KR20200111162A - System and method for improved electronic component interconnections - Google Patents

Abstract

Systems and methods are provided for improved interconnections to electronic components using ACAs. The methods involve using magnets that are specific for each component to be connected and are optimized in terms of size and strength, and position relative to the substrate and component. Kits are also provided that provide ovens adapted for use with methods and systems and parts of the system for use with existing ovens.

Description

System and method for improved electronic component interconnections

Cross-reference to related applications

This application claims priority to U.S. Provisional Patent Application No. 62/586,815, filed on November 15, 2017, the entirety of which is incorporated herein by reference.

Field of invention

The present application relates generally to establishing electrical connections of components in electronic circuitry. More particularly, this disclosure relates to improved methods of connecting components to a substrate using anisotropic conductive adhesives.

As the modern demand for technology increases, the number of electronic devices continues to increase, the availability and adoption of these devices continues to increase, the size of these devices continues to decrease, and the interconnection of electronic components required to manufacture these devices. The number of interconnects has increased significantly. Moreover, in many fields the previous analog devices have almost disappeared as these devices are replaced by electronics, and the size of electronic devices has decreased dramatically, while the power of those devices continues to expand rapidly.

As modern components become smaller and more powerful, there is more circuitry in smaller spaces on these components (i.e., increasing the density of circuitry), allowing for example between different aspects of a given chip or component. The errors have become much tighter (ie, the pitch has become smaller-"ultra-small pitch").

Thus, modern components are often more sensitive to temperature and pressure, either temperature or pressure can cause problems, and failure of the component and the entire device it is part of. Unfortunately, for example, current means of creating interconnects between components and their substrates all have limitations and drawbacks for certain applications.

There are a number of interconnecting means (e.g. traditional solder, anisotropic conductive films (ACFs) and anisotropic conductive adhesives (ACAs)), each of which has advantages and limitations. One of ordinary skill in the art will understand that each of them provides options that can meet the requirements for specific interconnections to specific applications, components, or devices.

Traditional soldering involves the exposure of components that are connected to a large amount of heat and pressure locally. Exposure of these components to these unfavorable or unsupportable conditions can lead to apparent failure, poor or unreliable performance, or significantly reduced lifetime.

As an effort to improve interconnects for various applications, ACFs have been developed. These conductive films can reduce the local heat required for connection by soldering, but can still require significant heat. In addition, both heat and pressure are typically applied to the components, which can be a significant limitation for sensitive components. ACFs also have limitations as to the pitch of interconnects they are suitable or can accommodate.

ACAs have also been developed to provide alternative solutions for creating difficult interconnects in specific applications. Like ACFs, these adhesives provide electrical conductivity only in the z-axis. ACAs, such as those produced by SunRay Scientific, contain magnetically alignable particles that form interconnects between components when the particles are aligned along the z-axis by exposure to a magnetic field. The adhesive matrix is then cured, such as by exposure to heat, to complete and fix the interconnect. Since no pressure is required, ACAs are good candidates for pressure sensitive components. In addition, curing can be accomplished at low heat for temperature sensitive components. Moreover, ACAs allow finer pitch applications than can be achieved using ACFs.

Prior art applications of ACAs generally employ a magnetic field applied across the entire substrate using an electromagnet. This field covers all components residing on the substrate, but can be disadvantageous in applications where one or more components on the substrate are sensitive to magnetic fields. In addition, the magnetic field applied to a large area includes the entire magnetic field including flux lines that are generally not perfectly perpendicular to the x-y plane.

While creating interconnects with ACAs is simple and easy, there is nevertheless a need for improved systems and methods for creating and optimizing interconnects using ACAs in specific applications.

The inventors have discovered methods that provide unexpected improvements in ACA-based electronic interconnects for specific applications and have developed a system that implements the methods. The methods select the appropriate ACA properties, use separate magnets positioned for each component to be interconnected, and select the properties of the magnets used for alignment of the ACA for each particular component residing on the substrate. Thus, it provides several advantages based on optimizing the creation of z-axis connections (in terms of height, number and direction of z-axis columns). Those methods allow the construction of what the inventors refer to as a'magnetic palette' that provides consistent optimal alignment and curing of ACA-based interconnects. The methods can provide improved interconnect consistency, reduced failures, improved lifetime and increased yields of functional connections, compared to existing methods of forming interconnects.

In a first aspect, the present disclosure provides novel methods of aligning and curing ACA based interconnections in digital devices, electronics, and the like. Methods of establishing an interconnect between a substrate and an electronic component residing on the substrate using a magnetically alignable anisotropic conductive adhesive (ACA) generally include:

a) Establishing dimensions and locations on the substrate of a first electronic component disposed on the substrate and to be connected to the substrate;

b) Determining a placement location of the first magnet corresponding to the dimension and location established for the component in step a);

c) Determining the dimensions and strength of the magnet required in step b); And

d) And mapping the magnetic flux lines of the magnetic field to the magnet.

