Printed Wiring Board Resist Coating Void Prevention
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Solution Overview
Problem
Existing methods for manufacturing printed wiring boards face challenges in preventing voids due to air bubbles trapped between seed layers and liquid resist coatings, which can lead to short circuits and defects in conductor circuits.
Innovation Solution
A method involving a coating system that includes a liquid resist coating device, a drying device for forming resist layers, and a heat and pressure application device to simultaneously apply heat and pressure to the resist layers on seed layers, effectively dissolving air bubbles and preventing voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If liquid resist is applied on seed layer by conventional coating methods, then the coating process is simple and fast, but air bubbles become trapped between seed layer and resist coating causing voids and short circuits
Solution Approach 1:
The patent applies preliminary action by heating the substrate to a predetermined temperature (e.g., 80-150°C) before applying the liquid resist coating. This pre-heating prepares the substrate surface to facilitate bubble removal during subsequent drying, allowing conventional coating methods to be used without causing voids or short circuits in the final conductor circuits
2Reliability
If heat and pressure are applied simultaneously to resist layer, then air bubbles are completely dissolved preventing voids, but the manufacturing process becomes more complex
Solution Approach 1:
The patent merges the drying function and pressure application function into a single integrated processing step. The drying device simultaneously applies both heat and pressure to the liquid resist coating, eliminating the need for separate drying and pressing equipment while completely removing air bubbles to prevent voids in conductor circuits
Solution Approach 2:
The drying device is designed with multi-functionality, serving both as a heating device and a pressure application device. This universal device performs multiple functions (drying, heating, and debubbling) in one unit, reducing overall system complexity while achieving void-free conductor circuits
3Device complexity
If conventional drying methods are used without pressure, then the drying process is simple, but air bubbles remain trapped causing voids in conductor circuits
Solution Approach 1:
The patent changes the physical parameters of the drying process by introducing pressure as an additional parameter alongside temperature. By applying predetermined pressure (e.g., 0.1-1.0 MPa) during drying at elevated temperature, air bubbles are forced out of the coating, ensuring high manufacturing precision and void-free conductor circuits without overly complicating the device structure
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
This approach ensures the formation of conductor circuits without voids, enhancing the yield and reliability of printed wiring boards by ensuring complete dissolution of air bubbles between seed layers and resist coatings.
Implementation Method 1
drying the liquid resist applied on the seed layer such that a resist layer is formed on the seed layer
Implementation Method 2
applying pressure and heat simultaneously to an entire surface of the resist layer formed on the seed layer
Implementation Method 3
applying pressure and heat simultaneously to an entire surface of the resist layer formed on the seed layer
Data Source
AI summary
A method for manufacturing a printed wiring board includes forming a seed layer on a surface of a resin insulating layer, applying liquid resist on the seed layer formed on the surface of the resin insulating layer, drying the liquid resist applied on the seed layer such that a resist layer is formed on the seed layer, applying pressure and heat simultaneously to an entire surface of the resist layer formed on the seed layer, forming a plating resist on the seed layer from the resist layer formed on the seed layer using a photographic technology, forming an electrolytic plating film on part of the seed layer exposed from the plating resist, removing the plating resist from the seed layer, and removing part of the seed layer exposed from the electrolytic plating film.