US3609033A - Mask for etching enlargement - Google Patents

Mask for etching enlargement Download PDF

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Publication number
US3609033A
US3609033A US850450A US3609033DA US3609033A US 3609033 A US3609033 A US 3609033A US 850450 A US850450 A US 850450A US 3609033D A US3609033D A US 3609033DA US 3609033 A US3609033 A US 3609033A
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Prior art keywords
mask
pattern
diameter
etchant
area
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Expired - Lifetime
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US850450A
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English (en)
Inventor
John J Frantzen
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Buckbee Mears Co
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Buckbee Mears Co
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Publication date
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/02—Manufacture of electrodes or electrode systems
    • H01J9/14—Manufacture of electrodes or electrode systems of non-emitting electrodes
    • H01J9/142—Manufacture of electrodes or electrode systems of non-emitting electrodes of shadow-masks for colour television tubes

Definitions

  • ABSTRACT A mask has a metallic material, preferably coldrolled steel, covered by an etchant-resist layer on both sides.
  • MASK FOR Q F ENLARGEMENT On one side the layer has a circular area of diameter X, void of 4 Claims 7 Dram"! etchant resist, and on the second side the layer has a circular [52] US. Cl 355/26, area of diameter X and an annular area of outer diameter X 355/77, 355/ 125 both void of etchant resist. The three areas are coaxially [5 1] Int. Cl 60;"; 21132 aligned.
  • This invention relates generally to making shadow masks for colored television tubes and, more specifically, for photopn'nting unusual patterns in register that are suitable for etching enlargement in a two-step etching process.
  • the shadow mask or aperture mask is located between the electron guns at therear of the tube and the phosphor-coated faceplate at the front'or viewing face of the tube. Electron beams pass through the openings or apertures inthe shadow mask and impinge upon a suitable color producing phosphorus dot on the faceplate. Behind each of the openings of the shadow masks are three phosphorus dots, a triad, one dot for each of the three primary colors.
  • theshadow mask is used as a mask or master for forming the phosphorus dots on the faceplate of the television tube. This is usually done using photographic techniques which are well known in the industry today.
  • the phosphor dots In order to produce the maximum possible brilliance at the face of the tube when the phosphor is struck by the electron beam but at the same time to focus the beam on the proper triad, it is necessary to have the phosphor dots smaller in diameter than the diameter of the apertures of the shadow inask. To facilitatethe screening of the phosphorus dots with the existing apertures of the shadow mask, it requires a temporary stepping down or reduction in the diameter of the apertures by partially filling the apertures with a second material tha'tis different from the mask material. The, after using the mask for forming the pattern for the phosphorus dots on the faceplate of the tube, the filling material can be removed to enlarge the holes in the aperture mask so thatthe maximum brilliance can be obtained in the television tube.
  • Another method of obtaining smaller holes in the shadow mask for the deposition of the phosphorus dots is to etch a set ar first circular opening in the shadow mask which have a diameter suitable for use as a pattern for forming the phosphorus dots on thefaceplate of the television tube. Then after layingthe phosphorus dot pattern on the faceplate of the television tube the holes are subjected to etching enlargement by controllably spraying etchant on the mask.
  • the present invention comprises the method of printing and compensation for forming a suitable pattern in register in photo resist for producing the etched configuration of a set of "circular openings with a corresponding set of undercut annular areas located around the circular openings.
  • a set of larger diameter annular areas which are coaxially located with respect to the first set of circula'r'openings are etched partially through the *mask.
  • the annular area'which was etchedpartially through the first etching step is etched completely through
  • the present'invention comprises a process where the holes in a shadow mask are first etched to produce an opening for laying a phosphorus dot pattern and then etched to remove an annular ring thus leaving the opening enlarged to the set of pinholes and onto a second photosensitive plate and then developing the negative formed on the second photosensitive plate.
  • the negative master plates are placed in optical registration and put into a suitable printing apparatus to print the etching pattern in photoresist on opposite-sides of the mask.
  • the mask is immersed in an etchant until a first set of central apertures are etched out.
  • FIG. 1 shows material used for making the negative pattern on a plate glass
  • FIG. 2 shows the frontside patterned image on a suitable glass plate
  • FIG. 3 shows the camera setup and the pinhole negative for use with the image that is projected on one side of a master pattern used for making a shadow mask
  • FIG. 4 shows the backside patterned image whichis formed on the opposite side of the shadow mask
  • FIG. 5 shows a cross-sectional oblique view of the etchantresist pattern located on opposite sides of the material
  • FIG. 6 shows the cross-sectional appearance of the mask after etching partially through the mask
  • FIG. 7 shows the cross-sectional appearance of an aperture as the surrounding annulus is etched free from the mask.
  • FIG. 1 shows a portion of a suitable opaquematerial for use in making an enlarged pattern for use in the photoprinting process.
  • An example of a suitable opaque material is an opaque material that comes in a roll and is marketed under'the trade name Studnite.
  • the operator cuts thepattern at approximately times scale to minimize and reduce errors in forming the pattern. After cutting the;pattem outline in the opaque material, the areas 1.1, 12, and 13 (H6. -l,-).are
  • the pattern also includes guidelines 11 located horizontally and vertically to enable the operator to properly align'the pattern with respect to the camera.
