Patent Publication Number: US-2023158751-A1

Title: Systems and methods of displacement control in additive manufacturing of electronic components

Description:
BACKGROUND 
     The field of the disclosure relates to manufacturing of electronic components, and more particularly, to additive manufacturing of electronic components. 
     Different techniques are known to manufacture electronic components such as resistors or voltage dividers by applying a non-insulating, electrically resistive film or foil material onto an insulating substrate. Typical methods are sputtering (thin film) or screen and stencil printing (thick film). 
     Known systems and methods of manufacturing electronic components are disadvantaged in some aspects and improvements are desired. 
     BRIEF DESCRIPTION 
     In one aspect, a system of additive manufacturing of a high-voltage electronic component is provided. The system includes a dispenser and a height control assembly. The dispenser has a tip configured to deposit an additive material onto a surface of a substrate. The height control assembly is coupled to the dispenser and configured to detect a distance change of the tip of the dispenser from the surface of the substrate, wherein the height control assembly is further configured to adjust the dispenser based on the detected distance change. 
     In another aspect, a method of additive manufacturing of a high-voltage electronic component is provided. The method includes detecting, via a height control assembly, a distance change of a tip of a dispenser from a surface of a substrate. The method also includes adjusting, via the height control assembly, the dispenser based on the detected distance change and depositing, via the dispenser, an additive material onto the substrate from the tip of the dispenser. 
    
    
     
       DRAWINGS 
       Non-limiting and non-exhaustive embodiments are described with reference to the following Figures, wherein like reference numerals refer to like parts throughout the various drawings unless otherwise specified. 
         FIG.  1 A  is a schematic diagram of an exemplary system of additive manufacturing. 
         FIG.  1 B  is a schematic diagram of an exemplary embodiment of the system of additive manufacturing shown in  FIG.  1 A . 
         FIG.  2    shows an exemplary embodiment of a height control assembly of the system shown in  FIG.  1 B . 
         FIG.  3    shows another exemplary embodiment of a height control assembly of the system shown in  FIG.  1 B . 
         FIG.  4    is a flow chart of an exemplary method of additive manufacturing. 
         FIG.  5    shows exemplary voltage dividers manufactured using systems and methods shown in  FIGS.  1 A- 4   . 
     
    
    
     DETAILED DESCRIPTION 
     The disclosure includes systems and methods of additive manufacturing of electronic components such as resistors or voltage dividers. Method aspects will be in part apparent and in part explicitly discussed in the following description. 
     In manufacturing electronic components such as resistors or voltage dividers, the process includes depositing a film onto a substrate, baking the deposition with the substrate in a high temperature furnace such as 850° C., and trimming the resistive path to fine-tune the electronic component. During deposition, a non-insulating, electrically resistive film or foil material, such as metal film or metal foil, e.g., nickel chromium, cermet film, e.g., tantalum nitride, ruthenium dioxide, bismuth ruthenate, carbon film, or a film of composite material based on a mixture of glass and cermet is deposited onto an insulating or dielectric substrate. The insulating substrate may be ceramic, silicon, glass or other synthetic material. In addition, highly conductive structures with considerable lower resistivity than the film material of the resistors are deposited on the substrate as well. The highly conductive structures are intended to be used as contacting terminals, and they are placed on the substrate in such a way that the resistive film material of the resistors overlaps partly with them. 
     Film material may be applied to the substrate by known methods such as sputtering or screen printing. Sputtering is not suitable for manufacturing resistors having a high resistance value (e.g., 20 M ohm or greater), voltage dividers having a high voltage ratio, or components in high voltage sensors. Screen printing therefore is typically used. Screen printing allows for reasonably high throughput on complex circuit shapes such as those in non-inductive high voltage resistors and other integrated circuits. Screen printing process, however, is inflexible. Screen printing requires a screen or mask to be generated. For low volume parts and circuit designs, it is prohibitively costly to operate a manufacturing line for screen printing for small orders and custom designs. Current suppliers of resistors for high voltage and high power devices have long lead times, such as 4-8 weeks for standard designs and longer for custom orders. Some custom and complex resistors having features such as voltage cushions, integrated voltage dividers, or non-typical resistance values have even longer lead times. 
