# Patent

## Title
Assembly comprising functional block deposited therein

## Abstract

An electronic assembly. The assembly includes a substrate, a plurality of recessed regions, and a plurality of functional blocks. Each functional block is deposited in one of the recessed regions. A substantial amount of the plurality of functional blocks is recessed below a top surface of the substrate. Substantial amount is defined by any one of less than 10% of said functional blocks protrudes above the top surface of the substrate; less than 1% of the functional blocks protrudes above the top surface of the substrate; more than 90% of the functional blocks are recessed below the top surface of the substrate; or more than 99% of the functional blocks are recessed below the top surface of the substrate.

## Background
RELATED APPLICATION
This application is related to and claims the benefit of U.S. Provisional Patent application Ser. No. 60/626,241 filed Nov. 8, 2004, which is hereby incorporated by reference in its entirety. This application is also related to co-pending U.S. patent application Ser. Nos. 11/159,574 and 11/159,550 filed on the same day with this application, Jun. 22, 2005, which are hereby incorporated by reference in their entireties.


GOVERNMENT RIGHT NOTICE
This invention was made with government support under Contract No. H94003-04-2-0406. The government has certain rights to this invention


FIELD
The present invention relates generally to the field of fabricating electronic devices with small functional elements deposited in a substrate.
BACKGROUND
There are many examples of functional blocks or components that can provide, produce, or detect electromagnetic or electronic signals or other characteristics. The functional blocks are typically objects, microstructures, or microelements with integrated circuits built therein or thereon. These functional blocks have many applications and uses. The functional components can be used as an array of display drivers in a display where many pixels or sub-pixels are formed with an array of electronic elements. For example, an active matrix liquid crystal display includes an array of many pixels or sub-pixels which are fabricated using amorphous silicon or polysilicon circuit elements. Additionally, a billboard display or a signage display such as store displays and airport signs are also among the many electronic devices employing these functional components.
Functional components have also been used to make other electronic devices. One example of such use is that of a radio frequency (RF) identification tag (RFID tag) which contains a functional block or several blocks each having a necessary circuit element. Information is recorded into these blocks, which is then transferred to a base station. Typically, this is accomplished as the RFID tag, in response to a coded RF signal received from the base station, functions to cause the RFID tag to reflect the incident RF carrier back to the base station thereby transferring the information. Such RFID tags are being incorporated into many commercial items for uses such as tracking and authenticating the items.
The functional components may also be incorporated into substrates to make displays such as flat panel displays, liquid crystal displays (LCDs), active matrix LCDs, and passive matrix LCDs. Making LCDs has become increasingly difficult because it is challenging to produce LCDs with high yields. Furthermore, the packaging of driver circuits has become increasingly difficult as the resolution of the LCD increases. The packaged driver elements are also relatively large and occupy valuable space in a product, which results in larger and heavier products.
Demand for functional components has expanded dramatically. Clearly, the functional components have been applied to make many electronic devices, for instance, the making of microprocessors, memories, power transistors, super capacitors, displays, x-ray detector panels, solar cell arrays, memory arrays, long wavelength detector arrays, phased array antennas, RFID tags, chemical sensors, electromagnetic radiation sensors, thermal sensors, pressure sensors, or the like. The growth for the use of functional components, however, has been inhibited by the high cost of assembling the functional components into substrates and fabricating final devices or end products that incorporate the functional components.
Often the assembling of these components requires complex and multiple processes thereby causing the price of the end product to be expensive. Furthermore, the manufacturing of these components is costly under the current method because of inefficient and wasteful uses of the technologies and the materials used to make these products.
Many aspects such as substrates' materials, characteristics, and dimensions, and/or functional blocks' dimensions and characteristics, and the like, impact the efficiency and cost of assembling the functional components into substrates. Accurate dimension and parameter control of these aspects are crucial for efficiency while reducing cost for assembling electronic devices containing functional blocks deposited therein.
SUMMARY
Embodiments of the present invention provide methods that can lead to efficient fabrications of an electronic assembly that incorporates a functional component or block.
One embodiment pertains to an electronic assembly which comprises a substrate having a recessed region. The recessed region having a first width-depth aspect ratio. A functional block is deposited in the recessed region. The functional block has a second width-depth aspect ratio. The first width-depth aspect ratio substantially matches said second width-depth aspect ratio. The first width-depth aspect ratio is equal to or less than 10.5:1. Alternatively, the first width-depth aspect ratio is and equal to or less than 7.5:1.
One embodiment pertains to an assembly, which comprises a substrate, a population of recessed regions, and a population of functional blocks. Each functional block is deposited in one of the recessed regions. A substantial amount of the population of functional blocks is recessed below a top surface of the substrate. The substantial amount is defined by less than 10% of the population of the functional blocks protrude above the top surface of the substrate, or more optimally, less than 1% of the population of the functional blocks protrude above the top surface of the substrate, or alternatively, more than 90% of the population of the functional blocks are recessed below the top surface of the substrate, or more optimally, more than 99% of the population of the functional blocks are recessed below the top surface of the substrate. In one embodiment, the recessed regions all have a first width-depth aspect ratio, the functional blocks all have a second width-depth aspect ratio. The first width-depth aspect ratio substantially matches the second width-depth aspect ratio. The first width-depth aspect ratio is equal to or less than 10.5:1. Alternatively, the first width-depth aspect ratio is and equal to or less than 7.5:1.
One embodiment pertains to a method, which comprises forming a population of recessed regions on a substrate with a vertical hot press, and depositing a population of functional blocks into the population of recessed regions. The method is further defined by a substantial amount of the population of functional blocks that are deposited in the recessed region, with no more than one block per recess, being recessed below a top surface of the substrate. The substantial amount is defined by less than 10% of the population of the functional blocks protrude above the top surface of the substrate, or optimally, less than 1% of the population of the functional blocks protrudes above the top surface of the substrate, or alternatively, more than 90% of the population of the functional blocks are recessed below the top surface of the substrate, or optimally more than 99% of the population of the functional blocks are recessed below the top surface of the substrate. In one embodiment, the method further comprises attaching a mold to a vertical hot press. The mold has feature dimensions used for each of the population of recessed regions. The feature dimensions for each of the population of recessed regions are about 0.5-1.0% larger than a desired corresponding feature of each of the population of recessed regions.
One embodiment pertains to a method which comprises forming a plurality of recessed regions on a substrate and depositing a plurality of functional blocks into the plurality of recessed regions. Each of the functional blocks is deposited in one of the recessed regions with a substantial amount of the plurality of functional blocks being recessed below a top surface of the substrate. Each of the recessed regions has a first width-depth aspect ratio and each of the functional blocks has a second width-depth aspect ratio. The first width-depth aspect ratio substantially matches the second width-depth aspect ratio. The first width-depth aspect ratio is equal to or less than 10.5:1. Alternatively, the first width-depth aspect ratio is and equal to or less than 7.5:1.



BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be understood more fully from the detailed description given below and from the accompanying drawings of various embodiments of the invention, which, however, should not be taken to limit the invention to the specific embodiments, but are for explanation and understanding only. In the drawings:
FIG. 1 illustrates an example of a functional component block;
FIG. 2A illustrates an exemplary embodiment of an electronic assembly with a functional block deposited in a substrate;
FIGS. 2B-2C illustrate exemplary embodiments of a via formed in a dielectric layer that is formed over a functional block;
FIGS. 2D, 2E(a)-2E(b), and 2F illustrate exemplary embodiments of a conductive interconnect coupling to a functional block;
FIG. 2G illustrates an exemplary embodiment of incorporating the assembly formed in FIG. 2A to a second substrate (a device substrate);
FIG. 3 illustrates an exemplary embodiment of an electronic assembly with a functional block deposited in a substrate that is a multi-layered substrate;
FIGS. 4-5 illustrate aspects of a recessed region formed in a substrate;
FIG. 6A illustrates an exemplary embodiment of an electronic assembly with multiple functional blocks deposited in a substrate with a plurality of recessed regions;
FIG. 6B illustrates an exemplary embodiment of an electronic assembly with multiple functional blocks deposited in a substrate with the functional blocks being recessed below a surface of the substrate;
FIGS. 7A-7D illustrate an exemplary embodiment that uses a template to create recessed regions in a substrate;
FIGS. 7E-7F illustrate non-uniform or inconsistent step-changes between frames of substrate;
FIGS. 7G-7H illustrate an exemplary embodiment of the present invention with consistent step-changes between frames of substrate;
FIGS. 7I-7M illustrate an exemplary embodiment that uses a roller with features to create recessed regions in a substrate;
FIG. 8 illustrates an exemplary embodiment of an overall process of making an electronic assembly with functional block in accordance to embodiments of the present invention;
FIG. 9 illustrates another exemplary embodiment of an overall process of making an electronic assembly with functional block in accordance to embodiments of the present invention;
FIGS. 10-11 illustrate a plurality of sheets being joined together to form a long sheet of substrate with recessed regions in accordance with embodiments of the present invention;
FIG. 12 illustrates an exemplary embodiment of an overall process of making an electronic assembly with functional block in accordance to embodiments of the present invention; and
FIGS. 13, 14A-14B and 15 illustrate exemplary methods of making an electronic assembly with functional block in accordance to embodiments of the present invention.



