Conductive Paste Gap Filling for EMI Shielding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for electromagnetic interference (EMI) shielding of electronic packages face limitations, including inferior conductivity, labor-intensive processes, high equipment costs, and difficulty in achieving uniform thin coatings, which affect the effectiveness and efficiency of EMI shielding.
Innovation Solution
The development of conductive formulations with a thermoset or thermoplastic matrix, conductive fillers, and optional diluents, designed to achieve high viscosity and thixotropic index, allowing for capillary flow to fill gaps and provide effective EMI shielding with thin coatings, improving conductivity and productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plating methods are used for EMI shielding, then full coverage and good thickness control are achieved, but pre-treatment and laborious masking are required
Solution Approach 1:
The patent extracts and eliminates the pre-treatment and masking steps from the plating process by using a screen printing method that directly applies conductive paste to the PCB surface without requiring surface preparation or masking operations
Solution Approach 2:
The patent replaces the electrochemical plating process with a mechanical screen printing process, substituting the complex electrochemical system with a simpler direct deposition method that achieves comparable thickness control without pre-treatment
2Reliability
If sputter methods are used for EMI shielding, then high electrical conductivity and effective shielding are achieved, but equipment cost is very expensive and UPH is very low
Solution Approach 1:
The patent uses inexpensive conductive paste materials instead of expensive sputtering equipment and materials, accepting that the paste-based coating is a consumable material that can be reapplied if needed, rather than using expensive vacuum deposition equipment
Solution Approach 2:
The patent employs screen printing technology that uses mechanical pressure and material flow to deposit conductive paste, replacing the vacuum-based sputtering process with a pressure-driven direct application method that enables higher throughput
3Ease of operation
If conductive paste adhesives are used for EMI shielding, then application is simplified, but very thick films are needed when electrical conductivity is not high
Solution Approach 1:
The patent optimizes the electrical conductivity parameter of the conductive paste formulation to achieve high conductivity values, which allows the use of thinner film coatings while maintaining effective EMI shielding performance
Solution Approach 2:
The patent uses composite conductive paste formulations containing metal particles or flakes in a adhesive matrix, combining the benefits of electrical conductivity with adhesive bonding properties to achieve both simplicity and thin-film capability
4Reliability
If regular spray or printing processes are used for conductive coatings, then EMI protection is provided, but uniform three-dimensional thin coating is difficult to produce
Solution Approach 1:
The patent uses screen printing with custom-designed screens that provide localized control over paste deposition, ensuring uniform coating thickness in three-dimensional areas by tailoring the screen aperture patterns to match the specific geometric requirements of the PCB features
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 achieves enhanced EMI shielding performance with thin coatings as low as 5 μm, higher unit production rates, and comparable metal coating effectiveness to sputter and plate processes, while overcoming the limitations of prior art methods.
Implementation Method 1
invention methods utilize capillary flow to substantially fill any gaps in the coating on the surface of an electronic package
Data Source
AI summary
Provided herein are conductive formulations which are useful for applying conductive material to a suitable substrate; the resulting coated articles have improved EMI shielding performance relative to articles coated with prior art formulations employing prior art methods. In accordance with certain aspects of the present invention, there are also provided methods for filling a gap in an electronic package to achieve electromagnetic interference (EMI) shielding thereof, as well as the resulting articles shielded thereby. Specifically, invention methods utilize capillary flow to substantially fill any gaps in the coating on the surface of an electronic package. Effective EMI shielding has been demonstrated with very thin coating thickness.