  • the material is contacted'to a first glass plate and then recontacted to a second glass plate 16 (FIG. 2) to put the pattern in negative contrast.
  • the negathe contrast patterns are identified by 110, 12a, and 13a,
  • tern plate 16 has to be aligned prior to exposing the negatives.
  • the lineup pattern is also a glass plate that has a set of mutually perpendicular lines located in the center of the glass plate.
  • the operator fastens pattern plate 16 to prevent movement during the subsequent steps and removes the lineup pattern plate from the back of the camera.
  • the lights are turned off and pinhold board 9 is placed into the proper position in the back of the camera (FIG. 3).
  • the operator places a photosensitive plate 8 behind the pinho ld board. Photosensitive plate 8 is positioned so that it lies in a plane parallel to the pinhole board. As the lens has been removed from the camera 10 an image can be projected from the copyboard through each of the pinholes and onto photosensitive plate 8 when light 18 is turned on.
  • Turning light 18 on produces a set of images on photosensitive plate 8 which are identical in appearance to the copyboard image or pattern plate 16, because they all have been formed from the same copyboard image on pattern plate 16.
  • the photosensitive plates can be developed.
  • These negatives containing a multiple frontside and backside patterns can be used as a master pattern to mask off the photoresist material on both sides of the mask.
  • the negative master patterns are printed in misalignment, the two-step etching process cannot be satisfactorily accomplished. For example, if there is misalignment so that the circular backside pattern is not coaxial with the annular frontside pattern, it will produce regions where the etchant cannot etch completely through the mask without enlarging the central opening beyond the preferred size.
  • such masks are unsuitable for use in colored television industry as the electron beams cannot be focused properly through the apertures unless the apertures are properly sized.
  • FIG. 5 shows a material 30 having a layer of patterned etchant resist 31 on one side and layers of patterned etchant resist 32 and 33 located on the opposite side.
  • Resist layer 31 has a central area 34 which is void of etchant resist and similarly located on the opposite side are two areas 35 and 36 which are also void of etchant resist.
  • Reference character X designates the diameter of circular area 34 and reference characters X and X designate the respective outermost dimension of area 25 and area 36.
  • Reference character L designates the width of area 25 while reference character T designates the thickness of material 30.
  • FIG. 6 shows a greatly enlarged aperture '38 having a central opening of diameter a in cross section after the first etching step. Note, the outline of the etched material 30 with the relatively bowl-shaped sides 20 and the smaller angular areas 21 and 22. Also, note how the etchant has undercut the corners of the resist.
  • the width of the annular area L is slightly less than one-fourth the thickness T of the shadow mask. Having the dimension L too large causes the material in area 35 to etch completely through to sidewalls 20 before the desired central opening 38 is obtained. Having the width L too small prevents the etchant from etching to the proper depth so that ringlike member 40 (FIG. 7) can be removed in a second etching step while still maintaining the integrity of the final dimension b.
  • a second central area having a dimension designated by X This diameter is substantially equal to the diameter of the central opening a through the mask (see FIG. 6).
  • the etchant undercuts the resist and generally angles inward to produce the desired central opening of diameter 0 shown in FIG. 6.
  • the operator In order to etch a typical cold roll steel shadow mask, the operator lowers the shadow mask containing the photoresist pattern, which is shown in FIG. 5, into a solution of ferric chloride etchant.
  • the shadow mask remains in the etchant until the etchant etches away the central circular areas thus leaving an opening of diameter a. This can be detennined by visual inspection and by monitoring the time the mask is in the etchant.
  • the larger diameter open area 35 etches faster into the shadow mask than the corresponding smaller areas 35 and 36 which are located on the opposite side of the mask.
  • the mask is removed from the etchant and washed to prevent any etchant clinging to the mask from enlarging or further undercutting the mask.
  • a typical mask areas 35 and 36 etch approximately onethird of the thickness of the mask while on the opposite side of the mask the center of the larger area 34 etches to a depth of approximately two-thirds the thickness of the mask in the same amount of time.
  • the mask After the mask has been used to lay the phosphorus dot pattern, the mask is immersed in etchant until the area of thickness c has been etched through (FIG. 7). This causes ringlike member 40 to drop out leaving an operator having an enlarged final diameter b. The resist can now be removed and the mask placed in the television tube.
  • An aperture mask suitable for etching enlarging comprising: a metallic material having a thickness T; a first layer of etchant resist located one side of said material and a second layer of etchant resist located on the opposite side of said material; said first layer of etchant resist having a first circular area of diameter X being substantially void of etchant resist; said second layer of etchant resist having a second circular area having a diameter X being substantially void of etchant resist, said second layer of etchant resist having an annular area substantially void of etchant resist, said annular area having an outer diameter X said outer diameter X being substantially equal to the diameter X, of said first circular area.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Preparing Plates And Mask In Photomechanical Process (AREA)
  • ing And Chemical Polishing (AREA)
  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
  • Manufacture Or Reproduction Of Printing Formes (AREA)
US850450A 1969-08-15 1969-08-15 Mask for etching enlargement Expired - Lifetime US3609033A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US85045069A 1969-08-15 1969-08-15

