Paste dispensing device and paste dispensing method of paste dispensing device

Abstract

The present invention provides a paste dispensing device and a paste dispensing method for the paste dispensing device. The paste dispensing device includes a printing head and a pressurized paste supply unit. The printing head includes an inlet opening, an outlet opening, an inner cavity connecting the inlet opening and the outlet opening, and at least one dispensing opening, wherein the paste in the inner cavity is dispensed onto a workpiece via the at least one dispensing opening. The pressurized paste supply unit is configured to circulate the paste through the inlet opening, the inner cavity, and the outlet opening of the printing head in sequence. The paste dispensing device and method of the present invention maintain continuous paste circulation through the inner cavity of the printing head while dispensing the paste through the dispensing opening connected to the inner cavity fluid, thereby maintaining long-term effective deposition of the paste while maintaining the specific mechanical and compositional properties of the paste.

Description

Technical Field

[0001] The present invention relates to the field of dispensing pastes and more particularly to dispensing conductive pastes for use in the electronics and solar cell fields. Background Art

[0002] U.S. Patent Application Publication No. 2010 / 0139509, which is incorporated herein by reference in its entirety, teaches a screen printing head that is capable of being displaced in a first direction above a surface of a workpiece during a printing operation to print a deposit of a printing medium on the workpiece, the screen printing head comprising: a printing head assembly including a printing unit, the printing unit comprising a main body and a rotatable unit, the main body comprising a printing medium, a cavity for accommodating the printing medium when in use, and a delivery hole, the delivery hole being fluidically connected to the printing medium cavity, and the printing medium being delivered from the printing medium cavity through the delivery hole to the surface of the workpiece during use, the rotatable unit being arranged in the printing medium cavity of the main body and being capable of being rotated to displace the printing medium accommodated in the printing medium cavity; and a driving unit, the driving unit being used to rotate the rotatable unit to displace the printing medium accommodated in the printing medium cavity, wherein the driving unit is operative to rotate the rotatable unit to apply a force to the printing medium at the delivery hole in the main body along a second direction, the second direction being opposite to the first direction of displacement of the screen printing head.

[0003] U.S. Patent No. 9,616,524, which is incorporated herein by reference in its entirety, teaches a method of depositing material on a receiving substrate, the method comprising: providing a source substrate having a back surface and a front surface, the back surface carrying at least one piece of coating material; providing a receiving substrate, the receiving substrate being positioned adjacent to the source substrate and facing the coating material; and emitting light toward the front surface of the source substrate so as to remove at least one piece of coating material from the source substrate and deposit the removed at least one piece as a whole onto the receiving substrate.

[0004] U.S. Patent Application Publication No. 2017 / 013724, which is incorporated herein by reference in its entirety, teaches a device for generating a transfer printing pattern to be used in a transfer printing process. The pattern is produced in a substrate that can be a thin sheet substrate and carries one or more grooves. The filler to be transferred is made to fill the grooves in the thin sheet substrate. At the end of filling the grooves with the filler, the substrate, the scraper and the rubber brush are translated from the working area with synchronous motion so that at least the scraper remains in full contact with the substrate during the translational motion.

[0005] The article Pattern Transfer Printing (PTP) by Lossen et al. (2015), 5th Symposium on Metallization of Crystalline Silicon Solar Cells, Energy Procedia, 67:156-162, is incorporated herein by reference in its entirety. TM )for c-Si solar cell metallization (pattern transfer printing (PTP) for c-Si solar cell metallization TM )) teaches pattern transfer printing (PTP) as a non-contact printing technique for advanced front side metallization of c-Si PV solar cells TM ), the pattern transfer printing (PTP TM ) is based on laser induced deposition from a polymer substrate.

[0006] However, there is a challenge in maintaining effective deposition of metal paste fillers over a long period of time while preserving the specific mechanical and compositional properties of the metal paste. Summary of the invention

[0007] The following is a simplified summary to provide an initial understanding of the invention. This summary does not necessarily indicate key elements of the invention, nor does it necessarily limit the scope of the invention, but merely serves as an introduction to the following description.