     In contrast, an additive manufacturing method offers a high degree of design flexibility whiles still providing relatively high throughput. With additive methods, increased complexity does not require an increase in production cost. Rather than designing screens, the systems and methods disclosed herein provide a simplified, continuous fluid dispensing printer for resistive, conductive and dielectric thin films. Systems and methods described herein provide a low cost printer with multiple movement stages, motors and control system that drastically reduces lead time to a time frame for example less than three days, allows for rapid prototyping of new designs, increases automation, and reduces the overall part count in printing integrated circuits. 
     In traditional additive manufacturing, a material is dispensed on a surface with defects and/or irregularities that do not exceed an acceptable tolerance. Additive manufacturing typically uses a reusable print surface that may be machined precisely. However, this level of precision becomes less practical when using additive manufacturing on a substrate embedded in the resultant print or electronic component, where the substrate is not reusable. The additional cost to precisely machine each substrate for each electronic component may become prohibitive. In volume manufacturing, tolerances of defects or unevenness of surface of the substrate are increased to lower cost. Further, ceramic substrates used as printing substrates for high voltage resistors and integrated voltage dividers may have significant, unique surface defects that needed be addressed for a high resistive path. Improvements are needed to meet the longstanding and unfulfilled needs in the art. 
     Systems and methods disclosed herein provide height control of the dispenser and real-time adjustment of height of the dispensing in an additive manufacturing process such that the distance between the tip of the dispenser and the surface of the substrate remains relatively constant. The ink of the additive material has a relatively high viscosity, e.g., greater than 1000 centipoise. As the dispenser or the dispenser travels along the surface of the substrate at a certain speed, the height of the dispenser affects the consistency and amount of ink deposited on the surface of the substrate and therefore the characteristics of the electronic component. The height of the dispenser relative to the surface of the substrate therefore should be precisely controlled to ensure the precision of the printed electronic components. Further, due to the high viscosity of the additive material, the diameter or size of the tip is relatively small, e.g., approximately 100-1000 μm (17-32 gauge) to better control the deposition of the additive material. Pressure applied onto the additive material therefore is relatively large, e.g., 100-125 pound-force per square inch (psi) (689-862 Kilopascal (kPa)). The ink should be dispensed continuously and adjustment of height of the dispenser should be instantaneously or real time, rather than pausing, adjusting, and restarting the dispenser during the manufacturing process. The simple design provided by the systems and methods described herein allows implement in a production environment, not just a laboratory setting, at relatively low cost and high throughput. Additionally, the electrical contact installation and coating process is also automated for high volume production. 
     Compared to screen-printing, one more advantage of additive manufacturing is that deposition patterns in additive manufacturing are not limited by the screen. In screen-printing, because a screen is required, screen-printing cannot print a pattern having a complete loop that encompasses a circumference of a three-dimensional (3D) substrate such as a cylindrical substrate, limiting designs of electronic components. 
     Compared to conventional manufacturing of an electrical component, systems and methods described herein are advantageous in manufacturing high voltage electrical components, such as high voltage dividers. In conventional manufacturing of a voltage divider, resistors of the divider and their connections are separately designed and manufactured. Systems and methods described herein provide design flexibility, save space for electrical components, and provide uniform form factors for electrical components. For example, resistors and their connections are included one deposition design on one substrate. 
       FIGS.  1 A and  1 B  are a schematic diagram of an exemplary system  120  of additive manufacturing of a high-voltage electronic component ( FIG.  1 A ) and an exemplary embodiment of system  120  ( FIG.  1 B ). The electronic component may be a resistor or a voltage divider, which may be used in a voltage sensor. The voltage range of the electronic component may be 3.6 kV or above. Alternatively, the resistance ratio of the voltage divider is greater than 1000:1, or even greater than 10,000:1. In the exemplary embodiment, the system  120  includes a deposition assembly  150  configured to deposit an additive material  126  onto a substrate  110  ( FIG.  1 B ), and a furnace  152  used to bake the printed components. System  120  may include a trimming assembly  154 . The systems and methods described herein, however, do not require a trimming assembly  154 . 
