JP2018527178A - Dispensing monitoring and control - Google Patents

Abstract

A method and system (10) for accurately dispensing a viscous fluid onto a substrate. In one embodiment, the method uses an electrical flow meter device (32a, 32b) to generate an electrical flow meter output signal to compensate for the difference between the output data set and the reference data set. The response control function is implemented in a closed loop manner by adjusting at least one dispensing parameter. In another embodiment, the system (10) includes a controller operably coupled to the gas flow meter device (32a, 32b) and the weight meter (72) to determine an amount of density of the viscous material. Allow that.

Description

  This application claims priority from US application Ser. No. 14 / 855,487, filed Sep. 16, 2015. The provisional application is hereby incorporated in its entirety by the relevant reference (incorporated by reference).

  The present invention generally relates to the field of fluid dispensers that accurately dispense small amounts of viscous fluid in various forms, such as dots, droplets, lines, and the like.

  In the manufacture of various articles such as printed circuit (PC) boards, it is often necessary to apply (apply) a minute amount of a viscous material having a viscosity, for example, greater than 50 centipoise, on a substrate. Such materials include general purpose adhesives, solder pastes, solder fluxes, solder masks, greases, oils, encapsulants, embedding resins, epoxy resins, die attach pastes, silicon, RTV, cyano. Acrylates are illustratively included, but are not limited thereto.

  As an example, a manufacturing method known as flip chip technology has been developed. It includes multiple processes that require viscous fluid dispensing. For example, a semiconductor die or flip chip is first attached to a PC board via solder balls or pads. In this process, a viscous solder solvent is applied between the flip chip and the PC board. Next, a viscous liquid epoxy resin is dispensed and allowed to flow under the chip and completely cover. Underfilling operations require that an accurate amount of liquid epoxy resin be deposited along at least one side edge of the semiconductor chip. As the volume of the epoxy resin decreases during the curing process, a pseudo-hydrostatic state of stress is imposed on the solder ball or pad, which provides resistance to solder ball or pad deformation, i.e., resistance to fracture. Liquid epoxy resin flows under the chip as a result of capillary action due to a small gap between the underside of the chip and the top surface of the PC board. When the underfill operation is complete, it is desirable to deposit enough liquid epoxy resin to encapsulate all of the electrical interconnects. Thereby, a fillet part is formed along the side edge of a chip | tip. A properly formed fillet ensures that sufficient epoxy resin is deposited to provide maximum mechanical strength of the bond between the chip and the PC board. Accurate deposition of the correct amount of epoxy resin in the correct location is important for the quality of the underfill process. Too little epoxy resin can result in corrosion and excessive thermal stress. Excessive epoxy resin can flow over the underside of the chip and interfere with other semiconductor devices and interconnects. These parameters must be accurately controlled in a manufacturing environment that requires high-speed productivity.

  In another application, the chip is coupled to a PC board. In this application, an adhesive pattern is deposited on the PC board and the chip is placed on the adhesive with downward pressure. The adhesive pattern is designed such that the adhesive flows uniformly between the bottom of the chip and the PC board and does not flow from below the chip to the outside. In this application, it is important that the correct amount of adhesive is deposited at the correct location on the PC board.

  The PC board is often held by a conveyor that passes through a viscous material dispenser that is mounted biaxially on the PC board. The moving dispenser is often of a type that can deposit small dots or droplets of viscous material at the desired location on the PC board. This type of dispenser is commonly referred to as a non-contact spray dispenser. There are several variables that are often controlled to provide a high quality viscous material dispensing process. First, the weight or size of each dot is controlled. Known viscous material dispensers have a closed loop control system designed to keep the dot size constant during the material dispensing process. Controlling the dispensed weight or dot size by varying the supply pressure of the viscous material, the on-time of the dispensing valve in the dispenser, and the stroke length of the valve member of the injection dispenser Are known. Known control loops have advantages and disadvantages depending on the particular dispenser design and the viscous material being dispensed. On the other hand, known techniques often require additional components and mechanical structures. For example, a weight scale. This creates additional cost, time and reliability issues. Furthermore, known methods often require the use of a calibration process, separate from the manufacturing process. This reduces productivity. Accordingly, there is a continuing need to provide a quick and simple means for controlling parameters such as dot size, dispense fluid volume or weight.

  Another important variable that can be controlled in the dispensing process is the total amount of viscous material dispensed in a particular period. Chip designers often specify the total amount of viscous material. The viscous material is, for example, a base filling epoxy resin or a bonding adhesive, and is used to provide a desired base filling processing or bonding processing. Upon firing, it is known to program dispenser controls, for example, for a given dot size and dispenser speed. This causes the dispenser to dispense the appropriate number of dots to dispense the specified amount of viscous material into the desired line or pattern at the desired location. Such a system is reasonably effective when the dispensing parameters are constant. However, such parameters change constantly, albeit only slightly, over a short period of time. The intensive effects of such changes can result in unwanted changes in the volume of fluid dispensed by the dispenser. Thus, there is a need for a control system that can detect changes in dispensed volume and make automatic adjustments so that the desired overall volume of viscous fluid is dispensed uniformly throughout the entire dispense cycle. .

