TWI652179B - Printing screens, methods of fabricating the same and methods of screen printing - Google Patents

Abstract

The stencil disclosed herein includes a plurality of first printing apertures and a plurality of second printing apertures intersecting the first printing apertures, wherein the second printing apertures include a mesh defining a plurality of secondary apertures.

Description

Printing screen, method of manufacturing the same, and method of screen printing

The invention relates to a printing screen, often also referred to as a stencil, in particular for printing narrow elongate structures on a substrate, such as a front side conductor on a solar cell, and a method and network for making such a printing screen The method of printing.

In the case of photovoltaic cells, a significant obstacle to continued development is the front metallization of the printing, especially in the joining of the front conductor and the bus bar, and especially in a single printing operation.

In one aspect, the invention provides a stencil comprising a plurality of first printing apertures and a plurality of second printing apertures intersecting the first printing apertures, wherein the second printing apertures (but not the first printing apertures) comprise a plurality of defined apertures The mesh of the secondary hole.

In another aspect, the present invention provides a screen printing method using the above stencil, wherein the first and second print deposits in a cross-over relationship are printed in a single printing operation.

In a specific aspect, a first tension is applied along a length of the first printing aperture, and a second tension lower than the first tension is applied across a width of the first printing aperture, optionally, the first tension is at least 1.5 times greater than the second tension.

In still a further aspect, the present invention provides a method of making a stencil comprising the steps of: providing a first patterned layer (which may alternatively be a dry film resist) to a mandrel of an electroforming apparatus; at a first patterned layer a hole is defined in which an open image is formed in the first patterned layer that allows the material to be electrically formed on the mandrel; a first stencil material layer is accumulated in the open image of the first patterned layer; and a second patterned layer is provided ( Optionally selecting a dry film resist) to the first patterned layer, the second patterned layer having a size and shape corresponding to the holes in the first patterned layer and aligned with the holes in the first patterned layer And accumulating a second layer of stencil material in the remaining open image of the first patterned layer.

3‧‧‧Template

4‧‧‧Printing holes

5‧‧‧Frame

7‧‧‧ first floor

9‧‧‧ second floor

15‧‧‧First printing hole

17‧‧‧Second printing hole

21‧‧‧ mesh

23‧‧‧ holes

25‧‧‧Inwardly thinner surface

27‧‧‧Outwardly thinned surface

31‧‧‧First elongated mesh element

33‧‧‧Second elongate mesh element

41‧‧‧First printing hole

43‧‧‧Second printing hole

101‧‧‧The first illuminable imaging layer

101’‧‧‧ exposed layer

103‧‧‧ mandrel

105‧‧‧Open image

107‧‧‧Materials

111‧‧‧Second illuminable imaging layer

111’‧‧‧second exposure layer

115‧‧‧Pre-patterned components

201‧‧‧Front metallized lines

203‧‧‧ positive bus bar

301‧‧‧Front metallized lines

303‧‧‧ positive bus bar

D‧‧‧ Width of the mesh element

D‧‧‧Printing direction

F ₁ ‧‧‧First tension

F ₂ ‧‧‧second tension

W ₁ ‧‧‧Average width of the first printed hole

W ₂ ‧‧‧Average width of the second printing hole

β ₁ ‧‧‧An angle enclosed by a tapered surface

_{2 2} ‧‧‧ Angles of the outwardly thinner surface

θ ₁ ‧‧‧inclination angle of the first mesh element to the longitudinal axis of the second printing hole

θ ₂ ‧‧‧inclination angle of the second mesh element to the longitudinal axis of the second printing hole