Steps a) to d) are repeated for each additional component to be placed on and connected to the substrate to determine the placement location and properties for each additional magnet required;

That way,

f) Creating a magnetic tray and securing each magnet to a respective batch location of each magnet on the tray;

g) Creating an alignment tray and adapting the alignment tray to hold the substrate during alignment and curing;

h) Placing the substrate on the alignment tray;

i) Applying the ACA to the substrate at a location suitable for interconnecting each component to be disposed on the substrate;

j) Housing the first component to which the ACA has been applied and each additional component on the substrate;

k) Assembling the alignment tray and the magnetic tray;

l) Allowing columns to be formed on the z-axis with ACA; And

m) By curing the ACA, establishing interconnects between the substrate and the first component and each additional component.

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

In a second aspect, a system is provided for creating interconnects between a substrate and electronic components attached to the substrate using a magnetically alignable anisotropic conductive adhesive (ACA). The systems generally include a magnetic tray including a nonmagnetic tray adapted to receive and hold each of the one or more magnets disposed therein, in a location corresponding to the location of the one or more electronic components on a substrate to which the components are to be connected.

The systems also include an alignment tray adapted to hold a substrate on which one or more components to be connected to the substrate to the ACA reside during alignment and curing of the ACA.

The systems also include an ACA comprising magnetically alignable particles that can form conductivity to interconnects in the z-axis.

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

In the presently preferred embodiments, the magnets are permanent magnets. In general, for each magnet in the magnet tray, the lines of magnetic flux are substantially parallel to each other and substantially perpendicular to the x-y plane in an area corresponding to the area of the substrate in which the component and ACA are located. In the presently preferred embodiment, the magnetic flux lines consist essentially of lines parallel to each other and perpendicular to the area of the substrate in which the component and ACA are located.

In a third aspect, the present disclosure provides a kit for creating interconnects between a substrate and electronic components attached to the substrate using a magnetically alignable anisotropic conductive adhesive. Kits are generally,

At least one magnetic tray including a non-magnetic tray adapted to hold one or more magnets using the ACA at locations corresponding to a desired placement of the electronic component on the substrate and connection of the component to the substrate;

Enough magnets to complete the magnetic tray-each magnet is of the desired size and strength to make an interconnection between the component and the substrate using an ACA;

At least one alignment tray adapted to receive and hold the substrate and components residing on the substrate during alignment and curing of the ACA to form an interconnect; And

Optionally, the kit includes an ACA suitable for use with the kit to create at least one interconnect between the component and the substrate.

In the kits provided, the magnetic tray and alignment tray are configured to be oriented perpendicular to each other. They are assembled such that when the magnet tray and the alignment tray are assembled in such a way, the electronic components (to be connected to the substrate with ACA) placed on the substrate on the alignment tray are vertically aligned with the magnets on the magnet tray. Each component requiring a connection (interconnect) has a corresponding magnet to which each component will be aligned when the trays are assembled.

In the presently preferred embodiments of the kits, the magnets include rare earth magnets, or other permanent magnets.

In another aspect, the present disclosure provides oven systems designed to create interconnections between a substrate and an electronic component disposed on the substrate and to be connected to the substrate using an ACA. Oven systems generally include a curing oven and one or more shelves or racks, each of which

A magnetic tray disposed on the substrate and into which one or more magnets each disposed at a location corresponding to a location of an electronic component to be connected to the substrate are fitted using ACA; And

And an alignment tray disposed on the substrate via the ACA and adapted to receive and hold a substrate on which one or more components to be connected to the substrate reside.

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.

1 is a cross-sectional schematic diagram of one embodiment of a system for magnetically aligning and curing ACA interconnects showing the magnetic tray, alignment tray, substrate, and components residing on the substrate in which magnets are placed.
2 is a flow chart showing steps of a method of magnetically aligning and curing components on a substrate using an ACA to create an electrical connection.
3 is a diagram showing one embodiment of an alignment tray for use with the present invention. The tray includes a plurality of substrates, each substrate having a habitable component disposed on and to be connected to the substrate.
4 is a diagram showing an embodiment of an oven employing a magnetic pallet system. A. Multiple magnetic tray and alignment tray assemblies are shown in a batch oven. The alignment and outer dimensions of the magnetic trays are dictated by the oven dimensions, but otherwise each magnetic tray or each alignment tray need not be the same. Thus, a single oven may be used to align and cure multiple interconnects for multiple electronic components on different substrates or devices. B. Shows an enlarged view of an assembly comprising an alignment tray and a magnet tray with orientation means (alignment holes). C. Shows a close-up overhead diagram of a magnetic tray acting as a rack in the oven

Methods and systems are provided herein for providing improved and more consistent interconnects for electronic components using ACAs.

Definitions and abbreviations

Unless explicitly defined otherwise, all technical and scientific terms, technical terms, and acronyms used herein are to those of ordinary skill in the art in the field(s) of the present invention in which the term is used. Have meanings commonly understood by In accordance with this description, the following abbreviations and definitions apply.

Abbreviations

The following abbreviations apply unless otherwise indicated:

AC: A.C;

ACA: Anisotropic conductive adhesive;

ACF: Anisotropic conductive film;

DC: direct current;

Gs: Gauss, magnetic field unit;

NIB: Neodymium-iron-boron;

PCB: Printed circuit board; And

T: Tesla, magnetic field unit (SI).