DETAILED DESCRIPTION
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the invention. It will be apparent to one skilled in the art, however, that the invention can be practiced without these specific details. In other instances, structures and devices are shown in block diagram form to avoid obscuring the invention.
Embodiments of the present invention relate to methods for forming holes, openings, or recessed regions in a substrate or web substrate and depositing functional blocks into the recessed regions, forming layers, and/or electrical interconnections to the blocks to form electronic assemblies. On many occasions, the disclosure refers to the substrate with one or more functional blocks deposited therein as a “strap assembly.” Electronic devices that can be formed using embodiments include a display, a smart card, a sensor, an electronic tag, an RFID tag, etc. Some embodiments of the present invention also relate to characteristics and features of the substrates or the substrate materials that the functional blocks are deposited therein. Some embodiments of the present invention also relate to feature dimensions and specifics of the functional blocks with respect to the substrate and the recessed regions.
Embodiments of the invention apply to both flexible and rigid substrates, and to both monolayer and multilayer substrates. By creating recessed regions in a substrate, the substrate is able to receive a functional block or functional blocks that may have a circuit element thereon. In some embodiments, the substrate includes one functional block. In many embodiments, the substrate includes a plurality of such recessed regions for a plurality of such functional blocks. Typically the blocks are contained in a slurry, which is deposited onto the flexible substrate as is typically done in a Fluidic Self-Assembly (FSA) process. Although the blocks may be comprised of single crystal silicon or other like material, which makes the block rigid, the substrate may still be flexible because the size of these blocks (e.g., 650×500 μm or 850×850 μm) is small, or significantly small, in comparison to the flexible substrate (e.g., 3×6 mm or larger). In some embodiments, the flexible substrate forms part of an RFID tag, a merchandise label, a packaging, a pharmaceutical label/seal, a currency (money), or a display backplane, to name a few example applications.
Many devices are made from a combination of a strap substrate and another substrate (or a receiving substrate or a device substrate). Such devices may include an RFID tags, a display, a smart card, a sensor, an electronic tag, or a sensor device. A device with a strap substrate combined to another substrate are described in U.S. Pat. No. 6,606,247, which is hereby incorporated herein by reference. In one example of this combination, the strap substrate is fabricated with one or more recessed receptor sites, and one or more functional or integrated circuit blocks are deposited into the recessed receptor sites, for example, using a Fluidic Self-Assembly (FSA) process. The functional blocks may be deposited by one or more FSA operations, by robotic pick-and-place operations, or by other methods. After a functional block is deposited into the corresponding strap substrate, the strap substrate is then attached to another substrate, which may comprise a set of patterned or printed conductor. The conductor can be an electrical element of a device, for instance, the conductor can be elements or parts of an antenna for an RFID device. More than one functional block may be deposited into a strap substrate depending on application.
A strap assembly is formed when one or more functional blocks are deposited in the strap substrate and other elements (e.g., dielectric layer and electrical interconnection) formed thereon. The overall manufacturing process of a strap assembly impacts the cost of the final device that incorporates the strap assembly. For example, when a strap assembly is formed using a web process, efficiencies of the block deposition, dielectric film formation, material usage, or electrical interconnection fabrication play important roles in the final device cost and performance.
FIG. 1 illustrates exemplary embodiments of an object that is functional component block 1. The functional block 1 can have various shapes and sizes. Each functional block 1 has a top surface 2 upon which a circuit element is situated (not shown). The circuit element on the top surface 2 may be an ordinary integrated circuit (IC) for any particular function. For example, the IC may be designed to drive a pixel of a display. The IC may also be designed to receive power from another circuit, such as an antenna, and perform a particular function or functions for the operation of a passive RFID tag. Alternatively, the IC may be designed to receive power from an energy source (e.g. battery) for the operation of an active RFID tag. The functional block 1 also includes a contact pad 3 (one or more contact pads 3) to allow electrical interconnection to the circuit element on the block 1. The functional block 1 can have a trapezoidal, rectangular, square, cylinder, asymmetrical, or asymmetrical shape. The top of the block 1 is often (but need not be) wider than the bottom of the block 1. Each functional block 1 may be created from a host substrate and separated from the host substrate. Methods of making a functional block 1 are known in the art and for instance, can be found U.S. Pat. Nos. 5,783,856; 5,824,186; 5,904,545; 5,545,291; and 6,291,896, which are hereby incorporated by reference in their entireties.
FIG. 2A illustrates a cross-sectional view of an exemplary embodiment of an electronic assembly (or a strap assembly) 200. The assembly 200 can be part of or made to incorporate into a display device, a RFID tag, a merchandise label (a CD label), a pharmaceutical label or bottle, etc. The assembly 200 can be attached to another substrate (e.g., a device substrate) that may have patterned, printed, or formed thereon a conductor or conductors. A functional block 202 is deposited in recessed region 204 of a substrate 206 to form the assembly 200. The functional block 202 can be the functional block 1 previously discussed. Methods of making a functional block are known in the art. In one embodiment, the functional block 202 is a NanoBlockTM made by Alien Technology. Once deposited, the functional block 202 is recessed below a surface 208 of the substrate 206. In one embodiment, the functional block 202 is recessed sufficiently below the surface 208 to provide sufficient space for electrical connection to the functional block 202. In one embodiment, the functional block 202 is deposited into the recessed region 204 using a Fluidic Self-Assembly (FSA) process. The surface 208 of the substrate 206 is the native surface of the substrate 206 before any deposition of any other materials on top of the surface 208. The substrate 206 may be a flexible substrate made out of plastic, fabric, metal, or some other suitable materials. In one embodiment, the substrate 206 is flexible. In one embodiment, the assembly 200 is flexible.
Also shown in FIG. 2A, a dielectric layer 210 is formed over the surface 208 and over the functional block 202. The dielectric layer 210 in many instances, also functions as a planarization layer as well as a layer that traps or keeps the functional block 202 in the recessed region 204. Vias 212 are also formed into the dielectric layer 210 to expose portions of the functional block 202. Typically, each of the exposed portions of the functional block 202 comprises a contact pad 216 that enables electrical interconnection to the functional block 202. In one embodiment, the functional block 202 includes two contact pads 216 placed on opposite sides and/or diagonal to each other. In such embodiments, the dielectric layer 210 has two vias 212, one for each contact pad 216. Each via 212 exposes some or all of the top area 216-A of the corresponding contact pad 216 (FIGS. 2B-2C). In one embodiment, as shown in FIG. 2B each via 212 has a diameter that is smaller than the top area 216-A of the corresponding contact pad 216. In some embodiment, the via 212 has a cone-like shape where the via 212 has a top diameter and a bottom diameter. The bottom diameter is smaller than the top diameter. In one embodiment, the bottom diameter is at least 20% smaller than the contact pad 216. Optimally, the diameter of the via 212 at the bottom should be no more than 80% of the width of the contact pad 216, which may be defined by the area 216A. Most optimally, it should be no more than 60% of the width of the contact pad 216, which may be defined by the area 216A. In one embodiment, the via 212 has a non-symmetrical cone-like shape in which one side of the via 212 has a flatter or gentler slope than the other side (FIG. 2C). As shown in FIG. 2C, the via 212 has two sides, 212-A and 212-B, in which the side 212-B has a more “gentle” or flatter slope than the side 212-A. In one embodiment, a small protrusion 212-C is formed on the side 212-B of the via 212. The configuration of the via 212 in accordance to the present embodiment helps the conductive material to more easily fill the via 212.
In one embodiment, the dielectric film 210 is deposited using a roll-to-roll process over the substrate 206 that has the functional block 202 deposited therein. The dielectric film 210 may be deposited using methods such as lamination of a polymer film or coating of a liquid layer over the substrate 206 and subsequent curing to form the dielectric film 210. In one embodiment, the dielectric film 210 is deposited by a wet coating process, such as comma coating, or by a direct writing process, and subsequently dried or cured. The dielectric film 210 may be necessary in embodiments where the assembly 200 is used for devices such as RFID tag since the dielectric film 210 provides good RF performance for the RFID tag. The dielectric film 210 contains at least one opening formed through the dielectric film for the via 212. Each via 212 enables the conductive interconnect 214 formed on the top of and into the dielectric film 210 to make electrical connection with a contact pad 216 on the functional block 202.
Each conductive interconnect 214 can be one conductor or two conductors joined together. The conductive interconnect 214 can be formed in a one-step process or a two-step process. When the conductive interconnect 21 is made of two (2) conductors, one conductor is referred to as a “via conductor” (214-V) since it fills the via 212. The other conductor is referred to a “pad conductor” (214-P) which sits on a portion of the dielectric layer 210 and connects or joins the via conductor 214-V.
Each via 212 in the dielectric film 210 is positioned over a contact pad 216, such that the via 212 enables interconnection from the corresponding contact pad 216 on the functional block 202 to the interconnect 214. In one embodiment, each via 212 is formed such that no dielectric material is present in the via 212.
In many embodiments, there are two (2) (or more) vias 212 created over each functional block 202. The number of vias 212 can be increased or decreased depending on the product. The number of vias 212 also depends on how many contact pads 216 are present in the functional block 202 or depending on how many electrical connection is needed. For example, many more dielectric vias may be needed for embodiments where the assembly 200 is incorporated into display driver or sensor applications. In one embodiment, there are two contact pads 216 on the functional block 202 and the contact pads are situated diagonally to each other. In such embodiment, the dielectric film 210 has two vias 212 which are also situated diagonally to each other over the corresponding contact pads 216.
In one embodiment, the dielectric film 210 has a thickness ranging from about 5 μm to about 60 μm. In another embodiment, the thickness of the dielectric film 210 is approximately 38 μm. The dielectric can be either as a wet film that is dried or cured, or as a dry film that is laminated onto the substrate 206.
In one embodiment, the dielectric film 210 has an adhesive functionality to the side that is applied to the substrate 206. The adhesive functionality could be an inherent property of the dielectric material or its application process, or it could be due to an adhesive film that is applied to the side of the dielectric film 210 that comes in contact with the substrate 206. In embodiments where an adhesive film is used to provide the adhesive to the dielectric film 210, the adhesive film is non-conductive and can be processed to achieve the desired structure for the via 212. For example, the adhesive film must be photo imagable or laser drillable to allow the via 212 to be formed. A laser drillable adhesive film could be fabricated by using an adhesive that inherently absorbs UV light, or else by using an adhesive formulation that consists of a UV-absorbing species. If an adhesive film is used on the dielectric film 210, all of the dimensions listed for the dielectric film 210, including film thickness and via diameter, applies to the dielectric and adhesive film combined together.
In one embodiment, the dielectric film 210 has a coefficient of thermal expansion (CTE) that is closely matched to that of the substrate 206. Preferably, the CTE is within ±20 ppm/° C. of the CTE of the base material of the substrate 206, which is typically 50-70 ppm/° C., but can vary depending on the substrate. The proximity of the dielectric film CTE to the substrate film CTE is more important than the absolute value of the substrate film CTE. Suitable dielectric materials include, but are not limited to polyimide, polyetherimide, liquid crystal polymer, and polyethylenenaphthalate.
