EHD dispensing device and EHD dispensing method

Abstract

The invention discloses an EHD dispensing device and an EHD dispensing method. The EHD dispensing device comprises a voltage output device, a dispensing needle and a workpiece to be dispensed; the dispensing needle is used for dispensing the to-be-dispensed workpiece; the voltage output device comprises a first voltage output end and a second voltage output end, the first voltage output end is used for outputting a first voltage signal, and the second voltage output end is used for outputting a second voltage signal; the first voltage output end is electrically connected with the dispensing needle, and the second output end is electrically connected with a workpiece to be dispensed; the first voltage signal is smaller than the second voltage signal, and the second voltage signal is larger than zero, so that a uniform electric field can be formed at each position of the surface of the to-be-dispensed workpiece, the stability of the electric field can be ensured when the dispensing needle moves, and the stability and accuracy of glue dropping can be ensured; the dispensing position can be accurate under the large dispensing distance, the glue line after dispensing is uniform, and the dispensing effect can be effectively improved on the basis of ensuring safe operation.

Description

Technical Field

[0001] The present invention relates to the technical field of glue dispensing, and in particular to an EHD glue dispensing device and an EHD glue dispensing method. Background Art

[0002] The current electrohydrodynamic (EHD) dispensing technology is an industrial application technology that uses electric fields to control fluid flow to achieve high-precision dispensing. It is widely used in the fields of electronics, optoelectronics and medical device manufacturing, and can meet the precise dispensing needs of precision components, improve production efficiency and product quality. In EHD dispensing, the dispensing height is a crucial parameter, which directly affects the accuracy, stability and consistency of dispensing. The dispensing height determines the state of contact between the glue and the substrate after it flows out of the needle.

[0003] At present, a positive voltage is usually applied to the dispensing needle to ground the workpiece to be dispensed. And the EHD dispensing height is usually a small pitch between tens of microns and hundreds of microns, which makes the distribution and control of the electric field relatively easy. However, at this dispensing height, the needle will easily interfere with the more complex circuit board substrate, thereby affecting the dispensing effect and even causing damage to the circuit board. If the dispensing height is too high, the uniformity of the electric field becomes difficult to guarantee, resulting in inaccurate dispensing position, poor accuracy and consistency of the glue line, and prone to problems such as uneven glue line size and large landing point deviation, and even possible defects such as glue drawing and tailing.

[0004] At larger dispensing distances, the dispensing needle requires a higher voltage to maintain the stability and accuracy of the droplets. However, high voltage may bring safety risks and may also cause technical difficulties such as equipment loss and insulation problems. Due to many factors, it is difficult to achieve large-distance dispensing. Summary of the invention

[0005] The present invention provides an EHD dispensing device and an EHD dispensing method, which can achieve stable and accurate large-spacing dispensing while ensuring safe operation.

[0006] According to one aspect of the present invention, an EHD dispensing device is provided, comprising: a voltage output device, a dispensing needle and a workpiece to be dispensed; the dispensing needle dispenses glue to the workpiece to be dispensed;

[0007] The voltage output device comprises a first voltage output terminal and a second voltage output terminal, the first voltage output terminal is used to output a first voltage signal, and the second voltage output terminal is used to output a second voltage signal;

[0008] The first voltage output end is electrically connected to the glue dispensing needle, and the second voltage output end is electrically connected to the workpiece to be glued;

[0009] The first voltage signal is smaller than the second voltage signal, and the second voltage signal is greater than zero.

[0010] Optionally, the first voltage signal is less than or equal to zero.

[0011] Optionally, the voltage output device includes: a signal generator and a voltage amplifier;

[0012] The input end of the voltage amplifier is electrically connected to the signal generator, the first voltage output end of the voltage amplifier is electrically connected to the glue dispensing needle, and the second voltage output end of the voltage amplifier is electrically connected to the workpiece to be glued.

[0013] Optionally, the EHD dispensing device further includes: an oscilloscope;

[0014] The oscilloscope is electrically connected to the signal collection end of the voltage amplifier.

[0015] Optionally, the second voltage signal is U2; 0<U2≤5kV.

[0016] Optionally, the EHD dispensing device further includes: a controller;

[0017] The controller is electrically connected to the voltage output device, and the controller is used to control the first voltage signal and / or the second voltage signal output by the voltage output device according to the dispensing distance between the dispensing needle and the workpiece to be dispensed.

[0018] Optionally, the EHD dispensing device further includes: a dispensing head assembly, the dispensing head assembly at least including the dispensing needle;

[0019] The controller is also connected to the glue dispensing head assembly and is used to control the movement of the glue dispensing head assembly.

