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POST ASSEMBLY CONTACT BUMP FABRICATION FOR FACILITATING ASSEMBLY OF MOSAIC THERMAL PRINTBARS

IP.com Disclosure Number: IPCOM000025560D
Original Publication Date: 1986-Apr-30
Included in the Prior Art Database: 2004-Apr-04
Document File: 4 page(s) / 149K

Publishing Venue

Xerox Disclosure Journal

Abstract

To improve the fabrication yield of large marking transducer arrays for electronic printing applications, such as thermal printers, it can be more economical to follow a mosaic assembly approach, where several marking transducer array modules are precisely aligned and mounted (butted) end-to-end. While page-width thermal printbars are presently being developed and manufactured, the mosaic approach may become even more advantageous as the transducer density rises beyond 300 per inch. Precision alignment and mounting requirements may be relaxed by defining the transducer position with a thermal contact bump applied after assembly.

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Page 1 of 4

XEROX DISCLOSURE JOURNAL

POST ASSEMBLY CONTACT BUMP FAB- RICATION FOR FACILITATING ASSEMBLY OF MOSAIC THERMAL PRINTBARS
Gary A. Kneezel

Proposed Classif rcation
U.S. Cl. 29/625

Int. CI. H05k 3/10

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Volume 11 Number 2 March/Aprll 1986 47

[This page contains 1 picture or other non-text object]

Page 2 of 4

POST ASSEMBLY CONTACT BUMP FABRICATION FOR FACILITATING

ASSEMBLY OF MOSAIC THERMAL PRINTBARS (Cont'd)

To improve the fabrication yield of large marking transducer arrays for electronic printing applications, such as thermal printers, it can be more economical to follow a mosaic assembly approach, where several marking transducer array modules are precisely aligned and mounted (butted) end-to-end. While page-width thermal printbars are presently being developed and manufactured, the mosaic approach may become even more advantageous as the transducer density rises beyond 300 per inch. Precision alignment and mounting requirements may be relaxed by defining the transducer position with a thermal contact bump applied after assembly.

Referring to Figure 1, the thermal. transducer modules 10 are assumed to be batch fabricated on a flat wafer-like substrate 12 which would then be diced. Because of the difficulty in dicing the devices such that the front edge 13 is at a precisely known distance and accurately parallel to the line of transducers 14,
alignment must generally be done in both x and y directions. Alignment in the z direction is accomplished by placing the modules on the same reference flat. Figure 1 shows module alignment in only the x and z direction, so that the linear arrays of transducers are not parallel with their front edges 13. Instead, the arrays are slightly skewed, so that confronting adjacent end transducers on separate modules are spaced different distances from front edge 13.

To overcome this problem In a sensor array readbar or image bar 16, it is known, as shown in Figure 2, to make the transducers 17 elongated in the y direction. The front edge 18 of all array modules 19 could then be referenced to the same banking wall edge 20. After mounting the modules end-to-end, the transducers 17 would be defined simultaneously by masking off all but a narrow slit 21, so that, for incoming light, the image bar 16 would behave like a full width array of well-defined transducers.

In the thermal printing technology field, it is known that the transfer marking resolution of elongated thermal resistive heater elements is srgnif icantly improved by the presence of a small. bump (a few microns high) at ea...