In one embodiment, the vias 212 in the dielectric film 210 are formed over corner areas of the functional block 202. In one embodiment, the vias 212 are only formed over the corners of the functional blocks with the contact pads 216. Additionally, the dielectric film 210 may also be formed only in discrete or selected positions on or around the functional block 202 and around the area of the substrate 206 that has the functional block 202 deposited therein. When the dielectric film 210 is discretely or selectively formed, the vias 212 may not be necessary since the dielectric material may be selected to not form over the contact pads 216 to leave the contact pads 216 exposed. A method that can be used for selectively or discretely form the dielectric film 210 includes direct write, such as ink-jet, and laser assisted deposition, etc. Such method enables the deposition of the dielectric film 210 anywhere the material is needed. Additionally, such selective deposition of the dielectric film 210 enables customizing deposition of the dielectric film for uses such as bridging or covering the gap from the functional block 202 to the substrate surface 208, and/or to protect sensitive areas on the functional block 202. Such selective deposition of the dielectric film 210 minimizes the use of the dielectric material where it is not needed. Other methods that can be used for selectively or discretely form the dielectric film 210 include patterning, etching, and photolithography.
One advantage of a structure that incorporates a via or vias and a dielectric layer is that the dielectric layer is disposed between the functional block which can be an integrated circuit (IC) for a device and the conductive interconnect or conductive traces which could be used to connect the functional block to an external electronic element such as an antenna. The via through the dielectric material provides a direct electrical connection to the IC, but there is still a capacitive coupling between other parts of the functional blocks and the external electronic element. It is disadvantageous to have such capacitive coupling between the IC and the conductive traces, and this capacitive coupling is increased due to proximity of the conductive traces to the IC. Placing the dielectric layer between the functional block and the external electronic element provides some vertical distance between them. Minimizing the size of the interconnection pad, and increasing the vertical distance between the traces and IC, minimizes this capacitive coupling. Additionally, the use of low dielectric constant materials as the dielectric layer will also minimize this capacitive coupling. Examples of low-dielectric constant materials include porous materials, fluorinated materials, and silicon-rich materials. It is to be appreciated that the dielectric layer is not necessary in many instances. For instances, the functional blocks may be configured so that a dielectric film is not necessary. In embodiments where no dielectric layer is used, it may be advantageous for the functional block to have some adhesion to the underlying substrate. Also, in embodiments where no dielectric layer is used, it may not be necessary to form vias as described below.
In one embodiment, each conductive interconnect 214 formed on top of and into (in a via created in the dielectric layer 208) the dielectric layer 208 fills a particular vias 212 so as to establish electrical interconnection to the functional block 202. In the present embodiment, each conductive interconnect 214 constitutes both a via conductor 214-V as well as a pad conductor 214-P. When each of the conductive interconnects 214 fills via 212, the conductive material covers all of the exposed area of the contact pad 216 that is exposed by the via 212. In one embodiment, the conductive interconnect 214 constitutes a conductive trace of an antenna element or acts as an interconnect for an antenna element. The conductive interconnect 214 can also interconnect the functional block 202 to an external electrical element or elements (e.g., antennas or electrodes). The conductive interconnect 214 can also be an electrical or conductive lead from the external electrical element.
In one embodiment, the conductive interconnect 214 is formed using a roll-to-roll process. For example, materials used to form the interconnect 214 is deposited onto and into the dielectric layer 208 as the substrate 208 is processed on a web line. Material used to make the conductive interconnect 214 may be selected such that it can be cured, for example, by heat or by electromagnetic or ultraviolet radiation, and can be used in the roll-to-roll process. For example, the interconnect 214 material is cured as the substrate 206 is processed on a web line.
In one embodiment the conductive interconnect 214 is made of a conductive composite of conductive particles in a non-conductive matrix, such as silver ink. In another embodiment, the conductive interconnect 214 is made of metal or metals that are evaporated onto the substrate 206 or onto the dielectric layer 210, over the corresponding via 212, and subsequently patterned. The conductive interconnect 214 can also be comprised of an organic conductor, or composites of carbon nanotubes or inorganic nanowires dispersed in a binder. In one embodiment the conductive interconnect 214 is made of a conductive composite, such as silver ink or silver-filled epoxy that completely filled by the corresponding vias 212. In one embodiment, the conductive interconnect 214 is made of one or more of the following: conductive particles dispersed in a nonconductive or an organometallic matrix (e.g., silver ink), sputtered or evaporated metal, conductive carbon composite, carbon nanotubes, inorganic nanowires dispersed in a nonconductive matrix, and any of these materials combined with metallic nanoparticles. In one embodiment, the conductive interconnect 214 comprises a nonconductive matrix that consists of a thermoplastic polymer, a thermoset polymer, or a B-staged thermoset polymer. In one embodiment, the elastic modulus of a conductive composite that is used to form the conductive interconnect 214 is between 120,000 psi and 60,000 psi. The resistivity of the conductive interconnect 214 is less than 76 mΩ/square/mil, more optimally, less than 60 mΩ/square/mil, even more optimally less than 42 mΩ/square/mil, and most optimally less than 25 mΩ/square/mil.
Additionally, the conductive interconnect 214 is made of a material that is able to maintain good electrical contact to the top-most conductive feature or features (e.g., the contact pad 216) on the functional block 202, such that the combination of the substrate 206, the functional block 202, the dielectric layer 210, the contact pad 216, and the conductive interconnect 214 is able to maintain sufficient electrical contact throughout, with less than a 10% variation in total resistance. In one embodiment, the combination of the substrate 206, the functional block 202, the dielectric layer 210, the contact pad 216, and the conductive interconnect 214 is able to maintain sufficient electrical contact throughout, with less than a 10% variation in total resistance, when the assembly 200 is subjected to thermal cycles for 100 times from −40° C. to 85° C., and bent over a 1-inch-diameter mandrel for 80-100 times. Each conductive interconnect 214 can partially or completely cover the corresponding via 212 for the conductive material in the via 212 to make electrical contact to the functional block 202 or the corresponding contact pad 216 on the functional block 202. Additionally, the conductive interconnects 214 also have a good adhesion to the dielectric film 210, such that the interconnects can survive flexing over a 1-inch mandrel as previously mentioned.
In one embodiment, the conductive interconnect 214 is coupled to another conductive trace (not shown) that may be formed on the substrate 206. Such conductive trace can be an antenna trace, for example, when the assembly 200 is to be incorporated into an RFID tag. Alternatively, the conductive interconnect 214 also forms the conductive trace for the final device itself. For example, the conductive interconnect 214 can also be part of an antenna element for an RFID tag. The conductive interconnect 214 and the conductive trace could be combined as one material applied in one process, or as two materials applied in two sequential steps.
In one embodiment, the interconnect 214 constitutes a via conductor 214-V and a pad conductor 214-P connecting to a particular contact pad 216. The via conductor 214-V contacts the conductive pad 216 on the functional block 202 at the bottom of the via 212. It is preferable that the via conductor 214-V covers all of the contact pad 216 that is exposed by the via 212.
In one embodiment, the top diameter or the top area of the via conductor 214-V is larger than the top diameter of the corresponding via 212. In one embodiment, the top diameter or the top area of the via conductor 214-V is about 1-3 times larger than the top diameter of the via 212. In another embodiment, top diameter or the top area of the via conductor 214-V is 1-2 times larger than the top diameter of the via 212.
The pad conductor 214-P, in one embodiment, provides a large or larger conductive area for fast electrical attachment of the assembly 200 to a conductor on another electrical functional element, such as a RFID antenna, a display driver strip, or a sensor assembly. In one embodiment, the pad conductor 214-P is at least (1 mm)×(1 mm) large. Since this interconnection area is larger than the connection or contact pad 216 on the functional block 202, lower-cost, lower-precision equipment can be used to produce electrical contact between the assembly 200 and other functional elements such as antennas. The pad conductor 214-P may be made of the same material or different material as the via conductor 214-V. The pad conductor 214-P must make electrical contact with any necessary conductive material in the via 212 (e.g., the via conductor 214-V) as well as the corresponding contact pad 216 that may be provided on the functional block 202.
The conductive interconnect 214 may have several layouts. Exemplary layouts are shown in FIGS. 2D-2F, below. The layouts in FIGS. 2D-2F illustrate exemplary configurations for the pad conductor 214-P of the conductive interconnects 214. It is to be noted that other configurations are also feasible.
Typically, the assembly 200 includes more than one interconnections 214 and more than one pad conductor 214-P. For instance, when the functional block 202 has two contact pads 216 so that multiple connections are needed. In FIG. 2D, a “bow-tie” configuration 214-A is provided. In this configuration, two pad conductors 214-P form a bow tie-like configuration. It is to be anticipated that besides the bow-tie configuration for the pad conductor, other configurations are possible. Any configuration that covers the desired contact areas can be deployed. For example, the shape of the pad conductors could be round, triangular, or asymmetric. The position of the pad conductors can be collinear with the functional block (as in the bowtie), but the pad conductors could also be placed at some other angle with respect to the functional block (such as the patch-block-patch structure forming a 90-degree angle). Additionally, placement of the pad conductors, their size and shape, is determined by considering how best to pack the strap assemblies on a web, as well as the precision required for placement with other electrical devices such as antenna. For example, in larger antenna structures it could be desirable to form even larger patches, which further reduces the tolerances required for assembly. The configuration 214-A includes two pad conductors 214-P, each of which having two fingers 244 coming out of each pad conductor. The fingers 244 are able to make contact with each of the contact pad 216 at any of the 4 corners of the functional block 202. Each finger 244 would make contact to a contact pad 216 that is closest to the corresponding finger 244. It is preferred to have a limited amount of conductive interconnect 214 over the functional block 202 such that the amount of stray capacitance is limited. Thus, only a small section of each finger 244 overlaps the functional block 202 or a contact pad 216 provided on the block 202. In one embodiment, the finger 244 is less than or equal to the top diameter of the corresponding contact pad 216 that the finger 244 connects to. In one embodiment, the finger 244 covers a portion of the via conductor that connects to the contact pad 216. In one embodiment, the finger 244 covers all of the via conductor that connects to the contact pad 216. The bow-tie configuration 214-A enables the conductive interconnect 214 to make contact to the functional block 202 where the contact pads 216 is placed on any of the four corners of the functional block 202. It may be that the functional block 202 has one contact pad 216. Thus, not all of the fingers 244 would contact a contact pad 216. The functional block 202 thus can also be deposited into a receptor 204 in a manner where the contact pads 216 can be oriented at any corner and still able to allow contact from the fingers 244 to the contacts pads 216.
In FIG. 2E(a)-2E(b), another “bow-tie” configuration 214-B, which does not have the fingers 244 shown in the bow-tie configuration 214-A is provided. Instead, in the bow-tie configuration 214-B, sides 246 are provided on the pad conductors 214-P where each of the sides 246 runs across almost the length of each side of the functional block 202. In this configuration, two pad conductors 214-P also form a bow tie-like configuration over parts of the functional block 202. In the present embodiment, each of the sides 246 is placed in contact with a contact pad 216 on the functional block 202. The central pad 216 can be at a corner location as shown in FIG. 2E(a) or at a center location as shown in FIG. 2E(b).
