Electromagnetic pick-and-place induction heater

Abstract

The apparatus and associated methods relate to a pick and place system that uses a magnetic core for both magnetic coupling with and heating of an assembly component. The magnetic core has a component engagement surface configured to magnetically and thermally engage the component. A controller is configured to supply both AC and DC currents to an induction coil wrapped around the magnetic core. The DC current supplied to the induction coil induces a magnetic field in the magnetic core, thereby magnetically attracting the component when engaged with the component engagement surface. The AC current supplied to the magnetic core induces and heats the magnetic core, thereby heating the component when engaged with the component engagement surface.

Description

Background Art

[0001] Pick and place tools are used to assemble, rework, and disassemble systems having attached components. The pick and place tool can be configured to engage a component (e.g., “pick” it), move the engaged component to a particular staging location, and place the component at that particular location. Some pick and place tools are also configured to attach or remove components from one location to where they are to be assembled or from where they are already assembled. The greater the capabilities such pick and place tools have, the more expensive and complex such systems would seem to be.

Summary of the Invention

[0002] An apparatus and related method relate to a system that heats, picks, and places components of an assembly. The system includes a magnetic core, an induction coil, and a controller. The magnetic core has a component engagement surface configured to magnetically and thermally engage components of the assembly. The induction coil is wound around the magnetic core. The controller supplies a DC signal and an AC signal to the induction coil. The DC signal induces a magnetic field in the magnetic core, thereby magnetically attracting the component when engaged with the component engagement surface. The AC signal induces heating of the magnetic core, thereby heating the component when engaged with the component engagement surface.

[0003] Some embodiments relate to a method of heating, picking, and placing components of an assembly. The method includes engaging a component at an engagement surface of a magnetic core. The method includes inducing a magnetic field in the magnetic core via a DC signal supplied to an induction coil wound around the magnetic core, thereby magnetically attracting the component when engaged with the component engagement surface. The method also includes inductively heating the magnetic core via an AC signal supplied to an induction coil wound around the magnetic core, thereby heating the component when engaged with the component engagement surface.

Brief Description of the Drawings

[0004]

Figure 1

Figure 2

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Modes for Carrying Out the Invention

[0005] The apparatus and related method relate to a pick-and-place system that uses a magnetic core for both magnetic coupling with an assembly component and heating of the assembly component. The magnetic core has a component engagement surface configured to magnetically and thermally engage a component. A controller is configured to supply both an AC current and a DC current to an induction coil wound around the magnetic core. The DC current supplied to the induction coil induces a magnetic field in the magnetic core, thereby magnetically attracting the component when engaged with the component engagement surface. The AC current supplied to the magnetic core inductively heats the magnetic core, thereby heating the component when engaged with the component engagement surface.

[0006] Figures 1A and 1B are perspective views of a pick-and-place tool removing a component adhesively attached from a system assembly. In Figures 1A and 1B, pick-and-place tool 10 is in the process of removing component 12 adhesively attached from system assembly 14. Pick-and-place tool 10 is configured to both heat and magnetically attract the adhesively attached component. Such heating and magnetic attraction are adjustable to either attach a component to system assembly 10 or remove a component such as component 12 adhesively attached from system assembly 10. Both such heating and magnetic attraction functions are performed by supplying current to induction coil 16.

[0007] Magnetic attraction is performed by supplying a DC current to the induction coil 16. Such a DC current conducted by the induction coil 16 induces a magnetic field, and the magnetic field is oriented to either attract or repel a magnetic object proximate to one side of the induction coil. Such a magnetic field can be directed by the core 18 around which the induction coil 16 is wound. Inductive heating is performed by supplying an AC current to the induction coil 16. Such an AC current can i) inductively heat a conductive core such as the core 18 around which the induction coil 16 is wound, ii) inductively heat any conductive material proximate thereto such that it is in the AC electromagnetic field induced by the AC current, and iii) conductively heat a component in contact with a conductive core such as the core 18 inductively heated by the AC current.