     Additive manufacturing is applied to a substrate  110 . For example, substrate  110  is configured to form a voltage divider for use in a high voltage sensor. Substrate  110  is generally a dielectric substrate, e.g. a ceramic material or plastic, that does not conduct electricity. Substrate  110  includes a surface  112  that is configured to receive an additive material, such as a conductive material or a resistive paste that is applied using additive manufacturing. Surface  112  include imperfections where surface  112  is not entirely flat. That is, surface  112  may include raised portions  114  and/or recessed portions  116 . In some embodiments, surface  112  is non-planar. For example, substrate  110  is generally cylindrical in shape. 
     In the exemplary embodiment, deposition assembly  150  of system  120  includes a dispenser  122 , an actuator  144 , and a height control assembly  156 . A dispenser may also be referred to as a dispensing needle. Dispenser  122  may be a pneumatic dispenser, a syringe pump dispenser, or other dispensing devises configured to dispense a material having a high viscosity, e.g., greater than 1000 centipoise. The dispenser includes a dispensing tip  124 . The size of tip  124  may be in the range of approximately 100-1000 μm. Tip  124  of dispenser  122  is moved along surface  112  of substrate  110  to apply an additive material  126  to surface  112 . 
     In the exemplary embodiment, height control assembly  156  is configured to monitor or detect changes in a distance  158  between tip  124  of dispenser  122  from surface  112  of substrate  110 . A distance between a point and a surface is the distance between the point and the projection of the point to the surface. system  120  further includes an actuator  144 . Actuator  144  is a linear actuator, where actuator  144  moves in a direction perpendicular to surface  112  of substrate. That is, actuator  144  moves along a height direction  170  of dispenser  122 . 
     System  120  may further include a controller  138  in communication with actuator  144  and height control assembly  156 . In some embodiments, controller  138  includes a processor-based microcontroller including a processor  146  and a memory device  148  wherein executable instructions, commands, and control algorithms, as well as other data and information needed to satisfactorily operate system  120 , are stored. Memory  148  includes instructions that when executed by processor  146  enable controller  138  to process the distance change detected by height control assembly  156  and in response to the distance change, to raise or lower tip  124  of dispenser  122  relative to surface  112  of substrate  110 . In some embodiments, memory device  148  may be, for example, a random access memory (RAM), and other forms of memory used in conjunction with RAM memory, including but not limited to flash memory (FLASH), programmable read only memory (PROM), and electronically erasable programmable read only memory (EEPROM). 
     As used herein, the term “processor-based” microcontroller shall refer not only to controller devices including a processor or microprocessor as shown, but also to other equivalent elements such as microcomputers, programmable logic controllers, reduced instruction set circuits (RISC), application specific integrated circuits and other programmable circuits, logic circuits, equivalents thereof, and any other circuit or processor capable of executing the functions described below. The processor-based devices listed above are exemplary only, and are thus not intended to limit in any way the definition and/or meaning of the term “processor-based.” 
     In operation, height control assembly  156  detects changes in distance  158  between tip  124  of dispenser  122  and surface  112  of substrate  110 . As system  120  applies additive material  126  to surface  112 , increases in the distance  158  are indicative of the tip having reached a recessed portion  16  where the dispenser is farther from surface  112 . In response, controller  38  lowers dispenser tip  24  to uniformly apply additive material  126  to recessed portion  116 . In contrast, decreases in the distance  158  are indicative of dispenser tip  124  passing over a raised portion  114  of surface  112 . In response, controller  138  raises dispenser tip  124  to uniformly apply additive material  126  to raised portion  114 . 
