System and method for improving electronic component interconnection

Abstract

The invention provides a system and a method for improving interconnection of electronic components. Systems and methods are provided for improving interconnection of electronic components using ACA. The method involves the use of a magnet dedicated to each component to be connected and optimized in terms of size and strength and position relative to the substrate and components. Oven adapted for use with the methods and systems and kits providing parts of the systems for use with existing ovens are also provided.

Description

[0001] This application is a divisional application of a patent application with application number 201880073739.1 (PCT / US2018 / 061395) filed on May 14, 2020, application date on November 15, 2018, and titled “Systems and Methods for Improving Interconnection of Electronic Components”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 586,815, filed on November 15, 2017, which is incorporated herein by reference in its entirety. Technical Field

[0004] This invention relates generally to establishing electrical connections of components in electronic circuits. More particularly, this invention relates to improved methods for connecting components to substrates using anisotropic conductive adhesives. Background Art

[0005] As modern demands on technology increase, the number of electronic devices continues to increase, the availability and adoption of such devices continues to increase, the size of such devices continues to decrease, and the number of interconnections of electronic components required to manufacture such devices has greatly increased. In addition, previously analog devices have almost disappeared in many fields as such devices have been replaced by electronic devices, and the size of electronic devices has dropped dramatically even as the power of those devices has continued to expand rapidly.

[0006] As modern components have become smaller and more powerful, there are more circuits on such components in less and less space (i.e., the density of circuits has increased), while at the same time the tolerances between different aspects of, for example, a given chip or component have become tighter (i.e., the pitch has become smaller - "ultra-fine pitch").

[0007] Modern components are therefore often more susceptible to temperature and pressure, either of which can cause problems and even lead to failure of the component and the entire device of which it is a part. Unfortunately, current means of creating interconnections between, for example, a component and its substrate for certain applications have limitations and disadvantages.

[0008] Skilled professionals will recognize that there are many interconnection approaches (such as traditional soldering, anisotropic conductive films (ACFs), and anisotropic conductive adhesives (ACAs)), each of which has benefits and limitations, and each of which provides options that can meet the specific interconnection requirements of a particular application, component, or device.

[0009] Conventional welding involves exposing the parts being joined to localized high amounts of heat and pressure. Exposing such parts to these adverse or unsustainable conditions can result in outright failure, poor or unreliable performance, or greatly reduced life.

[0010] As an effort to improve interconnects for various applications, ACFs have been developed. These conductive films can reduce the local heat required to make connections through soldering, but they can still require a lot of heat. In addition, both heat and pressure are usually applied to the components, which can be a significant limitation for sensitive components. ACFs are also limited in the pitch of interconnects they are suitable for or can accommodate.

[0011] ACAs have also been developed to provide an alternative solution for creating difficult interconnects in specific applications. Like ACFs, these adhesives provide conductivity only in the Z-axis. ACAs, such as those produced by SunRay Scientific, contain magnetically alignable particles that, when aligned along the Z-axis by exposure to a magnetic field, form interconnects between components. The adhesive matrix is ​​then cured, such as by exposure to heat, to complete and secure the interconnects. No pressure is required, making ACAs a good candidate for pressure-sensitive components. Additionally, for temperature-sensitive components, curing can be accomplished in low heat. Furthermore, ACAs allow for finer pitch applications than can be achieved using ACFs.

[0012] Prior art applications of ACA have typically employed a magnetic field applied across the entire substrate using an electromagnet. While such a field covers all components populated on the substrate, it may be disadvantageous in applications where one or more components on the substrate are sensitive to the magnetic field. Furthermore, the magnetic field applied over a large area includes the entire magnetic field, including flux lines that are not substantially perpendicular to the XY plane.

[0013] While creating interconnects using ACA is simple and easy, there remains a need for improved systems and methods for creating and optimizing interconnects using ACA in specific applications. Summary of the invention

[0014] The inventors have discovered methods that provide unexpected improvements in ACA-based electronic interconnects for specific applications and have developed systems that implement these methods. These methods provide several advantages based on the following steps: selecting appropriate ACA characteristics, using separate magnets positioned for each component to be interconnected, and selecting the characteristics of the magnets used for the alignment of the ACA for each specific component populated on the substrate to optimize the creation of Z-axis connections (in terms of the height, number and direction of the Z-axis columns). These methods allow the construction of what the inventors call a "magnetic pallet", which provides consistent and optimal alignment and curing of ACA-based interconnects. Compared with existing methods of forming interconnects, these methods can provide improved interconnect consistency, reduced failures, improved life and increased functional connection yields.

[0015] In a first aspect, the present disclosure provides novel methods for aligning and curing ACA-based interconnects in digital devices, electronic apparatuses, etc. The method for establishing interconnects between a substrate and electronic components populated on the substrate using a magnetically alignable anisotropic conductive adhesive (ACA) generally comprises the following steps:

[0016] a) establishing the size and position on the substrate of a first electronic component to be placed on and connected to the substrate;

[0017] b) determining a placement position of a first magnet corresponding to the size and position established for the component in step a);

[0018] c) determining the size and strength of the magnets required in step b); and

[0019] d) Draw the flux lines of the magnet's magnetic field.