[0008] To remove the component 12 adhesively attached from the system assembly 14, the pick-and-place tool 10 moves the component head 20 including the induction coil 16 and the core 18 to align with the component 12 adhesively attached with the component head 20 in the x-y plane (e.g., a plane parallel to the horizontal plane). Next, the pick-and-place tool 10 then lowers the component head 20 (e.g., moves it in the negative z direction) to engage the component engagement surface 22 of the core 18 with the component 12 adhesively attached. Then, the pick-and-place tool 10 can heat the adhesively attached component by supplying an AC current to the induction coil 16 to reduce the adhesive strength of the adhesive attaching the component 12 adhesively attached to the system assembly 14. When such an adhesive is heated, the adhesive strength of the component 12 adhesively attached to the system assembly 14 can be significantly reduced such that removal of the adhesively attached component 12 from the circuit board assembly 14 is possible.

[0009] To attach the component 12 adhesively attached to the circuit board assembly 14, various types of adhesives can be used. For attaching an electronic component to such a circuit board assembly such as the circuit board assembly 14, various solders, metals, and other adhesives are commonly used. For the conductive connection between the leads of the adhesively attached component 12 and the conductive traces of the circuit board assembly 14, such various adhesives can be used. For the physical attachment of only the adhesively attached component 12 and the circuit board assembly 14, some adhesives can be used.

[0010] After the adhesive strength of the adhesive used to attach the component 12 has weakened, a DC current can be supplied to the induction coil 16 to magnetically attract the component 12 to the component head 20. After the component 12 is magnetically coupled, the pick-and-place tool 10 can raise the component head 20 so as to lift the component 12 magnetically coupled to the component head 20 (e.g., move it in the positive z direction). Next, the pick-and-place tool 10 moves the component head 20 so as to align the component removal bin and the component head 20. Finally, the DC current is set to zero or reversed so as to drop the component 12 into the aligned component removal bin. Thus, the AC current and the DC current are sequenced to heat, magnetically couple, and remove the component 12 from the system assembly 14. In the illustrated embodiment, such a sequence of electrical excitations includes first supplying an AC current first, then supplying a DC current, and then not supplying a current or reversing the DC current. For the reverse operation - for placing and attracting components to the system assembly, such a sequence of electrical excitation signals changes appropriately. Such a sequence of electrical excitation signals is described in more detail below.

[0011] Figure 2 is a schematic diagram of a component head configured to both inductively heat and magnetically attract components of a system assembly. In Figure 2, component head 20 includes induction coil 16 wound around core 18. An electrical excitation signal is supplied to induction coil 16 by controller 22. Controller 22 sequences various electrical excitation signals in a manner corresponding to specific operations performed by a pick and place tool. In the illustrated embodiment, a first DC excitation signal 24 is generated and supplied to induction coil 16. During the time that DC excitation signal 24 is supplied to induction coil 16, controller 24 aligns the attached component with respect to the location on the system assembly where such a component is to be attached. After DC excitation signal 24 is terminated, controller 22 generates an AC excitation signal 26 to inductively heat an adhesive that attaches the component to the system assembly. During the time that AC excitation signal 26 is supplied, the controller may supply a downward force (a force directed in the negative z direction) to the component to ensure good thermal coupling between core 18 and the component.

[0012] Figures 3A - 3C are schematic diagrams illustrating the placement and removal of components on a system assembly. In Figure 3A, component head 20 is aligned with component 12 (e.g., in the x - y plane), and component 12 is adhesively attached to system assembly 14. In the illustrated embodiment, component 12 is a cover for an electronic component attached to system assembly 14. The component head 20 can be used to pick and place any type of component to which it can be coupled. In some embodiments, as shown below, a vacuum can be used to enhance the bond to provide an additional or complementary bond between component head 20 and component 12. In Figure 3A, arrow 28 indicates that the component head is being lowered to engage (e.g., contact) component 12.

