Crosslinkable Polymer Via Formation in Printed Circuit Boards
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Solution Overview
Problem
Current methods for manufacturing printed wire boards require cumbersome sequential curing and drilling processes to prevent via reflow, which can hinder interconnect formation and are inefficient for large-scale manufacturing.
Innovation Solution
A method involving lamination of a crosslinkable polymer composition with specific viscosity and molecular weight ranges, where vias are formed by laser ablation before curing, ensuring no reflow and maintaining addressability between layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the laminate is cured before via formation, then via reflow is prevented, but the process becomes cumbersome and less efficient
Solution Approach 1:
The patent applies preliminary action by forming vias in the uncured polymeric insulating layer before curing. The high viscosity composition prevents reflow during via formation, eliminating the need for pre-curing steps. This reverses the conventional sequence where curing must precede via formation, thereby improving productivity while maintaining via integrity through the inherent viscosity-based reflow prevention mechanism
2Ease of manufacture
If the polymeric insulating layer has low viscosity, then lamination is easier, but via reflow occurs during laser ablation
Solution Approach 1:
The patent applies parameter changes by optimizing the viscosity of the polymeric insulating layer to a high range (100-100,000 Pa-s) at processing temperature. This parameter change fundamentally alters the material behavior during via formation, preventing reflow while still allowing successful lamination. The high viscosity acts as a constraint that maintains via profile integrity during laser ablation, resolving the contradiction between ease of manufacture and manufacturing precision
3Reliability
If sequential curing and drilling is used, then each layer is individually addressable, but the process is time-consuming
Solution Approach 1:
The patent applies merging by combining multiple steps into a single integrated process. High viscosity polymeric insulating layers are laminated and then vias are formed through all layers in sequence without intermediate curing steps. The high viscosity material maintains layer integrity and prevents reflow throughout the entire via formation process, allowing multi-layer addressability to be achieved in one continuous operation rather than through repeated cure-drill cycles
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 allows for efficient and versatile large-scale manufacturing of printed wire boards with good via profiles and desmear results, preventing reflow and ensuring interconnect integrity.
Implementation Method 1
laminating a sheet having a layer comprising a crosslinkable polymer composition to a substrate
Implementation Method 2
forming at least one via in the crosslinkable polymer composition layer by laser ablation
Implementation Method 3
curing the crosslinkable polymer composition
Implementation Method 4
thermal curing in an oven to produce a cross-linked system
Data Source
AI summary
Disclosed herein is a method of forming vias in electrical laminates comprising laminating a sheet having a layer comprising a crosslinkable polymer composition to a substrate wherein the crosslinkable polymer composition has a viscosity at lamination temperatures in the range of 200 Pa-s to 100,000 Pa-s, forming at least one via in the crosslinkable polymer layer by laser ablation; and after the forming of the at least one via, thermally curing the crosslinkable polymer layer. According to certain embodiments the cross linkable polymer composition has a viscosity at lamination temperature of at least 5000 Pa-s. This method yields good lamination results, good via profiles, and good desmear results when such compositions are used and the via is laser ablated before cure.