Sintering Film Die Attachment for Low-Pressure Chip Bonding
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Solution Overview
Problem
Conventional soldering methods are inefficient and costly, and there is a need for a more reliable and cost-effective method to attach components at low temperatures and pressures while maintaining high thermal and electrical conductivity.
Innovation Solution
A sintering material composition comprising metal powder, binder, and solvent is used to form a film, which is applied to a substrate and laminated onto components, followed by low-pressure and low-temperature sintering to create a bond with high thermal and electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional soldering methods are used, then components can be attached, but the process is inefficient and costly with high material loss
Solution Approach 1:
The patent changes the physical and chemical parameters of the attachment material by using metal powder with specific size distributions (d10, d50, d90 values) and chemical compositions (Cu, Ag, Au, Pd, Ni, Sn, Pb, In, Bi) to achieve efficient attachment with reduced material loss. The controlled particle size and composition enable better flow and distribution during the attachment process.
Solution Approach 2:
The patent employs a composite material consisting of multiple metal powders with different properties (Cu for conductivity, Ag for oxidation resistance, Au for reliability, Pd for cost-performance balance, Ni for strength, Sn/Pb/In/Bi for low-temperature processing). This composite formulation optimizes both attachment efficiency and material utilization.
2Reliability
If high temperature and pressure processing is used for sintering, then reliable attachment is achieved, but capital costs and energy consumption increase
Solution Approach 1:
The patent modifies the sintering parameters by using metal powder with optimized size distributions and compositions that enable sintering at lower temperatures and pressures while maintaining reliable attachment. The specific particle size ranges and metal compositions facilitate bonding at reduced energy input.
Solution Approach 2:
The patent applies local quality optimization by controlling the distribution and composition of different metal particles in specific regions of the attachment material, enabling reliable bonding at lower overall processing conditions. The localized presence of reactive metals (Sn, Pb, In, Bi) facilitates low-temperature sintering.
3Reliability
If conventional attachment methods are used, then components are bonded, but thermal and electrical conductivity are insufficient
Solution Approach 1:
The patent uses a composite material system with metals selected for their specific conductivity properties (Cu and Ag for high electrical and thermal conductivity, Au for excellent reliability and conductivity). This composite formulation achieves superior conductivity performance while maintaining manufacturability through standardized processing.
Solution Approach 2:
The patent optimizes the chemical composition parameters of the attachment material by controlling the ratios of conductive metals (Cu, Ag, Au) and reactive metals (Sn, Pb, In, Bi) to achieve enhanced thermal and electrical conductivity. The specific composition ranges are designed to maximize conductivity while preserving ease of manufacture.
4Ease of manufacture
If low temperature and pressure sintering is used, then capital costs are reduced, but achieving uniform bond thickness becomes challenging
Solution Approach 1:
The patent changes the physical parameters of the metal powder (size distribution, shape, surface characteristics) to enable uniform flow and distribution during low-pressure sintering. The optimized particle size ranges (d10, d50, d90 values) ensure consistent packing and bonding, achieving uniform bond thickness even at reduced processing pressures.
5Reliability
If metal powder with specific size distribution is used, then attachment quality is improved, but material cost increases
Solution Approach 1:
The patent employs a composite material system that combines expensive high-performance metals (Au, Ag) with more cost-effective metals (Cu, Ni, Pd) and low-cost reactive metals (Sn, Pb, In, Bi). This composite approach achieves high attachment quality through the synergistic properties of different metals while controlling overall material cost by optimizing the proportion of each component.
Solution Approach 2:
The patent applies local quality by concentrating expensive metals (Au, Ag) in specific regions or at critical bonding interfaces where their properties are most needed, while using more economical metals in other areas. This localized distribution maintains attachment quality while reducing overall material cost.
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 method achieves reliable attachment with reduced material loss, lower capital costs, and higher throughput, forming bonds with uniform thickness and improved thermal and mechanical properties, suitable for various industries including hybrid electric vehicles and consumer electronics.
Implementation Method 1
a binder having a softening point between about 50 and about 170° C.
Implementation Method 2
Sintering has emerged as an alternative technology to conventional soldering. Sintering typically involves high temperature and high pressure processing to attach various components of an assembly.
Implementation Method 3
a solvent in an amount sufficient to dissolve at least the binder
Data Source
AI summary
Methods for die attachment of multichip and single components may involve printing a sintering paste on a substrate or on the back side of a die. Printing may involve stencil printing, screen printing, or a dispensing process. Paste may be printed on the back side of an entire wafer prior to dicing, or on the back side of an individual die. Sintering films may also be fabricated and transferred to a wafer, die or substrate. A post-sintering step may increase throughput.