[0020] Repeating steps a)-d) for each additional component to be placed on and connected to the base plate so as to determine the characteristics and placement of each additional magnet required;

[0021] The method further comprises the following steps:

[0022] f) creating a magnetic tray and securing each magnet in its corresponding placement position on the tray;

[0023] g) creating an alignment tray and adapting the alignment tray to hold the substrate during alignment and curing;

[0024] h) placing the substrate on an alignment tray;

[0025] i) applying the ACA to the substrate in a location suitable for interconnecting each component to be placed on the substrate;

[0026] j) populating the substrate with the first component and each additional component where the ACA has been applied;

[0027] k) Assemble the alignment tray and magnetic tray;

[0028] 1) allowing the formation of pillars in the ACA in the Z-axis; and

[0029] m) curing the ACA to establish interconnections between the substrate and the first component and each additional component.

[0030] The alignment tray and the magnetic tray are made of non-magnetic materials. The magnet tray is adapted to receive and hold the first magnet and each additional magnet in their respective placement positions on the tray. The assembled magnet tray (with magnets in place) and alignment tray (with the substrate populated with components and ACA) can be placed directly into a curing oven as an assembly.

[0031] In a second aspect, provided herein is a system for creating an interconnect between a substrate and an electronic component attached to the substrate using a magnetically alignable anisotropic conductive adhesive (ACA). The system generally includes a magnet tray including a non-magnetic tray adapted to receive and hold each of one or more magnets placed therein in a position corresponding to a position of one or more electronic components on a substrate to which the components are to be attached.

[0032] The system also includes an alignment tray adapted to hold a substrate populated with one or more components to be connected to the substrate using the ACA during alignment and curing of the ACA.

[0033] The system also includes an ACA comprising magnetically alignable particles capable of forming interconnects that conduct electricity in the Z-axis.

[0034] Both the alignment tray and the magnetic tray are preferably made of non-magnetic material.In various embodiments, the substrate can only be placed in the alignment tray in one orientation.

[0035] In a presently preferred embodiment, the magnets are permanent magnets. Typically, for each magnet in the magnet tray, the magnetic flux lines are substantially parallel to each other and substantially perpendicular to the XY plane in an area corresponding to an area of ​​the substrate on which the component and ACA are located. In a presently preferred embodiment, the magnetic flux lines consist essentially of lines that are parallel to each other and perpendicular to an area of ​​the substrate on which the component and ACA are located.

[0036] In a third aspect, the present disclosure provides a kit for creating an interconnect between a substrate and an electronic component attached to the substrate using a magnetically alignable anisotropic conductive adhesive. The kit generally includes:

[0037] at least one magnetic tray, the at least one magnetic tray comprising a non-magnetic tray adapted to hold one or more magnets in a position corresponding to a desired position of an electronic component on a substrate and connection of the component to the substrate using an ACA;

[0038] Sufficient magnets to complete the magnet tray, each magnet of the desired size and strength for making interconnections between the component and the substrate using the ACA;

[0039] at least one alignment tray adapted to receive and hold the substrate and components populated on the substrate during alignment and curing of the ACA to form interconnects;

[0040] and optionally, an ACA adapted for use with the kit to create at least one interconnect between the component and the substrate using the kit.

[0041] In the kit provided, the magnet tray and alignment tray are configured to be oriented vertically relative to each other. They are assembled so that when the magnet tray and alignment tray are assembled in that manner, the electronic components placed on the substrate on the alignment tray (to be connected to the substrate using the ACA) are vertically aligned with the magnets on the magnet tray. Each component that needs to be connected (interconnected) has a corresponding magnet, and when the trays are assembled, each component will be aligned with the corresponding magnet.

[0042] In a presently preferred embodiment of the kit, the magnets comprise rare earth magnets or other permanent magnets.

[0043] In yet another aspect, the present disclosure provides an oven system designed to create interconnections between a substrate and an electronic component to be placed on the substrate and connected to the substrate using an ACA. The oven system generally includes a curing oven and one or more shelves or racks, each shelf or rack including:

[0044] a magnetic tray equipped with one or more magnets, each magnet being placed in a position corresponding to the position of an electronic component to be placed on the substrate and connected to the substrate using the ACA; and

[0045] An alignment tray adapted to receive and hold a substrate populated with one or more components to be placed on the substrate and connected via the ACA.

[0046] These and / or additional aspects, features and advantages of the present invention will become apparent to those skilled in the art in view of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 : A cross-sectional overview of an embodiment of a system for magnetically aligning and curing ACA interconnects showing a magnet tray with magnets positioned therein, an alignment tray, a substrate, and components populated on the substrate.

[0048] Figure 2 : A flow chart showing the steps of a method for using an ACA to magnetically align and cure a component to a substrate to create an electrical connection.

[0049] Figure 3 : A drawing showing an embodiment of an alignment tray for use herein. The tray contains a plurality of substrates, each substrate having a filler component to be placed on and connected to the substrate.

