Patent Publication Number: US-2023156991-A1

Title: Component placement systems, multi-pipette placement heads, and methods of using the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 63/279,461, filed Nov. 15, 2021, the content of which is incorporated herein by reference. 
    
    
     FIELD 
     The invention relates to component placement systems, and more particularly, to improved component placement systems including placement heads having a plurality of pipettes, and methods of using the same. 
     BACKGROUND 
     In the electronics assembly industry, pick and place systems (i.e., component placement systems) are used for the placement of electronic components. In certain placement systems, a plurality of tools (e.g., pick up tools, pipettes, nozzles, etc.) may be carried by a single placement head. Thus, a plurality of electronic components (each carried by a distinct tool) may be carried at the same time by the placement head. 
     It would be desirable to provide improved component placement systems that overcome one or more of the deficiencies of conventional placement systems including as related to performance, accuracy, speed of operation. 
     SUMMARY 
     According to an exemplary embodiment of the invention, a component placement system is provided. The component placement system includes a placement head including a plurality of pipettes. Each of the plurality of pipettes is configured to pick and place components. The placement head includes a plurality of controllers, each of the plurality of controllers being configured to control a respective one of the plurality of pipettes. 
     According to another exemplary embodiment of the invention, another component placement system is provided. The component placement system includes a placement head including a plurality of placement assemblies. Each of the plurality of placement assemblies includes (i) a controller; (ii) a pipette; (iii) a rotary encoder for detecting a rotary position of the pipette; and (iv) a z-axis position encoder for detecting a z-axis position of the pipette. For example, such a rotary encoder may detect a rotary position of the respective one of the plurality of pipettes (e.g., see rotary encoder  160  in  FIG.  3 A ). For example, part of the rotary encoder may be on the pipette (e.g., on the shaft of the pipette, or some rotating element carrying the pipette). 
     According to yet another exemplary embodiment of the invention, another component placement system is provided. The component placement system includes a placement head including a plurality of placement assemblies. Each of the plurality of placement assemblies includes (i) a controller, (ii) a pipette, and (iii) a force sensor for detecting an impact force of the pipette during placement of a component. For example, such a force sensor may detect an impact force of the respective one of the plurality of pipettes during placement of a component (e.g., see force sensor  164  in  FIG.  3 A ). 
     Aspects of the invention also relate to methods of using the aforementioned component placement systems, or any component placement system within the scope of the invention. For example, according to yet another exemplary embodiment of the invention, a method of operating a component placement system is provided. The method includes the steps of: providing a placement head including a plurality of pipettes and a plurality of controllers, each of the plurality of controllers being configured to control a respective one of the plurality of pipettes; collecting a plurality of components with the plurality of pipettes; and placing the plurality of components with the plurality of pipettes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is best understood from the following detailed description when read in connection with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawings are the following figures: 
         FIG.  1    is a block diagram side view illustrating a component placement system in accordance with an exemplary embodiment of the invention; 
         FIGS.  2 A- 2 C  are perspective views of various placement heads in accordance with various exemplary embodiments of the invention; 
         FIG.  3 A  is a detailed block diagram view of the placement head of  FIG.  2 A , along with additional elements of a component placement system, in accordance with an exemplary embodiment of the invention; 
         FIG.  3 B  is a perspective view of a elements of a z-axis motion system used in connection with placement head of  FIG.  3 A , in accordance with an exemplary embodiment of the invention; 
         FIGS.  4 A- 4 B  are block diagram top views illustrating additional component placement systems in accordance with additional exemplary embodiments of the invention; and 
         FIG.  5    is a flow diagram illustrating a method of operating a component placement system in accordance with an exemplary embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     As used herein, the term “component” refers to any type of electronic component to be placed by a component placement system. Exemplary components include capacitors, resistors, semiconductor die or chips, etc. 
     According to certain exemplary embodiments of the invention, a component placement system is provided including one or more placement heads, each of the placement heads including multiple individual pipette cartridges (also referred to herein as “control modules”), which are implemented as a functional exchangeable sub module. 
     Aspects of the invention provide sensitive electronics at the pipette (or placement assembly including the pipette), and enable modularity within a placement head. As used herein, the term “placement assembly” refers to an assembly including a pipette and a respective control module (where the control module includes a controller for controlling motion of the pipette). Thus, aspects of the invention provide exchangeable placement assemblies that include a control module and a pipette. Such placement assemblies (specific to each pipette) may include integrated sensor and drive electronics. 
