Electronics Research and Development

Solder Jet® Technology

Solder Jet® technology is targeted for use in electronics assembly process where solder is utilized as an attachment and/or structural material for assembly of electronic components to substrates.

Solder Jet® technology is based on piezoelectric demand-mode ink-jet printing technology and is capable of placing molten solder droplets, 25-125µm in diameter, at rates up to 400 per second. Operating temperatures of 220ºC are normally used, and temperatures up to 300ºC have been demonstrated. This temperature range has been utilized to print conventional SnPb and lead free solder, such as SnCu, In and Sn. Solder jetting is an environmentally friendly process that does not require plating chemicals and prints only the desired amount of solder at an exact location.

Solder Jet® deposition is data driven, therefore no hard tooling such as phototools or screens are required. The figures below (courtesy of Motorola and Texas Instruments) illustrate the data driven nature of Solder Jet® technology. These logos were formed using 60µm diameter, 63/37 SnPb solder droplets.

One application of Solder Jet® deposition is wafer bumping. The figures below illustrate a perimeter array bumped with 60µm balls on 150µm centers and an area array bumped with 100µm balls on 250µm centers.

Solder Jet® deposition is non contact and can be directed at any angle in 3-D space to accommodate unique applications. A 45º rotation of the printhead was used to deposit these solder joints to a right angle interface between conductors and a VCSEL array.

Multiple depositions in a single location can be used to create 3-D solder structures, including the 240µm tall towers on 150µm centers shown below in a CSP concept prototype. A polymer has been dispensed, using ink-jet, between the towers to maintain geometry during reflow.

A Solder Jet® printhead as shown in below, can be mounted on MicroFab's jetlab® printing platforms and is available as a subsystem for integration into customer's platforms.

Direct-Write of Embedded Passives

Resistor Jet™ Technology based on demand-mode piezoelectric ink-jet printing technology, has demonstrated the ability to print embedded resistors with a range of values from 100-ohms/square to several k-ohms/square as part of a NIST/ATP sponsored program on embedded passives. For more details on this program, go to aept.ncms.org.

The data-driven nature of ink jet printing allows the formation of precise geometries at any location on the printed wiring board inner-layer.

The breadth of applications of this technology is only limited by the availability and environmental stability of the printing ink material. Several material companies are continuing the development of materials for use with the Resistor Jet™ processes.

Resistor Jet™ Technology can also be utilized as a complimentary process. If the choice for the embedded resistor is plated resistors, the Resistor Jet™ method has demonstrated the ability to “trim up”, or lower the resistive value, by selectively adding material to the plated deposit.

Extensions of Resistor Jet™Technology are being developed to print conductors, inductors, sensors, capacitors and optical elements.

Other Applications

MicroFab has successfully demonstrated dispensing a number of other materials used in electronics manufacturing. These include dielectrics, adhesives, organometallic inks for conductors, solder mask, and ferrite particles for inductors.