Definitions

As used herein, “substantially” can mean an amount greater or less than a reference item. Preferably substantially larger (or more) or smaller (or less) means at least about 10% to about 100% or more than the corresponding reference item. More preferably, "substantially" in these instances means at least about 20% to about 100% or more, greater or less than the reference item. As one of ordinary skill in the art will understand, the term'substantially' means more than 51% of the referenced item, number, or amount, preferably 60%, 67%, 70%, 75%, 80%, 85%, 90 It can also be used as in "substantially all" which means greater than or equal to %. “Substantially all” may also mean greater than 90%, including 91, 92, 93, 94, 95, 96, 97, 98, 99 or more percent of the referenced item, number, or amount.

As used herein, the singular form of a word includes the plural, and vice versa, unless the context explicitly states otherwise. Thus, references to “a”, “an”, and “the” generally include plural forms of the respective terms. For example, reference to “electrode” or “diode” includes a plurality of such “electrodes” or “diodes”.

The words "comprising" and "comprising" are to be interpreted as inclusive and not exclusive. Similarly, the terms "having", "having" and "or" are to be construed as all-inclusive, unless such configuration is expressly prohibited in the context. In addition, forms of the terms “comprising” or “having” are intended to include embodiments covered by the phrases “consisting essentially of” and “consisting of”. Likewise, the phrase “consisting essentially of” is intended to include embodiments covered by the phrase “consisting of”.

When used herein, ranges are provided as abbreviations to avoid listing and listing each and every value within the range. Any suitable value within the range, if appropriate, may be selected as the upper value, lower value, or terminus of the range.

Formulations, compositions, methods and/or other advances disclosed herein are not limited to the specific techniques, protocols, and/or components described herein, as those skilled in the art will understand. This is because it can be variable. Moreover, terms used herein are for the purpose of describing specific embodiments only, and are not intended to limit the scope of the disclosed or claimed application, and are not intended to limit such scope.

Any formulations, compositions, methods, or other means or materials similar or equivalent to those described herein may be used in the practice of the present invention, but preferred formulations, compositions, methods, or other means Or materials are described herein.

Any references, including any patents, patent applications, or other publications, technical and/or academic papers cited or referred to in this specification, are hereby incorporated by reference in their entirety to the extent permitted under applicable law. Included in the disclosure. Any discussion of those references is intended only to summarize the claims made in those documents. It is not admitted that any such patents, patent applications, publications or references are prior art, or that any portion of it is any one of the relevance or material of patentability of what is claimed herein. Applicant specifically reserves the right to challenge the accuracy and appropriateness of any claim that such patents, patent applications, publications, and other references are prior art, or related, and/or material.

As used herein, “alignment” means aligning a magnetic material or composition comprising magnetic particles. In general, alignment refers to the arrangement of magnetic particles in the z axis under the influence of a magnetic field. Alignment is the process by which columns are formed along the z-axis. As will be apparent from the context, sometimes'alignment' is also used herein to refer to ensuring proper orientation of two things-such as an alignment tray and a magnetic tray, or a substrate and an alignment tray-relative to each other.

As used herein, "columns" refer to structures formed by magnetic particles in a composition in the z-axis under the influence of a magnetic field. The process of column formation is sometimes referred to as'alignment'. Column properties (eg, height, diameter, etc.) will be determined by the properties of the ACA, including the strength of the magnets and the size and amount of magnetic particles in the ACA, and the viscosity and other physical properties of the ACA matrix. Columns can and will form within seconds after exposure to a suitable magnetic field.

Whether a "magnet" is generated by an electromagnet or a permanent magnet as used herein can generate a "magnetic field", including any magnetic field. The “strength” of a magnet can be measured in Gs (or Ts). One of ordinary skill in the art will understand how to determine the strength of any given magnet, or how to determine the desired magnetic strength for a given magnet. "Magnetic field mapping" as used herein refers to determining a specific shape of a magnetic field and a path of magnetic field lines. One of ordinary skill in the art will understand how to map the magnetic field of any magnet through various means.

As used herein, "permanent magnet" refers to a magnet that does not require current to flow in order to have a constant magnetic field. Permanent magnets for use herein may include iron, nickel, cobalt, and rare earth metals. Certain currently preferred embodiments of the present specification utilize rare earth magnets such as those containing lanthanoid elements. Magnets containing neodymium, or salts thereof, may be useful herein because of the magnetic strength of the magnets. In one embodiment, the magnets include neodymium, iron, and boron ("NIB magnets"). Samarium, gadolinium, and even dysprosium, and salts thereof, can be used for certain applications. Other types of permanent magnets, such as ceramic magnets and other composite magnets, and even flexible magnets may be suitable for use herein for other specific applications.

As used herein, an “interconnect” is generally a connection between any two aspects of a system. Interconnects herein generally reflect, for example, electrical and physical connections between two components or a component and a substrate. "Substrate" is any material used to hold or contain other electronic components that are connected to a substrate for use in an electronic system or device, such as a printed circuit board ('PCB'). Substrates can be flexible or rigid. Preferred rigid substrates include, for example, PCBs, composites, and rigid polymers; Preferred flexible supports include, for example, soluble polymers.

