US3784379A

US3784379A - Method of laminating one or more materials with a base structure for use in a high vacuum electron tube and method of masking the base preparatory to lamination

Info

Publication number: US3784379A
Application number: US00204158A
Authority: US
Inventors: R Orthuber
Original assignee: Deutsche ITT Industries GmbH
Current assignee: TDK Micronas GmbH; ITT Inc
Priority date: 1971-12-02
Filing date: 1971-12-02
Publication date: 1974-01-08
Anticipated expiration: 1991-01-08

Abstract

A method of making a structure for use in a black and white or color Kinescope or the like, the structure being called a multichannel array and including a perforated channel type electron multiplier with two perpendicular sets of insulated conductive strips extending over rows and columns of the multiplier holes. The strips have holes in registration with the multiplier holes. Conductive strips and glass insulating layers are deposited using a photoresist layer with or without a transparent photographic film. The photoresist is exposed to light through the multiplier holes.

Description

United States Patent 1 Orthuber METHOD OF LAMINATING ONE OR MORE MATERIALS WITH A BASE STRUCTURE FOR USE IN A HIGH VACUUM ELECTRON TUBE AND METHOD OF MASKING THE BASE PREPARATORY T0 LAMINATION [75] Inventor: Richard Kaspar Orthuber,

Sepulveda, Calif. [73] Assignee: International Telephone and Telegraph Corporation, New York, NY.

[22] Filed: Dec. 2, 1971 [21] Appl. No.: 204,158

[56] References Cited UNITED STATES PATENTS 3,541,254 1111970 Orthuber 178/73 [451 Jan. 8, 1974 3,412,456 1l/l968 Ebisawa 96/362 3,567,508 3/1971 Cox et al. 96/36.2 3,567,506 3/1971 Belardi 96/362 3,542,550 11/1970 Conrad et a] 96/362 Primary ExaminerNorman G. Torchin Assistant Examiner-Edward C. Kimlin Attorney-C. Cornell Remsen, Jr. et a1.

[5 7] ABSTRACT holes. Conductive strips and glass. insulating layers are deposited using a photoresist layer with or without a transparent photographic film. The photoresist is exposed to light through the multiplier holes.

7 Claims, 17 Drawing Figures 1 METHOD OF LAMINATING ONE OR MORE MATERIALS WITH A BASE STRUCTURE FOR USE IN A HIGH VACUUM ELECTRON TUBE AND METHOD OF MASKING THE BASE PREPARATORY TO LAMINATION BACKGROUND OF THE INVENTION This invention relates to the art of fabricating structures called multichannel arrays or the like, and more particularly, to a method of making perforate laminates.

The present invention may be employed for many purposes not disclosed herein, but has been found especially useful in the fabrication of a device called a multichannel array (MCA) disclosed in U. S. Pat. No. 3,541,254. This device has a multitude of very, very small andintricate component parts. It would thus normally be difficult to make within a resonable time and at reasonable cost.

SUMMARY OF THE INVENTION BRIEF DESCRIPTION OF THE DRAWINGS In the drawings which are to be regarded as merely illustrative;

FIG. 1 is a diagrammatic view of a television receiver disclosed in thesaid patent;

FIG. 2 is a perspective view of a structure shown internally of the evacuated envelope of a Kinescope in FIG. 1, the structure being called a multichannel array (MCA);

FIG. 3 is a broken away sectional view of the MCA taken on the line 3--3 shown in FIG..2;

FIG. 4 is a dielectric plate which may be employed with a channel type electron multiplier incorporated in the MCA of FIGS. 2 and 3;

FIG. 5 is a sectional view through the plate illustrating steps of depositing an electrode on opposite surfaces of the plate shown in FIG. 4;

FIG. 6 is a similar sectional view through the structure of FIG. 5 with a transparent photographic film thereon; I

FIG. 7 is a sectional view similar to FIG. 6 with a negative photoresist layer on the film which has been partially exposed to light; I FIG. 8 is a sectionalview similar to FIG. 7 with portions of the negative photoresist washed away, and the film area between remaining photoresist layer portions filled with frit;

FIG. 9 is a sectional view similar to FIG. 8, with the frit glazed and the film and negative photoresist decomposed in an oven;

FIG. 10 is a sectional view similar to FIG. 7 illustrating another'method of exposing a photoresist layer;