     Aspects of the invention relate to placement heads including a plurality of pipettes (and corresponding control modules for each pipette). The pipettes may be arranged in an array configuration (e.g., in a linear array as in  FIGS.  1  and  2 A- 2 C , in a matrix array as shown in  FIG.  4 B , etc.), in an turret configuration (e.g., see  FIG.  4 A ), etc. 
     In accordance with the invention, each placement head may include (and carry) a plurality of pipettes. For example, a placement head may include: at least 3 pipettes; at least 5 pipettes; at least 10 pipettes; etc. 
     As will be appreciated by those skilled in the art, a placement head may carry a plurality of components (e.g., one component carried by each of a plurality of pipettes). Typically, a component held by a pipette is rotated and/or generally aligned. Through an inspection process (e.g., using an imaging system including a camera), it may be determined that a component may require further alignment (e.g., using a rotary motor for the given pipette). In accordance with the invention, because each of the pipettes is included in a placement assembly with a respective control module (where the control module controls at least one of z-axis motor current, and theta axis motor current), adjustments may be made in preparation for placing a second component while the placement head is placing a first component. More specifically, while the first component is being placed by a first pipette of the placement head, a relative position of one of more other components held by respective pipettes may be adjusted (e.g., adjusted about a theta axis). In other examples, while a first pipette may be engaged in a pick or place operation (or other motion), z-axis motion of a second pipette (or pipettes) may be commenced. More specifically, in a pick operation, while a first pipette is picking a first component, a second pipette (or pipettes) may begin their descent toward picking another component to save time. Likewise, in a place operation, while a first pipette is placing a first component, a second pipette (or pipettes) may begin their descent toward placing another component (or components) to save time. Of course, such preparation in any of the above examples may be made for multiple components (not just a second component) while picking or placing the first component. This provides for an efficient placement process. 
     In accordance with aspects of the invention, each pipette may be controlled individually, all of the time. This is important for alignment processes (e.g., using an inspection camera between the component picking process and the component placement process). 
     Referring now to the drawings,  FIG.  1    illustrates a component placement system  100 . Component placement system  100  includes a plurality of placement heads  100   a   1 - 100   an , etc. Each placement head includes a plurality of control modules  102   a   1 - 102   an  configured for carrying pipettes in an array configuration (e.g., see pipettes  108  in 
       FIG.  2 A ). Component placement system  100  also includes a component supply  106  including a plurality of components  106   a  (e.g., where component supply  106  may include a number of component sources, including components of different types, etc.). Component placement system  100  also includes imaging system  107 , and support structure  104  for supporting a workpiece  110  (or a plurality of workpieces  110 ) configured to receive components  106   a  from pipettes of one or more placement heads  100   a   1 - 100   an.    
     Each component placement head  100   a   1 - 100   an  collects components  106   a  from component supply  106 . For example, the various pipettes included in a component placement head (e.g., component placement head  100   a   1 ) each collect a respective component  106   a  (e.g., using vacuum to collect and hold a component  106   a ). After collecting the components  106   a , the component placement head (e.g., component placement head  100   a   1 ) moves to a position with respect to imaging system  107  such that a component  106   a  may be imaged with respect to a part of the pipette (or other part of the control module) carrying that component. In a specific example, the component placement head may be moved to a position above an upward looking camera included in imaging system  107 . Imaging system  107  is used to collect positional data (e.g., relative positional data between (i) the component  106   a  held by a pipette, and (ii) the pipette itself or some other part of the control module). Using this positional data, correction may be made (e.g., adjusted about a theta axis) for accurately placing the component  106   a  on workpiece  110 . 
