US3645232A

US3645232A - Apparatus for simultaneously applying a plurality of coatings to a substrate

Info

Publication number: US3645232A
Application number: US18277A
Authority: US
Inventors: Ralph Ephraim Mishler
Original assignee: Globe Union Inc
Current assignee: Globe Union Inc
Priority date: 1970-03-10
Filing date: 1970-03-10
Publication date: 1972-02-29
Anticipated expiration: 1989-02-28
Also published as: GB1343026A; BR7125044D0; JPS501435B1; FR2081826B1; DE2107163C3; NL7102901A; CA934148A; DE2107163B2; ES387770A1; CH535480A; DE2107163A1; FR2081826A1

Abstract

An apparatus for applying continuously to the surface of a dielectric substrate, simultaneously, a plurality of microthin stripe coatings of even thickness interconnected along adjacent edges, each coating formed from a flowable plastic material having different electrical properties so that adjacent coatings form a linear junction between them having uniform and improved electrical characteristics across the junction between the different materials.

Description

United States Patent Mishler 1 Feb. 29, 1972 {54] APPARATUS FOR SIMULTANEOUSLY 2,494,378 1/1950 Dexter ..118/412 X APPLYING A PLURALITY OF 2,573,952 11/1951 Bretherton... ..1 18/412 COATINGS o A SUBSTRATE 2,565,036 8/1951 MacDonald. .1l8/D1G. 9 1,510,465 10/1924 Dittmar ..118/415 X [72] Inventor: Ralph Ephraim Mlshler, Menomonee 2,878,779 3/ 1959 Biedermann et a1 ..1 18/415 X Falls, Wis.

Primary ExaminerJohn P. McIntosh [73] Asslgnee' Globe-Union Milwaukee Attorney-John Phillip Ryan, Glenn A. Buse, Donald D. [22] Filed: Mar. 10, 1970 Demon and David T. Terry [21] Appl. No.. 18,277 [57] ABSTRACT An apparatus for applying continuously to the surface of a U.S.C1 ..l18/412, 118/413, 118/415 dielectric subsuate, Simultaneously, a plurality of microthin [58] new Search 118M 412 413 415 Die 9 stripe coatings of even thickness interconnected along adjacent edges, each coating formed from a flowable plastic 56] References Cited material having different electrical properties so that adjacent coatings form a linear junction between them having uniform NITED STATES PATENTS and improved electrical characteristics across the junction between the different materials. 2,526,991 10/1950 Biddle ..l18/413 X 2,695,005 ll/l954 Lewin et a1. ..1 18/413 X 15 Claims, 7 Drawing Figures Z 'IIIIIIIIIII'IIIILII I PATENTEI] FEB 2 9 I972 SHEET 1 OF 3 INVENTOR RALPH E. MISHLER ATTORNEY PATENTEDFEB 29 I972 SHEET 3 UF 3 INVENTOR RALPH E. MISHLER ATTORNEY APPARATUS FOR SIMULTANEOUSLY APPLYING A PLURALITY OF COATINGS TO A SUBSTRATE BACKGROUND OF THE INVENTION This invention relates to an apparatus for coating a substrate from which resistor-type elements, such as linear and nonlinear resistors, can be formed for use as components in sophisticated electronic circuitry where the uniformity or quality of the elements is of paramount importance to their function and ability to remain operative over extended periods of time. Such conductive elements require a plurality of coatings in stripe form of material having different electrical properties by forming on the surface of a substrate, such as a dielectrical substance, a plurality of coatings that are parallel to each other with adjacent coatings in edge-to-edge relationship so that there is a fine edge overlap junction between adjacent coatings. It is important that the resistor type elements have an edge-to-edge relationship between coatings that produces a fine line junction so that there is produced on the top surface of the coatings a sharp division between the material of one coating and the material of another to provide a smooth transition in the change of electrical characteristics from one coating to the adjacent coating. Stripe coating of two or more conductive-type materials having different electrical properties in edge-to-edge relationship is particularly difficult where the coatings are applied to a thin phenolic resin substrate by striping of two or more coatings in one operation with a fine edge junction between the edges of adjacent coatings. For example, striping a substrate with two parallel coatings of a flowable plastic material, one having silver particles therein and the other having carbon particles therein in edge-to-edge overlapped relationship and curing the plastic coatings produces a basic resistor element having two zones, each zone having different electrical characteristics, from which resistor elements can be made.