  Current systems assume that the density of the viscous material is constant. However, the density also changes constantly, resulting in an undesirable variation in the amount of fluid actually dispensed or jetted. Desirably, the amount of viscous material dispensed has a specific mass, volume, density, or acceptable tolerances for mass, volume, density. The accurate value of the viscous material being dispensed allows for greater accuracy when dispensing a desired amount of viscous material onto a substrate. Accordingly, there is a continuing need to accurately obtain the density of the viscous material as it is dispensed and adjust the dispensing parameters based on the density or specific gravity.

  In general, there is a need for an improved computer controlled viscous fluid dispensing system that addresses these and other challenges of accurately dispensing small amounts of viscous fluid, such as in high productivity manufacturing processes.

  The present invention provides, in various aspects, a method for controlling non-contact jet dispensing to accurately dispense a viscous fluid onto a substrate. The method includes directing viscous fluid from a viscous fluid supply to a non-contact jet dispenser. The non-contact spray dispenser has an inlet and an outlet. The method further comprises discharging the viscous fluid from the outlet of the non-contact spray dispenser. The non-contact spray dispenser may be operable to start and stop the flow of the viscous fluid from the outlet onto the substrate. The method further includes using an electrical flow meter device operably coupled in the flow path between the viscous fluid supply and the outlet to flow the viscous fluid through the flow path. Generating an electrical flow meter output signal proportional to. The electrical flow meter output signal forms an output data set. The method further includes comparing the output data set with a reference data set stored in a controller, and performing at least one response control function in a closed loop manner by adjusting a dispensing parameter; . This adjustment corrects (compensates) the difference between the output data set and the reference data set.

  A viscous fluid dispensing system for accurately dispensing viscous fluid onto a substrate is also disclosed. The system includes a viscous fluid dispenser having an inlet and an outlet. The system also includes a viscous fluid supply that is adapted to hold a viscous fluid and is coupled in fluid communication with the inlet of the viscous fluid dispenser, the viscous fluid supply of the viscous fluid dispenser A viscous fluid supply section that establishes a flow path of the viscous fluid between the outlet and the outlet; The system also includes a gas flow meter device operably coupled within the flow path to generate a gas flow meter output signal corresponding to the first amount of the viscous material. The system also includes a scale that is configured to receive the first quantity and measure the weight to generate a corresponding scale output signal. The system also includes a controller operably coupled to the gas flow meter device and the weigh scale. The control unit determines the mass of the first amount using the weighing scale output signal received from the weighing scale, and integrates the gas flow rate output signal received from the gas flow meter device. A volume of a first quantity is determined, and a density of the first quantity is determined using the mass of the first quantity and the volume of the first quantity. Various additional features or alternative features may be included in the system.

  A method of controlling a viscous fluid dispensing system to accurately dispense viscous fluid onto a substrate is also disclosed. The method includes directing a first amount of viscous fluid from a viscous fluid supply to a viscous fluid dispenser. The viscous fluid dispenser is operable to start and stop the flow of the viscous fluid onto the substrate through an outlet of the viscous fluid dispenser. The method also uses the gas flow meter device operably coupled in the flow path between the viscous fluid supply and the outlet to flow the first amount of the flow through the flow path. Generating a gas flow meter output signal proportional to. The method also includes discharging the first amount from the outlet to a weight scale coupled to the controller. The weigh scale generates a weigh scale output signal that is proportional to the mass of the first quantity. The method also includes performing a response control function in a closed loop manner by adjusting at least one dispensing parameter using the gas flow meter output signal and the weigh scale output signal.

  Additional features of the method will be understood from reference to the system operation described above and described in more detail below. For example, in some embodiments, the output data set may include an electrical flow meter output signal, and in other embodiments, the output data set includes a gas flow meter output signal and a weigh scale output signal. Dispensing can also include various types of segmented volume output of viscous fluids, such as dots, droplets, lines, or other types of output. These and other objects and advantages of the present invention will become more readily apparent upon consideration of the following detailed description in conjunction with the accompanying drawings.

FIG. 1 is a front view of a viscous fluid dispensing system constructed in accordance with one embodiment of the present invention.

FIG. 2 is a flow diagram illustrating one embodiment of a process group performed by controls associated with the system illustrated in FIG.

FIG. 3 is a flow diagram illustrating another embodiment of a process group performed by controls associated with the system illustrated in FIG.

FIG. 4 is a front view of a viscous fluid dispensing system constructed in accordance with another embodiment of the present invention.

FIG. 5 is a flow diagram illustrating one embodiment of a process group performed by controls associated with the system illustrated in FIG.

