Molded Circuit Module Layout for Reflow Delamination Relief
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Solution Overview
Problem
Existing electronic circuit modules experience delamination during multiple solder reflow processes, leading to connection defects due to thermal stress, especially when underfill material exceeds the mold member boundaries.
Innovation Solution
The design includes a first mold member that exposes a lower area of the circuit board's side surface, creating a housing space for excess underfill material, and a second mold member to cover the first circuit board, preventing delamination at boundaries and stress relief.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the mold member covers the entire side surface of the circuit board, then the structural integrity is improved, but delamination occurs during solder reflow due to thermal stress
Solution Approach 1:
The side surface coverage is segmented into two zones: an upper area covered by the mold member for structural support, and a lower area left exposed to prevent delamination. This segmentation allows the mold member to provide mechanical strength while avoiding thermal stress concentration at the boundary between the mold member and circuit board.
Solution Approach 2:
Different portions of the side surface are treated differently: the upper portion receives mold member coverage for structural integrity, while the lower portion remains exposed to reduce thermal stress. This local differentiation optimizes both structural strength and reliability by applying coverage only where mechanically necessary.
2Reliability
If underfill material is used to fill between circuit boards, then connection reliability is improved, but excess underfill material causes delamination at the mold member boundary during solder reflow
Solution Approach 1:
The lower area of the side surface is extracted from the mold member coverage zone, creating an exposed region that serves as a designated area for excess underfill material. This extraction prevents underfill material from accumulating at the harmful boundary between the mold member and circuit board, eliminating the delamination risk while preserving connection reliability.
3Adaptability or versatility
If multiple solder reflow processes are performed during multiplexed implementation, then manufacturing flexibility is improved, but delamination propagates due to repeated thermal loading
Solution Approach 1:
The lower exposed area of the side surface acts as a cushioning zone that absorbs and dissipates thermal stress before it can propagate to critical connection areas during repeated solder reflow processes. This pre-configured stress relief path protects the connection reliability while maintaining manufacturing flexibility for multiplexed implementation.
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 reduces the likelihood of connection defects by containing underfill material and allowing stress relief, even under thermal loads, thus enhancing the reliability of the electronic circuit module.
Implementation Method 1
A space formed between the end surface of the first mold member and the lower area of the side surface of the first circuit board serves as a housing part for an underfill material
Implementation Method 2
making delaminating occur at this portion allows stress relief. This can prevent a connection defect caused by delaminating due to a thermal load
Implementation Method 3
a first mold member that covers the upper surface of the first circuit board and a side surface thereof connecting the upper and lower surfaces so as to embed therein the electronic component
Data Source
AI summary
Disclosed herein is an electronic circuit module that includes a circuit board, an electronic component mounted on an upper surface of the circuit board, and a mold member that covers the upper and side surfaces of the circuit board. The lower area of the side surface of the circuit board is exposed so as not to be covered with the mold member.