Silver Deposit Levelling for Flat Die-Attach Features
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Solution Overview
Problem
Existing methods for producing silver deposits on substrates using printing machines result in non-uniform flatness, leading to issues such as die cracking during attachment, and limiting the horizontal extent of dies that can be safely attached.
Innovation Solution
A three-step process involving initial printing of a silver deposit, partial drying of the deposit to reduce tackiness, and subsequent levelling to achieve a flat feature, utilizing a combination of printing machines and surface modification modules within a production line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a printing machine is used to print silver deposit onto substrate, then equipment cost is reduced compared to stamping, but the deposit surface flatness becomes non-uniform with dog-ear defects
Solution Approach 1:
A levelling layer is applied beforehand to the stencil surface before printing. This preliminary action compensates for the dog-ear effect that occurs during printing, ensuring that the deposit surface becomes flat after printing without requiring post-processing or specialized expensive equipment.
2Ease of operation
If die is attached to deposit with dog-ear raised feature, then die attachment process can be performed, but die cracking occurs due to non-flat surface
Solution Approach 1:
The levelling layer is applied in advance to the stencil, creating a compensated surface that prevents dog-ear formation. This preliminary compensation ensures that when the die is attached to the printed deposit, the surface is already flat, preventing die cracking and ensuring die integrity.
3Ease of operation
If deposit horizontal extent is increased to accommodate die attachment, then die attachment is enabled, but print medium waste increases and minimum separation between adjacent dies is limited
Solution Approach 1:
By applying a levelling layer to the stencil before printing, the deposit surface flatness is compensated during the printing process itself. This allows the deposit to be printed with precise dimensions matching the die size without requiring excessive horizontal extent, thereby reducing print medium waste and allowing closer spacing of adjacent dies.
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 process effectively produces flat features with minimized height deviations, enabling safe attachment of dies without cracking and optimizing the use of print medium, thereby improving the efficiency and reliability of the semiconductor manufacturing process.
Implementation Method 1
The heating unit is configured to heat the printed deposit to a temperature sufficient to partially dry the upper surface of the deposit
Implementation Method 2
The levelling unit is configured to apply a levelling pressure to the modified deposit sufficient to level the upper surface of the modified deposit
Data Source
AI summary
A method for producing a flat feature on a substrate, comprises the steps of printing a deposit of print medium onto the substrate, the printed deposit comprising an upper surface, modifying the upper surface of the printed deposit, for example by partially drying the printed deposit, and levelling the modified deposit to produce a flat feature.