[0020] According to another aspect of the present invention, there is provided an EHD dispensing method, comprising:

[0021] Outputting a first voltage signal to the dispensing needle;

[0022] Outputting a second voltage signal to the workpiece to be dispensed;

[0023] The first voltage signal is smaller than the second voltage signal, and the second voltage signal is greater than zero.

[0024] Optionally, the first voltage signal is less than or equal to zero.

[0025] Optionally, the EHD dispensing method further includes:

[0026] Obtaining the dispensing distance between the dispensing needle and the workpiece to be dispensed;

[0027] The first voltage signal and / or the second voltage signal is controlled according to the dispensing distance.

[0028] The EHD dispensing device provided by the present invention provides a voltage signal to a dispensing needle and a workpiece to be dispensed with glue by setting a voltage output device, and sets a first voltage signal applied to the dispensing needle to be smaller than a second voltage signal provided to the workpiece to be dispensed with glue, and sets the second voltage signal to be larger than the first voltage signal, and the second voltage signal is larger than zero, so that a uniform electric field can be formed at each position on the surface of the workpiece to be dispensed with glue, so that the stability of the electric field can be ensured when the dispensing needle moves, so that the force applied to the glue by the dispensing needle at each position on the surface of the workpiece to be dispensed with glue is relatively consistent, and the stability and accuracy of the glue dripping can be ensured, so that the glue in the dispensing needle can be accurately dripped onto the surface of the workpiece to be dispensed under the joint action of the electric field force and the air pressure, and on the basis of ensuring safe operation, the dispensing position can be accurate and the glue line after dispensing can be uniform, so as to achieve stable and accurate large-spacing dispensing, and effectively improve the dispensing effect.

[0029] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0031] Figure 1 is a structural schematic diagram of an EHD dispensing device provided by an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the force analysis of the glue at the dispensing needle;

[0033] Figure 3 is a structural schematic diagram of another EHD dispensing device provided by an embodiment of the present invention;

[0034] Figure 4 is a structural schematic diagram of another EHD dispensing device provided by an embodiment of the present invention;

[0035] Figure 5 is a structural schematic diagram of another EHD dispensing device provided by an embodiment of the present invention;

[0036] Figure 6is a structural schematic diagram of another EHD dispensing device provided by an embodiment of the present invention;

[0037] Figure 7 is a flow chart of an EHD dispensing method provided by an embodiment of the present invention;

[0038] Figure 8 It is a flow chart of another EHD dispensing method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0040] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0041] Figure 1 is a schematic diagram of the structure of an EHD dispensing device provided by an embodiment of the present invention, such as Figure 1 As shown, the EHD dispensing device includes: a voltage output device 1, a dispensing needle 2 and a workpiece to be dispensed 3; the dispensing needle 2 dispenses glue to the workpiece to be dispensed; the voltage output device 1 includes a first voltage output terminal e1 and a second voltage output terminal e2, the first voltage output terminal e1 is used to output a first voltage signal, and the second voltage output terminal e2 is used to output a second voltage signal; the first voltage output terminal e1 is electrically connected to the dispensing needle 2, and the second voltage output terminal e2 is electrically connected to the workpiece to be dispensed 3; the first voltage signal is less than the second voltage signal, and the second voltage signal is greater than zero.

[0042] In some embodiments, the workpiece 3 to be glued may be a circuit board. The glue dispensing needle 2 is located directly above the workpiece 3 to be glued so as to drip glue onto the workpiece 3 to be glued. The second voltage output terminal e2 of the voltage output device 1 is electrically connected to the workpiece 3 to be glued, and the second voltage signal is greater than zero, so that a uniform electric field can be formed at each position on the surface of the workpiece 3 to be glued. The first output terminal e1 of the voltage output device 1 is electrically connected to the glue dispensing needle 2, and the first voltage signal is set to be less than the second voltage signal, so that the electric potential of the glue dispensing needle 2 is less than the electric potential at the position of the workpiece 3 to be glued, so that the glue in the glue dispensing needle 2 can accurately drip glue onto the surface of the workpiece 3 to be glued under the combined action of the electric field force and the air pressure. On this basis, since a positive voltage is applied to the workpiece 3 to be glued, a uniform electric field can be formed at each position on the surface of the workpiece 3 to be glued, and the movement of the glue dispensing needle 2 will not cause uneven changes in the electric field, so that when the glue dispensing needle 2 is at each position on the surface of the workpiece 3 to be glued, the force applied to the glue can be relatively consistent, which can ensure the stability and accuracy of the glue droplets, make the glue dispensing position accurate and the glue line after dispensing uniform, thereby effectively improving the glue dispensing effect.