       FIG.  2 A  illustrates placement head  100   a   1  (e.g., placement head  100   a   1  from  FIG.  1   ). Placement head  100   a   1  includes includes a plurality of placement assemblies  102   a . Each of the placement assemblies  102   a  includes one of control modules  102   a   1 - 102   an , and a corresponding pipette  108  (e.g., where pipette  108  is carried by the respective control module, and where the plurality of pipettes are arranged in an array configuration) (in  FIG.  2 A , the right most pipette  108  is shown extended further downward as compared to the other pipettes  108 ). Pipette  108  is illustrated carrying a component  106   a . For example, each of control modules  102   a   1 - 102   an  may be the same type of control module (e.g., where such control modules may carry the same type of pipette). However, it is understood that different types of control modules may be carried by placement head  100   a   1 . For example,  FIG.  2 B  illustrates another placement head  100   a   1 ′ including control modules  102   a   1 ′ (where control modules  102   a   1 ′ are different from control modules  102   a   1 - 102   an  from  FIG.  2 A ) (in  FIG.  2 B , only one pipette  108  is shown, but see  FIG.  2 A  for other pipettes). In another example,  FIG.  2 C  illustrates another placement head  100   a   1 ″ including a control module  102   a   1 ″ (where control module  102   a   1 ″ is different from control modules  102   a   1 - 102   an  from  FIG.  2 A ) (in  FIG.  2 C , only one pipette  108  is shown, but see  FIG.  2 A  for other pipettes). As shown in  FIG.  2 C , control module  102   a   1 ″ is illustrated as a larger module as compared to control module  102   a   1 . As will be appreciated by those skilled in the art, a larger module may be used to place a larger component  106   a , to provide a larger placement force, to carry a larger pipette, etc. For example, the geometry of a pipette  108  may differ depending on the size of the component to be picked and placed. Of course, this is just one example of different types of control modules (and corresponding pipettes). A critical aspect of the invention is that, because of the modular nature of the placement assemblies (including control modules and pipettes) of the placement head, different types of placement assemblies may be utilized in a single placement head. 
     Thus, in accordance with various exemplary aspects of the invention, a placement head includes modules for placing components of different types, and uses a combination of pipettes with different performance specifications for placement of the components of different types. 
       FIG.  3 A  is a detailed block diagram view of placement head  100   a   1  (e.g., placement head  100   a   1  from  FIG.  1   ), including one of the placement assemblies  102   a  (including one of the plurality of control modules  102   a   1  and a corresponding pipette  108 ), as well as other elements of component placement system  100 . Certain detailed elements (and functions) of control module  102   a   1  are also shown. 
       FIG.  3 A  illustrates a computer  134  (e.g., a computer included in component placement system  100 , a computer external to component placement system  100 , etc.) for providing commands to placement head controller  132 , and for receiving the status of the commanded actions from placement head controller  132 . Thus, placement head controller  132  executes commands received from computer  134  and send the status of commands to computer  134 . According to certain embodiment of the invention, placement head controller  132  (e.g., a single placement head controller of placement head  100   a   1 ) calculates the move profiles, and/or adapt the move profiles, of a pipette  108 —for example, based on feedback (e.g., based on feedback from force sensor  164 , to limit the forces on the component during the component handling (picking and placing)). Likewise, according to certain embodiment of the invention, placement head controller  132  calculates the required motor current (e.g., for z-axis motor coil  170  and/or rotary motor  162 ) based on required position and feedback from the motor encoders (e.g., z-axis position encoder  154  and/or rotary encoder  160 ). 
     Thus, in accordance with certain aspects of the invention, placement head controller  132  controls motion trajectories for the each of the plurality of pipettes  108  via communication with the respective one of the plurality of control modules  102   a   1 - 102   an  (through the controller  144  of such control module). 
     Placement head controller  132  communicates with each of the respective controllers  144  (in corresponding control modules  102   a   1 - 102   an ), by sending current command signals to controller  144 , and receiving sensor/encoder data via controller  144 . Thus, placement head controller  132  communicates in parallel with each of the control modules  102   a   1 - 102   an . Placement head controller  132  also communicates with the vacuum control system  128 , to control vacuum at each of the pipettes  108 . 
     Thus, in certain exemplary embodiments of the invention, as shown in  FIG.  3 A , placement head controller  132  controls vacuum for the plurality of pipettes. However, in other embodiments of the invention, each of the plurality of control modules (e.g., control module  102   a   1 - 102   an ) controls vacuum for the respective one of the plurality of pipettes. 
     Controller  144  (one of which is included in each control module, such as control module  102   a   1 ) controls the commanded electrical current signal from placement head controller  132  to each of (i) z-axis power stage  148  (providing the electrical current to z-axis motor coil  170 ) and (ii) rz power stage  146  (providing the electrical current to rotary motor  162 ). As such, each of the plurality of control modules  102   a   1 - 102   an  (using controller  144 ) controls at least one of (i) z-axis motor current control (through z-axis power stage  148 ) and (ii) theta axis motor current control (through rz power stage  146 ). 
