Liquid Thermal Interface Material in Semiconductor Lid Cavity
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Solution Overview
Problem
Conventional thermal interface materials face challenges in achieving effective thermal contact and adhesion with stacked semiconductor dice, particularly due to non-planar arrangements and potential diffusion into critical circuit structures, while also requiring efficient heat transfer for high-power chips.
Innovation Solution
A method involving a semiconductor chip device with a circuit board and a lid having an internal cavity filled with a liquid thermal interface material, which establishes thermal contact with the chip and board, using a secondary lid or heat spreader to seal and enhance thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermal interface materials (pastes, gels, metals) are used to provide heat transfer pathway, then thermal contact is established, but adhesion to silicon is poor and reflow process is required which complicates manufacturing
Solution Approach 1:
The patent changes the physical state parameter of the thermal interface material from solid (conventional pastes, gels, metals) to liquid, enabling it to flow and conform to non-planar surfaces without requiring reflow processing. This liquid state allows the material to automatically wet and adhere to both the silicon chip and lid surfaces, eliminating the need for additional reflow steps while maintaining reliable thermal contact.
Solution Approach 2:
The liquid thermal interface material acts as an intermediary substance between the silicon chip and the lid, filling the gap and establishing thermal contact. Unlike conventional materials that require metallization stacks and reflow processes, the liquid material directly bonds to both surfaces through its flow properties, simplifying the manufacturing process while ensuring reliable thermal transfer.
2Productivity
If stacked dice arrangement is used to increase integration density, then productivity is improved, but non-planar arrangement makes thermal contact difficult and exposes sidewalls to solder diffusion
Solution Approach 1:
The patent applies hydraulic principles by using a liquid thermal interface material that flows under pressure to conform to the non-planar surfaces of stacked dice. The liquid material is introduced in a controlled manner, allowing it to penetrate and fill the irregular gaps between stacked chips, ensuring complete thermal contact without requiring precise planar alignment. This fluid-based approach eliminates the solder diffusion problem by providing a barrier that seals the sidewalls.
3Reliability
If reflow process is performed to establish thermal contact with solder material, then favorable thermal contact is achieved, but manufacturing complexity increases and sidewall exposure to solder diffusion occurs
Solution Approach 1:
The patent extracts the harmful reflow process from the manufacturing sequence by using a liquid thermal interface material that does not require high-temperature reflow to establish thermal contact. The liquid material can be applied at lower temperatures and maintains its bonding properties without the need for aggressive reflow heating, thereby eliminating the source of solder diffusion into critical circuit structures while still achieving reliable thermal contact.
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 configuration ensures reliable thermal contact and efficient heat transfer for semiconductor chips, even in stacked arrangements, by using a liquid thermal interface material that fills voids and maintains contact with both the chip and circuit board, effectively managing heat without compromising circuit integrity.
Implementation Method 1
A liquid thermal interface material is placed in the internal cavity for thermal contact with the first semiconductor chip and the circuit board
Data Source
AI summary
A method of manufacturing is provided that includes providing a semiconductor chip device that has a circuit board and a first semiconductor chip coupled thereto. A lid is placed on the circuit board. The lid includes an opening and an internal cavity. A liquid thermal interface material is placed in the internal cavity for thermal contact with the first semiconductor chip and the circuit board.