FIG. 2F illustrates an exemplary embodiment of a configuration of the conductive interconnect 214 or the pad conductor 214-P with a non-bow-tie configuration 214-C. In the present embodiment, the functional block 202 may have contact pads 216 placed diagonally to each other. The configuration 214-C is similar to the configurations 214-A and 214-B above except that only one arm is necessary on each pad. The configuration 214-C is configured with two pad conductors 214-P each having an arm or extension 248 to make connection to one of the contact pads 216. The arm 238 allows the conductive interconnect 214 to contact the functional block 202 with minimal conductive material over the functional block 202. Other configurations or shape for the extension 248 are possible. The configuration 214-C is especially useful when the functional block does not have rotational symmetry that is greater than 2-fold.
In FIGS. 2D-2F, the contact pads 216 are shown to contact the fingers 244 or the sides 246 of the pad conductor. As previously mentioned, the dielectric layer 210 may be formed over the block 202 and the vias 212 are created in the dielectric layer 210 so that the contact pads 216 are exposed. The vias are filled with conductive interconnects 214 or via conductors 214-V as previously mentioned. As previously mentioned, the vias could also be filled by the same material and at the same time as the sides 246 are form. The fingers or sides from the pad conductors 214-P cover at least a portion of the corresponding via conductors 214-V to establish interconnection to the contact pads 216. For the sake of illustrating the pad conductor layouts, the vias 212 and the via conductors 214-V are not shown in FIGS. 2D-2F.
In one embodiment, each pad conductor 214-P has a resistivity that is less than 25 mΩ/square/mil, optimally less than 18 mΩ/square/mil, and most optimally less than 12 mΩ/square/mil.
In one embodiment, each part of the pad conductor part 214-P that is over the via conductor should be no wider than 2 times the smallest diameter of the corresponding via conductor 214-V, optimally no wider than 1.5 times the diameter of the via conductor 214-V, and more optimally, the same width as the widest diameter of the via conductor 214-V.
The assembly 200 shown in FIG. 2A can be referred to as a strap assembly. In one embodiment, the strap assembly 200 is further coupled or attached to another device for form a final device (for example, to form an RFID tag). FIG. 2G illustrates a cross-sectional view of the strap assembly 200 being attached to a second substrate or a device substrate 201. The substrate 201 may include other active elements and/or electrical components and in one embodiment, includes a conductor pattern 203 formed thereon. In one embodiment, the conductor pattern 203 is part of an antenna element that can be used for an RFID device. In one embodiment, the substrate 206 is “flipped” over such that the surface 208 is facing the second substrate 201 and the conductor pattern 203. The substrate 206 is attached to the second substrate 201 in a way that the conductor pattern 203 is coupled to the interconnects 214. Conductive adhesives may be used to facilitate the attachment of the strap assembly 200 to the substrate 206. Other sealing materials can also be added.
In one embodiment, the substrate 206 is a monolayer plastic film such as the substrate 206 shown in FIG. 2A. A plastic monolayer base film can be a thermoset or an amorphous or semicrystalline thermoplastic plastic film. In one embodiment, the substrate 206 is a thermoplastic base film and has a glass transition temperature (Tg) of at least about 100° C., more optimally at least about 125° C., and even more optimally at least about 145° C.-150° C. The thermoset plastic film can be selected from UV-curable, moisture-curable, and heat-curable thermoset plastic films. Example of suitable materials that can be used for the substrate 206 include, but are not limited to, polyethylene, polystyrene, polypropylene, polynorbornene, polycarbonate, liquid crystal polymer, polysulfone, polyetherimide, polyamide, polyethyleneterephthalate, and polyethylenenaphthalate, and derivatives thereof. Additional layers may be added to make the substrate 206 opaque; that is, to shield the integrated circuit from any light that may strike the strap assembly.
In alternative embodiments, the substrate 206 comprises multiple layers for example, layers 206A-206D, with the recessed regions 204 formed in one of the layers, e.g., the top layer 206A and with the additional layers used to provide one or more of dimensional stability, mechanical strength, dielectric properties, desired thickness, functionalities, etc. . . . (FIG. 3).
The substrate 206 is made of a material that minimizes positional distortion of the recessed region 204 after the substrate 206 is subjected to a first thermal excursion for about 30 minutes at about 125° C. Prior to assembling the functional block 202 into the recessed region 204, the substrate 206 is subjected to at least one thermal excursion cycle for about 30 minutes at about 125° C. During this thermal excursion cycle, the recessed region 204 that is formed into the substrate 206 may be distorted positionally. The position of the recessed region 204 on the substrate 206 may move or be distorted slightly due to the heat or change of material characterization due to heat. The substrate 206 must be made of a material that will cause only about 30-500 μm, more optimally, 30-300 μm, positional distortion to the location of the recessed region 204 that is formed on the substrate 206. Positional distortion refers to the location of the recessed region 204 being moved positionally from the originally created position on the substrate 206. In one embodiment, the substrate has a length of about 200 mm, along which the distortion is measured. Thus, the substrate 206 is made of a material that when subjected to a first thermal excursion causes the recessed region to be move by only about 30-500 μm, or 30-300 μm. In another embodiment, the substrate could have a length that is 300 mm or 500 mm long, and the allowable distortion along such a length would scale linearly with the distortion allowed along a shorter length.
In one embodiment, when the substrate 206 is subjected to a process that forms the recessed region 204, areas around the area where the recessed region 204 is to be formed is maintained at a temperature between about 50° C. and the glass transition temperature of the substrate material. Such temperature control minimizes distortion to the substrate 206 as the recessed region 204 is being formed.
The recessed region 204 is at least as large as the functional block 202 that fills the recessed region 204. More optimally, the recessed region 204 is slightly larger (e.g., 0-10 μm or 1-10 μm) than the functional block 202 in width, depth, and length, and has a sloping sidewall similar to that of the shaped functional block 202. In general, the recessed region matches the shape of the functional block; if the functional block 202 is square, the recessed region 204 is also square, and if the functional block 202 is rectangular, the recessed region 204 is also rectangular.
In one embodiment, the substrate 206 is substantially flat, especially in or near the recessed region 204. Substantially flat is characterized by surfaces of the substrate having no protrusion or no protrusion greater than 5 μm. In other words, if there are any protrusions at all, the protrusion is not greater than 5 μm, thus giving the substrate 206 a substantially flat characteristic. FIG. 4 illustrates an exemplary embodiment of the substrate 206 with a top surface 208 that is substantially flat. The substrate 206 only needs to have its top surface 208 (or alternatively, the top surface of the top layer of the substrate 206 when the substrate includes multiple layers) being substantially flat. As shown in FIG. 4, the sides of the recessed region 204 are substantially flat, as well. Thus, top sides 204-T, bottom side 204-B, and sidewalls 204-W of the recessed region 204 are substantially flat with no protrusion. FIG. 5 illustrates an exemplary embodiment of the substrate 206 with some minor protrusions 220 along a surface of the substrate 206. Nevertheless, the protrusions 220 are so minor that the substrate 206 still has the substantially flat characteristic and that the recessed region 204 has sides that are substantially flat.
The recessed region 204 has a width-depth aspect ratio that is configured to substantially match a width-depth aspect ratio of the functional block 202. In one embodiment, the recessed region 204 has a width-depth aspect ratio that is less than 14:1, optimally, less than 10.5:1, and even more optimally, less than 7.5:1. The functional block 202 thus has a similar width-depth aspect ratio.
The substrate 206 is also selected so that the substrate has a good thermal stability to withstand standard processing. The material of the substrate 206 is such that the substrate 206 allows the recessed region 204 to maintain the same positional accuracy requirements previously mentioned. The substrate 206 is made of a material that is able to allow the recessed region 204 to maintain its positional accuracy after going through a 125° C.-150° C. thermal excursion.
In many embodiments, the assembly 200 is cut, sliced, separated, or singulated from a plurality of web-assembled assemblies as will be described below. Thus, a plurality of assemblies 200 can be formed in one short time frame. A roll-to-roll process can be used. A web substrate is provided. The web substrate may be a continuous sheet of web material which when coiled, is a roll form. A plurality of recessed regions 204 are formed into the web material to form the web substrate. A plurality of functional blocks 202 are deposited into the recessed regions 204 on the web substrate (e.g., using an FSA process) to form a plurality of the assemblies 200 shown in FIG. 2A. Areas or strips of the web substrate can later be sliced, singulated, cut, or otherwise separated to produce individual assemblies 200. In one embodiment, a web sheet having a plurality of assemblies 200 is attached to another web substrate similarly to previously described in FIG. 2G. Individual devices can then be formed by slicing or singulating after the substrates are adhered to one another as illustrated in FIG. 2G.
FIGS. 6A-6B illustrate an assembly 400 that includes several assemblies formed similarly to the assembly 200. The assembly 400 is similar to the assembly 200 above except when multiple assemblies are formed on one piece of substrate material. In FIGS. 6A-6B, a substrate 406 includes a plurality or a population of recessed regions 404 formed therein. Each recessed region 404 includes a functional block 402 deposited therein. The assembly 400 is also similar to the assembly 200 shown above except that there are more of the functional blocks deposited in the substrate. Singulating areas of the substrate 406 after the functional blocks 402 have been deposited and other elements formed thereon can produce a plurality of assemblies 200 shown above. The substrate 406 can be a web substrate, a frame of a web substrate, a section of a web substrate, or a sheet substrate. In some embodiments, all of the available recessed regions 404 in the substrate 406 are filled with functional blocks 402. In some embodiments, 90-100% of the available recessed regions 404 in the substrate 406 are filled with functional blocks 402.
The recessed region 404 has a width-depth aspect ratio that is configured to substantially match a width-depth aspect ratio of the functional block 402. In one embodiment, the population of the recessed regions 404 has an average width-depth aspect ratio that substantially matches the average width-depth aspect ratio of the functional blocks 402 or in some case, the width-depth aspect ratio of each of the functional blocks 402. The average width-depth aspect ratio of the population of the recessed region is less than 14:1, optimally, less than 10.5:1, and even more optimally, less than 7.5:1. The functional blocks 402 thus has a similar width-depth aspect ratio to the recessed regions' width-depth aspect ratio.
In terms of recessed regions' depth, it is important to take into account the entire population of the depths 404-R of the recessed regions 404 and the thicknesses 402-D of the functional blocks 402. The thickness 402-D of each of the functional blocks 402 should account for any contact pads on top of the functional block 402. In one embodiment, after all the functional blocks 402 are deposited into their corresponding recessed regions 402, a substantial amount of the plurality of functional blocks 402 are recessed below a top surface 406-T of the substrate 406. In one embodiment, there is a gap 408 between the top surface 402-T of the functional block 402 and the top surface 406-T of the substrate 406. In one embodiment, the gap 408 is between about 0-10 μm. In one embodiment, the substantial amount of the functional blocks 402 being recessed below the surface of the substrate 406 is defined by (1) less than 10% of the plurality of the functional blocks protrude above the top surface 406-T of the substrate 406; (2) less than 1% of the plurality of the functional blocks 402 protrude above the top surface 406-T of the substrate 406; (3) more than 90% of the plurality of the functional blocks 402 are recessed below the top surface 406-T of the substrate 406; or (4) more than 99% of the plurality of the functional blocks 402 are recessed below the top surface 406-T of the substrate 406.
The populations of the depths 404-R of the recessed regions 404 and the thicknesses 402-D of the functional block thickness can be represented by distribution with an average depth or thickness (μr or μN, respectively) and a standard deviation (σr or σN, respectively). The probability that a functional block 402 protrudes up from a recessed region 404 can be determined by comparing the difference (Δ) in averages to the combined standard deviation, σc, where

