Polyimide nozzle plates are bonded to inkjet printhead heater chips using a phenolic/polyvinylbutyral adhesive. A 25μm thick polyimide film is coated with a 12.5μm thick layer of a B-staged phenolic adhesive, which is cured after the nozzle plate is attached to the chip. B-staged phenolic materials undergo aging reactions at shipping and storage temperatures prior to being cured. This behavior makes it difficult to achieve consistent nozzle plate to chip adhesion. Understanding and quantifying the aging of the phenolic is necessary for predicting its adhesion performance before it is used in printhead production. In this study nanoindentation measurements of thermally aged phenolic adhesive samples were made in order to calculate the modulus of the material. Modulus measurements, XPS data, and nozzle plate adhesion results were then used as a basis for proposing a mechanism describing phenolic aging.
James M. Mrvos, Girish S. Patil, Elizabeth C. Dickey, Christopher T. Wonderly, "Measurement of Modulus Changes of a Phenolic Adhesive Using Nanoindentation for an Inkjet Printhead Nozzle Plate" in Proc. IS&T Int'l Conf. on Digital Printing Technologies (NIP17), 2001, pp 385 - 391, https://doi.org/10.2352/ISSN.2169-4451.2001.17.1.art00086_1