       FIG.  2    shows an exemplary embodiment of height control assembly  156 - a . In the exemplary embodiment, height control assembly  156  includes a pole  202  offset from dispenser  122  and a ballpoint contactor  204  at an end of pole  202 . Ballpoint contactor  202  is fabricated from a rigid material such that ballpoint contactor  204  does not wear off or leave particles on substrate  110 . The material of ballpoint contactor  204  may include polytetrafluoroethylene, hardened steel, or tungsten carbide. Pole  202  is generally parallel to dispenser  122 . Pole  202  extends farther out from track  206  than dispenser such that ballpoint contactor  204  becomes in contact with surface  112  while dispenser  122  is not in contact with surface  112  when surface  112  is even at locations directly below ballpoint contactor  204  and tip  124  of dispenser  122 . A location on a surface directly below a point is the projection of the point onto the surface. Substrate  110  acts as a cam and ballpoint contactor  204  acts as a follower of the cam to follow surface  112  of substrate  110  such that ballpoint contactor  204  moves up or down as surface  112  raises or recesses. Height control assembly  156  is positioned proximate to dispenser  122 . For example, the distance or offset between ballpoint contactor  204  and tip  124  of dispenser  122  is less than 1 mm. As a result, the distance change detected by height control assembly  156  is approximately the same as the distance change in distance  158 . Both height control assembly  156  and dispenser  122  are positioned on and attached to stage  208  such that height control assembly  156  moves together with dispenser  122 . Height control assembly  156  is coupled with stage  208  through a buckle  210 . Other coupling mechanisms may be used to couple height control assembly  156  with stage  208  and therefore with dispenser  122 . Stage  208  may be mounted on a linear mounting track  206 . Track  206  may be spring loaded. Because dispenser  122  moves together with ballpoint contactor  204 , ballpoint contactor  204  maintains a constant distance  158  between tip  124  of dispenser  122  and surface  112  of the substrate  110 . When ballpoint contactor  204  becomes in contact with raised portion  114 , dispenser  122  is raised. When ballpoint contactor  204  becomes in contact with recesses portion  116 , dispenser  122  is lowered. 
       FIG.  3    shows another exemplary embodiment of height control assembly  156 - b . In the exemplary embodiment, both height control assembly  156  and dispenser  122  are attached to stage  208 . Height control assembly  156  is attached to stage  208  at an arm  302  extending from a body  304  of stage  208 . Body  304  includes holders sized to receive dispenser  122  therein. As a result, height control assembly  156  moves together with dispenser  122 . Height control assembly  156  includes a sensor  306  that measures distance between sensor  306  and substrate  110 . Sensor  306  includes an emitter  308  configured to emit a signal. Sensor is configured to detect a return signal reflected by surface  112  of substrate  110 . In the depicted embodiment, sensor  306  is a time of flight (TOF) sensor or camera, which is configured to emit light toward substrate  110 , receive a return signal or light reflected by surface  112  of substrate, and measure the distance between the camera and the substrate based on the time of flight between the emitted light and the reflected light. The light may be laser. Sensor  306  may be an 8 μm laser TOF sensor, which has an accuracy of 8 μm or higher or the error of the measurement is 8 μm or less. The light is aimed at a location on surface  112  of substrate  110  directly below tip  124  of dispenser  122 . In some embodiments, sensor  306  is a capacitive sensor configured to measure distance from sensor  306  to substrate  110 . Height control assembly  156  may include controller  138  configured to process the signals and provide distance measurements. Alternatively, signals are transmitted to and being processed by controller  138  located separately from height control assembly  156 . Controller  138  controls actuator  144  (see  FIG.  1 B ) to adjust the height of dispenser based on the detected distance change. Actuator  144  may be a ball screw stepper motor or a piezoelectric actuator. 
     In operation, the distance changes detected by height control assembly  156  are indicative the distance changes between tip  124  of dispenser  122  and surface  112  of substrate. Controller  138  is configured to adjust the height of dispenser  122  based on the distance changes by instructing actuator to raise or lower stage  208  based on the distance changes. An increase in the distance measured by height control assembly indicates that tip  124  has reached recessed portion  116  and actuator  144  lowers stage  208 . On the other hand, a decrease in the distance indicates that tip  124  has reached raised portion and actuator  144  raises stage  208 . 
