Dispensing – With heating or cooling means – Heating only
Reexamination Certificate
1999-07-13
2001-04-17
Kaufman, Joseph A. (Department: 3754)
Dispensing
With heating or cooling means
Heating only
C137S884000
Reexamination Certificate
active
06216917
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a method and apparatus for dispensing material onto a substrate, and more specifically, to variable volume positive displacement systems and methods.
BACKGROUND OF 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 onto circuit boards and integrated circuits. The liquid epoxy and solder is used to connect components 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.
It is desirable to use positive displacement pumps in dispensing systems to effectively control the volume of material dispensed. U.S. Pat. Nos. 4,907,950 and 5,004,404 to Pierrat, which are incorporated herein by reference, disclose positive displacement pumps used to dispense variable quantities of material. The pumps disclosed by Pierrat include a crank-shaft drive that drives a number of pistons and cylinders to couple pressurized material at an inlet of the pump to an outlet of the pump to dispense the material. The pumps disclosed by Pierrat have up to four cylinders, each of which has an inlet port and an outlet port that are respectively coupled on a time-shared basis to the inlet and the outlet of the pump to provide dispensing.
Typical prior art pumps include a material distribution block to distribute material from the inlet of the pump to each of the inlet ports of the cylinders and from each of the outlet ports of the cylinders to the outlet of the pump. These distribution blocks are typically one piece blocks, constructed from a solid block of plastic or stainless steel, and have a number of passages drilled in the blocks to couple the inlet of the pump to each of the inlet ports and to couple each of the outlet ports to the outlet of the pump. For a pump having four cylinders, the distribution block typically has eight passages formed therein. The eight passages are coupled between 10 openings in the distribution block. Four of the openings are inlet port openings to couple to the inlet ports of the cylinders, four are outlet port openings to couple to the outlet ports of the cylinders, one of the openings is an inlet opening to couple to the inlet of the pump, and one of the openings is an outlet opening to couple to the outlet of the pump. Four of the eight passages are inlet passages that extend from one of the inlet port openings to the inlet opening, and the other four passages are outlet passages that extend from one of the outlet port openings to the outlet port.
While the distribution blocks are effective in distributing material between the cylinders and the inlet and the outlet on the pump, it is desirable to provide a distribution block that is less expensive to manufacture, and easier to clean. For some dispensing materials, such as those used in the assembly of printed circuit boards and integrated circuit chips, it is typically necessary to clean the dispensing material from a dispensing pump on a periodic basis to prevent dried material from clogging the pump.
SUMMARY OF THE INVENTION
A first aspect of the present invention is directed to a dispensing pump for dispensing a metered quantity of material onto a substrate. The dispensing pump includes an inlet for receiving dispensing material, an outlet from which the dispensing material is dispensed, a dispensing apparatus having a plurality of inputs and a plurality of outputs, a motor, coupled to the dispensing apparatus that controls flow of material from the plurality of inputs in the dispensing apparatus to the plurality of outputs in the dispensing apparatus, and a distribution apparatus coupled to the dispensing apparatus to transfer material from the inlet to the plurality of inputs and to transfer material from the plurality of outputs to the outlet. The distribution apparatus includes a plurality of plates coupled together to form the distribution apparatus.
At least one of the plurality of plates may include a heater to heat the dispensing material. The distribution apparatus may include a first plate that has an inlet channel extending from the inlet to a junction point and a plurality of concave channels formed in a first surface of the plate and extending from the junction point to couple the inlet to each of the plurality of inputs. The distribution apparatus can further include a second plate having a first surface mated with the first surface of the first plate to enclose each of the concave channels. The second plate may have a second surface having a plurality of concave channels extending from a junction point to couple each of the plurality of outputs to the junction point. The third plate may have a first surface mated with the second surface of the second plate to enclose each of the concave channels of the second plate. The third plate may further include a second surface substantially parallel to the first surface and include an output channel aligned with the junction point of the second plate and extending from the first surface of the third plate to the second surface of the third plate.
Another aspect of the present invention is directed to a method of dispensing material from a dispensing apparatus having a plurality of inputs and a plurality of outputs, and a motor that controls flow of material from the plurality of inputs to the plurality of outputs. The method includes steps of coupling a plurality of plates to the dispensing apparatus, the plurality of plates forming a plurality of channels to couple the plurality of inputs to a single material input and to couple the plurality of outputs to a single material output, applying dispensing material to the single material input, and dispensing material from the single material output. The method may further include steps of disassembling the plates from the dispensing apparatus and cleaning the dispensing material from the plates. The method may also include a step of heating the dispensing material in the plurality of plates.
Another aspect of the present invention is directed to a dispensing pump for dispensing a metered quantity of material onto a substrate, the dispensing pump includes an inlet for receiving dispensing material, an outlet from which the dispensing material is dispensed, a dispensing apparatus having a plurality of inputs and a plurality of outputs, a motor, coupled to the dispensing apparatus that controls flow of material from the plurality of inputs in the dispensing apparatus to the plurality of outputs in the dispensing apparatus, and means for transferring material from the inlet to the plurality of inputs and for transferring material from the plurality of outputs to the outlet, the means for transferring including a plurality of sections coupled together to form a plurality of distribution channels.
The dispensing pump may further include means for heating the dispensing material in the means for transferring.
REFERENCES:
patent: 3495604 (1970-02-01), Trask
patent: 4269212 (1981-05-01), Kaartinen
patent: 4542162 (1985-09-01), Rutherford et al.
patent: 4907950 (1990-03-01), Pierrat
patent: 5004404 (1991-04-01), Pierrat
patent: 5551481 (1996-09-01), Elrad, Jr.
patent: 0767413 (1980-09-01), None
Cartagena Melvin A.
Kaufman Joseph A.
Mintz Levin Cohn Ferris Glovsky and Popeo P.C.
Speedline Technologies, Inc.
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