Interposer Warpage Control via Two-Step Reflow and Underfill
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Solution Overview
Problem
Conventional methods for forming semiconductor devices, such as stacked packages, often result in device warpage, excess mechanical stress, and unreliability.
Innovation Solution
A method involving a two-step reflow process for attaching an interposer to a substrate and a semiconductor die, where the interposer is initially bent and then flattened, combined with the formation of underfill in spaces between the substrate, interposer, and semiconductor die to reduce warpage and stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional methods are used to form stacked packages, then manufacturing process is simple, but device warpage and mechanical stress increase
Solution Approach 1:
The patent segments the attachment process into multiple reflow stages (first reflow for interposer attachment, second reflow for die attachment). This segmentation allows controlled thermal processing at different stages, reducing cumulative warpage while maintaining manufacturing feasibility through standardized reflow techniques.
Solution Approach 2:
The interposer is pre-bent before attachment to anticipate and compensate for warpage that will occur during subsequent reflow processes. This preliminary action counteracts the expected deformation, resulting in a flatter final assembled structure with reduced warpage.
2Ease of manufacture
If conventional stacking methods are used, then manufacturing is straightforward, but mechanical stress and unreliability increase
Solution Approach 1:
Underfill material is applied beforehand to the substrate or interposer surface before attachment. This underfill acts as a cushioning layer that absorbs and distributes mechanical stress during and after the reflow process, preventing stress concentration that would lead to solder joint failure and improving overall device reliability.
Solution Approach 2:
The patent employs controlled reflow temperature profiles and timing parameters to optimize the attachment process. By carefully managing thermal parameters (temperature, time, heating rate) during each reflow stage, the process achieves reliable solder joint formation while minimizing thermal stress and warpage that would compromise reliability.
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 minimizes warpage and stress in semiconductor devices, enhancing their reliability and manufacturing efficiency.
Implementation Method 1
mounting an interposer on the substrate and attaching the interposer to the substrate by a first reflow process, mounting a semiconductor die on the interposer and attaching the semiconductor die to the interposer by a second reflow process
Implementation Method 2
forming (e.g., injecting, etc.) an underfill in spaces (or regions) between the substrate and the interposer and between the interposer and the semiconductor die
Data Source
AI summary
A method for manufacturing a semiconductor device, for example formed utilizing component stacking. As non-limiting examples, various aspects of this disclosure provide a method for reducing warpage and/or stress in stacked semiconductor devices.