FIG. 11 is a sectional view illustrating a conductive metal strip evaporating step;

FIG. 12 is a sectional view of a partially constructed MCA having a layer of insulating glass and conductive strips bonded thereto in an oven;

FIG. 13 is a sectional view similar to FIG. 12 illustrating how a second glass layer is bonded to the laminate shown in FIG. 12;

FIG. 14 is a sectional view similar to FIG. 13 with hardened positive photoresist strips fixed on top of the assembly;

FIG. 15 is a sectional view of an assembly which may be identical to that shown in FIGS. 2 and 3; and

FIGS. 16 and 17 are sectional views through laminates illustrating an alternative method of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagrammatic view of a television receiver disclosed in the said patent. By this reference hereto, the entire disclosure of the said patent is hereby incorporated hereat as though fully set forth herein.

As shown in FIG. I, an intensity control circuit is provided at 10. A gating control circuit is provided at 11. Intensity control may be performed in several ways, as described in the said patent.

Circuit 10 may be identical to the intensity control 100 disclosed in the said patent, if desired. Circuit 11 may be identical to the scan control 101 disclosed in said patent, if desired.

In FIG. 1, a Kinescope is indicated at 12 having an evacuated envelope 13, a photocathode 14, a multichannel array 15 and an'aluminized phosphor screen 16. A lamp 17 is actuable to flood the photocathode 14 with light and thereby to supply primary electrons to the multichannel array (MCA) 15.

MCA 15, as will be explained, may include a channel type electron multiplier having a multitude of holes therethrough. Two sets of perpendicular spaced con-' ductive strips are employed to gate out electrons from only three holes at a time or from only one hole at a time. Thus, gating provides an entirely new concept in what was done in the prior art to scan an electron beam across a luminescent screen such as screen 16.

MCA 15 is again shown-in FIG. 2 including a dielectric plate 18 sandwiched in between input and

output electrodes

19 and 20, respectively.

Glass layers

21 and 22 insulate a plurality of horizontal conductive strips 23. Aplurality of spaced and insulated conductive strips 24 are fixed to the upper surface of glass layer 22, as shown in FIG. 2. I

As shown in FIG. 3, plate 18 has a plurality of holes 25 extending completely therethrough over much or all of the left hand face thereof, as viewed in FIG. 3. Holes 25 may be quite long, if desired, in comparison to their diameters. Holes 25 may be substantially defined by the cylindrical internal surfaces of plate 18 These cylindrical internal surfaces are made secondary emissive at least'by the time envelope 13 is sealed.

Electrode 20 has holes 26 which lie in registration with holes 25. Similarly, electrode 19 has holes 27 which lie in registration with holes 25. The same is true, respectively, of holes 28 in layer 2.1, holes 29 in strips 23, holes 30 in layer 22 and holes 31 in strips 24.

A plate 32 is shown in FIG. 4 which may be identical to plate 18.

Electrodes

33 and 34 may be evaporated onto plate 32, as shown in FIG. 5. Plate 32 may be made of any conventional ceramic employed in conventional channel type electron multipliers including, but not limited to, leaded glass.

Electrodes

33 and 34 may be made of a conductive metal.

Electrodes

33 and 34 thus correspond to

electrodes

19 and 20, respectively, shown in FIG. 3.

A transparent photographic film 35 is then adhered to electrode 33, as shown in FIG. 6.

A negative photoresist layer 36 is then deposited on top of film 35, as shown in FIG. 7. Film 35 is shown only as a line in FIG. 7 because film 35 is very thin in comparison to the thickness of layer 36. Further, throughout the drawings hereof, many dimensions have been exaggerated for clarity.

In FIG. 7, illumination is provided by a lamp 37 which shines light in a direction indicated by an arrow 38 through hole 39 in plate 32. As before,

electrodes

33 and 34 have holes which lie in registration with holes 39. Moreover, film 35 is transparent to the light provided by lamp 37. Portions 40 of negative photoresist layer 36 are then exposed to the light which emanates from a position on the side of plate 32 opposite the side on which film 35 is positioned. Portions 41 of layer 36 are left unexposed.

It is inherent in the nature of negative photoresist that only the exposed portions are hardened. Portions 41 are then washed away, and frit is deposited in the positions of portions 41, as indicated at 42 in FIG. 8.

