Semiconductor Lid Adhesive Sidewall Extension for Delamination
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Solution Overview
Problem
The coefficient of thermal expansion (CTE) mismatch between semiconductor integrated circuit dies and substrates can cause stress, cracking, and delamination in semiconductor packages, particularly in negatively warped substrates, where traditional adhesion methods fail to provide sufficient mechanical reliability and prevent delamination.
Innovation Solution
A semiconductor package design that includes a substrate with conductive layers, an integrated circuit die mounted using flip chip bonding and microbumps, underfill for stress relief, and an adhesive with a protrusion and base configuration that extends onto the sidewall of the lid, enhancing adhesion strength by conformally coating the lid corner and covering a majority of the inner sidewall, thereby preventing delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional adhesion methods are used to attach the lid to the substrate, then the manufacturing process is simple, but the adhesion strength is insufficient and delamination occurs due to CTE mismatch and substrate warpage
Solution Approach 1:
The adhesive structure transitions from a planar configuration to a three-dimensional configuration by adding a protrusion that extends onto the sidewall of the lid. This dimensional change allows the adhesive to occupy both the horizontal interface between lid and substrate and the vertical sidewall surface, creating a multi-dimensional bonding network that significantly enhances adhesion strength and resistance to delamination forces.
Solution Approach 2:
The adhesive is formulated as a composite material containing conductive particles dispersed within an adhesive matrix. This composite structure provides both mechanical adhesion functions and electrical conductivity functions, enabling the adhesive to serve multiple purposes: bonding the lid to the substrate, filling gaps, and providing electrical pathways, thereby improving overall package performance while managing CTE mismatch.
2Reliability
If the adhesive is applied only in the space between the lid and substrate, then the application process is simple, but the adhesion strength is insufficient to prevent delamination in negatively warped substrates
Solution Approach 1:
The protrusion is pre-formed on the adhesive before the lid is placed on the substrate. This preliminary structuring ensures that when the adhesive is applied, the protrusion is already positioned to extend onto the sidewall of the lid, creating immediate mechanical interlocking and enhanced bonding without requiring complex post-application processing or adjustment.
Solution Approach 2:
The adhesive structure features a protrusion with specific local geometry designed to conform to the lid corner and sidewall region. This localized structural enhancement concentrates adhesion strength precisely where delamination forces are most severe (at the lid corners and sidewalls), providing targeted reinforcement without unnecessarily complicating the entire adhesive application process.
3Strength
If the adhesive does not extend onto the sidewall of the lid, then the adhesive application is straightforward, but delamination occurs due to insufficient mechanical anchoring
Solution Approach 1:
The protrusion of the adhesive is nested within the corner region of the lid, with the adhesive base positioned at the lid corner and the protrusion extending along the sidewall. This nested configuration allows the adhesive to efficiently utilize the available space, creating a compact yet highly effective bonding structure that maximizes adhesion strength while maintaining manufacturing feasibility through standard dispensing techniques.
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 enhanced adhesion strength improves mechanical reliability and prevents delamination of the lid from the substrate, even in negatively warped configurations, ensuring improved device yield and reliability.
Implementation Method 1
an adhesive with a protrusion and base configuration that extends onto the sidewall of the lid, enhancing adhesion strength
Implementation Method 2
underfill for stress relief
Data Source
AI summary
A method of forming a semiconductor package includes dispensing an adhesive on a substrate that has an integrated circuit die attached thereon, placing a lid over the integrated circuit die such that a bottom surface of the lid caps at least a portion of the adhesive, and pressing the lid against the substrate such that a portion of the adhesive is squeezed from a space between the bottom surface of the lid and the substrate onto a sidewall of the lid.