Semiconductor Die Bonding Void Prevention via Preheating Metal Paste
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Solution Overview
Problem
The challenge in die bonding semiconductor chips to boards is the formation of voids in the bonding layer due to the vaporization of organic components in metal pastes, leading to cracks and reduced production efficiency, especially when rapid temperature increases are used during sintering.
Innovation Solution
A method involving a metal paste with a controlled organic component percentage (3-8% by mass) is applied to the base member, preheated to dry the organic component, and then sintered with the semiconductor chip in a multi-layer stack, using a controlled heating process to form a bonding layer with reduced voids and increased efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If rapid temperature increase is used during sintering to improve production efficiency, then sintering time is reduced, but voids form in the bonding layer due to organic component vaporization
Solution Approach 1:
The patent applies a preheating step before sintering to gradually remove organic components from the metal paste. This preliminary action prevents sudden vaporization during rapid sintering, allowing high production efficiency to be achieved without forming voids in the bonding layer.
Solution Approach 2:
The patent controls the organic component content within a specific range (3-8% by mass) and uses a two-stage heating process with different temperature rates. This parameter control allows rapid sintering while preventing void formation through controlled organic component removal.
2Ease of manufacture
If organic component content in metal paste is increased to improve bonding material processability, then ease of manufacture is improved, but void formation increases during sintering
Solution Approach 1:
The patent optimizes the organic component content to a specific range (3-8% by mass) that balances processability and void prevention. This parameter optimization allows the bonding material to be easily applied while minimizing void formation during subsequent sintering.
Solution Approach 2:
The preheating step performs preliminary removal of organic components before the main sintering process. This preliminary action allows higher organic content to be used for better processability without causing excessive void formation during final sintering.
3Productivity
If sintering temperature is increased to reduce sintering time, then productivity is improved, but cracking occurs in the bonding layer
Solution Approach 1:
The preheating step performs preliminary organic component removal before high-temperature sintering. This preliminary action prevents cracking during rapid high-temperature sintering by eliminating the source of vapor pressure that would cause cracks.
Solution Approach 2:
The patent uses a two-stage temperature profile with controlled organic component content. This parameter control allows rapid high-temperature sintering to be performed without causing cracking, maintaining both productivity and bonding layer strength.
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 approach effectively reduces the formation of voids in the bonding layer, enhances bond strength, and improves manufacturing efficiency by allowing for a shorter sintering time without cracking, resulting in a reliable and efficient composite structure for semiconductor devices.
Implementation Method 1
a preheating step including heating the bonding material before the element to be bonded is stacked on the bonding material and thereby drying the bonding material until a percentage of the organic component in the bonding material becomes equal to or greater than 3% by mass and equal to or less than 8% by mass
Implementation Method 2
a sintering step including sintering the bonding material by heating the multi-layer stack in a heating furnace and thereby forming the bonding layer
Data Source
AI summary
A method for manufacturing a composite structure includes: an application step including providing a bonding material on a base member by applying a metal paste onto the base member; a preheating step including heating the bonding material before an element to be bonded is stacked on the bonding material and thereby drying the bonding material until a percentage of an organic component in the bonding material becomes 3% by mass and equal to or less than 8% by mass with respect to the bonding material; a mounting step including stacking the element to be bonded onto the bonding material and heating the bonding material to form a multi-layer stack; and a sintering step including sintering the bonding material by heating the multi-layer stack in a heating furnace and thereby forming the bonding layer.