The assembly of FIG. 8 is then fired in an oven or furnace 43, as shown in FIG. 9. After firing, film 35 and hardened negative photoresist portions 40 are decomposed and effectively removed from the assembly, the firing causing frit 42 to be bonded to electrode 33 at 44 in the position shown in FIG. 9. Layer 44 is then a substantially solid glass layer or glaze which corresponds to layer 21 in FIG. 3.

In steps succeeding the step indicated in FIG. 9, another transparent photographic film 45 is adhered to the upper surface of layer 44, as viewed in FIG. 9. A layer of positive photoresist 46 is then laid on top of film 45. The positive photoresist layer 46 then has portions 47 that areexposed to light and portions 48 which are not exposed to light. Portions of portions 47 are exposed to light directly, which light emanates from a lamp 49 and enters plate holes 39, as in FIG. 7. However, in accordance with FIG. 10, portions 47 have a cross section larger than that of holes 39. Moreover, portions 47 have a width and thickness as shown which may be substantially uniform throughout their entire lengths. Portions 47 may also have lengths substantially longer than their widths. This is accomplished by a cylinder light reflecting lens raster 50 which has a, more or less, symmetrical axis. Cylinder lens raster 50 may be first held in a position such that its axis lies in a plane of the paper of the drawing of FIG. 10. Cylinder lens raster 50 is then moved always in a direction perpendicular to the paper.

As is inherent in positive photoresist, portions 48 harden, and portions 47 stay in a condition so that they may be washed away. Portions 47 are then, in fact, washed away leaving hardened portions 48, shown in FIG. 11.

In FIG. 11, a conductive metal layer 51 is then evaporated onto film 45 as indicated at 51. Portions of metal layer 51 may build up upon photoresist portions 48 at 52.

In FIG. 11, film 45 is again shown as a single line. The height of photoresist portions 48 has been exaggerated to illustrate the fact that layer 51 has a thickness generally very small in comparison to the height of photoresist portions 48. I

The assembly of FIG. 11 is then fired in a furnace 53, as shown in FIG. 12. Again, film 45 decomposes as do photoresist portions 48. This leaves the structure, as shown in FIG. 12, with insulated and spaced conductive strips 54 bonded to glass layer 44. Moreover, each strip 54 is insulated from all of the other strips 54, and each strip 54 has a plurality of holes therein which lie in registration with plate holes 39. Conductive buildups at 52 are thus dropped off during firing as portions 48 decompose, as shown in FIG. 11. The same is true of the portions of layer 51 which lie in registration with plate holes 39 after film 45 decomposes. Strips 54 thus correspond to strips 23, shown in FIGS. 2 and 3. A glass layer 55, shown in FIG. 13, is bonded to glass layer 44 and conductive strips 54 by performing the same steps by which glass layer 44 was bonded to electrode 33.

Hardened positive photoresist strips 56 are formed on the upper surface of glass layer 55 in FIG. 14 in the same manner that portions 48 are formed in FIG. 11.

By the use of strips 56, conductive strips 57 are bonded to glass layer 55 in the same manner that strips 54 are bonded to glass layer 44. Thus, glass layer 55 corresponds to glass layer 22, shown in FIG. 3, and strips 57 correspond to strips 24, shown in FIG. 3.

The section of FIG. 15 does not look like the section of FIG. 3 because these two sections have been taken at angles with respect to each other to show clearly the construction of the finished product. It will be noted that a section taken along the line A-A in FIG. 15 will be identical to that shown in FIG. 3, and that a section taken along the line B-B in FIG. 3 will be identical to that shown in FIG. 15.

If desired, the steps illustrated in FIGS. l0, l1, l4 and 15 may be performed without the use of film 45, as shown in FIGS. 16 and 17, respectively. For example, in FIG. 16,

parts

32', 33', 34, 44, 47 and 48' respectively correspond to

parts

32, 33, 34, 44, 47 and 48 in FIG. 10.

In FIG. 17,

parts

32, 33', 34, 44, 48, 51 and 52' correspond respectively to

parts

32, 33, 34, 44, 48, 51 and 52 shown in FIG. 11. However, layer 51 has holes 58 therein. In FIG. 11, layer 51 does not have holes therein except where the upper surface of layer 44 is masked by photoresist portions 48.

The assembly of FIG. 17 is then fired as in FIG. 12. The result is then the same as that shown in FIG. 12.

