Fabrication of Passive Elements using Ink-Jet Technology
by
Virang G Shah and Donald J Hayes
MicroFab Technologies, Inc.
1104 Summit Ave., Suite 110写作英文
元旦节怎么画Plano, TX 75074
Phone: 972.578.8076/Fax: 972.423.2438
,
Abstract
A novel process has been developed to print passive elements like resistors, capacitors and inductors using demand mode ink-jet technology. The process involves printing intrinsically conductive polymer, thermotting resin system loaded with conductive particles, ferrite-powders in thermotting resin mat
rix, or liquid metals using drop-on-demand printheads and a precision printing platform. The same printing technique can also be ud to enhance the yield of current embedded resistor process by trimming resistor down (reduce the resistance) using intrinsically conductive polymer. Introduction
MicroJet technology is an emerging technology developed to meet the needs of next generation electronic and opto-electronic packaging solutions in a data-driven manner. It is bad on piezoelectric demand-mode ink jet printing technology that is capable of generating and placing droplets of polymers, solder, organometallic and metal nanoparticle solutions, 25-125µm in diameter, at rates up to 4,000 per cond. As performance, real estate and overall system costs become critical in manufacture of printed circuit boards, ink jet printing is becoming an increasingly attractive material deposition method. Ink jet bad deposition is a low cost (no tooling required), noncontact, flexible & data driven (no masks or screens are required since the print pattern is created directly from CAD information and stored digitally), and environmentally friendly (it is an additive process with no chemical waste).
Ink Jet Technology
Two broad categories of ink jet printing technologies that are ud in manufacturing are demand mo
de and, continuous, charge and deflect. In demand mode ink jet systems, a volumetric change in the fluid is induced either by the displacement of piezoelectric material that is coupled directly or indirectly to the fluid,1 or by the formation of a vapor bubble in the ink, caud by the heating a resistive element.2 The volumetric change caus pressure/velocity transients and the are directed so as to produce a drop that issues from an orifice.3,4 A drop is created only when it is desired in demand mode printing systems and they generate drops that are approximately equal to the orifice diameter of the droplet generator. Figure 1 shows a single channel MicroJet device, fabricated by MicroFab, generating 50µm diameter drops of ethylene glycol at 2,000 per cond.
Figure 1 Demand mode ink-jet glass device generating 50µm diameter drops at 2kHz.
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Demand mode Ink Jet Device
Many device configurations for drop-on-demand (DOD) dispensing have been demonstrated over the past two decades. One of the earliest configurations developed is also one that can be adapted to dispen a wide range of materials. In this configuration, an annular piezoelectric transducer is attached to a glass tube with an integrated orifice, as illustrated in Figure 2. Since glass is the only wetted material, this configuration can be ud to dispen practically any material with acceptable fluid properties (<20 cP Newtonian viscosity).
Figure 3 and Figure 4 show this type of jetting device in a metal housing with fluid fittings. The device in Figure 3 is designed for operation up to 240o C, through the lection of appropriate piezoelectric and adhesive materials. It has operated for veral hours at 320o C. The devices in Figure 4 are designed for
operation below 100o C.
Figure 2 Single channel drop-on-demand dispensing device
configuration
The types of devices have been ud to dispen materials as diver as aqueous dispersions and solutions, molten solder, polymers, organometallic and metal nanoparticle solutions. They have
been ud at operating temperature ranging from
ambient to 340o C. Multiple devices of the type
described above can be mounted into a mechanical
asmbly to form an array. This type of an array of devices may be ud to increa throughput or to dispen multiple fluids, as shown in Figure 5.
Figure 3. Single channel drop-on-demand dispensing device;
drop-on-demand, dispensing
devices; T<100o C.
Figure 4 Single channel drop-on-demand dispensing device;
T<240o C.
Resistor Printing and Trimming
Figure 5 Ink-jet dispenr array
consisting of single channel devices mounted in a fixture. Ink jet printing of embedded resistors has been successfully demonstrated using both filled polymer and conductive polyimide ink as part of an ongoing NIST/ATP project. Figure 7 below shows one of the 4-up 18”x12” embedded resistor test vehicle panel printed using proprietary polyimide ink. Resistors
ranging from 100Ω to veral M Ω/square have been created using materials with low resistivity. Printed resistors ranged in size from 125µm to veral mm long.
A DOD ink jet printing process has developed whereby Ni/P plated resistors are trimmed down by printing conductive polymer onto plated resistors and, subquently curing the
Figure 6 Ink jet printed embedded
resistor using conductive polymer ; 100 ohm/sq.
Figure 7
A portion of inner layer of a multi-layer PWB
resistor panel trimmed using DOD ink jet technology
.
printed polymer at <200o C. Figure 7 above shows a ction of PWB inner layer panel trimmed down using conductive polymer. Table 1 shows results of trimming Ni/P plated resistors by printing conductive polymer. Notice an average 32% reduction in the resistance for different size
resistors.