[0050] Figure 4 : Drawings showing an embodiment of an oven employing a magnetic flat rack system. (A). Multiple magnet trays and alignment tray assemblies are shown in a batch oven. The outer dimensions of the alignment trays and magnet trays are dictated by the oven dimensions, but otherwise it is not necessary for each magnet tray or each alignment tray to be identical. Thus, a single oven can be utilized to align and cure multiple interconnects for multiple electronic components on different substrates or devices. (B). An enlarged view of an assembly including an alignment tray and a magnet tray with orienting means (alignment holes) is shown. (C). A close-up top view of a magnet tray used as a rack in an oven. DETAILED DESCRIPTION

[0051] Provided herein are methods and systems for using ACAs to provide improved and more consistent interconnections for electronic components.

[0052] Definitions and Abbreviations

[0053] Unless otherwise specifically defined, all technical and scientific terms, terminology and acronyms used herein have the meaning commonly understood by one of ordinary skill in the art in the field of the invention or in the field in which the terms are used. In accordance with this description, the following abbreviations and definitions apply.

[0054] Abbreviations

[0055] Unless otherwise indicated, the following abbreviations apply:

[0056] AC: Communication;

[0057] ACA: Anisotropic Conductive Adhesive;

[0058] ACF: Anisotropic Conductive Film;

[0059] DC: Direct current;

[0060] Gs: Gauss, unit of magnetic field;

[0061] NIB: Neodymium-Iron-Boron;

[0062] PCB: Printed Circuit Board; and

[0063] T: Tesla, SI unit of magnetic field.

[0064] definition

[0065] As used herein, "substantially" can mean an amount greater than or less than the referenced item. Preferably, substantially greater (or more) or smaller (or less) means at least about 10% to about 100% or more different from the corresponding referenced item. More preferably, "substantially" means at least about 20% to about 100% or more greater or less than the referenced item in such cases. As the technician will recognize, the term "substantially" can also be used as "substantially all", "substantially all" means more than 51% of the referenced item, quantity or amount, preferably more than 60%, 67%, 70%, 75%, 80%, 85%, 90% or more. "Substantially all" can also mean more than 90% of the referenced item, quantity or amount, including 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more.

[0066] As used herein, the singular form of a word includes the plural, and vice versa, unless the context clearly dictates otherwise. Thus, references to "a", "an", and "the" generally include the plural of the respective terms. For example, references to "an electrode" or "a diode" include a plurality of such "electrodes" or "diodes".

[0067] The words "comprising," "containing," and "including" are to be construed as inclusive rather than exclusive. Likewise, the terms "include," "including," and "or" should all be construed as inclusive, unless such construction is clearly prohibited from the context. Additionally, forms of the terms "comprising" or "including" are intended to include embodiments encompassed by the phrases "consisting essentially of" and "consisting of." Similarly, the phrase "consisting essentially of" is intended to include embodiments encompassed by the phrase "consisting of."

[0068] Where used herein, ranges are provided in shorthand form to avoid having to list and describe every value within the range. Where appropriate, any appropriate value within the range can be selected as the upper limit, lower limit or demarcation of the range.

[0069] The formulations, compositions, methods and / or other advances disclosed herein are not limited to the specific methodology, protocols and / or components described herein, as they may vary, as will be appreciated by the skilled artisan. Additionally, the terminology used herein is only used for the purpose of describing specific embodiments and is not intended to and does not limit the scope of the disclosed or claimed embodiments.

[0070] Although any formulations, compositions, methods, or other means or materials similar or equivalent to those described herein can be used in the practice of the present invention, the preferred formulations, compositions, methods, or other means or materials are described herein.

[0071] Any reference cited or referenced herein, including any patent, patent application or other publication, technical and / or scholarly article, is incorporated herein by reference in its entirety to the extent permitted under applicable law. Any discussion of those references is intended only to summarize the claims made therein. It is not acknowledged that any such patent, patent application, publication or reference is prior art, or that any part thereof is relevant or decisive to the patentability claimed herein. Applicants specifically reserve the right to question the accuracy and relevance of any claim that such patents, patent applications, publications and other references are prior art or are relevant and / or decisive.

[0072] As used herein, "alignment" means aligning a magnetic material or composition containing magnetic particles. Typically, alignment refers to the alignment of magnetic particles in the Z axis under the influence of a magnetic field. Alignment is a process used to form a column in the Z axis. As will be clear from the context, sometimes "alignment" is also used herein to refer to ensuring that two things, such as an alignment tray and a magnetic tray or a substrate and an alignment tray, are properly oriented relative to each other.

[0073] As used herein, "column" refers to a structure formed in the Z axis by magnetic particles in a composition under the influence of a magnetic field. The process of column formation is sometimes referred to as "alignment". The column characteristics (e.g., height, diameter, etc.) will be determined by the strength of the magnet and the characteristics of the ACA, including the size and amount of magnetic particles in the ACA and the viscosity and other physical properties of the ACA matrix. The column can and will form within seconds of exposure to a suitable magnetic field.