In FIG. 14, the exposed portion of the photoresist, not shown, may be exposed by use of a cylinder lens raster 50' which is moved in the direction indicated by arrow 50".

Alternatively, cylinder lens raster 50, shown in FIG. 14, may be of a construction the same as or similar to that shown in FIG. 10. Cylinder lens raster 50' is, more or less, a group of bodies similar to or the same as cylinder lens raster 50.

If desired, film 35 and film 45 both may be made of entirely conventional transparent photographic film.

Whenever either the negative photoresist or the posi- I tive photoresist is exposed to light as in, for example, FIGS. 7, 10, 14 and 16,

lamps

37, 49, 50" and 50"" may be positioned a substantial distance away from the structure illuminated. Moreover, a conventional parabolic reflector may be provided for each lamp, if desired, for collimation.

A cylinder lens raster 50" identical to cylinder lens raster 50 in FIG. is also shown in FIG. 16.

In FIG. 2, it will be noted that, as stated previously, holes extend all the way through MCA. 15. The holes may be described as being in columns and rows. For example, all of the holes in one strip 24 may be described as a column of holes. All the holes in one strip 23 may be described as a row of holes.

In FIG. 1 1, photoresist strips 48 are thus located midway between two immediately adjacent rows of holes in the MCA. The same is true of photoresist strips 48, shown in FIG. 17. Strips 56, shown in FIG. 14, are located midway between two immediately adjacent columns of holes.

As stated previously, the drawings are not to scale. Thus, if the source of light for photoresist exposure provides collimated light, is spaced a substantial distance from the photoresist, and provides a light beam which, in cross section, is at least as large as the structure being illuminated or can be moved thereover, light can enter each MCA' hole. However, due to the fact that the lengths of the MCA holes may be much greater than the diameters, little light divergence at the far end of a hole will occur. Accurate formations of holes in the laminates is thus possible.

In accordance with the foregoing, from FIGS. 16 and 17, it will be appreciated that all the conductive strips may beformed in their proper shapes, sizes and locations without the use of a film. However, the use of a film or an equivalent thereof is required to support, for example, the exposed portions 40 of the negative photoresist layer 36 after photoresist layer portions41 have been washed away. Note that the hardened photoresist layer portions 40 overlie the plate holes 39 in FIG. 7 and are not easily supported except by a film or its equivalent.

The methods of the present invention are by no means limited to making an MCA of any specific relative or absolute dimensions. However, some typical dimensions are given in the following.

In the first place, if desired, strips 23 may be three holes wide instead of one hole wide. However, for strips one hole wide, the space between two immediately adjacent strips 24 may be 1.6 mils. The spacing of strips 24 and and strips 23 may be uniform. The spacing of strips 23 may be identical to the spacing of strips 24, if desired. Each strip 24 may be 6.0 mils wide. Each strip 23 may have the same width.

Each strip may be centrally located over its corre' sponding column or row of holes. Each hole may have a diameter of 5.0 mils.

The spacing between the center of the holes in one strip 23 to the center of the holes, in a strip immediately adjacent thereto may be 7.6 mils. The spacing between the center of the holes in one strip 24 to the center of the holes in another strip 24 immediately adjacent thereto may also be 7.6 mils.

I An outstanding feature of the MCA 15, shown in FIG. 2, is that strips 23 and 24 act in a manner similar to the control grid of a triode and require only very small gating voltages.

In FIG. 1, photocathode 14 is maintained at a potential of 0 volts, voltages of O and -3 volts for all of the strips 23 and for all of the strips 24 are entirely adequate.

Note will be taken that MCA 15, shown in FIG. 2, if fabricated in accordance with the methods of the pres ent invention, may be used in any of the several embodiments disclosed in the said patent.

By itself, photoresist is well known in the art. However, to make it clear again how the photoresist layers are employed to mask certain surface portions of the laminate under construction, negative photoresist hardens when exposed to light. The unexposed portions of negative photoresist may thus be washed away. Conversely, the unexposed portions of positive photoresist harden, and the exposed portions of positive photoresist may be washed away. I The photoresist layers disclosed herein preferably have a thickness of about 1.0 mil or greater. This compares with a thickness of dielectric plate 32 in FIG. 15 of, for example, 50 mils.