Δ=μr−μN 

and

σc=√{square root over (σr2+σN2)}.

It is desirable to have σc<Δ. More preferably, using the equations above and applying Normal statistics, it is preferable to have σc and Δ such that less than 10%, or more preferably less than 1%, of the functional blocks 402 protrude above the top surface 406-T of the recessed regions 404.
In one embodiment, the assembly 400 is characterized in that the locations of the recessed regions 405 on the substrate 406 have a good positional accuracy. In one embodiment, across a 158 mm-wide area of the substrate 406, the positional accuracy of each recessed region 404 is within 100 μm at 3σ, in another embodiment, within 50 μm at 3σ, and in another embodiment, within 30 μm at 3σ. These positional accuracy numbers also scale linearly with the width of the substrate 406. For example, when the substrate 406 has a width of about 316 mm the positional accuracy of the recessed regions 404 is within 200 μm at 3σ. Similar to the assembly 200, the assembly 400 includes a dielectric film formed over the functional blocks 402, vias formed in the dielectric film to expose contact pads on the functional blocks 402, and conductive interconnections to establish electrical connections to the functional blocks 402.
The substrate 206 or 406 with recessed regions previously described can be processed using various exemplary methods and apparatuses of the present invention to form the recessed regions.
One embodiment in accordance with the invention includes a substrate in which a roller having protruding features is moved across the substrate and/or pressed down on the substrate. The roller creates holes or recessed regions in the substrate. Another embodiment includes or a substrate that passes under a roller having protruding features and the substrate contacts the protruding structures from the roller. In one embodiment, a template in which structures protrude from the template is used to create recessed regions in a substrate. The template is pressed against the substrate to create recessed regions or holes in the substrate. Another embodiment of the invention relates to creating recessed regions or holes in a web material using either a roller or a template. Another embodiment of the invention relates to creating recessed regions or holes in a web material using either a roller or a template in which heat is also applied to the polymer film to enable the recessed region formation process. In one embodiment, a device with features such as embossing features configured to create recessed regions is used. FIG. 7A shows a template 51 with protruding structures 52. The protruding structures 52 may vary in shapes and sizes depending upon the object that is to be placed into a substrate or web material that is used to create the substrate 406 or 206 previously described. The length of the protruding structure 52 may range from 500 angstroms to 85 microns or larger in some cases. Similarly, the diameter or other dimension (e.g., width) of a protruding structures 52 may range from 100 angstroms to 70 microns to 900 microns or larger in some cases.
In the embodiment where the template 51 is an embossing mold, the protruding structures 52 have feature dimensions and/or pitch that are 0.5-1% larger than the desired dimensions of the corresponding recessed regions to be formed on the substrate. In the present embodiment, the substrate will have the recessed regions formed with a pitch that has substantially similar pitch to the pitch of the recessed regions. The precise dimensions of the final product can thus be controlled. This is necessary so that sufficient alignment occurs through the assembling or fabrication process of the particular apparatus.
In one embodiment, the protruding structure 52 has a width-depth aspect ratio that is less than 10.5:1 or more optimally, less than 7.5:1. Additionally, the protruding structures 52 also have the shape that is the shape of the corresponding functional blocks to be deposited in the recessed regions.
The template 51 is comprised of sturdy materials (e.g., steel, polymers, etc.). In one embodiment, the template is an electroform stamper copy made from an electroform mother copy, which is made from a master mold that is made by either etching a silicon wafer or diamond turning machining a metal plate or roller. In another embodiment, the template is an electroform stamper copy made from a master mold negative that is made by etching a silicon wafer. In another embodiment, the template is an electroform stamper copy made by coupling (e.g., welding or attaching) together smaller electroform stamper copies to make a linear array (for example, x by 1) of stampers, where x>1. In another embodiment, the template is an electroform stamper copy made by welding together smaller electroform stamper copies to make an array (for example, x by y) of stampers, where both x and y are greater than 1.
FIG. 7B shows the template 51 with the protruding structures 52 facing one side of a substrate 50. The substrate 50 can be the substrate 406 or 206 previously mentioned. FIG. 7C shows the template 51 contacting the substrate 50 and the protruding structures 52 from the template 51 pierce or press into the substrate 50. These protruding structures 52 may be a variety of shapes depending on the shapes of objects to be deposited onto the substrate 50. Heat, electromagnetic radiation, or UV light may be applied at any point in this process to assist in the pattern transfer. FIG. 7D shows that when the template 51 is separated from the substrate 50, recessed regions or holes 53 are created in the substrate 50. The recessed regions 53 can be the recessed regions 404 or 204 previously mentioned.
The template 51 can be coupled to a vertical hot press and used to create the recessed regions on the substrate 50. The vertical hot press can be configured to move up or down to cause the template 51 to contact the substrate 50 in the manner described above so that the protruding structures 52 can create the recessed regions 53 into the substrate 50. The template 51 can also be configured to be used in a step-and-repeat process to make the substrate 50 which can be a sheet or a roll of material.
In one embodiment, the substrate 50 is a web substrate that once coiled, has a roll form. When formed from a step-and repeat process, one area or one frame of the substrate 50 is formed at a time by the template 51. Each individual area of the substrate is referred to as a frame. For optimal process conditions, it is important that the web substrate not have unpredictable or uncontrolled ridges, channels, indentations, or step-changes between individual frames of the web substrate. The ridges, channels, indentations, or step-changes between individual frames of the web substrate may cause interruption, disruption, or unpredictable changes in the movement in the flow of the slurry that carries the functional blocks to be deposited into the recessed regions 53 as is used in an FSA process. In one embodiment, a “frame” is approximately 6-inches-long in the material direction of the web substrate, and in other embodiments, a frame can be of any length, ranging from as small as one inch to arbitrarily long, such as 4-feet-long or 8-feet-long or longer.
Various embossing techniques use a repeating process in which an embossing tool provided with a template such as the template 51 is pressed against the web substrate at elevated temperature to emboss the recessed regions into the web substrate. Next, the embossing tool is separated from the web substrate and the web substrate is indexed forward one frame-length for the next frame/area. This entire process is repeated for as many frames as necessary to complete the web substrate of a particular length. Such process, and other embossing processes, can leave an uncontrolled step-change between the frames of the web substrate. This step-change can typically be about 10-50 μm tall or taller, 0.5-2 mm wide, and may not be continuous in the cross-direction of the web. FIG. 7E illustrates a cross-sectional view of an example of step-changes created between frames of a web substrate 70. In this figure, the web substrate 70 is processed using a step-and-repeat process in which step-changes 72 are formed between each two frames 74. In many instances, the step-changes 72 are not uniform or continuous in the same direction from frame to frame as shown in FIG. 7E. Similarly, as shown in FIG. 7F, step-changes can include channels or indentations 76 that are formed between frames 74. These types of step-changes should be avoided in the web substrate. These step-changes 72 or 76 unpredictably or uncontrollably interrupt the flow of the functional blocks during the FSA process, and therefore are detrimental to the process.
Many techniques used to form the recessed region in the web substrate can cause similar step-changes. Thus, the types of step-changes mentioned above can be formed in substrates that are processed otherwise and not necessarily results of step-and-repeat processes. For instance, the step-changes may be caused by a continuous belt that may be present in some processing. A roller used to form the recessed regions in the web substrate could have features that may cause similar step-changes in the web substrate. Uncontrolled step-changes are thus not desired for a web substrate whether the substrate is processed by a step-and-repeat process or by a continuous process.
A step-change between frames, however, may be acceptable in the web substrate if the step change is always in the same direction or in a controlled direction. That way, the FSA process can be controlled or monitored accordingly to a predictable presence of a step-change that is always in the same direction. In one embodiment, a step-change is created into the web substrate such that when examining the space between two frames on the web substrate, there is a step going from one frame to the next, and that the step is always higher on the left side, or is always higher on the right side, or always in the same direction. For instance, as illustrated in FIG. 7G, a web substrate 76 is formed such that there are a plurality of frames 74. Each frame 74 is separated from another frame by a step-change 78. The step-change 78 is consistently in the same direction from one frame 74 to the next frame 74. As can be seen, the step-change 78 is always higher on the left side than the right side of the step-change 78. FIG. 7H illustrates another example of a consistent or uniform step-change between two frames of the web substrate 76. One advantage of the consistent step-change is that the flow of FSA slurry is not disrupted by the step-changes 78 unexpectedly and thus, the FSA process can be more controlled. A template used to create the recessed regions may incorporate a feature that can create such a step-change in the substrate.
In some embodiments, instead of using a template and a step-and-repeat process to create recessed regions or holes, a roller or a drum 54 with protruding structures 55 is used on a substrate 50 (FIGS. 7I-7M). The substrate 50 can be processed to form recessed regions thereon in a continuous process in which a roller passes across the substrate to form the recessed regions. A similar template to the template 51 can be created and coupled to a roller that can be used to form the recessed regions. A roller 54 may be comprised of sturdy materials (e.g., steel, polymers, aluminum, electroformed nickel, machined copper, rubber, etc.). FIG. 7I shows a roller 54 with the protruding structures 55. FIG. 7J shows a substrate 50 without recessed regions or holes. FIG. 7K shows the roller 54 contacting the substrate 50 in a manner that the protruding structures 55 pressing into the substrate 50. FIGS. 7L-7M show the roller 54 moving across the substrate 50. Recessed regions or holes 53 are created in the substrate 50 after the protruding structures 55 on the roller 54 pierce the substrate 50 and then are removed from the substrate 50 as the roller 54 moves across the substrate 50. It should be noted that a roller includes a web wheel, a drum, or a supported belt.
The substrate 50 can be a sheet substrate or a web substrate as previously mentioned. The roller 54 may be placed so that the roller 54 rolls or moves across and on top of the substrate 50. Alternatively, the roller 54 may be placed so that the roller 54 rolls or moves across and on the bottom of the substrate 50. The substrate 50 may be comprised of polyether sulfone (PES), polysulfone, polyether imide, polyethylene terephthalate, polycarbonate, polybutylene terephthalate, polyphenylene sulfide (PPS), polypropylene, polyester, aramid, polyamide-imide (PAI), polyimide, nylon material (e.g. polyamide), aromatic polyimides, polyetherimide, polyvinyl chloride, acrylonitrile butadiene styrene (ABS), or metallic materials. Additionally, the substrate 50 when in a web process can be a flexible sheet with very high aspect ratios such as 25:1 or more (length:width). As is known, a web material involves a roll process. For example, a roll of paper towels when unrolled is said to be in web form and it is fabricated in a process referred to as a web process. When a web is coiled, it is in roll form.
FIG. 8 shows an overall process of fabricating an electronic assembly in according to embodiments of the present invention. Although the discussion below illustrates processes that may be continuous, other separate or sub-processes can also be used. For instance, a process that is continuous as shown in FIG. 8 can be separated into separate or sub-processes. The process in FIG. 8 can take place on one machine or on several machines.
FIG. 8 illustrates a web process where a web substrate is used for forming a plurality of electronic assemblies such as the assembly 200 or 400 previously described. A roll of substrate 120 is provided. The substrate 120 is flexible. The substrate 120 may be sprocket-hole-punched to assist in web handling. The substrate 120 is advanced from a station 117 or a roller 117 to a station 119 that forms a plurality of recessed regions as previously described. The recessed regions can be formed by machining, etching, casting, embossing, extruding, stamping, or molding. In one embodiment, a roller such as the roller 54 as previously described with protruding structures is provided for the formation of the recessed regions. The substrate 120 is advanced through a set of support members 122 as the recessed regions are created into the substrate 120. An fluid self-assembly process can be used to deposit a plurality of functional blocks into the recessed regions formed in the substrate. In one embodiment, a first slurry 124 containing a plurality of functional blocks is dispensed onto the substrate 120. A second slurry 126 containing a plurality of functional blocks may also be used to dispense onto the substrate 120. Excess slurry is collected in container 128 and is recycled. The functional blocks fall into the recessed regions in the substrate. The substrate 120 is then advanced to another set of support members 130. An inspection station (not shown) may be provided to check for empty recessed regions or for improperly filled recessed regions. There may also be a clearing device (not shown) to remove excess functional blocks or blocks not completely seated or deposited into the recessed regions of the substrate 120. A vibration device (not shown) may be coupled to the substrate 120 and/or to the slurry dispensing device to facilitate the distribution and/or of the functional blocks. An example of a dispensing device that can work with vibrational assistance to dispense the functional blocks is described in U.S. patent application Ser. No. 10/086,491, entitled “Method and Apparatus For Moving Blocks” filed on Feb. 28, 2002, which is hereby incorporated by reference in its entirety. In one embodiment, the functional blocks are deposited onto the substrate material using methods described in U.S. patent application Ser. No. 10/086,491. In one embodiment, the functional blocks are deposited onto the substrate using fluidic self-assembly process on a continuously moving web (the substrate 120).
