Contoured Package-on-Package Joint for Reduced Thickness
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Solution Overview
Problem
The semiconductor industry faces limitations in reducing the total thickness of package-on-package (PoP) technology due to constraints in solder ball joint height and pitch, which hinders further integration density and miniaturization of electronic components in devices like smartphones.
Innovation Solution
The implementation of contoured mounting studs, formed through electroplating or etching processes, allows for a finer bond pitch and reduced separation between adjacent joints by creating a complementary shape with connecting members, such as solder balls, to enhance contact area and prevent deformation, thereby enabling thinner and more densely integrated packages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If traditional solder ball joints are used in PoP technology, then the package can be assembled, but the total thickness cannot be reduced further due to constraints in solder ball joint height and pitch
Solution Approach 1:
The patent changes the geometric parameters of the mounting structure by transitioning from spherical solder balls to contoured studs with non-spherical geometries (e.g., flat tops, tapered sides). This parameter change allows for reduced pitch and height while maintaining structural integrity, directly addressing the thickness reduction goal without being constrained by traditional solder ball dimensions
Solution Approach 2:
The patent applies curvature principles in reverse by removing the spherical shape from mounting joints and replacing it with contoured, non-spherical geometries. The contoured studs feature flattened tops and tapered sides, which prevent deformation during assembly and allow for tighter pitch spacing, thereby enabling thinner package profiles
2Productivity
If the pitch between adjacent joints is reduced to increase integration density, then more components can be integrated, but the structural integrity and reliability of joints deteriorate
Solution Approach 1:
The patent applies local quality by creating contoured studs with varying geometries at different locations - the tapered sides provide structural strength for small pitch spacing, while the flat top surfaces provide large contact areas for reliable electrical and mechanical connection. This localized optimization of geometry allows high integration density without sacrificing joint reliability
Solution Approach 2:
By replacing spherical solder balls with contoured studs that have flattened tops and tapered sides, the patent eliminates the deformation issues inherent in spherical joints at small pitches. The non-spherical geometry provides inherent mechanical support and larger contact area, maintaining structural integrity and reliability even when pitch is reduced to increase integration density
3Volume of moving object
If smaller packages are used to reduce device size, then electronic components can be miniaturized, but the mounting joint deformation risk increases
Solution Approach 1:
The patent eliminates the spherical shape of traditional solder balls and replaces it with contoured studs featuring flat tops and tapered sides. This geometric modification prevents deformation during the reflow process and package assembly, as the flat top surface distributes stress evenly and the tapered sides provide structural support, thereby eliminating joint deformation risk in miniaturized packages
Solution Approach 2:
The patent changes the geometric parameters of mounting joints from spherical dimensions to contoured dimensions with flat tops and tapered sides. This parameter change allows the joints to maintain their shape and structural integrity even in smaller packages, preventing deformation while enabling package miniaturization
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 approach enables a significant reduction in package thickness and pitch, allowing for denser integration of electronic components without compromising structural integrity or increasing the risk of solder deformation, thus supporting the miniaturization of electronic devices.
Implementation Method 1
The mounting stud may have a contoured stud surface formed thereon. The contoured stud surface may be formed using an etching process, a mechanical process, or the like. In one embodiment, the contoured stud surface may be formed by electroplating a connecting member onto the mounting stud
Implementation Method 2
The contoured stud surface may be formed using an etching process, a mechanical process, or the like
Data Source
AI summary
A contoured package on package joint and a method for making the same are disclosed herein. A method for forming a device comprises providing a substrate having a package land and forming a mounting stud on the package land. A molded underfill is applied to the substrate and in contact with the mounting stud. A contoured stud surface is formed on the mounting stud is contoured and connecting member attached to the contoured stud surface with a second package attached to the connecting member. The connecting member may be solder and have a spherical shape. The contoured stud surface may be etched or mechanically formed to have a hemispherical shape conforming to the connecting member shape.