As used herein, "parallel" means that two lines, such as lines representing a magnetic flux, are always at the same distance and are never in contact with each other and are in the same plane, that is, their lines are zero relative to each other. It means that you are on the road. Parallel lines in this specification are generally reference flux lines in the z-axis, and these are generally perpendicular (ie, 90 degrees) to the x-y plane of the substrate. Due to the difficulty of having completely parallel magnetic flux lines throughout the entire application involving multiple magnets, the parallel lines in the various embodiments herein are "substantially parallel" to each other and/or to XY. It may include substantially vertical lines. These lines may be located, for example, from about -30 degrees to about 30 degrees to each other and/or from about 60 degrees to about 120 degrees to the Z-Y plane. More preferably these lines may be located, for example, from about -15 degrees to about 15 degrees with respect to each other and/or from about 75 degrees to about 105 degrees with respect to the Z-Y plane. Even more preferably substantially parallel magnetic flux lines are located, for example, from about -5 degrees to about 5 degrees with respect to each other, and/or from about 85 degrees to about 95 degrees with respect to the x-y plane of the substrate. Even more preferably the substantially parallel lines are located within about 0 degrees to about 2 degrees relative to each other and/or within about 0 degrees to about 2 degrees relative to the x-y plane of the substrate. The more magnetic flux lines are approximately parallel to each other and perpendicular to the xy plane, the more the ACA will form parallel columns during the alignment that will be the basis of the interconnect and negatively affect either the functionality or durability of the interconnects so formed. One of ordinary skill in the art will understand that there will be fewer shorts and other defects that will affect.

As used herein, "z-axis" means a main plane on which a substrate is placed, ie, a direction perpendicular to the x-y plane.

Detailed description of exemplary embodiments

Systems and methods for creating improved and more consistent electronic interconnects from electronic circuits to ACAs are provided in this disclosure. These systems generally include individual magnets placed in a location corresponding to each component to which it is connected. The size and strength of each magnet is determined based on the component, substrate, ACA in use, and the application in question. Only components connected to the ACA are exposed to arbitrary magnetic fields, which means that sensitive components are not exposed to unnecessary magnetic fields. Advantageously, optimized interconnects provide better yields, fewer shorts and other failures, and longer lifetimes/more cycles. The inventors have surprisingly found that by employing a strategic choice of magnet size, strength, and placement, the consistency and quality of interconnects can be substantially improved. Thus, methods and systems for improving the creation of interconnects using ACAs are disclosed herein.

In a first aspect, the present disclosure provides novel methods of aligning and curing ACA based interconnections in digital devices, circuit boards, electronics, and the like. Methods of establishing an interconnect between a substrate and an electronic component residing on the substrate using a magnetically alignable anisotropic conductive adhesive (ACA) generally include the following steps:

a) Establishing dimensions and locations on the substrate of a first electronic component disposed on the substrate and to be connected to the substrate;

b) Determining a placement location of the first magnet corresponding to the dimension and location established for the component in step a);

c) Determining the dimensions and strength of the magnet required in step b); And

d) Mapping the magnetic flux lines of the magnetic field to the magnet.

Steps a) to d) are repeated for each additional component to be placed on and connected to the substrate to determine the placement location and properties for each additional magnet required. One of ordinary skill in the art will appreciate that there are various methods referred to herein where various steps are referred to throughout the specification. In all cases where these steps are not strictly required to be performed in the order described, the methods are equivalent by performing the steps in a different order than that most facilitates the achievement of successful interconnects without altering the overall purpose and outcome. It should be noted that it can be done.

The method includes creating a magnetic tray and binding each magnet to a respective batch location of each magnet on the tray; And adapting the alignment tray to create the alignment tray and retain the substrate during curing and alignment of the ACA in the z-axis (ie, column formation).

The substrate is then placed on the alignment tray. The ACA is applied to the substrate on which the components will be placed. The substrate is then inhabited by the first and each additional component.

The alignment tray (including the substrate, components to be attached, and the ACA applied) and the magnetic tray are assembled to expose the ACA to the magnets. Sufficient exposure time is provided to allow the columns to form in the z-axis in the ACA; The ACA is then cured to establish interconnects between the substrate and the first and each additional component.

In general, the alignment tray and magnetic tray are made of non-magnetic material, such as aluminum or heat-stable materials, such as plastics or composites. The magnet tray is generally adapted to receive the first and each additional magnet at their respective placement locations on the tray. A completed assembly comprising a magnetic tray with magnets and an alignment tray with a substrate in which the components and the ACA reside may be placed in a curing oven.

In various embodiments, the magnets include permanent magnets. The magnets comprise rare earth magnets in one presently preferred embodiment. Rare earth magnets including neodymium or NIB magnets are used in one embodiment.

The inventor has found that the size and strength of the magnets to create the interconnects can be determined empirically for each application to optimize the consistency and quality of the interconnects being formed. One of ordinary skill in the art will understand that selecting the size and strength of a particular magnet will be relevant to the process of forming the column, and that magnet selection will be influenced by the desired properties of the columns such as the height, diameter, and strength of the column. Moreover, the connections of the column to both the component and the substrate are also affected by the magnetic properties.

Thus, in certain embodiments, the size and strength of the magnets are determined to optimize or resolve the properties of the column or final interconnects. These attributes may include the height of the columns, the strength of the interconnect, the number of resulting shorts, the expected life of the finished device or board, the yield of product usable, or the number of failures or rejects resulting from the process of creating the interconnects. I can.