The functional blocks can have shapes such as square, rectangular, trapezoid, cylinder, asymmetric block, asymmetric rectangular, and asymmetric trapezoid. The recessed regions have similar shapes as the functional blocks.
Continuing with FIG. 8, and generally shown at 132, a planarization (or dielectric) layer is then deposited or laminated or otherwise formed onto the substrate material. Vias are formed in the dielectric film. The dielectric layer can be applied using a variety of methods. Most commonly, a solid dielectric film is used, which can be applied with a hot roll laminator. Alternatively, a liquid dielectric could be applied by spin coating in sheet form using any variety of a printing methods, such as direct writing, laser-assisted deposition, screen printing, or wet coating (e.g., by comma coating or other types of roll-to-roll liquid coaters). A liquid dielectric could either be dried or cured to form a solid dielectric layer. Curing could be thermally-activated, moisture-activated, microwave-activated, or UV light-activated. The dielectric layer can be cured or dried in-line as the layer is being formed. In one embodiment, the dielectric film is formed by direct write techniques. In one embodiment, the deposition of the functional blocks by FSA and the formation of the dielectric film are done on the same machine. In one embodiment, the dielectric film is formed over the functional blocks using the continuously moving web (the substrate 120). In one embodiment, the dielectric layer is selectively applied in only specific locations, e.g., on the substrate areas with the functional blocks and/or over certain area of the functional blocks. In the embodiment where the dielectric layer is selectively deposited, it may assist in adhering the functional blocks in the recesses, and it may not be necessary to form vias.
In one embodiment, to form the vias that can expose the contact pads on the functional blocks, the substrate with the functional blocks deposited therein is inspected by an optical scanner (not shown) prior to via formation to determine the location of the contact pads on the functional blocks that need vias over them. Preferably, this inspection is done in-line with the via formation process, and the image analysis is done automatically by a computerized vision system (not shown), and the results are sent directly to the via formation apparatus to select which vias to form. As a result, vias are only formed in the dielectric above the contact pads of the functional blocks. Alternatively, vias can be drilled in arbitrary positions relative to the functional block position, which will open functional and non-functional vias.
The via opening(s) in the dielectric layer can be opened either before or after the dielectric film is placed on the functional blocks-filled substrate. The openings could be punched prior to dielectric layer application to the filled substrate web, or could be created by etching, photolithography, or by laser via drilling after the dielectric film is deposited over the substrate. Laser drilling can be used to form the vias, which could be accomplished with either a UV, visible, or IR laser. In one embodiment, a UV-laser is used to form the via openings in the dielectric layer. Laser via drilling can be accomplished with either a long pulse of energy, or a series of short pulses. In the case of a series of short pulses, the position of the laser can be adjusted so that one or more pulses occur in different positions within each via. A via with a wider, non-circular opening can be created by laser drilling partially through the dielectric film. The vias could also be self-forming in liquid systems that, after application to the functional block-filled substrate web, selectively de-wet off of the contact pads on the functional blocks.
In one embodiment, the substrate 120 is held flat on a chuck, scanned, and then drilled to form a group of vias prior to indexing forward so that another section of the substrate 120 can be treated. The scanning (e.g., optical scanning) and the via drilling may also occur on a moving web when the substrate 120 is moving or moving continuously.
Conductive interconnects are then formed into and on the dielectric film. In one embodiment, the conductive interconnects are formed in a continuously moving web. The conductive interconnects also fill the vias to allow electrical interconnection to the functional blocks. In one embodiment, the vias are filled with a conductive material to form a via conductors. A pad conductor is then formed on the dielectric film to interconnect to each via conductor. Each pad conductor and via conductor can form a conductive interconnect and/or be made of the same materials and in one process in many embodiments. The via conductors and the pad conductors can be formed on a continuously moving web of the substrate 120. The planarization and the conductive interconnect formation are generally shown at 132 in FIG. 8.
In one embodiment, residues in the vias are removed prior to filling the vias. The cleaning step can be accomplished by treatment with a detergent cleaning system, a water rinse system, an oxygen plasma system, a vacuum plasma system, an atmospheric plasma system, a brush scrubbing system, or a sand or solid carbon dioxide blasting system. The via can be filled with the conductive material using sputtering or evaporation across the entire substrate, followed by lithographic patterning of a mask and subsequent etching, to leave metal only around and in the via. The conductive material in the vias can be formed by any of a variety of conductive composite printing methods, including screen printing or gravure printing. In some embodiments, the conductive material in the vias is formed by a printing method. The conductive material is typically thermally-cured or UV-cured, or cured by air-drying. In other embodiments, the conductive materials in the vias are formed by a direct-write or an adaptive-wiring process. In the case of direct-write or adaptive wiring, the positioning of each individual conductive material in each via can be controlled by a machine vision system analogous to the system that is used to locate the position on the dielectric layer to form the vias openings.
Similar methods for forming the conductive material in the vias can be used to form the conductive interconnects on the dielectric film (also referred to as pad conductors) that couple to the via conductors. In some embodiments, the same conductive material is used to fill the via as well as forming the interconnects on the dielectric layer as previously described. In one embodiment, the interconnects are formed by metal sputtering or evaporation across the entire substrate 120, followed by lithographic patterning of a mask and subsequent etching, to leave metal only in the preferred pad conductor shape and in contact with the conductor in the vias. The via conductors and the pad conductors can be formed in one step as forming one continuous conductor.
The via conductors and the pad conductors can be made of one or more of the following: conductive particles dispersed in a nonconductive matrix (e.g., silver ink, sputtered/evaporated metal, conductive carbon composites, carbon nanotubes) or inorganic nanowires dispersed in a nonconductive matrix (e.g., a thermoplastic polymer, a thermoset polymer, or a B-staged thermoset polymer), or any of these materials combined with metallic nanoparticles. The via conductors and the pad conductors' materials are prepared so that they can be deposited on a continuously moving web.
A station 138 may be provided to inspect and/or test the functionality of the assemblies. The assemblies are tested for functionality such that known-bad assemblies can be marked, so that they can be actively avoided in future process steps. The assemblies can also be tested for features and strap assembly responses that determine whether a strap assembly is suitable or not suitable. Tests for the strap assemblies can also be arbitrary, and be configured to change depending on the end application or desired construction of the strap assemblies. Known-good assemblies can be marked, so that they can be actively selected in future process steps. Strap assemblies with partial functionality, or with intermediate levels of sensitivity, can also be marked for usage in less demanding applications. In this way, the assemblies can be sorted by functionality and future deployment. For example, assemblies with reduced sensitivity may be sorted and used with antennas and/or in applications where high sensitivity is not required. In one embodiment, a code may be written onto the particular assembly or assemblies. The code may be used to indicate the results of a test, the type of a test, be related to a security feature, or indicate other information useful in subsequent fabrication or deployment of the assemblies. The mark can be an ink mark, ink jet marking, stamping, or a laser burn mark, or any other mark that is detectable by either a human eye, a sensor, or both. In one embodiment, the marking is a laser marking and is applied to the particular pad conductors so as to leave a black mark on the pad conductors. In one embodiment, the tests are done by coupling the electromagnetic energy from the tester to the assemblies. The coupling can be resistive, inductive, or capacitive, or a combination thereof, using contact methods (e.g., direct electrical contact), non-contact methods, or a combination thereof. Even in a densely-packed set of straps, individual assemblies can be tested without undue interference from neighboring devices. In one embodiment, individual assemblies are tested based on a predefined set of criteria or parameters, for instance, one assembly out of every 10 assemblies formed on a web is tested. Other criteria or parameters are of course possible. After the testing, the substrate 120 is further advanced to another set of support members 134 for subsequent processing or lamination processes. In one embodiment, an additional conductive trace is formed on the substrate 120 to interconnect to the conductive interconnect. The conductive trace may be an antenna trace or other conductive element for an external electrical element. The conductive trace may be formed by a convenient method such as printing, laminating, deposition, etc. A roll of material 136 is shown to laminate to the substrate 120. The material from the roll 136 can be a cover a jacket or other suitable material for subsequent processing or for completing the assemblies. In one embodiment, the roll 136 is a device substrate having formed thereon a conductor pattern. The substrate 120 having the functional blocks deposited therein and other elements formed therein/thereon is attached to the substrate from the roll 136 such that the conductive interconnects are coupled to the conductor pattern. In one embodiment, the substrate assemblies after processed as shown in FIG. 8 are singulated or cut to form individual assemblies such as assemblies 200 or 400.
FIG. 9 illustrates another overall process of fabricating an electronic assembly in according to embodiments of the present invention. This process is similar to the one described in FIG. 8 except that the recessed regions on the substrate 120 are formed using a step-and-repeat process. The process in FIG. 9 can be a continuous process as illustrated or can be separated into one or more separate or sub-processes. The process in FIG. 9 can take place on one machine or on several machines.
Similar to FIG. 8, in FIG. 9, a roll of substrate 120 is provided. The substrate 120 material is flexible. The substrate 120 may be sprocket-hole-punched to assist in web handling. The substrate 120 is advanced from the roll 117 to a station 119 that forms a plurality of recessed regions as previously described. In one embodiment, a vertical hot press 121 is provided with a template such as the template 51 previously described for the formation of the recessed regions. The substrate 120 is advanced through a set of support members 122 as the recessed regions are created into the substrate 120. A first slurry 124 containing a plurality of functional blocks is dispensed onto the substrate 120. A second slurry 126 containing a plurality of functional blocks may also be used to dispense onto the substrate 120. Excess slurry is collected in a container 128 and is recycled. The functional blocks fall into the recessed regions in the substrate 120. The substrate 120 is advanced to another set of support members 130. An inspection station (not shown) may be provided to check for empty recessed regions or for improperly filled recessed regions. There may also be clearing device (not shown) to remove excess functional blocks or blocks not completely seated or deposited into the recessed regions off the substrate 120. A vibration device (not shown) may be coupled to the substrate 120 and/or to the slurry dispensing device to facilitate the distribution and/or deposition of the functional blocks. An example of a dispensing device that can work with vibrational assistance to dispense the functional blocks is described in U.S. patent application Ser. No. 10/086,491, entitled “Method and Apparatus For Moving Blocks” filed on Feb. 28, 2002, which is hereby incorporated by reference in its entirety. In one embodiment, the functional blocks are deposited onto the substrate using methods described in U.S. patent application Ser. No. 10/086,491.
Continuing with FIG. 9, and generally shown at 132 a planarization (or dielectric) layer is then deposited or laminated onto the substrate 120 similar to previously discussed. Vias are formed in the dielectric film. Conductive interconnects are then formed on the dielectric film. The conductive interconnects also fill the vias to allow electrical interconnection to the functional blocks. In one embodiment, the vias are filled with a conductive material referred to as a via conductor. A pad conductor is then formed on the dielectric film to interconnect to the via conductor. The pad conductor and the via conductor can form the conductive interconnect in many embodiments. The planarization and the conductive interconnect formation is generally shown at 132 in FIG. 9. A station 138 may be provided to inspect and/or test the functionality of the assemblies as previously described. After the testing, the substrate 120 is further advanced to another set of support members 134 for subsequent processing or lamination processed. In one embodiment, a conductive trace is formed on the substrate 120 to interconnect to the conductive interconnect. The conductive trace may be an antenna trace or other conductive element. The conductive trace may be formed by a convenient method such as printing, laminating, deposition, etc. A roll of material 136 is shown to laminate to the substrate 120. The material can be a cover a jacket or other suitable material to complete the assemblies. In one embodiment, the roll 136 is a device substrate having formed thereon a conductor pattern. The substrate 120 with the functional blocks deposited therein and other elements formed therein/thereon is attached to the substrate roll 136 such that the conductive interconnects are coupled to the conductor pattern. In one embodiment, the substrate assemblies after processed as shown in FIG. 9 are singulated or cut to form individual assemblies such as assemblies 200 or 400.
