Wafer-Level Redistribution Layer Using Laser Direct Structuring
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Solution Overview
Problem
Existing wafer-level packaging techniques face challenges in forming high density, large size, and high pin-count packages due to the disparity between wafer technology advancement and packaging technology, leading to increased costs.
Innovation Solution
The method involves using laser direct structuring (LDS) to form conductive traces within a resin activatable layer, followed by deposition of molding and passivation layers, and forming solder balls to create a redistribution layer, which eliminates the need for drilling and filling vias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional wafer-level packaging techniques are used, then basic packaging functionality is achieved, but the cost increases significantly for high density, large size, and high pin-count packages
Solution Approach 1:
The patent replaces mechanical drilling and filling operations with a chemical field-based approach using laser direct structuring. The LDS process uses laser energy to activate conductive particles within the resin, creating conductive traces through a chemical transformation rather than mechanical material removal and deposition. This substitution eliminates expensive and time-consuming mechanical steps while achieving the required manufacturing precision for high density and high pin-count packages
Solution Approach 2:
The patent changes the physical and chemical parameters of the resin material by incorporating laser-activatable conductive particles. The resin transitions from an insulating state to a conductive state through laser irradiation, changing its electrical conductivity parameter locally. This parameter change enables the formation of conductive traces without mechanical drilling, reducing manufacturing cost while maintaining the precision needed for advanced package configurations
2Reliability
If conventional drilling and filling vias are used to form redistribution layers, then conductive interconnections are achieved, but the process becomes expensive and time-consuming
Solution Approach 1:
The patent incorporates conductive particles within the resin material before the laser structuring step. This preliminary preparation ensures that the conductive material is already in position and properly distributed throughout the resin, eliminating the need for subsequent filling operations. The conductive particles are pre-positioned to form the desired trace patterns when activated by the laser, reducing manufacturing cycle time while ensuring reliable electrical interconnections
Solution Approach 2:
The patent merges multiple process steps into a single integrated operation. The laser direct structuring process simultaneously activates the conductive particles, forms the conductive traces, and defines the interconnection geometry in one step. This merging of functions (activation, trace formation, and pattern definition) eliminates separate drilling and filling operations, reducing cycle time while maintaining interconnection reliability through the unified process
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 the cost and complexity of forming high density, large size, and high pin-count wafer-level packages by utilizing LDS resin to form the redistribution layer, thereby eliminating expensive and time-consuming steps.
Implementation Method 1
forming a laser direct structuring (LDS) activatable resin over a back side of the plurality of integrated circuit dies
Implementation Method 2
activating desired areas of the LDS activatable resin to form conductive areas within the LDS activatable resin
Data Source
AI summary
A method of forming a wafer-level package includes singulating a wafer into a plurality of reconstituted integrated circuit dies, affixing a carrier to a front side of the plurality of integrated circuit dies, and forming a laser direct structuring (LDS) activatable resin over a back side of the plurality of integrated circuit dies, over side edges of the plurality of integrated circuit die, and over adjacent portions of the carrier. Desired areas of the LDS activatable resin are activated to form conductive areas within the LDS activatable resin, at least one of the conductive areas associated with each integrated circuit die being formed to contact a respective pad of that integrated circuit die and to run alongside to and in contact with a side of the LDS activatable resin in contact with a side edge of that integrated circuit die.