CN114932751B - A device and method for ultrasonic focused jet printing of aerosol ink particles - Google Patents

Abstract

The invention discloses a device and a method for ultrasonically focusing and spray-printing aerosol ink particles, which relate to the technical field of aerosol spray-printing and comprise a piezoelectric-ultrasonic transducer, wherein a fixing ring is arranged on the outer wall of a nozzle of an aerosol spray-printing system; the radial acoustic radiation force generated by the piezoelectric-ultrasonic transducer can realize the radial focusing of aerosol ink particles. The method based on the device can adapt to the ink types in a larger range or is not limited by the ink types, ensures that the focusing method has no damage to the ink materials, realizes the quantitative focusing of aerosol ink particles, and finally realizes the effective, reliable and accurate control of the overspray problem of aerosol spray printing.

Description

A device and method for ultrasonic focused jet printing of aerosol ink particles

technical field

The invention relates to the technical field of aerosol jet printing, in particular to a device and method for ultrasonic focused jet printing of aerosol ink particles.

Background technique

Conformal electronic printing can realize the preparation of two-dimensional electronic circuits on any curved surface by means of transfer printing, direct writing and thermoforming under the premise of retaining the functions of planar electronics, so as to improve the flexibility of electronic system design and realize the miniaturization of electronic systems , lightweight, and intelligent, it is considered to be one of the innovative technologies that subvert traditional electronic manufacturing. As a new type of conformal electronic printing technology, aerosol inkjet printing technology has non-contact, high-precision printing characteristics, and can realize conformal printing and manufacturing of active and passive electronic components and sensors. The optimization research has become a research hotspot in recent years.

Due to the non-contact design of aerosol inkjet printing technology, there is a gap of 1-5mm between the nozzle and the substrate; the ink droplet diameter is extremely small, only 2-5μm; the ink particle ejection rate is extremely high, up to 80- Therefore, when the aerosol ink particles pass through the injection channel at high speed, the aerosol ink flow will drift and disperse. The drift and dispersion are uncertain, resulting in the phenomenon of "overspray". "Satellite droplets" formed by drifting dispersed ink droplet deposits appear around the deposit. The "satellite droplet" will make the planned jet printing deposition insufficient, resulting in insufficient strength and electrical properties of the printed object. In addition, the planned adjacent deposition part will be contacted and shorted due to the "satellite droplet" deposition. In summary, the "overspray" caused by the drift and dispersion of aerosol ink particles during the spraying process will lead to serious problems such as insufficient deposition quality of the printed object or insufficient electrical performance or even failure.

Reliable control of the "overspray" of aerosol jet printing is one of the key conditions for the stable preparation of high-performance, highly integrated conformal electronics by aerosol jet printing. The direct method of controlling "overspray" is to The ink particles in the process are fully focused to suppress the drift and dispersion of ink particles. At present, there are three main methods of focusing on aerosol ink flow:

Method 1, adjust the flow rate of carrier gas and sheath gas: the role of carrier gas is to transport the aerosol ink to the nozzle, and determine the distribution and movement state of aerosol ink particles before spraying; the role of sheath gas is to The aerosol ink particles are focused and ejected, so the focusing effect of the ink flow can be controlled by adjusting the flow rate of the sheath gas and the carrier gas;

Method 2. Adjust the ink channel structure inside the nozzle: the complexity of the micro-geometric structure inside the nozzle increases the uncertainty of the dispersion of ink particles in the injection channel. Adjusting the geometric structure of the ink channel inside the nozzle can realize the ink flow morphology and ink The adjustment of particle focusing degree to reduce the uncertainty of ink particle drift and dispersion during jetting;

Method 3: Apply magnetic radiation force to the magnetic metal ink particles to focus by applying an external magnetic field: set a magnetic field outside the aerosol printing system, apply magnetic radiation force to the magnetic metal ink particles, and cause the ink particles to move radially, thereby realizing ink printing. Flow focus.

Although the aerosol ink particle focusing method described above can achieve a certain degree of focusing optimization effect, there are certain disadvantages in practice. Method 1 and method 2 can only achieve qualitative focusing optimization, because of the diversity of physical properties of ink materials, the particularity and unknowns of inks selected for practical applications, and the relationship between physical properties of inks and carrier gas, sheath gas flow, and jet channel geometry The relationship between the two methods is extremely complicated, and the quantitative analysis is not clear. Therefore, it is difficult to achieve quantitative focusing of aerosol ink particles by method 1 and method 2, so it is difficult to achieve reliable and quantitative control of "overspray". Method three has a strong dependence and selectivity on the physical properties of the ink material being focused, so there are certain limitations in ink selection and printing planning based on this method in practical applications.