     Controller  144  also serializes data (e.g., IO data, position data, force data, etc.) including data from z-axis position encoder  154 , rotary encoder  160 , and force sensor  164 , and provides that data to placement head controller  132 . Placement head controller  132  may include, for example, multiple serial interfaces (e.g., one for each pipette and associated placement assembly) that can operate in parallel. 
     Thus, in accordance with various exemplary aspects of the invention, through their respective controllers  144 , each of the plurality of control modules  102   a   1 - 102   an  may be in communication with at least one of (i) a primary motion controller for the placement head (e.g., see placement head controller  132  in  FIG.  3 A ), and (ii) a primary motion controller of the component placement system (e.g., see computer  134  in  FIG.  3   , acting as a motion controller). 
     Electrical power is provided to placement head  100   a   1  (including each of the placement assemblies  102   a , and their respective control module  102   a   1 - 102   an ) from an external power source  136 . In the exemplary configuration shown in  FIG.  3 A , power source  136  provides power to placement head  100   a   1  via power interface  138 , where power interface  138  feeds all interval device and components of placement head  100   a   1 . Power is provided to each control module (e.g., control module  102   a   1 ) from power interface  138  using respective power interface  142 . 
     An external vacuum supply  150  provides vacuum to placement head  100   a   1 . Vacuum is used to hold a component on pipette  108  through vacuum control system  128 . Vacuum control system  128  includes various elements to maintain proper vacuum at pipette  108  (e.g., valves for controlling the vacuum level, blower valves, pressure sensors to measure the vacuum level, etc.). An external compressed air supply  152  provides compressed air to blow off component from pipette  108  (e.g., during placement). 
     A z-axis motion system  300  (e.g., a linear z-servo motor) is provided for controlling z-axis motion of pipettes  108  (see  FIG.  3 B ). Z-axis motion system  300  includes z-axis motor magnets  130  in housing  300   a —where the z-axis motor magnets  130  are included as part of placement head  100   a   1  for all control modules  102   a   1 - 102   an  of the placement head  100   a   1 . In the illustrated example, the z-axis motor magnets  130  act as the stator part of the z-axis motion system  300 . Z-axis motion system  300  also includes a plurality of z-axis motor coils  170  which act as the moving part of z-axis motion system  300 . The various z-axis motor coils  170  are included in their respective control module (e.g., control module  102   a   1 ). 
     In the specific implementation shown in  FIG.  3 A , based on a control signal from controller  144 , electrical current is provided from z-axis power stage  148  to a respective z-axis motor coil  170 . This electrical current generates a force to move the pipette along the z-axis (i.e., along a vertical axis of component placement system  100 ). That is, z-axis power stage  148  provides the electrical current running through the z-axis motor coil  170  for the given control module (and associated pipette  108 ). A z-axis position encoder  154  measures a position along the z-axis (e.g., some relative position to provide position data of the pipette along the z-axis). In the illustrated embodiment in  FIG.  3 A , a linear guide  156  is provided, for example, to act as a bearing system to guide motion of the pipette along the z-axis. 
     In the specific implementation shown in  FIG.  3 A , based on a control signal from controller  144 , electrical current is provided from rz power stage  146  (where “rz” means rotation about the z-axis) to rotary motor  162 . That is, rz power stage  146  provides the electrical current to rotary motor  162 . Rotary motor  162  generates a torque proportional to the electrical current provided by rz power stage  146  to provide for rotation of pipette  108  about the z-axis. Rotary encoder  160  measures a position of rotation around the z-axis, and provides corresponding positional data to controller  144  (where controller  144  is in communication with placement head controller  132 , and computer  134 ). 
     Force sensor  164  measures the force applied on the component by a pipette  108  during the pick and place actions. Force sensor  164  may include an integrated spring (e.g., a pre-loaded spring) or other flexible element. For example, compression of the integrated spring (or other flexible element) can be measured and translated into a force value. Force sensor  164  may also be used to as a “touch” sensor, for sensing contact between the pipette and a component (at a pick location) and/or for sensing contact between the component and a surface (at a place location). Pipette interface  166  is a mechanical interface to connect pipette  108  to force sensor  164 . 