     Compared to height control assembly  156 - a  shown in  FIG.  2   , height control assembly  156 - b  is contactless and does not become in contact with surface  112  of substrate  110 , without concern of material of height control assembly  156 - a  being worn off or left in substrate  110 . Further, the distance changes detected by height control assembly  156 - b  are more accurate than distance changes detected by height control assembly  156 - a  because height control assembly  156  measures the location directly below tip  124  of dispenser, instead of the location directly below ballpoint contactor  204 . 
       FIG.  4    is a flow chart showing an exemplary method  400  of additive manufacture. Method  400  includes detecting  402  a distance change of a tip of a dispenser from a surface of a substrate. Method  400  also includes adjusting  404  the dispenser based on the detected distance change. Further, method  400  includes depositing  406  an additive material onto the surface of the substrate. In conventional screen printing or additive manufacturing of electronic components, trimming is needed to fine tune the electronic components. Trimming is expensive and time consuming. Because the height of dispenser  122  is precisely controlled and adjusted based on surface  112  of substrate  110 , the deposited additive material corresponds to the designed pattern for the electronic component, and trimming of the electronic component is not needed to fine tune the electronic component, thereby saving cost in machinery and labor. 
       FIG.  5    shows voltage dividers  502  manufactured using systems and methods described herein. Printed resistive voltage dividers  502  have a high aspect ratio primary resistive path, and a low aspect ratio secondary path. Line widths (i.e. print resolution) of 300-800 microns have been generated, though larger line widths are clearly possible. The printer has generated prints of resistors with resistance values as high as 50 MOhm, and higher resistances up to at least 5 GOhms are feasible. Printed path lengths may be at 1.6 meters with an aspect ratio of as high as 4000:1. Additionally, overlapping printed paths have been generated to create large printed areas with low aspect ratios. 
     As used herein, the terms “processor” and “computer,” and related terms, e.g., “processing device,” “computing device,” and “controller” are not limited to just those integrated circuits referred to in the art as a computer, but broadly refers to a microcontroller, a microcomputer, an analog computer, a programmable logic controller (PLC), an application specific integrated circuit (ASIC), and other programmable circuits, and these terms are used interchangeably herein. In the embodiments described herein, “memory” may include, but is not limited to, a computer-readable medium, such as a random-access memory (RAM), a computer-readable non-volatile medium, such as a flash memory. Alternatively, a floppy disk, a compact disc-read only memory (CD-ROM), a magneto-optical disk (MOD), and/or a digital versatile disc (DVD) may also be used. Also, in the embodiments described herein, additional input channels may be, but are not limited to, computer peripherals associated with an operator interface such as a touchscreen, a mouse, and a keyboard. Alternatively, other computer peripherals may also be used that may include, for example, but not be limited to, a scanner. Furthermore, in the example embodiment, additional output channels may include, but not be limited to, an operator interface monitor or heads-up display. Some embodiments involve the use of one or more electronic or computing devices. Such devices typically include a processor, processing device, or controller, such as a general purpose central processing unit (CPU), a graphics processing unit (GPU), a microcontroller, a reduced instruction set computer (RISC) processor, an ASIC, a programmable logic controller (PLC), a field programmable gate array (FPGA), a digital signal processing (DSP) device, and/or any other circuit or processing device capable of executing the functions described herein. The methods described herein may be encoded as executable instructions embodied in a computer readable medium, including, without limitation, a storage device and/or a memory device. Such instructions, when executed by a processing device, cause the processing device to perform at least a portion of the methods described herein. The above examples are not intended to limit in any way the definition and/or meaning of the term processor and processing device. 
     At least one technical effect of the systems and methods described herein includes (a) additive manufacturing of electronic components; (b) controlling height of a dispenser to maintain consistency in deposition; and (c) real-time adjustment of the height of the dispenser to allow continuous deposition of an additive material. 
     Exemplary embodiments of systems and methods of additive manufacturing of electronic components are described above in detail. The systems and methods are not limited to the specific embodiments described herein but, rather, components of the systems and/or operations of the methods may be utilized independently and separately from other components and/or operations described herein. Further, the described components and/or operations may also be defined in, or used in combination with, other systems, methods, and/or devices, and are not limited to practice with only the systems described herein. 
     Although specific features of various embodiments of the invention may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the invention, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.