Wafer Level Package Molding Structure with Sacrificial Layer
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Solution Overview
Problem
In wafer-level exposed-molding packaging, molding residue and mechanical material removal processes can cause redistribution layer (RDL) delamination defects and increase manufacturing costs, while uncontrolled recesses between the die and molding compound compromise device reliability and lead to RDL contacting multiple materials.
Innovation Solution
A method involving the formation of a sacrificial layer over microelectronic devices, followed by molding compound deposition around the devices with the sacrificial layer remaining uncovered, and subsequent removal of the sacrificial layer to expose electrical contacts without mechanical material removal processes, ensuring the RDL contacts only the dielectric layer and molding compound, thereby reducing delamination risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If mechanical material removal processes (grinding) are used to remove molding residue, then molding residue is removed, but manufacturing costs increase and components may be damaged
Solution Approach 1:
A release layer is applied to the mold cavity before molding. This preliminary action prevents molding residue from adhering to the mold, eliminating the need for subsequent mechanical removal processes and reducing manufacturing costs while avoiding component damage
Solution Approach 2:
The release layer acts as an intermediary between the mold cavity and the molding compound. It prevents direct adhesion of molding residue to the mold, allowing for easy release without mechanical grinding and reducing both costs and component damage risk
2Object-affected harmful factors
If mechanical material removal processes are used, then molding residue is removed, but component integrity is compromised due to overgrinding and material residue
Solution Approach 1:
The release layer is applied beforehand to prevent molding residue adhesion, eliminating the need for mechanical removal that could cause overgrinding and material residue, thereby preserving component integrity
Solution Approach 2:
The release layer serves as a protective intermediary that prevents direct contact between the mold and molding compound, avoiding mechanical damage to components during the release process
3Ease of manufacture
If uncontrolled recesses are present between die and molding compound, then molding is simpler, but device reliability is compromised
Solution Approach 1:
The release layer is selectively applied only in specific regions of the mold cavity where it is needed to prevent adhesion, while other regions maintain direct contact for proper molding. This localized approach ensures reliable device performance while maintaining molding simplicity
Solution Approach 2:
The release layer modifies the surface properties (adhesion parameters) of the mold cavity in specific areas, allowing controlled release without creating uncontrolled recesses, thereby maintaining both molding simplicity and device reliability
4Ease of manufacture
If RDL contacts multiple different materials, then manufacturing is simpler, but delamination defects increase
Solution Approach 1:
The release layer acts as a controlled intermediary that prevents the RDL from contacting multiple different materials (mold metal, molding compound, and release layer residues), reducing delamination defects while maintaining manufacturing simplicity
Data Source
AI summary
Apparatus, and methods of manufacture thereof, in which a molding compound is formed between spaced apart microelectronic devices. The molding compound comprises micro-filler elements. No boundary of any of the micro-filler elements is substantially parallel to a substantially planar surface of the molding compound, or to a substantially planar surface of any of the microelectronic devices.