IC Substrate Interconnects Using Masked Solder Containment
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Solution Overview
Problem
Existing interconnects between integrated circuits and carrier substrates face challenges in reducing bump pitch due to protruding solder material, which increases mechanical reliability issues and limits the density of interconnects.
Innovation Solution
The use of metal projections extending from bond pads on the integrated circuit and solder material connecting these projections to landing pads on the substrate, with a mask defining areas between the pads to allow the solder material to fill and reduce bulging, thereby minimizing bump pitch and enhancing mechanical reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder material is used to attach metal projections to landing pads, then mechanical reliability is improved, but bump pitch increases due to solder protrusion
Solution Approach 1:
A mask is applied to the substrate before applying solder material, pre-defining the areas where solder should be contained. This preliminary action prevents solder protrusion before it occurs, allowing the solder to be contained within the mask-defined areas and thus reducing the bump pitch while maintaining reliable mechanical attachment.
2Length of moving object
If metal projections are used instead of solder-only interconnects, then bump pitch is reduced, but manufacturing complexity increases
Solution Approach 1:
The interconnect structure is segmented into two distinct components: metal projections extending from the integrated circuit and solder material applied separately to attach these projections to the substrate. This segmentation allows each component to be optimized independently - the metal projections provide structural support and electrical connection, while the solder material provides mechanical bonding, thereby reducing bump pitch while maintaining manufacturability through standardized processes.
3Manufacturing precision
If solder material is contained using a photoresist mask, then solder protrusion is reduced, but manufacturing steps increase
Solution Approach 1:
The mask is applied directly to the substrate and serves a dual function: it defines the landing pad areas and simultaneously contains the solder material during the reflow process. The mask structure itself provides the containment mechanism, eliminating the need for separate containment structures or additional processing steps, thereby achieving precise solder containment while minimizing 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 configuration reduces bump pitch, allowing for more compact integration of interconnects and additional structures like I/O structures, while maintaining mechanical and electrical reliability through thermal expansion management.
Implementation Method 1
solder material for connecting the metal projections and the landing pads of the substrate
Data Source
AI summary
An integrated circuit/substrate interconnect apparatus and method are provided. Included is an integrated circuit including a plurality of bond pads, and a substrate including a plurality of landing pads and a mask. Such mask is spaced from the landing pads for defining areas therebetween. Further provided is a plurality of interconnects connected between the bond pads of the integrated circuit and the landing pads of the substrate. The interconnects include metal projections extending from the bond pads and a solder material for connecting the metal projections and the landing pads of the substrate.