[0013] In Figure 3B, an AC excitation signal 26 is supplied to induction coil 14 to heat component 12. Such heating can be performed for a predetermined duration or until component 12 or core 18 reaches a predetermined temperature. In some embodiments, component head 20 includes a temperature sensor configured to sense the temperature of core 20 and / or the temperature of component 12. After (or during) component 12 is heated, a DC excitation signal 24 is supplied to induction coil 14 to magnetically attract component 12 to component head 20. In Figure 3C, arrow 30 indicates that the component head is being raised to remove component 12, showing that component 12 is magnetically coupled from system assembly 14 to component head 20.

[0014] FIG. 4 is a side view of an embodiment of a pick and place tool configured to inductively heat, bond, and attach / detach components. In FIG. 4, a bonded and attached component 12 attached to system assembly 14 via solder ball 32 is shown. Component head 20 includes induction coil 16 and complementary high permeability members 34T and 34B. Complementary pairs 34T and 34B of high permeability members can be positioned on opposite sides of system assembly 14 around bonded and attached component 12. At least one of the complementary pairs 34T and 34B of high permeability members includes a central pedestal 36T (which operates such that core 18 operates in the embodiments shown in FIGS. 1-3C). In the embodiment shown, the top high permeability member 34T includes central pedestal 36T. Here, "top" refers to the side on which the bonded and attached component 12 is located and one of the complementary high permeability members 34T and 34B located on the same side of system assembly 14. The term "bottom" is used to refer to the other side of system assembly 14 that is located on the side opposite to the side on which the bonded and attached component 12 is located among the complementary high permeability members 34T and 34B. The terms "top" and "bottom" are not required to indicate a particular orientation of circuit board assembly 14. Instead, the terms "first" and "second" can be used to distinguish between the complementary high permeability members 34T and 34B.

[0015] A magnetic field can be induced in the complementary high permeability members 34T and 34B through an induction coil 16 surrounding the central pedestal 24T of the complementary pair 34T and 34B of high permeability members. The coil driver 18 is configured to generate an AC current in the induction coil 16 surrounding the central pedestal 36T, thereby inducing a magnetic field therein. Due to the high permeability members 34T and 34B being made of a high permeability material, any magnetic field induced therein is a channel through the high permeability members so as to minimize losses to the induced magnetic field. The magnetic field takes the "lowest resistance" path, which is a metaphor for the closed path with the highest permeability. By directing the magnetic field through the complementary high permeability members 34T and 34B, the complementary high permeability members 34T and 34B protect the magnetic field exposure circuit outside the internal cavity defined by the inner surfaces of the high permeability members 34T and 34B. Only the circuits within such cavities are exposed to the magnetic field.

[0016] At least one of the complementary pair 34T and 34B of high permeability members has a peripheral device pedestal. In the illustrated embodiment, both the top and bottom high permeability members 34T and 34B have central pedestals 36T and 36B respectively. The central pedestal 36T is configured to direct the magnetic field induced therein through adhesively attached components. The peripheral device pedestals 38T and 38B are configured to provide a return path for the magnetic field around the periphery of the adhesively attached components. The induction coil is wound around the central pedestal 36T. Thus, the configured central pedestal 36T functions such that the core 18 functions as it does in the embodiments represented in FIGS. 1 - 3C.

[0017] During operation, the complementary high-permeability members 34T and 34B are positioned on the opposite side of the circuit board assembly around the adhesively attached component 12. The high-permeability members 34T and 34B are positioned in a clam shell configuration so as to substantially surround the adhesively attached component 12 within an internal cavity defined by the inner surfaces of the high-permeability members 34T and 34B. A magnetic field is then induced in the high-permeability members 34T and 34B via AC excitation of the induction coil 16 by the coil driver 18. The induced magnetic field is directed through the adhesively attached component 12 so as to induce an AC current in any conductive material either within or beneath the adhesively attached component 12, thereby heating such conductive material. Any solder, leads, circuit board traces, etc. located within the region where the magnetic field is directed then heat up due to their induced AC currents. Such heating can directly heat the adhesive (e.g., if a solder adhesive is located within the region), or can indirectly heat the adhesive (e.g., via heat conduction from the heated conductive material to the adhesive).

