Thermal Via Substrate With Sinter-Bonded Heat Dissipation Structure
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Solution Overview
Problem
Conventional electrical circuit substrates face challenges such as high manufacturing costs, substrate warpage, and unsuitability for high heat concentration applications due to complex and costly processes like embedding metal slugs, which affect die attach quality and reliability.
Innovation Solution
A substrate with thermal vias and a sinter-bonded thermal dissipation structure, where thermal vias extend to the mounting surface ensuring coplanarity, and a metal thermal dissipation structure is sintered to the vias using a low-temperature process, reducing warpage and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If metal slugs are embedded within substrate using conventional processes, then thermal dissipation is achieved, but manufacturing cost increases and substrate warpage occurs
Solution Approach 1:
The patent changes the temperature parameter of the bonding process by using eutectic bonding at lower temperatures (e.g., 183°C for Sn/Pb eutectic) compared to conventional high-temperature metal slug embedding. This parameter change enables thermal dissipation structures to be formed without the costly and warpage-inducing high-temperature processes, thereby resolving the contradiction between achieving thermal dissipation and maintaining ease of manufacture.
Solution Approach 2:
The patent employs composite material structures by forming metallurgical bonds between dissimilar metals (e.g., Cu-Sn-Pb eutectic systems) to create intermediate bonding layers. These composite structures enable effective thermal dissipation while using lower-temperature bonding processes, thus reducing manufacturing cost and preventing substrate warpage associated with conventional single-material high-temperature embedding.
2Temperature
If metal slugs are embedded within substrate using conventional processes, then thermal dissipation is achieved, but substrate warpage occurs affecting die attach quality
Solution Approach 1:
By changing the bonding temperature parameter to lower temperatures through eutectic bonding, the patent prevents thermal stress-induced substrate warpage. This maintains substrate coplanarity and manufacturing precision while still achieving effective thermal dissipation, thereby resolving the contradiction between thermal dissipation performance and substrate flatness.
Solution Approach 2:
The patent applies local quality by creating focused thermal dissipation paths through eutectic bonding regions specifically at thermal via locations, rather than uniformly heating the entire substrate. This localized bonding approach dissipates heat effectively where needed without causing global substrate warpage, thus maintaining manufacturing precision.
3Temperature
If conventional metal embedding processes are used, then thermal conduction paths are formed, but process complexity and cost increase
Solution Approach 1:
The patent merges multiple functions into a single eutectic bonding process step that simultaneously creates thermal conduction paths, forms metallurgical bonds, and establishes mechanical attachment. This consolidation of functions into one process reduces overall process complexity and manufacturing cost while achieving effective heat conduction, resolving the contradiction between thermal performance and process simplicity.
Solution Approach 2:
By changing the bonding temperature to eutectic points, the patent simplifies the bonding process from multi-step high-temperature sequences to single-step low-temperature bonding. This parameter change reduces process complexity while maintaining effective thermal conduction paths, thereby resolving the contradiction between heat conduction capability and process simplicity.
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 effective heat dissipation with reduced system thermal resistance by up to 40%, improved coplanarity, and lower manufacturing costs, while mitigating warpage issues.
Implementation Method 1
After a low-temperature sintering process, the metal thermal dissipation structure is attached to the interior surfaces of the substrate in the recess and to the interior ends of the thermal vias by the now-sintered metal layer
Implementation Method 2
the thermal via(s) being within the substrate and configured to conduct heat away from a die pad on a mounting surface of the substrate
Data Source
AI summary
A substrate is described with a thermal dissipation structure sintered to thermal vias. In one example, a microelectronic module includes a recess between first and second substrate surfaces. One or more thermal vias extend between the first substrate surface and the interior recess surface, wherein each of the thermal vias has an interior end exposed at the interior recess surface. A sintered metal layer is in the recess and in physical contact with the interior end of the thermal vias and a thermal dissipation structure is in the recess over the sintered metal layer. The thermal dissipation structure is attached to the substrate within the recess by the sintered metal layer, and the thermal dissipation structure is thermally coupled to the thermal vias through the sintered metal layer.