  FIG. 1 is a schematic diagram of a viscous fluid dispensing system 10 for accurately dispensing viscous fluid and controlling the dispensing operation. The system 10 includes a viscous fluid inlet 14, a dispensing outlet 16 for the viscous fluid, and an internal movable valve 18 for controlling on / off of the dispensing operation of the viscous fluid 20 onto the substrate 22. A viscous fluid dispenser 12 is provided. The valve 18 is movable between an open position and a closed position, for example, to dispense the viscous fluid 20 on the substrate 22 via the outlet 16 in a segmented volume. The present invention is not limited to that type of method or structure for starting and stopping flow from the dispenser. For example, other types of dispensers that rely on pressure-induced aspects to start and stop flow may be utilized. The dispenser 12 may be of any suitable type and form, depending on the dispensing application and user needs. In general, the dispenser may dispense a continuous line or other pattern of viscous fluid 20 onto the substrate 22, or a jet type that rapidly dispenses a small segmented volume of viscous fluid in the form of dots or droplets. It may be a dispenser. For example, such jetting dispensers are available from Nordson ASYMTEK, Carlsbad, Calif. Under the names DispenseJet® and NexJet®. The dispenser 12 can be operated, for example, pneumatically or electrically. As shown, the dispenser 12 includes or is coupled to a solenoid valve 24 that controls the introduction of compressed working air through a line or conduit 25 in a known manner for moving the valve 18 to at least an open position. Yes. In a dual air chamber dispenser, compressed air can also be utilized to move the valve 18 to the closed position. In other embodiments, a spring may be utilized to move the valve 18 to the closed position.

  The system 10 further comprises a viscous fluid supply container 26 adapted to hold the viscous fluid 20 and coupled in fluid communication with the inlet of the dispenser 12. A viscous fluid flow path is established between the viscous fluid supply container 26 and the outlet 16 of the viscous fluid dispenser 12. In this embodiment, the supply of fluid 20 in the container 26 is compressed and driven by air from a suitable air source 28 that is regulated by a pressure regulator 30. An electrical flow meter output signal proportional to the flow rate of the fluid 20 flowing through the flow path when a liquid flow meter 32a, i.e., a flow sensor device, is coupled in the flow path and the valve 18 is in the open position. Is generated. The liquid flow meter 32a may be coupled directly into a fluid line or conduit 34 that extends from the outlet 36 of the supply container 26 to the inlet 14 of the dispenser 12. In this embodiment, the liquid flow meter 32a is preferably a Sensirion model LG16-2000 or LG16-1000 liquid flow sensor or model SLQ-QT105 flow sensor available from Sensirion AG, Switzerland. The particular model of flow meter selected typically depends on the flow rate required in the application and factors such as response time and sensitivity. In other embodiments, the liquid flow meter 32a may be included either directly in the dispenser 12 or in the flow path upstream of the outlet 16, as shown in phantom in FIG. Further alternatively, a liquid flow meter 32 a can be provided in the nozzle 16. In yet another embodiment, a gas flow meter 32b can be coupled to the pneumatically operated side of the system. For example, the gas flow meter 32 b can be coupled between the pressure regulator 30 and the inlet 38 of the container 26. In this embodiment, the gas flow meter 32b is preferably a Sensirion model SFM3100 or SFM4100 gas flow sensor available from Sensirion AG, Switzerland. A controller 40 is operably coupled to either or both electrical flow meters 32a, 32b, regardless of their position in the system. The controller 40 continuously receives and processes electrical flow meter output signals indicative of each of the viscous fluid or gas flow data points from the flow meters 32a, 32b and closes the loop as described in detail below. The response control function is performed in the manner described above. The controller 40 may be a PLC, programmable logic controller, or any other suitable computer-based controller that can process signals from the flow meters 32a, 32b, for example, to perform the functions detailed below. Can be. The application of the system 10 and the fluid material to be dispensed can be of any desired type, including those described in the background section.

  2 and 3 show different embodiments of the schematic flow of software implemented and executed by the control unit 40 shown in FIG. As shown in first step 50 of FIG. 2, flow meters 32a, 32b, pressure regulator 30, and any other control elements associated with dispenser 12 are initialized to initiate a dispensing operation. The In a next step 52, the dispenser 12 initiates viscous fluid dispensing in the desired manner as programmed and executed by the controller 40. For example, a plurality of dots or droplets or a line of viscous fluid 20 is dispensed at high speed onto the substrate 22 (FIG. 1). While the dispensing operation is being performed, flow data points (signals) of viscous fluid or gas are collected by the controller 40 from the flow meters 32a, 32b. This data is processed in step 54 in one or more manners as detailed below. For example, the processing in step 54 may include comparing the collected data set with stored reference data, or other analysis methods. In step 56, the control unit 40 determines whether or not the flow rate (flow velocity) of the viscous fluid is within an allowable range. If the flow rate is within an acceptable range, the process returns to step 52 and continues the dispensing operation. If the flow rate is not within an acceptable range, the dispense parameter is adjusted correspondingly at step 58. Thereafter, the control unit 40 continues to execute the dispensing operation and the control function in a closed loop manner.