[0018] When the adhesive is heated, the adhesively attached component 12 can be removed from the circuit board assembly 14. Various methods can be employed to remove the adhesively attached component 12 from the circuit board assembly 14. For example, the top high-permeability member 34T can be raised and the adhesively attached component 12 can be manually removed using tools, tweezers, etc. In some embodiments, the top high-permeability member 34T can be provided with a suction system so as to vacuum attach the top high-permeability member 34T to the top surface of the adhesively attached component 12. The adhesively attached component 12 vacuum attached thereto is then removed by raising the top high-permeability member 34T.

[0019] FIG. 5 is a side view of an embodiment of a component removal tool including a component extractor using vacuum technology. In FIG. 5, an adhesively attached component 12 attached to the system assembly 14 via a solder ball 32 is shown. The top high permeability member 34T' is different from the top high permeability member 34T shown in the embodiment represented in FIG. 4. The top high permeability member 34T' includes a component suction port 38. The component suction port 38 is a central opening from the outer surface of the top high permeability member 34T' through the central pedestal 34T'. A vacuum system can be fluidly connected to the component suction port 38 to supply suction that can engage the component 12 adhesively attached to the central pedestal 34T'. Then, when the solder ball 32 is melted (e.g., during reflow of the solder ball), the top high permeability member 34T' can be removed, thereby removing the component 12, and its melted solder ball 32 no longer supplies the adhesive attachment between the component 12 and the system assembly 14. For example, the component suction port 38 can be located in various other configurations, such as adjacent to the central pedestal 34T'. In some embodiments, for example, an annular opening can surround the central pedestal 34T' to provide an annular suction seal by the adhesively attached component 12.

[0020] Discussion of possible embodiments The following is a non-limiting description of possible embodiments of the present invention.

[0021] The apparatus and related methods relate to a system for heating, picking, and placing components of an assembly. The system includes a magnetic core, an induction coil, and a controller. The magnetic core has a component engagement surface configured to magnetically and thermally engage components of the assembly. The induction coil is wound around the magnetic core. The controller supplies a DC signal and an AC signal to the induction coil. The DC signal induces a magnetic field in the magnetic core, thereby magnetically attracting the component when engaged with the component engagement surface. The AC signal induces and heats the magnetic core, thereby heating the component when engaged with the component engagement surface.

[0022] The system of the preceding paragraph can optionally include any one or more of the following features, configurations, and / or additional components in addition to and / or instead of.

[0023] A further embodiment of the preceding system can further include a mechanical actuator for moving the magnetic core and an inductor wound around it.

[0024] In any further embodiment of the preceding system, the mechanical actuator can include an x-y position actuator and a z position actuator. The x-y position actuator is configured to align the magnetic core and the inductor wound around the magnetic core with the component in the x-y plane. The z position actuator is configured to engage / disengage the magnetic core with the component in the z direction.

[0025] In any further embodiment of the preceding system, the controller can further be configured to sequence the supplied DC signal and AC signal such that either the component is first heated and then magnetically attracted, or the component is first magnetically attracted and then heated.

[0026] In a further embodiment of any of the aforementioned systems, when removing a component from the assembly, the controller can first supply an AC signal, thereby heating the component, and then supply a DC signal, thereby magnetically attracting the component.

[0027] In a further embodiment of any of the aforementioned systems, when installing a component in the assembly, the controller can first supply a DC signal, thereby magnetically attracting the component, and then supply an AC signal, thereby heating the component.

[0028] In a further embodiment of any of the aforementioned systems, the controller can be configured to simultaneously supply both a DC signal and an AC signal so as to simultaneously heat and magnetically attract the component.

[0029] In a further embodiment of any of the aforementioned systems, the magnetic core can have a vacuum opening along the length of the magnetic core between the component engagement surface and another surface. The system can further include a vacuum component extractor configured to supply a vacuum to the vacuum opening, thereby providing a vacuum coupling of the component when engaged with the component engagement surface.

