Jetting or non-contact dispensing is an additive process where a material is deposited by rapidly shooting it at a substrate without making any physical contact. Like dispensing, it is a drop on demand process which produces consistent results and minimum material wastage. It is a versatile process which allows device designers to make advanced package designs for smaller and more interesting products as a material can be deposited in any shape or pattern. Jetting based dispensing for electronic packaging and precision manufacturing allows device designers to make advanced package designs for smaller and more interesting products. The following features make it useful for flip-chip underfilling and stacked-die applications. It has been used to manufacture flat panel displays and sensitive MEMS device packaging.
The major difference between dispensing and jetting is that jetting does not require contact with a substrate for deposition. During deposition a dispenser may have a lot of movement in the z-axis whereas z-axis motion is often not required for jetting depositions. The elimination of the z-axis movement increases the speed of deposition as the jetting head does not need to stop, go close to the surface to deposit and then lift up. Jetting offers higher consistency compared to dispensing as the volume of the deposition is precisely controlled by the valve. Jetting also eliminates any dripping, tails or strings as the nozzle contents do not come into contact with the substrate surface. Jetting can offer more accurate depositions in tight spaces without any risk of colliding with surrounding components/depositions.
For packaging applications, jetting is particularly useful for underfills and stacked-die applications where the components are laid out closely together with very small spaces between them. It has been used to manufacture flat panel displays and sensitive MEMS device packaging. Jetting can also be used for conformal coating and glob-top encapsulations. It offers an accurate, repeatable and consistent method of encapsulation. The shape and size of the encapsulation is only limited by the maximum deposition area of the stages and is compatible with a wide range of substrates and materials.
A robotic dispenser system consists of a pneumatic dispenser unit, XYZ movement stage, a syringe and a computer. A material to be dispensed is placed in the syringe, one end of the syringe is connected to an air hose which directs compressed air to the syringe and the other end has nozzle which directs the flow of ink on to the substrate. The dispenser unit controls and coordinates the air pressure applied to the contents of the syringe including the length of time the pressure is applied to the syringe. XYZ stages control the movement of the substrate and define area of substrate for material deposition. A computer coordinates the function of the dispenser unit and the movement stages. They are often determined by the application requirements of the electronics to be encapsulated.
The following are the jetting parameters which are used for defining a jetting deposition.
The Advanced Packaging Facility has a Nordson table top industrial jetting system. It consists of a robotic 3-axis movement stage, Integrated Keyence vision system, Nordson PICO valve and Nordson valve driver. The following are the specifications of the jetting system.