Lead Frame Ball Grid Array With Under-Die Traces
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current semiconductor packaging technologies face challenges in achieving high I/O density with robustness and cost-effectiveness, as they require multiple etching and plating steps, leading to increased form factor and cost, and often result in peeling issues due to thin packages and additional mounting steps for standoffs.
Innovation Solution
A semiconductor package design featuring routing traces under the die with standoffs formed by plating both sides of a copper substrate, allowing for increased contact density and reduced process steps, with standoffs that can be metallized for corrosion protection and enhanced solder adhesion, and an underfill layer for encapsulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple etching and plating steps are used to form routing traces and standoffs, then manufacturing precision can be improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the formation of routing traces and standoffs into a single plating step. The lead frame is plated on both sides simultaneously, creating routing traces on the first side and standoffs on the second side in one operation, eliminating the need for separate etching and plating steps that would otherwise be required
Solution Approach 2:
The lead frame serves multiple functions: it provides structural support, forms electrical routing traces, creates standoffs for spacing, and enables thermal management. This multi-functionality is achieved through a unified plating process that creates all these features simultaneously, reducing overall device complexity
2Productivity
If contact density is increased to achieve higher I/O density, then productivity is improved, but reliability deteriorates due to peeling issues
Solution Approach 1:
The patent moves contacts from the traditional peripheral arrangement to a three-dimensional configuration by placing routing traces underneath the die. This allows contacts to be distributed across multiple planes and locations, increasing I/O density without compromising the structural integrity of individual contact points
Solution Approach 2:
The plating process creates locally optimized contact structures with appropriate thickness and composition at each location. The routing traces and standoffs are plated with sufficient material depth to ensure robustness, while maintaining high contact density through strategic placement rather than uniform thin plating
3Volume of moving object
If package thickness is reduced to achieve smaller form factor, then volume is reduced, but strength deteriorates leading to peeling
Solution Approach 1:
The package structure is segmented into distinct functional zones: routing traces for electrical connection, standoffs for mechanical spacing and support, and plated regions for bonding. This segmentation allows each zone to be optimized independently, with standoffs providing localized strength support even in thin packages
Solution Approach 2:
The lead frame utilizes composite plating structures with multiple metal layers providing different properties. The plated regions combine structural metals for strength with conductive metals for electrical performance, creating a composite material system that maintains both thin profile and robustness
4Ease of operation
If standoffs are added as separate mounting components, then ease of operation is improved for PCB mounting, but device complexity and manufacturing cost increase
Solution Approach 1:
The standoffs are merged with the lead frame structure itself, formed through the same plating process that creates routing traces. This integration eliminates separate standoff components and their associated mounting steps, while still providing the necessary spacing and mechanical support functions
Solution Approach 2:
The lead frame structure provides its own standoff function through the plated regions on the second side. The plating process automatically creates elevated standoff structures that self-position and self-support, eliminating the need for external standoff components or additional assembly operations
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
The solution enables a robust, cost-effective semiconductor package with increased I/O density in a smaller form factor, reduced peeling issues, and improved thermal management, while maintaining a thin profile and ease of assembly.
Implementation Method 1
plating both sides of a copper substrate to form die attach pads and contacts
Implementation Method 2
When the copper is etched away, the remaining portions between the plated areas form standoffs
Data Source
AI summary
A package includes a first plated area, a second plated area, a die attached to the first plated area, and a bond coupling the die to the second plated area. The package further includes a molding encapsulating the die, the bond, and the top surfaces of the first and second plated areas, such that the bottom surfaces of the first and second plated areas are exposed exterior to the package. Additional embodiments include a method of making the package.