[0008] One aspect of the present invention provides a paste dispensing device, comprising: a printing head, the printing head comprising an inlet opening, an outlet opening, an inner cavity connecting the inlet opening and the outlet opening, and at least one dispensing opening, wherein the paste in the inner cavity is dispensed onto a workpiece via the at least one dispensing opening; and a pressurized paste supply unit, the pressurized paste supply unit being configured to circulate the paste through the inlet opening, the inner cavity and the outlet opening of the printing head in sequence.

[0009] Another aspect of the present invention provides a paste dispensing method, wherein the paste dispensing device comprises a printing head and a pressurized paste supply unit, the printing head comprises an inlet opening, an outlet opening, an inner cavity communicating with the inlet opening and the outlet opening, and at least one dispensing opening. The paste dispensing method comprises: circulating the paste sequentially through the inlet opening, the inner cavity, and the outlet opening of the printing head by the pressurized paste supply unit; and dispensing the paste in the inner cavity onto a workpiece via the at least one dispensing opening.

[0010] In certain embodiments, maintaining continuous circulation of the paste through the print head ensures continuous and efficient mixing of the metal paste, thereby ensuring specific mechanical and compositional properties of the metal paste, and preventing the paste from accumulating and remaining within the print head.

[0011] These, additional, and / or other aspects and / or advantages of the invention are set forth in the detailed description which follows; may be inferred from the detailed description; and / or may be learned by practice of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] For a better understanding of embodiments of the invention and to show how the invention may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings in which like reference numerals refer to corresponding elements or sections throughout.

[0013] In the attached picture:

[0014] Figures 1A to 1C , FIG. 2A to FIG. 2C and Figure 3 is a high level illustration of a paste dispensing device according to various embodiments of the present invention.

[0015] Figure 4 is a high level flow chart illustrating a paste dispensing method according to some embodiments of the present invention.

[0016] It should be understood that, for simplicity and clarity of illustration, the elements shown in the drawings are not necessarily drawn to scale. For example, for clarity, the size of some of the elements may be exaggerated relative to other elements. In addition, reference numerals may be repeated between the drawings to indicate corresponding or similar elements where deemed appropriate. DETAILED DESCRIPTION

[0017] In the following description, various aspects of the present invention are described. For the purpose of explanation, specific configurations and details are set forth to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be practiced without the specific details presented herein. In addition, known features may have been omitted or simplified so as not to confuse the present invention. With specific reference to the accompanying drawings, it should be emphasized that the details shown are only examples and are only for the purpose of illustrative discussion of the present invention, and the details shown are presented to provide what is considered to be the most useful and most understandable content for the principles and concepts of the present invention. In this regard, no attempt is made to show the structural details of the present invention in more detail than is necessary for a basic understanding of the present invention, and the description in conjunction with the accompanying drawings makes it clear to those skilled in the art how several forms of the present invention can be embodied in practice.

[0018] Before explaining at least one embodiment of the present invention in detail, it should be understood that the present invention is not limited in its application to the details of the configurations described in the following description or illustrated in the accompanying drawings and the arrangement of parts. The present invention can be applied to other embodiments and combinations of disclosed embodiments that can be practiced or performed in various ways. In addition, it should be understood that the words and terms used herein are for descriptive purposes and should not be considered restrictive.

[0019] Embodiments of the present invention provide efficient and economical methods and mechanisms for dispensing thick metal pastes, and thereby provide improvements in the technical field of printed electronic circuits. A paste dispensing apparatus and method are provided, which maintain the paste continuously circulating through the supply openings and inner cavity of a print head while dispensing the paste through one or more dispensing openings that are in fluid communication with the inner cavity. A pressurized paste supply unit circulates the paste through the print head, and the pressure in the supply unit is adjusted to maintain the continuous circulation of the paste through the supply openings and the inner cavity and to control the dispensing of the paste through the dispensing openings. For example, the paste can be delivered to the print head via an inlet opening, and the pressurized paste in a controllable manner can be added to the paste leaving the print head.