The prior art has employed both the spray and doctor blade techniques for coating many types of articles. Such coated articles do not have a sharp junction between adjacent edges of coatings; for example, the spray coating of the substrate with two or more parallel stripes of sprayable plastic material, each having different electrical properties, produces an edge junction between coatings of a relatively wide band of intermingling of the plastics from each plastic material due to the overspraying of one coating into the other. The intermingling of the difi'erent materials in the case of resistor elements would produce a zone between coatings not having a fine line division and therefore exhibiting poor electrical properties across the wide band junction of the coatings, thus resulting in a resistor element that exhibits poor electrical resolution when an electric contact element is passed from the surface of one conductor material to the other.

In like manner, the technique of doctor blade spreading known to the coating art still does not produce a consistent edge abutment of a plurality of adjacent coatings without a relatively wide zone of intermingling of the material of one coating into the other. Although the art teaches many forms of doctor blade spreading of flowable plastic materials on substrates, it does not teach means for obtaining accurate edge overlap contact between two or more adjacent coatings simultaneously applied so that there is a fine edge junction between the materials of the adjacent coats.

SUMMARY OF THE INVENTION The apparatus of this invention overcomes the disadvantages presented in the prior art by providing means for continuously stripe coating the surface of a dielectric substrate with a plurality of parallel coatings, simultaneously, to produce in adjacent coatings an edge-to-edge overlap abutment having a line line junction therebetween. The substrate is passed under an applicator head having a plurality of dispensing compartments, each containing a flowable plastic material having particular type of electrical performing particles therein. The adjacent walls between the compartments have means for inducing the flowing together of adjacent edges of the flowable plastic material to form edge overlap abutment of plastic materials at the point where the coatings are doctored to the desired thickness as the multiple striped coated strip passes from under the compartments.

Advantageously, the coating apparatus of this invention may provide for suitable roller means to advance the substrate through its coating operation. Also, suitable edge guide means may be employed to assure that the substrate is in registry with the dispensing compartments so that the laydown of the stripe coatings provides an edge-to-edge overlapped relationship between the stripes of flowable plastic material. It will be appreciated that the plurality of compartments are positioned above the surface of the substrate with the substrate passing thereunder and with the bottom of the walls of the compartments positioned against the surface of the substrate so that it can slide thereunder, except for its forward wall which may include doctoring means with its edge spaced at a distance above the surface of the substrate equal to the thickness of the material to be coated. This allows for the doctor blades to doctor the surface of the coatings to the desired thickness for the substrate surface exiting from under the compartments. A second roller means may be positioned downstream of the applicator head so as to assure continuous movement of said substrate through the apparatus, particularly where continuous end-to-end abutted strips of substrate are fed through the apparatus. The second roller means continues the travel of the substrate when it has passed through the feed rollers until it is out of contact with the flowable plastic material in the dispensing compartments and ready to be removed from the apparatus. The second roller means may be vertical in operation, such as the edge contact roller or rollers so that the uncured flowable plastic coated on the substrate is not disturbed by the roller action.

Advantageously, the doctoring of the flowable plastic material may be accomplished by a doctor blade that forms a forward wall of the dispensing compartments and is adjustable so that changes in thickness of the coatings can be made when desired. Also, a micrometer biasing means may be operationally connected to said doctor blade so that the lower edge of the doctor blade may be micrometrically set to produce microthin strip coatings that are held to close tolerances which are reproducible. Also, the doctor blade used to form the forward wall of the dispensing compartments may be bevelled outwardly and upwardly from its inner bottom edge to form a sharp edge that places a minimum of friction of the surface of the coatings immediately passing from under dispensing compartments.