The preferred embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings in which: FIG. 1 illustrates a printing screen unit in accordance with a first aspect of the invention; FIG. Partial bottom side view of the joining of the first and second printing holes in the stencil of the printing screen unit; FIG. 3 is a first vertical sectional view of the stencil of FIG. 2 (along the section II of FIG. 2); FIG. a second vertical cross-sectional view of the stencil of 2 (along section II-II of Figure 2); Figures 5 (a) to (g) exemplify the processing steps of manufacturing the stencil of Figure 2 (along section II of Figure 2); Figures 6(a) through (g) illustrate the processing steps in the manufacture of the stencil of Figure 2 (along section II-II of Figure 2), which corresponds to Figures 5(a) through (g); The front metallized line printed by the stencil of 2 and the front bus bar are joined; FIG. 8 exemplifies the modification of the first and second printing holes of the stencil in one of the printing screen units of FIG. Partial bottom side view of the joint; FIG. 9 illustrates a bottom bottom view of the joint in the first and second printing holes of another modified stencil of the printing screen unit of FIG. 1; FIG. 10 illustrates the printing of FIG. A bottom side view of a portion of the first and second printing holes of the stencil that further modifies the stencil; FIG. 11 illustrates a first vertical cross-sectional view of the stencil of FIG. 10 (along section III-III of FIG. 10); 12 demonstrates a second vertical cross-sectional view of the stencil of FIG. 10 (along section IV-IV of FIG. 10); and FIG. 13 demonstrates the joining of the front metallized lines printed with the stencil of FIG. 10 and the front bus bar.

1 through 6 illustrate a printing screen unit in accordance with a first embodiment of the present invention.

The printing screen unit comprises: a stencil 3, the specific aspect being a metal foil comprising a pattern of printing holes 4 defining an image to be printed; and a frame 5 supporting the stencil 3 and allowing for separation by the frame 5 Mechanism to extend the template.

The stencil 3 is formed by the first and second layers 7, 9; the upper first layer 7 provides a surface that traverses over the printing element (not shown, such as a rubber roller), and the lower second layer 9 contacts the underlying workpiece (This is a wafer for a fuel cell or a solar cell).

In this particular aspect, the first layer 7 is a metal layer that is fabricated prior to the second layer 9.

In this particular aspect, the first layer 7 is an electrically formed layer, here an electrically formed nickel layer.

In an alternative embodiment, the first layer 7 can be chemically etched or any other suitable The cutting technology is formed by sheets.

In this particular aspect, the first layer 7 has a thickness of 50 microns.

In a preferred embodiment, first layer 7 has a thickness of from about 20 microns to about 100 microns, alternatively from about 30 microns to about 80 microns, alternatively from about 40 microns to about 60 microns.

In this particular aspect, the second layer 9 is a metal layer that is fabricated after the first layer 7.

In this particular aspect, the second layer 9 is an electrically formed layer, here an electrically formed nickel layer.

In an alternative embodiment, the second layer 9 can be formed from a sheet by chemical etching or any other suitable cutting technique.

In this particular aspect, the second layer 9 has a thickness of 50 microns.

In a preferred embodiment, the second layer 9 has a thickness of from about 20 microns to about 100 microns, alternatively from about 30 microns to about 80 microns, alternatively from about 40 microns to about 60 microns.

The first layer 7 comprises a plurality of first printing apertures 15, which in this particular are parallel, narrow-length linear apertures, which define the front metallized lines of the solar cell. For ease of demonstration, only one printing aperture 15 is illustrated in FIG.

In this particular aspect, the first printing aperture 15 has an average width W _{1 of} about 40 microns.

In a preferred embodiment, the first printing aperture 15 has an average width W ₁ from about 20 microns to about 100 microns, alternatively from about 20 microns to about 80 microns, alternatively from about 20 microns to about 60 microns, alternatively from about 25 microns to about 50 microns.

In this particular aspect, the first printing aperture 15 has a pitch of about 1.25 mm.

In a preferred embodiment, the first printing aperture 15 has a pitch of from about 0.5 mm to about 2.5 mm, alternatively from about 0.5 mm to about 2.0 mm, alternatively from about 1 mm to about 1.5 mm.

The first layer 7 further includes a plurality of second printing apertures 17 defining the front bus bar of the solar cell, and in this particular aspect is an elongated aperture that extends substantially orthogonal to the first printing aperture 15 Relationship. For ease of demonstration, only one second printing aperture 17 is illustrated in FIG.

In this particular aspect, the second printing aperture 17 has an average width W _{2 of} about 1.25 mm.