  In order to analyze the data or signals collected from the flow meters 32a, 32b, the control unit 40 can compare output data from the flow meters 32a, 32b with stored reference data, for example. The output data from the flow diameters 32a and 32b can be, for example, one data set. The data set can be plotted on a graph as flow vs time. As a result, a curve or waveform can be generated by the controller 40. A generally rectangular waveform can be generated, in which case the signal peaks while the dispenser valve 18 is open, and then drops sharply when the valve is closed. During the jetting operation, the waveform or curve generated by the flow signal data output from the flow meters 32a and 32b is similar to a sawtooth pattern along the curve, and the fluid material 20 is discharged from the dispenser outlet 16 as a plurality of dots. This shows a quick on / off or open / closed state of the valve 18 when it is rapidly injected. When the valve 18 is maintained in the closed position at the end of the injection operation, the waveform or curve will drop to zero. In this operation, the analysis performed by the control unit 40 can compare the waveform generated by the data (signals) from the flow meters 32a and 32b with a reference waveform that represents a more ideal flow pattern. If the two waveforms or curves being compared are not similar, the controller 40 performs adjustments to the system 10. More generally speaking, the control unit 40 compares the current or real-time data set based on the signals from the flow meters 32a and 32b with the representative value of the viscous fluid or gas flow, and compares the real-time data. The set is compared to a similar reference data set of viscous fluid or gas flow. Based on detection of discrepancies between the two data sets being compared, the controller is programmed to perform adjustments to various processing parameters of the system. It is not necessary that the data set be assembled (processed) as a waveform by the control unit 40. For example, in the case of a continuous dispensing operation having a dispensing cycle in which the valve is continuously opened to dispense a single line of viscous fluid 20, the waveform can be even more rectangular.

  The analysis performed when collecting signals / data from the flow meters 32a, 32b may include various processes and / or algorithms. One process may include comparing the average of the detected waveform peaks to a reference or ideal waveform stored in the controller 40. Another method may include determining an area under the waveform (ie, integrating under the curve) and comparing the area with reference data.

  When dispensing fluid 20 lines, or when ejecting fluid 20 dots, a data set representing the appropriate flow during dispensing or jetting can be stored as a reference data set from flow meters 32a, 32b. Can be compared to real-time data sets. If the real-time data set fluctuates from the reference data set (if the difference is large), calibration can be done for dispensing or jetting. Changes to the system include, for example, changing the air pressure to the syringe or container 26 that supplies the fluid 20, adjusting the time at which the dispenser dispenses the viscous fluid 20, the temperature of the dispenser 12, the dispensing speed of the viscous fluid 20 (ignition frequency) ) Or the number of dots dispensed in a particular pattern. Calibration can be done very quickly, for example, response time is within 40 milliseconds. Typically, if there is a time on the order of 100 milliseconds between two consecutive dispenses, that time will adjust or calibrate the amount of viscous fluid 20 dispensed without affecting the processing time. Can be used. As a result, calibration can be made between the end of one dispense or spray operation and the start of the next dispense or spray operation. This very short response time is a few seconds that may be required for dispensing fluid material 20 on a weight scale, measuring the weight of fluid material 20, calculating flow rate, etc., as in conventional configuration processes. It is a good contrast to the time (very good).

  The system 10 can also be utilized to detect one or more air bubbles that are exhausted through the outlet 16. In this case, the flow meters 32a, 32b will detect an instantaneous increase in flow rate as the air bubbles pass through the dispenser outlet 16. This momentary increase in flow is detected by the controller 40 based on signals from the flow meters 32a, 32b, for example, via an alarm, signal light, or other indicator on the controller or computer screen. Can be used to present the problem. The operator 10 can then inspect the substrate 22 for quality issues and perform the necessary maintenance of the system 10. The system 10 can also be utilized to detect an occlusion or semi-occlusion condition associated with the dispenser 12, particularly associated with the nozzle or outlet 16 of the dispenser 12. In this case, the flow meters 32a, 32b will detect a state where there is no flow or a state where the flow is significantly reduced. If this condition is detected, the signals from the flow meters 32a, 32b are controlled using, for example, an alarm sound, light, or other controls or indicators on the computer screen to present the condition to the operator. Used by unit 40. This will allow the operator to shut down the system for maintenance purposes. Quickly shutting down the system 10 due to problems such as air bubbles or blockages minimizes waste (waste) of the product and increases yield.

  As shown in first step 60 of FIG. 3, flow meters 32a, 32b, pressure regulator 30, and any other control elements associated with dispenser 12 are initialized to initiate a dispensing operation. The In the next step 62, the dispenser 12 begins dispensing the viscous fluid in the desired manner as programmed and executed by the controller 40. For example, a plurality of dots or droplets or a line of viscous fluid 20 is dispensed onto substrate 22 at high speed. As described above, viscous fluid or gas flow data points are collected by the controller 40 from the flow meters 32a, 32b while the dispensing operation is being performed. These signals may include electrical flow meter device signals. This data may be processed at step 64 in one or more manners as detailed below. For example, the process in step 64 may include integrating the viscous fluid or gas flow meter data to determine a volume of viscous fluid 20 passing through the flow meters 32a, 32b. In other words, the flow meter data is integrated over time to produce a first volume of viscous fluid 20. The volume of the output data set can then be compared against the reference volume of the reference data set. If desired, the mass of the first amount of viscous fluid 20 can be determined using the reference data. Here, the mass corresponds to a specific amount of the viscous fluid 20 flowing through the flow meters 32a, 32b. These reference values can be stored in the control unit 40. In step 66, the total mass or volume is divided by the total number of dots so that the volume (in the form of data or signal) or the combined mass and volume (in the form of data or signal) is per dot. Can be determined. In step 68, the controller 40 may determine whether the value (eg, volume / mass value) is within acceptable tolerances. If the value is within acceptable tolerances, the viscous fluid is dispensed and the dispensing process proceeds. If the value is not within acceptable tolerances, one or more dispensing parameters may be adjusted. In addition, the user can be warned as detailed below.