[0074] A "magnet" is capable of producing a "magnetic field," which as used herein includes any magnetic field, whether produced by an electromagnet or a permanent magnet. The "strength" of a magnet can be measured in Gs (or Ts). A skilled person will recognize how to determine the strength of any given magnet, or how to determine the magnetic strength expected of a given magnet. As used herein, "mapping a magnetic field" means determining the specific shape of a magnetic field and the path of magnetic field lines. A skilled person will recognize how to map the magnetic field of any magnet by various means.

[0075] As used herein, "permanent magnet" means a magnet that does not require the flow of electric current in order to have a persistent magnetic field. Permanent magnets for use in this article can include iron, nickel, cobalt and rare earth metals. Some currently preferred embodiments herein utilize rare earth magnets, such as rare earth magnets containing lanthanides. Magnets containing neodymium or its salts may be useful in this article due to their magnetic strength. In one embodiment, the magnet contains neodymium, iron and boron ("NIB magnet"). Samarium, gadolinium and even dysprosium and its salts can be used for specific applications. Other types of permanent magnets such as ceramic magnets and other composite magnets and even flexible magnets may be suitable for use in other specific applications in this article.

[0076] As used herein, an "interconnect" is generally a connection between any two aspects of a system. An interconnection herein generally reflects, for example, an electrical connection and a physical connection between two components or a component and a substrate. A "substrate" is a component that is used to hold or contain other electronic components connected thereon for use in an electronic system or device, such as a printed circuit board ("PCB"). A substrate can be flexible or rigid. Preferred rigid substrates include, for example, PCBs, composite materials, and rigid polymers; preferred flexible supports include, for example, flexible polymers.

[0077] As used herein, "parallel" means that two lines, such as lines representing magnetic flux, are always separated by the same distance and never contact each other and exist in the same plane, that is, they are 0 degrees relative to each other. Parallel lines herein are generally reference magnetic flux lines in the Z axis, and the reference magnetic flux lines are generally perpendicular to the XY plane of the substrate (i.e. 90 degrees). Due to the difficulty of having completely parallel magnetic flux lines in all applications involving multiple magnets, the parallel lines in various embodiments herein may include lines that are "substantially parallel" to each other and / or substantially perpendicular to XY. Such lines can be positioned relative to each other, for example, about -30 to about 30 degrees, and / or about 60 to about 120 degrees relative to the ZY plane. More preferably, such lines are positioned relative to each other, for example, about -15 to about 15 degrees, and / or about 75 to about 105 degrees relative to the ZY plane. Even more preferably, substantially parallel magnetic flux lines are positioned relative to each other, for example, about -5 to about 5 degrees, and / or about 85 to about 95 degrees relative to the XY plane of the substrate. Even more preferably, the substantially parallel lines will be positioned within about 0 to about 2 degrees of each other and / or within about 0 to about 2 degrees of perpendicular to the XY plane. A skilled artisan will recognize that the closer the flux lines are to being parallel to each other and perpendicular to the XY plane, the more the ACA will form parallel columns during alignment that will be the basis for the interconnect, and the less likely there will be shorts and other defects that negatively impact the functionality or durability of the interconnect so formed.

[0078] As used herein, "Z-axis" means a direction perpendicular to the XY plane, which is a principal plane on which the substrate is located.

[0079] DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0080] Provided herein are systems and methods for creating improved and more consistent electronic interconnects using ACAs in electronic circuits. Such systems typically include individual magnets placed in positions corresponding to each component being connected. The size and strength of each magnet is determined based on the component, substrate, ACA in use, and the application mentioned. Only the components being connected using the ACA are exposed to any magnetic field, meaning that sensitive components are not exposed to unnecessary magnetic fields. Preferably, the optimized interconnect provides better yields, fewer short circuits and other failures, and longer life / more cycles. The inventors have surprisingly found that by strategically selecting magnet size, strength, and placement, the consistency and quality of the interconnect can be greatly improved. Therefore, disclosed herein are methods and systems for improving the creation of interconnects using ACAs.

[0081] In a first aspect, the present disclosure provides novel methods for aligning and curing ACA-based interconnects in digital devices, circuit boards, electronic devices, etc. The method for establishing interconnects between a substrate and electronic components populated on the substrate using a magnetically alignable anisotropic conductive adhesive (ACA) generally comprises the following steps:

[0082] a) establishing the size and position on the substrate of a first electronic component to be placed on and connected to the substrate;

[0083] b) determining a placement position of a first magnet corresponding to the size and position established for the component in step a);

[0084] c) determining the size and strength of the magnets required in step b); and

[0085] d) Draw the flux lines of the magnet's magnetic field.

[0086] Steps a)-d) are repeated for each additional component to be placed on and connected to the substrate in order to determine the characteristics and placement of each additional magnet required. The skilled person will recognize that throughout the specification there are various methods set forth herein in which various steps are set forth. It should be noted that where such steps are not strictly required to be performed in the order described, these methods can likewise be performed by performing these steps in a different order as this facilitates achieving a successful interconnection without changing the overall purpose and results.

