Circuit Substrate Insulating Layer Adhesion
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Solution Overview
Problem
Current semi-additive processes for fabricating circuit substrates with fine patterns and high density are costly and have lower process performance due to the limited use of specific materials like Ajinomoto build-up film (ABF) and poor adhesion of copper layers to non-ABF materials.
Innovation Solution
A manufacturing method involving the formation of a dielectric layer, an insulating layer, and an electroless plating layer, where the insulating layer has greater binding strength with the electroless plating layer than the dielectric layer, allowing for enhanced process performance without the need for specific materials like ABF, using thermosetting and thermoplastic resins, and electroless plating with metals like Cu, Ni, Ag, Cr, and Sn.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a non-ABF material is used as the dielectric layer, then production cost is reduced, but the binding strength between the copper layer and the dielectric layer deteriorates
Solution Approach 1:
An insulating layer is introduced as an intermediary between the dielectric layer and the electroless plating layer. This insulating layer serves as a mediator that provides excellent adhesion to the copper-based electroless plating layer, while allowing the use of cost-effective non-ABF dielectric materials. The insulating layer thus resolves the contradiction by decoupling the adhesion function from the dielectric material selection.
Solution Approach 2:
The patent employs a composite structure consisting of multiple layers: dielectric layer, insulating layer, and electroless plating layer. Each layer is selected for its specific properties - the dielectric layer for cost-effectiveness, the insulating layer for adhesion, and the electroless plating layer for conductivity. This composite approach allows optimization of each component independently, resolving the contradiction between cost and binding strength.
2Strength
If an ABF material is used as the dielectric layer, then the binding strength between the copper layer and the dielectric layer is improved, but production cost increases
Solution Approach 1:
The insulating layer acts as a mediator that transfers the adhesion function from the dielectric layer to itself. This allows the dielectric layer to be made from inexpensive non-ABF materials while the insulating layer provides the necessary binding strength for the copper layer, thus resolving the cost-strength contradiction.
Solution Approach 2:
The patent replaces the expensive ABF material with cheaper non-ABF dielectric materials. The adhesion function is then provided by the insulating layer, which is a more cost-effective solution. This substitution of expensive materials with cheaper alternatives while maintaining functionality embodies the principle of using cheap materials where appropriate.
3Ease of manufacture
If a thin copper layer is pressed on the non-ABF surface, then the circuit layer can be formed, but the process performance deteriorates due to poor adhesion
Solution Approach 1:
The insulating layer serves as an intermediary between the non-ABF dielectric layer and the thin copper layer. This mediator provides the necessary adhesion surface for the copper layer, enabling the semi-additive process to proceed effectively on non-ABF substrates. Without this intermediary, the poor adhesion would prevent successful circuit formation.
Solution Approach 2:
The patent changes the surface properties by introducing the insulating layer with specific adhesion characteristics. This parameter change in surface chemistry and morphology enables the thin copper layer to adhere properly to the non-ABF substrate, thereby improving process performance despite using alternative materials.
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 reduces production costs and improves process performance by forming a circuit substrate with a patterned conductive layer that has strong adhesion to the insulating layer, enhancing the overall manufacturing efficiency and reducing material limitations.
Implementation Method 1
An electroless plating layer is formed on the sidewall of the blind via and a remaining portion of the insulating layer
Data Source
AI summary
A manufacturing method of a circuit substrate includes the following steps. A dielectric layer is formed on at least one surface of a substrate. An insulating layer is formed on the dielectric layer. A portion of the insulating layer and a portion of the dielectric layer are removed, so as to form at least one blind via in the dielectric layer and the insulating layer. An electroless plating layer is formed on the sidewall of the blind via and a remaining portion of the insulating layer, wherein the binding strength between the insulating layer and the electroless plating layer is greater than that between the dielectric layer and the electroless plating layer. A patterned conductive layer is plated to cover the electroless plating layer.