WO2012136512A2 - Procédé de fabrication d'un écran de sérigraphie et cellule solaire fabriquée au moyen de cet écran - Google Patents

Procédé de fabrication d'un écran de sérigraphie et cellule solaire fabriquée au moyen de cet écran Download PDF

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Publication number
WO2012136512A2
WO2012136512A2 PCT/EP2012/055381 EP2012055381W WO2012136512A2 WO 2012136512 A2 WO2012136512 A2 WO 2012136512A2 EP 2012055381 W EP2012055381 W EP 2012055381W WO 2012136512 A2 WO2012136512 A2 WO 2012136512A2
Authority
WO
WIPO (PCT)
Prior art keywords
screen printing
template
angle
printing form
printed
Prior art date
Application number
PCT/EP2012/055381
Other languages
German (de)
English (en)
Other versions
WO2012136512A3 (fr
Inventor
Matthias SAUERESSIG
Renate ZAPF-GOTTWICK
Original Assignee
Universität Stuttgart
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Universität Stuttgart filed Critical Universität Stuttgart
Publication of WO2012136512A2 publication Critical patent/WO2012136512A2/fr
Publication of WO2012136512A3 publication Critical patent/WO2012136512A3/fr

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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/12—Production of screen printing forms or similar printing forms, e.g. stencils
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0224—Electrodes
    • H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
    • H01L31/022433—Particular geometry of the grid contacts
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy

Definitions

  • the invention relates to a method for producing a screen printing form, which is particularly suitable for producing particularly fine structures in front side printing on solar cells. Furthermore, the invention relates to a screen printing form produced in this way and a solar cell printed in particular on the front side.
  • the metallization is carried out at the front in industrial manufacturing mainly by means of a screen printing process, which is a low-cost technology with high throughput.
  • the structure of a solar cell on the front corresponds to an H-shaped grid with narrow fingers which direct the current collected on the cell to wider bus bars. Since the tracks on the front of the solar cell contribute to the shading and thus deteriorate the efficiency of the solar cell, the tracks should be as narrow as possible on the front, on the other hand have a good electrical conductivity.
  • a disadvantage of screen printing is the ever-increasing influence of the screen mesh, the smaller the structures become. With structures as small as 100 microns or less, so-called “mesh marking" through the mesh becomes more and more prominent. This results in a wave-shaped image both in the width, as well as in the height of the structures. As a result, there are high finger and contact resistances and unnecessary consumption of the silver conductive paste for the front-side contacting.
  • Another application problem with screen printing on the front of solar cells is the printing of contact fingers with reflective color. If the contact grid on the front of the solar cell, no light can penetrate into the solar cell at this point. However, the light incident on the grating may be redirected to the cell by multiple reflection from the grating onto the modulus glass, which requires the printing of a reflective color, such as a white color. However, the viscosity of such colors is usually very low. During screen printing, the ink runs from the existing fingers onto the free area of the solar cell and thus leads to shading losses, which reduce the efficiency of the module.
  • the invention is therefore based on the object to provide a method for producing a screen printing form, which in particular fine structures can be printed, which are particularly suitable for the front side printing of solar cells.
  • a method for producing a screen printing form which in particular fine structures can be printed, which are particularly suitable for the front side printing of solar cells.
  • uniform as possible cross-sections with a high aspect ratio especially in fine line printing should be able to be generated.
  • This object is achieved by a method for producing a screen printing form, in particular for the front side printing on solar cells, in which on the surface of a screen, first a first template structure is generated, which defines a structure to be printed, and in which subsequently on the first Template structure is generated at least one further template structure, which is aligned with the previous template structure and together forms the screen printing form.
  • a larger EOM is made possible by the generation of a two- or multi-level stencil structure.
  • part of the stencil layer which builds up on the stencil carrier, ie on the screen, and whose thickness is the difference between the screen printing plate thickness and the screen thickness.
  • EOM Emersion Over Mesh
  • a more consistent print can be achieved and mesh marking can be reduced, especially when printing fine textures.
  • a recess for a line structure of the printed image to be generated has a greater width than in a previous template structure.
  • the width may be increased by at least about 5%, in particular at least 10%, preferably by at most 30%, more preferably by at most 20%.
  • a shape of a stencil structure can be produced during fine line printing continuous lines while avoiding the mesh markings.
  • the aspect ratio can be improved.
  • a stencil structure thus produced leads to a significant improvement in the electrical conductivity of the finger pressure on the front of solar cells or to avoid the mesh markings.
  • the pressure of narrower fingers is made possible, whereby a higher aspect ratio can be achieved.
  • a line structure in a preceding and a subsequent template structure can thus be widened in a pyramid-like manner.
  • the first template structure can be generated approximately with the following steps:
  • steps (a) to (d) may be repeated with the previous template structure serving as a support for the subsequent template structure.
  • the step (c) in this case preferably comprises covering the copy layer with a film original and the exposure.
  • a capillary film is a carrier film to which a prefabricated emulsion layer is applied with a constant thickness.
  • the capillary film can be applied to the previous stencil structure, whereby sufficient adhesion can be produced by moistening or by applying a small amount of emulsion.
  • the carrier film is removed after the application.
  • the invention is solved by a method for producing a screen printing form, in particular for the front side printing on solar cells, with the following steps:
  • the thixotropy of the printing paste can be utilized, i. E. the property of liquefying under pressure. It can thus reach more paste through the opening on the substrate surface to be printed through the funnel-shaped extension on the doctor side locally.
  • the first inclination angle in the first exposure step is preferably + ot and the second inclination angle in the second exposure step is -ot. This results in a symmetrical widening of the copy layer from the pressure side to the squeegee side on both sides.
  • the inclination angle ⁇ is at least 5 °, in particular at least 10 °, preferably at least 20 °, more preferably at least 30 °.
  • the inclination angle ⁇ is at most 70 °, in particular at most 60 °, particularly preferably at most 50 °.
  • the screen printing forme produced according to the invention for the production of contacts, in particular of fingers, used on the front of solar cells.
  • particularly fine fingers with a width of less than 80 micrometers, preferably in the range of 50 to 60 micrometers, or even lower, and with high electrical conductivity and a high aspect ratio can be produced hereby.
  • a screen printing plate produced according to the invention has a screen on which a template is provided, in which a recess in the template widened or tapers on a characteristic to be printed, starting from the screen to the printing side.
  • the recess of the template may be pyramid-shaped on a feature to be printed on the pressure side. to broaden like that. This embodiment results when the screen printing stencil is made in two layers or in multiple layers.
  • a recess in the template tapers at a feature to be printed obliquely to the pressure side.
  • This embodiment results when the screen printing form is made by utilizing double exposure in different directions as described above.
  • a solar cell produced according to the invention has fingers with a finger width of at most 70 micrometers, which have an aspect ratio of height to width of at least 1: 3.
  • a solar cell can further be produced, in which the fingers are printed with a color, in particular with a reflective color.
  • the ink is essentially applied only to the surface of the fingers and that bleeding is largely avoided.
  • Figure 1 is a view of a screen printing form according to the invention
  • Figure 2 is a partial perspective view of a silicon solar cell
  • FIG. 4e
  • Figure 5 is a partial view of the contacts on the front side of a silicon solar cell according to Figure 2, wherein in the lower part a cross section through a finger is shown in enlarged form, from which the aspect ratio is visible;
  • FIG. 6a, b) shows a section through an alternative embodiment of a screen printing form with the support of a film original with an indication of two different exposure steps according to FIG. 6a) and FIG. 6b);
  • FIG. 7 shows the screen printing form according to FIG. 6 after development
  • 8 shows a finger on an associated wafer for solar cell production, which can be produced with the screen printing form according to FIG. 7, and