The inventor has also determined that distinct advantages arise using magnetic flux lines that are substantially parallel to each other and/or substantially perpendicular to the x-y plane in an area corresponding to the area of the substrate in which the component and the ACA are located. In various embodiments the lines of magnetic flux consist essentially of these parallel and/or vertical lines.

In various embodiments, the ACA forms columns that are substantially uniform in height and diameter as a result of using the methods provided. In presently preferred embodiments, the ACA forms substantially uniform columns that are substantially perpendicular to the x-y plane of the component and substrate.

To further optimize the method, to further improve the consistency and to make the method more robust, in one embodiment, the geometry of the portion of the alignment tray that receives and/or holds the substrate is such that the substrate is aligned in only one orientation. It is configured to be placed in a tray. This allows the technician to reproducibly place the substrate on the alignment tray for production.

In other embodiments, the alignment tray includes alignment means such as placement pins, complementary structures, etc. to ensure that the magnetic tray and alignment tray can only be assembled in an appropriate orientation relative to each other. Alternatively, the alignment and geometry of the magnetic trays allow assembly in only one (proper orientation). One of ordinary skill in the art will understand that there are a number of simple ways to provide an appropriate orientation. Again, these features will further increase the consistency and will allow any technician to use the production method.

As discussed above, in general, the methods allow an assembly comprising a positioned magnetic tray and alignment tray to be placed directly into the curing oven. Preferably the alignment tray and magnet tray contain materials that can withstand the curing conditions for curing the ACA. In one embodiment, the trays are aluminum or thermal stability capable of withstanding, for example, 50-70 C, 60-80 C, 70-100 C, 75-120 C, 100-140 C, or even higher temperatures, They are non-magnetic materials. It is expected that low temperature curing methods will continue to be developed in which the materials used in the alignment and magnetic trays can be correspondingly modified.

The methods can be more fully understood with reference to the drawings. 2 shows a flow diagram for one embodiment 200 of the methods described herein. As can be seen, the methods begin with an understanding of the substrate, as mentioned in step 210, and the components disposed on the substrate and to be connected to the substrate using an ACA. The dimensions and location of each component may be mapped to allow determination 220 of the design of the magnet tray and the required placement location of each magnet.

The size and strength of each magnet may be determined based on application specifics (225). The properties of the magnetic field, such as magnetic flux lines for each magnet, may be determined or mapped 230. One of ordinary skill in the art will understand how to determine the size, strength, and flux lines for each magnet required. One of ordinary skill in the art will also appreciate that the order of steps described above may be varied as would be desirable for a given application.

One of ordinary skill in the art will further appreciate that the properties of the magnet(s) will affect the development and formation of the columns in the z-axis within the ACA. Stronger magnets will allow higher columns to form faster, but it is not desirable that the magnet is too strong. In various embodiments, the ideal properties of the magnets are determined empirically for any given application.

A magnetic tray is created (235) and the magnets selected for operation are bound (240) to their respective locations. It is understood that the magnetic tray is designed to receive each of the magnets in their respective location by any useful means that does not change the magnetic field or position of the magnet with respect to the component and substrate. In one embodiment, the magnetic tray is made of aluminum with cut-out holes in the locations where each of the magnets will be placed. The magnets can again be bonded in place by any means without changing the strength or flux lines of the magnet (240). Adhesives may conveniently be used to bind the magnets to the magnet tray in certain embodiments.

An alignment tray is created 245 to serve as a carrier for the substrate and components and to ensure that the substrate and each component residing on the substrate align with a corresponding magnet in the magnet tray. The alignment tray is adapted to receive and hold the substrate during alignment and subsequent curing of the ACA (250). The tray can be adapted by any means for binding the substrate during the process of creating the interconnections. In one embodiment, concave regions that are complementary to the shape of the substrate are created to passively receive and hold the substrate during processing. In the presently preferred embodiment, the substrate is received in only one orientation in the alignment tray, thereby minimizing the risk of misalignment with the magnets in the magnet tray.

The ACA is applied (265) to the substrate at the locations where the components will be placed (260). In some embodiments contemplated herein the steps may be variable, eg, components may reside and the ACA may be applied simultaneously. Those of skill in the art will also appreciate that the order of operation can be so variable here, assuming that the end result is that each component is correctly placed at the desired location on the substrate with the desired amount of ACA between the two.

The alignment tray and magnet tray are then brought into close proximity to each other. In the presently preferred embodiment, the trays must be aligned while being positioned perpendicular to each other. This is reinforced by a structure that prevents the alignment tray with the substrate from sliding across the magnetic fields of the magnets in the magnet tray and initiating improper column formation. By requiring the magnet tray and alignment tray to be close in this manner, column formation is substantially optimized and limited in the z-axis. The trays 270 so assembled ('assembly' or magnetic pallet assembly) can then be placed in an oven for curing under appropriate conditions. Because the assembled trays fit together in a way that optimizes the formation of parallel z-axis (i.e. vertical) columns, and because the assembly can be moved without substantially interfering with the columns, the oven is It may be a batch oven that is manually moved in and out of the oven, or it may be semi-continuous or even continuous, such as a reflow oven in which assemblies move along a conveyor through the oven. There is little risk of affecting the column structure after the ACA has cured; That is, the columns are stable in cured ACA.