The applicator head may be held by positioning supports that assure alignment of the dispensing compartments with the substrate moving under it so that applicator heads having different dispensing compartments of different widths may be used to stripe different widths on the substrate as desired.

In order to maintain the substrate in its proper position with respect to the bottom surface of the dual compartment, spring means may be provided to bias the substrate upwardly so that coatings of even thickness are applied by the doctor blade. Also, the partition between the compartments may have its bottom edge tapered downwardly and inwardly to form a knife point contact with the inner bottom edge of the doctor blade so as to provide means for flowing together at the knife point the plastic material from each adjacent compartment to produce an edge contact of adjacent coatings at the doctoring of the material just before passage from contact with the plastic material in the dispensing compartments. It is believed that by having the plastic material in highly viscous state, such as for example 1,000 to 50,000 c.p.s. at 10 rpm. on Brookfield viscosimeter, there is produced a condition of increased flow at the adjacent edges so that the flowing together of the plastic material at the point of doctoring produces a thin edge abutment in the form of a reversed taper to provide, when cured, a fine edge overlapped junction between adjacent stripe coatings that results in consistent electrical characteristics across the junction. Also, it has been found that where the plastic material is thixotropic, the apparatus of this invention produces a flowing together to form a fine edge junction between the adjacent stripe coatings as heretofore described.

The products and the method for producing the products which may be made and carried out by the apparatus of this invention are particularly setforth and described in my appli cation for Letters Patent entitled Production of Resistive Coatings" filed concurrently herewith.

It has also been found that by producing in the bottom of the outer walls of the compartments an inward and outward taper, there is formed a smooth and even outer edge of the coatings.

BRIEF DESCRIPTION OF THE DRAWINGS Additional advantages of the apparatus of this invention for applying, simultaneously, a plurality of microthin coatings of flowable plastic materials on the surface of a substrate will become apparent from the following description of the accompanying drawings of a preferred embodiment, in which:

FIG. 1 is a view in elevation, having a portion of its view in section as taken on the line1 of FIG. 2, of an apparatus of this invention showing a guide track means and roller means for advancing the substrate, a stripe coating applicator head for applying parallel stripe coatings, and a vertical edge roller for removing the coated substrate from under the applicator head;

FIG. 2 is a plan view of the apparatus shown in FIG. 1 illustrating dual dispensing compartments in the applicator head;

FIG. 3 is a cross-sectional view on the line 33 of FIG. 2 showing the relationship of the feed rollers to the guide track for advancing a piece of substrate to said applicator head;

FIG. 4 is a cross-sectional view taken on the line 4-4 of FIG. 2 showing a vertical edge roller positioned downstream of said applicator head and the drive mechanism for rotating the feed rollers and vertical rollers to advance a piece of substrate at a constant speed through the apparatus;

FIG. 5 is a cross-sectional view on the line 55 of FIG. 1 showing the details of the leaf spring construction for contacting the underside of a piece of substrate passing through the apparatus and maintaining it in proper position during coat- 2;

FIG. 6 is a view in perspective of the applicator head showing it arranged in its positioning blocks with a piece of substrate passing under the compartments; and

FIG. 7 is an exploded view in perspective showing the component parts of the applicator head and its micrometer adj usting means for raising and lowering the doctor blade.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, numeral 10 represents a coating apparatus for simultaneously and continuously applying to the surface of the substrate or base material 12 two flowable plastic coatings in edge-to-edge overlapped relationship to each other. The coating apparatus has a guide track 14 upon which the substrate is moved. Track 14 is supported by upright members 15 which in turn are anchored to a base 16. The track 14 is in three sections: roller feed section 18, coating guide section 19 and removal section 20. Roller feed section 18 has edge guide 21 and a raised cover guide plate 22 positioned downstream thereof, both held in position by bolts 23. Coating guide section 19 has a raised guide cover plate 24 held in fixed position by bolts 25. Removal section has raised guide retaining strips 26, one positioned on each side of the track 14 and extending lengthwise therewith and covering an edge portion of the parallel edges of the substrate to guide and retain the substrate in the guide track 14 during its advancement through the apparatus. The retaining plates are maintained in position by suitable bolts 28.

