Multilayer Electronic Structure Via Formation
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Solution Overview
Problem
The existing 'drill & fill' method for creating vias in multilayer electronic support structures is limited by low throughput, high costs, difficulty in producing high-density vias of varying sizes and shapes, rough laser-drilled via walls, tapering, dimpling, overfill issues, and limitations in via geometry, which hinder the fabrication of high-density, reliable, and thin electronic components.
Innovation Solution
The method involves laminating copper substructures within a void-free dielectric material comprising continuous glass fibers in a polymer matrix, using a double action press pad to control dielectric thickness and achieve a smooth surface, and electroplating copper substructures with a pre-preg material under controlled pressure and temperature to create a stable and planar structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If laser drilling is used to create vias, then via channels can be formed, but the side walls become rough and tapered, reducing effective diameter and electrical contact quality
Solution Approach 1:
The patent replaces laser drilling (optical/thermal process) with mechanical punching or forming processes. This substitution eliminates the ablation-induced roughness and tapering characteristic of laser drilling, producing vias with smooth walls and precise cylindrical geometry that improve electrical contact and reduce stray inductances.
Solution Approach 2:
The patent changes the fundamental process parameter from thermal ablation (laser) to mechanical displacement (punching/forming). This parameter change transforms the via formation mechanism, achieving smooth walls and consistent dimensions without the harmful thermal effects and material removal irregularities of laser processing.
2Ease of manufacture
If drill & fill methodology is used, then vias can be created, but throughput rate is limited and fabrication costs become prohibitive for high-density substrates
Solution Approach 1:
The patent segments the via formation process from the subsequent filling and stacking processes. By creating all via channels simultaneously through punching or forming before any filling operations, the method enables parallel processing and eliminates the sequential bottleneck of individual via drilling, dramatically increasing throughput for high-density substrates.
Solution Approach 2:
The patent performs preliminary via channel creation through punching or forming at an early stage, before any filling or stacking operations. This preliminary action establishes all via geometries in advance, allowing subsequent copper filling and dielectric stacking to proceed independently and in parallel, thereby maximizing productivity.
3Adaptability or versatility
If different sized via channels are drilled and filled with metal, then different sized vias can be fabricated, but via channels fill at different rates causing dimpling or overfill
Solution Approach 1:
The patent creates all via channels of different sizes simultaneously through punching or forming before any filling operations. This preliminary establishment of diverse via geometries allows subsequent selective filling processes to target specific via sizes with optimized parameters, eliminating the problem of differential filling rates that occur when via channels are created and filled in sequence.
4Ease of manufacture
If laser drilled vias are used in composite dielectric materials, then via channels can be formed, but significant tapering and rough side walls occur due to ablation process
Solution Approach 1:
The patent replaces laser ablation (optical/thermal process) with mechanical punching or forming processes specifically for composite dielectric materials. This substitution eliminates the ablation-induced roughness and tapering, producing vias with smooth walls and precise cylindrical geometry that maintain electrical contact quality and reduce stray inductances in composite material stacks.
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 precise control of dielectric thickness and surface smoothness, reducing material waste and improving the reliability and electrical performance of multilayer electronic support structures, comparable to the drill & fill method in thickness control, while overcoming its limitations.
Implementation Method 1
cured resin having a highly planar surface covering upper ends of said via posts by less than 10 microns of cured resin
Implementation Method 2
pressing to pressures of 200 to 600 PSI
Implementation Method 3
electroplating copper substructures
Data Source
AI summary
A method of fabricating a multilayer electronic support structure comprising electroplating copper substructures, laying a dielectric pre-preg comprising a polymer resin over the copper substructures, and pressing to pressures of 200 to 600 PSI against a release film having a higher hardness than the resin of the prepreg but a lower hardness than the cured resin, and heating through a curing cycle while maintaining pressure.