Semiconductor Package Cover Discontinuity Enhances Encapsulant Adhesion
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Solution Overview
Problem
Conventional semiconductor packages for image sensor chips face issues with delamination of the transparent cover, which affects the adhesion and reliability of the encapsulant, leading to reduced seal strength and package reliability.
Innovation Solution
A semiconductor package design that includes a protective cover with discontinuities on its side surfaces, enhancing the adhesion of the encapsulant by creating an anchor for it, thereby reducing the risk of delamination and improving package reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transparent cover is attached to the sensor die using adhesive, then the die is protected from the environment, but delamination occurs between the cover and adhesive, reducing package reliability
Solution Approach 1:
The patent introduces a groove structure that segments the encapsulant into distinct regions, creating mechanical interlocking features that prevent delamination. The groove divides the encapsulant volume and creates anchor points that resist separation forces between the cover and substrate.
Solution Approach 2:
The patent applies discontinuous adhesive layers or modifies the encapsulant properties in specific localized regions rather than uniformly throughout. This creates enhanced adhesion zones at critical interfaces while maintaining overall package integrity, addressing delamination at specific problem areas.
2Strength
If adhesive is used to attach the cover to the die, then the cover is secured, but the seal strength is reduced due to delamination
Solution Approach 1:
The patent incorporates adhesive or encapsulant material into the groove structure before final assembly, pre-positioning the bonding material in optimal locations. This preliminary placement ensures proper adhesive distribution and maximizes bonding effectiveness before the cover is attached.
Solution Approach 2:
The patent employs composite structures combining the transparent cover, adhesive layer, encapsulant material, and groove features. This multi-material composite approach creates synergistic effects where each material contributes its unique properties to enhance overall seal strength and prevent delamination.
3Reliability
If the encapsulant covers the side surfaces of the protective cover, then environmental protection is improved, but adhesion is reduced due to lack of anchor points
Solution Approach 1:
The groove structure segments the encapsulant into anchored and free-standing portions, creating mechanical keyways that prevent the encapsulant from detaching. This segmentation provides discrete attachment points along the side surfaces, improving adhesion while maintaining environmental protection.
Solution Approach 2:
The patent transitions from a two-dimensional adhesive interface to a three-dimensional groove-based anchoring system. By adding vertical depth and lateral confinement through the groove structure, the encapsulant gains enhanced mechanical interlocking in multiple dimensions, significantly improving adhesion strength.
Data Source
AI summary
A method for forming a semiconductor package is disclosed. The method includes providing a package substrate having top and bottom major package substrate surfaces, the top major package surface including a die attach region. A die having first and second major die surfaces is attached onto the die attach region. The second major die surface is attached to the die attach region. The first major die surface includes an die active region and a cover adhesive region surrounding the die active region. The method also includes applying a cover adhesive to the cover adhesive region on the first major die surface. A protective cover with first and second major cover surfaces and side surfaces is attached to the die using the cover adhesive. The second major cover surface contacts the cover adhesive. The protective cover covers the die active region. The protective cover includes a discontinuity on at least one of the side surfaces. An encapsulant is disposed on the package substrate to cover exposed portions of the package substrate, die and bond wires and side surfaces of the protective cover, while leaving the first major cover surface exposed. The discontinuity enhances adhesion of the encapsulant to the protective cover.