Semiconductor Package Aperture Heat Spreader Thermal Stress
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Solution Overview
Problem
Semiconductor packages face cracking issues between the semiconductor die and the heat spreader due to differences in thermal expansion coefficients, leading to impaired thermal transfer and potential moisture ingress causing the 'popcorn phenomenon', which deteriorates electrical performance and can stop the device's function.
Innovation Solution
A semiconductor package design featuring a substrate with an aperture, where the semiconductor die is positioned within and attached to a heat spreader using a first adhesive with high thermal conductivity and a second adhesive with high adhesion, which spans the aperture and is peripherally attached to the substrate, encapsulated by an encapsulant, to manage thermal stress and prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat spreader is attached to a semiconductor die using adhesive, then thermal emission property is improved, but cracks form between the semiconductor die and heat spreader due to thermal expansion differences
Solution Approach 1:
The adhesive layer is segmented into multiple regions with different properties: a first adhesive layer between the semiconductor die and heat spreader with high thermal conductivity, and a second adhesive layer between the substrate and heat spreader with high adhesion. This segmentation allows each adhesive layer to perform its specific function optimally while reducing overall thermal stress.
Solution Approach 2:
The patent changes the parameters of the adhesive materials used at different interfaces. The first adhesive is selected for high thermal conductivity to efficiently transfer heat, while the second adhesive is selected for high adhesion strength to prevent cracking at the substrate interface. This parameter optimization resolves the contradiction between thermal performance and structural reliability.
2Length of moving object
If the semiconductor package uses thin design with die in aperture, then package thickness is reduced, but thermal stress management becomes more difficult
Solution Approach 1:
The patent applies local quality by positioning the heat spreader to span the aperture and extend onto the substrate surface, creating different structural configurations in different regions. The adhesive layers are also applied locally at specific interfaces rather than uniformly throughout the package, allowing optimized stress distribution in the thin package structure.
3Temperature
If adhesive layers are used to attach heat spreader, then thermal emission is improved, but moisture may permeate through cracks causing popcorn phenomenon
Solution Approach 1:
The patent applies beforehand cushioning by using the second adhesive layer with high adhesion strength to prevent crack formation at the substrate-heat spreader interface before moisture can infiltrate. This preventive measure ensures that even under thermal stress, the adhesive bond maintains integrity and blocks moisture pathways, preventing the popcorn phenomenon.
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 effectively transfers heat from the semiconductor die to the heat spreader while minimizing interface cracks and preventing moisture ingress, ensuring reliable thermal emission and preventing the popcorn phenomenon.
Implementation Method 1
attached to a heat spreader by a first adhesive... effectively transfers heat from the semiconductor die to the heat spreader
Implementation Method 2
peripherally attached to a bottom surface of the substrate by a second adhesive... minimizing interface cracks
Data Source
AI summary
A semiconductor package and method of manufacture has a substrate having an aperture. A semiconductor die is positioned in the aperture of the substrate and attached to a heat spreader by a first adhesive and electrically coupled to the substrate by at least one conductive wire. The heat spreader spans the aperture and is peripherally attached to a bottom surface of the substrate by a second adhesive. An encapsulant encapsulates the aperture, the semiconductor die, and the electrically conductive wire.