  • FIG. 7 shows the screen printing form according to FIG. 6 after development
  • 8 shows a finger on an associated wafer for solar cell production, which can be produced with the screen printing form according to FIG. 7, and
  • FIG. 7 shows the screen printing form according to FIG. 6 after development
  • 8 shows a finger on an associated wafer for solar cell production, which can be produced with the screen printing form according to FIG. 7, and
  • FIG. 7 shows the screen printing form according to FIG. 6 after development
  • 8 shows a finger on an associated wafer for solar cell production, which can be produced with the screen printing form according to FIG. 7, and
  • FIG. 7 shows the screen printing form according to FIG. 6 after development
  • 8 shows a finger on an associated wafer for solar cell production, which can be produced with the screen printing form according to FIG. 7, and
  • FIG. 7 shows the screen printing form according
  • Figure 9 is a view of a conventional screen printing form with a sieve and a slot-shaped opening for the production of a finger, wherein in the right half a hereby generated finger is shown, wherein the mesh marking is visible.
  • a screen printing form according to the invention is shown schematically and generally designated by numeral 10.
  • the screen printing form 10 has a screen printing frame 12, which serves to attach a screen printing stencil carrier.
  • the frame is chosen depending on the screen used, the screen tension and the print motif.
  • the size of the frame 12 depends directly on the size of the print motif. With a certain distance of usually at least 150 millimeters to the frame is the doctor blade surface 16. Within the doctor blade surface 16 finally the template 18 is recorded, which reproduces the print motif.
  • the distance between the doctor blade surface 16 and the frame 12 is also called color rest.
  • the screen 14 may be made of a fabric, such as a PET fabric or steel wire (stainless steel).
  • a fabric such as a PET fabric or steel wire (stainless steel).
  • steel fabrics are used, since this finer structures can be achieved because they work with a lower thread size and can be used with a higher fabric tension.
  • Fig. 2 is a partial perspective view of a silicon solar cell is shown, which is generally designated 20.
  • the solar cell 20 has on its front side an emitter 22 (n-type), followed by a base layer 24 (p-type) to which a rear-side contact 26 made of aluminum is applied flatly.
  • front side contacts 28 are arranged on the front side, which have a H- form a shaped structure, with two bus bars 30 parallel to each other with a larger cross-section, from which extend starting on both sides fingers 32 with a much smaller cross-section.
  • the front side contacts 28 are made of a silver alloy. They should be as small as possible to avoid shading losses, but have sufficient electrical conductivity.
  • fingers with a width of about 80 to 100 micrometers and a height of 20 to 25 micrometers can be produced with conventional screen printing forms.
  • Fig. 3 shows the various phases in the production of a screen printing form according to the invention.
  • a first template structure 34 is produced on a wire 14 in a conventional manner.
  • a UV-sensitive emulsion is applied to the wire 14 and then dried.
  • the copying layer 36 thus produced is then irradiated with UV radiation in the wavelength range from 350 to 450 nanometers with the interposition of a film original which reproduces the printed pattern.
  • the monomers combine to form long-chain polymers and the copy layer 36 loses its solubility in the sense of solvent (water).
  • the copying layer 36 thus becomes water-insoluble in the impingement region of the radiation, while the places covered by the film template, ie the image plane locations, remain water-soluble.
  • a screen printing plate produced in this way with a first conventionally produced screen printing layer 34 is shown in cross section in FIG. 3a).
  • a second template structure is subsequently applied to this first template structure 34.
  • a spacer 38 can be applied on both sides on both sides to predetermine the desired application thickness when applying an emulsion.
  • the application thickness is 60 microns.
  • UV-sensitive emulsion is again applied with a doctor blade 40, so that a second copying layer 43 results.
  • the screen printing form is then dried with the print side up in a drying oven.
  • the second copy layer 43 has a thickness of about 25 microns, as shown in Fig. 3c). Subsequently, an exposure takes place again with high-energy UV radiation with the interposition of a film original 44, which must be precisely aligned with respect to the structure previously generated in the first template structure 34.
  • the basic production corresponds to the previously explained with reference to FIG. 3 steps.
  • Fig. 4a shows a cross section through a screen printing form in which on the screen 14, a first template structure 34 has been produced in the conventional manner described above.
  • a second stencil structure 42 is applied thereto, which forms a second copying layer 43.
  • a second film original 44 is precisely aligned and subsequently exposed to UV radiation.
  • the second film original 44 is preferably designed so that it has a slightly larger width at a line-shaped recess 52 than the associated recess 50 in the first template structure 34.
  • the first recess 50 could have a width of 50 microns
  • the second Recess 52 has a width of about 60 microns, as dashed lines in Fig. 4c) and 4d) is indicated.
  • FIG. 4e shows a finger structure 48 produced with such a screen printing form 10 'on a substrate 46.
  • the result is a structure sharply defined at the edges, avoiding bleeding with a good aspect ratio.
  • a section of the front side contacting is shown schematically in the upper part, with a bus bar 30 and fingers 32 extending therefrom.
  • the fingers have a width w.
  • a cross section through one of the fingers 32 is shown enlarged.
  • the width of the finger is w, while the height is h.
  • an aspect ratio of about 0.4 can be achieved for an actual finger width of 50 micrometers. This represents a significant improvement over screen printing with conventional screen printing forms.
  • the screen printing form 10 " is produced in one stage in contrast to the previously described screen printing form.
  • a UV-sensitive emulsion is first applied in the usual way in order to produce a copying layer 36 ", followed by the usual drying step in the drying oven.
  • a first film original 44 is placed on the surface of the copy layer 36".
  • the exposure is subsequently not effected with a single exposure step with vertically incident light, but in two successive exposure steps with obliquely incident UV radiation.
  • the UV radiation is directed obliquely from the right onto the first film original 44 ", so that an angle of inclination ⁇ of approximately 45 ° results to the right with respect to the vertical , wider film original 44 "'launched (Fig. 6a)).
  • the second film original 44 "'prevents the UV radiation in the area to be developed later on the one side .
  • the incident radiation is indicated by solid lines.
  • the second film original 44 "' is shifted to the other side to prevent the incidence of radiation on the other side.”
  • the incident UV radiation is tilted at the angle -a from the vertical, ie 45 ° in the opposite direction ( Figure 6b).) Behind the film master 44 ", a V-shaped region of the master copy 36", which was not irradiated, thus results behind a recess 54 in the original film 44 ".
  • a screen printing form 10 "results as shown in FIG. 7, which has a V-shaped recess, which increases from the pressure side to the doctor side. If such a screen printing form 10 "is used in order to produce a fine structure, the thixotropic property is advantageously utilized, in particular when printing silver pastes on solar cells, in order to be able to produce particularly fine structures, since openings are formed in the area of the funnel-shaped widened opening liquefaction of the screen printing paste results, which leads to a higher material output in this area and thus enables printing of fine structures with a high aspect ratio.