Contents of the invention

The object of the present invention is to provide a device and method for ultrasonic focused printing of aerosol ink particles to solve the problems in the prior art above, to adapt to a wide range of ink types or not to be limited by ink types, and to ensure that the focusing method It is non-destructive to ink materials, realizes quantitative focusing of aerosol ink particles, and finally realizes effective, reliable and precise control of the "overspray" problem of aerosol jet printing.

To achieve the above object, the present invention provides the following scheme:

The invention provides a device for ultrasonic focused spray printing of aerosol ink particles, comprising a piezoelectric-ultrasonic transducer with a fixed ring arranged on the outer wall of the nozzle of the aerosol spray printing system, and the piezoelectric-ultrasonic transducer is electrically connected to There is a power amplifier, and the power amplifier is electrically connected with a signal generator; the piezoelectric-ultrasonic transducer can construct a ring-shaped sound pressure environment, and form a radial high-frequency sound field with full horizontal coverage on the periphery of the aerosol ink particle flow, The generated radial acoustic radiation force can achieve radial focusing on the aerosol ink particles. The high-frequency sound field has the characteristics of good directionality, strong penetrability, high sensitivity, and no damage, and is one of the effective means for particle manipulation. Therefore, the present invention adopts a ring-shaped high-frequency sound field on the jet channel of the aerosol ink flow In this way, the radial ultrasonic focusing of the aerosol ink particles is fully covered in the horizontal layer.

Optionally, the piezoelectric-ultrasonic transducer is a tubular structure, and the inner diameter of the piezoelectric-ultrasonic transducer is the same as the outer diameter of the nozzle.

Optionally, the length of the piezoelectric-ultrasonic transducer is 80% of the length of the nozzle.

Optionally, the piezoelectric-ultrasonic transducer is made of ceramic piezoelectric material, while realizing the inverse piezoelectric effect, it is ensured that the generated inverse piezoelectric effect is not enough to make the piezoelectric-ultrasonic transducer Under certain conditions, resonance is generated due to the properties of the piezoelectric material, which affects the stable operation of the system; the internal electrode of the piezoelectric-ultrasonic transducer is made of sintered silver (thick film) material, and the external electrode is made of PVD film (CuNi, Au) material. The stability of the excitation input is ensured; the internal electrodes of the piezoelectric-ultrasonic transducer are made of sintered silver material, and the external electrodes of the piezoelectric-ultrasonic transducer are made of PVD film material.

Optionally, an ultrasonic coupling agent is added between the outer wall of the nozzle and the inner wall of the piezoelectric-ultrasonic transducer; the part of the outer wall of the nozzle covered with the piezoelectric-ultrasonic transducer is a focusing area, The outer side of the upper end and the outer side of the lower end of the piezoelectric-ultrasonic transducer are respectively connected to the part of the outer wall of the nozzle outside the focusing area by adhesive bonding.

Optionally, the inside of the nozzle is hollow, and the bottom of the nozzle is integrally formed with a cone-shaped spray head, and the top of the nozzle is communicated with an injection channel, and the injection channel is used to transport aerosol ink particles and carrier gas; the injection channel The outer ring is provided with a tapered sheath gas channel, and the bottom of the sheath gas channel communicates with the outer side of the nozzle top.

The present invention also provides a method for ultrasonically focused jet printing aerosol ink particles, comprising the following steps:

Step 1: Determine the degree of focus of the aerosol ink particles according to the requirements of the jet printing deposition distribution and the internal and external environment of the jet printing system;

Step 2, aiming at the degree of focus in step 1, according to the scope of the focusing area and the physical properties of the aerosol ink particles, perform force-motion analysis on the aerosol ink particles to determine the radial aggregation force of the aerosol ink particles;

Step 3, adjust the working parameters of the ultrasonic focusing transducer according to the required radial focusing force, output the high-frequency acoustic wave response corresponding to the focusing effect, and generate the acoustic radiation force required for focusing to generate aerosol ink particles during the spraying process The radial acceleration finally realizes the radial quantitative focusing of the aerosol ink particles.