[0020] The disclosed paste dispensing can be used to print thin lines formed from thick metal pastes to produce electronic circuits, for example, to produce conductive lines or pads or other features on laminates for PCBs or other printed electronic boards or on silicon wafers, for example, for photovoltaic (PV) cells. Other applications can include producing conductive features in the manufacture of mobile phone antennas, decorative and functional automotive glass, semiconductor integrated circuits (ICs), semiconductor (IC) packaging connections, printed circuit boards (PCBs), PCB component assemblies, optical biological, chemical and environmental sensors and detectors, radio frequency identification (RFID) antennas, organic light emitting diode (OLED) displays (passive or active matrix), OLED lighting sheets, printed batteries and other applications.

[0021] Specifically, the disclosed paste dispensing apparatus and method ensure stable and uniform dispensing of high-viscosity pastes during long-term operation by: continuously recirculating the paste inside the dispensing head, for example, to prevent the paste material from accumulating anywhere within the printing head or related components; mixing the paste during circulation to ensure continuous adjustment of the paste composition, for example, to keep the components of the paste well mixed and to keep the volatile organic components in the paste uniform - thereby preventing the paste from drying out and breaking.

[0022] Advantageously, compared with the dispensing methods of the prior art, the evaporation of organic paste components (such as in the scraper (scraper) type dispensing devices of the prior art) and the resulting deterioration of the thixotropy (paste rheology) of the paste are avoided; and the changes in the composition of the paste such as segregation between paste compounds caused by excessive pressurization (such as in the non-circulating devices of the prior art) are prevented - thereby obtaining a uniform paste composition and therefore a stable printing quality.

[0023] For example, the disclosed paste dispensing apparatus and method can be used to generate a transfer pattern to be used in a transfer printing process, for example by depositing the paste into grooves of a substrate sheet and using the transferred pattern, for example, in a roll-to-roll manufacturing process (see, for example, Lossen et al., 2015).

[0024] Figures 1A to 1C , FIG. 2A to FIG. 2C and Figure 3 is a high level illustration of a paste dispensing device 100 according to various embodiments of the present invention. Figure 1A , Figure 1B and Figure 1C are a side view, a bottom perspective view, and a side cross-sectional view of some embodiments of the paste dispensing device 100, respectively; Figure 2A , Figure 2B and Figure 2C are, respectively, a perspective view, a bottom perspective view, and a perspective view with illustrated paste movement of some embodiments of the paste dispensing device 100; and Figure 3 is a cross-sectional side view of some embodiments of the paste dispensing device 100 with illustrated movement of the paste. Figures 1A to 1C , FIG. 2A to FIG. 2C and Figure 3 The elements of the present invention may be combined in any operable combination and the fact that certain elements are shown in certain drawings and not in other drawings is for illustrative purposes only and is non-limiting.

[0025] The paste dispensing device 100 comprises a print head 150, the print head 150 comprising at least two supply openings 161, 169, an inner cavity 165 and at least one dispensing opening 160 and a pressurized paste supply unit 105, wherein the at least two supply openings 161, 169, the inner cavity 165 and the at least one dispensing opening 160 are in fluid communication (see, for example, Figure 1C , Figure 2C and Figure 3 ), the pressurized paste supply unit 105 is configured to circulate the paste 90 through the print head 150. The pressurized paste supply unit (see, for example, Figure 1C , Figure 2C and Figure 3) is adjusted to keep the paste continuously circulating through the supply openings 161, 169 and the inner cavity 165 and to control the dispensing of the paste through the dispensing opening 160. For example, the pressurized paste supply unit 105 may include a paste pump 110 and a pressurized paste reservoir 120 in fluid communication with the inner cavity 165 of the print head 150, the pressurized paste reservoir 120 and the paste pump 110 being configured to circulate the paste through the inner cavity 165 of the print head 150. In a non-limiting example, the paste pump 110 may include a rotary pressure-sealed displacement system with a self-sealing rotor / stator design for dispensing precise volumes, such as from Dymax TM eco-PEN450 TM .

