Wire Bond Pitch Reduction in PoP 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 tight spacing, which is a challenge in microelectronic packaging for high-speed operations.
Innovation Solution
A microelectronic package design featuring wire bonds with bases joined to conductive elements on a substrate, where a dielectric encapsulation layer separates the wire bonds, and unencapsulated portions are exposed to facilitate connections, allowing for a finer pitch configuration and improved mechanical and electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used to form microcontacts, then manufacturing simplicity is maintained, but manufacturing precision deteriorates due to inability to form high aspect ratio and small pitch structures
Solution Approach 1:
The patent replaces conventional etching processes with a wire bonding process. Instead of using etching to form microcontacts, the invention uses wire bonds to create electrical connections, thereby achieving high aspect ratio and small pitch structures without the limitations of etching process precision
Solution Approach 2:
The invention changes the fundamental parameter of connection formation from etching-based material removal to wire bonding-based physical placement. This parameter change enables the formation of microcontacts with high aspect ratios and small pitches that are unachievable through conventional etching methods
2Reliability
If wire bonds are fully encapsulated by dielectric layer, then mechanical stability is improved, but electrical connectivity deteriorates due to lack of exposed connection points
Solution Approach 1:
The patent applies local quality by selectively exposing certain portions of wire bonds while encapsulating others. The dielectric encapsulation layer covers portions of the wire bonds for mechanical stability, while leaving end portions exposed to provide electrical connection points, thus achieving both mechanical stability and electrical connectivity in different locations
3Quantity of substance
If microcontacts are arranged with tight spacing, then device density is improved, but manufacturing precision deteriorates due to etching process limitations
Solution Approach 1:
The patent replaces etching-based contact formation with wire bonding. This substitution allows for tighter spacing between microcontacts because wire bonds can be precisely positioned and placed at high densities without the resolution limitations that constrain etching processes
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 ability to create microelectronic packages with finer pitch configurations, enabling high-speed operations by providing robust and efficient electrical connections while maintaining mechanical stability.
Implementation Method 1
wire bonds having bases joined to respective ones of the conductive elements and end surfaces remote from the substrate and remote from the bases
Implementation Method 2
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
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.