PCB Inter-layer Conductive Structure via Direct Copper Lamination
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Solution Overview
Problem
Conventional multi-layer printed circuit boards (PCBs) face challenges with high energy consumption, contamination, and voids in conductive holes due to electroplating, which hinder miniaturization, increase costs, and affect current intensity and density distribution, leading to larger hole sizes and increased board area.
Innovation Solution
A process involving a first and second insulating layer with conductive holes, where an electric contact material is inserted to form a conductive plug, and conductive layers are laminated on either side, allowing for efficient electric contact without extensive flanges, using materials like tin alloy that soften during reflow soldering for improved contact and reduced resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electroplating is used to form conductive holes, then electrical conduction between layers is achieved, but processing time increases, cost increases, and voids form in the holes
Solution Approach 1:
The patent extracts and eliminates the electroplating process from the manufacturing sequence, replacing it with a direct copper deposition method. This removes the harmful electroplating step while retaining the essential function of creating conductive pathways through the insulating layer, thereby reducing processing time and eliminating void formation.
Solution Approach 2:
The patent employs a consumable copper foil layer that is directly deposited and then patterned away where not needed. This disposable approach to copper deposition eliminates the need for durable electroplating infrastructure and reduces processing complexity, achieving conduction without the time-consuming electroplating steps.
2Reliability
If electroplating is used to fill holes, then conductive pathways are formed, but contamination increases and manufacturing cost increases
Solution Approach 1:
The patent converts the potential harm of direct copper deposition (which might leave residues) into a benefit by using a controlled lamination and patterning process. The copper foil is applied uniformly, then precisely patterned to form conductors only where needed, eliminating contamination while ensuring reliable conductive pathways.
Solution Approach 2:
The patent replaces the chemical electroplating system with a mechanical lamination and patterning system. Copper foil is physically laminated onto the insulating layer and then mechanically patterned, substituting chemical processes with mechanical ones to eliminate contamination while achieving the same conductive pathway formation.
3Reliability
If larger holes are used to reduce resistance, then current carrying capacity increases, but voids increase and board area increases
Solution Approach 1:
The patent changes the fundamental parameter of how conductivity is achieved - instead of varying hole size to reduce resistance, it uses direct copper deposition with controlled thickness and pattern density. This allows achieving the required current carrying capacity without increasing hole size, thereby maintaining compact board area while eliminating void formation.
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 reduces voids, minimizes board area, and enhances current intensity while lowering manufacturing costs and environmental impact by eliminating the need for electroplating, resulting in a more compact and reliable PCB design.
Implementation Method 1
using materials like tin alloy that soften during reflow soldering for improved contact and reduced resistance
Data Source
AI summary
For producing an inter-layer conductive structure of a circuit board, an insulating layer, a first conductive layer, a second conductive layer and an electric contact material are provided, wherein the insulating layer includes at least a conductive hole therein. The electric contact material is inserted into the conductive hole of the insulating layer to form a conductive plug, and the first and second conductive layers are laminated to opposite surfaces of the insulating layer, respectively. After lamination, the conductive plug has two ends thereof in electric contact with the first conductive layer and the second conductive layer, respectively.