Table 1 Ni/P plated resistors trimmed an average 32% (N=8 for each size) using intrinsically conductive polymer BEFORE TRIM AFTER TRIM
Resistor Resistance
Ohm/sq Resistance Ohm/sq Change mils Ohm Ohm % 320X90 24.0 45.2 17.2 32.4 -28.3 160X90 46.8 44.0 32.7 30.8 -30.1 80X90 98.1 46.2 65.1 30.6 -33.6 40X90 207.3 48.8 133.6 31.4 -35.6 20X90 534.0
62.8 359.0
42.2 -32.8
Emulator Trimming As part of the continuing effort to trim resistors, a 15-up emulator panel size 18”x24” was
trimmed using conductive polymer.
Results of trimming are prented in Table 2 below. Figure 8 shows a portion of a Ni/P plated OEM emulator trimmed by ink-jet printing conductive polymer.
追风透骨胶囊Table 2 Embedded Ni/P plated resistors trimmed (N=6)
山西省司法厅
Figure 8 A portion of an OEM
emulator resistor panel trimmed down by ink jet printing
Capacitors and Inductors
By creating local 3-D structures, capacitors and inductors can be formed (not necessarily planar) using ink jet printing techniques. One of the methods of creating the types of structures is shown schematically in Figure 9 and Figure 10. For a capacitor, the bottom electrode, dielectric, and top electrode layers are laid down successively, and may be repeated to form multilayer capacitors. Both the area and the thickness of the dielectric could be varied to achieve a range of capacitance values.
For an inductor, a center electrode, ferrite layer, and conductor coil are printed. The inductance could
be varied by changing the number of turns of the printed coil. The challenge is in the materials required to make capacitors and inductors of practical value. Both organometallic and metal nanoparticle (e.g., silver, gold or copper) solution have been jetted but postprocessing temperatures are usually high. Finally, most high-capacitance (e.g., Ba 1-x Ca x Ti 1-y Zr y O 3) and high-inductance materials (e.g., Ni-Zn or Mg-Zn-ferrite powder) are ceramics that are sintered at high temperature.
Despite the difficulties, progress has been made in development of suitable materials and ink jet printing methods in last few years for ink jet printing of capacitors and inductors.
Figure 9 Steps for Figure 10 Steps for direct-write capacitor fabrication.
direct-write of inductors.
Figure 11 shows 150µm ferrite spots and, Figure 12 illustrates 250µm silver nanoparticle lines ink-jet printed onto a ferrite nanoparticle layer, which was also ink-jet printed.
Figure 11150µm spots of ferrite particles
Figure 12 250µm Silver line printed on ferrite; both using DOD ink jet device
Ink jet printed.
Figure 13 shows dielectric material博士申请条件
printed onto head flexture circuit.
Figure 14 shows a test vehicle with pads
printed with eutectic solder. Ink-jet
printing of solder balls as small as 25µm
on 35µm pitch has been demonstrated as
shown in Figure 15.
武藤美幸Figure 13A portion of head flexture circuit with
UV-curing dielectric printed along 50µm wide
gold leads.
Figure 14 IC test vehicle with 1440 pads,
bumped with Sn63/Pb37 solder using Microjet
technology. Ball size is 70µm.
Figure 1525µm diameter bumps of solder on 35µm
centers and 25µm towers printed on 50µm centers
Acknowledgement
This rearch was funded in part by NCMS/Advanced Embedded Passives Technology (AEPT) Consortium under support of the U.S. Department of Commerce, National Institute of Standards and Technology, Advanced Technology Program, Cooperative Agreement Number 70NANB8H4025 and, by DARPA. Details are at /.
乐趣的英语References
[1] D.B. Wallace, “A Method of Characteristics Model of a Drop-on-Demand Ink-Jet
Device Using an Integral Method Drop Formation Model,” ASME publication 89-WA/FE-4, December 1989.
[2] J.S. Aden J.H Bohorquez, D.M. Collins, M.D. Crook, A. Garcia, and U.E. Hess,
“The Third Generation HP Thermal Ink Jet Printhead,” Hewlett-Packard Journal, Vol.45, No. 1, Feb. 1994.
[3] D.B. Bogy and F.E. Talke, “Experimental and Theoretical Study of Wave
Propagation Phenomena in Drop-on-Demand Ink Jet Devices,” IBM Journ. Res.
Develop., Vol. 29, pp.314-321, 1984.
[4] J.F. Dijksman,“Hydrodynamics of Small Tubular Pumps,” Journ. Fluid Mech.,
Vol. 139, pp. 173-191, 1984.