[0043] Exemplarily, the first voltage signal is less than or equal to zero. Assuming that the first voltage signal is U1, in some embodiments, -5kV≤U1≤0, that is, a negative voltage or a ground voltage is applied to the dispensing needle 2, and the surface of the dispensing needle 2 is polarized with negative charge, so that the glue in the dispensing needle 2 accumulates negative charge. Figure 2 This is a schematic diagram of the force analysis of the glue at the dispensing needle. Figure 2 As shown, due to the existence of the electric field gradient in the printing space, when the dispensing needle 2 is dispensing, the negative charge accumulated in the glue A0 will move from the area with high potential to the area with low potential, and the surface tension F1 and viscosity F2 of the glue A0 repel each other with the electrostatic force (normal electric field force F3 and tangential electric field force F4), so that tangential stress is generated on the surface of the glue A0 during the charge migration process, resulting in the deformation of the meniscus on the surface of the glue A0. And the negative charge of the glue A0 is mainly concentrated at the vertex position close to the workpiece 3 to be dispensed, resulting in the formation of a Taylor cone. Finally, when the electrostatic force exceeds the surface tension F1 and viscosity F2, under the joint action of the air pressure F5, the charged glue A0 will be ejected from the cone in the form of a jet, forming a fine jet, so that the workpiece 3 to be dispensed can be dispensed accurately and stably. The stability and accuracy of the glue droplets can be guaranteed at a larger dispensing distance, so that the dispensing position is accurate and the glue line after dispensing is uniform, thereby effectively improving the dispensing effect, and applying a low voltage to the dispensing needle 2 can avoid the safety hazards caused by applying a high voltage to the dispensing needle 2.

[0044] The EHD dispensing device provided by the embodiment of the present invention provides a voltage signal to the dispensing needle and the workpiece to be dispensed by setting a voltage output device, and sets the first voltage signal applied to the dispensing needle to be smaller than the second voltage signal provided to the workpiece to be dispensed, and sets the second voltage signal to be larger than the first voltage signal, and the second voltage signal is larger than zero, so that a uniform electric field can be formed at each position on the surface of the workpiece to be dispensed, so that the dispensing needle can ensure the stability of the electric field when moving, so that the dispensing needle can make the force condition of the glue at each position on the surface of the workpiece to be dispensed more consistent, and can ensure the stability and accuracy of the glue dripping, so that the glue in the dispensing needle can accurately drip the glue onto the surface of the workpiece to be dispensed under the joint action of the electric field force and the air pressure, and on the basis of ensuring safe operation, can make the dispensing position accurate and the glue line after dispensing uniform at a large dispensing distance, realize stable and accurate large-spacing dispensing, and can effectively improve the dispensing effect.

[0045] Optional, Figure 3 is a schematic diagram of the structure of another EHD dispensing device provided by an embodiment of the present invention, such as Figure 3 As shown, the voltage output device 1 includes: a signal generator 11 and a voltage amplifier 12; the input end of the voltage amplifier 12 is electrically connected to the signal generator 11, the first voltage output end e1 of the voltage amplifier 12 is electrically connected to the dispensing needle 2, and the second voltage output end e2 of the voltage amplifier 12 is electrically connected to the workpiece 3 to be dispensed.

[0046] Specifically, the signal generator 11 can provide a variety of voltage signals such as DC voltage signals and pulse signals, and can set parameters such as the frequency, duty cycle, amplitude, etc. of the signal. The voltage amplifier 12 can amplify the signal provided by the signal generator 11 by a certain multiple, and the amplification multiple is adjustable. The amplified signal (i.e., the excitation voltage waveform) can be directly output to the dispensing needle 2 and the workpiece 3 to be dispensed.

[0047] Exemplarily, in some embodiments, the second voltage signal is U2; 0<U2≤5kV. The second voltage signal output by the voltage amplifier 12 can be adjusted by the signal generator 11 so that the second voltage signal is adjusted between 0-5kV.

[0048] Optional, Figure 4 is a schematic diagram of the structure of another EHD dispensing device provided by an embodiment of the present invention, such as Figure 4 As shown, the EHD dispensing device also includes an oscilloscope 4; the oscilloscope 4 is electrically connected to the signal acquisition terminal c1 of the voltage amplifier 12. The oscilloscope 4 is used to monitor the voltage waveform output by the voltage amplifier 12, so that the operator can intuitively observe the voltage parameters applied to the dispensing needle 2 and the workpiece 3 to be dispensed. Exemplarily, the voltage reading of the oscilloscope 4 can be 1 / 1000 of that of the voltage amplifier.