     The various aspects of component placement system  100  shown in  FIG.  1    (and detailed embodiments shown in  FIGS.  2 A- 2 C  and  FIGS.  3 A- 3 B ) are not limited to a component placement system having that exact configuration. For example, the concept of different types of placement assemblies (e.g., see  FIGS.  2 B- 2 C ), or the details shown and described in connection with  FIGS.  3 A- 3 B  (including details regarding the placement head  100   a   1 , placement assembly  102   a , or other details shown in  FIGS.  3 A- 3 B ), are applicable to component placement systems  400   a - 400   b  shown in  FIGS.  4 A- 4 B , or any other component placement system within the scope of the invention. 
       FIG.  4 A  illustrates another component placement system  400   a . Component placement system  400   a  includes a plurality of placement heads  100   b   1 - 100   bn . Each placement head includes a plurality of control modules  102   b   1 - 102   bn  configured for carrying pipettes in a turret configuration. Component placement system  400   a  also includes a component supply  106  including a plurality of components  106   a  (e.g., where component supply  106  may include a number of component sources, including components of different types), an imaging system  107  (described above in connection with  FIG.  1   ), and a support structure  104  supporting a workpiece  110  (or a plurality of workpieces  110 ) configured to receive components  106   a . Each placement head (e.g., placement head  100   b   1 ) is configured to rotate as shown in  FIG.  4 A  for positioning of the relevant control modules (and associated pipette, not shown for simplicity) for pick and place operations. 
       FIG.  4 B  illustrates yet another component placement system  400   b . Component placement system  400   b  includes a plurality of placement heads  100   c   1 - 100   cn . Each placement head includes a plurality of control modules  102   c   1 - 102   cn  configured for carrying pipettes in a array configuration (in  FIG.  4 B , a matrix array). Component placement system  400   b  also includes a component supply  106  including a plurality of components  106   a  (e.g., where component supply  106  may include a number of component sources, including components of different types), an imaging system  107  (described above in connection with  FIG.  1   ), and a support structure  104  supporting a workpiece  110  (or a plurality of workpieces  110 ) configured to receive components  106   a . Each placement head (e.g., placement head  100   c   1 ) is configured for motion along a plurality of horizontal axes for positioning of the relevant control modules (and associated pipette, not shown for simplicity) for pick and place operations. 
       FIG.  5    is a flow diagram illustrating an exemplary method in accordance with the invention. As is understood by those skilled in the art, certain steps included in the flow diagrams may be omitted; certain additional steps may be added; and the order of the steps may be altered from the order illustrated-all within the scope of the invention. 
       FIG.  5    is a flow diagram illustrating a method of operating a component placement system. At Step 500, a placement head including a plurality of pipettes and a plurality of controllers is provided (e.g., see placement heads  100   a   1  in  FIGS.  1  and  2 A and  3   , placement head  100   a   1 ′ in  FIG.  2 B , placement head  100   a   1 ″ in  FIG.  2 C , placement head  100   b   1  in  FIG.  4 A , and placement head  100   c   1  in  FIG.  4 B ). Each of the plurality of controllers is configured to control a respective one of the plurality of pipettes. At Step 502, a plurality of components are collected with the plurality of pipettes (e.g., collected from one or more component sources, such as component supply  106 ). The plurality of components may be collected as desired (e.g., one component being collected at a time, or any other method). After being collected, the plurality of components are held by the placement head, where each component is held by a respective pipette. At Step 504, the plurality of components are placed with the plurality of pipettes. The plurality of components may be placed as desired (e.g., one component being placed at a time, or any other method). For example, one component may be placed by a first pipette while other components are held by other pipettes. While being held by the other pipettes (during placement of the first component), adjustment may be made (e.g., position adjustments, force adjustments, etc.) in preparation for placement of the other components. 
     While  FIG.  3 A  illustrates a z-axis motion system (not illustrated for simplicity) including z-axis motor magnets  130  carried by one portion of placement head  100   a   1 , and a z-axis motor coil  170  that is part of control module  102   a   1  (where the control module  102   a   1  may move with respect to a fixed part of placement head  100   a   1 , for example, along a z-axis), this is just an example of a z-axis motion system, and the invention is not limited thereto. 
     Various aspects of the invention provide a number of advantages over conventional placement systems such as, for example: higher performance (more accurate motion, lower placement forces, and/or faster due to parallel motion); easy exchangeable spare parts (reducing down time); and configurable pipettes with different performance within one array. 
     Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.