[0087] The method also includes the steps of creating a magnetic tray and securing each magnet in a corresponding placement position on the tray; and creating an alignment tray and adapting the alignment tray to hold the substrate during alignment (i.e., column formation) and curing of the ACA in the Z axis.

[0088] The substrate is then placed on an alignment tray. ACA is applied to the substrate where the components will be placed. The substrate is then populated with the first component and each additional component.

[0089] The alignment tray (including the substrate, the components to be attached and the applied ACA) and the magnetic tray are assembled to expose the ACA to the magnets. Sufficient exposure time is provided to allow the formation of pillars in the ACA in the Z axis; and the ACA is then cured to establish interconnections between the substrate and the first component and each additional component.

[0090] Typically, the alignment tray and the magnetic tray are made of a non-magnetic material such as aluminum or a thermally stable material such as plastic or a composite material. The magnet tray is typically adapted to accommodate the first magnet and each additional magnet in their respective placement positions on the tray. The completed assembly including the magnet tray with magnets and the alignment tray with the substrate populated with components and ACAs can be placed in a curing oven.

[0091] In various embodiments, the magnet comprises a permanent magnet. In a currently preferred embodiment, the magnet comprises a rare earth magnet. In one embodiment, a rare earth magnet comprising a neodymium or NIB magnet is used.

[0092] The inventors have discovered that the size and strength of the magnets used to create the interconnects can be determined empirically for each application to optimize the consistency and quality of the interconnects formed. The skilled person will recognize that the size and strength of the magnets selected will be related to the process of post formation, and that the magnet selection will be influenced by the desired characteristics of the post, such as the height, diameter, and strength of the post. In addition, the connection of the post to both the component and the substrate is also influenced by the magnet characteristics.

[0093] Thus, in certain embodiments, the size and strength of the magnets are determined to optimize or address properties of the post or final interconnect. Such properties may include the height of the post, the strength of the interconnect, the number of resulting shorts, the expected life of the finished device or board, the yield of usable product, or the failure rate or number of failures resulting from the process of creating the interconnect.

[0094] The inventors have also determined that significant benefits result from utilizing magnetic flux lines that are substantially parallel to each other and / or substantially perpendicular to the XY plane in areas corresponding to areas of the substrate on which the components and ACA are located. In various embodiments, the magnetic flux lines consist essentially of such parallel and / or perpendicular lines.

[0095] In various embodiments, as a result of utilizing the provided methods, the ACA forms substantially uniform pillars in height and diameter. In a presently preferred embodiment, the ACA forms substantially uniform pillars that are substantially perpendicular to the XY plane of the component and substrate.

[0096] In order to further optimize the method, further improve consistency and to make the method even simpler and more reliable, in one embodiment the geometry of the portion of the alignment tray that receives and / or holds the substrate is configured such that the substrate can only be placed in the alignment tray in one orientation. This enables technicians to reproducibly place the substrate in the alignment tray for production.

[0097] In other embodiments, the alignment tray includes alignment means such as placement pins, complementary structures, etc. to ensure that the magnetic tray and the alignment tray can only be assembled in the proper orientation relative to each other. Alternatively, the geometry of the alignment tray and the magnetic tray only allows assembly in one (proper orientation). The skilled person will recognize that there are many simple ways to provide the proper orientation. Again, such features will further improve consistency and allow any skilled person to use the method for production.

[0098] As discussed above, usually, these methods allow the assembly including the positioned magnet tray and alignment tray to be placed directly in a curing oven. Preferably, the alignment tray and the magnet tray comprise a material that can withstand the curing conditions for curing the ACA. In one embodiment, these trays are aluminum or thermally stable non-magnetic materials that can withstand, for example, 50-70C, 60-80C, 70-100C, 75-120C, 100-140C or even greater temperatures. It is expected that the low temperature curing method will continue to be developed, and the material for the alignment tray and the magnet tray can be revised accordingly in this case.

[0099] These methods can be more fully appreciated by referring to the figures. Figure 2 A flow chart of one embodiment 200 of the methods described herein is shown. As can be seen, these methods generally begin with an understanding of the substrate and the components to be placed on the substrate and connected to the substrate using ACAs as indicated in step 210. The size and location of each component can be mapped to allow the magnet tray to be designed and the required placement location of each magnet to be determined 220.

[0100] The size and strength of each magnet can be determined 225 based on the details of the application. The characteristics of the magnetic field, such as the flux lines of each magnet, can be determined or mapped 230. The skilled person will understand how to determine the size, strength, and flux lines of each magnet as required. The skilled person will also recognize that the order of the foregoing steps can be altered as may be preferred in a given application.

[0101] The skilled artisan will further recognize that the properties of the magnet will affect the development and formation of the pillars in the Z axis within the ACA. Stronger magnets will allow taller pillars to be formed more quickly, however it is not desirable to make the magnets too strong. In various embodiments, the ideal properties of the magnets are determined empirically for any given application.

