Multi-Die Semiconductor Interconnects Using LDS and Temporary Tie-Lines
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Solution Overview
Problem
Conventional die-to-die interconnections in multi-die semiconductor devices, such as those implemented by wire bonding, electroless plating, or conductive paste, result in high manufacturing costs and low reliability.
Innovation Solution
A method utilizing Laser Direct Structuring (LDS) to pattern laser-activatable material on semiconductor dice and leads, followed by electroplating to form electrically-conductive lines, including temporary 'tie-bars' to connect floating regions to a grounded area, and subsequent removal of these tie-bars to establish reliable die-to-die interconnections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonding, electroless plating, or conductive paste dispensing is used for die-to-die interconnections, then interconnections can be established, but manufacturing costs increase and reliability decreases
Solution Approach 1:
The patent replaces mechanical wire bonding with a laser-based direct structuring process. Laser radiation is used to activate conductive material within the encapsulant, creating conductive paths directly between bonding pads without physical wire manipulation. This substitution eliminates the mechanical complexity and cost of wire bonding while improving reliability through direct laser-formed connections.
Solution Approach 2:
The patent changes the state of the conductive material from inactive to active through laser irradiation. The conductive material embedded in the encapsulant is transformed from a non-conductive state to a conductive state by controlling laser parameters (intensity, duration, pattern), enabling precise formation of interconnection paths with improved reliability and reduced manufacturing cost.
2Ease of manufacture
If conventional die-to-die interconnection methods are used, then connections can be formed, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges the encapsulation process with the interconnection formation process. Conductive material is embedded within the encapsulant material itself, and laser activation occurs during or after encapsulation. This combining of functions eliminates separate interconnection formation steps, reducing manufacturing complexity while maintaining ease of production.
Solution Approach 2:
The encapsulant material serves dual functions: providing mechanical protection and housing conductive material for interconnections. The conductive material within the encapsulant self-activates through laser irradiation to form connections, eliminating the need for external wiring or complex assembly processes, thereby simplifying manufacturing.
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 enhances the reliability of die-to-die interconnections in multi-die semiconductor devices by using a combination of LDS and electroplating processes to create robust, electrically-conductive tracks.
Implementation Method 1
Laser radiation is directed onto the laser-activatable material to pattern a set of laser-activated lines
Implementation Method 2
A second metallic layer is selectively deposited onto the first and second subsets of electrically-conductive lines by means of electroplating
Data Source
Figure 1~2B
Figure 3A~5B
Figure 4C~6C
AI summary
In a method of manufacturing a multi-die semiconductor device (10), a metal leadframe is provided which includes a die pad (100) and electrically-conductive leads (102) arranged around the die pad. A first (12) and a second (14) semiconductor dice are arranged onto the die pad. A laser-activatable material is provided onto the dice (12, 14) and the leads (102), and a set of laser-activated lines is patterned which includes a first subset of lines coupling selected bonding pads of the dice (12, 14) to selected leads (102), a second subset of lines coupling selected bonding pads of the dice (12, 14) amongst themselves, and a third subset of lines coupling the lines in the second subset of lines to at least one line in the first subset of lines, and/or to at least one electrically-conductive lead. A first metallic layer is deposited onto the laser-activated lines to provide respective first, second and third subsets of electrically-conductive lines. A second metallic layer is selectively deposited onto the first and second subsets of electrically-conductive lines by means of electroplating to provide respective first (16C', 16C) and second (16B', 16B) subsets of electrically-conductive tracks. The electrically-conductive lines in said third subset of electrically-conductive lines are selectively removed.