[0026] In various embodiments, the paste dispensing device 100 includes at least one pressure sensor 140 configured to measure the pressure of the circulating paste. As a non-limiting example, the at least one pressure sensor 140 is, for example, Figures 1A to 1C The pressure sensor 140 schematically shown in FIG. 1 and associated with the paste mixer 130 is either FIG. 2A to FIG. 2C and Figure 3 Schematically illustrated in FIG. 1 , pressure sensors 140A, 140B are located at either end of the print head 150. Alternatively or additionally, the pressure measurement may be implemented in an element of the pressurized paste supply unit 105, such as the paste pump 110 and / or the paste reservoir 120. The paste dispensing device 100 may also include (at Figure 1C and Figure 2C ) at least one controller 170, which is schematically shown in the figure, and the at least one controller 170 is configured to adjust the pressure in the pressurized paste supply unit 105 (or a component of the pressurized paste supply unit 105) relative to the measured pressure of the circulating paste. The paste dispensing device 100 may also include one or more paste mixers 130 configured to mix the circulating paste. The paste mixer 130 can be, for example, a static mixer that mixes the paste by pressurizing it. In a non-limiting example, the paste mixer 130 can include a plastic disposable static mixer made of a large diameter plastic shell containing a plurality of mixing elements, such as from Stamixco TM GXF-10-2-ME TM .

[0027] The pressurized paste supply unit 105 may also be configured to introduce the paste into the inner cavity 165 via at least one inlet opening 161 of the at least two supply openings and receive the circulating paste via at least one outlet opening 169 of the supply opening in the print head 150. Typically, the inlet opening 161 and the outlet opening 169 are located at the top of the print head 150 opposite to the dispensing opening 160, which faces the substrate onto which the paste is deposited. Alternatively or additionally, the inlet opening 161 and / or the outlet opening 169 may be located on the side and / or extension of the print head 150.

[0028] The pressurized paste supply unit 105 may include a pressure-controlled paste reservoir 120, a paste pump 110, and a mixer 130 in fluid communication. The pressure-controlled paste reservoir 120 may be configured to deliver the paste to the paste pump 110, and the paste pump 110 may be configured to deliver the paste to the inlet opening 161 through the mixer 130. The pressurized paste supply unit 105 may also be configured to mix the paste from the outlet opening 169 with the paste delivered from the pressure-controlled paste reservoir 120 to the paste pump 110. The outlet of the pressure-controlled paste reservoir 120 is in fluid communication with the inlet of the paste pump 110. For example, Figure 2C and Figure 3 , paste 90 in paste reservoir 120 may be delivered (91) to paste pump 110 to be mixed (92) with paste 97 exiting outlet opening 169 of print head 150 to be pumped by paste pump 110 into mixer 130. Paste 93 from mixer 130 may be delivered (94) to inlet opening 161 of print head 150, wherein paste 96 moves along inner cavity 165 and some paste 95 may be dispensed through dispensing opening 160 to form a pattern such as lines on a substrate (for a non-limiting example, see, e.g., Lossen et al., 2015, for forming silver lines having a width of about 20 μm on a silicon wafer for PV cells). The remaining paste 97 is then mixed with the paste 91 from the paste reservoir 120 (e.g., the paste 91 delivered through the nozzle 122 at the joint 112) to compensate for the amount dispensed, and the paste is circulated through the paste dispensing device 100 to maintain the mechanical properties of the paste and to support the continuous mixing of the paste so as to maintain the chemical composition of the paste. In some embodiments, the paste dispensing device 100 can also be configured to change the paste composition, such as by adding additives such as solvents, to make the paste uniform, possibly in conjunction with monitoring pressure throughout the paste dispensing device 100. For example, additives such as solvents can be added to the paste entering the mixer 130 if necessary.