Compared with the prior art, the present invention has achieved the following technical effects:

The high-frequency sound waves excited in the present invention can be aimed at the focusing requirements of jet printing, combined with the properties of the aerosol ink material and the jet printing environment, through the quantitative calculation of the force-motion analysis of the aerosol ink particles by the acoustic radiation force, and by adjusting the pressure The working condition parameters of the electro-ultrasonic transducer are accurately output to realize the quantitative focusing of the aerosol ink particles; the piezoelectric-ultrasonic response output by the focusing device of the present invention is timely, and can be adjusted according to the printing requirements, printing environment, and printing materials. change, real-time adjustment of the working condition parameters of the piezoelectric-ultrasonic transducer, and real-time adjustment of the focusing effect of the aerosol ink particles; The aerosol jet printing method can jet print ink materials within the range; the invention has no interference to the aerosol jet printing system, and has no destructive effect on the ink material of the aerosol jet printing, including physical and chemical influences.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some of the present invention. Embodiments, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

Fig. 1 is the schematic diagram of the device structure of ultrasonic focused jet printing aerosol ink particles of the present invention;

Fig. 2 is a partial cross-sectional schematic diagram of a device for ultrasonically focused spray printing of aerosol ink particles of the present invention;

Fig. 3 schematic diagram of the focusing state of aerosol ink particles of the present invention;

Fig. 4 is the structure schematic diagram of piezoelectric-ultrasonic transducer of the present invention;

Fig. 5 is the schematic diagram of the cross-sectional structure of the piezoelectric-ultrasonic transducer of the present invention;

Fig. 6 is a schematic diagram of the nozzle structure of the present invention;

Fig. 7 is a schematic diagram of the sectional structure of the nozzle of the present invention;

Fig. 8 is a schematic diagram of the integrated assembly of the piezoelectric-ultrasonic transducer and the nozzle of the present invention;

Fig. 9 is a principle diagram of the vertical section of the working state of the ultrasonic focused jet printing aerosol ink particles of the present invention;

Fig. 10 is a principle diagram of a horizontal cross-section of the working state of ultrasonic focused jet printing aerosol ink particles of the present invention;

Description of reference signs: 1-aerosol jet printing system, 2-nozzle, 3-piezoelectric-ultrasonic transducer, 4-power amplifier, 5-signal generator, 6-aerosol ink particles, 7-jet channel, 8-sheath gas channel, 9-ultrasonic couplant.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The object of the present invention is to provide a device and method for ultrasonic focused printing of aerosol ink particles to solve the problems in the prior art above, to adapt to a wide range of ink types or not to be limited by ink types, and to ensure that the focusing method It is non-destructive to ink materials, realizes quantitative focusing of aerosol ink particles, and finally realizes effective, reliable and precise control of the "overspray" problem of aerosol jet printing.

In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

The present invention provides a device for ultrasonic focused spray printing of aerosol ink particles, as shown in Figure 1, Figure 2, Figure 3, Figure 4, Figure 5, Figure 6, Figure 7, Figure 8, Figure 9 and Figure 10, comprising The fixing ring is arranged on the piezoelectric-ultrasonic transducer 3 on the outer wall of the nozzle 2 of the aerosol printing system 1, the piezoelectric-ultrasonic transducer 3 is electrically connected to a power amplifier 4, and the power amplifier 4 is electrically connected to a signal generator 5 The piezoelectric-ultrasonic transducer 3 can construct a ring-shaped sound pressure environment, and form a radial high-frequency sound field with a full coverage of the horizontal layer on the periphery of the aerosol ink particle 6 flow, and the radial sound radiation force produced can realize the aerosol ink. Radial focusing of particles 6 . The high-frequency sound field has the characteristics of good directionality, strong penetrability, high sensitivity, and no damage, and is one of the effective means for particle manipulation. In the way of high-frequency sound field, radial ultrasonic focusing is performed on the aerosol ink particles 6 with full coverage of the horizontal layer.