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  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Electromagnetism (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Printing Methods (AREA)
  • Photovoltaic Devices (AREA)
  • Printing Plates And Materials Therefor (AREA)

Abstract

Procédé de fabrication d'un écran de sérigraphie (10) notamment pour imprimer la face avant de cellules solaires (20), selon lequel sur la surface d'une toile (14) est d'abord générée une première structure de pochoir (34) qui définit une structure à imprimer, puis sur cette première structure de pochoir (34) est générée au moins une autre structure de pochoir (42) qui est ajustée avec la première structure de pochoir (34) pour former ensemble ledit écran de sérigraphie.
PCT/EP2012/055381 2011-04-08 2012-03-27 Procédé de fabrication d'un écran de sérigraphie et cellule solaire fabriquée au moyen de cet écran WO2012136512A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102011016453.7 2011-04-08
DE201110016453 DE102011016453A1 (de) 2011-04-08 2011-04-08 Verfahren zur Herstellung einer Siebdruckform und damit hergestellte Solarzelle

Publications (2)

Publication Number Publication Date
WO2012136512A2 true WO2012136512A2 (fr) 2012-10-11
WO2012136512A3 WO2012136512A3 (fr) 2012-12-27

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PCT/EP2012/055381 WO2012136512A2 (fr) 2011-04-08 2012-03-27 Procédé de fabrication d'un écran de sérigraphie et cellule solaire fabriquée au moyen de cet écran

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DE (1) DE102011016453A1 (fr)
WO (1) WO2012136512A2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017506176A (ja) * 2014-02-20 2017-03-02 ガルス・フェルト・リュッシュ・アクチェンゲゼルシャフト スクリーン印刷ステンシル、およびその描画方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102014114362A1 (de) * 2014-10-02 2016-04-07 Hanwha Q Cells Gmbh Drucksieb für den Siebdruck einer Solarzellen-Elektrodenstruktur und Verfahren zum Siebdruck einer Solarzellen-Elektrodenstruktur mit einem solchen Drucksieb

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Publication number Priority date Publication date Assignee Title
JP2002512124A (ja) * 1998-04-21 2002-04-23 プレジデント・アンド・フェローズ・オブ・ハーバード・カレッジ エラストマ・マスク、およびピクセル化されたエレクトロルミネセンス・ディスプレイを含む装置の製造における使用
US7749883B2 (en) * 2007-09-20 2010-07-06 Fry's Metals, Inc. Electroformed stencils for solar cell front side metallization
DE102009024873A1 (de) * 2009-06-09 2010-12-16 Nb Technologies Gmbh Siebdruckform
WO2011033278A1 (fr) * 2009-09-21 2011-03-24 Dtg International Gmbh Pochoirs d'impression et leurs procédés de fabrication

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017506176A (ja) * 2014-02-20 2017-03-02 ガルス・フェルト・リュッシュ・アクチェンゲゼルシャフト スクリーン印刷ステンシル、およびその描画方法

Also Published As

Publication number Publication date
DE102011016453A1 (de) 2013-01-17
WO2012136512A3 (fr) 2012-12-27

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