Conductive Underfill Dam Layout for Uniform EMI Shield Grounding
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Solution Overview
Problem
Conventional semiconductor device assemblies face challenges in providing adequate electromagnetic interference (EMI) shielding due to directional sputtering techniques, which result in thinner coatings on vertical sidewalls and compromised grounding connections, leading to performance issues and unreliable electrical contact.
Innovation Solution
The implementation of a grounded underfill dam that constrains the underfill material to cover the vertical sidewalls of semiconductor dies, creating a sloped surface for uniform sputtered EMI shield formation and ensuring reliable electrical connection to grounding pads before underfill dispensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If directional sputtering technique is used to form EMI shield, then the EMI shield can be formed on the semiconductor die, but the coating thickness on vertical sidewalls becomes non-uniform and thinner
Solution Approach 1:
The underfill dam is formed before dispensing the underfill material, creating a pre-defined containment structure. This preliminary action ensures that when underfill is added, it is automatically constrained within the dam boundaries, preventing lateral flow and creating a uniform vertical sidewall surface that enables uniform EMI shield coating during subsequent sputtering processes.
Solution Approach 2:
The underfill dam acts as an intermediary structure between the underfill material and the EMI shield formation process. It mediates the interaction by providing a physical barrier that shapes the underfill material into a uniform configuration, which in turn provides a uniform substrate surface for the EMI shield coating process, resolving the contradiction between coating uniformity and sidewall coverage.
2Ease of manufacture
If underfill material is dispensed without constraints, then the dispensing process is simple, but the underfill contaminates grounding pads and compromises electrical contact
Solution Approach 1:
The substrate surface is segmented into distinct functional zones by the underfill dam: a containment zone within the dam where underfill is restricted, and external zones including grounding pads where underfill is prevented from reaching. This segmentation allows simple underfill dispensing while ensuring material confinement to the intended area, preventing contamination of grounding pads and maintaining reliable electrical contact.
Solution Approach 2:
The underfill dam is formed in advance to create a preliminary protective barrier that actively prevents underfill material from reaching grounding pads. This preliminary anti-action counteracts the potential harmful effect of underfill contamination before it can occur, allowing simple dispensing processes while ensuring grounding connection reliability is maintained.
3Object-affected harmful factors
If conventional packaging processes are used, then the die can be encapsulated, but adequate EMI shielding is not achieved due to non-uniform coating on vertical surfaces
Solution Approach 1:
The underfill dam and underfill material are formed before EMI shield deposition to pre-create a uniform vertical sidewall surface. This preliminary preparation eliminates the non-uniformity that would otherwise occur during directional sputtering, enabling uniform EMI shield coating thickness on vertical surfaces and achieving adequate EMI shielding effectiveness.
Solution Approach 2:
The underfill material, when constrained by the dam, serves as an intermediary layer that creates a uniform surface profile for EMI shield deposition. This intermediary structure compensates for the limitations of directional sputtering by providing a pre-shaped substrate that ensures uniform coating thickness, thereby achieving effective EMI shielding on vertical sidewalls.
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 solution ensures a more uniform and effective EMI shield thickness and maintains reliable electrical contact by forming a grounded underfill dam to constrain underfill material, addressing the shortcomings of directional sputtering and underfill contamination.
Implementation Method 1
directional sputtering techniques
Implementation Method 2
based on the slope angle of the underfill material that due to its adhesion to the material of the semiconductor die
Data Source
AI summary
A semiconductor device assembly is provided. The assembly includes a substrate including an upper surface having a plurality of internal contact pads and at least one grounding pad and a lower surface having a plurality of external contact pads. The assembly further includes a semiconductor die coupled to the plurality of internal contact pads, a conductive underfill dam coupled to the at least one grounding pad, and underfill material disposed at least between the semiconductor die and the substrate. The underfill material includes a fillet between the semiconductor die and the underfill dam. The assembly further includes a conductive EMI shield disposed over the semiconductor die, the fillet, and the conductive underfill dam.