Specifically, the piezoelectric-ultrasonic transducer 3 has a tubular structure to realize the radial acoustic radiation force with full coverage of the horizontal layer, and realize the radial focus of the full coverage of the horizontal layer of the aerosol ink particles 6, so as to realize the full coverage of the ink flow particles. Sufficiency and uniformity of focusing, and the inner diameter of the piezoelectric-ultrasonic transducer 3 is the same as the outer diameter of the nozzle 2, so as to minimize the distance between the transducer and the aerosol ink flow and avoid the transmission of high-frequency sound wave energy Excessive attenuation during the process, and ensure the high integration of the piezoelectric-ultrasonic transducer 3 and the aerosol printing system 1 . The length of the piezoelectric-ultrasonic transducer 3 is 80% of the length of the nozzle 2. Under the condition of not adding too much load to the aerosol printing system 1, a sufficient focusing range is constructed to ensure that the aerosol ink particles In order to achieve a sufficient focusing effect, it is fully focused.

The piezoelectric-ultrasonic transducer 3 is made of ceramic piezoelectric material, and the piezoelectric-ultrasonic transducer 3 works based on the inverse piezoelectric effect of piezoelectric ceramics, involving the conversion of electrical energy and mechanical energy. According to the inverse piezoelectric effect, an electrical signal of a certain frequency can be converted into a mechanical vibration of a certain frequency, and the vibration of the vibration source propagates in the form of waves through the medium to form a sound wave of a certain frequency. The signal generator and power amplifier are used as the excitation source, and the piezoelectric-ultrasonic transducer is input with an electrical signal of ≥50Vpp with a frequency of ≥2MHz, and the intensity and distribution of the generated ultrasonic waves are adjusted by adjusting the excitation input of the electrical signal , so as to control the force acting on the particles; the internal electrode of the piezoelectric-ultrasonic transducer is made of sintered silver material, and the external electrode of the piezoelectric-ultrasonic transducer is made of PVD film material.

The inside of the nozzle 2 is hollow, and the bottom of the nozzle 2 is integrally formed with a conical spray head, and the top of the nozzle 2 is connected with a spray channel 7, which is used to transport aerosol ink particles and carrier gas; the outer ring of the spray channel 7 is provided with a tapered structure The sheath gas channel 8, the bottom of the sheath gas channel 8 communicates with the outside of the top of the nozzle 2; an ultrasonic coupling agent 9 is added between the outer wall of the nozzle 2 and the inner wall of the piezoelectric-ultrasonic transducer 3; the outer wall of the nozzle 2 is coated with a piezoelectric-ultrasonic transducer The part of the transducer 3 is the focusing area, and the inner and outer walls of the nozzle 2 part within the focusing range are parallel to the tube wall of the piezoelectric-ultrasonic transducer 3, and the length of this part is the same as that of the piezoelectric-ultrasonic transducer 3. The length corresponds to avoid refraction of high-frequency sound waves due to changes in the interface direction of the propagation medium layer during the process of passing through the channel wall, air flow layer and ink solvent, thereby avoiding changes in the focusing direction of ink particles caused by the high-frequency sound field, ensuring that the radial direction of the horizontal layer Ultrasonic focusing effect, fill the micro gap, reduce the acoustic impedance difference between the outer wall of the nozzle and the inner wall of the transducer, so as to reduce the attenuation loss of ultrasonic energy. Finally, an adhesive is used to bond the outer side of the upper and lower ends of the piezoelectric-ultrasonic transducer to the part of the outer wall of the nozzle outside the focusing area, so as to ensure a stable assembly of the two and avoid placing the bonding material in the focusing area Internally, high-frequency sound waves change direction and energy attenuation during propagation. By using the piezoelectric-ultrasonic transducer 3 designed above and the electric signal excitation, the nozzle of the aerosol printing system in conjunction with the ultrasonic focusing device, and the connection assembly between the two, the ultrasonic focusing method is used to realize the aerosol ink Radial quantitative focusing with full coverage at particle level.

The present invention also provides a method for ultrasonic focusing jet printing of aerosol ink particles, which adopts the method of ultrasonic focusing to carry out radial quantitative focusing on the full coverage of the horizontal layer of the aerosol ink particles, so as to realize the "overspray" of aerosol jet printing Reliable control, including the following steps:

First of all, according to the deposition requirements of aerosol jet printing, including the deposition line width and the distance between adjacent deposition lines, the acceptable range of "overspray" is obtained. This acceptable range means that under the premise of the effective deposition amount of jet printing, " Overspray"The maximum extent of "overspray" that does not cause contact between adjacent deposition lines. According to the acceptable range of "overspray" and the effective deposition range, the required focusing degree of the aerosol ink particles 6 in the spraying process can be obtained by analysis.