Positioned between feed section 18 and the coating guide section 19 is a pair of horizontally disposed top and bottom

nip feed rolls

30 and 32, respectively, whose axis of rotation is normal to the centerline of guide track 14. Feed roll 30 is lever biased downwardly into surface contact with roll 32. The

feed rolls

30 and 32 are covered with a soft resilient material 34, such as rubber,- capable of frictional gripping of the substrate between them to move it at a constant predetermined speed through the apparatus. The top feed roll 30 operates rotationally in front and

rear bearings

36 and 38 on shaft number 40. The front and

rear bearings

36 and 38 are positioned in

pivot arms

37 and 39.

Pivot arms

37 and 39 are pivotally mounted in bearing blocks 41 and 42, respectively, on pivot shaft 44. Each

pivot arm

37 and 39 has an adjusting screw 45. The bottom feed roll 32 operates rotationally in front and

rear bearings

46 and 48 on drive shaft member 49. The front and

rear bearings

46 and 48 are maintained in

bearing blocks

50 and 52, respectively. Drive shaft member 49 at its rearward end has adrive pulley 54 for turning the drive shaft during operation of the

nip feed rolls

30 and 32 so as to move a sheet or strip of substrate 12 when it is nipped between the rolls through the apparatus. (See FIGS. 1, 2 and 3) Positioned in the removal section 20 of guide track 14 is a vertically disposed edge roll 56 for contacting the edge of the substrate as it is passed along guide track 14 to convey the substrate from the apparatus. The roll 56 has a soft surface 58 thereon, such as a rubber coating. The vertical roll 56 has a drive shaft 60 which is operatively connected to a bevel gear arrangement 62 which is in turn operatively connected to a second shaft 64 that is coupled at one end to a drive motor 66 and at the other end to a second drive pulley 67. A drive belt 68 operatively connects feed roll drive pulley 54 with drive pulley 67 so that operation of motor 66 turns feed rolls 30 and 32 and vertical edge roll 56 at a speed that maintains the passage of the substrate through the apparatus at a constant speed. Positioned opposite to edge roll 56 and in another position in removal section 20, and in coating guide section 19 are spring-biased roller mechanisms 69, the roller of which contact a parallel edge of the substrate and maintain it in contact with roll 56, one of the raised guide and retaining strips 26, and an edge of the guide cover plate 24. (See FIGS. 1, 2, and

Located between guide section 19 and removal section 20 is an applicator head 70, maintained in a fixed position with relation to guide track 14 by registering and holding plates 71 attached to the apparatus, for dispensing simultaneously dual coatings of a flowable plastic material onto the surface of the substrate 12 (see FIG. 6). The applicator head 70 has a blockshaped body portion 72 with milled out dispensing

compartments

74 and 76 formed therein and a rectangular slot 78 in the bottom thereof of a size and shape that permits the piece of substrate 12 to pass under the dispensing compartments. The top of the body portion 72 extends forward to form an integral lip or edge 80 that defines therein a U-shaped elongated slot 82 that terminates at the top of front face 84. On each side of slot 82 is a screw receiving hole 85. The bottom of

compartments

74 and 76 are each shaped so as to provide a rectangular opening that is smaller in width than the width of the major portion of the compartment, but of the width of the coating to be applied to the substrate. The compartments have

outer sidewalls

86 and 88, respectively, of

compartments

74 and 76 and backwalls 87 and 89. The bottom portion of

walls

86 and 88 are angled towards each other to form a sharply tapered

edge

90 and 92, respectively. A partition wall 94 separates the two compartments, the forward edge of the partition wall being tapered downwardly and inwardly to form a sharp point 96 with the bottom of the partition angling rearward to form a progressively wider flat bottom 98 from point 96 to the back of the dispensing compartments. Thus, there is provided a double taper in partition wall 94 with one taper being vertical and the other taper being horizontal with both tapers meeting to form point 96.