In a preferred embodiment, the second printing aperture 17 has an average width W _{2 of} from about 0.5 mm to about 2.5 mm, alternatively from about 0.5 mm to about 2.0 mm, alternatively from about 1 mm to about 1.5 mm.

In this particular aspect, the second printing aperture 17 is tapered over its length.

In an alternative embodiment, the second printing aperture 17 is linear over its length.

The second printing aperture 17 includes a mesh 21 that includes a plurality of secondary holes 23.

In this particular aspect, the secondary aperture 23 has an open area which has a reduced lateral dimension in the printing direction D, at least in its cross section (here at its downstream end), so as to present an inwardly tapered surface 25 .

In this particular aspect, the inwardly tapered surface 25 is substantially linear.

In this particular aspect, the inwardly tapered surface 25 encloses a substantially 90 degree angle β ₁ .

In a preferred embodiment, the angle β ₁ enclosed by the inwardly tapered surface 25 is less than about 120 degrees, and optionally less than about 100 degrees.

In a preferred embodiment, the angle β ₁ enclosed by the inwardly tapered surface 25 is greater than about 40 degrees, and optionally greater than about 60 degrees.

In an alternative embodiment, the inwardly tapered surface 25 is arcuate, such as defined by a smooth curve or a plurality of linear or arcuate segments.

In this particular aspect, the secondary aperture 23 has an open area which increases in lateral direction in the printing direction D, at least in its cross section (here at its upstream end), in order to present an outwardly thinned surface 27.

In this particular aspect, the outwardly thinned surface 27 is substantially linear.

In this particular aspect, the outwardly thinned surface 27 encloses an angle β ₂ of substantially 90 degrees.

In a preferred embodiment, the outwardly tapered surface 27 encloses an angle β _{2 of} less than about 120 degrees, and optionally less than about 100 degrees.

In a preferred embodiment, the outwardly tapered surface 27 encloses an angle β ₂ greater than about 40 degrees, and optionally greater than about 60 degrees.

In an alternative embodiment, the outwardly tapered surface 27 is arcuate, such as defined by a smooth curve or a plurality of linear or arcuate segments.

In this particular aspect, the secondary aperture 23 has a substantially square open area where its opposing corners are aligned with the printing direction D.

In an alternative embodiment, the secondary aperture 23 has a substantially diamond or diamond shape. The area where the opposite corners are aligned with the printing direction D.

In another alternative embodiment, the secondary aperture 23 has a substantially circular open area.

In still another alternative embodiment, the secondary aperture 23 has a substantially elliptical open area with the major axis of the ellipse aligned with the printing direction D.

In this specific aspect, the mesh 21 is formed by a plurality of first elongate mesh members 31 and a plurality of second elongate mesh members 33, and the plurality of first elongate mesh members 31 are arranged The parallel relationship, and the plurality of second elongate mesh members 33 are arranged in a parallel relationship and in a cross relationship with the first mesh member 31.

In this particular aspect, the first and second mesh members 31, 33 are arranged in an orthogonal relationship.

In this particular aspect, the first and second mesh members 31, 33 each extend in opposite directions and are at an oblique angle θ ₁ , θ _{2 to} the longitudinal axis of the second printing aperture 17 . In this specific aspect, the inclination angles θ ₁ and θ ₂ of the first and second mesh members 31, 33 are the same.

In this particular aspect, the mesh elements 31, 33 have a width d of about 30 microns.

In a preferred embodiment, the mesh members 31, 33 have a width d from about 15 microns to about 100 microns, alternatively from about 15 microns to about 80 microns, alternatively from about 15 microns to about 60. Micron, alternatively from about 15 microns to about 45 microns.

In this particular aspect, the mesh members 31, 33 each have a pitch of about 200 microns.

In a preferred embodiment, the mesh members 31, 33 each have a pitch of from about 100 microns to about 1000 microns, alternatively from about 100 microns to about 800 microns, alternatively from about 100 microns to about 600. Micron, optionally from about 100 microns to about 400 microns, optional Selectively from about 150 microns to about 300 microns.

In this specific aspect, the inclination angles θ ₁ and θ _{2 of} the first and second mesh members 31, 33 are each 45 degrees.

