Toray Industries, Inc., announced today that it has developed a negative photosensitive polyimide material (see glossary note 1). This new offering maintains the characteristic thermal resistance, mechanical properties, and adhesiveness of polyimides while increasing resolutions and enabling high-definition pattern formation on 100-micrometer and other thick films.
The number of electronic components in smartphones and other mobile devices will increase to accommodate the greater speeds and capacities of 5G, 6G, and subsequent broadband cellular networks. These devices will need more miniaturized electronic components and higher density mountings. Finer fabrication processes for polyimide materials will thus be necessary for the insulating layers of electronic components.
To date, these layers have often employed negative photosensitive polyimide materials delivering outstanding chemical resistance and reliability. The downside is low light transmittance. Photosensitivity deteriorates when thicknesses exceed 50 micrometers, preventing fine processing. Other issues are high thermal stresses after curing and significant warping, reducing reliability during processing.
Toray developed a negative photosensitive polyimide material that is 100 micrometers thick and can fabricate vias (glossary note 2) with 10 micrometer diameters. The company achieved this by leveraging the functional polyimide design technology it has amassed over the years to enhance light transmittance and control photoreactions.
Toray additionally made it possible to cut thermal stress to less than half that of regular polyimide materials and thus reduce warping by controlling polyimide resin cross-linking density from photoreactions during exposure and lowering curing shrinkage.
This material should make it possible to miniaturize electronic components and semiconductor package wiring and enhance reliability. Toray is shipping prototypes with a view to commercializing the material as a varnish and sheet.
The company aims to augment its lineup with grades with low thermal expansion coefficients and dielectric levels and small dielectric losses, offering them for semiconductor devices and electronic components that can drive ultrafast communication technologies.
Toray plans to deliver a presentation on its breakthrough at Wafer Level Package Symposium 2022, which starts on February 15, 2022.
Toray will continue leveraging its core technologies of synthetic organic and polymer chemistry, biotechnology, and nanotechnology to research and develop advanced materials that transform societies in keeping with its commitment to innovating ideas, technologies, and products that deliver new value.
1. Negative photosensitive polyimide : A cross-linked structure forms on exposed areas from a light-curing reaction in response to photoirradiation. While the exposed areas become insoluble in aqueous alkali, organic solvents, and other developing solutions, unexposed areas dissolve in developing solutions to enable the formation of via, lines, and other patterns.
2. Via : Hole for wiring to wiring connections between layers of multilayer boards and other devices.