Positioned in the front face 84 and spaced from each side of

outer walls

86 and 88 are

dowel pins

100, and 102, respectively, and two threaded

screw retaining holes

104 and 106; two other threaded screw retaining holes, not shown, are positioned above

holes

104 and 106. A rectangular holding block 108 defining two bolt holes 110 on one side of the front face of block 108 and two bolt holes 112 on the other side thereof positioned to mate with threaded screw holes 104 and 106 when bolts 113 are assembled. In like manner there are two holes, not shown, in back of block 108 adapted to receive

dowel pins

100 and 102 when the holding block is assembled to the front face 84 of body portion 72. The top surface of holding block 108 has a centralized wide slot 114 therein with a U-shaped slotted groove 115 extending from the front face of the block inwardly. On each side of the slotted groove 115 are vertically positioned biasing pins 116 and outboard of each side of wide slot 114 re thread holes 117 which are in registry with screw receiving holes 35 positioned in edge 80 of the body portion 72.

Between holding block 180 and front face 84 is positioned a doctor blade 118. The doctor blade is of an L-shaped configuration having a downwardly projecting portion 119 and a horizontally projecting top portion 120 at right angles to each other. The outer edge of top portion 120 has a second U- shaped slot 122 defined therein while the bottom edge of the downwardly projecting portion 119 has a tapered edge 124. The downwardly projecting portion 119 also forms the front wall for closing the

compartments

74 and 76 with the tapered edge 124 presenting a sharp edge along the bottom thereof where it meets with front face 84 when the top portion 120 is positioned in wide slot 114 of the holding block 108. In this position the horizontal projecting top portion 120 of the doctor blade is positioned in wide slot 114 with the

U-shaped slots

82 and 122 in registry with slotted groove 115 with bottom surface of the top portion 120 resting on biasing pins 115 when holding block 108 is assembled to front face 84 with the doctor blade 118 therebetween.

Positioned on top of edge 80 is a micrometer holding bar 126 having a centrally disposed micrometer barrel 128 and shaft 130 positioned therein with the shaft extending vertically downward through U-shaped slot 82. The end of shaft 130 has an annular groove 132 therein adapted to be received in and retained by U-shaped slot 122 so that an incremental movement of shaft 130 by turning barrel 128 causes the doctor blade 118 to be moved vertically with biasing by pins 116 thereby assuring that a fine adjustment in height above the top surface of the substrate can be made to produce the desired thickness of coatings on the substrate. The end portion of shaft 130 projects into U-shaped slot 115, bolt retaining holes 136 are defined near each end of the micrometer holding bar 126 in register with holes 85 and threaded holes 117 in holding block 108 so that when bolts 137 of holding bar 126 and bolts 113 of holding block 108 are assembled, the micrometer holding bar, the doctor blade, and the holding block are united to the body portion 72 to complete the assembly of the applicator head 70 and to provide for adjustment of the doctor blade riding on the front face 84 when bolts 113 are loose in the applicator head assembly with the assembled applicator head being retained in fixed position by setscrew 139 which is operatively connected to registering and holding plates 71 with the end thereof bearing against the side of applicator head 70 when the set screw is up tight.

