Coating processes – Nonuniform coating
Reexamination Certificate
2000-08-22
2002-05-28
Talbot, Brian K. (Department: 1762)
Coating processes
Nonuniform coating
C427S008000
Reexamination Certificate
active
06395334
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to an apparatus and method for performing a plurality of work operations in parallel using a plurality of work devices within one workstation. More specifically, the present invention relates to an apparatus and method for dispensing material onto a substrate using one or more dispensing heads in a dispensing system.
BACKGROUND OR THE INVENTION
There are several types of prior art dispensing systems used for dispensing metered amounts of liquid or paste for a variety of applications. One such application is in the assembly of printed circuit boards and integrated circuit chips. In this application, dispensing systems are used in the process of encapsulating integrated circuits with an encapsulating material and in the process of underfilling flip integrated circuit chips with an encapsulent. Prior art dispensing systems are also used for dispensing dots or balls of liquid epoxy or solder paste onto circuit boards and integrated circuits. The liquid epoxy and solder are used to secure components or connect components, respectively, to a circuit board or to an integrated circuit. The dispensing systems described above include those manufactured and distributed by Speedline Technologies, Inc, the assignee of the present invention, under the name CAMALOT™.
The dispensing systems described above are typically used in an electronics manufacturing facility in an automated assembly line with other equipment used in a circuit board or integrated circuit manufacturing process. The other equipment in-line with the dispensing systems may include, for example, pick and place machines, which place components on circuit boards, or reflow ovens that are used to heat materials, such as solder paste, dispensed onto the circuit boards or integrated circuits.
In a typical dispensing system, a pump and dispenser assembly is mounted to a moving assembly for moving the pump and dispenser assembly along three mutually orthogonal axes (x, y, z) using servomotors controlled by a computer system or controller. To dispense a dot of liquid on a circuit board at a desired location, the pump and dispenser assembly is moved along the horizontal x and y axes until it is located over the desired location. The pump and dispenser assembly is then lowered along the vertical z axis until the nozzle of the pump and dispenser assembly is at an appropriate dispensing height over the board. The pump and dispenser assembly dispenses a dot of liquid, is then raised along the z axis, moved along the x and y axes to a new location, and is lowered along the z axis to dispense the next liquid dot.
During the manufacture of circuit boards, it is sometimes necessary, or desirable, to dispense two different liquids or pastes onto a circuit board or to dispense different volumes of the same material. Dispensing systems have been designed that can dispense one of a number of dispensing materials from one dispensing head. One example of such a dispensing system is described in U.S. patent application Ser. No. 08/519,146, filed Aug. 24, 1995, now U.S. Pat. No. 5,795,390 which is incorporated herein by reference. These dispensing systems typically are only able to dispense one material at a time, and the throughput of product in these systems may be less than desired because of the time required to dispense multiple materials serially using one dispensing head.
To overcome the throughput problem, two dispensing systems may be placed adjacent to each other with the first dispensing system dispensing one material and the second dispensing system dispensing a second material. This solution is expensive since two complete machines are used, and since additional manufacturing space is required. In typical operations, manufacturing floor space is limited, and it is desirable to limit the “footprint” of each manufacturing system on the manufacturing floor.
SUMMARY OF THE INVENTION
In one general aspect, the invention features a dispensing system for dispensing material onto a substrate. The dispensing system includes a frame, a support, coupled to the frame, that supports the substrate at a dispensing position in the dispensing system, and a dispensing head, coupled to the frame, that dispenses the material onto the substrate. The dispensing head includes a motor unit having a first motor coupled to an output drive mechanism and a dispensing unit, removably coupled to the motor unit, having a material outlet from which the dispensing material is dispensed. The dispensing unit has a dispensing mechanism coupled to the material outlet and coupled to the output drive mechanism of the motor unit such that operation of the first motor causes the dispensing mechanism to dispense material through the outlet.
The motor unit can include a second motor operatively coupled to a lift plate to provide vertical movement of the lift plate, and the dispensing unit can further include an adapter that couples to the lift plate to provide vertical movement of the dispensing mechanism to lower the dispensing mechanism towards the substrate for dispensing.
The output drive mechanism can include a first gear and the dispensing mechanism can include a second gear disposed to engage the first gear. The first gear can have elongated teeth and the second gear can be constructed and arranged to move vertically when the dispensing mechanism is lowered while maintaining engagement with the elongated teeth of the first gear. The dispensing unit and the motor unit can be constructed and arranged to provide kinematic mating between the dispensing unit and the motor unit. The dispensing unit can include a plurality of electrical contacts, and the motor unit can include a plurality of electrical contacts for operatively coupling to the electrical contacts of the dispensing unit. The dispensing unit can include electrical identification circuitry coupled to the plurality of electrical contacts that provides identification of characteristics of the dispensing unit. The electrical identification circuitry can include a data storage element containing calibration data for the dispensing unit. The dispensing unit can include an inlet pneumatic port and the motor unit can include an output pneumatic port that mates with the inlet pneumatic port of the dispensing unit to provide pressurized air to the dispensing unit. The dispensing unit can include a syringe coupled to the dispensing mechanism to provide dispensing material to the dispensing mechanism, and the syringe can be constructed and arranged to move vertically when the dispensing mechanism is lowered. The dispensing system can be constructed and arranged such that the dispensing mechanism can be moved vertically over a range of movement, and such that over at least a portion of the range of movement, the syringe does not move with the dispensing mechanism. The motor unit can further include a second output drive mechanism and the dispensing unit can further include a second dispensing mechanism.
In another general aspect, the invention features a method of dispensing material onto a substrate using a dispensing system. The method includes steps of coupling a motor unit to the dispensing system, the motor unit having a motor with an output drive mechanism, coupling a dispensing unit to the motor unit such that a dispensing mechanism of the dispensing unit is operatively coupled to the output drive mechanism of the motor, and operating the motor to cause material to be dispensed onto the substrate from the dispensing mechanism.
The output drive mechanism can include a first gear and the dispensing mechanism can include a second gear, and the step of coupling the dispensing unit to the first motor unit can include engaging the second gear in the first gear. The method can further include a step of vertically moving the dispensing mechanism toward the substrate while maintaining the motor unit and the dispensing unit in a fixed position. The step of coupling the dispensing unit to the motor unit can provide a kinematic coupling between the motor unit and the di
Crouch Kenneth C.
Prentice Thomas C.
Prescott Brian P.
Scott Murray D.
Mintz Levin Cohn Ferris Glovsky & Popeo P.C.
Speedline Technologies, Inc.
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