  Adjusting the dispensing parameters can include, for example, adjusting the flow rate of the viscous fluid 20 dispensed through the outlet 16 of the dispenser 12, adjusting the dispensing time shorter or longer, within a given time period. Adjusting the frequency at which the viscous fluid is dispensed through the outlet onto the substrate by increasing the number of dispensing operations of the fluid, and the segmented dots using multiple doses of the viscous fluid 20 Or adjusting the number of droplets and adjusting the speed of relative movement between the dispenser 12 and the substrate. Each of these dispensing parameters can be adjusted to correct the difference between the output data set and the reference data set, either alone or in combination with other dispensing parameters. Adjusting the flow rate of the viscous fluid 20 dispensed through the outlet 16 of the dispenser 12 may include adjusting the viscosity of the viscous fluid 20, for example, by adjusting the temperature of the viscous fluid 20. The temperature of the viscous fluid 20 can be adjusted using a heater (not shown). The heater can be configured to raise or lower the temperature of the viscous fluid 20 dispensed by the dispenser 12. Further, the heater can be electrically coupled to the controller 40, and the controller 40 can be configured to operate (control) the heater. However, other methods of adjusting the flow rate of the fluid 20 dispensed from the outlet 16 are also contemplated.

  Adjusting the speed of relative movement between the dispenser 12 and the substrate can be implemented in the following manner. The system 10 automatically optimizes the relative velocity between the nozzle 48 and the substrate 22 as a function of the viscous fluid dispensing characteristics and the specified overall amount of material to be utilized on the substrate 22. Can be tolerated. The system 10 may also optimize the position where each dot is to be dispensed as a function of the relative velocity between the outlet 16 of the dispenser 12 and the substrate 22. Specifically, comparing the output data set to the reference data set may include determining the speed of relative movement between the dispenser 12 and the substrate 22 using the output data set. This results in the target amount of the viscous fluid 20 discharged onto the substrate 22.

  The speed of relative movement can be determined by determining the amount of viscous fluid 20 in the form of the total number of dots required to be substantially equal to the target amount. This can be determined by calculating the average volume per dot of the output data set. Additionally, the distance between each of the total number of dots required to distribute the dots or droplets is determined. Additionally, the rate at which the total number of dots or droplets is to be dispensed from the dispenser is determined. This is the rate at which the total number of dots or droplets is dispensed, and the distance between each of the dots in the total number of dots or droplets. This rate can then be used to adjust the speed of relative movement between the dispenser 12 and the substrate 22 to discharge a target amount of viscous fluid 20 onto the substrate 22. Further details can be found by the Applicant in US Application No. 13 / 079,300 entitled “Non-Contact Injection System for Viscous Materials”, now entitled US Pat. No. 8,257,779. It is disclosed. The contents of the application are incorporated herein by reference.

  FIG. 4 is a schematic diagram of a viscous fluid dispensing system 100 for accurately dispensing viscous fluid 20 and controlling the dispensing operation. The system 100 of FIG. 4 is similar to the system 10 of FIG. 1 but additionally includes a weigh scale 72 that is electrically coupled to the controller 40. The weigh scale 72 may include a calibration surface 73 for receiving the viscous fluid 20. The weigh scale 72 receives a quantity of the viscous fluid 20 deposited on the calibration surface 73, measures its weight, and generates a weigh scale output signal proportional to the mass of that quantity of the viscous fluid 20. It is configured as follows. The weigh scale 72 allows small amounts of viscous fluid 20 in various forms, such as dots, droplets or lines, to be accurately weighed. The viscous fluid 20 can be deposited or jetted depending on the desired application. In addition to the controller 40 being operably coupled to the weigh scale 72, the controller 40 is also coupled to either the liquid flow meter 32a or the gas flow meter 32b. As will be described in more detail below, using the weigh scale 72 and the gas flow meter 32b provides different advantages than using the weigh scale 72 and the liquid flow meter 32a.

  Using both the weigh scale 72 and the gas flow meter 32b allows the density of the viscous fluid 20 to be determined. This solves the problem when only one of the weight meter 72 and the gas flow meter 32b coupled to the control unit 40 is used. For example, if only the weigh scale 72 is used, the mass can be determined, but in order to obtain the mass from the weigh scale 72, the dispensing operation stops. This reduces the throughput of the viscous fluid dispenser 12, which is of course undesirable. The term “mass” as used herein is intended to include any measurement of mass (corresponding to mass), including, for example, mass, mass flow rate, and weight, as described below. Mass flow rate is a measure of the mass of the viscous fluid 20 flowing through the outlet 16 of the dispenser 12 in a given unit of time, conventionally measured in pounds per second or kilograms per second. Is done. Weight is related to mass using the formula W = m × g. Here, the weight (W) is equal to the mass (m) multiplied by the gravitational acceleration (g). Alternatively, since the temperature and pressure of the gas flowing through the gas flow meter 32b are known, this allows the gas volume to be determined. One skilled in the art will understand that this determines the volume of the viscous fluid 20. The term “volume” as used herein is intended to include any measurement of volume (corresponding to volume), including, for example, volume and volume flow. Volume flow is a measure of the volume of viscous fluid 20 flowing through outlet 16 of dispenser 12 in a given unit of time. However, the volume does not provide information regarding the mass of the viscous fluid 20.