[0049] Optional, Figure 5 is a schematic diagram of the structure of another EHD dispensing device provided by an embodiment of the present invention, such as Figure 5 As shown, the EHD dispensing device also includes: a controller 5; the controller 5 is electrically connected to the voltage output device 1, and the controller 5 is used to control the first voltage signal and / or the second voltage signal output by the voltage output device 1 according to the dispensing distance between the dispensing needle 2 and the workpiece 3 to be dispensed.

[0050] Specifically, the controller 5 can be a chip with data processing function, for example, it can be an MCU or a CPU, etc., which is not specifically limited in the embodiment of the present invention. The controller 5 can be electrically connected to the voltage output device 1, and is used to adjust the first voltage signal applied to the dispensing needle 2 and / or the second voltage signal applied to the workpiece 3 to be dispensed according to the dispensing distance between the dispensing needle 2 and the workpiece 3 to be dispensed. In some embodiments, the controller 5 can be specifically electrically connected to the signal generator 11. For example, when the dispensing distance between the dispensing needle 2 and the workpiece 3 to be dispensed is larger, the second voltage signal can be controlled to be larger, and / or the first voltage signal can be controlled to be smaller, so as to ensure the negative charge accumulation of the glue, thereby ensuring the stability and accuracy of the glue droplet, and being able to achieve a stable and accurate dispensing effect when dispensing at a large distance.

[0051] Optional, continue to refer to Figure 5 The EHD dispensing device also includes: a dispensing head assembly, the dispensing head assembly at least includes a dispensing needle 2, and the controller 5 is also connected to the dispensing head assembly to control the movement of the dispensing head assembly. In this way, the controller 5 can control the dispensing needle 2 to move in the three directions of X, Y, and Z above the workpiece 3 to be dispensed according to the preset dispensing program, and the controller 5 can control the moving speed, displacement, and moving trajectory of the dispensing needle 2 to achieve automated dispensing operations. It can be understood that the EHD dispensing device can also include a driving structure, and the controller 5 can control the movement of the workpiece 3 to be dispensed by controlling the driving structure. The driving structure can include a motor and a transmission device, etc., which is not specifically limited in the embodiments of the present invention.

[0052] For example, Figure 6 is a schematic diagram of the structure of another EHD dispensing device provided by an embodiment of the present invention, such as Figure 6As shown, the dispensing head assembly may also include a barrel 6, an adapter (not shown in the figure) and other structures. The adapter is connected to the air source to provide a stable air pressure to the barrel 6. The barrel 6 may be made of corrosion-resistant engineering plastics to ensure good compatibility with various glues and is used to store the glue to be dispensed. The dispensing needle 2 may be made of ceramic, glass, stainless steel, etc. The glue inside the barrel 6 is squeezed out to the tip of the needle by air pressure. A wire is provided at a position of the barrel 6 close to the dispensing needle 2, which is connected to the first voltage output terminal e1 of the voltage output device 1 for receiving a negative voltage signal. In addition, the EHD dispensing device may also be provided with a UV lamp 7 for curing the glue, and the energy of the UV lamp 7 is adjustable.

[0053] The EHD dispensing device can also include a carrier 8, which can be a stainless steel plate with a thickness of 10 mm. Its surface is polished and treated with an insulating coating. The thickness of the insulating coating can be 0.1 mm to prevent electric field leakage and ensure the stability and uniformity of the electric field of the workpiece 3 to be dispensed.

[0054] Based on the same inventive concept, an embodiment of the present invention further provides an EHD dispensing method, which is performed by the EHD dispensing device provided by any embodiment of the present invention. Therefore, the EHD dispensing method provided by the embodiment of the present invention includes the technical features of the EHD dispensing device provided by any embodiment of the present invention, and can achieve the beneficial effects of the EHD dispensing device provided by any embodiment of the present invention. The similarities can be referred to the above description of the EHD dispensing device provided by the embodiment of the present invention, and will not be repeated here.

[0055] Figure 7 is a flow chart of an EHD dispensing method provided by an embodiment of the present invention, such as Figure 7 As shown, the EHD dispensing method includes:

[0056] S110, outputting a first voltage signal to the dispensing needle.

[0057] S120, outputting a second voltage signal to the workpiece to be glued.

[0058] The first voltage signal is smaller than the second voltage signal, and the second voltage signal is greater than zero.

[0059] Exemplarily, in some embodiments, the first voltage signal is less than or equal to zero.