[0029] In various embodiments, the print head 150, the inner cavity 165, and the dispensing slit as the opening 160 limited by the slit edge 162 (eg, the metal slit lip 162) can be elongated (eg, see Figure 1B and Figure 2B ) and is configured for paste properties (e.g., viscosity values), a specific throughput, and specific features (e.g., length, width, and optional cross-section) of lines or other elements to be dispensed by print head 150. In certain embodiments, dispensing opening 160 may include one or more slits, one or more openings, a plurality of linearly arranged openings, one or more lines of, for example, circular or elliptical openings, and the like.

[0030] In various embodiments, the paste material may include a conductive silver-based metal paste and may generally have a high viscosity (e.g., a viscosity in the range of tens of Pa·s to hundreds of Pa·s). In non-limiting solar applications, the metal paste may, for example, include metal powder, optional glass powder and modifiers, volatile solvents, and non-volatile polymers and / or resins. Non-limiting examples of pastes include those from Heraeus TM SOL9651B TM .

[0031] The paste dispensing device 100 may include one or more pressure sensors 140, 140A, 140B configured to measure the pressure of the circulating paste at one or more corresponding locations along the paste circulation path. The pressure sensors 140, 140A, 140B may be, for example, disposed: adjacent to the inlet opening 161, the outlet opening 169; in fluid communication with the inner cavity 165 of the print head 150; and / or associated with any of the mixer 130, the paste reservoir 120, and / or the paste pump 110. Pressure-related indications from the pressurized paste reservoir 120 and / or the paste pump 110 may also be used to monitor the circulation of the paste through the paste dispensing device 100 and / or to monitor and possibly modify paste properties such as the viscosity of the paste, for example by adding solvent. The paste dispensing device 100 may also include at least one controller 170 (e.g., such as at least one controller 170 in communication with any of the components of the paste dispensing device 100 via a communication link), the at least one controller 170 being configured to adjust the pressure in the pressure-controlled paste reservoir 120 and / or the paste pump 110 relative to the measured pressure of the circulating paste, such as received from one or more pressure sensors 140, 140A, 140B. In a non-limiting example, any of the pressure sensors 140 may include, for example, a low-profile, media-compatible piezoresistive silicon pressure sensor encapsulated in a stainless steel housing (e.g., from TEconnection TM MEAS 86A TMor equivalent sensor).

[0032] In various embodiments, the pressure-controlled paste reservoir 120 and the paste pump 110 may open adjacent to the outlet opening 169 of the print head 150, and the paste dispensing device 100 may include a conduit 135 connecting the outlet of the mixer 130 to the inlet opening 161 of the print head 150 (see, for example, FIG. 2A to FIG. 2C and Figure 3 In some embodiments, the pressure-controlled paste reservoir 120 and the paste pump 110 may be open adjacent to the outlet opening 169 of the print head 150, the mixer 130 may be adjacent to the inlet opening 161 of the print head 150, and the conduit 133 may connect the paste pump 110 to the mixer 130. The pressure sensor 140 may be associated with the mixer 130 (see, for example, Figures 1A to 1C The size and orientation of the paste reservoir 120 and the paste pump 110 may vary, for example, both the paste reservoir 120 and the paste pump 110 may be positioned perpendicular to the print head 150 (see, for example, FIG. 2A to FIG. 2C and Figure 3 ), or one or both of the paste reservoir 120 and the paste pump 110 may be set to form an angle with the print head 150. For example, the paste pump 110 may be set to be tilted to distribute the weight of the paste pump 110 more evenly on the print head 150, such as Figures 1A to 1C Schematic diagram of the diagram.