In one embodiment, a roll of substrate with recessed regions formed therein is formed by joining several sheets of materials together as illustrated in FIGS. 10-11. In many instances, a number of certain predefined sections of the substrate are formed, for example, using a template such as the template 51 previously described. These sections of substrate with the recessed regions formed therein are then spliced, welded, or otherwise attached to one another to form a long section or a roll of substrate. As shown in FIG. 10, frame 1002, 1004, and 1006 are formed. The frame 1002 is formed with a piece of substrate 1008 with a predetermined dimension. Likewise, the frame 1004 are 1006 are also formed with a piece of substrate 1010 and 1012, respectively. Recessed regions 1014 are created into each of the substrates 1008, 1010, and 1012. Then, as shown in FIG. 11, the frames 1002, 1004, and 1006 are welded together to form a long piece of substrate 1020 or a roll of substrate 1020. Between each two frames, a step-change is formed. For example, between the frame 1002 and 1004 is a step-change 1022 and between the frame 1004 and 1006 is a step-change 1024. In the present embodiment, the frames can be attached together such that the step-changes are uniform and consistent from one frame to the next. The present embodiment allows one to control the direction of the step-changes for the benefits previously discussed.
After the substrate 1020 is formed, the substrate 1020 may be rolled up into a roll form and placed on a web line processing similar to those processes described in FIGS. 8-9 to deposit the functional blocks and form other elements on the substrate. As can be seen in FIG. 12, the substrate 1020 is advanced from a roller 117 through a set of support members 122. A first slurry 124 containing a plurality of functional blocks is dispensed onto the substrate 1020. A second slurry 126 containing a plurality of functional blocks may also be used to dispense onto the substrate 1020. Excess slurry is collected in a container 128 and is recycled. The functional blocks fall into the recessed regions in the substrate 1020. The substrate 1020 is advanced to another set of support members 130. An inspection station (not shown) may be provided to check for empty recessed regions or for improperly filled recessed regions. There may also be a clearing device (not shown) to remove excess functional blocks or blocks not completely seated or deposited into the recessed regions off the substrate 1020. A vibration device (not shown) may be coupled to the substrate 1020 and/or to the slurry dispensing device to facilitate the distribution and/or deposition of the functional blocks. An example of a dispensing device that can work with vibrational assistance to dispense the functional blocks is described in U.S. patent application Ser. No. 10/086,491, entitled “Method and Apparatus For Moving Blocks” filed on Feb. 28, 2002, which is hereby incorporated in its entirety. In one embodiment, the functional blocks are deposited onto the substrate using methods described in U.S. patent application Ser. No. 10/086,491.
A planarization (or dielectric) layer is then deposited or laminated onto the substrate 1020. Vias are formed in the dielectric film. Conductive interconnects are then formed on the dielectric film. The conductive interconnects also fill the vias to allow electrical interconnection to the functional blocks. In one embodiment, the vias are filled with a conductive material referred to as a via conductor. A pad conductor is then formed on the dielectric film to interconnect to the via conductor. The pad conductor and the via conductor can form the conductive interconnects in many embodiments. The planarization and the conductive interconnect formation is generally shown at 132 in FIG. 12. A station 138 may be provided to inspect and/or test the functionality of the assemblies as previously described. The substrate 1020 is further advanced to another set of support members 134 for subsequent processing or lamination processed. In one embodiment, a conductive trace is formed on the substrate 1020 to interconnect to the conductive interconnect. The conductive trace may be an antenna trace or other conductive element. The conductive trace may be formed by a convenient method such as printing, laminating, deposition, methods of direct writing, etc. A roll of material 136 is shown to laminate to the substrate 1020. The material can be a cover, a jacket, or other suitable material to complete the assemblies. In one embodiment, the roll 136 is a device substrate having formed thereon a conductor pattern. The substrate 1020 having the functional blocks deposited therein and other elements formed therein/thereon is attached to the roll 136 such that the conductive interconnects are coupled to the conductor pattern. In one embodiment, the substrate assemblies after processed as shown in FIG. 12 are singulated or cut to form individual assemblies such as assemblies 200 or 400. Similar to previously discussed, the process illustrated in FIG. 12 can occur on one machine or on several machines. Additionally, the process illustrated in FIG. 12 can also be separated into one or more sub-processes as opposed to be continuous as shown in this figure.
FIG. 13 illustrates an exemplary method 1300 of forming an electronic assembly in accordance to embodiments of the present invention. At box 1302, a plurality of recessed regions are formed on a substrate. At box 1304, a plurality of functional blocks is deposited into the recessed regions. Each of the functional blocks is deposited in one of the recessed regions. A substantial amount of the plurality of functional blocks are recessed below a top surface of said substrate. As mentioned above, substantial amount is defined by (1) less than 10% of the plurality of the functional blocks protrudes above the top surface of the substrate, (2) less than 1% of the plurality of the functional blocks protrudes above the top surface of the substrate, (3) more than 90% of the plurality of the functional blocks are recessed below the top surface of the substrate, or (4) more than 99% of the plurality of the functional blocks are recessed below the top surface of the substrate.
In one embodiment, each of the recessed regions has a first width-depth aspect ratio and each of the functional blocks has a second width-depth aspect ratio. The first width-depth aspect ratio substantially matches the second width-depth aspect ratio. The first width-depth aspect ratio is one of equal to or less than 10.5:1, or preferably equal to or less than 7.5:1.
A step-and-repeat process can be used to form the recessed regions as previously described. In such process, one area of the substrate is formed with the plurality of recessed regions at a time. In one embodiment, the material web that is used for the substrate is passed under a vertical hot press wherein a mold is attached thereto to form the plurality of recessed regions. At least one area of the substrate is formed with the plurality of recessed regions each time the substrate passes the vertical hot press.
In another embodiment, a continuous process is used to form the recessed regions as previously described. In one embodiment, a material that is used to form the substrate is extruded to form the substrate and while extruding, the plurality of recessed regions are formed into the substrate. In the present embodiment, materials used to form or extrude the substrate such as polymer pellets are heated and extruded to form a melted film. A roller or a template with features provided to form the recessed regions is brought into contact with the melted film. The recessed regions are thus formed into the substrate while it is being extruded.
At box 1306, a dielectric layer is formed over the functional blocks and/or the substrate. At box 1308, vias are created into the dielectric layer to allow contact to the functional blocks or the contact pads on the functional blocks as previously described. At box 1310, conductive interconnects are formed in the vias and over the dielectric layer as previously described to form via conductors and pad conductors.
FIGS. 14A-14B illustrates an exemplary method 1400 of forming an electronic assembly in accordance to embodiments of the present invention. The method 1400 is similar to the method 1300 described above with the addition of using copies of an embossing mold to form the recessed regions. At box 1402, a master mold is formed. The master mold comprises an etched silicon wafer and/or a diamond turning machined metal plate. At box 1404, a mother copy mold from the master mold is formed. In the case of a female silicon wafer master, which has receptors rather than embossing features, a father copy mold is made first, and the mother copy mold is made from the father copy mold. At box 1406, a stamper copy mold from the mother copy mold is formed. At box 1408, the stamper copy mold is used to form each of the plurality of recessed regions on a substrate. Each of said master mold, the mother copy mold, the father copy mold and the stamper copy mold comprises feature dimensions provided for each of the plurality of recessed regions. The feature dimensions for each of the plurality of recessed regions are about 0.5-1.0% larger than a desired corresponding feature of each of the plurality of recessed regions. Typically each of the forming steps involves electroforming a nickel plate or shim, but other forming methods, such as molding or casting of metal or polymer are also possible.
In another embodiment, a master mold negative is formed from the master mold. A stamper copy mold or generated is then formed from the master mold negative. At box 1408, the stamper copy mold formed form the master mold negative is used to form each of the plurality of recessed regions.
In another embodiment, one or more stamper copy molds are formed. Each of the stamper copy mold comprises at least one feature for forming one of the plurality of recessed regions. The stamper copy molds are then welded together to form a mold having an array of the features for forming an array of the recessed regions. The features are then used to form an array of the plurality of recessed regions on the substrate.
At box 1410, a plurality of functional blocks is deposited into the recessed regions. Each of the functional blocks is deposited in one of the recessed regions. A substantial amount of the plurality of functional blocks are recessed below a top surface of said substrate. As mentioned above, substantial amount is defined by (1) less than 10% of the plurality of the functional blocks protrudes above the top surface of the substrate, (2) less than 1% of the plurality of the functional blocks protrudes above the top surface of the substrate, (3) more than 90% of the plurality of the functional blocks are recessed below the top surface of the substrate, or (4) more than 99% of the plurality of the functional blocks are recessed below the top surface of the substrate.
At box 1412, a dielectric layer is formed over the functional blocks and/or the substrate. At box 1414, vias are created into the dielectric layer to allow contact to the functional blocks or the contact pads on the functional blocks as previously described. At box 1416, conductive interconnects are formed in the vias and over the dielectric layer as previously described.
FIG. 15 illustrates another exemplary method 1500 of forming an electronic assembly in accordance to embodiments of the present invention. At box 1502, a plurality of sheets of substrates is provided. The sheets comprise of materials that are used for the substrates of a plurality of electronic assemblies. The sheets can be comprised of different, same, or similar materials from one another. The sheets can be differently treated or similarly treated from one another and/or intended for same of different devices. At box 1504, an array of the recessed regions are formed on each sheet. The sheets may all have same types of recessed regions or different types of recessed regions formed therein. At box 1506, the sheets are joined or welded together to form a continuous web of the substrate having formed therein the plurality of recessed regions.
In one embodiment, each of the recessed regions has a first width-depth aspect ratio and each of the functional blocks has a second width-depth aspect ratio. The first width-depth aspect ratio substantially matches the second width-depth aspect ratio. The first width-depth aspect ratio is one of equal to or less than 10.5:1, and optimally equal to or less than 7.5:1.
In one embodiment, a step-and-repeat process using an embossing mold is used to form the recessed regions as previously described. In the present embodiment, each sheet is formed with the plurality of recessed regions at a time. After the recessed regions are formed, the sheets are joined together.
In an alternative embodiment, the sheets are joined together prior to the formation of the recessed regions. Previous methods discussed can be used to form the recessed regions in the joined sheets.
As previously mentioned, when the sheets are joined together, each sheet may be referred to as a frame. Between two frames, there may be a step-change and that one step-change is consistent in direction of change with another step-change from one frame to the next frame (e.g., FIGS. 7G-7H).
At box 1508, a plurality of functional blocks is deposited into the recessed regions. Each of the functional blocks is deposited in one of the recessed regions. A substantial amount of the plurality of functional blocks are recessed below a top surface of said substrate. As mentioned above, substantial amount is defined by any (1) less than 10% of the plurality of the functional blocks protrudes above the top surface of the substrate, (2) less than 1% of the plurality of the functional blocks protrudes above the top surface of the substrate, (3) more than 90% of the plurality of the functional blocks are recessed below the top surface of the substrate, or (4) more than 99% of the plurality of the functional blocks are recessed below the top surface of the substrate.
At box 1510, a dielectric layer is formed over the functional blocks and/or the substrate. At box 1512, vias are created into the dielectric layer to allow contact to the functional blocks or the contact pads on the functional blocks as previously described. At box 1514, conductive interconnects are formed in the vias and over the dielectric layer as previously described.
In many of embodiments of the present invention, a functional block or functional blocks are deposited or placed into a receptor region or receptor regions using FSA. It is to be understood that FSA is only an exemplary method that can be used to deposit the functional blocks. The functional blocks can be deposited or placed in a substrate by other suitable methods such as pick-and-place or other methods that can embed the functional blocks into a substrate.
In many of embodiments of the present invention, a functional block or functional blocks are deposited or placed into a receptor region or receptor regions of a substrate where the blocks are essentially coplanar or nearly coplanar with a surface of the substrate. In some embodiments, no dielectric film layer is present above the functional block. In some embodiments, the functional block protrudes above the surface of the substrate. In such embodiments, the functional block that protrudes above the surface of the substrate may be configured to press into another electrical element on another surface such as an antenna of a device substrate. It is envisioned that the antenna material may be soft and pliable at attachment time so that a protruding functional block can be pressed into the antenna material.
While the invention has been described in terms of several embodiments, those of ordinary skill in the art will recognize that the invention is not limited to the embodiments described. The method and apparatus of the invention, but can be practiced with modification and alteration within the spirit and scope of the appended claims. The description is thus to be regarded as illustrative instead of limiting.
Having disclosed exemplary embodiments, modifications and variations may be made to the disclosed embodiments while remaining within the spirit and scope of the invention as defined by the appended claims.

