Semiconductor Package Thermal Management via Brazing Control
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Solution Overview
Problem
Hermetic semiconductor packages face issues with heat dissipation and ceramic terminal breakage due to steps formed between metal and heat radiator bodies during brazing, leading to inefficient heat transfer and potential package bending.
Innovation Solution
A semiconductor package design featuring a metal plate with a through hole for a metal block, where the metal block has a lower upper surface than the metal base, and a brazing material covering the block, ensuring efficient heat dissipation and minimizing thermal expansion differences between materials, with a ceramic part attached to the frame to reduce stress on the ceramic terminal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a heat radiator body is brazed to a metal base body, then heat dissipation efficiency is improved, but steps may form between the components causing package bending and ceramic terminal breakage
Solution Approach 1:
The patent controls the thickness of the brazing material layer to be within a specific range (3-10 μm) to minimize height difference between the heat radiator body and metal base body. This parameter control prevents step formation that would cause package bending while maintaining effective thermal contact for heat dissipation.
Solution Approach 2:
The patent applies a limited thickness of brazing material (not too thin to ensure thermal contact, not too thick to cause steps) to achieve the optimal balance between heat dissipation efficiency and mechanical stability, preventing ceramic terminal breakage.
2Loss of energy
If brazing material thickness is increased to ensure thermal contact, then heat dissipation is improved, but steps form causing package bending
Solution Approach 1:
The patent specifies that the brazing material thickness should be controlled within 3-10 μm to achieve optimal thermal contact without creating excessive height differences. This parameter optimization ensures heat dissipation efficiency while maintaining package flatness and preventing bending.
3Loss of energy
If different metals are used for heat radiator and base body to optimize thermal conductivity, then heat dissipation is improved, but thermal expansion differences cause stress and potential breakage
Solution Approach 1:
The patent selects materials with matched thermal expansion coefficients, specifically using Invar (a nickel-iron alloy) for the metal base body which has a thermal expansion coefficient similar to ceramic. This material selection minimizes thermal stress during temperature cycling while maintaining effective heat dissipation.
Solution Approach 2:
The patent employs a composite structure combining Invar metal base body with ceramic frame and heat radiator materials, leveraging the complementary properties of each material to achieve both thermal management and mechanical stability under thermal stress.
4Loss of energy
If the heat radiator body protrudes from the metal base body to improve heat contact with chassis, then heat dissipation is improved, but the step causes package bending and stress
Solution Approach 1:
The patent controls the brazing material thickness to minimize the height difference between the heat radiator body and metal base body, ensuring that the heat radiator does not protrude excessively. This parameter control reduces internal stress while maintaining adequate thermal contact with the chassis for effective heat dissipation.
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 prevents step formation, enhances heat dissipation, and reduces the risk of ceramic terminal breakage by minimizing thermal expansion differences and voids in the solder, resulting in a more reliable and cost-effective semiconductor package.
Implementation Method 1
a brazing material covering the upper surface of the metal block
Implementation Method 2
a solder provided on the brazing material, a semiconductor device provided on the solder
Implementation Method 3
the metal block is higher in thermal conductivity than the metal base
Implementation Method 4
a difference in thermal expansion coefficient between the metal base and the ceramic part is smaller than a difference in thermal expansion coefficient between the metal block and the ceramic part
Data Source
AI summary
A semiconductor package according to the present invention includes a metal plate, a metal base, provided on the metal plate, in which a through hole is formed, a metal block, provided in the through hole, a brazing material covering an upper surface of the metal block, a solder provided on the brazing material, a semiconductor device provided on the solder and a frame provided on the metal base, wherein the frame includes a ceramic part, a difference in thermal expansion coefficient between the metal base and the ceramic part is smaller than a difference in thermal expansion coefficient between the metal block and the ceramic part, the metal block is higher in thermal conductivity than the metal base, and an arithmetic average roughness of an upper surface of the brazing material is not more than a thickness of the solder.