Supplementary Component for BGA Solder Stress Reduction
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Solution Overview
Problem
When large BGA components are mounted on both surfaces of a printed wiring board, the solder-mounting surface faces excessive stress due to thermal deformation and external stress, leading to potential failure of the bonded condition, and reinforcing the BGA component's solder-mounting surface with a back plate is not feasible when components overlap.
Innovation Solution
A supplementary component with an integrated heat-sink and reinforcement portion is placed on the second surface of the printed wiring board, acting as a heat-sink to remove heat from circuit components and reinforcing the first component mounting portion to prevent warping and stress on the solder-bonded areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a back plate is provided to reinforce the BGA component solder-mounting surface, then the reliability of the solder-bonded portions is improved, but the device complexity increases and the component cannot be mounted on overlapping surfaces
Solution Approach 1:
The patent combines the heat-sink function and reinforcement function into a single supplementary component. This component has a first portion that contacts the circuit component to sink heat, and a second portion that reinforces the mounting portion of the BGA component on the opposite surface. By merging these two functions into one component, the patent avoids the complexity of separate back plates while maintaining reliability.
Solution Approach 2:
The supplementary component serves multiple functions simultaneously: it acts as a heat-sink to remove heat from the circuit component, and as a reinforcement structure to prevent warping and stress on the BGA component's solder-bonded portions. This multi-functionality eliminates the need for separate components and enables component mounting on overlapping surfaces.
2Productivity
If BGA components are mounted on both surfaces of the printed wiring board, then the productivity and integration density are improved, but the solder-mounting surface is subjected to excessive stress from thermal deformation
Solution Approach 1:
The patent addresses the stress problem by moving the reinforcement function to the opposite surface of the printed wiring board. The supplementary component on the second surface reinforces the mounting portion of components on the first surface, effectively counteracting thermal deformation stresses from both sides of the board.
3Stress or pressure
If a back plate is provided to reinforce the BGA component, then the stress on solder-bonded portions is reduced, but the heat dissipation capability is insufficient when components overlap
Solution Approach 1:
The patent merges the heat-sink function and reinforcement function into a single supplementary component. This component has a first portion that contacts the circuit component to sink heat, and a second portion that reinforces the mounting portion of the BGA component on the opposite surface. By merging these two functions into one component, the patent avoids the complexity of separate back plates while maintaining reliability.
Solution Approach 2:
The supplementary component serves multiple functions simultaneously: it acts as a heat-sink to remove heat from the circuit component, and as a reinforcement structure to prevent warping and stress on the BGA component's solder-bonded portions. This multi-functionality eliminates the need for separate components and enables component mounting on overlapping surfaces.
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
The supplementary component effectively reduces stress on the solder-bonded areas by reinforcing the mounting portion and efficiently dissipating heat, preventing peeling off of the solder-bonded portions and enhancing the reliability of the printed wiring board assembly.
Implementation Method 1
a supplementary component which is provided on the second surface of the printed wiring board and functions as a heat-sink portion to remove heat produced from the circuit component
Implementation Method 2
the printed wiring board will warp due to the thermal deformation or external stress
Data Source
AI summary
According to one embodiment, there is provided a printed wiring board assembly composed of a printed wiring board having a first component mounting portion provided on one surface of the printed wiring board, a second component mounting portion provided on the other surface of the printed wiring board having the second component mounting portion overlapped partially with the first component mounting portion, a large-scaled ball grid array component mounted on the first component mounting portion, a circuit component mounted on the second component mounting portion, and a supplementary component which is provided on the second component mounting portion of the printed wiring board having a first portion functioning as a heat-sink to remove heat generated from the circuit component and a second portion functioning as a reinforcement portion to reinforce the first component mounting portion.