[0102] A magnet tray is created 235 and the magnets selected for the job are secured in their respective positions 240. It should be understood that the magnet tray is designed to accommodate each magnet in its respective position by any useful means that does not alter the position of the magnet relative to the component and substrate or the magnetic field. In one embodiment, the magnetic tray is made of aluminum with holes cut in the locations where each magnet will be placed. The magnets can again be secured in place 240 by any means that does not alter the strength or flux lines of the magnets. Adhesives can be conveniently used in some embodiments to secure the magnets in the magnet tray.

[0103] An alignment tray 245 is created to serve as a carrier for substrates and components and to ensure that the substrate and each component populated on the substrate is aligned with the corresponding magnet in the magnet tray. The alignment tray is adapted 250 to accommodate and hold the substrate during alignment and subsequent curing of the ACA. The tray can be adapted by any means to secure the substrate during the process of creating the interconnect. In one embodiment, a recessed area complementary to the shape of the substrate is created to passively accommodate and constrain the substrate during the process. In a currently preferred embodiment, the substrate can only be accommodated in the alignment tray in one orientation, thereby minimizing the risk of misalignment with the magnets in the magnet tray.

[0104] ACA is applied 265 to the substrate at the locations where the components are to be placed 260. In some embodiments contemplated herein, the steps may vary, for example, the components may be filled and the ACA may be applied simultaneously. The skilled artisan will also recognize that the order of operations herein may vary as such, as long as the end result is that each component is correctly placed in the desired location on the substrate with the desired amount of ACA between them.

[0105] The alignment tray and the magnet tray are then brought into proximity with each other. In a currently preferred embodiment, the trays must be aligned when positioned vertically relative to each other. This is implemented by a structure that prevents the alignment tray from sliding across the magnetic field of the magnets in the magnet tray with the substrate and inducing inappropriate column formation. By requiring the magnet tray and the alignment tray to be brought into proximity in this manner, column formation is optimized and confined to essentially the Z axis. The thus assembled tray 270 ("assembly" or magnet flat rack assembly) can then be placed in an oven to cure under appropriate conditions. Because the assembled trays are assembled together in a manner that optimizes the formation of Z-axis (i.e., vertical) columns parallel to each other and because the assembly can be moved without substantially interfering with the column, the oven can be a batch oven in which the assembly is manually moved in and out of the oven, or it can be a semi-continuous or even continuous oven, such as a reflow oven in which the assembly travels along a conveyor through the oven. After the ACA has been cured, there is little risk of affecting the column structure; that is, the column is stable in the curing ACA.

[0106] It should also be noted that certain components may experience a phenomenon referred to herein as "chip flipping". If the component is polar, that is, if the component has, for example, two separate poles, then when exposed to the magnetic field of the magnet tray, the component will "flip" to align itself with the magnetic field. Because the ACA is not yet aligned or cured when the system is exposed to the magnet tray, there is nothing to prevent the chip from doing so. In extreme cases, the component may be pulled out of the substrate as a whole. Although this only happens on certain components, it will cause problems if it exists. The inventor has developed a simple solution to this problem in the presence of such components. It needs to include an additional "sticking" step to fix the component / chip before exposure to the magnet tray. Typically, the component of interest is fixed to the substrate. A useful way is to apply a small amount of epoxy resin in the presence of a magnetic field to keep sensitive components in place. The current method includes using a UV-curable epoxy resin applied as a coating agent sufficient to fix the component, and then briefly exposed to UV light of sufficient intensity and duration to ensure that the epoxy resin is cured. The assembly of substrate, component and ACA can then be placed in suitable proximity to the magnet tray to allow the Z-axis column to be formed without concern for component / chip flipping.

[0107] In a second of its several aspects, the present disclosure provides a system for creating an interconnect between a substrate and an electronic component attached to the substrate using a magnetically alignable anisotropic conductive adhesive (ACA). The system includes a magnet tray including a non-magnetic tray adapted to receive and hold each of one or more magnets placed therein in a position corresponding to the position of one or more electronic components on the substrate to which the components are to be connected.

[0108] The system also includes an alignment tray adapted to receive a substrate populated with one or more components to be connected to the substrate using the ACA. The alignment tray is capable of holding the substrate during alignment and curing of the ACA.

[0109] The system also includes an ACA comprising magnetically alignable particles capable of forming interconnections that conduct electricity in the Z-axis. The ACA formulation can be varied for specific applications as may be dictated by the nature of the electronic components or the devices that interconnect these components. For applications with different pitch requirements, the ACA can be formulated using, for example, electromagnetic / conductive particles of different sizes.

[0110] In a currently preferred embodiment, the alignment tray and the magnetic tray are made of non-magnetic materials. In one embodiment, the substrate can only be placed in the alignment tray in one orientation to avoid confusion and errors and to allow non-technical staff to assist in production.

[0111] Typically, the magnet tray and the alignment tray are adapted to be removably arranged vertically together so that the components on the substrate are vertically aligned with the magnets in the magnet tray and the ACA is exposed to the magnetic field so that the flux lines are substantially perpendicular to the XY plane defining the substrate. This arrangement is preferably maintained until the curing of the ACA is completed.