[0060] The EHD dispensing method provided by the embodiment of the present invention sets the first voltage signal applied to the dispensing needle to be smaller than the second voltage signal provided to the workpiece to be dispensed, and sets the second voltage signal to be larger than the first voltage signal, and the second voltage signal is larger than zero, so that a uniform electric field can be formed at each position on the surface of the workpiece to be dispensed, so that the dispensing needle can ensure the stability of the electric field when moving, so that the dispensing needle can make the force condition of the glue at each position on the surface of the workpiece to be dispensed relatively consistent, and can ensure the stability and accuracy of the glue droplets, so that the glue in the dispensing needle can accurately drip the glue onto the surface of the workpiece to be dispensed under the joint action of the electric field force and the air pressure, and on the basis of ensuring safe operation, can make the dispensing position accurate and the glue line after dispensing uniform at a large dispensing distance, realize stable and accurate large-spacing dispensing, and can effectively improve the dispensing effect.

[0061] Optional, Figure 8 is a flow chart of another EHD dispensing method provided by an embodiment of the present invention, such as Figure 8 As shown, the EHD dispensing method includes:

[0062] S210, outputting a first voltage signal to the dispensing needle.

[0063] S220, outputting a second voltage signal to the workpiece to be glued.

[0064] S230, obtaining the distance between the dispensing needle and the workpiece to be dispensed.

[0065] S240, controlling the first voltage signal and / or the second voltage signal according to the dispensing distance.

[0066] Exemplary, with reference to Figure 1 to Figure 6 In any of the accompanying drawings, when the dispensing distance between the dispensing needle 2 and the workpiece 3 to be dispensed is larger, the second voltage signal can be controlled to be larger, and / or the first voltage signal can be controlled to be smaller, so as to ensure the accumulation of negative charges of the glue, thereby ensuring the stability and accuracy of the glue droplets, and being able to achieve a stable and accurate dispensing effect when dispensing at a large distance.

[0067] The EHD dispensing method provided in the embodiment of the present invention can ensure the negative charge accumulation of the glue by controlling the first voltage signal and / or the second voltage signal output by the voltage output device according to the dispensing distance between the dispensing needle and the workpiece to be dispensed, thereby ensuring the stability and accuracy of the glue droplets, and can ensure that the dispensing position is accurate and the glue line after dispensing is uniform when dispensing at a large distance, which can effectively improve the dispensing effect.

[0068] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An EHD dispensing device, characterized in that: include: A voltage output device, a glue dispensing needle and a workpiece to be glued; the glue dispensing needle dispenses glue to the workpiece to be glued; The voltage output device comprises a first voltage output terminal and a second voltage output terminal, the first voltage output terminal is used to output a first voltage signal, and the second voltage output terminal is used to output a second voltage signal; The first voltage output end is electrically connected to the glue dispensing needle, and the second voltage output end is electrically connected to the workpiece to be glued; The first voltage signal is smaller than the second voltage signal, and the second voltage signal is greater than zero.

2. The EHD dispensing device according to claim 1, characterized in that: The first voltage signal is less than or equal to zero.

3. The EHD dispensing device according to claim 1, characterized in that: The voltage output device comprises: a signal generator and a voltage amplifier; The input end of the voltage amplifier is electrically connected to the signal generator, the first voltage output end of the voltage amplifier is electrically connected to the glue dispensing needle, and the second voltage output end of the voltage amplifier is electrically connected to the workpiece to be glued.

4. The EHD dispensing device according to claim 3, characterized in that: Also includes: Oscilloscope; The oscilloscope is electrically connected to the signal collection end of the voltage amplifier.

5. The EHD dispensing device according to claim 1, characterized in that: The second voltage signal is U2; 0<U2≤5kV.

6. The EHD dispensing device according to claim 1, characterized in that: Also includes: Controller; The controller is electrically connected to the voltage output device, and the controller is used to control the first voltage signal and / or the second voltage signal output by the voltage output device according to the dispensing distance between the dispensing needle and the workpiece to be dispensed.

7. The EHD dispensing device according to claim 6, characterized in that: Also includes: A glue dispensing head assembly, the glue dispensing head assembly at least comprising the glue dispensing needle; The controller is also connected to the glue dispensing head assembly and is used to control the movement of the glue dispensing head assembly.

8. An EHD dispensing method, characterized in that: include: Outputting a first voltage signal to the dispensing needle; Outputting a second voltage signal to the workpiece to be dispensed; The first voltage signal is smaller than the second voltage signal, and the second voltage signal is greater than zero.

9. The EHD dispensing method according to claim 8, characterized in that: The first voltage signal is less than or equal to zero.

10. The EHD dispensing method according to claim 8, characterized in that: Also includes: Obtaining the dispensing distance between the dispensing needle and the workpiece to be dispensed; The first voltage signal and / or the second voltage signal is controlled according to the dispensing distance.

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