Polyamide-imide Resin Layer for Flexible Metal-Cladded Base Material
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Flexible printed wiring boards with multilayer structures face challenges in achieving high productivity, dimensional accuracy, easy-bending properties, and heat resistance due to insufficient adhesive properties of anchor coat layers and resin sheets with metal foils, which require costly high-temperature processing and surface treatments.
Innovation Solution
A flexible metal-cladded base material comprising a metal foil with a first resin layer made of a polyamide-imide resin containing specific constituent units, and optionally a second resin layer in a B-stage state, which improves adhesion and eliminates the need for surface treatments, allowing for lower processing temperatures and enhanced mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a resin sheet with a metal foil is used to form the electrically insulating layer, then the flexible printed wiring board can be manufactured, but the easy-bending properties of the cured product of the resin layer are insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the resin layer by incorporating a polyimide component and controlling the resin composition ratio. This parameter change transforms the resin layer from a standard epoxy-based material to a polyimide-modified material that maintains both manufacturability and superior easy-bending properties after curing.
Solution Approach 2:
The patent creates a composite resin layer by combining epoxy resin with polyimide components. This composite structure integrates the adhesive properties of epoxy with the flexibility of polyimide, achieving both strong bonding to the metal foil and excellent easy-bending characteristics in the final cured product.
2Reliability
If the anchor coat layer is formed by heating the varnish at a high temperature of 300°C or higher to promote cyclization of the polyamic acid, then the anchor coat layer containing polyimide can be formed, but the resin sheet with a metal foil may warp due to contraction of the anchor coat layer upon cooling
Solution Approach 1:
The patent fundamentally changes the formation mechanism of the anchor coat layer by using pre-formed polyimide particles instead of requiring in-situ cyclization of polyamic acid. This parameter change eliminates the need for high-temperature heating (300°C or higher) and the subsequent thermal contraction that causes warping, while still achieving reliable adhesive properties.
3Productivity
If an adhesive resin layer is placed on the anchor coat layer without surface treatment, then the production efficiency is improved, but the adhesive properties of the anchor coat layer are insufficient
Solution Approach 1:
The patent creates a composite structure where the anchor coat layer contains polyimide particles embedded in a resin matrix. This composite composition provides both sufficient adhesive strength for bonding the adhesive resin layer and maintains high production efficiency by eliminating the need for additional surface treatment steps.
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 solution enhances the productivity and dimensional accuracy of printed wiring boards by providing good easy-bending properties and heat resistance without the need for surface treatments, while maintaining flexibility and reducing processing costs.
Implementation Method 1
it is necessary to cause imidization of the polyamic acid by promoting cyclization of the polyamic acid by heating the varnish
Implementation Method 2
heating the varnish at a high temperature of 300° C. or higher
Implementation Method 3
the anchor coat layer would greatly contract as a result of cooling, and such contraction may cause a warp of the resin sheet with a metal foil
Implementation Method 4
by simply volatilizing a solvent from the varnish, an anchor coat layer containing the polyimide can be formed
Data Source
AI summary
The flexible metal-cladded base material pertaining to the present invention includes a metal foil and a first resin layer. The first resin layer is of a first resin composition containing a polyamide-imide resin. The polyamide-imide resin includes a first constituent unit represented by Formula (1) and a second constituent unit represented by Formula (2). The percentage of the second constituent unit is in a range of 5 to 35% by mol.