Compressible Tray for Uniform IC Package Assembly
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Solution Overview
Problem
The assembly process for multi-integrated circuit (IC) packages faces challenges due to non-uniform force and heating applications, leading to mechanical stresses, cracking, and delamination, caused by variations in flatness of the heat spreader, assembly tray, and weights, resulting in uneven thermal interface material distribution.
Innovation Solution
A clamping assembly tray with a compressible member, such as springs or elastic materials, is used to provide a uniform support surface for IC packages, ensuring consistent pressure and heating across the package, balancing force variations and maintaining uniform thermal interface material distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If mechanical force is applied to heat spreaders at higher than room temperature during assembly, then the heat spreader attaches to the IC package, but non-uniform force application causes mechanical stresses resulting in cracking and delamination
Solution Approach 1:
The patent applies a compressible member that changes its mechanical properties under temperature variation. At elevated temperatures during assembly, the compressible member is softer and more compliant, allowing uniform force distribution. As the package cools to room temperature, the compressible member becomes stiffer, providing rigid support and maintaining uniform pressure distribution, thereby preventing cracking and delamination while ensuring strong attachment.
Solution Approach 2:
The compressible member acts as a cushioning element that compensates for variations in flatness of the heat spreader, assembly tray, and weights before the actual attachment process. By absorbing irregularities in the force application path, it ensures uniform pressure distribution across the IC package surface, preventing stress concentrations that would lead to cracking and delamination.
2Force
If mechanical force is applied through weights with variations in flatness, then the heat spreader is pressed onto the IC package, but non-uniform force distribution causes mechanical stresses and cracking
Solution Approach 1:
The compressible member's material properties change with temperature, allowing it to adapt its compliance characteristics. During the heating phase at assembly temperature, the member is more compliant and can conform to surface irregularities, ensuring uniform force distribution despite variations in weight flatness. This temperature-dependent parameter change resolves the contradiction between applying sufficient force and maintaining force uniformity.
3Ease of operation
If the assembly tray has variations in flatness, then it supports multiple IC packages during assembly, but non-uniform support causes non-uniform heating and mechanical stresses
Solution Approach 1:
The compressible member compensates for tray flatness variations through temperature-dependent compliance. At assembly temperature, its softer state allows it to conform to the non-uniform tray surface, providing uniform support to each IC package. This ensures both easy assembly operation and uniform heating, as the compressible member acts as an intermediate layer that equalizes the support surface.
4Ease of manufacture
If thermal interface material thickness varies across the IC package, then assembly is simplified, but areas of higher thermal resistance are created
Solution Approach 1:
The compressible member maintains uniform pressure on the thermal interface material throughout the assembly and cooling process. By compensating for variations in heat spreader and tray flatness through its temperature-dependent compliance, it ensures the thermal interface material is compressed uniformly across the entire IC package surface, eliminating localized areas of higher thermal resistance while keeping the assembly process simple.
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 reduces mechanical stresses and ensures uniform thermal interface material coverage, preventing cracking and delamination while maintaining consistent thermal resistance across the IC package.
Implementation Method 1
a compressible member disposed on the bottom surface of the frame within the cavity, where a top portion of the compressible member provides a support surface for supporting the semiconductor device
Implementation Method 2
ensuring consistent pressure and heating across the package, balancing force variations
Implementation Method 3
heating the semiconductor devices while applying pressure to the lids to form the plurality of IC packages
Data Source
AI summary
An example clamping assembly tray for packaging a semiconductor device includes a frame having a bottom surface and side walls extending from the bottom surface that define a cavity; and a compressible member disposed on the bottom surface of the frame within the cavity, where a top portion of the compressible member provides a support surface for supporting the semiconductor device, the support surface being between the bottom surface and a top edge of the side walls.