Positioned under the bottom of the applicator head 70 and normal to the length of guide track 14 are two spring-biasing means 140 and 142. Each biasing means has leaf spring 144 adapted to support the substrate as it passes under the bottom of dispensing

compartments

74 and 76 in slot 78 so that the flat surface of the substrate is always maintained against the bottom of the two

outer sidewalls

36 and 88 and backwalls 89 and in spaced relationship with the bottom of the sharp edge of the doctor blade to provide for a constant doctoring of material on the surface of the substrate that is of uniformly deposited thickness. The springs 144 are held by holding lugs 146 in turn are attached to the frame of apparatus 10.

In operation, the micrometer barrel 128 is adjusted so that the bottom edge 124 of the doctor blade 118 is positioned at the desired height above the surface of the substrate passing under the

compartments

74 and 76. When the proper adjustment is set, the screws 113 are tightened to place the doctor blade in a fixed position. With a strip of substrate positioned under the applicator head 70, flowable plastic material of desired electrical characteristics is placed in each of the

compartments

74 and 76. The plastic materials is of such consistency that it will spread evenly when striped on the piece of substrate as it is passed through slot 78 under

compartments

74 and 76 when the motor is energized and feed roll 32, driven roll 30 and edge feed roll 56 are in continuous operation.

The pieces of dielectric substrate to be coated are continuously fed flatwise on the guide track 14 of feed section 18 with the pieces pushed longitudinally of the track with the forward edge of each piece in engagement with the rearward edge of the piece preceding it while the nip feed rolls 30 and 32 continuously advance the substrate into coating guide section 19, being held in a predetermined position by the spring-biased roller mechanisms 69. The top surface of the substrate, after passing through the coating guide section, passes into slot 78 where the top surface of the substrate receives a plurality of coatings of plastic material, designated as A and B on FIG. 6, each having different electrical characteristics. Spring biasing means 144 maintains the substrate against the bottom edges of the compartments in the applicator head and at the proper distance from the sharp edge 124 of the doctor blade 118 to assure that the stripe coatings are doctored to a uniform thickness.

The horizontal taper of the bottom of the partition wall 94 separating the

compartments

74 and 76 and the tapering of the bottom portion of the partition wall to form a sharp point at the walls intersection with the doctor blade causes the two plastic materials to flow together and meet at a point at the face of the doctor blade 118 where adjacent edges of the coatings overlap in an interfacial reversed taper to form a precise and sharp line junction C" therebetween so that, upon curing, the conductive characteristics across the junction are more uniform and of higher quality than heretofore presented in the art and thus provide improved resolution across the junction. The knife edge doctor blade produces an even thickness coating as the dielectric substrate passes from under the compartments with the nip feed rolls 30 and 32 and the edge roll 56 assuring that the piece is fed at a constant continuous rate through the stripe coating operation. After the substrate has been coated and passed from the apparatus it is then cured to set the coatings on the substrate.

It will be appreciated that the registering and holding plates 71 are so arranged with respect to the guide track that a multiple number of different applicator heads may be used depending upon the number of stripes and/or the width of the stripes desired.

In forming a resistor-type element from which small resistor can be made, a strip of dielectric substrate of about 20 mils in thickness and about 1% inches wide may have a lay down of a first stripe coating of plastic about three-eighths inch wide having silver particles therein and a second stripe coating of plastic about one-half inch wide having carbon particles therein with their adjacent edge flowing together in a reversed tapered overlapped junction that upon curing provides two parallel stripes of plastic material having different electrical properties with a thin edge overlap junction therebetween separating the materials of different electrical characteristics. From such coated substrate can be cut crescent-type resistor elements oriented so that the ends of the resistor elements are in the stripe with the silver particles while the center of the crescent element forms the stripe having the carbon particles.

