Wire-Bonded Package-on-Package Assembly for Fine-Pitch Microcontacts
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Solution Overview
Problem
Conventional etching processes are limited in forming microcontacts with a large aspect ratio and arrays of microcontacts with small pitch or spacing, making it difficult to create high-aspect-ratio microcontacts for efficient electrical connections in microelectronic packages.
Innovation Solution
A microelectronic package design featuring wire bonds with bases joined to conductive elements and end surfaces, where a dielectric encapsulation layer separates the wire bonds, and unencapsulated portions are exposed for additional connections, allowing for flexible configurations and finer pitch arrangements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used to form microcontacts, then the manufacturing process is simple, but the aspect ratio and pitch of microcontacts are limited
Solution Approach 1:
The patent replaces conventional etching processes with wire bonding technology. Instead of using chemical etching to form microcontacts, the invention uses mechanically deposited wire bonds that are laid onto the substrate and bonded to contact pads. This substitution enables the formation of microcontacts with much higher aspect ratios and finer pitches that cannot be achieved through traditional etching methods.
Solution Approach 2:
The invention changes the fundamental parameters of microcontact formation by transitioning from planar etched contacts to three-dimensional wire bond structures. The wire bonds can achieve aspect ratios significantly higher than etched contacts, and the bonding process allows for pitch dimensions below what is achievable with conventional etching. This parameter change enables high-aspect-ratio microcontacts with fine pitch arrangements.
2Reliability
If wire bonds with unencapsulated portions are used, then electrical connections are improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by selectively encapsulating only the lower portions of the wire bonds while leaving the upper portions unencapsulated. This localized differentiation serves specific functions: the encapsulated portions provide mechanical support and environmental protection, while the unencapsulated portions enable electrical connections to upper surfaces or stacked devices. This selective encapsulation approach improves connection reliability without requiring complete structural redesign.
Solution Approach 2:
The wire bond structure is segmented into distinct functional zones: an encapsulated lower portion for mechanical support and an unencapsulated upper portion for electrical connection. This segmentation allows each portion to perform its optimized function independently, improving overall connection reliability while maintaining a manageable structural complexity through clear functional division.
3Volume of moving object
If finer pitch arrangements are implemented, then assembly size is reduced, but manufacturing difficulty increases
Solution Approach 1:
The patent replaces conventional etching-based contact formation with wire bonding, which inherently allows for finer pitch arrangements. The wire bonding process can accommodate smaller spacing between contact pads and enable tighter packing of interconnects, thereby reducing overall assembly size while avoiding the pitch limitations of etching processes.
Solution Approach 2:
The invention transitions from two-dimensional planar contacts to three-dimensional wire bond structures. This dimensional change allows interconnects to route vertically and diagonally, enabling finer effective pitch and more compact routing that reduces assembly footprint without proportionally increasing manufacturing complexity.
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 design enhances the formation of microelectronic packages by enabling higher aspect ratio microcontacts and finer pitch arrangements, improving electrical connections and reducing the size of the assembly, facilitating high-speed operations.
Implementation Method 1
A dielectric encapsulation layer extends from at least one of the first or second surfaces and fills spaces between the wire bonds such that the wire bonds are separated from one another by the encapsulation layer
Implementation Method 2
wire bonds having bases joined to respective ones of the conductive elements and end surfaces remote from the substrate and remote from the bases
Data Source
AI summary
Apparatuses relating to a microelectronic package are disclosed. In one such apparatus, a substrate has first contacts on an upper surface thereof. A microelectronic die has a lower surface facing the upper surface of the substrate and having second contacts on an upper surface of the microelectronic die. Wire bonds have bases joined to the first contacts and have edge surfaces between the bases and corresponding end surfaces. A first portion of the wire bonds are interconnected between a first portion of the first contacts and the second contacts. The end surfaces of a second portion of the wire bonds are above the upper surface of the microelectronic die. A dielectric layer is above the upper surface of the substrate and between the wire bonds. The second portion of the wire bonds have uppermost portions thereof bent over to be parallel with an upper surface of the dielectric layer.