[0030] In a further embodiment of any of the aforementioned systems, the controller can be configured to sequence the AC signal supplied to the induction coil and the vacuum supplied to the vacuum opening such that either the component is first heated and then a vacuum coupling is supplied to the component, or the component is first supplied with a vacuum coupling and then heated.

[0031] In a further embodiment of any of the systems described above, the controller can be configured to simultaneously supply an AC signal to the induction coil and supply a vacuum to the vacuum opening so as to heat the component and supply a vacuum bond to the component at the same time.

[0032] In a further embodiment of any of the systems described above, the magnetic core can further include a central pedestal and a peripheral pedestal. The central pedestal is configured to direct the induced magnetic field through the components of the assembly. The peripheral pedestal is configured to provide a return path for the magnetic field in the vicinity of the periphery of the components of the assembly.

[0033] Some embodiments relate to a method of heating, picking, and placing components of an assembly. The method includes engaging a component at an engagement surface of a magnetic core. The method includes inducing a magnetic field in the magnetic core via a DC signal supplied to an induction coil wound around the magnetic core, thereby magnetically attracting the component when engaged with the component engagement surface. The method also includes inductively heating the magnetic core via an AC signal supplied to an induction coil wound around the magnetic core, thereby heating the component when engaged with the component engagement surface.

[0034] The method of the preceding paragraph can optionally include any one or more of the following features, configurations, and / or additional components in addition to and / or instead.

[0035] A further embodiment of the method described above can further include aligning the magnetic core and an inductor wound around the magnetic core with the component in the x-y plane via an x-y actuator.

[0036] In a further embodiment of the method described above, a mechanical actuator can include engaging and / or disengaging the magnetic core with the component in the z direction via a z-position actuator.

[0037] Further embodiments of the foregoing method can further include sequencing the supplied DC and AC signals such that, either first the component is heated and then the component is magnetically attracted, or first the component is magnetically attracted and then the component is heated.

[0038] Further embodiments of the foregoing method can further include removing a component from an assembly by first supplying an AC signal via a controller to thereby heat the component and then supplying a DC signal via the controller to thereby magnetically attract the component.

[0039] Further embodiments of the foregoing method can further include installing a component in an assembly by first supplying a DC signal via a controller to thereby magnetically attract the component and then supplying an AC signal via the controller to thereby heat the component.

[0040] Further embodiments of the foregoing method can further include simultaneously supplying both a DC signal and an AC signal such that the component is heated thermally and magnetically simultaneously.

[0041] In further embodiments of the foregoing method, the magnetic core can have a vacuum aperture along the length of the magnetic core between the component engagement surface and another surface. The method can further include supplying a vacuum to the vacuum aperture via a vacuum component extractor to thereby provide a vacuum coupling of the component when engaged with the component engagement surface.

[0042] Further embodiments of the foregoing method can further include ordering the AC signal supplied to the induction coil and the vacuum supplied to the vacuum opening, such as first heating the component and then supplying a vacuum bond to the component, or first supplying a vacuum bond to the component and then heating the component.

[0043] Although the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for its components without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its essential scope. Accordingly, the invention is not limited to the particular embodiments disclosed, but is intended to cover all embodiments falling within the scope of the appended claims.

Claims

1. A system for heating, picking, and placing components of an assembly, comprising: a magnetic core having a component engagement surface configured to magnetically and thermally engage the components of the assembly; an induction coil wound around the magnetic core; a controller configured to supply a DC signal and an AC signal to the induction coil; a mechanical actuator configured to move the magnetic core and the induction coil wound around the magnetic core; wherein the DC signal induces a magnetic field in the magnetic core, and when engaged with the component engagement surface, magnetically attracts the component; and the AC signal induces heating of the magnetic core, and when engaged with the component engagement surface, heats the component. A system.