In a preferred embodiment, the angles of inclination θ ₁ , θ ₂ of the first and second mesh members 31, 33 are from about 30 degrees to about 70 degrees, alternatively from about 35 degrees to about 65 degrees.

In this particular aspect, the first printing apertures 15 each have an open engagement with the individual apertures 23 of the second printing aperture 17. This arrangement has been discovered by the inventors to provide significantly improved connectivity between the first and second printing apertures 15, 17.

The second layer 9 comprises a plurality of first printing holes 41, which in this particular are parallel, narrow-length linear holes, which are the counterparts of the first printing holes 15 of the first layer 7, together defining the solar cells Front metallized lines. For ease of demonstration, only one first printing aperture 41 is illustrated in FIG.

The second layer 9 further includes a plurality of second printing holes 43, in this particular aspect being elongated holes extending in a substantially orthogonal relationship with the first printing aperture 41 and a second printing of the first layer 7. The counterparts of the holes 17 together define the front bus bar of the solar cell. For ease of demonstration, only one second printing aperture 43 is illustrated in FIG.

5(a) to (g) and 6(a) to (g) illustrate the process of the above stencil 3 according to an embodiment of the present invention.

In a first step, as exemplified in Figures 5(a) and (b), a first photoimageable layer 101 is applied to a mandrel 103 of an electroforming apparatus. In this particular aspect, the thickness of the photoimageable layer 101 corresponds to the combined thickness of the first and second layers 7, 9 of the desired stencil 3, where the thickness is 100 microns.

In this embodiment, the photo-imageable layer 101 is formed by a dry film, such as a dry film. A film resist laminated to the mandrel 103.

In a second step, as exemplified in Figures 5(b) and 6(b), the first and second printing holes 15, 17 of the first layer 7, and the first printing holes 41 of the second layer 9 pass through the patterned mask. The photoimageable layer 101 is exposed to be exposed in the photoimageable layer 101, and then the unexposed material is subsequently removed, leaving an opening in the exposed layer 101' that allows the material to be electrically formed on the mandrel 103. Image 105.

In this specific aspect, although a negative resist is being used, in other specific aspects, a positive resist may be used.

In an alternative embodiment, the photoimageable layer 101 can be exposed by direct writing thereof, such as by a laser tool, and then subsequently removing the unexposed material. Again, in other specific aspects, a negative resist is not used, or a positive resist can be used instead.

In a third step, as exemplified in Figures 5(c) and 6(c), material 107 (in this particular aspect nickel) is accumulated in the open image 105 of the exposed layer 101'. This electrical formation process continues until the deposited material 107 has the desired thickness of the first layer 7, which is 50 microns.

In a fourth step, as illustrated in Figures 5(d) and 6(d), a second photoimageable layer 111 is applied to the exposed layer 101'. In this particular aspect, the second photoimageable layer 111 has a thickness of 50 microns.

In this particular aspect, the second photoimageable layer 111 is formed of a dry film, such as a dry film resist, which is applied to the exposed layer 101'.

In this particular aspect, the second photoimageable layer 111 includes a pre-patterned element 115 having a size and shape corresponding to the second printing aperture 43 of the second layer 9 and a second printing aligned with the first layer 7. The hole 17, which has been defined by the deposition material 107.

In a fifth step, as illustrated in FIGS. 5(e) and 6(e), the second photoimageable layer 111 is thermally rolled to the exposed layer 101', and the second photoimageable layer 111 is conformed to the exposed layer. The underlying structure of 101' and encloses the underlying open image 105, and subsequent exposure to provide a second exposed layer 111'.

In a sixth step, as exemplified in Figures 5(f) and 6(f), material 115 (in this particular aspect nickel) accumulates in the remaining open image 105 of the exposed layer 101'. This electroforming process is continued until the deposited material 115 has the desired thickness of the second layer 9, which is 50 microns.

In the final seventh step, as exemplified in Figures 5(g) and 6(g), the materials of the first and second exposed layers 101', 111' are removed leaving the electroformed stencil 3.

In this particular aspect, when the stencil 3 is used, the first tension F ₁ can be applied along the length of the first printing apertures 15, 41 and can span the width of the first printing apertures 15, 41 and along the second printing The length of the holes 17, 43 applies the second tension F ₂ .

