Patent Application
20120171383
1. Field of the Disclosure The present disclosure relates generally to apparatus and methods for dispensing materials on a substrate, and more particularly to an apparatus and related methods for spray coating such materials on substrates.
2. Discussion of Related Art
Conformal coating is used in a variety of industries to protect various substrates from contaminates and damage. Conformal coating apparatus, such as spray coating machines, are well known in the art. Such apparatus may be configured to dispense a variety of materials onto substrates. By selectively spraying a preprogrammed path with a narrow angled spray valve the coating can be placed accurately so that the substrate is coated where necessary and not coated where coating would damage or otherwise negatively effect the function of the part. Typical conformal coating systems use Cartesian-type movement systems configured to achieve movement along three to five axes of movement, and are fitted with a variety of dispensing heads to transfer the material to the substrate in a controlled fashion.
One aspect of the present disclosure is directed to a conformal coating apparatus for depositing material on a substrate. In one embodiment, the conformal coating apparatus comprises a housing, a head configured to deposit material and a movement mechanism coupled to the housing and to the head. In a certain embodiment, the movement mechanism includes a movable member coupled to the head, at least three actuators coupled to the housing, each actuator having a motor with a rotating portion configured to rotate about an axis of the actuator, and at least three linkages respectively connecting the movable member to the at least three actuators. Each linkage connects the rotating portion of its respective actuator to the movable member. Each linkage has a single bar having a first end a second end. The first end of the single bar is coupled to the rotating portion of its respective actuator. A first articulated connector is coupled to the second end of the single bar. Each linkage further has two parallel bars, each parallel bar having a first end and a second end. The first ends of the two parallel bars are coupled to the first articulated connector. A second articulated connector is coupled to the second ends of the parallel bars and the movable member. A controller is coupled to the movement mechanism and the head. The controller is configured to control the automated movement of the movement mechanism to provide at least x-axis, y-axis and z-axis.
Embodiments of the conformal coating apparatus may further include a substrate support coupled to the housing. The substrate support includes a pair of support elements configured to support one or more substrates and a pair of frame support elements secured to the housing. The frame support elements are configured to support the support elements. The first articulated connector includes an axial bearing member coupled to the single bar and the first ends of the two parallel bars. The axial bearing member has a bearing that enables the axial bearing member to pivot with respect to the single bar. The axial bearing member further has two ends, each end being pivotally connected to the first end of its respective parallel bars. The second articulated connector includes an axial bearing member coupled to the movable member and the second ends of the two parallel bars. The axial bearing member has a bearing that enables the axial bearing member to pivot with respect to the movable member. The axial bearing member further has two ends, each end being pivotally connected to the second end of its respective parallel bars. In one embodiment, the controller is coupled to the at least three actuators. In another embodiment, the head includes a spray valve connected to a material supply. A regulator controls the delivery of material from the material supply to the spray valve. In yet another embodiment, the head includes a dispenser connected to a material supply. A regulator controls the delivery of material from the material supply to the dispenser.
Another aspect of the disclosure is directed to a method of depositing material on a substrate. In one embodiment, the method comprises: positioning a dispensing head (including a spray valve or a dispenser) proximate to a substrate; and controlling the automated movement of the dispensing head to deposit material on the substrate by moving the dispensing head in x-axis, y-axis and z-axis directions. The controlling the automated movement of the dispensing head is achieved by the movement mechanism.
The present disclosure will be more fully understood after a review of the following figures, detailed description and claims.
The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. Reference is made to the following drawing figures, which are incorporated herein by reference and in which:
For the purposes of illustration only, and not to limit the generality, the present disclosure will now be described in detail with reference to the accompanying figures. This disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The apparatus of embodiments disclosed herein is capable of other embodiments and of being practiced or being carried out in various ways. Also the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” “having,” “containing” “involving,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.
For purposes of illustration, embodiments of the present disclosure will now be described with reference to a conformal coating apparatus used to spray coat or otherwise dispense material on an object. With certain applications, conformal coating materials may be applied to printed circuit boards to protect against damage caused by the environment in which the circuit board operates, such as moisture, dust, chemicals and temperature. The coating can be achieved with a conformal coating apparatus that includes a spray valve applicator capable of applying material on the substrate in selective areas. In certain examples, flow rates and material viscosity are programmed into a computer system of the apparatus to control the applicator so that a desired coating thickness is maintained.