Publications (1)

Publication Number Publication Date
US3609033A true US3609033A (en) 1971-09-28

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US850450A Expired - Lifetime US3609033A (en) 1969-08-15 1969-08-15 Mask for etching enlargement

Country Status (7)

Country Link
US (1) US3609033A (enrdf_load_stackoverflow)
JP (1) JPS501870B1 (enrdf_load_stackoverflow)
BE (1) BE744171A (enrdf_load_stackoverflow)
DE (1) DE2005151A1 (enrdf_load_stackoverflow)
FR (1) FR2057648A5 (enrdf_load_stackoverflow)
GB (1) GB1252713A (enrdf_load_stackoverflow)
NL (1) NL7009574A (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3784301A (en) * 1970-09-03 1974-01-08 Xerox Corp Electrophotographic border apparatus
US3861798A (en) * 1972-05-22 1975-01-21 Hitachi Ltd Mask for aligning patterns
US3909311A (en) * 1974-08-05 1975-09-30 Hitachi Ltd Shadow mask for use in color picture tube and method for fabricating same
US3929532A (en) * 1974-07-17 1975-12-30 Rca Corp Method for etching apertured work piece

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5947946U (ja) * 1982-09-21 1984-03-30 大同特殊鋼株式会社 多段ロ−タリスイツチ
US5348825A (en) * 1991-07-02 1994-09-20 Dai Nippon Printing Co., Ltd. Method for manufacturing shadow mask and shadow mask manufactured by said method
EP0641009B1 (en) * 1993-08-25 2000-01-05 Kabushiki Kaisha Toshiba Color cathode ray tube and method of manufacturing the same

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3784301A (en) * 1970-09-03 1974-01-08 Xerox Corp Electrophotographic border apparatus
US3861798A (en) * 1972-05-22 1975-01-21 Hitachi Ltd Mask for aligning patterns
US3929532A (en) * 1974-07-17 1975-12-30 Rca Corp Method for etching apertured work piece
US3909311A (en) * 1974-08-05 1975-09-30 Hitachi Ltd Shadow mask for use in color picture tube and method for fabricating same

Also Published As

Publication number Publication date
JPS501870B1 (enrdf_load_stackoverflow) 1975-01-22
BE744171A (fr) 1970-06-15
DE2005151A1 (de) 1971-02-25
GB1252713A (enrdf_load_stackoverflow) 1971-11-10
NL7009574A (enrdf_load_stackoverflow) 1971-02-17
FR2057648A5 (enrdf_load_stackoverflow) 1971-05-21

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JPS5916245A (ja) カラ−映像管の発光スクリ−ンの製造方法
JPS5851379B2 (ja) シヤドウマスクの製造法