Also it is appreciated that the apparatus of this invention can produce a variety of thicknesses by adjustment of the doctor blade. Substrates of as little as 10 mils in thickness may be used and suitable multiple stripings have been found to be produced when the thickness of the stripings are from about 0.5 to about 10 mils. it has been found that the use of plastic materials having viscosities from about 1,000 to 50,000 c.p.s. at 10 r.p.m. on a Brookfield viscosimeter when the substrate is advancing at speeds from about to about 60 feet per minute produces excellent striped coated products having the desired overlap. it will be appreciated that the speed of advancement and the viscosity of the plastic material are interrelated so as to provide the overlap junction. Also excellent results are obtained when the plastic material is in a thixotropic state for it is believed that the flowing of two different types of plastic materials together bring them into a more sharply defined edge-to-edge overlap contact. Such a contact produces an excellent true fine line junction between the adjacent edges of the stripes which brings about high quality and improved resolution that is better than has been heretofore produced in the art.

It will also be appreciated that many different types, sizes and shapes of dielectric substrates can be simultaneously striped with a plurality of coatings in accordance with the apparatus of this invention. Among the suitable forms of dielectric substrates are ceramics, glass, various types of plastic materials and the like. The substrate may be in the form of sheets, films or any other form that has a flat surface with the capability of receiving and holding the coatings applied thereto. Also, the surface of the dielectric substrate may have a group of indexing holes therein for registering the surface of the substrate with the striping of the coatings thereon so that the parallel coatings will always appear in the exact position on the substrate. Also, indexing holes may be used as guides to punch, out and break away desired units of resistor elements from the body of the coated substrate.

It will be appreciated that the apparatus of this invention will lay down simultaneously stripe coatings in which there is a reversed edge taper between the material of adjacent coatings and that these tapers are substantially uniform and in interfacial relationship with each other and provide a junction line of demarcation in the top surface of the coating so as to produce a smooth transition of the electrical characteristics when passing from one coating to the other.

It has been found that the reversed tapered overlap between adjacent edges of said parallel stripe coatings produces a transition zone extending lengthwise on the top surface of the substrate with distinct lines of demarcation at the end of the taper portion to provide substantially linear edges, one on the surface of adjacent parallel stripe coatings and the other on the bottom of the stripe coating that is in contact with the top surface of the substrate. Thus, the reversed taper with its sharp lines of demarcation provides a transitional zone for effecting smooth change from the electrical characteristics of one stripe coating to the coating adjacent to it.

it will be appreciated that many changes, modifications and additions may be made to the apparatus of this invention in which only a preferred embodiment has been illustrated and described.

What is claimed is:

1. An apparatus for depositing simultaneously a plurality of parallel microthin stripe coatings on a flat surface of an advancing dielectric substrate with the adjacent edges of the coatings having a fine overlap comprising: roller means for continuously advancing said dielectric substrate in registry with and under a plurality of compartments, each having a substantially flat bottom portion and a common partition wall between adjacent compartments, each of said compartments adapted to hold a body of gravity flowable plastic material containing conductive particles dispersed therethrough having discrete electrical characteristics; a discharge opening in each of said bottom portions for supplying a quantity of said flowable plastic material to the surface of said advancing substrate to effect a deposit of a plurality of stripe coatings thereon; a bevelled edge means in said partition wall positioned adjacent to said substrate capable of inducing the flowing together of adjacent edges of the stripes of said flowable plastic materials to produce said fine overlap during the forming of said stripe coatings as said substrate advances; and doctor blade edge means in said compartments for doctoring an even thickness to said coatings on the surface of said substrate as it passes out of contact with said body of flowable plastic material, said bevelled edge means being two tapered portions that form a point contact with the inner bottom edge of said doctor blade edge means and tapered in a direction normal to each other; and said roller means being in operational contact with said dielectric substrate before and after said coating is applied.

2. The apparatus of claim 1 in which said doctor blade edge means includes micrometer biasing means adapted to adjust its height in relationship with the top surface of the substrate for providing said microthin coatings.

3. The apparatus of claim 1 in which said plurality of compartments are two, one adapted to deposit a wider stripe coating than the other.