  As a result, using the weigh scale 72 as a “setup tool” with the gas flow meter 32b before starting full dispensing allows a certain amount of density and specific gravity of the viscous fluid 20 to be determined. To do. Specifically, the gas flow meter 32b generates a gas flow meter output signal that is proportional to the flow rate of the second amount of viscous fluid that flows through the flow path and is dispensed through the outlet 36. This allows the control unit 40 to estimate the mass of the second quantity using the density of the first quantity and the volume of the second quantity. This allows for more accurate dispensing of the viscous fluid 20. Using historical data for the first and second quantities allows the system 10 to adjust the dispensing parameters in real time.

  FIG. 5 shows a schematic flow diagram of software implemented and executed by the control unit 40. FIG. 5 may utilize both the weigh scale 52 and the gas flow meter 32b to obtain the density or specific gravity of the fluid to be dispensed. In a first step 74, the gas flow meter 32b, the pressure regulator 30, and any other control elements associated with the dispenser 12 are initialized to initiate the dispensing operation. In the next step 76, the dispenser 12 begins dispensing the viscous fluid 20 in the desired manner. This includes the steps of dispensing a first amount of viscous fluid 20 to the weigh scale 72, collecting gas flow meter output data, and collecting weight scale output data. As a result, the first quantity of mass can be determined using the weigh scale output signal. Similarly, the volume of the first quantity can be determined at the same time, possibly using the gas flow meter output signal. This data may be processed in step 78 in one or more manners as detailed below. For example, the process at step 78 may include integrating the gas flow meter data to determine a certain first volume of viscous fluid 20 passing through the gas flow meter 32b. Integrating viscous fluid or gas flow meter data over time produces a certain first volume of viscous fluid 20.

  In the next step 80, the density (equal to the mass divided by the volume) is divided by the volume obtained using the weigh scale 72 as a whole by the volume obtained using the gas flow meter 32b. Can be determined. Specific gravity can also be determined using density. Specific gravity is the ratio of the density of the viscous fluid 20 (as described above) to the density of a reference material, typically water at a particular temperature. If desired, the mass and volume of the first amount of viscous fluid 20 can be determined per dot, per drop, or per line. In other words, the density can be determined using multiple dots, multiple droplets or multiple lines of viscous fluid 20, or alternatively, a single dot, single droplet of viscous fluid 20 Or it can be determined using a single line. In step 82, the control unit 40 determines whether the density of the viscous fluid 20 is within an allowable tolerance of a predetermined value. If the density is within acceptable tolerances, the process may utilize a conversion factor (eg, inverse density equal to volume / mass) to ensure higher operating accuracy. Acceptable tolerances can be determined using a reference data set stored in the controller 40 or by other acceptable methods. If the density is not within acceptable tolerances, the user is warned. For example, the controller 40 may provide suitable instructions to the operator, such as presenting an alarm sound or light, or a display on a screen or monitor associated with the controller. In addition to or instead of instructions to the operator, at least one dispensing parameter may be adjusted as described above. With respect to FIG. 5, the density is illustrated and described, but the specific gravity can also be determined and adjusted as desired.

  After the control unit 40 receives and processes the gas flow meter output signal and the weight meter output signal and determines the density of the first amount, the control unit 40 determines the density of the first amount and the volume of the second amount. Can be used to determine an estimated mass of the second quantity. By having the second amount of estimated mass, the controller 40 can adjust one or more dispensing parameters for the additional amount of viscous fluid dispensed through the outlet, as described above. . As a result, the viscous fluid dispensing system 10 can continuously improve the dispensing operation by continuously utilizing the previous (previous) amount of density and volume to estimate the mass. This allows all volume measurements to be obtained using a gas flow meter, obtains density from the gas flow meter 32b and weight meter 72, calculates the mass without stopping production, and processes Adjustments can be made.

  In another embodiment of the system 100, the controller may be operably coupled to both the weigh scale 72 and the liquid flow meter 32a. In this embodiment, using both the weigh scale 72 and the liquid flow meter 32a allows the liquid flow meter 32a to be calibrated quickly and accurately. By placing a known weight object on the calibration surface 73 of the scale 72, the scale 72 is initially quickly and accurately calibrated while the process for calibrating the liquid flow meter 32a is Is much more difficult than However, dispensing an amount of viscous fluid 20 on the calibration surface 73 of the weigh scale 72 through the liquid flow meter 32a allows for a quick and accurate configuration of the liquid flow meter 32a. As a result, including both the weight meter 72 and the liquid flow meter 32a allows the weight meter 72 to effectively calibrate the liquid flow meter 32a.

