Laser-Defined Via Filling with Metal Paste for HDI PCBs
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Solution Overview
Problem
The manufacturing of high-density interconnect (HDI) boards is challenging due to the complexity and cost of forming conductive vias between layers of multilayer PCBs, which limits miniaturization and increases production time and cost.
Innovation Solution
The method involves using a laser system and flowable metal paste to fill through-holes in a substrate with lamination foils defining the top and bottom boundaries of the holes, allowing for precise and efficient formation of conductive vias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional electroplating or copper insertion methods are used to form vias, then conductive paths can be established between PCB layers, but the manufacturing process becomes complicated and time-consuming
Solution Approach 1:
The patent extracts and eliminates the complex intermediate steps of traditional via formation (drilling, electroplating, or copper insertion). Instead, it directly deposits conductive metal paste into pre-formed holes through a simplified printing process, removing unnecessary manufacturing stages while maintaining via functionality.
Solution Approach 2:
The patent replaces complex mechanical and chemical processes (drilling machines, electroplating baths, copper insertion equipment) with a printing-based metal paste deposition system. This substitution simplifies the manufacturing apparatus and process while achieving the same via formation objective.
2Reliability
If traditional via formation methods are used, then conductive connections are achieved, but production time and cost significantly increase
Solution Approach 1:
The patent performs preliminary actions by pre-forming holes in the substrate before the via formation step and using a printing process that directly deposits conductive material in a single operation. This eliminates the need for sequential operations (drilling then plating, or drilling then inserting copper), significantly reducing production time while ensuring via connectivity.
Solution Approach 2:
The patent merges multiple discrete via formation operations (hole creation and conductive material deposition) into a single integrated printing process. By combining these steps, the manufacturing cycle is shortened and production efficiency is improved while maintaining reliable via connections.
3Strength
If solder is allowed to spread out during attachment, then electronic components can be securely mounted, but the required area increases limiting miniaturization
Solution Approach 1:
The patent applies local quality by creating precisely defined via structures with controlled metal paste deposition. The vias are formed with specific geometries and material distributions that provide sufficient mechanical anchoring and electrical conductivity without requiring excessive solder spread, thus reducing the area occupied by each component while maintaining secure attachment strength.
4Manufacturing precision
If high-density interconnect boards are manufactured with traditional methods, then conductive nets can be formed, but the process complexity and cost increase significantly
Solution Approach 1:
The patent replaces complex mechanical drilling and electrochemical plating systems with a printing-based metal paste deposition system. This substitution enables high-density interconnect formation with precise control over via placement and dimensions, achieving high manufacturing precision while significantly simplifying the manufacturing process and reducing equipment complexity.
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 enables high-precision and high-speed production of PCB layers with conductive vias, reducing production time and cost while allowing for increased miniaturization and integration.
Implementation Method 1
A laser system is used to produce the substrate and to remove material from the substrate to form through-holes
Data Source
AI summary
In a method for filling through-holes of a substrate with a metal paste, an upper lamination foil is secured to the top surface of the substrate and a lower lamination foil is secured to the bottom surface of the substrate. A laser beam is used to generate a first plurality of holes in the upper lamination foil, and a second plurality of holes in the lower lamination foil. Respective locations of the first and second plurality of holes are aligned with the through-holes of the substrate. Metal paste is applied into the through-holes through the first plurality of holes using a squeegee or a knife. Any metal paste that is pressed out from the second plurality of holes may be scraped off by the squeegee or the knife and recycled. Finally, the upper and lower lamination foils may be removed from the substrate.