Copper Foil Carrier Release Layer for Stable 350°C Separation
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Solution Overview
Problem
Conventional copper foils with carriers experience unstable releasability after being heated to high temperatures, particularly above 350°C, due to excessive increase in release strength, which makes it difficult to maintain stable separation of the carrier from the copper foil during the hot press process in multilayer printed circuit board manufacturing.
Innovation Solution
A copper foil with a carrier is designed, featuring a glass or ceramic carrier, an intermediate metal layer, and a release layer comprising a metal oxide sublayer and a carbon sublayer, which are deposited using physical vapor deposition (PVD), ensuring stable releasability even at high temperatures by preventing interdiffusion of metal elements and reducing additional intermetallic bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the copper foil with carrier is heated at high temperature during hot press process, then the insulating material is cured and bonding is achieved, but the release strength of the carrier increases excessively making separation difficult
Solution Approach 1:
The release layer is divided into two distinct sublayers: a adhesion promotion sublayer (metal oxide) that bonds to the intermediate layer, and a release promotion sublayer (carbon) that facilitates carrier separation. This segmentation allows the release layer to simultaneously provide strong bonding during hot press and easy release afterward, resolving the contradiction between bonding strength and releasability.
Solution Approach 2:
The release layer acts as an intermediary between the intermediate layer and the carrier. It mediates the bonding interaction during hot press (through the adhesion promotion sublayer) and enables easy separation afterward (through the release promotion sublayer), thus resolving the contradiction between maintaining strong bonding and achieving easy release.
2Ease of operation
If a single carbon layer is used as release layer, then the carrier is readily releasable at low temperature, but the release strength becomes unstable after heating to high temperature
Solution Approach 1:
The release layer is segmented into two functional sublayers with distinct properties. The adhesion promotion sublayer provides stable bonding that prevents excessive release strength increase at high temperature, while the release promotion sublayer maintains low-temperature releasability. This segmentation stabilizes the release strength across different temperature conditions.
Solution Approach 2:
The release layer's composition is changed from a single material (carbon) to a composite structure with two sublayers having different chemical and thermal properties. This parameter change in composition allows the release layer to exhibit stable release strength characteristics across a wide temperature range, from low temperature (easy release) to high temperature (stable bonding).
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
The copper foil with a carrier maintains stable releasability and prevents excessive increase in release strength, allowing for reliable separation of the carrier even after prolonged heating at 350°C or more, thus enhancing the manufacturing process of multilayer printed circuit boards.
Implementation Method 1
a release layer provided on the intermediate layer and comprising a metal oxide sublayer and a carbon sublayer
Implementation Method 2
preventing interdiffusion of metal elements and reducing additional intermetallic bonding
Data Source
AI summary
An extremely thin copper foil with a carrier is provided that can keep stable releasability even after being heated for a prolonged time at a high temperature of 350° C. or more. The extremely thin copper foil with a carrier includes a carrier composed of a glass or ceramic material; an intermediate layer provided on the carrier and composed of at least one metal selected from the group consisting of Cu, Ti, Al, Nb, Zr, Cr, W, Ta, Co, Ag, Ni, In, Sn, Zn, Ga, and Mo; a release layer provided on the intermediate layer and including a carbon sublayer and a metal oxide sublayer or containing metal oxide and carbon; and an extremely thin copper layer provided on the release layer.