Wafer Level Package Interconnects via Transfer Molding and Lamination
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Solution Overview
Problem
Conventional packaging technologies for wafer level packaging require complex processes and high costs due to the need for precise surface leveling and exposure of die surfaces, which is challenging with existing methods like grinding or etch back techniques.
Innovation Solution
A method involving transfer molding to form a molding compound around a die without covering its top surface, followed by lamination of a polymer layer using vacuum or heat roll lamination, which simplifies the process and reduces costs by eliminating the need for surface grinding and achieving a planarized surface through pressure clamping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional packaging technologies use grinding or etch back techniques to expose die surfaces, then the die surface can be exposed for forming interconnect structures, but the manufacturing process becomes complex and costly
Solution Approach 1:
The patent applies preliminary action by forming the molding compound around the die before the interconnect structures are formed. The molding compound is prepared in advance with a substantially planar top surface, eliminating the need for subsequent grinding or etch back operations to expose the die surface. This preliminary preparation of the molding compound surface enables direct formation of polymer layers and conductive features without complex surface treatment processes.
2Manufacturing precision
If conventional packaging technologies require precise surface leveling through grinding or etch back, then surface flatness can be achieved, but manufacturing costs increase
Solution Approach 1:
The patent employs a disposable molding compound layer that provides the necessary surface flatness temporarily during the interconnect formation process. The molding compound is formed with a substantially planar top surface using cost-effective transfer molding techniques rather than expensive precision grinding or etch back operations. This disposable surface preparation method achieves the required flatness at lower manufacturing cost.
3Reliability
If the molding compound covers the top surface of the die, then the die is protected during molding, but additional surface exposure steps are required
Solution Approach 1:
The patent applies local quality by creating a differentiated molding compound structure where the molding compound surrounds the die sidewalls and bottom for protection, but deliberately leaves the top surface area substantially planar and accessible. This localized differentiation allows the die to be protected during molding while maintaining direct access to the top surface for subsequent interconnect structure formation, eliminating the need for additional surface exposure steps.
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 reduces manufacturing costs and simplifies the package processing by maintaining a total thickness variation (TTV) of about 5 μm to 10 μm on the molding compound surface, enabling efficient formation of fan-out RDL structures over the die and molding compound.
Implementation Method 1
A method is disclosed for forming a fan-out package and corresponding structure. In some embodiments, a molding compound is formed around a die using a transfer molding process
Implementation Method 2
a first RDL is formed over the molding compound and the die using a lamination process
Implementation Method 3
The lamination process may further include planarizing a top surface of the polymer layer through pressure clamping
Data Source
AI summary
A method for forming a device package includes forming a molding compound around a die and laminating a polymer layer over the die. A top surface of the die is covered by a film layer while the molding compound is formed, and the polymer layer extends laterally past edge portions of the die. The method further includes forming a conductive via in the polymer layer, wherein the conductive via is electrically connected to a contact pad at a top surface of the die.