## Claims

1. A method comprising:
forming a population of recessed regions on a substrate; and
depositing a population of functional blocks into said population of recessed regions; each of said functional blocks is deposited in one of said recessed regions, a substantial amount of said population of functional blocks are recessed below a top surface of said substrate, wherein said substantial amount is defined by any one of less than 10% of said population of functional blocks protrudes above said top surface of said substrate, or more than 90% of said population of functional blocks are recessed below said top surface of said substrate,
wherein said population of recessed regions are formed using a step-and-repeat process in which one area of said substrate is formed with said population of recessed regions at a time and wherein forming said population of recessed regions on said substrate further comprising:
forming a master mold, said master mold comprising silicon wafer with recessed regions similar in shape to said recessed regions to be formed on said substrate;
forming a male copy mold from said master mold;
forming a female copy mold from said male copy mold;
forming a stamper copy mold from said female copy mold; and
using said stamper copy mold to form each of said population of recessed regions;
wherein each of said master mold, said male copy mold, said female copy mold, and said stamper copy mold comprises feature dimensions provided for each of said population of recessed regions, said feature dimensions for each of said population of recessed regions are about 0.5-1.0% larger than a desired corresponding feature of each of said population of recessed regions.

2. A method comprising:
forming a population of recessed regions on a substrate; and
depositing a population of functional blocks into said population of recessed regions; each of said functional blocks is deposited in one of said recessed regions, a substantial amount of said population of functional blocks are recessed below a top surface of said substrate, wherein said substantial amount is defined by any one of less than 10% of said population of functional blocks protrudes above said to surface of said substrate, or more than 90% of said population of functional blocks are recessed below said top surface of said substrate,
wherein said population of recessed regions are formed using a step-and-repeat process in which one area of said substrate is formed with said population of recessed regions a time and wherein forming said population of recessed regions on said substrate further comprising:
forming a master mold, said master mold comprising silicon wafer and/or diamond turning machined metal substrate;
forming a master mold negative from said master mold;
forming a stamper copy mold from said master mold negative: and
using said stamper copy mold to form each of said population of recessed regions:
wherein each of said master mold, said mother copy mold, and said stamper copy mold comprises feature dimensions provided for each of said population of recessed regions, said feature dimensions for each of said population of recessed regions are about 0.5-1.0% larger than a desired corresponding feature of each of said population of recessed regions.

3. A method comprising:
forming a population of recessed regions on a substrate; and
depositing a population of functional blocks into said population of recessed regions; each of said functional blocks is deposited in one of said recessed regions, a substantial amount of said population of functional blocks are recessed below a top surface of said substrate, wherein said substantial amount is defined by any one of less than 10% of said population of functional blocks protrudes above said top surface of said substrate, or more than 90% of said population of functional blocks are recessed below said top surface of said substrate,
wherein said population of recessed regions are formed using a step-and-repeat process in which one area of said substrate is formed with said population of recessed regions at a time and wherein forming said population of recessed regions on said substrate further comprising:
forming one or more stamper copy molds, each of said stamper copy molds comprises at least one feature for forming one of said population of recessed regions;
coupling said stamper copy molds together to form a mold having an array of said features, said array of said features being used to form an array of said population of recessed regions on said substrate;
wherein each of said features has dimensions for one of said population of recessed regions, said dimensions are about 0.5-1.0% larger than desired dimensions for each of said corresponding recessed regions.