It should also be noted that a phenomenon called'chip flipping' in this specification may occur with certain components. If a component is magnetically polarized—that is, if it has, for example, two separate magnetic poles, then when exposed to the magnetic field of the magnet tray, the component will'flip' to align itself with the magnetic field. Since the ACA has not yet been aligned or cured when the system is exposed to the magnetic tray, nothing prevents the chip(s) from doing so. In extreme cases, the component can be completely removed from the substrate. This only occurs in certain components, but if it exists, it becomes a problem. The inventor has developed a simple solution to solve this problem if such components exist. This requires the inclusion of an additional'tacking' step to fasten the component/chip prior to exposure to the magnetic tray. Typically, the components of interest are bound to the substrate. One useful method is to apply a small amount of epoxy to hold the sensitive component in place in the presence of a magnetic field. The methods herein include the use of a UV curable epoxy applied in a small amount sufficient to hold the component, followed by short exposure to UV light of sufficient intensity and duration to ensure that the epoxy cures. The assembly of the substrate, component, and ACA can then be placed in appropriate proximity to the magnet tray to allow the z-axis columns to be formed without concerns about flipping of the components/chips.

In a second of several aspects of the present disclosure, the present disclosure provides a system for creating interconnects between a substrate and electronic components attached to the substrate using a magnetically alignable anisotropic conductive adhesive (ACA). The system includes a magnetic tray including a nonmagnetic tray adapted to receive and hold each of the one or more magnets disposed therein, in a location corresponding to the location of the one or more electronic components on a substrate to which the components are to be connected.

The system also includes an alignment tray adapted to receive a substrate on which one or more components to be connected to the substrate with an ACA reside. The alignment tray can hold the substrate during alignment and curing of the ACA.

The system also includes an ACA comprising magnetically alignable particles that can form conductivity to interconnects in the z-axis. The ACA formulation may vary depending on the specific applications, which may be dictated by the nature of the electronic components or the device to which the components are interconnected. ACAs can be formulated with different sized electromagnetic/conductive particles, for example, for applications with different pitch requirements.

In preferred embodiments of the present application, the alignment tray and magnetic tray may be made of a non-magnetic material. In one embodiment the substrate may be placed in only one orientation on the alignment tray to avoid confusion and mistakes and to allow non-technical staff to support production.

In general, the magnet tray and alignment tray are adapted to be vertically aligned together in a detachable manner so 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. This arrangement is preferably maintained until curing of the ACA is complete.

In various embodiments of this system the magnets are permanent magnets. Rare earth magnets, including magnets containing neodymium, such as NIB magnets, are useful for many applications herein. These magnets can provide a strong magnetic field.

An assembly comprising a magnetic tray, an alignment tray, and a substrate on which the components reside may be placed directly into the curing oven in one embodiment. This makes it possible for the aligned ACA to cure with minimal movement with little risk of disturbing the columns formed in the z-axis when exposed to a magnetic field. In another embodiment the assembly and/or magnetic tray serves as a rack that can slide directly into the oven and does not require any support shelves or additional racks for use. In other embodiments, the assembly may be placed on a conveyor mechanism for use with a semi-continuous or continuous process oven. In these embodiments, the conveyor has the same for different configurations of the substrates and components-each corresponding to its own magnetic tray designed according to the substrate and the components to be interconnected with specifics-a number of different assemblies. Can include.

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 x-y plane in an area corresponding to the area of the substrate in which the component and ACA are located. Optimal interconnections can arise from these arrangements. The ACA forms substantially uniform columns substantially perpendicular to the x-y plane of the component and substrate in various embodiments.

With further reference to the figures, FIG. 1 depicts an embodiment 100 of a system for magnetically aligning and curing ACA interconnects that illustrate certain features of the system. A cross-sectional view of an embodiment for magnetically aligning and curing ACA interconnects is shown, showing a nonmagnetic magnet tray 110 with a plurality of magnets 120 positioned therein. The magnet tray 110 has openings (not numbered for convenience and clarity) for receiving the magnets 120, which do not change the magnetic flux lines or otherwise interfere with the magnets 120. It may be bound in the magnetic tray 110 using adhesive (not shown) or other binding means. The alignment tray 130 has a recess to receive the substrate 140 held in place during alignment and curing of the ACA to form the interconnects. Substrate 140 has a plurality of electronic components 150 positioned on the substrate. An ACA (not shown) is applied/located (or is likely to be applied) between components 150 and substrate 140. As can be seen, the placement of each of the magnets 120 corresponds to the location of the component 150 on the substrate 140 such that the magnets 120 are vertically aligned with the components 150. In this configuration the magnetic field provides the force to align the electronic particles of the ACA (not shown) to form a z-axis column. As can be seen, the area covered by each of the magnets 120 is larger than the area covered by the corresponding component 150, so that the system 100 has a prior art covering the entire surface of the substrate. Compared to electromagnets, or magnets of the same size as the component, they provide a more optimal and consistent alignment.

