Stiffened Wire Bonds for Offset BVA Microelectronic Packages
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Solution Overview
Problem
Conventional etching processes are limited in forming microcontacts with a high aspect ratio and small pitch, making it difficult to create arrays of microcontacts with appreciable height and small spacing, which is a challenge in microelectronic packaging for efficient connections between chip packages.
Innovation Solution
A microelectronic package design featuring a generally planar element with a reinforcing dielectric layer and encapsulation, where wire bonds with bends extend through the dielectric layer and encapsulation, providing mechanical and electrical connections with protruding regions that maintain the position of wire bond tips, allowing for increased pitch and reduced stress at interconnection interfaces.
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 the conventional etching process (chemical/mechanical system) with a wire bonding process that uses mechanical deposition and bonding. Wire bonds are physically deposited onto contact pads and embedded in encapsulant material, eliminating the need for complex etching processes while achieving higher aspect ratios and smaller pitches.
Solution Approach 2:
The patent changes the fundamental parameters of the interconnection approach by using wire bonds with diameters and lengths that can achieve aspect ratios exceeding 10:1 and pitches below 50 micrometers, compared to the limited parameters achievable through conventional etching processes.
2Area of stationary object
If wire bonds with bends are used, then the pitch between contacts can be increased, but the structural complexity increases
Solution Approach 1:
The patent introduces bends in the wire bonds that extend in lateral dimensions (x-y plane) rather than only vertical dimension. This allows the wire bonds to accommodate larger pitch between contacts by routing through the encapsulant material laterally, effectively using additional spatial dimensions to resolve the pitch constraint.
Solution Approach 2:
The encapsulant material serves as an intermediary that supports and positions the bent wire bonds. The wire bonds are embedded in the encapsulant, which provides mechanical support and allows the bonds to maintain complex bent configurations without requiring additional structural elements.
3Reliability
If higher aspect ratio microcontacts are formed, then electrical connections become more efficient, but mechanical stability decreases
Solution Approach 1:
The patent provides mechanical support for the wire bonds by embedding them in encapsulant material from the outset. This cushioning approach prevents mechanical instability that would otherwise result from the high aspect ratio, as the encapsulant surrounds and supports the wire bonds throughout their length, including the bent portions.
Solution Approach 2:
The patent creates a composite structure where the wire bond (conductive material) is combined with the encapsulant material (insulating and mechanical support). This composite approach allows the wire bond to achieve high aspect ratio for electrical efficiency while the encapsulant provides the necessary mechanical stability.
Data Source
AI summary
A component can include a generally planar element, a reinforcing dielectric layer overlying the generally planar element, an encapsulation overlying the reinforcing dielectric layer, and a plurality of wire bonds. Each wire bond can have a tip at a major surface of the encapsulation. The wire bonds can have first portions extending within the reinforcing dielectric layer. The first portions of at least some of the wire bonds can have bends that change an extension direction of the respective wire bond. The reinforcing dielectric layer can have protruding regions surrounding respective ones of the wire bonds, the protruding regions extending to greater peak heights from the first surface of the generally planar element than portions of the reinforcing dielectric layer between adjacent ones of the protruding regions. The peak heights of the protruding regions can coincide with points of contact between the reinforcing dielectric layer and individual wire bonds.