In this particular aspect, the first tension F ₁ is at least 1.5 times the second tension F ₂ , alternatively at least 1.75 times, alternatively at least 2 times.

In this particular aspect, the second tension F _{2 is} less than 25 Newtons, alternatively less than 20 Newtons, alternatively less than 15 Newtons, alternatively less than 10 Newtons.

In this particular aspect, the second tension F _{2 is} greater than 2 Newtons, and optionally greater than 5 Newtons.

Figure 7 illustrates the joining of the front metallization lines 201 and the front bus bar 203 printed using the stencil 3 of the above specific aspect.

As will be seen, the joining of the front metallization line 201 and the front bus bar 203 is excellent, and the front bus bar 203 is continuous without defects. What is required is this change Good printing is achieved by the operation of the inwardly thinner faces 25, 27 of the secondary holes 23 in the second printing hole 17 of the first layer 7, which is believed to provide concentrated pressure to act to drive the printing media in place. The volume of the second printing hole 43 of the second layer 9 below the second printing hole 17 of the first layer 7, and particularly for the first printing hole 15 of the first layer 7 and the second hole 23 of the second printing hole 17 Engagement.

The stencil 3 exemplified in Fig. 8 has a modified joint between the first printing aperture 15 and the individual secondary apertures 23 of the second printing aperture 17. As can be seen, although the joint between the first printing aperture 15 and the individual secondary apertures 23 is open, the secondary apertures 23 are of different sizes.

The stencil 3 exemplified in Fig. 9 has another first modified joint between the first printing aperture 15 and the individual secondary apertures 23 of the second printing aperture 17. As can be seen, although the joint between the first printing hole 15 and the individual secondary holes 23 is open, the secondary holes 23 have different sizes, and the first printing hole 15 has an offset or asymmetry with the secondary hole 23. relationship.

The printing screen 3 exemplified in Figures 10 through 12 is a modified version of the printing screen 3 of the first specific aspect described above.

The printing screen 3 of this embodiment is similar to the printing screen 3 of the specific aspect described above, and therefore, in order to avoid unnecessary repetitive description, only the differences will be described in detail, and the same components are denoted by the same reference numerals.

In this particular aspect, the printing screen 3 differs in the arrangement of the webs 21, wherein the secondary holes 23 comprise elongated holes extending in the printing direction D.

In this particular aspect, the first mesh element 31 has the same pitch as the first described specific aspect, and the second mesh element 33 has a larger pitch, here five times greater than the specific aspect first described. spacing.

Figure 13 illustrates the joining of the front metallization lines 301 and the front bus bar 303 printed using the stencil 3 of the above specific aspect.

As will be seen, although the bond between the front metallization line 201 and the front bus bar 203 is continuous, there is no defect in this continuity, as is the printing achieved by the stencil 3 of the specific aspect first described. It has been expected that the stencil 3 of this specific aspect will have a reduced area due to the total area of the mesh members 31, 33 relative to the second printing hole 17, and will produce a printing of the stencil 3 which is superior to the specific aspect described first. It is understood by the art that the area occupied by the mesh element hinders printing performance, and the art practice is to develop printing holes having as large an open area as possible. The results achieved by the template 3 of the specific description first described are contrary to what is understood by the art, and are therefore very surprising.

In the end, it will be appreciated that the invention has been described in its preferred embodiments, and may be modified in many different ways without departing from the scope of the invention as defined by the appended claims.

For example, although the stencil 3 of the above specific aspect has been developed to allow a single printing operation to be used to print the front metallization lines and the bus bar, in an alternative embodiment, a dual printing process may be employed, one of which is a template 3a is used for a printing operation to include the first printing holes 15, 41, and the other stencil 3b is used for another printing operation to include the second printing holes 17, 43. Thus, the use of these two stencils 3a, 3b in separate printing operations allows for the printing of both front metallization lines and bus bar. As noted above, when using the stencil 3a having the first printing apertures 15, 41, substantially greater tension can be applied along the length of the first printing apertures 15, 41.