3 depicts one embodiment of an alignment tray 300 illustrating various aspects. The depicted single tray 310 includes a plurality of substrates (not shown) each having a single component 320. In other embodiments that depend on size (not shown), a single alignment tray may hold a single substrate with one or more components. The presence of the alignment means 330 that are holes in this embodiment is a magnetic tray (not shown) such that the magnet tray and alignment tray are arranged vertically and the magnets in the magnetic tray are aligned with the corresponding components to be interconnected to the substrate on the alignment tray ), for example using pins or rods. Since proper alignment is critical to the successful formation of interconnects, in various embodiments the alignment trays are complementary structures in the magnet tray to ensure that the alignment tray and the magnet tray can only be aligned in a single orientation relative to each other. With simple features, such as various hole geometries, hole patterns or offsets, different hole sizes, combinations of holes and pins. One of ordinary skill in the art will appreciate that there are many technically recognized methods for achieving proper alignment between these two objects.

In another aspect, the present disclosure provides kits for creating interconnects between a substrate and electronic components attached to the substrate using a magnetically alignable anisotropic conductive adhesive. Kits are generally,

At least one magnetic tray including a non-magnetic tray adapted to hold one or more magnets using the ACA at locations corresponding to a desired placement of the electronic component on the substrate and connection of the component to the substrate;

Enough magnets to complete the magnetic tray-each magnet is of the desired size and strength to make an interconnection between the component and the substrate using an ACA; And

And at least one alignment tray adapted to receive and hold the substrate and components residing on the substrate during alignment and curing of the ACA to form an interconnect.

Optionally, the kits further include an ACA suitable for use with the kit to create interconnects between components and a substrate using the kit.

The magnet tray and alignment tray are generally configured to be oriented perpendicular to each other, and when the magnet tray and alignment tray are oriented and assembled perpendicular to each other, the electronic components placed on the substrate on the alignment tray will be assembled so that they are vertically aligned with the magnet on the magnet tray. I can. This configuration is used in both alignment and curing processes in various embodiments.

In the presently preferred embodiment the oriented and assembled magnetic tray and alignment tray (“assembly”) can be placed into the curing oven. In one embodiment, the magnetic trays or assembled trays function as a rack in an oven, or a rack for transport into a semi-continuous or continuous oven such as a reflow oven, or a curing tunnel.

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 xy in an area corresponding to the area of the substrate in which the component is located. Is substantially perpendicular to the plane. In general, when the trays are oriented and assembled, the ACA positioned between the substrate and the component on the substrate forms substantially uniform columns that are substantially perpendicular to the x-y plane of the component and substrate.

In a further further aspect, the present disclosure provides oven systems for creating interconnections between a substrate and an electronic component disposed on the substrate and to be connected to the substrate using an ACA. The systems generally operate as described above with respect to the other systems described herein and according to the methods. Typically oven systems include a curing oven and one or more shelves or racks, each shelf or rack being disposed on a substrate and having one or more magnets each disposed at a location corresponding to the location of the electronic component to be connected to the substrate. Magnetic tray fitted using ACA; And an alignment tray disposed on the substrate through the ACA and adapted to receive and hold a substrate on which one or more components to be connected to the substrate reside.

The magnets in one embodiment are permanent magnets. Rare earth magnets, including magnets containing neodymium, such as NIB magnets, are useful for many applications herein.

In various embodiments of oven systems, for each magnet in the magnet tray of that 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 in which the component and ACA are located. to be. The ACA forms substantially uniform columns, which in various embodiments are substantially perpendicular to the x-y plane of the component and substrate.

An embodiment 400 of an oven system is shown in FIG. 4. As can be seen, each assembly 450 of the magnetic tray 410 and alignment tray 420 serves as a rack 425 in a batch oven 401 generally designed to accommodate such a plurality of racks 425. can do. An enlarged view of the assembly 450 is shown as an inset FIG. 4B, which shows the substrate, components, and ACA (generally 430) during alignment of the columns in the z-axis and throughout the curing process. It includes an assembled magnetic tray 410 and an alignment tray 420 to hold. Alignment holes 435 ensure that the assembly can only be assembled in an appropriate orientation. Inset Figure 4c shows a separate magnet tray 410 showing a plurality of permanent magnets 415 in place.

The scope of the invention is set forth in the claims appended to the detailed description, which are, for example, affected by language limitations. While certain terms are employed to describe the present invention, those terms are used in an inclusive and descriptive sense and not for purposes of limitation. Moreover, while the presently preferred specific embodiments of the claimed invention have been described in this disclosure, those skilled in the art will understand that these embodiments are provided by way of example only. In view of the teachings provided in this disclosure, certain modifications, modifications, and permutations will occur to those of ordinary skill in the art. Therefore, it is understood that the invention may be practiced differently than specifically described and that these methods of carrying out the invention are within the scope of the claims, or are equivalent to those claimed, and do not depart from the scope and spirit of the invention as claimed. Should be.