[0033] In various embodiments, the conduit can be adjusted to accommodate any arrangement of the paste reservoir 120, the paste pump 110, and the mixer 130 to make the paste dispensing device 100 more compact or to adjust the paste dispensing device 100 to meet given space and weight distribution requirements within a printing press. FIG. 2A to FIG. 2C ), the holder 145 serves as an attachment element for attaching the paste dispensing device 100 to a printer (for a non-limiting example, see, e.g., U.S. Patent No. 9,616,524). In a non-limiting example, the conduit 135 can be connected between the opening (outlet) 131 in the mixer 130 and the opening 138 of the connector 137 located at the inlet opening 161 in the print head 150 (for example, see Figure 2A ), or the conduit 133 may be connected between the opening (outlet) 132 in the paste pump 110 and the opening (inlet) 134 in the mixer 130 (see, for example, Figure 1A A paste pump, wherein the mixer is attached to the connector 137 at the inlet opening 161 of the print head 150).

[0034] Figure 4is a high-level flow chart illustrating a paste dispensing method 200 according to some embodiments of the present invention. The stages of the method may be implemented with respect to the paste dispensing device 100 described above, which may optionally be configured to implement the method 200. The method 200 may include the following stages, regardless of the order of the stages.

[0035] The paste dispensing method 200 may include maintaining a continuous paste circulation through an inner cavity of a print head having at least one dispensing opening in fluid communication with the inner cavity (stage 210). The paste dispensing method 200 may also include mixing the paste during the continuous paste circulation (stage 220).

[0036] In certain embodiments, the paste dispensing method 200 may include pressurizing the paste in an adjustable manner to maintain paste circulation and control dispensing of the paste through the dispensing opening (stage 230); possibly by measuring the paste pressure and regulating the pressure (stage 232), respectively.

[0037] In certain embodiments, the paste dispensing method 200 may include mixing the paste exiting the internal cavity of the print head with the pressurized paste to compensate for the paste dispensed through the dispensing opening (stage 240).

[0038] In the above description, an embodiment is an example or implementation of the present invention. The various occurrences of "an embodiment", "an embodiment", "certain embodiments" or "some embodiments" do not necessarily all refer to the same embodiment. Although the various features of the present invention can be described in the context of a single embodiment, these features can also be provided separately or in any suitable combination. On the contrary, although the present invention can be described in the context of separate embodiments herein for the sake of clarity, the present invention can also be implemented in a single embodiment. Certain embodiments of the present invention may include features from different embodiments disclosed above, and certain embodiments may include elements from other embodiments disclosed above. The disclosure of the elements of the present invention in the context of a specific embodiment should not be considered to limit the use of these elements to only that specific embodiment. In addition, it should be understood that the present invention can be implemented or practiced in various ways, and the present invention can be implemented in certain embodiments other than the embodiments outlined in the above description.

[0039] The present invention is not limited to those drawings or corresponding descriptions. For example, the process does not need to run through each illustrated frame or state or to proceed in the same order as the illustrated and described order. Unless otherwise defined, the meaning of the technical and scientific terms used herein should be generally understood by those of ordinary skill in the art to which the present invention belongs. Although the present invention has been described with respect to a limited number of embodiments, these embodiments should not be interpreted as limitations on the scope of the present invention, but should be interpreted as examples of some preferred embodiments. Other possible variations, modifications and applications are also within the scope of the present invention. Therefore, the scope of the present invention should not be limited by what has been described so far, but should be limited by the attached claims and their legal equivalents.