In certain embodiments, the material includes parylene. In other embodiments, the material includes room temperature vulcanizing (RTV) silicone rubber, glues, sealants and other liquid coatings. However, other materials, including polymeric materials, may be employed with the apparatus disclosed herein. In other examples, solvent-based, water-based and solid materials may be employed. In other embodiments, objects may include, but are not limited to, electronic substrates, such as semiconductor wafers and printed circuit boards, medical devices, such as stents, and any other object or component requiring thin coatings of material. For example, and without limitation, objects used in the electronics, military, medical and automotive industries may be coated using the apparatus and methods disclosed herein. One skilled in the art will appreciate that embodiments of the present disclosure are not limited to conformal coating apparatus capable of spraying or dispensing protective materials onto electronic substrates, but rather, may be used in any application intended to coat objects.
In addition, although a particular conformal coating apparatus platform is disclosed herein, the conformal coating head of embodiments disclosed herein may be used with other types of platforms designed to manipulate such heads. In one embodiment, the platform may include spray coating platforms sold by Specialty Coating Systems, Inc. of Indianapolis, Ind. under the trade name Precisioncoat.
In a certain embodiment, a conformal coating apparatus includes a housing and a head (such as a spray valve or dispenser) that is configured to dispense or otherwise deposit material. As discussed above, traditional conformal coating machines have a gantry that is configured to provide x-axis, y-axis and z-axis movement. In some embodiments, the traditional gantry may also be configured to rotate about the z-axis and pivot about a point on the z-axis. The conformal coating apparatus of the present disclosure includes a movement mechanism that is coupled to the housing and to the head. The head may be manipulated by a controller coupled to the movement mechanism and the head. Specifically, the controller may be configured to control the automated movement of the movement mechanism to provide nearly unlimited freedom of movement of the head.
In one embodiment, the movement mechanism embodies what is known in the industry as a “delta robot” which is capable of generating three degrees of freedom of movement—three translational. In the past, the delta robot, or a parallel arm robot, was particularly useful in manipulating light and small objects at very high speeds. The delta robot is a parallel robot, which means there is more than one kinematic chain from a base of the robot to a dispensing head. A feature of the delta robot is the use of parallelograms to achieve the four degrees of movement. These parallelograms restrict the movement of the dispensing head to pure translation, i.e., movement in the x-axis, y-axis and z-axis directions. With traditional delta robots, a base of the delta robot is mounted above the workspace. The delta robot includes actuators that are located on the base. The delta robot typically includes three middle jointed arms, which extend from the base. These arms can be made of lightweight composite material. The ends of the three arms are connected to a small platform on which the dispensing head is mounted. Actuation of the input links will move the platform in the x-axis, y-axis and z-axis directions. Actuation can be done with linear or rotational actuators. From the base, a fourth leg extends to the middle of the platform to give the dispensing head a fourth, rotational degree of freedom. Because the actuators are all located in the base, and the arms are made of a composite material the moving parts of the delta robot have a small inertia. This allows for very high accelerations.
Referring now to the drawings, and more particularly to
In one embodiment, the controller 30 may be configured to have a suitable operating system (e.g., Windows XP® offered by Microsoft Corporation of Redmond, Wash.) with application specific software to control the operation of the conformal coating apparatus 10. In a certain embodiment, an operator of the conformal coating apparatus 10 may operate the apparatus either manually by manipulating a keyboard (not shown) and a mouse (not shown) provided with the controller 30 and/or the control panel 28 or automatically by preprogramming the controller by means of the keyboard and mouse through the controller and/or the control panel.
Still referring to
Specifically, a front door includes a first panel 36 of see-through material, such as glass or plastic, secured to the front 16 of the housing 12 adjacent the top 24 of the housing, a second, larger panel 38 of see-through material positioned below the first panel of material, and three hinges, each indicated at 40, which hingedly attach the second panel to the first panel. A handle 42 is provided to pivot the second panel 38 about the hinges 40 to access the interior 14 of the housing 12. The sides 20, 22 of the housing 12 each have a door that includes an outer frame 44 and a panel 46 of see-through material supported by the frame. For each side 20, 22, the frame 44 is securely attached to the housing 12 at the side of the housing 12 or, in other embodiments, may be hingedly connected to the housing at the bottom of the side of the housing so that the door is opened by pivoting the door about the bottom of the door. Each side door may include a handle.
As shown in
Referring to
As mentioned above, the dispensing head 34 includes the spray valve 58 that is designed to spray material on the substrates 68 that are positioned on the substrate support 62.
