Heat Spreader Attachment Using Laser-Ablated Mold Cap TIM Cavity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for attaching heat spreaders to semiconductor packages are complex and prone to issues such as cracking of semiconductor components, voids in thermal interface materials (TIM), and non-uniform TIM distribution, which can lead to inefficient heat dissipation and electrical failures.
Innovation Solution
A method involving a semiconductor package with a mold cap made of laser-activatable mold compound, where a cavity is formed above the semiconductor component by laser ablation, transforming the inner surface of the cavity into a conductive layer, and dispensing a TIM layer that protrudes from the mold cap, allowing for improved attachment of a heat spreader.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a thermal interface material (TIM) layer is applied on an outer surface of the mold cap to facilitate heat dissipation, then heat dissipation is improved, but the manufacturing complexity increases due to additional plating processes and the risk of cracking and delamination increases
Solution Approach 1:
The invention merges the mold cap structure with the TIM layer by forming the TIM layer directly on the outer surface of the mold cap during the molding process itself. This integration eliminates the need for separate plating processes and TIM application steps, thereby reducing manufacturing complexity while maintaining effective heat dissipation from the semiconductor chip through the mold cap to the external environment
Solution Approach 2:
The TIM layer is prepared and positioned on the mold cap surface before the final assembly and bonding steps. By pre-forming the TIM layer on the mold cap during molding, the invention eliminates subsequent plating operations and reduces the sequence of manufacturing steps, thereby simplifying the overall process while ensuring proper thermal interface is established before component assembly
2Temperature
If a TIM layer is formed between the semiconductor package and the heat spreader, then heat dissipation is improved, but voids may be formed in the TIM layer and the TIM material may not be well controlled in shape, resulting in electrical failure
Solution Approach 1:
The TIM layer is pre-formed on the mold cap outer surface with controlled thickness and uniform distribution before heat spreader attachment. This preliminary formation during the molding process ensures the TIM material is evenly distributed and properly positioned, preventing voids and shape control issues that would occur with post-assembly application methods
Solution Approach 2:
The invention replaces mechanical plating and TIM application processes with a molding-based TIM layer formation method. By using the molding process to directly form the TIM layer on the mold cap surface, the invention achieves superior uniformity and control over TIM thickness and distribution, eliminating the variability and defects associated with mechanical plating and manual or automated TIM application
3Shape
If the mold cap is ground to reduce thickness, then the profile is improved, but the semiconductor component may crack due to external damages applied during the grinding process
Solution Approach 1:
The invention replaces the mechanical grinding process with a molding-based thickness reduction method. By forming the mold cap with the desired final thickness profile directly through precision molding, the invention eliminates the need for subsequent grinding operations, thereby achieving the required mold cap profile without subjecting the semiconductor component to mechanical stress and cracking risks associated with grinding
Solution Approach 2:
The mold cap is formed with the target thickness profile during the initial molding process rather than requiring post-molding reduction. This preliminary formation of the final geometry ensures the semiconductor component is never exposed to damaging mechanical processes, while still achieving the desired thin profile for effective heat dissipation and proper assembly geometry
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 method simplifies the attachment process, reduces the risk of cracking, ensures uniform TIM distribution, and enhances heat dissipation by forming a reliable thermal path between the heat spreader and the semiconductor component.
Implementation Method 1
removing a portion of a thickness of the mold cap above the semiconductor component by laser ablation to form a cavity in the mold cap
Implementation Method 2
transform the laser-activatable mold compound at an inner surface of the cavity to a conductive layer
Implementation Method 3
A TIM layer 16 is formed between the semiconductor package 12 with a heat spreader 14 to facilitate heat dissipation
Data Source
AI summary
A method for attaching a heat spreader to a semiconductor package is provided. The method comprises: providing a semiconductor package, wherein the semiconductor package comprises a package substrate, a semiconductor component mounted on the package substrate and a mold cap formed on the package substrate and encapsulating the semiconductor component, and wherein the mold cap comprises a laser-activatable mold compound; removing a portion of a thickness of the mold cap above the semiconductor component by laser ablation to form a cavity in the mold cap and transform the laser-activatable mold compound at an inner surface of the cavity to a conductive layer; dispensing a thermal interface material (TIM) in the cavity to form on the conductive layer a TIM layer that protrudes from the mold cap; and attaching the heater spreader to the semiconductor package at least through the TIM layer.