Fan-Out Semiconductor Package Trenches to Prevent Wire Sagging
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Solution Overview
Problem
In the manufacturing of fan-out packages with vertical wires, wire sagging occurs due to the flow of molding material during the molding process, leading to wire short defects as demands for higher integration increase, causing issues with wire diameter and pitch.
Innovation Solution
A semiconductor package design featuring a redistribution wiring layer with trenches and conductive wires, filled by filling members with different properties from the sealing member, to prevent wire sagging and improve mechanical behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If wire diameter and pitch are decreased to achieve higher integration, then integration density is improved, but wire sagging occurs due to molding material flow causing wire short defects
Solution Approach 1:
The molding cavity is segmented into multiple regions by forming trenches around each wire. These trenches isolate the molding material flow for each wire, preventing the material from causing wires to sag and short-circuit while still allowing high integration density with small pitch wires.
Solution Approach 2:
A release agent is applied as an intermediary layer between the wire and the molding material. This release agent prevents the molding material from directly contacting and adhering to the wire, thereby preventing wire sagging during the molding process while maintaining high integration density.
2Area of moving object
If wire pitch is decreased for higher integration, then integration density is improved, but wire sagging occurs leading to manufacturing defects
Solution Approach 1:
Trenches are formed around each wire to segment the molding cavity, providing individual confinement for each wire. This segmentation maintains precise wire positioning even when pitch is reduced, preventing wires from deviating during molding and avoiding manufacturing defects.
3Ease of manufacture
If conventional molding process is used without trenches, then manufacturing process is simple, but wire sagging occurs causing wire short defects
Solution Approach 1:
The molding process is modified by adding trenches that segment the cavity. This segmentation is integrated into the existing molding process workflow, allowing the use of conventional injection molding equipment and procedures while preventing wire sagging through the trench structure, thus maintaining ease of manufacture while improving reliability.
Data Source
AI summary
A semiconductor package includes a redistribution wiring layer having redistribution wirings, a sealing member provided on the redistribution wiring layer and having a first surface in contact with the redistribution wiring layer and a second surface opposite to the first surface, a plurality of semiconductor chips sequentially stacked on one another within the sealing member and arranged such that a front surface on which chip pads each of the semiconductor chips are formed faces the redistribution wiring layer, a plurality of trenches extending in a vertical direction from the first surface of the sealing member to the front surfaces of the semiconductor chips and exposing the chip pads, a plurality of conductive wires extending in the vertical direction from the chip pads within the plurality of trenches and electrically connected to the redistribution wirings respectively, and filling members within the plurality of trenches and surrounding the conductive wires.