration that would occur at any single large bonding interface, distributing mechanical stress more evenly across multiple smaller joints. Simultaneously, the reduced individual pad sizes minimize the overall stress footprint on the thin circuit board, preventing delamination during assembly.
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 configuration prevents offset and delamination issues, maintains compactness, and reduces heat-induced deformation risks, ensuring precise assembly and reliability in miniaturized electronic components.
Implementation Method 1
the solder paste 12 is then reflowed, such that the electrode terminal 110 of the electronic element 11 is electrically connected to the solder pads 100
Data Source
AI summary
An electronic device includes a circuit board having a plurality of conductive contacts, and an electronic component disposed on the circuit board and having a plurality of electrode terminals. The conductive contacts include a plurality of solder pads spaced apart from each other, and are coupled to the electrode terminals, respectively. The stress generated by any one of the electrode terminals is distributed to all of the solder pads so as to prevent the electronic component from being offset during an assembly process.