Claims (53)

A stencil comprising a plurality of first printing apertures and a plurality of second printing apertures intersecting the first printing apertures, wherein the first printing apertures have no secondary apertures and comprise a narrow length extending into a substantially parallel relationship Shaped apertures, and wherein the second printed apertures include a mesh defining a plurality of secondary apertures and include elongated apertures extending into substantially orthogonal relationship with the first printed apertures. A stencil as claimed in claim 1, wherein the first printing holes are for printing metallized lines on the wafer. The stencil of claim 2, wherein the first printing apertures have an average width of from about 20 microns to about 100 microns, alternatively from about 20 microns to about 80 microns, alternatively from about 20 Micron to about 60 microns, alternatively from about 25 microns to about 50 microns. The stencil of claim 2, wherein the first printing apertures have a pitch of from about 0.5 mm to about 2.5 mm, alternatively from about 0.5 mm to about 2.0 mm, alternatively from about 1 mm. It is about 1.5 mm. A stencil as claimed in claim 1, wherein the second printing holes are for printing bus bars on the wafer. The stencil of claim 5, wherein the second printing apertures have an average width of from about 0.5 mm to about 2.5 mm, alternatively from about 0.5 mm to about 2.0 mm, alternatively from about 1 Mm to about 1.5 mm. A stencil according to claim 5, wherein the second printing holes are tapered in a longitudinal extent thereof. Such as the template of claim 5, wherein the second printing holes are in their longitudinal direction The circumference is straight. A stencil according to claim 1, wherein the secondary holes have an open area which is reduced in the printing direction, at least in its cross section, optionally at the downstream end thereof, so as to present The surface that is getting thinner inside. A stencil of claim 9 wherein the inwardly tapered surface encloses an angle of less than about 120 degrees, alternatively less than about 100 degrees. A stencil of claim 9 wherein the inwardly tapered surface encloses an angle greater than about 40 degrees, alternatively greater than about 60 degrees. A stencil as claimed in claim 9 wherein the inwardly tapered surface is substantially linear. A stencil according to claim 9 wherein the inwardly tapered surface is arcuate, optionally as defined by a smooth curve or a plurality of linear or arcuate segments. A stencil according to claim 1, wherein the secondary holes have an open area, the lateral dimension of which is increased in the printing direction, at least in its cross section, optionally at its upstream end, so as to present A thinner surface that goes outward. A stencil of claim 14 wherein the outwardly tapered surface encloses an angle of less than about 120 degrees, alternatively less than about 100 degrees. A stencil of claim 14 wherein the outwardly tapered surface encloses an angle greater than about 40 degrees, alternatively greater than about 60 degrees. A stencil as claimed in claim 14 wherein the outwardly thinned surface is substantially linear. A stencil as claimed in claim 14 wherein the outwardly thinned surface is arched Alternatively, as defined by a smooth curve or a plurality of linear or arcuate segments. A stencil according to claim 1, wherein the secondary holes have a substantially square open area, and optionally, the opposite corners are aligned with the printing direction. A stencil according to claim 1, wherein the secondary holes have an open area of substantially diamond or diamond shape, and optionally, the opposite corners are aligned with the printing direction. A stencil according to claim 1, wherein the secondary holes have substantially circular open areas. A stencil according to claim 1, wherein the secondary holes have a substantially elliptical open area, and optionally the major axis of the ellipse is aligned with the printing direction. The stencil of claim 1, wherein the mesh is formed by a plurality of first elongate mesh members and a plurality of second elongate mesh members, the plurality of first elongate mesh members Arranged to be spaced apart, optionally in a substantially parallel relationship, and the plurality of second elongate mesh members are arranged in spaced, optionally substantially parallel, relationships with the first mesh The elements are in a cross relationship. A stencil as claimed in claim 23, wherein the first and second mesh members are arranged in a substantially orthogonal relationship. The stencil of claim 23, wherein the first and second mesh members each extend in opposite directions at an oblique angle to a longitudinal axis of the second printing holes, and optionally the first The angles of inclination of the second mesh element are the same. A stencil according to claim 25, wherein the inclination angles of the first and second mesh members are each from about 30 degrees to about 70 degrees, alternatively from about 35 degrees to about 65 degrees. And