4. The apparatus of claim 1 in which said roller means for continuously advancing said dielectric substrate is a pair of horizontally placed advancing rolls having their axis of rotation normal to the axis of said substrate and positioned for feeding the forward ends of rectangularshaped pieces of substrate having parallel edges in succession under said compartments and an edge contacting roll that removes said substrate from under said compartments when the rearward end of each piece of substrate has passed through said advancing rolls.

5. The apparatus of claim 4 in which a biasing roller means maintains the edge of the substrate in contact with said edge contacting roll.

6. The apparatus of claim 1 in which said substrate is a ceramic strip.

7. The apparatus of claim 1 in which said substrate is glass.

8. The apparatus of claim 1 in which said substrate is a flexible plastic material.

9. The apparatus of claim 1 in which the substrate is a thin phenolic resin.

10. The apparatus of claim 1 in which said flowable conductive plastic material is a homogenous mixture of a curable plastic substance and conductive particles having a viscosity of from about 3,000 to 50,000 c.p.s. at 10 rpm. on a Brookfield viscosimeter.

11. The apparatus of claim 10 in which said bodies of flowable conductive plastic material is thixotropic.

12. The apparatus of claim 1 in which said plurality of compartments are removably held in a registering and holding means thereby permitting a variety of different groupings of compartments to be used interchangeably capable of coating simultaneously a plurality of different width stripe coatings with different compartment groupings.

13. The apparatus of claim 1 in which said edge means for doctoring each of said coatings is positioned from about 0.5 to about 10 mils above the surface of the advancing substrate.

14. The apparatus of claim 1 in which said means for con tinuously advancing the dielectric substrate advances it at a speed of from about 20 to about 60 feet per minute.

15. An apparatus for depositing simultaneously two parallel microthin stripe coatings having a fine reversed tapered edge overlap between adjacent coatings formed on the surface of a thin flat piece of a dielectric substrate having parallel edges comprising: guide track means for supporting and guiding said flat dielectric substrate along its parallel edges; nip roller means for continuously advancing at a constant rate said strip of dielectric substrate; applicator means having two compartments therein each adapted to hold and dispense a body of gravity flowable plastic material containing conductive particles dispersed therethrough having discrete electrical characteristics, said compartments having a substantially flat bottom portion, outer sidewalls, a rearward wall, a forward wall, and a common partition wall; means for registering and guiding the surface of said substrate into contact with the flowable plastic material in said compartments; bevelled edge means in said common partition wall for flowing said two parallel stripes of plastic materials together to form a fine reversed tapered overlap in adjacent edges of the stripe coatings at a point just before passage from contact with said plastic material in said compartments; doctor blade edge means for doctoring an even thickness to said parallel stripe coatings at the point of edge contact between the adjacent edges of said coatings, said bevelled edge means being two tapered portions that form a point contact with the inner bottom edge of said doctor blade edge means and are tapered in a direction normal to each other; and edge roller means for continuing removal of said coated substrate from contact with said bodies of plastic material.

Claims

4. The apparatus of claim 1 in which said roller means for continuously advancing said dielectric substrate is a pair of horizontally placed Advancing rolls having their axis of rotation normal to the axis of said substrate and positioned for feeding the forward ends of rectangular-shaped pieces of substrate having parallel edges in succession under said compartments and an edge contacting roll that removes said substrate from under said compartments when the rearward end of each piece of substrate has passed through said advancing rolls.

6. The apparatus of claim 1 in which said substrate is a ceramic strip.

7. The apparatus of claim 1 in which said substrate is glass.

9. The apparatus of claim 1 in which the substrate is a thin phenolic resin.

10. The apparatus of claim 1 in which said flowable conductive plastic material is a homogenous mixture of a curable plastic substance and conductive particles having a viscosity of from about 3,000 to 50,000 c.p.s. at 10 r.p.m. on a Brookfield viscosimeter.

14. The apparatus of claim 1 in which said means for continuously advancing the dielectric substrate advances it at a speed of from about 20 to about 60 feet per minute.