  During the manufacturing process, including dispensing operations, the system 10, 100 adjusts on-the-fly to the dispensing parameters as described above and on-the-fly. It will be understood that it can be utilized for the detection purposes of (fly). That is, the routines shown in FIGS. 2, 3 and 5 can be used continuously during the manufacturing process, and the dispense parameters are adjusted during manufacturing to improve productivity. The routine of FIG. 5 includes the step of determining the density prior to full dispensing as described above. The system 10, 100 can also be utilized with a calibration station, in which case the dispenser 112 is taken offline and moved to the calibration station, and the routines shown in FIGS. 2, 3 and 5 are performed at the calibration station. To be implemented. This aspect is in stark contrast to on-the-fly implementation during the manufacturing process. There are also advantages to using the system 10, 110 in a calibration station. For example, less fluid material 20 will be utilized than in a typical calibration station using a weigh scale, and the calibration and adjustment process will be faster and in some cases more accurate. Certain fluid materials, such as solder solvents, are volatile, and solvents associated with the fluids volatilize (evaporate) when exposed to the atmosphere. Therefore, if the weigh scale process takes time to allow volatilization, the results will be inaccurate. According to the system 10 of the present invention, the flow data is collected by the control unit 40 within a short time near real time. The volatilization of the solvent associated with the fluid has no effect on this measurement. It should be noted that offline means that the dispenser 12 that is still coupled to the system 10, 100 dispenses the viscous fluid 20 onto the calibration surface 73 of the weigh scale 72 positioned adjacent or close to the substrate. is assumed.

  The present invention has been described in terms of several embodiments, which have been described in considerable detail. However, it is not intended that the scope of the appended claims be limited to such details or in any way. Additional advantages and modifications are readily apparent to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details shown and described. The various features described herein can be used in any combination that is necessary or desired for a particular application. Consequently, developments from the details set forth herein may be made without departing from the spirit or scope of the claims.

Claims (31)