[0112] In various embodiments of the system, the magnet is a permanent magnet. Rare earth magnets can be used for many applications herein, including magnets containing neodymium, such as NIB magnets. These magnets are capable of providing strong magnetic fields.

[0113] In one embodiment, an assembly including a magnet tray, an alignment tray, and a substrate filled with components can be placed directly into a curing oven. This enables the aligned ACA to be cured with minimal movement and low risk of disturbing the columns formed in the Z axis when exposed to a magnetic field. In another embodiment, the assembly and / or magnet tray is used as a rack that can slide directly into the oven without the need for any supporting shelves or additional racks for use. In other embodiments, the assembly can be placed on a conveyor mechanism for use with a semi-continuous or continuous process oven. In such embodiments, the conveyor can include multiple different assemblies of the same or different configurations with substrates and components - each assembly matches its own magnetic tray designed according to the details and the components and substrates to be interconnected.

[0114] In various embodiments, for each magnet in the magnet tray of the system, the magnetic flux lines are substantially parallel to each other and substantially perpendicular to the XY plane in an area corresponding to the area of ​​the substrate on which the component and ACA are located. Optimal interconnection can result from such an arrangement. The ACA forms a substantially uniform column that is substantially perpendicular to the XY plane of the component and substrate in various embodiments.

[0115] Further reference to Figure, Figure 1An embodiment 100 of a system for magnetically aligning and curing an ACA interconnect depicting certain features of the illustrated system. Shown is a cross-sectional view of an embodiment for magnetically aligning and curing an ACA interconnect showing a non-magnetic magnet tray 110 with a plurality of magnets 120 positioned therein. The magnet tray 110 has openings (not numbered for convenience and clarity) to accommodate the magnets 120, which can be secured in the magnet tray 110 using adhesives (not shown) or other securing means that do not alter the magnetic flux lines or otherwise interfere with the magnets 120. The alignment tray 130 has a recess that accommodates a substrate 140 that is held in place during alignment and curing of the ACA to form the interconnect. The substrate 140 has a plurality of electronic components 150 positioned thereon. The ACA (not shown) is applied / positioned (or likely has been applied) between the components 150 and the substrate 140. As can be seen, the placement of each magnet 120 corresponds to the position of the component 150 on the substrate 140, so that the magnet 120 is vertically aligned with the component 150. In this configuration the magnetic field provides a force to align the electromagnetic particles of the ACA (not shown) to form a Z-axis column. As can be seen, the area covered by each magnet 120 is greater than the area covered by the corresponding component 150, so that the system 100 provides better and consistent alignment than prior art electromagnets that cover the entire surface of the substrate or magnets that are the same size as the component.

[0116] Figure 3 An embodiment of an alignment tray is depicted with various aspects thereof. The depicted single tray includes a plurality of substrates (not shown), each substrate having a single component. In other embodiments (not shown), depending on the size, a single alignment tray can hold a single substrate having one or more components. The alignment means in this embodiment is a hole that allows the use of, for example, a pin or a rod to be properly aligned with a magnet tray (not shown) so that the magnet tray and the alignment tray are arranged vertically and the magnets in the magnet tray are aligned with the corresponding components to interconnect to the substrate on the alignment tray. Because proper alignment is important for the successful formation of the interconnection, in various embodiments the alignment tray may include simple features, such as varying hole geometries, hole patterns or offsets, different hole sizes, combinations of holes and pins, and complementary structures in the magnet tray that ensure that the alignment tray and the magnet tray can only be aligned in a single orientation relative to each other. The skilled person will recognize that there are many technically recognized methods for achieving proper alignment between two such objects.

[0117] In yet another aspect, the present disclosure provides a kit for creating an interconnect between a substrate and an electronic component attached to the substrate using a magnetically alignable anisotropic conductive adhesive. The kit generally includes:

[0118] at least one magnetic tray, the at least one magnetic tray comprising a non-magnetic tray adapted to hold one or more magnets in a position corresponding to a desired placement of an electronic component on a substrate and connection of the component to the substrate using an ACA;

[0119] Sufficient magnets to complete the magnet tray, each magnet of the desired size and strength for making interconnections between the component and the substrate using the ACA; and

[0120] At least one alignment tray adapted to receive and hold the substrate and components populated on the substrate to form interconnects during alignment and curing of the ACA.

[0121] Optionally, the kit further comprises an ACA adapted for use with the kit to create an interconnect between a component and a substrate using the kit.

[0122] The magnet tray and alignment tray are generally configured to be oriented vertically relative to each other and can be assembled so that when the magnet tray and alignment tray are so oriented and assembled, the electronic components on the substrate placed on the alignment tray are vertically aligned with the magnets on the magnet tray. In various embodiments this configuration is used for both the alignment and curing processes.

[0123] In a presently preferred embodiment, the oriented and assembled magnet tray and alignment tray ("assembly") can be placed into a curing oven. In one embodiment, the magnet tray or assembled tray is used as a rack in an oven, or for transfer to a rack in a semi-continuous or continuous oven such as a reflow oven or curing tunnel.

