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High Resolution Electro-Erosion Printing

IP.com Disclosure Number: IPCOM000102457D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 5 page(s) / 233K

Publishing Venue

IBM

Related People

Cohen, MS: AUTHOR [+3]

Abstract

The structure of an integrated head for electro-erosion printing is very simple in principle (Fig. 1). An insulating chip is used as a substrate upon which fine metal conducting lines are delineated using modern photolithographic techniques. The lines come to the very edge of the chip so that contact is made with the direct-negative/direct plate (DNP) material (the ElectroNeg material) when the chip is held vertically. The lines are fanned out to wide pads at the other end of the chip so that contact can be made to the appropriate electronic drivers.

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High Resolution Electro-Erosion Printing

       The structure of an integrated head for electro-erosion
printing is very simple in principle (Fig. 1).  An insulating chip is
used as a substrate upon which fine metal conducting lines are
delineated using modern photolithographic techniques.  The lines come
to the very edge of the chip so that contact is made with the
direct-negative/direct plate (DNP) material (the ElectroNeg material)
when the chip is held vertically.  The lines are fanned out to wide
pads at the other end of the chip so that contact can be made to
the appropriate electronic drivers.

      A major potential problem encountered with any electro-erosion
head is fouling, i.e., the buildup of a hard cake of debris
originating in the erosion process; the building can continue until
it inhibits writing.  This debris is a combination of aluminum and
organic matter which is, at first, a harmless, powdery mass
concentrated around the electrodes, but which compacts with continued
writing into the harmful hard-cake form.  The fouling was so
pronounced for the earliest integrated heads that the hard-cake
buildup caused cessation of writing after only a few cm of sweep
length.

      From a study of the fouling of a conventional head it was
postulated that the compaction process is promoted by the high
temperatures attained by the electrodes and the insulating block
which contains them.  Since the earliest integrated heads were
fabricated on ceramic substrates, very high temperatures were
achieved, leading to early hard cake formation.  The geometrical
arrangement of such a head is considerably worse than that of a
conventional head in this regard, because the ceramic block in a
conventional head is raised from the DNP material by a distance of
several electrode diameters (Fig. 2); in the integrated head the
insulating substrate is also in contact with the DNP material (see
Fig. 1) so that debris compaction can easily take place.

      Two steps were taken to suppress fouling in the integrated
head:
1.   The head was arranged so that the electrodes faced the trailing
edge (Fig. 1), so that the debris tended to be left behind the chip.
2.   The interface between the chip and the DNP material (the
"footprint") was made as small as possible consistent with the
mechanical integrity of the head.
3.   The insulating chip was constructed of silicon, so that while
electrical insulation was maintained, high thermal conductivity was
achieved so that the temperature of the chip was as low as possible.
To insure low temperatures even further, the silicon chip was heat
sunk by bonding it to a copper block.

      It is believed that the third measure, the use of silicon as a
substrate, was the most important in suppressing fouling.  Various
metals, such as copper, nickel, or tungsten, could be used as
electrodes in the Integrated Head.  Tungsten has the immediate
advantage of possessing a good match to the therma...