LED Flip-Chip Assembly With IC Redistribution for Thinner Packaging
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Solution Overview
Problem
Conventional integrated circuit (IC) chips for driving light-emitting diode (LED) flip-chips are limited by wire bonding pads, which hinder further improvements in light-emitting device structures.
Innovation Solution
The integration of an IC flip-chip with flip-chip pads and a redistribution layer, allowing for a flip-chip process that includes a substrate with LED flip-chips, where the flip-chip pads are soldered to the substrate, enabling a more even distribution and stable connection for thinner and smaller light-emitting devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional IC chips with wire bonding pads are used, then wire bonding connections can be established, but the structure is hindered from further improvements and cannot achieve thinner designs
Solution Approach 1:
The patent inverts the conventional connection approach by using flip-chip technology where the IC chip is mounted upside down with pads facing downward toward the substrate, enabling direct soldering connections instead of wire bonding from the top surface. This inversion allows for thinner device profiles while maintaining connection integrity
Solution Approach 2:
The patent transitions from planar wire bonding connections to three-dimensional solder bump connections by adding vertical height through solder balls or solder bumps between the flip-chip pads and substrate contact pads, enabling shorter horizontal traces and more efficient space utilization that reduces overall device thickness
2Reliability
If wire bonding pads are used on conventional IC chips, then electrical connections can be made, but the distribution of connection points is uneven and connections are less stable
Solution Approach 1:
By inverting the chip orientation in flip-chip technology, the pads are positioned on the bottom surface of the IC chip, allowing for more uniform distribution across the chip area and enabling direct vertical alignment with substrate contact pads, which improves both manufacturing precision and connection stability
Solution Approach 2:
The IC chip pads are pre-configured with flip-chip technology before mounting, allowing for precise alignment marks and predetermined pad locations that ensure uniform distribution and stable connections during the subsequent soldering process to the substrate
3Volume of moving object
If conventional IC chip structures are used, then wire bonding can be performed, but the device size cannot be reduced further
Solution Approach 1:
The flip-chip inversion technique enables direct soldering connections from the chip bottom surface to the substrate, eliminating the need for long wire bonds that extend upward from the chip surface, thereby significantly reducing device volume while remaining manufacturable through established flip-chip assembly processes
Solution Approach 2:
By utilizing the vertical dimension through solder bumps rather than horizontal wire bonds, the patent achieves more compact device packaging with reduced footprint and volume, while the manufacturing process adapts to flip-chip assembly techniques that are well-established in the industry
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 solution facilitates the development of lighter and thinner light-emitting devices with improved structural integrity and efficiency by enabling the use of flip-chip technology, allowing for even distribution and stable connections of the IC and LED flip-chips.
Implementation Method 1
The flip-chip pads of the IC flip-chip and the electrodes of the LED flip-chips are disposed on the substrate by way of soldering
Data Source
AI summary
A light-emitting device, a light-emitting assembly and an integrated circuit (IC) flip-chip are provided. The light-emitting device includes the IC flip-chip, a plurality of light-emitting diode (LED) flip-chips and a substrate. The IC flip-chip includes a plurality of flip-chip pads. The LED flip-chips are spaced apart from the IC flip-chip. The substrate carries the IC flip-chip and the LED flip-chips. The LED flip-chips have a plurality of electrodes, and the flip-chip pads of the IC flip-chip and the electrodes of the LED flip-chips are disposed on the substrate by way of soldering. The LED flip-chips are electrically coupled to the IC flip-chip through the substrate.