IC Package Interconnect Surface Zoning for Solder Wetting
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Solution Overview
Problem
Existing interconnects for IC packages face challenges in achieving robust electrical communication and secure mounting while preventing solder bridges and ensuring effective adherence to the molding compound, as they are either solely oxidized or unoxidized, leading to either hindered solder wetting or bridging issues.
Innovation Solution
The interconnects are designed with a combination of spaced apart patches of unoxidized metal and a surrounding roughened metal region, allowing for improved solder wetting and secure mounting, while the roughened regions prevent solder bridges and enhance adherence to the molding compound.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the interconnect metal is oxidized to improve adherence to molding compound, then adherence is improved, but solder wetting is hindered and solder bridges occur
Solution Approach 1:
The interconnect surface is segmented into distinct regions: patches of unoxidized metal for soldering and surrounding roughened oxidized metal for molding adherence. This spatial segmentation allows each region to perform its specialized function without interference, resolving the contradiction between solder wetting and molding compound adherence
Solution Approach 2:
Different surface properties are applied to different locations on the interconnect. The patch areas maintain unoxidized smooth surfaces for optimal solder wetting, while the surrounding areas are oxidized and roughened for enhanced molding compound mechanical interlocking. This local differentiation of surface quality enables simultaneous optimization of both soldering and molding processes
2Reliability
If the interconnect metal is kept unoxidized to improve solder wetting, then solder wetting is improved, but adherence to molding compound deteriorates
Solution Approach 1:
The interconnect surface is divided into functional zones where unoxidized patches provide solder wetting and surrounding oxidized regions provide molding adherence, eliminating the need to choose between the two opposing requirements
Solution Approach 2:
The roughened oxidized metal surrounding the unoxidized patches acts as an intermediary structure that prevents solder from spreading beyond the patch boundaries while maintaining electrical connection. This intermediary zone controls solder flow and ensures proper solder joint formation without compromising molding compound attachment
3Strength
If the entire interconnect surface is roughened to improve molding adherence, then adherence is improved, but solder bridges occur and electrical isolation is compromised
Solution Approach 1:
Surface roughness and oxidation are applied locally only in areas where mechanical interlocking with molding compound is needed, while smooth unoxidized patches are preserved in areas requiring electrical connection and soldering. This localized application of surface treatment prevents solder bridges while maintaining electrical integrity
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 enables robust electrical communication and secure mounting without solder bridges, while improving the adherence of the molding compound to the interconnect, thus providing the benefits of both unoxidized and oxidized metal without their respective drawbacks.
Implementation Method 1
a region of roughened metal formed of oxidized metal
Implementation Method 2
The die is conductively coupled to at least a subset of the patches of unoxidized metal
Data Source
AI summary
An integrated circuit (IC) package includes an interconnect comprising patches of unoxidized metal that are circumscribed by a region of roughened metal formed of oxidized metal. The IC package also includes a die mounted on the interconnect. The die is conductively coupled to at least a subset of the patches of unoxidized metal.