M A R A N M AY U A N FA N G

R A M N E E T S I N G H

HP Thermal Bubble Jet Printer

Outline

• History of Printer Technologies• HP Bubble Jet Printer• HP Print Head Fabrication• Print Head Packaging & Circuitry• Performance Analysis• Conclusions

History

• 1878 – Lord Rayleigh – droplet breakup• 1960 – Continuous ink-jet - stream

broken into droplets via pressure wave pattern

History (cont’d)• 1979 – Canon develops drop-on-demand

thermal bubble-jet• 1984 – HP produces first commercial

bubble-jet called ThinkJet

• HP’s print head is disposable – doesn’t sacrifice quality

• Better quality due to frequent replacement

• Allows for up to 4800x1200 dpi @ 24 ppm

• Allows the use of pigmented ink for increased precision and superior fade performance

HP’s Bubble-jet Advantage

Video clip on HP Cartridge

Print Head Functional Requirements

Store ink for each nozzleHeat ink drop via heater resistorRelease ink at desired quantity &

position

HP Print Head Fabrication

Reusable substrate: silicon or glass, with photoresist islands

Orifice plate: nickel, via electroforming

Photoresist island

Reusable substrate

Orifice plate

• Integrated fabrication process, facilitates critical alignment of:– Ink reservoir– Heater resistor– Orifice plate

HP Print Head Fabrication (cont’d)

First insulating barrier: prevent shorting of resistor/conductor with orifice plate

Heater resistors: narrow region of conductorR = Rs (L/A)

Heater resistors – plan view

C-shaped heater resistor

Lead-in conductor

Insulating barrier layer

Heater resistor

Lead-in conductor

HP Print Head Fabrication (cont’d) Second insulating

barrier: prevent corrosion of resistor/conductor by ink

Seed layer: sputtered metal, etched to C shape

Ink reservoir wall: nickel, via electroplating

Substrate removal: peeling to unplug orifices

Seed pad

Wall

hole

Second insulating layer

Insulating layer

HP Print Head Fabrication (cont’d)

Layer Suitable Material Deposition Process Thickness [um]

Substrate Oxidized Silicon/ Glass 200-300

Orifice Plate Nickel Electroforming 20-75

Insulating Layer 1Silicon Dioxide/Silicon Nitride/Silicon Oxynitride

PECVD/LPCVD

1-3

Resistor & Conductor

Polysilicon/Tantalum Silicide/Gold

Sputtering/PECVD/LPCVD

0.05-0.5

Insulating Layer 2 Silicon Nitride &Silicon Carbide

LPCVD 0.5-2

Seed Layer Nickel/Titanium/Chromium

Sputtering0.5-2

Barrier Nickel Electroplating 10-75

Table 1. HP Bubble Jet print head fabrication procedure summary [8]

HP Print Head Fabrication (cont’d)

Lead-in conductor

C-shaped heater resistor

C-shaped reservoir wall

Orifice (nozzle)

Hole

Ink reservoirWall

Second insulating barrier layerFirst Insulating barrier layer

Heater resistor

Lead-in conductor

Orifice plate

Seed pad

Print head structure – plan view: ink flow channels along A

MEMS fabricated print head structure prior to assembly with cartridge

Print Head Packaging & CircuitryPackaging

Electrical contact with lead-in conductor

Dome of C-shaped ink reservoir wall

Ink supply chamber

Ink supply chamber wall

Electrical lead for circuit interfacing

Lead-in conductor

Print head soldered to ink supply chamber wall Electrical contact bonded to exposed conductors

Print Head Packaging & Circuitry (cont’d)

Circuitry

Print Head Packaging & Circuitry (cont’d)

TIJ vs Piezoelectric dots

Piezoelectric vs TIJ vs Laser print on plain paper

Performance AnalysisPiezoelectric printers are susceptible to

nozzle-cloggingTIJ use pigmented ink and pressure

nozzle ejection

Epson PM750 1440 dpi, 65microns

HP 2000C 600 dpi, 45microns

Colour Printingdpi is not the best measure of performanceRapid ejection of small dots is the key to

quality printing (dps)HP’s TIJ has a higher throughputSmaller drop fluid chamber – more nozzles and

higher firing frequency

Piezoelectric versus TIJ drops-per-second comparison

Colour Printing (cont’d)

Conclusions

The Bubble jet print head is fabricated using MEMS technology

Fabrication processes include: PECVD, LPCVD, photolithography, etching and sputtering

Integrated design of the print head can increase reliability and reduce cost

References[1] “Progress and Trends in Ink-jet Printing Technology”, Journal of Imaging Science and

Technology, volume 42, Number 1, Janurary/Feburary 1998[2] Vince Cabill, “Introduction to Digital Printing Technology”:

http://www.techexchange.com/thelibrary/tchnlgy.pdf [March 7 2005][3] “HP Business Inkjet 2800 Printer Series, Technical Specifications”, Hewlett-Packard

Development Company [August 2005][4] “Piezoelectric Process”, PDS Consulting:

http://www.pdsconsulting.co.uk/Images/Process/Piezelectric%20Process.jpg [May 8, 2006].

[5] David B. Wallace, Donald J. Hayes and Christopher J. Fredrickson, "Ink-Jet Based Fluid Microdispensing for High Throughput Drug Discovery," March 2008, http://www.microfab.com/about/papers/chibook/chi_book.htm

[6] Inkjet Workshop, “Tutorials – Definitions,” March 2008, http://www.inkjetworkshop.com/definitions.html

[7] Stephen D. Senturia, Microsystem Design. New York: Springer, 2001.[8] Eldurkar V. Bhaskar and Marzio A. Leban, “Integrated Thermal Ink Jet Printhead and

Method of Manufacture” US Patent 4847630, July 11, 1989[9] C. S. Chan and Robert R. Hay, “Barrier Layer and Orifice Plate for Thermal Ink Jet

Printhead Assembly” US Patent 4694308, September 15, 1987[10] Richard A. Murray, “Printer Ink Cartridge with Drive Logic Integrated Circuit” US

Patent 5646660, July 8, 1997

Questions?