Claims (20)

A method of establishing an interconnect between a substrate and an electronic component residing on the substrate using a magnetically alignable anisotropic conductive adhesive (ACA), comprising:
a) establishing dimensions and locations on the substrate of a first component disposed on and to be connected to the substrate;
b) determining a placement location of the first magnet corresponding to the dimension and location established for the component in step a);
c) determining the dimensions and strength of the magnet required in step b);
d) mapping the magnetic flux lines of the magnetic field to the magnet;
e) repeating steps a) to d) for each additional component placed on and to be connected to the substrate to determine the placement location and properties for each additional magnet required;
f) creating a magnetic tray and securing each magnet to a respective batch location of magnets on the tray;
g) creating an alignment tray and adapting the alignment tray to hold the substrate during alignment and curing;
h) placing the substrate on the alignment tray;
i) applying the ACA on the substrate to one or more locations where components will be placed;
j) populating the first and each additional component on the substrate;
k) assembling the alignment tray and the magnetic tray;
l) allowing columns to be formed on the z-axis with the ACA; And
m) by curing the ACA, establishing interconnects between the substrate and the first and each additional component.
Including,
The alignment tray and the magnetic tray are made of a non-magnetic material and the magnetic tray is adapted to receive the first and each additional magnet at their respective placement locations on the tray; The method of claim 1, wherein an assembly comprising the magnet tray having magnets, the alignment tray having a substrate on which components reside, and an ACA may be placed in a curing oven. The method of claim 1, wherein the magnets comprise permanent magnets. 3. The method of claim 2, wherein the magnets comprise rare earth magnets. The method of claim 3, wherein the size and strength of each magnet is to optimize the height of the columns, to optimize the interconnect strength, to reduce the number of shorts, to increase the expected life of the finished device or board. , Independently empirically determined to increase the yield of usable product, or to reduce failures or rejections as a result of creating interconnections. The method of claim 4, wherein 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 the area of the substrate in which the component and the ACA are located. Way. The method of claim 1, wherein the ACA forms columns that are substantially uniform in terms of height and diameter. The method of claim 1, wherein the ACA forms substantially uniform columns, the columns being substantially perpendicular to the x-y plane of the component and the substrate. The method of claim 1, wherein the substrate can be placed in only one orientation in the alignment tray. The method of claim 1, wherein the alignment tray comprises alignment means to ensure that the magnetic tray and the alignment tray can only be assembled in an appropriate orientation relative to each other. The method of claim 1, wherein the alignment tray and the magnet tray comprise materials capable of withstanding curing conditions to cure the ACA. A system for creating interconnects between a substrate and electronic components attached to the substrate using a magnetically alignable anisotropic conductive adhesive (ACA), comprising:
A magnetic tray including a nonmagnetic tray adapted to receive and hold each of the one or more magnets disposed therein, in a location corresponding to a location of one or more electronic components on a substrate to which the components are to be connected;
An alignment tray adapted to hold the substrate on which one or more components to be connected to the substrate to the ACA reside during alignment and curing of the ACA; And
ACA containing magnetically alignable particles capable of forming conductivity in interconnections in the z-axis
Including,
The alignment tray and the magnetic tray are made of a non-magnetic material;
The magnet tray and the alignment tray are arranged vertically together in a detachable manner so that the components on the substrate are vertically aligned with the magnets in the magnet tray, and magnetic flux lines are substantially perpendicular to the xy plane defining the substrate. So that the ACA is exposed to a magnetic field;
The substrate can be placed in the alignment tray in only one orientation. 12. The system of claim 11, wherein the magnets are permanent magnets. 12. The system of claim 11, wherein the magnets are rare earth magnets. The method of claim 13, wherein for each magnet in the magnet tray, the magnetic flux lines are substantially parallel to each other and are substantially perpendicular to the xy plane in an area corresponding to the area of the substrate in which the component and ACA are located. system. 12. The system of claim 11, wherein the ACA forms substantially uniform columns, the columns being substantially perpendicular to the x-y plane of the component and the substrate in the presence of the magnets. 12. The system of claim 11, wherein an assembly comprising the magnetic tray, the alignment tray, and the substrate on which components reside can be carried or placed directly into a curing oven. 17. The system of claim 16, wherein the assembly or the magnetic tray serves as a rack that can be slid or transported directly into the oven and does not require any support shelves, additional racks, or other supports. A kit for creating interconnects between a substrate and electronic components attached to the substrate using a magnetically alignable anisotropic conductive adhesive, comprising:
At least one magnetic tray including a non-magnetic tray adapted to hold one or more magnets using an ACA at locations corresponding to a desired placement of an electronic component on a substrate and connection of the component to the substrate;
Enough magnets to complete the magnet tray, each magnet being of a desired size and strength to establish an interconnection between the component and the substrate using the ACA;
At least one alignment tray adapted to receive and hold the substrate and components residing on the substrate during alignment and curing of the ACA to form the interconnect; And
Optionally, an ACA suitable for use with the kit to create at least one interconnect between a component and a substrate using the kit.
Including,
The magnet tray and the alignment tray are configured to be oriented and assembled perpendicular to each other, so that when the magnet tray and the alignment tray are so oriented and assembled, an electronic component disposed on a substrate on the alignment tray is provided with a magnet on the magnet tray. Kits that are vertically aligned. 19. The kit of claim 18, wherein the oriented and assembled magnetic tray and alignment tray can be placed or transported directly into a curing oven. 20. The kit of claim 19, wherein the magnetic tray or the assembled trays function as a rack in the oven.

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