Ceramic Substrate Air-Groove Structure for Warpage and Heat Dissipation
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Solution Overview
Problem
Conventional ceramic substrate units face challenges with warpage due to thermal expansion differences and high process costs, which affect bonding reliability and heat dissipation efficiency.
Innovation Solution
The ceramic substrate unit incorporates a ceramic substrate with an upper metal layer for semiconductor chip mounting and a lower metal layer with line grooves and recessed grooves, forming air gaps to manage thermal expansion and enhance heat dissipation, while using a brazing filler for bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the heat sink is made of aluminum or copper material with high thermal conductivity, then heat dissipation efficiency is improved, but warpage occurs due to difference in thermal expansion coefficient with ceramic substrate
Solution Approach 1:
The patent changes the material parameter of the heat sink from conventional aluminum or copper to AlSiC (silicon carbide reinforced aluminum) material. This material has a thermal expansion coefficient that closely matches the ceramic substrate, eliminating warpage during thermal cycling while maintaining sufficient heat dissipation capability through its composite structure.
2Strength
If soldering process is used to bond heat sink to ceramic substrate, then bonding strength is improved, but process cost increases due to solder paste, solder preform, and vacuum bonding equipment
Solution Approach 1:
The patent extracts and eliminates the soldering process from the manufacturing workflow. Instead of using solder paste, solder preform, and vacuum bonding equipment, the invention uses direct bonding between the AlSiC heat sink and ceramic substrate through metallization layers, removing the need for expensive soldering materials and equipment while maintaining bonding strength.
3Reliability
If high temperature bonding process is used, then bonding reliability is improved, but solder paste melts causing warpage and defects of heat sink
Solution Approach 1:
The patent changes the bonding process parameters by eliminating the need for high-temperature soldering. The direct bonding method using metallization layers on the AlSiC heat sink allows for reliable bonding at lower temperatures, preventing solder paste melting and subsequent warpage or defects in the heat sink structure.
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 effectively suppresses warpage, improves bonding reliability, and enhances heat dissipation efficiency, maintaining the semiconductor chip at a constant temperature without deterioration.
Implementation Method 1
a plurality of line grooves through which air flows are formed in an upper surface of the lower metal layer
Implementation Method 2
bonding the upper metal layer and the lower metal layer to the ceramic base
Implementation Method 3
there may occur warpage due to a difference in thermal expansion during a bonding process with the ceramic substrate
Data Source
AI summary
The present invention relates to a ceramic substrate unit and to a method for manufacturing same. The ceramic substrate has a plurality of line grooves, through which air flows, formed on an upper surface of a lower metal layer thereof, so that heat generated in a semiconductor chip can be released to the outside by air convection, and warping caused by a volume difference between an upper metal layer and the lower metal layer can be suppressed.