A method of controlling non-contact jet dispensing to accurately dispense a viscous fluid onto a substrate,
Directing the viscous fluid from the viscous fluid supply to a non-contact spray dispenser having an inlet and an outlet;
Discharging the viscous fluid through the outlet of the non-contact spray dispenser, wherein the non-contact spray dispenser starts and stops the flow of the viscous fluid onto the substrate through the outlet. A process of being operable;
Using an electrical flow meter device operably coupled in the flow path between the viscous fluid supply and the outlet of the non-contact jet dispenser, the viscous fluid flowing through the flow path Generating an electrical flow meter output signal proportional to the flow rate, wherein the electrical flow meter output signal forms an output data set;
Comparing the output data set with a reference data set stored in a controller;
Performing a response control function in a closed loop manner by adjusting at least one dispensing parameter to correct a difference between the output data set and the reference data set;
A method characterized by comprising: The method of claim 1, wherein performing the response control function further comprises adjusting a flow rate of viscous fluid dispensed through the outlet of the non-contact jet dispenser. . The method according to claim 2, wherein the step of adjusting the flow rate further includes the step of adjusting the viscosity of the viscous fluid. The method of claim 1, wherein the step of performing the response control function further comprises adjusting a dispensing time. The method of claim 1, wherein performing the response control function further comprises adjusting a frequency at which viscous fluid is dispensed through the outlet onto the substrate. The viscous fluid supply unit further includes a pressure supply unit that uses compressed air flowing through the pneumatic inlet of the viscous fluid supply unit,
The electrical flow meter device is operably coupled to the pneumatic inlet and provides an electrical flow meter output signal proportional to the flow rate of compressed air through the pneumatic inlet;
The method of claim 1, wherein adjusting the at least one dispensing parameter further comprises adjusting the pressure of the pressure supply. Discharging the viscous fluid through the outlet and implementing the response control function further comprises:
Discharging the viscous fluid through the outlet during relative movement between the non-contact spray dispenser and the substrate;
Adjusting the speed of the relative movement between the non-contact spray dispenser and the substrate;
The method of claim 1, comprising: Comparing the output data set with a reference data set and performing the response control function further comprises:
Using the output data set to determine a rate of relative movement between the non-contact spray dispenser and the substrate resulting in a target amount of viscous material being discharged onto the substrate;
Adjusting the speed of the relative movement between the non-contact spray dispenser and the substrate to discharge the target amount of viscous fluid onto the substrate;
Including
Determining the speed of the relative movement,
Determining the amount of viscous fluid in the form of the total number of dots required to be substantially equal to the target amount by determining an average volume per dot of the output data set;
Determining the distance between each of the total number of dots required to distribute the dots;
Determining the rate at which the total number of dots is dispensed from the non-contact spray dispenser;
Using the speed at which the total number of dots is dispensed, and the distance between each of the dots in the total number of dots,
The method of claim 1, comprising: The step of comparing the output data set with a reference data set stored in the controller further includes integrating the output data set to determine a volume of the output data set. Item 2. The method according to Item 1. Comparing the output data set with the reference data set and implementing the response control function further include:
Comparing the volume of the output data set with a reference volume of the reference data set;
Performing a response control function in a closed loop manner by adjusting at least one dispensing parameter to correct for a difference between the volume of the output data set and the reference volume of the reference data set; ,
The method of claim 9, comprising: The method of claim 1, wherein performing the response control function further comprises detecting air bubbles in the viscous fluid flowing through the non-contact spray dispenser. A viscous fluid dispensing system for accurately dispensing viscous fluid onto a substrate, comprising:
A viscous fluid dispenser having an inlet and an outlet;
A viscous fluid supply unit configured to hold a viscous fluid and coupled in fluid communication with the inlet of the viscous fluid dispenser, between the viscous fluid supply unit and the outlet of the viscous fluid dispenser. A viscous fluid supply section for establishing a flow path for the viscous fluid;
A gas flow meter device operatively coupled in the flow path to generate a gas flow meter output signal corresponding to the first amount of the viscous material;
A weigh scale configured to receive the first quantity and measure a weight to generate a corresponding weigh scale output signal;
A controller operably coupled to the gas flow meter device and the weigh scale;
With
The control unit determines the mass of the first amount using the weighing scale output signal received from the weighing scale, and integrates the gas flow rate output signal received from the gas flow meter device. A system for determining a volume of a first quantity and determining the density of the first quantity using the mass of the first quantity and the volume of the first quantity. 13. The control unit according to claim 12, wherein the control unit compares the density of the first amount with a predetermined allowable range and warns a user when the density is outside the allowable range. System. The gas flow meter device generates a gas flow meter output signal proportional to a volume of the second amount of the viscous fluid flowing through the flow path and dispensed from the outlet;
The system according to claim 12, wherein the control unit determines the mass flow rate of the second amount using the density of the first amount and the volume of the second amount. 15. The system of claim 14, further comprising an element that adjusts at least one dispensing parameter to adjust the second amount of the mass flow rate. The system of claim 15, wherein the element for adjusting the at least one dispensing parameter further comprises an element for adjusting a fluid supply pressure of the viscous fluid supply. 15. The system of claim 14, wherein the element for adjusting the at least one dispensing parameter further comprises an element for adjusting a frequency at which a continuous amount of the viscous fluid is dispensed from the outlet. A temperature control unit coupled to the control unit;
The system of claim 14, wherein the element for adjusting the at least one dispensing parameter further includes an element for adjusting the temperature of the viscous fluid dispenser using the temperature controller. The viscous fluid dispenser is an ejection dispenser configured to eject a plurality of dots of viscous fluid;
15. The system of claim 14, wherein the element that adjusts the at least one dispensing parameter further includes an element that adjusts the firing frequency at which the plurality of dots are ejected from the ejection dispenser. The viscous fluid dispenser is an ejection dispenser configured to eject a plurality of dots of viscous fluid;
15. The system of claim 14, wherein the element that adjusts the at least one dispensing parameter further includes an element that adjusts the number of dots fired in a pattern. The system of claim 12, wherein the controller detects an air bubble in the viscous fluid flowing through the viscous fluid dispenser. A method of controlling a viscous fluid dispensing system to accurately dispense viscous fluid onto a substrate, comprising:
Directing a first quantity of viscous fluid from a viscous fluid supply to a viscous fluid dispenser, wherein the viscous fluid dispenser directs the flow of the viscous fluid onto a substrate through an outlet of the viscous fluid dispenser. Being operable to start and stop;
A gas flow meter proportional to the flow rate of the first quantity flowing through the flow path using a gas flow meter device operably coupled in the flow path between the viscous fluid supply section and the outlet Generating an output signal; and
Discharging the first quantity from the outlet to a weight scale coupled to the control unit, wherein the scale produces a scale output signal proportional to the mass of the first quantity. Process,
Performing a response control function in a closed loop manner by adjusting at least one dispensing parameter using the gas flow meter output signal and the weigh scale output signal;
A method characterized by comprising: 23. The method of claim 22, wherein the response control function includes adjusting the flow rate of the viscous fluid dispensed through the outlet of the viscous fluid dispenser using the first amount of specific gravity. Method. The method of claim 22, wherein the step of performing the response control function further comprises adjusting a dispensing time using the specific gravity of the first amount. Determining the mass of the first quantity using the scale output signal;
Determining the volume of the first quantity using the gas flow meter output signal;
The method of claim 22, further comprising: The step of determining the volume of the first quantity further comprises the step of integrating the gas flow meter output signal obtained from the gas flow meter device using the controller. Item 23. The method according to Item 22. The step of performing the response control function further includes:
Calculating the specific gravity of the first quantity using the mass and volume of the first quantity;
Adjusting at least one dispensing parameter using the first amount of the specific gravity;
23. The method of claim 22, comprising: The step of performing the response control function further includes:
Calculating the density of the first quantity using the mass and volume of the first quantity;
Adjusting at least one dispensing parameter using the density of the first amount;
23. The method of claim 22, comprising: The gas flow meter output signal and the weight meter output signal form an output data set,
The method of claim 22, wherein performing the response control function further comprises adjusting at least one dispensing parameter using a specific gravity calculated using the output data set. . The gas flow meter output signal and the weight meter output signal form an output data set,
The method of claim 22, wherein performing the response control function further comprises adjusting at least one dispensing parameter with a density calculated using the output data set. . The gas flow meter output signal and the weight meter output signal form an output data set,
23. The method of claim 22, further comprising the step of comparing the output data set with a reference data set stored in the controller.

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