In print head manufacturing, chips with micro-machined silicon arrays are often attached to plastic holders. The micro-machined silicon plates are often covered by a thin and flexible glass membrane. The silicon array structure is in fluid communication with an ink reservoir, and includes multiple ink passageways communicating with ejection nozzles and having actuators (e.g. piezoelectric firing elements) that are selectively actuable to pressurize the ink and eject drops of ink onto print media. The silicon array structure is often adhesively bonded directly to the holder or mount, which can be made from plastic, composite, or other suitable material. In addition to serving as a structural mount or support for the printhead silicon, the holder frequently includes an ink reservoir and other components of the printing system.
One challenge presented by these structures is that there is a large difference in the coefficient of thermal expansion of silicon or glass and that of plastics. Consequently, differential thermal expansion of the silicon array and the plastic holder can produce significant mechanical stress in the glass membrane and the silicon plate. As a result of this stress the silicon array can bend or warp, causing the inkjet nozzles to loose directionality, or it can even crack, destroying the print head. This difference in expansion can also complicate print head production processes that involve the application of elevated temperature, and can complicate print head operation, since large temperature differences cannot be tolerated during operation.
While it is possible to construct a print head holder of a material having a coefficient of thermal expansion similar to silicon or glass, this is generally not economical or practical, and would adversely affect the cost of the print head module.