Photosensitive Polyimide Insulating Layer for High-Density PCB
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Solution Overview
Problem
The miniaturization of printed circuit boards faces challenges with high electromagnetic interference and noise interferences due to the thickness and complexity of existing manufacturing methods, which require high-temperature pressing and result in a thick insulating layer, making it difficult to achieve high-density interconnection and reducing manufacturing efficiency.
Innovation Solution
A novel printed laminated circuit board using a vertical conductive unit with a photosensitive polyimide insulating layer having a low glass transition temperature, allowing for low-temperature pressing and reducing the thickness of the insulating layer, thereby decreasing the overall thickness of the circuit board and simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the insulating layer is increased to meet breakdown voltage requirements, then electrical insulation is improved, but the overall thickness of the circuit board increases and wiring density decreases
Solution Approach 1:
The patent changes the material parameter of the insulating layer from conventional epoxy resin to polyimide resin, which has inherently higher dielectric strength. This material parameter change allows the insulating layer to achieve the required breakdown voltage (2 KV) with a reduced thickness of 15-25 μm, resolving the contradiction between electrical insulation reliability and physical thickness
Solution Approach 2:
The patent uses polyimide resin as a composite material that combines desirable electrical properties (high breakdown voltage), mechanical properties, chemical resistance, and low glass transition temperature in a single material system, eliminating the need for thick insulating layers while maintaining all required performance characteristics
2Reliability
If conventional epoxy resin is used for the insulating layer, then electrical properties are improved, but the glass transition temperature is too high requiring high-temperature pressing
Solution Approach 1:
The patent changes the thermal parameter (glass transition temperature) of the insulating material from epoxy resin (high Tg) to polyimide resin (low Tg). This parameter change enables the material to be processed at low temperatures (below 200°C) while maintaining desirable electrical properties, resolving the contradiction between electrical reliability and processing temperature
3Reliability
If multiple lamination layers with adhesive layers are added to achieve electrical connection, then interlayer connectivity is improved, but the overall thickness increases and manufacturing complexity increases
Solution Approach 1:
The patent merges the functions of the insulating layer and the adhesive layer into a single polyimide resin layer. This merged structure eliminates the need for separate adhesive layers and multiple lamination steps, achieving both electrical insulation and interlayer connectivity while simplifying the manufacturing process and reducing overall thickness
4Object-affected harmful factors
If the spacing between parallel wires is enlarged to reduce electromagnetic interference, then noise interference is reduced, but wiring density decreases
Solution Approach 1:
The patent changes the dielectric parameter (breakdown voltage and insulating performance) of the insulating layer by using polyimide resin. This parameter change allows the insulating layer to provide superior electromagnetic shielding and noise reduction performance at reduced thickness, enabling tighter wire spacing while maintaining low EMI, thus resolving the contradiction between interference reduction and wiring density
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 significantly decreases the thickness of the insulating layer, reduces manufacturing costs, and enhances microstrip wiring density while minimizing noise interferences such as near-end crosstalk and electromagnetic interference.
Implementation Method 1
the insulating layer comprises photosensitive polyimide
Implementation Method 2
A plurality of the vertical conductive units according to the present invention can be stacked on each other to form a printed laminated circuit board
Data Source
AI summary
The invention provides a vertical conductive unit. The vertical conductive unit comprises an insulating layer comprising a connecting via, a first conductor, a second conductor, and a third conductor. The insulating layer comprises photosensitive polyimide, and the glass transition temperature of the photosensitive polyimide is lower than about 200° C. The invention also provides a method for manufacturing the vertical conductive unit.