2. The mechanical actuator includes: an x-y position actuator configured to align the magnetic core and the induction coil wound around the magnetic core with the component in an x-y plane; and a z-position actuator configured to engage / disengage the magnetic core with the component in a z direction. The system according to claim 1.

3. The controller is further configured to sequence the supplied DC signal and AC signal such that either the component is first heated and then magnetically attracted, or the component is first magnetically attracted and then heated.

4. When removing the component from the assembly, the controller first supplies the AC signal to heat the component and then supplies the DC signal to magnetically attract the component.

5. When installing the component in the assembly, the controller first supplies the DC signal to magnetically attract the component and then supplies the AC signal to heat the component.

6. The controller is configured to simultaneously supply both the DC signal and the AC signal such that the component is heated thermally and magnetically attracted at the same time.

7. The magnetic core has a vacuum opening along the length of the magnetic core between the component engagement surface and another surface, The system further comprises a vacuum component extractor configured to supply a vacuum to the vacuum opening and provide a vacuum coupling of the component when engaged with the component engagement surface. The system according to claim 1.

8. The controller is configured to sequence the AC signal supplied to the induction coil and the vacuum supplied to the vacuum opening such that the controller first heats the component and then provides a vacuum coupling to the component, or first provides a vacuum coupling to the component and then heats the component.

9. The controller is configured to simultaneously supply the AC signal to the induction coil and supply a vacuum to the vacuum opening so as to simultaneously heat the component and provide a vacuum coupling to the component.

10. The magnetic core further comprises a central pedestal configured to direct an induced magnetic field through the component of the assembly, and a peripheral pedestal configured to provide a return path for the magnetic field in the vicinity of the periphery of the component of the assembly. The system according to claim 1.

11. A method of heating, picking, and placing components of an assembly, comprising: engaging the component at a component engagement surface of a magnetic core; inducing a magnetic field in the magnetic core via a DC signal supplied to an induction coil wound around the magnetic core and magnetically attracting the component when engaged with the component engagement surface; inducing and heating the magnetic core via an AC signal supplied to the induction coil wound around the magnetic core and heating the component when engaged with the component engagement surface; and moving the magnetic core and the induction coil wound around the magnetic core by a mechanical actuator. Method. **Claim 12**: The method according to claim 11, wherein moving the magnetic core and the induction coil wound around the magnetic core comprises aligning the magnetic core and the induction coil wound around the magnetic core with the component in the x-y plane via an x-y position actuator. **Claim 13**: The method according to claim 11, wherein moving the magnetic core and the induction coil wound around the magnetic core comprises engaging and / or disengaging the magnetic core with the component in the z direction via a z position actuator. **Claim 14** The method according to claim 11, further comprising sequencing the supplied DC signal and AC signal such that either the component is first heated and then magnetically attracted, or the component is first magnetically attracted and then heated. **Claim 15** **Claim 16**: The method according to claim 14, further comprising removing the component from the assembly by: first supplying the AC signal via a controller to heat the component; and then supplying the DC signal via the controller to magnetically attract the component. **Claim 17**: The method according to claim 14, further comprising installing the component in the assembly by: first supplying the DC signal via a controller to magnetically attract the component; and then supplying the AC signal via the controller to heat the component. **Claim 18**: The method according to claim 11, further comprising simultaneously supplying both the DC signal and the AC signal so as to heat the component thermally and magnetically simultaneously. **Claim 19**: The magnetic core has a vacuum opening along the length of the magnetic core between the component engagement surface and another surface, and the method further comprises supplying a vacuum to the vacuum opening via a vacuum component extractor to provide a vacuum coupling of the component when engaged with the component engagement surface. **Claim 20**: The method according to claim 11. **Claim 21** ​ ​ ​ ​ ​ The method according to claim 18, further comprising sequencing the AC signal supplied to the induction coil and the vacuum supplied to the vacuum opening, such that either the component is first heated and then a vacuum bond is supplied to the component, or a vacuum bond is first supplied to the component and then the component is heated.

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