Then, based on the range of the focal area during the jetting of the aerosol ink flow, the force-motion of the aerosol ink particles during the jetting process is analyzed without focusing. The force includes the fluid drag force of the solvent and the sheath gas, and the motion includes The velocity of the ink particles in the axial direction of the channel is used to construct the movement model of the aerosol ink particles in the axial direction of the focal area, and the time for the ink particles to jet through the focal area is calculated.

Secondly, for the required degree of focus of the aerosol ink particles 6, based on the movement time of the aerosol ink particles 6 in the focus area, and according to the physical properties of the aerosol ink particles 6, including particle size and density, the aerosol ink particles 6 in The radial force-motion analysis of the focus area determines the sound field parameters required to realize the radial focus movement of the aerosol ink particles 6, including frequency, pressure node distribution, sound pressure, sound intensity, etc.

Finally, according to the relevant parameters of the focused sound field obtained from the above analysis, according to the excitation-response relationship of the piezoelectric-ultrasonic transducer 3, the excitation parameters of the signal generator 5 and the power amplifier 4 are adjusted to make the piezoelectric-ultrasonic transducer 3 The corresponding inverse piezoelectric effect is generated, the ultrasonic focusing response is output, and the radial quantitative focusing of the aerosol ink particles is fully covered in the horizontal layer.

In the description of the present invention, it should be noted that the terms "center", "top", "bottom", "left", "right", "vertical", "horizontal", "inner", "outer" etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, or in a specific orientation. construction and operation, therefore, should not be construed as limiting the invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and should not be understood as indicating or implying relative importance.

In the present invention, specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only used to help understand the method and core idea of the present invention; meanwhile, for those of ordinary skill in the art, according to the present invention The idea of the invention will have changes in the specific implementation and scope of application. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims (4)

1. A device for ultrasonic focused jet printing aerosol ink particles, characterized in that: comprising a piezoelectric-ultrasonic transducer on the nozzle outer wall of the aerosol jet printing system, the piezoelectric-ultrasonic transducer The device is electrically connected with a power amplifier, and the power amplifier is electrically connected with a signal generator; the radial acoustic radiation force generated by the piezoelectric-ultrasonic transducer can realize the radial focusing of the aerosol ink particles; the pressure The electric-ultrasonic transducer is a tubular structure, and the inner diameter of the piezoelectric-ultrasonic transducer is the same as the outer diameter of the nozzle; There is an ultrasonic coupling agent; the part of the outer wall of the nozzle covered with the piezoelectric-ultrasonic transducer is the focusing area, and the outer side of the upper end and the outer side of the lower end of the piezoelectric-ultrasonic transducer are respectively in focus with the outer wall of the nozzle. The part outside the action area is connected by adhesive bonding; the nozzle is hollow inside, and the bottom of the nozzle is integrally formed with a tapered nozzle, and the top of the nozzle is connected with a spray channel, which is used to transport aerosol ink Particles and carrier gas; the outer ring of the injection channel is provided with a sheath gas channel with a tapered structure, and the bottom of the sheath gas channel communicates with the outer side of the nozzle top. 2 . The device for ultrasonic focused jet printing of aerosol ink particles according to claim 1 , wherein the length of the piezoelectric-ultrasonic transducer is 80% of the length of the nozzle. 3. The device for ultrasonic focused spray printing of aerosol ink particles according to claim 1, characterized in that: the piezoelectric-ultrasonic transducer is made of ceramic piezoelectric material; the piezoelectric-ultrasonic transducer The internal electrodes of the piezoelectric-ultrasonic transducer are made of sintered silver material, and the external electrodes of the piezoelectric-ultrasonic transducer are made of PVD film material. 4. A method for ultrasonically focused jet printing aerosol ink particles, characterized in that: comprising the steps: Step 1: Determine the degree of focus of the aerosol ink particles according to the requirements of the jet printing deposition distribution and the internal and external environment of the jet printing system; Step 2, aiming at the degree of focus in step 1, according to the scope of the focusing area and the physical properties of the aerosol ink particles, perform force-motion analysis on the aerosol ink particles to determine the radial aggregation force of the aerosol ink particles; Step 3, adjust the working parameters of the ultrasonic focusing transducer according to the required radial focusing force, output the high-frequency acoustic wave response corresponding to the focusing effect, and generate the acoustic radiation force required for focusing to generate aerosol ink particles during the spraying process The radial acceleration finally realizes the radial quantitative focusing of the aerosol ink particles.

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