Electrostatic Particle Deposition for Precision Solder Bumps
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Solution Overview
Problem
Traditional methods for applying particles to substrates, such as solder alloy on silicon wafers, face challenges in precision and uniformity due to 'edge effects' and the need for varying solder bump thicknesses, which are cumbersome to achieve with traditional stencil printing methods.
Innovation Solution
A method involving electrostatic or electrokinetic deposition of particles onto substrates using masked surfaces with controlled charging and potential differences to precisely deposit particles in patterns, reducing edge effects and enabling uniformity and varying thicknesses in a single-step process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional stencil printing methods are used to apply particles to substrates, then the process is simple and straightforward, but the precision and uniformity of particle deposition deteriorates due to edge effects and inability to control varying thicknesses
Solution Approach 1:
The patent replaces traditional mechanical stencil printing methods with electrostatic or electrokinetic field-based particle deposition. By applying electrical charges to masked surfaces and using charged particles in a fluid medium, the system achieves precise particle placement through electrostatic attraction and repulsion forces, eliminating edge effects and enabling controlled varying thicknesses without complex mechanical adjustments
Solution Approach 2:
The patent controls particle deposition by adjusting electrical parameters including voltage levels, charge polarity, and charge magnitude on masked surfaces. By varying these electrical parameters, the system can precisely control particle attraction strength, deposition patterns, and layer thickness, enabling both uniform and varying thickness deposits as needed for different application requirements
2Manufacturing precision
If traditional powder application methods are used, then the equipment is simple, but the precision required for appropriate pattern formation deteriorates
Solution Approach 1:
The patent replaces mechanical powder application with electrostatic field-controlled particle deposition. Charged particles in a fluid medium are attracted to or repelled from charged masked surfaces, enabling precise pattern formation on substrates with high concentration connection points and fine pitch spacing that cannot be achieved with traditional mechanical methods
Solution Approach 2:
The system uses feedback from electrical field interactions to control particle deposition. The charged masked surfaces create electrical fields that attract or repel charged particles, and by monitoring and adjusting the electrical parameters, the system achieves uniform particle distribution without overdeposition or stray particles
3Manufacturing precision
If deposition processes are used without electrostatic control, then the process is simple, but edge effects cause non-uniform particle distribution around the periphery
Solution Approach 1:
The patent replaces uncontrolled mechanical deposition with electrostatic field-controlled deposition. By applying electrical charges to masked surfaces and using charged particles in a fluid medium, the system achieves precise particle placement through electrostatic attraction and repulsion forces, eliminating edge effects and enabling controlled varying thicknesses without complex mechanical adjustments
Solution Approach 2:
The patent applies preliminary electrostatic charging to masked surfaces before particle deposition. By pre-establishing the electrical field pattern on masked surfaces, the system prevents edge effects from occurring during deposition, as the electrical forces uniformly distribute particles across all areas including peripheries
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 precise and uniform particle deposition, reducing edge effects and allowing for controlled solder bump thicknesses, enhancing the precision and efficiency of substrate preparation for electronic devices.
Implementation Method 1
applying an electrostatic charge to at least some of the masked surfaces of the substrate to yield charge-holding masked surfaces
Implementation Method 2
exposing the substrate with the charge-holding masked surfaces thereon to the particles in a fluid medium... thereby electrostatically depositing the particles onto the unmasked surfaces of the substrate
Implementation Method 3
attaching the electrode and counterelectrode to opposite poles of a voltage supply to establish an electrical potential between the counter electrode and the electrode and thereby electrokinetically depositing the particles on the unmasked portions of the substrate
Data Source
AI summary
A method for applying particles in a pattern to a substrate, either directly or by use of an intermediate tool, by electrokinetic or electrostatic means by exposing the substrate to particles in a fluid medium to electrokinetically or electrostatically deposit the particles onto the substrate.