Fan-Out Package Redistribution Layer Without Substrate Transfer
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Solution Overview
Problem
In the manufacturing of fan out panel level packages, the redistribution circuit substrate is prone to uneven expansion and contraction during the transfer process, affecting the structural reliability of the final product.
Innovation Solution
A package structure and manufacturing method where the redistribution layer is formed on a temporary carrier panel, with the temporary carrier panel removed after the chip assembly is placed, allowing the redistribution circuits to be manufactured in a sequential manner to avoid the need for substrate transfer, ensuring good structural reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the redistribution circuit substrate is transferred from one temporary substrate to another, then the chip pad can be exposed for electrical connection, but the substrate is prone to uneven expansion and contraction affecting structural reliability
Solution Approach 1:
The patent forms the redistribution circuits and photoimageable dielectric layers in a predetermined sequence on the temporary substrate before chip bonding. The outermost photoimageable dielectric layer is prepared with openings exposing solder ball pads in advance, eliminating the need for substrate transfer and subsequent expansion/contraction issues.
Solution Approach 2:
The patent extracts the problematic transfer process from the manufacturing flow. Instead of transferring the redistribution circuit substrate between substrates, the solution keeps everything on the original temporary substrate throughout the process, removing the source of uneven expansion and contraction.
2Productivity
If multiple substrate transfers are performed during manufacturing, then chip assembly can be completed, but manufacturing complexity and time increase
Solution Approach 1:
The patent combines multiple manufacturing steps into a single continuous process on one substrate. The redistribution circuits, dielectric layers, openings, and chip assembly all occur sequentially on the same temporary substrate without interruption or transfer, merging what would otherwise be separate operations.
Solution Approach 2:
The manufacturing process maintains continuous useful action without interruption. The temporary substrate serves as the work platform throughout the entire process from redistribution circuit formation to chip assembly, eliminating idle transfer time and maintaining productive workflow continuity.
Data Source
AI summary
A package structure includes a redistribution layer, a chip assembly, a plurality of solder balls, and a molding compound. The redistribution layer includes redistribution circuits, photoimageable dielectric layers, conductive through holes, and chip pads. One of the photoimageable dielectric layers located on opposite two outermost sides has an upper surface and openings. The chip pads are located on the upper surface and are electrically connected to the redistribution circuits through the conductive through holes. The openings expose portions of the redistribution circuits to define solder ball pads. Line widths and line spacings of the redistribution circuits decrease in a direction from the solder ball pads towards the chip pads. The chip assembly is disposed on the chip pads and includes at least two chips with different sizes. The solder balls are disposed on the solder ball pads, and the molding compound at least covers the chip assembly.