Embedded Heat Sink with V-Shaped Down Sets for Semiconductor Packages
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Solution Overview
Problem
Current thermal management solutions for semiconductor packages face challenges such as space constraints, quality issues with arrayed heat sinks, increased production time and costs, misalignment, and adhesive-related problems, which affect thermal performance and manufacturing efficiency.
Innovation Solution
A thermally enhanced semiconductor package with an integrated heat sink structure featuring a ring structure with slanted or V-shaped down sets, etched tie bars, and alignment holes, which is embedded during molding to ensure proper alignment and adhesion, and a method involving a mold release film and vacuum to maintain heat sink engagement and prevent mold flash.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a drop-in heat sink is embedded during encapsulation, then thermal management is improved, but it takes up space within the package constraining placement of active chips and other devices
Solution Approach 1:
The heat sink is nested within the mold cavity structure itself, with the heat sink positioned on the mold surface and the encapsulant molded around it. This integration allows the heat sink to be embedded during the encapsulation process without requiring additional package volume, as the heat sink becomes part of the molded assembly rather than a separate component occupying additional space.
2Temperature
If arrayed heat sinks with connecting down sets are used, then thermal management is improved, but quality issues such as mold flash occur during the molding process
Solution Approach 1:
The down sets are designed with preliminary anti-action features where the connecting portions extend below the heat sink base level, creating mechanical interlocks that prevent mold flash before it can occur during injection. The V-shaped or slanted configurations of the down sets redirect excess encapsulant material away from the heat sink edges, preventing flash formation at critical interfaces.
3Temperature
If heat sink is attached after singulation by adhesive layer, then thermal management is improved, but adhesive coverage is inconsistent leading to easy removal of heat sink
Solution Approach 1:
The adhesive-based mechanical attachment system is replaced with a molded mechanical interlock system. The down sets create physical interlocking features between the heat sink and the encapsulant, where the connecting portions extend into the encapsulant material to form integral mechanical bonds. This eliminates reliance on adhesive coverage consistency and provides reliable attachment through geometric interlocking.
4Temperature
If heat sink is attached after singulation, then thermal management is improved, but production time and costs increase
Solution Approach 1:
The heat sink attachment process is merged with the encapsulation molding process. The heat sink is positioned on the mold surface along with the substrate and chip assembly, and the encapsulant is molded around all components in a single operation. This integration eliminates separate attachment steps and enables mass production of thermally enhanced packages without additional process time.
5Temperature
If excessive adhesive is used to attach heat sink, then thermal management is improved, but adhesive bleed out contaminates package edges or contact pads
Solution Approach 1:
The adhesive application system is replaced with a mold-based mechanical interlock system. The down sets create physical interlocking features where the connecting portions extend into the encapsulant material, forming integral bonds without requiring adhesive materials. This eliminates the harmful effect of adhesive bleed out entirely by removing the adhesive application step.
6Temperature
If insufficient adhesive is used to attach heat sink, then thermal management is improved, but large gaps form that adversely affect thermal performance
Solution Approach 1:
The adhesive-based positioning system is replaced with mold-based mechanical positioning features. The down sets and connecting portions create geometric interlocks that precisely locate the heat sink relative to the substrate and chip assembly. The encapsulant flows around these interlocking features to create rigid mechanical bonds, eliminating gaps and ensuring precise alignment without relying on adhesive distribution.
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 provides improved thermal characteristics, simplifies manufacturing, enhances holding strength between the heat sink and encapsulant, and reduces production costs while maintaining high thermal performance, suitable for various package types including ball grid arrays and quad flat nonleaded packages.
Implementation Method 1
a heat sink in direct contact with the entire top surface of the encapsulant
Implementation Method 2
curing the encapsulant, whereby the heat sink structure adheres to the encapsulant
Implementation Method 3
placing a mold release film onto a second mold portion, clamping a second mold portion onto a portion of the heat sink structure
Data Source
AI summary
This invention includes a heat sink structure for use in a semiconductor package that includes a ring structure with down sets and a heat sink connected to the ring structure. The down sets can be slanted or V-shaped. The invention also includes a method of manufacturing a semiconductor package that includes inserting a substrate with an attached semiconductor chip in a first mold portion, placing a heat sink structure on top of a portion of the substrate, placing a mold release film onto a second mold portion, clamping a second mold portion onto a portion of the heat sink structure, injecting an encapsulant into a mold cavity, wherein the encapsulant surrounds portions of the substrate, semiconductor chip and heat sink structure, curing the encapsulant, whereby the heat sink structure adheres to the encapsulant and singulating the encapsulated assembly to form a semiconductor package.