[0124] In various embodiments, when the magnet tray and alignment tray are assembled together, for each magnet in the magnet tray, the magnetic flux lines are substantially parallel to each other and substantially perpendicular to the XY plane in an area corresponding to an area of ​​the substrate on which the component is located. Typically, the ACA positioned between the substrate and the component thereon forms a substantially uniform column that is substantially perpendicular to the XY plane of the component and substrate when the tray is oriented and assembled.

[0125] In yet another aspect, the present disclosure provides an oven system for creating an interconnection between a substrate and an electronic component to be placed on the substrate and connected to the substrate using an ACA. These systems generally operate as described above for other systems described herein and in accordance with these methods. Typically the oven system comprises: a curing oven and one or more shelves or racks, each shelf or rack comprising: a magnetic tray, the magnetic tray being equipped with one or more magnets, each magnet being placed in a position corresponding to the position of an electronic component to be placed on the substrate and connected to the substrate using an ACA; and an alignment tray, the alignment tray being adapted to accommodate and hold a substrate, the substrate being filled with one or more components to be placed on the substrate and connected via the ACA.

[0126] The magnets are, in one embodiment, permanent magnets.Rare earth magnets can be used for many applications herein, including magnets containing neodymium, such as NIB magnets.

[0127] In various embodiments of the oven system, for each magnet in a magnet tray of the system, the magnetic flux lines are substantially parallel to each other and substantially perpendicular to the XY plane in an area corresponding to an area of ​​the substrate on which the parts and ACA are located. The ACA forms a substantially uniform column that is substantially perpendicular to the XY plane of the parts and substrate in various embodiments.

[0128] exist Figure 4 An embodiment of an oven system is shown in FIG. As can be seen, each assembly of the magnet tray and alignment tray can be used as a rack in a batch oven which is typically designed to accommodate multiple such racks. An enlarged view of the assembly is shown as an inset. Figure 4 (B) in the illustration includes the assembled magnet tray and the alignment tray that holds the substrate, components, and ACA during alignment of the posts in the Z axis and throughout the curing process. The alignment holes ensure that the components can only be placed together in the proper orientation. Figure 4 (C) shows a separate magnet tray showing multiple permanent magnets in place.

[0129] The scope of the present invention is set forth in the appended claims, subject, for example, to language limitations. Although specific terms are used to describe the present invention, those terms are used only in a general and descriptive sense and not for limiting purposes. In addition, although some currently preferred embodiments of the claimed invention have been described herein, those skilled in the art will recognize that such embodiments are provided only by way of example. In view of the teachings provided herein, those skilled in the art will appreciate that certain variations, modifications and substitutions will occur to them. It should therefore be understood that the present invention may be practiced in a manner different from that specifically described, and that such a manner of practicing the present invention is within the scope of the claims, or is equivalent to the scope of the claimed protection, and does not depart from the scope and spirit of the present invention as claimed.

Claims

1. An oven system for creating interconnections between a substrate and an electronic component to be placed on the substrate and connected to the substrate using an anisotropic conductive adhesive (ACA), the system comprising: a curing oven and one or more shelves or racks, each such shelf or rack including a magnet tray equipped with one or more magnets, each magnet being positioned in a position corresponding to a position of an electronic component to be placed on the substrate and connected to the substrate using the ACA; as well as an alignment tray adapted to receive and hold a substrate populated with one or more components to be placed on the substrate and connected via the ACA; in: The alignment tray and the magnet tray are made of non-magnetic materials; The ACA includes magnetically alignable particles capable of forming interconnects that conduct electricity in the Z-axis when exposed to a magnetic field; the magnet tray and the alignment tray being removably arranged vertically together during use such that the components on the substrate are vertically aligned with the magnets in the magnet tray and the ACA is exposed to a magnetic field such that flux lines are substantially perpendicular to an XY plane defining the substrate on which the electronic components and the ACA are located; and The substrate can be placed in the alignment tray in only one orientation.

2. The oven system according to claim 1, wherein: The magnet comprises a permanent magnet.

3. The oven system according to claim 2, wherein: The size and strength of each magnet is independently determined to optimize the height of the post, to optimize the interconnect strength, to reduce the number of short circuits, to increase the life expectancy of the completed interconnect, to increase the yield of usable products including the interconnect, or to reduce failures or scrap resulting from creating the interconnect.

4. The oven system according to claim 1, wherein: In the presence of a magnetic field, the ACA forms a pillar that is substantially uniform in height and diameter, and the pillar is substantially perpendicular to the XY plane of the electronic component and the substrate.

5. The oven system according to claim 1, wherein: The alignment tray comprises alignment means to ensure that the magnet tray and the alignment tray can only be assembled in a proper orientation relative to each other.

6. The oven system according to claim 1, wherein: The alignment tray and the magnet tray include materials capable of withstanding conditions used to cure the ACA in the oven.

7. The oven system according to claim 6, wherein: In use, each shelf or rack comprises an assembly of said magnet tray, said alignment tray and said base plate populated with components.

8. The oven system according to claim 7, wherein: Each shelf or rack can be conveyed into or out of the oven in batches, semi-continuously, or continuously.

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