Solder Preform with Alloy Layers for Void-Free Die Bonding
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Solution Overview
Problem
Conventional solder preforms for die bonding between semiconductor elements and substrates often result in weak bonding due to void formation around high melting point metal particles, leading to sloping or peeling issues, especially as semiconductor elements become smaller and soldered areas decrease.
Innovation Solution
A solder preform with high melting point metal particles dispersed in a solder sheet, where the particle diameter variation is limited to 20 micrometers and an alloy layer of the solder forms around the metal particles, ensuring metallic bonding and eliminating voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high melting point metal particles are interspersed in solder preform to maintain suitable clearance between portions to be soldered, then bonding strength is improved, but manufacturing complexity increases due to the need for precise particle size control and uniform dispersion
Solution Approach 1:
The patent specifies precise parameter ranges for metal particle diameter (30-70 micrometers) and particle size variation (standard deviation ≤ 2.0 micrometers) to optimize bonding strength while ensuring manufacturability. These parameter controls prevent void formation and maintain uniform solder distribution.
Solution Approach 2:
The patent applies local quality by controlling the distribution and size of metal particles at specific locations within the solder preform. The particles are uniformly dispersed throughout the solder material to locally prevent void formation at the bonding interface between semiconductor elements and substrates.
2Ease of manufacture
If metal particles with large size variation are used in solder preform, then ease of manufacture is improved, but bonding reliability deteriorates due to void formation around particles
Solution Approach 1:
The patent establishes strict parameter controls for metal particle size (diameter 30-70 micrometers with standard deviation ≤ 2.0 micrometers) to prevent void formation. This parameter optimization ensures both manufacturability and bonding reliability by eliminating the root cause of void formation around particles.
Solution Approach 2:
The patent uses metal particles as spacers that replicate the desired clearance geometry between bonding surfaces. The uniformly sized particles create consistent gaps that prevent solder shorting while ensuring reliable electrical and thermal contact.
3Productivity
If roller embedding method is used to disperse metal particles on solder sheet, then productivity is improved, but manufacturing precision deteriorates due to poor particle size control and non-uniform dispersion
Solution Approach 1:
The patent specifies precise particle diameter ranges (30-70 micrometers) and variation limits (standard deviation ≤ 2.0 micrometers) that must be achieved through the roller embedding process. These parameter controls ensure that productivity gains do not compromise bonding reliability.
Solution Approach 2:
The patent applies local quality control by ensuring uniform dispersion of metal particles throughout the solder preform. The roller embedding process is optimized to achieve consistent particle distribution at all locations, preventing localized void formation while maintaining high production efficiency.
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 enhances bonding strength by preventing void formation and maintaining semiconductor elements parallel to the substrate, even under external impacts, thereby improving the reliability of electronic components.
Implementation Method 1
an alloy layer of an alloy with the solder is formed around the metal particles
Implementation Method 2
ensuring metallic bonding and eliminating voids
Data Source
AI summary
A solder preform according to the present invention has a variation in the size of high melting point metal particles which is at most 20 micrometers when the metal particle diameter is 50 micrometers, and an alloy layer of the high melting point metal particles and the main component of solder is formed around the high melting point metal particles. In addition, no voids at all are present in the solder. An electronic component according to the present invention has a semiconductor element bonded to a substrate with the above-described solder preform and has excellent resistance to heat cycles.