optionally about 45 degrees. A stencil according to claim 23, wherein the reticular elements have a width of from about 15 microns to about 100 microns, alternatively from about 15 microns to about 80 microns, alternatively from about 15 microns to About 60 microns, alternatively from about 15 microns to about 45 microns. A stencil according to claim 23, wherein the mesh members each have a pitch of from about 100 microns to about 1000 microns, alternatively from about 100 microns to about 800 microns, alternatively from about 100 microns. Up to about 600 microns, alternatively from about 100 microns to about 400 microns, alternatively from about 150 microns to about 300 microns. The stencil of claim 1, wherein the first printing apertures each have an open engagement with the individual secondary apertures of the second printing apertures. A stencil as claimed in claim 1, wherein the stencil is a sheet metal stencil, optionally electrically formed. A stencil as claimed in claim 1, wherein the stencil is formed by two layers. A stencil according to claim 31, which comprises a first layer and a second layer, the first layer providing a surface traversing the printing element, the printing element being optionally a rubber roller, and the second layer In contact with the underlying workpiece, the workpiece can optionally be a wafer. A stencil of claim 32, wherein the first layer is fabricated prior to the second layer. A stencil as claimed in claim 32, wherein the first layer is a metal layer. A stencil according to claim 32, wherein the first layer is an electroformed layer, optionally an electrically formed nickel layer. A stencil according to claim 32, wherein the first layer is a cut sheet, optionally cut by chemical etching. The stencil of claim 32, wherein the first layer has a thickness of from about 20 microns to about 100 microns, alternatively from about 30 microns to about 80 microns, alternatively from about 40 microns to about 60 microns. A stencil as claimed in claim 32, wherein the second layer is a metal layer. A stencil according to claim 32, wherein the second layer is an electroformed layer, optionally an electrically formed nickel layer. A stencil according to claim 32, wherein the second layer is a cut sheet, optionally cut by chemical etching. The stencil of claim 32, wherein the second layer has a thickness of from about 20 microns to about 100 microns, alternatively from about 30 microns to about 80 microns, alternatively from about 40 microns to about 60 microns. A screen printing method using a stencil according to any one of claims 1 to 41, wherein the first and second printed deposits in a cross-correlation are printed in a single printing operation. The method of claim 42, wherein the first tension is applied along a length of the first printing holes, and a second tension lower than the first tension is applied across a width of the first printing holes, Alternatively, the first tension is at least 1.5 times greater than the second tension. A method of making a stencil, comprising the steps of: providing a first patterned layer to a mandrel of an electroforming device; defining a hole in the first patterned layer, leaving a hole in the first patterned layer Having the material electrically form an open image on the mandrel; accumulating a first stencil material layer in the open image of the first patterned layer; providing a second patterned layer to the first patterned layer, the second pattern Size and shape of the layer Corresponding to the holes in the first patterned layer and aligned to the holes in the first patterned layer; and accumulating a second layer of stencil material in the remaining open image of the first patterned layer. The method of claim 44, wherein the first patterned layer comprises a dry film laminated to the mandrel. The method of claim 44, wherein the step of defining a hole in the first patterned layer comprises: exposing the first patterned layer, optionally using a patterned mask or directly writing It. The method of claim 44, wherein the first stencil layer is accumulated to have a thickness less than a thickness of the first patterned layer. The method of claim 44, wherein the second patterned layer comprises a dry film. The method of claim 44, wherein the second patterned layer comprises pre-patterned elements sized and shaped to correspond to the holes in the first patterned layer. The method of claim 44, wherein the second patterned layer conforms to the underlying structure of the first patterned layer and encloses the open image underneath. The method of claim 50, wherein the second patterned layer is thermally laminated to the first patterned layer, and the second patterned layer conforms to the underlying structure of the first patterned layer and is closed The open image underneath. The method of claim 44, wherein the second stencil layer is accumulated to have a thickness equal to a thickness of the first patterned layer. The method of claim 44, further comprising the step of removing the first and second patterned layers after the step of accumulating the second stencil layer.