Multilayer PCB Via Hole Protection for Reliable Interlayer Connections
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Solution Overview
Problem
Existing methods for manufacturing multilayer printed circuit boards with high-speed signal transmission face challenges in ensuring interlayer connection reliability and productivity, particularly when using conductive paste for interlayer connection paths, due to differences in thermal expansion coefficients and potential damage during unnecessary portion removal.
Innovation Solution
A method involving the preparation of wiring substrates with insulating resin films and conductive pastes, where a protective film covers the conductive paste-filled via holes, allowing for precise removal of unnecessary portions without damaging the paste, followed by lamination to form exposed inner layer terminals and reliable interlayer connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conductive paste is used for interlayer connection paths to reduce transmission loss, then signal transmission quality is improved, but interlayer connection reliability deteriorates due to thermal expansion coefficient differences
Solution Approach 1:
The patent changes the physical state of the conductive paste by controlling its drying and curing processes. The paste transitions from a wet state (easy to fill) to a dried state (provides good adhesion and electrical conductivity) through controlled heating at specific temperatures, resolving the contradiction between filling ease and connection reliability
Solution Approach 2:
The patent uses a composite structure combining the conductive paste with the insulating resin film. The paste contains conductive particles suspended in a resin binder, creating a composite material that provides both electrical conductivity for signal transmission and mechanical adhesion for reliable interlayer connections
2Device complexity
If conventional manufacturing methods are used without protective films, then process simplicity is maintained, but productivity deteriorates due to paste damage during unnecessary portion removal
Solution Approach 1:
The patent applies a protective film to the conductive paste before the unnecessary portion removal process. This preliminary protective action prevents paste damage during subsequent processing steps, eliminating the need for rework and improving manufacturing productivity without significantly complicating the overall process
Solution Approach 2:
The protective film acts as an intermediary layer between the conductive paste and the mechanical removal tools. This intermediary protects the delicate paste during the removal of unnecessary portions, preventing damage while allowing the process to proceed efficiently
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 method enhances productivity and ensures high-yield manufacturing of multilayer printed circuit boards with reliable interlayer connections, capable of transmitting high-speed signals with low signal loss and allowing for flexible connections to electronic components.
Implementation Method 1
an insulating resin film having a low dielectric constant and a dielectric loss tangent (tan 5) has been studied to reduce transmission loss
Implementation Method 2
a conductive via formed of conductive paste as the interlayer connection path
Implementation Method 3
an adhesive insulating resin film is attached to a metal-clad laminate
Data Source
AI summary
A method for manufacturing a multilayer printed circuit board includes: preparing a first wiring substrate having a first insulating resin film having a first circuit pattern formed on a first main surface, and a first protective film releasably bonded to a second main surface; partially removing the first protective film and the first insulating resin film to form a bottomed via hole having the first circuit pattern exposed on a bottom surface; filling the bottomed via hole with a conductive paste; disposing a second protective film on the first protective film to cover the bottomed via hole filled with the conductive paste; removing an unnecessary portion of the first wiring substrate after the second protective film is disposed on the first protective film; and peeling off the first protective film and the second protective film from the first wiring substrate after the unnecessary portion is removed.