Claims

1. A paste dispensing device, comprising: A printing head, the printing head comprising an inlet opening, an outlet opening, an inner cavity communicating with the inlet opening and the outlet opening, and at least one dispensing slit, wherein the paste in the inner cavity is dispensed onto a workpiece via the at least one dispensing slit; and a pressurized paste supply unit configured to circulate paste sequentially through the inlet opening, the inner cavity and the outlet opening of the print head, wherein the pressure in the pressurized paste supply unit is adjusted to maintain continuous circulation of the paste through the inlet opening, the inner cavity and the outlet opening and to control dispensing of the paste through the at least one dispensing slit, Wherein, the paste is a high-viscosity metal paste, wherein the at least one dispensing slit is configured to dispense the high-viscosity metal paste to form at least one corresponding paste line on the surface of the workpiece, The pressurized paste supply unit comprises a pressure-controlled paste reservoir and a paste pump, the inlet of the paste pump is fluidically connected to the outlet of the pressure-controlled paste reservoir to pump the paste from the pressure-controlled paste reservoir into the inner cavity of the printing head, and The inlet of the paste pump is fluidically connected to the outlet opening to deliver the paste in the inner cavity to the paste pump.

2. The paste dispensing device according to claim 1, wherein: The pressurized paste supply unit is further configured to be able to adjust the pressure of the paste in the inner cavity.

3. The paste dispensing device of claim 2, further comprising at least one pressure sensor configured to provide a signal indicative of a pressure of the paste in the inner cavity.

4. The paste dispensing device according to claim 3, further comprising at least one controller configured to control the pressurized paste supply unit to adjust the pressure of the paste in the inner cavity based on a signal of the at least one pressure sensor.

5. The paste dispensing device according to any one of claims 1 to 4, wherein: The pressurized paste supply unit further includes at least one mixer fluidly connecting an outlet of the paste pump to an inlet opening of the print head, the at least one mixer being configured to mix the circulating paste.

6. The paste dispensing device according to claim 3, wherein: The at least one pressure sensor is arranged adjacent to the inlet opening and / or the outlet opening.

7. The paste dispensing device according to claim 5, wherein: The mixer is a static mixer that mixes the paste by applying pressure.

8. The paste dispensing device of claim 5, further comprising a first conduit to connect the outlet of the mixer to the inlet opening.

9. The paste dispensing device according to claim 5, wherein: A second conduit is also included to connect the paste pump to the mixer.

10. The paste dispensing device of claim 5, further comprising a pressure sensor associated with the mixer.

11. A paste dispensing method of a paste dispensing device, wherein: The paste dispensing device comprises a printing head and a pressurized paste supply unit, wherein the printing head comprises an inlet opening, an outlet opening, an inner cavity communicating with the inlet opening and the outlet opening, and at least one dispensing slit, and the pressurized paste supply unit comprises a pressure-controlled paste reservoir and a paste pump, wherein the inlet of the paste pump is in fluid communication with the outlet of the pressure-controlled paste reservoir, and the inlet of the paste pump is in fluid communication with the outlet opening, The paste dispensing method comprises: circulate the paste sequentially through the inlet opening, the inner cavity and the outlet opening of the print head by means of the pressurized paste supply unit, wherein the pressure in the pressurized paste supply unit is adjusted to maintain continuous circulation of the paste through the inlet opening, the inner cavity and the outlet opening and to control dispensing of the paste through the at least one dispensing slit; dispensing the paste in the inner cavity onto a workpiece via the at least one dispensing slit to form at least one corresponding paste line on a surface of the workpiece; and delivering the paste leaving the inner cavity from the outlet opening to the paste pump so that the paste leaving the inner cavity from the outlet opening is mixed with the paste delivered from the pressure-controlled paste reservoir to the paste pump, Wherein, the paste is a high-viscosity metal paste. 12 . The paste dispensing method according to claim 11 , further comprising adjusting the pressure of the paste in the inner cavity by the pressurized paste supply unit.

13. The paste dispensing method according to claim 12, further comprising providing a signal representing the pressure of the paste in the inner cavity by at least one pressure sensor, in, The pressurized paste supply unit is controlled based on a signal of the at least one pressure sensor to adjust the pressure of the paste in the inner cavity.

14. The paste dispensing method according to any one of claims 11 to 13 further includes pumping the paste leaving the inner cavity of the print head and the paste supplied by the pressure-controlled paste reservoir into at least one mixer via the paste pump for mixing to compensate for the paste dispensed through the at least one dispensing slit.

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