Each actuator 76 includes a case 84, which is mounted on the bottom 74 surface of the top 24 of the housing 12. The case 84 supports a motor 86 having a rotating portion 88 that is coupled to its respective linkage 78 and rotates about a long axis of the case 84. The arrangement is such that the rotating portion 88 is coupled to the controller 30 to control the rotation of the rotating portion 88. Openings 90 are provided in the top 24 of the housing 12 so that the actuators 76 may be coupled to the controller 30. Another opening 92 is provided so that material can be fed from the canister 52 or 54 to the dispensing head 34.
Referring to
As illustrated in
Each linkage 136 includes a single bar 150 having a first end (not designated) that is connected to the rotating portion 146 and a second end (not designated). Each linkage 136 further includes two parallel bars, each indicated at 152, each parallel bar having a first end (not designated) that is connected to the single bar 150 and a second end (not designated) that is connected to the movable member 132. A first articulated connector, generally indicated at 154, is provided to connect the second end of the single bar 150 to the first ends of the two parallel bars 152. A second articulated connector, generally indicated at 156, is provided to connect the second ends of the two parallel bars 152 to the movable member 132.
As shown in
When dispensing materials on electronic substrates, such as printed circuit (or wiring) boards, accuracy, functionality and speed are important considerations. In certain embodiments, a conformal coating apparatus includes a spray coating valve that is mounted on a movement mechanism that is capable of providing three axes of movement, i.e., x-axis, y-axis and z-axis movement. Rotational movement may be achieved by a separate motor provided on the moveable member to rotate the dispensing head in a desired direction. In contrast to Cartesian gantry systems providing three axes of movement and having three large and heavy linear actuators arranged in x-axis, y-axis, and z-axis configurations, the apparatus of the present embodiment uses three actuators and linkages to create motion in the three directions with considerably less mass and cost. The configuration of the conformal coating apparatus of the present disclosure is simple in design, and the smooth and quiet motion of the movement system maintains a stable platform that yields more uniform results than conventional selective sprayers.
The conformal coating apparatus of the present disclosure can be configured to include air atomized spraying heads, dispensing heads, swirl-coating nozzles, dual-mode nozzles, and jetting heads. Coating applications using a needle to dispense the material may include needle valves and auger valves. Each of these valves can be mounted on the gantry system or multiple heads can be mounted at the same time. An additional axis of motion can be fitted to the movement system thereby enabling four, five or six axes of motion to further add flexibility to place the coating as necessary on substrates. In such an embodiment, the dispensing head may be configured to provide the one or more additional axes of motion.
The movement system may embody a small tabletop selective coater that has three axes of motion capability and the ability to carry any of the coating technologies disclosed herein. By comparison, Cartesian gantry systems and similar gantries require more space and weigh more to accommodate the same work area. In one embodiment, the housing 12 of the conformal coating apparatus 10 is twenty-eight inches wide by twenty-eight inches deep by twenty-four inches high, and weighs approximately ninety pounds.
During operation, when spraying material on a substrate, the dispensing head is positioned proximate to the substrate. The controller controls the automated movement of the dispensing head to spray material on the substrate by moving the dispensing head in x-axis, y-axis and z-axis directions by means of the movement mechanism. The dispensing head may be configured to spray particular materials. For example, the dispensing head may be configured with a particular type of nozzle suitable for spraying a conformal coating material. In one embodiment, the dispensing head may be an assembly of separate components or provided by a suitable manufacturer, such as EFD, Inc. of East Providence, R.I. or Graco Inc. of North Canton, Ohio.
During operation, when spraying material on a substrate, such as an electronic substrate, the dispensing head is positioned proximate to the substrate. The controller controls the automated movement of the dispensing head to spray material on the substrate by moving the dispensing head in x-axis, y-axis, z-axis directions by means of the movement mechanism. The controller, by means of controlling the operation of the actuators, controls movement (linear and rotational) of the movable member and the dispensing head.
Thus, it should be observed that the apparatus disclosed herein are particularly suited for positioning a dispensing head in a desired position without having to manually manipulate the dispensing head. The controller may be programmed to move the gantry assembly and the device to position the head. The automated movement of the head saves time as well as enables the operation to exactly position the head for optimal operation.
Having thus described at least one embodiment of the present disclosure, various alternations, modifications and improvements will readily occur to those skilled in the art. Such alterations, modifications and improvements are intended to be within the scope and spirit of the disclosure. Accordingly, the foregoing description is by way of example only and is not intended to be limiting. The disclosure's limit is defined only in the following claims and equivalents thereto.
