Solderless Interconnection Structure for High-Density IC Packages
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Solution Overview
Problem
The challenge in creating reliable interconnect structures for integrated circuit devices with high input-output density is exacerbated by solder bridging issues, which limit the density of IC packages due to the need for adequate spacing between conductive pillars to prevent solder wetting and shorting.
Innovation Solution
A solderless interconnection structure is achieved by directly aligning and attaching conductive pillars on an integrated circuit die to corresponding conductive pads on a package substrate using a thermal compression process, eliminating the need for solder and allowing for closer pillar placement without bridging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder is used to connect conductive pillars to conductive pads, then reliable electrical connection is achieved, but solder bridging occurs between adjacent conductive pillars requiring adequate spacing
Solution Approach 1:
The patent removes solder from the interconnection process entirely, extracting the problematic material that causes bridging. Conductive pillars are directly connected to conductive pads through mechanical compression and bonding without any solder intervention, eliminating the bridging issue while maintaining electrical connectivity.
Solution Approach 2:
The patent replaces the thermal soldering process with a mechanical compression bonding system. Conductive pillars are pressed directly against conductive pads under controlled pressure and temperature conditions, creating reliable electrical connections through mechanical contact and diffusion bonding without molten solder.
2Quantity of substance
If conductive pillars are placed closer together to increase density, then IC package density is improved, but solder bridging causes shorting between adjacent pillars
Solution Approach 1:
By removing solder from the connection process, the patent eliminates the material that causes bridging between closely spaced conductive pillars. This allows pillars to be placed at minimum spacing without risking shorting, thereby maximizing package density while maintaining connection reliability.
Solution Approach 2:
The patent changes the fundamental parameters of the connection process by eliminating molten solder and its associated wetting behavior. The direct compression bonding approach allows conductive pillars to be positioned at closer spacing (10 micrometers or less) without the risk of solder flowing between them and causing shorts.
3Strength
If thermal compression bonding is performed with pre-soldered bumps, then conductive pillars are attached to conductive pads, but solder bridging occurs when pillars and pads are too close
Solution Approach 1:
The patent removes pre-soldered bumps from the package substrate, eliminating the source of solder that would bridge between closely spaced conductive pillars during thermal compression bonding. Direct bonding between conductive pillars and conductive pads is achieved without any intervening solder material.
Solution Approach 2:
The patent introduces a controlled thermal compression process as an intermediary mechanism that enables direct bonding between conductive pillars and conductive pads without solder. The heat and pressure facilitate diffusion bonding and mechanical adhesion while preventing any solder bridging that would occur with traditional pre-soldered approaches.
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 enables higher density integrated circuit packages with reduced risk of solder shorting, allowing conductive pillars to be placed as close as 10 micrometers apart, enhancing electrical connectivity and mechanical stability without the use of solder.
Implementation Method 1
thermal compression bonding may be performed to attach the conductive pillars on the IC die to the pre-soldered bumps on the package substrate
Implementation Method 2
A reflow process can be performed to melt the solder
Implementation Method 3
thermal compression bonding may be performed to attach the conductive pillars
Data Source
AI summary
An integrated circuit package may include an integrated circuit die and a package substrate having a conductive pad. A conductive pillar is formed on a front surface of the integrated circuit die and directly contacts the conductive pad. Prior to contacting the conductive pad directly, the conductive pillar may be positioned adjacent to the conductive pad such that it is aligned to the conductive pad. The integrated circuit package further includes an interconnect structure that is formed in the package substrate. The interconnect structure may include conductive traces that are electrically connected to the conductive pad and the conductive pillar. An additional integrated circuit die may be mounted on the package substrate. The additional integrated circuit die may couple to the integrated circuit die through the interconnect structure.