If desired,

films

35 and 45 may be identical. In such a case, each may, if desired, have a thickness of from about 1.0 micron to about 5.0 microns. The same is true of

strips

23 and 24, and

electrodes

19 and 20.

Strips 54 have a thickness much smaller than that shown in FIG. 13. Hence, the use of a film over the top of strips 54 informing glass layer 55 thereon does not pose any problem to bonding glass layer 55 to strips 54 or to glass layer 44. Glass layer 55 is at least semifluid during firing; and during firing, the film is decomposed.

This means that the frit can flow down between conductive strips 54 to bond to glass layer 44. Glass layer 55 will easily bond to conductive strips 54 in any event.

What is claimed is:

l. The method of fabricating a laminated electron tube structure, said method comprising the steps of: forminga base plate having approximately flat opposite side surfaces and having a plurality of holes extending completely therethrough in a directionapproximately normal to said base surfaces; fixing one side of a transparent film to the surface of one side of said base to cover said surface and holes; forming a photoresist layer on the other film side over said surface and holes; directing light from a position on the other side of said base through said base holesto expose the areas of said photoresist layer over said holes while the other areas of said photoresist layer remain unexposed; washing away the unexposed areas of said photoresist layer; and

forming an added dielectric layer on said film over said areas where said photoresist layer was washed away, said exposed layer areas serving to mask a corresponding portion of said other film side; and heating said base, said film and said exposed photoresist layer areas to a temperature causing said film and said exposed photoresist layer areas to decompose leaving said added dielectric layer bonded to said base surface over the areas substantially congruent with said unexposed areasof said photoresist layer.

2. The method of claim 1, wherein saidphotoresist layer includes a negative photoresist, said added layer being frit, said heating step being performed to raise the temperature of said frit sufficiently high to form a glaze and remove said exposed areas and film.

3. The invention as defined in claim 2, wherein a further transparent film layer is fixed to said one side of said base over said glazed frit and holes and a positive photoresist layer is formed on said further transparent layer, said positive photoresist layer being exposed to light in an increased cross sectional area over and extending around and beyond said holes approximately normal to the axes of said holes, said increased area being produced by directing light from said other side of said base through said holes and layers and positioning light reflecting lens means over said positive photoresist layer.

4. The invention as defined in claim 3, including washing away said increased area photoresist layer around said holes and depositing an added conductive metal layer onto said further transparent film in said increased area and over the remaining photoresist portion.

5. The invention as defined in claim 4, wherein said added layer has a thickness substantially less than that of said remaining photoresist layer portion.

6. The invention as defined in claim 5, including heating said base, glaze, further transparent film, positive photoresist and metal layers to decompose said film and photoresist and cause said metal layer on said film over said holes and remaining photoresist to break off from said base and to leave said holes open and said metal bonded to said base in positions around said holes and spaced apart from said metal around adjacent holes.

7. The invention as defined in claim 6, including forming a further dielectric layer over said metal layer and between said holes, and forming conductive electrode strips over said further dielectric layer.

l l =l

Claims

2. The method of claim 1, wherein said photoresist layer includes a negative photoresist, said added layer being frit, said heating step being performed to raise the temperature of said frit sufficiently high to form a glaze and remove said exposed areas and film.
3. The invention as defined in claim 2, wherein a further transparent film layer is fixed to said one side of said base over said glazed frit and holes and a positive photoresist layer is formed on said further transparent layer, said positive photoresist layer being exposed to light in an increased cross sectional area over and extending around and beyond said holes approximately normal to the axes of said holes, said increased area being produced by directing light from said other side of said base through said holes and layers and positioning light reflecting lens means over said positive photoresist layer.
4. The invention as defined in claim 3, including washing away said increased area photoresist layer around said holes and depositing an added conductive metal layer onto said further transparent film in said increased area and over the remaining photoresist portion.
5. The invention as defined in claim 4, wherein said added layer has a thickness substantially less than that of said remaining photoresist layer portion.
6. The invention as defined in claim 5, including heating said base, glaze, further transparent film, positive photoresist and metal layers to decompose said film and photoresist and cause said metal layer on said film over said holes and remaining photoresist to break off from said base and to leave said holes open and said metal bonded to said base in positions around said holes and spaced apart from said metal around adjacent holes.
7. The invention as defined in claim 6, including forming a further dielectric layer over said metal layer and between said holes, and forming conductive electrode strips over said further dielectric layer.