Reinforced Chip Package Structure for Bonding Crack Reduction
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Solution Overview
Problem
The adhesion between a dummy silicon layer and a wafer in a wafer level chip scale package (WLCSP) is poor, leading to delamination and cracks due to uneven stress at the bonding interface, and existing methods to enhance thickness, such as using a dummy silicon or ceramic layer, increase processing complexity and costs.
Innovation Solution
A package structure with a reinforcement element, such as a soft encapsulant, is used to reduce warpage and crack formation by adhering directly to the backside surface of the electronic component, eliminating the need for complex surface smoothing and additional adhesives, and allowing for adjustable thickness through molding techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a dummy silicon layer is added to increase wafer thickness, then warpage control is improved, but adhesion between the dummy silicon layer and wafer deteriorates
Solution Approach 1:
The patent introduces an adhesive layer as an intermediary between the dummy silicon layer and the wafer. This adhesive layer mediates the bonding interface, providing strong adhesion while allowing the dummy silicon layer to maintain its warpage control function. The adhesive layer resolves the contradiction by creating a transition zone that accommodates both structural support and bonding requirements.
Solution Approach 2:
The patent creates a composite structure consisting of the wafer, adhesive layer, and dummy silicon layer. This composite material approach allows each layer to contribute its specific properties: the wafer provides the base substrate, the adhesive layer provides bonding strength, and the dummy silicon layer provides warpage control. The composite structure resolves the adhesion problem while maintaining thickness enhancement.
2Reliability
If an extra adhesive is applied to attach dummy silicon layer to wafer, then adhesion is improved, but delamination and cracks occur due to uneven stress
Solution Approach 1:
The patent modifies the physical and chemical parameters of the adhesive layer, including its thickness, composition, and mechanical properties. By optimizing these parameters, the adhesive layer can distribute stress uniformly across the bonding interface, preventing the formation of delamination and cracks while maintaining strong adhesion between the dummy silicon layer and wafer.
Solution Approach 2:
The patent applies the adhesive layer selectively at specific locations where bonding is required, rather than uniformly across the entire interface. This localized application allows for optimized stress distribution in critical areas while reducing the overall stress burden on the bonding interface, thereby preventing delamination and cracks.
3Strength
If dummy silicon or ceramic layer is used to enhance thickness, then structural support is improved, but processing complexity and costs increase
Solution Approach 1:
The patent makes the adhesive layer serve multiple functions: it provides adhesion between layers, controls warpage through its mechanical properties, and simplifies processing by eliminating the need for complex surface preparation. This multi-functionality reduces overall processing complexity while maintaining the structural support provided by the dummy silicon layer.
Solution Approach 2:
The patent extracts and eliminates unnecessary processing steps such as complex surface smoothing and high-power laser cutting by using the adhesive layer as the primary bonding mechanism. This extraction of redundant processes simplifies the overall manufacturing workflow while maintaining structural integrity.
4Ease of manufacture
If bonding surfaces are not sufficiently planarized, then processing is simplified, but delamination occurs due to poor adhesion
Solution Approach 1:
The patent changes the parameters of the adhesive layer to compensate for surface irregularities. By adjusting the adhesive's viscosity, thickness, and curing characteristics, the bonding process can accommodate non-planar surfaces without requiring extensive surface preparation, thereby maintaining both processing simplicity and adhesion reliability.
Solution Approach 2:
The patent creates a composite bonding interface where the adhesive layer acts as a buffer between the irregular surfaces of the wafer and dummy silicon layer. This composite approach allows the adhesive to flow into and accommodate surface irregularities, achieving reliable adhesion without requiring highly planarized surfaces.
Data Source
AI summary
A package structure is provided. The package structure includes an electronic component and a reinforcement element. The electronic component has an active surface, a backside surface opposite to the active surface, and a lateral surface extending between the active surface and the backside surface. The electronic component includes a device layer closer to the active surface than to the backside surface. The reinforcement element contacts the backside surface and is configured to reduce the formation of a crack in the electronic component during a bonding operation.